阅读说明：本技术 一种基于资源化利用的氢氧化镁生产装置及方法 (Magnesium hydroxide production device and method based on resource utilization ) 是由 王德喜 刘波 范丽华 崔玮琳 周士海 刘文涛 高倩楠 于 2021-09-30 设计创作，主要内容包括：本发明的一种基于资源化利用的氢氧化镁生产装置及方法,属于化工技术领域,所述装置包括打浆罐、空化反应器、蒸氨塔、蒸氨液闪蒸罐、卧式双鼓离心机、气雾沉镁塔、喷射反应器、沉镁液闪蒸罐、带式真空过滤机、高速混合机、流化床干燥器、气流粉碎机；空化反应器、喷射反应器、气雾沉镁塔、高速混合机强化了传热、传质；蒸氨、沉镁反应后经闪蒸回收二次水蒸汽为蒸氨反应提供辅助热源,干燥分离出的热空气为流化床干燥器空气预热器提供热源,喷射反应器出来的未反应氨气可为蒸氨塔提供辅助热源；节能效果明显,装置综合节能30％；氢氧化镁质量高于工业品国标。本发明工艺成熟,连续操作,自动化程度高,资源循环利用,环境友好。(The invention relates to a magnesium hydroxide production device and method based on resource utilization, belonging to the technical field of chemical industry, wherein the device comprises a beating tank, a cavitation reactor, an ammonia still flash tank, a horizontal double-drum centrifuge, an aerial fog magnesium precipitation tower, a jet reactor, a magnesium precipitation flash tank, a belt vacuum filter, a high-speed mixer, a fluidized bed dryer and a jet mill; the cavitation reactor, the jet reactor, the aerial fog magnesium precipitation tower and the high-speed mixer strengthen heat transfer and mass transfer; after ammonia distillation and magnesium precipitation reaction, recovering secondary water vapor through flash evaporation to provide an auxiliary heat source for the ammonia distillation reaction, drying and separating hot air to provide a heat source for an air preheater of a fluidized bed dryer, and spraying unreacted ammonia gas from a reactor to provide an auxiliary heat source for an ammonia distillation tower; the energy-saving effect is obvious, and the device can save energy by 30% comprehensively; the quality of the magnesium hydroxide is higher than the national standard of industrial products. The invention has the advantages of mature process, continuous operation, high automation degree, cyclic utilization of resources and environmental protection.)

1. The utility model provides a magnesium hydrate apparatus for producing based on resource utilization which characterized in that: a magnesium hydroxide production device based on resource utilization comprises a beating tank, a cavitation reactor, an ammonia evaporation liquid flash tank, a horizontal double-drum centrifuge, an aerial fog magnesium precipitation tower, a jet reactor, a magnesium precipitation liquid flash tank, a belt type vacuum filter, a high-speed mixer, a fluidized bed dryer and a jet mill which are connected in sequence; an ammonia still is arranged above the cavitation reactor; the pulping tank is used for preparing mixed slurry of MgO and ammonium salt; the cavitation reactor is used for the ammonia distillation reaction of the slurry; the ammonia evaporation liquid flash tank is used for carrying out flash evaporation on the ammonia evaporation liquid; the horizontal double-drum centrifuge is used for carrying out liquid-solid separation on the flash evaporation liquid; the aerial fog magnesium precipitation tower is used for atomizing the separated refined magnesium liquid and performing magnesium precipitation reaction with ammonia gas; the jet reactor is used for continuously carrying out magnesium precipitation reaction on the magnesium precipitation liquid and ammonia gas; the magnesium precipitation liquid flash tank is used for carrying out flash evaporation on the magnesium precipitation liquid; the belt type vacuum filter is used for carrying out liquid-solid separation on the flash evaporation liquid; the high-speed mixer is used for modifying the separated magnesium hydroxide; the fluidized bed dryer is used for drying the modified magnesium hydroxide; the jet mill is used for grinding and grading the dried magnesium hydroxide powder;

an ammonia gas reflux pipeline is arranged between the jet reactor and the ammonia still and used for conveying unreacted ammonia gas in the jet reactor to the bottom of the ammonia still; the cavitation reactor comprises a reactor body, and a tooth-shaped baffle is arranged on the inner wall of the reactor body; the outer wall of the reactor body is provided with a jacket, a hollow stirring heat transfer rotor is arranged in the reactor body, the lower part of the stirring heat transfer rotor is provided with an anchor type stirring paddle, and the outer wall of the stirring heat transfer rotor above the anchor type stirring paddle is provided with a plurality of layers of blades; the jet reactor adopts jet stirring and adopts jacket heat exchange; the cavitation reactor exchanges heat with the jacket through the stirring heat transfer rotor;

the device further comprises: the ammonia gas compressor has an input end and an output end which are respectively connected with an ammonia gas outlet at the top of the ammonia distillation tower and an ammonia gas buffer tank, the ammonia gas buffer tank is connected with the aerosol magnesium precipitation tower, the separated ammonia gas in the ammonia distillation tower enters the ammonia gas buffer tank after being compressed by the ammonia gas compressor, and the ammonia gas collected by the ammonia gas buffer tank enters the aerosol magnesium precipitation tower; the input end of the steam compressor is connected with the ammonia evaporation liquid flash tank and the magnesium deposition liquid flash tank, and the output end of the steam compressor is connected with the cavitation reactor; and low-pressure steam which is adiabatically flashed out from the ammonia evaporation liquid flash tank and the magnesium deposition liquid flash tank enters a steam compressor to be heated and pressurized to form secondary steam which is used as an auxiliary heat source of the cavitation reactor.

2. The magnesium hydroxide production device based on resource utilization according to claim 1, characterized in that: the device also comprises a cyclone separator, a bag filter and a fluidized air preheater, wherein the cyclone separator and the bag filter are used for carrying out gas-solid separation on hot air containing magnesium hydroxide discharged by the fluidized bed dryer, the separated magnesium hydroxide powder enters the jet mill, the fluidized air preheater preheats the fluidized air by taking the hot air separated by the cyclone separator and the bag filter as a heat source, and the preheated fluidized air enters the fluidized air heater for reheating and then enters the hot air fluidized material of the fluidized bed dryer.

3. The magnesium hydroxide production device based on resource utilization according to claim 2, characterized in that: the apparatus further includes a water vapor condensate tank I, II; the cavitation reactor uses secondary water vapor and water vapor as heat sources, the fluidized bed dryer and the fluidized air heater use the water vapor as the heat sources, the water vapor condensate tank I is used for collecting secondary water vapor condensate water generated by the cavitation reactor, the collected secondary water vapor condensate water is used for filter cake washing water of the horizontal double-drum centrifuge, the water vapor condensate tank II is used for collecting water vapor condensate water generated by a built-in discharge pipe of the fluidized bed dryer and the fluidized air heater, and the collected water vapor condensate water is used for the filter cake washing water of the belt type vacuum filter.

4. The magnesium hydroxide production device based on resource utilization according to claim 1, characterized in that: the device also comprises a mother liquor tank which is used for collecting the mother liquor filtered by the belt type vacuum filter, and the collected mother liquor enters the pulping tank after passing through a cooler at the upper section of the ammonia still to be used as the ingredient water of the pulping tank.

5. A method for producing magnesium hydroxide based on the device of any one of claims 1 to 4, characterized in that: the method specifically comprises the following steps:

(1) MgO and NH as raw materials₄NO₃Water enters a pulping tank and is stirred by a mechanical stirrer to be pulped;

(2) continuously feeding MgO slurry in a pulping tank into a cavitation reactor by gravity, and carrying out ammonia distillation reaction on the MgO slurry in the cavitation reactor; the cavitation reactor adopts secondary water vapor and water vapor to be heated through a stirring heat transfer rotor and a jacket; the liquid phase in the cavitation reactor enters an ammonia evaporation liquid flash tank through an ammonia evaporation liquid pump, and the gas phase in the cavitation reactor enters an ammonia evaporation tower;

(3) the gas phase in the cavitation reactor enters an ammonia still and ammonia water and steam from an injection reactor, the ammonia water and the steam are separated in the ammonia still, the ammonia gas enters an ammonia gas compressor after demisting, and the compressed ammonia gas enters an aerosol magnesium precipitation tower through an ammonia gas buffer tank;

(4) liquid phase in the cavitation reactor enters an ammonia evaporation liquid flash tank through an ammonia evaporation liquid pump, low-pressure water vapor is flashed out in an adiabatic manner, and the water vapor enters a water vapor compressor to be heated and pressurized and then is used as secondary water vapor; feeding the flash evaporation liquid in the ammonia evaporation liquid flash evaporation tank into a horizontal double-drum centrifuge by gravity;

(5) feeding the flash evaporation liquid in the ammonia evaporation liquid flash evaporation tank into a horizontal double-drum centrifuge for liquid-solid separation by gravity; the separated refined magnesium liquid enters a refined magnesium liquid tank and continuously enters an aerosol magnesium precipitation tower through a refined magnesium liquid pump;

(6) the refined magnesium liquid continuously enters an aerosol magnesium precipitation tower, and the atomized refined magnesium liquid and ammonia gas entering from the bottom of the tower are subjected to magnesium precipitation reaction; discharging unreacted ammonia gas out of the tower through a demister, allowing the ammonia gas to enter a coupler of the injection reactor, and allowing magnesium precipitation liquid to enter the liquid level in the injection reactor through a liquid seal pipe;

(7) the magnesium deposition liquid in the injection reactor enters the coupler through the power fluid pump part of the injection reactor, continues to perform magnesium deposition reaction through the injector and ammonia gas, and partially enters the magnesium deposition liquid flash tank; injecting unreacted ammonia and water vapor in the reactor into the bottom of the ammonia still;

(8) the precipitated magnesium liquid enters a precipitated magnesium liquid flash tank, low-pressure steam is flashed out in an adiabatic manner, and the steam enters a steam compressor to be used as secondary steam after being heated and pressurized; the flash liquid in the magnesium precipitation flash tank enters a belt type vacuum filter through gravity;

(9) the flash liquid in the magnesium precipitation flash tank enters a belt type vacuum filter for liquid-solid separation through gravity; the separated magnesium hydroxide filter cake enters a high-speed mixer;

(10) continuously feeding the magnesium hydroxide filter cake separated by the belt type vacuum filter into a high-speed mixer, adding an auxiliary agent, and stirring to modify the magnesium hydroxide filter cake; the modified magnesium hydroxide of the high-speed mixer enters a fluidized bed dryer;

(11) continuously feeding the modified magnesium hydroxide in the high-speed mixer into a fluidized bed dryer through a blanking machine of the high-speed mixer; hot air containing magnesium hydroxide and discharged by the fluidized bed dryer is used for separating gas and solid through a cyclone separator and a bag filter;

(12) and (3) separating gas from solid by using magnesium hydroxide powder from a fluidized bed dryer, a cyclone separator and a bag filter, continuously feeding the magnesium hydroxide powder into a jet mill for grinding and grading, separating the gas from the solid by using the cyclone separator and the bag filter, and feeding the magnesium hydroxide powder into a magnesium hydroxide powder bin.

6. The method for producing magnesium hydroxide according to claim 5, characterized in that: the raw materials of MgO light burning powder and solid NH are added into the pulping tank in the step (1)₄NO₃Mother liquor recovered by the belt type vacuum filter continuously enters a pulping tank through preheating, and is stirred by a mechanical stirrer for pulping; MgO slurry solid content is 3.5% -4.5% by MgO, MgO and NH₄NO₃The molar ratio is 1: (2.58-2.68); the temperature in the pulping tank is 50-55 ℃, the pressure is normal pressure, and the retention time of the materials is 2-2.5 h.

7. The method for producing magnesium hydroxide according to claim 5, characterized in that: and (2) continuously feeding MgO slurry in the pulping tank 1 into a cavitation reactor by gravity, wherein the MgO slurry is subjected to ammonia evaporation reaction in the cavitation reactor, the temperature in the cavitation reactor is 105-110 ℃, the pressure in the cavitation reactor is 0.12-0.14 MPa, the rotating speed of a stirring heat transfer rotor of the cavitation reactor is 1000-1100 rpm, and the retention time of the material is 2-2.5 h.

8. The method for producing magnesium hydroxide according to claim 5, characterized in that: the temperature of the top of the ammonia still 3 in the step (3) is 50-60 ℃, and the pressure is normal pressure; the adiabatic flash evaporation temperature of the ammonia evaporation flash tank in the step (4) and the magnesium deposition flash tank in the step (8) is 60-65 ℃, and the retention time of the materials is 1-1.5 h; the outer rotary drum of the horizontal double-drum centrifuge 5 in the step (5) is 2350rpm, the inner rotary drum is 2400rpm, the temperature of an impurity filter cake is 45-50 ℃, and the moisture content is 35-40%; the temperature of the top of the aerial fog magnesium precipitation tower in the step (6) is 80-90 ℃, the pressure is 0.15-0.16 MPa, the temperature of the bottom of the aerial fog magnesium precipitation tower is 120-130 ℃, and the pressure is 0.2-0.27 MPa.

9. The method for producing magnesium hydroxide according to claim 5, characterized in that: the temperature in the injection reactor in the step (7) is 110-115 ℃, the pressure is 0.143-0.169 MPa, and the retention time of the materials is 2-2.5 h; the pressure of the belt type vacuum filter 9 in the step (9) is 0.053MPa to 0.043MPa, the moisture content of the magnesium hydroxide filter cake is 45 percent to 50 percent (wet basis), the temperature of the magnesium hydroxide filter cake is 40 ℃ to 45 ℃, the temperature in the high-speed mixer in the step (10) is 80 ℃ to 85 ℃, the pressure is normal pressure, and the retention time of the materials is 1h to 1.5 h.

10. The method for producing magnesium hydroxide according to claim 5, characterized in that: in the step (11), a fluidized bed dryer is used for providing hot air for fluidized drying of the modified magnesium hydroxide particles by a fluidized air heater; the built-in heating inner discharge pipe provides main drying heat, the temperature in the fluidized bed dryer is 185-195 ℃, and the retention time of the materials is 0.75-1 h; the temperature of the magnesium hydroxide powder leaving the fluidized bed dryer is 80-85 ℃, the temperature of the drying waste gas leaving the fluidized air preheater is 70-75 ℃, and the particle size of the magnesium hydroxide ground and classified by the jet mill in the step (12) is less than 2 μm.

Technical Field

The invention belongs to the technical field of chemical industry, and particularly relates to a magnesium hydroxide production device and method based on resource utilization.

Background

The industrial production method of magnesium hydroxide generally adopts ammonia method and caustic soda method, etc., and mainly adopts ammonia method to prepare magnesium hydroxide. The main raw materials are light calcined powder, brine and the like, and if the raw materials are not properly treated, the crystal form of magnesium hydroxide is affected, and the quality of the magnesium hydroxide is further affected. The preparation process of the magnesium hydroxide generally adopts a kettle type reactor and mechanical stirring, and the preparation equipment has the defects of low heat transfer and mass transfer efficiency; the reaction period is long, the energy consumption is high, the cost is increased due to the increase of the energy consumption, and the industrial production is not facilitated. The novel equipment is adopted to prepare magnesium hydroxide from light burning powder and ammonium nitrate through ammonia evaporation reaction and magnesium precipitation reaction, and then the high-quality magnesium hydroxide is produced through a one-step method through chemically modifying the magnesium hydroxide.

The art is eagerly looking for a low energy consumption and environment-friendly process for preparing magnesium hydroxide, which can overcome the above technical problems.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide a magnesium hydroxide production device and method based on resource utilization.

Aiming at the engineering problems and the market demand and aiming at overcoming the problems in the prior art, the invention provides a process which is simple, continuous in operation, high in automation degree, cyclic in resource utilization and environment-friendly, and simultaneously adopts advanced equipment such as a cavitation reactor, a jet reactor, an ammonia still, an aerosol magnesium precipitation tower and an MVR; the cavitation reactor and the jet reactor are adopted to directly replace a mechanical stirring kettle type reactor, the safety and the energy conservation are realized, the reasonable utilization of resources in the magnesium hydroxide preparation process is realized, the residual heat in the drying process is recovered, the heat in the ammonia distillation and magnesium precipitation reaction process is recovered by adopting the MVR technology, and the energy consumption is greatly reduced.

In order to achieve the purpose, the invention adopts the following technical scheme:

a magnesium hydroxide production device based on resource utilization comprises a beating tank, a cavitation reactor, an ammonia evaporation liquid flash tank, a horizontal double-drum centrifuge, an aerial fog magnesium precipitation tower, a jet reactor, a magnesium precipitation liquid flash tank, a belt type vacuum filter, a high-speed mixer, a fluidized bed dryer and a jet mill which are connected in sequence; an ammonia still is arranged above the cavitation reactor; the pulping tank is used for preparing mixed slurry of MgO and ammonium salt; the cavitation reactor is used for the ammonia distillation reaction of the slurry; the ammonia evaporation liquid flash tank is used for carrying out flash evaporation on the ammonia evaporation liquid; the horizontal double-drum centrifuge is used for carrying out liquid-solid separation on the flash evaporation liquid; the aerial fog magnesium precipitation tower is used for atomizing the separated refined magnesium liquid and performing magnesium precipitation reaction with ammonia gas; the jet reactor is used for continuously carrying out magnesium precipitation reaction on the magnesium precipitation liquid and ammonia gas; the magnesium precipitation liquid flash tank is used for carrying out flash evaporation on the magnesium precipitation liquid; the belt type vacuum filter is used for carrying out liquid-solid separation on the flash evaporation liquid; the high-speed mixer is used for modifying the separated magnesium hydroxide; the fluidized bed dryer is used for drying the modified magnesium hydroxide; the jet mill is used for grinding and grading the dried magnesium hydroxide powder;

an ammonia gas reflux pipeline is arranged between the jet reactor and the ammonia still and used for conveying unreacted ammonia gas in the jet reactor to the bottom of the ammonia still;

the cavitation reactor comprises a reactor body, wherein a tooth-shaped baffle is arranged on the inner wall of the reactor body, a jacket is arranged on the outer wall of the reactor body, a hollow stirring heat transfer rotor is arranged in the reactor body, an anchor type stirring paddle is arranged at the lower part of the stirring heat transfer rotor, and a plurality of layers of blades are arranged on the outer wall of the stirring heat transfer rotor above the anchor type stirring paddle;

the jet reactor adopts jet stirring and adopts jacket heat exchange; the cavitation reactor exchanges heat through the stirring heat transfer rotor and the jacket.

Further, the apparatus further comprises: the ammonia gas compressor has an input end and an output end which are respectively connected with an ammonia gas outlet at the top of the ammonia distillation tower and an ammonia gas buffer tank, the ammonia gas buffer tank is connected with the aerosol magnesium precipitation tower, the separated ammonia gas in the ammonia distillation tower enters the ammonia gas buffer tank after being compressed by the ammonia gas compressor, and the ammonia gas collected by the ammonia gas buffer tank enters the aerosol magnesium precipitation tower; the input end of the steam compressor is connected with the ammonia evaporation liquid flash tank and the magnesium deposition liquid flash tank, and the output end of the steam compressor is connected with the cavitation reactor; and low-pressure steam which is adiabatically flashed out from the ammonia evaporation liquid flash tank and the magnesium deposition liquid flash tank enters a steam compressor to be heated and pressurized to form secondary steam which is used as an auxiliary heat source of the cavitation reactor.

Furthermore, the multiple layers of blades are 45-degree 12-blade turbine blades uniformly distributed on the stirring heat transfer rotor, and the blades of each layer are staggered with the teeth of the toothed baffle in the horizontal direction; the tooth-shaped baffles are four and are symmetrically arranged on the inner wall of the reactor body at intervals of 90 degrees.

Furthermore, the aerial fog magnesium precipitation tower comprises two refined magnesium liquid atomizers which are respectively arranged at the upper part and the lower part in the tower, a demister is also arranged above the refined magnesium liquid atomizer at the upper part, and the refined magnesium liquid atomizer at the lower part is arranged above the ammonia gas inlet at the bottom; the device also comprises a liquid seal pipe, wherein the liquid seal pipe is used for conveying the magnesium precipitation liquid in the aerial fog magnesium precipitation tower to a position below the liquid level in the jet reactor.

The device further comprises a cyclone separator, a bag filter and a fluidized air preheater, wherein the cyclone separator and the bag filter are used for carrying out gas-solid separation on hot air containing magnesium hydroxide discharged by the fluidized bed dryer, the separated magnesium hydroxide powder enters the jet mill, and the fluidized air preheater preheats the fluidized air by taking the hot air separated by the cyclone separator and the bag filter as a heat source; the preheated fluidizing air enters a fluidizing air heater to be heated again and then enters a fluidized bed dryer to fluidize the material by hot air.

Furthermore, the device also comprises a water vapor condensation water tank I, II, the cavitation reactor takes secondary water vapor and water vapor as heat sources, and the fluidized bed dryer and the fluidized air heater take water vapor as heat sources; the water vapor condensate tank I is used for collecting secondary water vapor condensate generated by the cavitation reactor, and the collected secondary water vapor condensate is used for filter cake washing water of the horizontal double-drum centrifuge; and the water vapor condensate tank II is used for collecting water vapor condensate generated by a built-in calandria heater and a fluidized air heater of the fluidized bed dryer, and the collected water vapor condensate is used for filter cake washing water of the vacuum filter.

Further, the device also comprises a mother liquor tank which is used for collecting the mother liquor filtered by the belt type vacuum filter, and the collected mother liquor enters the pulping tank after passing through a cooler at the upper section of the ammonia still to be used as the batching water of the pulping tank.

A magnesium hydroxide production method based on the device specifically comprises the following steps:

(1) MgO and NH as raw materials₄NO₃Continuously feeding water into a pulping tank, and pulping under the stirring of a mechanical stirrer;

(2) continuously feeding MgO slurry in a pulping tank into a cavitation reactor by gravity, and carrying out ammonia distillation reaction on the MgO slurry in the cavitation reactor; the cavitation reactor adopts secondary water vapor and water vapor to be introduced into the stirring heat transfer rotor and the jacket for heating; the liquid phase in the cavitation reactor enters an ammonia evaporation liquid flash tank through an ammonia evaporation liquid pump, and the gas phase in the cavitation reactor enters an ammonia evaporation tower;

(3) the gas phase in the cavitation reactor enters an ammonia still to be mixed with ammonia gas and water vapor from an injection reactor, the ammonia gas and the water vapor are separated in the ammonia still, the ammonia gas enters an ammonia gas compressor after demisting, and the compressed ammonia gas enters an aerosol magnesium precipitation tower through an ammonia gas buffer tank;

(4) liquid phase in the cavitation reactor enters an ammonia evaporation liquid flash tank through an ammonia evaporation liquid pump, low-pressure water vapor is flashed out in an adiabatic manner, and the water vapor enters a water vapor compressor to be heated and pressurized and then is used as secondary water vapor; feeding the flash evaporation liquid in the ammonia evaporation liquid flash evaporation tank into a horizontal double-drum centrifuge by gravity;

(5) feeding the flash evaporation liquid in the ammonia evaporation liquid flash evaporation tank into a horizontal double-drum centrifuge for liquid-solid separation by gravity; the separated refined magnesium liquid enters a refined magnesium liquid tank and continuously enters an aerosol magnesium precipitation tower through a refined magnesium liquid pump;

(6) the refined magnesium liquid continuously enters an aerosol magnesium precipitation tower, and the atomized refined magnesium liquid and ammonia gas entering from the bottom of the tower are subjected to magnesium precipitation reaction; discharging unreacted ammonia gas out of the tower through a demister, allowing the ammonia gas to enter a coupler of the injection reactor, and allowing magnesium precipitation liquid to enter the liquid level in the injection reactor through a liquid seal pipe;

(7) the magnesium deposition liquid in the injection reactor enters the coupler through the power fluid pump part of the injection reactor, continues to perform magnesium deposition reaction through the injector and ammonia gas, and partially enters the magnesium deposition liquid flash tank; injecting unreacted ammonia and water vapor in the reactor into the bottom of the ammonia still to provide partial heat for the ammonia still;

(8) the precipitated magnesium liquid enters a precipitated magnesium liquid flash tank, low-pressure steam is flashed out in an adiabatic manner, and the steam enters a steam compressor to be used as secondary steam after being heated and pressurized; the flash liquid in the magnesium precipitation flash tank enters a belt type vacuum filter through gravity;

(9) the flash liquid in the magnesium precipitation flash tank enters a belt type vacuum filter for liquid-solid separation through gravity; the separated magnesium hydroxide filter cake enters a high-speed mixer;

(10) continuously feeding the magnesium hydroxide filter cake separated by the belt type vacuum filter into a high-speed mixer, adding an auxiliary agent, and stirring to modify the magnesium hydroxide filter cake; the modified magnesium hydroxide of the high-speed mixer enters a fluidized bed dryer;

(11) continuously feeding the modified magnesium hydroxide in the high-speed mixer into a fluidized bed dryer through a blanking machine of the high-speed mixer; hot air containing magnesium hydroxide and discharged by the fluidized bed dryer is used for separating gas and solid through a cyclone separator and a bag filter;

(12) and (3) separating gas from solid by using magnesium hydroxide powder from a fluidized bed dryer, a cyclone separator and a bag filter, continuously feeding the magnesium hydroxide powder into a jet mill for grinding and grading, separating the gas from the solid by using the cyclone separator and the bag filter, and feeding the magnesium hydroxide powder into a magnesium hydroxide powder bin.

Furthermore, MgO is industrial MgO light-burned powder, and the mass content of MgO is 85%; solid NH₄NO₃Is industrial, NH₄NO₃The mass content is 99 percent; the water vapor is the water vapor of public works and is the self-contained power plantBack pressure water vapor of 0.45MPa and 245 ℃; the water vapor of the public works mainly provides a heat source for the fluidized bed dryer and also provides a heat source for the cavitation reactor; the ammonia evaporation liquid flash tank and the magnesium precipitation liquid flash tank flash off low-pressure steam to MVR, the temperature of secondary steam is 268 ℃, and the pressure of the secondary steam is 0.14MPa of superheated steam; the secondary water vapor can provide a heat source for the cavitation reactor.

Further, the raw materials of MgO light-burned powder and solid NH are added into the pulping tank in the step (1)₄NO₃(after the device normally operates, only needs to be supplemented), the mother liquor recovered by the belt type vacuum filter continuously enters a pulping tank through preheating, and pulping is carried out under the stirring of a mechanical stirrer; MgO slurry solid content is 3.5% -4.5% by MgO, MgO and NH₄NO₃The molar ratio is 1: (2.58-2.68); the temperature in the pulping tank is 50-55 ℃, the pressure is normal pressure, and the retention time of the materials is 2-2.5 h.

And further, the MgO slurry in the pulping tank 1 continuously enters a cavitation reactor in the step (2) through gravity, the MgO slurry is subjected to ammonia evaporation reaction in the cavitation reactor, the temperature in the cavitation reactor is 105-110 ℃, the pressure is 0.12-0.14 MPa, the rotating speed of a stirring heat transfer rotor of the cavitation reactor is 1000-1100 rpm, and the retention time of the materials is 2-2.5 h.

Further, the temperature at the top of the ammonia still 3 in the step (3) is 50-60 ℃, and the pressure is normal pressure.

Further, the adiabatic flash temperature of the ammonia evaporation liquid flash tank in the step (4) is 60-65 ℃, and the retention time of the material is 1-1.5 h.

Further, the outer rotary drum of the horizontal double-drum centrifuge 5 in the step (5) is 2350rpm, the inner rotary drum is 2400rpm, the temperature of an impurity filter cake is 45-50 ℃, and the moisture content (wet basis) is 35-40%; in the step (6), the temperature at the top of the aerial fog magnesium precipitation tower is 80-90 ℃, the pressure is 0.15-0.16 MPa, the temperature at the bottom of the aerial fog magnesium precipitation tower is 120-130 ℃, and the pressure is 0.2-0.27 MPa.

Further, the temperature in the injection reactor in the step (7) is 110-115 ℃, the pressure is 0.143-0.169 MPa, and the retention time of the materials is 2-2.5 h.

Further, the adiabatic flash temperature of the magnesium precipitation liquid flash tank in the step (8) is 60-65 ℃, and the retention time of the material is 1-1.5 h.

Further, the pressure of the belt type vacuum filter 9 in the step (9) is 0.053MPa to 0.043MPa, the moisture content of the magnesium hydroxide filter cake is 45 percent to 50 percent, and the temperature of the magnesium hydroxide filter cake is 40 ℃ to 45 ℃.

Further, the temperature in the high-speed mixer in the step (10) is 80-85 ℃, the pressure is normal pressure, and the retention time of the materials is 1-1.5 h.

Further, the step (11) is that the fluidized bed dryer is provided with hot air by a fluidized air heater to fluidize and dry the modified magnesium hydroxide particles; the built-in heating inner discharge pipe provides main drying heat, the temperature in the fluidized bed dryer is 185-195 ℃, and the retention time of the materials is 0.75-1 h; the temperature of the magnesium hydroxide powder leaving the fluidized bed dryer is 80-85 ℃ and the temperature of the drying exhaust gas leaving the fluidized air preheater is 70-75 ℃.

Further, the particle size of the magnesium hydroxide ground and classified by the jet mill in the step (12) is less than 2 μm.

Compared with the prior art, the magnesium hydroxide production device and method based on resource utilization have the beneficial effects that:

1. the ammonia gas is hermetically recycled, so that the environment is friendly; the water vapor of the public works is the back pressure water vapor of the self-contained power plant; low-pressure water vapor is flashed to MVR from the material flow after the ammonia evaporation and magnesium deposition reaction, and secondary water vapor can provide an auxiliary heat source for a cavitation reactor for ammonia evaporation reaction; hot air separated by the fluidized bed dryer provides a heat source for a fluidized air preheater of the fluidized bed dryer; unreacted ammonia gas from the injection reactor can provide an auxiliary heat source for the ammonia still; water vapor condensate water is used as filter cake washing water; the resources are effectively utilized, the energy is saved, and the environment is protected.

2. The cavitation reactor, the jet reactor, the white steel structured packing ammonia still and the aerosol magnesium precipitation tower are adopted, so that the heat transfer and mass transfer are enhanced, the production efficiency is improved, and the reaction time is shortened; the aerial fog deposition of magnesium creates a prerequisite for the completeness of the crystal form of magnesium hydroxide, and the high-temperature deposition of magnesium in the jet reactor provides a hydrothermal condition for the completeness of the crystal form of magnesium hydroxide; the high-speed mixer provides convenient conditions for the modification of magnesium hydroxide;

3. the reaction rate of the magnesium oxide is more than 90 percent, and the quality of the magnesium hydroxide is superior to the national standard of industrial products; the invention has the advantages of mature process, continuous operation, high automation degree, resource recycling, environment friendliness and comprehensive energy saving of the device by 30 percent.

Drawings

FIG. 1 is a schematic view of a magnesium hydroxide production apparatus based on resource utilization according to the present invention;

FIG. 2 is a schematic structural diagram of a cavitation reactor in a magnesium hydroxide production device based on resource utilization.

Reference numerals: 1. a pulping tank 1-1, a mechanical stirrer; 2. 2-1 parts of a cavitation reactor, 2-2 parts of a stirring heat transfer rotor, 2-2 parts of a mechanical seal, 2-3 parts of a tooth-shaped baffle (four uniformly distributed), 2-4 parts of a jacket, 2-5 parts of 45-degree 12-blade turbine blades (four layers), 2-6 parts of an anchor type stirring blade, 2-7 parts of an ammonia distillation liquid pump, 2-8 parts of a secondary water vapor condensation water tank, 2-9 parts of a secondary water vapor condensation water pump; 3. 3-1 parts of an ammonia still, 3-2 parts of white steel structured packing, 3-3 parts of a built-in cooler, 3-3 parts of a demister, 3-4 parts of an ammonia gas compressor, 3-5 parts of an ammonia gas buffer tank; 4. ammonia liquor flash evaporation tank, 4-1, water vapor compressor; 5. 5-1 parts of a horizontal double-drum centrifuge, 5-2 parts of a refined magnesium liquid tank and a refined magnesium liquid pump; 6. 6-1 parts of an aerial fog magnesium precipitation tower, 6-2 parts of an atomizer, 6-3 parts of a demister and a liquid seal pipe; 7. a spray reactor 7-1, a coupler 7-2, a sprayer 7-3 and a power fluid pump; 8. a magnesium precipitation liquid flash tank; 9. a belt type vacuum filter 9-1, a vacuum chamber 9-2, a buffer tank 9-3, a vacuum pump 9-4, a washing water pump 9-5, a mother liquor tank 9-6 and a mother liquor pump; 10. 10-1 parts of a high-speed mixer, 10-1 parts of a stirring paddle, 10-2 parts of a blanking machine; 11. the system comprises a fluidized bed dryer, 11-1 parts of a public engineering water vapor condensate pump, 11-2 parts of a rake stirrer, 11-3 parts of a fluidized air preheater, 11-4 parts of a fluidized air heater, 11-5 parts of a heating inner discharge pipe, 11-6 parts of a cyclone separator, 11-7 parts of a bag filter, 11-8 parts of an induced draft fan, 11-9 parts of a public engineering water vapor condensate tank; 12. 12-1 of an airflow crusher, 12-2 of a cyclone separator, 12-3 of a bag filter and 12-3 of a magnesium hydroxide powder bin.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Example 1

As shown in fig. 1 and 2, a magnesium hydroxide production device based on resource utilization comprises a beating tank 1, a cavitation reactor 2, an ammonia liquor flash tank 4, a horizontal double-drum centrifuge 5, an aerosol magnesium precipitation tower 6, an injection reactor 7, a magnesium liquor flash tank 8, a belt vacuum filter 9, a high-speed mixer 10, a fluidized bed dryer 11 and a jet mill 12 which are connected in sequence; an ammonia still 3 is arranged above the cavitation reactor; the pulping tank 1 is used for preparing mixed slurry of MgO and ammonium salt; the cavitation reactor 2 is used for the ammonia distillation reaction of the slurry; the ammonia evaporation liquid flash tank 4 is used for carrying out flash evaporation on the ammonia evaporation liquid; the horizontal double-drum centrifuge 5 is used for carrying out liquid-solid separation on the flash evaporation liquid; the aerial fog magnesium precipitation tower 6 is used for atomizing the separated refined magnesium liquid and performing magnesium precipitation reaction with ammonia gas; the injection reactor 7 is used for continuously carrying out magnesium precipitation reaction on the magnesium precipitation liquid and ammonia gas; the magnesium precipitation liquid flash tank 8 is used for carrying out flash evaporation on the magnesium precipitation liquid; the belt type vacuum filter 9 is used for carrying out liquid-solid separation on the flash evaporation liquid; the high-speed mixer 10 is used for modifying the separated magnesium hydroxide; the fluidized bed dryer 11 is used for drying the modified magnesium hydroxide; the jet mill 12 is used for grinding and grading the dried magnesium hydroxide powder;

an ammonia gas reflux pipeline is arranged between the injection reactor 7 and the ammonia still 3 and used for conveying unreacted ammonia gas in the injection reactor to the bottom of the ammonia still;

the cavitation reactor comprises a reactor body, wherein a tooth-shaped baffle plate 2-3 is arranged on the inner wall of the reactor body, a jacket 2-4 is arranged on the outer wall of the reactor body, a hollow stirring heat transfer rotor 2-1 is arranged in the reactor body, an anchor type stirring paddle 2-6 is arranged at the lower part of the stirring heat transfer rotor, a 45-degree 12-blade transparent paddle 2-5 is arranged on the outer wall of the stirring heat transfer rotor above the anchor type stirring paddle, and each layer of blade is staggered with each tooth of the tooth-shaped baffle plate in the horizontal direction; the four tooth-shaped baffles are symmetrically arranged on the inner wall of the reactor body at intervals of 90 degrees;

the jet reactor adopts jet stirring and adopts jacket heat exchange; the cavitation reactor exchanges heat with a jacket through a stirring heat transfer rotor (steam is introduced to be used as a reaction heat source);

the device further comprises: the ammonia gas recovery device comprises an ammonia gas compressor 3-4 and a water vapor compressor 4-1, wherein the input end and the output end of the ammonia gas compressor are respectively connected with an ammonia gas outlet at the top of an ammonia still 3 and an ammonia gas buffer tank, the ammonia gas buffer tank is connected with an aerosol magnesium precipitation tower, ammonia gas separated from the ammonia still enters the ammonia gas buffer tank after being compressed by the ammonia gas compressor, and the ammonia gas collected by the ammonia gas buffer tank enters the aerosol magnesium precipitation tower; the input end of the water vapor compressor 4-1 is connected with the ammonia evaporation liquid flash tank 4 and the magnesium deposition liquid flash tank 8, and the output end is connected with the cavitation reactor 2; and low-pressure steam adiabatically flashed out from the ammonia evaporation liquid flash tank 4 and the magnesium deposition liquid flash tank 8 enters a steam compressor 4-1 to be heated and pressurized to form secondary steam which is used as an auxiliary heat source of the cavitation reactor.

The device also comprises a cyclone separator 11-6, a bag filter 11-7 and a fluidized air preheater 11-3, wherein the cyclone separator and the bag filter are used for carrying out gas-solid separation on hot air containing magnesium hydroxide discharged by the fluidized bed dryer, the separated magnesium hydroxide powder enters the jet mill, the fluidized air preheater preheats the fluidized air by taking the hot air separated by the cyclone separator and the bag filter as a heat source, and the preheated fluidized air enters the fluidized air heater 11-4 for reheating and then enters hot air fluidized materials of the fluidized bed dryer.

The device also comprises a secondary water vapor condensation water tank and a public engineering water vapor condensation water tank, wherein the cavitation reactor 2 takes secondary water vapor and water vapor as heat sources, and the fluidized bed dryer 11 and the fluidized air heater 11-4 take water vapor as heat sources; the secondary water vapor condensate tank 2-8 is used for collecting secondary water vapor condensate generated by the cavitation reactor, and the collected secondary water vapor condensate is used for filter cake washing water of the horizontal double-drum centrifuge 5; the water vapor condensate tank 11-9 of the public engineering is used for collecting water vapor condensate generated by a built-in calandria heater and a fluidized air heater of the fluidized bed dryer, and the collected water vapor condensate is used for filter cake washing water of the belt type vacuum filter 9.

The device also comprises a mother liquor tank 9-5 which is used for collecting the mother liquor filtered by the belt type vacuum filter, and the collected mother liquor enters the pulping tank after being preheated by the built-in cooler 3-2 at the upper section of the ammonia still 3 and is used as the ingredient water of the pulping tank.

The cavitation reactor 2 adopted by the invention consists of a hollow stirring heat transfer rotor 2-1, a mechanical seal 2-2, a tooth-shaped baffle (four blocks are uniformly distributed) 2-3, a jacket 2-4, a 45-degree 12-blade turbine blade (four layers) 2-5 and an anchor type stirring blade 2-6; the MgO slurry is subjected to ammonia evaporation reaction in a cavitation reactor, and generates a cavitation effect under the combined action of four layers of 45-degree 12-blade turbine blades 2-5 on a high-speed stirring heat transfer rotor 2-1 and a tooth-shaped baffle 2-3, so that a hydration layer is effectively stripped; the instant local high temperature and high pressure, micro jet and shock wave caused by cavitation provide good physicochemical environment for the chemical reaction, improve the chemical reaction rate and provide chemical reaction power; the macro mixing and the micro mixing in the flow field are improved, and the gas phase, the liquid phase and the solid phase have extremely high mass transfer rate;

the ammonia still 3 consists of white steel structured packing 3-1, a built-in cooler 3-2, a demister 3-3, an ammonia gas compressor 3-4 and an ammonia gas buffer tank 3-5; the cavitation reactor 2 plays a role of a reboiler of the ammonia still 3, and ammonia gas and water vapor from the jet reactor 7 are mixed to bring heat to the ammonia still 3; separating ammonia and water vapor in an ammonia still 3 through white steel structured packing 3-1, enabling an internal cooler 3-2 to generate internal reflux, demisting cooled ammonia gas through a demister 3-3, then feeding the cooled ammonia gas into an ammonia gas compressor 3-4, and feeding the compressed ammonia gas into an aerosol magnesium precipitation tower 6 through an ammonia gas buffer tank 3-5;

the aerial fog magnesium precipitation tower 6 consists of a refined magnesium liquid atomizer 6-1, a demister 6-2 and a magnesium precipitation liquid seal pipe 6-3; the refined magnesium liquid continuously enters an upper atomizer 6-1 and a lower atomizer 6-1 in the aerial fog magnesium precipitation tower 6, and the atomized refined magnesium liquid and ammonia gas entering from the tower bottom carry out magnesium precipitation reaction;

the injection reactor 7 consists of a coupler 7-1, an injector 7-2 and a power fluid pump 7-3; wherein the coupler 7-1 comprises a mixed liquid inlet pipe, a mixed liquid distribution cavity, a gas suction pipe, a gas distribution cavity and the like; the ejector adopts the venturi jet principle and consists of a power fluid inlet, a flow guide ring, a power fluid nozzle, a gas suction inlet, a mixing cavity, a diffusion cavity and a mixed liquid outlet; the power fluid pump 7-3 is operated to suck the mixed liquid in the device, the mixed liquid is pumped into the coupler 7-1, the power fluid passes through the nozzle to form high-speed fluid, the kinetic energy of the fluid is maximum at the moment, the potential energy is minimum, negative pressure can be generated at the gas suction inlet, then the gas is sucked in, the sucked gas is rapidly expanded in a negative pressure area and is beaten into micro bubbles by the power fluid, the gas, the liquid and the solid are fully mixed in the coupler 7-1 and are discharged in an accelerated manner due to energy exchange, the potential energy of the mixed liquid is increased to the maximum value through the pressure expansion cavity, and the mixed liquid is dragged to further enhance the mixing and stirring effect; ammonia gas is sucked by the coupler 7-1, high-speed jet flow close to the speed of sound can be generated, and heat and mass transfer among mixed liquor is facilitated to carry out magnesium precipitation reaction.

The raw material light calcined powder adopted by the invention is an industrial product, and the MgO mass content is 85%; NH (NH)₄NO₃Is industrial, NH₄NO₃The mass content is 99 percent; the used water vapor of the public engineering is back pressure water vapor of 0.45MPa and 245 ℃ of a self-contained power plant; the water vapor of the public works mainly provides a heat source for the fluidized bed dryer and also provides a heat source for the cavitation reactor; the ammonia evaporation liquid flash tank and the magnesium precipitation liquid flash tank flash off low-pressure steam to MVR, the temperature of secondary steam is 268 ℃, and the pressure of the secondary steam is 0.14MPa of superheated steam; the secondary water vapor can provide a heat source for the cavitation reactor.

When the production device is started, the pulping tank 1 is prepared by process water, and the cavitation reactor 2 heats materials by public engineering water vapor through a jacket and a stirring heat transfer rotor; when the production device is started, the injection reactor 7 heats materials by using public engineering water vapor through a jacket until the whole production device operates normally, and the reaction is continued by switching to cooling water; when the secondary steam is insufficient, the water vapor of the public works is also used as a heating source of the cavitation reactor 2, the devices are connected through corresponding pipelines, and the pipelines in the attached figure 1 are drawn according to the principle of vertical and continuous intersection when the pipelines are intersected on the figure but not actually intersected.

A method for producing magnesium hydroxide based on resource utilization specifically comprises the following steps:

(1) the pulping tank 1 is added with light calcined powder (MgO) solid powder and (supplementary) solid NH₄NO₃Mother liquor recovered by the belt type vacuum filter 9 continuously enters the pulping tank 1 after being preheated, and is pulped under the stirring of the mechanical stirrer 1-1;

(2) MgO slurry in a pulping tank 1 continuously enters a cavitation reactor 2 through gravity, the MgO slurry is subjected to ammonia evaporation reaction in the cavitation reactor, and a hydration layer is effectively stripped under the combined action of four layers of 45-degree 12-blade turbine blades 2-5 on a high-speed stirring heat transfer rotor 2-1 and a tooth-shaped baffle 2-3; the liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, and the gas phase in the cavitation reactor 2 enters an ammonia evaporation tower 3;

(3) gas phase in a cavitation reactor 2 enters an ammonia still 3 and unreacted ammonia and water vapor from an injection reactor 7 are separated in the ammonia still 3 through white steel structured packing 3-1, an internal cooler 3-2 can generate internal reflux, cooled ammonia enters an ammonia compressor 3-4 after being demisted by a demister 3-3, and compressed ammonia enters an aerosol magnesium precipitation tower 6 through an ammonia buffer tank 3-5;

(4) liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, low-pressure steam is obtained through adiabatic flash evaporation, and the steam enters a steam compressor 4-1 to be used as secondary steam after being heated and pressurized; the flash liquid in the ammonia evaporation liquid flash tank 4 enters a horizontal double-drum centrifuge 5 through gravity;

(5) the flash liquid in the ammonia evaporation liquid flash tank 4 enters a horizontal double-drum centrifuge 5 for liquid-solid separation through gravity; washing water from a secondary water vapor condensate water tank 2-8 continuously leaches filter cakes through a secondary water vapor condensate water pump 2-9, and the separated filter cakes are sent to a waste residue treatment system; the separated refined magnesium liquid enters a refined magnesium liquid tank 5-1 and continuously enters an aerosol magnesium precipitation tower 6 through a refined magnesium liquid pump 5-2;

(6) the refined magnesium liquid continuously enters an upper atomizer 6-1 and a lower atomizer 6-1 in an aerosol magnesium precipitation tower 6, and the atomized refined magnesium liquid and ammonia gas entering from the bottom of the tower are subjected to magnesium precipitation reaction; unreacted ammonia gas is discharged out of the tower through a demister 6-2 and enters a coupler 7-1 of an injection reactor 7, and magnesium precipitation liquid enters the liquid level in the injection reactor 7 through a liquid seal pipe;

(7) unreacted ammonia gas from the aerial fog magnesium precipitation tower 6 enters a coupler 7-1 of an injection reactor 7; magnesium deposition liquid of the aerial fog magnesium deposition tower 6 enters the position below the liquid level in the injection reactor 7 through the liquid seal pipe 6-3, part of the magnesium deposition liquid enters the coupler 7-1 through the power fluid pump 7-3 of the injection reactor 7, the magnesium deposition reaction is continuously carried out through the ejector 7-2 and ammonia gas, and part of the magnesium deposition liquid enters the magnesium deposition liquid flash tank 8; unreacted ammonia and steam in the injection reactor 7 enter the bottom of the ammonia still 3 to provide part of heat for the ammonia still;

(8) part of the precipitated magnesium liquid from the injection reactor 7 enters a precipitated magnesium liquid flash tank 8, low-pressure water vapor is subjected to adiabatic flash evaporation, and the water vapor enters a water vapor compressor 4-1 to be used as secondary water vapor after being heated and pressurized; the flash liquid in the magnesium precipitation liquid flash tank 8 enters a belt type vacuum filter 9 through gravity;

(9) feeding the flash liquid in the magnesium precipitation liquid flash tank 8 into a belt type vacuum filter 9 through gravity, and carrying out liquid-solid separation on the flash slurry through a vacuum chamber 9-1 under the action of a vacuum pump 9-3; separated washing liquid and mother liquid firstly enter a buffer tank 9-2, a washing water pump 9-4 is used for flushing primary filter cakes with primary washing water, then the mother liquid enters a mother liquid tank 9-5 and continuously enters an upper section cooler 3-2 of an ammonia still 3 through a mother liquid pump 9-6; the preheated mother liquor continuously enters a pulping tank 1; washing water from a water vapor condensate tank 11-9 of the public work is used for continuously leaching magnesium hydroxide filter cakes through a water vapor condensate pump 11-1 of the public work, and the separated magnesium hydroxide filter cakes are sent to a high-speed mixer 10;

(10) continuously feeding the magnesium hydroxide filter cake separated by the belt type vacuum filter 9 into a high-speed mixer 10, simultaneously adding auxiliary agents (surfactant and coupling agent, the adding amount is 1-5% of the mass of the magnesium hydroxide), and modifying the magnesium hydroxide filter cake (improving the affinity of inorganic magnesium hydroxide and organic matters) under the action of a stirring paddle 10-1; the magnesium hydroxide modified by the high-speed mixer 10 continuously enters a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10;

(11) continuously feeding the modified magnesium hydroxide in the high-speed mixer 10 into a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10; crushing the modified magnesium hydroxide by a rake type stirrer 11-2, and providing hot air for fluidizing and drying the modified magnesium hydroxide particles by a fluidized air heater 11-4 in a fluidized bed dryer 11; a built-in heating inner calandria 11-5 provides main drying heat, and a cyclone separator 11-6 and a bag filter 11-7 separate gas from solid; the induced draft fan 11-8 is used for sending the waste hot gas separated by the fluidized bed dryer 11 to the fluidized air preheater 11-3 for preheating the fluidized air, and then discharging the waste hot gas to a waste gas treatment system; the dried magnesium hydroxide powder from the fluidized bed dryer 11 is continuously fed into a jet mill 12;

(12) continuously feeding the magnesium hydroxide powder from the fluidized bed dryer 11 into a jet mill 12 for grinding and grading; gas-solid separation is carried out on the magnesium hydroxide powder through a cyclone separator 12-1 and a bag filter 12-2, and the magnesium hydroxide powder enters a magnesium hydroxide powder bin 12-3.

Example 2

A resource utilization-based magnesium hydroxide production method based on the device in the embodiment 1 comprises the following steps:

(1) adding 50kg/h of light calcined powder (MgO mass content 85%) solid powder into the pulping tank 1, and recovering mother liquor (NH) from the belt vacuum filter 9₄NO₃215kg/h, containing make-up NH₄NO₃)1156kg/h is preheated and continuously enters a pulping tank 1, and pulping is carried out under the stirring of a mechanical stirrer 1-1; MgO slurry solid content is 3.5% in MgO, MgO and NH₄NO₃The molar ratio is 1: 2.68; the temperature in the pulping tank 1 is 50 ℃, the pressure is normal pressure, and the retention time of the materials is 2 hours;

(2) MgO slurry in a pulping tank 1 continuously enters a cavitation reactor 2 through gravity, the MgO slurry is subjected to ammonia evaporation reaction in the cavitation reactor, and a hydration layer is effectively stripped under the combined action of four layers of 45-degree 12-blade turbine blades 2-5 on a high-speed stirring heat transfer rotor 2-1 and a tooth-shaped baffle 2-3; the cavitation reactor 2 is heated by secondary water vapor and public engineering water vapor through a stirring heat transfer rotor 2-1 and a jacket 2-4, and the cavitation reactor 2 simultaneously plays a role of a reboiler of an ammonia still 3; the liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, and the gas phase in the cavitation reactor 2 enters an ammonia evaporation tower 3; the temperature in the cavitation reactor 2 is 105 ℃, the pressure is 0.12MPa, the rotating speed of a stirring heat transfer rotor 2-1 of the cavitation reactor 2 is 1000rpm, and the retention time of the materials is 2.5 h;

(3) the gas phase in the cavitation reactor 2 enters the ammonia still 3 to be mixed with ammonia gas and water vapor from the jet reactor 7, meanwhile, the heat is brought to the ammonia still 3, and the cavitation reactor 2 simultaneously plays the role of a reboiler of the ammonia still 3; separating ammonia and water vapor in an ammonia still 3 through white steel structured packing 3-1, enabling an internal cooler 3-2 to generate internal reflux, demisting cooled ammonia gas through a demister 3-3, then feeding the cooled ammonia gas into an ammonia gas compressor 3-4, and feeding the compressed ammonia gas into an aerosol magnesium precipitation tower 6 through an ammonia gas buffer tank 3-5; the temperature at the top of the ammonia still 3 is 50 ℃, and the pressure is normal pressure;

(4) liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, low-pressure steam is obtained through adiabatic flash evaporation, the steam enters a steam compressor 4-1, the temperature and the pressure of the steam are raised and then the steam is used as secondary steam, the temperature of the secondary steam is 268 ℃, and the pressure of the secondary steam is 0.14 MPa; the flash liquid in the ammonia evaporation liquid flash tank 4 enters a horizontal double-drum centrifuge 5 through gravity; the adiabatic flash temperature of the ammonia evaporation liquid flash tank 4 is 60 ℃, and the retention time of the materials is 1.5 h;

(5) feeding the flash liquid in the ammonia evaporation liquid flash tank 4 into a horizontal double-drum centrifuge 5 for liquid-solid separation by gravity; washing water from a secondary water vapor condensate water tank 2-8 continuously leaches filter cakes through a secondary water vapor condensate water pump 2-9, and the separated filter cakes are sent to a waste residue treatment system; the separated refined magnesium liquid enters a refined magnesium liquid tank 5-1 and continuously enters an aerosol magnesium precipitation tower 6 through a refined magnesium liquid pump 5-2; the outer rotary drum of the horizontal double-drum centrifuge 5 is 2350rpm, the inner rotary drum is 2400rpm, the temperature of an impurity filter cake is 45 ℃, and the moisture content (wet basis) is 35 percent;

(6) the refined magnesium liquid continuously enters an upper atomizer 6-1 and a lower atomizer 6-1 in an aerosol magnesium precipitation tower 6, and the atomized refined magnesium liquid and ammonia gas entering from the bottom of the tower are subjected to magnesium precipitation reaction; unreacted ammonia gas is discharged out of the tower through a demister 6-2 and enters a coupler 7-1 of an injection reactor 7, and magnesium precipitation liquid enters the liquid level in the injection reactor 7 through a liquid seal pipe; the temperature of the top of the aerial fog magnesium precipitation tower 6 is 80 ℃, the pressure is 0.15MPa, the temperature of the bottom of the aerial fog magnesium precipitation tower is 120 ℃, and the pressure is 0.2 MPa;

(7) unreacted ammonia gas from the aerial fog magnesium precipitation tower 6 enters a coupler 7-1 of an injection reactor 7; the magnesium precipitation liquid of the aerial fog magnesium precipitation tower 6 enters the liquid level in the jet reactor 7 through the liquid seal pipe 6-3 and passes through the power fluid pump 7-3 part (2 m) of the jet reactor 7³H) enters a coupler 7-1, and continues to carry out magnesium precipitation reaction with ammonia gas through an ejector 7-2, and part (1 m)³H) entering a magnesium precipitation liquid flash tank 8; the unreacted ammonia gas in the injection reactor 7 enters the bottom of the ammonia still 3 to provide part of heat for the ammonia still; the temperature in the jet reactor 7 is 110 ℃, the pressure is 0.143MPa, and the retention time of the materials is 2.5 h;

(8) part of the precipitated magnesium liquid from the injection reactor 7 enters a precipitated magnesium liquid flash tank 8, low-pressure water vapor is subjected to adiabatic flash evaporation, and the water vapor enters a water vapor compressor 4-1 to be used as secondary water vapor after being heated and pressurized; the flash liquid in the magnesium precipitation liquid flash tank 8 enters a belt type vacuum filter 9 through gravity; the adiabatic flash temperature of the magnesium precipitation liquid flash tank 8 is 60 ℃, and the retention time of the material is 1.5 h;

(9) feeding the flash liquid in the magnesium precipitation liquid flash tank 8 into a belt type vacuum filter 9 through gravity, and carrying out liquid-solid separation on the flash slurry through a vacuum chamber 9-1 under the action of a vacuum pump 9-3; separated washing liquid and mother liquid firstly enter a buffer tank 9-2, a washing water pump 9-4 is used for flushing primary filter cakes with primary washing water, then the mother liquid enters a mother liquid tank 9-5 and continuously enters an upper section cooler 3-2 of an ammonia still 3 through a mother liquid pump 9-6; the preheated mother liquor continuously enters a pulping tank 1; washing water from a water vapor condensate tank 11-9 of the public work is used for continuously leaching magnesium hydroxide filter cakes through a water vapor condensate pump 11-1 of the public work, and the separated magnesium hydroxide filter cakes are sent to a high-speed mixer 10; the pressure of the belt type vacuum filter 9 is 0.053MPa, the moisture content of the magnesium hydroxide filter cake is 50% (wet basis), and the temperature of the magnesium hydroxide filter cake is 40 ℃;

(10) continuously feeding the magnesium hydroxide filter cake separated by the belt type vacuum filter 9 into a high-speed mixer 10, adding an auxiliary agent, and modifying the magnesium hydroxide filter cake under the action of a stirring paddle 10-1; the magnesium hydroxide modified by the high-speed mixer 10 continuously enters a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10; the temperature in the high-speed mixer 10 is 80 ℃, the pressure is normal pressure, and the retention time of the materials is 1.5 h;

(11) continuously feeding the modified magnesium hydroxide in the high-speed mixer 10 into a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10; crushing the modified magnesium hydroxide by a rake type stirrer 11-2, and providing hot air for fluidizing and drying the modified magnesium hydroxide particles by a fluidized air heater 11-4 in a fluidized bed dryer 11; a built-in heating inner calandria 11-5 provides main drying heat, and a cyclone separator 11-6 and a bag filter 11-7 separate gas from solid; the induced draft fan 11-8 is used for sending the waste hot gas separated by the fluidized bed dryer 11 to the fluidized air preheater 11-3 for preheating the fluidized air, and then discharging the waste hot gas to a waste gas treatment system; the dried magnesium hydroxide powder from the fluidized bed dryer 11 is continuously fed into a jet mill 12; the temperature in the fluidized bed dryer 11 is 185 ℃, and the retention time of the materials is 1 h; the temperature of the magnesium hydroxide powder leaving the fluidized bed dryer 11 was 80 ℃ and the temperature of the drying exhaust gas leaving the fluidized air preheater 11-3 was 70 ℃;

the step (12) is to continuously feed the magnesium hydroxide powder from the fluidized bed dryer 11 into a jet mill 12 for grinding and classification; gas-solid separation is carried out on the magnesium hydroxide powder through a cyclone separator 12-1 and a bag filter 12-2, and 51kg/h of magnesium hydroxide powder enters a magnesium hydroxide powder bin 12-3; the particle size of the magnesium hydroxide ground and classified by the jet mill 12 is less than 2 μm.

Example 3

A resource utilization-based magnesium hydroxide production method based on the device in the embodiment 1 comprises the following steps:

(1) adding 50kg/h of light calcined powder (MgO mass content 85%) solid powder into the pulping tank 1, and recovering mother liquor (NH) from the belt vacuum filter 9₄NO₃215kg/h, containing make-up NH₄NO₃)1156kg/h is preheated and continuously enters a pulping tank 1, and pulping is carried out under the stirring of a mechanical stirrer 1-1; MgO slurry solid content is 4.5% in MgO, MgO and NH₄NO₃The molar ratio is 1: 2.58; the temperature in the pulping tank 1 is 55 ℃, the pressure is normal pressure, and the retention time of the materials is 2 hours;

(2) MgO slurry in a pulping tank 1 continuously enters a cavitation reactor 2 through gravity, the MgO slurry is subjected to ammonia evaporation reaction in the cavitation reactor, and a hydration layer is effectively stripped under the combined action of four layers of 45-degree 12-blade turbine blades 2-5 on a high-speed stirring heat transfer rotor 2-1 and a tooth-shaped baffle 2-3; the cavitation reactor 2 is heated by secondary water vapor and public engineering water vapor through a stirring heat transfer rotor 2-1 and a jacket 2-4, and the cavitation reactor 2 simultaneously plays a role of a reboiler of an ammonia still 3; the liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, and the gas phase in the cavitation reactor 2 enters an ammonia evaporation tower 3; the temperature in the cavitation reactor 2 is 110 ℃, the pressure is 0.14MPa, the rotating speed of a stirring heat transfer rotor 2-1 of the cavitation reactor 2 is 1100rpm, and the retention time of the materials is 2 hours;

(3) the gas phase in the cavitation reactor 2 enters the ammonia still 3 to be mixed with ammonia gas and water vapor from the jet reactor 7, meanwhile, the heat is brought to the ammonia still 3, and the cavitation reactor 2 simultaneously plays the role of a reboiler of the ammonia still 3; separating ammonia and water vapor in an ammonia still 3 through white steel structured packing 3-1, enabling an internal cooler 3-2 to generate internal reflux, demisting cooled ammonia gas through a demister 3-3, then feeding the cooled ammonia gas into an ammonia gas compressor 3-4, and feeding the compressed ammonia gas into an aerosol magnesium precipitation tower 6 through an ammonia gas buffer tank 3-5; the temperature at the top of the ammonia still 3 is 60 ℃, and the pressure is normal pressure;

(4) liquid phase in the cavitation reactor 2 enters an ammonia evaporation liquid flash tank 4 through an ammonia evaporation liquid pump 2-7, low-pressure steam is obtained through adiabatic flash evaporation, the steam enters a steam compressor 4-1, the temperature and the pressure of the steam are raised and then the steam is used as secondary steam, the temperature of the secondary steam is 268 ℃, and the pressure of the secondary steam is 0.14 MPa; the flash liquid in the ammonia evaporation liquid flash tank 4 enters a horizontal double-drum centrifuge 5 through gravity; the adiabatic flash temperature of the ammonia evaporation liquid flash tank 4 is 65 ℃, and the retention time of the materials is 1 h;

(5) feeding the flash liquid in the ammonia evaporation liquid flash tank 4 into a horizontal double-drum centrifuge 5 for liquid-solid separation by gravity; washing water from a secondary water vapor condensate water tank 2-8 continuously leaches filter cakes through a secondary water vapor condensate water pump 2-9, and the separated filter cakes are sent to a waste residue treatment system; the separated refined magnesium liquid enters a refined magnesium liquid tank 5-1 and continuously enters an aerosol magnesium precipitation tower 6 through a refined magnesium liquid pump 5-2; the outer rotary drum of the horizontal double-drum centrifuge 5 is 2350rpm, the inner rotary drum is 2400rpm, the temperature of an impurity filter cake is 50 ℃, and the moisture content (wet basis) is 40%;

(6) the refined magnesium liquid continuously enters an upper atomizer 6-1 and a lower atomizer 6-1 in an aerosol magnesium precipitation tower 6, and the atomized refined magnesium liquid and ammonia gas entering from the bottom of the tower are subjected to magnesium precipitation reaction; unreacted ammonia gas is discharged out of the tower through a demister 6-2 and enters a coupler 7-1 of an injection reactor 7, and magnesium precipitation liquid enters the liquid level in the injection reactor 7 through a liquid seal pipe; the temperature of the top of the aerial fog magnesium precipitation tower 6 is 90 ℃, the pressure is 0.16MPa, the temperature of the bottom of the aerial fog magnesium precipitation tower is 130 ℃, and the pressure is 0.27 MPa;

(7) unreacted ammonia gas from the aerial fog magnesium precipitation tower 6 enters a coupler 7-1 of an injection reactor 7; magnesium deposition liquid of the aerial fog magnesium deposition tower 6 enters the position below the liquid level in the injection reactor 7 through the liquid seal pipe 6-3, part of the magnesium deposition liquid enters the coupler 7-1 through the power fluid pump 7-3 of the injection reactor 7, the magnesium deposition reaction is continuously carried out through the ejector 7-2 and ammonia gas, and part of the magnesium deposition liquid enters the magnesium deposition liquid flash tank 8; the unreacted ammonia gas in the injection reactor 7 enters the bottom of the ammonia still 3 to provide part of heat for the ammonia still; the temperature in the jet reactor 7 is 115 ℃, the pressure is 0.169MPa, and the retention time of the materials is 2 h;

(8) part of the precipitated magnesium liquid from the injection reactor 7 enters a precipitated magnesium liquid flash tank 8, low-pressure water vapor is subjected to adiabatic flash evaporation, and the water vapor enters a water vapor compressor 4-1 to be used as secondary water vapor after being heated and pressurized; the flash liquid in the magnesium precipitation liquid flash tank 8 enters a belt type vacuum filter 9 through gravity; the adiabatic flash temperature of the magnesium precipitation liquid flash tank 8 is 65 ℃, and the retention time of the material is 1 h;

(9) feeding the flash liquid in the magnesium precipitation liquid flash tank 8 into a belt type vacuum filter 9 through gravity, and carrying out liquid-solid separation on the flash slurry through a vacuum chamber 9-1 under the action of a vacuum pump 9-3; separated washing liquid and mother liquid firstly enter a buffer tank 9-2, a washing water pump 9-4 is used for flushing primary filter cakes with primary washing water, then the mother liquid enters a mother liquid tank 9-5 and continuously enters an upper section cooler 3-2 of an ammonia still 3 through a mother liquid pump 9-6; the preheated mother liquor continuously enters a pulping tank 1; washing water from a water vapor condensate tank 11-9 of the public work is used for continuously leaching magnesium hydroxide filter cakes through a water vapor condensate pump 11-1 of the public work, and the separated magnesium hydroxide filter cakes are sent to a high-speed mixer 10; the pressure of the belt type vacuum filter 9 is 0.043MPa, the moisture content of the magnesium hydroxide filter cake is 45% (wet basis), and the temperature of the magnesium hydroxide filter cake is 45 ℃;

(10) continuously feeding the magnesium hydroxide filter cake separated by the belt type vacuum filter 9 into a high-speed mixer 10, adding an auxiliary agent, and modifying the magnesium hydroxide filter cake under the action of a stirring paddle 10-1; the magnesium hydroxide modified by the high-speed mixer 10 continuously enters a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10; the temperature in the high-speed mixer 10 is 85 ℃, the pressure is normal pressure, and the retention time of the materials is 1 h;

(11) continuously feeding the modified magnesium hydroxide in the high-speed mixer 10 into a fluidized bed dryer 11 through a blanking machine 10-2 of the high-speed mixer 10; crushing the modified magnesium hydroxide by a rake type stirrer 11-2, and providing hot air for fluidizing and drying the modified magnesium hydroxide particles by a fluidized air heater 11-4 in a fluidized bed dryer 11; heating the inner calandria 11-5 to provide main drying heat, and separating gas and solid by the cyclone separator 11-6 and the bag filter 11-7; the induced draft fan 11-8 is used for sending the waste hot gas separated by the fluidized bed dryer 11 to the fluidized air preheater 11-3 for preheating the fluidized air, and then discharging the waste hot gas to a waste gas treatment system; the dried magnesium hydroxide powder from the fluidized bed dryer 11 is continuously fed into a jet mill 12; the temperature in the fluidized bed dryer 11 is 195 ℃, and the retention time of the materials is 0.75 h; the temperature of the magnesium hydroxide powder leaving the fluidized bed dryer 11 was 85 ℃ and the temperature of the drying exhaust gas leaving the fluidized air preheater 11-3 was 75 ℃;

(12) continuously feeding the magnesium hydroxide powder from the fluidized bed dryer 11 into a jet mill 12 for grinding and grading; gas-solid separation is carried out on the magnesium hydroxide powder through a cyclone separator 12-1 and a bag filter 12-2, and 52kg/h of magnesium hydroxide powder enters a magnesium hydroxide powder bin 12-3; the particle size of the magnesium hydroxide ground and classified by the jet mill 12 is less than 2 μm.

In the method for producing magnesium hydroxide based on resource utilization, the device is energy-saving comprehensively by 30%; the quality of the magnesium hydroxide is higher than the standard of HG T3607-2007 industrial magnesium hydroxide.

The technical idea of the present invention is described in the above technical solutions, and the protection scope of the present invention is not limited thereto, and any changes and modifications made to the above technical solutions according to the technical essence of the present invention belong to the protection scope of the technical solutions of the present invention.