阅读说明：本技术 一种由脱硫石膏生产ii型无水石膏的装置及方法 (Device and method for producing II type anhydrous gypsum from desulfurized gypsum ) 是由 宋小霞 万建东 唐绍林 陈家伟 彭卓飞 于 2019-11-25 设计创作，主要内容包括：本发明提供了一种由脱硫石膏生产II型无水石膏的装置及方法,所述装置包括依次连接的干燥单元、煅烧单元和产品收集单元,所述干燥单元包括破碎装置和至少一级干燥装置,所述煅烧单元包括流态化煅烧装置。本发明所述装置通过干燥及煅烧工艺的结合,将脱硫石膏精准转化为II型无水石膏,可实现脱硫石膏中亚硫酸钙的氧化以及有机物的分解,杂质去除率达到99％以上,极大降低了有害杂质对石膏制品的影响；所述方法以超硫酸盐水泥为目标产品时,提高了脱硫石膏原料中氯离子的最低限值,间接减少预处理的水耗及二次水污染；本发明提高了脱硫石膏的综合利用效率,进一步复配超硫酸盐水泥,产品性能稳定,强度高,扩大了脱硫石膏的应用途径。(The invention provides a device and a method for producing II type anhydrous gypsum by desulfurized gypsum, wherein the device comprises a drying unit, a calcining unit and a product collecting unit which are sequentially connected, the drying unit comprises a crushing device and at least one stage of drying device, and the calcining unit comprises a fluidized calcining device. According to the device, the desulfurization gypsum is accurately converted into the II-type anhydrous gypsum through the combination of drying and calcining processes, so that the oxidation of calcium sulfite and the decomposition of organic matters in the desulfurization gypsum can be realized, the impurity removal rate reaches over 99 percent, and the influence of harmful impurities on gypsum products is greatly reduced; when the method takes the super-sulfate cement as a target product, the minimum limit value of chloride ions in the desulfurized gypsum raw material is improved, and the water consumption of pretreatment and secondary water pollution are indirectly reduced; the invention improves the comprehensive utilization efficiency of the desulfurized gypsum, further compounds the super-sulfate cement, has stable product performance and high strength, and enlarges the application approach of the desulfurized gypsum.)

1. The device for producing the II-type anhydrous gypsum from the desulfurized gypsum is characterized by comprising a drying unit, a calcining unit and a product collecting unit which are sequentially connected, wherein the drying unit comprises a crushing device and at least one stage of drying device, and the calcining unit comprises a fluidized calcining device.

2. The apparatus of claim 1, wherein the crushing device comprises a forced air dryer;

preferably, the drying means comprises a cyclonic dryer;

preferably, the number of stages of the drying device is 2-4;

preferably, the last stage of drying device is a pre-calcining device, and a solid outlet of the pre-calcining device is connected with an inlet of the calcining unit;

preferably, the drying unit further comprises a first induced draft fan, and an inlet of the first induced draft fan is connected with a gas outlet of the drying unit.

3. The apparatus of claim 1 or 2, wherein the fluidized calcining apparatus is a vertical fluidized calciner;

preferably, the calcining unit further comprises a feeder, a discharger, a temperature control device and an air control device, the feeder is arranged at the inlet of the fluidized calcining device, the discharger is arranged at the outlet of the fluidized calcining device, the temperature control device is arranged in the fluidized calcining device and in front of the outlet, and the air control device is arranged at an air inlet pipeline of the fluidized calcining device;

preferably, a pressurizing fan, a product separator and a product buffer are arranged behind the calcining unit, an outlet of the pressurizing fan is connected with an inlet of an air inlet pipeline of the fluidization calcining device, an outlet of the upper part of the fluidization calcining device is connected with an inlet of the product separator, a solid outlet of the product separator is connected with the product collecting unit, the discharger is connected with an inlet of the product buffer, and an outlet of the product buffer is connected with the product collecting unit;

preferably, the product collection unit comprises a hoist and a product collection bin.

4. The apparatus according to any one of claims 1 to 3, further comprising a feeding unit, an outlet of the feeding unit being connected to an inlet of the drying unit;

preferably, the feeding unit comprises a raw material storage device and a raw material conveying device, and inlets of the raw material storage device, the raw material conveying device and the crushing device are sequentially connected;

preferably, an anti-sticking wall assembly is arranged on the raw material storage device.

5. The apparatus according to any one of claims 1 to 4, further comprising a cooling unit disposed between the calcining unit and the product collecting unit;

preferably, the cooling unit comprises a cooler, a first air blower, a first dust collector and a product conveying device, an outlet of the fluidization calcining device is connected with an inlet of the cooler, an outlet of the first air blower is connected with an inlet of the cooler, a gas outlet of the cooler is connected with an inlet of the first dust collector, a solid outlet of the cooler and a solid outlet of the first dust collector are both connected with the product conveying device, and the product conveying device is connected with the product collecting unit;

preferably, the product conveying means comprises a screw conveyor;

preferably, the device further comprises a dust removal unit, the dust removal unit comprises a dust remover and a second induced draft fan, an inlet of the dust remover is connected with a gas outlet of a first dust collector of the cooling unit and a gas outlet of the product collection unit, a solid outlet of the dust remover is connected with an inlet of the product collection unit, and a gas outlet of the dust remover is connected with the second induced draft fan;

preferably, the device further comprises a heat supply unit, wherein the heat supply unit comprises a hot blast stove, and a gas outlet of the hot blast stove is independently connected with gas inlets of the drying unit and the calcining unit;

preferably, the heat supply unit still includes gas heater, second air-blower and second dust collector, gas heater's entry links to each other with the export of second draught fan, gas heater's export links to each other through the entry of second air-blower with the hot-blast furnace, the export of hot-blast furnace links to each other through the gas inlet of second dust collector with fluidization calcining device.

6. A method for producing type II anhydrite using the apparatus as set forth in any one of claims 1 to 5, characterized in that the method comprises the steps of:

(1) crushing and drying the desulfurized gypsum to obtain III type anhydrous gypsum;

(2) and (2) carrying out fluidized calcination treatment on the III type anhydrous gypsum obtained in the step (1) to obtain II type anhydrous gypsum.

7. The method of claim 6, wherein the desulfurized gypsum of step (1) is a byproduct of a limestone-gypsum wet desulfurization process;

preferably, the desulfurized gypsum of step (1) contains free water, calcium sulfite and chloride ions;

preferably, the content of the free water accounts for 8-14 wt% of the total amount of the desulfurized gypsum;

preferably, after the crushing in the step (1), the proportion of particles with the particle size of less than 80 μm in the raw material is more than 90%;

preferably, the drying grade in the step (1) is 2-4 grades;

preferably, the temperature of the next stage drying is higher than that of the previous stage drying;

preferably, the temperature of the last stage of drying is 220-350 ℃;

preferably, hot source gas is introduced in the crushing and drying processes in the step (1);

preferably, the heat source gas used for crushing and drying in the step (1) is from a heat supply unit.

8. The method according to claim 6 or 7, wherein the calcination treatment of step (2) is carried out in a fluidized calcination apparatus;

preferably, the temperature of the calcination treatment in the step (2) is 320-720 ℃;

preferably, the time of the calcination treatment in the step (2) is 18-55 min;

preferably, the gas used for maintaining fluidization of the anhydrous gypsum in step (2) is a heat source gas from a heat supply unit.

9. The method according to any one of claims 6 to 8, wherein the calcination treatment of step (2) is followed by a cooling treatment;

preferably, the cooling treatment is: introducing gas to cool the calcined product, then carrying out gas-solid separation, collecting the obtained solid product, and carrying out dust removal treatment on the obtained gas;

preferably, the temperature of the solid obtained after the gas-solid separation is reduced to below 110 ℃;

preferably, the gas after dust removal treatment enters a heat supply unit for generating hot source gas;

preferably, the heat supply unit generates a heat source gas by combustion of coal or natural gas;

preferably, the type II anhydrous gypsum of step (2) is used as a raw material for super sulfate cement, gypsum slag cement or gypsum composite cementitious material.

10. Method according to any of claims 6-9, characterized in that the method comprises the steps of:

(1) crushing and drying the desulfurized gypsum, wherein the free water content of the desulfurized gypsum accounts for 8-14 wt% of the total amount of the desulfurized gypsum, the particle size of the crushed raw material is less than 80 mu m and accounts for more than 90%, the drying grade is 2-4, the drying temperature of the next stage is higher than that of the previous stage, the drying temperature of the last stage is 220-350 ℃, and the type III anhydrous gypsum is obtained, and heat source gas is introduced in the crushing and drying processes;

(2) carrying out fluidized calcination treatment on the III type anhydrous gypsum obtained in the step (1), wherein the calcination treatment temperature is 320-720 ℃, and the calcination treatment time is 18-55 min;

(3) cooling the calcined product in the step (2) by using gas, then carrying out gas-solid separation, cooling the obtained solid to below 110 ℃, and recovering the product to obtain II type anhydrous gypsum, wherein the II type anhydrous gypsum is used as a raw material of super-sulfate cement, gypsum slag cement or a gypsum composite cementing material; and (4) carrying out dust removal treatment on the gas obtained by gas-solid separation, and enabling the gas after dust removal treatment to enter a heat supply unit for generating heat source gas.

Technical Field

The invention belongs to the technical field of solid waste utilization, and relates to a device and a method for producing II-type anhydrous gypsum by using desulfurized gypsum.

Background

Along with the development of national economy, a great deal of fossil energy such as coal, petroleum and the like is used, and SO is generated in the combustion process₂、NO_xAnd the like, wherein thermal power generation is one of important sources of gas pollutants, the power demand is continuously increased, so that the pollutant production is still increased, and desulfurization and denitrification become necessary environmental protection measures for each coal-fired or fuel-fired device. At present, the desulfurization process mainly comprises limestone-gypsum wet desulfurization, limestone-gypsum dry or semi-dry desulfurization, ammonia desulfurization and the like, wherein the limestone-gypsum wet desulfurization process accounts for about 90 percent and is the most important desulfurization process.

The by-product of limestone-gypsum wet desulphurization is dihydrate gypsum, also called as desulfurized gypsum in the industry, the grade of the desulfurized gypsum is generally more than 90 percent, the total grade of the desulfurized gypsum is higher than that of natural gypsum, but the desulfurized gypsum contains Na⁺、Mg²⁺、Cl^-、CaSO₃·0.5H₂Impurities such as O and the like are more than those of natural gypsum, and if the impurities are directly used without pretreatment, the application range is limited, and equipment is damaged due to corrosivity. At present, the desulfurization byproduct gypsum is mainly used for cement retarders, building materials, mould materials, soil conditioners, fillers and the like in comprehensive utilization, wherein the building materials are only used for surface layers or decoration and are not applied to main structure materials, the utilization amount of the building materials is limited by the application range, the annual comprehensive utilization range of the building materials is far shorter than the annual production amount, and the dosage of the building materials is far lower than that of the cement used for the main structure materials. Therefore, the desulfurization gypsum needs to be converted to replace the traditional cement, so that the byproduct desulfurization gypsum can be digested in a large amount, and the environmental protection problem is solved.

CN 110066125A discloses a two-step method building gypsum powder production process based on the characteristics of desulfurized gypsum, which mainly comprises the steps of mixing desulfurized gypsum raw materials with carbon fibers treated by plasma, carrying out ball milling to obtain a mixed material, carrying out primary drying and subsequent calcination on the mixed material, and then carrying out aging and homogenization to obtain building gypsum powder; the plasma adopted in the process method increases the treatment cost, and the lower calcination temperature causes incomplete dehydration of the desulfurized gypsum and poorer stability. CN 204138536U discloses a device for drying and calcining desulfurized gypsum, which comprises a feeding structure, a scattering structure, an air flow drying tower, a pulse bag-type dust collector and a draught fan which are connected in sequence, wherein the pulse bag-type dust collector is connected with a calcining fluidized bed furnace, the bottom of the pulse bag-type dust collector is provided with a spiral conveying structure, the spiral conveying structure is connected with a feeding hole of the calcining fluidized bed furnace through a dried gypsum conveying pipe, and a waste heat outlet of the calcining fluidized bed furnace is connected with the scattering structure through an air duct; the device has good sealing performance, can produce various gypsum products, but has unclear hierarchical distribution of drying and calcining, the temperature of the drying and calcining is close to that of the calcining, anhydrous gypsum products cannot be obtained, and the application range is limited.

At present, because the super-sulfate cement has the characteristics of low hydration heat, sulfate corrosion resistance and good freezing resistance, the super-sulfate cement can effectively replace the traditional cement, the application range is continuously expanded, the main component of the super-sulfate cement comprises gypsum, wherein the effect of II type anhydrous gypsum is optimal, and therefore, a method for accurately preparing the II type anhydrous gypsum by the desulfurized gypsum is necessarily sought, the influence of impurities in the desulfurized gypsum can be solved, the resource utilization rate of the desulfurized gypsum is improved, and the application range of the super-sulfate cement is expanded.

Disclosure of Invention

Aiming at the problems in the prior art, the invention aims to provide a device and a method for producing II type anhydrous gypsum by using desulfurized gypsum, wherein the device takes desulfurized gypsum which is a byproduct of a desulfurization process as a raw material, removes calcium sulfite and organic matters in the desulfurized gypsum through drying and calcining processes, improves the minimum limit value of the content of chloride ions, and reduces the water consumption required by washing; meanwhile, the invention is also assisted with processes such as cooling, waste heat recovery, dust removal and the like, so that the desulfurized gypsum has the advantages of large treatment capacity, high comprehensive utilization degree, energy conservation, environmental protection and no secondary pollution.

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

in one aspect, the invention provides a device for producing type II anhydrous gypsum from desulfurized gypsum, which comprises a drying unit, a calcining unit and a product collecting unit which are connected in sequence, wherein the drying unit comprises a crushing device and at least one stage of drying device, and the calcining unit comprises a fluidized calcining device.

According to the device, the type II anhydrous gypsum is produced by taking the desulfurization gypsum which is a byproduct of a desulfurization process as a raw material, free water and most of bound water in the desulfurization gypsum are sufficiently removed in a drying unit, calcium sulfite in the desulfurization gypsum is oxidized by a calcining unit, and meanwhile, possibly existing organic matters are decomposed, so that the influence of impurities on subsequent gypsum products is reduced; the II type anhydrous gypsum is generated by drying and calcining processes, particularly by controlling the fluidization calcining process of the gypsum, has stable quality and is difficult to excite hydration and condensation, and can be used as a raw material to prepare the super-sulfate cement, so that the minimum limit of the chloride ion content can be improved, the water consumption for washing the raw material is reduced, the performance of the obtained product is stable, the strength is high, and the resource utilization rate of the desulfurized gypsum is improved.

The following technical solutions are preferred technical solutions of the present invention, but not limited to the technical solutions provided by the present invention, and technical objects and advantageous effects of the present invention can be better achieved and achieved by the following technical solutions.

In a preferred embodiment of the present invention, the crushing apparatus includes a forced air dryer for crushing the raw material before main drying and assisting drying and dehydration.

Preferably, the drying means comprises a cyclonic dryer.

Preferably, the number of the drying devices is 2-4, such as 2, 3 or 4, the number of the drying devices is selected according to the free water content in the desulfurized gypsum, and the higher the free water content is, the more the number of the drying devices is required.

Preferably, the last stage drying device is a precalcination device, the solids outlet of which is connected to the inlet of the calcination unit.

In the invention, the outlet heat source gas of the next stage drying device in the multi-stage drying device is used as the inlet heat source gas of the previous stage drying device to carry out multi-stage countercurrent drying; the forced airflow dryer also needs to be introduced with heat source gas to take the raw materials out, and the forced airflow dryer plays a role of a drying device, and after gas-solid separation, the solid raw materials enter a subsequent drying device.

Preferably, the drying unit further comprises a first induced draft fan, and an inlet of the first induced draft fan is connected with a gas outlet of the drying unit.

As a preferable technical scheme of the invention, the fluidization calcining device is a vertical fluidization calciner.

Preferably, the calcining unit further comprises a feeder, a discharger, a temperature control device and an air control device, the feeder is arranged at an inlet of the fluidized calcining device, the discharger is arranged at an outlet of the fluidized calcining device, the temperature control device is arranged in the fluidized calcining device and in front of the outlet, and the air control device is arranged at an air inlet pipeline of the fluidized calcining device.

In the invention, a fluidized calcining mode is adopted to treat the dried material, and a radiating pipe, an air distribution plate, an air outlet, an outlet baffle plate and the like are arranged in the fluidized calcining device; the radiating pipe is made of high-temperature-resistant alloy, hot air is introduced into the radiating pipe, and gypsum powder and hot air with a fluidization effect are arranged outside the radiating pipe; the hot air is a mixed gas of hot flue gas subjected to primary dust removal treatment and hot air, and active substances in the flue gas can promote the oxidation of calcium sulfite in the desulfurized gypsum and improve the heat transfer efficiency; because the radiating pipe and the inlet of the fluidized air need to be filled with air, the wind control device is arranged at two positions.

In addition, the residence time of the materials is controlled by controlling the feeding amount, the fluidizing air quantity and the height of the outlet baffle.

Preferably, a pressurizing fan, a product separator and a product buffer are arranged behind the calcining unit, an outlet of the pressurizing fan is connected with an inlet of an air inlet pipeline of the fluidization calcining device, an outlet of the upper part of the fluidization calcining device is connected with an inlet of the product separator, a solid outlet of the product separator is connected with the product collecting unit, the discharger is connected with an inlet of the product buffer, and an outlet of the product buffer is connected with the product collecting unit.

Preferably, the product collection unit comprises a hoist and a product collection bin.

As a preferable technical scheme, the device also comprises a feeding unit, and an outlet of the feeding unit is connected with an inlet of the drying unit.

Preferably, the feeding unit comprises a raw material storage device and a raw material conveying device, and the raw material storage device, the raw material conveying device and the inlet of the crushing device are connected in sequence.

In the invention, the raw material conveying device can adopt a belt weighing machine, and the addition amount of the desulfurized gypsum can be simultaneously controlled.

Preferably, the raw materials storage device is last to set up and to prevent that the adhesion of desulfurization gypsum is a large amount of on the device inner wall influences the device operation, also can reduce the corruption of desulfurization gypsum raw materials to the device, increase of service life.

As a preferable technical solution of the present invention, the apparatus further comprises a cooling unit disposed between the calcining unit and the product collecting unit.

Preferably, the cooling unit comprises a cooler, a first air blower, a first dust collector and a product conveying device, an outlet of the fluidization calcining device is connected with an inlet of the cooler, an outlet of the first air blower is connected with an inlet of the cooler, a gas outlet of the cooler is connected with an inlet of the first dust collector, a solid outlet of the cooler and a solid outlet of the first dust collector are both connected with the product conveying device, and the product conveying device is connected with the product collecting unit.

Preferably, the product conveying means comprises a screw conveyor.

Preferably, the device still includes the dust removal unit, the dust removal unit includes dust remover and second draught fan, the entry of dust remover links to each other with the gas outlet of the first dust collector of cooling unit and the gas outlet of product collection unit, the solid export of dust remover links to each other with the entry of product collection unit, the gas outlet of dust remover links to each other with the second draught fan.

Preferably, the device further comprises a heat supply unit comprising a hot blast stove, and a gas outlet of the hot blast stove is independently connected with gas inlets of the drying unit and the calcining unit.

The hot blast stove comprises a combustion chamber and a heat exchange chamber, coal or natural gas is used as a raw material for combustion, air is subjected to heat exchange to obtain hot air at a required temperature, the hot air is used as heat source gas of a drying unit and inlet air of a radiating pipe of a fluidized calcining device, and generated hot flue gas can be used as hot air for fluidization in the fluidized calcining device.

Preferably, the heat supply unit still includes gas heater, second air-blower and second dust collector, gas heater's entry links to each other with the export of second draught fan, gas heater's export links to each other through the entry of second air-blower with the hot-blast furnace, the export of hot-blast furnace links to each other through the gas inlet of second dust collector with fluidization calcining device.

In another aspect, the present invention provides a method for producing type II anhydrous gypsum using the above apparatus, the method comprising the steps of:

(1) crushing and drying the desulfurized gypsum to obtain III type anhydrous gypsum;

(2) and (2) carrying out fluidized calcination treatment on the III type anhydrous gypsum obtained in the step (1) to obtain II type anhydrous gypsum.

As a preferable technical scheme of the invention, the desulfurized gypsum in the step (1) is a byproduct of a limestone-gypsum wet desulphurization process.

Preferably, the desulfurized gypsum of step (1) contains free water, calcium sulfite and chloride ions.

Preferably, the free water content is 8-14 wt% of the total desulfurized gypsum, such as 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt% or 14 wt%, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

Preferably, after the crushing in step (1), the proportion of particles having a raw material particle size of less than 80 μm is 90% or more, for example, 80 μm, 75 μm, 70 μm, 65 μm or 60 μm, or 90%, 91%, 92%, 93%, 94% or 90%, but the present invention is not limited to the above-mentioned values, and other values not listed in the above-mentioned range are also applicable.

Preferably, the drying stage number in the step (1) is 2-4 stages, such as 2 stages, 3 stages or 4 stages, and the number of the drying devices is selected according to the free water content in the desulfurized gypsum and the drying temperature.

Preferably, the temperature of the next stage drying is higher than that of the previous stage drying.

Preferably, the temperature of the final stage drying is 220 to 350 ℃, for example 220 ℃, 250 ℃, 280 ℃, 300 ℃, 320 ℃ or 350 ℃, but is not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, hot source gas is introduced in the crushing and drying process in the step (1).

Preferably, the heat source gas used for crushing and drying in the step (1) is from a heat supply unit.

As a preferable embodiment of the present invention, the calcination treatment in the step (2) is carried out in a fluidized calcination apparatus.

Preferably, the temperature of the calcination treatment in step (2) is 320 to 720 ℃, for example 320 ℃, 350 ℃, 400 ℃, 450 ℃, 550 ℃, 600 ℃, 630 ℃, 650 ℃, 680 ℃, 700 ℃ or 720 ℃, etc., but not limited to the recited values, and other values not recited in the range of the values are also applicable.

Preferably, the time of the calcination treatment in step (2) is 18-55 min, such as 18min, 21min, 25min, 30min, 35min, 40min, 45min, 50min or 55min, but not limited to the recited values, and other values not recited in the range of the recited values are also applicable.

In the invention, the calcining temperature and time are accurately controlled, so that the gypsum can be converted into II-type anhydrous gypsum which is difficult to hydrate and coagulate, and industrial by-product gypsum is subjected to reduction and harmless treatment and is used as a raw material for further utilization.

Preferably, the gas for maintaining fluidization of the type III anhydrous gypsum in the step (2) is a heat source gas of a heat supply unit.

As a preferable embodiment of the present invention, the calcination treatment in the step (2) is followed by cooling treatment.

Preferably, the cooling treatment is: and introducing gas to cool the calcined product, then carrying out gas-solid separation, collecting the obtained solid product, and carrying out dust removal treatment on the obtained gas.

Preferably, the temperature of the solid obtained after the gas-solid separation has been reduced to 110 ℃ or lower, for example 110 ℃, 100 ℃, 90 ℃, 80 ℃, 70 ℃, 60 ℃, 50 ℃ or 40 ℃ and the like, but is not limited to the recited values, and other values not recited in the range of values are equally applicable.

Preferably, the gas after dust removal treatment enters a heat supply unit for generating hot source gas.

Preferably, the heat supply unit generates the heat source gas by combustion of coal or natural gas.

Preferably, the type II anhydrous gypsum of step (2) is used as a raw material for super sulfate cement, gypsum slag cement or gypsum composite cementitious material, preferably super sulfate cement.

In the invention, when the II type anhydrous gypsum takes the super-sulfate cement as a target product, the minimum limit value of the chloride ion content can be increased, the chloride ion content in the desulfurized gypsum after the flue gas desulfurization treatment of a general power plant can meet the requirement, the problems of water consumption and sewage increase in the traditional raw material pretreatment are reduced, and the treatment cost is reduced.

As a preferred technical scheme of the invention, the method comprises the following steps:

(1) crushing and drying the desulfurized gypsum, wherein the free water content of the desulfurized gypsum accounts for 8-14 wt% of the total amount of the desulfurized gypsum, the particle size of the crushed raw material is less than 80 mu m and accounts for more than 90%, the drying grade is 2-4, the drying temperature of the next stage is higher than that of the previous stage, the drying temperature of the last stage is 220-350 ℃, and the type III anhydrous gypsum is obtained, and heat source gas is introduced in the crushing and drying processes;

(2) carrying out fluidized calcination treatment on the III type anhydrous gypsum obtained in the step (1), wherein the calcination treatment temperature is 320-720 ℃, and the calcination treatment time is 18-55 min;

(3) cooling the calcined product in the step (2) by using gas, then carrying out gas-solid separation, cooling the obtained solid to below 110 ℃, and recovering the product to obtain II type anhydrous gypsum, wherein the II type anhydrous gypsum is used as a raw material of super-sulfate cement, gypsum slag cement or a gypsum composite cementing material; and (4) carrying out dust removal treatment on the gas obtained by gas-solid separation, and enabling the gas after dust removal treatment to enter a heat supply unit for generating heat source gas.

Compared with the prior art, the invention has the following beneficial effects:

(1) the device accurately converts the desulfurized gypsum into the II-type anhydrous gypsum through the combination of drying and calcining processes, can realize the oxidation of calcium sulfite and the decomposition of organic matters in the desulfurized gypsum, has the impurity removal rate of over 99 percent, greatly reduces the influence of harmful impurities on gypsum products, has high purity of the obtained product, only has one crystal structure of the II-type anhydrous gypsum, is difficult to hydrate, and has the hydration rate of less than 2 percent under the hydration condition (25 ℃, the water-paste ratio of 10 and the hydration time of 24 hours);

(2) when the super-sulfate cement is taken as a target product, the minimum limit value of chloride ions in the desulfurized gypsum raw material is improved, and the water consumption of pretreatment and secondary water pollution are indirectly reduced;

(3) the invention combines the cooling, waste heat recovery, dust removal and other processes with the main process, improves the comprehensive utilization efficiency of the desulfurized gypsum, has the waste heat recovery rate of 65-88 percent, and does not bring the problems of dust pollution, tail gas pollution and the like;

(4) the device improves the productivity of producing II type anhydrous gypsum and further compounding super sulfate cement by using the desulfurized gypsum, has stable product performance and high strength, can replace the traditional cement, and enlarges the application approach of the desulfurized gypsum.

Drawings

FIG. 1 is a schematic structural connection diagram of a device for producing type II anhydrous gypsum from desulfurized gypsum according to example 1 of the present invention;

fig. 2 is a schematic structural diagram of a crushing cutter head in the crushing device provided by the embodiment 1 of the invention;

FIG. 3 is a schematic view of the structure of a fluidized calcination apparatus provided in example 1 of the present invention;

wherein, 1-a feeding unit, 11-a raw material storage device, 12-a raw material conveying device, 2-a drying unit, 21-a crushing device, 22-a primary drying device, 23-a secondary drying device, 24-a tertiary drying device, 25-a quaternary drying device, 26-a gas-solid separation device, 27-an intermediate product conveying device, 28-a first induced draft fan, 3-a calcining unit, 31-a feeder, 32-a fluidized calcining device, 321-a feeding port, 322-a discharging port, 323-a fluidized air inlet, 324-an air distribution plate, 325-an exhaust port, 326-a hot air inlet, 327-a hot air outlet, 328-a calcining chamber, 329-a radiating pipe, 33-a pressure fan, 34-a temperature control device and 35-an air control device, 36-product separator, 37-discharger, 38-product buffer, 4-cooling unit, 41-cooler, 42-first blower, 43-first dust collector, 44-product conveying device, 5-dedusting unit, 51-deduster, 52-second induced draft fan, 6-heat supply unit, 61-hot blast stove, 62-gas preheater, 63-second blower, 64-second dust collector, 7-product collection unit, 71-hoister and 72-product collection bin.

Detailed Description

In order to better illustrate the present invention and facilitate the understanding of the technical solutions of the present invention, the following embodiments are only simple examples of the present invention and do not represent or limit the scope of the present invention, which is defined by the claims.

The invention provides a device and a method for producing II type anhydrous gypsum from desulfurized gypsum, the device comprises a drying unit 2, a calcining unit 3 and a product collecting unit 7 which are connected in sequence, the drying unit 2 comprises a crushing device 21 and at least one stage of drying device, and the calcining unit 3 comprises a fluidized calcining device 32.

The method comprises the following steps:

(1) crushing and drying the desulfurized gypsum to obtain III type anhydrous gypsum;

(2) and (2) carrying out fluidized calcination treatment on the III type anhydrous gypsum obtained in the step (1) to obtain II type anhydrous gypsum.

The following are typical but non-limiting examples of the invention: