阅读说明：本技术 一种炉法磷酸生产系统以及生产工艺 (Furnace-process phosphoric acid production system and production process ) 是由 向红跃 于 2021-11-09 设计创作，主要内容包括：本发明公开了一种炉法磷酸生产系统,中间炉法反应组件包括炉法反应器,所述炉法反应器包括还原区与氧化区,还原区设置有一次空气进口、燃烧气进口以及固体物料进口,氧化区设置有二次空气进口,一次空气进口连接有一次空气装置,燃烧气进口连接有燃烧气装置,固体物料进口连接前端给料组件的物料出口,二次空气进口连接有二次空气装置,P-(2)O-(5)气体出口连接后端磷酸制备组件的气体进口。本发明还公开了一种炉法磷酸生产工艺。与现有技术相比,本发明可直接用磷矿石生产出高浓度磷酸而无需用净化设备,它可以大大降低能耗和生产成本,无污染物排放,还可以充分利用低品位的磷矿,符合节能省耗,碳中和,资源综合利用的要求。(The invention discloses a furnace-process phosphoric acid production system, wherein an intermediate furnace-process reaction component comprises a furnace-process reactor, the furnace-process reactor comprises a reduction area and an oxidation area, the reduction area is provided with a primary air inlet, a combustion gas inlet and a solid material inlet, the oxidation area is provided with a secondary air inlet, the primary air inlet is connected with a primary air device, the combustion gas inlet is connected with a combustion gas device, the solid material inlet is connected with a material outlet of a front-end feeding component, the secondary air inlet is connected with a secondary air device, and P is the ratio of the mass of the solid material to the mass of the material 2 O 5 The gas outlet is connected with the gas inlet of the phosphoric acid preparation assembly at the rear end. The invention also discloses a furnace-method phosphoric acid production process. Compared with available technology, the present invention can produce high concentration phosphoric acid directly from phosphate ore without needing purifying apparatus, and has greatly lowered power consumption and production costPollutant discharge, can also make full use of low-grade phosphorite, accord with the requirements of energy saving and consumption saving, carbon neutralization and resource comprehensive utilization.)

1. A furnace-process phosphoric acid production system is characterized in that: including front end feed subassembly, middle furnace process reaction unit and rear end phosphoric acid preparation subassembly, middle furnace process reaction unit includes furnace process reactor, furnace process reactor includes reduction zone and oxidation zone, the reduction zone is provided with primary air inlet, combustion gas import and solid material import, the oxidation zone is provided with secondary air inlet, primary air inlet is connected with primary air device, combustion gas inlet is connected with combustion gas device, the material export of solid material access connection front end feed subassembly, secondary air inlet is connected with secondary air device, oxidation zone upper portion is provided with P₂O₅Gas outlet, said P₂O₅The gas outlet is connected with the gas inlet of the phosphoric acid preparation assembly at the rear end.

2. The furnace-method phosphoric acid production system of claim 1, wherein the front-end feeding assembly comprises three groups of crushing mills and single material bins for respectively crushing phosphate ore, coal or coke and silica, the material outlets of the crushing mills of each group are connected with the corresponding single material bins, the material outlets of the single material bins are connected with a mixer for uniformly mixing the raw materials, the discharge port of the mixer is connected with a granulator, and the discharge port of the granulator is connected with the solid material inlet of the reduction zone through a continuous feeder.

3. The furnace-process phosphoric acid production system of claim 2, wherein the back-end phosphoric acid preparation assembly comprises a multi-stage absorption tower, a circulation tank, a circulation pump, a demister, a filter press and a finished product bin, wherein an air inlet of the multi-stage absorption tower is connected with the oxidationP of the region₂O₅The gas outlet, the liquid outlet of multistage absorption tower passes through the pipe connection circulation tank, the circulation tank disposes the circulating pump, the export of circulating pump passes through the pressure filter and connects the finished product feed bin, the waste gas mouth of multistage absorption tower connects the defroster, set up in the defroster and catch the foam device.

4. The furnace-process phosphoric acid production system of claim 3, wherein a gas distributor, a flow meter and a regulating valve are arranged in the combustion gas device, the primary air device and the secondary air device are respectively provided with the gas distributor, the flow meter, the regulating valve and a fan, the regulating valve is simultaneously connected with an external PLC (programmable logic controller), the continuous feeder is provided with a weighing sensor and a variable frequency motor, the variable frequency motor is connected with the external PLC, and the weighing sensor and the variable frequency motor form a closed-loop control weightlessness scale.

5. The furnace phosphoric acid production system of claim 4, wherein the bottom of the furnace reactor is provided with a catalytic device for catalyzing the reaction in the furnace.

6. The furnace-process phosphoric acid production system of claim 5, wherein the inner wall of the furnace-process reactor is provided with a refractory heat-insulating layer.

7. The furnace-method phosphoric acid production process is characterized by comprising the following steps of:

1) crushing and mixing raw materials: the phosphate ore, the coke and the silica are sent into respective crushing mills by a grab bucket to be crushed and ground to prepare particles with the granularity of less than 0.2mm, the ground phosphate ore, the coke and the silica are respectively sent into respective single material bins, and the phosphate ore, the coke and the silica are weighed according to the preparation proportion and then are sent into a mixer to be uniformly mixed;

2) granulating and feeding: the mixed material is sent into a granulator for granulation, the granularity of the granulated material is less than 4mm, the granulated material enters a mixing bin and a continuous feeder, the continuous feeder is a closed-loop control weightless scale, the metering precision is less than 1%, and the material continuously enters a furnace reactor according to the set feeding flow for reduction and oxidation reaction;

3)P₂O₅preparing gas: the continuous feeder sends the mixed material into a reduction zone in a furnace through a solid material inlet of a furnace reactor, a primary air device quantitatively feeds air into the reduction zone, a combustion gas device quantitatively feeds gas into the reduction zone, the gas and oxygen in the air are combusted to provide energy for reducing phosphorus simple substances, a flame zone formed by combustion of the gas and the oxygen in the air forms an independent reduction zone, the phosphorus simple substances subjected to reduction reaction float upwards under the action of high flame pressure to enter an oxidation zone, a secondary air device in the oxidation zone feeds quantitative air, and the phosphorus simple substances are oxidized to generate P₂O₅Gas, said P₂O₅Gas passing through P in the upper part of the oxidation zone₂O₅The gas outlet enters a rear-end phosphoric acid preparation component for hydration absorption to prepare phosphoric acid liquid with quantitative concentration;

4) preparing phosphoric acid solution: p generated after the material finishes reaction in the furnace reactor₂O₅The gas enters an absorption tower after heat exchange by a heat exchanger to complete absorption hydration, and enters P in the absorption tower₂O₅The gas temperature is controlled at 800 ℃ and 1000 ℃, P₂O₅The gas is changed into phosphoric acid after hydration and absorption, and then the phosphoric acid enters a circulating tank and then enters an absorption tower through a circulating pump to repeatedly absorb P₂O₅Reaching the set phosphoric acid concentration and the phosphoric acid spraying temperature<And (4) removing acid mist from tail gas discharged from the absorption tower through a demister, discharging the tail gas after reaching the standard, conveying impurities contained in the phosphoric acid reaching the required concentration into a filter press through a circulating pump, removing residues, and feeding the residues into a finished product bin.

8. The process for producing furnace phosphoric acid according to claim 7, wherein in the step 3), the reaction temperature in the furnace reactor is controlled at 1200-1500 ℃, the oxygen content of the air entering the furnace reactor from the primary air device (13) and the secondary air device is more than 10%, and the speed and the flow rate of the air entering the furnace reactor are controlled by adjusting the adjusting valves and the fans in the primary air device and the secondary air device, so that the reaction in the reduction zone and the oxidation zone is completed, the reduced phosphorus is completely combusted in the air, and the reduction zone and the oxidation zone in the furnace reactor are separated.

9. The furnace-process phosphoric acid production process of claim 7, wherein the primary air device, the secondary air device, the combustion gas device and the weightless scale are respectively controlled by an external PLC controller.

Technical Field

The invention relates to the technical field of chemical product processing, in particular to a furnace-process phosphoric acid production system and a production process.

Background

At present, two production processes, namely thermal production of phosphoric acid and wet production of phosphoric acid, are mainly used for producing phosphoric acid in the world.

The thermal phosphoric acid is prepared by reducing phosphorus in phosphate ore to yellow phosphorus by using a coke reducing agent at high temperature in an electric furnace, then burning and oxidizing the yellow phosphorus to prepare P2O5, and hydrating and absorbing the P2O 5. The production method has high energy consumption, high pollution and high emission. The electricity consumption of 1.5-1.7 million KWH per 1 ton of yellow phosphorus is consumed, 3.34tCO is generated per 1 ton of yellow phosphorus, the concentration of CO in tail gas is up to more than 90%, which is very unfavorable for carbon emission reduction, most of the tail gas is burnt in the prior production, which is also a huge energy waste, and the yellow phosphorus production is gradually moved to developing countries due to the fact that the yellow phosphorus production consumes a large amount of energy and brings great influence on the surrounding environment.

The wet process phosphoric acid production is to extract phosphorus from phosphate ore by using strong acid such as sulfuric acid and the like to directly obtain phosphoric acid, and various impurities in the ore also enter product acid because the wet process phosphoric acid is obtained by directly carrying out acidolysis on the phosphate ore. The quality of the product is inferior to that of phosphoric acid by a wet method, and phosphogypsum and impurities are required to be separated under low viscosity in the production of phosphoric acid by the wet method, so that the obtained product has lower acid concentration. Therefore, wet-process phosphoric acid must be purified and concentrated for high-concentration fine phosphate production. Thus, the production cost is greatly increased, and in the wet-process phosphoric acid production, the biggest problem is that a large amount of phosphogypsum as a byproduct is generated, and generally, 4 to 4.5t of phosphogypsum is generated per 1t of wet-process phosphoric acid (calculated as P2O 5) produced. At present, phosphogypsum is mainly treated by transporting the phosphogypsum to a slag yard and discharging the phosphogypsum into a flowing water area behind a slag storage. The phosphogypsum contains iron, zirconium, aluminum, arsenic, lead, acid and the like, which cause serious pollution to the environment. In addition, the components and the contents of impurities in the phosphoric acid are related to the production area, the grade and the impurity varieties in the ores, so that the adoption of medium-high grade phosphate ores in wet-process phosphoric acid production is limited.

Disclosure of Invention

The invention aims to provide a furnace-process phosphoric acid production system and a production process, which aim to solve the technical defects of high energy consumption, high pollution and high emission of hot-process phosphoric acid, high pollution of wet-process phosphoric acid and low product quality in the production process of phosphoric acid in the prior art.

The technical scheme of the invention is realized as follows:

a furnace-process phosphoric acid production system is characterized in that: comprises a front-end feeding component, an intermediate furnace reaction component and a rear-end phosphoric acid preparation component, wherein the intermediate furnace reaction componentThe subassembly includes furnace reactor, furnace reactor includes reduction zone and oxidation zone, reduction zone is provided with primary air inlet, combustion gas import and solid material import, the oxidation zone is provided with secondary air inlet, primary air inlet is connected with primary air device, combustion gas inlet is connected with combustion gas device, the material export of solid material access connection front end feed subassembly, secondary air inlet is connected with secondary air device, oxidation zone upper portion is provided with P₂O₅Gas outlet, said P₂O₅The gas outlet is connected with the gas inlet of the phosphoric acid preparation assembly at the rear end.

Preferably, the front-end feeding assembly comprises three groups of crushing mills and single-material bins for respectively crushing phosphate ore, coal or coke and silica, the material outlet of each group of crushing mills is connected with the corresponding single-material bin, the material outlets of the single-material bins are connected with a mixer for uniformly mixing the raw materials, the discharge port of the mixer is connected with the granulator, and the discharge port of the granulator is connected with the solid material inlet of the reduction zone through the continuous feeder.

Preferably, the rear-end phosphoric acid preparation assembly comprises a multi-stage absorption tower, a circulating tank, a circulating pump, a demister, a filter press and a finished product bin, wherein an air inlet of the multi-stage absorption tower is connected with the P of the oxidation zone₂O₅The gas outlet, the liquid outlet of multistage absorption tower passes through the pipe connection circulation tank, the circulation tank disposes the circulating pump, the export of circulating pump passes through the pressure filter and connects the finished product feed bin, the waste gas mouth of multistage absorption tower connects the defroster, set up in the defroster and catch the foam device.

Preferably, a gas distributor, a flow meter and a regulating valve are arranged in the combustion gas device, the primary air device and the secondary air device are respectively provided with the gas distributor, the flow meter, the regulating valve and a fan, the regulating valve is simultaneously connected with an external PLC (programmable logic controller), the continuous feeder is provided with a weighing sensor and a variable frequency motor, the variable frequency motor is connected with the external PLC, and the weighing sensor and the variable frequency motor form a closed-loop control weightless scale.

Preferably, the bottom of the furnace reactor is provided with a catalytic device for catalyzing the reaction in the furnace.

Preferably, the inner wall of the furnace reactor is provided with a refractory heat-insulating layer, the refractory heat-insulating layer is used for preventing heat in the furnace from radiating outside the furnace, the reduction reaction and the oxidation reaction are completed in the furnace reactor, the reduction reaction is an endothermic reaction, the heat is mostly provided by combustion of gas provided by a combustion gas device, the oxidation reaction is an exothermic reaction (the oxidation reaction is equivalent to combustion of white phosphorus, so a large amount of heat is generated), and nearly half of the heat in the oxidation reaction area in the furnace reactor is transferred to the reduction area for the reduction reaction by radiation, so that the consumption of the gas can be greatly reduced.

The invention also provides a furnace-method phosphoric acid production process, which comprises the following steps:

1) crushing and mixing raw materials: the phosphate ore, the coke and the silica are sent into respective crushing mills by a grab bucket to be crushed and ground to prepare particles with the granularity of less than 0.2mm, the ground phosphate ore, the coke and the silica are respectively sent into respective single material bins, and the phosphate ore, the coke and the silica are weighed according to the preparation proportion and then are sent into a mixer to be uniformly mixed;

2) granulating and feeding: the mixed material is sent into a granulator for granulation, the granularity of the granulated material is less than 4mm, the granulated material enters a mixing bin and a continuous feeder, the continuous feeder is a closed-loop control weightless scale, the metering precision is less than 1%, and the material continuously enters a furnace reactor according to the set feeding flow for reduction and oxidation reaction;

3)P₂O₅preparing gas: the continuous feeder sends the mixed material into a reduction zone in the furnace through a solid material inlet of the furnace reactor, a primary air device quantitatively feeds air into the reduction zone, a combustion gas device quantitatively feeds gas into the reduction zone, the gas and oxygen in the air are combusted to provide energy for reducing phosphorus simple substances, a flame zone formed by combustion of the gas and the oxygen in the air forms an independent reduction zone, and phosphorus simple substances in the reduction reaction float upwards under the action of high flame pressure to enter an oxidation zoneIntroducing quantitative air into a secondary air device in the oxidation zone, and oxidizing the phosphorus simple substance to generate P₂O₅A gas, wherein the oxidation reaction in the oxidation zone generates a large amount of heat, approximately half of the oxidation heat in the portion is radiated to the reduction zone for the reduction reaction, and the P₂O₅Gas passing through P in the upper part of the oxidation zone₂O₅The gas outlet enters a rear-end phosphoric acid preparation component for hydration absorption to prepare phosphoric acid liquid with quantitative concentration;

4) preparing phosphoric acid solution: p generated after the material finishes reaction in the furnace reactor₂O₅The gas enters an absorption tower after heat exchange by a heat exchanger to complete absorption hydration, and enters P in the absorption tower₂O₅The gas temperature is controlled at 800 ℃ and 1000 ℃, P₂O₅The gas is changed into phosphoric acid after hydration and absorption, and then the phosphoric acid enters a circulating tank and then enters an absorption tower through a circulating pump to repeatedly absorb P₂O₅Reaching the set phosphoric acid concentration and the phosphoric acid spraying temperature<And (4) removing acid mist from tail gas discharged from the absorption tower through a demister, discharging the tail gas after reaching the standard, conveying impurities contained in the phosphoric acid reaching the required concentration into a filter press through a circulating pump, removing residues, and feeding the residues into a finished product bin.

Preferably, in the step 3), the reaction temperature in the furnace reactor is controlled at 1200-1500 ℃, the oxygen content of the air entering the furnace reactor from the primary air device (13) and the secondary air device is greater than 10%, and the air speed and flow entering the furnace reactor are controlled by adjusting the adjusting valves and fans in the primary air device and the secondary air device, so that the reaction of the reduction zone and the oxidation zone is completed, the reduced phosphorus is completely combusted in the air, and the reduction zone and the oxidation zone in the furnace reactor are separated.

Preferably, the primary air device, the secondary air device, the combustion gas device and the weightlessness scale are respectively controlled by an external PLC controller for use.

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

according to the furnace-method phosphoric acid production system and the production process, phosphorus ore directly completes reduction reaction and oxidation reaction in the combustion reactor in the phosphoric acid production, high-concentration high-quality phosphoric acid is directly obtained after hydration, the production process is pollution-free, waste is discharged, the production energy consumption and the production cost can be greatly reduced, the furnace-method phosphoric acid production system and the production process are environment-friendly, energy is saved, consumption is reduced, and the comprehensive utilization efficiency of phosphorite resources is extremely high;

the furnace reactor can ensure that the reduction and the oxidation process are completely reacted by adjusting the speed and the amount of air entering the reactor, completely separate the reduction reaction and the oxidation reaction in the reactor, and improve the conversion rate of raw materials and the full utilization of reaction heat;

the bottom structure of the furnace reactor can generate high linear speed, and ensures that the phosphorite mixture particles entering the reactor are fluidized;

the invention adopts the furnace reactor, can directly transfer the oxidation reaction heat in the reactor to the reduction space, realizes energy saving, and can save energy by 50-60 percent compared with the prior art;

furthermore, because the burning is rapid, the reaction time is short, the temperature is high, and various harmful substances are changed or reduced in the high-temperature heating reaction process, the low-grade phosphate ore can be utilized to produce high-concentration high-quality phosphoric acid, and the phosphorous slag can be directly used for producing cement. Solves a worldwide problem. Because the existing phosphorite resources are gradually depleted worldwide, and 15-19% of the low-quality phosphorite is not utilized;

the invention can directly produce phosphoric acid from phosphate ore, the tailings can produce cement, and the byproduct phosphogypsum is not produced, the production flow is greatly simplified, the production cost is greatly reduced, and compared with the prior production technology, the production cost can be reduced by 80-100%;

the invention can use the tail gas produced by the prior yellow phosphorus as a heat source, not only can recover the energy of the yellow phosphorus tail gas, but also can utilize the tail gas to deeply carbonize the phosphorus slag to produce building materials, thereby realizing carbon neutralization;

the invention can produce high-concentration (85%) high-purity phosphoric acid, and its impurity is less than that of wet-process phosphoric acid, so that it can produce phosphate product with higher added value for food grade and new energy battery, and because of high phosphoric acid concentration, it can greatly simplify technological process and reduce investment, and compared with existent technology, it can reduce investment by about 20-30%.

Drawings

FIG. 1 is a schematic view of the apparatus of a furnace-type phosphoric acid production system according to the present invention.

In the figure: a furnace reactor 1, a reduction zone 2, an oxidation zone 3, a primary air inlet 4, a combustion gas inlet 5, a solid material inlet 6, a secondary air inlet 7, a primary air device 8, a combustion gas device 9, a secondary air device 10 and P₂O₅The device comprises a gas outlet 11, a crushing pulverizer 12, a single material bin 13, a mixer 14, a granulator 15, a multi-stage absorption tower 16, a circulating tank 17, a circulating pump 18, a demister 19, a filter press 20, a finished product bin 21, a fan 22, an external PLC (programmable logic controller) 23, a catalytic device 24, a continuous feeder 25 and a mixing bin 26.

Detailed Description

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.

As shown in figure 1, a furnace phosphoric acid production system comprises a front-end feeding component, an intermediate furnace reaction component and a rear-end phosphoric acid preparation component, wherein the intermediate furnace reaction component comprises a furnace reactor 1, the bottom of the furnace reactor 1 is designed to generate high linear velocity, so as to ensure that phosphate rock mixture particles entering the reactor are fluidized, the furnace reactor 1 comprises a reduction zone 2 and an oxidation zone 3, the reduction zone 2 is positioned at the lower part of a furnace body, the oxidation zone 3 is positioned at the upper part of the reduction zone 2, the reduction zone 2 is provided with a primary air inlet 4, a combustion gas inlet 5 and a solid material inlet 6, the oxidation zone 3 is provided with a secondary air inlet 7, the primary air inlet 4 is connected with a primary air device 8, the combustion gas inlet 5 is connected with a combustion gas device 9, the solid material inlet 6 is connected with a material outlet of the front-end feeding component, the secondary air inlet 7 is connected with a secondary air device 10, and the upper part of the oxidation zone 3 is provided with P₂O₅Gas outlet 11, said P₂O₅The gas outlet 11 is connected with the gas inlet of the phosphoric acid preparation assembly at the rear endAnd (4) a mouth.

The front end feeding assembly comprises three groups of crushing mills 12 and single material bins 13 for respectively crushing phosphate ore, coal or coke and silica, the material outlets of the crushing mills 12 of each group are connected with the corresponding single material bins 13, the material outlets of the single material bins 13 are connected with a mixer 14 for uniformly mixing raw materials, the discharge port of the mixer 14 is connected with a granulator 15, and the discharge port of the granulator 15 is connected with the solid material inlet 6 of the reduction zone 2 through a continuous feeder 25.

The rear-end phosphoric acid preparation component comprises a multi-stage absorption tower 16, a circulating tank 17, a circulating pump 18, a demister 19, a filter press 20 and a finished product bin 21, wherein an air inlet of the multi-stage absorption tower 16 is connected with P of the oxidation zone 3₂O₅The system comprises a gas outlet 11, a liquid outlet of a multi-stage absorption tower 16 is connected with a circulating tank 17 through a pipeline, the circulating tank 17 is provided with a circulating pump 18, the outlet of the circulating pump 18 is connected with a finished product bin 21 through a filter press 20, the filter press 20 is used for filter-pressing tailings into blocks, cement and the like can be produced from the agglomerated tailings, waste discharge is greatly reduced, a waste gas outlet of the multi-stage absorption tower 16 is connected with a demister 19, a foam catching device is arranged in the demister 19, the tail gas discharged from the absorption tower 16 is discharged after acid mist is removed through the demister 19 and reaches the standard, and only the demister 19 discharges the tail gas after reaching the standard in the whole process, so that the system has little environmental pollution.

The combustion gas device 9 is internally provided with a gas distributor, a flow meter and a regulating valve, the primary air device 4 and the secondary air device 10 are respectively provided with the gas distributor, the flow meter, the regulating valve and a fan 22, the regulating valve is simultaneously connected with an external PLC (programmable logic controller) 23, the fan 22 is also connected with the external PLC, the continuous feeder 15 is provided with a weighing sensor and a variable frequency motor, the variable frequency motor is connected with the external PLC 23, and the weighing sensor and the variable frequency motor form a closed-loop control weightless scale.

The bottom of the furnace reactor 1 is provided with a catalytic device 24 for catalyzing the reaction in the furnace, and the catalyst in the catalytic device 24 can increase the reaction rate in the furnace by several times.

The inner wall of the furnace method reactor 1 is provided with a fireproof heat insulation layer, the fireproof heat insulation layer is used for preventing heat in the furnace from radiating outside the furnace, reduction and oxidation reactions are completed in the furnace method reactor 1, the reduction reactions are endothermic reactions, most of the heat is provided by combustion gas provided by a combustion gas device, the oxidation reactions are exothermic reactions (the oxidation reactions are equivalent to combustion of white phosphorus, so that a large amount of heat can be generated), and nearly half of the heat in an oxidation reaction area in the furnace method reactor 1 can be transferred to a reduction area for the reduction reactions to utilize in a radiation mode, so that the consumption of the gas can be greatly reduced.

The invention also provides a furnace-method phosphoric acid production process, which comprises the following steps:

1) crushing and mixing raw materials: the phosphate ore, the coke and the silica are sent into respective crushing mills by a grab bucket to be crushed and ground to prepare particles with the granularity of less than 0.2mm, the ground phosphate ore, the coke and the silica are respectively sent into respective single material bins, and the phosphate ore, the coke and the silica are weighed according to the preparation proportion and then are sent into a mixer to be uniformly mixed;

2) granulating and feeding: the mixed material is sent into a granulator for granulation, the granularity of the granulated material is less than 4mm, the granulated material enters a mixing bin and a continuous feeder, the continuous feeder is a closed-loop control weightless scale, the metering precision is less than 1%, and the material continuously enters a furnace reactor according to the set feeding flow for reduction and oxidation reaction;

3)P₂O₅preparing gas: the continuous feeder sends the mixed material into a reduction zone in a furnace through a solid material inlet of a furnace reactor, a primary air device quantitatively feeds air into the reduction zone, a combustion gas device quantitatively feeds gas into the reduction zone, the gas and oxygen in the air are combusted to provide energy for reducing phosphorus simple substances, a flame zone formed by combustion of the gas and the oxygen in the air forms an independent reduction zone, the phosphorus simple substances subjected to reduction reaction float upwards under the action of high flame pressure to enter an oxidation zone, a secondary air device in the oxidation zone feeds quantitative air, and the phosphorus simple substances are oxidized to generate P₂O₅Gas, said P₂O₅Gas passing through the upper part of the oxidation zoneP₂O₅The gas outlet enters a rear-end phosphoric acid preparation component for hydration absorption to prepare phosphoric acid liquid with quantitative concentration;

4) preparing phosphoric acid solution: p generated after the material finishes reaction in the furnace reactor₂O₅The gas enters an absorption tower after heat exchange by a heat exchanger to complete absorption hydration, and enters P in the absorption tower₂O₅The gas temperature is controlled at 800 ℃ and 1000 ℃, P₂O₅The gas is changed into phosphoric acid after hydration and absorption, and then the phosphoric acid enters a circulating tank and then enters an absorption tower through a circulating pump to repeatedly absorb P₂O₅Reaching the set phosphoric acid concentration and the phosphoric acid spraying temperature<And (4) removing acid mist from tail gas discharged from the absorption tower through a demister, discharging the tail gas after reaching the standard, conveying impurities contained in the phosphoric acid reaching the required concentration into a filter press through a circulating pump, removing residues, and feeding the residues into a finished product bin.

In the step 3), the reaction temperature in the furnace reactor is controlled at 1200-1500 ℃, the oxygen content of the air entering the furnace reactor from the primary air device (13) and the secondary air device is more than 10%, the speed and the flow of the air entering the furnace reactor are controlled by adjusting the adjusting valves and the fans in the primary air device and the secondary air device, so that the reaction of the reduction zone and the oxidation zone is complete, the reduced phosphorus is completely combusted in the air, and the reduction zone and the oxidation zone in the furnace reactor are separated.

The primary air device, the secondary air device, the combustion gas device and the weightlessness scale are respectively controlled by an external PLC controller for use.

Example one

This furnace method phosphoric acid production system includes: the reaction is carried out in the furnace reactor 1 by using a ground mill 12 and a single bunker 13 for phosphate ore, a ground mill 12 and a single bunker 13 for coal or coke, a ground mill 12 and a single bunker 13 for silica, a mixer 14 for uniformly mixing the respective raw materials, a granulator 15, and a continuous feeder 25. Phosphoric acid from the multistage absorption tower 16 passes through a circulation tank 17, a circulation pump 18 and a filter press 20 and then enters a finished product bin 21, and tail gas is discharged after passing through a demister 19.

When in use, the phosphate rock, coke and silica are fed into the storage bins by the grab bucket, and then are fed into respective crushing mills 12 to be crushed and ground to prepare the phosphate rock with the granularity of less than 0.2mm, the ground phosphate rock, coke and silica are respectively fed into respective single material storage bins 13, the phosphate rock, the coke and the silica are weighed according to the preparation proportion and then are fed into a mixer 14 to be uniformly mixed, the mixed material is fed into a granulator 15 to be granulated, the granulated material has the granularity of less than 4mm, the granulated material is fed into a mixing storage bin 26 and a continuous feeder 25, the continuous feeder 25 is a weightlessness weighing system, the metering precision is less than 1 percent, and the material is continuously fed into the furnace reactor 1 to be subjected to reduction and oxidation reaction according to the set requirement. The required heat is provided by a combustion gas device 9, a primary air device 8 and a secondary air device 10, in order to strengthen the reaction process, a catalytic device 24 is arranged, P2O5 gas generated after the materials finish the reaction in a furnace reactor 1 enters a multi-stage absorption tower 16 after heat exchange through a heat exchanger to finish absorption hydration, the temperature of the P2O5 gas entering the multi-stage absorption tower 16 is controlled at 800-. After reaching the required concentration, the phosphoric acid contains a small amount of impurities, and is sent to a filter press 20 through a circulating pump 18, and then residues are removed and enter a finished product bin 21.

Example two

The furnace-method phosphoric acid production system comprises a continuous feeder 25 which is connected with a solid material inlet 6 at the lower part of a furnace-method reactor 1 through a discharging pipe, a combustion gas device 9 which consists of a gas flowmeter and an adjusting valve and is connected with the furnace-method reactor 1 through a pipeline, a primary air device 8 which consists of a gas flowmeter and an adjusting valve and is connected with the upper part of a discharge hole of the furnace-method reactor 1 through a pipeline, and a gas distributor is arranged at the connection position. The secondary air device 10 consists of a gas flowmeter and a regulating valve, is connected with the upper part of the feed inlet of the furnace reactor 1 through a pipeline, and is provided with a gas distributor at the joint. The catalytic device 24 is connected with the furnace reactor 1 through a nozzle, and the weightlessness scale in the continuous feeder 25, the gas flow meter and the adjusting valve in each device are connected with the external PLC controller 23 through communication cables.

When in use, the coke is mixed according to the theoretical amount of 105-110 percent, the silica amount is calculated according to the SiO2/CaO of 0.75-0.85, the phosphate ore, the coke and the silica are mixed according to the mixture ratio and granulated, then the mixture is continuously fed into the furnace reactor 1 according to the set flow rate by the continuous feeder 25, and the reduction oxidation reaction is carried out according to the following chemical reaction formula under the action of combustion gas and oxygen to generate gas containing P2O 5.

Ca₃(PO₄)₂+5C+3SiO₂→P₂↑+5CO↑+3CaSiO₃

2CaF₂+3SiO₂→2CaSiO₃+SiF₄↑

P₂+5/2O₂→P₂O₅

5CO+5/2O₂→5CO₂

The valves in the primary air device 8 are adjusted to allow air to enter from the bottom of the furnace reactor 1 at a high linear velocity to ensure fluidization of the solid material particles. The reaction temperature in the furnace reactor 1 was controlled at 1200-1500 ℃. To ensure complete reaction and complete combustion of phosphorus in air, the oxygen content of the air entering the furnace reactor 1 from the fans 22, the primary air device 8 and the secondary air device 10 is > 10%, and the air velocity entering the furnace reactor 1 is controlled by adjusting the valves and fans in the primary air device 8 and the secondary air device 10, and the flow rate separates the reduction zone and the oxidation zone in the furnace reactor 1.

The capacity in the furnace reactor 1 can be increased by 2-4 times by adjusting the current, voltage and nozzle in the catalytic device 24, and the weightlessness scale in the continuous feeder 25, the valve and fan in the combustion gas device 9, the valve and fan in the primary air device 8, and the valve and fan in the secondary air device 10 are all automatically adjusted and controlled by the external PLC controller 23 according to the set parameters by the computer.

The system equipment structure and the production process are integrated. The furnace-method phosphoric acid production system and the production process are completely different from the existing phosphoric acid production equipment, can directly produce high-concentration phosphoric acid by using phosphate ore without using purification equipment, can greatly reduce energy consumption and production cost, have no pollutant discharge, can fully utilize low-grade phosphate ore, and meet the requirements of energy conservation, energy saving, carbon neutralization and comprehensive utilization of resources.