Production process for co-producing tricalcium phosphate and yellow phosphorus by using phosphate ore

Abstract

The invention relates to the technical field of chemical production, and particularly discloses a production process for co-producing tricalcium phosphate and yellow phosphorus by using phosphate ore, which comprises six operation steps of reverse flotation magnesium removal, reverse flotation desilicication, tailing concentration and ball pressing, yellow phosphorus production from tailings, concentrate concentration and drying, and TCP production from concentrate. Low-quality phosphate ores with high silicon content are divided into tailings and concentrates through magnesium removal and desilicication treatment, the concentrates are concentrated, dehydrated, dried, mixed with sodium salt, ground and granulated and then fed into a rotary kiln to be calcined to generate TCP, yellow phosphorus is generated after the tailings are subjected to a series of treatment, the problem that existing phosphate ore resources are insufficient is solved, and the utilization rate of the phosphate ore resources is increased. And moreover, low-quality phosphorite resources are utilized to produce TCP and yellow phosphorus, so that the input cost of TCP production is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical production, and particularly relates to a production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock. Background Art

[0002] Tricalcium phosphate, usually also known as calcium phosphate, is an inorganic compound with the chemical formula Ca3(PO4)2, abbreviated as TCP. TCP is commonly used as an anti-caking agent, buffer, moisture-holding agent, acidity regulator, stabilizer, and nutritional fortifier, etc. in the food industry. It can help strengthen the calcium content in food and prevent or treat calcium deficiency symptoms.

[0003] The existing production method of TCP is to place phosphate rock into a rotary kiln for high-temperature calcination to produce defluorinated tricalcium phosphate. This calcination method has certain requirements for the silicon content in phosphate rock. The silicon content in phosphate rock cannot be higher than 4%. Phosphate rock with a silicon content higher than 4% is prone to sticking, which greatly increases the calcination difficulty of the rotary kiln and is not conducive to the production and capacity expansion of TCP. However, with the continuous development and utilization of phosphate rock resources, the phosphate rock resources are further depleted, resulting in a continuous decrease in the phosphorus content and an increase in the silicon content in the existing phosphate rock resources. Low-grade phosphate rock resources cannot meet the production requirements of TCP. Furthermore, the raw material supply for directly using the rotary kiln to calcine and produce TCP is insufficient. More costs need to be invested in purchasing high-grade phosphate rock to meet the existing TCP production requirements, while low-grade phosphate rock cannot be utilized, causing resource waste. Summary of the Invention

[0004] The purpose of the present invention is to provide a production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock, so as to solve the problems that low-grade phosphate rock resources cannot meet the production requirements of TCP, resulting in resource waste and an increase in the production cost of TCP.

[0005] To solve the above problems, the following technical solutions are provided:

[0006] A production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock, comprising the following steps:

[0007] S1: Reverse flotation for magnesium removal: After crushing, screening, and slag separation of low-quality phosphate rock, water is added and stirred to obtain a raw material pulp. Subsequently, the raw material pulp is introduced into a beneficiation machine, and a magnesium removal agent is added to the beneficiation machine for two-stage reverse flotation magnesium removal treatment. After the magnesium removal treatment, the tailings with magnesium elements are taken away by foam from the upper part of the beneficiation machine, and the first-stage concentrate after the magnesium removal treatment flows out from the lower part of the beneficiation machine;

[0008] S2: Reverse flotation desilication: The first-stage concentrate after magnesia removal is fed into a stirring tank and mixed with water to adjust its concentration. The first-stage concentrate with adjusted concentration is introduced into a concentrator, and desilication agents are added. The first-stage concentrate undergoes two-stage reverse flotation desilication to separate tailings and the second-stage concentrate. After desilication, the tailings with silicon elements are carried away by foam from the upper part of the concentrator, and the second-stage concentrate after desilication flows out from the lower part of the concentrator.

[0009] S3: Tailings thickening and pelletizing: The tailings from steps S1 and S2 enter the tailings tank for defoaming treatment. After defoaming, the tailings are fed into a thickener for sedimentation. The sedimented tailings are dehydrated and dried. Then, the dried tailings powder is mixed with silica, and an appropriate amount of water is added. After being evenly mixed in a mixing agitator, pelletizing and drying treatments are carried out to form pelletized ore, which is finally transported to the storage yard for storage through a belt.

[0010] S4: Producing yellow phosphorus from tailings: The pelletized ore after pelletizing treatment and coke are added into a yellow phosphorus furnace together, and yellow phosphorus is produced by electrothermal method in the yellow phosphorus furnace.

[0011] S5: Concentrate thickening and drying: The second-stage concentrate after desilication is fed into a thickener for sedimentation treatment. The sedimented second-stage concentrate undergoes dehydration and drying treatments.

[0012] S6: Producing TCP from concentrate: The dried second-stage concentrate is mixed with sodium salt to form a mixed material. The mixed material is fed into a ball mill for grinding through a metering belt. The ground mixed ore powder is granulated by adding raffinate acid, and finally sent to a rotary kiln for calcination to produce TCP.

[0013] The beneficial effects of the above technical solutions are as follows: By means of magnesia removal and desilication treatments, low-quality phosphate ores with a relatively high silicon content are divided into tailings and concentrate. After the concentrate is concentrated, dehydrated, dried, mixed with sodium salt, ground and granulated, it is sent to a rotary kiln for calcination to produce TCP, while the tailings are processed through a series of steps to produce yellow phosphorus. This not only solves the problem of insufficient existing phosphate ore resources, but also utilizes low-quality phosphate ore resources to produce TCP and yellow phosphorus, saving the input cost for producing TCP.

[0014] Further, the concentration of the raw ore pulp in step S1 is controlled between 20% - 40%, the particle size of the flotation feed meets the requirement that the proportion of the 200-mesh particle size accounts for 50% - 70%, the magnesium content in the concentrate after magnesia removal is < 1% w, P2O5 ≥ 32% w, and SiO2 ≤ 10% w.

[0015] Further, the pulp concentration in step S2 is controlled between 20% - 30%, the pulp residence time is 5 - 15 minutes, and the mass fraction of the concentrate after desilication is P2O5 ≥ 36% w and SiO2 ≤ 4% w.

[0016] Further, in the defoaming method of step S3, a high-pressure water gun and a defoaming agent are used in combination for defoaming. In particular, after the defoaming agent is diluted about 3 - 6 times, it is atomized and sprayed using a nozzle.

[0017] Further, the temperature in the yellow phosphorus furnace in step S4 is controlled at 1500 - 2500 °C.

[0018] Further, in step S5, the heat source for the drying treatment is the tail gas discharged from the yellow phosphorus furnace in step S4.

[0019] Further, in step S6, the sodium salt is composed of one or more of soda ash, mirabilite, sodium chloride, and baking soda.

[0020] Further, the temperature in the rotary kiln in step S6 is controlled at 1500 - 2000 °C.

[0021] Further, the magnesium removal agent in step S1 is Wengfu No. 1 agent, and Wengfu No. 1 agent is a sodium dodecyl sulfonate solution; the silicon removal agent in step S2 is a reverse flotation collector, and the reverse flotation collector is a sodium fluorosilicate solution. The sodium dodecyl sulfonate solution can selectively adsorb on the surface of magnesium minerals, making them hydrophobic and floating; the sodium fluorosilicate solution can selectively inhibit apatite, making it stay in the trough while the silicate minerals float. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic process flow diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0023] The following is further detailed through specific embodiments:

[0024] The embodiment is basically as shown in the Figure 1 drawing:

[0025] The specific implementation process is as follows:

[0026] A production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock includes the following steps:

[0027] S1: Reverse flotation for magnesium removal: Take low-quality phosphate rock with a phosphorus pentoxide content of 19.73% and a silicon content of 6.26%. After crushing, screening, and slag separation, add water to the agitation tank and stir to obtain the raw material pulp. Control the concentration of the raw material pulp between 20% and 40%. Subsequently, add the Wengfu No. 1 reagent, sodium dodecyl sulfonate solution, to the agitation tank for two-stage reverse flotation for magnesium removal. The Wengfu No. 1 reagent has an affinity for magnesium. After adding the Wengfu No. 1 reagent, the raw material pulp stays in the agitation tank for 5 minutes, then undergoes crushing and screening again. At this time, the particle size of the flotation feed meets the requirement that the proportion of the 200-mesh particle size accounts for 50%-70%. Introduce the raw material pulp into the first concentrator to separate the tailings and the first-stage concentrate. The tailings carry magnesium and are taken away by foam from the upper part of the first concentrator. The separated tailings are stored in the tailings pond. The first-stage concentrate flows out from the lower part of the first concentrator. At this time, the magnesium content in the first-stage concentrate is less than 1% w, the P2O5 content is 32.1% w, and the SiO2 content is 8.29% w. If the above content is not reached, repeat the aforementioned magnesium removal steps for treatment;

[0028] S2: Reverse flotation for silicon removal: Feed the first-stage concentrate after magnesium removal treatment into the agitation tank, add water and stir to adjust its concentration between 20% and 30%. After adjusting the concentration, add the reverse flotation collector, sodium fluorosilicate solution, to the agitation tank. The reverse flotation collector has an affinity for silicon. After adding the reverse flotation collector, the first-stage concentrate stays in the agitation tank for 5 minutes. Introduce the previously treated first-stage concentrate into the second concentrator to separate the tailings and the second-stage concentrate. The tailings carry silicon and are taken away by foam from the upper part of the second concentrator. The tailings separated by the second concentrator are also stored in the tailings pond, and the second-stage concentrate flows out from the lower part of the second concentrator;

[0029] S3: Tailings thickening and briquetting: The tailings from steps S1 and S2 enter the tailings tank for defoaming treatment. The defoaming method uses a high-pressure water gun and defoaming agent in combination for defoaming. After the defoaming agent is diluted about 3-6 times, it is atomized and sprayed using a nozzle. After defoaming is completed, the tailings are sent to the first thickener for sedimentation. At this time, the P2O5 content in the tailings is 28.13%, the SiO2 content is 18.24%, and the tailings concentration is 45%. The sedimented tailings are transported through a pipeline to the first plate and frame filter press. After plate and frame filtration, the moisture is dried to 5% by a dryer. Then, mix the dried tailings powder with silica in a stirrer, add an appropriate amount of water, and after uniform mixing in the mixing stirrer, transport it through a pipeline to a briquetting machine for briquetting treatment to form briquette ore, and finally transport it to the storage yard for storage by belt;

[0030] S4: Producing yellow phosphorus from tailings: The pelletized ore after pelletizing treatment and coke are added into the yellow phosphorus furnace together. The temperature of the yellow phosphorus furnace is controlled at 1500 - 2500 °C. Coke has a reducing effect and can reduce the elemental phosphorus in the pelletized ore. Silica is used as a flux and is calcined by the electrothermal method in the yellow phosphorus furnace for 4 - 6 hours to produce yellow phosphorus. The pelletized ore has uniform particle size and high strength, can utilize the tailings powder, and does not require additional mixing of phosphoric acid, reducing the production cost;

[0031] S5: Concentrating and drying the concentrate: The secondary concentrate after desilication in step S2 is sent to the second thickener for sedimentation and concentration treatment. The content of P2O5 in the secondary concentrate after sedimentation and concentration is 36.11%, the content of SiO2 is 3.03%, and the concentration of the secondary concentrate is 60%. The concentrated concentrate is transported through a pipeline to the second plate and frame filter press for further dehydration treatment. The water content of the secondary concentrate after dehydration is 12%. Then, it enters the dryer to dry the secondary concentrate, and the tail gas discharged from the yellow phosphorus furnace in step S4 is used as the heat source of the dryer;

[0032] S6: Producing TCP from the concentrate: The dried secondary concentrate and sodium salt are mixed into a mixture. The sodium salt is composed of one or more of soda ash, mirabilite, sodium chloride, and baking soda. The mixture is sent to the ball mill for grinding through a metering belt. The ground mixed ore powder is granulated by adding the raffinate acid. The raffinate acid can supplement and increase the phosphorus content in the secondary concentrate. Finally, it is sent to the rotary kiln for calcination for 4 - 6 hours to produce TCP. During this period, the temperature of the rotary kiln is controlled at 1500 - 2000 °C. The tail gas of the dryer in step S5 is discharged into the rotary kiln to supplement the heat source of the rotary kiln, saving energy. At the same time, pulverized coal is added to the rotary kiln as the fuel of the rotary kiln.

[0033] This technical solution classifies the low-quality phosphate rock with a high silicon content into tailings and concentrate through demagnesium and desilication treatments. After the concentrate is concentrated, dehydrated, dried, mixed with sodium salt, ground, and granulated, it is sent to the rotary kiln for calcination to produce TCP, while the tailings are processed through a series of processes to produce yellow phosphorus. It not only solves the problem of insufficient existing phosphate rock resources, but also utilizes the low-quality phosphate rock resources to produce TCP and yellow phosphorus, saving the input cost of producing TCP.

[0034] The above are only the embodiments of the present invention. Common general knowledge such as the specific structures and characteristics in the solution is not described in detail here. It should be noted that for those skilled in the art, without departing from the structure of the present invention, several deformations and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the implementation effect of the present invention and the practicality of the patent. The protection scope required by this application should be subject to the content of its claims, and the specific implementation manners and the like recorded in the specification can be used to interpret the content of the claims.

Claims

1. A production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock, characterized in that: The following steps are involved: S1: Reverse flotation demagnesization: After crushing, screening and slag separation of low-quality phosphate ore, water is added and stirred to obtain raw ore pulp. Subsequently, the raw ore pulp is introduced into the concentrator, and demagnesization reagents are added into the concentrator for two-stage reverse flotation demagnesization treatment. After demagnesization treatment, the tailings with magnesium elements are taken away by foam from the upper part of the concentrator, and the primary concentrate after demagnesization treatment flows out from the lower part of the concentrator; S2: Reverse flotation desiliconization: The first-level concentrate after magnesium removal is sent to the stirring tank and water is added to adjust its concentration. The first-level concentrate after concentration adjustment is introduced into the concentrator, and desiliconization reagent is added. The first-level concentrate undergoes two-stage reverse flotation desiliconization treatment to separate tailings and secondary concentrate. After desiliconization treatment, the tailings with silicon elements are taken away by foam from the upper part of the concentrator, and the secondary concentrate after desiliconization flows out from the lower part of the concentrator; S3: Tailings concentration and briquetting: The tailings from steps S1 and S2 are all put into the tailings tank for defoaming treatment. After the defoaming is completed, the tailings are sent to the thickener for sedimentation. The settled tailings are dehydrated and dried. Then, the dry tailings powder is mixed with silica, and an appropriate amount of water is added. After uniform mixing in a mixer, the tailings are briquetting and drying to form pellets, which are finally transported to the storage yard by belt conveyor for storage; S4: Production of yellow phosphorus from tailings: The pelletized ore and coke are added to a yellow phosphorus furnace, where yellow phosphorus is produced by an electric heating method; S5: Concentration and drying of concentrate: The secondary concentrate after desiliconization is sent to the thickener for sedimentation. The secondary concentrate after sedimentation is dehydrated and dried; S6: Concentrate production TCP: The dried secondary concentrate is mixed with sodium salt to form a mixed material, which is then sent to a ball mill for grinding through a metering belt. The ground mixed ore powder is added with residual acid for granulation and finally sent to a rotary kiln for calcination to produce TCP.

2. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 1, characterized in that: The raw material slurry concentration of step S1 is controlled between 20% and 40%, the flotation feed particle size meets the 200 mesh particle size accounting for 50% to 70%, the magnesium content of the concentrate after demagnesium removal is less than 1%w, P2O5≥32%w, and SiO2≤10%w.

3. A production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 2, characterized in that: In step S2, the slurry concentration is controlled between 20% and 30%, the slurry residence time is 5 to 15 minutes, and the mass fraction of the concentrate after desiliconization is calculated as P2O5 ≥ 36% w and SiO2 ≤ 4% w.

4. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 3, characterized in that: The defoaming method in step S3 is to use a high-pressure water gun and a defoaming agent to defoam. In particular, after the defoaming agent is diluted about 3-6 times, a nozzle is used for mist spraying.

5. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 4, characterized in that: In step S4, the temperature of the yellow phosphorus is controlled at 1500-2500°C.

6. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 5, characterized in that: The heat source for the drying process in step S5 is the tail gas discharged from the yellow phosphorus furnace in step S4.

7. A production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 6, characterized in that: In step S6, the sodium salt is composed of one or more of soda ash, sodium sulfate, sodium chloride and baking soda.

8. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 7, characterized in that: In step S6, the temperature of the rotary kiln is controlled at 1500-2000°C.

9. The production process for co-producing tricalcium phosphate and yellow phosphorus using phosphate rock according to claim 1, characterized in that: The demagnesizing agent in step S1 is Wengfu No. 1 agent, which is a sodium dodecyl sulfate solution; The desiliconization agent in step S2 is a reverse flotation collector, and the reverse flotation collector is a sodium fluorosilicate solution.

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