Device for circularly decomposing phosphorite by acidifying ammonium sulfate

Abstract

The utility model relates to the technical field of phosphorite decomposition, and particularly provides an ammonium sulfate acidifying and circularly decomposing phosphorite device which comprises a pre-decomposition reaction tank, an acidolysis reaction tank, a first filter, a desulfurization reaction tank, a second filter, an acidolysis dephosphorization reaction tank and a third filter which are sequentially connected through pipelines and pumps, wherein the pre-decomposition reaction tank is provided with a phosphoric acid feeding port, the acidolysis reaction tank is provided with an acidified ammonium sulfate feeding port, filter residues of the first filter are conveyed to the acidolysis reaction tank through a conveying belt, the desulfurization reaction tank is provided with a phosphorite feeding port, and filter residues of the second filter are conveyed to the pre-decomposition reaction tank through a conveying belt. Filter residues of the third filter are conveyed out of the ardealite through a conveying belt. Phosphorite is decomposed through acidified ammonium sulfate, a crude ammonium phosphate solution and ardealite can be obtained, impurities of a product are continuously removed through raw materials subsequently, the content of sulfate radicals in the ammonium phosphate solution can be reduced, and agricultural monoammonium can be directly produced on the downstream. The content of phosphorus pentoxide in the phosphogypsum can also be reduced.

Description

Technical Field

[0001] This utility model belongs to the field of phosphate rock decomposition technology and relates to an acidified ammonium sulfate circulating decomposition device for phosphate rock. Background Technology

[0002] Currently, the decomposition of phosphate rock mostly employs the wet phosphoric acid process, which uses sulfuric acid, nitric acid, or hydrochloric acid to decompose phosphate rock to obtain phosphoric acid. Wet phosphoric acid production generates a large amount of phosphogypsum, which, in addition to its main component calcium sulfate dihydrate, also contains incompletely decomposed phosphate rock, residual phosphoric acid, fluorides, acid-insoluble substances, and organic matter. The phosphorus pentoxide content in phosphogypsum is generally between 1% and 2%. When phosphogypsum is deposited by rainwater, it produces leachate with a high phosphorus content. If this leachate flows into natural water bodies, it can lead to eutrophication, weaken oxygen-enriching capacity, reduce aquatic biomass, and harm water resources and the ecological environment.

[0003] The higher the phosphorus content in phosphogypsum, the greater the environmental pollution and the more difficult it is to treat. As the country places increasing emphasis on environmental protection, how to reduce and utilize the phosphorus resources in phosphogypsum is a question that everyone in the chemical industry needs to consider.

[0004] In the production of phosphate compound fertilizers, sulfuric acid is often used to decompose phosphate rock. Sulfuric acid provides the acidic conditions for decomposing the phosphate rock and also acts as a calcium precipitant, separating calcium from the phosphate rock to form phosphogypsum. Phosphogypsum can then be used to prepare ammonium sulfate or potassium sulfate. Although ammonium sulfate does not have the ability to decompose phosphate rock, it has the advantage of making the separation of phosphorus and calcium from phosphate rock relatively simple. If it is first acidified before being used to decompose phosphate rock to prepare ammonium phosphate fertilizers, the problem of wet recycling of sulfur in phosphate chemical production can be solved, saving sulfuric acid usage and effectively utilizing the sulfur resources byproducts of phosphate chemical enterprises. Summary of the Invention

[0005] This invention provides an acidified ammonium sulfate circulating decomposition device for phosphate rock. The phosphate rock is decomposed by acidified ammonium sulfate to obtain crude ammonium phosphate solution and phosphogypsum. The raw materials are then used to further remove impurities from the products, which can reduce the sulfate content in the ammonium phosphate solution. The downstream products can be directly used to produce agricultural monoammonium phosphate. It can also reduce the phosphorus pentoxide content in phosphogypsum.

[0006] The technical solution of this utility model is to provide an acidified ammonium sulfate circulating decomposition device for phosphate rock, comprising a pre-decomposition reaction tank, an acidification reaction tank, a first filter, a desulfurization reaction tank, a second filter, an acidified dephosphorization reaction tank, and a third filter connected in sequence by pipelines and pumps; wherein the pre-decomposition reaction tank is provided with a phosphoric acid feed port, the acidification reaction tank is provided with an acidified ammonium sulfate feed port, the filter residue of the first filter is conveyed to the acidification reaction tank by a conveyor belt, the desulfurization reaction tank is provided with a phosphate rock feed port, the filter residue of the second filter is conveyed to the pre-decomposition reaction tank by a conveyor belt, and the filter residue of the third filter is conveyed to the external phosphogypsum via a conveyor belt.

[0007] Furthermore, the device also includes an acid buffer tank, the filtrate outlet of the third filter is connected to the inlet of the acid buffer tank, and the outlet of the acid buffer tank is connected to the inlet of the acidolysis reaction tank via a pipeline and a pump.

[0008] Furthermore, the device also includes a crude ammonium phosphate solution buffer tank, the filtrate outlet of the first filter is connected to the feed inlet of the crude ammonium phosphate solution buffer tank, and the discharge outlet of the crude ammonium phosphate solution buffer tank is connected to the feed inlet of the desulfurization reaction tank via a pipeline and a pump.

[0009] Furthermore, the device also includes a phosphate ammonium filtrate buffer tank, the filtrate outlet of the second filter is connected to the inlet of the phosphate ammonium filtrate buffer tank, and the outlet of the phosphate ammonium filtrate buffer tank is connected to the inlet of the acid dephosphorization reaction tank via a pipeline and a pump.

[0010] Furthermore, the ammonium phosphate filtrate buffer tank is also equipped with an ammonium phosphate feed outlet.

[0011] Furthermore, the acid dephosphorization reaction tank is also equipped with a sulfuric acid feed port.

[0012] Furthermore, the first filter, the second filter, and the third filter are all plate and frame filters.

[0013] Furthermore, the pre-decomposition reaction tank, acid hydrolysis reaction tank, desulfurization reaction tank, and acid dephosphorization reaction tank are all closed containers, and are equipped with stirring components inside.

[0014] Furthermore, the driving device for the stirring assembly is an explosion-proof motor.

[0015] This utility model has the following beneficial effects:

[0016] The apparatus provided by this invention can decompose phosphate rock using ammonium sulfate acidification, reducing sulfuric acid consumption. Further treatment of the acidified slag with acid reduces the phosphorus content in phosphogypsum. Adding phosphate rock to the filtrate after acidification further desulfurizes the phosphate rock, reducing the sulfate content in the ammonium phosphate solution, making it directly usable for the preparation of monoammonium phosphate (MAP) in agriculture. The desulfurized phosphate rock is pretreated with phosphoric acid in a pre-decomposition reaction tank before being introduced into the acidification reaction tank for more thorough acidification.

[0017] The entire phosphate rock decomposition equipment does not involve high-temperature and high-pressure processes, and has low requirements for equipment structure, materials, and operation, ensuring the safety of the production environment. The reagents used in the reaction process are all phosphoric acid, sulfuric acid, and ammonium sulfate, which will not introduce new impurities. The process generates no waste gas or waste liquid, reducing consumption and lowering costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of this utility model. Detailed Implementation

[0019] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.

[0020] like Figure 1 As shown, this utility model provides an acidification ammonium sulfate circulating decomposition device for phosphate rock, including a pre-decomposition reaction tank 1, an acidification reaction tank 2, a first filter 3, a desulfurization reaction tank 5, a second filter 6, an acidification dephosphorization reaction tank 8, and a third filter 9 connected in sequence by pipes and pumps; wherein the pre-decomposition reaction tank is provided with a phosphoric acid feed port, the acidification reaction tank is provided with an acidification ammonium sulfate feed port, the filter residue of the first filter is conveyed to the acidification reaction tank by a conveyor belt, the desulfurization reaction tank is provided with a phosphate rock feed port, the filter residue of the second filter is conveyed to the pre-decomposition reaction tank by a conveyor belt, and the filter residue of the third filter is conveyed to the phosphogypsum externally by a conveyor belt.

[0021] In some embodiments, the apparatus further includes an acid buffer tank 10, with the filtrate outlet of the third filter connected to the inlet of the acid buffer tank, and the outlet of the acid buffer tank connected to the inlet of the acidolysis reaction tank via a pipeline and pump. In a preferred embodiment, a sulfuric acid feed port can also be provided in the acidolysis dephosphorization reaction tank. The phosphate slag after the acidolysis reaction undergoes further dephosphorization treatment, specifically by adding purified ammonium phosphate solution and a certain amount of sulfuric acid to remove phosphorus from the phosphate slag. The resulting reaction filtrate can be reused in the acidolysis process, preventing phosphorus loss. Simultaneously, the reduced phosphorus content in the phosphogypsum also facilitates its reuse.

[0022] In some embodiments, the apparatus further includes a crude ammonium phosphate solution buffer tank 4. The filtrate outlet of the first filter is connected to the inlet of the crude ammonium phosphate solution buffer tank, and the outlet of the crude ammonium phosphate solution buffer tank is connected to the inlet of the desulfurization reaction tank via a pipeline and a pump. This portion of the filtrate is temporarily stored and then sent to the desulfurization reaction tank 5, where phosphate rock is used as the calcium source to remove sulfur from the filtrate.

[0023] In some embodiments, the apparatus further includes a phosphate ammonium filtrate buffer tank 7. The filtrate outlet of the second filter is connected to the inlet of the phosphate ammonium filtrate buffer tank, and the outlet of the phosphate ammonium filtrate buffer tank is connected to the inlet of the acid dephosphorization reaction tank via a pipeline and pump. This portion of the filtrate has a high phosphate ammonium content and can be discharged directly, or a portion can be added to the acid dephosphorization reaction tank along with a certain amount of sulfuric acid to effectively remove phosphorus from the filter residue of the first filter. In a more preferred embodiment, the phosphate ammonium filtrate buffer tank is also provided with a phosphate ammonium solution outlet. After a period of reaction, the phosphate ammonium solution is collected from this outlet and can be directly used in the production of agricultural fertilizers.

[0024] In some embodiments, the first filter, the second filter, and the third filter are all plate and frame filters. This offers high processing efficiency and relatively low investment.

[0025] In some embodiments, the pre-decomposition reaction tank, acidolysis reaction tank, desulfurization reaction tank, and acidolysis-phosphorus reaction tank are all sealed containers, each equipped with a stirring assembly. The reaction temperature is approximately 90°C, but does not involve high-temperature or high-pressure conditions. More preferably, in a lower embodiment, the driving device for the stirring assembly is an explosion-proof motor.

[0026] When using the above-mentioned device to decompose phosphate rock by acidification with ammonium sulfate, the process involves using sulfuric acid to acidify and decompose the phosphate rock with ammonium sulfate, and using sulfuric acid and phosphate rock to remove impurities from the subsequent products. The main steps include pre-decomposition, acidolysis mixing, desulfurization, and dephosphorization.

[0027] Step 1: Pre-decomposition

[0028] Phosphoric acid is transported to the pre-decomposition reaction tank, and phosphate rock is transported to the pre-decomposition reaction tank via a conveyor belt. After being stirred evenly, the reaction is carried out for 30 minutes. The resulting phosphate rock slurry is then pumped into the acid hydrolysis reaction tank.

[0029] Step 2: Acid hydrolysis and mixing

[0030] After the phosphate rock slurry enters the acid hydrolysis reaction tank, ammonium sulfate treated with sulfuric acid is added and stirred for 90-120 minutes. The resulting acid hydrolysis slurry is pumped into the first filter for separation. The crude ammonium phosphate filtrate enters the crude ammonium phosphate solution buffer tank, and the primary filter residue is transported to the acid hydrolysis reaction tank via a conveyor belt.

[0031] Step 3: Desulfurization

[0032] The crude ammonium phosphate filtrate from the crude ammonium phosphate solution buffer tank is pumped to the desulfurization reaction tank, where phosphate rock is added and mixed for 30 minutes. After the reaction is completed, the slurry is pumped into the second filter for separation. The filtrate enters the ammonium phosphate filtrate buffer tank, and the filter residue is transported to the pre-decomposition reaction tank for circulation via a conveyor belt.

[0033] Step 4: Dephosphorization

[0034] After the ammonium phosphate filtrate enters the ammonium phosphate filtrate buffer tank, a portion of the filtrate is pumped into the acid dephosphorization reaction tank, sulfuric acid is added, and the mixture is stirred and reacted with the filter residue of the first filter for 30 minutes. The reaction slurry is pumped into the third filter for separation. The filtered solids can be transported to the phosphogypsum stockpile by a conveyor belt. The filtrate enters the acid buffer tank and is pumped to the acid dephosphorization reaction tank for circulation.

[0035] In the specific operation, the phosphate rock added in step one is only added during startup; subsequently, the filter residue from the third filter is used for recycling. New phosphate rock is only added in step three. The sulfuric acid added in step two is also only added during startup; subsequently, acid from the acid buffer tank is used for recycling. Furthermore, the reaction temperature in the reaction tanks in steps one, two, three, and four is 90°C. The concentration of the sulfuric acid solution added in steps two and four is 98%.

[0036] This apparatus utilizes acidified ammonium sulfate to decompose phosphate rock, reducing the P2O5 content in phosphogypsum to 0.8% and decreasing the SO4 content in the ammonium sulfate solution. 2- With the content reduced to 0.7%, the resulting ammonium phosphate solution can be directly used downstream to produce monoammonium phosphate fertilizer for agriculture. This device features a simple process flow, does not involve high temperature or high pressure, and has low requirements for equipment strength. The impurity removal process utilizes a post-reaction recycling system to reduce costs and improve resource utilization.

[0037] The above embodiments describe preferred embodiments of the present invention, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including combining the various technical features in any other way. These simple modifications and combinations should also be considered as the content disclosed by the present invention and all fall within the protection scope of the present invention. Therefore, the protection scope of the present invention patent should be determined by the appended claims.

Claims

1. A device for the acidification and recycling of ammonium sulfate to decompose phosphate rock, characterized in that: The system includes a pre-decomposition reaction tank, an acid hydrolysis reaction tank, a first filter, a desulfurization reaction tank, a second filter, an acid hydrolysis and dephosphorization reaction tank, and a third filter, which are connected in sequence by pipes and pumps. The pre-decomposition reaction tank is equipped with a phosphoric acid feed port, the acid hydrolysis reaction tank is equipped with an acidified ammonium sulfate feed port, the filter residue of the first filter is conveyed to the acid hydrolysis reaction tank by a conveyor belt, the desulfurization reaction tank is equipped with a phosphate rock feed port, the filter residue of the second filter is conveyed to the pre-decomposition reaction tank by a conveyor belt, and the filter residue of the third filter is used to transport phosphogypsum externally by a conveyor belt.

2. The apparatus according to claim 1, characterized in that: The device also includes an acid buffer tank, the filtrate outlet of the third filter is connected to the inlet of the acid buffer tank, and the outlet of the acid buffer tank is connected to the inlet of the acidolysis reaction tank via a pipeline and a pump.

3. The apparatus according to claim 1, characterized in that: The device also includes a crude ammonium phosphate solution buffer tank. The filtrate outlet of the first filter is connected to the feed inlet of the crude ammonium phosphate solution buffer tank, and the discharge outlet of the crude ammonium phosphate solution buffer tank is connected to the feed inlet of the desulfurization reaction tank via a pipeline and a pump.

4. The apparatus according to claim 1, characterized in that: The device also includes a phosphate ammonium filtrate buffer tank. The filtrate outlet of the second filter is connected to the inlet of the phosphate ammonium filtrate buffer tank, and the outlet of the phosphate ammonium filtrate buffer tank is connected to the inlet of the acid dephosphorization reaction tank via a pipeline and a pump.

5. The apparatus according to claim 4, characterized in that: The ammonium phosphate filtrate buffer tank is also equipped with an ammonium phosphate feed outlet.

6. The apparatus according to claim 1, characterized in that: The acid-dephosphorization reaction tank is also equipped with a sulfuric acid feed port.

7. The apparatus according to any one of claims 1 to 6, characterized in that: The first filter, the second filter, and the third filter are all plate and frame filters.

8. The apparatus according to any one of claims 1 to 6, characterized in that: The pre-decomposition reaction tank, acid hydrolysis reaction tank, desulfurization reaction tank, and acid dephosphorization reaction tank are all closed containers and are equipped with stirring components inside.

9. The apparatus according to claim 8, characterized in that: The driving device for the stirring assembly is an explosion-proof motor.

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