A raw meal preparation method in anhydrous phosphogypsum acid making process

Abstract

This invention relates to a raw material preparation method in anhydrous phosphogypsum acid production process, comprising the following steps: providing a wet-based main material, various auxiliary materials, and various supplementary materials; premixing the various auxiliary materials in a premixing device to obtain premixed auxiliary materials, and premixing the various supplementary materials in a premixing device to obtain premixed supplementary materials; mixing the wet-based main material and the premixed auxiliary materials in a primary mixing device to obtain a primary mixture; activating hydration in an aging chamber to obtain a hydrated mixture; and mixing the hydrated mixture and the premixed supplementary materials in a final mixing device to obtain raw material. By employing the technical solution of this invention, the wet-based main material and various auxiliary materials are uniformly mixed multiple times, ensuring uniform distribution of the auxiliary materials. Through the activation hydration reaction of the auxiliary materials, the various auxiliary materials adhere to the surface of the anhydrous gypsum crystals. Furthermore, grinding the various auxiliary materials into powder increases the reduction reaction rate and makes the reduction reaction more complete.

Description

Technical Field

[0001] This invention belongs to the field of chemical process equipment technology, and particularly relates to a raw material preparation method in anhydrous phosphogypsum acid production process. Background Technology

[0002] Phosphogypsum is a solid waste product from the wet process of phosphoric acid production, with approximately 4 to 5 tons of dry phosphogypsum produced per ton of wet-process phosphoric acid. With the continuous development of the phosphate fertilizer industry and the new energy sector, phosphogypsum emissions are increasing daily. China's average annual phosphogypsum emissions are approximately 80 million tons, but the comprehensive utilization rate is less than 50%. Large-scale stockpiling of phosphogypsum not only occupies land but also poses serious environmental risks. The production of sulfuric acid from phosphogypsum and the co-production of cement clinker is one of the effective ways to scale up the consumption of phosphogypsum and improve its comprehensive utilization rate. The existing process for producing sulfuric acid from phosphogypsum and co-producing cement clinker generally includes the following steps: drying the wet-based main material, mixing the wet-based main material with auxiliary materials to form raw meal, preheating to remove the crystal water and attached water in the raw meal, partially reducing calcium sulfate to calcium sulfide, and decomposing the calcium sulfide and the remaining calcium sulfate to calcium oxide and simultaneously producing SO2. The SO2 is used to produce sulfuric acid, and the calcium oxide reacts with various auxiliary materials at high temperature to produce cement clinker. Among these steps, drying the wet-based main material requires large-scale drying equipment, resulting in high energy consumption and significantly increasing the production cost of enterprises. In the reduction reaction process where calcium sulfate is partially reduced to calcium sulfide, the uneven mixing of calcium sulfate in the raw meal and the reducing agent in the auxiliary materials can also cause incomplete local reactions of the materials, affecting the efficiency of the reduction reaction, and consequently affecting the production efficiency and capacity of sulfuric acid and cement clinker. Summary of the Invention

[0003] To solve the above-mentioned technical problems, the present invention provides a raw material preparation method in the process of anhydrous phosphogypsum acid production.

[0004] This invention provides a raw material preparation method for anhydrous phosphogypsum acid production process, comprising the following steps: Step 1: Provide wet-based main materials, various auxiliary materials, and various supplementary materials; Step 2: After premixing multiple auxiliary materials in a premixing equipment, premixed auxiliary materials are obtained; after premixing multiple supplementary materials in a premixing equipment, premixed supplementary materials are obtained. Step 3: After mixing the wet-based main material and premixed auxiliary materials in the primary mixing equipment, a primary mixture is obtained; Step 4: After the initial mixture is sent into the aging chamber for activation and hydration, a hydrated mixture is obtained; Step 5: The hydrated mixture from Step 4 and the premixed feed from Step 2 are fed into the final mixing equipment for mixing to obtain raw material.

[0005] The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: before step five, the hydrated mixture is crushed and dispersed.

[0006] The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: before step one, the wet base material is filtered using a turbulent washing filter press, and various auxiliary materials and supplementary materials are ground into powder form using a mill.

[0007] The wet-based main material mentioned in step one is wet-based anhydrous phosphogypsum; the premixed auxiliary materials include lime powder, coke powder and clay powder, and the mass fractions of each component in the initial mixture are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; lime powder 1-2 parts, coke powder 3-5 parts and clay powder 1-2 parts; the premixed supplementary material includes coke powder and clay powder, and the mass fractions of each component in the raw meal are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; coke powder 6-8 parts and clay powder 1-2 parts.

[0008] The premixing equipment mentioned in step two is a spiral mixer.

[0009] The initial mixing equipment mentioned in step three is a fly knife mixer.

[0010] In step four, the duration of the initial mixture hydration is 5-7 days.

[0011] The final mixing equipment mentioned in step five is a twin-shaft paddle mixer.

[0012] The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: first, using a belt scale to measure the wet base main material, auxiliary material, supplementary material, premixed auxiliary material, premixed supplementary material, initial mixture or hydrated mixture, and then using a chain conveyor or belt conveyor to transfer them between the corresponding process steps.

[0013] The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: after completing step five, the raw material is supplied to the kiln tail preheater using an elevator.

[0014] The beneficial effects of this invention are as follows: Using the technical solution of this invention, before the reduction reaction of calcium sulfate to calcium sulfide, the wet-based main material and various auxiliary materials are mixed evenly multiple times. On the one hand, this ensures uniform mixing of the wet-based main material and various auxiliary materials, preventing incomplete local reactions of the raw materials during the reaction process and improving the reduction reaction efficiency. On the other hand, the attached water in anhydrous phosphogypsum generates an activated hydration reaction with various auxiliary materials, allowing coke powder and clay powder to adhere evenly to the surface of the anhydrous gypsum crystals. Subsequently, during the reduction reaction, the wet-based main material and auxiliary materials are in full contact, further improving the reduction reaction efficiency. Actual calculations show that the reduction reaction rate can be increased by more than 40% compared to existing technologies. Furthermore, most of the attached water in the anhydrous gypsum itself is absorbed and converted into crystal water during the activated hydration reaction, while another portion evaporates and is lost during the activated hydration process. The remaining attached water does not require drying and dehydration during the raw material preparation process and can be directly used for batching, reducing equipment investment in the gypsum dehydration and drying section, saving energy consumption for dehydration and drying, truly achieving kiln entry without drying, and greatly reducing the production cost of gypsum-based acid production. Attached Figure Description

[0015] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0016] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but the scope of protection claimed is not limited thereto; This invention provides a method for preparing raw materials in anhydrous phosphogypsum acid production processes, such as... Figure 1 As shown, it includes the following steps: Step 1: Provide wet-based main materials, various auxiliary materials, and various supplementary materials; Step 2: After premixing multiple auxiliary materials in a premixing equipment, premixed auxiliary materials are obtained; after premixing multiple supplementary materials in a premixing equipment, premixed supplementary materials are obtained. Step 3: After mixing the wet-based main material and premixed auxiliary materials in the primary mixing equipment, a primary mixture is obtained; Step 4: After the initial mixture is sent into the aging chamber for activation and hydration, a hydrated mixture is obtained; Step 5: The hydrated mixture from Step 4 and the premixed feed from Step 2 are fed into the final mixing equipment for mixing to obtain raw material.

[0017] The technical solution of this invention involves multiple uniform mixing of the wet-based main material and various auxiliary materials before the reduction reaction of calcium sulfate to calcium sulfide. This ensures uniform mixing of the wet-based main material and auxiliary materials, preventing incomplete local reactions during the raw material reaction and improving the reduction efficiency. Furthermore, the adhering water in anhydrous phosphogypsum triggers an activating hydration reaction with the auxiliary materials, allowing coke powder and clay powder to adhere uniformly to the surface of the anhydrous gypsum crystals. This ensures sufficient contact between the wet-based main material and auxiliary materials during the reduction reaction, further enhancing the reduction efficiency. Actual calculations show that the reduction reaction rate can be increased by more than 40% compared to existing technologies. Additionally, most of the adhering water in the anhydrous gypsum is absorbed and converted into crystal water during the activating hydration reaction, while another portion evaporates during the activating hydration process. The remaining adhering water does not require drying during the raw material preparation process and can be directly used for batching, reducing equipment investment in gypsum dehydration and drying, saving energy consumption, and truly achieving kiln-free drying, significantly reducing the production cost of gypsum-based acid production.

[0018] Specifically, the raw material preparation method in the anhydrous phosphogypsum acid production process further includes the following steps: Before step five, the hydrated mixture is crushed and dispersed. By employing the technical solution of this invention, during the raw material preparation process, the material is thoroughly crushed and dispersed, reducing the particle size and allowing various auxiliary materials to adhere uniformly to the surface of the anhydrous gypsum crystals. Consequently, during the reduction reaction, the wet-based main material and auxiliary materials are in full contact, and because the auxiliary materials are crushed and dispersed, the specific surface area increases, improving the reduction reaction efficiency.

[0019] In addition, the raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: Before step one, the wet base material is filtered using a turbulent washing filter press, and various auxiliary materials and feedstocks are ground into powder using a mill. By adopting the technical solution of this invention, the particle size of the material is reduced by grinding it into powder, allowing various auxiliary materials to adhere evenly to the surface of the anhydrous gypsum crystals. Consequently, during the reduction reaction, the wet base material and auxiliary materials are in full contact, and because the auxiliary materials are broken down and dispersed, the specific surface area increases, thus improving the reduction reaction efficiency.

[0020] In addition, the wet-based main material in step one is wet-based anhydrous phosphogypsum; the premixed auxiliary materials include lime powder, coke powder and clay powder, and the mass fractions of each component in the initial mixture are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; lime powder 1-2 parts, coke powder 3-5 parts and clay powder 1-2 parts; the premixed supplementary material includes coke powder and clay powder, and the mass fractions of each component in the raw meal are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; coke powder 6-8 parts and clay powder 1-2 parts.

[0021] Specifically, in step two, the premixing equipment is a spiral mixer. In step three, the primary mixing equipment is a fly knife mixer. In step four, the duration of activating hydration of the primary mixture is 5-7 days. In step five, the final mixing equipment is a twin-shaft paddle mixer.

[0022] Furthermore, the raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: First, a belt scale is used to measure the wet-based main material, auxiliary material, supplementary material, premixed auxiliary material, premixed supplementary material, initial mixture, or hydrated mixture; then, a chain conveyor or belt conveyor is used to transfer them between the corresponding process steps. By employing the technical solution of this invention, the material proportioning accuracy is improved by accurately measuring the materials between each process using a belt scale before transfer and mixing, and the material transfer efficiency is improved by utilizing a chain conveyor or belt conveyor.

[0023] In addition, the raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: after completing step five, the raw material is supplied to the kiln tail preheater using an elevator.

Claims

1. A method for preparing raw materials in an anhydrous phosphogypsum acid production process, characterized in that: Includes the following steps: Step 1: Provide wet-based main materials, various auxiliary materials, and various supplementary materials; Step 2: After premixing multiple auxiliary materials in a premixing equipment, premixed auxiliary materials are obtained; after premixing multiple supplementary materials in a premixing equipment, premixed supplementary materials are obtained. Step 3: After mixing the wet-based main material and premixed auxiliary materials in the primary mixing equipment, a primary mixture is obtained; Step 4: After the initial mixture is sent into the aging chamber for activation and hydration, a hydrated mixture is obtained; Step 5: The hydrated mixture from Step 4 and the premixed feed from Step 2 are fed into the final mixing equipment for mixing to obtain raw material.

2. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: before step five, the hydrated mixture is crushed and dispersed.

3. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: before step one, the wet base material is filtered using a turbulent washing filter press, and various auxiliary materials and supplementary materials are ground into powder form using a mill.

4. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The wet-based main material mentioned in step one is wet-based anhydrous phosphogypsum; the premixed auxiliary materials include lime powder, coke powder and clay powder, and the mass fractions of each component in the initial mixture are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; lime powder 1-2 parts, coke powder 3-5 parts and clay powder 1-2 parts; the premixed supplementary material includes coke powder and clay powder, and the mass fractions of each component in the raw meal are as follows: wet-based anhydrous phosphogypsum converted to dry basis is 100 parts; coke powder 6-8 parts and clay powder 1-2 parts.

5. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The premixing equipment mentioned in step two is a spiral mixer.

6. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The initial mixing equipment mentioned in step three is a fly knife mixer.

7. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: In step four, the duration of the initial mixture hydration is 5-7 days.

8. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The final mixing equipment mentioned in step five is a twin-shaft paddle mixer.

9. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: first, using a belt scale to measure the wet base main material, auxiliary material, supplementary material, premixed auxiliary material, premixed supplementary material, initial mixture or hydrated mixture, and then using a chain conveyor or belt conveyor to transfer them between the corresponding process steps.

10. The raw material preparation method in the anhydrous phosphogypsum acid production process as described in claim 1, characterized in that: The raw material preparation method in the anhydrous phosphogypsum acid production process also includes the following steps: after completing step five, the raw material is supplied to the kiln tail preheater using an elevator.

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