Method for producing calcium superphosphate by using white fertilizer as raw material

Abstract

The invention relates to the technical field of phosphorus chemical resource recycling, in particular to a calcium superphosphate production method taking white fertilizer as a raw material, which comprises the following steps: S1, mixing and stirring the white fertilizer, sulfuric acid and phosphoric acid through a stirring mechanism, and absorbing reacted gas by an absorption liquid to obtain a fluorine-containing acid solution and a mixture A; s2, uniformly mixing and stirring ground phosphate rock with sulfuric acid and phosphoric acid through a stirring mechanism, and absorbing the reacted gas by an absorption liquid to obtain a fluorine-containing acidic solution and a mixture B; s3, mixing and stirring the mixture A and the mixture B, and curing for a period of time to obtain a blocky phosphate fertilizer; and S4, crushing the blocky phosphate fertilizer through a crushing mechanism to obtain the low-grade calcium superphosphate fertilizer. The fluorine content in the white fertilizer can be effectively reduced, the water-soluble phosphorus content is increased, and the white fertilizer can be converted into a low-grade calcium superphosphate fertilizer and a fluorine-containing acid solution for resourceful treatment.

Description

Technical Field

[0001] The invention relates to the technical field of phosphorus chemical resource recycling, in particular to a method for producing superphosphate using white fertilizer as a raw material. Background Art

[0002] Fertilizer-grade calcium hydrogen phosphate is a phosphorus-containing byproduct produced by phosphorus chemical companies during the process of extracting wet phosphoric acid and neutralizing impurities such as iron, aluminum, sulfur, and fluorine in the process of producing feed-grade calcium hydrogen phosphate from phosphate rock. Its fluorine content can reach more than 10%, and its phosphorus content can reach more than 25%. It is commonly known as white fertilizer. It is usually applied directly as a fertilizer or as a compound fertilizer in the form of a phosphorus source. Because it contains a large amount of fluorine, and the phosphorus it contains is mainly citrate-soluble phosphorus, and the water-soluble phosphorus content is low, applying it to alkaline soil will cause insufficient fertility and soil compaction. At present, there is no effective way to solve the above problems and recycle white fertilizer resources. Summary of the invention

[0003] The object of the present invention is to solve the above-mentioned shortcomings and provide a resource processing method which can effectively reduce the fluorine content in white fertilizer, increase the water-soluble phosphorus content, and convert the white fertilizer into low-grade superphosphate fertilizer and fluorine-containing acidic solution.

[0004] The technical implementation scheme of the present invention is: A method for producing superphosphate using white fertilizer as raw material comprises the following steps: S1, mixing and stirring white fertilizer, sulfuric acid and phosphoric acid by a stirring mechanism, and absorbing liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture A; S2, mixing the phosphate rock powder with sulfuric acid and phosphoric acid by a stirring mechanism and stirring them uniformly, and the absorption liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture B; S3, mixing the mixture A and the mixture B, and aging them for a period of time to obtain a block phosphate fertilizer; S4. The blocky phosphate fertilizer is crushed by a crushing mechanism to obtain low-grade superphosphate fertilizer.

[0005] Optionally, the amount of the white fertilizer added is 10 parts to 30 parts, the amount of the sulfuric acid added is 60 parts to 80 parts, and the amount of the sulfuric acid added is 40 parts to 80 parts.

[0006] Optionally, the mixing and stirring reaction time of the white fertilizer with sulfuric acid and phosphoric acid is 130min to 30min; the mixing and stirring reaction time of the phosphate rock powder with sulfuric acid and phosphoric acid is 1min to 30min; and the mixing and stirring time of the mixture A and the mixture B is 1min to 30min.

[0007] Optionally, during the reaction of the white fertilizer, the amount of sulfuric acid added is 0.3 to 1.0 times the mass of the white fertilizer; The mass ratio of the white fertilizer to the phosphate rock powder is 1:0.1-1.0; When the phosphate rock powder is reacted, the amount of sulfuric acid added is 0.1 to 0.4 times the mass of the phosphate rock powder.

[0008] Optionally, the amount of phosphoric acid is 0.01 to 0.2 times the amount of phosphate rock powder.

[0009] Optionally, the moisture content of the white fertilizer is 10-30%.

[0010] Optionally, the stirring mechanism includes a connecting ring, a stirring tank, a sealing cover, a first drive motor, a stirring shaft, a disturbance bracket and an air return duct. The stirring tank is a cylindrical hollow structure with an upper opening, and a sealing cover is provided on the upper part of the stirring tank, the first drive motor is provided on the sealing cover, and the stirring shaft and the disturbance bracket are provided on the output shaft of the first drive motor, and the material is stirred by the disturbance bracket.

[0011] Optionally, the sealing cover is provided with a first feed port, a second feed port and an air guide port, and the air guide port is connected to the air inlet on the stirring tank through an air guide pump and an air guide pipe to reintroduce the gas generated by the reaction into the absorption liquid.

[0012] Optionally, a discharge port is provided at the bottom of the mixing tank, and a material guide pipe is provided on the discharge port, a spiral material guide rod is provided inside the material guide pipe, the spiral material guide rod is connected to the second drive motor through a connecting piece, and a discharge port is provided on one side of the material guide pipe; the mixing tank is connected to the support through a connecting ring.

[0013] The present invention has the following advantages: The white fertilizer is mixed with sulfuric acid and phosphoric acid in proportion and stirred evenly, the gas generated by the reaction is absorbed by water, and the water becomes an absorption liquid; the phosphate rock powder is mixed with sulfuric acid and phosphoric acid in proportion and stirred evenly, and the absorption liquid repeatedly absorbs the gas generated by the reaction; the mixture A and the mixture B are mixed and stirred evenly, and after a period of maturation, a block phosphate fertilizer is obtained, and finally the block phosphate fertilizer is crushed to obtain a low-grade superphosphate fertilizer. The technical scheme and method not only effectively reduce the fluorine content in the white fertilizer and increase the water-soluble phosphorus content, but also can convert the white fertilizer into a low-grade superphosphate fertilizer and a fluorine-containing acidic solution, thereby realizing the resource processing of the white fertilizer. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the stirring mechanism of the present invention.

[0015] Figure 2 It is a schematic diagram of the explosion structure of the stirring mechanism of the present invention.

[0016] The meanings of the reference numerals in the figure are: 1-connecting ring, 2-pillar, 3-mixing tank, 4-sealing cover, 5-first feed inlet, 6-first drive motor, 7-air pump, 8-air duct, 9-second feed inlet, 10-discharge port, 11-feed duct, 12-second drive motor, 13-mixing shaft, 14-disturbance bracket. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that the directional terms such as up, down, left, right, front, back, inside, outside, etc. that appear or will appear in the text of the present invention are only based on the accompanying drawings of the present invention, and are not specific limitations of the present invention. Example

[0018] A method for producing superphosphate using white fertilizer as raw material comprises the following steps: S1, mixing and stirring white fertilizer, sulfuric acid and phosphoric acid by a stirring mechanism, and absorbing liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture A; S2, mixing the phosphate rock powder with sulfuric acid and phosphoric acid by a stirring mechanism and stirring them uniformly, and the absorption liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture B; S3, mixing the mixture A and the mixture B, and aging them for a period of time to obtain a block phosphate fertilizer; S4. The blocky phosphate fertilizer is crushed by a crushing mechanism to obtain low-grade superphosphate fertilizer.

[0019] Optionally, the amount of the white fertilizer added is 20 parts, the amount of the sulfuric acid added is 70 parts, and the amount of the sulfuric acid added is 60 parts.

[0020] The amount of the white fertilizer added is 20 parts, the amount of the sulfuric acid added is 55 parts, and the amount of the sulfuric acid added is 60 parts; the mixing and stirring reaction time of the white fertilizer, sulfuric acid and phosphoric acid is 15 minutes; the mixing and stirring reaction time of the phosphate rock powder, sulfuric acid and phosphoric acid is 18 minutes; the mixing and stirring time of the mixture A and the mixture B is 21 minutes; when the white fertilizer is reacted, the amount of sulfuric acid added is 0.6 times the mass of the white fertilizer; The mass ratio of the white fertilizer to the phosphate rock powder is 1:0.5; When the phosphate rock powder is reacted, the amount of sulfuric acid added is 0.25 times the mass of the phosphate rock powder; The amount of phosphoric acid is 0.1 times the amount of phosphate rock powder.

[0021] It should be noted that in the technical solution, the water content of the white fertilizer is 20%, which is conducive to the full reaction of the white fertilizer with sulfuric acid and phosphoric acid; the gas produced by the reaction of the white fertilizer with sulfuric acid and phosphoric acid is absorbed by the absorption liquid through the absorption tower after dust removal; the phosphate rock powder reacts with sulfuric acid and phosphoric acid, and the gas generated by the reaction continues to be absorbed by the absorption liquid through the absorption tower, and the water in the absorption tower is recycled until the fluorine-containing acidic solution reaches the required concentration and then replaced; the absorption liquid is water; the mixing and stirring reaction time of the white fertilizer with sulfuric acid and phosphoric acid is 15 minutes; the mixing and stirring reaction time of the phosphate rock powder with sulfuric acid and phosphoric acid is 18 minutes; The main components of white fertilizer are calcium hydrogen phosphate, calcium dihydrogen phosphate, calcium fluorosilicate and a small amount of phosphoric acid, calcium fluoroaluminate, etc. The reaction mechanism is as follows 2CaHPO4 + H2SO4→ CaSO4↓+ Ca(H2PO4)2 CaF6Si + H2SO4 → CaF2 + CaSO4 + SiF4↑ CaF2 + H2SO4 → CaSO4 + 2HF↑ Ca(H2PO4)2 + H2O + H3PO4 → Ca(H2PO4)2·H2O It should be further explained that in the technical scheme, first, the reaction of white fertilizer with sulfuric acid and phosphoric acid is carried out efficiently as a one-step reaction. During this process, specific components in the white fertilizer react with the acid to generate a variety of products and release gas. At the same time, the reaction of phosphate rock powder with sulfuric acid and phosphoric acid is carried out in two steps in an orderly manner. In the first step, the phosphate rock powder initially contacts with the acid to react, and in the second step, the reaction process is further deepened, and gas is also produced. The gases produced by these reactions will first be dusted to remove solid impurities, and then transported to the absorption tower. A multi-level circulating water system is set inside the absorption tower. When the gas enters the absorption tower, it is fully contacted and combined with the circulating water to form a fluorine-containing acidic solution, which realizes the effective recovery and treatment of fluorine and other components in the gas. Then, the materials obtained by reacting white fertilizer and phosphate rock powder with sulfuric acid and phosphoric acid in precise proportions are mixed, and the mixed materials enter the maturation stage. After a period of maturation, the materials are gradually converted into block phosphate fertilizers. Finally, the block phosphate fertilizer is processed by a crushing process to obtain a low-grade superphosphate fertilizer.

[0022] It is worth mentioning that during the entire reaction process, the calcium hydrogen phosphate that was originally slightly soluble in water was successfully transformed into calcium dihydrogen phosphate that was easily soluble in water. This not only effectively reduced the fluorine content in the white fertilizer, but also significantly increased the water-soluble phosphorus content. Ultimately, low-grade superphosphate fertilizer was successfully prepared, which improved the quality and performance of the product and had good economic and environmental benefits. Example

[0023] The original composition (dry basis) of the fertilizer-grade calcium hydrogen phosphate produced as a byproduct of the existing feed-grade calcium hydrogen phosphate plant is: fluorine element (F): 8.28%, the total content of phosphorus pentoxide: 30.50%, the effective phosphorus pentoxide content: 25.34%, and the water content in phosphorus pentoxide: 1.06%.

[0024] It can be optimized by: First, fertilizer-grade calcium hydrogen phosphate is weighed and placed in a reactor, then 0.5 times sulfuric acid and 0.05 times phosphoric acid of the mass of white fertilizer are weighed and placed in the reactor, the number of sulfuric acid is 60 parts, the number of phosphoric acid is 40 parts, and the sulfuric acid and phosphoric acid are added to the reactor at a uniform rate after stirring is started. After the reaction is completed, the mixture I is transferred to another reactor for standby use, and the reaction stirring time is 20 minutes; then, phosphate rock powder is weighed and placed in a reactor, 0.2 times sulfuric acid and 0.02 times phosphoric acid of the mass of phosphate rock powder are weighed and placed in the reactor, the number of sulfuric acid is 60 parts, the number of phosphoric acid is 40 parts, and the sulfuric acid and phosphoric acid are added to the reactor at a uniform rate after stirring is started. The reaction stirring time is 10 minutes, and after the reaction is completed, a mixture B is obtained; the mixture B is transferred to the reactor containing the mixture A and mixed and stirred evenly; the mixed and stirred mixture is transferred to a warehouse for maturation for 12 days to obtain a block phosphate fertilizer; the block phosphate fertilizer is crushed to obtain a low-grade superphosphate fertilizer; the gas generated by the reaction is pumped into an absorption tower by a vacuum pump through cyclone separation and dust removal.

[0025] After the reaction is completed, a low-grade superphosphate fertilizer is obtained, and the composition (wet basis) is: fluorine element (F): 4.15%, the overall content of phosphorus pentoxide: 23.26%, the content of phosphorus pentoxide: 22.85%, and the water content in phosphorus pentoxide: 13.27%.

[0026] Table 1 is a comparison of the experimental data obtained by analysis: Example

[0027] The original composition (dry basis) of fertilizer-grade calcium hydrogen phosphate, a by-product of feed-grade calcium hydrogen phosphate plant, is: fluorine element (F): 7.82%, the overall content of phosphorus pentoxide is: total: 29.74%, the effective phosphorus pentoxide content is: 23.83%, and the water content in phosphorus pentoxide is: 2.03%.

[0028] First, fertilizer-grade calcium hydrogen phosphate is weighed and placed in a reactor, then 0.4 times sulfuric acid and 0.04 times phosphoric acid of the mass of white fertilizer are weighed and placed in the reactor, the number of sulfuric acid is 60 parts, the number of phosphoric acid is 40 parts, and the sulfuric acid and phosphoric acid are added to the reactor at a uniform rate after stirring. After the reaction is completed, the mixture I is transferred to another reactor for standby use, and the reaction stirring time is 20 minutes; then, phosphate rock powder is weighed and placed in a reactor, 0.3 times sulfuric acid and 0.03 times phosphoric acid of the mass of phosphate rock powder are weighed and placed in the reactor, the number of sulfuric acid is 60 parts, and the number of phosphoric acid is 40 parts, and the sulfuric acid and phosphoric acid are added to the reactor at a uniform rate after stirring, and the reaction stirring time is 10 minutes. After the reaction is completed, a mixture B is obtained; the mixture B is transferred to a reactor containing the mixture A and mixed and stirred evenly; the mixed and stirred mixture is transferred to a warehouse for maturation for 12 days to obtain a block phosphate fertilizer; the block phosphate fertilizer is crushed to obtain a low-grade superphosphate fertilizer; the gas generated by the reaction is pumped into an absorption tower by a vacuum pump through cyclone separation and dust removal.

[0029] After the reaction is completed, a low-grade superphosphate fertilizer is obtained, and the composition (wet basis) is: fluorine element (F): 5.02%, the total content of phosphorus pentoxide: 23.70%, the effective content of phosphorus pentoxide: 22.06%, and the water content in phosphorus pentoxide: 12.40%.

[0030] Table 2 is a comparison of the experimental data obtained by analysis:

[0031] It can be seen from the above embodiments that the method provided by the present invention can reduce the fluorine content in white fertilizer, increase the water-soluble phosphorus content, and convert the white fertilizer into low-grade superphosphate fertilizer and fluorine-containing acidic solution, thereby realizing the resource processing of white fertilizer. Example

[0032] like Figure 1-Figure 2As shown, the stirring mechanism includes a connecting ring 1, a stirring tank 3, a sealing cover 4, a first drive motor 6, a stirring shaft 13, a disturbance bracket 14 and a return air duct 8. The stirring tank 3 is a cylindrical cavity structure with an upper opening, and a sealing cover 4 is provided on the upper part of the stirring tank 3. The sealing cover 4 is provided with a first drive motor 6. The output shaft of the first drive motor 6 is provided with a stirring shaft 13 and a disturbance bracket 14, and the material is stirred by the disturbance bracket 14; the sealing cover 4 is provided with a first feed inlet 5, a first feed inlet 6 and a first feed inlet 7; Two feed ports 9 and an air guide port, the air guide port is connected to the air inlet on the stirring tank 3 through an air guide pump 7 and an air guide pipe 8, so as to reintroduce the gas generated by the reaction into the absorption liquid; a discharge port 10 is arranged at the bottom of the stirring tank 3, and a material guide pipe 11 is arranged on the discharge port 10, a spiral material guide rod is arranged inside the material guide pipe 11, and the spiral material guide rod is connected to the second drive motor 12 through a connecting piece, and a discharge port is arranged on one side of the material guide pipe 11; the stirring tank 3 is connected to the support 2 through a connecting ring 1.

[0033] It should be noted that in this process, in order to achieve efficient mixing of multiple materials, a set of innovative stirring mechanisms is specially designed, the core components of which include a stirring shaft 13 driven by a first drive motor 6 and a disturbance bracket 14 connected thereto. The stirring mechanism can perform all-round and powerful mixing treatment on the materials in the internal chamber of the stirring tank 3 to ensure that the materials are fully in contact and react.

[0034] It is worth noting that a large amount of gas will be generated during the material mixing process. In order to significantly accelerate the mixing efficiency of the gas and the solution and thus improve the overall reaction effect, we cleverly set an air pump 7 at the air outlet of the sealing cover 4. The air pump 7 quickly extracts the generated gas and is accurately connected to the air inlet on the stirring tank 3 through a carefully designed air pipe 8, thereby re-introducing the gas into the solution inside the stirring tank 3. Such a cyclical process of gas introduction and export allows the gas and the solution to be in full contact, greatly promoting the fusion and absorption between the two, providing more favorable conditions for the subsequent reaction process, ensuring the efficient and stable operation of the entire process, and further improving the product quality and production efficiency.

[0035] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the above embodiments, and various changes can be made within the knowledge scope of those skilled in the art without departing from the spirit of the present invention.

Claims

1. A method for producing superphosphate using white fertilizer as raw material, characterized in that: The following steps are involved: S1, mixing and stirring white fertilizer, sulfuric acid and phosphoric acid by a stirring mechanism, and absorbing liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture A; S2, mixing the phosphate rock powder with sulfuric acid and phosphoric acid by a stirring mechanism and stirring them uniformly, and the absorption liquid absorbs the gas after the reaction to obtain a fluorine-containing acidic solution and a mixture B; S3, mixing the mixture A and the mixture B, and aging them for a period of time to obtain a block phosphate fertilizer; S4. The blocky phosphate fertilizer is crushed by a crushing mechanism to obtain low-grade superphosphate fertilizer.

2. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: The amount of the white fertilizer added is 10-30 parts, the amount of the sulfuric acid added is 60-80 parts, and the amount of the sulfuric acid added is 40-80 parts.

3. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: The mixing and stirring reaction time of the white fertilizer with sulfuric acid and phosphoric acid is 1 min to 30 min; the mixing and stirring reaction time of the phosphate rock powder with sulfuric acid and phosphoric acid is 1 min to 30 min; the mixing and stirring time of the mixture A and the mixture B is 1 min to 30 min.

4. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: When the white fertilizer is reacted, the amount of sulfuric acid added is 0.3 to 1.0 times the mass of the white fertilizer; The mass ratio of the white fertilizer to the phosphate rock powder is 1:0.1-1.0; When the phosphate rock powder is reacted, the amount of sulfuric acid added is 0.1 to 0.4 times the mass of the phosphate rock powder.

5. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: The amount of phosphoric acid is 0.01 to 0.2 times the amount of phosphate rock powder.

6. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: The moisture content of the white fertilizer is 10-30%.

7. A method for producing superphosphate using white fertilizer as raw material according to claim 1, characterized in that: The stirring mechanism comprises a connecting ring (1), a stirring tank (3), a sealing cover (4), a first drive motor (6), a stirring shaft (13), a disturbance bracket (14) and a return air duct (8); the stirring tank (3) is a cylindrical hollow structure with an upper opening, and a sealing cover (4) is arranged on the upper part of the stirring tank (3); the first drive motor (6) is arranged on the sealing cover (4); the stirring shaft (13) and the disturbance bracket (14) are arranged on the output shaft of the first drive motor (6); and the material is stirred by the disturbance bracket (14).

8. A method for producing superphosphate using white fertilizer as raw material according to claim 7, characterized in that: The sealing cover (4) is provided with a first feed port (5), a second feed port (9) and a gas guide port, and the gas guide port is connected to the gas inlet on the stirring tank (3) through a gas guide pump (7) and a gas guide pipeline (8), so as to reintroduce the gas generated by the reaction into the absorption liquid.

9. A method for producing superphosphate using white fertilizer as raw material according to claim 8, characterized in that: A discharge port (10) is provided at the bottom of the stirring tank (3), and a material guide pipe (11) is provided on the discharge port (10), a spiral material guide rod is provided inside the material guide pipe (11), and the spiral material guide rod is connected to the second drive motor (12) via a connecting piece, and a discharge port is provided on one side of the material guide pipe (11); The stirring tank (3) is connected to the support (2) via a connecting ring (1).

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