Method for recovering humic acid from ardealite

Abstract

A method for recovering humic acid from ardealite belongs to the technical field of humic acid separation and extraction, and comprises the following steps: after the ardealite is subjected to full extraction gypsum phase pretreatment, the obtained tailings are used as raw materials for later use without being crushed and screened; raw materials and water are prepared into slurry, an ammonia water solution is adopted as a leaching agent for mixing, heating and stirring, humic acid in the raw materials is dissolved in the ammonia water solution, stirring and leaching are conducted, then solid-liquid separation is conducted in a vacuum suction filtration mode, the obtained solid phase is insoluble tailings, and the filtrate is an ammonium humate solution; and evaporating and concentrating the obtained ammonium humate solution, then cooling and crystallizing, centrifugally filtering to obtain an ammonium humate product and a crystallized solution, and returning the crystallized solution as a leaching agent for recycling. The method provided by the invention has the advantages of high technical practicability and no waste liquid generation problem, is a clean humic acid extraction method with a wide application prospect, and can solve the problem that the residual organic phase in the phosphogypsum is difficult to comprehensively utilize at present.

Description

Technical Field

[0001] The invention belongs to the technical field of humic acid separation and extraction, and particularly relates to a method for recovering humic acid from phosphogypsum. Background Art

[0002] Humic acid is a kind of natural organic matter with complex composition. It is accumulated from the decomposition and transformation of animal and plant residues by microorganisms and a series of geochemical processes. Its acidic functional groups such as carboxyl and phenolic hydroxyl have the ability to complex metal ions, which can greatly improve the biological effectiveness of metal ions. my country has rich humic acid resources, large reserves, wide distribution and good quality. As an organic raw material, it is widely used in agriculture, chemical industry, building materials, medicine and other fields.

[0003] In terms of the comprehensive utilization of humic acid, humic acid is usually added during the phosphate rock beneficiation process to improve the composition of apatite. Humic acid and its salts can be used as inhibitors. For example, in the flotation separation process of apatite and other minerals, sodium humate can inhibit the flotation of certain gangue minerals or impurity minerals, increase the difference in the surface floatability of apatite and these minerals, make apatite easier to float out, and improve the grade of apatite concentrate. In the phosphate ore sorting process, humic acid can also be used as a selective flocculant, which selectively adsorbs on the surface of apatite particles to cause flocculation, while the flocculation effect on other minerals is weaker. In this way, apatite particles can be agglomerated together, which is convenient for subsequent separation and enrichment, and helps to improve the recovery efficiency of apatite. Therefore, in the process of producing phosphoric acid from phosphate concentrate, humic acid usually enters into phosphogypsum, so that the content of humic acid in phosphogypsum can reach more than 4%, the content of amorphous SiO2 can reach more than 8%, and the content of unreacted apatite can reach more than 5%, and even more than 10%. The utilization rate of humic acid, SiO2 and apatite in the impurity phase is greatly improved, but there is no patent or literature report on the recovery of humic acid in phosphogypsum.

[0004] Since humic acid can react with ammonia water to neutralize, water-insoluble humic acid is converted into water-soluble ammonium humate salt. The present invention uses ammonia leaching technology to extract humic acid from the tailings after gypsum extraction from phosphogypsum using ammonia solution, releases humic acid in the form of ammonium humate salt, and then obtains ammonium humate product through concentration, crystallization and separation, which provides support for the comprehensive utilization of phosphogypsum resources.

[0005] In summary, after extracting the gypsum phase from phosphogypsum, the resource utilization of the tailings becomes a technical bottleneck restricting the cleanliness and comprehensive resource utilization of phosphogypsum. The tailings are mainly composed of apatite, amorphous SiO2 and humic acid. How to realize their resource utilization is of great practical significance to phosphogypsum. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for recovering humic acid from phosphogypsum, which is used to extract the organic phase from the remaining tailings (apatite, amorphous SiO2 and humic acid) after the gypsum phase is extracted from phosphogypsum, so as to solve the problem of resource utilization and high-value utilization of humic acid. It not only has a short process flow and low cost, but also has no environmental problems.

[0007] The main purpose of the present invention is achieved through the following solutions:

[0008] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0009] S1. After the gypsum phase is fully extracted from the phosphogypsum, the tailings obtained do not need to be crushed or sieved and are used as raw materials for standby use;

[0010] S2. The raw material and water are configured into a slurry, and then mixed with an ammonia solution as a leaching agent, heated and stirred, and the humic acid in the raw material is dissolved in the ammonia solution and then stirred and leached;

[0011] S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, the resulting solid phase is an insoluble tailings, and the filtrate is an ammonium humate solution;

[0012] S4. The obtained ammonium humate solution is evaporated and concentrated, then cooled and crystallized, and the ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0013] in:

[0014] In step S1, the tailings have a composition, by mass fraction, of 5% to 15% humic acid, 10% to 20% apatite, 60% to 80% SiO2, and the remaining 5% is organic matter.

[0015] In step S2, the solid-liquid ratio of the raw material to water is 1: (4-10) g / mL, and the mass percentage concentration of the ammonia solution is 5%-15%.

[0016] In the step S2, the heating temperature is 20°C to 50°C, the stirring speed is 45 r / min to 120 r / min, and the stirring time is 10 min to 60 min.

[0017] In the step S2, the leaching temperature of the stirring leaching is 20°C to 50°C, the leaching time is 20min to 60min, the pH value of the solution after leaching is controlled to be 8 to 9, and the leaching rate of humic acid in the tailings is ≥99%.

[0018] In step S3, the specific components of the insoluble tailings are a silicon-rich phase and a phosphorus-rich phase.

[0019] In step S4, the ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 30% to 40%, the temperature during cooling and crystallization is 10° C. to 20° C., and the stirring speed of the centrifugal filtration is 30 r / min to 90 r / min.

[0020] The ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid of the first-class product is not less than 35%, and the dry basis content of available nitrogen is not less than 4%; the dry basis content of water-soluble humic acid of the second-class product is not less than 25%, and the dry basis content of available nitrogen is not less than 3%, and the recovery rate of humic acid in phosphogypsum tailings is ≥98%.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] (1) The technology provided by the present invention saves energy and reduces consumption, and reduces pollution. Hydrometallurgy is mainly divided into acid leaching and ammonia leaching. Compared with acid leaching, the ammonia leaching of the present invention has the advantages of good selectivity and low production cost. The sorted tailings can be leached through the ammonia leaching method to release humic acid in the form of humic acid ammonium salt.

[0023] (2) The present invention adopts a direct extraction and separation method to prepare humic acid, which has simple steps, short production cycle, and high leaching rate and extraction rate of humic acid in tailings.

[0024] (3) The present invention is based on chemical extraction method, utilizes ammonia leaching technology, and improves the leaching rate of humic acid by controlling the process system, so that the humic acid in the phosphogypsum tailings can be efficiently recycled and utilized, and high-quality ammonium humate products can be obtained. The technology provided by the present invention is highly practical and has no problem of waste liquid generation. It is a clean method for extracting humic acid with broad application prospects, which can solve the problem that the residual organic phase in phosphogypsum is difficult to comprehensively utilize. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 A process flow chart of recovering humic acid from phosphogypsum according to the present invention. DETAILED DESCRIPTION

[0026] In order to make the technical solutions, creative purposes and advantages achieved by the present invention more clear, the present invention is further explained below in conjunction with specific embodiments.

[0027] Example 1

[0028] A method for recovering humic acid from phosphogypsum, the process flow chart of which is as follows Figure 1 As shown, the specific steps include:

[0029] S1. After the gypsum phase is fully extracted from the phosphogypsum, the components of the tailings obtained by mass fraction include 5% humic acid, 10% apatite and 80% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or screened and can be used as raw materials.

[0030] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:4g / mL. Then, at 50°C, a 15% mass percentage ammonia solution is added as a leaching agent, stirred for 60 minutes, and the stirring rate is set to 120r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at a temperature of 50°C for 20 minutes. The pH value of the solution after leaching is controlled to be 8.5. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The humic acid leaching rate in the tailings is 99.31%.

[0031] S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, and the resulting solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution;

[0032] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 35%, and then cooled and crystallized at 20°C. Ammonium humate crystals are precipitated in the solution, and the ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 90r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0033] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid of the product is 41.4%, the dry basis content of available nitrogen is 4.5%, and the recovery rate of humic acid in phosphogypsum tailings is 98.64%.

[0034] Example 2

[0035] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0036] S1. After the gypsum phase is fully extracted from the phosphogypsum, the resulting tailings contain, by mass fraction, 6% humic acid, 10% apatite and 79% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or sieved and can be used as a raw material.

[0037] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:8g / mL. Then, at 40°C, a 14% ammonia solution is added as a leaching agent, stirred for 20 minutes, and the stirring rate is set to 100r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at a temperature of 40°C for 25 minutes. The pH value of the solution after leaching is controlled to be 8. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.64%.

[0038] S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, and the resulting solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution;

[0039] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 40%, and then cooled and crystallized at 18°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 50r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0040] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid of the product is 38.8%, the dry basis content of available nitrogen is 4.2%, and the recovery rate of humic acid in phosphogypsum tailings is 98.93%.

[0041] Example 3

[0042] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0043] S1. After the gypsum phase is fully extracted from the phosphogypsum, the components in the tailings obtained by mass fraction include 8% humic acid, 12% apatite and 75% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or screened and can be used as raw materials.

[0044] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:6g / mL. Then, at 45°C, a 12% ammonia solution is added as a leaching agent, stirred for 10 minutes, and the stirring rate is set to 90r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at a temperature of 45°C for 30 minutes. The pH value of the solution after leaching is controlled to be 9. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.16%.

[0045] S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, and the resulting solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution;

[0046] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 30%, and then cooled and crystallized at 20°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 40r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0047] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 36.5%, the dry basis content of available nitrogen is 5.6%, and the recovery rate of humic acid in phosphogypsum tailings is 99.25%.

[0048] Example 4

[0049] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0050] S1. After the gypsum phase is fully extracted from the phosphogypsum, the components of the tailings obtained by mass fraction include 9% humic acid, 18% apatite and 68% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or screened and can be used as a raw material.

[0051] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:10g / mL. Then, at 40°C, a 10% ammonia solution is added as a leaching agent, stirred for 35 minutes, and the stirring rate is set to 80r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at a temperature of 40°C for 35 minutes. The pH value of the solution after leaching is controlled to be 8. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.53%.

[0052] S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, and the resulting solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution;

[0053] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 35%, and then cooled and crystallized at 15°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 80r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0054] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 37.1%, the dry basis content of available nitrogen is 6.1%, and the recovery rate of humic acid in phosphogypsum tailings is 98.52%.

[0055] Example 5

[0056] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0057] S1. After the gypsum phase is fully extracted from the phosphogypsum, the components of the tailings obtained by mass fraction include 10% humic acid, 14% apatite and 71% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or screened and can be used as a raw material.

[0058] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:8g / mL. Then, at 35°C, a 9% ammonia solution is added dropwise as a leaching agent, stirred for 30 minutes, and the stirring rate is set to 70r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at a temperature of 35°C for 40 minutes. The pH value of the solution after leaching is controlled to be 8.5. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.42%.

[0059] S3. After leaching is completed, vacuum filtration is used to separate the solid and liquid. The obtained solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution.

[0060] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 30%, and then cooled and crystallized at 15°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 60r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0061] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 39.8%, the dry basis content of available nitrogen is 4.7%, and the recovery rate of humic acid in phosphogypsum tailings is 99.41%.

[0062] Example 6

[0063] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0064] S1. After the gypsum phase is fully extracted from the phosphogypsum, the resulting tailings contain, by mass fraction, 12% humic acid, 13% apatite and 70% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or sieved and can be used as a raw material.

[0065] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:6g / mL. Then, at 30°C, an 8% ammonia solution is added as a leaching agent, stirred for 50 minutes, and the stirring rate is set to 60r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at 30°C for 45 minutes. The pH value of the solution after leaching is controlled to be 9. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.71%.

[0066] S3. After leaching is completed, vacuum filtration is used to separate the solid and liquid. The obtained solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution.

[0067] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 40%, and then cooled and crystallized at 20°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 40r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0068] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 35.7%, the dry basis content of available nitrogen is 5.9%, and the recovery rate of humic acid in phosphogypsum tailings is 98.39%.

[0069] Example 7

[0070] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0071] S1. After the gypsum phase is fully extracted from the phosphogypsum, the resulting tailings contain, by mass fraction, 14% humic acid, 16% apatite and 65% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or sieved and can be used as a raw material.

[0072] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:4g / mL. Then, at 50°C, a 10% ammonia solution is added as a leaching agent, stirred for 15 minutes, and the stirring rate is set to 50r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at 50°C for 40 minutes. The pH value of the solution after leaching is controlled to be 8.5. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.37%.

[0073] S3. After leaching is completed, vacuum filtration is used to separate the solid and liquid. The obtained solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution.

[0074] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 35%, and then cooled and crystallized at 10°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 30r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0075] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 40.6%, the dry basis content of available nitrogen is 6.4%, and the recovery rate of humic acid in phosphogypsum tailings is 99.16%.

[0076] Example 8

[0077] A method for recovering humic acid from phosphogypsum, comprising the following steps:

[0078] S1. After the gypsum phase is fully extracted from the phosphogypsum, the resulting tailings contain, by mass fraction, 15% humic acid, 20% apatite and 60% SiO2, and the remaining 5% is organic matter. It does not need to be crushed or sieved and can be used as a raw material.

[0079] S2. The raw material and water are prepared into a slurry, and the solid-liquid ratio of the raw material to water is 1:10g / mL. Then, at 20°C, a 5% ammonia solution is added dropwise as a leaching agent, stirred for 40 minutes, and the stirring rate is set to 60r / min. After the humic acid in the raw material is dissolved in the ammonia solution, it is leached at 20°C for 60 minutes. The pH value of the solution after leaching is controlled to be 8. Under this condition, the humic acid fully reacts with the ammonia solution in the solution to form a humic acid ammonium solution. The leaching rate of humic acid in the tailings is 99.25%.

[0080] S3. After leaching is completed, vacuum filtration is used to separate the solid and liquid. The obtained solid phase is an insoluble tailings, the specific components of which are a silicon-rich phase and a phosphorus-rich phase, and the filtrate is an ammonium humate solution.

[0081] S4. The obtained ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 40%, and then cooled and crystallized at 15°C. The ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The stirring speed of the centrifugal filtration is 50r / min. The crystallized solution is returned to step S2 for recycling as a leaching agent.

[0082] The obtained ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid in the product is 37.9%, the dry basis content of available nitrogen is 5.3%, and the recovery rate of humic acid in phosphogypsum tailings is 98.47%.

Claims

1. A method for recovering humic acid from phosphogypsum, characterized in that: The specific steps include: S1. After the gypsum phase is fully extracted from the phosphogypsum, the tailings obtained do not need to be crushed or sieved and are used as raw materials for standby use; S2. The raw material and water are configured into a slurry, and then an ammonia solution is used as a leaching agent for mixing, heating and stirring, and the humic acid in the raw material is dissolved in the ammonia solution and then stirred for leaching; S3. After leaching is completed, vacuum filtration is used for solid-liquid separation, the resulting solid phase is an insoluble tailings, and the filtrate is an ammonium humate solution; S4. The obtained ammonium humate solution is evaporated and concentrated, then cooled and crystallized, and the ammonium humate product and the crystallized solution are obtained by centrifugal filtration. The crystallized solution is returned to step S2 for recycling as a leaching agent.

2. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In step S1, the components of the tailings include, by mass fraction, 5% to 15% humic acid, 10% to 20% apatite, 60% to 80% SiO2, and the remaining 5% is organic matter.

3. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In the step S2, the solid-liquid ratio of the raw material to water is 1: (4-10) g / mL, and the mass percentage concentration of the ammonia solution is 5%-15%.

4. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In the step S2, the heating temperature is 20°C to 50°C, the stirring speed is 45 r / min to 120 r / min, and the stirring time is 10 min to 60 min.

5. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In the step S2, the leaching temperature of the stirring leaching is 20°C to 50°C, the leaching time is 20min to 60min, the pH value of the solution after leaching is controlled to be 8 to 9, and the leaching rate of humic acid in the tailings is ≥99%.

6. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In step S3, the specific components of the insoluble tailings are a silicon-rich phase and a phosphorus-rich phase.

7. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: In the step S4, the ammonium humate solution is evaporated and concentrated to a mass percentage concentration of 30% to 40%, the temperature during cooling and crystallization is 10° C. to 20° C., and the stirring speed of the centrifugal filtration is 30 r / min to 90 r / min.

8. A method for recovering humic acid from phosphogypsum according to claim 1, characterized in that: The ammonium humate product meets the industry standard requirements HG1-1143-78, the dry basis content of water-soluble humic acid of the first-class product is not less than 35%, and the dry basis content of available nitrogen is not less than 4%; the dry basis content of water-soluble humic acid of the second-class product is not less than 25%, and the dry basis content of available nitrogen is not less than 3%, and the recovery rate of humic acid in phosphogypsum tailings is ≥98%.

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