Comprehensive utilization method for extracting phosphorus, calcium and magnesium from hydrochloric acid acidolysis phosphate tailings

Abstract

The invention provides a comprehensive utilization method for extracting phosphorus, calcium and magnesium from hydrochloric acid acidolysis phosphate tailings, which comprises the following steps: preparing raw phosphate tailings into slurry, dropwise adding hydrochloric acid to react, and filtering to obtain filter residues and a leaching solution; the filter residues are sieved through a 120-mesh sieve, a 200-mesh sieve and a 300-mesh sieve respectively, flotation treatment is carried out, and residual dolomite in the filter residues is selected out; adding sulfate into the leaching solution, precipitating Ca < 2 + >, filtering filtrate, and circularly pulping until Mg < 2 + > in the leaching solution is saturated and precipitated; adding a saturated ammonium sulfate solution into the saturated leaching solution, precipitating Ca in the leaching solution into calcium sulfate, and carrying out carbonization treatment to convert the calcium sulfate into light calcium carbonate; and after Ca in the leaching solution is completely precipitated, gradually adjusting the pH value, sequentially precipitating phosphorus in the leaching solution into ammonium magnesium phosphate and Fe precipitation, adding a saturated ammonium carbonate solution to obtain high-purity magnesium carbonate, and filtering to obtain an ammonium chloride solution. The method is completely closed-loop, no waste is produced, the recycling rate of the phosphate tailings is increased, and the problems that the phosphate tailings are difficult to treat and single in application are solved.

Description

Technical Field

[0001] The invention relates to the technical field of resource utilization, and in particular to a method for extracting phosphorus, calcium and magnesium from phosphate tailings by hydrochloric acid acidization for comprehensive utilization. Background Art

[0002] my country's phosphorus resources rank second in the world, but about 90% are low- and medium-grade phosphate ore, with an average grade of about 17%. Therefore, before chemical phosphorus extraction, it is necessary to use mineral processing to obtain concentrate, and a large amount of tailings will be generated during the mineral processing process. "Phosphorus tailings are industrial solid wastes generated after phosphorus chemical industry purifies phosphorus concentrate. Under normal circumstances, 0.44 tons of phosphorus tailings will be generated for every ton of phosphorus concentrate produced; in addition to a small amount of P2O5, the tailings mainly contain metal / non-metal compounds such as magnesium, calcium, and silicon.

[0003] At present, the utilization of phosphate tailings is mainly concentrated in tailings re-selection, construction material preparation, fertilizer production, mine filling, etc., but the overall recycling rate is less than 10%. A large amount of phosphate tailings are stockpiled, which seriously endangers the safety of the ecological environment. As a result, the rational disposal and utilization of phosphate tailings has become an urgent problem to be solved.

[0004] The main components of phosphate tailings are carbonates of Ca and Mg, accounting for more than 75% of the total amount of phosphate tailings. How to use an appropriate method to separate and extract the Ca and Mg elements therein is undoubtedly the resource utilization of phosphate tailings, and is one of the important issues that continue to be solved in this field. Based on this, the present invention proposes a method for extracting phosphorus, calcium and magnesium from phosphate tailings by hydrochloric acid acid hydrolysis. Summary of the invention

[0005] Based on the above description, the present invention provides a method for comprehensive utilization of phosphorus, calcium and magnesium extracted from phosphate tailings by hydrochloric acid hydrolysis, so as to solve the technical problems that the recovery rate of existing phosphate tailings is insufficient, less than 10%, and the stockpiling treatment seriously endangers the safety of ecological environment.

[0006] The technical solution of the present invention to solve the above technical problems is as follows:

[0007] In a first aspect, the present invention provides a method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings, comprising the following steps:

[0008] S1: adding water to the original phosphorus tailings to prepare a slurry, controlling the slurry water bath temperature at 10-60° C., adding hydrochloric acid dropwise according to a preset solid acid ratio, and filtering after the reaction to obtain a filter residue and an leaching solution;

[0009] S2: passing the filter residue collected in step S1 through 120-mesh, 200-mesh and 300-mesh sieves respectively, and performing flotation treatment to select the dolomite remaining in the filter residue;

[0010] S3: Add sulfate to the leaching solution collected in step S1 to precipitate Ca 2+ , filter and collect gypsum, and circulate the filtrate for pulping until the Mg in the leaching solution is 2+ After reaching saturation, precipitation occurs;

[0011] S4: adding a saturated ammonium sulfate solution to the saturated leaching solution in step S3 to precipitate Ca in the leaching solution as calcium sulfate, and then carbonizing the leaching solution to convert it into light calcium carbonate;

[0012] S5: After the Ca in the leaching solution is completely precipitated, the pH is gradually adjusted to precipitate the phosphorus in the leaching solution into ammonium magnesium phosphate, precipitate the Fe in the leaching solution, add saturated ammonium carbonate solution to obtain high-purity magnesium carbonate, and filter to obtain ammonium chloride solution. At this point, the calcium, magnesium and phosphorus elements in the phosphate tailings are all extracted.

[0013] Based on the above technical solution, the present invention can also be improved as follows.

[0014] Furthermore, the specific process of flotation treatment in step S3 includes:

[0015] The filter residue collected in step S1 is passed through 120-mesh, 200-mesh and 300-mesh sieves respectively, wherein the minerals of the 120-mesh to 200-mesh sieves are added with a positive flotation agent for flotation treatment to select the dolomite remaining in the filter residue; the minerals of the 300-mesh sieve are subjected to a reverse flotation agent to remove organic matter, the pH is adjusted to 2-6, and a positive flotation agent is added to select the dolomite remaining in the filter residue.

[0016] Furthermore, the positive flotation reagent is a fatty acid collector.

[0017] Furthermore, the reverse flotation agent is an ether collector.

[0018] Furthermore, the reverse flotation agent comprises one or more of a surfactant, a flocculant, and a coupling agent.

[0019] Furthermore, the preparation of the slurry in step 1 is as follows: the original phosphate tailings are added with water to prepare a 5-75% slurry.

[0020] Furthermore, the carbon dioxide generated during the reaction of step S1 is collected by concentrated ammonia water to obtain high-purity ammonium bicarbonate crystals.

[0021] Furthermore, after step S4, the ammonium sulfate solution obtained by the carbonization process is used to precipitate Ca in the leaching solution to obtain calcium sulfate.

[0022] Further, in step S5, the pH is gradually adjusted, the phosphorus in the leaching solution is precipitated into ammonium magnesium phosphate, the Fe in the leaching solution is precipitated, and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate, which specifically includes:

[0023] Adjusting the pH to 2-6 to precipitate the phosphorus in the leaching solution into ammonium magnesium phosphate;

[0024] Adjust the pH to 8 to precipitate Fe in the leaching solution;

[0025] After the Fe precipitation is complete, the pH is adjusted to 10 and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate.

[0026] Furthermore, in step S5, after filtering to obtain the ammonium chloride solution, the method further includes: concentrating the ammonium chloride solution to obtain ammonium chloride crystals.

[0027] Compared with the prior art, the technical solution of this application has the following beneficial technical effects:

[0028] The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphorus tailings provided by the present invention has the following advantages compared with the existing method:

[0029] The method provided by the present invention utilizes solid waste phosphate tailings to produce phosphate ore, calcium carbonate and magnesium carbonate through hydrochloric acid leaching, flotation purification, chemical precipitation and other methods. The grade of the phosphate ore produced by the method can be increased from 4% to about 20%, and good phosphate fertilizer can be prepared; the purity of calcium carbonate is greater than 99%, and the whiteness is greater than 99%, which has the characteristics of high purity and high whiteness, and can be used as a good filler in coatings; by processing the phosphorus content in magnesium carbonate, it is a good raw material for preparing metal materials, glass and ceramics. The method is completely closed-loop, has no waste output, improves the recovery rate of phosphate tailings, solves the problems of difficult treatment and single application of phosphate tailings, and is environmentally friendly. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0031] Figure 1 A schematic flow chart of a method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0032] The specific implementation of the present invention is described in detail below. It should be understood that the specific implementation described here is only used to illustrate and explain the present invention, and is not used to limit the protection scope of the present invention.

[0033] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0034] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0035] The existing phosphate ore flotation process will produce a large amount of phosphate tailings as a by-product, and there is currently no better method for treating phosphate tailings. The long-term storage of phosphate tailings will not only cause serious pollution to the surrounding environment, but also continuously consume manpower and material resources, causing a huge economic burden. Based on this, the present invention utilizes phosphate tailings to produce phosphate ore with high economic value through a hydrochloric acid leaching-flotation purification process, and the cost is low and the product is stable; and the by-products of light calcium carbonate and magnesium carbonate have high economic value, and the wastewater in the whole process can be recycled and reused, and no other waste is generated, which provides a new idea for the application of phosphate tailings.

[0036] The following is combined with Figure 1 , providing multiple embodiments for introduction:

[0037] Example 1

[0038] The method provided in this embodiment for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphorus tailings comprises:

[0039] Step S1: 500g of the original phosphate tailings is added with water to form a 10% slurry, the slurry is placed in a 5L three-necked flask, the water bath temperature is controlled at about 45°C, and then hydrochloric acid is added dropwise according to a solid-acid ratio of 1:0.75 (in the present invention, the solid-acid ratio can be adaptively selected from 1:0.75-0.95 according to actual needs, and the amount of hydrochloric acid consumed by the decomposition of dolomite in the phosphate tailings can be provided), and the reaction is carried out for 5 hours. After the reaction is completed, the phosphate ore residue and the leaching liquid are obtained by filtering;

[0040] The carbon dioxide in the above reaction process is collected by ammonia water, and the ammonia water is converted into ammonium bicarbonate solution until saturation and precipitation of 300g of ammonium bicarbonate crystals; after the reaction is completed, the P2O5 grade in the filter residue is 16.98%, and the recovery rate of apatite in the filter residue is 78.1%, and the leaching solution is collected for the next acid hydrolysis and pulping;

[0041] Step S2: the filter residue is sieved through 120 mesh, 200 mesh and 300 mesh sieves, and the P2O5 content in the filter residue above 120 mesh is 19.87%, the P2O5 content in the filter residue below 200 mesh is 12.37%, and the P2O5 content in the filter residue below 300 mesh is 13.89%;

[0042] The minerals with 120-200 mesh sieves are added with a positive flotation agent (the positive flotation agent is a fatty acid collector) to select the dolomite remaining in the filter residue through a coarse and fine process, and the P2O5 content of the filter residue in the flotation tank is 20.26%; the minerals below 300 mesh are subjected to reverse flotation (the reverse flotation agent is a self-made ether collector, and the components are one or more of a surfactant, a flocculant, and a coupling agent) to remove organic matter, and the P2O5 content in the organic matter is 17.48%. Subsequently, the pH is adjusted to 4, and a positive flotation agent (the positive flotation agent is a fatty acid collector) is added to select the dolomite remaining in the filter residue, and the P2O5 content of the filter residue in the flotation tank is 19.75%.

[0043] Step S3: adding saturated ammonium sulfate solution to the saturated leaching solution to precipitate Ca in the leaching solution into calcium sulfate. The obtained calcium sulfate has a whiteness of 99.26% and a purity of 99.95%.

[0044] Gypsum is collected by filtration, and the filtrate is circulated and slurried until the Mg in the leaching solution is 2+ After reaching saturation, precipitation occurs.

[0045] Step S4: Then, the carbonization treatment is performed to convert the carbonized calcium into light calcium carbonate, the whiteness of which can reach 99.91% and the grade can reach 97.89%. Meanwhile, the ammonium sulfate solution obtained by the carbonization process is collected and used for precipitation to obtain calcium sulfate.

[0046] Step S5: After Ca is completely precipitated, ammonia water is added to adjust the pH to 5.5, and a small amount of phosphorus in the leaching solution is precipitated as ammonium magnesium phosphate; then the pH is adjusted to 8 to remove Fe ions in the filtrate; after the Fe ions are removed, the pH is adjusted to 10, and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate. At this time, the filtrate obtained by filtration is an ammonium chloride solution, and the ammonium chloride solution can be concentrated and distilled to obtain ammonium chloride crystals.

[0047] Example 2

[0048] The method provided in this embodiment for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphorus tailings comprises:

[0049] Step S1: 500 g of raw phosphorus tailings are added with water to prepare a 10% slurry, the slurry is placed in a 5 L three-necked flask, the water bath temperature is controlled at about 45° C., and hydrochloric acid is then added dropwise at a solid acid ratio of 1:0.85, and the reaction is carried out for 5 hours. After the reaction is completed, the phosphorus ore residue and the leaching liquid are obtained by filtering;

[0050] The carbon dioxide in the reaction process is collected by ammonia water, and the ammonia water is converted into ammonium bicarbonate solution until saturation and precipitation of 289g of ammonium bicarbonate crystals; after the reaction is completed, the P2O5 grade in the filter residue is 15.84% and the recovery rate of apatite in the filter residue is 74.8%. The leaching solution is collected and used for the next acid hydrolysis and pulping;

[0051] Step S2: the filter residue was sieved through 120 mesh, 200 mesh and 300 mesh sieves, and the P2O5 content in the filter residue above 120 mesh was 18.66%, the P2O5 content in the filter residue above 200 mesh was 11.38%, and the P2O5 content in the filter residue below 300 mesh was 13.19%;

[0052] The minerals with 120-200 meshes were added with positive flotation reagents to select the dolomite remaining in the filter residue through a coarse and fine process, and the P2O5 content of the filter residue in the flotation tank was 19.89%; the minerals below 300 meshes were subjected to reverse flotation to remove organic matter, and the P2O5 content in the organic matter was 16.94%. Subsequently, the pH was adjusted to 3, and the positive flotation reagent was added to select the dolomite remaining in the filter residue, and the P2O5 content of the filter residue in the flotation tank was 19.35%.

[0053] Step S3: Add saturated ammonium sulfate solution to the saturated leaching solution to precipitate Ca in the leaching solution into calcium sulfate. The obtained calcium sulfate has a whiteness of 99.35% and a purity of 99.93%. Gypsum is collected by filtration and the filtrate is circulated and pulped until the Mg in the leaching solution is 2+ After reaching saturation, precipitation occurs.

[0054] Step S4: Then, the carbonization treatment is performed to convert the carbonized calcium into light calcium carbonate, the whiteness of which can reach 99.88% and the grade can reach 97.95%. At the same time, the ammonium sulfate solution obtained by the carbonization process is collected and used for precipitation to obtain calcium sulfate.

[0055] Step S5: After Ca is completely precipitated, ammonia water is added to adjust the pH to 5.5, and a small amount of phosphorus in the leaching solution is precipitated as ammonium magnesium phosphate; then the pH is adjusted to 8 to remove Fe ions in the filtrate; after the Fe ions are removed, the pH is adjusted to 10, and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate. At this time, the filtrate obtained by filtration is an ammonium chloride solution, and the ammonium chloride solution can be concentrated and distilled to obtain ammonium chloride crystals.

[0056] Example 3

[0057] The method provided in this embodiment for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphorus tailings comprises:

[0058] Step S1: 500g of raw phosphorus tailings are added with water to prepare a 10% slurry, the slurry is placed in a 5L three-necked flask, the water bath temperature is controlled at about 45°C, and hydrochloric acid is then added dropwise at a solid acid ratio of 1:0.95, and the reaction is carried out for 5 hours. After the reaction is completed, the phosphorus ore residue and the leaching liquid are obtained by filtering;

[0059] The carbon dioxide in the reaction process is collected by ammonia water, and the ammonia water is converted into ammonium bicarbonate solution until saturation and precipitation of 297g of ammonium bicarbonate crystals; after the reaction is completed, the P2O5 grade in the filter residue is 16.56% and the recovery rate of apatite in the filter residue is 75.48%, and the leaching solution is collected for the next acid hydrolysis and pulping;

[0060] Step S2: the filter residue was sieved through 120 mesh, 200 mesh and 300 mesh sieves, and the P2O5 content in the filter residue above 120 mesh was 19.97%, the P2O5 content in the filter residue above 200 mesh was 12.88%, and the P2O5 content in the filter residue below 300 mesh was 13.19%;

[0061] The minerals with 120-200 meshes were added with positive flotation reagents to select the dolomite remaining in the filter residue through a coarse and fine process, and the P2O5 content of the filter residue in the flotation tank was 21.32%; the minerals below 300 meshes were subjected to reverse flotation to remove organic matter, and the P2O5 content in the organic matter was 17.23%. Then the pH was adjusted to 6, and the positive flotation reagent was added to select the dolomite remaining in the filter residue, and the P2O5 content of the filter residue in the flotation tank was 19.22%.

[0062] Step S3: Add saturated ammonium sulfate solution to the saturated leaching solution to precipitate Ca in the leaching solution into calcium sulfate. The obtained calcium sulfate has a whiteness of 99.75% and a purity of 99.84%. Gypsum is collected by filtration, and the filtrate is circulated and pulped until the Mg in the leaching solution is 2+ After reaching saturation, precipitation occurs.

[0063] Step S4: Then, the carbonization treatment is performed to convert the carbonized calcium into light calcium carbonate, the whiteness of which can reach 99.91% and the grade can reach 97.96%. At the same time, the ammonium sulfate solution obtained by the carbonization process is collected and used for precipitation to obtain calcium sulfate.

[0064] Step S5: After Ca is completely precipitated, ammonia water is added to adjust the pH to 6, and a small amount of phosphorus in the leaching solution is precipitated as ammonium magnesium phosphate; then the pH is adjusted to 8 to remove Fe ions in the filtrate; after the Fe ions are removed, the pH is adjusted to 10, and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate. At this time, the filtrate obtained by filtration is an ammonium chloride solution, and the ammonium chloride solution can be concentrated and distilled to obtain ammonium chloride crystals.

[0065] Comparative Example 1

[0066] Based on Example 1, the difference of this comparative example is that the method provided is to directly float the phosphate tailings before hydrochloric acid leaching. The P2O5 grade in the foam is 3.87%, and the MgO grade is 17.51%; the P2O5 grade in the ore sample at the bottom of the tank is 4.75%, and the MgO grade is 16.60%. There is no obvious difference between the composition of the ore sample in the foam and the composition of the ore sample at the bottom of the tank, indicating that the direct flotation of the phosphate tailings without acid leaching has a weak collecting ability of the collector and a poor flotation effect.

[0067] In Example 1, the phosphorus tailings were floated after hydrochloric acid leaching, and the corresponding P2O5 grade in the foam was 4.60%, and the MgO grade was 17.58%; the P2O5 grade in the bottom ore sample was 19.93%, and the MgO grade was 7.19%. After acid leaching, the flotation was performed, and the composition of the ore sample in the foam and the composition of the ore sample in the bottom of the trough were significantly different, indicating that the flotation efficiency was qualitatively improved after acid leaching.

[0068] Since phosphate tailings are the unutilized solid waste discharged during the flotation of phosphate concentrate, their mineral composition is complex, including some undissociated collophanite and dolomite, and it is difficult to effectively separate phosphate from dolomite by flotation at this time. Therefore, hydrochloric acid leaching can decompose the dolomite wrapped on the surface of phosphate, and a small amount of undecomposed dolomite will be separated from the phosphate, so that the reagent can better interact with the ore sample and improve the flotation efficiency.

[0069] Comparative Example 2

[0070] Based on Example 1, the difference of this comparative example is that the method provided is direct flotation without screening. The P2O5 grade in the foam is 8.03%, the MgO grade is 13.78%, and the P2O5 recovery rate is only 65.59%.

[0071] In Example 1, after screening, the flotation of the ore sample above 120 mesh obtained a P2O5 grade of 2.88%, a MgO grade of 18.32%, and a P2O5 recovery rate of 96.63% in the foam; the flotation of the ore sample of 120-300 mesh obtained a P2O5 grade of 2.11% in the foam, a MgO grade of 17.58%, and a P2O5 recovery rate of 89.77%; the flotation of the ore sample below 300 mesh obtained a P2O5 grade of 15.7% in the effective mineral, a MgO grade of 4.98%, and a P2O5 recovery rate of 91.11%.

[0072] In the flotation process, by adjusting the particle size and specific physical and chemical properties of the selected minerals, effective separation of mineral particles can be achieved. The main connection between this and the sieve mesh number is that the sieve mesh number determines the particle size distribution range of the mineral particles, which in turn affects the flotation effect.

[0073] Through the analysis of the fineness of mineral particles after acid leaching of phosphorus tailings, it was found that the content of P2O5 in the mineral composition above 120 mesh is the highest, the content of P2O5 in the mineral composition of 120 mesh-300 mesh is the lowest, and the content of P2O5 in the mineral composition below 300 mesh is in the middle; at the same time, the content of organic matter in the ore samples below 300 mesh is relatively high, and the presence of organic matter will affect the flotation efficiency of the reagent, and reverse flotation is required to remove the organic matter before forward flotation; the content of organic matter in the mineral above 300 mesh is not high, and there is no need for reverse flotation to remove the organic matter. Targeted flotation of minerals of different particle sizes can improve the flotation efficiency.

[0074] In summary, the method for comprehensive utilization of phosphorus, calcium and magnesium extracted from phosphate tailings by hydrochloric acid acid hydrolysis provided by the embodiment of the present invention utilizes solid waste phosphate tailings to produce phosphate ore, calcium carbonate and magnesium carbonate by methods such as hydrochloric acid leaching, flotation purification, and chemical precipitation. The grade of phosphate ore produced by the method can be increased from 4% to about 20%, and good phosphate fertilizer can be prepared; the purity of calcium carbonate is greater than 99%, and the whiteness is greater than 99%, which has the characteristics of high purity and high whiteness, and can be used as a good filler in coatings; by treating the low phosphorus content in magnesium carbonate, it is a good raw material for preparing metal materials, glass and ceramics. The method is completely closed-loop, has no waste output, improves the recovery rate of phosphate tailings, solves the problems of difficult treatment and single application of phosphate tailings, and is environmentally friendly.

[0075] In the description of this specification, the description with reference to the terms "specific example" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiment of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example.

[0076] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for comprehensive utilization of phosphorus, calcium and magnesium by hydrochloric acid hydrolysis of phosphate tailings, characterized in that: The steps include: S1: adding water to the original phosphorus tailings to prepare a slurry, controlling the slurry water bath temperature at 10-60° C., adding hydrochloric acid dropwise according to a preset solid acid ratio, and filtering after the reaction to obtain a filter residue and an leaching solution; S2: passing the filter residue collected in step S1 through 120-mesh, 200-mesh and 300-mesh sieves respectively, and performing flotation treatment to select the dolomite remaining in the filter residue; S3: Add sulfate to the leaching solution collected in step S1 to precipitate Ca 2+ , filter and collect gypsum, and circulate the filtrate for pulping until the Mg in the leaching solution is 2+ After reaching saturation, precipitation occurs; S4: adding a saturated ammonium sulfate solution to the saturated leaching solution in step S3 to precipitate Ca in the leaching solution as calcium sulfate, and then carbonizing the leaching solution to convert it into light calcium carbonate; S5: After the Ca in the leaching solution is completely precipitated, the pH is gradually adjusted to precipitate the phosphorus in the leaching solution into ammonium magnesium phosphate, precipitate the Fe in the leaching solution, add saturated ammonium carbonate solution to obtain high-purity magnesium carbonate, and filter to obtain ammonium chloride solution. At this point, the calcium, magnesium and phosphorus elements in the phosphate tailings are all extracted.

2. The method for comprehensive utilization of phosphorus, calcium and magnesium by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: The specific process of flotation treatment in step S3 includes: The filter residue collected in step S1 is passed through 120-mesh, 200-mesh and 300-mesh sieves respectively, wherein the minerals of the 120-mesh to 200-mesh sieves are added with a positive flotation agent for flotation treatment to select the dolomite remaining in the filter residue; the minerals of the 300-mesh sieve are subjected to a reverse flotation agent to remove organic matter, the pH is adjusted to 2-6, and a positive flotation agent is added to select the dolomite remaining in the filter residue.

3. The method for comprehensive utilization of phosphorus, calcium and magnesium by hydrochloric acid hydrolysis of phosphate tailings according to claim 2, characterized in that: The positive flotation reagent is a fatty acid collector.

4. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 2, characterized in that: The reverse flotation agent is an ether collector.

5. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 4, characterized in that: The reverse flotation agent comprises one or more components of a surfactant, a flocculant, and a coupling agent.

6. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: The preparation of the slurry in step 1 is as follows: take the original phosphorus tailings and add water to prepare a 5-75% slurry.

7. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: The carbon dioxide generated during the reaction of step S1 is collected by concentrated ammonia water to obtain high-purity ammonium bicarbonate crystals.

8. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: After step S4, the ammonium sulfate solution obtained by the carbonization process is used to precipitate Ca in the leaching solution to obtain calcium sulfate.

9. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: In step S5, the pH is gradually adjusted to sequentially precipitate the phosphorus in the leaching solution into ammonium magnesium phosphate, precipitate the Fe in the leaching solution, and add a saturated ammonium carbonate solution to obtain high-purity magnesium carbonate, specifically comprising: Adjusting the pH to 2-6 to precipitate the phosphorus in the leaching solution into ammonium magnesium phosphate; Adjust the pH to 8 to precipitate Fe in the leaching solution; After the Fe precipitation is complete, the pH is adjusted to 10 and a saturated ammonium carbonate solution is added to obtain high-purity magnesium carbonate.

10. The method for comprehensive utilization of phosphorus, calcium and magnesium extracted by hydrochloric acid hydrolysis of phosphate tailings according to claim 1, characterized in that: In step S5, after filtering to obtain the ammonium chloride solution, the process further includes: concentrating the ammonium chloride solution to obtain ammonium chloride crystals.

Images