Process for removing impurity metal ions and compounds from raffinate acid

Abstract

The present application belongs to the technical field of mineral processing and environmental protection, and particularly relates to a method for removing impurity metal ions and compounds in raffinate acid. The impurity metal ions and compounds such as iron, magnesium and aluminum in the raffinate acid are selectively removed under the synergistic action of adsorption materials and flotation reagents. The method mainly uses the strong adsorption of the adsorption materials and the strong selectivity of the specific flotation reagents, and uses the adsorption materials and the flotation reagents in combination, and through adjusting and controlling the types, the ratio, the dosage of the adsorption materials and the flotation reagents, and the reaction sequence, the time and the temperature, the selective removal of the impurity metal ions and compounds in the raffinate acid is realized, and the comprehensive utilization rate of the raffinate acid is improved. The method is suitable for the purification system of the raffinate acid in the phosphorus chemical industry, and has the advantages of simple method, strong selectivity, remarkable effect and short action time, and has important significance for solving the problems of difficult disposal and reuse of the raffinate acid, high production cost of the phosphorus chemical industry and serious waste of phosphorus resources.

Description

Technical Field

[0001] This invention belongs to the field of mineral processing technology utilization and environmental protection technology, specifically relating to a method for removing impurity metal ions and compounds from raffinate. Background Technology

[0002] With the continuous advancement of phosphate chemical technology, the quality of refined phosphoric acid has been steadily improving, and phosphorus resources are expanding horizontally into agriculture, industry, food, and pharmaceuticals. Due to limitations in industrial purification methods, wet-process phosphoric acid inevitably produces raffinate as a byproduct during solvent extraction. Simultaneously, as the grade of phosphate rock decreases and the content of dilute acid impurities increases, the proportion of raffinate shows an increasing trend. The quality of raffinate is slightly lower than that of ordinary phosphoric acid, but its P2O5 content reaches 40% or even higher. Based on maximizing the benefits of phosphorus resources, raffinate has gradually become an indispensable resource in the phosphate chemical industry. This byproduct is used in the production of ammonium phosphate fertilizers (MAP, DAP) and superphosphate; its resource utilization is an important way to improve the recovery rate of phosphorus resources, and can also greatly enhance the use value and economic value of phosphorus resources. However, as a byproduct, raffinate has a complex composition, with many types and high contents of impurities, and is viscous with poor flowability. Impurities in residual acid exist in the form of metal ions and compounds such as iron, magnesium, and aluminum, which increase the viscosity of phosphoric acid, reduce its quality, and hinder pipeline transportation, seriously affecting the normal production and application of phosphoric acid.

[0003] Faced with increasingly severe problems of resource waste and environmental pollution, how to rationally purify and utilize residual raffinate has become one of the key directions for the development of phosphate chemical enterprises. The efficient removal of impurity metal ions from residual raffinate has always been a challenge in purification technology, especially the removal of metal ions and compounds such as iron, magnesium, and aluminum. Traditional treatment methods, such as single chemical precipitation, have relatively limited capacity and are difficult to achieve effective removal of metal ions; extraction purification and membrane exchange methods require additional extraction, distillation, and membrane exchange equipment, resulting in high processing costs and complex operations. Therefore, the development and application of novel purification technologies for residual raffinate are urgently needed.

[0004] Furthermore, traditional purification methods are confined to the chemical industry, neglecting the essential nature of phosphorus resources as mineral resources. From the perspective of comprehensive recovery and utilization of mineral resources, combining mineral sorting with chemical engineering, and developing a high-efficiency purification technology for raffinate to efficiently remove impurities such as iron, magnesium, and aluminum, can achieve the recycling of raffinate, reduce industrial waste emissions, and has profound significance for the comprehensive recovery and utilization of secondary resources and environmental protection. Summary of the Invention

[0005] The purpose of this invention is to provide a method for removing impurity metal ions and compounds from raffinate. This method utilizes the strong adsorption properties of the adsorbent material and the strong selectivity of a specific flotation reagent to synergistically remove impurity metal ions and compounds, thereby achieving highly efficient purification of the raffinate.

[0006] The method for removing impurity metal ions and compounds from raffinate according to the present invention selectively removes impurity metal compounds from raffinate under the synergistic effect of adsorption materials and flotation reagents.

[0007] in:

[0008] The residual acid comprises one or both of the following: the raw liquid system containing residue or the filtered clear liquid system.

[0009] The solid content of the slag-containing raw liquid system is 30%-80%, and the impurities in the slag-containing raw liquid system are in a state of dissolution equilibrium in the solid and liquid phases.

[0010] The solid content of the filtered clear liquid system is 0;

[0011] When the raw liquid system containing slag and the filtered clear liquid system coexist, the solid content is 1% to 30%;

[0012] The impurities in both the raw liquid system containing slag and the filtered clear liquid system contain one or two of the following: metal ions or metal compounds. The metal ions include at least one of iron, magnesium, aluminum, titanium, or calcium; the metal compounds include at least one of ferric oxide, magnesium oxide, aluminum oxide, titanium dioxide, or calcium oxide.

[0013] The adsorption material is at least one of activated carbon, magnetic material or silicate material;

[0014] The flotation reagent is at least one of fluorosilicic acid reagents, starch reagents, or phosphate reagents.

[0015] in:

[0016] The activated carbon material is at least one of coconut shell activated carbon, apricot shell activated carbon, fruit kernel shell activated carbon, walnut shell activated carbon, wood activated carbon, or coal-based activated carbon.

[0017] The magnetic material is at least one of pyrometallurgical hematite or pyrometallurgical magnetite.

[0018] The silicate material is at least one of sepiolite, garnet, halloysite, montmorillonite, or palygorskite.

[0019] Fluorosilicic acid agents are at least one of fluorosilicic acid, sodium fluorosilicate, or calcium fluorosilicate.

[0020] Starch-based agents are at least one of corn starch, potato starch, Pb-based starch, Al-based starch, or Fe-based starch.

[0021] Phosphate-based agents are at least one of sodium hexametaphosphate or sodium pyrophosphate.

[0022] Raffinate is a byproduct of the extraction process in the production of phosphoric acid in the phosphate chemical industry. The raw liquid containing slag is the raffinate that has not undergone any treatment, while the filtered liquid is the raffinate after sedimentation and filtration. The two have significant differences in component content, fluidity, and treatment difficulty, and therefore are studied in different systems during the treatment process.

[0023] When treating a raw liquid system containing slag, flotation reagents should be added before or simultaneously with the adsorption material. The mass ratio of adsorption material to flotation reagents is 5:1 to 1:9. The total amount of adsorption material and flotation reagents added to the raw liquid system containing slag is 50 to 200 g / L. The reaction time is 10 to 30 min, and the reaction temperature is 30 to 60℃.

[0024] When treating the filtrate system, the adsorbent material should be added before or simultaneously with the flotation reagent. The mass ratio of the adsorbent material to the flotation reagent is 9:1 to 1:5. The total amount of adsorbent material and flotation reagent added to the filtrate system is 10 to 100 g / L. The reaction time is 5 to 20 min and the reaction temperature is 10 to 50 °C.

[0025] When treating a system where raw liquid containing slag and filtered clear liquid coexist, the adsorption reagent and flotation reagent are added simultaneously. The mass ratio of adsorption material to flotation reagent is 5:1 to 1:5. The total amount of adsorption material and flotation reagent added to the coexisting system is 50 to 150 g / L. The reaction time is 10 to 20 min, and the reaction temperature is 30 to 50℃.

[0026] The key to the method for removing impurity metal ions and compounds from raffinate described in this invention lies in the specific types, ratios, reaction sequences, reaction times, and reaction temperatures of the adsorption materials and flotation reagents used for raffinate with different compositions. Research has revealed significant differences in the composition and properties of the slag-containing raw liquid system, the filtered clarified liquid system, and the coexistence of both in raffinate. Consequently, the adsorption materials and flotation reagents used also differ significantly. For the slag-containing raw liquid system, the solid content is high, and impurities exist in both solid and liquid phases in a state of dissolution equilibrium. Therefore, while removing impurity metal ions and elements from the liquid phase, it is also necessary to prevent the dissolution of metal ions from the solid phase. Thus, flotation reagents are added first or simultaneously to prevent the dissolution of solid-phase impurities and to complex the liquid-phase impurities. At the same time, the overall dosage is increased, the reaction time is extended, and the reaction temperature is raised to ensure complete reaction. For the clarified filtrate, impurity metal ions and compounds exist only in the liquid phase. Therefore, to enhance the removal effect, adsorbent material is added first or simultaneously to fully adsorb impurity metal ions and compounds, followed by the addition of flotation reagents to complex difficult-to-treat impurity metals. The reagent dosage, reaction time, and temperature are all reduced compared to the slag-containing raw solution. For the system where slag-containing raw solution and clarified filtrate coexist, there is both a certain solid content and sufficient liquid phase; therefore, the treatment conditions such as dosage, ratio, sequence, time, and temperature fall between those of the slag-containing raw solution and the clarified filtrate.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] (1) The method for removing impurity metal ions and compounds from raffinate described in this invention utilizes the strong adsorption properties of the adsorption material and the strong selectivity of the specific flotation reagent to synergistically remove impurity metal ions and compounds, thereby achieving efficient purification of raffinate. It can selectively remove specific impurity metal ions and compounds for different raffinate components without causing loss of phosphorus resources. It can solve the problem of difficulty in reusing raffinate caused by excessive impurity metal ions and compounds, improve the utilization rate of phosphorus resources in raffinate, and solve the environmental pollution caused by the accumulation of by-products, thus achieving the dual goals of resource conservation and environmental friendliness.

[0029] (2) The method for removing impurity metal ions and compounds from raffinate described in this invention uses adsorption materials and flotation reagents in synergy, and achieves selective removal of impurity metal ions and compounds from raffinate by controlling the types, ratios, amounts, reaction order, time and temperature of materials and reagents, thereby improving the comprehensive utilization rate of raffinate.

[0030] (3) The method for removing impurity metal ions and compounds from residual acid described in this invention is applicable to the purification system of residual acid in the phosphorus chemical industry. The method is simple, highly selective, effective, and has a short action time. It is of great significance for solving problems such as the difficulty in disposing of and reusing residual acid, the high production cost of phosphorus chemical industry, and the serious waste of phosphorus resources. Attached Figure Description

[0031] Figure 1 This is a comparison chart showing the effects of treating the residual acid-containing raw liquid before and after the treatment when the amount of coal-based activated carbon is 100 g / L and the amount of potato starch is 100 g / L in Example 1.

[0032] Figure 2 This is a comparison chart showing the effects of treating the residual acid filtrate before and after treatment when the amount of sepiolite and fluorosilicic acid used in Example 2 was 20 g / L. Detailed Implementation

[0033] The present invention will be further described below with reference to embodiments.

[0034] Example 1

[0035] Using a residue-containing liquid (60% solids content) from a certain source of acid extraction in Guizhou as the test object, coal-based activated carbon was selected as the adsorbent and potato starch as the flotation reagent. The reaction temperature was 40℃ and the reaction time was 20 min. Dosage experiments were conducted, and the results are shown below. The experiment shows that the synergistic effect of coal-based activated carbon and potato starch is significantly stronger than that of using them alone. With the increase of reagent dosage, the contents of Al2O3, Fe2O3, and MgO decreased significantly, while the content of P2O5 increased slightly, and the MER value (the percentage of impurity metal compound content to P2O5 content) decreased significantly. When the total dosage of activated carbon and starch is 40 g / L (below 50 g / L), the contents of Al2O3, Fe2O3, and MgO, as well as the MER value, decrease but do not reach the optimal level. When the total dosage of activated carbon and starch reaches 200 g / L, the contents of Al2O3, Fe2O3, and MgO, as well as the MER value, reach their lowest values, and the purification effect is optimal. When the total dosage exceeds 200 g / L, while the content of impurity metal compounds decreases, the content of P2O5 also decreases significantly, and the MER value increases instead of decreasing, resulting in a significant loss of phosphorus resources. Meanwhile, if... Figure 1 As shown, when the amount of coal-based activated carbon is 100 g / L and the amount of potato starch is 100 g / L, the acid solution treated under the optimal conditions has advantages in terms of color, transmittance, and fluidity compared to the untreated filtrate (acid solution).

[0036] Table 1. Test results of residual acid-containing raw solution

[0037]

[0038] Example 2

[0039] Using the filtrate of residual acid from a phosphate chemical plant in Hubei Province as the experimental subject, the reaction temperature was fixed at 20℃, the reaction time at 10 min, and the total dosage at 40 g / L. The effects of the dosage and ratio of sepiolite, fluorosilicic acid, and Al-based starch on the metal impurities and MER value of the residual acid were studied. The results are shown below. The experiment shows that the synergistic effect is better than the effect of a single effect; a 1:1 mass ratio of sepiolite to fluorosilicic acid can reduce the content of Al2O3 and MgO, and reduce the MER value of the residual acid.

[0040] Table 2 Results of the test on the filtrate of residual acid.

[0041]

[0042]

[0043] Example 3

[0044] Using a coexisting system of residual acid residue and filtrate from a Guizhou extraction plant as the experimental subject, with a fixed reaction temperature of 45℃ and a reaction time of 15 min, the effects of the ratio and dosage of pyrometallurgically calcined magnetite and sodium hexametaphosphate on the removal of impurity metals were studied. The results are shown below. The results indicate that, with a fixed overall dosage, the synergistic effect of pyrometallurgically calcined magnetite and sodium hexametaphosphate is better than that of either. In the synergistic effect, a higher proportion of pyrometallurgically calcined magnetite compared to sodium hexametaphosphate results in better impurity metal removal and a lower MER value. When the total dosage is below 150 g / L, the impurity metal content decreases significantly with increasing dosage; when the total dosage exceeds 150 g / L, the decrease in MER becomes slower with increasing dosage.

[0045] Table 3 Results of the test on the filtrate of residual acid.

[0046]

Claims

1. A method for removing impurity metal ions and compounds from residual acid, characterized in that: Impurity metal compounds in the raffinate are selectively removed through the synergistic effect of adsorption materials and flotation reagents; in: The residual acid comprises one or both of the following: the raw liquid system containing residue or the filtered clear liquid system. The solid content of the slag-containing raw liquid system is 30%-80%, and the impurities in the slag-containing raw liquid system are in a state of dissolution equilibrium in the solid and liquid phases. The solid content of the filtered clear liquid system is 0; When the raw liquid containing slag and the filtered clear liquid coexist, the solid content is 1%~30%; The impurities in both the raw liquid system containing slag and the filtered clear liquid system contain one or two of the following: metal ions or metal compounds. The metal ions include at least one of iron, magnesium, aluminum, titanium, or calcium; the metal compounds include at least one of ferric oxide, magnesium oxide, aluminum oxide, titanium dioxide, or calcium oxide. The adsorption material is at least one of activated carbon, magnetic material or silicate material; The flotation reagent is at least one of fluorosilicic acid reagents, starch reagents, or phosphate reagents; in: When treating a raw liquid system containing slag, flotation reagents should be added before or simultaneously with the adsorption material. The mass ratio of adsorption material to flotation reagents is 5:1 to 1:

9. The total amount of adsorption material and flotation reagents added to the raw liquid system containing slag is 50 to 200 g / L. The reaction time is 10 to 30 min and the reaction temperature is 30 to 60℃. When treating the filtrate system, the adsorbent material should be added before or simultaneously with the flotation reagent. The mass ratio of the adsorbent material to the flotation reagent is 9:1 to 1:

5. The total amount of adsorbent material and flotation reagent added to the filtrate system is 10 to 100 g / L. The reaction time is 5 to 20 min and the reaction temperature is 10 to 50℃. When treating a system where raw liquid containing slag and filtered clear liquid coexist, the adsorption reagent and flotation reagent are added simultaneously. The mass ratio of adsorption material to flotation reagent is 5:1 to 1:

5. The total amount of adsorption material and flotation reagent added to the coexisting system is 50 to 150 g / L. The reaction time is 10 to 20 min, and the reaction temperature is 30 to 50℃.

2. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: The activated carbon material is at least one of coconut shell activated carbon, apricot shell activated carbon, fruit kernel shell activated carbon, walnut shell activated carbon, wood activated carbon, or coal-based activated carbon.

3. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: The magnetic material is at least one of pyrometallurgical hematite or pyrometallurgical magnetite.

4. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: The silicate material is at least one of sepiolite, garnet, halloysite, montmorillonite, or palygorskite.

5. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: Fluorosilicic acid agents are at least one of fluorosilicic acid, sodium fluorosilicate, or calcium fluorosilicate.

6. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: Starch-based agents are at least one of corn starch, potato starch, Pb-based starch, Al-based starch, or Fe-based starch.

7. The method for removing impurity metal ions and compounds from residual acid according to claim 1, characterized in that: Phosphate-based agents are at least one of sodium hexametaphosphate or sodium pyrophosphate.

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