P 204 Method for removing calcium and magnesium from rare earth industry wastewater, respectively

Abstract

This invention discloses a method using P 204 Methods for removing calcium and magnesium from rare earth industrial wastewater include: using P 204 As an extractant, P 204 Single-stage extraction was performed with the wastewater to remove calcium ions. The calcium-loaded organic phase was back-extracted and washed with hydrochloric acid to obtain a blank organic phase and a calcium chloride solution. P was then used... 204 As an extractant, the extractant undergoes saponification with an alkaline solution, and the saponified P... 204 Multi-stage extraction with low-calcium wastewater allows magnesium ions in the wastewater to react with phosphorus... 204 In combination, the magnesium-loaded organic phase is back-extracted and washed with hydrochloric acid to obtain a blank organic phase and a magnesium chloride solution. This invention achieves separate removal of calcium and magnesium ions from wastewater, with large processing capacity, fast reaction rate, good separation effect, no introduction of new impurities, no wastewater generation, and the extractant can be recycled.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of wastewater pretreatment in rare earth hydrometallurgy, and particularly relates to a method for removing calcium and magnesium ions in rare earth industrial wastewater by using P 204 Methods for removing calcium and magnesium ions in rare earth industrial wastewater, respectively. BACKGROUND

[0002] In the rare earth industry, metal ions are produced and other impurities are separated by using extraction method, and a large amount of production wastewater is generated in the production process, which seriously pollutes the environment and restricts the sustainable and healthy development of the industry. With the gradual improvement of the national pollution discharge standard, enterprises have carried out clean production and wastewater comprehensive treatment work. The production wastewater is crystallized into corresponding salt through evaporation, concentration and other processes, and the generated condensed water is recycled. Due to the addition of calcium oxide and magnesium oxide in the production process, a certain amount of calcium and magnesium ions are contained in the wastewater, which affects the smooth progress of the subsequent wastewater treatment process and the quality of the crystallized salt after wastewater treatment.

[0003] Magnesium is one of the commonly used non-ferrous metals, and magnesium and its alloys are widely used in aerospace, automobile, construction and other industries. Therefore, it is of great significance to recycle and utilize magnesium resources. Therefore, how to remove calcium and magnesium ions in wastewater, recycle magnesium ions in wastewater, improve the added value of wastewater treatment, and ensure that the crystallized salt in the subsequent wastewater treatment process is a single component is of great significance to enterprises.

[0004] A large amount of ammonium sulfate wastewater, ammonium chloride wastewater and magnesium sulfate wastewater is generated in the production and smelting process of rare earth, and the existence of excessive calcium and magnesium ions in the wastewater will affect the quality of the corresponding ammonium sulfate, ammonium chloride and magnesium sulfate, and reduce the efficiency and service life of the wastewater treatment facilities.

[0005] Publication No. CN105461002A discloses a method for treating ammonium sulfate wastewater. The ammonium sulfate wastewater generated in the rare earth acid smelting process is the treatment object. P 507 50% volume ratio of sulfonated kerosene is added as an organic extractant, and extraction is carried out under the conditions of an organic phase to liquid phase volume ratio of 1-2 and a saponification rate of 45%-60%. After extraction, the layers are separated after standing. This process uses P 507 And saponification is needed.

[0006] Publication No. CN103964556A discloses a method for separating calcium and magnesium ions in ammonium sulfate wastewater. Soluble phosphate is added to the wastewater to introduce phosphate radicals, and calcium phosphate and ammonium magnesium phosphate crystal precipitates are generated, which are then separated from the liquid, and the calcium and magnesium ions in the wastewater are removed. This process introduces new impurities, phosphate radicals, while removing calcium and magnesium ions, increasing the difficulty of subsequent wastewater treatment. SUMMARY

[0007] The purpose of the present application is to provide a method for removing calcium and magnesium ions in rare earth industrial wastewater by using P 204The method for removing calcium and magnesium in rare earth industrial wastewater respectively realizes separate removal of calcium and magnesium ions in the wastewater, has large treatment capacity, fast reaction speed, good separation effect, no introduction of new impurities, no generation of wastewater, and recyclable use of the extractant.

[0008] To achieve the above-mentioned purpose, the technical solution used by the application is:

[0009] P 204 The method for removing calcium and magnesium in rare earth industrial wastewater respectively includes:

[0010] P 204 is used as the extractant, P 204 is subjected to single-stage extraction with the wastewater, calcium ions in the wastewater are removed, and the organic phase loaded with the calcium ions is subjected to back extraction with hydrochloric acid to be washed into blank organic phase and calcium chloride solution;

[0011] P 204 is used as the extractant, the extractant is subjected to saponification with an alkaline solution, and the saponified P 204 is subjected to multi-stage extraction with low-calcium wastewater, magnesium ions in the low-calcium wastewater are combined with P 204 , and the organic phase loaded with the magnesium ions is subjected to back extraction with hydrochloric acid to be washed into blank organic phase and magnesium chloride solution.

[0012] Further, P 204 is mixed with kerosene to be used as the extractant, the extractant is subjected to single-stage extraction with the wastewater, calcium ions in the wastewater are combined with P 204 , low-calcium wastewater is discharged from the extraction equipment, and the organic phase loaded with the calcium ions is subjected to multi-stage back extraction with hydrochloric acid to be washed into blank organic phase and calcium chloride solution.

[0013] Further, in the process of removing calcium ions in the wastewater, P 204 has a concentration of 1-1.8 mol / l, the phase ratio of the wastewater to the organic phase is 1-10:1, and the concentration of hydrochloric acid is 2-8 mol / l.

[0014] Further, P 204 is mixed with kerosene to be used as the extractant, and the extractant is subjected to saponification with ammonia water.

[0015] Further, in the process of removing magnesium ions in the wastewater, P 204 has a concentration of 1-1.8 mol / l, the saponification rate is 33%-53%, the phase ratio of low-calcium wastewater to the organic phase is 1-2:1, and the concentration of hydrochloric acid is 2-8 mol / l.

[0016] Further, low-calcium and magnesium wastewater is discharged from the extraction equipment, calcium chloride solution and magnesium chloride solution are introduced out of the extraction equipment to be continuously used, and blank organic phase is recycled.

[0017] The technical effects of the application include:

[0018] 1. This invention enables the separate removal of calcium and magnesium ions from wastewater, allowing for the recovery of pure magnesium resources and the acquisition of corresponding high-quality products.

[0019] Ensuring that the combined calcium and magnesium content in the wastewater is less than 0.05 g / L guarantees the smooth progress of subsequent wastewater treatment processes and ensures the quality of the corresponding products.

[0020] After extraction and settling, the removal rates of calcium and magnesium ions in the original wastewater can reach over 98%. This process connects to subsequent processes in the pretreatment of wastewater for resource utilization, ensuring the quality of by-products.

[0021] 2. This invention enables continuous production, has a large processing capacity, fast reaction speed, good separation effect, and the extractant can be recycled.

[0022] 3. This invention is environmentally friendly, removing calcium and magnesium ions in stages, and can effectively recover magnesium resources from rare earth industrial wastewater, bringing social benefits while creating economic benefits.

[0023] This invention is applied to the rare earth hydrometallurgical production process, and the removal of calcium and magnesium ions from the generated industrial wastewater can achieve stepwise treatment of calcium and magnesium ions, thereby recovering magnesium resources.

[0024] 4. The treatment method is simple. Just connect a few extraction tanks at the wastewater outlet, and the wastewater at the outlet can directly enter the wastewater treatment system. Attached Figure Description

[0025] Figure 1 In this invention, P is used 204 Flowcharts of methods for removing calcium and magnesium from rare earth industrial wastewater. Detailed Implementation

[0026] The following description fully illustrates specific embodiments of the invention to enable those skilled in the art to practice and reproduce them.

[0027] like Figure 1 As shown, this is the P used in this invention. 204 Flowcharts of methods for removing calcium and magnesium from rare earth industrial wastewater.

[0028] Use P 204 The method for removing calcium and magnesium from rare earth industrial wastewater involves first removing calcium ions from the wastewater through single-stage extraction without saponification; then, removing magnesium ions from low-calcium wastewater through multi-stage extraction with controlled saponification; the calcium and magnesium ions are then converted into calcium chloride and magnesium chloride solutions, respectively, for stepwise removal of calcium and magnesium ions from the wastewater, thus recovering and utilizing magnesium resources, resulting in wastewater with low impurity content. The specific steps are as follows:

[0029] Step 1: Use P 204 As an extractant, P204 Single stage extraction with waste water, removing calcium ions in waste water, loaded calcium ions organic phase using hydrochloric acid back extraction, washing into blank organic phase and calcium chloride solution;

[0030] P 204 Mixed with kerosene as extractant, single stage extraction with waste water, calcium ions in waste water combined with P 204 , low calcium waste water discharged from extraction equipment, loaded calcium ions organic phase back extracted by using hydrochloric acid, washed into blank organic phase and calcium chloride solution, blank organic phase recycled.

[0031] Reaction formula as follows: Ca 2+ +2(HA)2→Ca(HA2)2+2H +

[0032] Ca(HA2)2+2HCl→CaCl2+(HA)2

[0033] Control conditions:

[0034] P 204 Concentration = 1-1.8 mol / l;

[0035] Ratio (waste water: organic phase) = 1-10:1;

[0036] Hydrochloric acid concentration = 2-8 mol / l.

[0037] Using extractant P 204 Non-saponification calcium removal, non-saponification, no new impurities introduced, lower cost, no waste water produced. At the same time P 204 Extraction of calcium requires pH 2-3, while P 507 Extraction of calcium requires pH 5-6, P 204 Higher equilibrium acidity, P 204 Extraction capacity greater than P 507 , not easy to produce emulsion.

[0038] Step 2: using P 204 As an extractant, the extractant is saponified with an alkaline solution, saponified P 204 Multi-stage extraction with low calcium waste water, magnesium ions in low calcium waste water combined with P 204 , loaded magnesium ions organic phase back extracted by using hydrochloric acid, washed into blank organic phase and magnesium chloride solution, blank organic phase recycled;

[0039] P 204 Mixed with kerosene as extractant, extractant saponified with ammonia water.

[0040] Reaction formula as follows: Mg 2+ +2(HA)2→Mg(HA2)2+2H+

[0041] Mg(HA2)2+ 2HCl → MgCl2+ (HA)2

[0042] Process conditions:

[0043] P 204 Concentration = 1-1.8 mol / l;

[0044] Degree of saponification = 0.5-0.8 (saponification rate = 33%-53%);

[0045] Phase ratio (wastewater: organic phase) = 1-2:1;

[0046] Hydrochloric acid concentration = 2-8 mol / l.

[0047] Step 3: low calcium, magnesium wastewater is discharged from the extraction equipment, and the calcium chloride solution and the magnesium chloride solution are introduced into the extraction equipment for subsequent use.

[0048] Example 1: Ammonium sulfate wastewater is used as the treatment object, and two-step extraction is performed to remove calcium ions and magnesium ions in the ammonium sulfate wastewater.

[0049] (1) Component analysis of ammonium sulfate wastewater:

[0050] analytical elements MgO CaO pH content (g / l) 6.75 0.74 2.3

[0051] (2) The organic phase (P 204 and kerosene) is subjected to an extraction reaction with ammonium sulfate wastewater, the P 204 concentration is controlled to be 1.5 mol / L, the phase ratio (wastewater: organic phase) is controlled to be 10:1, a low-calcium ammonium sulfate solution and a calcium-loaded organic phase are generated, the low-calcium ammonium sulfate solution is discharged from the extraction equipment, and the calcium-loaded organic phase is subjected to back extraction and washing with 6N hydrochloric acid to generate a blank organic phase for recycling and a calcium chloride solution. After the first step of extraction, the calcium content in the wastewater is 0.01 g / l, and the magnesium content is 6.02 g / l.

[0052] (3) The low-calcium ammonium sulfate solution is subjected to the next step of extraction, the organic phase is subjected to saponification with ammonia water, the P 204 concentration is also controlled to be 1.5 mol / L, the degree of saponification is 0.54, the saponified organic phase is reacted with wastewater, the phase ratio (wastewater: organic phase) is controlled to be 1:1, a low-impurity-content ammonium sulfate solution and a magnesium ion-loaded organic phase are generated, the ammonium sulfate solution is discharged from the extraction equipment, and the magnesium-loaded organic phase is subjected to back extraction and washing with 6N hydrochloric acid to generate a blank organic phase for recycling. After the second step of extraction, the calcium content in the wastewater is <0.01 g / l, and the magnesium content is 0.02 g / l. The magnesium content in the magnesium chloride solution is 43.17 g / l.

[0053] Example 2: Ammonium chloride wastewater as the treatment object, through the extraction method to remove calcium ions in the ammonium chloride wastewater.

[0054] (1), ammonium chloride wastewater composition analysis:

[0055]

[0056]

[0057] (2), organic phase (P 204 And kerosene) and ammonium chloride wastewater extraction reaction, control P 204 Concentration of 1.5mol / L, phase ratio (wastewater: organic phase) is 10:1, the generation of impurities containing less ammonium chloride solution and calcium loaded organic phase, ammonium chloride solution discharge extraction equipment, calcium loaded organic phase by 6N hydrochloric acid back extraction, washing, to generate can be recycled blank organic phase and calcium chloride solution.

[0058] (3), ammonium chloride wastewater composition analysis after treatment:

[0059] analytical elements MgO CaO content (g / l) ＜0.01 ＜0.01

[0060] Calcium content of calcium chloride solution is 15g / l.

[0061] Example 3: Magnesium sulfate wastewater as the treatment object, through the extraction method to remove calcium ions in the magnesium sulfate wastewater.

[0062] (1), CaO content in magnesium sulfate wastewater is 1.26g / l.

[0063] (2), organic phase (P 204 And kerosene) and magnesium sulfate wastewater extraction reaction, control P 204 Concentration of 1.5mol / L, phase ratio (wastewater: organic phase) is 5:1, the generation of impurities containing less magnesium sulfate solution and calcium loaded organic phase, magnesium sulfate solution discharge extraction equipment, calcium loaded organic phase by 6N hydrochloric acid back extraction, washing, to generate can be recycled blank organic phase and calcium chloride solution.

[0064] (3), CaO content in magnesium sulfate wastewater after treatment is 0.03g / l. Calcium content of calcium chloride solution is 50g / l.

[0065] The terms used in the present application are illustrative and exemplary, but not limiting terms. Since the present application can be embodied in various forms without departing from the spirit or essential characteristics of the technical solution, it should be understood that the above examples are not limited to any of the foregoing details, but should be interpreted broadly within the spirit and scope of the appended claims, therefore all changes and modifications falling within the scope of the claims or their equivalents should be covered by the appended claims.

Claims

1. A method for removing calcium and magnesium from rare earth industry wastewater by P204, characterized in that, The application relates to a method for removing calcium ions and magnesium ions in wastewater. The method comprises the following steps: using P204 mixed with kerosene as an extractant, performing single-stage extraction on the extractant and wastewater to remove calcium ions, in the process of removing the calcium ions in the wastewater, the concentration of the P204 is 1-1.8 mol / L, the calcium ions in the wastewater are combined with the P204, the calcium ions in the wastewater are removed, low-calcium wastewater is discharged from the extraction equipment, the organic phase loaded with the calcium ions is subjected to multi-stage stripping with hydrochloric acid, and the organic phase is washed to become a blank organic phase and a calcium chloride solution, the phase ratio of the wastewater to the organic phase is 1-10:1, and the concentration of the hydrochloric acid is 2-8 mol / L; The method comprises the following steps: using P204 mixed with kerosene as an extractant, performing single-stage extraction on the extractant and wastewater to remove calcium ions, in the process of removing the calcium ions in the wastewater, the concentration of the P204 is 1-1.8 mol / L, the calcium ions in the wastewater are combined with the P204, the calcium ions in the wastewater are removed, low-calcium wastewater is discharged from the extraction equipment, the organic phase loaded with the calcium ions is subjected to multi-stage stripping with hydrochloric acid, and the organic phase is washed to become a blank organic phase and a calcium chloride solution, the phase ratio of the wastewater to the organic phase is 1-10:1, and the concentration of the hydrochloric acid is 2-8 mol / L;

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