A method for purifying the mother liquor from high-calcium, magnesium, and rare earth smelting MVR

Abstract

This invention discloses a purification method for MVR mother liquor from high-calcium and magnesium rare earth smelting, belonging to the field of wastewater treatment technology in mineral processing and rare earth smelting. Addressing the problem that existing strong alkali and high-temperature treatment processes easily cause ammonium chloride in the mother liquor to decompose and release ammonia gas, failing to effectively purify the rare earth smelting MVR mother liquor, this invention employs a stepwise precipitation process to treat the mother liquor. First, ammonia water is used to adjust the pH of the mother liquor; then, a calcium and magnesium softening agent is added to complete the initial removal of calcium and magnesium; subsequently, a zinc precipitation composite agent is added to deeply remove heavy metal impurities such as zinc and lead; finally, ammonium bicarbonate is added for further deep magnesium removal. The purified MVR mother liquor is obtained through multi-step solid-liquid separation. Utilizing the low solubility product of calcium fluoride, magnesium fluoride, zinc sulfide, and calcium carbonate, efficient impurity separation is achieved. The process is simple, with low reagent consumption and low operating costs. The reaction conditions are mild with no ammonia gas emission, effectively solving the industry problem of impurity enrichment affecting the crystallization quality of ammonium chloride. This method is suitable for treating MVR mother liquor with different component concentrations.

Description

Technical Field

[0001] This invention relates to the field of mineral processing technology, specifically to a method for purifying the mother liquor of high-calcium magnesium rare earth smelting MVR. Background Technology

[0002] High-concentration ammonium chloride wastewater is generated during the ion-adsorption rare earth smelting process in southern China. This wastewater is typically pretreated and then subjected to MVR evaporation and crystallization to recover industrial ammonium chloride salt. However, this process also produces an MVR mother liquor containing high concentrations of calcium and magnesium ions. The recirculation of this mother liquor to the upstream process increases the overall concentration of calcium, magnesium, and heavy metal ions in the wastewater before evaporation, severely impacting the crystallization quality of ammonium chloride. Therefore, there is an urgent need to develop a purification method for the MVR mother liquor from high-calcium and magnesium rare earth smelting.

[0003] Numerous methods exist for softening water and removing heavy metals from it. For example, calcium oxide is used to soften wastewater, and high-temperature heating is used to remove magnesium ions from boiler water. However, these methods rely on highly alkaline and high-temperature solutions, making them unsuitable for rare earth smelting MVR mother liquor. This wastewater contains large amounts of ammonium chloride, which generates ammonia gas in a highly alkaline environment, posing a threat to the environment. Therefore, conventional technologies struggle to purify high-calcium, high-magnesium rare earth smelting MVR mother liquor. Developing a method capable of precisely separating calcium and magnesium impurities to effectively purify rare earth smelting MVR mother liquor has become a significant technological challenge in this field. This invention is proposed based on this practical need. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide a simple and low-cost method for purifying the mother liquor of high-calcium magnesium rare earth smelting MVR. This method can accurately and efficiently separate calcium, magnesium and heavy metal impurities in the mother liquor through stepwise precipitation, thereby realizing the recycling of the mother liquor and solving the industry problem of impurity accumulation in the system.

[0005] To address the aforementioned technical problems, this invention provides a method for purifying the mother liquor from high-calcium, magnesium, and rare earth smelting MVR (Medium-Volume Resin Transmission) processes, comprising the following steps: S1. pH Adjustment: Use a pH adjuster to adjust the pH of the mother liquor from high-calcium magnesium rare earth smelting MVR to 7.0-8.0; S2. Mother liquor softening: Add calcium and magnesium softening agent according to the calcium and magnesium ion content in the MVR mother liquor of high calcium and magnesium rare earth smelting, stir for 30 min, let stand for 1 h, and then separate solid and liquid to obtain filtrate I and calcium and magnesium softening residue. S3. Deep De-gravity Removal: Add zinc precipitation compound agent according to the zinc ion content in filtrate I, stir for 30 min, let stand for 1 h, and then separate solid and liquid to obtain filtrate II and de-gravity residue. S4. Deep softening: Add ammonium bicarbonate according to the calcium and magnesium ions in filtrate II, stir for 30 minutes, let stand for 1 hour, and then separate the solid and liquid to obtain filtrate III and deep softening residue. Filtrate III is the purified MVR mother liquor.

[0006] In some embodiments of the present invention, in step S1, the pH adjuster is ammonia.

[0007] As some embodiments of the present invention, in step S1, the calcium ion concentration of the high-calcium-magnesium rare earth smelting MVR mother liquor ranges from 6 to 13 g / L, the magnesium ion concentration ranges from 8 to 16 g / L, and the ammonium chloride concentration ranges from 3 to 5 mol / L.

[0008] As some embodiments of the present invention, in step S2, the calcium magnesium softener is a composite agent of fluoride inorganic salt and ammonium bicarbonate, wherein the weight percentage of fluoride inorganic salt in the composite agent is 90% and the weight percentage of ammonium bicarbonate is 10%, and the amount of composite agent added is 50-80 g / L.

[0009] In some embodiments of the present invention, the reaction temperature in step S2 is 60–90°C.

[0010] As some embodiments of the present invention, in step S3, the zinc precipitation composite agent is TMT102 (the main component is trithiotriazine trisodium salt), which is added according to the concentration of zinc, and the mass concentration ratio of zinc to TMT102 is 30~50.

[0011] As some embodiments of the present invention, in step S4, the amount of ammonium bicarbonate added is 20-30 g / L.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: This invention relies on the low solubility product of calcium fluoride, magnesium fluoride, zinc sulfide, and calcium carbonate, and uses a stepwise precipitation method to remove impurity ions such as calcium, magnesium, zinc, and lead from the mother liquor in sequence. It has strong targeting for impurity removal, can be adapted to high calcium and magnesium rare earth smelting MVR mother liquor with different components and different ion concentrations, and has wide applicability.

[0013] The entire process flow is simple in design, and the precipitates generated in each reaction step have excellent settling properties, making solid-liquid separation very easy to achieve without the need for complex specialized equipment. The process operating conditions are mild, the operating parameters are easy to control, and the on-site operation is simple, facilitating industrial-scale implementation and continuous production. At the same time, this invention requires less reagent dosage and consumes fewer raw and auxiliary materials, significantly reducing the overall cost of mother liquor treatment.

[0014] Unlike traditional calcium oxide softening and high-temperature magnesium removal processes, this method requires no strongly alkaline or extremely high-temperature environment throughout the entire process. This effectively prevents the decomposition of high-concentration ammonium chloride in the mother liquor, thus avoiding the release of ammonia and eliminating secondary air pollution, resulting in higher environmental safety. The MVR mother liquor purified by this process achieves a removal rate of approximately 99% for calcium, magnesium, and heavy metal ions, demonstrating excellent purification performance. The purified mother liquor can be reused in the upstream processes of rare earth smelting, fundamentally solving the industry problem of continuous impurity accumulation affecting the crystallization quality of ammonium chloride, and effectively improving the operational stability and resource utilization rate of the entire smelting system. Attached Figure Description

[0015] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 A schematic diagram of the process flow of an embodiment of the present invention. Detailed Implementation

[0017] To make the technical means, creative features, objectives and effects of this invention easier to understand, the technical solutions in the specific embodiments of this invention are described clearly and completely below to further illustrate this invention. Obviously, the specific embodiments described are only a part of the embodiments of this invention, and not all of them.

[0018] Example 1: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentrations of calcium ions in the mother liquor are 8.17 g / L, magnesium ions 13.04 g / L, zinc ions 1.74 g / L, and lead ions 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 7.0 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 17.7g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor of high calcium magnesium rare earth smelting MVR. Keep the temperature at 60℃ and stir for 30min. After standing for 1h, separate the solid and liquid to obtain filtrate I and calcium magnesium softening slag. The obtained filtrate I is transferred to the subsequent processing. S3. Deep deweighting: Under stirring, add 40g of TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate II and deweighting residue. The obtained filtrate II is transferred to the subsequent processing. S4. Deep softening: Under stirring, add 10.5g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h, and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0019] The formula for calculating the removal rate is as follows:

[0020] In the formula: Y Indicates the removal rate; C 1 indicates the concentration before adding the drug; V 1 indicates the volume before adding the medicine; C 2 indicates the concentration after adding the drug; V 2 indicates the volume after adding the drug.

[0021] Example 2: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentrations of calcium ions in the mother liquor are 8.17 g / L, magnesium ions 13.04 g / L, zinc ions 1.74 g / L, and lead ions 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 7.5 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 22.1g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor, maintain the temperature at 80℃ and stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate I and calcium magnesium softening residue. The obtained filtrate I is transferred to the subsequent processing process. S3. Deep De-gravity Removal: Under stirring, add 40g of zinc precipitation composite agent TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate solid and liquid to obtain filtrate II and de-gravity residue. The obtained filtrate II is transferred to the subsequent treatment process. S4. Deep softening: Under stirring, add 6.75g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h, and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0022] Example 3: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentrations of calcium ions in the mother liquor are 8.17 g / L, magnesium ions 13.04 g / L, zinc ions 1.74 g / L, and lead ions 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 7.3 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 26.6g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor, maintain the temperature at 80℃ and stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate I and calcium magnesium softening residue. The obtained filtrate I is transferred to the subsequent processing process. S3. Deep De-gravity Removal: Under stirring, add 40g of zinc precipitation composite agent TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate solid and liquid to obtain filtrate II and de-gravity residue. The obtained filtrate II is transferred to the subsequent treatment process. S4. Deep softening: Under stirring, add 6.75g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h, and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0023] Example 4: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentrations of calcium ions in the mother liquor are 8.17 g / L, magnesium ions 13.04 g / L, zinc ions 1.74 g / L, and lead ions 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 7.0 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 24.4g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor, maintain the temperature at 90℃ and stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate I and calcium magnesium softening residue. The obtained filtrate I is transferred to the subsequent processing process. S3. Deep De-gravity Removal: Under stirring, add 40g of zinc precipitation composite agent TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate solid and liquid to obtain filtrate II and de-gravity residue. The obtained filtrate II is transferred to the subsequent treatment process. S4. Deep softening: Under stirring, add 10.5g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h, and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0024] Example 5: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentration of calcium ions in the mother liquor is 8.17 g / L, magnesium ions is 13.04 g / L, zinc ions is 1.74 g / L, and lead ions is 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 8.0 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 19.9g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor, maintain the temperature at 80℃ and stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate I and calcium magnesium softening residue. The obtained filtrate I is transferred to the subsequent processing process. S3. Deep De-gravity Removal: Under stirring, add 32g of zinc precipitation composite agent TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate solid and liquid to obtain filtrate II and de-gravity residue. The obtained filtrate II is transferred to the subsequent treatment process. S4. Deep softening: Under stirring, add 7.8g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h, and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0025] Example 6: This example uses a purification method for high-calcium-magnesium rare earth smelting MVR mother liquor to treat the mother liquor from a hydrometallurgical plant processing ion-adsorption rare earth ore. The concentrations of calcium ions in the mother liquor are 8.17 g / L, magnesium ions 13.04 g / L, zinc ions 1.74 g / L, and lead ions 11.55 mg / L. Figure 1 As shown, the purification method for the mother liquor from the high-calcium-magnesium rare earth smelting MVR process includes the following steps: S1. pH adjustment: Take 300ml of high calcium magnesium rare earth smelting MVR mother liquor, and adjust the pH of the high calcium magnesium rare earth smelting MVR mother liquor to 7.5 with ammonia water while stirring. S2. Mother liquor softening: Under stirring, add 17.7g of a composite agent of fluoride inorganic salt and ammonium bicarbonate with a weight ratio of 9:1 to the mother liquor, maintain the temperature at 80℃ and stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate I and calcium magnesium softening residue. The obtained filtrate I is transferred to the subsequent processing. S3. Deep De-gravity Removal: Under stirring, add 30g of zinc precipitation composite agent TMT102 to filtrate I, stir for 30min, let stand for 1h and then separate solid and liquid to obtain filtrate II and de-gravity residue. The obtained filtrate II is transferred to the subsequent treatment process. S4. Deep softening: Under stirring, add 10.3g of ammonium bicarbonate to filtrate II, stir for 30min, let stand for 1h and then separate the solid and liquid to obtain filtrate III and deep softening slag (magnesium carbonate slag). The obtained filtrate III is the purified MVR mother liquor, which is recycled back to the front-end process.

[0026] Table 1 Detection results of each embodiment

[0027] As can be seen from the results of the various embodiments in Table 1, the present invention can effectively purify the mother liquor of high-calcium, magnesium, and rare earth smelting MVR. In the above embodiments, the maximum removal rate of calcium ions was 99.82%, the maximum removal rate of magnesium ions was 99.97%, the maximum removal rate of zinc ions was 99.99%, and the maximum removal rate of lead ions was 99.64%. Therefore, the present invention can effectively purify the mother liquor of high-calcium, magnesium, and rare earth smelting MVR.

[0028] The main technical features, basic principles, and related advantages of the present invention have been described above. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the concept or basic characteristics of the invention. Therefore, the above-described embodiments should be considered exemplary and non-limiting in all respects. The scope of the present invention is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of the equivalents of the claims are intended to be included within the present invention.

[0029] Furthermore, it should be understood that although this specification describes various embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for purifying the mother liquor from high-calcium, magnesium, and rare earth smelting MVR (Medium-Volume Resin Transmission) process, characterized in that, Includes the following steps: S1. pH Adjustment: Use a pH adjuster to adjust the pH of the mother liquor from high-calcium magnesium rare earth smelting MVR to 7.0-8.0; S2. Mother liquor softening: Add calcium and magnesium softening agent according to the calcium and magnesium ion content in the MVR mother liquor of high calcium and magnesium rare earth smelting, stir for 30 min, let stand for 1 h, and then separate solid and liquid to obtain filtrate I and calcium and magnesium softening residue. S3. Deep De-gravity Removal: Add zinc precipitation compound agent according to the zinc ion content in filtrate I, stir for 30 min, let stand for 1 h, and then separate solid and liquid to obtain filtrate II and de-gravity residue. S4. Deep softening: Add ammonium bicarbonate according to the calcium and magnesium ions in filtrate II, stir for 30 minutes, let stand for 1 hour, and then separate the solid and liquid to obtain filtrate III and deep softening residue. Filtrate III is the purified MVR mother liquor.

2. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S1, the pH adjuster is ammonia.

3. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S1, the calcium ion concentration range of the high-calcium-magnesium rare earth smelting MVR mother liquor is 6–13 g / L, the magnesium ion concentration range is 8–16 g / L, and the ammonium chloride concentration is 3–5 mol / L.

4. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S2, the calcium-magnesium softener is a composite agent of fluoride inorganic salt and ammonium bicarbonate. The weight percentage of the fluoride inorganic salt in the composite agent is 90%, and the weight percentage of the ammonium bicarbonate is 10%. The amount of the composite agent added is 50-80 g / L.

5. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S2, the reaction temperature is 60–90°C.

6. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S3, the zinc precipitation compound agent is TMT-102, which is added according to the zinc concentration, with a zinc to TMT102 mass concentration ratio of 40~50.

7. The purification method for MVR mother liquor in high-calcium magnesium rare earth smelting according to claim 1, characterized in that, In step S4, the amount of ammonium bicarbonate added is 20–30 g / L.

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