Extraction and impurity removal method for MHP pickle liquor
By employing a synergistic extraction strategy for impurities calcium and scandium, the problems of calcium crystal blockage and emulsification in the P204 extraction impurity removal process were solved, achieving efficient and stable MHP acid leaching for impurity removal, optimizing process steps and reducing costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-23
- Publication Date
- 2026-03-13
AI Technical Summary
In the existing P204 extraction and impurity removal process, calcium ions are prone to crystallization, leading to blockage, and scandium ions form hydrophobic complexes with the extractant, causing emulsification, which affects the stability and efficiency of the production line and makes it difficult to meet industrial requirements.
A synergistic extraction strategy for impurities calcium and scandium is adopted. Through steps such as pH adjustment, saponification treatment, countercurrent extraction, acid washing and back extraction, the concentration of calcium and scandium in MHP leachate is reduced, emulsification is avoided, and extraction efficiency and production line stability are improved.
It effectively reduces the risk of calcium crystal blockage, avoids emulsification caused by scandium enrichment, improves the extraction efficiency of the P204 system, simplifies the operation process, and reduces energy consumption and operating costs.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of hydrometallurgical technology, specifically relating to an extraction and impurity removal method for MHP acid leaching solution. Background Technology
[0002] With the large-scale development and utilization of nickel resources, the smelting process using nickel cobalt hydroxide (MHP) as raw material is becoming increasingly important. However, MHP often contains various impurity elements such as manganese, copper, calcium, and scandium, which seriously affect the quality and performance of the final nickel product and must be effectively removed.
[0003] In existing P204 extraction and impurity removal processes, calcium ions easily form scale in the extraction tank and pipelines, affecting the stable operation of the production line. The resulting calcium slag also carries a large amount of aqueous phase, leading to the loss of valuable metals. Simultaneously, the scandium ion-P204 complex Sc(HA2)3 is highly hydrophobic, easily inducing the formation of a third phase (three-phase slag), making extraction and phase separation difficult. These factors combined result in the existing P204 extraction and impurity removal process being inefficient, cumbersome to operate, and costly, making it difficult to meet the needs of industrial applications.
[0004] Therefore, how to remove calcium and scandium simultaneously and efficiently to improve the stability of the subsequent P204 extraction and impurity removal process is a technical problem that urgently needs to be solved. Summary of the Invention
[0005] To address the shortcomings of existing technologies, the present invention aims to provide an extraction and impurity removal method for MHP acid leaching solutions. This invention introduces a synergistic extraction strategy for impurities calcium and scandium, which not only reduces the Ca concentration in the MHP leachate to below 1 mg / L and the Sc concentration to below 0.1 mg / L, effectively lowering the risk of blockage caused by calcium crystallization in the subsequent P2O4 extraction and impurity removal stage, but also avoids emulsification caused by Sc enrichment in the organic phase. This significantly improves the extraction efficiency of the P2O4 system, ensuring stable and continuous operation of the production line. Furthermore, this strategy simplifies the operation process, optimizes the process steps, reduces energy consumption, and significantly saves operating costs.
[0006] To achieve this objective, the present invention adopts the following technical solution:
[0007] This invention provides an extraction and impurity removal method for MHP acid leaching solution, the extraction and impurity removal method comprising the following steps:
[0008] The pH of the MHP acid leaching solution was adjusted to obtain the pretreated MHP acid leaching solution.
[0009] The organic phase containing the extractant is saponified to obtain the saponified organic phase.
[0010] The saponified organic phase was subjected to countercurrent extraction of the pretreated MHP acid leaching solution to obtain a raffinate and a supported organic phase. The supported organic phase contained calcium ions and scandium ions.
[0011] The supported organic phase is acid-washed to obtain a nickel-cobalt washing solution and a washed organic phase. The washed organic phase is then back-extracted for calcium to obtain a first back-extraction solution and a back-extracted organic phase. The back-extracted organic phase is then back-extracted for scandium to obtain a second back-extraction solution and a regenerated organic phase.
[0012] This invention introduces a synergistic extraction strategy for impurities calcium and scandium, which not only reduces the Ca concentration in the MHP leachate to below 1 mg / L and the Sc concentration to below 0.1 mg / L, effectively reducing the risk of blockage caused by calcium crystallization in the subsequent P204 extraction and impurity removal stage, but also avoids emulsification caused by Sc enrichment in the organic phase. This significantly improves the extraction efficiency of the P204 system, ensuring the stable and continuous operation of the production line. Furthermore, this strategy simplifies the operation process, optimizes the process steps, reduces energy consumption, and significantly saves operating costs.
[0013] In this invention, the purpose of acid washing is to recover the residual valuable metals nickel and cobalt in the supported organic phase into the nickel-cobalt washing solution (i.e., the aqueous phase). On the one hand, this prevents them from entering the subsequent calcium and scandium back-extraction steps with the supported organic phase, thus contaminating the calcium and scandium back-extraction products. On the other hand, it achieves deep recovery of nickel and cobalt, reduces the loss of valuable metals, and improves the resource utilization efficiency and economy of the process.
[0014] Preferably, the concentration of calcium ions in the MHP acid leaching solution is 800-900 mg / L, for example, 800 mg / L, 820 mg / L, 840 mg / L, 860 mg / L, 880 mg / L, or 900 mg / L, and the concentration of scandium ions is 5-15 mg / L, for example, 5 mg / L, 7.5 mg / L, 10 mg / L, 12.5 mg / L, or 15 mg / L.
[0015] Preferably, the pH of the pretreated MHP acid leaching solution is 2.5-3.5, for example, it can be 2.5, 2.6, 2.7, 2.8, 2.9, 3, 3.1, 3.2, 3.3, 3.4 or 3.5, etc.
[0016] The present invention adjusts the pH of the MHP acid leaching solution to 2.5-3.5 in order to optimize the selectivity of the extractant, improve the ability to extract calcium, and reduce co-extraction of cobalt and nickel.
[0017] Preferably, the organic phase containing the extractant includes both the extractant and the diluent.
[0018] Preferably, the extractant includes Deyuancui Ca extractant. It should be noted that the acid value of Deyuancui Ca extractant is 2.5, and when diluted 15%, the calcium loading is 2 g / L.
[0019] Preferably, the diluent comprises sulfonated kerosene.
[0020] Preferably, the mass ratio of the extractant to the diluent is 1:(0.8-1.2), for example, it can be 1:0.8, 1:0.9, 1:1, 1:1.1 or 1:1.2, etc.
[0021] Preferably, the saponification value of the saponified organic phase is 0.15-0.3, for example, it can be 0.15, 0.2, 0.25 or 0.3, etc.
[0022] In this invention, a saponified organic phase with a suitable saponification value is beneficial for increasing the extraction loading and reaction rate.
[0023] Preferably, the saponification step includes:
[0024] The organic phase containing the extractant is reacted with an alkali to undergo saponification.
[0025] Preferably, the alkali includes liquid alkali.
[0026] Preferably, the countercurrent extraction has 7-9 stages, for example, 7, 8 or 9 stages.
[0027] In this invention, the number of countercurrent extraction stages is limited to 7-9 stages. Under this number of stages, the extraction of cobalt and nickel is minimized, and the concentration of calcium ions in the raffinate is controlled to be less than 1 mg / L and the concentration of scandium ions to be less than 0.1 mg / L.
[0028] Preferably, during the countercurrent extraction process, the flow rate of the pretreated MHP acid leaching solution is 1380-2280 mL / h, for example, it can be 1380 mL / h, 1400 mL / h, 1500 mL / h, 1600 mL / h, 1700 mL / h, 1800 mL / h, 1900 mL / h, 2000 mL / h, 2100 mL / h, 2200 mL / h, or 2280 mL / h, etc., and the flow rate of the saponified organic phase is 360-720 mL / h, for example, it can be 360 mL / h, 400 mL / h, 500 mL / h, 600 mL / h, 700 mL / h, or 720 mL / h, etc.
[0029] Preferably, the pickling solution used in the pickling process includes dilute sulfuric acid, the concentration of which is 0.25-1N, for example, 0.25N, 0.5N, 0.75N, or 1N. It should be noted that the unit "N" is used to express the "effective particle concentration participating in the reaction" in the solution, reflecting the actual reactivity of a substance in a chemical reaction, rather than simply the total concentration of the substance, i.e., the concentration of hydrogen ions. The same applies below.
[0030] Preferably, the number of extraction stages in the pickling extraction line is 2-5 stages, for example, it can be 2, 3, 4 or 5 stages. It should be noted that "the number of extraction stages in the pickling extraction line is 2-5 stages" means that the multi-stage countercurrent extraction process used for pickling is composed of 2 to 5 extraction stages connected in series.
[0031] Preferably, the flow rate of the dilute sulfuric acid is 180-600 mL / h, for example, it can be 180 mL / h, 200 mL / h, 300 mL / h, 400 mL / h, 500 mL / h or 600 mL / h.
[0032] Preferably, in the process of calcium back-extraction, the back-extraction agent used includes dilute hydrochloric acid, and the concentration of the dilute hydrochloric acid is 2-5N, for example, it can be 2N, 3N, 4N or 5N, etc.
[0033] This invention uses dilute hydrochloric acid with a concentration of 2-5N for calcium back-extraction. This not only breaks the coordination bond between calcium ions and the extractant (such as Deyuan Extract Ca extractant) through competitive displacement of hydrogen ions, achieving efficient desorption of calcium ions, but also prevents scandium ions from entering the back-extraction solution along with calcium ions because the acidity is not high enough to destroy the strong chelation between scandium ions and the extractant. This ensures the purity and recovery rate of subsequent scandium enrichment.
[0034] Preferably, the number of back-extraction stages for the back-extracted calcium is 5-7, for example, it can be 5, 6 or 7 stages.
[0035] Preferably, the flow rate of the dilute hydrochloric acid is 100-240 mL / h, for example, it can be 100 mL / h, 150 mL / h, 200 mL / h or 240 mL / h.
[0036] Preferably, in the scandium back-extraction process, the back-extraction agent used includes sulfuric acid, and the concentration of the sulfuric acid is 3-5N, for example, it can be 3N, 3.5N, 4N, 4.5N or 5N, etc.
[0037] This invention uses sulfuric acid with a concentration of 3-5N for scandium back-extraction, which can provide a high concentration of hydrogen ions. Through competitive displacement, the complex structure is strongly destroyed, and scandium ions are completely transferred from the organic phase to the aqueous phase. Deep scandium removal can be achieved with only 1-2 back-extraction stages.
[0038] Preferably, the scandium back-extraction stage is 1-2 stages, for example, it can be 1 stage or 2 stages.
[0039] Preferably, the flow rate of the sulfuric acid is 100-240 mL / h, for example, it can be 100 mL / h, 150 mL / h, 200 mL / h or 240 mL / h.
[0040] Preferably, the concentration of calcium ions in the raffinate is <1 mg / L, for example, it can be 0.8 mg / L, 0.6 mg / L, 0.4 mg / L or 0.2 mg / L.
[0041] Preferably, the concentration of scandium ions in the raffinate is <0.1 mg / L, for example, it can be 0.08 mg / L, 0.06 mg / L, 0.04 mg / L or 0.02 mg / L, etc.
[0042] Preferably, the extraction and impurity removal method includes the following steps:
[0043] (1) Provide MHP leaching solution; wherein the concentration of nickel ions in the MHP leaching solution is 90-100 g / L (e.g., 90 g / L, 92 g / L, 94 g / L, 96 g / L, 98 g / L or 100 g / L, etc.), the concentration of cobalt ions is 7-7.6 g / L (e.g., 7 g / L, 7.1 g / L, 7.2 g / L, 7.3 g / L, 7.4 g / L, 7.5 g / L or 7.6 g / L, etc.), the concentration of calcium ions is 800-900 mg / L, and the concentration of scandium ions is 5-15 mg / L; wherein the MHP leaching solution contains sulfate anions.
[0044] The pH of the MHP acid leaching solution was adjusted to obtain a pretreated MHP acid leaching solution with a pH of 2.5-3.5.
[0045] An organic phase containing an extractant is reacted with an alkali and saponified to obtain a saponified organic phase with a saponification value of 0.15-0.3; the organic phase containing the extractant includes an extractant and a diluent, the extractant includes Deyuancui Ca extractant, and the diluent includes sulfonated kerosene; the mass ratio of the extractant to the diluent is 1:(0.8-1.2); wherein, the alkali includes liquid alkali.
[0046] (2) The saponified organic phase is used to perform countercurrent extraction on the pretreated MHP acid leaching solution to obtain raffinate and supported organic phase; the supported organic phase contains calcium ions and scandium ions.
[0047] The countercurrent extraction stage is 7-9 stages; the flow rate of the pretreated MHP acid leaching solution is 1380-2280 mL / h, and the flow rate of the saponified organic phase is 360-720 mL / h; the concentration of calcium ions in the raffinate is <1 mg / L, and the concentration of scandium ions is <0.1 mg / L.
[0048] The raffinate is subjected to precipitation treatment (for example, sodium sulfide or other precipitating agents can be used) to obtain nickel-cobalt precipitate.
[0049] (3) The loaded organic phase is acid-washed with dilute sulfuric acid with a concentration of 0.25-1N and a flow rate of 180-600mL / h. The extraction stage of the acid washing extraction line is 2-5 stages to obtain nickel-cobalt washing solution and washed organic phase.
[0050] (4) Use dilute hydrochloric acid with a concentration of 2-5N and a flow rate of 100-240mL / h to back-extract calcium from the washed organic phase. The back-extraction stage is 5-7 stages to obtain the first back-extraction solution and the back-extracted organic phase.
[0051] The first back-extraction solution was concentrated and crystallized to recover calcium salts.
[0052] (5) The organic phase after back-extraction is back-extracted with sulfuric acid at a concentration of 3-5N and a flow rate of 100-240mL / h. The back-extraction stage is 1-2 stages to obtain a second back-extraction solution and a regenerated organic phase. The regenerated organic phase is reused in the organic phase containing the extractant in step (1).
[0053] The second back-extraction solution was subjected to precipitation, filtration, and calcination to recover scandium oxide.
[0054] The numerical range described in this invention includes not only the point values listed above, but also any point values within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values included in the range.
[0055] Compared with the prior art, the present invention has the following beneficial effects:
[0056] This invention introduces a synergistic extraction strategy for impurities calcium and scandium, which not only reduces the Ca concentration in the MHP leachate to below 1 mg / L and the Sc concentration to below 0.1 mg / L, effectively reducing the risk of blockage caused by calcium crystallization in the subsequent P204 extraction and impurity removal stage, but also avoids emulsification caused by Sc enrichment in the organic phase. This significantly improves the extraction efficiency of the P204 system, ensuring the stable and continuous operation of the production line. Furthermore, this strategy simplifies the operation process, optimizes the process steps, reduces energy consumption, and significantly saves operating costs. Detailed Implementation
[0057] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.
[0058] Example 1
[0059] This embodiment provides an extraction and impurity removal method for MHP acid leaching solution, which includes the following steps:
[0060] (1) Provide MHP acid leaching solution; wherein the concentration of nickel ions in the MHP acid leaching solution is 90 g / L, the concentration of cobalt ions is 7.2 g / L, the concentration of calcium ions is 850 mg / L, and the concentration of scandium ions is 10 mg / L; wherein the MHP acid leaching solution contains sulfate anions.
[0061] The pH of the MHP leaching solution was adjusted to obtain a pretreated MHP leaching solution with a pH of 3.
[0062] The organic phase containing the extractant is reacted with liquid alkali for saponification to obtain a saponified organic phase with a saponification value of 0.2; the organic phase containing the extractant includes an extractant and a diluent, the extractant is Deyuancui Ca extractant, and the diluent is sulfonated kerosene; the mass ratio of the extractant to the diluent is 1:1.
[0063] (2) The saponified organic phase is used to perform countercurrent extraction on the pretreated MHP acid leaching solution to obtain raffinate and supported organic phase; the supported organic phase contains calcium ions and scandium ions.
[0064] The countercurrent extraction process has eight stages; the flow rate of the pretreated MHP acid leaching solution is 1830 mL / h, and the flow rate of the saponified organic phase is 540 mL / h.
[0065] The raffinate was subjected to precipitation treatment to obtain nickel-cobalt precipitate.
[0066] (3) The loaded organic phase was acid-washed with dilute sulfuric acid with a concentration of 0.6N and a flow rate of 300mL / h. The acid washing was performed in three stages to obtain nickel-cobalt washing solution and washed organic phase.
[0067] (4) Use dilute hydrochloric acid with a concentration of 3.5N and a flow rate of 170mL / h to back-extract calcium from the washed organic phase. The back-extraction stage is 6 stages, to obtain the first back-extraction solution and the back-extracted organic phase.
[0068] The first back-extraction solution was concentrated and crystallized to recover calcium salts.
[0069] (5) The organic phase after back-extraction is back-extracted with sulfuric acid of 4N concentration and 170mL / h. The back-extraction stage is 1 stage, to obtain a second back-extraction solution and a regenerated organic phase. The regenerated organic phase is reused in the organic phase containing the extractant in step (1).
[0070] The second back-extraction solution was subjected to precipitation, filtration, and calcination to recover scandium oxide.
[0071] Example 2
[0072] This embodiment provides an extraction and impurity removal method for MHP acid leaching solution, which includes the following steps:
[0073] (1) Provide MHP acid leaching solution; wherein the concentration of nickel ions in the MHP acid leaching solution is 90 g / L, the concentration of cobalt ions is 7.2 g / L, the concentration of calcium ions is 850 mg / L, and the concentration of scandium ions is 10 mg / L; wherein the MHP acid leaching solution contains sulfate anions.
[0074] The pH of the MHP leaching solution was adjusted to obtain a pretreated MHP leaching solution with a pH of 2.5.
[0075] The organic phase containing the extractant is reacted with liquid alkali for saponification to obtain a saponified organic phase with a saponification value of 0.15. The organic phase containing the extractant includes an extractant and a diluent. The extractant is Deyuancui Ca extractant, and the diluent is sulfonated kerosene. The mass ratio of the extractant to the diluent is 1:0.8.
[0076] (2) The saponified organic phase is used to perform countercurrent extraction on the pretreated MHP acid leaching solution to obtain raffinate and supported organic phase; the supported organic phase contains calcium ions and scandium ions.
[0077] The countercurrent extraction process has 7 stages; the flow rate of the pretreated MHP acid leaching solution is 1380 mL / h, and the flow rate of the saponified organic phase is 360 mL / h.
[0078] The raffinate was subjected to precipitation treatment to obtain nickel-cobalt precipitate.
[0079] (3) The loaded organic phase was acid-washed with dilute sulfuric acid with a concentration of 0.25N and a flow rate of 180mL / h. The extraction line of the acid washing was of the second stage, and nickel-cobalt washing solution and washed organic phase were obtained.
[0080] (4) Use dilute hydrochloric acid with a concentration of 2N and a flow rate of 100mL / h to back-extract calcium from the washed organic phase. The back-extraction stage is 5 stages to obtain the first back-extraction solution and the back-extracted organic phase.
[0081] The first back-extraction solution was concentrated and crystallized to recover calcium salts.
[0082] (5) The organic phase after back-extraction is back-extracted with sulfuric acid of concentration 3N and flow rate of 100mL / h. The back-extraction stage is 1 stage, to obtain a second back-extraction solution and a regenerated organic phase. The regenerated organic phase is reused in the organic phase containing the extractant in step (1).
[0083] The second back-extraction solution was subjected to precipitation, filtration, and calcination to recover scandium oxide.
[0084] Example 3
[0085] This embodiment provides an extraction and impurity removal method for MHP acid leaching solution, which includes the following steps:
[0086] (1) Provide MHP acid leaching solution; wherein the concentration of nickel ions in the MHP acid leaching solution is 90 g / L, the concentration of cobalt ions is 7.2 g / L, the concentration of calcium ions is 850 mg / L, and the concentration of scandium ions is 10 mg / L; wherein the MHP acid leaching solution contains sulfate anions.
[0087] The pH of the MHP leaching solution was adjusted to obtain a pretreated MHP leaching solution with a pH of 3.5.
[0088] The organic phase containing the extractant is reacted with liquid alkali for saponification to obtain a saponified organic phase with a saponification value of 0.3. The organic phase containing the extractant includes an extractant and a diluent. The extractant is Deyuancui Ca extractant, and the diluent is sulfonated kerosene. The mass ratio of the extractant to the diluent is 1:1.2.
[0089] (2) The saponified organic phase is used to perform countercurrent extraction on the pretreated MHP acid leaching solution to obtain raffinate and supported organic phase; the supported organic phase contains calcium ions and scandium ions.
[0090] The countercurrent extraction process has nine stages; the flow rate of the pretreated MHP acid leaching solution is 2280 mL / h, and the flow rate of the saponified organic phase is 720 mL / h.
[0091] The raffinate was subjected to precipitation treatment to obtain nickel-cobalt precipitate.
[0092] (3) The loaded organic phase was acid-washed with dilute sulfuric acid with a concentration of 1N and a flow rate of 600 mL / h. The extraction line of the acid washing was 5 stages to obtain nickel-cobalt washing solution and washed organic phase.
[0093] (4) Use dilute hydrochloric acid with a concentration of 5N and a flow rate of 240mL / h to back-extract calcium from the washed organic phase. The back-extraction stage is 7 stages, to obtain the first back-extraction solution and the back-extracted organic phase.
[0094] The first back-extraction solution was concentrated and crystallized to recover calcium salts.
[0095] (5) The stripped organic phase is stripped with 5N sulfuric acid at a flow rate of 240 mL / h. The stripping stage is 2 stages to obtain a second stripping solution and a regenerated organic phase. The regenerated organic phase is reused in the organic phase containing the extractant in step (1).
[0096] The second back-extraction solution was subjected to precipitation, filtration, and calcination to recover scandium oxide.
[0097] Example 4
[0098] The difference between this embodiment and Embodiment 1 is that the saponification value of the saponified organic phase is 0.1.
[0099] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0100] Example 5
[0101] The difference between this embodiment and Embodiment 1 is that the saponification value of the saponified organic phase is 0.4.
[0102] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0103] Example 6
[0104] The difference between this embodiment and Embodiment 1 is that the countercurrent extraction has 6 stages.
[0105] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0106] Example 7
[0107] The difference between this embodiment and Embodiment 1 is that the countercurrent extraction has 10 stages.
[0108] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0109] Example 8
[0110] The difference between this embodiment and embodiment 1 is that the concentration of the dilute sulfuric acid in step (3) is 1.5N.
[0111] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0112] Example 9
[0113] The difference between this embodiment and embodiment 1 is that the concentration of the dilute hydrochloric acid in step (4) is 6N.
[0114] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0115] Example 10
[0116] The difference between this embodiment and embodiment 1 is that the sulfuric acid in step (5) is replaced with hydrochloric acid of the same concentration.
[0117] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0118] Comparative Example 1
[0119] The difference between this comparative example and Example 1 is that the saponification process in step (1) is not performed.
[0120] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0121] Comparative Example 2
[0122] The difference between this comparative example and Example 1 is that step (3) is omitted.
[0123] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0124] Comparative Example 3
[0125] The difference between this comparative example and Example 1 is that steps (4) and (5) are swapped.
[0126] The remaining extraction and impurity removal methods and parameters are consistent with those in Example 1.
[0127] Performance testing
[0128] The calcium and scandium ion contents of the raffinates provided in the above examples and comparative examples were detected by inductively coupled plasma optical emission spectrometry (ICP-OES).
[0129] Inductively coupled plasma optical emission spectrometry (ICP-OES) was used to detect the calcium and scandium ion contents of the first and second back-extraction solutions provided in the above examples and comparative examples, respectively. The corresponding recovery rates were obtained based on the calcium and scandium ion contents in the MHP acid leaching solution. Calcium ion recovery rate (%) = (calcium ion concentration in the first back-extraction solution × volume of the first back-extraction solution) / (initial calcium ion concentration in the MHP acid leaching solution × treatment volume of the MHP acid leaching solution) × 100%; Scandium ion recovery rate (%) = (scandium ion concentration in the second back-extraction solution × volume of the second back-extraction solution) / (initial scandium ion concentration in the MHP acid leaching solution × treatment volume of the MHP acid leaching solution) × 100%.
[0130] The test results are shown in Table 1.
[0131] Table 1
[0132]
[0133] analyze:
[0134] As shown in Table 1, the present invention introduces a synergistic extraction strategy for impurities calcium and scandium, which not only reduces the Ca concentration in the MHP leachate to below 1 mg / L and the Sc concentration to below 0.1 mg / L, effectively reducing the risk of blockage caused by calcium crystallization in the subsequent P204 extraction and impurity removal stage, but also avoids emulsification caused by the enrichment of Sc in the organic phase. This significantly improves the extraction efficiency of the P204 system, ensuring the stable and continuous operation of the production line. Moreover, this strategy simplifies the operation process, optimizes the process steps, reduces energy consumption, and significantly saves operating costs.
[0135] As can be seen from the comparison between Example 1 and Examples 4-5, if the saponification value of the saponified organic phase is too small, the saturation capacity is low and the concentration of loaded organometallic substances is low, resulting in excessively high concentrations of Ca and Sc in the raffinate; if the saponification value of the saponified organic phase is too large, it is easy to emulsify, and the extraction of other valuable metals increases the washing cost.
[0136] As can be seen from the comparison between Example 1 and Examples 6-7, if the number of countercurrent extraction stages is too small, the extraction rate will be low, resulting in excessive concentrations of Ca and Sc in the raffinate; if the number of countercurrent extraction stages is too large, the operating cost will increase, which may lead to problems such as emulsification and slow phase separation.
[0137] As can be seen from the comparison between Example 1 and Examples 8-9, if the concentration of dilute sulfuric acid in step (3) is too high, the extracted Ca will be washed off, generating calcium slag, which will make phase separation difficult; if the concentration of dilute hydrochloric acid in step (4) is too high, it will increase the cost and cause the extractant to degrade.
[0138] As can be seen from the comparison between Example 1 and Example 10, if the sulfuric acid in step (5) is replaced with hydrochloric acid of the same concentration, the Sc cannot be completely back-extracted.
[0139] As can be seen from the comparison between Example 1 and Comparative Example 1, if the saponification process in step (1) is not carried out, Ca and Sc cannot be effectively extracted.
[0140] As can be seen from the comparison between Example 1 and Comparative Example 2, if step (3) is not performed, the hydrochloric acid consumption is large during back-extraction, and the loss rate of valuable metals such as cobalt and nickel increases.
[0141] As can be seen from the comparison between Example 1 and Comparative Example 3, if the order of steps (4) and (5) is changed, the recovery rate of Ca and Sc will be significantly reduced.
[0142] It should be noted that the present invention is illustrated through the above embodiments, but the present invention is not limited to the above process steps, that is, it does not mean that the present invention must rely on the above process steps to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent substitutions of the raw materials used in the present invention, additions of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.
Claims
1. A method for extraction and impurity removal from MHP acid leaching solution, characterized in that, The extraction and impurity removal method includes the following steps: The pH of the MHP acid leaching solution was adjusted to obtain a pretreated MHP acid leaching solution. The organic phase containing the extractant is saponified to obtain a saponified organic phase; The saponified organic phase was subjected to countercurrent extraction of the pretreated MHP acid leaching solution to obtain a raffinate and a supported organic phase; the supported organic phase contained calcium ions and scandium ions; The supported organic phase is acid-washed to obtain a nickel-cobalt washing solution and a washed organic phase; the washed organic phase is back-extracted for calcium to obtain a first back-extraction solution and a back-extracted organic phase; the back-extracted organic phase is back-extracted for scandium to obtain a second back-extraction solution and a regenerated organic phase.
2. The extraction and impurity removal method according to claim 1, characterized in that, In the MHP acid leaching solution, the concentration of calcium ions is 800-900 mg / L, and the concentration of scandium ions is 5-15 mg / L; Preferably, the pH of the pretreated MHP acid leaching solution is 2.5-3.
5.
3. The extraction and impurity removal method according to claim 1 or 2, characterized in that, The organic phase containing the extractant includes both the extractant and the diluent. Preferably, the extractant includes Deyuancui Ca extractant; Preferably, the diluent comprises sulfonated kerosene; Preferably, the mass ratio of the extractant to the diluent is 1:(0.8-1.2).
4. The extraction and impurity removal method according to any one of claims 1-3, characterized in that, The saponification value of the saponified organic phase is 0.15-0.3; Preferably, the saponification step includes: The organic phase containing the extractant is reacted with an alkali to undergo saponification.
5. The extraction and impurity removal method according to any one of claims 1-4, characterized in that, The countercurrent extraction process has 7-9 stages; Preferably, during the countercurrent extraction process, the flow rate of the pretreated MHP acid leaching solution is 1380-2280 mL / h, and the flow rate of the saponified organic phase is 360-720 mL / h.
6. The extraction and impurity removal method according to any one of claims 1-5, characterized in that, The pickling process uses a pickling solution including dilute sulfuric acid, the concentration of which is 0.25-1N. Preferably, the number of extraction stages in the acid washing extraction line is 2-5. Preferably, the flow rate of the dilute sulfuric acid is 180-600 mL / h.
7. The extraction and impurity removal method according to any one of claims 1-5, characterized in that, In the process of calcium back-extraction, the back-extraction agent used includes dilute hydrochloric acid, and the concentration of the dilute hydrochloric acid is 2-5N. Preferably, the number of back-extraction stages for the back-extracted calcium is 5-7. Preferably, the flow rate of the dilute hydrochloric acid is 100-240 mL / h.
8. The extraction and impurity removal method according to any one of claims 1-5, characterized in that, In the scandium back-extraction process, the back-extraction agent used includes sulfuric acid, and the concentration of the sulfuric acid is 3-5N. Preferably, the scandium back-extraction stage is 1-2 stages; Preferably, the flow rate of the sulfuric acid is 100-240 mL / h.
9. The extraction and impurity removal method according to any one of claims 1-8, characterized in that, The concentration of calcium ions in the raffinate is <1 mg / L; Preferably, the concentration of scandium ions in the raffinate is <0.1 mg / L.
10. The extraction and impurity removal method according to any one of claims 1-9, characterized in that, The extraction and impurity removal method includes the following steps: (1) Provide MHP acid leaching solution; wherein the concentration of nickel ions in the MHP acid leaching solution is 90-100 g / L, the concentration of cobalt ions is 7-7.6 g / L, the concentration of calcium ions is 800-900 mg / L, and the concentration of scandium ions is 5-15 mg / L; wherein the MHP acid leaching solution contains sulfate anions; The pH of the MHP leaching solution was adjusted to obtain a pretreated MHP leaching solution with a pH of 2.5-3.
5. An organic phase containing an extractant is reacted with an alkali and saponified to obtain a saponified organic phase with a saponification value of 0.15-0.3; the organic phase containing the extractant includes an extractant and a diluent, the extractant including Deyuancui Ca extractant, and the diluent including sulfonated kerosene; the mass ratio of the extractant to the diluent is 1:(0.8-1.2); wherein, the alkali includes liquid alkali; (2) The saponified organic phase is used to perform countercurrent extraction on the pretreated MHP acid leaching solution to obtain raffinate and supported organic phase; the supported organic phase contains calcium ions and scandium ions; The countercurrent extraction process has 7-9 stages; the flow rate of the pretreated MHP acid leaching solution is 1380-2280 mL / h, and the flow rate of the saponified organic phase is 360-720 mL / h; the concentration of calcium ions in the raffinate is <1 mg / L, and the concentration of scandium ions is <0.1 mg / L. The raffinate was subjected to precipitation treatment to obtain a nickel-cobalt precipitate; (3) The loaded organic phase is acid-washed with dilute sulfuric acid with a concentration of 0.25-1N and a flow rate of 180-600mL / h. The extraction line of the acid washing is 2-5 stages to obtain nickel-cobalt washing solution and washed organic phase. (4) Use dilute hydrochloric acid with a concentration of 2-5N and a flow rate of 100-240mL / h to back-extract calcium from the washed organic phase. The back-extraction stage is 5-7 stages to obtain the first back-extraction solution and the back-extracted organic phase. The first back-extraction solution was concentrated and crystallized to recover calcium salts; (5) The stripped organic phase is stripped with scandium using sulfuric acid with a concentration of 3-5N and a flow rate of 100-240mL / h. The stripping stage is 1-2 stages to obtain a second stripping solution and a regenerated organic phase. The regenerated organic phase is reused in the organic phase containing the extractant in step (1). The second back-extraction solution was subjected to precipitation, filtration, and calcination to recover scandium oxide.