Reverse extraction crystallization method

Abstract

The invention belongs to the technical field of hydrometallurgy extraction and crystallization, and particularly relates to a reverse extraction crystallization method which comprises the following steps: S1, a loaded organic solvent and a saturated reverse extraction solution are obtained, the loaded organic solvent comprises an organic solvent and metal ions loaded by the organic solvent, and the saturated reverse extraction solution comprises a saturated salt solution of the metal ions; s2, the saturated strip liquor reacts with the loaded organic solvent to separate out ionic crystals, raffinate and a no-load organic solvent are obtained, the raffinate comprises a saturated solution of the salt solution of the metal ions, and the ionic crystals comprise the metal ions; according to the method, the loaded organic solvent is extracted through the saturated strip liquor, crystallization and rapid growth of metal salt can be promoted, evaporation and concentration of the solution are not needed, the crystallization efficiency is improved, and the production cost is reduced; meanwhile, continuous production can be achieved in the production process, and the production efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgical extraction and crystallization, and specifically relates to a stripping crystallization method. Background Art

[0002] At present, in the production technology of metal salts of many metals such as nickel and cobalt, most of them adopt extraction and purification followed by acid back extraction of the loaded organic phase to obtain a pure metal salt solution, and then evaporate, concentrate and crystallize the metal salt solution to obtain the corresponding metal salts. The evaporation process consumes a lot of steam and electricity, increasing production costs and a lot of investment. Finding a process technology that can reduce the energy consumption and investment of traditional metal salt production is the direction of industry development. Summary of the invention

[0003] In order to solve the problems existing in the prior art, the main purpose of the present invention is to provide a stripping crystallization method, comprising the following steps: S1, obtaining a loaded organic solvent and a saturated stripping solution, wherein the loaded organic solvent comprises an organic solvent and metal ions loaded by the organic solvent, and the saturated stripping solution comprises a saturated salt solution of the metal ions; S2. Reacting the saturated stripping solution with the loaded organic solvent to precipitate ionic crystals to obtain a raffinate and an unloaded organic solvent, wherein the raffinate comprises a saturated solution of a salt solution of the metal ions, and the ionic crystals comprise the metal ions.

[0004] The saturated stripping solution is obtained by continuously reacting the stripping agent and the loaded organic solvent until the salt solution of the metal ions in the stripping solution is saturated, or the saturated stripping solution is obtained by supplementing the stripping agent with the raffinate, or the saturated stripping solution is directly prepared by the stripping agent and the salt of the metal ions.

[0005] Wherein, in the step S2: the saturated stripping solution is reacted with the loaded organic solvent and then cooled to 3-35° C. to accelerate the precipitation and growth of the ionic crystals.

[0006] Wherein, the step S2 further comprises: separating the ionic crystals, the raffinate and the empty organic solvent, recovering the raffinate and the organic solvent, and recovering the ionic crystals after dehydration.

[0007] Wherein, the step S2 further comprises: when recovering the raffinate, simultaneously recovering part of the ionic crystals, so that part of the ionic crystals exist in the raffinate in the form of crystals.

[0008] Wherein, the loaded organic solvent includes: a copper-loaded organic phase of M5640, a nickel-loaded organic phase of P507 or a cobalt-loaded organic phase of CY272.

[0009] Among them, the stripping agent includes: hydrochloric acid or sulfuric acid.

[0010] Among them, the hydrogen ion concentration in the stripping agent is 1-12 mol / L.

[0011] Among them, the acid radical of the metal ion salt solution is the same as that of the stripping agent.

[0012] Among them, the acid radical concentration of the acid in the stripping agent is greater than the extraction concentration, and the extraction concentration is the acid radical concentration of the saturated salt solution of the metal ion at 40-45 °C.

[0013] By using a saturated stripping solution to extract the loaded organic solvent, the present invention can promote the crystallization and rapid growth of metal salts, without the need for evaporation and concentration of the solution, improving the crystallization efficiency and reducing the production cost; at the same time, the present invention can be carried out continuously during the production process, increasing the production efficiency. Detailed implementation manners

[0014] The technical solutions in the embodiments will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0015] In the embodiments of the present application, concentrated H2SO4 or concentrated HCl is used as the stripping agent to prepare a stripping solution with a saturated solution of a metal salt solution such as Cu, Ni or Co, and it is subjected to a stripping reaction with a loaded organic phase loaded with metal cations such as Cu, Ni or Co, so that the metal ions in the organic phase undergo a displacement reaction with the hydrogen ions in the stripping acid radical, and the metal ions in the loaded organic phase enter the stripping acid solution. The hydrogen ions in the stripping acid solution decrease, and the metal ion concentration increases, making the metal ion concentration in the solution reach a supersaturated state exceeding its solubility at the corresponding temperature. The chemical reaction principle equation is as follows: H2SO4 + 2NR = 2HR + NSO4, 2HCl + 2NR = 2HR + NCl2 (R represents extraction agents such as M5640, P507, CY272, etc., and N represents metal ions such as Cu, Ni, Co, etc.); among them, the acid radical ions in the metal salt solution are the same as those in the stripping agent.

[0016] In other embodiments, the loaded organic phase can also be other organic solvents loaded with other metal ions, and the types of acids used for the stripping agent can also be other acids, which are not limited in the present application.

[0017] S1. Obtain a loaded organic solvent and a saturated stripping solution. The loaded organic solvent includes an organic solvent and metal ions loaded by the organic solvent. The saturated stripping solution includes a saturated salt solution of the metal ions. S2. React the saturated stripping solution with the loaded organic solvent to precipitate ionic crystals, obtaining a raffinate and the unloaded organic solvent. The raffinate includes a saturated solution of a salt solution of the metal ions, and the ionic crystals include the metal ions.

[0018] Wherein, the saturated stripping solution is obtained by continuously reacting a stripping agent with the loaded organic solvent until the salt solution of the metal ions in the stripping solution is saturated, or the saturated stripping solution is obtained by supplementing the stripping agent to the raffinate, or the saturated stripping solution is directly prepared from a stripping agent and a salt of the metal ions. If the saturated stripping solution is obtained by continuously reacting a stripping agent with the loaded organic solvent until the salt solution of the metal ions in the solution is saturated, it can be understood that a stripping solution containing a salt solution of the metal ions can be obtained by directly reacting the stripping agent with the loaded organic solvent, but the salt containing the metal ions is not saturated. The process stripping agent can be obtained by recovering the stripping solution and supplementing the stripping agent thereto. The process stripping agent is then reacted with the loaded organic solvent, and the cycle is repeated until the salt solution of the metal ions in the process stripping agent is saturated, obtaining the saturated stripping solution.

[0019] If the saturated stripping solution is obtained by supplementing the stripping agent to the raffinate, it can be understood that if the raffinate contains a saturated solution of a salt solution of the metal ions, supplementing the stripping agent to the raffinate can be used as the saturated stripping solution in step S1 to strip the loaded organic solvent. Further, after each stripping with the saturated stripping solution, a raffinate containing a saturated solution of a salt solution of the metal ions can be obtained. Therefore, the technical solution in the present application can continuously crystallize and increase the crystallization efficiency by recovering the raffinate, supplementing the stripping agent to the raffinate, and then continuously extracting the loaded organic solvent.

[0020] If the saturated stripping solution is directly prepared from a stripping agent and a salt of the metal ions, it can be understood that the saturated stripping solution can also be directly prepared from a stripping agent and a salt of the metal ions to obtain a saturated stripping solution including a saturated salt solution of the metal ions.

[0021] Further, since the stripping reaction is exothermic, the temperature of the raffinate will increase, increasing the solubility of the metal ion salt solution. By cooling the raffinate, the solubility of the metal ion salt solution can be reduced, making it easier for the metal ion salt solution to become saturated. It can be understood that even without active cooling, during the process of recovering the raffinate, the raffinate will release heat to the environment due to its temperature being higher than the environment, resulting in a temperature decrease.

[0022] Further, in some embodiments of the present application, while recovering the raffinate, some crystals are introduced into the raffinate. When the raffinate is used as a saturated stripping agent for the stripping reaction again after replenishing the stripping agent, the some crystals can act as crystal seeds to accelerate the crystallization process.

[0023] Further, in some embodiments of the present application, the saturated stripping agent is used to strip the loaded organic solvent to separate the crystals and the raffinate. After replenishing the stripping agent to the raffinate, it is used as a saturated stripping agent to continue stripping the loaded organic solvent, and the process can be continuous and cyclic. It can be understood that during the cyclic process, if the raffinate is not a saturated solution of the metal ion salt solution after replenishing the stripping agent, after stripping the loaded organic solvent, the concentration of the metal ion salt solution in the raffinate will increase, and then continue to replenish the stripping agent and cycle until the metal ion salt solution in the raffinate reaches saturation. If the raffinate is still a saturated solution of the metal ion salt solution after replenishing the stripping agent, after the stripping reaction, the crystals and the raffinate are separated, and the stripping agent is replenished to the raffinate and then continue to cycle.

[0024] Example 1 A stripping crystallization method includes the following steps: S1. Obtain the organic phase M5640 loaded with Cu 2+ , prepare sulfuric acid containing a saturated copper sulfate solution as a saturated stripping agent. The saturated stripping agent contains 62 g / L of Cu 2+ and 580 g / L of H2SO4, and the temperature of the saturated stripping agent is 45 °C; S2. Use the saturated stripping agent to perform back extraction on the loaded organic solvent. The obtained light phase is the unloaded M5640 organic solvent, and the obtained heavy phase is the raffinate. The raffinate contains 125 g / L of Cu 2+ and 30 g / L of H2SO4, the temperature of the raffinate is 45 °C. Separate the light phase and the heavy phase, and recover the M5640 organic solvent in the light phase; S3. After the crystals generated in the raffinate grow, separate the crystals and the raffinate, dehydrate the crystals to obtain CuSO4·5H2O crystals, and replenish concentrated sulfuric acid to the raffinate until the Cu 2+The raffinate after supplementation is returned to S2 as a saturated extractant for back extraction, where the Ni content is 62 g / L and the H2SO4 content is 580 g / L. S4. Repeat S2 and S3 to continuously perform back extraction crystallization and continuously produce CuSO4·5H2O crystals.

[0025] Example 2 A back extraction crystallization method includes the following steps: S1. Obtain the organic phase P507 loaded with Ni 2+ and prepare sulfuric acid containing saturated copper sulfate solution as a saturated back extractant. The saturated back extractant contains 115 g / L of Ni 2+ and 50 g / L of H2SO4, and the temperature of the saturated back extractant is 45°C. S2. Use the saturated back extractant to perform back extraction on the loaded organic solvent. The obtained light phase is the empty P507 organic solvent, and the obtained heavy phase is the raffinate. The raffinate contains 145 g / L of Ni 2+ and 10 g / L of H2SO4. The temperature of the raffinate is 45°C. Separate the light phase and the heavy phase, and recover the P507 organic solvent in the light phase. S3. Cool the raffinate to 3°C. After the crystals generated in the raffinate grow, the Ni concentration in the raffinate is 121 g / L, and the H2SO4 concentration is 10 g / L. Separate part of the crystals and the raffinate, so that part of the fine crystals still exist in the raffinate in crystal form. Dehydrate the separated part of the crystals to obtain NiSO4·7H2O crystals. Add concentrated sulfuric acid to the raffinate until the Ni content in the raffinate is 115 g / L and the H2SO4 content is 50 g / L. Return the supplemented raffinate to S2 as a saturated extractant for back extraction. 2+ 2+ S4. Repeat S2 and S3 to continuously perform back extraction crystallization and continuously produce NiSO4·7H2O crystals.

[0026] Example 3 A back extraction crystallization method includes the following steps: S1. Obtain the organic phase CY272 loaded with Co 2+ and prepare sulfuric acid containing saturated copper sulfate solution as a saturated back extractant. The saturated back extractant contains 184 g / L of Co 2+ and 300 g / L of HCl, and the temperature of the saturated back extractant is 40°C. S2. Use the saturated back extractant to perform back extraction on the loaded solvent phase. The obtained light phase is the empty CY272 organic solvent, and the obtained heavy phase is the raffinate. The raffinate contains 315 g / L of Co 2+and 5 g / L of HCl, the temperature of the raffinate is 40 °C, the light phase and the heavy phase are separated, and the CY272 organic solvent in the light phase is recovered; S3. Cool the raffinate to 35 °C. After the crystals generated in the raffinate grow, the Co in the raffinate 2+ has a concentration of 248 g / L, the concentration of HCl is 5 g / L. The crystals and the raffinate are separated, and the crystals are dehydrated to obtain CoCl2·6H2O crystals. Concentrated hydrochloric acid is added to the raffinate until the Co in the raffinate 2+ is 184 g / L and HCl is 300 g / L. The supplemented raffinate is used as a saturated extractant and returned to S2 for back extraction; S4. Repeat S2 and S3, and continuous back extraction crystallization can be carried out to continuously produce CoCl2·6H2O crystals.

[0027] By using a saturated back extractant to extract the loaded organic solvent, the present invention can promote the crystallization and rapid growth of metal salts, without the need for evaporation and concentration of the solution, improving the crystallization efficiency and reducing the production cost; at the same time, the present invention can be carried out continuously during the production process, increasing the production efficiency.

[0028] The above are only the preferred embodiments of the present invention, and do not limit the patent scope of the present invention accordingly. Any equivalent structural transformation made by using the content of the specification of the present invention under the inventive concept of the present invention, or direct / indirect application in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An anti-extraction crystallization method, characterized in that, It includes the following steps: S1. Obtain a loaded organic solvent and a saturated stripping solution. The loaded organic solvent includes an organic solvent and metal ions loaded by the organic solvent. The saturated stripping solution includes a saturated salt solution of the metal ions; S2. React the saturated stripping solution with the loaded organic solvent to precipitate ionic crystals, obtaining a raffinate and the organic solvent without load. The raffinate includes a saturated solution of the salt solution of the metal ions, and the ionic crystals include the metal ions.

2. The counter-extraction crystallization method according to claim 1, wherein The saturated stripping solution is obtained by continuously reacting a stripping agent with the loaded organic solvent until the salt solution of the metal ions in the stripping solution is saturated, or the saturated stripping solution is obtained by supplementing the stripping agent to the raffinate, or the saturated stripping solution is directly prepared from the stripping agent and the salt of the metal ions.

3. The counter-extraction crystallization method according to claim 1, wherein In step S2: After reacting the saturated stripping solution with the loaded organic solvent, cool it to 3 - 35 °C to accelerate the precipitation and growth of the ionic crystals.

4. The counter-extraction crystallization method according to claim 1, wherein Step S2 further includes: Separating the ionic crystals, the raffinate and the organic solvent without load, recovering the raffinate and the organic solvent, and dehydrating and then recovering the ionic crystals.

5. The counter-extraction crystallization method according to claim 4, wherein, Step S2 further includes: When recovering the raffinate, simultaneously recovering part of the ionic crystals so that part of the ionic crystals exist in the form of crystals in the raffinate.

6. The counter-extraction crystallization method according to claim 1, characterized in that, The loaded organic solvent is obtained by extracting the metal ions with the organic solvent.

7. The counter-extraction crystallization method according to claim 2, characterized in that, The stripping agent includes: hydrochloric acid or sulfuric acid.

8. The counter-extraction crystallization method according to claim 7, characterized in that, The hydrogen ion concentration in the stripping agent is 1 - 12 mol / L.

9. The counter-extraction crystallization method according to claim 7, characterized in that, The acid radical of the salt solution of the metal ions is the same as the acid radical of the stripping agent.

10. The counter-extraction crystallization method according to claim 9, wherein The acid radical concentration of the acid in the stripping agent is greater than the extraction concentration, and the extraction concentration is the acid radical concentration of the saturated salt solution of the metal ions at 40 - 45 °C.