Acid-salt separation method for acid-containing high-valence metal salt solution

Abstract

The invention provides an acid-salt separation method for an acid-containing high-valence metal salt solution, and belongs to the technical field of salt solution separation. According to the acid-salt separation method provided by the invention, the high-valence metal hydroxide precipitate is generated through the precipitation reaction of sodium hydroxide and the high-valence metal ions in the acid-containing high-valence metal salt solution, so that the high-valence metal ions are effectively separated, and the problem of bipolar membrane blockage caused by high-valence metal hydroxide formed by direct use of bipolar membrane separation is avoided; carrying out conversion separation on the sodium salt subjected to the precipitation reaction by utilizing bipolar membrane electroosmosis to obtain acid liquor and alkali liquor, and separating to obtain acid in the acid-containing high-valence metal salt solution; and dissolving the high-valence metal hydroxide precipitate by using the obtained acid solution to obtain a high-valence metal salt solution, thereby effectively realizing acid-salt separation of the acid-containing high-valence metal salt solution. Results of the embodiment show that the acid-salt separation method provided by the invention realizes effective separation of the acid and the metal salt in the acid-containing high-valence metal salt solution, and the recovery rate of the metal salt can reach 100%.

Description

Technical Field

[0001] The present invention relates to the technical field of salt solution separation, and particularly to a method for separating acid and salt from a solution of a high-valent metal salt containing acid. Background Art

[0002] In many fields such as metal smelting and food production, a large amount of acid-salt waste is generated. Under the vision of "zero discharge" and circular economy, realizing the separation of acid and salt in acid-salt waste is not only to remove harmful substances, but also to achieve the efficient recovery and reuse of acid and salt resources. In the field of acid-salt separation, the separation of acid and salt from a solution of a high-valent metal salt containing acid has a relatively high technical difficulty and has always been the key research direction of researchers at home and abroad.

[0003] Currently, the commonly used methods for acid-salt separation are evaporation, nanofiltration, ion exchange resin, and bipolar membrane. However, the above four separation methods all have certain limitations for the separation of a solution of a high-valent metal salt containing acid. The evaporation process consumes a large amount of energy, and due to the presence of acid, the metal salt cannot be separated from the solution in the form of crystals; nanofiltration is a separation technology driven by pressure, and there is too high an osmotic pressure inside the solution of a high-valent metal salt containing acid, which will affect the nanofiltration separation effect; although the ion exchange resin can selectively adsorb high-valent metal ions from the solution, due to the presence of acid, there will be competitive adsorption between hydrogen ions and high-valent metal ions, affecting the adsorption effect of the ion exchange resin on high-valent metal ions; moreover, there is a technology in the prior art that provides an ion exchange resin for acid-salt separation. When the acid concentration in the acid-salt solution exceeds 0.5 mol / L, the ion exchange resin has almost no adsorption effect on metal ions; and in the currently typical solution of a high-valent metal salt containing acid, the acid concentration can reach 2 mol / L or even higher, that is to say, the ion exchange resin has limited separation effect on the solution of a high-valent metal salt containing acid; although the bipolar membrane can separate the acid-salt solution into an acid solution and a salt solution, high-valent metal ions often form metal salt hydroxide precipitates in a neutral environment, resulting in the blockage of the bipolar membrane channels, which greatly limits the application of the bipolar membrane in the acid-salt separation of a solution of a high-valent metal salt containing acid.

[0004] In summary, the commonly used acid-salt separation methods in the prior art cannot meet the acid-salt separation of a solution of a high-valent metal salt containing acid, and there is an urgent need for a method that can effectively separate the acid and metal salt in the solution of a high-valent metal salt containing acid. Summary of the Invention

[0005] The purpose of the present invention is to provide a method for separating acid and salt from a solution of a high-valent metal salt containing acid. The separation method provided by the present invention can effectively separate the acid and metal salt in the solution of a high-valent metal salt containing acid, and the recovery rate of the metal salt can reach 100%.

[0006] In order to achieve the above invention purpose, the present invention provides the following technical solutions: The present invention provides a method for separating acid and high-valent metal salt in a solution containing acid and high-valent metal salt, comprising the following steps: (1) Performing a precipitation reaction on the solution containing acid and high-valent metal salt and sodium hydroxide, followed by solid-liquid separation, to obtain a high-valent metal hydroxide precipitate and a sodium salt solution; (2) Concentrating the sodium salt solution obtained in step (1) and then performing bipolar membrane electroosmosis to obtain a sodium hydroxide solution and an acid solution; (3) Dissolving the high-valent metal hydroxide precipitate in step (1) with a part of the acid solution obtained in step (2) to obtain a high-valent metal salt solution.

[0007] Preferably, in step (1), sodium hydroxide is added in the form of a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 1-3 mol / L.

[0008] Preferably, the sodium hydroxide solution obtained in step (2) is recycled to step (1).

[0009] Preferably, the time for the precipitation reaction in step (1) is 20-40 min.

[0010] Preferably, in step (2), the concentration multiple for concentration is 2-8 times, and the concentration pressure is 3-5 MPa.

[0011] Preferably, in step (2), the voltage of each bipolar membrane unit for bipolar membrane electroosmosis is 1.5-2 V, and the current density of each bipolar membrane unit is 600-800 A / m 2 ; the membrane surface flow rate for the bipolar membrane electroosmosis is 3-10 cm / s.

[0012] Preferably, in step (2), the concentration of the acid solution is 1-3 mol / L.

[0013] Preferably, in step (3), the pH value of the high-valent metal salt solution is 4-5.

[0014] Preferably, in step (3), the dissolution time is 1-3 h.

[0015] Preferably, the acid in the solution containing acid and high-valent metal salt in step (1) is hydrochloric acid, sulfuric acid or nitric acid; the high-valent metal salt in the solution containing acid and high-valent metal salt is one or more of nickel salt, calcium salt, magnesium salt, copper salt and cobalt salt; the hydrogen ion concentration of the solution containing acid and high-valent metal salt is 1-3 mol / L, and the high-valent metal ion concentration is 10-200 g / L.

[0016] The present invention provides a method for separating acid and salt from a solution of a high-valent metal salt containing acid, comprising the following steps: (1) performing a precipitation reaction on the solution of the high-valent metal salt containing acid and sodium hydroxide, followed by solid-liquid separation to obtain a precipitate of high-valent metal hydroxide and a sodium salt solution; (2) concentrating the sodium salt solution obtained in step (1) and then performing bipolar membrane electroosmosis to obtain a sodium hydroxide solution and an acid solution; (3) dissolving the precipitate of high-valent metal hydroxide in step (1) with a part of the acid solution obtained in step (2) to obtain a high-valent metal salt solution. The present invention utilizes the precipitation reaction between sodium hydroxide and high-valent metal ions in the solution of the high-valent metal salt containing acid to generate a precipitate of high-valent metal hydroxide, thereby effectively separating the high-valent metal ions in the solution and avoiding the problem of bipolar membrane blockage caused by directly using bipolar membrane separation to form high-valent metal hydroxide; then, bipolar membrane electroosmosis is used to convert and separate the sodium salt of the above precipitation reaction to obtain an acid solution and an alkali solution, so as to separate the acid in the solution of the high-valent metal salt containing acid; the obtained acid solution is used to dissolve the precipitate of high-valent metal hydroxide to obtain a high-valent metal salt solution, thereby effectively realizing the separation of acid and salt in the solution of the high-valent metal salt containing acid. The results of the examples show that the method for separating acid and salt provided by the present invention effectively separates the acid and metal salt in the solution of the high-valent metal salt containing acid, and the recovery rate of the metal salt can reach 100%. Detailed Embodiments

[0017] The present invention provides a method for separating acid and salt from a solution of a high-valent metal salt containing acid, comprising the following steps: (1) Performing a precipitation reaction on the solution of the high-valent metal salt containing acid and sodium hydroxide, followed by solid-liquid separation to obtain a precipitate of high-valent metal hydroxide and a sodium salt solution; (2) Concentrating the sodium salt solution obtained in step (1) and then performing bipolar membrane electroosmosis to obtain a sodium hydroxide solution and an acid solution; (3) Dissolving the precipitate of high-valent metal hydroxide in step (1) with a part of the acid solution obtained in step (2) to obtain a high-valent metal salt solution.

[0018] The present invention performs a precipitation reaction on the solution of the high-valent metal salt containing acid and sodium hydroxide, followed by solid-liquid separation to obtain a precipitate of high-valent metal hydroxide and a sodium salt solution.

[0019] The present invention has no special limitation on the source of the solution of the high-valent metal salt containing acid, and a solution of the high-valent metal salt containing acid well-known to those skilled in the art can be used.

[0020] As an embodiment of the present invention, the acid in the acid-containing high-valent metal salt solution can be hydrochloric acid, sulfuric acid or nitric acid, or sulfuric acid; the high-valent metal salt in the acid-containing high-valent metal salt solution can be one or more of nickel salt, calcium salt, magnesium salt, copper salt and cobalt salt, or nickel salt; the hydrogen ion concentration in the acid-containing high-valent metal salt solution can be 1-3 mol / L, or 1.5-2 mol / L; the concentration of the high-valent metal ions in the acid-containing high-valent metal salt solution can be 10-200 g / L, or 50-150 g / L, or 100-120 g / L; the concentration of the acid radical in the acid-containing high-valent metal salt solution can be 150-240 g / L; or 180-220 g / L, or 200-120 g / L.

[0021] As an embodiment of the present invention, the acid-containing high-valent metal salt solution can be pretreated before the precipitation reaction; the pretreatment can include fine filtration and ultrafiltration carried out in sequence; the filtration accuracy of the fine filtration can be 0.5-10 μm, or 1-8 μm, or 3-5 μm; the filtration accuracy of the ultrafiltration can be 0.01-0.1 μm, can be 0.03-0.08 μm, or 0.05-0.06 μm; the pressure of the ultrafiltration can be 0.1-0.6 MPa, or 0.2-0.3 MPa. In the present invention, by defining the pretreatment process of the acid-containing high-valent metal salt solution, the suspended solids and large particle impurities in the acid-containing high-valent metal salt solution are fully removed by fine filtration, and the fine particles, colloids and organic pollutants in the solution are fully removed by ultrafiltration, avoiding the blockage of the subsequent membrane treatment by impurities and the influence on the acid-salt separation effect.

[0022] As an embodiment of the present invention, the sodium hydroxide can be added in the form of a sodium hydroxide solution; the concentration of the sodium hydroxide solution can be 1-3 mol / L, or 1.5-2.5 mol / L, or 2-2.3 mol / L; the present invention has no special limitation on the dosage of the sodium hydroxide solution, as long as the high-valent metal ions in the acid-containing high-valent metal salt solution can be completely precipitated. In the present invention, by defining the concentration of the sodium hydroxide solution, it is ensured that the high-valent metal ions in the acid-containing high-valent metal salt solution can be completely precipitated, further improving the acid-salt separation effect.

[0023] As an embodiment of the present invention, the time of the precipitation reaction can be 20-40 min, or 25-35 min, or 28-30 min. In the present invention, by defining the time range of the precipitation reaction, it is ensured that the sodium hydroxide solution reacts fully with the high-valent metal ions in the acid-containing high-valent metal salt solution, realizing the complete precipitation of the high-valent metal ions, and further improving the acid-salt separation effect.

[0024] The present invention does not specifically limit the method of solid-liquid separation. Any method of solid-liquid separation commonly used by those skilled in the art can be adopted as long as it can completely separate the precipitate product of the precipitation reaction from the solution. In the embodiments of the present invention, the method of solid-liquid separation can specifically be pressure filtration, centrifugation, or suction filtration.

[0025] After obtaining the high-valent metal hydroxide precipitate and the sodium salt solution, the present invention concentrates the sodium salt solution and then performs bipolar membrane electroosmosis to obtain a sodium hydroxide solution and an acid solution.

[0026] As an embodiment of the present invention, the concentration method can be reverse osmosis membrane technology; the concentration multiple can be 2 to 8 times, or 3 to 7 times, or 5 to 6 times; the concentration pressure can be 3 to 5 MPa, or 3.5 to 4.5 MPa, or 4 to 4.2 MPa. In the present invention, by limiting the concentration method and process parameters, the concentration of the sodium salt solution is controlled, the treatment efficiency of subsequent bipolar membrane electroosmosis is effectively improved, and the blockage and damage of the bipolar membrane are avoided simultaneously.

[0027] As an embodiment of the present invention, the voltage of each bipolar membrane unit in the bipolar membrane electroosmosis can be 1.5 to 2 V, or 1.6 to 1.9 V, or 1.7 to 1.8 V; the current density of each bipolar membrane unit in the bipolar membrane electroosmosis can be 600 to 800 A / m 2 ,or 650 to 750 A / m 2 ,or 680 to 700 A / m 2 ; the membrane surface flow rate of the bipolar membrane electroosmosis can be 3 to 10 cm / s, or 4 to 8 cm / s, or 5 to 6 cm / s. In the present invention, by limiting the process parameters of the bipolar membrane electroosmosis, the efficient progress of the electrochemical reaction is ensured, and the sufficient contact between the concentrated sodium salt solution and the separation membrane is ensured, realizing the effective separation of the sodium salt solution and effectively separating the acid solution from the acid-containing high-valent metal salt solution.

[0028] The present invention does not specifically limit the number of groups of bipolar membrane units connected in series in the bipolar membrane electroosmosis, which can be determined according to the amount of the concentrated sodium salt solution as long as the sodium salt solution can be completely separated to obtain a sodium hydroxide solution and an acid solution.

[0029] As an embodiment of the present invention, the sodium hydroxide solution obtained by the bipolar membrane electroosmosis can be recycled to the precipitation reaction of the acid-containing high-valent metal salt solution. In the present invention, through the recycling of the sodium hydroxide solution, the reaction cost can be effectively reduced.

[0030] As an embodiment of the present invention, the concentration of the sodium hydroxide solution obtained by bipolar membrane electroosmosis can be 1 - 3 mol / L, or 1.5 - 2.5 mol / L, or 2 - 2.3 mol / L; the concentration of the acid solution obtained by bipolar membrane electroosmosis can be 1 - 3 mol / L, or 1.5 - 2.5 mol / L, or 2 - 2.3 mol / L. In the present invention, by limiting the concentration of the products obtained by bipolar membrane electroosmosis, the complete separation of the sodium salt solution is ensured, and the separation effect is further improved; at the same time, the quality of the acid solution separated from the acid-containing high-valent metal salt solution is further improved.

[0031] After obtaining the sodium hydroxide solution and the acid solution, the present invention uses a part of the acid solution to dissolve the high-valent metal hydroxide precipitate to obtain a high-valent metal salt solution.

[0032] As an embodiment of the present invention, the pH value of the high-valent metal salt solution is 4 - 5. In the present invention, by limiting the pH value of the high-valent metal salt solution after dissolution, the amount of the acid solution is controlled, so that the high-valent metal hydroxide precipitate can be just completely dissolved, and the high-valent metal salt solution in the acid-containing high-valent metal salt solution can be effectively separated.

[0033] As an embodiment of the present invention, the dissolution time can be 1 - 3 h, or 1.5 - 2.5 h, or 1.8 - 2 h. In the present invention, by limiting the dissolution time, the complete dissolution of the metal hydroxide precipitate is achieved, the high-valent metal salt solution is effectively separated, and the recovery rate of the high-valent metal salt is further improved.

[0034] As an embodiment of the present invention, the remaining part of the acid solution is the acid in the separated acid-containing high-valent metal salt solution.

[0035] The acid-salt separation method provided by the present invention realizes the effective separation of the acid and the high-valent metal salt in the acid-containing high-valent metal salt solution, and at the same time effectively avoids the problem of bipolar membrane blockage caused by directly using a bipolar membrane to separate and form a high-valent metal hydroxide; by recycling the sodium hydroxide obtained by bipolar membrane electroosmosis separation to the precipitation process, a closed-loop process is formed, effectively reducing the production cost and reducing the waste discharge, and the concentrations of the alkali solution and the acid solution obtained by bipolar membrane electroosmosis separation are controllable and can be adjusted according to needs to meet the specific requirements of different application scenarios; the present invention performs precision filtration and membrane separation technology on the acid-containing high-valent metal salt solution to ensure the purity of the metal salt product; and this technology can operate continuously and stably for a long time, the equipment is compact, reducing the space requirement of the factory layout and effectively reducing the investment cost.

[0036] To further illustrate the present invention, the following describes in detail the acid-salt separation method for the acid-containing high-valent metal salt solution provided by the present invention in combination with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0037] Example 1 An acid-salt separation method for a mixed solution of sulfuric acid and nickel sulfate in a certain production link of a high-nickel ternary cathode material is as follows: (1) The mixed solution of sulfuric acid and nickel sulfate (Ni 2+ concentration is 70 g / L, H + concentration is 1.1 mol / L, SO4 2- concentration is 168 g / L) is finely filtered through a PP cotton filter element with a filtration accuracy of 5 μm, and then ultrafiltered through an ultrafiltration membrane with a filtration accuracy of 0.05 μm at 0.3 MPa; the pretreated mixed solution of sulfuric acid and nickel sulfate and a 2.05 mol / L sodium hydroxide solution are subjected to a precipitation reaction for 30 min to completely precipitate the nickel ions in the mixed solution of sulfuric acid and nickel sulfate. After the precipitation reaction is completed, pressure filtration is carried out to obtain nickel hydroxide precipitate and a sodium sulfate solution with a volume concentration of 6.4%; (2) The sodium sulfate solution obtained in step (1) is concentrated 2.3 times at 4.8 MPa by using a reverse osmosis membrane, and the concentration of the sodium sulfate solution is increased to 15%; after the concentration is completed, bipolar membrane electroosmosis is carried out. The bipolar membrane electroosmosis includes 400 groups of series-connected bipolar membrane units. The voltage of each group of bipolar membrane units is 1.8 V and the current density is 650 A / m 2 , and the membrane surface flow rate of the bipolar membrane electroosmosis is 6 cm / s to obtain a 2.05 mol / L sodium hydroxide solution and a 1 mol / L sulfuric acid; the obtained sodium hydroxide solution can be returned to step (1); (3) Dissolve the nickel hydroxide precipitate in step (1) with a part of the sulfuric acid obtained in step (2) for 1.5 h to obtain a nickel sulfate solution with a pH value of 4.5 and a concentration of 192 g / L, where the Ni 2+ concentration is 72 g / L, and the salt recovery rate reaches 100%.

[0038] Example 2 An acid-salt separation method for a mixed solution of sulfuric acid and copper sulfate in a certain production link of copper electroplating includes the following steps: (1) The mixed solution of sulfuric acid and copper sulfate (Cu 2+ concentration is 82 g / L, H + concentration is 1.3 mol / L, SO4 2-The mixed solution of sulfuric acid and copper sulfate with a concentration of 183 g / L is finely filtered through a PP cotton filter element with a filtration accuracy of 5 μm, and then ultrafiltered through an ultrafiltration membrane with a filtration accuracy of 0.05 μm at 0.3 MPa; the pretreated mixed solution of sulfuric acid and copper sulfate is subjected to a precipitation reaction with a 2.08 mol / L sodium hydroxide solution for 30 min to completely precipitate the copper ions in the mixed solution of sulfuric acid and copper sulfate. After the precipitation reaction is completed, pressure filtration is carried out to obtain copper hydroxide precipitate and a sodium sulfate solution with a volume concentration of 6.9%. (2)The sodium sulfate solution obtained in step (1) is concentrated 2.17 times at 4.2 MPa using a reverse osmosis membrane, and the concentration of the sodium sulfate solution is increased to 15%; after concentration, bipolar membrane electroosmosis is carried out. The bipolar membrane electroosmosis includes 400 series-connected bipolar membrane units, and the voltage of each bipolar membrane unit is 1.8 V and the current density is 650 A / m 2 , and the membrane surface flow rate of the bipolar membrane electroosmosis is 6 cm / s to obtain a sodium hydroxide solution with a concentration of 2.08 mol / L and a sulfuric acid with a concentration of 1 mol / L; the obtained sodium hydroxide solution can be returned to step (1); (3)Dissolve the copper hydroxide precipitate in step (1) with a part of the sulfuric acid obtained in step (2) for 1.5 h to obtain a copper sulfate solution with a pH value of 4.5 and a concentration of 202 g / L, where the Cu 2+ concentration is 82 g / L, and the salt recovery rate reaches 100%.

[0039] Comparative Example 1 A method for separating sulfuric acid and nickel sulfate in a mixed solution in a certain production link of a high-nickel ternary cathode material is as follows: (1)The mixed solution of sulfuric acid and nickel sulfate (Ni 2+ with a concentration of 70 g / L, H + with a concentration of 1.1 mol / L, and SO4 2- with a concentration of 168 g / L) is finely filtered through a PP cotton filter element with a filtration accuracy of 5 μm, and then ultrafiltered through an ultrafiltration membrane with a filtration accuracy of 0.05 μm at 0.3 MPa to obtain a pretreated mixed solution; (2)The pretreated mixed solution obtained in step (1) is subjected to bipolar membrane electroosmosis. The bipolar membrane electroosmosis includes 400 series-connected bipolar membrane units, and the voltage of each bipolar membrane unit is 1.8 V and the current density is 650 A / m 2 , and the membrane surface flow rate of the bipolar membrane electroosmosis is 6 cm / s.

[0040] Since the hydroxide ions generated by the bipolar membrane electrolyzing water react with nickel to form a precipitate, the bipolar membrane is blocked. The bipolar membrane process cannot continue, and effective acid-salt separation cannot be carried out.

[0041] Comparing Examples 1-2 with Comparative Example 1, it can be seen that the acid-salt separation method provided by the present invention realizes the effective separation of acid and high-valent metal salt in the acid-containing high-valent metal salt solution, and the recovery rate of the metal salt can reach 100%.

[0042] The above are only the preferred embodiments of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present invention.

Claims

1. A method for separating acid and salt from a solution of a high-valent metal salt containing acid, characterized in that, It includes the following steps: (1) After carrying out a precipitation reaction between a solution of a metal salt with high valence and acid and sodium hydroxide, solid-liquid separation is performed to obtain a precipitate of metal hydroxide with high valence and a sodium salt solution; (2) The sodium salt solution obtained in the step (1) is concentrated and then subjected to bipolar membrane electroosmosis to obtain a sodium hydroxide solution and an acid solution; (3) Part of the acid solution obtained in the step (2) is used to dissolve the precipitate of metal hydroxide with high valence in the step (1) to obtain a solution of a metal salt with high valence.

2. The acid-salt separation method according to claim 1, characterized in that, In the step (1), sodium hydroxide is added in the form of a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 1 - 3 mol / L.

3. The acid salt separation method according to claim 2, characterized in that, The sodium hydroxide solution obtained in the step (2) is recycled to the step (1).

4. The acid salt separation method according to claim 1, characterized in that, The time for the precipitation reaction in the step (1) is 20 - 40 min.

5. The acid salt separation method according to claim 1, characterized in that In the step (2), the concentration multiple is 2 - 8 times, and the concentration pressure is 3 - 5 MPa.

6. The acid-salt separation method according to claim 1, characterized in that, In step (2), the voltage of each bipolar membrane unit in bipolar membrane electroosmosis is 1.5 - 2 V, and the current density of each bipolar membrane unit is 600 - 800 A / m 2 ; the membrane surface flow rate of the bipolar membrane electroosmosis is 3 - 10 cm / s.

7. The acid salt separation method according to claim 1, wherein In the step (2), the concentration of the acid solution is 1 - 3 mol / L.

8. The acid salt separation method according to claim 1, characterized in that, In the step (3), the pH value of the solution of a metal salt with high valence is 4 - 5.

9. The acid-salt separation method according to claim 1, wherein In the step (3), the dissolution time is 1 - 3 h.

10. The acid-salt separation method according to any one of claims 1 to 9, characterized in that, The acid in the solution of a metal salt with high valence and acid in the step (1) is hydrochloric acid, sulfuric acid or nitric acid; the metal salt with high valence in the solution of a metal salt with high valence and acid is one or more of nickel salt, calcium salt, magnesium salt, copper salt and cobalt salt; the hydrogen ion concentration of the solution of a metal salt with high valence and acid is 1 - 3 mol / L, and the concentration of the metal ion with high valence is 10 - 200 g / L.