CN113957248B - A method for separating zinc and cobalt by selective precipitation and flotation of cobalt ions in acidic solution - Google Patents

Abstract

The invention discloses a zinc-cobalt separation method for selective precipitation and flotation of cobalt ions in an acidic solution, which belongs to the technical field of element separation and solves the problem of low and incomplete cobalt ion separation efficiency in the prior art. It includes: step 1, adjusting the pH of the solution containing zinc and cobalt ions to acidic through a pH adjuster; step 2, adding cobalt ion chelating precipitant and particle stabilizer to the above solution at a certain temperature, and stirring and mixing. , obtain a first intermediate system containing cobalt ion chelated precipitated particles; step 3, add surfactant to the first intermediate system, and stir and mix evenly to obtain a second intermediate system containing cobalt precipitated suspended particles; step 4, use The flotation separation device performs air-filled flotation on the above-mentioned second intermediate system, and collects particles containing cobalt precipitates. The method of the invention effectively solves the problem of zinc and cobalt separation.

Description

A method for separating zinc and cobalt by selective precipitation and flotation of cobalt ions in acidic solution

Technical field

The invention belongs to the technical field of element separation, and particularly relates to a zinc-cobalt separation method for selective precipitation and flotation of cobalt ions in an acidic solution.

Background technique

Cobalt is a strategic key metal supporting the development of high-tech fields. With the popularization of electronic products and the promotion of new energy vehicles, cobalt is used more and more widely in battery materials, and its demand is also increasing day by day. At present, my country has become the largest consumer of cobalt. However, my country's cobalt reserves only account for 1.1% of global reserves, and its dependence on foreign countries exceeds 90%, and most of them are associated with sulfide ores of zinc, copper, nickel and other metals. The cobalt grade of cobalt-containing minerals is generally low, and the direct smelting and extraction process is difficult and costly. Moreover, its output is difficult to meet my country's rapidly growing cobalt consumption demand. Therefore, the development of various cobalt-containing secondary resources (cobalt-containing solid waste, industrial wastewater, etc.) is an effective way to ensure the supply of cobalt raw materials in my country.

Zinc-cobalt-containing smelting slag, industrial solid waste, and used battery materials are important cobalt-containing secondary resources. Through the acid leaching process, metal components can enter the leachate; in addition, some industrial wastewater contains a certain concentration of zinc. Cobalt ions. Whether it is the separation and extraction of cobalt from secondary zinc-cobalt resources or the purification and impurity removal of cobalt in solution, we need to face the problem of efficient separation of zinc and cobalt ions in the solution.

At present, the separation methods of zinc and cobalt in acidic solutions mainly include zinc powder replacement method, extraction method, precipitation method, etc. The zinc powder replacement method uses the potential difference between zinc and cobalt to replace cobalt ions in the reduction solution with zinc powder and form a precipitate; however, this method requires the addition of zinc powder that exceeds the theoretical amount dozens of times, and the cobalt removal slag formed contains a large amount of unreacted The extraction of cobalt from zinc powder and cobalt removal residue will once again face the problem of zinc and cobalt separation, so the difficulty of zinc and cobalt separation has not been completely solved. When solvent extraction is used to separate zinc and cobalt from a solution, the extraction effect is poor because the cobalt ion content in the solution is generally low. At the same time, when precipitation is used to separate zinc and cobalt from the solution, precipitants include sulfide, xanthate, etc. However, also affected by the low content of cobalt ions, it is difficult to form larger precipitated particles, the sedimentation process is slow, and it is difficult to completely separate.

The root cause of the problem of zinc and cobalt separation in solution is that the concentration of cobalt ions is generally low. When using the above methods to separate zinc and cobalt, there are problems such as poor selectivity, slow mass transfer process, low and incomplete separation efficiency. Therefore, how to efficiently separate zinc and cobalt ions has become an urgent problem to be solved.

Contents of the invention

In view of the above analysis, the present invention aims to provide a zinc-cobalt separation method for selective precipitation and flotation of cobalt ions in an acidic solution to solve the problems of poor selectivity and low separation efficiency in the prior art caused by the low concentration of cobalt ions in the solution. And to solve the problem of incompleteness, the present invention can achieve efficient separation of zinc and cobalt ions in the solution.

The purpose of the present invention is mainly achieved through the following technical solutions:

The invention provides a zinc and cobalt separation method for selective precipitation and flotation of cobalt ions in an acidic solution, which includes:

Step 1. Use a pH adjuster to adjust the pH of the solution containing zinc and cobalt ions to acidic;

Step 2. At a certain temperature, simultaneously add cobalt ion chelating precipitant and particle stabilizer to the above solution, stir and mix, and obtain a first intermediate system containing cobalt ion chelating precipitated particles;

Step 3: Add surfactant to the first intermediate system and stir and mix evenly to obtain a second intermediate system containing cobalt precipitated suspended particles;

Step 4: Use a flotation separation device to perform air flotation on the above-mentioned second intermediate system to collect particles containing cobalt precipitates.

Further, in step 1, in the solution containing zinc and cobalt ions, the concentration of zinc ions is 0.5-185g/L, and the concentration of cobalt ions is 1mg/L-5g/L.

Further, in step 1, the pH of the adjusted solution is 2.0-3.5.

Further, in step 1, the pH adjusting agent is an inorganic acid or alkali.

Further, in step 2, the cobalt ion chelating precipitating agent is α-nitroso-β-naphthol.

Further, in step 2, the temperature is 30-70°C.

Further, in step 2, the molar ratio of the added amount of cobalt ion chelating precipitant to the cobalt ions in the solution is 3:1 to 10:1.

Further, in step 2, the particle stabilizer is a solution containing Fe ³⁺ .

Further, in step 2, the molar ratio of the added amount of particle stabilizer to the cobalt ions in the solution is 0.5:1 to 1.5:1.

Further, in step 2, the stirring rate is less than or equal to 100 rpm, and the stirring time is 10 to 60 minutes.

Compared with the existing technology, the present invention can achieve at least one of the following technical effects:

1) For the first time, the present invention applies the chelating precipitation-flotation method to the separation of zinc and cobalt ions in solution, utilizing the selective complexation of cobalt ion chelating precipitating agent (α-nitroso-β-naphthol) and cobalt ions. The cobalt ion chelating precipitant selectively chelates the cobalt ions in the solution, and through the particle stabilizer added at the same time, the chelate of the cobalt ions and the agent forms stable suspended particles, and then with the help of microbubble flotation technology , ultimately achieving the selective extraction of cobalt ions in the solution, thereby achieving the purpose of efficiently separating zinc and cobalt ions in the solution. The method of the invention can be used to separate zinc and cobalt ions and remove cobalt ions in various solutions containing low concentrations of cobalt ions. It has good zinc and cobalt separation effects, high cobalt ion recovery rate, low cost and short process.

2) Existing zinc and cobalt separation technologies include zinc powder replacement method and xanthate precipitation cobalt removal method. Zinc powder replacement method: The zinc powder consumption is large, usually more than 20 times the theoretical amount, the operation time is long, it needs to be carried out at about 80°C, and toxic gases such as AsH ₃ and SbH ₃ are often produced. Xanthate precipitation cobalt removal method: Due to the low concentration of cobalt ions in the solution, in order to make the reaction proceed quickly and remove cobalt completely, an excess of xanthate must be added, and the dosage is generally 10 to 15 times the theoretical dosage. In order to ensure the quality of the purified solution, excess organic chemicals in the leachate need to be removed. Compared with the existing methods, the method of the present invention adopts the precipitation-flotation separation method to achieve the removal of cobalt ions, and has a wide range of applicability to the concentration of metal ions in the solution, especially in the removal of low-concentration ions, and has stronger applicability. The reagent consumption is low; it can be carried out continuously, the solution processing capacity is large, the solid-liquid separation rate is fast, and the metal ion separation is more thorough.

Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by means of the written description.

Detailed ways

A zinc-cobalt separation method for selective precipitation and flotation of cobalt ions in an acidic solution will be further described in detail below with reference to specific examples. These examples are only for comparison and explanation purposes, and the present invention is not limited to these examples. .

A method for separating zinc and cobalt by selective precipitation and flotation of cobalt ions in acidic solution, including the following steps:

Step 1. Use a pH adjuster to adjust the pH of the solution containing zinc and cobalt ions to acidic;

Step 2. At a certain temperature, simultaneously add cobalt ion chelating precipitant and particle stabilizer to the above solution, stir and mix, and obtain a first intermediate system containing cobalt ion chelating precipitated particles;

Step 3: Add surfactant to the first intermediate system and stir and mix evenly to obtain a second intermediate system containing cobalt precipitated suspended particles;

Step 4: Use a flotation separation device to perform air-filled flotation on the above-mentioned second intermediate system to collect particles containing cobalt precipitates to achieve selective chelation precipitation-flotation removal of cobalt ions in the solution and achieve efficient separation of zinc and cobalt.

Specifically, in the above step 1, the solution containing zinc and cobalt ions can be zinc hydrometallurgy acid leaching solution, zinc-cobalt-containing solid residue acid leaching solution, zinc-cobalt-containing electronic waste acid leaching solution, or zinc-cobalt-containing industrial wastewater. The concentration ranges of zinc and cobalt ions are 0.5~185g/L and 1mg/L~5g/L respectively. Wherein, the concentration of zinc ions is 0.5-185g/L, for example, such as 0.5g/L, 5g/L, 10g/L, 30g/L, 40g/L, 50g/L, 70g/L, 90g/L , 100g/L, 120g/L, 130g/L, 140g/L, 150g/L, 170g/L, 180g/L; the concentration of cobalt ions is 1mg/L~5g/L, for example, such as 1mg/L , 10mg/L, 100mg/L, 200mg/L, 300mg/L, 400mg/L, 500mg/L, 600mg/L, 700mg/L, 800mg/L, 900mg/L, 1g/L, 2g/L, 3g /L, 4g/L, 5g/L.

Specifically, in the above step 1, it is considered that the pH of the solution is too high, which will cause hydrolysis and precipitation of zinc ions in subsequent steps, thereby affecting the separation efficiency of zinc and cobalt ions; the pH of the solution is too low, which will affect the chelating precipitant and cobalt ions in subsequent steps. The complexation precipitation efficiency. Therefore, the pH of the solution adjusted in step 1 is controlled to be 2.0-3.5, for example, such as 2.0, 2.2, 2.5, 2.8, 3.0, 3.3, 3.5.

It should be noted that in the above step 1, the pH adjusting agent is an inorganic acid or alkali, such as sulfuric acid, hydrochloric acid or sodium hydroxide.

Specifically, in the above step 2, if the temperature is too high, the chelating precipitant will decompose, causing unnecessary loss of the chelating precipitant; if the temperature is too low, it will increase the difficulty of temperature control during the treatment process; therefore, the control temperature is 30 ~ 70°C, for example, such as 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, and 70°C.

Specifically, in the above step 2, the cobalt ion chelating precipitating agent is α-nitroso-β-naphthol.

Considering that if the amount of cobalt ion chelating precipitant is too low, the removal rate of cobalt ions in the solution will be low; if the amount of precipitant is too high, it will cause waste of reagents and contaminate the solution. Therefore, in the above step 2, the molar ratio of the added amount of cobalt ion chelating precipitant to the cobalt ions in the solution is controlled to be 3:1 to 10:1, for example, such as 3:1, 4:1, 5:1 , 6:1, 7:1, 8:1, 9:1, 10:1.

Specifically, in the above step 2, the particle stabilizer is a solution containing Fe ³⁺ , which can be an iron sulfate solution and/or a ferric chloride solution.

Specifically, in the above step 2, the principle of stabilizing the cobalt ion chelated precipitation product in the Fe ³⁺ -containing solution is: in view of the low concentration of cobalt ions in the solution, in order to ensure that the cobalt ion chelated precipitation particle size meets the requirements of the flotation process, Taking advantage of the fact that Fe ³⁺ is easily hydrolyzed to form Fe(OH) ₃ floc precipitation, the size of the cobalt ion chelated precipitation particles can be controlled, allowing the finer precipitation particles to grow into particles that meet the flotation requirements.

Considering that if the amount of particle stabilizer is too low, the removal rate of cobalt ions in the solution will be low; if the amount of particle stabilizer is too high, it will cause waste of reagents and contaminate the solution with iron ions. Therefore, the molar ratio of the added amount of particle stabilizer to the cobalt ions in the solution is controlled to be 0.5:1 to 1.5:1, for example, such as 0.5:1, 0.7:1, 0.8:1, 1:1, 1.2:1 , 1.3:1, 1.5:1.

Specifically, in the above step 2, if the stirring speed is too fast, it will be difficult for the particles to aggregate and grow, which will have an adverse effect on subsequent flotation; if the stirring time is too short, chelation precipitation will be insufficient; if the stirring time is too long, the treatment efficiency will be affected. Therefore, the stirring rate is controlled to be less than or equal to 100 rpm, and the stirring time is 10 to 60 min, for example, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min.

Specifically, in the above step 3, the surfactant is one of cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and methyl isobutyl carbinol (MIBC) or Various.

Specifically, in step 3 above, surfactant is used to further regulate particle size and stability. Considering that too much surfactant is added, it will cause surfactant residues in the solution; too little is added, and it will not be able to control the particle size. Therefore, the amount of surfactant added is controlled to be 10 to 100 mg/L, for example, such as 10 mg/L, 15 mg/L, 20 mg/L, 25 mg/L, 30 mg/L, 40 mg/L, 45 mg/L, 50 mg /L, 55mg/L, 60mg/L, 65mg/L, 70mg/L, 80mg/L, 85mg/L, 90mg/L, 95mg/L, 100mg/L.

Specifically, in the above step 3, the stirring and mixing time is 5 to 60 min, for example, such as 5 min, 10 min, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min.

Specifically, in step 3 above, the factors that affect the particle size of suspended particles mainly include the amount of particle stabilizer added, stirring and mixing time, stirring speed, ion concentration, etc.; considering that the particle size of suspended particles is too small, the flotation process It is difficult to be adhered by bubbles and then separated by flotation; the particle size is too large, has large mass and high momentum and is difficult to be taken out by bubbles. Therefore, the particle diameter of suspended particles is controlled to be 20 to 50 μm.

It should be noted that after in-depth research, the inventor found that since the concentration of cobalt ions in the solution is very low, the particles formed are smaller. If the precipitation filtration method is used, the filter cloth will be easily blocked. If the precipitation filtration method is used, large particles need to be formed. Precipitation, the production time is long, and more excess reaction reagents are needed to increase the particle size; the production efficiency is low, the amount of reaction reagents is large, and the economy is poor; therefore, in the above step 4, a flotation separation device is used to carry out the second intermediate system Aerated flotation.

Specifically, in the above step 4, the flotation separation device includes a flotation machine or a flotation column.

Specifically, in the above step 4, the step of air flotation includes: passing the second intermediate system into the flotation separation device, and air flotation; the particles containing cobalt precipitate float up with the bubbles and are enriched in the upper foam layer, and then The foam is discharged and collected.

Alternatively, in the above steps 1-4, the solution containing zinc and cobalt ions is passed into the flotation separation device, and then the pH of the solution containing zinc and cobalt ions is adjusted to acidic; and then steps 2-4 are continued.

Compared with the existing technology, the precipitation method is generally used to separate zinc and cobalt in existing solutions. However, due to the low concentration of cobalt ions in some cases, it is difficult to form larger precipitated particles, and the amount of precipitant must be increased to ensure the formation of precipitates. The particles meet the particle size requirements for filtration separation. The production time is long and more excess reaction reagents are needed to enlarge the particles; the production efficiency is low, the amount of reaction reagents is large, and the economy is poor. In the technical solution of the present invention, the cobalt ion chelating precipitant α-nitroso-β-naphthol is used to selectively chelate cobalt ions in the solution, and the cobalt ions are chelated with cobalt ions by adding a particle stabilizer at the same time. The precipitant forms stable suspended sediment particles, and then microbubble flotation technology is used to achieve flotation separation of cobalt ion chelated sediment particles in the solution, and finally realizes the selective extraction of low-concentration cobalt ions in the solution, thereby achieving efficient separation of zinc in the solution , the purpose of cobalt ions; the method of the present invention uses less reagents, short reaction time, high production efficiency, significant economic benefits, and good zinc and cobalt separation effects.

Example 1

This embodiment provides a method for separating zinc and cobalt by selective precipitation and flotation of cobalt ions in an acidic solution, which includes the following steps:

Add a pH adjuster to a solution containing 0.5g/L zinc ions and 1mg/L cobalt ions to adjust the pH value of the solution to 2.0; control the solution temperature to 30°C and add a cobalt ion chelating precipitant (α- Nitroso-β-naphthol), the molar ratio of the added amount to the cobalt ions in the solution is 3:1, and the particle stabilizer (iron sulfate solution) is added at the same time, the molar ratio of the added amount to the cobalt ions in the solution is 0.5 :1; Stir for 10 minutes at a stirring speed of 50 rpm to obtain a solution containing cobalt ion chelated precipitated particles (first intermediate system); then add 10 mg/L cetyltrimethyl bromide to the mixed solution Ammonium (CTAB) is used as a surfactant, and further stirred evenly to obtain a second intermediate system containing cobalt precipitated suspended particles. The stirring time is 5 minutes; bubbles are bubbled for flotation, and the flotation foam product is dried to obtain a cobalt-rich material. Through the chelation precipitation-flotation process, 85.1% of the cobalt ions in the solution can be recovered by flotation, and the zinc ion flotation recovery rate is 2.1%. The zinc ion content in the obtained cobalt-rich material is 2.1%, and the zinc-cobalt separation effect is good. .

Example 2

Add a pH adjuster to a solution containing 75g/L zinc ions and 1g/L cobalt ions to adjust the pH value of the solution to 2.5; control the solution temperature to 45°C, and add a cobalt ion chelating precipitant (α-substituted ion) to the solution. Nitro-β-naphthol), the molar ratio of the added amount to the cobalt ion in the solution is 5:1, and the particle stabilizer (ferric chloride solution) is added at the same time, the molar ratio of the added amount to the cobalt ion in the solution is 1 :1; Stir for 30 minutes at a stirring speed of 75 rpm to obtain a solution containing cobalt ion chelated precipitated particles (first intermediate system); then add 50 mg/L cetyltrimethyl bromide to the mixed solution Ammonium (CTAB) is used as a surfactant, and further stirred evenly to obtain a second intermediate system containing cobalt precipitated suspended particles. The stirring time is 30 minutes; bubbles are bubbled for flotation, and the flotation foam product is dried to obtain a cobalt-rich material. Through the chelation precipitation-flotation process, 90.8% of the cobalt ions in the solution can be recovered by flotation, and the zinc ion flotation recovery rate is 1.3%. The zinc ion content in the obtained cobalt-rich material is 3.6%, and the zinc-cobalt separation effect is good. .

Example 3

Add a pH adjuster to a solution containing 185g/L zinc ions and 5g/L cobalt ions to adjust the pH value of the solution to 3.5; control the temperature of the solution to 70°C, and add a cobalt ion chelating precipitant (α-substrate) to the solution. Nitro-β-naphthol), the molar ratio of the added amount to the cobalt ions in the solution is 10:1, and the particle stabilizer (mixed solution of ferric sulfate and ferric chloride) is added at the same time, the added amount is equal to the molar ratio of the cobalt ions in the solution The molar ratio is 1.5:1; stir for 60 minutes at a stirring speed of 100 rpm to obtain a solution containing cobalt ion chelated precipitated particles (first intermediate system); then add 100 mg/L hexadecyl to the mixed solution Trimethylammonium bromide (CTAB) is used as a surfactant, and further stirred evenly to obtain a second intermediate system containing cobalt precipitated suspended particles. The stirring time is 60 minutes; bubbles are bubbled for flotation, and the flotation foam product is obtained after drying Cobalt-rich materials. Through the chelation precipitation-flotation process, 97.3% of the cobalt ions in the solution can be recovered by flotation, and the zinc ion flotation recovery rate is 1.6%. The zinc ion content in the obtained cobalt-rich material is 3.9%, and the zinc-cobalt separation effect is good. .

Comparative example 1

This comparative example provides a method for separating zinc and cobalt ions, using the xanthate direct precipitation method to treat the same solution containing zinc and cobalt ions as in Example 1. The molar ratio of the added amount of chemical reagents to the cobalt ions in the solution is 13:1; the precipitation treatment time is 3-5h; 87.5% of the cobalt ions in the solution can be precipitated and recovered, and the zinc ion precipitation rate is 8.5%, obtaining The zinc ion content in the cobalt-rich material is 10.8%. The reaction time of this comparative example is long, the efficiency is low, the cobalt recovery rate is low, and the zinc-cobalt separation effect is poor.

In the technical solution of the present invention, a cobalt ion chelating precipitant (α-nitroso-β-naphthol) is used to selectively chelate cobalt ions in the solution, and a particle stabilizer is added at the same time to make the cobalt ions and cobalt ions The chelating precipitant forms stable suspended precipitated particles, and then microbubble flotation technology is used to achieve flotation separation of cobalt ion chelated precipitated particles in the solution. Finally, the selective extraction of low-concentration cobalt ions in the solution is achieved, thereby achieving efficient solution separation. The purpose of zinc and cobalt ions. The method of the invention uses less reagents, has short reaction time, high production efficiency, significant economic benefits, and good zinc-cobalt separation effect.

The above are only preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of changes or modifications within the technical scope disclosed in the present invention. All substitutions are within the scope of the present invention.

Claims (8)

1. A zinc-cobalt separation method using selective precipitation and flotation of low-concentration cobalt ions in an acidic solution, which is characterized by including: Step 1. Use a pH adjuster to adjust the pH of the solution containing zinc and cobalt ions to 2.0~2.5; Step 2: At a certain temperature, simultaneously add cobalt ion chelating precipitant and particle stabilizer to the above solution, stir and mix, and obtain a first intermediate system containing cobalt ion chelating suspended particles; Step 3: Add surfactant to the first intermediate system and stir and mix evenly to obtain a second intermediate system containing cobalt precipitated suspended particles; Step 4: Use a flotation separation device to perform air flotation on the above-mentioned second intermediate system to collect particles containing cobalt precipitates; In the step 1, in the solution containing zinc and cobalt ions, the concentration of zinc ions is 0.5~185g/L, and the concentration of cobalt ions is 1mg/L~10mg/L; In step 1, the pH is adjusted to 2.0~2.5 to avoid hydrolysis and precipitation of zinc ions in subsequent steps; In the step 2, the cobalt ion chelating precipitating agent is α-nitroso-β-naphthol; the molar ratio of the added amount of cobalt ion chelating precipitating agent to the cobalt ions in the solution is 3:1~10:1; The particle stabilizer is a solution containing Fe ³⁺ ; the molar ratio of the added amount of the particle stabilizer to the cobalt ions in the solution is 0.5:1~1.5:1; In the step 2, the stirring rate is less than or equal to 100rpm, and the stirring time is 10~60min; In the step 3, the surfactant is cetyltrimethylammonium bromide. The surfactant is used to further regulate the particle size and stability. The amount of surfactant added is 10~100mg/L; In step 3, the particle diameter of the suspended particles is 20~50 μm. 2. The zinc-cobalt separation method according to claim 1, characterized in that in step 1, in the solution containing zinc and cobalt ions, the concentration of zinc ions is 0.5~170g/L. 3. The zinc-cobalt separation method according to claim 1, characterized in that in step 1, the pH of the adjusted solution is 2.0~2.2. 4. The zinc-cobalt separation method according to claim 1, characterized in that in step 1, the pH adjuster is an inorganic acid or alkali. 5. The zinc-cobalt separation method according to claim 1, characterized in that in step 2, the temperature is 30~70°C. 6. The zinc-cobalt separation method according to claim 1, characterized in that in step 2, the molar ratio of the added amount of cobalt ion chelating precipitant to the cobalt ions in the solution is 3:1~9:1. 7. The zinc-cobalt separation method according to claim 1, wherein in step 2, the molar ratio of the added amount of particle stabilizer to the cobalt ions in the solution is 0.5:1~1:1. 8. The method for separating zinc and cobalt according to any one of claims 1 to 7, characterized in that in step 2, the stirring time is 10 to 55 minutes.