阅读说明：本技术 一种湿法炼锌中上清液深度净化除镉钴的方法 (Method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy ) 是由 袁武 张鸿烈 杨斌 段宏志 胡伟 杜虎忠 马菲菲 江建新 崔耀 于 2019-08-23 设计创作，主要内容包括：本发明的目的是提供一种湿法炼锌中上清液深度净化除镉钴的方法,包括：一段净化除铜镉、二段净化除镉、三段净化除镉、钴和四段冷却沉降。本发明的方法优异的深度除镉钴效率,由于反应温度较常规工艺低,因此蒸汽消耗量少,成本低,净化剂用量少、利用率高、成本低廉,反应过程稳定性好,不会出现镉、钴杂质复溶现象,产生的钴渣渣量少,钴含量较高,对后续资源化利用十分有利,净化过程中锌粉单耗显著下降,不产生二次污染。(The invention aims to provide a method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy, which comprises the following steps: first-stage purification for removing copper and cadmium, second-stage purification for removing cadmium, third-stage purification for removing cadmium and cobalt, and fourth-stage cooling and settling. The method has excellent deep cadmium and cobalt removal efficiency, and has the advantages of low steam consumption, low cost, low purifying agent consumption, high utilization rate, low cost, good stability in the reaction process, no re-dissolution of cadmium and cobalt impurities, low cobalt slag amount, high cobalt content, contribution to subsequent resource utilization, obvious reduction of zinc powder consumption in the purification process and no secondary pollution because of low reaction temperature compared with the conventional process.)

1. A method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy is characterized by comprising the following steps:

(1) first-stage purification for removing copper and cadmium:

pumping supernatant in zinc hydrometallurgy into a first-stage purification tank, adding zinc powder for reaction, carrying out solid-liquid separation on ore pulp after the reaction is finished, wherein filter residues are copper-cadmium residues, filtrate is first-stage purification filtrate, and measuring the content of Cd in the first-stage purification filtrate, wherein the control index of the first-stage purification filtrate is that Cd is less than or equal to 100 mg/L;

(2) second-stage purification and cadmium removal:

pumping the first-stage purification filtrate into a second-stage purification tank, adding zinc powder for reaction, carrying out solid-liquid separation on the ore pulp after the reaction is finished, wherein filter residues are cadmium residues, the filtrate is second-stage purification filtrate, measuring the content of Co and Cd in the second-stage purification filtrate, and controlling the index of the second-stage purification filtrate to be less than or equal to 20 mg/L;

(3) three-stage purification and cadmium and cobalt removal:

heating the second-stage purification filtrate to 70-85 ℃, then feeding the second-stage purification filtrate into a third-stage purification tank, stirring for reaction, and calculating the using amount of a purifying agent according to the content of Cd in the second-stage purification filtrate measured in the step (2):

cleaning agent dosage per hour = (Co)²⁺/59+Cd²⁺/112)×C₁×R₁×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; cd [ Cd ]²⁺: cadmium content (mg/L) in the second-stage purification filtrate; c₁: relative atomic mass of scavenger; r₁: reaction coefficient, R is not less than 2₁Less than or equal to 8; l: purifying the driving flow in three stages;

calculating the dosage of the activating agent according to the content of Co in the purified filtrate determined in the step (2):

activator dosage per hour = Co²⁺/59×C₂×R₂×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; c₂: activator relative molecular mass; r₂: coefficient, R is not less than 0.5₂Less than or equal to 2; l: purifying the driving flow in three stages;

adding a purifying agent and an activating agent into industrial water to prepare a solution with the concentration of 10-30%, uniformly adding the solution into three sections of purifying tanks for reaction, carrying out solid-liquid separation on the ore pulp after the reaction is finished, wherein filter residues are cobalt residues, filtrate is three sections of filtrate, the control indexes of the three sections of filtrate are that Cd is less than or equal to 0.5mg/L and Co is less than or equal to 0.5mg/L, and the contents of other metal ions meet the zinc electrodeposition requirement;

(4) cooling and settling in four sections:

cooling the filtrate to 60-70 deg.C, and pumping into thickener to obtain supernatant as new liquid.

2. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 1, wherein: controlling the acidity of the reaction in the step (1) to be 4.5-5.5, controlling the reaction temperature to be 60-70 ℃, carrying out zinc powder addition at 0.5-5.0kg/m and stirring at 76-85 r/min, and carrying out topdressing for 1.5-2.0 h.

3. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 1 or 2, wherein: and (3) controlling the acidity pH of the reaction in the step (2) to be 4.5-5.5, controlling the reaction temperature to be 60-70 ℃, and carrying out zinc powder loading on the high-purity medium-purity high-purity zinc powder.

4. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 3, wherein: and (3) controlling the rotation speed of the stirring reaction at 76-85 r/min, controlling the reaction temperature at 70-85 ℃ and controlling the reaction time for 1.0-1.5 h.

5. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 4, wherein: in the step (3), the purifying agent is an alkali metal thiocarbamate with different carbon chain substituents.

6. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 5, wherein: the purifying agent in the step (3) is sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium diethyldithiocarbamate or zinc diethyldithiocarbamate.

7. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 6, wherein: the purifying agent in the step (3) is sodium dimethyldithiocarbamate.

8. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 7, wherein: in the step (3), the activating agent is an alkali metal nitrite.

9. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 8, wherein: in the step (3), the activating agent is one or a mixture of sodium nitrite and potassium nitrite.

10. The method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy as claimed in claim 9, wherein: and (4) the activating agent in the step (3) is sodium nitrite.

Technical Field

The invention belongs to the technical field of supernatant purification in the zinc hydrometallurgy industry, and particularly relates to a method for deeply purifying and removing cadmium and cobalt from the supernatant in the zinc hydrometallurgy.

Background

At present, in the domestic and foreign zinc hydrometallurgy industry, the processes for purifying and removing cadmium and cobalt from the supernatant mainly comprise a zinc powder replacement (adding agent) method, a beta-naphthol purification method and a xanthate purification method, wherein the zinc powder replacement (adding antimonate) method is the most commonly applied process for removing cadmium and cobalt at present, but the impurity content in the zinc concentrate sold in the market is higher and higher, the traditional purification method is difficult to realize the deep purification of cadmium and cobalt impurities in the process of purifying the supernatant, and the production cost is high.

Purification is an important step between leaching and electrolysis in a hydrometallurgical zinc process. Most smelting plants at home and abroad commonly adopt a zinc powder replacement (antimony salt adding) purification process, one section of the process is used for removing copper and cadmium at a low temperature (50-60 ℃), the other section of the process is used for removing cobalt and nickel at a high temperature (more than 80 ℃) and the other section of the process is used for removing residual cadmium at a medium temperature (60-70 ℃), the process needs to keep a higher temperature and add excessive zinc powder in the reaction process so as to improve the purification depth and the purification efficiency, but when the cobalt content of the middle-upper clear liquid is higher (more than 40 mg/L), the defects of high zinc powder consumption, poor process stability, high production cost, additional impurity antimony, difficulty in realizing deep cobalt removal, need of subsequent treatment of residual cadmium, poor working environment and the like exist, and in the purification process, virulent AsH can be generated₃Gas, which is extremely harmful to the body of the operator.

In order to solve the problem of cobalt removal of zinc sulfate solution in zinc hydrometallurgy, patent CN102839284B proposes a process for removing cadmium and cobalt from high cobalt zinc sulfate solution, wherein zinc powder is adopted for removing cadmium and cobalt, and the zinc powder is high in consumption and cost. Application number 201610148339.5 proposes a patent of adding manganese-based alloy powder containing 90% of manganese metal into a zinc sulfate solution to remove impurities such as copper, cadmium, cobalt, nickel and the like in the zinc sulfate solution in one step; CN106893872B proposes a three-stage purification process, and the used purifying agent is alloy powder containing 30-49% of manganese. The zinc electrolysis efficiency can be influenced by a large amount of manganese ions entering a zinc sulfate solution system. In patent CN105483376A, cobalt remover A is prepared from glycine, cobalt remover B is prepared from sodium nitrite, and the mixture of cobalt remover A and cobalt remover B is used as cobalt remover, the concentration of sodium nitrite added in the method is 2-4 times of that of cobalt and iron, so that nitrate ions in the system are accumulated, and the anode plate of the main system is corroded.

Disclosure of Invention

The invention aims to provide a method for deeply purifying supernatant in zinc hydrometallurgy to remove cadmium and cobalt, which aims to solve the problems of high zinc powder consumption, unstable system, frequent cadmium and cobalt redissolution, difficult filtration, high production cost, poor production environment and the like in the process of deeply purifying the cadmium and cobalt in the supernatant.

In order to achieve the purpose, the invention adopts the technical scheme that:

a method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy comprises the following steps:

(1) first-stage purification for removing copper and cadmium: the main purpose is to remove most of copper and cadmium in the supernatant by using a zinc powder replacement principle to obtain copper-cadmium slag;

pumping supernatant in zinc hydrometallurgy into a first-stage purification tank, adding zinc powder for reaction, carrying out solid-liquid separation on ore pulp after the reaction is finished, wherein filter residues are copper-cadmium residues, filtrate is first-stage purification filtrate, and measuring the content of Cd in the first-stage purification filtrate, wherein the control index of the first-stage purification filtrate is that Cd is less than or equal to 100 mg/L;

(2) second-stage purification and cadmium removal: cadmium is further removed by utilizing a zinc powder replacement principle to obtain cadmium slag;

pumping the first-stage purification filtrate into a second-stage purification tank, adding zinc powder for reaction, carrying out solid-liquid separation on the ore pulp after the reaction is finished, wherein filter residues are cadmium residues, the filtrate is second-stage purification filtrate, measuring the content of Co and Cd in the second-stage purification filtrate, and controlling the index of the second-stage purification filtrate to be less than or equal to 20 mg/L;

(3) three-stage purification and cadmium and cobalt removal: the purifying agent and the activating agent are used for realizing the deep purification of cadmium and cobalt, so that the redissolution of cadmium and cobalt is avoided, and the defects of large zinc powder consumption, low utilization rate, large slag amount, difficult filtration, high labor intensity and the like in the deep cadmium and cobalt removal of the alloy zinc powder are avoided;

heating the second-stage purification filtrate to 70-85 ℃, then feeding the second-stage purification filtrate into a third-stage purification tank, stirring for reaction, and calculating the using amount of a purifying agent according to the content of Cd in the second-stage purification filtrate measured in the step (2): the temperature is lower than the temperature requirement of the conventional process, and the steam consumption is low;

cleaning agent dosage per hour = (Co)²⁺/59+Cd²⁺/112)×C₁×R₁×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; cd [ Cd ]²⁺: cadmium content (mg/L) in the second-stage purification filtrate; c₁: relative atomic mass of scavenger; r₁: reaction coefficient, R is not less than 2₁Less than or equal to 8; l: purifying the driving flow in three stages; the purifying agent adopted by the invention is a broad-spectrum heavy metal precipitator, can react with various heavy metal ions (such as copper, cadmium, cobalt, nickel, zinc and the like) in the zinc sulfate solution to generate chelate salt precipitate, can deeply remove other impurities such as residual copper, nickel and the like in the solution while deeply removing cadmium and cobalt, and obviously improves the impurity removal effect of the zinc sulfate solution;

calculating the dosage of the activating agent according to the content of Co in the purified filtrate determined in the step (2):

activator dosage per hour = Co²⁺/59×C₂×R₂×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; c₂: activator relative molecular mass; r₂: coefficient, R is not less than 0.5₂Less than or equal to 2; l: purifying the driving flow in three stages; the activator adopted by the invention can form a cobalt complex with cobalt ions, so that divalent cobalt ions are oxidized into trivalent cobalt ions, the trivalent cobalt ions and the purifying agent form a chelate precipitate with smaller solubility product and more stability, the deep separation of the cobalt ions is realized, and the cobalt content can be reduced to below 0.3mg/L from 50-90mg/L so as to meet the electrolysis requirements of 24h and 48 h;

adding a purifying agent and an activating agent into industrial water to prepare a solution with the concentration of 10-30%, uniformly adding the solution into three sections of purifying tanks for reaction, carrying out solid-liquid separation on the ore pulp after the reaction is finished, wherein filter residues are cobalt residues, filtrate is three sections of filtrate, the control indexes of the three sections of filtrate are that Cd is less than or equal to 0.5mg/L and Co is less than or equal to 0.5mg/L, and the contents of other metal ions meet the zinc electrodeposition requirement;

(4) cooling and settling in four sections: the three-stage purified filtrate is cooled and settled, so that the influence of excessive reagent on a subsequent electrolysis system is avoided;

cooling the filtrate to 60-70 deg.C, and pumping into thickener to obtain supernatant as new liquid.

In order to further realize the method, the acidity of the reaction in the step (1) is controlled to be pH4.5-5.5, the reaction temperature is controlled to be 60-70 ℃, the adding amount of zinc powder is 0.5-5kg/m for carrying out thin film plantation, the stirring speed is 76-85 r/min, and the reaction time is 1.5-2 h.

In order to further realize the method, the acidity pH value of the reaction in the step (2) is 4.5-5.5, the reaction temperature is controlled at 60-70 ℃, the adding amount of zinc powder is 0.5-2.0kg/m for carrying out the thin film zinc ingot plantation, the stirring speed is 76-85 r/min, and the reaction time is 1.0-1.5 h.

In order to further realize the invention, the rotating speed of the stirring reaction in the step (3) is controlled at 76-85 r/min, the reaction temperature is controlled at 70-85 ℃, and the reaction time is controlled for 1-1.5 h.

In order to further realize the present invention, the scavenger in the step (3) is an alkali metal thiocarbamate of different carbon chain substituents.

In order to further realize the present invention, the scavenger in the step (3) is sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium diethyldithiocarbamate or zinc diethyldithiocarbamate.

In order to further realize the invention, the purifying agent in the step (3) is sodium dimethyldithiocarbamate.

In order to further realize the present invention, the activator in the step (3) is an alkali metal nitrite.

In order to further realize the invention, the activating agent in the step (3) is one or a mixture of two of sodium nitrite and potassium nitrite.

In order to further realize the present invention, the activating agent in the step (3) is sodium nitrite.

Compared with the prior art, the invention has the beneficial effects that:

the method has excellent deep cadmium and cobalt removal efficiency, and has the advantages of low steam consumption, low cost, low purifying agent consumption, high utilization rate, low cost, good stability in the reaction process, no re-dissolution of cadmium and cobalt impurities, low cobalt slag amount, high cobalt content, contribution to subsequent resource utilization, obvious reduction of zinc powder consumption in the purification process and no secondary pollution because of low reaction temperature compared with the conventional process.

Detailed Description

The present invention will be further described with reference to the following embodiments.

A method for deep purification and cadmium and cobalt removal of supernatant in zinc hydrometallurgy comprises the following steps:

(1) first-stage purification for removing copper and cadmium:

pumping supernatant in zinc hydrometallurgy into a first-stage purification tank, adding zinc powder to react, controlling the acidity of the reaction to be 4.5-5.5, controlling the reaction temperature to be 60-70 ℃, controlling the adding amount of the zinc powder to be 0.5-5kg/m, carrying out topdressing at the stirring speed of 76-85 r/min, controlling the reaction time to be 1.5-2h, carrying out solid-liquid separation on ore pulp after the reaction is finished, wherein filter residues are copper-cadmium residues, filtrate is first-stage purification filtrate, determining the content of Cd in the first-stage purification filtrate, and the control index of Cd of the first-stage purification filtrate is less than or equal to 100 mg/L;

(2) second-stage purification and cadmium removal:

pumping the first-stage purification filtrate into a second-stage purification tank, adding zinc powder to react, controlling the acidity pH of the reaction to be 4.5-5.5, controlling the reaction temperature to be 60-70 ℃, controlling the adding amount of the zinc powder to be 0.5-2.0kg/m, carrying out stirring at a rotating speed of 76-85 r/min, controlling the reaction time to be 1.0-1.5h, carrying out solid-liquid separation on ore pulp after the reaction is finished, wherein filter residues are cadmium residues, the filtrate is second-stage purification filtrate, determining the content of Co and Cd in the second-stage purification filtrate, and controlling the index of the second-stage purification filtrate to be less than or equal to 20 mg/L;

(3) three-stage purification and cadmium and cobalt removal:

heating the second-stage purification filtrate to 70-85 ℃, then feeding the second-stage purification filtrate into a third-stage purification tank, carrying out stirring reaction, controlling the rotation speed of the stirring reaction at 76-85 revolutions/min, controlling the reaction temperature at 70-85 ℃, controlling the reaction time for 1-1.5h, and calculating the using amount of a purifying agent according to the content of Cd in the second-stage purification filtrate determined in the step (2):

cleaning agent dosage per hour = (Co)²⁺/59+Cd²⁺/112)×C₁×R₁×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; cd [ Cd ]²⁺: cadmium content (mg/L) in the second-stage purification filtrate; c₁: relative atomic mass of scavenger; r₁: reaction coefficient, R is not less than 2₁Less than or equal to 8; l: purifying the driving flow in three stages;

calculating the dosage of the activating agent according to the content of Co in the purified filtrate determined in the step (2):

activator dosage per hour = Co²⁺/59×C₂×R₂×L；

Wherein, Co²⁺: cobalt content (mg/L) in the second-stage purification filtrate; c₂: activator relative molecular mass; r₂: coefficient, R is not less than 0.5₂Less than or equal to 2; l: purifying the driving flow in three stages;

adding a purifying agent and an activating agent into industrial water to prepare a solution with the concentration of 10-30%, uniformly adding the solution into three sections of purifying tanks for reaction, carrying out solid-liquid separation on the ore pulp after the reaction is finished, wherein filter residues are cobalt residues, filtrate is three sections of filtrate, the control indexes of the three sections of filtrate are that Cd is less than or equal to 0.5mg/L and Co is less than or equal to 0.5mg/L, and the contents of other metal ions meet the zinc electrodeposition requirement;

(4) cooling and settling in four sections:

cooling the filtrate to 60-70 deg.C, and pumping into thickener to obtain supernatant as new liquid.

The purifying agent in the step (3) is an alkali metal thiocarbamate with different carbon chain substituents, and sodium dimethyldithiocarbamate, potassium dimethyldithiocarbamate, zinc dimethyldithiocarbamate, sodium diethyldithiocarbamate, potassium diethyldithiocarbamate or zinc diethyldithiocarbamate is adopted, and preferably sodium dimethyldithiocarbamate is adopted.

In the step (3), the activating agent is alkali metal nitrite, and adopts one or a mixture of two of sodium nitrite and potassium nitrite, preferably sodium nitrite.