CN112030003A - Method for simultaneously removing multiple impurity ions in wet-process zinc smelting waste electrolyte - Google Patents

Abstract

The invention relates to a method for simultaneously removing various impurity ions in wet-process zinc smelting waste electrolyte, belonging to the field of non-ferrous metallurgy. Precooling the wet-process zinc smelting waste electrolyte through a heat exchanger, adding the precooled solution into an impurity removal reaction kettle with a stirring device for heat exchange and cooling to-15-0 ℃, adding seed crystals in the cooling process, reacting for 20-60 min, precipitating and separating out impurity components such as lead, calcium, silicon, fluorine, antimony and the like in the solution in the form of solid crystallization products, and quickly separating the solid products containing the impurity components after the reaction is finished to obtain the electrolyte after the impurity removal. The method is characterized in that on the premise of not changing the main components of the waste electrolyte of zinc hydrometallurgy, impurities such as lead, calcium, silicon, fluorine, antimony and the like are directly separated from the waste electrolyte containing high-concentration sulfuric acid, the electrolyte after impurity removal meets the requirement of zinc electrolytic deposition on impurity concentration, and the method has the advantages of short process flow, simplicity in operation, low reagent consumption, high impurity ion removal efficiency and the like.

Description

A kind of method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting

technical field

The invention relates to a method for simultaneously removing various impurity ions in waste electrolyte of zinc smelting by wet method, and belongs to the technical field of non-ferrous metal metallurgy.

Background technique

At present, about 80% of zinc is produced by the hydrometallurgical process. In the zinc electrodeposition process, the high concentration of impurity ions in the electrolyte will have a great adverse effect on the current efficiency, power loss and the quality of the deposited zinc. . There are many impurity ions in the electrolytic solution of zinc hydrometallurgy, among which the common impurity ions such as copper, cadmium, nickel and cobalt are removed by the method of zinc powder replacement purification before the zinc electrolysis process, but lead, calcium, silicon, fluorine, antimony, etc. The impurity ions are enriched with the recycling of the waste electrolyte, which makes it difficult to remove these impurity ions in the electrolyte, which brings great harm to the electro-deposition of zinc by hydrometallurgy.

In the electrolysis process of zinc hydrometallurgy, lead-silver alloys are widely used as anodes. Although a dense PbO ₂ protective film and a manganese dioxide covering layer are formed on the surface of the anode during the zinc electrolysis process, the corrosion of the anode and the dissolution reaction of lead during production It is still unavoidable, especially when the manganese dioxide coating is damaged or becomes loose, the corrosion rate of the lead-silver anode is accelerated, and the lead concentration in the electrolyte increases (in severe cases, the lead concentration in the electrolyte is higher than 5mg/L), Cause the lead content in the cathode zinc exceeds the standard. Since the standard reduction potential of lead is much higher than that of zinc, even when the concentration of lead in the electrolyte is extremely low, lead will precipitate on the cathode in preference to zinc, polluting the precipitated cathode zinc product.

Calcium in the electrolytic solution of zinc hydrometallurgy will combine with sulfate to form calcium sulfate adsorbed on the surface of the anode plate, increasing the anode resistance and increasing the power consumption. During the leaching process of zinc hydrometallurgy, the silicon in the zinc calcine forms soluble silicon and enters the leaching solution. Although part of the soluble silicon can be hydrolyzed and removed during the purification process, a small amount of soluble silicon remaining in the purification solution is mixed with zinc sulfate. After entering the electrolysis process, due to the change of process conditions such as the increase of sulfuric acid concentration in the solution and the decrease of temperature, these soluble silicon are converted into viscous micelles such as silica gel, which are adsorbed on the surface of the cathode zinc, which not only affects the quality of zinc products, but also affects the quality of zinc products. It hinders the further deposition and precipitation of zinc ions, reduces the current efficiency, and increases the energy consumption of electrolysis.

If the concentration of fluorine in the electrolyte is too high, the aluminum oxide film on the surface of the cathode aluminum plate will be destroyed, so that the precipitated zinc and the fresh surface of the aluminum plate will form a zinc-aluminum alloy, which will make it difficult to peel off the zinc sheet. In industrial production, it is necessary to control the fluoride ion concentration in the electrolyte not to exceed 80 mg/L. Antimony is one of the most harmful impurity elements in the zinc electrolytic deposition process. The excessive antimony concentration in the electrolyte causes the precipitated zinc to redissolve. In order to ensure the normal zinc electrolysis process, hydrometallurgical zinc smelting enterprises usually require the antimony concentration in the electrolyte to be less than 0.3 mg/L.

Due to the high concentration of sulfuric acid in the waste electrolyte (up to 150-180g/L), it is impossible to directly use zinc powder for purification to remove impurities such as lead, calcium, silicon, fluorine, and antimony. In addition, since the zinc electrolysis workshop adopts the waste electrolyte circulating liquid distribution system, that is, most of the waste electrolyte produced by zinc electrolysis is cooled by the cooling tower, and then returned to the liquid distribution tank and mixed with the new liquid in proportion, and then supplied to each electrolytic cell for electrolysis again. The cyclic accumulation of impurity ions is inevitable during such a cycle. In the production, the open circuit part of the waste electrolyte is usually used, and the method of adding lime for neutralization realizes the removal of impurity ions. However, the use of waste electrolyte lime neutralization method produces a large amount of heavy metal-containing gypsum slag and acid waste water. The output of waste slag and waste water is large and the cost is high, which is not enough for the current hydrometallurgical zinc smelting plant to remove impurities from waste electrolyte. ionic demand. Therefore, the development of a new and efficient method for removing impurities from the waste electrolyte of zinc hydrometallurgy has become a common problem faced by the zinc smelting industry.

SUMMARY OF THE INVENTION

In order to overcome the deficiencies of the prior art, the present invention provides a method for simultaneously removing various impurity ions in the waste electrolyte of zinc smelting by the wet process. The invention realizes simultaneous and rapid removal of various impurity ions in the waste electrolyte of wet zinc smelting through the combination of cooling treatment and the entry of crystal seeds under the synergistic effect of special conditions and parameters.

A method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to the present invention comprises the following steps:

The waste electrolyte produced in the electrolytic process of zinc hydrometallurgy is used as the treatment object; the temperature of the treatment object is lowered to -15 to 0 ° C; then crystal seeds are introduced, and after the reaction for at least 15 minutes, the solid-liquid separation is carried out; the electrolysis for removing impurity ions is obtained liquid; the impurity ions include at least two of lead, calcium, silicon, fluorine and antimony;

or

The waste electrolyte produced in the electrolytic process of zinc hydrometallurgy is taken as the treatment object; the treatment object is cooled to -15-0° C.; crystal seeds are introduced during the cooling process, and the solid-liquid separation is carried out after the reaction for at least 15 minutes; the impurity removal is obtained. ionic electrolyte; the impurity ions include at least two of lead, calcium, silicon, fluorine, and antimony;

The seed crystal is calcium sulfate or hydrated calcium sulfate.

As a preferred solution, the present invention provides a method for simultaneously removing various impurity ions in the waste electrolyte of zinc hydrometallurgy, wherein the concentration of sulfuric acid in the waste electrolyte produced by the electrolysis process of zinc hydrometallurgy is 150-180 g/L .

As a preferred version, a method for simultaneously removing multiple impurity ions in the waste electrolyte of wet zinc smelting of the present invention comprises the following steps:

(1) Pre-cooling by heat exchange: the waste electrolyte with a temperature of 35 to 40 °C and a concentration of sulfuric acid of 150 to 180 g/L produced in the electrolytic process of zinc hydrometallurgy is pumped into a tubular heat exchanger, and cooled by a carrier. The temperature of the waste electrolyte is pre-cooled to 5-20 ℃, and the pre-cooling liquid is obtained;

(2) crystallization and impurity removal: the pre-cooling liquid produced in step (1) is pumped into the impurity removal reactor with stirring device, and the heat exchanger is used to continue heat exchange and cooling by the carrier refrigerant, and the solution temperature is reduced to -15 ～0℃, add 1～5g/L of crystal seeds during the cooling process, and react for 20～60min to obtain a solution containing a solid crystalline product;

(3) solid-liquid separation: the solution containing the solid crystalline product obtained in step (2) is subjected to rapid solid-liquid separation to obtain an electrolyte that removes impurity ions, and this electrolyte is returned to the hydrometallurgical zinc electrolysis process for recycling. The impurity ions are selected from at least 3 kinds of lead, calcium, silicon, fluorine and antimony.

As a further preferred solution, the present invention is a method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting, and the refrigerant used in the steps (1) and (2) is a temperature of -30 Calcium chloride solution at ~-15°C.

As a preferred solution, the present invention provides a method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting, wherein the crystal seed added in step (2) is calcium sulfate dihydrate.

As a preferred solution, the present invention provides a method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting, wherein the stirring speed of the stirring device used in the step (2) is 30-100 rpm.

As a preferred solution, the present invention provides a method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting, wherein the rapid solid-liquid separation device in the step (3) is a scraper discharge centrifuge.

The present invention is a method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting. In the obtained electrolyte after removing impurities, the concentration of lead ions is less than or equal to 3.1 mg/L, and can be less than or equal to 2.1 mg/L after optimization. L, calcium ion concentration is less than or equal to 76mg/L, optimized to be less than or equal to 65mg/L, further optimized to be less than or equal to 32mg/L, silica concentration less than or equal to 92mg/L, optimized to be less than or equal to 78mg/L, Further optimization can be less than or equal to 75.7mg/L, fluoride ion concentration is less than or equal to 80mg/L, after optimization, it can be less than or equal to 75mg/L, after further optimization, it can be less than or equal to 72mg/L, antimony ion concentration is less than or equal to 0.12mg/L, optimized It can be less than or equal to 0.11 mg/L, and can be less than or equal to 0.1 mg/L after further optimization.

The beneficial effects of the present invention are:

(1) Under the premise of not changing the main components of the zinc hydrometallurgical waste electrolyte, the impurity components such as lead, calcium, silicon, fluorine and antimony are simultaneously and directly separated from the waste electrolyte containing high-concentration sulfuric acid, and the impurity components are removed. The resulting electrolyte meets the requirements of the impurity concentration of zinc electrolytic deposition, and can be returned to the electrolytic process of zinc hydrometallurgy for recycling. It has the advantages of short process flow, simple operation, and high removal efficiency of impurity ions.

(2) The process of removing impurity ions such as lead, calcium, silicon, fluorine and antimony does not need to add neutralizers such as lime to carry out neutralization reaction, nor does it need to add zinc powder to carry out replacement purification. The separation of impurities such as lead, calcium, silicon, fluorine and antimony in the waste electrolyte is directly achieved by physical methods, which has the advantages of less reagent consumption, less intermediate waste output, and clean and environmentally friendly process.

(3) this method utilizes calcium sulfate or hydrated calcium sulfate (preferably calcium sulfate dihydrate) as crystal seed, accelerates the carrying out of various ion impurity removal reactions and strengthens the removal of impurity ions, has fast reaction speed, and removes impurity ions The advantage of high efficiency.

Description of drawings

Fig. 1 is the process flow diagram of the present invention.

Detailed ways

The present invention will be further described below in conjunction with specific embodiments.

Example 1

A method for removing impurity ions in the waste electrolyte of wet zinc smelting, the concrete steps of which are as follows:

(1) Pre-cooling by heat exchange: take the waste electrolyte from the zinc electrolysis process of the wet zinc smelting factory, and the physicochemical properties of the electrolyte are: temperature 40°C, sulfuric acid concentration 180g/L, zinc ion concentration 45g/L, Lead ion concentration 9.2mg/L, calcium ion concentration 45mg/L, silica concentration 120mg/L, fluoride ion concentration 110mg/L, antimony ion concentration 0.3mg/L. The waste electrolyte is pumped into the tubular heat exchanger at a flow rate of 1m ³ /h, and the calcium chloride solution with a temperature of -15°C is used as the refrigerant for heat exchange. The waste electrolyte of the heat exchanger is pre-cooled to the outlet temperature. At 20°C, a pre-cooling liquid was obtained.

(2) crystallization and impurity removal: the precooling liquid produced in step (1) is pumped into the impurity removal reactor with stirring device at a flow rate of 1 m ³ /h, and the control stirring speed is 30 rpm, and a coil tube heat exchanger is adopted, The temperature of the calcium chloride solution at a temperature of -30°C is used as the cooling agent to continue heat exchange and cooling, and the temperature of the solution is reduced to -20°C. During the cooling process, 1g/L calcium sulfate dihydrate crystal seeds are added, and the reaction is performed for 20min to obtain solids containing solids. solution of the crystalline product.

(3) solid-liquid separation: the solution containing the solid crystalline product obtained in step (2) adopts a scraper discharge centrifuge to carry out rapid solid-liquid separation under the condition that the rotating drum speed is 1200 rpm, to obtain the electrolyte after removing impurities The main chemical components are analyzed and tested as follows: sulfuric acid concentration 199.7g/L, zinc ion concentration 25g/L, lead ion concentration 2.1mg/L, calcium ion concentration 32mg/L, silica concentration 75.7mg/L, fluoride ion concentration 75mg/L, antimony ion concentration 0.1mg/L.

The electrolyte after removing impurities is returned to the electrolytic process of hydrometallurgy zinc for recycling.

Example 2

A method for removing impurity ions in the waste electrolyte of wet zinc smelting, the concrete steps of which are as follows:

(1) Pre-cooling by heat exchange: take the waste electrolyte from the zinc electrolysis process of the wet zinc smelting factory, and the physicochemical properties of the electrolyte are: temperature 38°C, sulfuric acid concentration 170g/L, zinc ion concentration 46g/L, Lead ion concentration 7.5mg/L, calcium ion concentration 82mg/L, silica concentration 110mg/L, fluoride ion concentration 152mg/L, antimony ion concentration 0.36mg/L. The waste electrolyte was pumped into the tubular heat exchanger at a flow rate of 1m ³ /h, and the calcium chloride solution with a temperature of -20°C was used as the refrigerant for heat exchange. The waste electrolyte of the heat exchanger was pre-cooled at the outlet temperature. At 10°C, a pre-cooling liquid was obtained.

(2) crystallization and impurity removal: the precooling liquid produced in step (1) is pumped into the impurity removal reactor with stirring device at a flow rate of 1 m ³ /h, and the control stirring speed is 60 rpm, and a coil heat exchanger is adopted, The temperature of the solution was lowered to -10°C by continuing heat exchange and cooling with a calcium chloride solution refrigerant at a temperature of -20°C. During the cooling process, 3g/L calcium sulfate dihydrate crystal seeds were added, and the reaction was carried out for 30min to obtain a solid-containing crystalline product. The solution.

(3) solid-liquid separation: the solution containing the solid crystalline product obtained in step (2) adopts a scraper discharge centrifuge to carry out rapid solid-liquid separation under the condition that the rotating drum speed is 1000 rpm, to obtain the electrolyte after removing impurities The main chemical components are analyzed and tested as follows: sulfuric acid concentration 175g/L, zinc ion concentration 32g/L, lead ion concentration 2.1mg/L, calcium ion concentration 65mg/L, silica concentration 78mg/L, fluoride ion concentration 80mg/L L, antimony ion concentration 0.11mg/L.

The electrolyte solution after the impurity removal is returned to the electrolytic process of hydrometallurgy zinc for recycling.

Example 3

A method for removing impurity ions in the waste electrolyte of wet zinc smelting, the concrete steps of which are as follows:

(1) Pre-cooling by heat exchange: take the waste electrolyte from the zinc electrolysis process of the wet zinc smelting factory, and the physicochemical properties of the electrolyte are: temperature 37°C, sulfuric acid concentration 150g/L, zinc ion concentration 50g/L, Lead ion concentration 6.3mg/L, calcium ion concentration 95mg/L, silica concentration 135mg/L, fluoride ion concentration 95mg/L, antimony ion concentration 0.35mg/L. The waste electrolyte was pumped into the tubular heat exchanger at a flow rate of 1m ³ /h, and the calcium chloride solution with a temperature of -15°C was used as the refrigerant for heat exchange. The waste electrolyte of the heat exchanger was pre-cooled at the outlet temperature. At 5°C, a pre-cooling liquid was obtained.

(2) crystallization and impurity removal: the precooling liquid produced in step (1) is pumped into the impurity removal reactor with stirring device at a flow rate of 1 m ³ /h, and the control stirring speed is 100 rpm, and a coil heat exchanger is adopted, The temperature of the solution was lowered to 0°C by continuing heat exchange and cooling with a calcium chloride solution refrigerant at a temperature of -15°C. During the cooling process, 5g/L calcium sulfate dihydrate crystal seeds were added, and the reaction was carried out for 60min to obtain a solid-containing crystalline product. The solution.

(3) solid-liquid separation: the solution containing the solid crystalline product obtained in step (2) adopts a scraper discharge centrifuge to carry out rapid solid-liquid separation under the condition that the rotating drum speed is 1000 rpm, to obtain the electrolyte after removing impurities The main chemical components are analyzed and tested as follows: sulfuric acid concentration 160g/L, zinc ion concentration 37g/L, lead ion concentration 3.2mg/L, calcium ion concentration 76mg/L, silica concentration 92mg/L, fluoride ion concentration 72mg/L L, antimony ion concentration 0.12mg/L.

The electrolyte after removing impurities is returned to the electrolytic process of hydrometallurgy zinc for recycling.

Comparative Example 1

Other conditions are consistent with embodiment 1, and the difference is: after obtaining pre-cooling night in step (1), directly add crystal seed, after solid-liquid separation, the main chemical components in the gained electrolyte are: sulfuric acid concentration 199g/L, zinc Ion concentration 28g/L, lead ion concentration 6.5mg/L, calcium ion concentration 40mg/L, silica concentration 101mg/L, fluoride ion concentration 82mg/L, antimony ion concentration 0.2mg/L.

Comparative Example 2

Other conditions are consistent with Example 1, the difference is: the crystal seed is zinc sulfate; after the solid-liquid separation, the main chemical components in the obtained electrolyte are: sulfuric acid concentration 199.2g/L, zinc ion concentration 29g/L, lead ion concentration 6.6mg/L, calcium ion concentration 38mg/L, silica concentration 101mg/L, fluoride ion concentration 86mg/L, antimony ion concentration 0.2mg/L.

Comparative Example 3

Other conditions are consistent with embodiment 1, the difference is: the crystal seed is magnesium sulfate heptahydrate; after the solid-liquid separation, the main chemical components in the gained electrolyte are: sulfuric acid concentration 199.0g/L, zinc ion concentration 23g/L, lead The ion concentration is 6.2mg/L, the calcium ion concentration is 40mg/L, the silica concentration is 83mg/L, the fluoride ion concentration is 76mg/L, and the antimony ion concentration is 0.2mg/L.

Comparative Example 4

Other conditions are consistent with embodiment 1, the difference is: the solution after precooling is cooled to 5 ℃; after solid-liquid separation, the main chemical components in the obtained electrolyte are: sulfuric acid concentration 180g/L, zinc ion concentration 43g/L, Lead ion concentration 8.8mg/L, calcium ion concentration 43mg/L, silica concentration 110mg/L, fluoride ion concentration 104mg/L, antimony ion concentration 0.3mg/L.

The specific embodiments of the present invention have been described in detail above, but the present invention is not limited to the above-mentioned embodiments. Various changes can be made within the scope of knowledge possessed by those of ordinary skill in the art without departing from the spirit of the present invention. .

Claims (8)

1. a method for simultaneously removing multiple impurity ions in the waste electrolytic solution of wet zinc smelting, is characterized in that, comprises the following steps: Taking the waste electrolyte produced in the electrolysis process of zinc hydrometallurgy as the treatment object; cooling the treatment object to -15~0°C; introducing crystal seeds during the cooling process, and performing solid-liquid separation after the reaction for at least 15 minutes; obtaining the removal of impurities ionic electrolyte; the impurity ions include at least two of lead, calcium, silicon, fluorine, and antimony; The seed crystal is calcium sulfate or hydrated calcium sulfate. 2. a kind of method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 1, it is characterized in that: in the waste electrolyte of the output of the electrolytic process of zinc smelting by hydrolysis, sulfuric acid The concentration is 150 ~ 180g/L. 3. a kind of method for simultaneously removing multiple impurity ions in the waste electrolytic solution of wet zinc smelting according to claim 1, is characterized in that, comprises the following steps: (1) Heat exchange and pre-cooling: The waste electrolyte with a temperature of 35~40℃ and a sulfuric acid concentration of 150~180g/L produced in the electrolytic process of zinc hydrometallurgy is pumped into a tubular heat exchanger, and cooled by a carrier. The temperature of the waste electrolyte is pre-cooled to 5~20 ℃, and the pre-cooling liquid is obtained; (2) Crystallization and impurity removal: the pre-cooling liquid produced in step (1) is pumped into the impurity removal reaction kettle with a stirring device, and a heat exchanger is used to continue heat exchange and cooling through the carrier refrigerant, and the solution temperature is reduced to -15 ~0°C, add 1~5g/L of crystal seeds during the cooling process, and react for 20~60min to obtain a solution containing a solid crystalline product; (3) Solid-liquid separation: the solution containing the solid crystalline product obtained in step (2) is subjected to rapid solid-liquid separation to obtain an electrolyte from which impurity ions have been removed, and the electrolyte is returned to the hydrometallurgical zinc electrolysis process for recycling. The impurity ions are selected from at least two of lead, calcium, silicon, fluorine and antimony. 4 . The method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 3 , characterized in that: the refrigerant used in the step (1) and the step (2) It is a calcium chloride solution with a temperature of -30~-15℃. 5 . The method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 3 , wherein the crystal seed added in the step (2) is calcium sulfate dihydrate. 6 . 6 . The method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 3 , wherein the stirring speed of the stirring device used in the step (2) is 30 to 100 rpm. 7 . . 7. The method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 3, characterized in that: the rapid solid-liquid separation device in the step (3) is a scraper discharge centrifuge . 8. a kind of method for simultaneously removing various impurity ions in the waste electrolyte of wet zinc smelting according to claim 3, it is characterized in that: in the electrolyte after the gained removal of impurities, lead ion concentration is less than or equal to 3.1 mg /L, optimized to be less than or equal to 2.1 mg/L, calcium ion concentration less than or equal to 76 mg/L, optimized to be less than or equal to 65 mg/L, further optimized to be less than or equal to 32 mg/L, silica concentration less than or equal to 92 mg /L, optimized to be less than or equal to 78 mg/L, further optimized to be less than or equal to 75.7 mg/L, fluoride ion concentration less than or equal to 80 mg/L, optimized to be less than or equal to 75 mg/L, further optimized to be less than or equal to 72 mg /L, the antimony ion concentration is less than or equal to 0.12 mg/L, can be less than or equal to 0.11 mg/L after optimization, and can be less than or equal to 0.1 mg/L after further optimization.

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