CN114622094A - Method for separating magnesium ions in zinc hydrometallurgy system - Google Patents

Abstract

The invention discloses a method for separating magnesium ions in a zinc hydrometallurgy system, which comprises the following steps: reacting the neutral leaching supernatant with calcium hydroxide to generate a precipitate, and performing first filtration to obtain a first filtrate and a first filter residue; wherein the neutral leaching supernatant comprises: zn²⁺、Cu²⁺And Mg²⁺. Thus, Zn²⁺And Cu²⁺Can react with calcium hydroxide to form Zn (OH)₂And Cu (OH)₂Precipitation and Mg²⁺Not precipitating, and performing primary filtration to obtain primary filtrate containing Mg²⁺The first filter residue comprises Zn (OH)₂And Cu (OH)₂The separation of magnesium ions in the zinc hydrometallurgy system can be realized through simple filtering operation. In addition, the method of the invention also has the advantages of simple operation, high efficiency and low cost.

Description

Method for separating magnesium ions in zinc hydrometallurgy system

Technical Field

The invention belongs to the technical field of metallurgy, and particularly relates to a method for separating magnesium ions in a zinc hydrometallurgy system.

Background

In the process of the zinc hydrometallurgy, magnesium in the system is difficult to remove in the purification process, so that the magnesium is continuously and circularly enriched in the zinc hydrometallurgy system, the structures of a system pipeline, a tank and the like are directly influenced, the problems of crystallization blockage, energy consumption increase and the like are brought, and the zinc hydrometallurgy cost is increased. Therefore, how to remove magnesium ions in solution is an important issue of constant attention in the zinc hydrometallurgy industry.

The traditional mode for removing magnesium ions in a wet zinc smelting system is as follows: the solubility of the magnesium ion-containing compound is lowered at low temperature, and the magnesium-containing compound is precipitated at low temperature.

The existing method can realize the removal of magnesium ions to a certain extent and reduce the harm of the magnesium ions to zinc hydrometallurgy. However, the existing method has the problems of high operation cost, low magnesium ion removal efficiency, complex process flow and the like.

Therefore, there is a need for an improved method for separating magnesium ions in a zinc hydrometallurgy system.

Disclosure of Invention

The present invention aims to ameliorate at least one of the above technical problems to at least some extent.

In order to solve the technical problems, the invention provides a method for separating magnesium ions in a zinc hydrometallurgy system, which comprises the following steps: reacting the neutral leaching supernatant with calcium hydroxide to generate a precipitate, and performing first filtration to obtain a first filtrate and a first filter residue; wherein the neutral leaching supernatant comprises: zn²⁺、Cu²⁺And Mg²⁺. Thus, Zn²⁺And Cu²⁺Can react with calcium hydroxide to generate Zn (OH)₂And Cu (OH)₂Precipitation and Mg²⁺Not precipitated, Mg²⁺Can be left in solution and subjected to a first filtration comprising Mg in a first filtrate²⁺The first filter residue comprises Zn (OH)₂And Cu (OH)₂The separation of magnesium ions in the zinc hydrometallurgy system can be realized through simple filtering operation. Moreover, the method of the invention also has the advantages of simple operation, high efficiency and low cost.

According to an embodiment of the invention, the Zn²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0.85-0.88) 1; the Cu²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0.83-0.86): 1.

According to an embodiment of the invention, the reaction is carried out at a pH of 6.5 to 7.5.

According to an embodiment of the invention, the temperature of the reaction is 60-70 ℃.

According to an embodiment of the invention, the reaction time is greater than 60 min.

According to an embodiment of the present invention, the calcium hydroxide is prepared by: the calcium oxide is mixed with water to produce calcium hydroxide.

According to an embodiment of the invention, the neutral leaching supernatant further comprises: SO (SO)₄ ^2-；

After performing the first filtration, the reacting further comprises: and reacting the first filter residue with the waste electrolyte, and performing second filtration to obtain a second filtrate and a second filter residue.

According to an embodiment of the invention, the spent electrolyte comprises H₂SO₄；

The content ratio of the waste electrolyte to the first filter residue is (3-4): 1L/kg.

According to an embodiment of the invention, said H₂SO₄The content of (b) is 150-170 g/L.

According to an embodiment of the invention, the temperature of the reaction is between 40 ℃ and 60 ℃.

Drawings

FIG. 1 is a flow chart of a method for separating magnesium ions in a zinc hydrometallurgy system according to an embodiment of the present invention;

FIG. 2 is a flow chart of a method for separating magnesium ions in a zinc hydrometallurgy system according to another embodiment of the present invention;

FIG. 3 is a flow chart of a process for separating magnesium ions in a zinc hydrometallurgy system according to another embodiment of the present invention.

Detailed Description

Embodiments of the present application are described in detail below. The following description of the embodiments is merely exemplary in nature and is in no way intended to limit the present disclosure. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents used are not indicated by manufacturers, and are all conventional products available on the market.

The inventor finds that magnesium ions in a zinc hydrometallurgy system are difficult to remove, and the excessive magnesium content affects the electrolytic power consumption and increases the zinc hydrometallurgy cost. In particular, Mg²⁺Has a precipitation potential of-2.378V, Zn²⁺Has a precipitation potential of-0.763V, Mg²⁺Is more than Zn in precipitation potential²⁺The precipitation potential of (2) is more negative, so Mg²⁺Difficult to precipitate at the cathode, Mg²⁺Substantially retained in the electrolyte to increase the viscosity of the solution, and has good Zn resistance²⁺The migration has an obstruction effect, and the energy has to be increased (the cell voltage is increased) to overcome, so that the power consumption is increased. Zinc is precipitated at a potential of less than-0.763V, and Mg²⁺Is selected as a surfactant to be adsorbed on the cathode active site, resulting in Zn²⁺The adsorption and surface diffusion at the cathode are limited, so that the crystallization overvoltage of zinc appears to different degrees, the possibility of accelerating the precipitation of hydrogen and impurities due to the influence of the surface of the precipitated zinc is caused, and the electric efficiency is also reduced. When Mg contained in a zinc hydrometallurgy system reaches a saturated concentration, the Mg can be separated out and scaled on pipelines and tanks. Therefore, the method has important significance for reducing the content of magnesium ions in the zinc hydrometallurgy system.

In order to solve the technical problems, the invention provides a method for separating magnesium ions in a zinc hydrometallurgy system, which comprises the following steps: reacting the neutral leaching supernatant with calcium hydroxide to generate a precipitate, and performing first filtration to obtain a first filtrate and a first filter residue; wherein the neutral leaching supernatant comprises: zn²⁺、Cu²⁺And Mg²⁺. Thus, Zn²⁺Reacting with calcium hydroxide to form Zn (OH)₂Precipitation of，Cu²⁺Reacting with calcium hydroxide to produce Cu (OH)₂Precipitation, Mg²⁺Not precipitated, Mg²⁺Left in solution; through the first filtration, the product containing Mg can be obtained²⁺The first filtrate of (1) comprises Zn (OH)₂And Cu (OH)₂The first filter residue can be filtered to realize the separation of magnesium ions from the zinc hydrometallurgy system, the method can reduce the Mg content in the zinc hydrometallurgy system, and the first filter liquor can be recycled. Moreover, the method of the invention also has the advantages of simple operation, and reduced labor cost and power consumption.

According to an embodiment of the present invention, referring to fig. 1, the calcium hydroxide may be prepared by: the calcium oxide is mixed with water to produce calcium hydroxide. The reaction equation is as follows:

CaO+H₂O＝Ca(OH)₂

in some embodiments of the invention, the particle size of calcium oxide can be less than or equal to 200 meshes, the particle size of calcium oxide less than or equal to 200 meshes accounts for 80%, the purity of CaO is greater than or equal to 93%, water is mixed with calcium oxide, and calcium hydroxide ore pulp of about 250g/L is prepared, so that the normal conveying of the ore pulp can be ensured, and the water consumption is reduced as much as possible.

The neutral leaching supernatant is the neutral leaching supernatant in the zinc hydrometallurgy process and is also called as middle supernatant. The invention can carry out neutral leaching on Zn in the supernatant²⁺、Cu²⁺And Mg²⁺The content of (A) is not limited, e.g. Zn²⁺May be 130g/L, Cu²⁺The content of (B) may be 0.6g/L, Mg²⁺The content of (B) may be 20 g/L.

According to an embodiment of the invention, the Zn²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0.85-0.88): 1, such as 0.85:1, 0.86:1, 0.87:1 and 0.88: 1; if the ratio is too low, there is an excess of calcium hydroxide added, Mg²⁺Settling to Mg (OH)₂Failure to realize Zn²⁺With Mg²⁺Separation and the like. If the ratio is too high, there is a shortage of calcium hydroxide and Zn²⁺Can not be completely precipitated, resulting in Zn²⁺And Mg²⁺Failure to completely separate, resulting inDifficult treatment and the like.

The Cu²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0.83-0.86): 1, for example, 0.83:1, 0.84:1, 0.85:1, 0.86: 1. If the ratio is too low, there is an excess of calcium hydroxide added, Mg²⁺Settling to Mg (OH)₂Cannot realize Cu²⁺With Mg²⁺Separation and the like. If the ratio is too high, there is insufficient calcium hydroxide, Cu²⁺Can not be completely precipitated, resulting in Cu²⁺And Mg²⁺The separation is incomplete, and the post-treatment is difficult.

According to an embodiment of the invention, the reaction is carried out at a pH of 6.5-7.5, e.g. the pH of the reaction may be 6.5, 6.6, 6.7, 6.8, 6.9, 7, 7.1, 7.2, 7.3, 7.4, 7.5. If the pH of the reaction is too low, Zn is caused²⁺And Cu^{2 +}The precipitation is incomplete and even can not generate precipitates, so that the separation of magnesium ions can not be realized. If the pH of the reaction is too high, Mg²⁺Will generate Mg (OH)₂Possibly resulting in Mg (OH)₂、Zn(OH)₂And Cu (OH)₂Meanwhile, the magnesium ions can not be separated by precipitation.

According to the embodiment of the present invention, the temperature of the reaction is 60 to 70 ℃, and for example, 60 ℃, 61 ℃, 62 ℃, 63 ℃, 64 ℃, 65 ℃, 66 ℃, 67 ℃, 68 ℃, 69 ℃, 70 ℃ can be used. If the reaction temperature is too low, the reaction may be incomplete and the first filtrate may contain residual Zn²⁺And/or Cu²⁺Resulting in difficulty in post-treatment. If the reaction temperature is too high, the reaction rate cannot be effectively increased, and there is also a disadvantage that the energy consumption is too large.

According to an embodiment of the present invention, the reaction time is more than 60min, for example, 61min, 62min, 63min, 64min, 65min, 66min, 67min, 68min, 69min, 70min, and the like. If the reaction time is too short, there is a disadvantage that the reaction is incomplete.

According to an embodiment of the invention, the neutral leaching supernatant further comprises: SO (SO)₄ ^2-During the reaction, CaSO₄Hui and Zn (OH)₂And Cu (OH)₂Is precipitated together, that is, the first filter residue also comprises CaSO₄. The reaction equation is as follows:

ZnSO₄+Ca(OH)₂+n·H₂O＝Zn(OH)₂↓+CaSO₄·nH₂O↓

CuSO₄+Ca(OH)₂+n·H₂O＝Cu(OH)₂↓+CaSO₄·nH₂O↓

according to an embodiment of the present invention, referring to fig. 2, after performing the first filtration, the reacting further comprises: and reacting the first filter residue with the waste electrolyte, and performing second filtration to obtain a second filtrate and a second filter residue. According to an embodiment of the invention, the spent electrolyte comprises H₂SO₄. Thus, Zn (OH) in the first residue₂Reacts with the waste electrolyte to generate Zn²⁺(ii) a Cu (OH) in first filter residue₂Reacts with the waste electrolyte to generate Cu²⁺(ii) a And CaSO₄Does not react with the spent electrolyte. The second filtrate comprises Zn²⁺And Cu²⁺And the second filtrate can be returned to the zinc hydrometallurgy system. The second filter residue comprises CaSO₄And the second filter residue can be sold as gypsum residue. The reaction equation is as follows:

Zn(OH)₂↓+H₂SO₄＝ZnSO₄+2H₂O

Cu(OH)₂↓+H₂SO₄＝CuSO₄+2H₂O

according to an embodiment of the invention, H in the spent electrolyte₂SO₄The content of (b) is 150-170 g/L.

According to an embodiment of the present invention, the reaction of the first residue with the spent electrolyte may be carried out in a slurrying tank.

The inventor finds that when the solution in the pulping tank contains more than or equal to 30g/L of acid after the reaction, the reaction of the first filter residue and the waste electrolyte can be ensured to be complete. I.e. acid and Zn (OH) in the spent electrolyte₂And Cu (OH)₂Reaction to form ZnSO₄With CuSO₄After, of spent electrolyte in the system after the reactionThe content is more than or equal to 30g/L, and if the content of the waste electrolyte in the system after reaction is too small, the problems of difficult filtration, high zinc content in the second filter residue, high zinc loss and the like exist.

The content ratio of the waste electrolyte to the first filter residue is (3-4): 1L/kg. If the proportion is too low, the amount of the waste electrolyte is not enough, and the final acidity can not be ensured to be more than or equal to 30g/L, so that the second filter residue is difficult to filter, the second filter residue has high zinc content, high zinc loss and other adverse problems. If the ratio is too high, the content of the added waste electrolyte is too high, and the end point acidity is high, which leads to an increase in the system throughput, and other problems.

According to an embodiment of the present invention, the temperature of the reaction is 40 ℃ to 60 ℃, for example, 40 ℃, 45 ℃, 50 ℃, 55 ℃, 60 ℃.

According to an embodiment of the present invention, referring to fig. 3, the reaction of calcium oxide and water may be performed in a surge tank, the reaction of the medium supernatant with calcium hydroxide may be performed in a neutralization tank, and the reaction of the spent electrolyte and the first residue may be performed in a slurrying tank. Specifically, calcium oxide and water are added to the size mixing tank to produce calcium hydroxide. Adding the calcium oxide and the supernatant after size mixing into a neutralization tank, adjusting the pH value of the neutralization tank to 6.5-7.5, and performing pressure filtration on the ore pulp obtained by reaction in a first pressure filter to obtain a first filtrate and a first filter residue, wherein the first filtrate contains Mg²⁺The first filtrate can be recycled, and the first filter residue comprises Zn (OH)₂、Cu(OH)₂And CaSO₄. The first filter residue enters a pulping tank, waste electrolyte is added, the leached ore pulp enters a second filter press for filter pressing to obtain second filtrate and second filter residue, wherein the second filtrate comprises Zn²⁺And Cu²⁺The second filtrate returns to the zinc hydrometallurgy system, and the second filter residue comprises CaSO₄And the second filter residue is sold out of the system. The invention can realize the separation of Mg ions in the zinc hydrometallurgy system, reduce the Mg content in the zinc hydrometallurgy system and greatly reduce the unit consumption of electrolytic direct current.

According to some embodiments of the invention, the neutralization tank may comprise three reaction tanks connected in series, and the reaction volume may be 210m³Three reaction tanks are operated continuously, and a single reaction tankMay be 70m in volume³。

In general, the method can realize the separation of magnesium ions in the zinc hydrometallurgy, reduce the content of Mg in a zinc hydrometallurgy system, and reduce the content of supernatant Mg and the content of waste liquid Mg in the zinc hydrometallurgy system after long-term operation, specifically, the first filtrate contains Mg²⁺Mg can be obtained after water treatment²⁺Solutions with very low contents of Mg²⁺The very low level solution may be returned to the supernatant to reduce the Mg level of the supernatant. In some embodiments of the invention, the Mg content of the medium supernatant can be reduced from 20g/L to 10 g/L. The solution in the zinc hydrometallurgy system is recycled, the Mg content in the whole system can be reduced, specifically, in the process of preparing the supernatant, the filter residue needs to be treated by the waste liquid, and the supernatant is obtained after leaching, so that the Mg content in the waste liquid can be reduced from 23g/L to 12 g/L.

The method can also improve the electrolysis current efficiency and reduce the unit consumption of electrolysis direct current. In some embodiments of the invention, the electrolysis direct current power consumption can be reduced by 90 kW.h/t, and the electrolysis direct current unit consumption is greatly reduced.

The method can reduce the Mg content in the zinc hydrometallurgy system, the viscosity of the system solution is reduced after the Mg content is reduced, and the cleaning frequency of pipelines and tanks is reduced.

In addition, the zinc hydrometallurgy system belongs to closed cycle, various liquids are recycled after different process control, when external liquids enter, the total volume can expand, so that the system is collapsed (such as water brought by steam heating and water brought by sanitation cleaning), when more water is discharged, the volume of the system is reduced, and the system is difficult to circulate (such as evaporation). The separation of magnesium ions can be realized by adding calcium hydroxide, the first filtrate can be discharged to water for treatment, and the solution with lower Mg content after water treatment is returned to the wet zinc smelting system, so that the Mg content of the system is reduced, the volume balance of the wet system is ensured, and the volume balance condition of the wet system is improved.

In the description of the present invention, it is to be understood that the terms "first", "second" and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implying any number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless specifically limited otherwise.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.

Claims (10)

1. The method for separating magnesium ions in the zinc hydrometallurgy system is characterized by comprising the following steps: reacting the neutral leaching supernatant with calcium hydroxide to generate a precipitate, and performing first filtration to obtain a first filtrate and a first filter residue;

wherein the neutral leaching supernatant comprises: zn²⁺、Cu²⁺And Mg²⁺。

2. The method of claim 1, wherein the Zn is²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0).85～0.88):1；

The Cu²⁺The molar ratio of the calcium hydroxide to the calcium hydroxide is (0.83-0.86): 1.

3. The method according to claim 1, wherein the reaction is carried out at a pH of 6.5 to 7.5.

4. The process according to claim 1, wherein the temperature of the reaction is 60-70 ℃.

5. The method of claim 1, wherein the reaction time is greater than 60 min.

6. The method according to claim 1, characterized in that the calcium hydroxide is prepared by: the calcium oxide is mixed with water to produce calcium hydroxide.

7. The method of claim 1, wherein the neutral leaching supernatant further comprises: SO (SO)₄ ^2-；

After performing the first filtration, the reaction further comprises: and reacting the first filter residue with the waste electrolyte, and performing second filtration to obtain a second filtrate and a second filter residue.

8. The method of claim 7, wherein the spent electrolyte comprises H₂SO₄；

The content ratio of the waste electrolyte to the first filter residue is (3-4): 1L/kg.

9. The method of claim 8, wherein the H is₂SO₄The content of (b) is 150-170 g/L.

10. The process according to claim 7, wherein the temperature of the reaction is 40 ℃ to 60 ℃.

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