Methods for removing chlorine in zinc hydrometallurgy.

Abstract

The present invention provides a method for removing chlorine from a process solution in a zinc hydrometallurgy process, comprising the steps of: preparing a process solution from a leaching process for leaching zinc cinder; charging the process solution into a reaction tank and charging lead concentrate into the reaction tank while blowing oxygen into the reaction tank; subjecting a slurry formed in the reaction tank to solid-liquid separation in a filtration tank; and post-treating the filtrate and the residue of the lead concentrate separated in the solid-liquid separation step, in which chlorine ions in the process solution react with silver contained in the lead concentrate in the reaction tank to precipitate silver chloride.

Description

[Technical field]

[0001] The present invention relates to a method for removing chlorine in the hydrometallurgical process for zinc. [Background technology]

[0002] There are two methods for extracting zinc from zinc concentrate: dry smelting and hydrometallurgy. In the hydrometallurgy method, zinc concentrate is roasted, leached, purified, and electro-winning to extract high-purity zinc.

[0003] The electrolysis process is very sensitive to various impurities, so the impurities must be removed to an appropriate level or below in the leaching process and / or solution purification process. Among these impurities, chlorine accelerates the corrosion of various metal equipment and causes the generation of chlorine gas in the electrolytic cell, so its concentration must be maintained at an appropriate level or below. However, it is very difficult to remove chlorine in the leaching and solution purification processes. Therefore, the chlorine concentration must be controlled by a method that reduces the input amount of raw materials in the wet process, but in this case, it becomes difficult to treat various raw materials in zinc smelting, and there is a problem especially when treating secondary raw materials with high chlorine content that are generated in the zinc recycling process. Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to remove chlorine contained in the process solution to an appropriate level using lead concentrate in the leaching process of zinc hydrometallurgy, thereby suppressing gas generation in the electrolytic cell in the subsequent electrolysis process, preventing corrosion of the equipment, and making it possible to treat various types of zinc concentrates and secondary raw materials generated in the zinc recycling process. [Means for solving the problem]

[0005] One embodiment of the present invention provides a method for removing chlorine from a process solution in a zinc hydrometallurgy process, the method comprising: preparing a process solution from a leaching process for leaching zinc cinder; introducing the process solution into a reaction tank and introducing lead concentrate into the reaction tank while blowing oxygen into the reaction tank; subjecting a slurry formed in the reaction tank to solid-liquid separation in a filtration tank; and post-treating a filtrate and a residue of the lead concentrate separated in the solid-liquid separation step, wherein the chlorine ions in the process solution react with silver contained in the lead concentrate in the reaction tank to precipitate silver chloride.

[0006] According to an embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, in which the residue of the lead concentrate is smelted in a lead smelting process.

[0007] In one embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, wherein the leaching process includes a neutral leaching process, a weak acid leaching process, a hot acid leaching process, and a super hot acid leaching process, and the process solution is a supernatant of a settling tank of the super hot acid leaching process.

[0008] In one embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, in which the filtrate is input into the strong acid leaching process.

[0009] According to an embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, wherein the lead concentrate contains 0.1 wt % or more of silver (Ag), 6 wt % or more of zinc (Zn), and 3 wt % or more of copper (Cu).

[0010] In one embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, wherein the particle size of the lead concentrate is less than 50 μm.

[0011] In one embodiment of the present invention, the oxygen is fed to the reaction vessel at a rate of 100 to 400 Nm3 / hr.

[0012] One embodiment of the present invention provides a method for removing chlorine from a process solution in a zinc hydrometallurgy process, in which the pulp concentration of the lead concentrate is in the range of 80 to 150 g / L.

[0013] One embodiment of the present invention provides a method for removing chlorine from a process solution in a zinc hydrometallurgical process, the method including: a roasting step for forming cinder from zinc concentrate; a leaching step for forming a leachate from the cinder; a chlorine removal step for removing chlorine from a part of the process solution in the leaching step using lead concentrate; a solution purification step for removing impurities from the leachate; and an electrolysis step for forming zinc from an electrolyte after the solution purification step.

[0014] According to an embodiment of the present invention, there is provided a method for removing chlorine from a process solution in a zinc hydrometallurgy process, wherein the chlorine removing step includes the steps of: introducing the process solution into a reaction vessel; introducing oxygen into the reaction vessel; and introducing the lead concentrate into the reaction vessel. Effect of the Invention

[0015] The present invention can prevent corrosion caused by chlorine ions generated throughout the smelter and generation of harmful gases in the electrolysis process by lowering the concentration of chlorine contained in the process solution in the zinc hydrometallurgical process. In addition, it is possible to process zinc concentrate and secondary raw materials with high chlorine content, which contributes to resource circulation. In addition, it is possible to recover zinc contained in large amounts in lead concentrate, which provides an economical zinc smelting method. [Brief description of the drawings]

[0016] [Figure 1] 1 is a process flow diagram illustrating a zinc hydrometallurgical process according to one embodiment of the present invention. [Diagram 2] 1 is a process flow chart showing a chlorine removal process in a zinc hydrometallurgical process according to an embodiment of the present invention. [Diagram 3] 1 is a diagram illustrating a chlorine removal process in a zinc hydrometallurgical process according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] The examples of the present invention are illustrated for the purpose of explaining the technical idea of ​​the present invention, and the scope of the invention is not limited to the examples presented below or the specific explanations of these examples.

[0018] The present invention will now be described with reference to the drawings.

[0019] Referring to FIG. 1, a zinc hydrometallurgical process may include a roasting step (S10), a leaching step (S20), a purification step (S30), and an electrolysis step (S40).

[0020] The zinc concentrate may be fed to a roasting step (S10), which is a step in which the zinc concentrate, which exists as a sulfide, is converted into an oxide using heat and oxygen, thereby forming calcine.

[0021] The leaching process (S20) is a process in which the cinder formed in the roasting process (S10) is dissolved in an acid solution such as sulfuric acid to form a zinc leachate. The spent electrolyte formed in the electrolysis process (S40) may be used in the leaching process (S20). In one embodiment, the leaching process (S20) may be comprised of multiple steps to maximize the zinc leaching rate and minimize the dissolution of impurities. In the multiple-step leaching process (S20), the spent electrolyte, the cinder, and the unreacted cinder may be countercurrent flows. The leaching process (S20) may include a neutral leaching process, a weak acid leaching process, a hot acid leaching process, and a super hot acid leaching process.

[0022] In one embodiment, the residue from the neutral leaching step may be fed to the weak acid leaching step, the residue from the weak acid leaching step may be fed to the strong acid leaching step, or the residue from the strong acid leaching step may be fed to the very strong acid leaching step. In one embodiment, the filtrate from the neutral leaching step may be fed to the liquid purification step (S30). Also, the filtrate from at least one of the weak acid leaching step, the strong acid leaching step, and the very strong acid leaching step may be fed to the neutral leaching step and / or another step thereafter.

[0023] The purification step (S30) is a step of removing impurities other than zinc from the leachate formed in the leaching step (S20). The solution after the purification step (S30) is used as an electrolyte in the electrolysis step (S40).

[0024] The electrolysis step (S40) is a step in which zinc is electrodeposited onto a cathode from an electrolyte solution containing zinc sulfate.

[0025] FIG. 2 is a process flow chart showing a chlorine removal process in a zinc hydrometallurgical process according to one embodiment of the present invention.

[0026] FIG. 3 is a diagram illustrating a chlorine removing process in a zinc hydrometallurgical process according to an embodiment of the present invention.

[0027] 2 and 3, the chlorine removal process may include a process liquid preparation step (S100), a lead concentrate input step (S200), a solid-liquid separation step (S300), and a filtrate and lead concentrate residue post-treatment step (S400).

[0028] <Process liquid preparation stage (S100)> First, a process liquid suitable for removing chlorine may be prepared from a zinc hydrometallurgical process. The process liquid suitable for removing chlorine may be a supernatant liquid of a settling tank of any one of the neutral leaching process, the weak acid leaching process, the hot acid leaching process, and the super hot acid leaching process of the leaching process (S20) in FIG. 1. For example, the process liquid suitable for removing chlorine may be a supernatant liquid of a settling tank of the super hot acid leaching process. The process liquid may be introduced into a reaction tank (100) as shown in FIG. 3.

[0029] The supernatant of the settling tank in the very strong acid leaching step may contain sulfuric acid at a concentration of 70 to 120 g / L and chlorine at a concentration of 0.4 to 0.7 g / L. The supernatant of the settling tank in the strong acid leaching step may contain sulfuric acid at a concentration of 20 to 70 g / L, the pH of the supernatant of the settling tank in the weak acid leaching step may be in the range of 1.5 to 3, and the pH of the supernatant of the settling tank in the neutral leaching step may be in the range of 3.5 to 5. However, the concentrations of sulfuric acid and chlorine in the process liquid may vary depending on the refinery.

[0030] If the entire process liquid were to be used, a large amount of lead concentrate would be required, so by adjusting the flow rate of the process liquid depending on the level of chlorine to be removed, chlorine can be efficiently removed using an appropriate amount of lead concentrate.

[0031] For example, by preparing only a portion of the process liquids (i.e., the supernatant liquid of the settling tank of the very strong acid leaching process) from among the multiple steps of the leaching process (S20) and appropriately adjusting the flow rate, it is possible to prevent the introduction of an unnecessarily large amount of lead concentrate. If a portion (e.g., about 50%) of the supernatant liquid of the settling tank of the very strong acid leaching process is introduced into the reaction tank (100) to remove a predetermined percentage of chlorine, the amount of lead concentrate introduced can be reduced compared to introducing the entire supernatant liquid of the settling tank of the very strong acid leaching process into the reaction tank (100) to remove a predetermined percentage of chlorine. In another embodiment, the entire supernatant liquid of the settling tank of the very strong acid leaching process may be introduced into the reaction tank (100) to remove chlorine.

[0032] <Lead concentrate input stage (S200)> Lead concentrate may be poured into the reaction tank (100). Oxygen may be blown into the reaction tank (100) and the lead concentrate may be poured into the reaction tank (100). In the reaction tank (100), chlorine (Cl) ions in the liquid may combine with silver (Ag) components contained in the lead concentrate to generate a precipitate in the form of silver chloride (AgCl). In this case, the concentration of chlorine (Cl) ions in the liquid in the reaction tank (100) decreases. The reaction between chlorine and silver can be expressed by the following reaction formula.

[0033] [Reaction formula] Ag + + Cl - = AgCl

[0034] The reaction temperature in the reaction vessel (100) may be in the range of 80-95°C, and the reaction time may be 5-20 hours. The pulp concentration of the lead concentrate may be preferably 80-150g / L. The pulp concentration of the lead concentrate is the amount of lead concentrate fed into the reaction vessel (100) per 1L of process liquid. Oxygen is supplied to the reaction vessel (100) through a typical bottom injection method, and may be injected at various flow rates depending on the size of the reaction vessel (100). For example, if the reaction vessel (100) has a volume of about 250m 3 When the dimensions are 3 / hr or approx. 100~400Nm 3 / hr. Oxygen may be injected into the reaction vessel (100) for the purpose of dissolving the copper and zinc components contained in the lead concentrate.

[0035] If the pulp concentration of the lead concentrate is less than 80 g / L, the chlorine removal efficiency decreases, and if it exceeds 150 g / L, the amount of lead concentrate added may be unnecessarily large.

[0036] Although a general lead concentrate may be used, a relatively high silver (Ag) content may be desirable, and a relatively high zinc content and copper content may also be desirable. Silver (Ag) directly combines with chlorine in the process solution, so a high Ag content is desirable to improve the efficiency of chlorine removal. Although zinc and copper contained in lead concentrate are elements that are harmful to lead smelting, even if their content is high, they can be recovered in the subsequent zinc smelting process, and the residue of the lead concentrate after the zinc and copper are dissolved in the process solution has reduced zinc and copper contents, which is also advantageous in lead smelting.

[0037] The zinc and copper components contained in lead concentrate are difficult to smelt in a dry process. However, since 80-95% of the zinc and copper components may be dissolved in the reaction tank (100), the residue of the lead concentrate has a reduced content of zinc and copper components, making it easier to smelt the residue of the lead concentrate into lead. In addition, the dissolved zinc and copper components can be recovered in a subsequent process of zinc smelting, providing an economical zinc smelting method.

[0038] The lead concentrate may contain 0.1% by weight or more of silver (Ag). If the silver content in the lead concentrate is less than 0.1%, the effect of removing chlorine from the process liquid decreases.

[0039] The lead concentrate may contain 6% by weight or more of zinc (Zn), because if the zinc content in the lead concentrate is less than 6% by weight, the effect of recovering zinc in the subsequent process becomes small.

[0040] The lead concentrate may contain 3% by weight or more of copper (Cu), because if the copper content in the lead concentrate is less than 3% by weight, the effect of recovering copper in the subsequent process is reduced.

[0041] In some cases, a fine particle size of the lead concentrate is desirable, for example, the particle size of the lead concentrate may be 50 μm or less, as larger particle size lead concentrates may be less reactive, resulting in reduced chlorine removal, zinc recovery, and copper recovery.

[0042] In order to increase the acidity of the solution in the reaction tank (100) in the lead concentrate introduction step (S200), the electrolytic septic solution (Spent) formed in the electrolysis step (S40) of Fig. 1 may be introduced into the reaction tank (100). This is because as the acidity of the solution in the reaction tank (100) increases, the dissolution rate of zinc and copper may increase.

[0043] The lead (Pb) component of the lead concentrate does not dissolve in the sulfuric acid, and some of it may change from sulfide to sulfate, but this does not cause any problems in the subsequent lead smelting process (300).

[0044] <Solid-liquid separation stage (S300)> The slurry after the reaction is subjected to solid-liquid separation through a filtration device, and separated into a filtrate and a lead concentrate residue. In one embodiment, the slurry may be passed through a settling tank before filtration. The filtration device is preferably a general filter press, but is not limited thereto, and other types of solid-liquid separation devices may be used.

[0045] <Filtrate and lead concentrate residue post-treatment stage (S400)> The filtrate after the reaction may have a significantly reduced chlorine concentration compared to the initial solution, and may have slightly increased zinc and copper concentrations. The filtrate after the reaction may be fed to a strong acid leaching process, which has the second highest acidity, in comparison to the super strong acid leaching process, which has the highest acidity. In the subsequent electrolysis process, the chlorine concentration in the electrolyte is reduced, which suppresses the generation of gas in the electrolytic cell, preventing corrosion of the equipment, and enabling the treatment of various types of zinc concentrate and secondary raw materials generated in the zinc recycling process.

[0046] The lead concentrate residue after the reaction may be smelted in the lead smelting process (300). The zinc and copper contents in the lead concentrate residue are low, which may be advantageous when smelting by a dry process. The lead concentrate residue contains a slightly increased concentration of chlorine, but this does not have a significant effect on the lead smelting process (300), so there is no difficulty in smelting lead.

[0047] According to an exemplary embodiment of the present invention, by lowering the chlorine concentration in the process solution in zinc hydrometallurgy, it is possible to prevent corrosion caused by chlorine ions generated throughout the refinery and generation of harmful gases in the electrolysis process. In addition, it is possible to process zinc concentrate and secondary raw materials with high chlorine content, which contributes to resource circulation. In addition, it is possible to recover zinc contained in large amounts in lead concentrate, which provides an economical zinc smelting method.

[0048] [Examples 1 and 2] 2L of process solution from the leaching process of a zinc smelting process and 300g of lead concentrate were reacted for 16 hours by blowing oxygen into a reaction tank at 90°C, and then filtered. The concentration of chlorine (Cl) contained in the filtrate after filtration was measured. In Comparative Example 1 and Comparative Example 2, the other conditions were the same as in Example 1 and Example 2, except for the component content and particle size of the lead concentrate. The chlorine concentration and chlorine removal rate of the filtrate after filtration in the Examples and Comparative Examples are compared in Table 1.

[0049] In Examples 1 and 2, a process liquid containing chlorine (Cl) at a concentration of 0.568 g / L, zinc (Zn) at a concentration of 92 g / L, and sulfuric acid at a concentration of 126 g / L was used.

[0050] In Example 1, lead concentrate A containing 51.1 wt % lead (Pb), 0.4 wt % silver (Ag), 6.3 wt % zinc (Zn), and 3.7 wt % copper (Cu) was used.

[0051] In Example 2, lead concentrate B containing 29.4 wt % lead (Pb), 0.3 wt % silver (Ag), 13.7 wt % zinc (Zn), and 1.9 wt % copper (Cu) was used.

[0052] The results of the above-described experiment are shown in Table 1 below.

[0053] [Table 1]

[0054] When the particle size of the lead concentrate is as large as 85 μm as in Comparative Example 2, the chlorine removal rate is 14.3%, whereas when the particle size of the lead concentrate is 50 μm or less as in Examples 1 and 2, the chlorine removal rate is significantly higher than that of Comparative Example 1. When the silver contained in the lead concentrate is 0.05 wt% as in Comparative Example 1, the chlorine removal rate is 8.1%, whereas when the silver contained in the lead concentrate is 0.1 wt% or more as in Examples 1 and 2, the chlorine removal rate is significantly higher than that of Comparative Example 1.

[0055] In addition, Example 1, which used lead concentrate with a higher silver content, had a higher chlorine removal rate in the process liquid than Example 2.

[0056] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it should be understood by those skilled in the art to which the present invention pertains that the present invention may be embodied in other specific forms without changing its technical concept or essential characteristics.

[0057] Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the above detailed description, and all modifications and alterations derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

Claims

1. providing a process liquor from a leaching process for leaching zinc cinder; pouring the process solution into a reaction vessel, and pouring lead concentrate into the reaction vessel while blowing oxygen into the reaction vessel; subjecting the slurry formed in the reaction vessel to solid-liquid separation in a filtration vessel; and and post-treating the filtrate and the lead concentrate residue separated in the solid-liquid separation step; A method for removing chlorine from a process solution in a zinc hydrometallurgy process, comprising reacting the chlorine ions in the process solution with the silver contained in the lead concentrate in the reaction tank to precipitate silver chloride.

2. 2. The method for removing chlorine from a process solution in a zinc hydrometallurgy process according to claim 1, wherein the residue of the lead concentrate is smelted in a lead smelting process.

3. The leaching process includes a hot acid leaching process and a super hot acid leaching process to which a residue from the strong acid leaching process is added; 2. The method for removing chlorine from a process solution in a zinc hydrometallurgy process according to claim 1, wherein the process solution is a supernatant liquid from a settling tank in the very strong acid leaching process.

4. 4. The method for removing chlorine from a process solution in a zinc hydrometallurgy process according to claim 3, wherein the filtrate is introduced into the strong acid leaching process.

5. 2. The method for removing chlorine from a process solution in a zinc hydrometallurgical process according to claim 1, wherein the lead concentrate contains 0.1% by weight or more of silver (Ag), 6% by weight or more of zinc (Zn), and 3% by weight or more of copper (Cu).

6. 2. The method for removing chlorine from a process solution in a zinc hydrometallurgical process according to claim 1, wherein the particle size of the lead concentrate is 50 μm or less.

7. The oxygen is added to the reaction vessel at 100 to 400 Nm ３ 2. The method for removing chlorine from a process solution in a zinc hydrometallurgical process according to claim 1, wherein the process solution is blown in at a flow rate of 1000 ml / hr.

8. The method for removing chlorine from a process solution in a zinc hydrometallurgy process according to claim 1, wherein the pulp concentration of the lead concentrate is in the range of 80 to 150 g / L.

9. a roasting step for forming cinder from the zinc concentrate; leaching to form a leachate from the cinder; a chlorine removal step for removing chlorine from a part of the process solution of the leaching step using lead concentrate; A purification step for removing impurities from the leachate; and A method for removing chlorine from a process solution in a zinc hydrometallurgical process, comprising an electrolysis step of forming zinc from the electrolyte after the solution purification step.

10. 10. The method for removing chlorine from a process solution in a zinc hydrometallurgical process according to claim 9, wherein the chlorine removing step comprises the steps of: feeding the process solution into a reaction vessel; and feeding the lead concentrate into the reaction vessel while blowing oxygen therein.

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