Method for treating by - products of zinc hydrometallurgy process with reduced carbon emissions

Abstract

A method for treating a by-product of a zinc hydrometallurgy process according to one embodiment of the present invention includes a pressure leaching process in which a lead / silver-containing by-product generated in a finish leaching process in a zinc hydrometallurgy process is pressure leached in an autoclave to reduce the zinc and iron contents in the leaching residue to less than 1 wt %, respectively.

Description

Technical Field

[0001] The present invention relates to a method for treating by-products generated in the zinc wet smelting process.

Background Art

[0002] The methods for extracting zinc from zinc concentrate include a dry smelting method and a wet smelting method. Among these, the wet smelting method refers to a method in which, after passing through the roasting process, leaching process, and purification process of zinc concentrate, finally, high-purity zinc is extracted through an electrolysis process.

[0003] FIG. 1 shows a flowchart of a partial process of conventional zinc wet smelting.

[0004] Referring to FIG. 1, an acid leaching step (S10) for leaching zinc calcine that has undergone a roasting process, a strong acid leaching step (S20) for further leaching the cake generated in the acid leaching step (S10) with a stronger acid, and a finishing leaching step (S30) for finally leaching the cake generated in the strong acid leaching step (S20) are carried out, and a lead / silver-containing by-product is generated. The lead / silver-containing by-product can be a by-product containing lead (Pb) and silver (Ag), and can be generated in the leaching step in the zinc wet smelting process as described above.

[0005] The lead / silver-containing by-product generated in such zinc wet smelting contains a considerable amount of about 5% zinc (Zn) and 10% iron (Fe), and thus is a raw material more suitable for volatilization treatment using a fumer than melting treatment in a smelter in the dry treatment process. This is because when the zinc ferrite (ZnO·Fe 2 O 3 ) component in the lead / silver-containing by-product is treated in a melting smelting furnace, it does not easily melt and causes operational instability. Accordingly, conventionally, the generated lead / silver-containing by-product has been treated in a volatilization treatment step (S40) of volatilizing and recovering the metal using a fumer.

[0006] However, the volatilization treatment using a volatile smelting furnace can process lead / silver-containing by-products with high zinc (Zn) and iron (Fe) contents. However, it usually has the disadvantage that the carbon emissions per unit of raw material are more than five times higher compared to the melting treatment through a melting smelting furnace. There is also a problem that the recovery rates of valuable metals such as silver (Ag), gold (Au), and copper (Cu) are considerably lower compared to the melting treatment using a melting smelting furnace. Specifically, as described in Table 1 below, when treating 1 ton of lead / silver-containing by-products in a volatile smelting furnace, about 1.38 tons of CO 2 is generated, whereas when treating in a melting smelting furnace, the generation amount of CO 2 can be reduced to about 0.26 tons.

Table 1

Summary of the Invention

Problems to be Solved by the Invention

[0007] An object of the present invention is to provide a treatment method for lead / silver-containing by-products, which are by-products generated in a zinc hydrometallurgy process, with a high recovery rate of valuable metals and a low carbon emission amount.

Means for Solving the Problems

[0008] The method for treating by-products of the zinc hydrometallurgy process of the present invention may include a pressure leaching step of subjecting the lead / silver-containing by-products generated in the finishing leaching step of the zinc hydrometallurgy process to pressure leaching in an autoclave so that the contents of zinc and iron contained in the leaching residue are each less than 1% by weight.

[0009] According to an embodiment of the present invention, in the pressure leaching step, the lead / silver-containing by-products can be pressure leached with zinc electrolysis tail liquor.

[0010] According to an embodiment of the present invention, the pressure leaching step can be performed so that the concentration of iron in the leaching solution is maintained at 10 - 12 g / L.

[0011] According to an embodiment of the present invention, the amount of the zinc electrolysis tail liquid to be input can be adjusted according to the iron content of the lead / silver-containing by-product so that the iron concentration in the leachate is maintained at 10 to 12 g / L.

[0012] A method for treating a by-product of a zinc hydrometallurgy process according to an embodiment of the present invention includes a pressure leaching step of subjecting a lead / silver-containing by-product generated in a finishing leaching step of a zinc hydrometallurgy process to pressure leaching in an autoclave so that the contents of zinc and iron contained in the leaching residue are each less than 1% by weight, a separation step of solid-liquid separating the leachate and the leaching residue of the pressure leaching step, and a melting treatment step of treating the leaching residue in a melting furnace.

[0013] According to an embodiment of the present invention, the leachate filtered in the separation step can be sent to a purification step in a zinc hydrometallurgy process.

Effects of the Invention

[0014] According to the present invention, the amount of the lead / silver-containing by-product, which is a by-product generated in the zinc hydrometallurgy process, can be reduced by subjecting it to pressure leaching. Specifically, the ratio of the leaching residue generated through pressure leaching can be about 56 to 63% of the input by-product, whereby the treatment cost for the by-product generated in the zinc hydrometallurgy process can be reduced.

[0015] Further, according to the present invention, the contents of zinc and iron contained in the leaching residue after pressure leaching can be reduced to 1 wt%, which is a level that can be processed in a melting furnace. less than Thereby, by subjecting the leaching residue after pressure leaching to melting treatment using a melting furnace, the recovery rate of valuable metals can be increased and the carbon emission can be reduced.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0017] FIG. 2 is a process flowchart of a method for treating a lead / silver-containing byproduct according to the present invention.

[0018] Referring to FIG. 2, a method for treating a lead / silver-containing byproduct according to the present invention may include a pressure leaching step (S100), a separation step (S200), and a melting treatment step (S300).

[0019] The lead / silver-containing byproduct used as a raw material for the method for treating a lead / silver-containing byproduct according to the present invention is a lead / silver-containing byproduct generated as a byproduct in the zinc hydrometallurgy process is the final leaching step of finish leaching step (S30). a .

[0020] [Pressure Leaching Step (S100)] In the pressure leaching step (S100), a pressure leaching step can be performed on the lead / silver-containing byproduct at a pressure higher than normal pressure using an autoclave. Specifically, in the pressure leaching step (S100), leaching of zinc and iron in the lead / silver-containing byproduct can be performed at a temperature of 130° C. or higher and a pressure of 3.7 bar or higher using an autoclave.

[0021] The pressure leaching step (S100) can be performed for 1 to 2 hours. As will be described later together with experimental data, when the pressure leaching step (S100) is prolonged, the leached iron may be reprecipitated, so the desired reaction time may vary depending on the temperature and pressure. For example, the pressure leaching step (S100) can be performed for 1 to 1.5 hours at a temperature of 130° C. or higher and lower than 150° C. and a pressure of 3.7 to 4.0 bar, and can be performed for 1 to 2 hours at a temperature of 150° C. or higher and a pressure of 3.7 to 4.0 bar.

[0022] According to one embodiment, the solution used for leaching in the pressure leaching step (S100) can be zinc spent leachate obtained after the electrolysis step in the zinc hydrometallurgy process. For example, the main component of the zinc spent leachate is sulfuric acid (H 2 SO 4 ), and the concentration of sulfuric acid can be about 160 - 180 g / L. In contrast, according to other embodiments, the solution used for leaching in the pressure leaching step (S100) can be sulfuric acid with a concentration of about 160 - 180 g / L. The reaction formula related to leaching is as shown in Formula 1 below.

[0023] ZnFe 2 O 4 +4H 2 SO 4 →ZnSO 4 +Fe 2 (SO 4 ) 3 +4H 2 O…(Formula 1)

[0024] The ratio of the leaching residue after the pressure leaching step (S100) (i.e., the ratio of the leaching residue after the pressure leaching step to the lead / silver-containing by-product input as raw material) can be about 56 - 63%. The contents of zinc (Zn) and iron (Fe) contained in the leaching residue are about 1 wt% less than . As will be described later together with experimental data, among the lead / silver-containing by-products, jarosite and zinc ferrite are leached, and it is judged that the amount of the leaching residue and the contents of zinc and iron contained therein are reduced.

[0025] Thus, according to the present invention, the amount of the lead / silver-containing by-product can be reduced through the pressure leaching step (S100), so that the cost of subsequent treatment for this can be reduced.

[0026] Also, according to the present invention, the contents of zinc and iron contained in the leaching residue are at a level that can be processed in a smelting furnace, which is 1 wt% less thanIt can be reduced. By subjecting the leaching residue after pressure leaching to melting treatment using a melting and smelting furnace, the recovery rate of valuable metals can be increased and the carbon emission can be reduced.

[0027] The leaching solution in the pressure leaching step (S100) contains zinc (Zn) and iron (Fe) leached from the lead / silver-containing by-product. The concentration of iron contained in the leaching solution can be about 10 to 12 g / L. Under this condition, the formation of jarosite is suppressed and the iron content in the leaching residue can be reduced to 1 wt% less than or less.

[0028] [Separation step (S200)] After the pressure leaching step (S100), a separation step (S200) for solid-liquid separation of the leaching solution and the leaching residue can be performed.

[0029] The filtered leaching solution can be sent to a purification step (S210) in a separate zinc hydrometallurgy process, and the leaching residue can be transferred to a melting treatment step (S300).

[0030] [Melting treatment step (S300)] A melting treatment step (S300) can be performed on the leaching residue generated in the separation step (S200). In the melting treatment step (S300), valuable metals such as zinc (Zn), copper (Cu), gold (Au), and silver (Ag) can be recovered from the leaching residue using a melting and smelting furnace.

[0031] In one embodiment, after charging the leaching residue into a melting and smelting furnace together with a flux and a reducing agent, melting and smelting it at a temperature above the melting point can separate valuable metals such as zinc, copper, gold, and silver from impurities.

[0032] Hereinafter, the present invention will be specifically described through experimental examples.

[0033] [Experimental example] [Examples 1 to 4 and Comparative Examples 1 and 2] The main components of the lead / silver-containing by-product used in this experimental example are lead and iron. Lead mainly exists in the form of lead sulfate (PbSO 4 4), and among the total 8.9% iron, about 1.0% exists in the form of jarosite, and the remaining about 7.9% of iron exists in the form of zinc ferrite.

[0034] The content composition of the components of the lead / silver-containing by-product used in this experimental example is described in Table 2.

Table 2

[0035] The lead / silver-containing by-product was charged into an autoclave and leached under a temperature of 130 - 150 °C and a pressure of 3.7 - 4.0 bar for 1.5 - 2.0 hours with zinc electrolysis tail liquor. The results are shown in Table 3.

Table 3

[0036] As can be confirmed from Table 3, in Examples 1 - 4, the grades of iron and zinc in the leaching residue can be reduced to less than 1 wt%, and the ratio of the leaching residue to the input lead / silver-containing by-product was 56 - 63%. Also, during pressure leaching, as the reaction time increased from 1.5 hours to 2.0 hours, a tendency for the dissolved iron to reprecipitate appeared.

[0037] On the other hand, the XRD measurement results of the leaching residue and the lead / silver-containing by-product raw material of Example 3 (leaching at 150 °C for 1.5 hours) are shown in Table 4.

Table 4

[0038] Referring to Table 4, it can be confirmed that the XRD peaks of jarosite and zinc ferrite in the leaching residue decreased significantly compared to the lead / silver-containing by-product raw material. Therefore, it is judged that the reason for the decrease in the leaching residue is that jarosite and zinc ferrite in the lead / silver-containing by-product raw material dissolved during the pressure leaching process.

[0039] [Example 5 and Comparative Examples 3 - 5] In this experimental example, the iron concentration in the leachate was varied by adjusting the solid density in the pressure leaching process, and the iron and zinc concentrations in the leach residue were measured. In this experimental example, the pressure leaching process was carried out at a temperature of 150 °C and a pressure of 3.7 - 4.0 bar for 1.5 hours, and the iron content in the lead / silver-containing by-product raw material was about 13 wt%.

Table 5

[0040] Referring to Table 5, when the iron concentration in the leachate during pressure leaching is 10 - 12 g / L, jarosite is not formed, so it is judged that the iron grade in the residue can be maintained below 1 wt%. Therefore, it is judged that in order to produce a leach residue for melting treatment in a melting furnace, the iron concentration in the leachate during pressure leaching must be maintained at 10 - 12 g / L.

[0041] In connection with this, when the iron content in the lead / silver-containing by-product raw material is high, the iron concentration in the leachate can be high, so it is necessary to adjust the solid density according to the iron content. For example, when the iron content of the lead / silver-containing by-product raw material is high, increase the amount of zinc electrolysis tail liquor input for pressure leaching, and when the iron content of the lead / silver-containing by-product raw material is low, reduce the amount of zinc electrolysis tail liquor input for pressure leaching, and the iron concentration of the leachate must be maintained at 10 - 12 g / L.

[0042] [Comparative Examples 6 - 9] In this experimental example, the results of leaching the lead / silver-containing by-product with zinc electrolysis tail liquor at atmospheric pressure (1 bar) for 12 hours at a reaction temperature of 95 °C with different solid densities are shown in Table 5.

Table 6

[0043] As can be confirmed from Table 6, only atmospheric pressure leaching cannot reduce the iron and zinc grades in the leach residue to 1 wt% less thanSince it is difficult to remove it completely, the conditions for treating the leaching residue in the melting and smelting furnace cannot be satisfied.

[0044] Thus, according to the present invention, while subjecting the lead / silver-containing by-product to pressure leaching in an autoclave, by adjusting the process temperature, process time, and iron concentration in the leaching filtrate, the contents of iron and zinc in the leaching residue can be reduced to less than 1 wt%, whereby a leaching residue that can be treated in a melting and smelting furnace can be obtained. Thereby, the recovery rate of valuable metals can be increased (Zn 83% → 85%, Cu 70 → 95%, Ag 95% → 99.8%, Au 85% → 98.5%), and the carbon emission can also be reduced.

[0045] Also, according to the present invention, by-products that must be subsequently processed can be reduced through pressure leaching using an autoclave, thereby reducing the treatment cost of the by-products.

[0046] As described above, the embodiments of the present invention have been described with reference to the attached drawings. Those having ordinary knowledge in the technical field to which the present invention pertains should be able to understand that the present invention can be implemented in other specific forms without changing its technical idea or essential features.

[0047] Therefore, each of the embodiments described above should be understood to be exemplary and non-limiting in all aspects. The scope of the present invention is indicated by the claims rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts are to be construed as being included within the scope of the present invention.

Claims

1. A pressure leaching step in which a lead / silver-containing by-product generated in the final leaching step in the zinc hydrometallurgy process is pressure-leached in an autoclave so that the contents of zinc and iron contained in the leaching residue are each less than 1% by weight; A separation step of solid-liquid separating the leaching solution and the leaching residue of the pressure leaching step; A melting treatment step of treating the leaching residue in a melting furnace, and The zinc hydrometallurgy process includes performing at least one leaching step on zinc calcine, The lead / silver-containing by-product is generated from zinc calcine in which the final leaching step of the at least one leaching step is performed, The pressure leaching step is a method for treating a by-product of a zinc hydrometallurgy process, which is performed so that the concentration of iron in the leaching solution is maintained at 10 to 12 g / L.

2. The method for treating a by-product of a zinc hydrometallurgy process according to claim 1, wherein the lead / silver-containing by-product is pressure-leached with a zinc electrolysis tail solution in the pressure leaching step.

3. The method for treating a by-product of a zinc hydrometallurgy process according to claim 1, wherein the amount of the zinc electrolysis tail solution introduced is adjusted according to the iron content of the lead / silver-containing by-product so that the concentration of iron in the leaching solution is maintained at 10 to 12 g / L.

4. The method for treating a by-product of a zinc hydrometallurgy process according to claim 1, wherein the leaching solution filtered in the separation step is fed to a purification step in the zinc hydrometallurgy process.

Images