A method for improving the leaching rate of indium in zinc oxide fume by using an oxidizing agent

Abstract

This invention belongs to the field of metallurgical technology and discloses a method for improving the indium leaching rate from zinc oxide flue dust using an oxidant, wherein the oxidant is either ozone or hydrogen peroxide. Adding an oxidant during the zinc oxide flue dust leaching process provides an oxidizing atmosphere, enhances the acid leaching reaction, and thus achieves the purpose of increasing the indium leaching rate from the zinc oxide flue dust. Ozone generates oxygen after the oxidation reaction, while hydrogen peroxide generates both water and oxygen after the oxidation reaction, both of which can continue to oxidize without introducing new impurities. Application results show that the indicators of the zinc oxide flue dust leaching stage are significantly improved, the indium content in lead slag is effectively controlled, and the indium leaching rate from the zinc oxide flue dust can reach over 90%.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, and more specifically relates to a method for improving the indium leaching rate in zinc oxide dust using an oxidizing agent. Background Technology

[0002] Currently, when zinc sulfide concentrate is leached using direct pressure leaching (DPL), the resulting slag, which contains high levels of zinc and valuable metals, is sent to the lead system's pyrometallurgical smelting furnace for recovery. Ultimately, zinc, indium, and small amounts of lead and silver enter the zinc oxide flue dust and are returned to the zinc system for reuse. The zinc and indium are recovered after leaching, while the small amounts of lead and silver in the zinc oxide flue dust remain in the slag and are then returned to the lead system for recovery. The indium leaching rate in the zinc oxide flue dust determines how much indium metal can be recovered; an insufficient indium leaching rate is detrimental to the comprehensive recovery of indium metal.

[0003] However, due to the strong reducing power of zinc oxide dust and its zinc content of 5-10%, the indium leaching rate during acid leaching is insufficient, only 60-70%. The tailings lead sludge contains 1000-1500 g / t of indium, meaning a significant amount of indium metal remains unleached, affecting indium recovery. Furthermore, because the indium recovery system is closely linked to the zinc system, oxidants that introduce new impurities cannot be used. Therefore, a relatively pure oxidant is needed to counteract the reducing power of zinc oxide dust, enhance the acid leaching reaction, and improve the indium leaching rate from the zinc oxide dust.

[0004] Therefore, how to provide a method for improving the indium leaching rate in zinc oxide flue gas using oxidants is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In order to overcome the shortcomings and deficiencies of the prior art, the present invention provides a method for improving the indium leaching rate in zinc oxide flue dust using an oxidant.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A method for increasing the indium leaching rate in zinc oxide fumes using an oxidizing agent includes the following steps: (1) Add waste electrolyte and oxidant to zinc oxide flue dust, perform neutral leaching, and then filter under pressure to obtain filter residue and medium leaching filtrate. The medium leaching filtrate is then returned to neutralization. (2) The filter residue obtained in step (1) is pulped, and waste electrolyte is added for acid washing. The filter residue and filtrate are obtained by pressure filtration. The filtrate is returned to the neutral leaching in step (1). (3) Add concentrated sulfuric acid and oxidant to the filter residue obtained in step (2) for a first-stage leaching, then filter by pressure to obtain a first-stage acid leaching residue and a first-stage acid leaching filtrate; add iron powder to the first-stage acid leaching filtrate to remove Fe 3+ Reduced to Fe2+ Bone glue, flocculant, and activated carbon are added for desiliconization and impurity removal; (4) Add concentrated sulfuric acid and oxidant to the first stage of acid leaching residue, carry out second stage leaching, and then filter under pressure to obtain second stage acid leaching filtrate and lead slag. The second stage acid leaching filtrate is returned to the neutral leaching in step (1), and the lead slag is sent to the lead plant.

[0008] Preferably, the zinc oxide dust in step (1) is zinc-containing dust obtained by a fuming furnace after zinc-containing materials are smelted in a lead smelting furnace, with a zinc content of 5-10%; the zinc-containing materials include zinc-containing waste residue produced during the production of zinc ingots from zinc sulfide concentrate.

[0009] Preferably, the waste electrolyte in step (1) is the electrolyte produced during the zinc electrowinning process in the production of zinc ingots from zinc sulfide concentrate. Its components include zinc sulfate and dilute sulfuric acid, with an acid content of 150~160g / L and a zinc content of 45~50g / L.

[0010] Preferably, the concentrated sulfuric acid has a mass fraction of 92.5%.

[0011] Preferably, the oxidant is either ozone or hydrogen peroxide.

[0012] Preferably, the volume fraction of the hydrogen peroxide is 30%.

[0013] Preferably, the amount of hydrogen peroxide used in neutral leaching is 40 mL / kg zinc oxide dust, and the amount used in both the first-stage and second-stage leaching is 60 mL / kg zinc oxide dust.

[0014] Preferably, the amount of ozone used in neutral leaching is 0.3 g / min·L solution, and the amount used in both the first-stage and second-stage leaching is 0.6 g / min·L solution.

[0015] Preferably, the initial acid concentration of the leaching in step (3) is 180 g / L and the final acid concentration is 60-70 g / L.

[0016] Preferably, the initial acid concentration of the two-stage leaching in step (4) is 200-260 g / L, and the final acid concentration is 140-160 g / L.

[0017] The beneficial effects of the above technical solution are as follows: the first stage of leaching mainly controls the final acid in order to prepare a solution that meets the requirements for the subsequent stage; the second stage of leaching needs to control the initial acid to ensure the leaching rate and avoid the final acid being too high and affecting the subsequent treatment of the solution. Therefore, an upper limit for the initial acid in the second stage of leaching is set, and an oxidant is added to enhance the reaction.

[0018] As can be seen from the above technical solution, compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for improving the indium leaching rate from zinc oxide flue dust using an oxidant. An oxidant is added during the zinc oxide flue dust leaching process to provide an oxidizing atmosphere, enhancing the acid leaching reaction and thus increasing the indium leaching rate. Ozone generates oxygen after the oxidation reaction, and hydrogen peroxide generates both water and oxygen after the oxidation reaction; both can continue to oxidize without introducing new impurities. Application results show that the indicators of the zinc oxide flue dust leaching stage are significantly improved, the indium content in lead slag is effectively controlled, and the indium leaching rate from zinc oxide flue dust can reach over 90%. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0020] Figure 1 This is a process flow diagram of the present invention.

[0021] Figure 2 This is a graph showing the relationship between ozone flow rate and indium leaching rate in the two-stage leaching operation of Example 1.

[0022] Figure 3 This is a graph showing the relationship between the amount of hydrogen peroxide added and the indium leaching rate in the two-stage leaching process of Example 2. Detailed Implementation

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] In this embodiment of the invention, the zinc oxide dust is zinc-containing dust obtained from a fuming furnace after zinc-containing materials have been smelted in a lead smelting furnace; the zinc-containing materials include zinc-containing waste residue produced during the production of zinc ingots from zinc sulfide concentrate. The waste electrolyte is the electrolyte produced during the zinc electrowinning process in the production of zinc ingots from zinc sulfide concentrate, and its components include zinc sulfate and dilute sulfuric acid, with an acid content of 150-160 g / L and a zinc content of 45-50 g / L. The concentrated sulfuric acid has a mass fraction of 92.5%.

[0025] Example 1 The composition of the oxidizing dust used is shown in Table 1. The Zn mentioned is the total zinc in the zinc oxide dust, which includes metallic Zn.

[0026] Table 1 Zinc oxide dust analysis data

[0027] A method for increasing the indium leaching rate in zinc oxide fumes using an oxidizing agent includes the following steps: (1) Add waste electrolyte and ozone to zinc oxide dust with a zinc content of 6.37% and ozone dosage of 0.3 g / min·L solution for neutral leaching, then filter under pressure to obtain filter residue and intermediate leaching filtrate. The intermediate leaching filtrate is then returned to neutralization. (2) The filter residue obtained in step (1) is pulped, and waste electrolyte is added for acid washing. The filter residue and filtrate are obtained by pressure filtration. The filtrate is returned to the neutral leaching in step (1). (3) Add concentrated sulfuric acid and ozone to the filter residue obtained in step (2) for a first-stage leaching, then filter by pressure to obtain a first-stage acid leaching residue and a first-stage acid leaching filtrate; the initial acid concentration of the first-stage leaching is 180 g / L, and the final acid concentration is 66.71 g / L; add iron powder to the first-stage acid leaching filtrate to remove Fe 3+ Reduced to Fe 2+ Bone glue, flocculant, and activated carbon are added for desiliconization and impurity removal; (4) Add concentrated sulfuric acid and ozone to the first stage of acid leaching residue for second stage leaching, and then filter under pressure to obtain the second stage acid leaching filtrate and lead slag. The second stage acid leaching filtrate is returned to the neutral leaching in step (1), and the lead slag is sent to the lead plant.

[0028] The ozone used was generated from air using an ozone generator at a concentration of 0.03% (300 mg / L) and a maximum flow rate of 4 L / min. It was directly introduced into the beaker using a φ15 cm aeration disc, and no stirrer was used during the reaction. The ozone concentration was adjusted to 0.03% during the experiment, and the ozone addition was adjusted by regulating the ozone flow rate. The final acid concentration for the two-stage leaching operation was controlled at 150 g / L. Each experimental group treated 500 g of zinc oxide fume. The experimental results are shown in Table 2. The relationship between ozone flow rate and indium leaching rate in the two-stage leaching operation is shown in the graph below. Figure 2 As shown. By Figure 2 It can be seen that, under the condition of controlling the final acid concentration of 150 g / L in the acid leaching reaction, the indium leaching rate gradually increases with the increase of ozone addition, eventually stabilizing between 88% and 89%. The optimal ozone addition flow rate is 3.0 L / min, and the concentration is 0.03%, i.e., the dosage is 0.6 g / min·L solution. The indium leaching rate can be further improved by increasing the acidity.

[0029] Table 2 Ozone Experimental Data

[0030] Example 2 A method for increasing the indium leaching rate in zinc oxide fumes using an oxidizing agent includes the following steps: (1) Add waste electrolyte and hydrogen peroxide to zinc oxide dust with a zinc content of 7.37%, and the amount of hydrogen peroxide is 40 mL / kg of zinc oxide dust. Perform neutral leaching, and then filter press to obtain filter residue and intermediate leaching filtrate. The intermediate leaching filtrate is returned to neutralization. (2) The filter residue obtained in step (1) is pulped, and waste electrolyte is added for acid washing. The filter residue and filtrate are obtained by pressure filtration. The filtrate is returned to the neutral leaching in step (1). (3) Add concentrated sulfuric acid and hydrogen peroxide to the filter residue obtained in step (2) for a first-stage leaching, followed by pressure filtration to obtain a first-stage acid leaching residue and a first-stage acid leaching filtrate; the initial acid concentration of the first-stage leaching is 180 g / L, and the final acid concentration is 62.96 g / L; add iron powder to the first-stage acid leaching filtrate to remove Fe 3+ Reduced to Fe 2+ Bone glue, flocculant, and activated carbon are added for desiliconization and impurity removal; (4) Add concentrated sulfuric acid and hydrogen peroxide to the first stage of acid leaching residue, carry out the second stage leaching, and then filter under pressure to obtain the second stage acid leaching filtrate and lead slag. The second stage acid leaching filtrate is returned to the neutral leaching in step (1), and the lead slag is sent to the lead plant.

[0031] The hydrogen peroxide used was an analytical grade 30% aqueous solution. The experiment involved adjusting the amount of hydrogen peroxide added to verify whether it promoted the leaching rate of zinc oxide dust. The final acid concentration in the two-stage leaching process was controlled at 150 g / L, and 500 g of zinc oxide dust was treated in each experimental group. The experimental results are shown in Table 3. The relationship between the amount of hydrogen peroxide added in the two-stage leaching process and the indium leaching rate is shown in the graph below. Figure 3 As shown. By Figure 3 It can be seen that, under the condition of controlling the final acid concentration of 150 g / L in the acid leaching reaction, the indium leaching rate gradually increases with the increase of hydrogen peroxide addition, eventually stabilizing at over 91%. The optimal amount of hydrogen peroxide is 60 mL / kg zinc oxide dust.

[0032] Table 3. Experimental data for hydrogen peroxide

[0033] Table 4. Indium content in lead slag after hydrogen peroxide treatment.

[0034] As shown in Table 4, this invention can improve the leaching rate of indium and zinc in zinc oxide flue dust. The zinc content in the tailings is all below 2%, and the product obtained after the hydrogen peroxide reaction is water, which will not introduce new impurities and will not affect the subsequent zinc or indium recovery system.

[0035] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. The solutions disclosed in the embodiments are described simply because they correspond to the methods disclosed in the embodiments; relevant parts can be found in the method section.

[0036] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for increasing the indium leaching rate in zinc oxide flue dust using an oxidizing agent, characterized in that, Includes the following steps: (1) Add waste electrolyte and oxidant to zinc oxide flue dust, perform neutral leaching, and then filter under pressure to obtain filter residue and medium leaching filtrate. The medium leaching filtrate is then returned to neutralization. (2) The filter residue obtained in step (1) is pulped, and waste electrolyte is added for acid washing. The filter residue and filtrate are obtained by pressure filtration. The filtrate is returned to the neutral leaching in step (1). (3) Add concentrated sulfuric acid and oxidant to the filter residue obtained in step (2) for a first-stage leaching, then filter by pressure to obtain a first-stage acid leaching residue and a first-stage acid leaching filtrate; add iron powder to the first-stage acid leaching filtrate to remove Fe 3+ Reduced to Fe 2+ Bone glue, flocculant, and activated carbon are added for desiliconization and impurity removal; (4) Add concentrated sulfuric acid and oxidant to the first stage of acid leaching residue, carry out second stage leaching, and then filter under pressure to obtain second stage acid leaching filtrate and lead slag. The second stage acid leaching filtrate is returned to the neutral leaching in step (1), and the lead slag is sent to the lead plant.

2. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 1, characterized in that, The zinc oxide dust mentioned in step (1) is zinc-containing dust obtained by a fuming furnace after zinc-containing materials are smelted in a lead smelting furnace, with a zinc content of 5-10%; the zinc-containing materials include zinc-containing waste residue produced during the production of zinc ingots from zinc sulfide concentrate.

3. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 1, characterized in that, The waste electrolyte mentioned in step (1) is the electrolyte produced during the zinc electrowinning process in the production of zinc ingots from zinc sulfide concentrate. Its components include zinc sulfate and dilute sulfuric acid, with an acid content of 150~160g / L and a zinc content of 45~50g / L.

4. The method for increasing the indium leaching rate in zinc oxide flue dust using an oxidant according to claim 1, characterized in that, The concentrated sulfuric acid has a mass fraction of 92.5%.

5. The method for increasing the indium leaching rate in zinc oxide flue dust using an oxidant according to claim 1, characterized in that, The oxidant is either ozone or hydrogen peroxide.

6. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 5, characterized in that, The hydrogen peroxide has a volume fraction of 30%.

7. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 5, characterized in that, The amount of hydrogen peroxide used in neutral leaching is 40 mL / kg zinc oxide dust, and the amount used in both the first-stage and second-stage leaching is 60 mL / kg zinc oxide dust.

8. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 5, characterized in that, The amount of ozone used in neutral leaching is 0.3 g / min·L solution, and the amount used in both the first and second stage leaching is 0.6 g / min·L solution.

9. The method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 1, characterized in that, The initial acid concentration of the leaching in step (3) is 180 g / L, and the final acid concentration is 60-70 g / L.

10. A method for increasing the indium leaching rate in zinc oxide flue gas using an oxidant according to claim 1, characterized in that, The initial acid concentration of the two-stage leaching in step (4) is 200-260 g / L, and the final acid concentration is 140-160 g / L.

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