Method for synergistically leaching leaching residues in zinc sulfide concentrate and zinc calcine

Abstract

The invention relates to a method for synergistically leaching leaching residues in zinc sulfide concentrate and zinc calcine, and belongs to the technical field of metallurgical engineering. The method comprises the following steps that (1) zinc sulfide concentrate is divided into two parts to be treated, one part of zinc sulfide concentrate is directly subjected to oxygen pressure leaching, and oxygen pressure leaching liquid and oxygen pressure leaching residues are obtained; the other part of zinc sulfide concentrate and the neutral leaching residues of the zinc calcine are subjected to reduction synergistic leaching together, and reduction leaching liquid and reduction leaching residues are obtained; (2) mixing the oxygen pressure leachate and the reduction leachate, and removing iron by using a hematite or goethite method to obtain iron slag and iron-removed liquid; (3) after the iron-removed liquid is purified, purified slag and new liquid are obtained, the new liquid is sent to an electrodeposition process, and the purified slag is sent to a recovery process to recover Cu, Cd and Co; wherein the oxygen pressure leaching residues, the reduction leaching residues and the iron residues are directly sold. According to the method, the slag rate of the oxygen pressure leaching slag can be remarkably reduced, and the leaching rate of zinc can be increased.

Description

Technical Field

[0001] This application relates to the field of metallurgical engineering technology, and in particular to a method for the co-leaching of zinc sulfide concentrate and leaching residue in zinc roasted sand. Background Technology

[0002] Yongchang's lead-zinc smelting system employs oxygen pressure leaching and fluidized bed roasting processes for zinc sulfide concentrate. Previously, the leaching residue from the zinc roasted ore was treated by incorporating it into an oxygen pressure leaching section, resulting in a high oxygen pressure leaching residue rate and failing to achieve the "three-fold" target (refinement, conversion, and processing) of the leached residue. Furthermore, the overall zinc smelting recovery rate using this process was only 95.43%. In addition, the resulting oxygen pressure leaching residue had a relatively low Zn content, but low Fe and Pb contents. Therefore, the oxygen pressure leaching residue could not be sold as either iron slag or lead slag, posing a significant challenge for the company.

[0003] Therefore, there is an urgent need to develop a process for zinc sulfide concentrate and zinc roasted sand to improve the overall recovery rate of zinc smelting, while simultaneously reducing, rendering harmless, and recycling oxygen pressure leaching residue, which is of great economic significance to enterprises. Summary of the Invention

[0004] To address or partially address the problems existing in related technologies, this application provides a method for the co-leaching of zinc sulfide concentrate and leaching residue in zinc roasted sand. Based on the complementary properties of zinc sulfide concentrate and leaching residue in zinc roasted sand, the leaching of zinc sulfide concentrate generates an acidic environment and Fe³⁺ (a strong oxidizing agent), providing the necessary conditions (high acidity + oxidizing atmosphere) for the dissolution of ZnFe₂O₄ in the intermediate leaching residue. The alkaline components such as ZnO and CaO in the intermediate leaching residue neutralize the excess H⁺ generated during zinc sulfide leaching, reducing overall acid consumption. Fe₂O₃ in the intermediate leaching residue acts as an "auxiliary oxidizing agent," being reduced to Fe²⁺ under acidic conditions, and then oxidized to Fe³⁺ by oxygen, thus promoting the oxidation of ZnS in a cyclical manner. This method not only significantly reduces the slag ratio of oxygen pressure leaching residue but also increases the zinc leaching rate, which has significant economic and environmental benefits for enterprises.

[0005] A method for co-leaching zinc sulfide concentrate and zinc roasted sand leaching residue according to this application includes the following steps: (1) The zinc sulfide concentrate is divided into two parts for processing. One part of the zinc sulfide concentrate is directly subjected to oxygen pressure leaching to obtain oxygen pressure leaching solution and oxygen pressure leaching residue. The other part of the zinc sulfide concentrate is subjected to reduction synergistic leaching together with the neutral leaching residue of zinc roasted sand to obtain reduction leaching solution and reduction leaching residue. The specific process of the reduction-co-leaching is as follows: the mass ratio of zinc sulfide concentrate to intermediate leaching residue is 1:0.5-2, the liquid-solid ratio is 4-6:1, the initial acidity is 50-100 g / L, the temperature is 80-100℃, and the reaction time is 2-4 h. (2) After mixing the oxygen pressure leaching solution and the reduction leaching solution, iron is removed by the hematite or goethite method to obtain iron slag and iron-removed liquid; (3) After the iron removal liquid is purified, purified residue and new liquid are obtained. The new liquid is sent to the electrowinning process, and the purified residue is sent to the recycling process to recover Cu, Cd and Co. Among them, oxygen pressure leaching residue, reduction leaching residue and iron slag are sold directly to external customers.

[0006] Furthermore, the specific process of oxygen pressure leaching is as follows: liquid-to-solid ratio 4.3~5:1, initial acidity 150~185g / L, pressure 1.0-1.2Mpa, kettle temperature 135~165℃, leaching time 90~120min, oxygen introduced 1200Nm / h, oxygen purity >99.95%.

[0007] Furthermore, in step (1), the proportion of zinc sulfide concentrate (-320 mesh) exceeds 85%, and the proportion of leaching residue (-200 mesh) in zinc roasted sand exceeds 85%. The mechanism of this application: Zinc sulfide concentrate is mainly composed of ZnS, with associated sulfides such as FeS2, PbS, and CuS, and small amounts of silicate impurities. Leaching it alone requires high acid consumption and oxygen partial pressure, and Fe³⁺ is easily hydrolyzed to form iron slag, which may encapsulate unreacted ZnS and reduce the leaching rate.

[0008] Zinc roasted sand leaching residue is the residue remaining after neutral leaching. Its main components are undissolved zinc compounds (such as ZnFe2O4, accounting for 60%~80% of the zinc in the residue), Fe2O3, SiO2, CaO, and small amounts of PbSO4, Ag, etc. ZnFe2O4 is a typical sparingly soluble substance, almost insoluble under neutral / weakly acidic conditions, and can only be decomposed in a high acidity (H2SO4 concentration >100g / L) or strong reducing / oxidizing environment. Its leaching alone requires high acid consumption, and impurities such as silicon and calcium easily form colloids or precipitates, affecting subsequent treatment.

[0009] The synergistic leaching of zinc sulfide concentrate and zinc roasted leaching residue is based on the complementary properties of the two materials. Leaching of zinc sulfide concentrate creates an acidic environment and Fe³⁺ (a strong oxidizing agent), providing the necessary conditions for the dissolution of ZnFe₂O₄ in the intermediate leaching residue. The alkaline components such as ZnO and CaO in the intermediate leaching residue neutralize the excess H⁺ generated during zinc sulfide leaching, reducing overall acid consumption. Fe₂O₃ in the intermediate leaching residue acts as an "auxiliary oxidizing agent," being reduced to Fe²⁺ under acidic conditions, and then oxidized to Fe³⁺ by oxygen, thus promoting the oxidation of ZnS in a cyclical manner.

[0010] The beneficial effects of this application are: Before the upgrade, the original process produced 40,000 tons / year of oxygen pressure leaching residue. If the residue storage cost is calculated at RMB 234 / ton, the annual storage cost would be approximately RMB 9.36 million. After the upgrade, the process described in this application reduces the oxygen pressure leaching residue rate from the current 60.00% to 38.00%, reduces the amount of oxygen pressure leaching residue to 25,300 tons, and reduces the annual storage cost to RMB 5.9202 million, saving approximately RMB 3.4398 million in residue storage costs per year.

[0011] Before the upgrade, the current lead-zinc oxygen pressure leaching zinc sulfide concentrate processing capacity in Yongchang, Yunnan is 117.88 t / d, and the fluidized bed furnace zinc sulfide processing capacity is 80.72 t / d. Based on the zinc sulfide concentrate containing 46% Zn, the zinc recovery rate will increase from the current 95.43% to 96.50%. The zinc metal price is 24,030 yuan / t at the current market price, and the zinc raw material pricing coefficient is 60%.

[0012] The resulting benefit is: (117.88 + 80.72) 330 (96.5-95.43) / 100 24030 0.6 / 10000 = 10,110,700 yuan / year As can be seen from the above, this application only focuses on two indicators: reducing the amount of slag and improving the zinc recovery rate. The total economic benefit is RMB 343.98 + 1011.07 = RMB 1355.05 million per year, which has significant economic and environmental significance for enterprises. Attached Figure Description

[0013] The above and other objects, features and advantages of this application will become more apparent from the more detailed description of exemplary embodiments thereof in conjunction with the accompanying drawings, wherein the same reference numerals generally represent the same components in the exemplary embodiments thereof.

[0014] Figure 1 This is a schematic diagram of the process flow in this application. Detailed Implementation

[0015] The embodiments of this application will now be described in more detail with reference to the examples. While embodiments of this application are shown in the examples, it should be understood that this application can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to make this application more thorough and complete, and to fully convey the scope of this application to those skilled in the art.

[0016] Example 1 A method for co-leaching zinc sulfide concentrate and leaching residue from zinc roasted sand, the process flow is as follows: Figure 1 As shown, it includes the following steps: (1) The zinc sulfide concentrate is divided into two parts for processing. One part of the zinc sulfide concentrate is directly leached with oxygen pressure using the waste electrolyte of wet zinc smelting to obtain oxygen pressure leaching solution and oxygen pressure leaching residue. The other part of the zinc sulfide concentrate and the neutral leaching residue of zinc roasted sand are leached together with the waste electrolyte of wet zinc smelting to obtain reduction leaching solution and reduction leaching residue. The composition of zinc sulfide concentrate is shown in Table 1 below: Table 1 The composition of the intermediate leaching residue is shown in Table 2 below: Table 2 The specific process for oxygen pressure leaching is as follows: liquid-to-solid ratio 4.5:1, initial acidity 160 g / L, pressure 1.2 MPa, kettle temperature 165℃, leaching time 90 min, oxygen flow rate 1200 Nm / h, oxygen purity > 99.95%; The specific process of reduction-co-leaching is as follows: the mass ratio of zinc sulfide concentrate to intermediate leaching residue is 1:1, the liquid-solid ratio is 5:1, the initial acidity is 80 g / L, the temperature is 85℃, and the reaction time is 3 h.

[0017] (2) After mixing the oxygen pressure leaching solution and the reduction leaching solution, iron is removed by the hematite or goethite method to obtain iron slag and iron-removed liquid; (3) After iron removal, the solution is purified by zinc powder and antimony salt to remove Cu, Cd and Co impurities from the solution, resulting in purified residue and new solution. The new solution is sent to the electrowinning process, and the purified residue is sent to the recycling process to recover Cu, Cd and Co. Among them, oxygen pressure leaching residue, reduction leaching residue and iron slag are sold directly to external customers.

[0018] Specifically, the chemical compositions of the obtained oxygen pressure leaching residue, reduction leaching residue, and iron slag are shown in Table 3 below: Table 3 In this embodiment, the zinc leaching rate was 96.6%, and the slag rate was 37.8%.

[0019] Example 2 The method for co-leaching zinc sulfide concentrate and zinc roasted sand leaching residue in Example 2 uses the same raw materials as in Example 1.

[0020] The difference lies in the specific process of oxygen pressure leaching in Example 2: liquid-to-solid ratio 4.3:1, initial acidity 150 g / L, pressure 1.0 MPa, kettle temperature 135°C, leaching time 120 min, oxygen flow rate 1200 Nm / h, oxygen purity > 99.95%; The specific process of reduction-co-leaching is as follows: the mass ratio of zinc sulfide concentrate to intermediate leaching residue is 1:0.5, the liquid-solid ratio is 6:1, the initial acidity is 50 g / L, the temperature is 100℃, and the reaction time is 4 h.

[0021] The remaining iron removal and purification processes are the same.

[0022] In this embodiment, the zinc leaching rate was 96.5%, and the slag rate was 38.2%.

[0023] Example 3 The method for co-leaching zinc sulfide concentrate and zinc roasted sand leaching residue in Example 3 uses the same raw materials as in Example 1.

[0024] The difference lies in the specific process of oxygen pressure leaching in Example 2: liquid-to-solid ratio 5:1, initial acidity 185 g / L, pressure 1.1 MPa, kettle temperature 150°C, leaching time 100 min, oxygen flow rate 1200 Nm / h, oxygen purity > 99.95%; The specific process of reduction-co-leaching is as follows: the mass ratio of zinc sulfide concentrate to intermediate leaching residue is 1:2, the liquid-solid ratio is 4:1, the initial acidity is 100g / L, the temperature is 80℃, and the reaction time is 3h.

[0025] The remaining iron removal and purification processes are the same.

[0026] In this embodiment, the zinc leaching rate was 96.4%, and the slag rate was 38.0%.

[0027] Comparative Example 1 (This comparative example is based on oxygen pressure leaching of zinc sulfide concentrate before the modification) The original process was used to process the intermediate leaching residue and zinc sulfide concentrate. The specific process was as follows: the intermediate leaching residue and zinc sulfide concentrate were mixed in a mass ratio of 3:1. After being mixed evenly, oxygen pressure leaching was carried out. The oxygen pressure leaching process conditions, iron removal process conditions and purification process conditions in Example 2 were the same as those in Example 1.

[0028] In this comparative example, the zinc leaching rate was 95.33%, and the slag rate was 60%.

[0029] Comparative Example 2 The original process was used to process the intermediate leaching residue and zinc sulfide concentrate. The specific process was as follows: the intermediate leaching residue and zinc sulfide concentrate were mixed in a mass ratio of 4:1. After being mixed evenly, oxygen pressure leaching was carried out. The oxygen pressure leaching process conditions, iron removal process conditions and purification process conditions in Example 2 were the same as those in Example 1.

[0030] In this comparative example, the zinc leaching rate was 95.30%, and the slag rate was 58.8%.

[0031] Comparative Example 2 The original process was used to process the intermediate leaching residue and zinc sulfide concentrate. The specific process was as follows: the intermediate leaching residue and zinc sulfide concentrate were mixed in a mass ratio of 5:1. After being mixed evenly, oxygen pressure leaching was carried out. The oxygen pressure leaching process conditions, iron removal process conditions and purification process conditions in Example 2 were the same as those in Example 1.

[0032] In this comparative example, the zinc leaching rate was 95.41%, and the slag rate was 58.5%.

[0033] The various embodiments of this application have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is chosen to best explain the principles, practical application, or improvement of the technology in the market, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A method for the synergistic leaching of zinc sulphide concentrates with leaching residues of zinc calcine, characterized in that, The method comprises the following steps: (1) The zinc sulfide concentrate is divided into two parts for processing, one part of the zinc sulfide concentrate is directly subjected to oxygen pressure leaching to obtain an oxygen pressure leaching solution and an oxygen pressure leaching residue; the other part of the zinc sulfide concentrate is subjected to reduction and synergistic leaching together with the neutral leaching residue of zinc calcine to obtain a reduction leaching solution and a reduction leaching residue; The specific process of the reduction and synergistic leaching is as follows: the mass ratio of the zinc sulfide concentrate to the leaching residue is 1:0.5-2, the liquid-solid ratio is 4-6:1, the initial acidity is 50-100 g / L, the temperature is 80-100 ℃, and the reaction time is 2-4 h; (2) The oxygen pressure leaching solution and the reduction leaching solution are mixed and then subjected to iron removal by using the hematite or goethite method to obtain an iron residue and a solution after iron removal; (3) The solution after iron removal is purified to obtain a purified residue and a new solution, the new solution is sent to an electrodeposition process, and the purified residue is sent to a recovery process to recover Cu, Cd and Co; The oxygen pressure leaching residue, the reduction leaching residue and the iron residue are directly sold.

2. A process for the synergistic leaching of zinc sulphide concentrates with leaching residues of zinc calcine according to claim 1, characterized in that, The specific process of the oxygen pressure leaching is as follows: the liquid-solid ratio is 4.3-5:1, the initial acidity is 150-185 g / L, the pressure is 1.0-1.2 MPa, the kettle temperature is 135-165 ℃, the leaching time is 90-120 min, 1,200 Nm / h of oxygen is introduced, and the oxygen purity is greater than 99.95%.

3. A process for the synergistic leaching of zinc sulphide concentrate with leaching residue of zinc calcine as claimed in claim 1, wherein, The zinc sulfide concentrate in the step (1) has a -320 mesh proportion of more than 85%, and the leaching residue of the zinc calcine has a -200 mesh proportion of more than 85%.

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