Method for comprehensive recovery of tellurium from lead anode slime

Abstract

The present application relates to a kind of methods for recovering tellurium from lead anode slime, and the method is specifically: lead anode slime is mixed with reducing agent and slagging agent, the mixture is put into a horizontal converter for smelting and impurity removal, by controlling smelting time and temperature, the output waste slag is poured out, and a crude antimony alloy containing gold, silver, antimony, tellurium, lead and other elements is produced; the crude antimony alloy is added with a collector in a deslagging pot, so that the tellurium element enters the antimony alkali slag to separate from gold, silver, lead and other elements; the collected antimony alkali slag is deeply deslagged, and the deslagged antimony alkali slag is put into a silver separation furnace for high-temperature smelting, the molten material is blown and slagged by adding a mixed slagging agent, and more than 40% tellurium slag is produced, which is transferred to a tellurium electrodeposition process for finished tellurium ingot production. The present application improves the recovery rate of tellurium in lead anode slime, ensures the efficient recovery of gold, silver and other precious metals, and has the advantages of clear process, simple process, low cost and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of pyrometallurgical process, and relates to a method for comprehensively recovering tellurium from lead anode slime. BACKGROUND

[0002] The lead anode slime is rich in gold, silver and antimony elements, and the traditional pyrometallurgical process mainly aims at extracting precious metals, and tellurium is taken as an accessory product in the production process. The main process is to produce precious lead through converter reduction smelting, to produce crude silver through antimony removal by blowing, and to produce tellurium slag through oxidation refining of the crude silver by a silver separating furnace, so as to enrich and recover the tellurium slag. However, in the traditional process, the tellurium element is dispersed in the slag and ash of each process, which leads to the dispersion of the tellurium element and repeated smelting in the process, thereby causing a low direct recovery rate of tellurium.

[0003] There are many lead anode slime treatment processes, and the patents for recovering tellurium elements also have different characteristics, but they can be basically divided into two categories. One is a pyrometallurgical recovery process, which gradually produces tellurium slag through lead anode slime smelting furnace pyrometallurgical smelting, such as the lead anode slime side-blown furnace reduction smelting technology proposed by Xie Zhigang of Hunan Yuteng Nonferrous Metal Co., Ltd. (CN201310197994.6). The lead anode slime is smelted and refined by blowing to remove impurities, and the precious lead is used to produce tellurium slag. The above process mainly has the following disadvantages: 1. In the lead anode slime smelting process, gold, silver, antimony, tellurium and other elements are dispersed into the ash and slag, which leads to a low recovery rate; 2. The precious lead needs high-temperature oxidation blowing to produce tellurium slag, and a large amount of tellurium is oxidized into refining ash, which leads to a low direct recovery rate of tellurium; and 3. Various types of slag need to be repeatedly smelted, which increases the production cost and lengthens the production cycle. The other is a wet recovery process, which first recovers antimony from the lead anode slime by wet method, such as the method for recovering valuable metals from lead anode slime proposed by Liu Jibo of Hunan Rare Earth Metal Material Research Institute (CN201210479038.2). The method is to acid leach antimony from the lead anode slime and then recover it by hydrolysis. The main problem of the wet process is that a large amount of wastewater is generated, the wastewater treatment cost is high, the environmental protection pressure is large, and the process operation is complex.

[0004] Therefore, the optimization and innovation of the lead anode slime production process is to comprehensively recover tellurium elements while recovering precious metals, so as to form a simple and easy high-direct-recovery-rate tellurium recovery method, which is the main problem to be solved in the technical field. SUMMARY

[0005] In order to overcome the problems and deficiencies of the prior art, the application provides a method for comprehensively recovering tellurium from lead anode slime. Compared with the prior art, the method has the characteristics of a high direct recovery rate of tellurium, a high recovery rate of gold and silver and other precious metals, a high grade of tellurium slag and easy extraction.

[0006] The technical scheme of the application is implemented as follows: A method for comprehensively recovering tellurium from lead anode slime, comprising the following process steps:

[0007] (1) The lead anode slime is mixed with a reducing agent and a slagging agent in a ratio of 100:3-5:4-6 of the anode slime, the reducing agent and the slagging agent, and the mixture is put into a horizontal converter for smelting and impurity removal. The smelting is carried out at a temperature of 1150-1250°C for 1-3 hours, and the resulting waste slag is poured out, and the crude antimony alloy is retained;

[0008] (2) The crude antimony alloy is put into a deslagging pot and melted at a temperature of 550-650°C. After melting, the stirring is started. According to the content of tellurium element, a collecting agent is added in a proportion of 1:1.8-2.5, so that the tellurium element enters the antimony alkali slag in the form of sodium tellurite, and the enrichment of the tellurium element is realized;

[0009] (3) The antimony alkali slag is deeply deslagged, and the impurities in the antimony alkali slag are further removed through a ball milling-oxygen pressure water leaching process. At the same time, the sodium tellurite is converted into water-insoluble sodium tellurate, and the tellurium is enriched in the water leaching slag;

[0010] (4) The water leaching slag is put into a silver separation furnace, melted and low-temperature blown at a temperature of 750-900°C, compressed air is introduced for low-temperature table blowing, and the first slag is poured out. The enriched molten liquid in the furnace is added with a reducing agent, sodium hydroxide and compressed air for stirring for 2 hours. Under the reducing and oxidizing atmosphere, the tellurium is converted into sodium tellurite to form a tellurium slag, and the tellurium slag is transferred to a tellurium electrodeposition process to produce qualified tellurium ingot products;

[0011] (5) The crude antimony alloy enriched with tellurium is put into an oxidizing pot to produce diantimony trioxide products that meet the industry standards. The remaining alloy is used as raw material for gold and silver production and enters the subsequent system until high-purity gold and silver products are produced;

[0012] Preferably, the reducing agent in step 1 is one or more of coke powder, coke and coal;

[0013] Preferably, the slagging agent in step 1 is one or both of flake soda and soda ash mixed with quartz sand;

[0014] Preferably, the collecting agent in step 2 is a mixture of sodium hydroxide and sodium nitrate in a proportion of 1-1.5:1;

[0015] Preferably, the crude antimony alloy produced by the reduction smelting of the lead anode slime in step 2 is added with a mixture of sodium hydroxide and sodium nitrate in a proportion according to the content of tellurium element. The mixture of sodium hydroxide and sodium nitrate is added in a surface covering manner at a temperature of 300-350°C according to the slag type to determine the collection end point. The tellurium element enters the antimony alkali slag in the form of sodium tellurite, is separated from gold, silver, lead and other elements, and the enrichment of the tellurium element is realized. After the reduction smelting of the lead anode slime, the tellurium element in the crude antimony alloy exists in the form of an element, and the tellurium element and the antimony element are separated from the alloy. Deep oxidation is carried out, and sodium hydroxide is added as a slagging agent,

[0016] The reaction equation is as follows:

[0017] Te+2NaNO3 High temperature TeO2 + 2NaNO2

[0018] TeO2 + 2NaOH High temperature Na2TeO3+H2O

[0019] According to the reaction equation, elemental tellurium reacts with sodium hydroxide under the oxidizing effect of sodium nitrate at high temperature to form sodium tellurite, which forms solid slag that floats on the surface of the alloy and is removed by a spiral slag remover.

[0020] Preferably, the ball milling-oxygen pressure water leaching process parameters in step 3 are a liquid-to-solid ratio of 5:1 and a leaching temperature of 80°C.

[0021] The production process proposed in this invention has the advantages of clear process, simple technology and low cost. Compared with the traditional lead anode mud tellurium recovery process, this invention avoids the loss of tellurium in multiple process steps, and concentrates tellurium in antimony alkali slag, which greatly improves the recovery rate of tellurium in lead anode mud and has high economic benefits.

[0022] To fully verify the feasibility of the oxygen pressure water washing process for enriching tellurium in antimony-alkali slag involved in this invention, phase analysis was performed on the antimony-alkali slag, such as... Figure 2 As shown,

[0023] from Figure 2 XPS phase analysis of antimony alkali slag revealed that tellurium in the slag mainly exists in the forms of elemental tellurium (Te) and sodium tellurite (Na2TeO3). Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the present invention;

[0025] Figure 2 This is a phase analysis diagram of the antimony-alkali slag of the present invention. Detailed Implementation

[0026] To better understand and implement this invention, the following description, in conjunction with the accompanying drawings, will further illustrate the invention.

[0027] Example 1: The following describes in detail a method for the comprehensive recovery of tellurium from lead anode mud. The elemental contents of the lead anode mud are shown in Table 1:

[0028] Table 1. Element content (%) in lead anode mud

[0029]

[0030] Note: Elements marked with * are in g / t.

[0031] The following steps were adopted: lead anode mud was mixed with coke, soda ash and quartz sand in a ratio of 100:5:3:1 and reduced and smelted at 1200℃ to produce a crude antimony alloy with a tellurium grade of 2.31% (the element content of the crude antimony alloy is shown in Table 3).

[0032] The crude antimony alloy was processed by adding a mixture of sodium hydroxide and sodium nitrate in a 1.2:1 ratio to the surface of the refining pot at 600°C, and then collecting the antimony alkali slag (the element content of the antimony alkali slag produced is shown in Table 5).

[0033] The antimony-alkali slag produced during the oxidative refining process was purified by ball milling followed by oxygen-pressure water leaching. The purified antimony-alkali slag was obtained at a liquid-solid ratio of 5:1 and a reaction temperature of 80℃. It was then fed into a silver separation furnace for reduction oxidation smelting to produce tellurium slag, which was then transferred to a tellurium electrodeposition system to produce tellurium products. After comprehensive calculation, the tellurium direct recovery rate reached 81.34% (the content of each element in the antimony-alkali slag after oxygen-pressure water leaching is shown in Table 7).

[0034] Comparative Example 1: The elemental contents of lead anode mud are shown in Table 1. Lead anode mud is mixed with reducing agent (coke powder) and slag-forming agent (soda ash) in a ratio of 100:5:3 and smelted at 1200℃ to form slag (the elemental contents of the crude antimony alloy produced are shown in Table 2).

[0035] The crude antimony alloy produced was processed in a refining pot at 600°C with only sodium hydroxide added to remove the antimony alkali slag (the element content of the antimony alkali slag produced is shown in Table 4).

[0036] For the antimony-alkali slag produced during the oxidative refining process, a water leaching process is used to remove impurities (the content of each element in the antimony-alkali slag after water leaching is shown in Table 6).

[0037] The crude antimony alloy enriched with tellurium is fed into an oxidation pot to produce antimony trioxide products that meet industry standards; the remaining alloy is used as raw material for gold and silver production and enters subsequent systems until high-purity gold and silver products are produced.

[0038] The comparison results of each process step between Example 1 and Comparative Example 1 are as follows:

[0039] Table 2 shows the % content of each element in crude antimony alloy under the condition that only reducing agent and soda ash are added during the ore blending process.

[0040]

[0041] Note: Elements marked with * are in g / t.

[0042] Table 3. Element content (%) of crude antimony alloy under the condition of adding quartz sand during ore blending.

[0043]

[0044] Note: Elements marked with * are in g / t.

[0045] A comparison of Tables 2 and 3 reveals that adding quartz sand during the lead anode mud blending stage, rather than not adding it during the blending stage, results in better slag fluidity, increased tellurium enrichment, and reduced tellurium loss.

[0046] Table 4 shows the % content of various elements in antimony-alkali slag under the condition of adding sodium hydroxide.

[0047]

[0048] Note: Elements marked with * are in g / t.

[0049] Table 5. Element content (%) of arsenic-alkali residue under conditions of sodium hydroxide and sodium nitrate addition.

[0050]

[0051] Note: Elements marked with * are in g / t.

[0052] A comparison of Tables 4 and 5 reveals that adding a mixture of sodium hydroxide and sodium nitrate to the refining pot using a surface covering method significantly improves the enrichment rate of tellurium in the antimony alkali slag compared to adding only sodium hydroxide.

[0053] Table 6. Content of each element in antimony-alkali residue after water leaching (%)

[0054]

[0055] Note: Elements marked with * are in g / t.

[0056] Table 7. Element content (%) of antimony-alkali residue after impurity removal by oxygen-pressure water leaching.

[0057]

[0058] Note: Elements marked with * are in g / t.

[0059] A comparison of Tables 6 and 7 reveals that the ball milling-oxygen pressure water immersion process resulted in a higher enrichment rate of tellurium compared to water immersion for impurity removal.

Claims

1. A method for the comprehensive recovery of tellurium from lead anode mud, characterized in that... The process includes the following steps: (1) Lead anode mud, reducing agent, and slag-forming agent are mixed in a ratio of anode mud: reducing agent: slag-forming agent of 100: 3-5: 4-6. The mixture is put into a horizontal converter for smelting and impurity removal. The smelting is carried out at a temperature of 1150-1250℃ for 1-3 hours. The waste slag is poured out and the crude antimony alloy is retained. The reducing agent is one or two of coke powder and coal. The slag-forming agent is one or two of caustic soda flakes and soda ash mixed with quartz sand. (2) The crude antimony alloy obtained in step (1) is put into a refining pot and melted at a temperature of 550-650°C. After melting, stirring is started. According to the content of tellurium in the crude antimony alloy, a collector is added at a mass ratio of tellurium to collector of 1:1.8-2.5, so that tellurium enters the antimony alkali slag in the form of sodium tellurite, thereby achieving the enrichment of tellurium. The collector is a mixture of sodium hydroxide and sodium nitrate, wherein the mass ratio of sodium hydroxide to sodium nitrate is 1-1.5:

1. The collector is added to the surface of the molten crude antimony alloy by surface covering, and the collection endpoint is determined according to the slag shape formed at a temperature of 300-350°C. (3) The antimony alkali slag obtained in step (2) is subjected to deep impurity removal by ball milling-oxygen pressure water leaching process. The liquid-solid ratio of the oxygen pressure water leaching is 5:1 and the leaching temperature is 80℃. This process further removes impurities from the antimony alkali slag and converts sodium tellurite in the antimony alkali slag into sodium tetrahydrogen tellurate which is insoluble in water, so that tellurium is enriched in the water leaching slag. (4) The water-leached slag obtained in step (3) is put into the silver separation furnace, heated to 750-900℃ to melt and carry out low-temperature blowing, and compressed air is introduced for low-temperature surface blowing to form a primary slag. The molten liquid in the furnace is enriched, a reducing agent and sodium hydroxide are added, and compressed air is introduced to stir for 2 hours. Under the reducing and oxidizing atmosphere, tellurium is converted into sodium tellurite to form tellurium slag. The tellurium slag is transferred to the tellurium electrodeposition process to produce qualified tellurium ingot products. (5) The crude antimony alloy remaining after enriching tellurium in step (2) is transferred to an oxidation pot to produce antimony trioxide products that meet industry standards; the alloy remaining after blowing to remove tellurium in the silver separation furnace in step (4) is used as a raw material for gold and silver production and enters the subsequent refining system until high-purity gold and silver products are produced.

2. The method for comprehensive recovery of tellurium from lead anode mud as described in claim 1, characterized in that... In step (2), after the lead anode mud is reduced and smelted, the tellurium element in the crude antimony alloy exists in elemental form; after the addition of the collecting agent, the elemental tellurium reacts with sodium hydroxide under the oxidation of sodium nitrate to generate sodium tellurite. The main chemical reaction equations are as follows: According to the reaction equation, elemental tellurium reacts with sodium hydroxide under the oxidizing effect of sodium nitrate at high temperature to form sodium tellurite, which forms a solid slag that floats on the surface of the alloy and is removed by a spiral slag remover.

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