A method for improving tin recovery rate in pyrometallurgical lead smelting process

Abstract

The present invention discloses a method for improving the tin recovery rate during pyrometallurgical lead smelting, relating to the field of non-ferrous metal smelting. The method involves mixing a copper-containing material with a lead concentrate in a predetermined ratio. After batching, bottom-blowing smelting, reduction smelting, and pyrometallurgical refining to remove copper and tin, a copper slag with a high tin content is produced. By introducing copper into the pyrometallurgical lead smelting process, the method achieves efficient enrichment of tin from the lead concentrate in the copper slag, thereby improving the tin recovery and enrichment rates during the pyrometallurgical lead smelting process. The copper slag with a high tin content can be used as a raw material for further tin recovery. The method is simple to operate and has good economic benefits.

Description

Technical Field

[0001] The invention belongs to the field of nonferrous metal smelting, and particularly relates to a method for improving the tin recovery rate in the process of pyrometallurgical lead smelting. Background Art

[0002] Tin is one of the earliest metals discovered and used by humans. Since the 20th century, with the development of the electronics industry, tin has gradually become an essential metal material in modern industry. However, after long-term mining, tin ore resources have gradually become depleted, and the separation of tin from tin-related ores has become a current research hotspot.

[0003] Lead and tin have similar physicochemical properties, both belonging to Group IVA in the periodic table. These two elements often coexist, but the tin content of lead concentrates is relatively low, making most domestic lead smelters refrain from tin recovery. Because tin easily oxidizes and readily forms alloys with other metals, it is dispersed throughout the lead smelting process, found in crude lead, copper dross, electrolyte, lead anode slime, and water-quenched slag, making centralized tin recovery difficult. Currently, domestic research focuses on the enrichment and recovery of tin from crude lead in reverberatory furnaces. Only a few domestic lead smelters recover tin from tin-rich slag during the pyrometallurgical refining of crude lead in reverberatory furnaces. This process, however, presents challenges such as low tin recovery rates and tin dispersion during the lead smelting process.

[0004] Therefore, the efficient recovery of tin metal in the lead smelting production process is a technical challenge in the industry. At the same time, with the rapid development of my country's lead smelting industry, the crude lead production capacity of large domestic lead smelters has reached 100,000 tons or more. Recovering metallic tin from the lead smelting process and improving the tin recovery rate have great economic value and significance. Summary of the Invention

[0005] Based on the problems existing in the background technology, the present invention overcomes the shortcomings of the existing technology and provides a method for improving the tin recovery rate in the pyrometallurgical lead smelting process. By mixing a copper-containing material with a lead concentrate in a certain ratio, and then undergoing the steps of batching, bottom blowing smelting, reduction smelting, and pyrometallurgical refining to remove copper and tin, a copper slag with a high tin content is produced, thereby achieving the purpose of enriching the majority of the tin in the lead concentrate in the copper slag and improving the tin recovery rate in the lead concentrate. The present invention is achieved through the following technical solutions:

[0006] A method for improving the tin recovery rate in the pyrometallurgical lead smelting process, the specific steps of which are as follows:

[0007] (1) First, lead concentrate, copper-containing materials, fly ash, limestone, quartz sand, lump coal and other materials are transported to the granulator through a feeding belt in a certain proportion for mixing and granulation to obtain pellets;

[0008] (2) The evenly mixed pellets are transported to the bottom-blown smelting furnace through a feeding belt for smelting to produce high-lead slag;

[0009] (3) The high-lead slag is transported to the reduction furnace through a chute, and coke or charcoal is added for reduction smelting to produce crude lead;

[0010] (4) The crude lead produced by the reduction furnace is transferred to a lead melting pot for fire refining to remove copper and tin, producing high-tin copper slag.

[0011] Furthermore, the copper content of the pellets after mixing and granulation in step (1) is controlled to be 1.8-2.0%.

[0012] Furthermore, the copper-containing material in step (1) is copper sulfide concentrate, copper oxide concentrate, matte, etc. or a mixture thereof.

[0013] Furthermore, in step (1), the slag type is controlled as follows: m(Fe) / m(SiO2)=1.6-1.8, m(CaO) / m(SiO2)=0.3-0.6.

[0014] Furthermore, in the step (1), the copper-containing material is fed using a separate feeding belt, which facilitates timely adjustment of the furnace condition.

[0015] Furthermore, in step (2), the smelting temperature of the bottom blowing furnace is controlled at 1000-1100°C.

[0016] Furthermore, in step (3), the reduction smelting temperature is controlled at 1150-1250°C.

[0017] The main mechanism involved in the method for improving the tin recovery rate in the pyrometallurgical lead smelting process described in the present invention is as follows:

[0018] During the crude lead production process, the copper content in the mixed ore is increased by adding a certain proportion of copper-containing materials, thereby increasing the copper content in the lead liquid. Copper has a strong affinity with elements such as arsenic, antimony, and tin, and can form high-melting-point intermetallic compounds such as Cu3As, Cu5As, Cu2Sb, and Cu6Sn5. The binding energy of the intermetallic compounds is greater than the solubility energy of arsenic, antimony, and tin in the lead liquid phase. During the crude lead pyrorefining process, the high-melting-point intermetallic compounds such as Cu3As, Cu5As, Cu2Sb, and Cu6Sn5 are precipitated from the lead liquid, and tin is enriched in the copper slag together with the copper, arsenic, antimony, and other elements, thereby achieving the purpose of efficiently enriching tin in the lead concentrate and improving the recovery rate.

[0019] The beneficial effects of the present invention are:

[0020] (1) This process is simple to operate. Without changing the main production process of crude lead, only the ingredients in the production process are optimized. The production process is easy to implement and the production cost is low.

[0021] (2) This process can achieve efficient enrichment and recovery of tin in lead concentrate. The recovery rate of tin in lead concentrate can be increased from 54% to more than 73%. Tin is mainly enriched in high-tin copper slag, and the tin content in high-tin copper slag can reach 1.28%;

[0022] (3) This process has a high level of resource utilization, and the high-tin copper slag produced can be used as raw material for further tin recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0025] Example 1:

[0026] Lead concentrate, copper-containing materials, fly ash, limestone and quartz sand are mixed and granulated to obtain mixed pellets. The element analysis of the mixed pellets is shown in the following table:

[0027]

[0028] The mixed pellets are fed into the bottom-blown furnace through the feeding belt for smelting. During the smelting process, the pellet feeding rate is 48t / h and the oxygen-to-material ratio is controlled at 115Nm 3 / t, the smelting temperature is controlled at 1000℃, the smelting time is controlled at 1.5h, and high-lead slag is released after the smelting is completed; the high-lead slag enters the reduction furnace through the chute for reduction smelting, the reduction smelting temperature is controlled at 1200℃, the amount of aromatic carbon added is controlled at 2t / h, the reduction smelting time is controlled at 2h, and the reduction slag and crude lead are released after the reduction smelting is completed; the crude lead in the reduction furnace is transported to the crude lead fire refining process for fire refining, the crude lead is first hoisted into the lead melting pot for melting, and then multiple The surface slag is removed by secondary slag pressing and slag removal operations. When the lead liquid temperature drops to 500℃, it is hoisted into a mixer for stirring to form a vortex. Lead oxide slag is added to the vortex and stirred for 0.5h. The thin slag is removed. After the thin slag is removed, the butt electrode is added to cool it down. In order to speed up the operation, water is sprayed on the surface of the lead liquid to cool it down and gradually reduce the temperature of the lead liquid to 330℃. The solidified slag on the surface is removed. The high-tin copper slag obtained in the fire refining process can be used as raw material for further tin recovery.

[0029] After the above process, the tin content in crude lead, lead anode plate and high-tin copper slag is as follows:

[0030]

[0031] Example 2:

[0032] Lead concentrate, copper-containing materials, fly ash, limestone and quartz sand are mixed and granulated to obtain mixed pellets. The element analysis of the mixed pellets is shown in the following table:

[0033]

[0034] The mixed pellets are fed into the bottom-blown furnace through a feeding belt for smelting. During the smelting process, the pellet feeding rate is 45t / h and the oxygen-to-material ratio is controlled at 118Nm 3 / t, the smelting temperature is controlled at 1000℃, the smelting time is controlled at 1.5h, and high-lead slag is released after the smelting is completed; the high-lead slag enters the reduction furnace through the chute for reduction smelting, the reduction smelting temperature is controlled at 1250℃, the amount of aromatic carbon added is controlled at 1.8t / h, the reduction smelting time is controlled at 2h, and the reduction slag and crude lead are released after the reduction smelting is completed; the crude lead in the reduction furnace is transported to the crude lead fire refining process for fire refining, the crude lead is first hoisted into the lead melting pot for melting, and then melted. The surface slag is removed by repeated slag pressing and slag removal operations. When the lead liquid temperature drops to 480℃, it is hoisted into a mixer for stirring to form a vortex. Lead oxide slag is added to the vortex and stirred for 0.5h. The thin slag is removed. After the thin slag is removed, the butt electrode is added to cool it down. In order to speed up the operation, water is sprayed on the surface of the lead liquid to cool it down and gradually reduce the lead liquid temperature to 340℃. The solidified slag on the surface is removed. The high-tin copper slag obtained in the fire refining process can be used as raw material for further tin recovery.

[0035] After the above process, the tin content in crude lead, lead anode plate and high-tin copper slag is as follows:

[0036]

[0037] Example 3:

[0038] Lead concentrate, copper-containing materials, fly ash, limestone and quartz sand are mixed and granulated to obtain mixed pellets. The element analysis of the mixed pellets is shown in the following table:

[0039]

[0040] The mixed pellets are fed into the bottom-blown furnace through the feeding belt for smelting. During the smelting process, the pellet feeding rate is 50t / h and the oxygen-to-material ratio is controlled at 118Nm 3 / t, the smelting temperature is controlled at 1050℃, the smelting time is controlled at 1.5h, and high-lead slag is released after the smelting is completed; the high-lead slag enters the reduction furnace through the chute for reduction smelting, the reduction smelting temperature is controlled at 1230℃, the amount of aromatic carbon added is controlled at 2.0t / h, the reduction smelting time is controlled at 2h, and the reduction slag and crude lead are released after the reduction smelting is completed; the crude lead in the reduction furnace is transported to the crude lead fire refining process for fire refining, the crude lead is first hoisted into the lead melting pot for melting, and then melted. The surface slag is removed by repeated slag pressing and slag removal operations. When the lead liquid temperature drops to 500℃, it is hoisted into a mixer for stirring to form a vortex. Lead oxide slag is added to the vortex and stirred for 0.5h. The thin slag is removed. After the thin slag is removed, the butt electrode is added to cool it down. In order to speed up the operation, water is sprayed on the surface of the lead liquid to cool it down and gradually reduce the lead liquid temperature to 335℃. The solidified slag on the surface is removed. The high-tin copper slag obtained in the fire refining process can be used as raw material for further tin recovery.

[0041] After the above process, the tin content in crude lead, lead anode plate and high-tin copper slag is as follows:

[0042] .

Claims

1. A method for improving the tin recovery rate in the pyrometallurgical lead smelting process, characterized in that: The specific steps are as follows: (1) First, lead concentrate, copper-containing materials, fly ash, limestone, quartz sand, and lump coal are conveyed to a granulator through a feeding belt in a certain proportion for mixing and granulation to obtain pellets; (2) transporting the evenly mixed pellets to a bottom-blown smelting furnace through a feeding belt for smelting to produce high-lead slag; (3) The high-lead slag is transported to the reduction furnace through a chute, and coke or charcoal is added for reduction smelting to produce crude lead; (4) The crude lead produced by the reduction furnace is transferred to a lead melting pot for pyro-refining to remove copper and tin, thereby producing a high-tin copper slag; The copper content of the pellets after mixing and granulation in the step (1) is controlled to be 1.8-2.0%.

2. The method for improving the tin recovery rate in the pyrometallurgical lead smelting process according to claim 1, wherein: The copper-containing material in step (1) is copper sulfide concentrate, copper oxide concentrate, matte or a mixture thereof.

3. The method for improving the tin recovery rate in the pyrometallurgical lead smelting process according to claim 1, wherein: In the step (1), the slag type is controlled as follows: m(Fe) / m(SiO2)=1.6~1.8, m(CaO) / m(SiO2)=0.3~0.

6.

4. The method for improving the tin recovery rate in the pyrometallurgical lead smelting process according to claim 1, wherein: In the step (1), the copper-containing material is fed using a separate feeding belt, which facilitates timely adjustment of the furnace condition.

5. The method for improving the tin recovery rate in the pyrometallurgical lead smelting process according to claim 1, characterized in that: In the step (2), the smelting temperature of the bottom blowing furnace is controlled at 1000-1100°C.

6. The method for improving the tin recovery rate in the pyrometallurgical lead smelting process according to claim 1, characterized in that: In the step (3), the reduction smelting temperature is controlled at 1150-1250°C.

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