A high-efficiency converting method and converting device for lead matte

Abstract

The present invention discloses an efficient blowing method and blowing device for lead matte, a lead matte blowing device comprising a hollow furnace, a feeding port being provided on the furnace, a copper port and a slag port being provided on the lower portion of the furnace from bottom to top, a lifting device being provided above the furnace, a top-blowing lance being fixedly connected to a main shaft of the lifting device in the vertical direction, and a side-blowing lance being provided on the upper portion of the furnace. The blowing method of the present invention can achieve deep separation of copper and lead, and the blowing product is crude copper with extremely low lead content, and is rich in precious metals such as Ag, thereby increasing the value of the lead matte. In the blowing method of the present invention, most of the Pb element volatilizes to smoke dust, which can be returned to the lead smelting system for further extraction and recovery. The blowing slag can be sent to a cement plant as raw material after copper is extracted from the slag, and the sulfur-containing flue gas can be sent to acid production after purification. The entire process is pollution-free to the environment.

Description

Technical Field

[0001] The present invention relates to the field of pyrometallurgical copper smelting, and in particular to a high-efficiency converting method and converting device for lead matte. Background Art

[0002] Lead matte is an intermediate product produced during the initial fire refining of crude lead, containing high levels of copper and lead. It primarily contains metal sulfides such as Cu2S, PbS, and FeS, as well as certain amounts of elements such as As, Sb, and Ag. The composition of lead matte varies significantly depending on the initial fire refining process. One method involves decoppering lead in a lead smelting pot, producing a copper slag containing 10-15% copper. During the treatment of the copper slag, soda ash, iron filings, pyrite, and coke are typically added to produce lead matte, crude lead, and slag. This lead matte typically contains the following components by mass: Cu 25-55%, Fe 10-20%, Pb 10-35%, and S 8-13%. Another method involves decoppering crude lead in a continuous refining furnace. This process directly produces lead matte containing 45-55% copper, approximately 20% lead, and very low levels of iron and sulfur, with the majority of the copper and lead present as alloys. At present, the processing technology of valuable metals in lead matte is usually divided into two types: wet method and pyrolysis method. The wet smelting process mainly includes acid leaching, chloride leaching, ammonia leaching, etc. Since the wet treatment will produce a large amount of lead slag during leaching, solid-liquid separation and subsequent waste slag disposal are more difficult, so it is less used.

[0003] Currently, lead smelters primarily use pyrometallurgical processes to process lead matte, which can be broadly categorized as traditional pyrometallurgical converting and converter bath converting. Traditional pyrometallurgical processes, such as reverberatory furnaces and blast furnaces, present several challenges: first, low efficiency; converting a single batch of lead matte typically takes three to seven days; second, high energy consumption, particularly with reverberatory furnaces boasting a thermal efficiency of only around 30%; third, low levels of mechanization and automation; and fourth, inability to fully separate copper from lead, requiring two or three further steps to produce blister copper. In recent years, some companies have adopted methods such as oxygen-enriched bottom blowing in converters. These methods place lead matte into the furnace, along with a certain amount of siliceous flux and granular coal, while simultaneously blowing air into the bath. This oxidizes impurities and causes them to rise to form slag, leaving the high-grade matte to sink to the bottom layer. Further processing is required to produce blister copper, and there are no reports of direct blister copper production.

[0004] Due to the complex chemical composition of lead matte, an ideal treatment process has not yet been developed, which cannot meet the current requirements of low-carbon, environmentally friendly and efficient solid waste disposal. This has always been a difficult problem for the comprehensive recovery of lead smelting resources.

[0005] The Chinese patent with publication number CN113817924A discloses a method for producing crude copper by smelting copper slag. The method of the invention has high smelting intensity, can efficiently process copper slag and produce crude lead and crude copper products in one step, reducing the difficulty of subsequent process treatment. The raw material processed by the method of the invention is copper slag. The method of the invention melts copper and lead in different areas separately. First, it can separate the flue gas in the smelting area and the upper part of the blowing area, so that the two spaces can control the gas partial pressure separately and realize the functions of different stages; second, it can prevent the smelting slag and copper blowing slag from miscible, and realize the efficient recycling of copper-containing waste slag; third, it can realize the flow of matte to the blowing area; therefore, through the method of zoned smelting, the separation effect of each component is better and the metal recovery rate is high. In the method of the invention, after smelting, the temperature of the lead liquid layer is 700-800℃, which can reduce the copper content in crude lead and increase the copper recovery rate. The above-mentioned disclosed patents have the following defects:

[0006] (1) The raw material processed in the above-mentioned patent disclosure is copper slag, which is melted on the left side of the device and then enters the blowing area on the right side. The copper slag enters the blowing area, and therefore, only top blowing alone can be used for blowing and slagging;

[0007] (2) The dual-zone furnace structure adopted in the above-mentioned disclosed patent is difficult to operate during the furnace start-up phase. When the side-blowing smelting furnace is started, problems such as insufficient furnace heat and coke accumulation are prone to occur. Simply relying on the side-blowing spray gun to increase the temperature of the area below the tuyere is limited.

[0008] (3) During the smelting process of the dual-zone furnace used in the above-mentioned disclosed patent, when the raw materials or furnace conditions fluctuate, such as when the molten pool temperature is low, the passage in the retaining wall area is prone to blockage, and the retaining wall structure is easily corroded by long-term hot scouring. It is difficult to repair in a hot state and the furnace needs to be shut down. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to provide a high-efficiency blowing method and blowing device for lead matte in view of the shortcomings of the existing technology, so as to realize rapid slag formation, achieve deep impurity removal of lead matte, and produce high-grade crude copper, thereby solving the technical problems of incomplete copper-lead separation and low smelting efficiency in the lead matte processing process.

[0010] In order to solve the above technical problems, the technical solution adopted in the present invention is: a lead matte blowing device, comprising a hollow furnace cylinder, a charging port is provided on the furnace cylinder, a copper port and a slag port are provided at the lower part of the furnace cylinder from bottom to top, a lifting device is installed above the furnace cylinder, the main shaft of the lifting device in the vertical direction is fixedly connected to a top-blowing lance, a side-blowing lance is installed on the upper part of the furnace cylinder, the side-blowing lance includes a water-cooling air port, and the outer side of the water-cooling air port is coated with refractory material.

[0011] There is currently no precedent for using a side-blowing lance to directly blow lead matte in the industry. The main reason is that the side-blowing tuyere is protected by a water jacket, and matte contains a high sulfur content. If the matte melt directly contacts the copper water jacket, it is prone to explosion. Therefore, the present application coats the outside of the water jacket with refractory material to prevent the matte from overflowing onto the furnace when the liquid level is high and directly contacting the copper water jacket, thereby avoiding explosion. Top-blowing lances rely on gas cooling and lack a water jacket structure, eliminating the risk of explosion. The present invention uses a top-blowing lance to achieve deep impurity removal of matte, producing high-grade blister copper.

[0012] The lifting device can realize free switching of the injection position among the gas area, slag layer and matte layer.

[0013] In a preferred embodiment of the present invention, the side-blowing lance is 1000-1200 mm above the furnace bottom. The side-blowing lance mainly sprays the slag and matte mixed area to achieve the slag-making process.

[0014] In a preferred embodiment of the present invention, a plurality of side-blowing lances are installed, and the side-blowing lances are arranged in two layers of high and low. The two layers of side-blowing lances can greatly increase the stirring kinetic energy and achieve a rapid slag-forming reaction.

[0015] In a preferred embodiment of the present invention, the side-blowing lance is a concentric sleeve lance. The side-blowing lance can spray oxygen-enriched air alone or a mixture of coal gas / pulverized coal and oxygen-enriched air to supplement heat to the melt.

[0016] In a preferred embodiment of the present invention, the top-blowing lance is a concentric sleeve lance. The top-blowing lance can spray oxygen-enriched air alone or a mixture of coal gas / pulverized coal and oxygen-enriched air to supplement heat to the melt.

[0017] In a preferred embodiment of the present invention, the lowest position of the top-blowing lance is 400-500 mm from the furnace bottom. The top-blowing lance mainly sprays the matte layer to achieve the copper-making process while preventing the airflow from eroding the refractory material at the furnace bottom.

[0018] In a preferred embodiment of the present invention, a lead opening is provided below the copper opening, and the lead opening, the copper opening and the slag opening are staggered in the vertical direction.

[0019] The present invention also discloses a lead matte converting method, comprising the following steps:

[0020] S1. Mixing lead matte and slag-forming flux in a ratio of 100:4-6 and adding the mixture to the lead matte converting device according to claim 1; performing a primary converting operation using a side-blowing lance; and forming a matte layer and a slag layer from bottom to top in the furnace after the primary converting operation.

[0021] S2. A top-blowing lance is used to descend to the matte layer, and secondary blowing is performed simultaneously with the side-blowing lance, so that a blister copper layer and a slag layer are formed from bottom to top in the furnace.

[0022] In the primary blowing process, the lead matte and slag-forming flux such as silica are mixed and added to the blowing device through the top feeding port. The side-blowing lance is turned on for oxidative blowing. After the granular raw materials are melted, some impurities such as Pb, As, and Sb are volatilized into smoke, and some are oxidized together with the Fe element to form slag and float up. Valuable metals such as Cu and Ag are enriched in the matte phase and sink to the lower layer. This process achieves the enrichment of Cu and the removal of some impurities.

[0023] During the secondary blowing process, the top-blowing lance is lowered to the matte layer to inject oxygen-rich air for the second stage of blowing. Impurity elements in the matte are fully oxidized and enter the smoke or blowing slag. The sulfur element is oxidized and enters the flue gas. After cooling and purification, it is sent to the acid production system, generating liquid blister copper rich in precious metals, which sinks below the matte layer. When the liquid level reaches a predetermined height, the lower copper outlet is opened to release the copper liquid.

[0024] The raw material lead matte contains Cu 25-55%, Pb 10-35%, Fe 8-12% and Ag 800-2000g / t.

[0025] In a preferred embodiment of the present invention, during the primary blowing in S1, oxygen-enriched and pulverized coal are blown in via a side-blowing lance, with a pulverized coal ratio of 7-10%. The heat required for blowing is partially provided by the heat released by oxidation of metal sulfides in the feedstock, and the remainder is provided by combustion of the pulverized coal blown in via the side-blowing lance.

[0026] In a preferred embodiment of the present invention, the primary blowing temperature is 1000-1200° C., and the primary blowing time is 6-10 hours, to ensure complete melting of the matte and slag.

[0027] In a preferred embodiment of the present invention, the secondary blowing temperature in S2 is 1100-1300° C., and the secondary blowing time is 10-14 hours.

[0028] The raw material processed in this application is lead matte, which has a copper content half that of the matte in the second step of the Chinese patent with publication number CN113817924A. Lead matte contains only about 30% of the copper, and the content of impurities such as Fe, Pb, As, and Sb is very high, requiring a large amount of slagging. According to the results of heat balance calculations, the slagging period cannot be self-heated and requires additional fuel. Therefore, top blowing alone will slow down the slagging process, and the long-term heat preservation of the melt consumes a large amount of fuel, and the furnace processing capacity is also low. The equipment in the present invention is equipped with 10 side-blowing lances arranged along the circumferential direction, which can greatly increase the stirring kinetic energy and achieve a rapid slagging reaction. At the same time, taking advantage of the adjustable height of the top-blowing lance, the top-blowing lance head is lowered below the horizontal line of the side-blowing tuyere to achieve deep impurity removal of the matte and produce high-grade blister copper.

[0029] At present, the reverberatory furnace process is the most widely used process for lead matte processing. Compared with the traditional reverberatory furnace process, the process of the present invention has the following obvious advantages: the side-top blowing molten pool smelting replaces the almost static molten pool smelting of the reverberatory furnace, the melt stirring intensity is increased, the kinetic conditions of the chemical reaction are improved, the reaction time is shortened, and since the oxygen-enriched air mixes well in the melt, impurities are removed more thoroughly, the heat utilization rate is increased, and the fuel consumption is significantly reduced; at the same time, the traditional reverberatory furnace requires at least two furnaces to blow lead matte into 80% black copper, and the intermediate furnace charge needs to be transported once. The process of the present invention can achieve the output of crude copper in one step, the process flow is shortened, the operation difficulty is reduced, and the working environment is significantly improved.

[0030] Compared with the current converter molten pool smelting process for lead matte, the process described in the present invention eliminates the burner in the converter. Most of the heat required for melting and reaction of the charge comes from the heat released by oxidation of impurity elements, and a small part is supplemented by the submerged combustion of carbonaceous fuel in the melt. Heat loss is small, and the side-blowing smelting and stirring kinetic energy is large. When the same blister copper is blown out, the blowing time of the process of the present invention can be shortened to one third compared with the current converter process.

[0031] To further improve resource recycling efficiency, this paper combines the concepts of lead matte molten pool converting and matte top blowing to propose a smelting method that can efficiently process lead matte materials. The invention also develops supporting smelting equipment—a composite converting furnace. This method utilizes side-blowing and top-blowing lances to complete the entire process of melting, slagging, and copper production within the same molten pool. Tests have shown that this method achieves thorough copper-lead separation, producing blister copper with a lead content of less than 0.3%, suitable for direct refining in copper anode furnaces. The converting efficiency is over 10 times higher than traditional methods. The process is energy-efficient, highly automated, and environmentally friendly, making it of great significance for lead smelting companies to enhance their technological capabilities.

[0032] This patented design incorporates both side-blowing lances and liftable top-blowing lances. When a side-blowing smelting furnace is started, problems such as insufficient hearth heat and coke accumulation can be easily encountered. While the side-blowing lances continue to operate, the top-blowing lances can be used to inject oxygen-enriched air to assist combustion, or directly inject fuel and oxygen-enriched air for combustion to supplement heat. This allows for flexible regulation of the hearth temperature and effectively prevents hearth freezing. This patented design is particularly adaptable to processing lead matte materials with fluctuating sulfur content.

[0033] The present invention improves the side top blowing function into the same reaction space, simplifies the structure inside the furnace, and can effectively extend the life of the furnace body and increase the operating rate.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) The blowing device of the present invention combines the advantages of side blowing and top blowing of the molten pool, and blows lead matte in stages in the same reaction space, which not only improves the blowing intensity but also greatly shortens the entire process flow, and produces crude copper in one step. It is a low-energy consumption and easy-to-operate blowing method. 2) The blowing method of the present invention can achieve deep separation of copper and lead, and the blowing product is crude copper with extremely low lead content, and is rich in precious metals such as Ag, which increases the value of lead matte. 3) In the blowing method of the present invention, most of the Pb element volatilizes to smoke dust, which can be returned to the lead smelting system for further extraction and recovery. The blowing slag can be sent to the cement plant as raw material after copper selection, and the sulfur-containing flue gas can be sent to acid production after purification. The entire process is pollution-free to the environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a schematic structural diagram of a lead matte blowing device in one embodiment of the present invention.

[0036] Figure 2 This is a process flow chart of oxygen-enriched side blowing and oxygen-enriched top blowing of lead matte in one embodiment of the present invention.

[0037] Figure 3 Schematic diagram of the structure of a side-blowing spray gun in one embodiment of the present invention.

[0038] Among them: 1-furnace shell, 2-furnace hearth, 3-lead port, 4-copper port, 5-slag port, 6-side blowing lance, 7-top blowing lance, 8-charging port, 9-steel frame, 10-flue, 11-waste heat recovery device, 12-flue gas outlet, 13-tuyere water jacket, 14-refractory material, 15-furnace shell water jacket. DETAILED DESCRIPTION

[0039] Example 1

[0040] The following describes the apparatus for copper smelting in one step of oxygen-enriched side blowing and oxygen-enriched top blowing of lead matte according to the present invention with reference to the accompanying drawings.

[0041] like Figure 1As shown, the furnace body of the oxygen-enriched side-blowing and oxygen-enriched top-blowing process for lead matte of the present invention is a cylindrical structure, and there is only one continuous reaction space from top to bottom in the furnace. The furnace shell 1 is surrounded by 20-30 mm thick steel plates, and the outer periphery of the steel plates is reinforced with ribs. The furnace cylinder 2 is built with multiple layers of refractory bricks, with temperature measuring thermocouples buried at the bottom and water-cooling elements buried in the furnace wall. A lead port 3 is provided at the bottom of the furnace, and if the lead content in the charge is high to generate crude lead, the lead can be discharged regularly. A copper port 4 is provided on the upper part of the lead port, and a slag port 5 is provided on the upper part of the copper port. To facilitate the opening operation, each straight discharge port is arranged at a certain angle in the circumferential direction of the furnace cylinder, and is provided with an independent chute. Multiple side-blowing lances 6 are arranged circumferentially in the upper center of the furnace hearth. Arranged in two tiers, they remain submerged in the slag layer during blowing. The lance bodies, constructed from multi-layered concentric tubes, can inject oxygen-enriched air alone or a mixture of coal gas, pulverized coal, and oxygen-enriched air to supplement the melt's heat. The outer diameter of the lances ranges from 30 to 50 mm. The manufacturer of these lances is Xi'an Fuso Electromechanical Co., Ltd.

[0042] like Figure 3 As shown, the outer side of the water-cooling air port 13 of the side-blowing lance 6 is covered with a refractory material 14, and the refractory material is aluminum-chrome brick.

[0043] A top-blowing lance 7 is inserted into the center of the furnace roof. The tail of the lance is fixed on a sliding lifting device and is moved vertically by a hoisting mechanism. The position of the lance head can be freely switched between the gas area, slag layer, and matte layer. The body of the top-blowing lance is a multi-layer concentric sleeve structure. It can blow in oxygen-enriched air alone or simultaneously blow coal gas / pulverized coal and oxygen-enriched air to achieve the functions of blowing, replenishing heat, and adjusting the furnace atmosphere. The outer diameter of the lance body is between Φ50-Φ76. The feeding port 8 and the water-cooling flue 9 are located on the upper part of the furnace body. The flue is a circular structure. A water channel surrounded by channel steel is provided on the outside of the steel plate, and an anchor is provided on the inside of the steel plate for anchoring refractory materials. A ash cleaning port is provided at the top of the water-cooling flue 10, and thermocouple temperature measuring devices and pressure measuring devices are provided at the inlet and outlet. The waste heat recovery device 11 is a rectangular structure with a width of 4m-5m and is equipped with an ash removal device. The flue outlet 12 is composed of a water-cooled wall or a water-cooled jacket, and is at an angle of 30°-45° to the vertical.

[0044] The oxygen-enriched side-blowing and oxygen-enriched top-blowing copper smelting apparatus of the present invention operates in sections within a reaction space. The upper portion of the furnace is an empty area, and the lower molten pool during the blowing process is divided into two or three layers, which are, from top to bottom, a slag layer, a matte layer, and a lead liquid layer. When the raw material contains a high amount of elemental lead, it may be generated and needs to be discharged regularly. A plurality of side-blowing lances 6 are evenly arranged on the furnace wall around the slag layer and immersed in the slag. Oxygen-enriched air can be blown into the furnace to adjust the oxidizing atmosphere and disturb the melt, or fuel can be blown in at the same time to provide a heat source. The granular raw material added from the furnace top charging port is stirred by the high-speed airflow blown in in the slag layer, gradually heating up and melting. Since the tuyere is arranged at the upper part of the entire molten pool, only the slag is vigorously stirred, and the matte layer at the lower part is relatively static. The matte settled in the furnace cannot be heated by the fuel blown in by the lance, and its heat mainly comes from conduction from the molten pool. A direct slag discharge port, located above the tuyere of the slag layer, allows for regular discharge of the blowing slag to prevent the oxidation and dissolution of large amounts of Cu into the slag during the blowing process, which can complicate subsequent handling. If the charge contains a high crude lead content and some settles to the bottom of the furnace, the lead outlet located at the bottom of the furnace wall can be used to release the liquid lead, preventing the blowing process from affecting the quality of the crude copper.

[0045] After the blowing slag is discharged, it enters the blowing section, where the liftable top-blowing lance 7 is vertically lowered into the matte layer to blast in rich oxygen for blowing. The required heat comes from the heat released by the oxidation of metal sulfides. During the blowing process, the lower molten pool is divided into three layers, namely, the copper slag layer, the matte layer, and the copper liquid layer from top to bottom. During blowing, the position of the lance is adjusted in time with the change in the thickness of the matte layer. The molten pool below the muzzle is relatively still, and the copper liquid generated by the interactive reaction can be precipitated at the bottom to form a metal molten pool, which is released from the copper port at the bottom of the furnace wall. After partial oxidation and slagging, the impurity elements float up into the copper slag layer, and some of them evaporate into the smoke.

[0046] The flue gas from the side-blowing refining section and the top-blowing refining section can be sent to the waste heat recovery device 11 through the water-cooled flue 10, and then enter the dust removal system to recover the flue dust. The flue gas can then be purified and sent to the acid production system.

[0047] The process of treating lead matte by oxygen-enriched side blowing and oxygen-enriched top blowing according to the present invention will be described below with reference to the accompanying drawings.

[0048] like Figure 2As shown, the present invention's oxygen-enriched side-blowing and oxygen-enriched top-blowing process for treating lead matte includes: The raw material, lead matte, contains 33% by weight Cu, 12% by weight Pb, and 9% by weight Fe. The lead matte is mixed with silica in a ratio of 100:5 (since the content of impurities such as Pb and Fe in the lead matte is higher than in the matte disclosed in the patent, and both Pb and Fe oxides are alkaline oxides, an acidic oxide is added to form slag in the process of the present invention, so the amount of silica used is greater than that in the disclosed slag, to produce a low-melting-point slag). The mixture is then conveyed by a belt to a charging port and added to a converting furnace. A side-blowing lance positioned above the slag layer injects enriched oxygen. The process continues with blowing for 8 hours at a temperature of 1200°C. The lead matte completes melting and liquid phase separation within the furnace hearth, while 10% by weight of pulverized coal is added to supplement heat. Fuel can be added via granular coal added through the charging port or injected via the side-blowing lance. Silica is added to the blowing stage to form a eutectic with the rising impurity oxides, improving the fluidity of the slag. After oxidation, CuS reacts with FeS to form a matte phase with a copper grade of 65-75%. During the blowing process, attention must be paid to the liquid level to ensure that the interface between the slag and matte does not rise above the slag outlet. The blowing slag is discharged through the slag outlet for copper flotation extraction. The flue gas is cooled and dust-removed before being fed to the acid production system.

[0049] At the beginning of the second-stage blowing, 0.6 wt% silica (relative to matte) is added to the molten pool through the furnace's top charging port. A top-blowing lance, located above the furnace, blows enriched oxygen for blowing. The lance controls the oxygen partial pressure, achieving a two-step blowing process of slagging and copper production. The blowing process lasts 12 hours at a temperature of 1300°C. Fe and other impurities oxidize and float to form slag with the added acidic flux. Some Cu is also oxidized and incorporated into the slag. The main eutectic copper slag types in the blowing zone include FeO-SiO2, FeO-SiO2-Cu2O, and FeO-SiO2-Cu2O-PbO. The blister copper produced by matte oxidation is deposited at the bottom of the furnace hearth, and the molten copper is discharged through a copper port in the lower furnace wall. The copper slag produced in the blowing stage is small in volume and high in copper content, so it can be retained to react with the next batch of melted lead matte, allowing the Cu element to be recovered. This process effectively separates copper and lead from lead matte, producing blister copper in a single step.

[0050] The blowing and refining flue gas is cooled by the water-cooled flue and waste heat recovery device and then sent to the dust collecting device, and then merged into the acid making system after purification process.

[0051] In S1, the lead matte oxidation-converting process is accomplished by submerged, multi-layer side-blowing lances 6 positioned on the side of the furnace wall. The heat required for the conversion is partially generated by the oxidation of metal sulfides in the raw materials, with the remainder generated by the combustion of pulverized coal injected into the lances. The pulverized coal ratio is 7-10%. During the oxidation-converting stage, the lead matte and silica flux, under the action of oxygen-enriched air and fuel injection, form white matte with a copper grade of 65-75% and a eutectic conversion slag. The slag types primarily include FeO-SiO2-PbO, FeO-SiO2-PbO-SbO2, and FeO-SiO2-PbO-ZnO. After the oxidation-converting stage, the conversion slag is discharged from the slag outlet 5. During the conversion process, the interface between the slag and the matte must not exceed the height of the slag outlet. The smoke dust is partially captured by the waste heat recovery device 11 and then sent to the dust collection system through the flue gas outlet 12 for recovery. After the flue gas is purified, it is fed to the acid production system.

[0052] After the blowing stage, the slag outlet is opened to discharge the low-copper blowing slag. The top-blown oxygen lance is lowered to the matte layer to blow in oxygen-rich air for the second blowing stage. Impurity elements in the matte are fully oxidized and enter the smoke or blowing slag. The sulfur element is oxidized into the flue gas. After cooling and purification, it is sent to the acid production system, generating liquid crude copper rich in precious metals, which sinks below the matte layer. When the liquid level reaches a predetermined height, the lower copper outlet is opened to release the copper liquid.

[0053] In S2, the matte converting process is completed by the liftable top-blowing oxygen lance 7 reaching the matte layer. The lance can control the oxygen partial pressure to achieve two-step converting of slag and copper. During the converting process, the height of the top-blowing lance is adjusted in real time with the reaction. The converting temperature is 1100-1300°C. The crude copper obtained by converting and the converting slag are settled and separated in the furnace 2. The copper liquid is discharged from the copper port 4, and the converting slag is not discharged. It can react with the next batch of molten charge to recover the Cu element therein. The low eutectic copper slag slag types in the converting section mainly include: FeO-SiO2 type, FeO-SiO2-Cu2O type and FeO-SiO2-Cu2O-PbO type. The flue gas in the converting area can be sent to the dust collecting device after passing through the water-cooled flue, and the flue gas after purification is merged into the acid making system.

[0054] In the method of this embodiment, the matte produced in the blowing section contains 70% Cu and <3% Pb. Compared with the matte produced by traditional reverberatory furnace fire smelting, its Pb content is reduced by 5% and the copper grade is increased by about 20%. The copper content (mass fraction, the same below) of the blister copper in this embodiment is ≥95%, the Pb content is ≤0.3%, the Ag content is ≥4500g / t, the Pb impurity removal rate is ≥99.5%, and the Ag recovery rate is ≥99%. Compared with the traditional reverberatory furnace fire blowing process, the blister copper grade is increased by 15%, and a single device is used to complete the lead matte blowing and copper making blowing process, shortening the original blowing cycle of several to more than ten days per furnace to less than 24 hours, greatly improving the blowing efficiency.

[0055] The Chinese patent with publication number CN113817924A adopts a dual-zone furnace smelting process. The obvious advantage of the dual-zone furnace smelting process is that different redox atmospheres can be controlled in the two smelting areas, but the disadvantages are also obvious, that is, it is difficult to open the furnace, the life of the retaining wall is short, the channel is easily blocked, and the furnace needs to be shut down for maintenance. The raw material processed by the patent is copper slag, which contains a large amount of lead oxide that needs to be reduced. Therefore, a dual-zone structure is considered. However, for lead matte, the slag making and copper making processes are both strong oxidizing atmospheres, and there is no need to divide the atmosphere. The use of a single-zone structure avoids the inherent deficiencies of the dual-zone furnace and effectively improves the operating rate. At the same time, the single-zone structure also avoids the problem of liquid pressure balance on both sides of the retaining wall during the operation of the dual-zone furnace, reduces the operational difficulty of the blowing process, and ensures the stability of product quality.

[0056] The original intention of the Chinese patent with publication number CN113817924A and this patent is to give full play to the advantages of oxygen-enriched side-blowing molten pool smelting technology, such as large stirring kinetic energy, strong processing capacity and low energy consumption. The present invention directly superimposes the top blowing function in the side-blowing smelting area, which not only avoids the shortcomings of the double-zone furnace, but also improves the flexibility of the operation of this furnace type. During the furnace opening stage and when the heat in the furnace fluctuates during the blowing process, the side-blowing submerged combustion can supplement the heat of the upper melt. The top-blowing spray gun is different from the disclosed patent. It adopts a multi-layer sleeve spray gun, which can simultaneously blow oxygen-enriched air and fuel into the melt to supplement the heat of the lower melt, overcomes the deficiency of slow downward heat transfer of the side-blowing furnace, effectively reduces the risk of "dead furnace", and improves the adaptability of the process to lead matte raw materials with different sulfur contents.

Claims

1. A lead matte converting process, characterized in that The following steps are involved: S1. Mixing lead matte and silica in a ratio of 100:4-6 and adding the mixture to a lead matte blowing device, performing a primary blowing using a side-blowing lance, wherein a matte layer and a slag layer are formed from bottom to top in the furnace hearth after the primary blowing; S2, using a top-blowing lance to descend to the matte layer, and simultaneously performing secondary blowing with a side-blowing lance, forming a blister copper layer and a slag layer from bottom to top in the furnace; The primary blowing temperature is 1000-1200°C, and the primary blowing time is 6-10 hours; The secondary blowing temperature in S2 is 1100-1300°C, and the secondary blowing time is 10-14 hours; The lead matte blowing device comprises a hollow furnace (2), a feeding port (8) is provided on the furnace (2), a copper port (4) and a slag port (5) are provided on the lower part of the furnace (2) from bottom to top, a lifting device is installed on the top of the inner side of the furnace (2), and the main shaft of the lifting device is fixedly connected to the top blowing lance (7) in the vertical direction, a side blowing lance (6) is installed in the middle of the furnace (2), a water jacket (13) is installed on the outside of the air port (15) of the side blowing lance (6), and the outside of the water jacket (13) is covered with a refractory material (14).

2. The lead matte converting process according to claim 1, characterized in that: During the primary blowing described in S1, oxygen-enriched and pulverized coal are blown in through a side-blowing lance, with a pulverized coal rate of 7-10%.

3. The lead matte converting process according to claim 1, characterized in that: The height of the side-blowing lance (6) from the furnace bottom is 1000-1200 mm.

4. The lead matte converting process according to claim 1 or 2, characterized in that: A plurality of side-blowing spray guns (6) are installed, and the side-blowing spray guns (6) are arranged in two layers, high and low.

5. The lead matte converting process according to claim 1 or 2, characterized in that: The side-blowing spray gun (6) is a concentric sleeve spray gun.

6. The lead matte converting process according to claim 1 or 2, characterized in that: The top-blowing spray gun (7) is a concentric sleeve spray gun.

7. The lead matte converting process according to claim 1 or 2, characterized in that: The lowest position of the top-blowing lance (7) is 400-500 mm from the furnace bottom.

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