A method for high-efficiency reduction and separation of lead-zinc smelting slag in lead-zinc integration

Abstract

The present application relates to the technical field of lead-zinc smelting, and particularly relates to a method for efficient reduction and separation of lead-zinc integrated lead-zinc smelting slag, wherein the lead-zinc smelting slag is poured into a reduction furnace through a slag inlet, flux and a reducing agent coke are mixed, and then the mixture is added into the reduction furnace in a sealed manner, so that the coke forms a coke layer above the slag surface, the upper electrode of the reduction furnace is embedded into the coke layer, the bottom electrode is electrified, the coke layer and the smelting slag are heated through the resistance heating effect, the reduction furnace is heated by the coke powder-oxygen heating mode, efficient reaction is carried out in the furnace, the generated molten lead is discharged from a siphon channel, the tail slag is discharged from a slag discharge port, and the mixed flue gas is introduced into a condenser, and is sequentially treated in a first condensing zone, a second condensing zone and a third condensing zone for grading, so as to realize condensation and separation of lead and zinc. The method has the advantages of shortening the process flow, improving the lead-zinc collection rate, avoiding metal re-oxidation and the like.

Description

Technical Field

[0001] This invention relates to the field of lead-zinc smelting technology, specifically to a method for efficient reduction and separation of lead and zinc in lead-zinc slag. Background Technology

[0002] Currently, the main lead-zinc smelting processes are as follows: zinc smelting primarily uses a hydrometallurgical process of "roasting-leaching purification-electrolysis," while lead smelting mainly uses a pyrometallurgical process of "oxygen-enriched smelting-molten reduction-fumigation zinc extraction." In lead-zinc co-smelting, the ISP process is currently the primary method. Hydrometallurgical zinc smelting suffers from a long process flow and is used to process zinc concentrate. Pyrometallurgical lead smelting focuses on producing lead while simultaneously enriching and recovering zinc, failing to achieve direct reduction of the molten material. This results in a long process flow, high energy consumption, and high zinc content in the final slag. Some research institutions are currently attempting molten reduction technology for lead and zinc, primarily using electric furnaces. However, this method suffers from problems such as floating reducing agent within the furnace and poor reaction kinetics, leading to slow reduction rates and wasted heat energy.

[0003] To address the problems of long process flow, weak reaction intensity, easy oxidation of metals, and high zinc content in the final slag in the aforementioned technologies, this invention employs a highly efficient integrated reduction and separation method for lead-zinc slag. Through immersion reduction combined with bottom electrode heating technology (actually a combination of an upper electrode, coke and slag conductive medium, and a bottom electrode), this method solves the problems of efficient reaction between slag and coke, as well as long process flow, high energy consumption, and high zinc content in the final slag, thus forming a novel, highly efficient integrated reduction and separation method for lead and zinc. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method for efficient reduction and separation of lead and zinc in lead-zinc slag, which solves the technical problems of slow reaction between slag and coke, poor reaction effect, long process, high energy consumption and high zinc content in the final slag in lead-zinc smelting process.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for efficient reduction and separation of lead and zinc in lead-zinc slag, comprising the following steps: Step 1: The lead-zinc slag is fed into the reduction furnace through the slag inlet. The flux and excess coke reducing agent are fully mixed and then added into the reduction furnace through a closed feeding method. The coke reducing agent forms a coke layer above the slag surface. The furnace cavity of the reduction furnace is equipped with an upper electrode and a bottom electrode. When the flux and excess coke reducing agent are added to the reduction furnace, part of the upper electrode is buried in the formed coke layer. The upper electrode, coke layer, slag, bottom electrode and external power supply equipment form a current loop. Step 2: The external power supply equipment supplies power, and the coke layer and slag are heated under the action of DC power. The temperature of the slag and coke layer is kept between 1150℃ and 1450℃ by controlling the external power supply equipment. The immersion depth of the coke layer in the slag is adjusted by adjusting the thickness of the coke layer, so that the slag and coke are in full contact, generating molten lead, mixed flue gas and tailings. In step three, the molten lead metal generated in step two is discharged from the siphon channel at the bottom of the reduction furnace, the tailings are discharged through the slag discharge port of the reduction furnace, and the lead and zinc vapors volatilized during reduction are introduced into the condenser to recover the corresponding metals. The condensed mixed flue gas is cooled, dust collected or washed with water to obtain zinc-containing blue powder.

[0006] As an optional technical solution, in step two, while the external power supply equipment provides power, the carbon powder-oxygen heating method is also used to stir and replenish the heat inside the reduction furnace.

[0007] As an optional technical solution, the reduction furnace is also equipped with a spray gun. In step two, while the external power supply equipment provides power, oxygen and carbon powder are injected into the reduction furnace using the spray gun.

[0008] As an optional technical solution, the spray gun is located at the bottom side of the reduction furnace, and the spray gun sprays oxygen and carbon powder into the reduction furnace while stirring the furnace.

[0009] This invention addresses the shortcomings of existing technologies by combining a complete process system of coke immersion reduction, resistance heating effect, closed feeding, temperature-controlled reduction, and multi-stage selective condensation. Through structural innovation and process reform, it achieves a full-process technological upgrade, offering the following significant advantages and positive effects compared to existing processes: 1. Effectively shortens the process flow: By supplying power to the bottom electrode and utilizing the resistance heating effect, the coke can be kept in an incandescent state under the action of current. The coke immersion reduction method can ensure that the material and the reducing agent are in full contact, and that mass transfer and heat exchange are carried out. The reaction is faster and more thorough, shortening the operating cycle of conventional processes by 80%. 2. It can improve lead and zinc recovery rate: the reduction reaction is carried out by immersing coke in molten slag, which reduces the residual zinc content in the tailings. The zinc content in the tailings can reach below 0.8%, which is far lower than the industry level of 1%-2.0% zinc content in tailings, significantly improving the zinc resource recovery rate and effectively improving the economics of resource recovery. 3. The bottom electrode power supply heating method effectively reduces the use of oxygen. It can simultaneously adopt measures such as shaft converter, liquid seal slag feeding, and closed feeding to effectively block excess air from entering the system, eliminate the conditions for lead and zinc vapor oxidation from the source, and avoid the occurrence of metal re-oxidation. 4. Based on the differences in the physical properties of the products, the product undergoes graded condensation. By fully utilizing the differences in boiling points, condensation temperatures, and densities of lead and zinc, a three-stage temperature control system and different condensation and collection media are adopted to achieve selective separation of lead and zinc vapors. 5. Outstanding economic benefits: It has strong adaptability to raw material sources, expanding the range of zinc content required from 25-30% in traditional processes to 5-30%; it has good social benefits, significantly reducing carbon emissions; in terms of products, it can further produce high-quality crude lead, multi-grade zinc-aluminum alloys, zinc-aluminum-magnesium alloys, and zinc-containing blue powder based on this process, realizing the full value-added utilization and maximizing the benefits of lead and zinc resources, and significantly enhancing the core market competitiveness of enterprises. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 A schematic diagram of the reduction furnace and condenser; Figure 2 This is a schematic diagram of the interior of the reduction furnace; In the diagram: 1. Reduction furnace, 11. Upper electrode, 12. Bottom electrode, 13. Siphon channel, 14. Slag, 15. Coke layer, 16. Spray gun, 2. Condenser, 21. First condensing zone, 22. Second condensing zone, 23. Third condensing zone. Detailed Implementation

[0012] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0013] like Figure 1 and Figure 2 As shown, a method for efficient reduction and separation of lead and zinc slag is described. In the reduction furnace 1 used in this method, an upper electrode 11 is provided at the top of the furnace cavity and a bottom electrode 12 is provided at the bottom of the furnace. The reduction furnace 1 is equipped with an external power supply device. The upper electrode 11 and the bottom electrode 12 are connected to the corresponding interfaces of the external power supply device, which can provide DC power.

[0014] The lead-zinc reduction and separation method of this embodiment includes the following steps: Step 1: The lead-zinc slag 14 flows into the reduction furnace 1 through the slag inlet. After the flux and excess coke reducing agent are fully mixed, they are added into the reduction furnace 1 through a closed feeding method. The coke reducing agent accumulates above the slag surface and forms a coke layer 15. Part of the structure of the upper electrode 11 is buried in the coke layer 15. The bottom electrode 12 and the upper electrode 11, which are connected to the external power supply equipment, can form a closed current circuit through the slag 14 and the coke layer 15.

[0015] Step 2: When the external power supply is supplied, the coke layer 15 and the molten slag 14 heat up under the action of DC power due to the resistance heating effect. By controlling the power of the external power supply, the temperature of the molten slag 14 and the coke layer 15 is kept between 1150℃ and 1450℃. By adjusting the thickness of the coke layer 15, the immersion depth of the coke layer 15 in the molten slag 14 is adjusted by the magnitude of the gravity of the coke layer 15, so that the molten slag 14 and the coke can fully contact each other for mass transfer and heat exchange, generating molten metal lead, tailings and mixed flue gas containing lead and zinc vapors from reduction volatilization.

[0016] In a further embodiment, while using external power supply to heat the molten slag 14 and coke layer 15, a combined carbon powder-oxygen heating method is also used to supplement the heat, ensuring reaction efficiency and the temperature of coke and molten slag 14. The high-temperature flue gas generated by carbon powder-oxygen heating is also introduced into the condenser 2 for treatment along with mixed flue gas such as lead-zinc vapor. In some embodiments, the reduction furnace 1 is also equipped with a spray gun 16, which injects oxygen and carbon powder into the reduction furnace 1 to achieve carbon powder-oxygen combustion for supplemental heating of the reduction furnace 1. The spray gun 16 is located at the bottom side of the reduction furnace 1, and while the spray gun 16 injects oxygen and carbon powder into the reduction furnace 1, the airflow can also drive the material in the furnace to move, achieving a stirring effect, so that the coke and molten slag 14 undergo a strong mass transfer reaction.

[0017] Step 3: The molten lead metal generated in step 2 is discharged from the siphon channel (13) at the bottom of the reduction furnace (1), and the tail slag is discharged through the slag discharge port of the reduction furnace (1). The lead and zinc vapors volatilized during reduction are introduced into the condenser (2) to recover the corresponding metals. The mixed flue gas after condensation is cooled, dust collected or washed with water to obtain zinc-containing blue powder.

[0018] As a specific example, the condenser 2 used in this method has a built-in three-stage condensation zone. For ease of description, these three condensation zones are referred to as the first condensation zone 21, the second condensation zone 22, and the third condensation zone 23 according to the direction of flue gas flow during use. The first condensation zone 21 uses lead rain as the cooling and capturing medium, the second condensation zone 22 uses zinc rain as the cooling and capturing medium, and the third condensation zone 23 uses zinc-aluminum alloy as the cooling and capturing medium.

[0019] At this point, in step three, the mixed gases generated in step two, including the reduced and volatilized lead-zinc vapor and the high-temperature flue gas produced by the combustion of charcoal powder, are introduced into condenser 2. Lead rain is used as the cooling and trapping medium in the first condensing zone 21, with the exhaust temperature controlled at 700℃-800℃; zinc rain is used as the cooling and trapping medium in the second condensing zone 22, with the exhaust temperature controlled at 500℃-700℃; and a heart rate alloy is used as the cooling and trapping medium in the third condensing zone 23, with the exhaust temperature controlled at 500℃~650℃.

[0020] When the mixed gas passes through the first condensation zone 21, lead rain at 430℃-550℃ specifically condenses lead vapor. Combined with an exhaust temperature of 700℃-800℃, this effectively reduces premature condensation of zinc vapor, achieving initial separation of lead and zinc. When the mixed gas passes through the second condensation zone 22, the lead content has been significantly reduced while the zinc content remains high. The second condensation zone 22 uses zinc rain to specifically condense zinc vapor. Combined with an exhaust temperature of 500℃~700℃, this condenses most of the zinc vapor and trace amounts of lead impurities, enriching zinc resources. During the third condensation process, the lead content in the mixed flue gas is extremely low. The third condensation process uses a zinc-aluminum alloy as the cooling and trapping medium, with the exhaust temperature controlled at 500℃~650℃, to deeply condense the remaining zinc vapor in the mixed flue gas, yielding zinc-aluminum products.

[0021] Then, the mixed liquid collected in each condensation zone is allowed to stand, cooled, and separated into layers. Based on the density difference and melting point, the corresponding metals are obtained by standing and cooling the layers. The mixed flue gas discharged from the third condensation zone 23 can be cooled, dust collected, or washed with water to recover zinc-containing blue powder.

[0022] In this specification, the terms "an embodiment," "example," "specific example," etc., refer to a specific feature, structure, material, or characteristic described in connection with that embodiment or example, which is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for efficient reduction and separation of lead and zinc in lead-zinc slag, characterized in that: Includes the following steps: Step 1: The lead-zinc slag (14) is fed into the reduction furnace (1) through the slag inlet. The flux and excess coke reducing agent are fully mixed and then added into the reduction furnace (1) through a closed feeding method. The coke reducing agent forms a coke layer (15) above the slag surface. The furnace cavity of the reduction furnace (1) is provided with an upper electrode (11) and a bottom electrode (12). When the flux and excess coke reducing agent are added into the reduction furnace (1), part of the upper electrode (11) is buried in the formed coke layer (15). The upper electrode (11), coke layer (15), slag (14), bottom electrode (12) and external power supply equipment form a current loop. Step 2: The external power supply equipment supplies power, and the coke layer (15) and slag (14) are heated under the action of DC power. By controlling the external power supply equipment, the temperature of the slag (14) and coke layer (15) is kept between 1150℃ and 1450℃. The immersion depth of the coke layer (15) in the slag (14) is adjusted by adjusting the thickness of the coke layer (15), so that the slag (14) and coke are in full contact, generating molten metal lead, mixed flue gas and tailings. Step 3: The molten lead metal generated in step 2 is discharged from the siphon channel (13) at the bottom of the reduction furnace (1), and the tail slag is discharged through the slag discharge port of the reduction furnace (1). The lead and zinc vapors volatilized during reduction are introduced into the condenser (2) and the corresponding metals are recovered by condensation. The mixed flue gas after condensation is cooled, dust collected or washed with water to obtain zinc-containing blue powder.

2. The method for efficient reduction and separation of lead and zinc in lead-zinc slag according to claim 1, characterized in that: In step two, while the external power supply equipment supplies power, the carbon powder-oxygen heating method is also used to stir and reheat the reduction furnace (1).

3. The method for efficient reduction and separation of lead and zinc in lead-zinc slag according to claim 2, characterized in that: The reduction furnace (1) is also equipped with a spray gun (16). In step two, while the external power supply equipment supplies power, oxygen and carbon powder are sprayed into the reduction furnace (1) using the spray gun (16).

4. The method for efficient reduction and separation of lead and zinc in lead-zinc slag according to claim 3, characterized in that: The spray gun (16) is located at the bottom side of the reduction furnace (1), and the spray gun (16) sprays oxygen and carbon powder into the reduction furnace (1) while stirring the furnace (1).

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