Technology and device for directly smelting zinc from low-grade complex zinc oxide material

Abstract

The invention relates to the technical field of zinc smelting, and discloses a direct zinc smelting technology and device for a low-grade complex zinc oxide material, and the direct zinc smelting technology comprises the steps of value-added mixing, uniform mixing and drying, reducing agent drying, normal-pressure melting and purifying, strengthened reduction zinc smelting, crude zinc liquid liquation and ingot casting. The low-grade zinc oxide ore, the high-impurity steel colored zinc-containing dust and the like are directly used for producing metal zinc and lead, the efficient utilization space of low-grade inferior zinc-containing resources is opened, the production process is short, the investment and operation cost is low, full-resource utilization is achieved, the energy utilization rate is high, energy consumption is low, and environmental protection and cleanliness are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of zinc smelting, and particularly to a direct zinc smelting technology and device for low-grade complex zinc oxide materials. Background Art

[0002] Traditional zinc smelting technologies mainly use high-quality zinc sulfide concentrates as raw materials for zinc smelting, which have the advantages of high efficiency, large scale, and high resource utilization rate. They are the mainstream in the market and determine the price of zinc ingots. However, relative to the huge zinc production capacity and market, China's high-quality zinc resources are relatively scarce, and a large amount of zinc concentrates and even zinc ingots need to be imported every year to make up for the market gap. On the other hand, China is rich in low-grade zinc oxide resources, and there are abundant secondary zinc-containing slag and dust resources produced from industries such as iron and steel, non-ferrous metals, and chemical industries every year, which are important advantageous zinc resources. However, due to the low zinc content, high impurity content, many harmful components, and low zinc-to-impurity ratio of this resource, it has become "low-grade complex zinc oxide materials" that cannot be processed by traditional zinc smelting technologies and have high processing costs for existing zinc smelting technologies.

[0003] In practice, low-grade complex zinc oxide materials refer to low-grade zinc oxide ores with zinc content below 35%, zinc-containing slag, dust, and mud produced from industries such as iron and steel, non-ferrous metals, and chemical industries with zinc content of 8-35%, high impurity metals such as lead, copper, and iron, and high fluorine and chlorine content, as well as secondary zinc oxide, hot zinc ash, and paint zinc ash with high fluorine and chlorine content. In the prior art, almost all technologies for zinc smelting using "low-grade complex zinc oxide materials" first enrich the low-grade zinc oxide materials by pyrometallurgy to obtain high-chlorine secondary zinc oxide, and then remove fluorine and chlorine by pyrometallurgy or washing to obtain "qualified zinc oxide calcine or materials" that meet the requirements of zinc smelting technologies. Such as "pyrometallurgy-hydrometallurgy combined zinc smelting technology", "pyrometallurgical enrichment-hydrometallurgical impurity removal-fractional extraction multi-stage coupling centralized treatment technology", and "pyrometallurgical enrichment-pyrometallurgical defluorination and dechlorination-large electric furnace combined zinc smelting technology", etc. They are essentially indirect long-process zinc smelting technologies, with the core being traditional zinc smelting technologies. The difference is that additional pyrometallurgical enrichment, defluorination, and dechlorination processes and technologies are added, inevitably increasing the investment and operating costs of the technology.

[0004] According to industry common sense, the efficiency of zinc smelting is related to the reduction reaction rate and reaction speed of zinc oxide. The reduction reaction rate and reaction speed are linearly and positively correlated with the zinc concentration in zinc oxide materials, and exponentially and positively correlated with the reaction temperature and intensity. Under the conditions of conventional zinc smelting technology, the zinc concentration in the materials has a decisive impact on the extraction rate and efficiency of zinc. When the zinc content is lower than 48%, it will significantly affect the technology efficiency. Obviously, increasing the temperature and intensity of the zinc oxide reduction reaction can also improve the efficiency of zinc smelting. However, in the conventional electric furnace zinc smelting mode mainly based on slag resistance electrothermal, as the electrode insertion depth and input power increase, the slag temperature increases, and the zinc oxide reduction reaction speeds up. But then the decrease in slag resistance will cause overcurrent or even short circuit in the electric furnace, forcing the operation to raise the electrode and reduce the input power. As a result, the slag temperature decreases again, and the zinc reduction and volatilization rate also decreases, and the zinc smelting efficiency drops, limiting the lowest zinc grade of the furnace charge for electric furnace zinc smelting. In addition, the gases discharged from the decomposition of complex zinc oxide carbonates, sulfates and crystal water will affect the normal furnace condition, and the easily volatile fluorine and chlorine elements will combine with zinc and lead, causing zinc loss and equipment corrosion. Therefore, they must also be removed before reduction zinc smelting.

[0005] By changing the temperature of the zinc oxide reduction reaction, the reaction rate of the zinc oxide reduction reaction can be increased, and the output per unit reaction area can be improved; under normal pressure and high temperature conditions, combined zinc oxide ores such as carbonic acid and silicic acid will undergo decomposition reactions to oxidize and exclude CO2, and easily volatile harmful components such as fluorine, chlorine, potassium, sodium and sulfur will decompose or volatilize. Therefore, by increasing the temperature of the zinc oxide reduction reaction; using the thermal decomposition oxidation of different zinc oxide ores and the thermal volatilization of easily volatile harmful components, direct zinc smelting of low-grade complex zinc oxide materials can be realized. For this reason, the applicant proposes a direct zinc smelting technology and device for low-grade complex zinc oxide materials. Summary of the Invention

[0006] The purpose of the present invention is to provide a direct zinc smelting technology and device for low-grade complex zinc oxide materials to overcome the technical problems existing in the prior art.

[0007] To achieve the above technical purpose and reach the above technical effect, the present invention provides the following technical solutions:

[0008] A direct zinc smelting method for low-grade complex zinc oxide materials includes the following steps:

[0009] S1. Value-added mixing and blending, based on the main metal materials with a zinc content of 20%-25%, reasonably matching materials with different zinc grades and accompanying metals to obtain materials with higher economy, optimizing costs and increasing the content and value of accompanying metals;

[0010] S2. Mixing and drying, using a rotary hot air drying kiln to mix and heat the mixed materials to obtain dry hot materials with a moisture content <1%, ensuring the stability of the subsequent melting process. The rotary hot air drying kiln uses the self-produced gas of the electric furnace as fuel;

[0011] S3. The reducing agent is dried. The oxidizing agent is heated and dried using a direct-fired rotary dryer to obtain a dried reducing agent with a moisture content of <1%, ensuring its effectiveness in the reduction reaction. The direct-fired rotary dryer uses self-produced coal gas or natural gas as fuel.

[0012] S4. Atmospheric melting and purification. The dried materials are loaded into an AC submerged arc ferroalloy melting electric furnace to be melted, decomposing metal oxides such as zinc oxide and lead and discharging volatile gases to obtain a clean zinc oxide-containing melt. The working temperature is 1250 - 1350 °C.

[0013] S5. Intensified zinc smelting by reduction. The clean zinc oxide-containing melt is introduced into a DC transfer arc zinc smelting electric furnace for continuous heating. The working temperature is 1400 - 1550 °C. Selective carbon addition reduction smelting is carried out to produce molten slag, pig iron alloy, and zinc-containing combustible mixed gas. After entering the zinc rain condenser for condensation, crude zinc liquid is obtained, and the electric furnace gas is separated.

[0014] S6. Liquation of crude zinc liquid. The crude zinc liquid is introduced into a long-period crude zinc liquation furnace for temperature-controlled liquation. The working temperature is 230 - 520 °C. Different components in the crude zinc liquid are separated by liquation to produce crude zinc liquid, crude lead liquid, and hard zinc.

[0015] S7. Ingot casting. The crude zinc liquid and crude lead liquid are cast into commercial crude zinc and commercial crude lead using an ingot casting machine.

[0016] A direct zinc smelting device for low-grade complex zinc oxide materials, based on the direct zinc smelting method for low-grade complex zinc oxide materials, includes a hot air rotary dryer, a direct-fired rotary dryer, a mixing electric furnace, a long-period crude zinc liquid liquation furnace, and an ingot casting machine. The mixing electric furnace is composed of an AC submerged arc ferroalloy melting electric furnace and a DC transfer arc zinc smelting electric furnace. The AC submerged arc ferroalloy melting electric furnace is used for oxidative melting and decomposition oxidation removal of dried hot materials. The DC transfer arc zinc smelting electric furnace includes a condenser, a dry electric furnace gas purification, dust collection, and utilization system, and is used for reduction and volatilization smelting of zinc oxide and lead in the zinc oxide melt and condensation of zinc-containing combustible mixed gas into crude zinc and separation of electric furnace gas.

[0017] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the AC submerged arc ferroalloy melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in an integrated two-furnace structure, and a communication channel is provided between the AC submerged arc ferroalloy melting electric furnace and the DC transfer arc zinc smelting electric furnace.

[0018] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the AC submerged arc ferroalloy melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in a one-furnace-with-multiple-furnaces structure, and are directly connected by a chute between the AC submerged arc ferroalloy melting electric furnace and the DC transfer arc zinc smelting electric furnace.

[0019] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the AC submerged arc ferrothermal melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in a structure of one furnace with multiple furnaces. The AC submerged arc ferrothermal melting electric furnace and the DC transfer arc zinc smelting electric furnace are connected through a chute and a heat preservation distribution furnace, respectively meeting the requirements of different production scales and site space limitations.

[0020] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the working voltage of the AC submerged arc ferrothermal melting electric furnace is 60 - 110V, the current is P / (V * cos0.75 - 0.85), and the linear area power density of the melt is 60 - 90 kva / m 2 .

[0021] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the working voltage of the DC transfer arc zinc smelting electric furnace is 130 - 230V, the bottom power load is 130 - 230 kva / m 2 , and the DC transfer arc zinc smelting electric furnace adopts a splash-type rotor condenser.

[0022] Preferably, in a direct zinc smelting device for low-grade complex zinc oxide materials, the melt inlets and outlets of the AC submerged arc ferrothermal melting electric furnace and the DC transfer arc zinc smelting electric furnace connected to the chute are all arranged with a siphon-type turning connection structure to prevent external air from entering the electric furnace.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. The process of the present invention has strong adaptability, directly uses low-grade zinc oxide ore and high-impurity iron, steel, and non-ferrous zinc-containing dust and sludge to produce metallic zinc and lead, opening up a space for the efficient utilization of low-grade and inferior zinc-containing resources, with a value increase of more than 60%;

[0025] 2. The production process of the present invention is short. From raw materials to the production of commercial crude zinc, crude lead, etc., there are only three main processes: drying, mixed zinc smelting, and liquation, and the reduction in the number of processes is more than 50%;

[0026] 3. The investment and operation costs of the present invention are low. Due to the shortened process, the equipment and facilities are greatly reduced, the space occupation is small, and low-cost raw materials are used, resulting in a 36% - 70% reduction in investment costs and a 16 - 20% reduction in operation costs;

[0027] 4. The present invention realizes full resource utilization, and the zinc, lead, iron, carbon, silicon, and calcium elements in the materials are all recycled with high value. The zinc recovery rate > 96%, the lead recovery rate > 95%, the iron recovery rate is 30% - 70%, the copper recovery rate is 70%, the recovery rate of silicon-calcium-iron slag is 100%, and the carbon is converted into gas with 100% utilization;

[0028] 5. The present invention has a high energy utilization rate and low energy consumption. The electric furnace gas is used as the fuel for drying materials and reducing agents, the dried materials are hot-charged into the melting electric furnace, and the melt in the melting electric furnace is directly / transported into the DC transfer arc zinc smelting electric furnace for smelting; the waste heat of the furnace charge and melt, as well as the calorific value of the electric furnace gas, are all efficiently utilized, solving the problems of large amount of zinc slag and high energy consumption in zinc smelting from low-grade zinc-containing materials. The energy consumption per ton of furnace charge is 30-50% lower than that of the conventional electric furnace zinc smelting technology (roasted ore).

[0029] 6. The present invention is environmentally friendly and clean, with a full-process pyrometallurgical treatment. There is no waste residue or waste water discharged during production. The slag becomes inert molten slag and is fully utilized. The cooling water and slag flushing water used in production are recycled by more than 96% and not discharged. The main pollution sources are smoke and dust air pollution, but there are few pollution sources. The production smoke and dust are centrally collected and discharged up to the standard after bag dust removal. The smoke and dust emission is <50mg / m³, and the environmental smoke and dust are discharged after being collected and dust-removed. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present invention, the drawings required for use in the following description of the specific embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0031] Figure 1 It is a working process schematic diagram of the direct zinc smelting method for low-grade complex zinc oxide materials in the present invention;

[0032] Figure 2 It is a distribution schematic diagram of the direct zinc smelting device for low-grade complex zinc oxide materials in the present invention;

[0033] Figure 3 It is a layout structure schematic diagram of the mixing electric furnace in the present invention Figure 1 ;

[0034] Figure 4 It is a layout structure schematic diagram of the mixing electric furnace in the present invention Figure 2 ;

[0035] Figure 5 It is a layout structure schematic diagram of the mixing electric furnace in the present invention Figure 3 .

[0036] In the figure: 1. Hot air rotary drying kiln; 2. Direct-fired rotary drying kiln; 3. Mixing electric furnace; 4. Long-period crude zinc liquid liquation furnace; 5. Ingot casting machine; 31. AC submerged arc ore thermal melting electric furnace; 32. DC transfer arc zinc smelting electric furnace. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0037] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0038] Embodiment 1

[0039] Please refer to Figures 1-5 As shown, this embodiment is a method for directly smelting zinc from low-grade complex zinc oxide materials, including the following steps:

[0040] S1. Value-added blending: Based on the main metal material containing 20%-25% zinc, reasonably mix materials with different zinc grades and accompanying metals to obtain materials with higher economy, optimize costs, and increase the content and value of the accompanying metals.

[0041] S2. Mixing and drying: Use a rotary hot air dryer to mix and heat the mixed materials to obtain dry hot materials with a moisture content <1%, ensuring the stability of the subsequent melting process. The rotary hot air dryer uses the self-produced gas from the electric furnace as fuel.

[0042] S3. Reducing agent drying: Use a direct-fired rotary dryer to heat and dry the oxidizing agent to obtain a dry reducing agent with a moisture content <1%, ensuring its effectiveness in the reduction reaction. The direct-fired rotary dryer uses self-produced gas or natural gas as fuel.

[0043] S4. Atmospheric melting and purification: Load the dry materials into an AC submerged arc ore thermal melting electric furnace to melt, decompose metal oxides such as zinc oxide and lead, and discharge volatile gases to obtain a clean zinc oxide-containing melt. The working temperature is 1250 - 1350 °C.

[0044] S5. Enhanced reduction zinc smelting: Introduce the clean zinc oxide-containing melt into a DC transfer arc zinc smelting electric furnace for continuous heating. The working temperature is 1400 - 1550 °C, and selective carbon addition reduction smelting is carried out to produce molten slag, pig iron alloy, and zinc-containing combustible mixed gas. After entering the zinc rain condenser for condensation, crude zinc liquid is obtained, and the electric furnace gas is separated.

[0045] S6. Crude zinc liquid liquation: Introduce the crude zinc liquid into a long-period crude zinc liquation furnace for temperature-controlled liquation. The working temperature is 230 - 520 °C. Different components in the crude zinc liquid are separated by liquation to produce crude zinc liquid, crude lead liquid, and hard zinc.

[0046] S7. Ingot casting: Use an ingot casting machine 5 to cast the crude zinc liquid and crude lead liquid to obtain commercial crude zinc and commercial crude lead.

[0047] The specific implementation manner of this embodiment is as follows:

[0048] The present invention adopts the mixing of economic materials, and optimizes the mixing according to the different zinc contents of raw materials, the values of accompanying metals, different harmful components and cost prices. The purpose is to control the zinc content at 20-25% and the zinc-iron ratio at 3-1.5, and to mix more materials with high added metal value and low cost price to form economic materials with low cost price and high metal content value. It gives play to the characteristics of good technical process adaptability and high metal recovery rate;

[0049] The present invention adopts the molten purification-high temperature zinc smelting technology, which splits the primary zinc smelting into two-stage continuous zinc smelting. Through the melting of materials, the volatile harmful components such as fluorine, chlorine, potassium and sodium are promoted to volatilize, forming a clean zinc-containing melt. Through the melting of materials, the volatile harmful components such as fluorine, chlorine, potassium and sodium are promoted to volatilize, forming a clean zinc-containing melt. By heating the clean zinc-containing melt, energy is provided for the next step of high-temperature zinc smelting, reducing the energy consumption of zinc smelting. By transferring the arc electric arc resistance heat and plasma heat, the zinc-containing melt is continuously heated at high temperature. The heating process is not affected by the change of slag resistance, solving the problem that the heating of traditional electric furnace zinc smelting is affected by the slag type and the change of slag resistivity with temperature. The reduction smelting temperature is as high as 1400-1550 degrees, much higher than that of traditional electric furnace zinc smelting. The reduction and volatilization rate of zinc oxide is greatly increased, and the unit area production capacity is 30-50% higher than that of the traditional one, solving the energy efficiency of zinc smelting from low-grade zinc oxide materials;

[0050] Different from the traditional electric furnace zinc smelting which mainly pursues the gas-solid carbon thermal reduction reaction for zinc oxide, the reduction reaction of high-temperature zinc smelting is mainly a liquid-liquid reduction reaction, and the mass transfer speed is faster. The metal thermal and carbon thermal reduction reactions are carried out simultaneously. Different from the traditional electric furnace zinc smelting non-stratified smelting technology, there are a bottom iron layer, a molten layer and a slag layer in the transfer arc high-temperature zinc smelting. In addition to the carbon thermal reduction reaction occurring at the slag-gas interface, more carbon thermal and metal thermal reduction reactions occur at the molten layer and the molten metal interface layer. By high-temperature operation, the reduction of iron is inhibited, coke is saved, stronger oxidation-reduction conditions are provided, and low-price low-reactivity coal is used as a reducing agent instead of high-price carbon.

[0051] Example Two

[0052] This embodiment is a direct zinc smelting device for low-grade complex zinc oxide materials. Based on the direct zinc smelting method for low-grade complex zinc oxide materials, it includes a hot air rotary drying kiln 1, a direct-fired rotary drying kiln 2, a mixing electric furnace 3, a long-period crude zinc liquid liquation furnace 4 and an ingot casting machine 5. The mixing electric furnace 3 is composed of an alternating current submerged arc ferrosilicon melting electric furnace 31 and a direct current transfer arc zinc smelting electric furnace 32. The alternating current submerged arc ferrosilicon melting electric furnace 31 is used for the oxidation melting and decomposition oxidation exclusion of dry hot materials. The direct current transfer arc zinc smelting electric furnace 32 includes a condenser, a dry method electric furnace gas purification, dust collection and utilization system, and is used for the reduction and volatilization smelting of zinc oxide and lead in the zinc oxide melt and the condensation of zinc-containing combustible gas and the separation of electric furnace gas.

[0053] The AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32 are arranged in an integrated structure with two furnaces. A communication channel is provided between the AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32, and the distribution method is as Figure 3 shown.

[0054] The AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32 are arranged in a structure with one furnace driving multiple furnaces. The AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32 are directly connected by a chute, and the distribution method is as Figure 4 shown.

[0055] The AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32 are arranged in a structure with one furnace driving multiple furnaces. The AC submerged arc smelting electric furnace 31 and the DC transfer arc zinc smelting electric furnace 32 are reconnected through a chute and a heat preservation distribution furnace, and the distribution method is as Figure 5 shown, which are respectively suitable for the requirements of different production scales and site space limitations.

[0056] The working voltage of the AC submerged arc smelting electric furnace 31 is 60 - 110V, the current is P / (V * cos0.75 - 0.85), and the linear area power density of the melt is 60 - 90 kva / m 2 , and the AC submerged arc smelting electric furnace 31 includes circular and rectangular electric furnaces, three-phase and single-phase power supplies, three electrodes, three electrodes in one line, and six electrodes in one line arrangements.

[0057] The working voltage of the DC transfer arc zinc smelting electric furnace 32 is 130 - 230V, and the bottom power load of the furnace is 130 - 230 kva / m 2 , and the DC transfer arc zinc smelting electric furnace 32 includes circular, rectangular, etc., single electrode, double electrode or multi-electrode power supplies to form upper and lower circuits and left and right circuits. The DC transfer arc zinc smelting electric furnace 32 uses a splash type rotor condenser.

[0058] The melt inlets and outlets of the AC submerged arc smelting electric furnace 31, the DC transfer arc zinc smelting electric furnace 32 connected to the chute are all arranged with a siphon type turning connection structure to prevent external air from entering the electric furnace.

[0059] The specific implementation method of this embodiment is as follows:

[0060] In this embodiment, the technical solution integrates all the processes and procedures of enriching low-grade complex zinc oxide materials, defluorinating and dechlorinating, zinc smelting, pyrometallurgical slag treatment, and sewage treatment into the second-stage process of zinc smelting in the further mixing electric furnace 3, eliminating multiple processes and a large number of equipment and facilities such as rotary kiln reduction and volatilization enrichment, rotary kiln calcine defluorination and dechlorination or / and washing defluorination and dechlorination, pyrometallurgical treatment of wet leaching slag, and washing sewage treatment;

[0061] The oxygen-controlled melting purification technology is used to treat low-grade complex zinc oxide materials. During the heating and melting process, it promotes the decomposition and oxidation of zinc oxide ores such as smithsonite, hydrozincite, hemimorphite, and willemite, discharges decomposition gases such as CO2, SO2, and H2O, and volatile components such as fluorine, chlorine, potassium, sodium, and sulfur are also volatilized and discharged, solving the problem of extremely simple purification of different zinc oxide ores and complex zinc oxide materials;

[0062] The direct current transfer arc zinc smelting electric furnace uses 32 arc resistance heat to directly heat the melt, avoiding the dependence on slag type and the limitations on input power and intensity in the traditional slag resistance heating mode. It raises the reduction temperature of zinc oxide to 1400 - 1500 degrees, greatly increasing the reduction reaction rate of zinc oxide and achieving a breakthrough in high-efficiency zinc smelting of low-grade zinc oxide materials; directly utilizing the energy output by the high thermal efficiency alternating current submerged arc melting electric furnace, it greatly reduces the energy consumption of reduction and volatilization zinc smelting, lowers the system energy consumption, and solves the problem of inevitable high energy consumption of low-grade materials; selective carbon addition and high temperature jointly inhibit the excessive reduction of iron oxide, improving zinc reduction and volatilization and reducing the influence of high iron grade; the anode effect in the iron layer and melt layer at the furnace bottom promotes the matte-making reaction, which is beneficial to the formation of matte and improves the recovery value of copper and silver. The flexible coupling mode of the mixed electric furnace 3 can form a structure of one body with two furnaces, a structure with one furnace leading two furnaces directly connected by an intermediate chute, and a structure with one furnace leading multiple furnaces connected by an intermediate distribution furnace buffer, respectively meeting the requirements of different production scales and site spaces. Especially the structure of one furnace leading multiple furnaces breaks through the limitation of the condenser capacity of the zinc smelting electric furnace on the production capacity of electric furnace zinc smelting in a high-efficiency distribution manner, solving the bottleneck of large-scale electric furnace zinc smelting. A single system can even reach a scale of 100,000 tons / year.

[0063] Example III

[0064] Based on Example I and Example II, 100 tons of low-grade zinc oxide ore powder (mainly smithsonite) containing 25% zinc, 4% lead, and 12% moisture, zinc-containing steel dust containing 14% zinc, 1% lead, 0.5% copper, and 40% iron, and high-chlorine secondary zinc oxide containing 50% zinc, 6% lead, and 9% chlorine are mixed in a ratio of 5:4:1 according to the target zinc content of 25%, obtaining economic materials containing 24.35% zinc, 3.4% lead, 16% iron, 0.19% copper, 8% chlorine and moisture, and a pricing coefficient of 24.2%. The contents of iron, lead, chlorine, and moisture are also appropriately controlled. The valuable metals such as lead, iron, and copper that can be priced account for 80% of zinc, and the value has increased;

[0065] 100 tons of economic mixed materials are introduced into the electric furnace gas hot air rotary drying kiln for drying. The heating temperature is controlled at 120 - 150 degrees, and the hot feedback controls the air temperature, air volume, and rotary kiln speed so that the material temperature out of the kiln is 80 - 120 degrees, obtaining 93 tons of dried materials with a moisture content below 1%;

[0066] 11.4 tons of coke fines containing 7% moisture are introduced into an electric furnace gas / natural gas direct-fired rotary dryer for drying. The drying temperature is 400 - 500 °C, and the moisture content of the reductant exiting the kiln is controlled to be < 1%, obtaining 10.6 tons of dried coke fines.

[0067] 93 tons of economic materials are introduced into an alternating current submerged arc melting electric furnace for melting. By adjusting the power input and fluxes, the melting temperature is controlled at 1250 - 1300 °C (the melting temperature exceeds 50%), obtaining 85.6 tons of clean molten zinc oxide-containing material with good fluidity at a temperature of about 1300 °C. CO2, SO2, H2O decomposed and oxidized from combined zinc oxide, and 7.4 tons of volatile components such as fluorine, chlorine, potassium, and sodium that are easily volatilized are discharged. After cooling, washing, and dust collection, they meet the standards and are emptied; (power consumption: 455 kWh / ton of dried material)

[0068] 85.6 tons of clean molten zinc oxide-containing material are introduced into a direct current transfer arc zinc smelting electric furnace 32, and 10.6 tons of dried coke fines are added for arc starting or shallow arc selective reduction smelting. The smelting temperature is controlled at 1400 - 1500 °C, the positive pressure inside the furnace is 150 - 250 Pa, and the CO:CO2 ratio of the furnace gas at the condenser outlet is > 10. 48.24 tons of zinc-containing mixed gas, 4.8 tons of pig iron alloy, and 42.4 tons of molten slag are produced. The zinc-containing mixed gas directly enters a zinc rain condenser for condensation to produce 25.74 tons of crude zinc liquid. 21.4 tons of electric furnace gas are separated, and after cooling and dust collection, 0.4 tons of zinc ash containing zinc and lead and 0.68 tons of blue powder containing zinc and lead are recovered; (power consumption: 740 kWh / ton of molten material)

[0069] 25.74 tons of crude zinc liquid are introduced into a long-period crude zinc liquation furnace for liquation while being kept warm and buffered. The liquation temperature is controlled at 430 - 520 °C, and the liquation time is 60 - 90 hours. 22.1 tons of commercial crude zinc, 3.34 tons of crude lead, and 0.3 tons of hard zinc are produced by liquation.

[0070] In the description of this specification, the descriptions referring to terms such as "one embodiment", "example", "specific example", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0071] The preferred embodiments of the present invention disclosed above are only used to help illustrate the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to the specific embodiments described. Obviously, many modifications and variations can be made according to the content of this specification. These embodiments are selected and specifically described in this specification to better explain the principles and practical applications of the present invention, so that those skilled in the art can well understand and utilize the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A direct zinc smelting method for low-grade complex zinc oxide materials, characterized in that, It includes the following steps: S1. Value-added blending: Based on the main metal materials containing 20%-25% zinc, reasonably mix materials with different zinc grades and accompanying metals to obtain materials with higher economy, optimize costs and increase the content and value of accompanying metals; S2. Blending and drying: Use a rotary hot air drying kiln to blend and heat the mixed materials to obtain dry hot materials with a moisture content <1%, ensuring the stability of the subsequent melting process. The rotary hot air drying kiln uses the gas produced by the electric furnace itself as fuel; S3. Reducing agent drying: Use a direct-fired rotary drying kiln to heat and dry the oxidizing agent to obtain a dry reducing agent with a moisture content <1%, ensuring its effectiveness in the reduction reaction. The direct-fired rotary drying kiln uses the gas produced by itself or natural gas as fuel; S4. Atmospheric melting and purification: Load the dry materials into an AC submerged arc submerged melting electric furnace to melt, decompose metal oxides such as zinc oxide and lead, and discharge volatile gases to obtain a clean zinc oxide-containing melt, with a working temperature of 1250-1350°C; S5. Intensified zinc smelting by reduction: Import the clean zinc oxide-containing melt into a DC transfer arc zinc smelting electric furnace for continuous heating, with a working temperature of 1400-1550°C, perform selective carbon addition reduction smelting to produce molten slag, pig iron alloy and zinc-containing combustible gas mixture. After entering the zinc rain condenser for condensation, crude zinc liquid is obtained, and the electric furnace gas is separated; S6. Crude zinc liquid liquation: Import the crude zinc liquid into a long-period crude zinc liquation furnace for temperature-controlled liquation, with a working temperature of 230-520°C. By liquation, different components in the crude zinc liquid are separated to produce crude zinc liquid, crude lead liquid and hard zinc; S7. Ingot casting: Use an ingot casting machine to cast the crude zinc liquid and crude lead liquid to obtain commercial crude zinc and commercial crude lead.

2. A direct zinc smelting device for low-grade complex zinc oxide materials, based on the direct zinc smelting method for low-grade complex zinc oxide materials described in claim 1, characterized in that: It includes a rotary hot air drying kiln, a direct-fired rotary drying kiln, a mixing electric furnace, a long-period crude zinc liquid liquation furnace and an ingot casting machine. The mixing electric furnace is composed of an AC submerged arc submerged melting electric furnace and a DC transfer arc zinc smelting electric furnace.

3. The direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in an integrated two-furnace structure, and there is a connecting channel between the AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace.

4. A direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in a one-furnace-with-multiple-furnaces structure, and the AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace are directly connected by a chute.

5. The direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace are arranged in a one-furnace-with-multiple-furnaces structure, and the AC submerged arc submerged melting electric furnace and the DC transfer arc zinc smelting electric furnace are reconnected through a chute and a heat preservation distribution furnace.

6. A direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The working voltage of the AC submerged arc ferroalloy melting electric furnace is 60 - 110V, the current is P / (V * cos0.75 - 0.85), and the linear area power density of the melt is 60 - 90kva / m 2 .

7. A direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The working voltage of the DC transferred arc zinc smelting electric furnace is 130 - 230V, and the bottom power load is 130 - 230 kVA / m 2 , and the DC transferred arc zinc smelting electric furnace adopts a splash type rotor condenser.

8. A direct zinc smelting device for low-grade complex zinc oxide materials according to claim 2, characterized in that: The molten body inlets and outlets of the AC submerged arc submerged melting electric furnace, the DC transfer arc zinc smelting electric furnace connected to the chute are all arranged in a siphon-type turning connection structure.

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