High-valued utilization method of zinc-containing silicon-manganese alloy fly ash and rotary hearth furnace undersize powder

Abstract

The invention discloses a high-valued utilization method of zinc-containing silicon-manganese alloy fly ash and rotary hearth furnace undersize powder, which comprises the following steps: S1, adding the zinc-containing silicon-manganese alloy fly ash, the rotary hearth furnace undersize powder and a reducing agent into a rotary kiln for pre-reduction roasting to obtain a sintered material and zinc-containing flue gas, and recovering the zinc-containing flue gas to obtain secondary zinc oxide powder; and S2, the sintered material is hotly charged into an ore-smelting electric furnace to be smelted, quick lime and coke are added, and manganese-silicon-iron alloy and metallurgical slag are obtained after smelting is finished. According to the method, the zinc-containing silicon-manganese alloy dedusting ash and the undersize powder of the rotary hearth furnace are cooperatively treated through prereduction of the rotary kiln and the ore-smelting electric furnace, the secondary zinc oxide powder and the iron-silicon-manganese alloy product are finally produced, and zinc, iron, silicon and manganese elements in the two kinds of solid waste are comprehensively recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of metallurgical environmental protection, and in particular relates to a method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder. Background Art

[0002] my country is a major producer of ferroalloys, with an annual output of about 3.5 million tons of silicon-manganese alloy. Each ton of alloy produced can produce 120-200 kg of by-products, and the output of silicon-manganese alloy dust can reach 420,000 t / a, of which the manganese oxide content can reach 20%-30%, and the silicon dioxide content can reach 20-30%, which has reached the manganese grade of manganese concentrate in some domestic enterprises. In addition, silicon-manganese alloy dust also contains harmful elements such as Zn, Pb, K, Na and Cl, which is a typical dust containing heavy metals. At present, the recycling of silicon-manganese alloy dust mainly adopts batching sintering method and pelletizing method through pyrometallurgical process, some use wet leaching process or use it as agricultural fertilizer, and some smaller enterprises adopt stockpiling method for treatment. The pyrometallurgical process has a thorough removal effect on heavy metals such as zinc and lead, and the associated dust and residue are easy to be recycled. It has the advantages of simple process, strong raw material adaptability, and high metal recovery potential. However, the recycling of silicon-manganese alloy dust as sintering raw material has poor sintering performance and will cause the enrichment of harmful elements. Wet treatment processes such as acid leaching, alkali leaching and ammonia leaching have low removal efficiencies for zinc, lead and alkali elements (K, Na) (for example, the removal rate for zinc is mostly less than 85%), and a large amount of harmful wastewater and other secondary products that are difficult to treat and utilize will be generated during the treatment process. If recycled as fertilizer, the heavy metal elements in the dust pose a risk of damaging the soil and endangering human health. Stacking and landfilling not only wastes resources but also pollutes the surrounding environment and human health.

[0003] The rotary hearth furnace process belongs to the category of non-blast furnace ironmaking and is a rapidly developing type of coal-based direct reduction process. The rotary hearth furnace process has the advantages of short reduction time, high volatilization rate of valuable metals, and high iron content and metallization rate of metallized pellets after reduction (can be directly used as ironmaking raw materials). It is widely used in the steel industry. Domestic rotary hearth furnaces generally use briquetting and pelletizing processes to treat metallurgical dust and sludge in steel plants, among which briquetting accounts for a relatively large proportion. The high-quality metallized pellets produced by the rotary hearth furnace can be directly used as raw materials for steelmaking or ironmaking, but at the same time, 20-30% of undersize powder with a particle size of less than 3mm is produced. The undersize powder has a total iron content of 50%-60%, a metallization rate of 10-20%, and a zinc content of 1-2%. Due to its fine particle size and low metallization rate, it cannot be directly consumed by the steelmaking or ironmaking system. At present, it is mainly returned to the rotary hearth furnace for batching or added to the sintering system of the steel plant for coordinated disposal, and has not been fully and effectively utilized as a resource.

[0004] Chinese patent application number CN202210666242.9 provides a method for preparing carbon-containing silicon-manganese alloy dust ash pellets, comprising the following steps: (1) silicon-manganese alloy dust ash and carbon powder are fully mixed in proportion to obtain a mixture 1; (2) an organic component of a binder is added to the mixture 1, and the mixture is fully mixed to obtain a mixture 2; (3) an aqueous solution of an inorganic component of a binder is added to the mixture 2, and the mixture is fully mixed to obtain a mixture 3; (4) the mixture 3 is pressed into a ball press to obtain carbon-containing silicon-manganese alloy dust ash pellets, and (5) the carbon-containing silicon-manganese alloy dust ash pellets are dried to obtain a finished product. This technology returns the silicon-manganese alloy dust ash to the silicon-manganese alloy smelting system, but does not solve the open circuit problem of harmful elements such as Zn, Pb, K, Na and Cl in the silicon-manganese alloy dust, which has a great impact on the entire smelting system, among which the enrichment of zinc chloride and sodium chloride will stick in the smelting system, affecting the smooth operation of the system.

[0005] Chinese patent application number CN202010260695.2 provides a method for comprehensive utilization of silicon-manganese alloy dust removal ash and waste acid to produce battery-grade manganese sulfate, wash low-grade silicon-manganese alloy dust removal ash with 20% dilute sulfuric acid, and obtain a sulfate solution after slag removal, wherein the sulfate includes manganese sulfate, calcium sulfate, aluminum sulfate, and magnesium sulfate, and the concentrations of calcium sulfate, aluminum sulfate, and magnesium sulfate in the sulfate solution are adjusted so that calcium sulfate, aluminum sulfate, and magnesium sulfate form calcium magnesium sulfate co-precipitation, and then a certain amount of manganese powder is added, and calcium magnesium sulfate is separated to obtain a manganese sulfate solution, and the obtained manganese sulfate solution is crystallized at high temperature, and the crystals are separated to obtain manganese sulfate. The acid leaching process of this technology has a low removal efficiency for zinc, lead, and alkali elements (K, Na) (such as the removal rate for zinc is mostly less than 85%), and a large amount of harmful wastewater and other secondary products that are difficult to treat and utilize will be generated during the treatment process.

[0006] Chinese patent application number CN202011219309.1 discloses a method and device for pressing undersize powder from a rotary hearth furnace, comprising the following steps: screening the metal balls and undersize powder after sintering and reduction in the rotary hearth furnace, and conveying them to a closed silo after metering, feeding the undersize powder in the closed silo into a double-shaft mixer, and sequentially adding a binder and water to the double-shaft mixer to obtain a dust-free mixture; uniformly stirring to obtain a semi-finished product; uniformly feeding the semi-finished product to a wheel mill, and conveying it to a briquetting machine after wheel milling and mixing to be processed into pellets; and obtaining finished balls. The method of the present invention enables the undersize powder from the rotary hearth furnace to be directly processed into high-quality cold-pressed balls suitable for steelmaking and ironmaking, so that resources are fully utilized, and it is environmentally friendly and energy-saving, without dust flying, and without wastewater discharge, realizing the high added value utilization of all resources, and achieving clean and efficient production. The device of this technology is dust-free, exhaust-free and waste-water-free, and the product is green, environmentally friendly and energy-saving. However, heavy metal elements such as lead and zinc screened out in the powder using this method still return to the steel system and are not recycled as resources. The enrichment of harmful elements is not conducive to the steel smelting process.

[0007] Chinese Patent Application No. CN202111229853.9 This invention discloses a method for processing the undersize powder of the metallized pellets of the rotary hearth furnace, which is mixed with other metallurgical solid wastes to make pellets and used as raw materials for steelmaking converters. Raw materials suitable for use in steelmaking converters are produced by selecting raw materials for proportioning and processing, and have the characteristics of stable composition, low production line investment, and low production cost. This method is similar to the traditional cold-pressed ball process, which belongs to the return production process and has low resource utilization. Summary of the invention

[0008] In view of the problems of the prior art, the purpose of the present invention is to provide a method for high-value utilization of zinc-containing silicon-manganese alloy dust ash and rotary hearth furnace undersize powder, which combines rotary kiln pre-reduction and high-temperature smelting technology, utilizes rotary kiln pre-reduction to output sintered products containing ferrous oxide, and recovers valuable metal zinc at the same time, and then utilizes the high ferrous oxide content in the sintering material to remove phosphorus, thereby solving the problem that high-phosphorus solid waste raw materials cannot smelt manganese-silicon ferroalloy, and at the same time solves the problem of insufficient resource utilization of zinc-containing silicon-manganese alloy dust ash and rotary hearth furnace undersize powder, thereby obtaining products with higher economic value.

[0009] To achieve the above object, the present invention adopts the following technical solution:

[0010] The present invention provides a method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder, comprising the following steps:

[0011] S1, adding zinc-containing silicon-manganese alloy dust, rotary hearth furnace undersize powder, and a reducing agent into a rotary kiln for pre-reduction roasting to obtain sintering material and zinc-containing flue gas, and recovering the zinc-containing flue gas to obtain secondary zinc oxide powder;

[0012] S2, hot charging the sintered material into a submerged arc furnace for smelting, and adding quicklime and coke, and obtaining ferromanganese silicon alloy and metallurgical slag after the smelting.

[0013] Preferably, in step S1:

[0014] The mass ratio of the zinc-containing silicon-manganese alloy dust to the rotary hearth furnace undersize powder is 100:4.5-8.5, and the Mn / Fe in the mixture of the zinc-containing silicon-manganese alloy dust and the rotary hearth furnace undersize powder is controlled to be ≥8;

[0015] The mass ratio of the mixture of the zinc-containing silicon-manganese alloy dust ash and the rotary hearth furnace undersize powder to the reducing agent is 100:2-4.

[0016] Preferably, in step S1:

[0017] The mixture of the zinc-silicon-manganese alloy dust and the rotary hearth furnace undersize powder has a TFe content of 2.5-3.8wt%, a Zn content of 7-15wt%, a Mn content of 20-30wt%, a SiO2 content of 10-20wt%, and a CaO content of 2-3.5wt%;

[0018] The reducing agent is coal, and its particle size is less than 3mm.

[0019] Preferably, in step S1, during the pre-reduction roasting process, the temperature of the rotary kiln is 600-1150°C, the preheating time is 40-60 min, and the temperature is kept at 1150°C-1200°C for 60-80 min, after which the sintered material is cooled to 700°C in the discharging zone before being discharged.

[0020] Preferably, in step S1:

[0021] The sintering material has a TFe content of 6-7wt%, a Mn content of 50-55wt%, a SiO2 content of 25-33wt%, and a CaO content of 5-6wt%;

[0022] The zinc content of the secondary zinc oxide powder is more than 60%.

[0023] Preferably, in step S2:

[0024] During the smelting process of the ore-fired electric furnace, the binary basicity in the sintering material is controlled to be 0.8-1.2 by adding quicklime;

[0025] The particle size of the coke is 3-5 mm, and the mass ratio of the sintering material to the coke is 100:15-20.

[0026] Preferably, in step S2:

[0027] The smelting in the electric furnace is divided into two stages. The first stage is a low-temperature dephosphorization stage, the temperature is controlled at 1500-1520°C, and the dephosphorization time is 30-50 minutes. After the first stage of dephosphorization is completed, the electric furnace is heated to 1600-1650°C to start the second stage of smelting manganese silicon iron alloy, and the smelting time is 1-1.5 hours.

[0028] Preferably, in step S2:

[0029] In the ferromanganese-silicon alloy, the TFe content is ≤16%, the manganese-silicon content is greater than 83%, the carbon content is less than 1.5%, the phosphorus content is less than 0.2%, and the sulfur content is less than 0.01%.

[0030] The method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder of the present invention also has the following beneficial effects:

[0031] 1. The present invention utilizes rotary kiln pre-reduction + ore-fired electric furnace to process zinc-silicon-manganese alloy dust and rotary hearth furnace underscreen powder, and finally produces secondary zinc oxide powder and iron-silicon-manganese alloy products, and comprehensively recovers zinc, iron, silicon and manganese elements in the two solid wastes;

[0032] 2. The present invention combines pre-reduction and high-temperature smelting technologies, uses a rotary kiln for pre-reduction to produce sintered products containing ferrous oxide, and recovers valuable metal zinc at the same time, and then uses the high ferrous oxide content in the sintering material to remove phosphorus, thereby solving the problem that high-phosphorus solid waste raw materials cannot smelt manganese-silicon ferroalloys, and at the same time, realizes the problem of insufficient resource utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace underscreen powder, thereby obtaining products with higher economic value; 3.

[0033] 3. The present invention realizes the recovery of zinc element and the generation of ferrous oxide by dephosphorization through pre-reduction control of rotary kiln, thereby realizing the purpose of producing ferrosilicon manganese alloy with high-phosphorus solid waste raw materials; and realizes the purpose of dephosphorization, desulfurization and smelting ferrosilicon manganese alloy through staged smelting in the ore-fired electric furnace. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0035] Figure 1 It is a schematic flow chart of the method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder of the present invention;

[0036] Figure 2 The present invention is a schematic structural diagram of a system used in the method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder. DETAILED DESCRIPTION

[0037] In order to better understand the above technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with embodiments.

[0038] Combination Figure 1 As shown, the method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder provided by the present invention comprises the following steps:

[0039] S1, adding zinc-containing silicon-manganese alloy dust, rotary hearth furnace undersize powder, and reducing agent into a rotary kiln for pre-reduction roasting to obtain sintering material and zinc-containing flue gas;

[0040] The composition of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder is shown in Table 1;

[0041] Table 1

[0042] Element TFe FeO Zn Mn <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO P S Zinc-silicon-manganese alloy dust % 0.5～3 0 7～15 20～30 10～20 2～3 0.1～0.2 0.25～0.4 0.2～0.4 0.1～0.2 Rotary hearth furnace undersize powder % 45～55 30～40 1～2 0.05～0.1 3.8～5 7～10 0.5～1.2 2～3 0.3～0.6 0.3～0.5

[0043] The above-mentioned zinc-silicon-manganese alloy dust ash and rotary hearth furnace undersize powder are added to the rotary kiln in a mass ratio of 100:4.5-8.5, and Mn / Fe in the mixture is controlled to be ≥8. The composition of the mixture of zinc-silicon-manganese alloy dust ash and rotary hearth furnace undersize powder is shown in Table 2. In the mixture, the TFe content is 2.5-3.8wt%, the Zn content is 7-15wt%, the Mn content is 20-30wt%, the SiO2 content is 10-20wt%, and the CaO content is 2-3.5wt%.

[0044] Table 2

[0045] Element TFe FeO Zn Mn <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO P S Mixture % 2.5～3.8 1.3～1.8 7～15 20～30 10～20 2～3.5 0.1～0.2 0.25～0.4 0.25～0.5 0.1～0.22

[0046] The mixture of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder and reducing agent are added into the rotary kiln at a mass ratio of 100:2-4 for pre-reduction roasting. The reducing agent can be coal with a particle size of less than 3 mm.

[0047] The main purpose of pre-reduction roasting is to volatilize the zinc in the mixture into the flue gas and obtain secondary zinc oxide powder through dust removal and other methods. During the pre-reduction roasting process, iron oxide is reduced to ferrous oxide.

[0048] The pre-reduction roasting equipment adopts a rotary kiln, which can be φ4.5*70m in size and 3.5% in slope. During the pre-reduction roasting process, the temperature of the rotary kiln is 600-1150℃, the preheating time is 40-60min, and the temperature is kept at 1150℃ for 60-80min. After that, the sintered material is cooled in the discharge area for 30-50min, and the temperature is reduced from 1150-1200℃ to 700℃ before discharge. The rotary kiln provides heat by burning coal gas, and the coal gas used can be natural gas, coke oven gas, blast furnace gas, converter gas and mixed gas.

[0049] Since the iron in the mixture exists in the form of Fe3O4, Fe0, and Fe2O3, during the pre-reduction roasting process, when the temperature is less than 1150°C, Fe3O4 and Fe2O3 are reduced to Fe0 by carbon, and ferrous oxide mainly exists in the form of ferric silicate (FeSiO4). The reaction is as follows:

[0050] Fe3O4+C=3FeO+CO(g)

[0051] Fe3O4+CO=3FeO+CO2(g)

[0052] Fe2O3+C=2FeO+CO(g)

[0053] Fe2O3+CO=2FeO+CO2(g)

[0054] The zinc element in the mixture mainly exists in the form of zinc ferrite, zinc oxide and other phase structures. This type of phase structure is reduced by carbon to metallic zinc at 600-1150°C and volatilizes into the flue gas. The zinc-containing flue gas is discharged at the tail of the rotary kiln. The zinc in the flue gas is oxidized and collected by the bag filter as secondary zinc oxide powder. At the same time, some potassium, sodium, sulfur and other elements in the mixture also enter the flue gas. The main reaction equation is as follows:

[0055] 3ZnFe2O4+C=2Fe3O4+3ZnO(g)+CO(g)

[0056] ZnO+C=Zn(g)+CO(g)

[0057] ZnO+CO=Zn(g)+CO2(g)

[0058] The volatilization rate of zinc in the pre-reduction roasting process of the mixed material exceeds 88%, and the zinc-containing flue gas is recovered to obtain secondary zinc oxide powder with a zinc grade of more than 60%. After the mixed material is pre-reduced and roasted, a sintered material is obtained, and the composition is shown in Table 3 below. In the sintered material, the TFe content is 6-7wt%, the Mn content is 50-55wt%, the SiO2 content is 25-33wt%, and the CaO content is 5-6wt%;

[0059] Table 3

[0060] Element TFe FeO Zn Mn <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO P S Sintering material% 6～7 3～4 0.2～0.3 50～55 25～33 5～6 0.35～0.5 0.55～0.8 0.28～0.65 0.12～0.25

[0061] S2, hot charging the sintered material into a submerged arc furnace for smelting, and adding quicklime and coke, and obtaining ferromanganese silicon alloy and metallurgical slag after the smelting.

[0062] The sintering material is hot charged into a mineral heat electric furnace for smelting, and quicklime is added to ensure that the binary basicity (i.e. CaO% / SiO2%) in the sintering material is 0.8-1.2. Coke with a particle size of 3-5 mm is added as a reducing agent, and the ratio of the sintering material to the coke is 100:15-20.

[0063] The smelting of the electric furnace is divided into two stages. The first stage is the low-temperature dephosphorization stage. The temperature is controlled at 1500-1520℃. In this stage, part of the ferrous oxide and calcium oxide in the sintering material react with phosphorus to play the role of dephosphorization. The dephosphorization time is 30-50 minutes, and the phosphorus removal rate is greater than 90%. The reaction is as follows:

[0064] 2[P]+5(FeO)+4(CaO)=(4CaO··P2O5)+5[Fe]

[0065] After the first stage of dephosphorization is completed, the electric furnace is heated to 1600-1650°C to start the second stage of smelting ferromanganese silicon alloy. The manganese element in the sintered material mainly exists in the form of MnO. The smelting time is 1-1.5 hours. At the end of smelting, high-quality ferromanganese silicon alloy and metallurgical slag are obtained. The composition of ferromanganese silicon alloy: TFe content ≤16%, manganese silicon content>83%, carbon content<1.5%, phosphorus content<0.2%. Since the sintered material contains a large amount of calcium oxide, it plays a role of desulfurization in the high-temperature smelting stage. Finally, the sulfur content in the ferromanganese silicon alloy is reduced to below 0.01%. The specific reaction is as follows: MnO+SiO2+FeO+3C=MnSi(Fe)+3CO.

[0066] The system used in the method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder of the present invention is as follows: Figure 2 As shown, zinc-silicon-manganese alloy dust, rotary hearth furnace undersize powder and reducing agent are placed in dust ash silo 1, undersize powder silo 2 and reducing agent silo 3, coke and quicklime are placed in coke silo 6 and quicklime silo 7 respectively, dust ash silo 1, undersize powder silo 2 and reducing agent silo 3 are connected to the feed port of rotary kiln 4 through belts, the discharge port of rotary kiln 4 is connected to the feed port of ore-fired electric furnace 5, and coke silo 6 and quicklime silo 7 are connected to the feed port of ore-fired electric furnace 5 through belts.

[0067] The following is a further introduction to the high-value utilization method of the zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder of the present invention in conjunction with specific examples. In the following embodiments, the zinc-containing silicon-manganese alloy dust and the rotary hearth furnace undersize powder are formed into three kinds of mixed materials according to a mass ratio of 100:4.5-8.5, and Mn / Fe is controlled to be ≥8. The composition of the zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder mixed materials is shown in Table 4 below;

[0068] Table 4 Composition of mixed materials (%)

[0069] Element TFe FeO Zn Mn <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO P S Mix 1 2.5 1.3 7 20 10 2 0.1 0.25 0.25 0.1 Mix 2 3.2 1.55 12.5 25 15 2.8 0.15 0.33 0.38 0.16 Mix 3 3.8 1.8 15 30 20 3.5 0.2 0.4 0.5 0.22

[0070] Example 1

[0071] The method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder in this embodiment is as follows:

[0072] Mixture 1 and reducing agent coal are added to the rotary kiln in a ratio of 100:2 for pre-reduction roasting. The temperature of the rotary kiln is controlled at 600-1150°C, preheated for 40 minutes, and then kept at 1150°C for 60 minutes. The sintered material is then cooled in the discharge area for 30 minutes and the temperature is reduced from 1150°C to 700°C before being discharged. The zinc volatilization rate of mixture 1 during the pre-reduction roasting process is 88.2%, and secondary zinc oxide powder with a zinc grade of 60.25% is obtained. After roasting, mixture 1 is obtained to obtain sintered material 1, and the composition is shown in Table 5 below.

[0073] The sintering material 1 is hot charged into the electric furnace for smelting, and quicklime is added to ensure that the binary basicity of the sintering material is 0.8. Coke with a particle size of 3-5 mm is added as a reducing agent. The ratio of the sintering material to the coke is 100:15. The smelting in the electric furnace is divided into the first stage, the temperature is controlled at 1500°C, the dephosphorization time is 30min, and the phosphorus removal rate is 90.11%. After the first stage of dephosphorization, the electric furnace is heated to 1600°C to start the second stage of smelting ferromanganese silicon alloy, the binary basicity is controlled at 0.8, the smelting time is 1h, and the smelting is completed. High-quality ferromanganese silicon alloy and metallurgical slag with TFe content ≤16%, manganese silicon content>83%, carbon content<1.5%, and phosphorus content<0.2% are obtained. Finally, the sulfur content in the ferromanganese silicon alloy is reduced to below 0.01%.

[0074] Example 2

[0075] The method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder in this embodiment is as follows:

[0076] Mixture 2 and reducing agent coal are added to the rotary kiln in a ratio of 100:3 for pre-reduction roasting. The temperature of the rotary kiln is controlled at 600-1150°C, preheated for 50 minutes, and then kept at 1150°C for 70 minutes. The sintered material is then cooled in the discharging area for 40 minutes and the temperature is reduced from 1180°C to 700°C before being discharged. The zinc volatilization rate of mixture 1 during the pre-reduction roasting process is 90.05%, and secondary zinc oxide powder with a zinc grade of 61.83% is obtained. Mixture 2 is roasted to obtain sintered material 2, and the composition is shown in Table 5 below.

[0077] The sintered material 2 is hot charged into the electric furnace for smelting, and quicklime is added to ensure that the binary basicity of the sintered material is 0.8. Coke with a particle size of 3-5 mm is added as a reducing agent. The ratio of the sintered material to the coke is 100:18. The smelting in the electric furnace is divided into the first stage of temperature control at 1525°C, dephosphorization time 30min, and phosphorus removal rate 91.63%. After the first stage of dephosphorization, the electric furnace is heated to 1620°C to start the second stage of smelting ferromanganese silicon alloy, the binary basicity is controlled at 1.0, the smelting time is 1h, and the smelting is completed. High-quality ferromanganese silicon alloy and metallurgical slag with TFe content ≤16%, manganese silicon content>83%, carbon content <1.5%, and phosphorus content <0.2% are obtained. Finally, the sulfur content in the ferromanganese silicon alloy is reduced to below 0.01%.

[0078] Example 3

[0079] The method for high-value utilization of zinc-silicon-manganese alloy dust and rotary hearth furnace undersize powder in this embodiment is as follows:

[0080] Mixture 3 and reducing agent coal are added to the rotary kiln in a ratio of 100:3 for pre-reduction roasting. The temperature of the rotary kiln is controlled at 600-1150°C, preheated for 50 minutes, and then kept at 1200°C for 70 minutes. The sintered material is then cooled in the discharging area for 40 minutes and the temperature is reduced from 1150°C to 700°C before being discharged. The volatilization rate of zinc in mixture 3 during the pre-reduction roasting process is 91.88%, and secondary zinc oxide powder with a zinc grade of 62.86% is obtained. After roasting, mixture 3 is obtained to obtain sintered material 3, and the composition is shown in Table 5 below.

[0081] The sintering material 3 is hot charged into the electric furnace for smelting, and quicklime is added to ensure that the binary basicity of the sintering material is 0.8. Coke with a particle size of 3-5 mm is added as a reducing agent. The ratio of the sintering material to the coke is 100:18. The smelting in the electric furnace is divided into the first stage of temperature control at 1550°C, dephosphorization time 30min, and phosphorus removal rate 92%. After the first stage of dephosphorization, the electric furnace is heated to 1650°C to start the second stage of smelting ferromanganese silicon alloy, the binary basicity is controlled at 1.2, the smelting time is 1h, and the smelting is completed. High-quality ferromanganese silicon alloy and metallurgical slag with TFe content ≤16%, manganese silicon content>83%, carbon content <1.5%, and phosphorus content <0.2% are obtained. Finally, the sulfur content in the ferromanganese silicon alloy is reduced to below 0.01%.

[0082] Table 5 Composition of sintering material (%)

[0083] Element TFe FeO Zn Mn <![CDATA[SiO2]]> CaO <![CDATA[Al2O3]]> MgO P S Sintering material 1 6 3 0.2 50 25 5 0.4 0.55 0.28 0.12 Sintering material 2 6.23 3.67 0.24 52 28.63 5.48 0.41 0.63 0.43 0.18 Sintering material 3 7 4 0.3 55 28.63 5.48 0.41 0.63 0.32 0.25

[0084] Those skilled in the art should recognize that the above embodiments are only used to illustrate the present invention, and are not intended to limit the present invention. As long as they are within the spirit of the present invention, any changes or modifications to the above embodiments will fall within the scope of the claims of the present invention.

Claims

1. A method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder, characterized in that: The following steps are involved: S1, adding zinc-containing silicon-manganese alloy dust, rotary hearth furnace undersize powder, and a reducing agent into a rotary kiln for pre-reduction roasting to obtain sintering material and zinc-containing flue gas, and recovering the zinc-containing flue gas to obtain secondary zinc oxide powder; S2, hot charging the sintered material into a submerged arc furnace for smelting, and adding quicklime and coke, and obtaining ferromanganese silicon alloy and metallurgical slag after the smelting.

2. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1 is characterized in that: In step S1: The mass ratio of the zinc-containing silicon-manganese alloy dust to the rotary hearth furnace undersize powder is 100:4.5-8.5, and the Mn / Fe in the mixture of the zinc-containing silicon-manganese alloy dust and the rotary hearth furnace undersize powder is controlled to be ≥8; The mass ratio of the mixture of the zinc-containing silicon-manganese alloy dust ash and the rotary hearth furnace undersize powder to the reducing agent is 100:2-4.

3. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In step S1: The mixture of the zinc-silicon-manganese alloy dust and the rotary hearth furnace undersize powder has a TFe content of 2.5-3.8wt%, a Zn content of 7-15wt%, a Mn content of 20-30wt%, a SiO2 content of 10-20wt%, and a CaO content of 2-3.5wt%; The reducing agent is coal, and its particle size is less than 3mm.

4. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In the step S1, during the pre-reduction roasting process, the temperature of the rotary kiln is 600-1150°C, the preheating time is 40-60 minutes, and the temperature is kept at 1150-1200°C for 60-80 minutes. After that, the sintered material is cooled to 700°C in the discharge zone before being discharged.

5. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In step S1: The sintering material has a TFe content of 6-7wt%, a Mn content of 50-55wt%, a SiO2 content of 25-33wt%, and a CaO content of 5-6wt%; The zinc content of the secondary zinc oxide powder is more than 60%.

6. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In step S2: During the smelting process of the ore-fired electric furnace, the binary basicity in the sintering material is controlled to be 0.8-1.2 by adding quicklime; The particle size of the coke is 3-5 mm, and the mass ratio of the sintering material to the coke is 100:15-20.

7. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In step S2: The smelting in the electric furnace is divided into two stages. The first stage is a low-temperature dephosphorization stage, the temperature is controlled at 1500-1520°C, and the dephosphorization time is 30-50 minutes. After the first stage of dephosphorization is completed, the electric furnace is heated to 1600-1650°C to start the second stage of smelting manganese silicon iron alloy, and the smelting time is 1-1.5 hours.

8. The method for high-value utilization of zinc-containing silicon-manganese alloy dust and rotary hearth furnace undersize powder according to claim 1, characterized in that: In step S2: In the ferromanganese-silicon alloy, the TFe content is ≤16%, the manganese-silicon content is greater than 83%, the carbon content is less than 1.5%, the phosphorus content is less than 0.2%, and the sulfur content is less than 0.01%.

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