A collaborative treatment process for zinc-containing fly ash and red mud in steel mills

Abstract

The present invention relates to a collaborative treatment process for zinc-containing steel mill fly ash and red mud, comprising the following steps: uniformly mixing the zinc-containing steel mill fly ash to be treated with red mud in a mass ratio of 1-3:1, forming pellets to obtain pellets; adding the pellets, a reducing agent, and a flux to a molten bath smelting furnace, bubbling oxygen-enriched air, and smelting to obtain zinc-containing flue gas and molten iron; condensing the zinc-containing flue gas to obtain zinc liquid; and then smelting the zinc liquid and casting ingots to obtain zinc ingots. The present invention utilizes zinc-containing steel mill fly ash and red mud to directly smelt and produce pig iron and zinc ingots, greatly shortening the existing disposal process, obtaining high-value-added products, and simultaneously realizing the resourceful treatment of zinc-containing steel mill fly ash and red mud.

Description

Technical Field

[0001] The invention relates to a collaborative treatment process for zinc-containing fly ash and red mud in a steel plant, belonging to the technical field of comprehensive recovery of non-ferrous metals. Background Art

[0002] The zinc-containing fly ash in steel mills is mainly composed of blast furnace gas ash (mud) and electric furnace ash. The zinc in gas ash (mud) is mainly due to the continuous enrichment of low-grade zinc in the raw materials during the "large and small cycles", while the electric furnace ash is mainly due to the high zinc content of the raw materials during the smelting process of scrap steel, resulting in a higher zinc content in the smoke.

[0003] At present, the pyrometallurgical processes for the disposal of zinc-containing fly ash mainly include the rotary kiln reduction method and the rotary hearth furnace method, and their products are mainly direct reduced iron or sponge iron, and zinc mainly enters the flue gas for reoxidation and then enters the smoke to obtain a secondary zinc oxide product. The main purpose of this type of process is to remove zinc, and only zinc and iron intermediate products are obtained, which still need to be further disposed of. For example, the zinc-containing fly ash treatment method of Chinese Patent Publication No. CN103740939A needs to first make pellets or blocks and ensure that it has a certain strength, and coke needs to be used as a reducing agent, which is no different from a conventional ironmaking process. Chinese Patent Publication No. CN112080645A only treats the single zinc-containing fly ash, and does not fully consider the coordinated disposal with other hazardous wastes, and the recovered products are zinc oxide and iron, and it is impossible to obtain zinc ingots in one step. Chinese Patent Publication No. CN112941331A discloses a method for treating electric furnace ash using a molten reduction process. The method involves mixing the electric furnace ash, an internal reducing agent, a binder, and water, forming pellets, and drying them to obtain pellets. The pellets are then smelted, with flux, an external reducing agent, and a slag-forming agent added in stages during the smelting process. Upon completion of the smelting process, zinc-containing flue gas, molten iron, and slag are obtained, respectively. While this method can effectively treat the electric furnace ash, it requires the addition of a binder for granulation, which increases costs and may result in an increased amount of slag.

[0004] Red mud is an industrial solid waste produced during the extraction of alumina by the aluminum industry. It is called red mud because of its high iron oxide content and its resemblance to reddish earth. Depending on the ore grade, production methods, and technological level, approximately 1.0 to 1.8 tons of red mud are emitted for every ton of alumina produced. With the development of the aluminum industry, red mud stockpiles are increasing, causing increasingly serious environmental pollution. Maximizing its resource utilization is imperative. Red mud typically contains a high sodium content, which can corrode the kiln's refractory bricks when processed using pyrometallurgical methods. Furthermore, red mud has a high moisture content and typically requires drying to a certain degree before it can be added to the furnace. Summary of the Invention

[0005] In view of the deficiencies of the prior art, the object of the present invention is to provide a collaborative treatment process for zinc-containing fly ash and red mud from steel mills, so as to achieve the collaborative resource treatment of zinc-containing fly ash and red mud from steel mills.

[0006] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0007] A process for the coordinated treatment of zinc-containing fly ash and red mud in a steel plant comprises the following steps:

[0008] S1. uniformly mixing the zinc-containing fly ash from the steel mill to be treated with red mud in a mass ratio of 1-3:1, and forming pellets to obtain pellets;

[0009] The zinc-containing fly ash of the steel plant has an Fe content of 20-50wt%, a Zn content of 5-30wt%, a Pb content of 0-4wt%, a C content of 0-2wt%, a S content of 0-1wt%, a CaO content of 2-10wt%, a MnO content of 0-5wt%, a MgO content of 1-10wt%, an Al2O3 content of 0-1wt%, and a SiO2 content of 2-5wt%;

[0010] The red mud has an Fe content of 30-70 wt%, an Al2O3 content of 10-20 wt%, a Na2O content of 2-10 wt%, a K2O content of 0-1 wt%, a CaO content of 2-8 wt%, a TiO2 content of 0-8 wt%, and a MgO content of 0-1 wt%;

[0011] S2, adding the pellets, reducing agent and flux into a molten pool smelting furnace, blowing in oxygen-enriched air, and smelting to obtain zinc-containing fume and molten iron;

[0012] The smelting temperature is 1400-1550°C, and the reducing atmosphere in the molten pool smelting furnace is controlled to meet the following requirements: the molar ratio of CO to CO2 is 1.5-2.5; the pellets and flux added generally meet the following requirements: (CaO+MgO) / SiO2=0.8-1.4, (CaO+MgO) / (SiO2+Al2O3)=0.6-1.2, and Na2O / (CaO+MgO+SiO2+Al2O3)=0.05-0.2; the amount of the reducing agent added is 10-30wt% of the pellets;

[0013] S3. Condensing the zinc-containing flue gas to obtain zinc liquid; and then melting and casting the zinc liquid to obtain zinc ingots.

[0014] In the present invention, (CaO+MgO) / SiO2 refers to the ratio of the total mass of CaO and MgO in the added pellets and flux to the mass of SiO2; (CaO+MgO) / (SiO2+Al2O3) refers to the ratio of the total mass of CaO and MgO in the added pellets and flux to the total mass of SiO2 and Al2O3; Na2O / (CaO+MgO+SiO2+Al2O3) refers to the ratio of the mass of Na2O in the added pellets and flux to the total mass of CaO, MgO, SiO2 and Al2O3.

[0015] Zinc-containing fly ash and red mud both contain valuable elements such as zinc and iron of high quality, and have extremely high recycling value. Red mud contains calcium oxide, aluminum oxide, silicon dioxide, potassium salt, sodium salt and other components that are helpful for slag formation, which can effectively make up for the shortcoming of adding a large amount of slag forming agent when treating zinc-containing fly ash alone. At the same time, red mud contains a high amount of water and has a certain degree of adhesion, and cannot be directly put into the furnace for smelting. Zinc-containing fly ash has low water content and is loose. The present invention combines the advantages and disadvantages of the two materials and complements each other. The two are first mixed, and the viscosity of red mud is used to achieve pelletization without adding binders and other substances. The pellets are then smelted in a molten pool to obtain zinc-containing flue gas and pig iron, thereby separating zinc and iron. The zinc-containing flue gas is then subjected to simple condensation to separate and obtain zinc liquid.

[0016] At the same time, the present invention can effectively lower the melting point of the entire smelting system and promote the volatilization of zinc by synergistically treating zinc-containing fly ash and red mud, combining the properties of the two materials and complementing each other's advantages, thereby achieving the purpose of efficient low-temperature reduction smelting to extract zinc and smelt iron.

[0017] The present invention adjusts the amount of Na2O in the incoming materials, and thus the concentration of Na2O in the slag, by adjusting the ratio of zinc-containing fly ash to red mud. The pH is adjusted by adding a flux. The applicant's research has found that too low a Na2O content in the smelting reaction system prevents low-temperature smelting, while too high a Na2O content corrodes refractory bricks and reduces the service life of the molten bath smelting furnace.

[0018] In the present invention, the amount of the reducing agent added is 10-30wt% of the pellets, and its main purpose is to ensure sufficient reducing atmosphere during the smelting process, thereby preventing secondary oxidation of zinc.

[0019] Furthermore, in S1, the mass ratio of zinc-containing fly ash to red mud in the steel plant is 1-4:1.

[0020] Furthermore, in S1, the particle size of the pellets is 20 mm to 40 mm.

[0021] Furthermore, in S2, the concentration of the oxygen-enriched air is 40-80 vol%, preferably 60-80 vol%; the blowing amount of the oxygen-enriched air is 200-600 m 3 / t-pellets. By using oxygen-enriched air with an oxygen concentration of 60-80%, the amount of flue gas can be effectively reduced, the amount of heat carried away by the flue gas can be reduced, the concentration of zinc vapor can be increased, and the zinc vapor can be more easily condensed and captured. Conventional non-melt pool smelting technologies, such as blast furnace ironmaking and blast furnace zinc smelting, cannot introduce high-concentration oxygen-enriched air due to the presence of the material column. At the same time, the temperature zones in the process furnace are distributed in a stepped manner, and the reaction rate is much lower than the melt pool smelting process. It is often necessary to ensure that the material entering the furnace is at a higher zinc grade. For example, the blast furnace zinc smelting process usually needs to ensure that the zinc grade of the material entering the furnace is above 40%. The present invention accelerates the smelting efficiency through oxygen-enriched melt pool smelting, can improve the instantaneous zinc vapor concentration, and solves the problem that low-grade zinc-containing materials (the zinc content of zinc-containing fly ash is not prominent, and the zinc content will be further reduced by red mud pelletizing) cannot meet the zinc vapor concentration requirements of conventional pyrometallurgical zinc smelting processes.

[0022] Furthermore, the instantaneous zinc vapor concentration in the zinc-containing flue gas needs to be greater than 5wt%, which can facilitate subsequent condensation and capture. If the zinc vapor concentration is too low, the subsequent capture efficiency will be reduced and the recovery rate will be reduced. The present invention adopts molten pool smelting and controls the concentration of oxygen-enriched air to make the zinc vapor concentration within an appropriate range.

[0023] Furthermore, the zinc-containing fly ash from the steel plant includes one or more of blast furnace gas ash (mud) and electric furnace ash.

[0024] Furthermore, in S2, the smelting temperature is 1450-1500°C.

[0025] Furthermore, in S2, during smelting, natural gas is injected into the molten pool smelting furnace. Optionally, the amount of natural gas used is 100 to 350 m3. 3 / t-pellets, preferably 100-200m 3 / t-Pellets.

[0026] Furthermore, in S2, the reducing atmosphere in the molten pool smelting furnace is controlled to satisfy: the molar ratio of CO to CO2 is 1.5-2.

[0027] Furthermore, in S2, the reducing agent includes one or more of carbon essence, waste activated carbon, coking coal, anthracite, and coke.

[0028] Furthermore, in S2, the flux includes one or more of limestone, quartz stone, and dolomite; preferably, the flux is limestone.

[0029] Furthermore, in S2, the outlet temperature of the zinc-containing flue gas is higher than 1000°C, so as to prevent secondary oxidation of zinc vapor and prevent the reaction ZnO+CO=Zn+CO2 from proceeding in reverse.

[0030] Furthermore, in S3, a lead rain condenser is used to condense the zinc-containing flue gas.

[0031] Optionally, the zinc-containing flue gas is passed directly from the exhaust port of the molten pool smelting furnace into a lead rain condenser, where it is cooled to below 550°C, preferably below 500°C, after heat exchange with the lead rain. This significantly reduces the saturated vapor pressure of the zinc vapor to a lower value, allowing for better recovery of zinc from the flue gas. After rapid cooling in the lead rain condenser, the zinc vapor condenses into zinc liquid and is captured in the lead liquid. The lead and zinc are precipitated and separated, and the lead liquid is returned to the lead rain condenser for reuse. The zinc liquid is further smelted and cast into zinc ingots. The remaining flue gas is purified through flue gas purification processes such as surface coolers and bag filters to obtain clean flue gas with a high CO concentration, which can be further used for combustion and energy supply.

[0032] Red mud contains a high amount of water. If it is processed alone, it needs to be dried to a certain water content before being put into the furnace. However, zinc-containing fly ash has a lower water content. If it is directly put into the furnace, it will increase the amount of smoke and dust. The present invention combines the two, which can not only solve the above-mentioned problems caused by separate treatment, but also because red mud has a certain viscosity, it can completely replace the binder required in the pelletizing process, and can obtain smelting pellets with a certain strength, further reducing the amount of dust.

[0033] Red mud contains a large amount of sodium aluminate, which can effectively lower the melting point of the molten system during the molten pool smelting process of the present invention; at the same time, silicon oxide, calcium oxide, and aluminum oxide in the red mud can also act as flux, which can reduce the amount of flux used, reduce costs, and improve the smelting effect.

[0034] Red mud is rich in iron. The present invention combines red mud with zinc-containing fly ash to increase the iron content of the mixture. Both zinc-containing fly ash and red mud from steel mills contain high iron content. Mixing the two ensures a high iron content in the raw materials, enabling the production of molten iron during the smelting process.

[0035] Red mud has a high sodium content, making it highly corrosive to refractory bricks when treated alone. This invention combines red mud with zinc-containing fly ash and processes them together to reduce the sodium content in the red mud and control the sodium ratio in the molten bath. This effectively lowers the melting point and prevents sodium salts from corroding the refractory bricks in the molten bath furnace. Adding external sodium salts, such as sodium carbonate, sodium sulfate, or sodium chloride, not only results in high costs, but also generates CO2, SO2, and NaCl gases at high temperatures, which can destabilize the smelting system. This invention utilizes the sodium inherent in the red mud to effectively avoid these issues.

[0036] The smelting temperature of conventional ironmaking processes is higher than 1500℃. The present invention can significantly reduce the smelting temperature by co-processing zinc-containing fly ash with red mud and relying on the Na2O in the red mud. That is, the material can be melted when the temperature is controlled at 1400℃ to 1450℃, and has good fluidity, which can achieve good separation of molten iron and slag. Figure 2 and Figure 3 It can be seen that adding sodium oxide to the CaO-MgO-SiO2 ternary slag to form the Na2O-CaO-MgO-SiO2 quaternary slag can effectively reduce the slag melting temperature, thereby making low-temperature smelting possible.

[0037] The present invention controls the reducing atmosphere at CO / CO2=1.5-2.5, which can ensure that the molten pool smelting furnace has a strong reduction potential during the smelting process, thereby preventing zinc vapor from being secondary oxidized to form zinc oxide, which makes it impossible to capture and recover zinc in the form of elemental zinc. In addition, the higher reduction potential is conducive to the positive reduction reaction of iron.

[0038] Optionally, during the smelting process in the molten pool, the molten iron is discharged through the tap hole, and a pig iron product is obtained after casting; the slag is discharged through the slag tap hole, and the slag is rapidly cooled (such as water quenching) to obtain water-quenched slag.

[0039] The main reactions occurring during the molten pool smelting process are as follows:

[0040] (1) Redox reaction:

[0041] 2C+O2=2CO

[0042] ZnFe2O4+C=ZnO+2FeO+CO(g)

[0043] 2ZnO+C=2Zn+CO2(g)

[0044] ZnO+CO=Zn+CO2(g)

[0045] 2Zn+O2=2ZnO

[0046] 2Fe2O3+C=4FeO+CO2(g)

[0047] 2FeO+C=2Fe+CO2(g)

[0048] Fe2O3+CO=2FeO+CO2(g)

[0049] FeO+CO=Fe+CO2(g)

[0050] Zn2SiO4+CaO=2ZnO+CaSiO3

[0051] 2FeO·SiO2+CaO=2FeO+CaSiO3

[0052] Zn2SiO4+Na2O=2ZnO+Na2SiO3

[0053] 2FeO·SiO2+Na2O=2FeO+Na2SiO3

[0054] 3Fe+C=Fe3C

[0055] (2) Slag formation reaction

[0056] MgO+SiO2=MgO·SiO2

[0057] CaO+SiO2=CaO·SiO2

[0058] Al2O3+2SiO2=Al2O3·2SiO2

[0059] Na2O+SiO2=Na2SiO3

[0060] NaAlO2+3SiO2=NaAlSi3O8

[0061] The present invention synergistically treats zinc-containing fly ash and red mud from a steel plant, and can obtain zinc ingots and pig iron products by regulating the atmosphere and slag type. Under the premise of efficiently recovering valuable metals, the smelting energy consumption and smelting process are further reduced, zinc and iron are separated, and the final product is obtained in one step, which can effectively shorten the treatment process of zinc-containing fly ash and reduce disposal energy consumption.

[0062] Compared with the prior art, the present invention has the following beneficial effects:

[0063] 1) The present invention utilizes zinc-containing fly ash and red mud from steel mills to directly smelt and produce pig iron and zinc ingots, which greatly shortens the existing disposal process, can obtain high-value-added products, and at the same time realizes the resource treatment of zinc-containing fly ash and red mud from steel mills.

[0064] 2) The present invention synergistically disposes zinc-containing fly ash from steel mills and red mud, complementing each other's advantages, achieving low-temperature zinc extraction and ironmaking, rationally recycling and utilizing the valuable metals in the two hazardous wastes, avoiding the use of binders and other substances, reducing energy consumption, and realizing green resource recovery.

[0065] 3) Conventional methods (such as rotary kiln and rotary hearth furnace treatment processes) for treating zinc-containing fly ash generally produce secondary zinc oxide products or iron-containing pellets, which require further treatment to obtain pig iron or zinc ingots. The method of the present invention can generate elemental iron and elemental zinc in one step, greatly reducing the overall energy consumption. BRIEF DESCRIPTION OF THE DRAWINGS

[0066] Figure 1The invention relates to a collaborative treatment process for zinc-containing fly ash and red mud in a steel plant.

[0067] Figure 2 It is the Na2O-CaO-MgO-SiO2 quaternary slag phase diagram.

[0068] Figure 3 It is a CaO-MgO-SiO2 ternary slag phase diagram. DETAILED DESCRIPTION

[0069] The present invention will be described in detail below with reference to the embodiments. It should be noted that, unless otherwise specified, the embodiments and features of the embodiments of the present invention may be combined with each other. Unless otherwise specified, the relevant percentages are percentages by mass.

[0070] like Figure 1 As shown, a process for the coordinated treatment of zinc-containing fly ash and red mud in a steel plant comprises the following steps:

[0071] S1. uniformly mixing the zinc-containing fly ash from the steel mill to be treated with red mud in a mass ratio of 1-3:1, and forming pellets to obtain pellets;

[0072] Wherein, referring to Table 1, the zinc-containing fly ash of the steel plant has an Fe content of 20-50wt%, a Zn content of 5-30wt%, a Pb content of 0-4wt%, a C content of 0-2wt%, a S content of 0-1wt%, a CaO content of 2-10wt%, a MnO content of 0-5wt%, a MgO content of 1-10wt%, an Al2O3 content of 0-1wt%, and a SiO2 content of 2-5wt%;

[0073] Referring to Table 2, the red mud has an Fe content of 30-70 wt%, an Al2O3 content of 10-20 wt%, a Na2O content of 2-10 wt%, a K2O content of 0-1 wt%, a CaO content of 2-8 wt%, a TiO2 content of 0-8 wt%, and a MgO content of 0-1 wt%;

[0074] S2, adding the pellets, reducing agent and flux into a molten pool smelting furnace, blowing in oxygen-enriched air, and smelting to obtain zinc-containing fume and molten iron;

[0075] Among them, the smelting temperature is 1400-1550℃, and the reducing atmosphere in the molten pool smelting furnace is controlled to meet the following requirements: the molar ratio of CO to CO2 is 1.5-2.5; the added pellets and flux generally meet the following requirements: (CaO+MgO) / SiO2=0.4-1.4, (CaO+MgO) / (SiO2+Al2O3)=0.6-1.2, Na2O / (CaO+MgO+SiO2+Al2O3)=0.05-0.2; the amount of the reducing agent added is 20-50wt% of the pellets; the amount of the flux added is 2-6wt% of the pellet mass.

[0076] S3. Condensing the zinc-containing flue gas to obtain zinc liquid; and then melting and casting the zinc liquid to obtain zinc ingots.

[0077] In S1, the mass ratio of zinc-containing fly ash from the steel plant to red mud is 1.5-2.5: 1. The particle size of the pellets is 20 mm to 40 mm.

[0078] In S2, the concentration of the oxygen-enriched air is 40-80 vol%, preferably 60-80 vol%; the amount of oxygen-enriched air blown in is 200-600 m 3 / t. The smelting temperature is 1450-1500°C. During smelting, natural gas is injected into the molten bath furnace. By adding a reducing agent, the reducing atmosphere in the molten bath furnace is controlled to meet a molar ratio of CO to CO₂ of 1.5-2. The reducing agent includes one or more of carbon concentrate, spent activated carbon, coking coal, anthracite, or coke. The flux includes one or more of limestone, quartz, and dolomite.

[0079] In S3, a lead rain condenser is used to condense the zinc-containing flue gas, so that zinc enters the lead rain collector in the form of zinc vapor along with the flue gas to obtain a zinc ingot product.

[0080] The iron is discharged from the lower iron outlet of the liquid phase in the form of pig iron and slag phase, and the molten slag is discharged from the upper slag outlet.

[0081] Table 1 Main chemical composition of zinc-containing fly ash from steel mills

[0082]

[0083] Table 2 Main chemical components of red mud

[0084]

[0085] Example 1

[0086] A process for the coordinated treatment of zinc-containing fly ash and red mud in a steel plant comprises the following steps:

[0087] S1. uniformly mixing the zinc-containing fly ash from the steel mill to be treated with red mud containing 30% water in a mass ratio of 2:1, and pelletizing to obtain pellets;

[0088] The zinc-containing fly ash from the steel mill has an Fe content of 27.5wt%, a Zn content of 18.7wt%, a Pb content of 0.6wt%, a C content of 1.2wt%, a S content of 0.1wt%, a CaO content of 4.5wt%, a Mn content of 3.2wt%, a MgO content of 2.1wt%, an Al2O3 content of 1.6wt%, and a SiO2 content of 5.2wt%.

[0089] The red mud has an Fe content of 42.1 wt%, an Al2O3 content of 15.2 wt%, a Na2O content of 7.2 wt%, a K2O content of 1.3 wt%, a CaO content of 3.2 wt%, a TiO2 content of 0.2 wt%, and a MgO content of 0.3 wt%;

[0090] S2. adding the pellets, anthracite and quartz stone (flux) into a molten pool smelting furnace, blowing in oxygen-enriched air, and performing oxygen-enriched side-blowing smelting to obtain zinc-containing fume and melt;

[0091] The melt is placed in an electric heating front bed and layered to obtain pig iron and molten slag;

[0092] Among them, the smelting temperature is 1400℃, and the reducing atmosphere in the molten pool smelting furnace is controlled to meet the following conditions: the molar ratio of CO to CO2 is 1.7; the added pellets and flux generally meet the following conditions: (CaO+MgO) / SiO2=1.0, (CaO+MgO) / (SiO2+Al2O3)=0.6 (i.e., quaternary alkalinity), Na2O / (CaO+MgO+SiO2+Al2O3)=0.08; the amount of the reducing agent (anthracite) added is 18wt% of the pellets; and the amount of the flux added is 3% of the mass of the pellets.

[0093] S3. Condensing the zinc-containing flue gas to obtain zinc liquid; and then melting and casting the zinc liquid to obtain zinc ingots.

[0094] In S1, the mass ratio of zinc-containing fly ash from the steel plant to red mud is 1.5-2.5: 1. The particle size of the pellets is 25 mm.

[0095] In S2, the concentration of the oxygen-enriched air is 70 vol% and the injection rate of the oxygen-enriched air is 500 m3 / t. During smelting, 180 m3 / t of natural gas is injected into the molten pool smelting furnace.

[0096] In S3, a lead rain condenser is used to condense the zinc-containing flue gas, allowing the zinc to enter the lead rain collector as zinc vapor along with the flue gas, resulting in zinc ingots. The exhaust gas from the lead rain condenser is fed into an exhaust gas treatment system for treatment and discharge after meeting standards.

[0097] The molten iron solidifies to produce pig iron containing 91% iron and 2.5% carbon, with an iron recovery rate of 92.5%. The zinc ingot contains 99.6% zinc, with a zinc recovery rate of 98%.

[0098] Example 2

[0099] Example 1 was repeated, except that the amount of flux added was 5% of the pellet mass, the ternary basicity was 0.8, the quaternary basicity was 0.5, Na2O / (CaO+MgO+SiO2+Al2O3)=0.07, and the smelting temperature was 1450°C.

[0100] The pig iron contains 93% iron and 3.5% carbon, with an iron recovery rate of 96.5%. The zinc ingot contains 99.7% zinc, with a zinc recovery rate of 99%.

[0101] Comparative Example 1

[0102] Example 1 was repeated, except that the mass ratio of zinc-containing fly ash to red mud was 5:1, the ternary basicity was 1.0, the quaternary basicity was 0.7, and the Na₂O / (CaO+MgO+SiO₂+Al₂O₃) ratio was 0.03. Results: The slag viscosity was too high, the slag and gold did not separate, and proper slag tapping was impossible.

[0103] Example 3

[0104] Example 1 was repeated except that the smelting temperature was 1550°C. The pig iron contained 93% iron and 3.5% carbon, with an iron recovery rate of 89%. The zinc ingot had a zinc content of 99.6% and a zinc recovery rate of 99%.

[0105] Comparative Example 2

[0106] Example 1 was repeated, except that the mass ratio of zinc-containing fly ash to red mud was 0.8:1, the ternary basicity was 1.0, the quaternary basicity was 0.5, and Na2O / (CaO+MgO+SiO2+Al2O3)=0.14.

[0107] The pig iron contained 89% iron and 4.5% carbon, with an iron recovery rate of 76%. The zinc ingot contained 99.5% zinc, with a zinc recovery rate of 91%. The aluminum content in the slag was significantly increased, indicating severe corrosion of the high-aluminum refractory bricks used in the furnace hearth.

[0108] Comparative Example 4

[0109] Example 1 was repeated except that red mud was not added and zinc-containing fly ash was processed alone. The ternary basicity was 1.0 and the quaternary basicity was 0.85. The results were: the slag could not be completely melted, the slag and gold were not separated, and the slag could not be discharged normally.

[0110] Comparative Example 5

[0111] Example 1 was repeated, except that red mud was not added, and the zinc-containing fly ash was processed alone. The ternary basicity was 1.0, the quaternary basicity was 0.85, and the smelting temperature was 1600°C. The results showed that the pig iron contained 91% iron and 3.5% carbon, with an iron recovery rate of 92%. The zinc ingot had a zinc content of 99.4%, and a zinc recovery rate of 99%.

[0112] Comparative Example 6

[0113] Example 1 was repeated, except that zinc-containing fly ash was not added, and red mud was processed alone. The ternary basicity was 1.0, the quaternary basicity was 0.3, and Na₂O / (CaO+MgO+SiO₂+Al₂O₃)=0.25. The results showed that the slag melting point was too high, the slag and gold were not separated, and the slag could not be discharged normally.

[0114] Comparative Example 7

[0115] Example 1 was repeated, except that zinc-containing fly ash was not added, and red mud was processed alone. The ternary basicity was 1.0, the quaternary basicity was 0.3, the Na₂O / (CaO+MgO+SiO₂+Al₂O₃) ratio was 0.25, and the smelting temperature was 1600°C. The results showed that the slag could not be completely melted, the slag and gold were not separated, and normal slag tapping was impossible.

[0116] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

Claims

1. A process for the coordinated treatment of zinc-containing fly ash and red mud from a steel plant, characterized in that: The steps include: S1. uniformly mixing the zinc-containing fly ash from the steel mill to be treated with red mud in a mass ratio of 1-4:1, and pelletizing to obtain pellets; The zinc-containing fly ash of the steel mill has an Fe content of 20-70wt%, a Zn content of 5-30wt%, a Pb content of 0-4wt%, a C content of 0-2wt%, a S content of 0-1wt%, a CaO content of 2-10wt%, a MnO content of 0-5wt%, a MgO content of 1-10wt%, an Al2O3 content of 0-1wt%, and a SiO2 content of 2-5wt%. The red mud has an Fe content of 30-60 wt%, an Al2O3 content of 10-20 wt%, a Na2O content of 2-10 wt%, a K2O content of 0-1 wt%, a CaO content of 2-8 wt%, a TiO2 content of 0-8 wt%, and a MgO content of 0-1 wt%. S2, adding the pellets, reducing agent and flux into a molten pool smelting furnace, blowing in oxygen-enriched air, and smelting to obtain zinc-containing fume and molten iron; The smelting temperature is 1400-1550°C, and the reducing atmosphere in the molten pool smelting furnace is controlled to meet the following requirements: the molar ratio of CO to CO2 is 1.5-2.5; the pellets and flux added generally meet the following requirements: (CaO+MgO) / SiO2=0.8-1.4, (CaO+MgO) / (SiO2+Al2O3)=0.6-1.2, and Na2O / (CaO+MgO+SiO2+Al2O3)=0.05-0.2; the amount of the reducing agent added is 10-30wt% of the pellets; S3. Condensing the zinc-containing flue gas to obtain zinc liquid; and then melting and casting the zinc liquid to obtain zinc ingots.

2. The collaborative processing process according to claim 1, characterized in that: In S1, the mass ratio of zinc-containing fly ash to red mud from the steel plant is 1.5-2.5:

1.

3. The collaborative processing process according to claim 1, characterized in that: In S1, the particle size of the pellets is 20 mm to 40 mm.

4. The collaborative processing process according to claim 1, characterized in that: In S2, the concentration of the oxygen-enriched air is 40-80 vol%; the injection volume of the oxygen-enriched air is 200-600 m 3 / t.

5. The collaborative processing process according to claim 4, characterized in that: In S2, the concentration of the oxygen-enriched air is 60-80 vol%.

6. The collaborative processing process according to claim 1, characterized in that: In S2, the melting temperature is 1450-1500°C.

7. The collaborative processing process according to claim 1, characterized in that: In S2, natural gas is injected into the molten pool smelting furnace during smelting.

8. The collaborative processing process according to claim 1, characterized in that: In S2, the reducing atmosphere in the molten pool smelting furnace is controlled to satisfy the following conditions: the molar ratio of CO to CO2 is 1.5-2.

9. The collaborative processing method according to claim 1, characterized in that: In S2, the reducing agent includes one or more of carbon essence, waste activated carbon, coking coal, anthracite, and coke.

10. The collaborative processing method according to claim 1, characterized in that: In S2, the flux includes one or more of limestone, quartz stone, and dolomite.

11. The collaborative processing method according to claim 1, characterized in that: In S3, a lead rain condenser is used to condense the zinc-containing flue gas.

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