Method for utilizing all components of zinc-containing dust

Abstract

A method for utilizing all components of zinc-containing dust belongs to the technical field of metallurgical waste resourceful treatment, and comprises the following steps: adding water into zinc-containing dust and bentonite, stirring, pelletizing the mixture, and drying; the dried green pellets are fed into a rotary kiln, CO / CO2 mixed gas is introduced into the kiln for reduction roasting, the green pellets make uniform contact with the reducing atmosphere, zinc oxide is reduced into metal zinc and volatilized to generate zinc steam, and iron oxide is reduced into metal iron; zinc steam emitted from the rotary kiln is rapidly cooled and condensed into solid zinc powder, and then the solid zinc powder is collected intensively; cooling the reduced green pellets to room temperature, and crushing and screening to obtain an iron product; the whole system adopts closed operation, a bag-type dust collector and a gas condensing device are arranged at the discharge hole of the rotary kiln and the condenser, so that dust and waste gas generated in the reduction process are not leaked, and the waste gas generated by the rotary kiln is discharged after being treated to reach the standard, so that the influence on the environment is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of resource treatment of metallurgical waste, and specifically relates to a method for utilizing all components of zinc-containing dust. Background Art

[0002] Zinc dust is a solid waste generated during the smelting of steel and non-ferrous metals. It mainly comes from processes such as electric arc furnace steelmaking, converter steelmaking and hot-dip galvanizing. The global annual production volume is as high as 6 to 10 million tons, of which China's annual production accounts for more than 30%. Zinc dust has a complex composition, mainly containing 10% to 30% zinc oxide, 20% to 50% iron oxide, and a small amount of heavy metals such as lead and cadmium and silicate impurities. The particles of zinc dust are usually below 75μm. Its fine particles are not only easy to spread, but also the heavy metals contained in it have high biological toxicity. If it is not properly handled, it may cause soil and water pollution after discharge, threatening the ecological environment and human health. At the same time, if the zinc and iron resources rich in zinc dust are not fully recovered, it will cause a waste of resources.

[0003] At present, the treatment of zinc-containing dust is mainly hydrometallurgy and pyrometallurgy. Patent CN113957257A discloses a method for hydrometallurgical smelting of zinc-containing slag. The hydrometallurgical process represented by this method is relatively cumbersome, and strong acid or strong alkali needs to be added during the production process, which is easy to produce acidic or alkaline wastewater, which has a heavy burden on the environment, and the recovery rate of zinc and iron is low, and zinc and iron cannot be recovered efficiently. At this stage, the resource utilization of zinc-containing dust is still mainly based on pyrometallurgy. Patent CN106702169A discloses a method of reducing zinc-containing dust pellets using a ring roasting furnace, and then grinding and magnetic separation to recover zinc and iron. This method requires high temperature operation and consumes a lot of energy.

[0004] Existing pyrometallurgical treatment methods have many deficiencies in resource recovery. Although pyrometallurgy represented by the rotary kiln reduction method has potential, it is easy to cause agglomeration and incomplete reduction due to the fine dust particles, poor fluidity, and uneven atmosphere control. In addition, the existing processes generally have problems such as high energy consumption, complex operation, incomplete recovery and secondary pollution, making it difficult to achieve efficient resource utilization of zinc-containing dust. Based on this, the present invention proposes a method of mixing zinc-containing dust with bentonite to form balls, and then reducing and roasting in a rotary kiln. This method optimizes and adjusts the ball-forming process, accurately controls the temperature of the rotary kiln and the reducing atmosphere, not only achieving efficient separation and recovery of zinc and iron, but also simplifying the processing process, reducing energy consumption, and reducing secondary pollution. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for utilizing all components of zinc-containing dust, which specifically comprises the following steps:

[0006] S1. Pretreatment: adding water to the zinc-containing dust and bentonite and stirring them to uniformly mix the zinc-containing dust and bentonite, pelletizing the mixture, and drying the resulting green balls;

[0007] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is used for reduction roasting. The green balls are fully tumbled in the kiln and evenly contacted with the reducing atmosphere. The zinc oxide in the kiln is reduced to metallic zinc and volatilizes to generate zinc vapor. The iron oxide is reduced to generate metallic iron.

[0008] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled by the condenser at the end of the rotary kiln, condensed into solid zinc powder and then collected;

[0009] S4. Cooling and recovery of iron products: The reduced green balls leave the rotary kiln and are slowly cooled to room temperature in the air. After crushing and screening, iron products are obtained;

[0010] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0011] in:

[0012] In the step S1, the particle sizes of the zinc-containing dust and the bentonite are both ≤75 μm, and the mass ratio of the two is (45-55):1.

[0013] In the step S1, the mixing and stirring time of the zinc-containing dust and the bentonite is 30 minutes to 60 minutes, and the water content of the obtained mixture is 10% to 12%.

[0014] In the step S1, the particle size of the obtained green balls is 10 mm to 15 mm, the drying temperature of the green balls is 100° C. to 105° C., and the drying time is 4 h to 8 h.

[0015] In step S2, CO / CO 2 The volume fraction of CO in the mixed gas is 30% to 40%.

[0016] In step S2, the roasting temperature is 950°C to 1100°C, the rotation speed of the rotary kiln is 0.5r / min to 1r / min, and the green balls stay in the kiln for 45min to 120min.

[0017] In step S2, the specific reduction reaction is as follows:

[0018] ZnO+CO(g)=Zn+CO 2 (g) (1)

[0019] Fe 2 O 3 +CO(g)=Fe 3 O 4 +CO 2 (g) (2)

[0020] Fe 3 O 4 +CO(g)=3FeO+CO 2 (g) (3)

[0021] FeO+CO(g)=Fe+CO 2 (g) (4).

[0022] In step S3, the zinc vapor is cooled to below 600° C. to obtain solid zinc powder, and an inert gas is introduced into the condenser to prevent oxidation of the zinc powder during the condensation process, so that the zinc content in the zinc powder reaches more than 95%.

[0023] In step S4, the iron content in the iron product is ≥85%.

[0024] The key technical principle of the method for utilizing all components of zinc-containing dust of the present invention is:

[0025] This method utilizes the high-temperature reducing atmosphere in the rotary kiln to increase the particle fluidity and reaction contact area after balling, so as to promote the step-by-step reduction reaction of zinc oxide and iron oxide in zinc-containing dust, thereby achieving efficient separation and recovery of zinc and iron. The detailed technical principle can be explained as follows:

[0026] 1. Temperature control and step-by-step reduction principle: In the rotary kiln, the roasting temperature is controlled at 950℃~1100℃, which is suitable for the step-by-step reduction reaction of zinc oxide and iron oxide. Zinc oxide is first reduced to metallic zinc at this temperature. When the temperature reaches the boiling point of zinc (906℃), metallic zinc quickly evaporates into zinc vapor, while avoiding mutual interference between iron oxide and zinc, so that zinc and iron can be gradually separated. As the temperature rises further, iron oxide is gradually reduced to metallic iron in the reducing atmosphere and retained in the particles, thereby achieving effective recovery of iron resources.

[0027] 2.CO / CO 2 Reducing atmosphere control: by introducing CO / CO 2 The mixed gas is used to control the volume fraction of CO in the reducing atmosphere to 30% to 40%. CO has a strong reducing property and can effectively reduce zinc oxide to metallic zinc and further reduce iron oxide to metallic iron.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. Bentonite pelletizing omits the traditional agglomeration or high-temperature sintering steps, simplifies the process flow, and reduces equipment requirements and energy consumption.

[0030] 2. By optimizing the ball-making process and accurately controlling the roasting temperature and reducing atmosphere, efficient separation and recovery of zinc and iron are achieved.

[0031] 3. Zinc vapor is efficiently recovered through the condensation system, and pollutant emissions are reduced through a closed system, which reduces the risk of secondary pollution, meets environmental protection requirements, and is suitable for industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A process flow chart of a method for utilizing all components of zinc-containing dust according to the present invention;

[0033] Figure 2 Figure 1 shows the calcined products obtained in Example 1 of the present invention; wherein Figure (a) shows calcined pellets, and Figure (b) shows zinc powder. DETAILED DESCRIPTION

[0034] Example 1

[0035] A method for utilizing all components of zinc-containing dust, the process flow chart of which is as follows: Figure 1 As shown, the specific steps include:

[0036] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 49:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 60 minutes. The moisture content of the obtained mixture is 10%. The mixture is added to a disc ball making machine for ball making. The particle size of the obtained raw balls is 10mm. After ball making, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 105°C and dried for 6 hours.

[0037] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 950°C. The volume fraction of CO in the mixed gas is 30%. The speed of the rotary kiln is maintained at 1r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 60 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0038] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to improve the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.18%.

[0039] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 87.26% is obtained. The obtained roasted product is shown in the figure Figure 2 shown.

[0040] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0041] Example 2

[0042] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0043] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 46:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 45 minutes. The moisture content of the obtained mixture is 10%. The mixture is added to a disc pelletizer for pelletizing. The particle size of the obtained raw balls is 12mm. After pelletizing, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 105°C and dried for 8 hours.

[0044] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 1000°C. The volume fraction of CO in the mixed gas is 30%. The rotation speed of the rotary kiln is maintained at 0.5r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 80 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0045] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to improve the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.82%.

[0046] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 86.22% is obtained.

[0047] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0048] Example 3

[0049] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0050] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 48:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 40 minutes. The water content of the obtained mixture is 12%. The mixture is added to a disc ball making machine for ball making. The particle size of the obtained raw balls is 15mm. After ball making, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 100°C and the drying is performed for 8 hours.

[0051] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is used for reduction roasting at a temperature of 1100°C. The volume fraction of CO in the mixed gas is 30%. The speed of the rotary kiln is maintained at 0.5r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 120 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0052] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 97.26%.

[0053] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, iron products with an iron content of 88.35% are obtained.

[0054] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0055] Example 4

[0056] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0057] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 49:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 60 minutes. The water content of the obtained mixture is 11%. The mixture is added to a disc pelletizer for pelletizing. The particle size of the obtained raw balls is 12mm. After pelletizing, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 105°C and dried for 6 hours.

[0058] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 1000°C. The volume fraction of CO in the mixed gas is 40%. The rotation speed of the rotary kiln is maintained at 0.5r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 60 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0059] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.81%.

[0060] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 88.14% is obtained.

[0061] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0062] Example 5

[0063] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0064] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 51:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 45 minutes. The water content of the obtained mixture is 10%. The mixture is added to a disc ball making machine for ball making. The particle size of the obtained raw balls is 15mm. After ball making, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 100°C and the balls are dried for 8 hours.

[0065] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 950°C. The volume fraction of CO in the mixed gas is 30%. The rotation speed of the rotary kiln is maintained at 1r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 80 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0066] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.27%.

[0067] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 86.32% is obtained.

[0068] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0069] Example 6

[0070] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0071] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 50:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 50 minutes. The water content of the obtained mixture is 12%. The mixture is added to a disc ball making machine for ball making. The particle size of the obtained raw balls is 12mm. After ball making, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 105°C and dried for 8 hours.

[0072] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 1000°C. The volume fraction of CO in the mixed gas is 30%. The rotation speed of the rotary kiln is maintained at 0.5r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 45 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0073] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and collected to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.14%.

[0074] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, iron products with an iron content of 87.20% are obtained.

[0075] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0076] Example 7

[0077] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0078] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 52:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 45 minutes. The water content of the obtained mixture is 11%. The mixture is added to a disc pelletizer for pelletizing. The particle size of the obtained raw balls is 10mm. After pelletizing, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 105°C and dried for 5 hours.

[0079] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is used for reduction roasting at a temperature of 1000°C. The volume fraction of CO in the mixed gas is 40%. The speed of the rotary kiln is maintained at 1r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 60 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0080] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and then collected to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.42%.

[0081] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 87.12% is obtained.

[0082] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

[0083] Example 8

[0084] A method for utilizing all components of zinc-containing dust, specifically comprising the following steps:

[0085] S1. Pretreatment: zinc-containing dust (<75μm) and bentonite (<75μm) are placed in a blender at a mass ratio of 49:1, and water is added for stirring to make the zinc-containing dust and bentonite evenly mixed. The mixing and stirring time is 30 minutes. The water content of the obtained mixture is 10%. The mixture is added to a disc ball making machine for ball making. The particle size of the obtained raw balls is 12mm. After ball making, the raw balls are added to a vacuum oven for drying to improve their strength and thermal stability. The oven temperature is controlled at 100°C and the drying is performed for 8 hours.

[0086] S2. Reduction roasting: The dried green balls are sent to the rotary kiln, and CO / CO is introduced into the kiln. 2 The mixed gas is subjected to reduction roasting at a temperature of 950°C. The volume fraction of CO in the mixed gas is 40%. The rotation speed of the rotary kiln is maintained at 0.5r / min. The green balls are fully tumbled in the kiln and stay in the kiln for 120 minutes to be evenly exposed to the reducing atmosphere. The zinc oxide is reduced to metallic zinc and volatilizes to generate zinc vapor, and the iron oxide is reduced to generate metallic iron.

[0087] S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled to below 600°C through the condenser at the rear of the rotary kiln, condensed into solid zinc powder and collected centrally to increase the zinc recovery rate. Oxidation is avoided during the condensation process, and the zinc content in the zinc powder is measured to be 96.12%.

[0088] S4. Cooling and recovery of iron products: After reduction, the green balls leave the rotary kiln and are slowly cooled to room temperature in the air to retain the magnetism and purity of the metallic iron. The main components of the cooled green balls are metallic iron or magnetic oxides. After appropriate crushing and screening, an iron product with an iron content of 86.31% is obtained.

[0089] S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

Claims

1. A method for utilizing all components of zinc-containing dust, characterized in that: The specific steps include: S1. Pretreatment: adding water to the zinc-containing dust and bentonite and stirring them to uniformly mix the zinc-containing dust and bentonite, pelletizing the mixture, and drying the resulting green balls; S2. Reduction roasting: The dried green balls are sent to a rotary kiln, and a CO / CO2 mixed gas is introduced into the kiln for reduction roasting. The green balls are fully tumbled in the kiln and evenly exposed to the reducing atmosphere. The zinc oxide in the balls is reduced to metallic zinc and volatilized to generate zinc vapor, and the iron oxide is reduced to generate metallic iron. S3. Zinc vapor condensation and recovery: The zinc vapor emitted from the rotary kiln is rapidly cooled by the condenser at the end of the rotary kiln, condensed into solid zinc powder and then collected; S4. Cooling and recovery of iron products: The reduced green balls leave the rotary kiln and are slowly cooled to room temperature in the air. After crushing and screening, iron products are obtained; S5. Treatment of waste gas and dust: The whole system adopts closed operation. Bag dust collector and gas condensation device are installed at the discharge port and condenser of the rotary kiln to ensure that the dust and waste gas generated during the reduction process will not leak out. The waste gas generated by the rotary kiln is discharged after being treated to meet the standards to reduce the impact on the environment.

2. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In the step S1, the particle sizes of the zinc-containing dust and the bentonite are both ≤75 μm, and the mass ratio of the two is (45-55):

1.

3. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In the step S1, the mixing and stirring time of the zinc-containing dust and the bentonite is 30 minutes to 60 minutes, and the water content of the obtained mixture is 10% to 12%.

4. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In the step S1, the particle size of the obtained green balls is 10 mm to 15 mm, the drying temperature of the green balls is 100° C. to 105° C., and the drying time is 4 h to 8 h.

5. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In step S2, the volume fraction of CO in the CO / CO2 mixed gas is 30% to 40%.

6. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In step S2, the roasting temperature is 950°C to 1100°C, the rotation speed of the rotary kiln is 0.5r / min to 1r / min, and the green balls stay in the kiln for 45min to 120min.

7. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In step S3, the zinc vapor is cooled to below 600° C. to obtain solid zinc powder, and an inert gas is introduced into the condenser to prevent oxidation of the zinc powder during the condensation process, so that the zinc content in the zinc powder reaches more than 95%.

8. The method for utilizing all components of zinc-containing dust according to claim 1, characterized in that: In step S4, the iron content in the iron product is ≥85%.

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