Zinc-containing dust fluidization hydrogen group reduction comprehensive utilization method

Abstract

A zinc-containing dust fluidization hydrogen group reduction comprehensive utilization method belongs to the technical field of zinc-containing dust treatment, and comprises the following steps: screening and crushing collected zinc-containing dust, and then drying to obtain pretreated zinc-containing dust; nitrogen is introduced into the fluidization reaction device, the zinc-containing dust is added for heating, and after the temperature is stable, hydrogen is introduced to reduce the flow of the nitrogen; when the hydrogen flow reaches a specified value, the hydrogen channel is kept open, the nitrogen channel is closed, and fluidized hydrogen group reduction roasting is carried out by controlling the temperature; after gaseous zinc is formed, the gaseous zinc enters a condensation system with inert gas along with hydrogen flow to be condensed into metal zinc particles, the metal zinc particles are collected and recycled, and solid metal iron is reserved at the bottom of the reaction device; and the roasted gas enters a tail gas treatment system and is recycled after being purified. Hydrogen reduction adopted by the method has lower environmental influence, the rapid and thorough reduction process can be achieved under the high-temperature condition, and the current requirements of green metallurgy and low-carbon economy are met.

Description

Technical Field

[0001] The invention belongs to the technical field of zinc-containing dust treatment, and in particular relates to a method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction. Background Art

[0002] Zinc-containing dust is a byproduct of many industrial processes, especially in the production of steel and galvanized steel. For example, in the process of electric arc furnace steelmaking (EAF), due to high temperature treatment, the generated dust contains compounds such as zinc oxide and iron oxide. In addition, non-ferrous metal smelting (such as lead and zinc smelting) and the recycling of scrap galvanized metals also produce a large amount of zinc-containing dust. These dusts are rich in zinc and iron and have high recycling value, but due to their complex composition and fine particle size, they face great challenges in treatment and utilization. If left untreated, direct discharge or storage of these dusts will cause multiple hazards to the environment and human health. First, heavy metals in dust are easily spread by wind, polluting soil and water bodies, and the accumulation of elements such as zinc and iron in the natural environment will destroy the balance of the ecosystem. Second, dust particles are easily inhaled into the human body, and long-term exposure may cause respiratory and blood system diseases. In addition, dust storage will increase the risk of soil acidification and heavy metal migration, leading to groundwater pollution. Therefore, effective treatment and resource utilization of zinc-containing dust are urgent.

[0003] At present, the treatment technologies of zinc-containing dust mainly include pyrometallurgy and hydrometallurgy. Hydrometallurgy uses acid or alkaline solution to dissolve and separate zinc and iron in zinc-containing dust, which has a high metal recovery rate and good treatment effect. However, this method consumes a large amount of chemical reagents and produces a large amount of wastewater containing heavy metals, which increases the cost of waste liquid treatment and environmental risks. Therefore, pyrometallurgy has become one of the main methods for treating zinc-containing dust. Patent CN118374676A proposes a method for separating and recovering zinc and iron by reduction in a rotary hearth furnace after pelletizing. This type of traditional pyrometallurgical process mainly uses carbon-based reducing agents, which will emit greenhouse gases such as carbon dioxide and nitrogen oxides during the roasting process, with a high carbon footprint, which does not meet the requirements of green development. In addition, traditional pyrometallurgical processes usually require pelletizing and reduction roasting, the process is long and complicated, and problems such as uneven roasting of pellets and severe sintering often occur during the roasting process.

[0004] Therefore, an environmentally friendly and efficient zinc-containing dust treatment method is urgently needed to achieve efficient separation and recovery of zinc and iron, reduce environmental pollution and improve resource utilization. The fluidized hydrogen-based reduction technology proposed in the present invention not only avoids carbon emissions, but also significantly improves the reduction efficiency through the fluidization process, showing broad industrial application prospects. Summary of the invention

[0005] In view of the shortcomings of the prior art, the present invention provides a method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, which specifically comprises the following steps:

[0006] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm, and then dried to control the moisture content in the dust to less than 1%, thereby obtaining the pretreated zinc-containing dust;

[0007] S2. Preheating: nitrogen is introduced into the fluidized bed reactor for inert protection, and then the pretreated zinc-containing dust is added and heated. When the temperature in the reactor stabilizes at the target temperature, hydrogen is gradually introduced while reducing the nitrogen flow rate;

[0008] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches the specified value and stabilizes, the hydrogen fully contacts the dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to perform fluidized hydrogen-based reduction roasting, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron;

[0009] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized bed reactor along with the hydrogen flow and enters a condensation system with an inert gas. The condensation temperature is controlled to condense the gaseous zinc into metallic zinc particles, which are collected and recovered. The solid metallic iron remains at the bottom of the fluidized bed reactor.

[0010] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction and then recover it through a secondary hydrogen recovery device.

[0011] in:

[0012] In the step S1, the average particle size of the zinc-containing dust is between 25 μm and 500 μm, the mass fraction of zinc is between 10% and 30%, and the mass fraction of iron is between 20% and 60%.

[0013] In the step S1, the drying temperature of the treated zinc-containing dust is 100° C. to 105° C., and the drying time is 36 h to 48 h.

[0014] In step S2, the fluidized reaction device is a suspension roasting furnace.

[0015] In step S2, the nitrogen flow rate introduced into the fluidized reactor is 5m 3 / h~20m 3 / h, and the temperature in the reaction device is heated to 800℃~1000℃.

[0016] In step S3, the hydrogen flow rate is 3m 3 / h~15m 3 / h, the temperature in the reaction device is 850℃~1000℃, and the reduction reaction time is 10min~30min.

[0017] In step S3, the temperature in the reaction device is preferably 900°C to 950°C.

[0018] In step S3, the reaction equation of the fluidized hydrogen-based reduction roasting process is as follows:

[0019] ZnO + H2(g) = Zn(g) + H2O (1)

[0020] 3Fe2O3 + H2(g) = 2Fe3O4 + H2O (2)

[0021] Fe3O4 + 4H2(g) = 3Fe + 4H2O (3)

[0022] Fe3O4 + H2(g) = 3FeO + H2O (4)

[0023] FeO + H2(g) = Fe + H2O (5).

[0024] In step S4, the condensation temperature in the condensation system is controlled to be 450° C. to 550° C., and air is prevented from entering the condensation process of the gaseous zinc.

[0025] In the step S4, the zinc content of the obtained metallic zinc particles is ≥95%.

[0026] In step S4, the solid metallic iron is further purified through a separation process and then recycled.

[0027] In step S5, the unreacted hydrogen in the reaction waste gas is recovered and recycled, and the volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0028] The key technical principle of the method for comprehensive utilization of zinc-containing dust fluidized hydrogen-based reduction of the present invention is:

[0029] 1. The present invention adjusts the gas flow rate to suspend the zinc-containing dust in the gas to form a fluidized state similar to a liquid. Fluidization can significantly increase the contact area between solid particles and gas, improve the efficiency of the reduction reaction, and thus enhance the mass transfer and heat transfer efficiency of the reaction. During the fluidization process, the particles are suspended and move quickly, so that heat is quickly transferred between particles, and the reaction interface between hydrogen and the dust surface remains active, greatly accelerating the mass transfer process of the reduction reaction. At the same time, the suspended particles are in direct contact with the gas, so that the reaction temperature is evenly distributed, which improves the overall reaction rate.

[0030] 2. The present invention reacts zinc oxide in zinc-containing dust with hydrogen at a temperature of 850°C to 1000°C, especially at 900°C to 950°C, to generate gaseous metallic zinc and water vapor. The gaseous zinc rapidly volatilizes and enters the condensation system with the air flow for separation and recovery, while the iron oxide is gradually reduced to solid iron under the action of hydrogen and remains at the bottom of the reactor for easy collection. In addition, the hydrogen reduction reaction is highly efficient and the decomposition is more complete and thorough.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. The present invention uses hydrogen as the reducing gas instead of the carbon-based reduction in the traditional process. The hydrogen reduction used in the present invention only produces water vapor, without greenhouse gas emissions such as CO2, has a lower environmental impact, can achieve a rapid and thorough reduction process under high temperature conditions, and meets the current needs of green metallurgy and low-carbon economy.

[0033] 2. The present invention innovatively combines fluidization technology with hydrogen-based reduction to ensure uniformity and high efficiency of zinc-containing dust during the reduction reaction. At the same time, the reaction process is more controllable, ensuring efficient separation of zinc and iron.

[0034] 3. The zinc-containing dust treatment method proposed in the present invention does not require the traditional ball-making step, simplifies the process flow, reduces energy consumption, and improves the flexibility and economy of the process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 A process flow chart of a method for comprehensive utilization of fluidized hydrogen-based reduction of zinc-containing dust according to the present invention. DETAILED DESCRIPTION

[0036] In the embodiment of the present invention, the fluidized reaction device used is a suspension roasting furnace.

[0037] Example 1

[0038] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, the process flow chart of which is as follows: Figure 1 As shown, the specific steps include:

[0039] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 300 μm. It is then dried in an oven with the oven temperature set at 105°C for 36 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 15.41%, and the mass fraction of iron is 25.92%.

[0040] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, and the nitrogen flow rate is 10m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 900°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0041] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 10m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to 900°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 30 minutes, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron;

[0042] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 450°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 95.68% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0043] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0044] Example 2

[0045] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0046] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 50 μm. It is then dried in an oven with the oven temperature set at 105°C for 48 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 28.21%, and the mass fraction of iron is 41.57%.

[0047] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 1000°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0048] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 15m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to be 1000°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 25 minutes. The zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron.

[0049] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled at 500°C to condense the gaseous zinc into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc. Finally, zinc powder with a zinc content of 97.23% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0050] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0051] Example 3

[0052] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0053] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 150 μm. It is then dried in an oven with the oven temperature set at 102°C for 40 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 15.39%, and the mass fraction of iron is 32.46%.

[0054] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 1000°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0055] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 12m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to be 1000°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 30 minutes. The zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron.

[0056] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 450°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 97.36% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0057] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0058] Example 4

[0059] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0060] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 100 μm. It is then dried in an oven with the oven temperature set at 105°C for 36 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 14.63%, and the mass fraction of iron is 30.91%.

[0061] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 950°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0062] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 10m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to 950°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 25 minutes, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron;

[0063] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 500°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 98.31% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0064] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0065] Example 5

[0066] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0067] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 95 μm. It is then dried in an oven with the oven temperature set at 103°C for 40 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 13.28%, and the mass fraction of iron is 36.25%.

[0068] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 950°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0069] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 15m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to 950°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 25 minutes, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron;

[0070] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 450°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 96.42% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0071] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0072] Example 6

[0073] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0074] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 160 μm. It is then dried in an oven with the oven temperature set at 105°C for 36 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 15.16%, and the mass fraction of iron is 25.83%.

[0075] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 1000°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0076] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 14m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to be 1000°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 25 minutes. The zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron.

[0077] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 550°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 97.25% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0078] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0079] Example 7

[0080] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0081] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 150 μm. It is then dried in an oven with the oven temperature set at 100°C for 48 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 12.56%, and the mass fraction of iron is 26.31%.

[0082] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 20m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 950°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0083] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 15m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to 950°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 30 minutes, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron;

[0084] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 450°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 96.31% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0085] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

[0086] Example 8

[0087] A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, specifically comprising the following steps:

[0088] S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm to ensure the uniformity of the dust, and the average particle size is 400 μm. It is then dried in an oven with the oven temperature set at 105°C for 48 hours to remove moisture from the dust and control the moisture content in the dust to below 1% to obtain pretreated zinc-containing dust; wherein the mass fraction of zinc in the zinc-containing dust is 16.21%, and the mass fraction of iron is 40.42%.

[0089] S2. Preheating: nitrogen is introduced into the suspension roasting furnace for inert protection, with a nitrogen flow rate of 15m 3 / h to prevent oxidation during the subsequent heating process. Then add the pretreated zinc-containing dust and heat the temperature in the suspension roasting furnace to 1000°C. When the temperature in the suspension roasting furnace stabilizes, gradually introduce hydrogen and reduce the nitrogen flow rate.

[0090] S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches 12m 3 / h and stabilized, hydrogen fully contacts with dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to be 1000°C, and fluidized hydrogen-based reduction roasting is carried out. The reduction reaction time is 30 minutes. The zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron.

[0091] S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized reactor with the hydrogen flow and enters the condensation system with inert gas. The condensation temperature is controlled to 450°C, and the gaseous zinc is condensed into metallic zinc particles for collection and recovery. Air should be avoided during this condensation process to prevent secondary oxidation of zinc, and finally zinc powder with a zinc content of 97.31% is obtained. After the hydrogen-based reduction reaction, the iron oxide has been reduced to solid metallic iron and remains at the bottom of the reaction device. The iron particles are further purified through subsequent separation processes to achieve effective recycling of iron resources.

[0092] S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction. The reaction waste gas contains a small amount of unreacted hydrogen and volatile impurities. The unreacted hydrogen is recovered and recycled through the secondary hydrogen recovery device, thereby reducing resource waste. The volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

Claims

1. A method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction, characterized in that: The specific steps include: S1. Pretreatment: The collected zinc-containing dust is screened and crushed to ensure that the particle size of the treated zinc-containing dust is less than 1 mm, and then dried to control the moisture content in the dust to less than 1%, thereby obtaining the pretreated zinc-containing dust; S2. Preheating: nitrogen is introduced into the fluidized bed reactor for inert protection, and then the pretreated zinc-containing dust is added and heated. When the temperature in the reactor stabilizes at the target temperature, hydrogen is gradually introduced while reducing the nitrogen flow rate; S3. Fluidized hydrogen-based reduction roasting: When the hydrogen flow rate reaches the specified value and stabilizes, the hydrogen fully contacts the dust to form a fluidized suspension state, the hydrogen channel is kept open, the nitrogen channel is closed, and the timing is started. The temperature in the reaction device is controlled to perform fluidized hydrogen-based reduction roasting, and the zinc oxide in the dust is reduced to gaseous zinc, and the iron oxide is reduced to solid metallic iron; S4. Product recovery: After the gaseous zinc is formed, it is carried out of the fluidized bed reactor along with the hydrogen flow and enters a condensation system with an inert gas. The condensation temperature is controlled to condense the gaseous zinc into metallic zinc particles, which are collected and recovered. The solid metallic iron remains at the bottom of the fluidized bed reactor. S5. Tail gas treatment: The gas after fluidized hydrogen-based reduction roasting enters the tail gas treatment system, which is equipped with dust removal and impurity removal devices to purify the waste gas generated by the reaction and then recover it through a secondary hydrogen recovery device.

2. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In the step S1, the average particle size of the zinc-containing dust is between 25 μm and 500 μm, the mass fraction of zinc is between 10% and 30%, and the mass fraction of iron is between 20% and 60%.

3. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In the step S1, the drying temperature of the treated zinc-containing dust is 100° C. to 105° C., and the drying time is 36 h to 48 h.

4. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In the step S2, the fluidized reaction device is a suspension roasting furnace.

5. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S2, the nitrogen flow rate introduced into the fluidized reactor is 5m 3 / h~20m 3 / h, and the temperature in the reaction device is heated to 800℃~1000℃.

6. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S3, the hydrogen flow rate is 3m 3 / h~15m 3 / h, the temperature in the reaction device is 850℃~1000℃, and the reduction reaction time is 10min~30min.

7. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S3, the temperature in the reaction device is preferably 900°C to 950°C.

8. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S4, the condensation temperature in the condensation system is controlled to be 450° C. to 550° C., and air is prevented from entering the condensation process of the gaseous zinc.

9. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S4, the zinc content of the obtained metallic zinc particles is ≥95%, and the solid metallic iron is further purified through a separation process and then recycled.

10. The method for comprehensive utilization of zinc-containing dust by fluidized hydrogen-based reduction according to claim 1, characterized in that: In step S5, the unreacted hydrogen in the reaction waste gas is recovered and recycled, and the volatile impurities in the reaction waste gas are further treated and discharged after meeting environmental protection requirements.

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