Gas ash synergistic iron and zinc enrichment and separation method and system

Abstract

The invention discloses a gas ash synergistic iron-zinc enrichment and separation method which comprises the following steps: mixing gas ash and water to prepare slurry, collecting carbon through a flotation machine, collecting iron through a magnetic separator, and carrying out filter pressing to obtain wet gas mud; drying the wet gas sludge; mixing the dried gas mud, the original gas ash and a binder in proportion, granulating to form granules, and feeding the granules into a rotary kiln; the aggregates are incinerated in the rotary kiln, iron-rich slag is discharged from the tail of the rotary kiln to be formed, zinc oxide is reduced and gasified into zinc steam, and the zinc steam is attached to flue gas particles after being cooled to form zinc-containing flue gas; and after the zinc-containing flue gas is cooled by the multi-tube heat exchanger, zinc-rich ash is collected by the cyclone dust collector and the bag-type dust collector. According to the method, the extraction purity of iron and zinc is greatly improved, the interference of iron on zinc volatilization during high-temperature reduction is remarkably reduced, the nodulation problem is avoided from the source, meanwhile, flue gas waste heat is fully utilized, and the energy utilization efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metallurgical solid waste treatment, and in particular to a method and system for gas ash coordinated iron and zinc enrichment and separation. Background Art

[0002] Gas ash is a significant byproduct generated in large quantities during industrial production processes, such as steelmaking. Containing valuable elements such as iron, zinc, and carbon, gas ash has high recycling value. However, due to the intertwining of elements in gas ash and its complex physicochemical properties, the efficient separation and enrichment of iron, zinc, and carbon from gas ash presents a challenging technical challenge.

[0003] Patent publication number CN112708770A discloses a method for enriching iron, zinc, and carbon in gas ash. This method utilizes a dry process combined with a wind-classification and wind-magnetic separation device. Through a series of steps, including screening, baking, grinding, and pneumatic conveying, the method achieves separation and recovery of iron, zinc, and carbon from gas ash. While this technology achieves a certain degree of recovery of valuable elements in gas ash, several technical challenges remain that need to be addressed: First, the existing dry treatment process has limited separation accuracy for each element, making it difficult to obtain high-purity iron, zinc and carbon products; second, in the traditional pyrometallurgical zinc smelting process, due to the limited control conditions of the temperature field in the furnace, nodules are easily formed on the inner wall of the smelting equipment, seriously affecting the normal operation of the equipment, shortening the equipment service life, increasing equipment maintenance costs, and also reducing production efficiency; in addition, the existing gas ash treatment technology still has much room for improvement in energy utilization efficiency. The energy consumption in the production process is high, and waste emissions still occur. Summary of the Invention

[0004] The purpose of the present invention is to address the problems existing in the prior art and provide a method for the coordinated enrichment and separation of iron and zinc by gas ash, which greatly improves the extraction purity of iron and zinc; at the same time, it fully utilizes the waste heat in the flue gas and improves the energy utilization efficiency.

[0005] To achieve the above object, the technical solution adopted by the present invention is: A method for the coordinated enrichment and separation of gas ash and iron and zinc comprises the following steps: S1. Mixing gas ash and water in a pulper to prepare a pulp, sequentially passing through a flotation machine to collect and separate carbon, a magnetic separator to collect and separate iron, and then filtering through a filter press to obtain wet gas mud; S2, drying the wet gas mud through a drying tower; S3, the dried gas mud, original gas ash and binder are put into a homogenizer in proportion for mixing, the mixed material is granulated into pellets by a granulator, and is sent to the rotary kiln through a conveying device; S4. The pellets are burned in a rotary kiln, and the iron-rich slag is discharged from the kiln tail to form slag blocks. The zinc oxide is reduced and gasified to form zinc vapor. The zinc vapor cools and adheres to the flue gas particles to form zinc-containing flue gas. S5. After the zinc-containing flue gas is cooled by the multi-tube heat exchanger, the zinc-rich ash is collected by the first cyclone dust collector and the first bag dust collector.

[0006] Step S1 specifically includes: S1.1. Set the liquid-to-solid ratio of gas ash and water to 1:4-1:7 and stir in a pulping machine for 20-40 minutes; S1.2, the flotation machine mixes the pulp and gas and collects them in layers. The flotation time is 15-30 minutes, and the flotation concentrate with a carbon content of ≥85% is collected; S1.3. Feed the gas slurry after flotation into a magnetic separator, control the magnetic field strength to 0.8-1.2T, and the magnetic separation linear speed to 0.8-1.2m / s, to obtain magnetically separated refined iron with an iron grade of ≥55%; S1.4. Filter the gas slurry after magnetic separation through a filter press to a moisture content of 40-50% to form wet gas slurry; S1.5. The filter press wastewater is transported back to the pulping machine for water replenishment.

[0007] Step S2 specifically includes: S2.1. Send the wet gas mud into the drying tower; S2.2, the zinc-containing flue gas will be processed by the first cyclone dust collector and the first bag dust collector and then transported to the drying tower as a drying heat source; S2.3, the dry exhaust gas is purified and dusted by the second cyclone dust collector and the second bag dust collector before being discharged, and the collected dust is returned to the mixing process in step S3; S2.4. Control the drying temperature of the drying tower to 180-220℃ and the residence time to 20-40 minutes, so that the moisture content of the gas mud after drying is below 8%.

[0008] Step S3 specifically includes: S3.1. By mass percentage, add 50-70% dry gas mud, 20-40% original gas ash and 5-10% binder into a homogenizer; The binder is bentonite or composite organic binder, and the addition amount is 3-8% of the total material mass; S3.3, when mixing, control the mixer speed to 15-25r / min and the mixing time to 10-20 minutes; S3.4. The mixed material is pressed into pellets with a diameter of 10-30 mm by a roller forming machine; S3.5. After being sorted by the vibration screen, the qualified pellets are sent to the rotary kiln via a high-temperature resistant conveyor belt.

[0009] Step S4 specifically includes: S4.1. Control the rotary kiln incineration temperature to 950-1050°C and the material residence time to 40-60 minutes; S4.2. Install a nitrogen quenching pipe at the kiln head, extending 5-8 meters into the kiln. Zinc vapor is rapidly cooled by nitrogen here, dropping its temperature from 900-1000°C to below 350°C, transforming from a gaseous state to a solid state. The solid state adheres to the flue gas particles, forming zinc-containing flue gas. S4.3. When the iron-rich slag is discharged from the kiln tail, the temperature is controlled at 600-700℃. After being formed into slag blocks by a hydraulic briquetting machine, it is cooled to below 80℃ by a water-cooled roller and then discharged.

[0010] The other end of the nitrogen quenching pipe is connected to two branch pipes, one of which is connected to the output end of the blower, and the input end of the blower is connected to the multi-tube heat exchanger; the other branch pipe is connected to the nitrogen gas source.

[0011] Step S5 specifically includes: S5.1. Pass the zinc-containing flue gas into a multi-tube heat exchanger and control the flue gas temperature to be gradually cooled from 200-300°C to 120-150°C; S5.2. After cooling, the flue gas enters the first cyclone dust collector to collect the coarse zinc-rich ash. The flue gas after cyclone dust collection enters the first bag dust collector to collect the fine zinc-rich ash. S5.4. Transport the zinc ash collected by the first cyclone dust collector and the first bag dust collector to the ash silo for storage; S5.5. The purified flue gas is transported into the drying tower as a drying heat source.

[0012] Furthermore, the drying tower comprises: The tower body has a feed port at its upper end and a discharge port at its lower end. Several horizontal conveyor belts are arranged in sequence from top to bottom inside the tower body, and two adjacent conveyor belts form a transmission relationship; A flue gas main pipe is provided on the outside of the tower body, one end of the flue gas main pipe is connected to the exhaust pipe of the first bag filter, and the other end is connected to a plurality of flue gas branch pipes, the plurality of flue gas branch pipes are all extended into the tower body, and are respectively provided between two upper and lower adjacent conveyor belts; The tower body is provided with a flue gas outlet for connecting to the second cyclone dust collector and the second bag dust collector.

[0013] Furthermore, the drying tower is a hollow paddle dryer, and steam is introduced into the hollow paddle dryer to form dry gas mud, condensed water and steam volatiles, and then the steam volatiles are introduced into a condenser to form condensed wastewater.

[0014] A gas ash coordinated iron and zinc enrichment and separation system, comprising: Pulping machine, flotation machine, magnetic separator, filter press, drying tower, mixer, granulator, rotary kiln, briquetting machine, first cyclone dust collector and first bag dust collector; The pulping machine is used to mix gas ash with water to make pulp, the flotation machine is used to collect and separate carbon in the gas slurry, the magnetic separator is used to collect and separate iron in the gas slurry, and the filter press is used to filter the gas slurry to obtain wet gas slurry; The drying tower is used to thoroughly dry the wet gas mud to form dry gas mud. The mixer is used to mix the dry gas mud, original gas ash and binder in proportion. The granulator is used to granulate the mixed material into granules. The rotary kiln is used to burn pellets, with iron-rich slag blocks discharged from the kiln tail and zinc-containing flue gas discharged from the kiln head; The first cyclone dust collector and the first bag dust collector are used to purify zinc-containing flue gas and collect zinc-rich ash.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. A pretreatment process combining wet flotation and magnetic separation is used. By mixing gas ash with water to make pulp, flotation machines are used to collect and separate carbon, and magnetic separators are used to collect and separate iron. This effectively recovers carbon and iron-rich resources from the gas ash, reducing subsequent energy consumption. At the same time, the refined carbon obtained through flotation and the refined iron obtained through magnetic separation greatly improve the purity and quality of the products, providing high-quality raw materials for subsequent resource utilization. 2. After pretreatment, the dried gas mud, raw gas ash, and binder are mixed in a specific ratio and granulated into pellets in a granulator. This granulation process precisely controls the material form, ensuring a more even distribution of the material within the rotary kiln and a more complete reaction. Combined with high-temperature incineration in the rotary kiln, it achieves selective reduction and gasification of zinc. By rationally controlling the rotary kiln incineration temperature and material residence time, and installing a nitrogen quenching tube at the kiln head, the zinc vapor is rapidly cooled by nitrogen, dropping its temperature from 900-1000°C to below 350°C. The zinc vapor rapidly transforms from a gaseous state to a solid state, attaching to the flue gas particles to form zinc-containing flue gas. This combination of granulation and high-temperature reduction significantly improves zinc recovery efficiency. 3. By installing a nitrogen quenching pipe at the kiln head, zinc vapor is rapidly solidified in a very short time, greatly reducing the probability of zinc vapor adhering to the inner wall of the rotary kiln and effectively preventing zinc nodules on the inner wall of the rotary kiln, extending the service life of the equipment and reducing equipment maintenance costs. At the same time, combined with multi-stage dust removal, the zinc recovery rate is further improved, ensuring the maximum recovery of zinc resources. 4. The purified flue gas is transported into the drying tower as a heat source for drying wet gas mud, which makes full use of the waste heat in the flue gas, reduces the consumption of external energy, reduces production costs, and improves energy utilization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 The present invention provides a flow chart of a method for the coordinated enrichment and separation of gas ash and iron and zinc. DETAILED DESCRIPTION

[0018] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0019] The size of the serial numbers of each step in the description of this application does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0020] In the description of this application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish descriptions and should not be understood as indicating or implying relative importance. It should also be understood that although the terms "first", "second", etc. are used in the text to describe various elements in some embodiments of the present application, these elements should not be limited by these terms. These terms are only used to distinguish one element from another. For example, a first table can be named a second table, and similarly, a second table can be named a first table without departing from the scope of the various described embodiments. Both the first table and the second table are tables, but they are not the same table.

[0021] References to "one embodiment" or "some embodiments" in this specification mean that a particular feature, structure, or characteristic described in conjunction with that embodiment is included in one or more embodiments of the present application. Thus, phrases such as "in one embodiment," "in some embodiments," "in other embodiments," and "in other embodiments" appearing in various places in this specification do not necessarily refer to the same embodiment, but rather mean "one or more but not all embodiments," unless otherwise specifically emphasized. The terms "including," "comprising," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0022] Patent publication number CN112708770A discloses a method for enriching iron, zinc, and carbon in gas ash. This method utilizes a dry process combined with a wind-classification and wind-magnetic separation device. Through a series of steps, including screening, baking, grinding, and pneumatic conveying, the method achieves separation and recovery of iron, zinc, and carbon from gas ash. While this technology achieves a certain degree of recovery of valuable elements in gas ash, several technical challenges remain that need to be addressed: First, the existing dry treatment process has limited separation accuracy for each element, making it difficult to obtain high-purity iron, zinc and carbon products; second, in the traditional pyrometallurgical zinc smelting process, due to the limited control conditions of the temperature field in the furnace, nodules are easily formed on the inner wall of the smelting equipment, seriously affecting the normal operation of the equipment, shortening the equipment service life, increasing equipment maintenance costs, and also reducing production efficiency; in addition, the existing gas ash treatment technology still has much room for improvement in energy utilization efficiency. The energy consumption in the production process is high, and waste emissions still occur.

[0023] In response to the above technical problems, the present invention provides a method for the coordinated enrichment and separation of gas ash and iron and zinc, comprising the following steps S1-S5: S1. Mix gas ash and water in a pulping machine to make pulp, then pass through a flotation machine to collect and separate carbon, a magnetic separator to collect and separate iron, and then filter through a filter press to obtain wet gas mud.

[0024] In some embodiments, step S1 specifically includes: S1.1. Set the liquid-to-solid ratio of the gas ash and water mixture to 1:4-1:7, and stir the mixture in a pulping machine for 20-40 minutes to ensure that the slurry is evenly dispersed.

[0025] S1.2. The flotation machine mixes the pulp and gas and collects them in layers. The flotation time is 15-30 minutes, and the flotation concentrate with a carbon content of ≥85% is collected.

[0026] Specifically, when a flotation machine is operating, as the impeller rotates, the slurry in the tank is drawn from all sides through the bottom of the tank and into the space between the impeller blades. Simultaneously, low-pressure air supplied by a blower enters the tank through the hollow shaft and the air distributor in the impeller cavity. The force of bubbles in the slurry separates useful minerals from waste rock. Specifically, the flotation machine mixes the slurry with a gas—air or other gases such as oxygen or nitrogen. When the ore particles in the slurry come into contact with the bubbles, the surface tension of the bubbles causes them to form a thin film within the slurry, where they react with the mineral particles. Bubbles adsorbed on the mineral surface combine with the mineral particles to form bubble-mineral particle aggregates. These aggregates rise to the surface of the slurry with the bubbles, forming bubbles. Due to the higher density of the mineral particles, they sink to the bottom of the bubbles. The lower density of the bubble-mineral particle aggregates forms a scum on the surface of the bubbles, which can be separated mechanically or by gravity.

[0027] S1.3. Send the gas slurry after flotation into the magnetic separator, control the magnetic field strength to 0.8-1.2T, and the magnetic separation linear speed to 0.8-1.2m / s, to obtain magnetically separated refined iron with an iron grade of ≥55%.

[0028] S1.4. The gas slurry after magnetic separation is filtered through a filter press to a moisture content of 40-50% to form wet gas slurry, which is convenient for subsequent drying and avoids energy waste caused by excessive dehydration.

[0029] S1.5. The filter press wastewater is transported back to the pulping machine for water replenishment.

[0030] Through the synergistic effects of flotation and magnetic separation in the above steps, carbon recovery purity ≥85% and iron recovery grade ≥55% are achieved, significantly outperforming traditional dry processes and providing a low-interference raw material base for efficient subsequent zinc extraction. Pre-recovery of the majority of the iron and carbon effectively reduces the inhibitory effect of iron on zinc volatilization during the high-temperature reduction stage. This also prevents buildup of equipment walls caused by iron-zinc eutectic melting, extending equipment life. Filter press wastewater is reused in pulping, reducing fresh water consumption and minimizing environmental pollution.

[0031] S2. Dry the wet gas mud through a drying tower.

[0032] In some embodiments, step S2 specifically includes: S2.1. Send wet gas mud with a moisture content of 25-35% into the drying tower; S2.2: Zinc-containing flue gas is treated in the first cyclone and bag filters before being transported to the drying tower, where it serves as a drying heat source. After purification in the first cyclone and bag filters, the majority of particulate matter is removed. Residual heat in the purified flue gas is evenly released through flue gas branches distributed throughout the tower, where it comes into countercurrent contact with the wet gas sludge, achieving heat transfer and water evaporation.

[0033] The drying tower utilizes a multi-layer conveyor belt structure, transporting wet gas mud layer by layer from top to bottom, ensuring full contact with the hot flue gas. The drying temperature is controlled at 180-220°C, with a residence time of 20-40 minutes. This not only effectively evaporates moisture but also prevents premature oxidation or volatilization of residual metals such as zinc and iron in the gas mud.

[0034] S2.3: The dried tail gas is purified and dusted by the second cyclone dust collector and the second bag dust collector before being discharged. The collected dust is returned to the mixing process in step S3, achieving closed-loop material utilization.

[0035] S2.4. Control the drying temperature of the drying tower to 180-220℃ and the residence time to 20-40 minutes, so that the moisture content of the gas mud after drying is below 8% to meet the material requirements of the subsequent granulation process.

[0036] Through these steps, the waste heat from purified flue gas is used as a drying heat source, replacing traditional external energy sources. This allows for efficient waste heat utilization and reduces carbon emissions. The multi-layer conveyor belt's countercurrent contact with the hot flue gas extends heat exchange time and ensures uniform drying of the gas sludge. The drying exhaust undergoes two-stage dust removal and purification, with the recovered dust directly reused in the granulation process, minimizing raw material loss and achieving resource recycling.

[0037] S3. Mix the dried gas mud, original gas ash and binder in proportion, granulate the mixture into pellets through a granulator, and send it into the rotary kiln through a conveying equipment.

[0038] In some embodiments, step S3 specifically includes: S3.1. By mass percentage, put 50-70% dry gas mud, 20-40% original gas ash and 5-10% binder into the homogenizer.

[0039] The binder is bentonite or composite organic binder, and the addition amount is 3-8% of the total material mass.

[0040] S3.3. During mixing, control the mixer speed to 15-25r / min and the mixing time to 10-20 minutes.

[0041] S3.4. The mixed material is pressed into pellets with a diameter of 10-30 mm by a double-roll forming machine.

[0042] S3.5. After being sorted by the vibration screen, the qualified pellets are sent to the rotary kiln via a high-temperature resistant conveyor belt.

[0043] Through the above steps, the mixed material is prepared into pellets, which can accurately control the material morphology. The pellets can take into account both heat conduction efficiency and zinc vapor escape, shorten the reduction reaction time, and improve the zinc recovery rate.

[0044] S4. The pellets are burned in the rotary kiln, and the iron-rich slag is discharged from the kiln tail to form slag blocks. The zinc oxide is reduced and gasified to form zinc vapor. The zinc vapor cools and adheres to the flue gas particles to form zinc-containing flue gas.

[0045] In some embodiments, step S4 specifically includes: S4.1. Control the rotary kiln incineration temperature to 950-1050℃ and the material residence time to 40-60 minutes.

[0046] The reaction formula is 2ZnO+C→2Zn↑+C 、ZnO+CO→Zn↑+C The rotary kiln can not only ensure that zinc oxide is fully reduced to zinc vapor, but also prevent the iron slag from being excessively melted and adhering to the kiln wall, thus ensuring the complete gasification of zinc and the full enrichment of iron slag.

[0047] S4.2. A nitrogen quenching pipe is installed at the kiln head of the rotary kiln, extending 5-8 meters into the kiln. After the zinc vapor is quenched by nitrogen here, its temperature drops sharply from 900-1000℃ to below 350℃, and it transforms from gaseous state to solid state, attaching to the flue gas particles to form zinc-containing flue gas.

[0048] S4.3. When the iron-rich slag is discharged from the kiln tail, the temperature is controlled at 600-700℃. After being formed into slag blocks by a hydraulic briquetting machine, it is cooled to 80℃ by a water-cooled roller and then discharged.

[0049] In some embodiments, the other end of the nitrogen quenching tube is connected to two branch pipes, one of which is connected to the output end of the blower, and the input end of the blower is connected to the multi-tube heat exchanger; the other branch pipe is connected to the nitrogen gas source.

[0050] Specifically, a blower draws air through a multi-tube heat exchanger and mixes it with nitrogen to form a quenching medium. At the outlet of the quenching tube, the zinc vapor comes into contact with the low-temperature medium, causing its temperature to drop sharply to below 350°C. The zinc vapor rapidly solidifies and adsorbs onto the surface of flue gas particles, forming zinc-containing flue gas. The optimized design, with an insertion depth of 5-8 meters, ensures that the quenching occurs at a critical section of the zinc vapor escape path, minimizing zinc adhesion to the kiln walls.

[0051] S5. After the zinc-containing flue gas is cooled by the multi-tube heat exchanger, the zinc-rich ash is collected by the first cyclone dust collector and the first bag dust collector.

[0052] In some embodiments, step S5 specifically includes: S5.1. Pass the zinc-containing flue gas into a multi-tube heat exchanger and control the flue gas temperature to be gradually cooled from 500-600°C to 120-150°C.

[0053] S5.2. After cooling, the flue gas enters the first cyclone dust collector to collect coarse zinc-rich ash; the flue gas after cyclone dust collection enters the first bag dust collector to collect fine zinc-rich ash.

[0054] S5.4. Transport the zinc ash collected by the first cyclone dust collector and the first bag dust collector to the ash silo for storage.

[0055] S5.5. The purified flue gas is transported into the drying tower as a drying heat source.

[0056] The zinc-containing flue gas first enters the multi-tube heat exchanger and exchanges heat with the external cooling medium air through the heat exchange tubes. The flue gas temperature gradient drops to 120-150°C to avoid particle agglomeration of zinc ash due to rapid cooling. Part of the waste heat is transported to the nitrogen quenching tube in step S4 through the blower, forming a heat energy recycling.

[0057] The cooled flue gas enters the first cyclone and the first bag filter, sequentially. The first cyclone separates coarse zinc-rich ash using centrifugal force. The remaining flue gas enters the first bag filter, where the filter bags capture fine zinc-rich ash. The two-stage dust removal system works synergistically to ensure a total zinc ash recovery rate of ≥99.8%. The collected zinc ash is then transported to an ash silo for storage via a closed conveying system to prevent degradation of the zinc ash quality.

[0058] In some embodiments, the drying tower comprises: The tower body has a feed port at its upper end and a discharge port at its lower end. Several horizontal conveyor belts are arranged in sequence from top to bottom inside the tower body, and two adjacent conveyor belts form a transmission relationship; A flue gas main pipe is provided on the outside of the tower body, one end of the flue gas main pipe is connected to the exhaust pipe of the first bag dust collector, and the other end is connected to several flue gas branch pipes. Several of the flue gas branch pipes extend into the tower body and are respectively arranged between the two adjacent conveyor belts above and below; the tower body is provided with a flue gas outlet for connecting to the second cyclone dust collector and the second bag dust collector.

[0059] In summary, the advantages of this application are: The pretreatment process combines wet flotation with magnetic separation. By mixing gas ash with water to make pulp, flotation machines are used to collect and separate carbon, and magnetic separators are used to collect and separate iron. This effectively removes carbon and some iron from the gas ash, significantly reducing the interference of iron on zinc volatilization during the subsequent high-temperature reduction process, and avoiding the problem of nodules at the source. At the same time, the refined carbon obtained by flotation and the refined iron obtained by magnetic separation greatly improve the purity and quality of the products, providing high-quality raw materials for subsequent resource utilization. After pretreatment, the dried gas mud, raw gas ash, and binder are mixed in a specific ratio and granulated into pellets in a granulator. The granulation process can precisely control the material form, ensuring a more even distribution of the material in the rotary kiln and a more complete reaction. Combined with the high-temperature incineration in the rotary kiln, it achieves selective reduction and gasification of zinc. By rationally controlling the rotary kiln incineration temperature and material residence time, and installing a nitrogen quenching tube at the kiln head, the zinc vapor is rapidly cooled by nitrogen, dropping its temperature from 900-1000°C to below 350°C. It quickly transforms from a gaseous state to a solid state and adheres to the flue gas particles to form zinc-containing flue gas. This combination of granulation and high-temperature reduction significantly improves zinc recovery efficiency. By installing a nitrogen quenching tube at the kiln head, zinc vapor solidifies quickly in a very short time, greatly reducing the probability of zinc vapor adhering to the inner wall of the rotary kiln and effectively preventing zinc nodules on the inner wall of the rotary kiln, extending the service life of the equipment and reducing equipment maintenance costs. At the same time, combined with multi-stage dust removal, the zinc recovery rate is further improved, ensuring the maximum recovery of zinc resources. The purified flue gas is transported into the drying tower as a heat source for drying wet gas mud, which makes full use of the waste heat in the flue gas, reduces the consumption of external energy, reduces production costs, and improves energy utilization efficiency.

[0060] In some embodiments, the drying tower is a hollow paddle dryer, and steam is introduced into the hollow paddle dryer to form dry gas mud, condensed water and steam volatiles, and then the steam volatiles are introduced into a condenser to form condensed wastewater.

[0061] Another aspect of the present application provides a gas ash coordinated iron and zinc enrichment and separation system, comprising: Pulping machine, flotation machine, magnetic separator, filter press, drying tower, mixer, granulator, rotary kiln, briquetting machine, first cyclone dust collector and first bag dust collector; The pulping machine is used to mix gas ash with water to make pulp, the flotation machine is used to collect and separate carbon in the gas slurry, the magnetic separator is used to collect and separate iron in the gas slurry, and the filter press is used to filter the gas slurry to obtain wet gas slurry; The drying tower is used to completely dry the wet gas mud to form dry gas mud. The mixer is used to put the dry gas mud, original gas ash and binder into the homomixer in proportion for mixing. The granulator is used to granulate the mixed material into granules. The rotary kiln is used to burn pellets, with iron-rich slag blocks discharged from the kiln tail and zinc-containing flue gas discharged from the kiln head; The first cyclone dust collector and the first bag dust collector are used to purify zinc-containing flue gas and collect zinc-rich ash.

[0062] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A method for the coordinated enrichment and separation of gas ash and iron and zinc, characterized in that: The following steps are involved: S1. Mixing gas ash and water in a pulper to prepare a pulp, sequentially passing through a flotation machine to collect and separate carbon, a magnetic separator to collect and separate iron, and then filtering through a filter press to obtain wet gas mud; S2, drying the wet gas mud through a drying tower; S3, the dried gas mud, original gas ash and binder are put into a homogenizer in proportion for mixing, the mixed material is granulated into pellets by a granulator, and is sent to the rotary kiln through a conveying device; S4. The pellets are burned in a rotary kiln, and the iron-rich slag is discharged from the kiln tail to form slag blocks. The zinc oxide is reduced and gasified to form zinc vapor. The zinc vapor cools and adheres to the flue gas particles to form zinc-containing flue gas. S5. After the zinc-containing flue gas is cooled by a multi-tube heat exchanger, the zinc-rich ash is collected by a dust collector.

2. The method for coalescing iron and zinc from gas ash according to claim 1, characterized in that: Step S1 specifically includes: S1.

1. Set the liquid-to-solid ratio of gas ash and water to 1:4-1:7 and stir in a pulping machine for 20-40 minutes; S1.2, the flotation machine mixes the pulp and gas and collects them in layers. The flotation time is 15-30 minutes, and the flotation concentrate with a carbon content of ≥85% is collected; S1.

3. Feed the gas slurry after flotation into a magnetic separator, control the magnetic field strength to 0.8-1.2T, and the magnetic separation linear speed to 0.8-1.2m / s, to obtain magnetically separated refined iron with an iron grade of ≥55%; S1.

4. Filter the gas slurry after magnetic separation through a filter press to a moisture content of 40-50% to form wet gas slurry; S1.

5. The filter press wastewater is transported back to the pulping machine for water replenishment.

3. The method for coalescing iron and zinc from gas ash according to claim 1, characterized in that: Step S2 specifically includes: S2.

1. Send the wet gas mud into the drying tower; S2.2, the zinc-containing flue gas will be processed by the first cyclone dust collector and the first bag dust collector and then transported to the drying tower as a drying heat source; S2.3, the dry exhaust gas is purified and dusted by the second cyclone dust collector and the second bag dust collector before being discharged, and the collected dust is returned to the mixing process in step S3; S2.

4. Control the drying temperature of the drying tower to 180-220℃ and the residence time to 20-40 minutes, so that the moisture content of the gas mud after drying is below 8%.

4. The method for coalescing iron and zinc from gas ash according to claim 1, characterized in that: Step S3 specifically includes: S3.

1. By mass percentage, add 50-70% dry gas mud, 20-40% original gas ash and 5-10% binder into a homogenizer; S3.3, when mixing, control the mixer speed to 15-25r / min and the mixing time to 10-20 minutes; S3.

4. The mixed material is pressed into pellets with a diameter of 10-30 mm by a roller forming machine; S3.

5. After being sorted by the vibration screen, the qualified pellets are sent to the rotary kiln via a high-temperature resistant conveyor belt.

5. The method for coalescing iron and zinc from gas ash according to claim 1, characterized in that: Step S4 specifically includes: S4.

1. Control the rotary kiln incineration temperature to 950-1050°C and the material residence time to 40-60 minutes; S4.

2. Install a nitrogen quenching pipe at the kiln head, extending 5-8 meters into the kiln. Zinc vapor is rapidly cooled by nitrogen here, dropping its temperature from 900-1000°C to below 350°C, transforming from a gaseous state to a solid state. The solid state adheres to the flue gas particles, forming zinc-containing flue gas. S4.

3. When the iron-rich slag is discharged from the kiln tail, the temperature is controlled at 600-700℃. After being formed into slag blocks by a hydraulic briquetting machine, it is cooled to below 80℃ by a water-cooled roller and then discharged.

6. The method for coalescing iron and zinc from gas ash according to claim 5, characterized in that: The other end of the nitrogen quenching pipe is connected to two branch pipes, one of which is connected to the output end of the blower, and the input end of the blower is connected to the multi-tube heat exchanger; the other branch pipe is connected to the nitrogen gas source.

7. The method for coalescing iron and zinc from gas ash according to claim 1, characterized in that: Step S5 specifically includes: S5.

1. Pass the zinc-containing flue gas into a multi-tube heat exchanger and control the flue gas temperature to be gradually cooled from 200-300°C to 120-150°C; S5.

2. After cooling, the flue gas enters the first cyclone dust collector to collect the coarse zinc-rich ash. The flue gas after cyclone dust collection enters the first bag dust collector to collect the fine zinc-rich ash. S5.

4. Transport the zinc ash collected by the first cyclone dust collector and the first bag dust collector to the ash silo for storage; S5.

5. The purified flue gas is transported into the drying tower as a drying heat source.

8. The method for coalescing iron and zinc enrichment and separation of gas ash according to claim 1, characterized in that: The drying tower is a flue gas drying tower, comprising: a tower body, wherein the upper end of the tower body is provided with a feed port, the lower end is provided with a discharge port, and the interior of the tower body is provided with a plurality of horizontal conveyor belts from top to bottom, and the upper and lower adjacent conveyor belts form a transmission relationship; A flue gas main pipe is provided on the outside of the tower body, one end of the flue gas main pipe is connected to the exhaust pipe of the first bag filter, and the other end is connected to a plurality of flue gas branch pipes, the plurality of flue gas branch pipes are all extended into the tower body, and are respectively provided between two upper and lower adjacent conveyor belts; The tower body is provided with a flue gas outlet for connecting to the second cyclone dust collector and the second bag dust collector.

9. The method for coalescing iron and zinc enrichment and separation of gas ash according to claim 1, characterized in that: The drying tower is a hollow blade dryer. Steam is introduced into the hollow blade dryer to form dry gas mud, condensed water and steam volatiles, and the steam volatiles are then introduced into a condenser to form condensed wastewater.

10. A gas ash coordinated iron and zinc enrichment and separation system, characterized in that: include: Pulping machine, flotation machine, magnetic separator, filter press, drying tower, mixer, granulator, rotary kiln, briquetting machine, dust collector; The pulping machine is used to mix gas ash with water to make pulp, the flotation machine is used to collect and separate carbon in the gas slurry, the magnetic separator is used to collect and separate iron in the gas slurry, and the filter press is used to filter the gas slurry to obtain wet gas slurry; The drying tower is used to thoroughly dry the wet gas mud to form dry gas mud. The mixer is used to mix the dry gas mud, original gas ash and binder in proportion. The granulator is used to granulate the mixed material into granules. The rotary kiln is used to burn pellets, with iron-rich slag blocks discharged from the kiln tail and zinc-containing flue gas discharged from the kiln head; The dust collector is used to purify zinc-containing flue gas and collect zinc-rich ash.

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