Process for extracting metallic aluminum from aluminum ash with high purity and high recovery rate

Abstract

The invention provides a process for extracting metallic aluminum from aluminum ash with high purity and high recovery rate, which comprises the following steps: S1, putting the aluminum ash into a raw material bin, S2, conveying the aluminum ash in the raw material bin to a jaw crusher for crushing until the particle size is less than 20mm; s3, the crushed aluminum ash is subjected to crushing and fine grinding through a ball mill and then transferred to a rotary screen to be screened, and oversize coarse aluminum sheets are obtained; s4, the coarse aluminum sheet is conveyed into an iron remover, and iron substances attached to the coarse aluminum sheet are removed; s5, the coarse aluminum sheet is weighed and then transferred into an aluminum melting furnace to be heated to be in a molten state, and metal aluminum liquid is formed; s6, molten metal aluminum is injected into an ingot mold of the linear ingot casting machine through the cast aluminum chute, and the molten metal aluminum is cooled in the ingot mold and then demolded to form an aluminum ingot; wherein in the steps from S1 to S6, the dust removal step is synchronously carried out, the dust removal system is used for collecting generated dust and waste gas, metal aluminum in the dust is recycled, and the effect of improving the recycling purity and the recycling rate of the metal aluminum is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of aluminum ash slag treatment processes, and particularly relates to a process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag. Background Art

[0002] With the improvement of aluminum industry technology, the resulting environmental pressure cannot be underestimated. Aluminum ash slag generated during aluminum processing has been included in the "National List of Hazardous Wastes". Among them, aluminum ash slag with a relatively high metallic aluminum content can reach 20% - 80%, and can be used as one of the raw materials for the secondary aluminum industry. Currently, there are many processes for recycling metallic aluminum from aluminum ash slag, and the most commonly used method is the salt bath process with the addition of double salts, including ash frying method, rotary kiln method, tilting rotary furnace method, etc.

[0003] Regarding the above related technologies, although the salt bath process extracts a large amount of valuable metallic aluminum from aluminum ash, due to the addition of salt fluxes, the purity of the recycled metallic aluminum is low, and the residue (secondary aluminum ash) contains a large amount of soluble salts, greatly increasing the difficulty of subsequent treatment; at the same time, a large amount of soot generated during the treatment process makes the production environment harsh, and there are defects such as low purity and low recovery rate in the recycling and extraction of metallic aluminum. Summary of the Invention

[0004] The purpose of the present invention is to provide a process for extracting metallic aluminum from aluminum ash slag with high purity and high recovery rate to solve the problems of low purity and low recovery rate in the recycling and extraction of metallic aluminum.

[0005] To achieve the above purpose, a process for extracting metallic aluminum from aluminum ash slag with high purity and high recovery rate of the present invention adopts the following technical solutions:

[0006] A process for extracting metallic aluminum from aluminum ash slag with high purity and high recovery rate includes the following steps:

[0007] S1. Feed the aluminum ash slag into the raw material bin.

[0008] S2. Convey the aluminum ash slag in the raw material bin to a jaw crusher through a vibrating feeder for crushing, and crush the aluminum ash slag to a particle size less than 20 mm.

[0009] S3. After the crushed aluminum ash slag is pulverized and finely ground by a ball mill, transfer it to a drum screen for screening to obtain oversize coarse aluminum flakes.

[0010] S4. Convey the coarse aluminum flakes to a magnetic separator, and use the magnetic separator to remove the iron substances attached to the coarse aluminum flakes.

[0011] S5. After weighing the coarse aluminum flakes with the iron substances removed, transfer them to a melting furnace for heating. Heat the coarse aluminum flakes to a molten state to form molten aluminum liquid.

[0012] S6. Pour the molten aluminum into the ingot mold of the straight ingot casting machine through the aluminum casting chute. After the molten aluminum cools in the ingot mold, it is demolded to form aluminum ingots.

[0013] Among them, in the steps of S1 - S6, a dust removal step is also carried out synchronously, including: collecting the generated dust and waste gas through a dust removal system and recovering the metallic aluminum in the dust.

[0014] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S1, a triangular cone bag breaker is provided at the top of the raw material bin for puncturing the aluminum ash slag packaging bags.

[0015] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S3, the ball mill is a double - chamber ball mill. The first chamber uses steel balls for grinding, and the second chamber uses steel segments for grinding. The particle size of the fine - ground aluminum ash slag is less than 0.15 mm.

[0016] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S3, the drum sieve uses a double - layer screen. The first - layer screen is 12 mesh, and the second - layer screen is 80 mesh. The aluminum ash slag obtains the material in the sieve through only the first - layer screen of the drum sieve, and the material in the sieve is returned to the ball mill for secondary ball milling. The aluminum ash slag obtains the material under the sieve through the double - layer screen of the drum sieve, and the material under the sieve is fine aluminum ash, which is transported to the storage bin for recovery.

[0017] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S5, the melting furnace for aluminum is a tiltable gas - crucible holding furnace, which is heated to 700 °C using natural gas.

[0018] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, step S5 also includes cooling the dross generated during the melting of the coarse aluminum sheets and transporting it to the raw material bin.

[0019] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S6, electric heating wires are provided in the aluminum casting chute to keep the molten aluminum in a molten state.

[0020] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S6, the operating speed of the straight ingot casting machine is controlled by a frequency converter, and the operating speed of the straight ingot casting machine is adjusted synchronously with the aluminum casting speed.

[0021] As an optimization of the process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, in step S6, a burner is provided at the front end of the ingot mold of the straight ingot casting machine for drying the moisture in the ingot mold; a ingot receiving table is provided at the tail end of the ingot mold of the straight ingot casting machine for receiving the demolded aluminum ingots.

[0022] As an optimization of the process for extracting high-purity and high-recovery metallic aluminum from aluminum ash slag, in the dust removal step, the dust removal system includes a normal-temperature bag filter and a high-temperature bag filter. The normal-temperature bag filter is used to recover the aluminum ash generated from the raw material bin and the conveyor belt, and the high-temperature bag filter is used to recover the aluminum ash generated from the aluminum melting furnace.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] (1) By combining cold treatment screening and heat treatment melting, the metallic aluminum and other impurities in the aluminum ash slag are effectively separated, the purity of the aluminum ingot is significantly improved, and the recovery rate of metallic aluminum can reach more than 80%.

[0025] (2) By adopting the grading screening and secondary ball milling technologies, the undersize aluminum ash (containing about 5% aluminum) is temporarily stored and then processed for the second time to maximize the recovery of metallic aluminum and reduce resource waste.

[0026] (3) By separately treating the crushed and screened dust and the molten waste gas through the normal-temperature and high-temperature bag dust removal systems, the dust emission concentration is lower than the national standard, the production environment is improved, and the risk of secondary pollution is reduced.

[0027] (4) By using equipment such as vibrating feeders and palletizing robots to achieve continuous production, manual intervention is reduced, the processing efficiency is improved, and the energy consumption and production costs are reduced.

[0028] (5) A burner is arranged at the front end of the ingot casting machine to dry the moisture in the ingot mold, avoiding splashing accidents caused by the contact of molten aluminum with moisture and ensuring operation safety. Description of the Drawings [[ID=2l]]

[0029] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0030] Figure 1 It is a schematic diagram of the process method for extracting high-purity and high-recovery metallic aluminum from aluminum ash slag in an embodiment of the present application;

[0031] Figure 2 It is a process flow chart of the process for extracting high-purity and high-recovery metallic aluminum from aluminum ash slag in an embodiment of the present application. Detailed Embodiments

[0032] To make the technical solutions and advantages of the present invention clearer, the following will further describe the present invention and its beneficial effects in detail in combination with the specific embodiments and the drawings in the specification, but the embodiments of the present invention are not limited thereto.

[0033] In the description of the present invention, unless otherwise clearly defined and limited, the terms "installation", "connection", "connection", and "fixation" shall be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral body; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0034] The standard parts used in the present invention can all be purchased from the market, and the special-shaped parts can be customized according to the description of the specification and the drawings. The specific connection methods of each part all adopt conventional means such as bolts, rivets, and welding that are mature in the prior art. The machinery, parts, and equipment all adopt conventional models in the prior art, and the circuit connection adopts the conventional connection method in the prior art, which will not be elaborated here.

[0035] The following will Figure 1-2 , make a further detailed description of this application.

[0036] This application provides a process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, and adopts the following technical solutions: including the following steps:

[0037] S1. Lift the ton bags of aluminum ash slag transported back to the raw material bin by an electric hoist.

[0038] Further, a triangular cone bag breaker is installed at the top of the raw material bin. The triangular cone bag breaker can automatically puncture the ton bags of aluminum ash slag, so that the aluminum ash slag therein falls into the raw material bin, realizing the rapid unloading of the aluminum ash slag.

[0039] S2. Transport the aluminum ash slag in the raw material bin to a jaw crusher through a vibrating feeder for crushing. The jaw crusher crushes the aluminum ash slag to a particle size less than 20 mm. In this step, the lumpy or granular aluminum ash slag is evenly, regularly, and continuously fed from the raw material bin to the jaw crusher through the vibrating feeder, thereby improving the uniformity of the crusher feed and being beneficial to improving the crushing efficiency of the crusher.

[0040] S3. Transport the crushed aluminum ash slag to a ball mill through a large-inclination belt (inclination greater than 45°) for pulverization and fine grinding, and then transfer the finely ground aluminum ash slag to a drum screen for screening. The particles in the material with a size larger than the screen holes are intercepted by the screen mesh on the screen and discharged in the form of oversize materials. Among them, the main component of the oversize materials is coarse aluminum flakes.

[0041] Furthermore, the ball mill is a double-compartment ball mill. The first compartment uses steel balls for grinding, and the second compartment uses steel segments for grinding. The particle size of the finely ground aluminum ash slag is less than 0.15 mm. With the double-compartment ball mill, the aluminum ash slag can be crushed more finely and evenly, thereby improving the fine grinding efficiency of the aluminum ash slag.

[0042] Even further, the drum sieve has a double-layer screen. The mesh size of the first-layer screen is 12 mesh (1.4 mm), and the mesh size of the second-layer screen is 80 mesh (0.18 mm). After passing through the drum sieve, the finely ground aluminum ash slag is divided into oversize (particle size greater than 1.4 mm), intermediate size (particle size less than or equal to 1.4 mm and greater than 0.18 mm), and undersize (particle size less than or equal to 0.18 mm). Among them, the main component of the oversize is coarse aluminum flakes, and the oversize enters the S4 step for further processing; the main component of the intermediate size is aluminum ash slag, and the intermediate size is fed back to the ball mill in the S3 step through a belt for secondary crushing and fine grinding to further improve the efficiency of material crushing; the main component of the undersize is fine aluminum ash, and the metal aluminum content in the fine aluminum ash is about 5%. The undersize is transferred to a storage bin for storage and will be separately processed later to recycle metal aluminum secondarily, increasing the recovery amount of metal aluminum, thereby improving the recovery rate of metal aluminum.

[0043] S4. Convey the coarse aluminum flakes to a magnetic separator through a belt. The magnetic separator can be equipment such as a flat magnetic separator or a flat magnetic iron remover. Remove the iron substances attached to the coarse aluminum flakes through the magnetic separator, thereby reducing other metal impurities attached to the coarse aluminum flakes and facilitating the improvement of the purity of metal aluminum.

[0044] S5. Weigh the coarse aluminum flakes after removing the iron substances and transfer them to a melting furnace through a hopper for heating. The coarse aluminum flakes are heated to a molten state to form molten aluminum liquid. Further, the melting furnace is an inclined gas crucible insulation furnace, heated to 700 °C with natural gas. The dross generated during the melting process is cooled and returned to the raw material bin for reprocessing to reduce the impurities in the molten aluminum liquid, thereby improving the purity of metal aluminum and facilitating the improvement of the recovery rate of metal aluminum.

[0045] S6. Pour the molten aluminum liquid into a casting aluminum chute, and input it into the ingot mold of a linear ingot casting machine through a distributor. The molten aluminum liquid cools and demolds in the ingot mold to form aluminum ingots, and then they are arranged and placed by a palletizing robot.

[0046] In a preferred embodiment of the present application, an electric heating wire is installed in the casting aluminum chute in the S6 step. The molten aluminum liquid in the casting aluminum chute is heated through the electric heating wire to maintain a stable molten state of the molten aluminum liquid and prevent the aluminum liquid from rapidly cooling and solidifying in the casting aluminum chute during the transfer process.

[0047] In a preferred embodiment of the present application, the running speed of the linear ingot casting machine in step S6 is controlled by a frequency converter. The running speed of the linear ingot casting machine is adjusted synchronously with the aluminum casting speed, avoiding the mixing of impurities in the aluminum ingot due to asynchronous speeds, thereby making the forming of the aluminum ingot more uniform and improving the surface quality of the aluminum ingot.

[0048] Furthermore, a burner is installed at the front end of the ingot mold of the linear ingot casting machine to preheat and dry the moisture in the ingot mold through the burner, avoiding the direct contact of high-temperature aluminum liquid with moisture, which may cause local splashing of aluminum liquid. This not only reduces the loss of aluminum liquid but also improves the safety of the process operation. A ingot receiving table is installed at the tail end of the linear ingot casting machine. After the aluminum ingot in the linear ingot casting machine is cooled and demolded, it falls onto the ingot receiving table and is grabbed and stacked by a palletizing robot.

[0049] In the steps S1 - S6 described above, a dust removal step is also carried out synchronously, including collecting the generated dust and waste gas through a dust removal system and recovering the metallic aluminum in the dust. Specifically, the dust removal system includes a normal-temperature bag filter and a high-temperature bag filter. Air ducts are connected above the raw material bin and the conveyor belt. By controlling the air volume, the generated dust-containing gas is introduced into the normal-temperature bag filter for dust removal. During the natural gas combustion and aluminum melting process, the entrained dust enters the dust collection hood above the aluminum melting furnace and is introduced into the high-temperature bag filter for dust removal. The aluminum ash collected by the bags of the normal-temperature bag filter and the high-temperature bag filter is transferred to the storage bin for storage, and subsequent secondary aluminum ash recovery treatment is carried out. Through this step, on the one hand, the dust content can be reduced by the dust removal system, making the discharged gas meet the environmental protection emission standards. On the other hand, the collected fine aluminum ash is transferred to the storage bin for temporary storage, which can collect and recover the aluminum ash in the air and further improve the recovery rate of metallic aluminum.

[0050] Based on the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the above specific embodiments. Any obvious improvements, substitutions, or variations made by those skilled in the art based on the present invention fall within the protection scope of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention.

Claims

1. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag, characterized in that It includes the following steps: S1. Feed the aluminum ash residue into the raw material bin. S2. Convey the aluminum ash residue in the raw material bin to a jaw crusher through a vibrating feeder for crushing, and crush the aluminum ash residue to a particle size less than 20 mm. S3. After the crushed aluminum ash residue is pulverized and finely ground by a ball mill, it is transferred to a rotary screen for screening to obtain oversize coarse aluminum flakes. S4. Convey the coarse aluminum flakes to a magnetic separator, and use the magnetic separator to remove the iron substances attached to the coarse aluminum flakes. S5. Weigh the coarse aluminum flakes after removing the iron substances and transfer them to a melting furnace for heating. The coarse aluminum flakes are heated to a molten state to form molten aluminum liquid. S6. Inject the molten aluminum liquid into the ingot mold of a straight ingot casting machine through a casting aluminum chute. After the molten aluminum liquid cools in the ingot mold, it is demolded to form aluminum ingots. Among them, in the steps of S1 - S6, a dust removal step is also carried out synchronously, including: collecting the generated dust and waste gas through a dust removal system and recovering the metallic aluminum in the dust.

2. The process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 1, wherein, In step S1, a triangular cone bag breaker is provided at the top of the raw material bin for puncturing the packaging bags of the aluminum ash residue.

3. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 1, characterized in that, In step S3, the ball mill is a double - chamber ball mill. The first chamber uses steel balls for grinding, and the second chamber uses steel segments for grinding. The particle size of the finely ground aluminum ash residue is less than 0.15 mm.

4. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag according to claim 1, characterized in that, In step S3, the rotary screen uses a double - layer screen mesh. The first - layer screen mesh is 12 meshes, and the second - layer screen mesh is 80 meshes; the aluminum ash residue passes through only the first - layer screen mesh of the rotary screen to obtain the intermediate product, and the intermediate product returns to the ball mill for secondary ball milling; the aluminum ash residue passes through the double - layer screen mesh of the rotary screen to obtain the undersize product, and the undersize product is fine aluminum ash, which is conveyed to a storage bin for recycling.

5. The process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag according to claim 1, wherein, In step S5, the melting furnace is a tiltable gas - fired crucible holding furnace, which is heated to 700 °C using natural gas.

6. The process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 5, wherein, Step S5 also includes cooling the dross generated during the melting of the coarse aluminum flakes and conveying it to the raw material bin.

7. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 1, characterized in that, In step S6, heating wires are provided in the casting aluminum chute to keep the molten aluminum liquid in a molten state through the heating wires.

8. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 1, characterized in that, In step S6, the running speed of the straight ingot casting machine is controlled by a frequency converter, and the running speed of the straight ingot casting machine is synchronously adjusted with the casting aluminum speed.

9. A process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash slag according to claim 1 or 8, characterized in that, In step S6, a burner is provided at the front end of the ingot mold of the straight ingot casting machine for drying the moisture in the ingot mold; a ingot receiving table is provided at the tail end of the ingot mold of the straight ingot casting machine for receiving the demolded aluminum ingots.

10. The process for extracting metallic aluminum with high purity and high recovery rate from aluminum ash residue according to claim 1, wherein In the dust removal step, the dust removal system includes a normal - temperature bag filter and a high - temperature bag filter. The normal - temperature bag filter is used to recover the aluminum ash generated from the raw material bin and the belt, and the high - temperature bag filter is used to recover the aluminum ash generated from the melting furnace.

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