Covering agent for smelting aluminum-containing waste as well as preparation method and application of covering agent

Abstract

The invention provides a covering agent for aluminum-containing waste smelting and a preparation method and application thereof, and belongs to the field of metal aluminum recovery. Comprising the following raw materials in parts by weight: 1 to 5 parts of MgCl2, 30 to 90 parts of NaCl, 30 to 60 parts of KCl, 1 to 5 parts of NaAlO2, 0.5 to 5 parts of Na2SO4, 1 to 10 parts of fluoride salt and 0.1 to 1.5 parts of Li2SiO3. The components of the covering agent for smelting the aluminum-containing waste are reasonably designed, the fluoride can effectively reduce the melting point of the solvent, and liquid aluminum is prevented from being further oxidized; naCl, KCl and MgCl2 form a multi-phase system with low melting point and small surface tension, so that the covering effect is enhanced; due to the grading design of KCl, MgCl2, NaAlO2 and Na2SO4, a more stable melt covering layer can be formed, and air suction and volatilization of the melt are reduced; all the components in the covering agent are fused with one another to form a compact multi-stage compound material, and the refining process is facilitated. Therefore, the burning loss of the aluminum-containing waste in the smelting process is reduced, and meanwhile the smelting recovery rate of the metal aluminum is increased.

Description

Technical Field

[0001] The present application relates to the technical field of metal aluminum recovery, and in particular to a covering agent for smelting aluminum-containing waste materials, and a preparation method and application thereof. Background Art

[0002] Aluminum and aluminum alloys are a kind of metal material commonly used in daily life. They have the advantages of low density, good light and heat conductivity, easy processing, shock absorption and noise reduction. They are widely used in aerospace, navigation, electronic mechanical components, transportation, packaging containers, daily sports and other fields. Aluminum and aluminum alloy materials will inevitably cause the loss of metal aluminum in the process of manufacturing and use, such as aluminum pots, aluminum tubes, aluminum cans and various aluminum used in construction in daily life. Waste aluminum materials; for example, aluminum slag formed by aluminum that is not completely recovered during the smelting process; and scraps and cuttings left over from the processing of some aluminum products. The above-mentioned aluminum slag, scraps and cuttings left over from processing, and waste aluminum materials formed by aluminum used in daily life, construction, transportation, etc. are collectively referred to as aluminum-containing waste, and with the continuous improvement of people's living standards, the amount of aluminum-containing waste has increased significantly.

[0003] However, the current domestic aluminum waste recycling market is relatively chaotic, with few large-scale aluminum waste smelting and recycling companies. In addition, the traditional aluminum waste smelting and recycling production process has a high burnout rate of metallic aluminum, with the common burnout rate being more than 5%, and a large amount of aluminum slag is also produced, which not only pollutes the environment but also reduces the aluminum recovery rate. Summary of the invention

[0004] The present application provides a covering agent for smelting aluminum-containing waste, a preparation method and an application thereof, in order to solve the following technical problem: how to improve the smelting recovery rate of metallic aluminum while reducing the burning loss of aluminum-containing waste during the smelting process.

[0005] In the first aspect, the present application provides a covering agent for smelting aluminum-containing waste, wherein the covering agent comprises the following raw materials, in parts by mass: MgCl 2 1 to 5 parts, NaCl 30 to 90 parts, KCl 30 to 60 parts, NaAlO 2 1 to 5 parts, Na 2 SO 4 0.5 to 5 parts, fluoride salt 1 to 10 parts and Li 2 SiO 3 0.1 to 1.5 portions.

[0006] Optionally, the fluoride salt comprises: AlF 3 、Na 3 AlF 6 , CaF 2 and K 3 AlF6 One or more of .

[0007] Optionally, the particle size of the covering agent is <2 mm.

[0008] In a second aspect, the present application provides a method for preparing the covering agent according to any one embodiment of the first aspect, the method comprising:

[0009] Mixing the raw materials of the covering agent according to set weight parts to obtain a coarse material;

[0010] The coarse material is sequentially melt-treated, cooled and ground into powder to obtain a covering agent.

[0011] Optionally, the temperature of the melting treatment is 800° C. to 900° C., and the time of the melting treatment is 60 min to 100 min.

[0012] In a third aspect, the present application provides an application of the covering agent according to any one embodiment of the first aspect, wherein the application comprises:

[0013] The covering agent is laid on at least a portion of the surface of the aluminum-containing waste block, and then compression molding is performed to form a core-shell structure aluminum material;

[0014] At a set heating rate, CaCO 3 The rotary heating is performed, and when the temperature of the rotary heating reaches a first set temperature, the CaCO 3 The core-shell structure aluminum material is added, and then the rotary heating is continued to melt the core-shell structure aluminum material to obtain aluminum liquid.

[0015] Optionally, the mass of the covering agent is 5% to 25% of the mass of the aluminum-containing waste block.

[0016] Optional, CaCO 3 The mass of the aluminum-containing waste block is 2% to 6% of the mass of the aluminum-containing waste block.

[0017] Optionally, the rotary heating uses a rotary furnace, the rotation speed of the rotary furnace is 5r / min to 10r / min, and the horizontal inclination angle is 5° to 15°.

[0018] Optionally, the set heating rate is 30°C / min to 40°C / min, the first set temperature is 600°C to 650°C, the endpoint temperature of the rotary heating is 720°C to 800°C, and the insulation time of the rotary heating at the endpoint temperature is 20min to 40min.

[0019] The above technical solution provided by the embodiment of the present application has the following advantages compared with the prior art:

[0020] The present invention provides a covering agent for smelting aluminum-containing waste, which comprises the following raw materials in parts by mass: MgCl 2 1 to 5 parts, NaCl 30 to 90 parts, KCl 30 to 60 parts, NaAlO 2 1 to 5 parts, Na 2 SO 4 0.5 to 5 parts, fluoride salt 1 to 10 parts and Li 2 SiO 3 0.1 to 1.5 parts. The present invention rationally designs the components of the covering agent for smelting aluminum-containing waste. Fluoride can effectively reduce the melting point of the solvent, quickly form a liquid film, and prevent further oxidation of liquid aluminum; NaCl, KCl and MgCl 2 Form a multi-phase system with low melting point and small surface tension, enhance the coverage effect and reduce impurities; KCl, MgCl 2 、NaAlO 2 and Na 2 SO 4 The grading design helps to form a more stable melt covering layer, reduce the absorption and volatilization of the melt, and reduce the possibility of defects in the aluminum ingot; in addition, the components in the covering agent fuse with each other to form a compact multi-level composite material, which can still maintain a close fit between the liquid films at a low speed, which is conducive to the refining process. In addition, the covering agent and the aluminum-containing waste are extruded to reduce the exposed area of ​​the aluminum-containing waste in the air; on the other hand, through the wrapping of the covering agent, when the aluminum-containing waste is smelted in the rotary furnace, part of the aluminum-containing waste is melted first, and part of the heat generated by the aluminum liquid is radiated to the covering agent, blocking oxidation and accelerating melting; the heat generated by the covering agent is reflected into the aluminum liquid, forming a virtuous cycle, until the melt is completely formed to cover the surface of the aluminum liquid, avoiding direct contact between the aluminum liquid and the air, and improving the recovery rate of metal aluminum in the aluminum-containing waste. Thereby, while reducing the burning loss of aluminum-containing waste during the smelting process, the smelting recovery rate of metal aluminum is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0022] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0023] Figure 1 A schematic diagram of the preparation method and application of the covering agent provided in the embodiments of the present application;

[0024] Figure 2 A flow chart of a method for preparing a covering agent provided in an embodiment of the present application;

[0025] Figure 3 A flow chart of the application of the covering agent provided in an embodiment of the present application. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0027] Various embodiments of the present application may be presented in the form of a range; it should be understood that the description in the form of a range is only for convenience and brevity, and should not be understood as a rigid limitation on the scope of the present application; therefore, the range description should be considered to have specifically disclosed all possible sub-ranges and single numerical values ​​within the range. For example, the range description from 1 to 6 should be considered to have specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5 and 6, which apply regardless of the range. In addition, whenever a numerical range is indicated herein, it is meant to include any cited number (fractional or integer) within the indicated range.

[0028] In addition, in the description of the specification of the present application, the terms "including", "comprising", etc. mean "including but not limited to". In this article, relational terms such as "first" and "second", etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this article, "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. Wherein A and B can be singular or plural. In this article, "at least one" means one or more, and "plurality" means two or more. "At least one", "the following at least one item (items)" or similar expressions refer to any combination of these items, including any combination of single items (items) or plural items (items). For example, "at least one of a, b, or c", or "at least one of a, b and c", can both mean: a, b, c, ab (i.e. a and b), ac, bc or abc, where a, b, c can be single or plural, respectively.

[0029] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] Aluminum-containing waste mainly comes from waste aluminum, aluminum slag, and scraps and cuttings from the production of other aluminum products. These aluminum-containing wastes have a high content of metallic aluminum and have a high recycling value. However, due to the complexity of the composition and the lack of a systematic recycling technology, this part of the aluminum resources is wasted in large quantities. Currently, the recycling of metallic aluminum generally relies on high-temperature smelting, but simple smelting not only leads to a large amount of oxidation of metallic aluminum, but also creates certain difficulties for the subsequent alloying or purification of the aluminum liquid.

[0031] The embodiments of the present application provide corresponding technical solutions to solve the above problems, which are as follows:

[0032] The present application provides a covering agent for smelting aluminum-containing waste, which includes the following raw materials in parts by mass: MgCl 2 1 to 5 parts, NaCl 30 to 90 parts, KCl 30 to 60 parts, NaAlO 2 1 to 5 parts, Na 2 SO 4 0.5 to 5 parts, fluoride salt 1 to 10 parts and Li 2 SiO 3 0.1 to 1.5 portions.

[0033] In some embodiments, the fluoride salt comprises: AlF 3 、Na 3 AlF 6 , CaF 2 and K 3 AlF 6 One or more of .

[0034] MgCl 2 :MgCl 2 After melting, a dense flux layer can be quickly formed on the surface of the aluminum liquid, effectively isolating the air and significantly reducing the oxidation rate of the aluminum liquid, thereby reducing the burning of the metal aluminum. 2 It can also absorb impurities such as iron oxide during the melting process, which helps to purify the melt. NaCl and KCl: As the main chloride salt components in the covering agent, NaCl and KCl have a lower melting point, which helps to form a molten covering layer at a lower temperature. At the same time, the lower surface tension of NaCl and KCl makes it difficult to form a difficult-to-separate interlayer between the aluminum liquid and the salt slag, thereby increasing the aluminum output rate. In addition, NaCl and KCl are relatively cheap, which reduces production costs. NaAlO2 :In the aluminum melting process, NaAlO 2 It can form a stable covering film, further enhancing the protection of aluminum liquid and reducing oxidation loss. 2 SO 4 :Na 2 SO 4 It can reduce the melting point of aluminum during the smelting process, thus helping to optimize smelting conditions and reduce energy consumption. 3 ,K 3 AlF 6 ,Na 3 AlF 6 ): Fluoride can not only lower the melting point, but also increase the fluidity of aluminum melt, which helps to improve the smelting effect. AlF 3 It can improve the surface tension of NaCl and KCl melts, promote the aggregation of tiny aluminum beads, and improve the uniformity of the smelting products. 3 AlF 6 and Na 3 AlF 6 AlF produced by decomposition at high temperature 3 It can effectively remove impurities such as iron and silicon in aluminum liquid and play a refining role. 2 SiO 3 :Although the content is relatively small, Li 2 SiO 3 It may have a positive impact on the overall performance of the covering agent through its unique physical and chemical properties, such as improving the stability of the melt and reducing the evaporation loss of the melt.

[0035] At the same time, the application reasonably designs the content of each raw material of the covering agent, which firstly helps fluoride and the like to effectively reduce the melting point of the solvent, quickly form a liquid film, and prevent further oxidation of the liquid aluminum. Secondly, it helps NaCl, KCl, MgCl 2 and CaF 2 The formation of a multi-phase system with low melting point and small surface tension enhances the coverage effect and reduces impurities. 2 、NaAlO 2 and Na 2 SO 4 The grading design helps to form a more stable melt covering layer, reduce the absorption and volatilization of the melt, and reduce the possibility of defects in the aluminum ingot. In addition, it helps the components in the covering agent to merge with each other to form a compact multi-level composite material, which can still maintain a close fit between the liquid films at a low speed, which is beneficial to the refining process. For example, MgCl 2The mass parts of can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc. The mass parts of NaCl can be 30 parts, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts. The mass parts of KCl can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, etc. The mass parts of NaAlO 2 The mass parts of Na can be 1 part, 1.2 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc. 2 SO 4 The mass parts of can be 0.5 parts, 1 parts, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, etc. The mass parts of the fluoride salt can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 6 parts, 8 parts, 10 parts, etc. 2 SiO 3 The mass parts can be 0.1 parts, 0.2 parts, 0.5 parts, 0.8 parts, 1.0 parts, 1.2 parts, 1.4 parts, 1.5 parts, etc.

[0036] In some embodiments, the particle size of the covering agent is <2 mm.

[0037] Limiting the particle size of the covering agent to less than 2mm makes it easier to form a uniform and dense protective layer, thereby more effectively preventing oxidation and impurity contamination of the aluminum liquid.

[0038] Figure 1 A schematic diagram of the preparation method and application of the covering agent provided in the embodiments of the present application; Figure 2 A flow chart of a method for preparing a covering agent provided in an embodiment of the present application; Figure 3 A flow chart of the application of the covering agent provided in an embodiment of the present application.

[0039] See also Figures 1 to 3 Based on a general inventive concept, the present application provides a method for preparing a covering agent as described in any one of the above embodiments, the method comprising:

[0040] S101, mixing the raw materials of the covering agent according to set weight parts to obtain a coarse material;

[0041] S102, sequentially melting, cooling and grinding the coarse material into powder to obtain a covering agent.

[0042] In some embodiments, the temperature of the melt treatment is 800° C. to 900° C., and the time of the melt treatment is 60 min to 100 min.

[0043] The temperature of the melting treatment is limited to 800°C to 900°C, and the time of the melting treatment is 60min to 100min. At this melting temperature and time, various covering agent components can be fully fused to form a solid solution required for application in the smelting process. Reasonable insulation time promotes the formation of various gradations. At the same time, high-temperature melting reduces the moisture in various reagents and is tightly combined. Too low temperature and time will cause incomplete fusion. Too high temperature or time will cause individual components of the covering agent to decompose or agglomerate, resulting in failure of the covering agent. Exemplarily, the temperature of the melting treatment can be 800°C, 810°C, 820°C, 830°C, 840°C, 850°C, 860°C, 880°C, 900°C, etc., and the time of the melting treatment can be 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, etc.

[0044] The product prepared by the method for preparing the covering agent is the above-mentioned covering agent. The chemical composition and structure of the covering agent prepared by the method for preparing the covering agent can refer to the above-mentioned embodiment. Since the method for preparing the covering agent adopts part or all of the technical solutions of the covering agent embodiment, it at least has all the beneficial effects brought by the technical solutions of the covering agent embodiment, which will not be described one by one here.

[0045] Based on a general inventive concept, the present application provides an application of the covering agent described in any one embodiment of the first aspect, the application comprising:

[0046] S201, laying the covering agent on at least a portion of the surface of the aluminum-containing waste block, and then performing compression molding to form a core-shell structure aluminum material;

[0047] S202, at a set heating rate, CaCO 3 The rotary heating is performed, and when the temperature of the rotary heating reaches a first set temperature, the CaCO 3 The core-shell structure aluminum material is added, and then the rotary heating is continued to melt the core-shell structure aluminum material to obtain aluminum liquid.

[0048] In some embodiments, the mass of the covering agent is 5% to 25% of the mass of the aluminum-containing waste block.

[0049] On the one hand, the use of covering agents can reduce the temperature during the smelting process and form a covering film on the surface of the aluminum liquid to block the contact between air and aluminum liquid and prevent further oxidation of the aluminum liquid. In addition, the molten salt formed can combine with the impurities in the aluminum liquid to achieve the purpose of impurity removal and purification. Among them, if the proportion of covering agent is too low, the coverage is insufficient and the burnout rate increases; if the proportion of covering agent is too high, on the one hand, the shell layer is thicker and requires a higher temperature or time to melt. On the other hand, if there is too much covering agent, the amount of slag increases, and some small aluminum beads will be sandwiched in the slag as they rotate, and the yield of aluminum-containing waste will decrease. Exemplarily, the mass of the covering agent can be 5%, 8%, 10%, 12%, 15%, 18%, 20%, 22%, 25%, etc. of the mass of the aluminum-containing waste block.

[0050] In some embodiments, CaCO 3 The mass of the aluminum-containing waste block is 2% to 6% of the mass of the aluminum-containing waste block.

[0051] The added calcium carbonate releases protective gas during the heating process, and the calcium oxide formed by decomposition can be a good slag-forming agent in the smelting process to prevent the quality of metal aluminum from decreasing. Specifically: on the one hand, the protective gas formed by the early thermal decomposition of calcium carbonate prevents the oxidation of aluminum; on the other hand, the calcium oxide produced by decomposition can also be used as a slag-forming agent to improve the purity of metal aluminum. For example, CaCO 3 The mass of the aluminum-containing waste block is 2%, 2.5%, 3%, 3.5%, 4%, 4.5%, 5%, 5.5%, 6%, etc.

[0052] In some embodiments, the rotary heating uses a rotary furnace, the rotary speed of the rotary furnace is 5 r / min to 10 r / min, and the horizontal inclination angle is 5° to 15°.

[0053] The rotation speed of the rotary furnace is limited to 5r / min~10r / min, and the horizontal inclination angle is 5°~15°. If the rotation speed is too fast, the solution will splash in the furnace body, resulting in increased burning loss of metal aluminum. If the rotation speed is slow, the aluminum-containing waste will be heated unevenly, and some aluminum-containing waste will not be melted, resulting in a decrease in the yield rate. If the horizontal inclination angle is too large, the aluminum-containing waste will accumulate, which will prolong the time to form the molten pool and increase energy loss. If the horizontal inclination angle is too small, the molten pool area formed by the aluminum-containing waste is large. At high temperature, the oxidation degree of metal aluminum increases, affecting the aluminum output rate of the aluminum-containing waste. Exemplarily, the rotation speed of the rotary furnace can be 5r / min, 6r / min, 7r / min, 8r / min, 9r / min, 10r / min, etc., and the horizontal inclination angle can be 5°, 7°, 9°, 10°, 12°, 14°, 15°, etc.

[0054] In some embodiments, the set heating rate is 30°C / min to 40°C / min, the first set temperature is 600°C to 650°C, the endpoint temperature of the rotary heating is 720°C to 800°C, and the holding time of the rotary heating at the endpoint temperature is 20min to 40min.

[0055] During the heating process, part of the added calcium carbonate releases protective gas, and the decomposed calcium oxide can be a good slag-forming agent in the smelting process to prevent the quality of metal aluminum from decreasing. If the rotary heating temperature is too low, the aluminum-containing waste will not be completely melted within the corresponding time, and the slag volume will be large. If the temperature is too high, the formed metal aluminum liquid will be severely burned. Correspondingly, if the holding time is low, there will be a large amount of slag. If the holding time is long, the burning rate will be high. Exemplarily, the heating rate can be set to 30℃ / min, 32℃ / min, 34℃ / min, 36℃ / min, 38℃ / min, 40℃ / min, etc., the first set temperature can be 600℃, 610℃, 620℃, 630℃, 640℃, 650℃, etc., the endpoint temperature of rotary heating can be 720℃, 730℃, 740℃, 750℃, 760℃, 770℃, 780℃, 790℃, 800℃, etc., and the holding time of rotary heating at the endpoint temperature can be 20min, 22min, 25min, 28min, 30min, 32min, 35min, 38min, 40min, etc.

[0056] In some embodiments, the method for preparing the aluminum-containing waste block comprises: drying the aluminum-containing waste at 150° C. for 6 h to 8 h after removing organic matter, and mechanically compressing and molding the aluminum-containing waste to obtain the aluminum-containing waste block.

[0057] Aluminum-containing waste includes waste aluminum, aluminum slag, and other scraps and cuttings from the production of aluminum products.

[0058] The present application will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are intended only to illustrate the present application and are not intended to limit the scope of the present application. The experimental methods for which specific conditions are not specified in the following examples are usually measured according to industry standards. If there is no corresponding industry standard, then the conditions recommended by the manufacturer are followed.

[0059] Example 1

[0060] This embodiment provides a covering agent for smelting aluminum-containing waste, and the preparation method thereof comprises the following steps:

[0061] S101, mixing the raw materials of the covering agent according to the set mass parts to obtain a coarse material; the raw materials of the covering agent are: MgCl 23 parts, NaCl 52 parts, KCl 34 parts, AlF 3 2 portions, Na 3 AlF 6 or K 3 AlF 6 2.5 parts, Li 2 SiO 3 0.5 parts NaAlO 2 2 parts, CaF 2 1 part and Na 2 SO 4 3 servings;

[0062] S102, sequentially subjecting the coarse material to melting treatment, cooling and grinding into powder to obtain a covering agent; the melting treatment temperature is 800° C., the melting time is 100 min, and the particle size of the covering agent is less than 2 mm.

[0063] Based on the above covering agent, this embodiment also provides an application of the covering agent, including the following steps:

[0064] S201, the aluminum-containing waste is pretreated and extruded to form an aluminum-containing waste block, a covering agent is laid on the surface of the aluminum-containing waste block, and then compression molding is performed to form a core-shell structure aluminum material;

[0065] S202, put calcium carbonate powder into a rotary furnace for heating to 600°C, add core-shell aluminum material, continue to heat to a specified temperature, smelt and recover liquid aluminum metal, tilt the rotary furnace after the aluminum-containing waste is melted, block the aluminum slag and pour out the aluminum liquid, remove the aluminum slag after the aluminum liquid is completely out, and cool and solidify the aluminum liquid to obtain an aluminum ingot. The specific process parameters of the application of the covering agent and the aluminum recovery results are shown in Table 1.

[0066] Example 2

[0067] The difference between this embodiment and embodiment 1 is that the temperature of the melting treatment of the covering agent is 820°C, the melting time is 90 minutes, and the specific process parameters of the application of the covering agent are different. The specific process parameters of the application of the covering agent and the aluminum recovery results are shown in Table 1.

[0068] Example 3

[0069] The difference between this embodiment and embodiment 1 is that the temperature of the melting treatment of the covering agent is 840°C, the melting time is 80 minutes, and the specific process parameters of the application of the covering agent are different. The specific process parameters of the application of the covering agent and the aluminum recovery results are shown in Table 1.

[0070] Example 4

[0071] The difference between this embodiment and embodiment 1 is that the temperature of the melting treatment of the covering agent is 860°C, the melting time is 70 minutes, and the specific process parameters of the application of the covering agent are different. The specific process parameters of the application of the covering agent and the aluminum recovery results are shown in Table 1.

[0072] Example 5

[0073] The difference between this embodiment and embodiment 1 is that the temperature of the melting treatment of the covering agent is 900°C, the melting time is 60 minutes, and the specific process parameters of the application of the covering agent are different. The specific process parameters of the application of the covering agent and the aluminum recovery results are shown in Table 1.

[0074] Comparative Example 1

[0075] The difference between this comparative example and Example 1 is that the amount of covering agent added is different. In this comparative example, 2% of covering agent is added, and the rest of the steps are the same as Example 1. Due to the reduction of the added covering agent, the molten salt film formed above the aluminum liquid is reduced, and part of the metal aluminum liquid is exposed, resulting in a decrease in the aluminum recovery rate. The specific process parameters and aluminum recovery results of this example are shown in Table 1.

[0076] Comparative Example 2

[0077] The only difference between this comparative example and Example 2 is that calcium carbonate is not added in the early stage of smelting, and the remaining steps are the same as Example 2. Since calcium carbonate is not added, effective protective gas and slag forming agent cannot be formed, resulting in a reduced aluminum recovery rate. The specific process parameters and aluminum recovery results of this example are shown in Table 1.

[0078] Comparative Example 3

[0079] The only difference between this comparative example and Example 3 is that the holding time is different. This comparative example holds the temperature for 50 minutes, and the other steps are the same as Example 3. Due to the extended smelting time, the contact between the liquid metal aluminum and the air is increased, resulting in a reduced aluminum recovery rate. The specific process parameters and aluminum recovery results of this example are shown in Table 1.

[0080] Comparative Example 4

[0081] The only difference between this comparative example and Example 4 is that no covering agent is added, and the remaining steps are the same as those of Example 4. Since the metallic aluminum liquid is directly in contact with the air, the recovery rate of aluminum is reduced. The specific process parameters and aluminum recovery results of this example are shown in Table 1.

[0082] Comparative Example 5

[0083] The only difference between this comparative example and Example 5 is that the smelting temperature is increased to 820°C, and the remaining steps are the same as those of Example 5. As the smelting temperature is increased, more impurities such as aluminum oxide are formed when the aluminum liquid contacts the air, resulting in a decrease in the aluminum recovery rate. The specific process parameters and aluminum recovery results of this example are shown in Table 1.

[0084] Table 1 Process parameters and aluminum recovery rate of the covering agent application in the embodiments and comparative examples

[0085]

[0086] It can be seen from Comparative Example 1 and Example 1 that appropriately increasing the amount of covering agent added can prevent oxidation of metallic aluminum liquid during the smelting process, avoid causing large amounts of burning, and improve the recovery of metallic aluminum in aluminum-containing waste.

[0087] It can be seen from Comparative Example 2 and Example 2 that calcium carbonate can provide protective gas and slag-forming agent during the smelting process, reduce oxidation, and avoid waste of metallic aluminum.

[0088] When the smelting time is extended in Comparative Example 3 and Example 3, overburning occurs, which is not conducive to the recovery of metallic aluminum.

[0089] It can be seen from Comparative Example 4 and Example 4 that without adding a covering agent, the oxidation of metallic aluminum will be greatly affected, resulting in increased burnout and causing certain difficulties in subsequent refining.

[0090] It can be seen from Comparative Example 5 and Example 5 that increasing the temperature will lead to faster oxidation of metallic aluminum, resulting in more aluminum slag, resulting in increased aluminum burnout, which is not conducive to the recovery of metallic aluminum in the actual production process.

[0091] In addition, one or more technical solutions in the embodiments of the present invention have at least the following technical effects or advantages:

[0092] In the embodiments of the present invention, the provided covering agent will not cause corrosion to the furnace body, and the covering agent will not stick to the furnace wall after smelting, and is easy to clean. In addition, the chemical reagent raw materials provided by the present invention are easy to obtain, and no toxic gases such as nitrogen oxides are generated during the smelting process, so the smelting process is green and environmentally friendly. The provided covering agent and the use method can increase the smelting recovery rate of metallic aluminum in aluminum-containing waste to more than 98%, providing technical support for maximizing the recovery of metallic aluminum in the recycled aluminum industry, and having broad application prospects in the recycled aluminum industry.

[0093] In an embodiment of the present invention, an extruded core-shell structure is designed, in which the aluminum-containing waste and the covering agent are extruded to form a tight covering agent wrapped around the outer layer of the aluminum-containing waste, thereby conserving energy while isolating the air, and different proportions of the covering agent components are graded to form different multiphase substances. The addition of the covering agent during the rotary smelting process of the aluminum-containing waste can effectively reduce the contact between the aluminum liquid and the air, reduce the oxidation of the metallic aluminum, and also play a refining role to avoid the degradation of the aluminum quality, thereby effectively reducing the burning loss rate of the aluminum-containing waste smelting and improving the quality of the recovered metallic aluminum.

[0094] The above description is only a specific implementation of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to the embodiments shown herein, but will conform to the widest range consistent with the principles and novel features applied for herein.

Claims

1. A covering agent for smelting aluminum-containing waste, characterized in that: In parts by mass, the covering agent includes the following raw materials: 1 to 5 parts of MgCl2, 30 to 90 parts of NaCl, 30 to 60 parts of KCl, 1 to 5 parts of NaAlO2, 0.5 to 5 parts of Na2SO4, 1 to 10 parts of fluoride salt and 0.1 to 1.5 parts of Li2SiO3.

2. The covering agent according to claim 1, characterized in that The fluoride salt includes one or more of AlF3, Na3AlF6, CaF2 and K3AlF6.

3. The covering agent according to claim 1, characterized in that The particle size of the covering agent is less than 2 mm.

4. A method for preparing the covering agent according to any one of claims 1 to 3, characterized in that: The method comprises: Mixing the raw materials of the covering agent according to set weight parts to obtain a coarse material; The coarse material is sequentially melt-treated, cooled and ground into powder to obtain a covering agent.

5. The method according to claim 4, characterized in that The temperature of the melting treatment is 800° C. to 900° C., and the time of the melting treatment is 60 min to 100 min.

6. Use of the covering agent according to any one of claims 1 to 3, characterized in that: The applications include: The covering agent is laid on at least a portion of the surface of the aluminum-containing waste block, and then compression molding is performed to form a core-shell structure aluminum material; The CaCO3 is rotationally heated at a set heating rate. When the rotationally heated temperature reaches a first set temperature, the core-shell structure aluminum material is added to the CaCO3 having the first set temperature, and then the rotational heating is continued to melt the core-shell structure aluminum material to obtain aluminum liquid.

7. The use according to claim 6, characterized in that: The mass of the covering agent is 5% to 25% of the mass of the aluminum-containing waste block.

8. The use according to claim 6, characterized in that: The mass of CaCO3 is 2% to 6% of the mass of the aluminum-containing waste block.

9. The use according to claim 6, characterized in that: The rotary heating uses a rotary furnace, the rotary speed of the rotary furnace is 5 r / min to 10 r / min, and the horizontal inclination angle is 5° to 15°.

10. The use according to claim 6, characterized in that: The set heating rate is 30°C / min to 40°C / min, the first set temperature is 600°C to 650°C, the end temperature of the rotary heating is 720°C to 800°C, and the insulation time of the rotary heating at the end temperature is 20min to 40min.

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