阅读说明：本技术 废铝的回收利用方法 (Method for recycling waste aluminum ) 是由 李鹏 杨墨瞳 国宏伟 闫炳基 陈栋 于 2019-10-25 设计创作，主要内容包括：本发明公开了一种废铝的回收利用方法,其包括如下步骤：对废铝进行预处理；将预处理后的废铝与碳酸锂熔盐混合,随后放入坩埚中,并将所述坩埚置于反应炉内,通入惰性气体以将所述反应炉中的空气排出；加热至反应温度并通入二氧化碳进行反应；对反应后的尾气以及固态产物进行收集。上述废铝的回收利用方法,首先,生成的固态产物为γ-LiAlO<Sub>2</Sub>,γ-LiAlO<Sub>2</Sub>材料具有良好的热稳定性、耐熔融碳酸盐腐蚀能力,可作为MCFC的电解质基板材料。并且通过本发明的废铝回收利用方法制得的γ-LiAlO<Sub>2</Sub>材料,利用废铝替代原生铝,能够大幅度降低γ-LiAlO<Sub>2</Sub>材料的生产成本,可大规模推广应用。其次,反应过程中消耗二氧化碳,将二氧化碳转换为一氧化碳燃料,实现碳减排与循环利用。(The invention discloses a recycling method of waste aluminum, which comprises the following steps of pretreating the waste aluminum, mixing the pretreated waste aluminum with lithium carbonate molten salt, then placing the mixture into a crucible, placing the crucible into a reaction furnace, introducing inert gas to discharge air in the reaction furnace, heating to a reaction temperature, introducing carbon dioxide to react, collecting tail gas and solid products after the reaction 2 ，γ‑LiAlO 2 The material has good thermal stability and molten carbonate corrosion resistance, and can be used as an electrolyte substrate material of MCFC. And gamma-LiAlO prepared by the method for recycling aluminum scrap 2 The material utilizes waste aluminum to replace original aluminum, and can greatly reduce gamma-LiAlO 2 MaterialThe production cost can be promoted to for application in a large scale, and then carbon dioxide is consumed in the reaction process and is converted into carbon oxide fuel, so that carbon emission reduction and recycling are realized.)

1, kinds of aluminium scrap recycling method, characterized by, including the following step:

pretreating the waste aluminum;

mixing the pretreated waste aluminum with lithium carbonate molten salt, then placing the mixture into a crucible, placing the crucible into a reaction furnace, and introducing inert gas to exhaust air in the reaction furnace;

heating to a reaction temperature and introducing carbon dioxide for reaction;

collecting the tail gas and the solid products after the reaction.

2. The method for recycling the aluminum scrap according to claim 1, wherein the aluminum scrap is aluminum cans.

3. The method for recycling aluminum scrap according to claim 2, wherein the pretreatment comprises the steps of:

crushing the waste aluminum, and then performing paint removal treatment on the waste aluminum.

4. The method of recycling scrap aluminum in accordance with claim 3, wherein the average size of the scrap aluminum after crushing is 2mm x 2 mm.

5. The method for recycling the aluminum scrap according to claim 3, wherein the depainting treatment is to treat the aluminum scrap at 500 ℃ for 20-30 min.

6. The method for recycling aluminum scrap according to claim 1, wherein the reaction temperature is 800 ℃ to 950 ℃.

7. The method of claim 1, wherein the partial pressure of carbon dioxide is not higher than twenty percent during the reaction.

8. The method for recycling aluminum scrap according to claim 1, further comprising:

the collected reaction tail gas is subjected to carbon dioxide removal through soda lime and is dried through silica gel.

9. The method of recycling scrap aluminum in accordance with claim 1 wherein the crucible is a platinum crucible.

10. The method of recycling scrap aluminum in accordance with claim 1 wherein said inert gas is argon.

Technical Field

The invention belongs to the technical field of waste aluminum recovery, and relates to a recycling method of waste aluminum.

Background

During the production and processing of metallic aluminum and the distribution and use of related aluminum products, a large amount of scrap aluminum is produced each year. The waste aluminum pop-top can is taken as an example for explanation, and the yield of the waste aluminum pop-top can is about 16-20 ten thousand tons every year in China; although most of the waste aluminum ring-pull cans are recycled, the recovery rate can reach more than 85%, the recycling difficulty of the recycled waste aluminum ring-pull cans is high, most of the waste aluminum ring-pull cans are degraded and used, and the utilization added value of aluminum resources is greatly reduced.

The traditional treatment method of the waste aluminum pop-top can comprises the following steps: through smelting, component regulation, filtering, casting and other steps. The traditional treatment mode not only has complex process, but also can generate a large amount of aluminum slag in the smelting process. The compounds such as aluminum nitride and aluminum carbide contained in the aluminum slag are easy to hydrolyze in a humid environment, and generate a large amount of flammable and harmful gases.

Therefore, the method has important practical significance for exploring a new method for recycling the aluminum scraps, carrying out efficient treatment and improving the added utilization value of the aluminum scraps.

Disclosure of Invention

In order to overcome the defects in the prior art, new methods for recycling the waste aluminum are needed.

The recycling method of kinds of waste aluminum comprises the following steps:

pretreating the waste aluminum;

mixing the pretreated waste aluminum with lithium carbonate molten salt, then placing the mixture into a crucible, placing the crucible into a reaction furnace, and introducing inert gas to exhaust air in the reaction furnace;

heating to a reaction temperature and introducing carbon dioxide for reaction;

collecting the tail gas and the solid products after the reaction.

The method for recycling the waste aluminum comprises the steps of firstly, generating a solid product of gamma-LiAlO₂，γ-LiAlO₂The material has good propertiesGood thermal stability and resistance to corrosion of molten carbonate, and can be used as electrolyte substrate material of MCFC. The method utilizes the waste aluminum to replace the original aluminum, and can greatly reduce the gamma-LiAlO₂The production cost of the material can be promoted to for application in a large scale, and then carbon dioxide is consumed in the reaction process and is converted into carbon oxide fuel, so that carbon emission reduction and recycling are realized.

Optionally, the aluminum scrap is aluminum cans.

Optionally, the pre-processing comprises the steps of:

crushing the waste aluminum, and then performing paint removal treatment on the waste aluminum.

Optionally, the crushed scrap aluminum has an average size of 2mm x 2 mm.

Optionally, the depainting treatment is to treat the waste aluminum at 500 ℃ for 20min to 30 min.

Optionally, the reaction temperature is from 800 ℃ to 950 ℃.

Alternatively, the partial pressure of carbon dioxide during the reaction should not be greater than twenty percent.

Optionally, the method further comprises:

the collected reaction tail gas is subjected to carbon dioxide removal through soda lime and is dried through silica gel.

Optionally, the crucible is a platinum crucible.

Optionally, the inert gas is argon.

Drawings

FIG. 1 is a technical flowchart of a method for recycling scrap aluminum according to the present invention.

FIG. 2 shows scrap aluminum and CO₂The high temperature reaction behavior is shown in (A) as the CO generation rate curve and (B) as the metallic aluminum conversion curve.

FIG. 3 is a phase diagram of X-ray diffraction analysis of the solid product obtained in example 1.

FIG. 4 is a scanning electron microscopy topography characterization of the solid product from example 1.

Detailed Description

For purposes of making the objects, aspects and advantages of the present invention more apparent, the present invention is described in further detail in conjunction with the following detailed description.

The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention, the term "and/or" as used herein includes any and all combinations of or more of the associated listed items.

The invention provides a recycling method of waste aluminum, which is described below by taking the waste aluminum as an example of a pop can.

The elemental composition of the can body is shown in table 1 and contains about 97 wt% of metallic aluminum, as well as other alloying elements.

TABLE 1 elemental composition of Pop-top can body

The method for recycling the waste aluminum provided by the invention, as shown in figure 1, comprises the following steps:

and S1, pretreating the waste aluminum.

In step S1, the purpose of pretreatment is to effectively ensure the proceeding of the subsequent reaction and avoid the influence of other substances in the aluminum scrap on the subsequent reaction.

In , the pretreatment comprises the steps of crushing the waste aluminum, and then performing paint removal treatment on the waste aluminum, wherein the paint removal treatment can remove the paint attached to the surface of the waste aluminum such as pop cans and the like, and avoid the influence of the paint on the subsequent reaction.

More specifically, the average size of the scrap after crushing was 2mm × 2mm, which further steps improved the subsequent reaction.

In a more specific embodiment, the depainting treatment is carried out by treating the aluminum scrap at 500 ℃ for 20min to 30 min. Through high-temperature treatment, the paint attached to the surface of the aluminum scrap is removed, so that the removing effect is good.

Of course, before or after crushing, a cleaning step can be optionally added according to actual conditions to remove dirt on the surface of the waste aluminum.

And S2, mixing the pretreated waste aluminum with lithium carbonate molten salt, then placing the mixture into a crucible, placing the crucible into a reaction furnace, and introducing inert gas to exhaust air in the reaction furnace.

In a preferred embodiment of , the crucible is a platinum crucible.

In step S2, the inert gas is introduced to exhaust the air in the reaction furnace, so as to prevent the aluminum scrap from being oxidized by oxygen in the air during the subsequent reaction. The inert gas is preferably argon.

Preferably, high purity argon gas of 200ml/min is continuously introduced for 12 hours before the reaction, thereby blowing off the air remaining in the reaction furnace and the piping.

And S3, heating to the reaction temperature and introducing carbon dioxide for reaction.

Scrap aluminum and CO₂The high temperature reaction behavior in the presence of lithium carbonate molten salt is shown in figure 2. In fig. 2, the boxes represent the case where only the scrap aluminum, i.e., no lithium carbonate molten salt, is present; the circle represents the condition of the waste aluminum under the action of lithium carbonate molten salt; wherein (A) is a CO generation rate curve, and (B) is a metallic aluminum conversion rate curve. The inventor of the invention discovers through research that under the participation of lithium carbonate molten salt, the waste aluminum and CO can be greatly improved within the temperature range of 850-₂The reaction rate of the catalyst is improved, and the conversion rate of the waste aluminum is improved to 0.88 from the original 0.03.

In step S3, at high temperature, the carbon dioxide and the waste aluminum undergo an oxidation-reduction reaction to generate an aluminum oxide film and carbon oxide, and once the dense aluminum oxide film is generated, the reaction rate is greatly reduced, while in the presence of lithium carbonate, the liquid lithium carbonate molten salt reacts with the dense aluminum oxide film on the surface of the waste aluminum to generate lithium aluminate, which continuously consumes and destroys the aluminum oxide film, thereby promoting the overall reaction.

After the reaction, the carbon dioxide was converted to carbon oxide, and the lithium carbonate was converted to γ -LiAlO₂。

In a preferred embodiment of , the reaction temperature is in the range of 800 ℃ to 950 ℃.

Alternatively, the partial pressure of carbon dioxide during the reaction should not be greater than twenty percent.

In a preferred embodiment of , the reactor is ramped up to 900 deg.C at a ramp rate of 5 deg.C/min and 40ml/min CO is started at 500 deg.C₂A gas.

And S4, collecting the tail gas and the solid products after the reaction.

In step S4, the solid product is γ -LiAlO₂. Specifically, the solid product is cooled to normal temperature under an inert atmosphere and collected.

In the embodiment, the reaction off-gas collected is subjected to soda lime to remove carbon dioxide and silica gel to obtain carbon oxide fuel with high purity.

The method for recycling the waste aluminum comprises the steps of firstly, generating a solid product of gamma-LiAlO₂，γ-LiAlO₂The material has good thermal stability and molten carbonate corrosion resistance, and can be used as an electrolyte substrate material of MCFC. And gamma-LiAlO prepared by the method for recycling aluminum scrap₂Secondly, carbon dioxide is consumed in the reaction process and is converted into carbon oxide fuel, so that carbon emission reduction and recycling are realized, and the conversion rate of carbon dioxide to carbon oxide can be greatly improved under the participation of lithium carbonate molten salt, so that the utilization rate of substances and energy of the whole reaction system is maximized.

By adopting the method of the invention, tons of aluminum pop cans can be produced to obtain 2.32 tons of cansPurity lithium aluminate, 1144 cubic meters of CO, while consuming 1.47 tons of greenhouse gas CO₂And the aim of carbon emission reduction is effectively fulfilled.

The invention is further illustrated at with reference to specific examples.