Innovative technology for defluorination of secondary aluminum dross by alkali leaching

The worldwide recycled aluminum generation is increasing quickly thanks to the environmental considerations and continuous growing of use demands. Aluminum dross recycling, as the secondary aluminum process, has been always considered as a problematic issue in the world. The aim of this work is to propose a methodical and easy procedure for the proposed system selection as the MCDM problem. Here, an evaluation method, integrated FAHP, is presented to evaluate aluminum waste management systems. Therefore, we drive weights of each pair comparison matrix by the use of the goal programming (GP) model. The functional unit includes aluminum dross and aluminum scrap, which is defined as 1000 kilograms. The model is confirmed in the case of aluminum waste management in Arak. For the proposed integrated fuzzy AHP model, five alternatives are investigated. The results showed that, according to the selected attributes, the best waste management alternative is the one involving the primary aluminum ingot 99.5% including 200 kg and the secondary aluminum 98% (scrap) including 800 kg, and beneficiation activities are implemented, duplicate aluminum dross is recycled in the plant, and finally it is landfilled.

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Harmless disposal and resource utilization for secondary aluminum dross: A review

The Science of The Total Environment ◽

10.1016/j.scitotenv.2020.143968 ◽

2021 ◽

Vol 760 ◽

pp. 143968

Author(s):

Hanlin Shen ◽

Bo Liu ◽

Christian Ekberg ◽

Shengen Zhang

Keyword(s):

Resource Utilization ◽

Secondary Aluminum ◽

Aluminum Dross ◽

Harmless Disposal

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A Study of Stabilization and Recycling for Aluminum Dross

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.275-277.2237 ◽

2013 ◽

Vol 275-277 ◽

pp. 2237-2240 ◽

Cited By ~ 1

Author(s):

Hsieh Kuo Cheng ◽

T.H. Ueng ◽

Ching Chyi Chen

Keyword(s):

Calcium Oxide ◽

Manufacturing Process ◽

Raw Materials ◽

Aluminum Carbide ◽

Raw Material ◽

Hydration Reaction ◽

Secondary Aluminum ◽

Stabilizing Agents ◽

Alkaline Environment ◽

Aluminum Dross

In this study, a recycling process for stabilized secondary aluminum dross is proposed. Calcium oxide-containing materials, such as de-sulfur slag produced from steel manufacturing process, are used as stabilizing agents for secondary aluminum dross. The de-sulfur slag was first hydrolyzed. Due to the high content of calcium oxide (about 45%), hydration of de-sulfur slag can produce a solution with strong alkalinity (pH≧12). In the strong alkaline environment, the residual pernicious components in the aluminum dross, such as aluminum nitride, aluminum carbide and metal aluminum, are hydrolyzed and decomposed rapidly, resulting in the stabilization of secondary aluminum dross. The stabilized aluminum dross, therefore, was used as the raw material for preparing concrete bricks. In the subsequent concrete brick manufacturing process, the hydration reaction between stabilized aluminum dross and other raw materials can also produce strong alkaline environment (pH≧12), which further stabilizes the aluminum dross wastes, and produce high-pressure concrete bricks with satisfactory performance.

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Research on the Preparation Parameters and Basic Properties of Premelted Calcium Aluminate Slag Prepared from Secondary Aluminum Dross

Materials ◽

10.3390/ma14195855 ◽

2021 ◽

Vol 14 (19) ◽

pp. 5855

Author(s):

Shaoyan Hu ◽

Deyong Wang ◽

Dong Hou ◽

Wei Zhao ◽

Xianglong Li ◽

...

Keyword(s):

Melting Point ◽

Resource Utilization ◽

Calcium Aluminate ◽

Water Soluble ◽

Secondary Aluminum ◽

Phase Component ◽

Aluminum Dross ◽

Leaching Toxicity ◽

Main Components ◽

Main Component

Secondary aluminum dross is a byproduct of the electrolytic aluminum industry, whose main components are Al2O3, AlN and Na3AlF6. Secondary aluminum dross is a type of hazardous waste, with a tremendous yield every year. Realizing the harmless treatment or resource utilization of secondary aluminum dross has important economic and social benefits. In the present research, the process of preparing premelted calcium aluminate slag used for molten steel refining from secondary aluminum dross was studied in detail. Firstly, the chemical composition and phase component of secondary aluminum dross were analyzed systematically. Then, according to phase diagram analysis and melting point measurement, the appropriate mixing ratio of CaO and secondary aluminum dross and the appropriate calcination temperature were determined. On this basis, an experiment of premelted calcium aluminate slag preparation was carried out in a tubular resistance furnace. The phase component and micromorphology of the premelted slag were analyzed by XRD and SEM. The results show that the main component of the premelted calcium aluminate slag is 11CaO·7Al2O3·CaF2 phase with a low melting point. The original Na3AlF6 phase, which is the cause of leachable fluoride in secondary aluminum dross, disappears totally, and there is no water-soluble fluoride detected in the leaching toxicity detection. The research indicates that the process of preparing premelted calcium slag from secondary aluminum dross is feasible, which provides a helpful reference for the resource utilization of secondary aluminum dross.

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The Investigation of Optimizing Leaching Efficiency of Al in Secondary Aluminum Dross via Pretreatment Operations

Processes ◽

10.3390/pr8101269 ◽

2020 ◽

Vol 8 (10) ◽

pp. 1269

Author(s):

Haigang Feng ◽

Guofan Zhang ◽

Qun Yang ◽

Luobing Xun ◽

Siyuan Zhen ◽

...

Keyword(s):

Chemical Interaction ◽

Acid Leaching ◽

Scanning Electron Micrographs ◽

Water Leaching ◽

Secondary Aluminum ◽

Aluminum Dross ◽

Process Mineralogy ◽

Leaching Experiments ◽

Physical And Chemical ◽

Leaching Efficiency

Secondary aluminum dross (SAD) is an inevitable by-product from the secondary aluminum industry and has caused serious environmental issues. In this study, the effect of pretreatment operations on the subsequent acid leaching operation was studied by process mineralogy, a series of leaching experiments, XRD, and SEM. Leaching results showed that the leaching efficiency of Al in direct acid leaching was only 22.99%. Process mineralogy showed the complex intertexture and continuous network structure in the SAD. Pretreatment operations were extremely efficient in destroying the structure by physical and chemical interaction. Interestingly, by adding the grinding and water leaching operations, the leaching efficiency of total aluminum in the SAD reached approximately 28.70%. XRD results showed that nearly all metallic Al, AlN, and partial Al2O3 were leached by grinding–water leaching–acid leaching. The scanning electron micrographs showed that the residue particles mainly included some insoluble components and had a smooth surface.

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