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Xie H, Guo Z, Xu R, Zhang Y. Particle sorting to improve the removal of fluoride and aluminum nitride from secondary aluminum dross by roasting. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2023; 30:54536-54546. [PMID: 36872407 DOI: 10.1007/s11356-023-26201-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2022] [Accepted: 02/25/2023] [Indexed: 06/18/2023]
Abstract
It is important to remove active substances from secondary aluminum dross (SAD) to meet the reuse of SAD. In this work, the removal of active substances from different particle sizes of SAD was studied using roasting improvement with particle sorting. The results showed that roasting after particle sorting pretreatment can effectively remove fluoride and aluminum nitride (AlN) from SAD, while getting the high-grade alumina (Al2O3) crude materials. The active substances of SAD mainly contribute to AlN, aluminum carbide (Al4C3), and soluble fluoride ions. AlN and Al3C4 mainly exist in particles of 0.05-0.1 mm, while Al and fluoride are mainly in particles of 0.1-0.2 mm. The SAD of particle size ranging 0.1-0.2 mm has high activity and leaching toxicity; the gas emission was reached 50.9 mL/g (limit value of 4 mL/g), and the fluoride ion concentration in the literature was 137.62 mg/L (limit value of 100 mg/L) during the identification for reactivity and leaching toxicity according to GB5085.5-2007 and GB5085.3-2007, respectively. Roasting at 1000 °C for 90 min, the active substances of SAD were converted to Al2O3, N2, and CO2; meanwhile, soluble fluoride converted to stable CaF2. The final gas release was reduced to 2.01 mL/g while soluble fluoride from SAD residues was reduced to 6.16 mg/L, respectively. The Al2O3 content of SAD residues was determined at 91.8% and has been classified as category I solid waste. The results suggested that the roasting improvement with particle sorting of SAD can meet the reuse of valuable materials at full scale.
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Affiliation(s)
- Huimin Xie
- School of Metallurgy and Environment, Central South University, No. 932 South Lushan Road, Changsha, 410083, China
| | - Zhaohui Guo
- School of Metallurgy and Environment, Central South University, No. 932 South Lushan Road, Changsha, 410083, China.
| | - Rui Xu
- School of Metallurgy and Environment, Central South University, No. 932 South Lushan Road, Changsha, 410083, China
| | - Yanglin Zhang
- School of Metallurgy and Environment, Central South University, No. 932 South Lushan Road, Changsha, 410083, China
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Li Z, Li H, Huang X, Wu W, Sun Z, Wu X, Li S. Removal of nitrides and fluorides from secondary aluminum dross by catalytic hydrolysis and its mechanism. Heliyon 2023; 9:e12893. [PMID: 36691546 PMCID: PMC9860295 DOI: 10.1016/j.heliyon.2023.e12893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 01/05/2023] [Accepted: 01/06/2023] [Indexed: 01/10/2023] Open
Abstract
Secondary aluminum dross (SAD) refers to hazardous waste from secondary aluminum refinement. It contains a large amount of aluminum nitride and fluorides that cause serious environmental pollution for direct discharge and hinder the resource utilization of SAD. However, it is difficult to remove nitride and fluoride simultaneously for their complicated phases. In this paper, the catalytic hydrolysis of SAD using NaOH as a catalyst to remove nitrides and fluorides synchronously was investigated systemically through single factor and response surface experiments. In addition, the chemical speciation and transformation of nitrides and fluorides were analyzed systematically. The catalytic hydrolysis removal mechanism was summarized. The optimal conditions for catalytic hydrolysis were established as follows: reaction temperature 96.60 °C; reaction time 2.85 h; liquid-solid ratio 9.28 mL/g and catalyst addition 12.62 wt %; and removal efficiency of nitrides and fluorides reached 99.03% and 81.93%, respectively. The mechanism of nitrides removal was that aluminum nitride was hydrolyzed to Al(OH)3 and NH3. NaOH reacting with Al(OH)3 covering on the surface of AlN and the rapid escape of NH3 promoted the hydrolysis of AlN under the catalysis of NaOH. The mechanism of fluorides removal was that the encapsulated fluoride particles were opened by catalytic hydrolysis to be dissolved in the solution. In this research, nitrides and fluorides were removed efficiently and synchronously. The hydrolysis residues can be used to prepare polyaluminum chloride (PAC) and ceramic materials. The hydrolysate can be prepared NH3·H2O by evaporative in alkaline solution. Then the solution without NH4 + was prepared Al(OH)3 by precipitation of adjusting pH value using HCl. And the remained liquid after removing NaAlO2 was used to prepare refining agent by evaporative crystallization. The work in this paper was beneficial for the utilization of SAD.
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Affiliation(s)
- Zhanbing Li
- School of Science, China University of Geosciences Beijing, Beijing 100083, China
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Huiquan Li
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xingzhong Huang
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Wenfen Wu
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Zhenhua Sun
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiuwen Wu
- School of Science, China University of Geosciences Beijing, Beijing 100083, China
- Corresponding author.
| | - Shaopeng Li
- National Engineering Research Center of Green Recycling for Strategic Metal Resources, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- Corresponding author.
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Preparation of Sintered Brick with Aluminum Dross and Optimization of Process Parameters. COATINGS 2021. [DOI: 10.3390/coatings11091039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Aluminum dross is produced in the process of industrial production and regeneration of aluminum. Currently, the main way to deal with aluminum dross is stacking and landfilling, which aggravates environmental pollution and resource waste. In order to find a green and environmental protection method for the comprehensive utilization, the aluminum dross was used as raw materials to prepare sintered brick. Firstly, the raw material ratio, molding pressure and sintering process were determined by single factor test and orthogonal test, and the mechanism of obvious change of mechanical strength of sintered brick was studied by XRD and SEM. The experimental results show that, the optimal formula of sintered brick is 50% aluminum dross, 37.50% engineering soil and 12.50% coal gangue. The optimum process parameters are molding pressure 10 MPa, heating rate 8 °C/ min, sintering temperature 800 °C, holding time 60 min. The samples prepared under the above formula and process parameters present outstanding performance, and the compressive strength, flexural strength and water absorption rate are 16.21 MPa, 3.42 MPa and 17.12% respectively.
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He L, Shi L, Huang Q, Hayat W, Shang Z, Ma T, Wang M, Yao W, Huang H, Chen R. Extraction of alumina from aluminum dross by a non-hazardous alkaline sintering process: Dissolution kinetics of alumina and silica from calcined materials. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 777:146123. [PMID: 33684763 DOI: 10.1016/j.scitotenv.2021.146123] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2020] [Revised: 02/01/2021] [Accepted: 02/22/2021] [Indexed: 06/12/2023]
Abstract
The aluminum dross (AD), which causes numerous problems of its management and disposal to environment is a useful resource to extract alumina. This study explains a novel process to extract highly pure alumina (Al2O3) from AD at a high extraction rate without producing the residues and exhaust gases. An experimental set up was designed to perform the grinding of AD for the decomposition of aluminum nitride (AlN) and the removal of salts. Thereby, the desalted dross was used to detect the optimum alkaline (NaOH) calcination parameters and leaching conditions, as well as the dissolution kinetics of alumina and silica. The leaching residues were used to produce Ettringite mineral with calcium-based compounds (including CaO and CaSO4) to avoid the problems of solid waste disposal from the leaching process. Moreover, to purify the alumina, slightly soluble CaSO4 was added in leaching solution to precipitate silicate and the optimum additive/solution ratio (g/mL) was determined. The aluminum hydroxide (Al(OH)3), precipitated after the carbonization was calcinated at 900.0 °C for 2 h to produce γ-alumina. The morphological and mineralogical characterizations of AD, γ-Al2O3 and the synthesized Ettringite mineral were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and X-ray fluorescence (XRF). It was observed that activation temperature of 1000.0 °C, Na2O/Al2O3 molar ratio of 1.4, leaching temperature of 60.0 °C, leaching time of 40.0 min, and the leaching liquid/solid ratio (mL/g) of 25/1 were the optimal parameter conditions to extract alumina with the extraction rate at 86.7% and purity of more than 98%. The results of leaching kinetics' study showed that the dissolution of alumina and silica were both controlled by layer diffusion process with the apparent activation energy of 11.4010 kJ·mol-1 and 2.0556 kJ·mol-1, respectively.
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Affiliation(s)
- Liuqing He
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Lin Shi
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China.
| | - Qizhen Huang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Waseem Hayat
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China; Guangdong Provincial Key Laboratory of Atmospheric Environment and Pollution Control, South China University of Technology, Guangzhou 510006, PR China
| | - Zhongbo Shang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Tengfei Ma
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Min Wang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Weidong Yao
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Haoyong Huang
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
| | - Rui Chen
- School of Environment and Energy, South China University of Technology, Guangzhou 510006, PR China; The Key Lab of Pollution Control and Ecosystem Restoration in Industry Clusters, Ministry of Education, South China University of Technology, Guangzhou 510006, PR China
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Shen H, Liu B, Ekberg C, Zhang S. Harmless disposal and resource utilization for secondary aluminum dross: A review. THE SCIENCE OF THE TOTAL ENVIRONMENT 2021; 760:143968. [PMID: 33341624 DOI: 10.1016/j.scitotenv.2020.143968] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 11/11/2020] [Accepted: 11/13/2020] [Indexed: 06/12/2023]
Abstract
Secondary aluminum dross (SAD) is solid waste of primary aluminum dross extracted aluminum, which contains approximately 40-60 wt% alumina, 10-30 wt% aluminum nitride (AlN), 5-15 wt% salts and other components. The salts include sodium chloride, potassium chloride and fluorine salts. SAD has dual attributes as resource and pollutant. SAD landfill disposal has the disadvantages of occupying land, wasting resources, a high cost and great environmental impact. SAD utilization methods are currently pyrometallurgy and hydrometallurgy. In pyrometallurgy, AlN is oxidized and the salts are evaporated at high temperature. After mixing, molding and calcination, firebricks and ceramics can be manufactured from SAD. In hydrometallurgy, AlN is hydrolyzed and salts are dissolved in water. After dissolving, filtrating, precipitating, washing and calcination, γ-Al2O3 can be prepared from SAD. Resource consumption and emission from both utilization methods were assessed. A ton of magnesium aluminum titanate based ceramics by pyrometallurgy consumes 1043 kg raw materials and releases 69 kg of waste gas, 4.17 t of waste water and no solid waste. A ton of γ-Al2O3 by hydrometallurgy consumes 3389 kg raw materials and releases 111 kg of waste gas, 12.98 t of waste water and 267 kg of solid waste. Therefore, the resource consumption and emission of SAD utilization by pyrometallurgy is lower than that by hydrometallurgy. We should focus on reducing the emission of the three wastes from pyrometallurgy. We are sure that SAD can be utilized for glass ceramics by pyrometallurgy. AlN and salts can be transformed into alumina and glass phases at high temperature with no emission. We should clarify mechanisms for SAD composition adjustment to lower the glass ceramics' melting point, AlN and salts transformed into alumina and glass phases respectively, and nucleation and crystal growth of glass ceramics at high temperature.
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Affiliation(s)
- Hanlin Shen
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PR China
| | - Bo Liu
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PR China
| | - Christian Ekberg
- Nuclear Chemistry Industrial Material Recycling, Department of Chemistry and Chemical Engineering, Chalmers University of Technology, Gothenburg 41296, Sweden
| | - Shengen Zhang
- Institute for Advanced Materials and Technology, University of Science and Technology Beijing, Beijing 100083, PR China.
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Wan B, Li W, Sun W, Liu F, Chen B, Xu S, Chen W, Yi A. Synthesis of Cryolite (Na 3AlF 6) from Secondary Aluminum Dross Generated in the Aluminum Recycling Process. MATERIALS (BASEL, SWITZERLAND) 2020; 13:E3871. [PMID: 32887240 PMCID: PMC7503661 DOI: 10.3390/ma13173871] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2020] [Revised: 08/25/2020] [Accepted: 08/27/2020] [Indexed: 11/17/2022]
Abstract
Secondary aluminum dross (SAD) is regarded as a solid waste of aluminum recycling process that creates serious environmental and health concerns. However, SAD can also be used as a good source of aluminum, so that utilizing the SAD for the production of valuable products is a promising approach of recycling such waste. In the present work, a novel eco-friendly three-step process was proposed for the synthesis of cryolite (Na3AlF6) from the SAD, and it consisted of (1) water-washing pretreatment of SAD, (2) extraction of Al component via pyro-hydrometallurgy, including low-temperature alkaline smelting, water leaching and purification of leachate in sequence, (3) precipitation of cryolite from the purified NaAlO2 solution using the carbonation method. By analysis of the parameter optimization for each procedure, it was found that the maximum hydrolysis efficiency of aluminum nitride (AlN) in the SAD was around 68.3% accompanied with an extraction efficiency of Al reaching 91.5%. On this basis, the cryolite of high quality was synthesized under the following optimal carbonation conditions: reaction temperature of 75 °C, NaAlO2 concentration of 0.11 mol/L, F/(6Al) molar ratio of 1.10, and 99.99% CO2 gas pressure, and flow rate of 0.2 MPa and 0.5 L/min respectively. The formation of Na3AlF6 phase can be detected by XRD. The morphological feature observed by SEM revealed that the as-synthesized cryolite had a polyhedral shape (~1 μm size) with obvious agglomeration. The chemical composition and ignition loss of the as-synthesized cryolite complied well with the requirements of the Chinese national standard (GB/T 4291-2017).
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Affiliation(s)
- Bingbing Wan
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523000, China; (B.W.); (W.S.); (B.C.); (A.Y.)
- School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
- Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, Guangzhou 510640, China;
| | - Wenfang Li
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523000, China; (B.W.); (W.S.); (B.C.); (A.Y.)
| | - Wanting Sun
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523000, China; (B.W.); (W.S.); (B.C.); (A.Y.)
- School of Materials Science and Engineering, Xi’an Jiaotong University, Xi’an 710049, China
| | - Fangfang Liu
- Department of Electromechanical Engineering, Guangdong University of Science and Technology, Dongguan 523083, China;
| | - Bin Chen
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523000, China; (B.W.); (W.S.); (B.C.); (A.Y.)
| | - Shiyao Xu
- Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, Guangzhou 510640, China;
| | - Weiping Chen
- Guangdong Key Laboratory for Advanced Metallic Materials Processing, South China University of Technology, Guangzhou 510640, China;
| | - Aihua Yi
- School of Materials Science and Engineering, Dongguan University of Technology, Dongguan 523000, China; (B.W.); (W.S.); (B.C.); (A.Y.)
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