Study the Phase Changes and Formation conditions of the sodium aluminate phase in the Alkaline Roasting Process of the Bauxite under Mechanical Milling and Heating Conditions

Document Type : Original Article

Authors

• Omid Nouri Kohan
• Nader Setoudeh
• Raziye Hayati

Materials Engineering Department, Faculty of Engineering, Yasouj University, Yasouj, Iran.

10.22067/jmme.2025.90200.1166

Abstract

Mechanical milling for mixtures of Bauxite-Na2CO3 were done at different times (15 minutes, 2 and 5 h). STA analysis was undertaken with heating rate of 20 ºC/min up to 900 ºC under air atmosphere. The mass loss of bauxite was ~%13 and for bauxite-Na2CO3 mixtures was in the range of 27-30%. The isothermal heating was done at different temperatures for one hour under air atmosphere. To dissolve the sodium aluminate, leaching of the heated samples at 900 ºC was undertaken at temperature of 80 ºC for one hour with caustic soda solution (NaOH, 0.1M). The signs of the albite, boehmite and hematite were observed in XRD patterns of the milled samples, however, sodium aluminate and sodium aluminum silicate phases were detected in the heated samples. With increasing temperature and/or amount of sodium carbonate, the signs of the sodium aluminate were the prevailed phase in the products of the heated sample. Albite and hematite phases were detected in the solid residues of the leaching. The phase changes were studied in the microstructures of the samples after heating and leaching.

Keywords

• Alkaline roasting
• Aluminum oxide
• Boehmite
• Mechanical milling
• Sodium aluminate

Main Subjects

• Extractive Metallurgy

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