Romanian Journal of Ecology & Environmental Chemistry
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Short review on mechanical activation in non-metallurgical alumina production


Authors: LIDIA KIM, GHEORGHE DOBRA, RALUCA ISOPESCU, SORIN ILIEV, LUCIAN COTET, ALINA BOIANGIU, LAURENTIU FILIPESCU

Keywords: alumina, production, mechanical activation
https://doi.org/10.21698/rjeec.2022.206

Bauxite is the primary source for both metallurgical and non-metallurgical grades of alumina. Metallurgical alumina serves for aluminum production and non-metallurgical alumina, is used in a wide range of industrial applications, which makes it the subject of this review. The total world bauxite production is about 300m tpy, but only 10-15m tpy is estimated to be used for non-metallurgical applications. From the mined bauxite around 80-85% is processed via the Bayer alumina process to make alumina trihydrate (ATH) and further by calcination, the smelter grade alumina (SGA) for electrolytic aluminum. The rest of the crude bauxite remained to produce a range of non-metallurgical bauxite grades (refractories, abrasives, high aluminum cement, activated bauxite, alumina-based ceramic proppants, etc.). There are three main grades of non-metallurgical bauxite: Abrasive-grade bauxite used to produce abrasives; Chemical-grade bauxite used to produce aluminum chemicals, and Refractory-grade bauxite used to produce high alumina refractories. Around 1.2 million tpy of calcined bauxite is used in refractories, with a small amount also going into abrasives. Other ranges of non-metallurgical alumina grades like aluminum chemicals, low soda alumina, and activated alumina, including fillers and pigments for plastics and elastomers, special calcined alumina for ceramics, soft- and hard-burned alumina for alumina cement, calcium-aluminate cement, and mineral wool are produced from alumina trihydrate (ATH). Other uses include aluminum fluoride and zeolites.