Mineral transformation in treating low-grade bauxite using the calcification–carbonization process and preparing cement clinker with the obtained residue. (July 2019)

• Record Type: Journal Article
• Authors: Wang, Yanxiu; Zhang, Ting-an; Zhang, Yuhai; Lyu, Guozhi; Zhang, Weiguang
• Is Part Of: Minerals engineering. Volume 138(2019)
• Page Start: 139
• Page End: 147
• Publication Date: 2019-07
• Subjects: Mineral transformation -- Bauxite residue -- Calcification–carbonization process -- Low-grade bauxite; Mines and mineral resources -- Periodicals; Ressources minérales -- Périodiques; Mines and mineral resources; Periodicals; Electronic journals; 622
• DOI: 10.1016/j.mineng.2019.04.031
• Languages: English
• ISSNs: 0892-6875

Abstract

Highlights: A novel C-C process was used to deep extract alumina from low-grade bauxite. A near-neutral C-C residue with high Ca and low Al was obtained to prepare cement clinker. The mineral transformation in alumina extraction and clinker preparation was studied. The combined method realizes the efficient production of alumina and zero discharge. Abstract: During the Bayer process for alumina production, the molecular formula of the bauxite residue is approximately equivalent to Na2 O·Al2 O3 ·1.7SiO2 · n H2 O. This means that 1 kg of SiO2 in bauxite will produce 1 kg of Al2 O3 and 0.608 kg of Na2 O in bauxite residue. Thus, the extraction efficiency of alumina is low when processing low-grade bauxite. In addition, it is difficult to utilize bauxite tailings with solid alkali in the structure. In this study, low-grade bauxite was treated using a calcification–carbonization process. A new type of residue (C-C residue) with a different structure from that of traditional bauxite residue was obtained. A cement clinker was prepared with C-C residue as the main ingredient at a dosage of 50%. The experimental results show the alumina extraction efficiency reached 75.82% when processing low-grade bauxite of A/S 3.06 using the calcification–carbonization process. This is higher than the 61.44% of the Bayer process. The main phases of C-C residue [CaCO3, amorphous Ca(4−2x) Six O4, and undecomposed Ca3 Al2 (SiO4 )(OH)4 ] convert into Ca2 SiO4, Ca3 SiO5, and Ca2 Fex Al(2−x) O5 after calcination. The calcification–carbonization process combined with cement production helped low-grade bauxite achieve highly efficient and clean alumina production, which is conducive to the sustainable development of alumina industry.