At the increasing demand both in China and abroad, many alumina plants have sprung up in China in recent years. The total production of alumina in China added up to 13.7 million tons in 2006 which had increased 60% compared with that of in 2005^[1]. China ranked the second place among alumina production countries in the world following Australia. Red mud is generated as solid waste in the production of alumina by alkaline leaching process of bauxite. In general, 1-1.5 tons of red mud will be produced with each ton of alumina production. And there are approximately 15 million tons of red mud produced in China every year.

Red mud characterizes to be of high alkalinity, so it can cause serious environment problems. Alkaline solution and red mud slurry usually seep from the red mud stockyard or pipelines into ground or underground water. Vast areas of land are required for the storage of red mud, which may cause the reduction of farming land. And the building and maintenance of red mud dam need a lot of money. An alumina plant in Shandong province, China, used to spend 70 million Yuan on a red mud hill ^[2].

Characteristics of red mud differ from different processes of alumina production ^[3]. Red mud from sinter process, containing some reactive substance such as β-2CaO•SiO₂, can be used to produce building materials directly ^{[2, 4, 5]}. However in Bayer process, Al₂O₃ is dissolved depending on sodium hydroxide from high-iron, high-aluminum boehmite and gibbsite bauxite without calcination. Thus there is less reactive substance in the Bayer red mud. It is not feasible to use red mud from Bayer process as that from calcination process.

[1]     National Bureau of Statistics of China, National economic and social development statistical bulletin P. R. China in 2006. Available at: http://www.stats.gov.cn/tjgb/ndt jgb/qgndtjgb/ t20070228_402387821.htm, 2007.

[2]     J.K. Yang, C. Fan, J. Hou, B. Xiao, W. Liu, Engineering application of basic level materials of red mud high level pavement, Chin. Mun. Eng. 123 (2006) 7-9.

[3]     Y. Liu, C.X. Lin, Y.G. Wu, Characterization of red mud derived from a combined Bayer Process and bauxite calcination method, J. Hazard. Mater. (2007), doi:10.1016/j.jhazmat.2006.12.015

[4]     G. Xing, J.K. Yang, J. Hou, B. Xiao, Study on compositions of raw materials of the non-fired brick made from red mud and fly ash, Light. Met. 3(2006) 24-27.

[5]     P.X. Zhang, R.Y. Lin, J.Q. Yan, Making glass-ceramics using red mud as raw materials, Nonfer. Metals. 52(4) (2000) 77-79.