Sustainable and economically profitable reuse of bauxite mining waste with life cycle assessment

According to the report of Hetherington et al. (2007) the world aluminium production was 31.9 million tonnes in 2005 and the demand is still growing. Aluminium is obtained from alumina ore called bauxite. Apart from Antarctica, bauxite is mined in all continents (Schwarz and Lalík, 2012). Bauxite consists of aluminium-hydroxide minerals, such as gibbsite, boehmite and/or diaspore. After weathering aluminous silicate rock (lateritic bauxite) and less commonly carbonate rock (karst bauxite) form bauxite in mainly tropical and sub-tropical climates (Rai et al., 2012). The total amount of bauxite resources is estimated to be 55 to 75 billion tonnes distributed in different continents such as Africa (33%), Oceania (24%), South America and the Caribbean (22%), Asia (15%), and elsewhere (6%) (USGS, 2010). Although production of bauxite deceased in Guinea, Guyana, Jamaica, Russia and Suriname, new sources and expansion in Australia, China, Brazil and India partially offset the decline in global production but there remained a slight decrease in 2009 (201 million tonnes per year) compared to 2008 (205 million tonnes per year) (Rai et al., 2012; Schwarz and Lalík, 2012). Bauxites can be classified by function of the ore type. Alumina occurs in crystallographically different ways and there are three phases based on the ore type: gibbsitic (γ-Al(OH)3), boehmitic (γ-AlO(OH)) and diasporic (α-AlO(OH)). The metallurgical processes needed for alumina production depend on the mineralogical characteristics of the bauxite ore (Rai et al., 2012; Schwarz and Lalík, 2012). The bauxite residue, on a dry basis, is produced in almost a 1 to 1 kg ratio to alumina. Every tonne of alumina produced results in the production of about 1.5–2.5 tonnes of bauxite residue, but it depends on the bauxite source and alumina extraction efficiencies. Approximately 2 billion tonnes (Bt) of bauxite residue was produced by the year 2000, and it was estimated that the amount might reach the 4 Bt mark by 2015 at its current production rate (Power et al., 2009). An inventory of about 3 billion tonnes of bauxite residue wait in stockpiling yards for utilization and 120 million tonnes of bauxite residue are added every year.According to the report of Hetherington et al. (2007) the world aluminium production was 31.9 million tonnes in 2005 and the demand is still growing. Aluminium is obtained from alumina ore called bauxite. Apart from Antarctica, bauxite is mined in all continents (Schwarz and Lalík, 2012). Bauxite consists of aluminium-hydroxide minerals, such as gibbsite, boehmite and/or diaspore. After weathering aluminous silicate rock (lateritic bauxite) and less commonly carbonate rock (karst bauxite) form bauxite in mainly tropical and sub-tropical climates (Rai et al., 2012). The total amount of bauxite resources is estimated to be 55 to 75 billion tonnes distributed in different continents such as Africa (33%), Oceania (24%), South America and the Caribbean (22%), Asia (15%), and elsewhere (6%) (USGS, 2010). Although production of bauxite deceased in Guinea, Guyana, Jamaica, Russia and Suriname, new sources and expansion in Australia, China, Brazil and India partially offset the decline in global production but there remained a slight decrease in 2009 (201 million tonnes per year) compared to 2008 (205 million tonnes per year) (Rai et al., 2012; Schwarz and Lalík, 2012). Bauxites can be classified by function of the ore type. Alumina occurs in crystallographically different ways and there are three phases based on the ore type: gibbsitic (γ-Al(OH)3), boehmitic (γ-AlO(OH)) and diasporic (α-AlO(OH)). The metallurgical processes needed for alumina production depend on the mineralogical characteristics of the bauxite ore (Rai et al., 2012; Schwarz and Lalík, 2012). The bauxite residue, on a dry basis, is produced in almost a 1 to 1 kg ratio to alumina. Every tonne of alumina produced results in the production of about 1.5–2.5 tonnes of bauxite residue, but it depends on the bauxite source and alumina extraction efficiencies. Approximately 2 billion tonnes (Bt) of bauxite residue was produced by the year 2000, and it was estimated that the amount might reach the 4 Bt mark by 2015 at its current production rate (Power et al., 2009). An inventory of about 3 billion tonnes of bauxite residue wait in stockpiling yards for utilization and 120 million tonnes of bauxite residue are added every year.