Sequestration of carbon dioxide in red mud

Acid transformation of bauxite residue: Conversion of its alkaline characteristics

“…Raising demand for alumina worldwide has increased the rate of bauxite residue production. Globally, the accumulative storage of bauxite residue has arrived at over 4 billion tons, and is still rapidly increasing [6][7][8], and as yet there is no economic alternative to landfill [9][10][11][12][13]. Therefore, almost all bauxite residue continues to be stored indefinitely in bauxite residue disposal areas (BRDAs) [14,15], which require on-going efforts to manage the waste and lower its potential to contaminate water, occupy land and disturb the surrounding ecology [16][17][18][19][20][21][22].…”

“…Use of CO2 would also reduce the emission of industrial carbon dioxide, which could create an additional benefit. However, the conversions of sodalite and cancrinite are small, and components of these alkaline substances in bauxite residue can't be neutralized by CO2 [10,46]. …”

Bauxite Residue Safety Disposal and Possibilities to Further Utilization. Part 1. Acid Soils Remediation

“…From thenceforth, the factory accumulated a good experience in processing this type of bauxite and started some projects carried out in its laboratory or in cooperation with other Romanian research -8 -Gheorghe Dobra, Laurentiu Filipescu… Bauxite Residue Safety Disposal and Possibilities to Further Utilization… institutes, trying to find new applications for the well characterized bauxite residue (bauxite residue chemical/mineralogical analysis and physical properties, new measurements of radioactivity, heavy metal content, composition and properties of the minimal processed bauxite residue at the disposal site location, and toxicity/irritation and dermal corrosivity thresholds) [1]. Many studies underlined that the bauxite residue application to any soil is very effective for reducing the phosphorous leaching, improving the pasture growth, ameliorating the soil acidity, increasing the plant metal sorption and decreasing the soluble metals concentration, and above all, the bauxite residue reduces the heavy metals availability [2][3][4][5][6][7]. But, the acid soil rehabilitation with bauxite residue is not just a simple problem of mixing and dispersing.…”

“…It should be avoided the pH values above 8.5-9.0 (promoting some larger increases in the concentrations of aluminium, vanadium and arsenic), as well as the low organic carbon and high clay content (promoting the heavy metal mobilization). This is the reason for the bauxite residue association with other materials rich in organic carbon [1][2][3][4][5][6][7].…”

“…It should be avoided the pH values above 8.5-9.0 (promoting some larger increases in the concentrations of aluminium, vanadium and arsenic), as well as the low organic carbon and high clay content (promoting the heavy metal mobilization). This is the reason for the bauxite residue association with other materials rich in organic carbon [1][2][3][4][5][6][7].Researches concerning the uses of bauxite residue in agriculture could be classified according to their disclosed specific purposes into two main groups: a) deep reshaping of the bauxite residue composition, capping and revegetation; b) change of the soils chemistry by bauxite residue metal immobilization and acid soils remediation. The common strategies for reaching these purposes are including: amendments of gypsum for reducing pH, balancing the sodicity, alkalinity, aluminum toxicity and improving porosity, and amendments of sand, clay or other materials for changing the water holding capacity of bauxite residue, Also, amendments of organic and inorganic fertilizers, supplied for providing minimal mineral nutrition and amelioration of C/N ratio are highly required.…”