The effect of high concentrations of calcium hydroxide in neutralised synthetic supernatant liquor.Implications for alumina refinery residues

Sara J. Palmer; Matthew K. Smith; Ray L. Frost

Journal of Industrial and Engineering Chemistry, Vol.17, No.1, 56-61, January, 2011

Sara J. Palmer, Matthew K. Smith¹, and Ray L. Frost^†

Chemistry Discipline of the Faculty of Science and Technology, School of Physical and Chemical Sciences, Queensland University of Technology, Queensland, Australia
¹Rio Tinto Alcan, Business Development & Growth, Technology and R&D, QRDC, Queensland, Australia

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The presence of calcium hydroxide in Bayer residue slurry inhibits the effectiveness of seawater neutralisation. An increase in the slurry pH, after neutralisation, is caused by the dissolution of calcium hydroxide and hydrocalumite (both components are found in the solid residue). At increased calcium hydroxide concentrations, additional hydrocalumite forms. Hydrocalumite has been found to be unstable when the solution pH is less than 10.5, releasing OH- ions and aluminium ions back into solution (pH and aluminium reversion). Through this mechanism, the concentration of calcium hydroxide in alumina refinery residues has an impact on seawater neutralisation process efficiency.

Keywords:Calcium hydroxide;Seawater neutralisation;Red mud;Reversion;Supernatant liquor

[References]

Chvedov D, Ostap S, Le T, Colloids Surf. A., 182, 131 (2001)
Hind AR, Bhargava SK, Grocott SC, Colloids Surf. A., 146, 359 (1999)
Jamialahmadi M, Muller-Steinhagen H, JOM., 50, 44 (1998)
Lin C, Maddocks G, Lin J, Lancaster G, Chu C, Aust. J. Soil Res., 42, 649 (2004)
Menzies NW, Fulton IM, Morrell WJ, J. Environ. Qual., 33, 1877 (2004)
Summers RN, Pech JD, Agric. Ecosyst. Environ., 64, 219 (1997)
Hanahan C, McConchie D, Pohl J, Creelman R, Clark M, Stocksiek C, Environ. Eng. Sci., 21, 125 (2004)
Costantino U, Marmottini F, Nocchetti M, Vivani R, Eur. J. Inorg. Chem., 10, 1439 (1998)
Frost RL, Ding Z, Kloprogge JT, Can. J. Anal. Sci. Spectrosc., 45, 96 (2000)
Frost RL, Erickson KL, J. Therm. Anal. Calorim., 76, 217 (2004)
Durrant PJ, General and Inorganic Chemistry, Longmans, London (1960)
Heslop RB, Robinson PL, Inorganic Chemistry, Elsevier, London (1961)
Palmer SJ, Frost RL, Appl. Spectrosc., 63, 748 (2009)
Palmer SJ, Soisonard A, Frost RL, J. Colloid Interface Sci., 329(2), 404 (2009)
Palmer SJ, Frost RL, Nguyen T, J. Therm. Anal. Calorim., 92, 879 (2008)
Chrysochoou M, Dermatas D, J. Hazard. Mater., 136(1), 20 (2006)

[Referenced By]

[1] Chvedov D, Ostap S, Le T, Colloids Surf. A., 182, 131 (2001)

[2] Hind AR, Bhargava SK, Grocott SC, Colloids Surf. A., 146, 359 (1999)

[3] Jamialahmadi M, Muller-Steinhagen H, JOM., 50, 44 (1998)

[4] Lin C, Maddocks G, Lin J, Lancaster G, Chu C, Aust. J. Soil Res., 42, 649 (2004)

[5] Menzies NW, Fulton IM, Morrell WJ, J. Environ. Qual., 33, 1877 (2004)

[6] Summers RN, Pech JD, Agric. Ecosyst. Environ., 64, 219 (1997)

[7] Hanahan C, McConchie D, Pohl J, Creelman R, Clark M, Stocksiek C, Environ. Eng. Sci., 21, 125 (2004)

[8] Costantino U, Marmottini F, Nocchetti M, Vivani R, Eur. J. Inorg. Chem., 10, 1439 (1998)

[9] Frost RL, Ding Z, Kloprogge JT, Can. J. Anal. Sci. Spectrosc., 45, 96 (2000)

[10] Frost RL, Erickson KL, J. Therm. Anal. Calorim., 76, 217 (2004)

[11] Durrant PJ, General and Inorganic Chemistry, Longmans, London (1960)

[12] Heslop RB, Robinson PL, Inorganic Chemistry, Elsevier, London (1961)

[13] Palmer SJ, Frost RL, Appl. Spectrosc., 63, 748 (2009)

[14] Palmer SJ, Soisonard A, Frost RL, J. Colloid Interface Sci., 329(2), 404 (2009)

[15] Palmer SJ, Frost RL, Nguyen T, J. Therm. Anal. Calorim., 92, 879 (2008)

[16] Chrysochoou M, Dermatas D, J. Hazard. Mater., 136(1), 20 (2006)