(290b) Statistical Evaluation of Mineral Carbonation of a Fly Ash/Brine System
AIChE Annual Meeting
2012
2012 AIChE Annual Meeting
Accelerating Fossil Energy Technology Development Through Integrated Computation and Experimentation
Mineralization
Tuesday, October 30, 2012 - 12:50pm to 1:10pm
Muriithi N. Grace1[1] Petrik F. Leslie1, Gitari M. Wilson2 and Doucet J. Frédéric 3,
1Environmental Nano Sciences Group, Chemistry Department, University of the Western Cape,
South Africa.
2Department of Ecology and Resource Management, School of Environmental Studies,
University of Venda, South Africa.
3Industrial Mineralogy Laboratory, Council for Geoscience, Pretoria, South Africa.
Statistical evaluation of mineral carbonation of a fly ash/brine system
Abstract
As countries continue on their development path, coal is bound to play a vital role as the main source of energy especially in BRICS (Brazil, Russia, India, China and South Africa) where coal is available in considerable quantities. International regulations, specifically the 2nd Kyoto agreement reached in Durban, South Africa (28th November to 9th December 2011) binds developing countries to reduce their carbon emissions even as they industrialize. Finding alternatives to reduce CO2 emissions is going to be paramount to achieve the targets set. The effect of four parameters on the mineralization potential of class F fly ash and a NaSO4 brine type was evaluated in a statistically designed protocol. Main effects of temperature, particle size and solid to liquid (S/L) ratio were the most significant while the interactions of temperature and particle size as well as temperature and S/L ratio were also significant. Between 2.75 % to 6.5 % conversion of the CaO in fly ash into CaCO3 was achieved depending on the factor combinations. Mineral carbonation at 90 ⁰C and 4 Mpa using bulk ash and S/L ratio of 1 gave the highest degree of carbonation of 6.5 %. Carbonation conducted at 30 ⁰C and 1 Mpa using the >150 µm particle size and S/L ratio of 0.1 gave the lowest degree of carbonation of 2.75 %. Application of brine instead of ultra-pure water resulted in higher carbonation efficiency due to the utilization of the additional Ca2+ and Mg2+ present in brine. Moreover the carbonation effluents after the experiments are cleaner with regards to most elements (Pb, Zn, Cu, NO3, Na, SO4, As, Se, K, Al, Mg, Ca, Si, Sr and Ni) while Mo, B, V and Cl increased with carbonation. McNemar’s test (p-value of 0.01) of the factor combinations reveals that carbonation carried out at 90 ⁰C and 4 Mpa using bulk ash and S/L ratio of 1 has the best factor combinations as the highest removal of contaminants was achieved (≥70 %).
[1]Corresponding author; Muriithi N. Grace; Email: gmuriithi@uwc.ac.za; Tel: +27219593878;
Fax: +27219593838
See more of this Group/Topical: Topical D: Accelerating Fossil Energy Technology Development Through Integrated Computation and Experimentation