Comparison of CO2 capture by ex-situ accelerated carbonation and in in-situ naturally weathered coal fly ash

https://repository.up.ac.za/bitstream/handle/2263/16641/Mahlaba_Physical%282011%29.pdf?sequence=1&isAllowed=y

Physical, chemical and mineralogical characterisation of hydraulically disposed fine coal ash from SASOL Synfuels

Evaluation of workability and strength development of fly ash pastes prepared with industrial brines rich in SO4= and Cl− to expand brine utilisation

Chemical, mineralogical and morphological changes in weathered coal fly ash: A case study of a brine impacted wet ash dump

https://repository.up.ac.za/bitstream/handle/2263/16640/Mahlaba_Effect%282011%29.pdf?sequence=1

Effect of fly ash characteristics on the behaviour of pastes prepared under varied brine conditions

Sasol, a global petrochemical player uses large quantities of coal, steam and oxygen as feedstock for the production of fuels and chemicals. Inevitably, large amounts of waste products are generated such as coal combustion residues (ash) via coal gasification as well as brines via demineralization, desalination and evaporation processes. Sasol Technology Research and Development is currently investigating the concept of brine (high strength inorganic salt solutions) encapsulation with the use of coal gasification ash. The process will involve reacting inorganic salts with the coal mineral matter under thermal conditions to form stable compounds, potentially resulting in an environmentally safe brine disposal option. Laboratory-scale experiments investigated brine addition at 3.5% (m/m) and 29% (m/m) to coarse gasification coal ash (with and without CaO addition). These samples were sintered at 700 °C for 30 or 60 mins. Selected ash residues from laboratory-scale brine gasification simulations were subjected to water leaching tests to determine the leachate properties, the extent of salt stabilisation achieved as well as the influence that CaO addition on inorganic salts encapsulation. The results of this study indicated that some of the ionic species in the brine were encapsulated and the addition of CaO improved stabilization.

Karl-Heinz J. Riedel

Papers

Leachate Characteristics of Ash Residues from a Laboratory-Scale Brine Encapsulation Simulation Process