Abstract

STRYDOM, C.A.; MTHOMBO, T.S.; BUNT, J.R.  and  NEOMAGUS, H.W.J.P.. Some physical and chemical characteristics of calcium lignosulphonate-bound coal fines. J. S. Afr. Inst. Min. Metall. [online]. 2018, vol.118, n.12, pp.1277-1283. ISSN 2411-9717.  http://dx.doi.org/10.17159/2411-9717/2018/v118n12a6.

Low-cost calcium lignosulphonate (CL), which is a byproduct of the wood pulping industry, was investigated as a potential binder during laboratory-scale pelletization of inertinite-rich high-ash coal fines from the Highveld Coalfield of South Africa. Coal-binder mixtures containing between 1 and 15% calcium lignosulphonate were prepared, pressed, and ultimate, proximate, porosity, XRD, and XRF analyses obtained. It was found that increased pressure during pelletization results in increased attractive forces, due to increased interparticle contact areas. FTIR analysis showed that chemical interactions occur between coal fines and the binder, as evidenced by the formation of new C-O ether-type bonds. The presence of moisture during pelletization enhanced surfactant activity of the binder. Chemical interactions between the coal and the binder seem to be mainly electrostatic, driven by Ca²+ from the calcium lignosulphonate, which may act as a bridge between the anionic parts of the binder and the surface of the coal.

Keywords : Calcium lignosulphonate; coal fines; chemical interaction; binder; surfactant; porosity.

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