Investigating the use of sugar alcohol as an alternative non-toxic binder to conventional coal tar/coal tar pitch for use in taphole clay

Abstract

Currently, the main purpose for obtaining alternative binders for use in taphole clay is to reduce the exposure to harmful polycyclic aromatic hydrocarbons (PAH) associated with conventional coal tar (CTht) binders. Some advances have been made such as using lower-PAH alternative binders or phenolic resole resins (resin-bonded) in taphole clays. The use of non-toxic binders has become exceedingly difficult due to the versatility of CTht in taphole clay. This study investigated a combination binder system that consisted of a sugar alcohol (research-grade glycerine) and phenolic resole resin as a potential non-toxic binder for use in platinum smelting taphole clay. The binder system was characterized according to its composition by means of Fourier-transform infrared spectroscopy and the PAH content (16-EPA-PAH) was determined using targeted gas chromatography mass spectroscopy. Flow behaviour of the binder was determined based on rotational rheology, and the volatilization and rheological thermal stability of the binders were assessed by means of thermogravimetric analysis and thermorheology, respectively. The effect of mixing these binder constituents on the cross-linking behaviour of the phenolic resin was evaluated using differential scanning calorimetry. The combination binder had a higher average mass loss and lower carbon yield compared to conventional CTht, but with a lower total PAH content, making it a more health-friendly alternative.