Purification of talcs by chlorination and leaching

The use of chlorine in talcs deferrication has been studied in four samples taken from the province of Mendoza, Argentina. The techniques used in this process were thermogravimetry (TG), X-ray fluorescence (XRF), X-ray diffraction (XRD) and CieLab colorimetry. Experimental results show that the pyrometallurgical process of chlorination is an efficient method for removing Fe2O3 from talc, by volatilizing it as FeCl3. Previous leaching of the sample with HCl 10% (w/w) produced the elimination of carbonates, and a slight iron removal. Quantitative elimination of iron, both in untreated samples and leached ones, was made by chlorination with chlorine gas 1:1 in nitrogen, at temperatures over 800 °C. Experimental results show that deferrication can remarkably improve mineral coloration.

► The use of chlorine in talcs deferrification was studied.
► A thermogravimetric system able to work in Cl2 atmosphere was used.
► The techniques used in this process were TG, XRD, XRF and CieLab colorimetry.
► The process of leaching removes carbonates, and only small amounts of iron.
► The process of chlorination efficiently removes iron from talc.