Desulfurisation and ash reduction of pyrolysis carbon black from waste tires by combined Fe3+oxidation-flotation

The recycling of valuable carbon black (CB) of pyrolysis carbon black (CBp) from waste tires is important considering the conservation of secondary resources and the alleviation of potential hazardous effects on envi-ronment, but the high ash content hinders the high-value utilisation of CBp. In this work, the ash reduction and desulfurisation of CBp were studied using Fe3+ in acid medium and flotation. The effects of different operating factors on the quality improvement of carbon black were investigated, and the properties of the products were analysed with morphology and phase characterisation technology. The Fe3+ leaching results show that 90.27% yield and 11.53% ash content of clean CB were obtained when the leaching temperature of 25 degrees C, leaching time of 150 min, pulp density of 250 g/L, and Fe3+ concentration of 99 kg/t. Then, flotation results show that 79.96% yield of clean carbon black and 9.14% ash content for flotation concentrate under the optimum flotation con-ditions: 25 g/L pulp density, 2,500 g/t collector, 1,000 g/L frother, and 0.25 m3/h aeration rate. In this study, minerals such as ZnS, SiO2 and CaCO3 were effectively removed. The results show that desulfurisation and ash reduction of CBp were achieved with Fe3+ leaching and floatation.