Waste slag from lignite combustion as an adsorbent for the removal of ethyl xanthate from wastewater of the flotation plant for copper ore and precious metals processing in Bor

The waste slag generated from lignite combustion at Valjevo heating plant and Kostolac thermal power plant represents a serious ecological hazard, therefore, it is crucial to find its new utility value and return it into the reuse streams in accordance with circular economy concepts. This study examines two types of waste slags as potential adsorbents for removal of ethyl-xanthate from industrial wastewater [1–3]. Samples of wastewater were obtained from the Bor copper mine flotation tailings. Quantity of 10 mg waste slag was added to 50 cm3 of wastewater sample for each of the waste slag types. Adsorption was observed during a period of 24 h at 25 °C at pH 10. As a reference sample, an aqueous solution of ethyl – xanthate was used, at a fixed concentration of 21 mg/dm3 for both types of waste slag as adsorbents. The obtained results showed that both waste slags are suitable for ethyl - xanthate removal from copper mine tailings. Given their respective removal efficacies of 75 % (slag from Valjevo) and 81.5% (slag from Kostolac) during 24 h, it was concluded that waste slag from Kostolac power plant was a more efficient adsorbent for ethyl – xanthate removal from flotation tailings. It was noted, that both types of waste slag were efficient adsorbents for ethyl – xanthate removal where 250 g of waste slag succeeded in purifying about 1000 liters of mine wastewater. Therefore, we suggest both types of waste slag are suitable materials for ethyl – xanthate removal.