Effect of limestone and dolomite tailings’ particle size on potentially toxic elements adsorption

Abstract

The aim of the study is the investigation of potentially toxic elements adsorption on limestone, dolomite and marble particles of different size. As parameters, rock particle size, solution concentration, contact time and presence of other elements in the solution have been investigated. Four fractions with different particle size (−4mm + 1mm, −1mm + 315μm, −315μm + 90μm, <90μm) have been studied. Batch experiments have been carried out at 20, 60, 120 min from monoelement and competitive Cd, Cu, Pb, Zn solutions at concentrations 5, 100, 500 mg/L, whereas fixed bed conditions have also been applied. In lower concentrations, adsorption reaches equilibrium after 60 min. 15% difference in Pb adsorption and 15-30% in Zn adsorption has been observed depending on particle size. However, according to Taguchi method particle size has not proven a determinative parameter, so as to make grinding and/or sieving necessary for their further utilisation. Cd and Zn adsorption from a competitive solution is lower, whereas Cu and Pb adsorption is similar. Adsorption capacity of materials rises up to 0.03 mg Cd/g, 0.60 mg Cu/g, 0.03 mg Pb/g, 0.60 mg Zn/g. In fixed bed conditions more than 93% element is adsorbed, of which only 4% is leached.

Keywords

• limestone
• dolomite
• marble
• potentially toxic element
• adsorption capacity
• particle size