EARTH

[2801-14-13] Using flotation waste and neutralization sludge from copper smelting as one-part replacement of cement binder to solidify/stabilize arsenic-containing sludge

Degang Liu¹, ○Xiaobo Min^1,2, Yong Ke^1,2, Liyuan Chai^1,2, Yanjie Liang^1,2, Yuancheng Li¹, Liwei Yao¹, Zhongbing Wang¹ (1. Central South University, 2. Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution)

Chairman：Dodbiba Gjergj（University of Tokyo）, Shuji Owada (Waseda University)

Keywords:stabilization/solidification, arsenic-containing sludge, heavy metals, cement clinker

This work investigated the utilization of flotation waste of copper slag (FWCS) and neutralization sludge as one-part replacement of cement binder to treat arsenic-bearing gypsum sludge produced by lime-ferrate process from copper smelting industry. The binder ratio (mass ratio of m(FWCS)-m(neutralization sludge)-m(cement clinker)) was determined to be 40: 10: 50 according to the optimal experiments. When the binder was mixed with arsenic-bearing gypsum sludge with a mass ratio of 5:5, the unconfined compressive strength (UCS) of matrix can reach 11.06 MPa after curing 28 days, which meets the required UCS level of MU10 brick in China. At the same time, the heavy metals concentrations in leachate from matrix were all below the limit of China standard leaching test (CSLT). The Cu, Zn, Cd, Hg, Be, Ni, and Se were not detected, and the concentrations of As and Pb were 1.36 and 1.01 mg/L, respectively. Therefore, the matrices had a potential to use as brick in industrial construction.