Environmental Effects and Reduction of Cement Usage During the Mechanical Activation Procedure for Residue Based Sulphatic Tailings Treatment

The huge sector for hazardous solid waste is sulfuric mine tailings, which are highly toxic heavy metal -containing waste. Improper treatment of tailings can lead to heavy metal transfer emissions into the environment and acid mine drainage. Therefore, mechanical activation was employed in this study to successful immobilization of heavy metals and repurpose a mixture of carbon tailings (T_P) and sulphate tailings (T_A) for concrete construction. Based on the test for toxic behaviour in the samples, leachate test was carried out and it results in less leachate rate than the permitted rate. The procedure to conduct leachate was called as Toxicity Characteristic Leachate procedure (TCLP). In the porosimeter test, the result of the surface area was increasing, and the porosity was decreasing respectively. In the 20% sample of activated tailing replaced with cement, the diameter of the pore after 28 days of curing was 60nm and this was very less than the critical diameter which was 150nm and the compressive strength was 31.2 MPa. The ettringite and the Ca, Si hydration gel was needed to stabilize the metal pollutant, and it was shown by XRD and SEM results. Overall, in this research, the combined tailings which was activated mechanically could replace 40% of the cement to make concrete samples. Aside from reducing cement consumption, the combined approach used resulted in a reduction of the negative impact of sulphide content in concrete samples.