COLD-BOND AGGLOMERATION OF REACTIVE PYRRHOTITE TAILINGS FOR BACKFILL USING LOW-COST BINDERS - GYPSUM BETA-HEMIHYDRATE AND CEMENT

The Cold-Bond Tailings Agglomeration (CBTA) technique was first presen ted by Amaratunga and Annor (1989) for agglomeration of the fine fract ion of tailings, allowing total utilization of tailings as backfill an d other products. The main objective of the CBTA technique is to reduc e or eliminate the surface impoundment of tailings. Surface disposal o f reactive pyrrhotite tailings with high iron sulphide composition, wh ich are commonly produced in Sudbury mining operations will lead to ox idation in the presence of air and water resulting in Acid Mine Draina ge (AMD). Therefore, for environmental and economic reasons, surface i mpoundment of pyrrhotite tailings should be avoided. The CBTA process has also been proven effective in controlling AMD using alkaline addit ives such as portland cement, fly ash and bactericides. The removal of industrial SO2 by the Flue Gas Desulphurization (FGD) process produce s gypsum beta-hemihydrate (CaSO4 1/2H(2)O) as a waste by-product, whic h may also be used as a non-alkaline binder. This paper will outline t he investigation of the agglomeration of fine reactive pyrrhotite tail ings for backfill employing Portland cement and gypsum beta-hemihydrat e as low cost binders. The study showed that the development of an opt imum cold-bonded pyrrhotite tailings pellet with Portland cement and G ypsum beta-hemihydrate as binder depends on the fracture load of the c ured pellet, availability and cost of Gypsum beta-hemihydrate.