COLD-BOND AGGLOMERATION OF GOLD MILL TAILINGS FOR BACKFILL USING GYPSUM BETA-HEMIHYDRATE AND CEMENT AS LOW-COST BINDERS

Several types of binder have been studied at Laurentian University usi ng the Cold-Bond Tailings Agglomeration (CBTA) process of fine mill ta ilings. Most of these binders have been alkaline (lime, blast furnace slag cement, Portland cement, etc.). However, the application of non-a lkaline and more economical binders should be examined. Investigation of the cold-bonding ability of gypsum (beta-hemihydrate form), which i s the most common and economical form of gypsum, was the main objectiv e of this study. A drum pelletizer was used in the agglomeration proce ss to investigate the influence of varying the moisture content of the pellets, binder dosages, pellet size, and curing period on the streng th of the agglomerates. The investigation of the properties of gypsum as a binder for cold-bond agglomeration of fine gold mill tailings sho wed that the wet strength of the green pellets is strongly influenced by the moisture content. In general, green pellets achieved sufficient wet strength to withstand breakage during transportation. Also, an in crease in pellet size resulted in an increase in the strength of pelle ts. The cured pellets developed higher strength with addition of gypsu m to cement than using Portland cement alone as the binder. Therefore, as a low cost binder, gypsum (beta-hemihydrate) can be utilized econo mically in the agglomeration process of fine gold mill tailings. Since due gas desulphurisation gypsum (FGD) products are now available in t he market, it is viable to use it as a low cost binder for the CBTA pr ocess. (C) 1997 Canadian Institute of Mining and Metallurgy. Published by Elsevier Science Ltd. All rights reserved.