Laboratory Rinsing Behaviors of Spent Ores.
Dix-RB; Comba-PG; McGill-SL
Proc 2nd Int'l Conf on Env Issues & Mgmt of Waste in Energy & Min Prod Balkema PP 917-24 :917-24
Environmental regulations have been adopted in recent years by gold- producing states requiring the rinsing of spent heaps to remove residual cyanide. The final heap rinse effluents must meet criteria for ph, cyanide, and metals content. Laboratory column rinsing studies on three different ore types were conducted by the U.S. Bureau of Mines. Rinse profiles for cyanide as a function of volume of rinse solution passed through the spent ore are presented. Fresh water rinsing of two agglomerated ores at flowrates between 0.003 and 0.010 Gal/min.Ft2 of ore surface showed the cyanide removal was independent of the rinse solution application rate during the initial phases of rinsing. Use of a chemical oxidant to destroy cyanide in the rinse effluents with recycle of the neutralized solution reduced the volume of waste solution generated. Recycle of untreated rinse effluents reduced the volume of waste solution generated through natural degradation of cyanide but the volume of solution recycled to the ore was approximately three times the volume of fresh water required to obtain the same concentration of cyanide in the effluent solutions. The volume of fresh water required per metric ton of ore in a 20-foot laboratory column test to meet cyanide detoxification criteria was approximately 50 pct of the volume required per metric ton of ore in a 6-foot laboratory column test conducted at the same flowrate on the same ore.
Proc 2nd Int'l Conf. on Env. Issues & Mgmt of Waste in Energy & Min. Prod., Balkema, PP. 917-24