1. Classification of Gold-Copper Ores and Corresponding Beneficiation Processes
2. Considerations and Operational Methods for Cyanidation-Flotation Processes in Gold-Copper Ores
3. Comparative Analysis of Three Flotation Processes for Gold-Copper Ores
4. Re-Flotation of Tailings from Gold-Copper Beneficiation Equipment
5. Optimization of Reprocessing Flotation Tailings from Gold-Copper Ores
Gold-copper ores are divided into sulfide and oxide types, each requiring different beneficiation methods due to their distinct properties.
In sulfide ores, the primary metallic minerals are chalcopyrite and pyrite, with minor minerals including arsenopyrite, pyrrhotite, chalcocite, and bornite. Gangue minerals include quartz, sericite, and plagioclase. Gold is closely associated with chalcopyrite and also occurs in pyrite and other sulfides, with minimal presence in gangue. The main method for processing these ores is flotation to produce a mixed concentrate of gold, copper, and sulfur, which is then separated by flotation to obtain gold-copper and gold-sulfur concentrates. The gold-copper concentrate is sent to a smelter for comprehensive recovery, while the gold-sulfur concentrate can be cyanide leached and then smelted to recover gold. If the gold particle size is coarse, mercury amalgamation and gravity separation can be added before flotation to recover coarse gold.
Gold-copper oxide ores contain iron hydroxide and copper oxide minerals, making them difficult to process. When using a flotation-cyanidation combined process, the flotation recovery of gold-bearing iron hydroxide is challenging, and copper minerals affect cyanidation, resulting in poor recovery. A combined beneficiation and smelting process is preferred: first, recover gold-bearing sulfides by flotation, then use different reagents to recover copper oxides and gold-coated surfaces, and finally, acid leach to recover cleaned copper and gold-bearing sulfides.
Copper minerals associated with gold, except for a few like chalcopyrite and chrysocolla, have high solubility in cyanide solutions. Soluble copper competes with gold for cyanide and oxygen, hindering gold dissolution. Therefore, beneficiation equipment should adjust the process based on the copper content in the ore.
For ores with low soluble copper content, cyanide consumption can be increased if economically feasible. Operations should be conducted at lower temperatures and cyanide concentrations, as copper dissolution rates increase with higher temperatures and cyanide concentrations. Segmental addition of cyanide helps control dissolution rates, ensuring gold recovery while minimizing cyanide consumption.
Preferential flotation process: Sequentially produces gold-copper concentrate, iron sulfide concentrate, and tailings.
Mixed flotation process: More likely to produce discarded tailings compared to the preferential process.
Iso-flotation process: Separates easy-to-float gold-sulfides from difficult-to-float gold-sulfides.
Each process requires different conditions due to varying floatability. For difficult-to-float gold-sulfides, increased collector dosage ensures thorough recovery. During separation flotation of mixed concentrates, only small amounts of depressants are needed as easy-to-float pyrite particles are already absent. The iso-flotation process requires more equipment than the other two but offers high flotation indices and reduced reagent consumption.
To fully utilize gold-copper resources, various leaching methods can be applied to tailings for comprehensive recovery. For instance, using dilute sulfuric acid to leach copper, followed by iron replacement to obtain sponge copper, with the resulting copper-depleted residue cyanide leached for gold. This method is also applicable for treating gold-copper concentrates.
For ores with high copper content (e.g., >0.3%), where cyanide consumption is economically unfeasible, flotation can be used to obtain copper concentrate, followed by cyanidation of the tailings for gold recovery.
To increase the value of reprocessed flotation tailings, three trials were conducted: industrial roughing tests on fixed chutes, laboratory re-grinding and flotation tests of rough concentrate, and laboratory re-grinding and full-slime cyanidation leaching tests of rough concentrate. The results suggest two options for reprocessing: chute roughing followed by flotation, or chute roughing followed by cyanidation. The former increases grinding and flotation costs, while the latter increases grinding and leaching costs. The optimal process should be determined through detailed economic and technical comparison. The beneficiation plant should use targeted special collectors to improve flotation recovery rates based on a single-stage grinding-flotation process.
Y&X Beijing Technology Co., Ltd. specializes in efficient, eco-friendly reagents for metal and non-metal ore beneficiation. With extensive experience in ores like copper, molybdenum, gold, silver, lead, zinc, nickel, magnesium, cobalt, palladium, bismuth, fluorite, and phosphate, we offer customized, advanced solutions to maximize your benefits. Committed to providing one-stop beneficiation services, we look forward to a successful partnership with you.