Scientific Gold Extraction Methods for Sulphide Gold Ore to Enhance Recovery Efficiency

High-sulphide gold ores contain significant quantities of sulphide minerals such as pyrite and arsenopyrite, exhibiting low gold grades and fine particle sizes, often encapsulated within sulphide minerals. Direct cyanide leaching proves ineffective for such ores, yielding poor gold recovery rates while increasing leaching agent consumption and production costs; consequently, this method is not recommended.

I. Flotation: The Fundamental and Flexible Core Process

Flotation serves as the standard treatment for sulphide-bearing gold ores, concentrating gold within copper, lead, or sulphur concentrates. This enables multimetal recovery while enhancing gold yield, proving economically viable for ores containing multiple base metals. In practice, flotation is frequently integrated with other processes to form combined beneficiation schemes, thereby improving investment returns.

II. Gravity Separation - Flotation Process: Addressing Co-occurrence and Unevenly Distributed Minerals

The gravity separation - flotation process is suitable for gold-bearing quartz vein ores where gold is closely associated with sulphides requiring smelting recovery, or where coarse-grained gold is unevenly distributed. The raw ore undergoes flotation to produce a concentrate. As coarse-grained gold encapsulated within sulphides in the flotation tailings is difficult to recover, gravity separation equipment such as jigs or shaking tables is employed to extract this gold, thereby improving the overall gold recovery rate.

III. Flotation - Cyanidation of Concentrates Process: An Energy-Efficient Combination

The flotation-cyanidation process is predominantly used for ores such as gold-bearing quartz veins. Using xanthates as collectors and pine oil as frothers, gold concentrate is obtained through flotation in a weakly alkaline pulp. The concentrate is then leached with cyanide, and zinc powder is used to replace the gold slime. Finally, pyrometallurgical processes yield pure gold. This process reduces the need for fine grinding of ore, lowering energy consumption and capital investment.

IV. Flotation - Roasting - Cyanidation Process: Addressing Complex Ore Challenges

The flotation-roasting-cyanidation process is suited for complex ores such as refractory gold-arsenic ores. Flotation is performed first, followed by oxidation roasting of the high-sulphur, high-arsenic flotation concentrate to remove arsenic and sulphur while loosening the roasted sand for subsequent gold and silver leaching.

V. Flotation - Concentrate Thiourea Leaching Process: Low-Toxicity Solution for Specialised Ores

The flotation-concentrate thiourea leaching process is suitable for vein gold ores containing high levels of arsenic, sulphur, and carbonaceous material. The acidic thiourea solution rapidly dissolves gold and silver with low toxicity and easy regeneration, unaffected by multiple impurities, achieving high gold recovery efficiency.

VI. Process Selection: Experimental Validation Prioritises Solution Design

Given the diverse nature of gold ores, suitable processes vary. Prior to selecting a process, mineral processing experiments must be conducted and analysed. Solutions should be customised based on scientific reports to enhance gold extraction efficiency, reduce costs, and achieve economically viable and environmentally responsible mining.