Gold Ore Gravity Concentration, Flotation, and Cyanidation Processes

Oxidized gold ore refers to gold-bearing ore formed in the surface or near-surface oxidation zone through oxidation reactions caused by exposure to oxygen or other oxidants. Due to its complex properties, beneficiation processes need to be optimized based on the specific mineral composition. Common beneficiation methods include gravity concentration, flotation, cyanidation, and heap leaching, or a combination of methods to improve gold recovery.

Gravity Concentration of Oxidized Gold Ore

Gravity concentration is a physical beneficiation method that utilizes differences in mineral density for separation. It is often used for the pretreatment of oxidized gold ore. After crushing and grinding, the ore is separated using equipment such as shaking tables, jigs, or centrifugal thickeners to obtain gold-rich concentrate.

Flotation of Oxidized Gold Ore

Flotation is a beneficiation method that separates minerals based on differences in the physicochemical properties of their surfaces. Oxidized gold ore typically exhibits poor flotation results due to the lack of a carrier for gold particle flotation.

Cyanidation of Oxidized Gold Ore

Cyanidation is a commonly used method for extracting oxidized gold ore, particularly suitable for fine-grained, high-grade oxidized gold ore. After grinding, the ore is mixed with a cyanide solution under alkaline conditions. The gold dissolves into gold cyanide through a leaching reaction under alkaline conditions. The dissolved gold is then recovered through activated carbon adsorption or zinc precipitation.

Heap Leaching of Oxide Gold Ores

Heap leaching is a common gold extraction process used for low-grade oxide gold ores. The basic process includes heap construction, drip (spray) leaching, precious liquor collection, and gold recovery. The ore is first crushed and screened to a particle size of -10mm to -20mm, then piled on a heap leaching field lined with an impermeable membrane. Layered or sloping heaps are used to ensure good permeability, allowing the leachate to penetrate evenly and fully contact the gold ore. Subsequently, the heap is sprayed with a cyanide solution or dilute sulfuric acid, causing the gold to dissolve and permeate to the bottom of the heap through the leachate. The gold-bearing solution is collected through a collection system, and then gold is extracted from the solution using activated carbon adsorption. Gold is then recovered through desorption and electrolysis.