How to Recover Gold from Low-Grade Gold Ore?

Low-grade gold ore features sparse gold distribution and low gold content. Direct smelting is uneconomical, so beneficiation routes must be selected according to mineral composition, gold occurrence and ore permeability to balance recovery rate and operation cost.

The first step is crushing and grinding. Raw ore is crushed and ground to liberate fine gold particles from gangue minerals. For free-milling low-grade gold oxide ore with coarse gold grains, gravity separation is a preferred option. Equipment such as jigs and shaking tables can pre-enrich gold with low reagent consumption, often used as a pre-concentration unit combined with other processes.

Flotation is widely adopted for low-grade sulfide gold ore with fine disseminated gold. By adding collectors and frothers, gold-bearing sulfide minerals are separated into gold concentrate. The concentrate can then go into CIL/CIP cyanidation leaching for further gold extraction. This combined flotation-leaching route cuts the volume of material entering the leaching system and reduces reagent cost.

Heap leaching is the most cost-effective solution for large-tonnage, porous low-grade oxide gold ore. After crushing or agglomeration, ore is stacked on an impermeable pad and sprayed with lixiviant. Gold dissolves into pregnant solution, then recovered via carbon adsorption and electrowinning. It requires less investment and infrastructure, suitable for remote mines.

For refractory low-grade gold ore where gold is locked in pyrite or arsenopyrite, pre-treatment including bio-oxidation, pressure oxidation or roasting is necessary before leaching. Without pre-treatment, gold cannot be exposed to lixiviants and recovery will stay very low.

Ore mineralogy test is the premise of process selection. A single method rarely meets targets. Many mines adopt combined flowsheets: gravity pre-concentration + flotation, flotation concentrate cyanidation, or heap leaching for waste ore and marginal ore. Customized EPC design helps mines unlock economic value from low-grade gold resources.