How to Recover Gold From Refractory Gold Ore?

01Dry grinding-roasting method to recover gold

For ores that are difficult to separate because they contain organic carbon, roasting as a pretreatment operation before cyanidation can achieve a higher gold recovery rate.

This process is used for ores and concentrates containing pyrite, arsenic pyrite and cyanides. Roasting oxidizes sulfides and eliminates carbonaceous matter (through combustion). This single-stage oxidation process is also suitable for existing co-current cyanidation and carbon adsorption processes.

The fine particle size required for grinding and the high clay content of some ores prove that filtration of ground slurry is uneconomical. Therefore, dry grinding was chosen for roasting feed preparation. Using this process to pretreat refractory ores is economically and environmentally feasible. A certain gold mine uses a dry ball mill for dry grinding. The hot air required comes from the oil combustion chamber and is supplemented by the waste heat of the boiling roaster, which can save fuel costs every year.

02Flash roasting method to recover gold

While gold ore or gold concentrate roasters currently use airflow and circulating ebullated beds, the flash roasting principle has also been proposed as a more cost-effective method for large-scale gold ore roasting. The flash roasting process has been used in the mineral industry to calcine cement, phosphate, alumina and limestone.

In the flash roaster, the hot combustion airflow enters the bottom of the satin burning chamber through the throat, and the raw materials are directly fed into the hot airflow from above. Small particles are immediately sucked in and react, while larger particles fall in the direction and are Here, the high-speed airflow is inhaled and reaches a balance with the thin spray layer inside the calcining chamber.

Therefore, the role of the calcining chamber, a backmix reactor for larger particles and a plug flow reactor for smaller particles, was used to evaluate the role of a gas suspension satin calcination furnace for roasting gold ore.

Flash roasting is a suspension system in which the material is processed in a gas stream, so the residence time is very short, usually only a few seconds. The short stay reduces the likelihood that the gold will become encased in iron oxide. In other cases, flash roasting replaces the traditional rotary kiln or boiling process.

03Low temperature oxidation method to recover gold

The economic indicators of low-temperature (160°C) pressure oxidation, high-temperature (200°C) pressure oxidation and roasting are very close. Wet pressure oxidation at low temperatures, while reasonable from a process engineering design and operational standpoint, presents some unique issues when temperatures reach 160°C.

The above introduces three beneficiation methods for transition zone type refractory gold ores. In the actual beneficiation process, the treatment methods for refractory gold ores are more complicated and generally require joint separation through multiple means. Therefore, multiple beneficiation methods are required. Only through experiments and repeated tests can a suitable beneficiation process plan for refractory gold ores be designed.

Xinhai Mining has more than 30 years of experience in gold ore beneficiation, gold extraction and gold ore smelting, and has completed several gold ore beneficiation projects for many companies around the world. Welcome to consult if you have any needs.