Gold Gravity Concentration

 

For a long time the use of gravity concentration to recover gold has been very important in the design of several operations around the world. In some circumstances, the use of gravity concentration methods to recover gold has been coupled with flotation and/or cyanidation. There has been a widespread lack of understanding of the principles of possible applications of gravity separation in gold ores processing. Essentially, this type of processing was thought to be applicable only to free gold deposits. The last years there have been a resurgence of interest in gravity separation, especially in using its low cost to improve the economics of high tonnage or low grade operations.

Gravity separation has been found to be increasingly applicable in the recovery of free gold, sulphide and oxide minerals, and in the processing of low grade gold ores. The reasons for this interest are basically associated with the low capital costs of gravity separation and the low operation costs due to low power consumption and the absence of reagents. Other advantages include the ability to separate gold bearing minerals that are liberated at coarser sizes, above the normal size range for flotation or cyanidation. The absence of reagent contaminated waste products from a gravity separation plant may also offer environmental advantages. With the time, the introduction of centrifuge units has changed the concept of some gold gravimetric plants or new designs of spiral concentrators that are easy to install and require minimal supervision, while providing a high degree of separation, will aid this interest by removing the restrictions over gravimetric equipment.

Gravity separation has the potential of providing an economical means of recovering and concentrating many types of gold ores. Laboratory separations and small scale testwork can provide data for reliable design of treatment plants. Flexibility in the operation of gravimetric concentrator enables spiral plans to be designed so that material is processed according to its particular requirement. Improved designs of gravimetric equipment offer efficient and economical alternatives. The use of gravity concentration for gold recovery has been widely considered by many plant designers. Equipment traditionally used includes strakes, shaking tables, spirals, jigs, sluices, spirals, cones and the last years, centrifugal concentrators. In some circumstances, it has important to install a pilot unit in an existing gold operation. For example, before the introduction of centrifugal unit, the Ok Tedi plant, Papua New Guinea evaluated a spiral unit. The results indicated the benefits of using gravity concentration before leaching, mainly the recovery of coarse gold, shorter leach times, reduce soluble losses, lower gold inventories and reduced reagent consumption.