Terms of reference specified by the client is to increase efficiency of gold recovery during work on refractory placers. The task is formed, because production devices used earlier could not process placers without high level of losses.
For decreasing of washing time of whole polygon allocated for stockpile of mine being built, washing complex PSK-52 (ПСК-52) is applied. Slurry underflow is directed to scrubber trommel SB-150 (СБ-150) with perforation of 30 mm.
On exit from scrubber trommel, slurry underflow goes to three small direction sluices for decreasing the slurry flow passing through one sluice.
Slurry flow exiting each sluice is divided into two parts for feeding two parallel jigging machines MOD-2 (МОД-2). Dewatering hutches are used for load uniformity.
Onwards, underflow product with fineness of 3.2 mm is served by gravity to the seventh jigging machine MOD-2 (МОД-2) equipped with grid made wire with diameter of 1.6. After seventh jigging, processed product is directed to jigging machine MOD-1 (МОД-1) equipped with heavy bed.
Underflow product of jigging machine MOD-1 (МОД-1) goes by gravity via rubber hose with inner diameter of 90 mm into 200-liter drum washers. Volume of gold concentrate (underflow placer MOD-1) had been varying from 3 to 16 drums a day at the beginning of works. For decreasing gold concentrate to a minimum value without losses, optimal grid sizes had been selecting for a long time at the all stages of jigging machines.
Obtained concentrate comes for processing to placer gold-concentrate site. Jigging machines MOD-0.2 (МОД-0.2) with heavy bed are used for decreasing concentrate volume; after that, gold dust are extracted on the shaking table SKO-1 (СКО-1).
Then, black placer accumulated during recovery of 10 kg of concentrate of main cleanup (approximately 60 l) is gradually annealed under temperature of approximately 650 degrees and grinded on a grinder. As a result, additional recovery reaches 628 g of gold along with 9,864 g of main cleanup.
Absolute result reaches 6% of additional recovery with well-processed gold concentrate on the shaking table SKO-1 (СКО-1) of experimental design, what is becomes an opportunity for medium and small companies to recover additional gold by their own forces.
For increasing of recovery of refractory gold within this project, combined experience and recommendations of specialists and research engineers of Irgiredmet, OAO regarding processing of entire slurry flow of jigging technology production device are applied.
Application of PSK-52 (ПСК-52) at processing complex has allowed increasing sand washing to reach stable values of 2,500-3,500 m3 per day.
Actual performance of complex with applying of scrubber trommel SB-150 (СБ-150) is from 80 to 120 m3 per hour. The inclusion of scrubber trommel with lower performance into processing complex within this project is unfeasible because of conditions of washaway of clay sands.
Additional recovery of gold with the help of this complex with application of jigging machines processing entire slurry flow of sluice extension with polyurethane screens was changed from 21.7 to 47.2% in relation to cleanup of gold from main sluice of scrubber trommel. Average value of additional recovery during the period of technical support of production season was 37.7%.
Works were held during two washing seasons of 2013-2014.