The mine is characterized by increased concentration of clay in gold bearing sediments. Gold of this field is refractory from polygon complex to recovery at placer gold-concentration site (PGCS). It is common for clay saprolites of gold fields.
Taking into consideration geological peculiarities, washing and processing complex has been constructed for gold recovery from clay sands. Concentration of clay in clastic and river cobble deposits forming goldbearing volumes of sand was from 20 to 35%. Gold recovery was complicated by extremely low particle size and prevailing of flake form particles over isometric form ones.
In these conditions, the decision to equip the processing complex with two consequent scrubber trommel for two-stage washaway of clay sands was adopted. The first drum is needed for preparation of slurry from incoming earth materials for further processing by the second scrubber trommel with performance rate to 150 m3/hour. Due to great dispersion of clay quantities in earth materials serving into hutch from different paces of processed mine, it was necessary to regulate the volume of feed by controlling of clay washaway level with the help of washer complex. Quality of clay washaway from clastic material is easy to determine by boulders drop from drum into lixiviation dump.
Slurry from scrubber trommel was divided by fineness and came into sluice equipped by riffles and rubber mats for capturing of heavy minerals from the flow. For maximum recovery, sluice extension with polyurethane screens was applied.
Slurry flow was directed to sluices of small load; on exiting them, was processed by jigging machines equipped with heavy bed. Well-adjusted heavy bed acted as a concentrator with current discharge. Underflow placer directed for further stage of processing and its decreasing was accumulated in the tank of one more jigging machine.
For processing of releasable gold concentrate, placer gold-concentrate site was equipped with jigging machines MOD-02 (МОД-02) with heavy bed, on which it is easy to perform gold concentrate processing by the manual method of feed into shovel trough with the help of pullers. Then, obtained underflow placer was directed to the shaking table SKO-1 (СКО-1) where placer gold was recovered.
Calculations and long term operation trials prove that refractory gold with the great quantity of small and very small gold (approximately 35% of 0.2 mm size if less) is recovered easily with the help of jigging machine equipped with heavy bed with further extraction into concentrate (goldilocks) of shaking table.
I t is well seen on photos of operation of the shaking table SKO-1 (СКО-1) that major part of recovered gold is small – less than 0.2 mm.
Gold concentrate processing from sluice of scrubber trommel was held separately from gold concentrate processing obtained from underflow placer of jigging machines. Weighting (in grams) and analysis of recovered gold balance were held separately. For main cleanup, gold recovered from releasable gold concentrate from main sluice was taken, and for additional recovery, gold from underflow product of jigging machines was taken. Dispersion of additional recovery values was from 21.7 to 47.2%. Average additional recovery was illustrated by the value of 37.7.
As a result, the steady value was additional recovery of 150 gram of gold during cleanup of 500 gram of gold from main sluice, what is 30% from main volume!