Viable Options

It is a common knowledge that the loss in the process of extracting placer and ore gold is associated with fine, plate and dust shape gold, with particles size varying from +500 to several microns.

About 80 % of all current gold production in Russia is of placer origin. Due to intensive exploitation for many decades the fraction of coarse, easy to catch metal has diminished considerably. Average grades have gone down by 2 to 3 times as well as average particle sizes decreased by 2,5 to 3 times. Prevailing are the sources with gold particle sizes varying from –0,2 to + 0,05 mm and less.

These negative trends may be diminished through introduction of new technologies and technical means of benificiation. Otherwise at present gold digging co-operatives lose from 20 to 50% of gold due to the use of traditional, inefficient equipment and methods..

The use of sluices and jigging machines results in reducing losses by 5 to 15 % . But the average extraction level of fine fraction tends to be still low, namely 76 % with –0,25 +0,1, 48 % with –0,1 +0,05 and only 18 % with –0,05 fractions.

Currently used concentration tables, spiral separators and jigging machines are not able to solve comprehensively the problem of fine gold extraction. Stringent ecological legislation in most gold producing countries, prescribing the use of mercury in the process also contributes significantly to the losses.

It is evident that the new technological methods are required to deal with the problem of fine gold loss. The most promising and efficient ones are the schemes using centrifugal gravity concentrators.

Another aspect of this problem is an enormous amount of accumulated technogenic dumps, resulting from decades of mining, which may become a source of additional gold through re-mining. In some cases the grades at such dumps are comparable to those of the newly commissioned mines.

The most promising way of dealing with this issue is using centrifugal concentrators. Practical experience accumulated by this company proves that the use of Itomak concentrators for extraction of free gold starting from 0,3g/t is a viable undertaking in most cases.

The level of extraction of free metal reaches 80 % and in some cases exceeds this figure.