The Method for Preliminary Enrichment of Gold-Containing Ore

In recent years the separation of the tails with minimal content of valuable components at the processing of the minerals before expensive enrichment has attracted considerable attention. This will be favourable for increasing the ore enrichability as well as significant reducing the costs of the further operations for enrichment. The samples for investigation have been taken from the gold-containing polymetallic ores of Georgian Bektakari deposit (Bolnisi district) with the content of gold – 5.61g/ton, of lead – 1.65%, of zinc – 2.43%. At the preliminary preparation of the samples the following was taken into consideration: the crushing of the coarsegrained fragments to the classes of +8, 8-3 and 3-0 mm; separation of the 8-3 mm class from the crushed fragments and their enrichment for obtaining of the tails on the modernized high-frequency diaphragm precipitating machine (Georgian Patent #U 2018 1962 Y) of improved construction. The novelty of the machine lies in the fact that together with the main oscillation, frequency of water oscillation, water discharge) the additional controlling parameters are introduced in the process, such as water low-amplitude high-frequency oscillations, velocity of water downflow. The first one is obtained as the result of the impacts of eccentric axis and diaphragm frame. It should be also noted that the above-mentioned oscillations reduce the frictional force between the suspended grains. As the result the minerals of various density freely move in their own layers, increasing the efficiency of the minerals separation. In the second section of the precipitating machine the enhanced velocity of water downflow is obtained by compressing of the spring fixed on the frame which imparts the various accelerations to the minerals of the different densities and is favourable for their efficient separation. Along with it, the compression of the spring enhances the force of the frame impact as well as the frequency of low-amplitude oscillation. In the course of the investigations on the enrichment of 8-3 mm classes, when the amplitude of water main oscillation comprised: A=16 mm, oscillation velocity n = 420 rpm and water discharge was 5.5 l/min, in the second section of the precipitating machine the product was obtained by the yield – 22.3% by gold content Au=0.4 g/ton. On this basis the mentioned product may be isolated. It may be considered as the tails and the investigation on the enrichment may be performed for residual product. On the basis of the analysis of experimental data the action of the controlling and disturbing parameters for the control of precipitation process was revealed. The optimal control of the process is performed by the requirements of technological criterion: retention of such vales of controlling parameters which provide the maximum content of gold (minimum content of gold in the tails) in the concentrate in spite of the variation of distributing actions. For this reason, the goal function and mathematical model were derived on the basis of which the method for automatic control was elaborated.