Increasing the selectivity modification of diamonds spectral characteristics before the X-ray luminescent separation process

Abstract

Introduction. A promising direction in solving the problem of increasing the recovery of diamonds with weak or anomalous luminescence is the use of modern technologies for modifying the spectral characteristics of diamonds with luminophore-containing reagents. Materials and methods. In the experiments, we used collections consisting of diamond crystals with weak and anomalous luminosity and grains of kimberlite minerals selected from the gravity enrichment concentrate. When evaluating the efficiency of fixing luminophores on the surface of diamonds, a vision-metric method was used in UV radiation with the determination of the proportion of surface areas covered with luminophores. The spectral and kinetic characteristics of diamond crystals and kimberlite grains were measured under laboratory conditions on a «Polus-M» separator. The separation of diamonds and kimberlite grains was carried out in the mode used in the industrial radar process. Results. The causes and regularities of the interaction of modifier reagents with kimberlite minerals, as well as the effect of dispersant reagents on the fixation of luminophores and the spectral and kinetic characteristics of kimberlite are determined. Discussion. It is shown that the fixation of an organic collector with luminophores on kimberlite minerals proceeds according to the adhesion mechanism with the formation of focal surface formations on hydrophobic minerals and point fixation on the surface of faces with low surface energy. It is shown that the high selectivity of the X-ray luminescence separation process is achieved at a surface concentration of the luminophores on diamonds of at least 15 % and a surface concentration of luminophores on kimberlite minerals of no more than 3%, controlled by the addition of reagents-dispersants. Conclusions. The article presents the results of studies of the mechanism and regularities of fixing luminophore-containing compositions on kimberlitic minerals in the presence of dispersant reagents. It was found that the addition of luminophore-containing reagents-modifiers of sodium hexametaphosphate, sulfonol, carboxymethylcellulose and liquid glass to the aqueous phase of emulsions provides an increase in the selectivity of fixing luminophores on the surface of diamonds and improves the performance of X-ray luminescent separation of diamond-containing products. A mode of increasing the selectivity of the action of an aqueous emulsion of the MLA-3 modifier reagent based on luminophore E-515-115-G5 has been developed by adding sodium hexametaphosphate to the emulsion aqueous phase at a concentration of 1-1.5 g/l, providing 90% recovery of weakly and abnormally luminous diamonds into the X-ray luminescent separation concentrate with a decrease in kimberlite yield by 33 %. The tested modifier agents and the selected conditions of their application can be useful in industrial conditions for the X-ray luminescent separation of diamond-containing kimberlites. Resume. As a result of the studies, a mode was developed to increase the selectivity of the action of an aqueous emulsion of the MLA-3 modifier reagent based on the E-515-115-G5 luminophore with the addition of a dispersant reagent (sodium hexametaphosphate) to the aqueous phase of the emulsion at a concentration of 1-1.5 g/l , providing the possibility of 90 % extraction of weakly and abnormally luminous diamonds into the concentrate of X-ray luminescent separation while reducing the yield of kimberlite by 33 %. Suggestions for practical application and direction for future research. The developed reagents-modifiers and the selected conditions for their use are recommended for testing and implementation in industrial conditions.