Optimizing composition and application conditions of agents for modifying spectral characteristics of diamonds in X-ray luminescence separation

Abstract

One of the research areas focused on improving the efficiency of diamond-bearing kimberlite beneficiation processes involves the utilization of technology aimed at enhancing the recovery of weakly and anomalously luminescent diamonds during the X-ray luminescence separation process using luminophore-containing chemical agents. The objective of this research was to select the optimal composition of agents that modify the spectral characteristics of minerals and the conditions for their application. A crucial factor for process efficiency is the effective attachment of modifying agents to diamond crystals while avoiding similar attachment to kimberlite mineral surfaces. This is achieved through the use of organic collectors with an optimal composition, characterized by their ability to both adhere to the diamond surface and retain inorganic luminophore grains. The evaluation of luminophore attachment efficiency was performed using visiometric analysis in the UV range. The capability of diamonds to retain luminophore collector droplets or films on their surfaces was evaluated using a technique to measure the three-phase limiting wetting angle. The spectral and kinetic characteristics of diamonds and their recovery during the X-ray luminescence separation process were determined using a POLYUS-M separator. The feasibility of purposefully modifying the spectral characteristics of weakly and anomalously luminescent diamonds through luminophore-containing compositions based on zinc sulfides and zinc orthosilicate has been confirmed through the conducted studies. By considering the criterion of selectivity in the attachment of luminophore emulsion to diamonds and kimberlite minerals, calculated based on the measured surface concentrations of luminophores on the minerals, the optimal ratios between the masses of inorganic luminophore, organic collector, and the aqueous phase of the emulsion were determined. Dispersing agents that offer selective binding of luminophores to diamond crystals were identified, and rational parameters for the composition of the organic collector were established. The temperature range for treating diamond-containing material was defined. As a result of bench testing the modifying agents with the selected composition and conditions for their application in the diamond-containing material treatment cycle before XRF separation, it was confirmed that the recovery of anomalously and weakly luminescent diamonds could exceed 90%, while keeping the yield of kimberlite minerals in the concentrate below 1%.