Mineral control on the geochemistry of the Rock Canyon Creek REE-F-Ba deposit, British Columbia, Canada

The Rock Canyon Creek carbonate-hosted REE-F-Ba deposit has tectonic, stratigraphic and structural similarities with Mississippi Valley-type and sparry magnesite deposits in the SE Rocky Mountains. The main REE-fluorite zone is a steeply dipping body, extending 1100 m along-strike, 50 m wide and 100 m deep. It spatially coincides with pre-existing crackle breccias in carbonate rocks, and consists of dolomite, fluorite, barite, pyrite, quartz, K-feldspar, calcite, porous apatite, REE-fluorocarbonates and REE-phosphates. The main fluorocarbonates are bastnaesite, parisite and synchysite. Monazite, crandallite group minerals and apatite are the main phosphates. Fluorite content varies from less than 1 to 13.5% (by weight) and ∑REE + Y concentrations vary from trace to 1.95% (by weight). The mineralized zone is heterogeneous on the deposit scale, as indicated by three-dimensional geochemical modelling combined with a geochemical assessment based on 89 mineralized samples and detailed downhole mineral and geochemical profiles of a key borehole. Chemical heterogeneity and key elemental co-variations are explained by strong mineralogical control and have implications for the design of exploration and development programmes for this type of deposit. The chondrite-normalized REE pattern of samples from the mineralized zone shows enrichment in LREE, similar to typical carbonatite-related mineralization; however, no carbonatite is exposed nearby.

Study of promises for the use of ultrasound in the technology of secondary benefication of processing wastes

The results of the study, aimed at designing of benefication technology of mine processing wastes of Voznesenskiy ore district, are presented in this paper. By the expert appraisals, the amount of tailings dumps of the Yaroslavskaya Mining Company is estimated to be more than 30 million tons. Sample testing has shown that fluorite content varies from 13% to 23%, calcite - up to 14%, and zinc - in the range of 0.4-0.6%. The research was conducted with tailing samples containing 20.7% of CaF2 and 10.2% of CaCO3. Mineral grains of the secondary raw material were examined for their surface state and a package of necessary preliminary operations, which provide an efficient material - flotation reagents interaction, was determined. It has been established that extraction of fluorite to concentrates that would match existing requirements is possible in principle. The use of ultrasonic treatment of material in its preparation for flotation is conditioned by an effective desorption of films of different nature from mineral particles. The suggested scheme of fluorite flotation involves preliminary treatment of raw material by ultrasound with dumping of released mud fractions. The optimal operating regime allows obtaining concentrates of higher quality than it is under usual technology without the ultrasonic exposure. In this process, the extraction of fluorite to a concentrate with 94.47% of CaF2 increases up to 61.11%, which is higher by 2.96% against the original studies.

The prospects for secondary processing of tailings remained after the beneficiation of fluorite ores of Primorye Krai using a highly selective combination of reagents

The study of the composition and preparability of two samples of tailings dumped at the Yaroslavl Mining Company revealed the following contents: CaF2 - 15.2 and 20.7%, CaCO3 - 13.3 and 10.2%, and Zn - 0.49 and 0.38%. The volume of the stockpiled wastes is estimated at 30 million tons. The need for fine material grinding at the stage of preparation for flotation was shown, and the efficient fluorite concentration was possible with technical solutions found. The determined optimal parameters of the flotation acid-base condition provided neutralization of the negative influence of salts and slimes left by the previous processing cycle. It has been established that a mixture of ammonium and lignosulfonates was effective as a modifier. The extraction of sample 1 yielded 52% of fluorite extraction to the concentrates with 92.2-92.8% fluorite content, and more than 69% when beneficiating the sample 2. Upgrading of the concentrate quality is only possible through transferring to flotation tails of the most contaminated fluorite grains impregnated with silicate minerals, but this is followed by a significant extraction reduction. The concentration of sphalerite to a separate product occurs with low effectiveness. The inclusion of sulfide flotation in the circuit head can improve the fluorite cycle efficiency: extraction of CaF2 to the concentrates of FF-92 brand may reach 70%.