Institute of Geology, Karelian Research Centre, Russian Academy of Science (Petrozavodsk, Russia):
Svetova E. N., Senior Researcher, Candidate of Geological and Mineralogical Sciences, enkotova@rambler.ru (corresponding author)
Bubnova T. P., Researcher

Institute of Geology, Komi Research Center of Uralian Branch of Russian Academy of Science (Syktyvkar, Russia):

Shanina S. N., Senior Researcher, Candidate of Geological and Mineralogical Sciences

The paper presents the results of a study of milk-white vein quartz of the Fenkina–Lampi deposit in Karelia, regarded as a potential source of high-grade quartz raw materials. A process flow including magnetic separation, microwave exposure, ultrasonic treatment, and fractional chemical leaching in HCl and HF solutions was proposed for the low-grade feed quartz with the total content of impurity elements of 529 ppm. The effectiveness of individual quartz grain processing operations was monitored using inductively coupled plasma atomic emission spectrometry (ICP-AES), electron microscopy, and pyrolytic gas chromatography. It has been established that microwave exposure contributes to the efficient decrepitation of coarse and medium gas–liquid inclusions, but fails to ensure liberation of ultra-fine vacuoles. Sequential chemical leaching in HCl and HF solutions leads to a decrease in the total amount of impurities to 43 ppm in concentrates with the fineness of –0.315+0.2 and –0.2+0.1 mm. The experimental data demonstrate that the use of directed exposures, with due account of the typomorphic features of the quartz, allows obtaining satisfactory quartz concentrates from initially contaminated quartz raw materials, which expands the scope of their application in the manufacture of high-tech quartz products.

The authors are grateful to L. S. Skamnitskaya for the discussion of the results of this work.
The studies were carried out under state assignments of the Institute of Geology of the Karelian Scientific Center of the Russian Academy of Sciences and the Institute of Geology of the Komi Scientific Center of the Ural Branch of the RAS.

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