Acta Petrologica et Mineralogica

Fused quartz crucible produced from high purity quartz (HPQ) sands is an essential material in which monocrystalline silicon ingot is grown by a process called the Czochralski process, and therefore plays an important role in solar photovoltaic cell and semiconductor industries. Almost all HPQ sands used for fused quartz crucible production in China come from overseas HPQ deposits in USA and India. Investigations on foreign HPQ ores with focus on impurities occurrences, beneficiation test, and resources potential evaluation are pivotal for HPQ deposits prospecting in China. In this study, I used a combination of multiple analytical techniques to conduct petrographic analysis, process mineralogical investigation and beneficiation test on a high purity quartz ore from northern India. My efforts reveal that quartz crystals from the ore material are relatively equant in size and largely devoid of liquid-gas inclusions. The existing liquid-gas inclusion assemblages predominately occur along grain boundaries of quartz crystals, and diffusive inclusion assemblages are extremely rare. Identified gangue minerals, in order of frequency, are Fe-bearing muscovite, iron oxides, ilmenite, zircon, monazite, brabantite, rutile, and mainly embedded among quartz crystals. Based on the impurities occurrence features of the Indian HPQ ore, refinement flowsheet composed of crushing-grinding, sorting, calcination, water quenching, high gradient magnetic separation, flotation, acid leaching, and hot chlorination was carried out, and end products were verified as 4N8 grade HPQ sands (total concentrations of 15 trace elements < 20×10^-6, SiO₂ content > 99.998%). By comparison with IOTA CG HPQ sands, the 4N8 grade HPQ sands extracted from the Indian HPQ ore were deemed to be used to produce outer layer of quartz crucible. Implications for HPQ ore prospecting in China deduced from this investigation practice on the Indian quartz-crucible-grade HPQ ore could be concluded as follows. Resources evaluation on potential HPQ ore in conjunction with process mineralogical study and beneficiation test is an essential prerequisite for deposits prospecting. Given the current political-economic environment, I recommend that the Chinese government designate the HPQ raw material as a unique mineral resource and enroll it on the National Strategic Mineral List. Subsequently, a general specification for HPQ ore exploration is needed with great urgency. In order to create domestic breakthrough on HPQ ore prospecting and resolve the dilemma that supply chain of HPQ sands used for solar and semiconductor industries relies heavily on USA and India, the domestic sections of HPQ deposits prospecting and exploration, HPQ sands extraction, HPQ products fabrication, and application end user should work collaboratively under the government organization and supervision.

quartz crucible; beneficiation test; high purity quartz sand; high purity quartz deposit; implication for ore prospecting