Mineralogy and Processing of Hydrothermal Vein Quartz from Hengche, Hubei Province (China)

Abstract

Quartz occurs in many geological materials, and is used in numerous industrial fields as a raw material. Mineralogy and the processing of hydrothermal quartz were studied by optical microscope, electron probe microanalysis, scanning electron microscope, inductively coupled plasma-optical emission spectrometry, and inductively coupled plasma mass spectrometer. A combination of the geological occurrence of the quartz deposit, mineralogical studies, and the processing technologies of the hydrothermal quartz was accomplished. The results show that impurities within the quartz mainly include muscovite, hematite, apatite, and secondary fluid inclusions. The main chemical impurities are Al (353 µg·g −1 ), K (118 µg·g −1 ), Fe (61.2 µg·g −1 ), P (15.5 µg·g −1 ), Na (13.4 µg·g −1 ), Mg (11.8 µg·g −1 ), Ti (8.31 µg·g −1 ), and B (10.8 µg·g −1 ). Based on these results, a combined process consisting of calcination and fluoride-free pressure acid leaching was established to effectively decompose and dissolve the quartz, and remove gangue minerals and fluid inclusions. The calcination process not only removed volatile components; it also destroyed the crystal structure of gangue minerals and enhanced their release probabilities. The calcination process has a positive influence on the removal of impurity elements by the fluoride-free pressure acid leaching process. A total of 85.2 wt % and 84.0 wt % of impurity elements was removed using the leaching systems of HCl-NH 4 Cl and H 2 SO 4 -NH 4 Cl, respectively.

Assessment of shear zone-derived quartz from the Etam area, southwest Cameroon as potential high-purity quartz resource: petrography, geochemistry and technological studies

“…However, the abundance and the variability of fluid inclusions suggest that this quartz benefitted from hydrothermal fluids inputs. Impurities contained in it are similar to some hydrothermal quartz data available [16,64]. Therefore, it is suggested that quartz in Etam was probably formed during metamorphic processes implying circulation of hydrothermal fluid saturated in silica [73], followed by silica precipitation and formation of hydrothermal veins.…”

“…Therefore, for quartz to be suitable as HPQ raw material, it should meet certain natural requirements, or the processing should be done by methods that are less hazardous and more efficient. Indeed, an efficient fluorine-free leaching system to purify quartz has been developed with an objective to establish a fluoride-free technology for improving quartz quality [16]. According to the authors, the method can consistently purify quartz by removing elements impurities up to 88.2 wt%, 99.0 wt% and 98.1 wt%, for the HCl-NH4Cl system, and 87.5 wt%, 98.1 wt% and 98.2 wt% for the H 2 SO 4 -NH 4 Cl system, respectively, for Al, K and Fe.…”

“…Proper processing methods such as calcination pretreatment combined with ultrasound-assisted leaching [15] that increase SiO 2 content concentration up to 99.9% and methods using HCl-NH 4 Cl and H 2 SO 4 -NH 4 Cl reagents with removal rate between 88 and 99 wt% for some impurities (Al, K and Fe) have been developed [16] to upgrade quartz purity in order to meet industries' quartz glass requirements. In this regard, industries often prefer the application of purification techniques in medium-to high-purity resources.…”

New Approach in Research of Quartzes and Quartzites for Ferroalloys and Silicon Production

“…The difference between them is mainly in the content of impurities. Quartz may contain individual trace amounts of impurities including aluminum, iron, magnesium, calcium, titanium, potassium, lithium and boron, whereas quartzite contains quantifiable amounts of impurities which also form individual mineral-based compounds in the ore (e.g., calcite, hematite or dolomite) [1]. The main types of deposits for lump metallurgical quartz in geological terms are quartzite, hydrothermal quartz and pegmatite quartz (rock quartz) and fluvial quartz (gravel quartz) [2].…”

Editorial for Special Issue “Mineralogy of Quartz and Silica Minerals”

“…The papers by Götze et al [3], Lin et al [4], Pei et al [5] and Guatame-Garcia and Buxton [6] impressively demonstrate how advanced analytical methods are being used for the characterization of mineral properties and how this knowledge can be used for processing. The material that was investigated in these studies includes high-purity quartz from metamorphic host rocks, hydrothermal vein quartz, as well as diatomite.…”