heavy mineral
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2021 ◽  
Vol 38 (2) ◽  
pp. 25-35
Author(s):  
Souradeep Mukherjee ◽  
Dr. A. Yugandhara Rao

Surficial sediment transportation studies carried out in the beach zone of Bendi-Baruva mineral sand deposit show that sand grains are transported by wind (saltation and suspension) beyond the high water line. The sand population of the study area contains heavy mineral sands (~20%) like ilmenite, garnet and sillimanite which covers 95% of the heavy mineral distribution with subordinate amounts of monazite, rutile, and zircon whereas light mineral sands (~80%) contain mostly quartz. Due to the sorted nature of these beach and dune sands the whole spectra falls within a specific range of grain size which shows a bi-modal distribution, primary mode at 0.025cm and secondary at 0.015cm. Due to this variation in density and grain size, mass of these sand particles vary resulting in differential transportation in any energy regime. In the study area, on the beach near the frontal dunes, surficial concentration of garnet grains are observed in patches having an average thickness 0.2cm i.e. around ten times of the dominant grain diameter. This surficial enrichment of garnet grains resting on a semi-uniform sand surface is the result of differential transportation of the dominant mineral grains. As more than 80% of the grain size population show a dominant grain size of 0.025cm, the wind flow parameters for the whole population is standardized with mean grain diameter (D) of 0.025cm. Mass of dominant individual minerals arrived from the grain counting technique was tallied with the theoretical mass considering spherical shape of the grains indicates a difference of mass to be within 5%. For ease of calculation and generalization the grains were considered to be spherical and their theoretical masses were taken into consideration in calculations. Considering the whole spectra of mineralogical distribution, a theoretical mass group distribution for dominant different minerals of different dominant grain sizes were formulated and total six mass groups were identified. Because quartz (~80%), ilmenite, sillimanite and garnet (together ~20%) are the most abundant, their positions were identified specifically in the theoretical mass groups and only these are considered for further discussion. To analyse wind velocity and pressure at different heights from the surface, a sediment trap was fabricated using piezo-electric sensors. A tail was attached to orient the device parallel to the wind flow so that the piezo surfaces always face the wind flow at 900 angle. The device records pressure data and converts those into voltage. Using the velocity data, macroscopic physical quantities of aeolian transportation were calculated for the study area, which empirically show the effect of mass in differential transportation of the dominant minerals that gives rise to these surficial garnet patches.


2021 ◽  
Vol 38 (2) ◽  
pp. 79-84
Author(s):  
Indrajit Patra ◽  
William Prasad ◽  
A Y Rao

The concentration of heavy mineral placer deposits along the coastal tracts are function of various favourable factors i.e. hinterland geological formations, prevalence of favourable climatic condition, their transportation through intricate drainage systems and various coastal processes, which operated during the geological past. Textural analysis of the available unconsolidated sediments from the present deposits is of vital importance to decode the prevailing depositional environment while grain size analysis is the major parameter used. Present study highlights the grain size analysis of the identified sand column from Chhatrapur Mineral Sand Deposit along the coastal tract of Odisha to infer the environment of deposition of heavy mineral bearing sand and their heavy mineral content variation. Standard procedure of sampling, data analysis and interpretation techniques were adopted. Result shows that, sands from frontal and rear dune are characterized by distinct bi-modal distribution, medium to fine, moderately to well sorted with good positive skewness, whereas, sand from Inter-dunal region shows dominant unimodal, medium to coarse grain, moderately poorly sorted nature and slightly positive skewness. The better heavy mineral concentration (10 to 25 % grade) in frontal and rear dunes is attributed to prevalence of aeolian dune deposition accompanied by good sorting. In contrast, the low concentration of heavy mineral (3 to 6 %) in inter dune region is due to occasional fluvial regime and poor sorting of sediments. Thus, grain size analysis can be an effective tool to decipher local prevailing depositional environment, which has a bearing on heavy mineral concentration as well.


Minerals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 59
Author(s):  
Daniel Layton-Matthews ◽  
M. Beth McClenaghan

This paper provides a summary of traditional, current, and developing exploration techniques using indicator minerals derived from glacial sediments, with a focus on Canadian case studies. The 0.25 to 2.0 mm fraction of heavy mineral concentrates (HMC) from surficial sediments is typically used for indicator mineral surveys, with the finer (0.25–0.50 mm) fraction used as the default grain size for heavy mineral concentrate studies due to the ease of concentration and separation and subsequent mineralogical identification. Similarly, commonly used indicator minerals (e.g., Kimberlite Indicator Minerals—KIMs) are well known because of ease of optical identification and their ability to survive glacial transport. Herein, we review the last 15 years of the rapidly growing application of Automated Mineralogy (e.g., MLA, QEMSCAN, TIMA, etc) to indicator mineral studies of several ore deposit types, including Ni-Cu-PGE, Volcanogenic Massive Sulfides, and a variety of porphyry systems and glacial sediments down ice of these deposits. These studies have expanded the indicator mineral species that can be applied to mineral exploration and decreased the size of the grains examined down to ~10 microns. Chemical and isotopic fertility indexes developed for bedrock can now be applied to indicator mineral grains in glacial sediments and these methods will influence the next generation of indicator mineral studies.


2021 ◽  
pp. 105016
Author(s):  
Huizhen Hao ◽  
Zhiwei Jiang ◽  
Shiping Ge ◽  
Cong Wang ◽  
Qing Gu

2021 ◽  
Vol 14 (12) ◽  
pp. 33-47
Author(s):  
Joya Moni Mout ◽  
Ranjan Kumar Sarmah

This study presents a record of the depositional mode and provenance of the Kopili sandstones outcropped in and around Umrangso, the Dima Hasao district of Assam, India using proxies such as grain size and heavy mineral study. The Grain size study reveals that the sandstones of the Kopili formation consist predominantly of fine-grained sands mixed with medium sands. The grain size statistical parameters divulge that the sandstones are characterized mostly by moderately sorted sands, coarse skewed to near symmetrical, leptokurtic to extremely leptokurtic nature. The frequency distribution curves reflect mostly bimodal as well as polymodal distribution of sediments. The Linear Discriminant Function analysis indicates shallow marine beach sub environment in agitated water depositional condition for the Kopili sediments. The CM pattern discloses that saltation and suspension are the dominant transporting modes. The Heavy mineral analysis discerns that opaques dominate over transparent heavies. Transparent heavies in decreasing order of abundance are zircon, tourmaline, rutile, clinopyroxene, staurolite, hornblende, garnet, chlorite and epidote. The zircontourmaline- rutile (ZTR) maturity index (average 53.15%) discloses sub-mature to mature nature of the Kopili sandstones. The heavy mineral assemblage corroborates their mixed provenance (silicic igneous and metamorphic) for the Kopili sandstones.


Minerals ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 1253
Author(s):  
Uwe König ◽  
Sabine M. C. Verryn

Heavy mineral sands are the source of various commodities such as white titanium dioxide pigment and titanium metal. The three case studies in this paper show the value of X-ray diffraction (XRD) and statistical methods such as data clustering for process optimization and quality control during heavy mineral processing. The potential of XRD as an automatable, reliable tool, useful in the characterization of heavy mineral concentrates, product streams and titania slag is demonstrated. The recent development of ultra-high-speed X-ray detectors and automated quantification allows for ‘on the fly’ quantitative X-ray diffraction analysis and truly interactive process control, especially in the sector of heavy mineral concentration and processing. Apart from the information about the composition of a raw ore, heavy mineral concentrate and the various product streams or titania slag, this paper provides useful information by the quantitative determination of the crystalline phases and the amorphous content. The analysis of the phases can help to optimize the concentration of ores and reduction of ilmenite concentrate. Traditionally, quality control of heavy mineral concentrates and titania slag relies mainly on elemental, chemical, gravimetrical, and magnetic analysis. Since the efficiency of concentration of minerals in the different product streams and reduction depends on the content of the different minerals, and for the latter on the titanium and iron phases such as ilmenite FeTiO3, rutile TiO2, anatase TiO2, or the various titanium oxides with different oxidation stages, fast and direct analysis of the phases is required.


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