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Mineral-driven industrialisation of Africa
Published in Francis P. Gudyanga, Minerals in Africa, 2020
The other cause of the siltation is the erosion of their banks. This is very evident especially where there are settlements and gardening activities along the rivers. Mineral sands contain suites of minerals with high specific gravity known as ‘heavy minerals’. These minerals occur in very low concentrations in a variety of igneous and metamorphic rocks, but being chemically and physically resistant to weathering, and having comparatively high specific gravity, they tend to accumulate in placer deposits in river channels or along coastal shorelines.
Mineral Deposits
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Many different natural processes can concentrate minerals and create ores. In the rest of this chapter, we will look at some of the most significant of those processes and the kinds of ore deposits they produce. Some processes are physical processes, involving deposition of sediment or of heavy mineral grains. Others are chemical processes that involve elements or minerals dissolving in water before being precipitated somewhere else. Still others are magmatic processes involving minerals crystallizing in a pluton or associated with volcanism. Economic geologists have proposed many classification schemes, but none is perfect because there is great variation between different kinds of deposits, and there is no single, logical way to group them. Thus, the examples below do not include every possible kind of ore deposits, but instead are descriptions of some of the deposits of greatest importance.
Selective flotation of ilmenite from ilmenite-rutile mixtures
Published in Gülhan Özbayoğlu, Çetin Hoşten, M. Ümit Atalay, Cahit Hiçyılmaz, A. İhsan Arol, Mineral Processing on the Verge of the 21st Century, 2017
M. Köse, Ç. Hoşten, Y. Topkaya, M. Akser
Rutile(TiO2) and ilmenite(FeTiO3) are some of the most common heavy minerals used for TiO2 pigment and titanium metal production. Rutile and ilmenite occur together frequently. This is commonly true in placer deposits where their high specific gravity has caused a mixed concentration of such heavy minerals. For the separation of valuable heavy minerals, gravity methods are firstly used to remove sand and clay. Then, the concentrate is dried and conducting titanium minerals are separated from the other products by high-tension separators. The electrically conductive minerals such as ilmenite, rutile, leucoxene give up their charge to a grounded rotor and fall free while the non-conductors (silicates, oxides and phosphates) are pinned to the rotor. Magnetic separators are used to separate paramagnetic minerals (ilmenite, leucoxene) from non-magnetics (rutile). These conventional methods, however, work efficiently only on particles coarser than 100 mesh. Significant loss of productivity occurs in finer sizes in current heavy mineral process industries, and the separation process becomes uneconomical below 45 μm particle size. Therefore, there are large tonnages of fine-sized ilmenite-rutile mixtures in the world that cannot be used for pigment manufacture.
Upgrading a Brahmaputra River sand from northern Bangladesh by flotation to produce a high-grade silica glass sand concentrate
Published in Mineral Processing and Extractive Metallurgy, 2022
Md. Aminur Rahman, Kevin J. Davey, Graeme W. Heyes, Warren J. Bruckard, Graham J. Sparrow, Mark I. Pownceby, James Tardio, Md. Nazim Zaman
Research on river sand deposits in Bangladesh has largely focussed on the heavy mineral (HM) content, which is appreciable (Datta and Subramanian 1997; Heroy et al. 2003; Rahman et al. 2014, 2020; Garzanti et al. 2019). Recent studies have demonstrated that it is possible to recover the valuable heavy mineral components (e.g. ilmenite, garnet, zircon and rutile) using dredging followed by wet and dry beneficiation techniques commonly employed in the mining of heavy minerals from beach sand deposits (Rahman et al. 2016). In such operations, the rejected light minerals, as well as the uneconomic heavy minerals, would usually be disposed into mined-out areas. In Bangladesh however, backfilling of dredged waterways is not possible as the initial objective of sand mining is to clear navigable waterways from the huge volumes of sand and silt that are deposited annually following erosion and transportation from the high Himalayas during summer melting. Consequently, utilisation of the light mineral fraction may also be considered for potential recovery and uses such as ordinary sand for civil engineering works or for the manufacture of sand-cement blocks to be used in construction. Furthermore, since quartz makes up >80–85% of the total sand and silt load (Rahman et al. 2014, 2020) – the balance is mainly other light minerals such as feldspar and micaceous materials – if the quartz was effectively separated and provided it met market specifications regarding size, particle shape and chemistry, it could provide a raw material feedstock for glassmaking.
Multi-disciplinary ore deposit exploration in Sonqor, northwest Iran
Published in Australian Journal of Earth Sciences, 2021
S. Niroomand, D. Poreh, A. Kananian
In the Sonqor area, heavy mineral exploration was also carried out to define the extension of substantial minerals. Rock-forming minerals with a density greater than 2.8 (garnet, pyroxene, micas and/or zircon, tourmaline, apatite) are classified as heavy minerals and have been widely applied to detection and tracing of mineral deposits. Gravel and silts samples (2–10 kg) were taken from natural traps of shallow drainage with local geological settings, tectonics, rock formations, placer configurations and other important factors noted. Heavy mineral concentrates were prepared using three/tetra-Bermo-Ethan, Mitilin iodide and Clerici with a density of 2.89, 2.96, 3.32, and 4.42 . For heavier minerals like garnet or zircon, LST liquids with changing densities may be used; the heavy liquids were cleaned from mineral faces with Easton, alcohol or methylated spirit.
Paleo-environment and provenance in a lacustrine shallow-water delta-meandering river sedimentary system: insights from the Middle–Upper Jurassic formations of the Fukang Sag of Junggar Basin, NW China
Published in Australian Journal of Earth Sciences, 2019
L. Luo, X. Gao, X. Tan, J. Gluyas, J. Wang, X. Kong, J. Huang, H. Shao, F. Qu
Generally heavy minerals are derived from specific source rocks and heavy mineral analysis is the most common technique for provenance determination (Aubrecht et al., 2017; Bassis, Hinderer, & Meinhold, 2016; Do Nascimento et al., 2015; Garzanti, Andò, & Vezzoli, 2008; Morton & Hallsworth, 1999; Nie et al., 2012; Sevastjanova, Hall, & Alderton, 2012; Svendsen & Hartley, 2002). The heavy mineral composition of a source rock can be altered and modified by many processes such as chemical weathering, hydraulic sorting during transport, sorting by grainsize, diagenetic alteration during deposition and burial processes (Garzanti et al., 2008; Morton & Hallsworth, 1999). Therefore, some heavy mineral (HM) assemblages, which are sensitive to their environment, can also be used to evaluate the approximate paleogeographic conditions, including paleoclimate, paleo-environment and paleotopography (Dinis & Soares, 2007; Jin, Lin, Yang, & Ji, 2002; Lin, Chen, & Liu, 2008; Liu, 2012). Heavy mineral analysis was performed on 30 samples, which were collected from the Toutunhe and Qigu formations, to identify the species and characteristics. Moreover, the heavy mineral data of 56 samples from the East Fukang slope were collected from the Xinjiang oilfield and previous published results (Ji et al., 2014).