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Mineralogical and leaching characteristics of altered ilmenite beach placer sands

Mineralogical and leaching characteristics of altered ilmenite beach placer sands

  • Authors: Ramakokovhu, Munyadziwa Mercy , Olubambi, Peter Apata , Mbaya, Richard Kady Kadiambuji , Mojisola, Tajudeen , Teffo, Moipone Linda
  • Date: 2020
  • Subjects: Ilmenite , Characterization , Leaching
  • Language: English
  • Type: Article
  • Identifier: http://hdl.handle.net/10210/464080 , uj:41443 , Citation: Ramakokovhu, M.M. et al. 2020. Mineralogical and leaching characteristics of altered ilmenite beach placer sands.
  • Description: Abstract: In order to have a good understanding of the treatment process and improvement on the market value of ilmenite beach placer sands, knowledge of its mineral composition and phase distribution is fundamental. In this study, a combination of characterization techniques including high-resolution scanning electron microscopy (HR-SEM), high-resolution transmission electron (HR-TEM) microscope, and X-ray diffraction (XRD) techniques was used to understand the mineralogical characteristics of ilmenite beach placer sands obtained from Richards Bay, South Africa. The mineral phase constituents of the ilmenite beach placer sands were studied before pre-oxidation and additive leaching in a chloride environment. During observations using XRD and HR-SEM, the ilmenite beach placer sands exhibited signature rhombohedral crystal form and crescentic pits with evidence of alteration phases. The characterized pre-oxidized ilmenite showed the presence of a ferric oxide film deposit of the particles. The leaching characteristics of both raw and pre-oxidized ilmenite was studied in the presence of additives. The leaching efficiency of the pre-oxidized ilmenite in the presence of additives increased by 20% at atmospheric conditions. The characterized residues show the improved amenability of pre-oxidized leach in chloride media. The formation of new phases containing pseudo-rutile indicated crystallographic disintegration by the movement of atoms during dissolution. Some particles retained the crescentic pit and the subangular grain structure; however, the phase changes were observed at the grain boundaries and grain edges. The leached residue’s EDS results still indicated the presence of pseudo-rutile and some minor unreacted oxides such as SiO2, Al2O3, and other trace metals. The trace metals impurities present in the as-received ilmenite were reduced by 80% in the final residue after the leaching.
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Sintering of nanostructured titanium carbonitride from carbonitrothermic reduced ilmenite

  • Authors: Mojisola, Tajudeen
  • Date: 2019
  • Subjects: Sintering , Nanostructured materials , Titanium , Nitrides , Ilmenite
  • Language: English
  • Type: Doctoral (Thesis)
  • Identifier: http://hdl.handle.net/10210/418221 , uj:35451
  • Description: Abstract: In recent years, there has been concerted effort towards the synthesis of cermet materials from low grade titanium ore. This is because the reserve of high grade titanium containing ore, i.e. natural rutile, is fast depleting and rutile becoming more expensive across the globe. Today, titanium containing hard ceramic powders, e.g. TiC, TiN and their solid solution TiCN powders have become important reinforcement materials due to their suitable properties. Titanium carbonitride, which is a boundary solid solution of titanium carbide and titanium nitride combines the excellent properties of both TiC and TiN in one structure of TiCN. In order to make this special material readily available, various methods have been adopted to synthesize titanium carbonitride powder. Although, the synthesis of titanium carbonitride by carbothermic reduction of titanium dioxide (rutile) with carbon under nitrogen atmosphere has been the most widely used for the commercial production of titanium carbonitride. However, this process requires the extraction and purification of titanium dioxide from its ore e.g. ilmenite, which itself is a costly process, or the use of natural rutile, which is fast depleting and becoming more expensive across the globe. Ilmenite (FeTiO3), which is a mineral source of titanium dioxide, is abundantly found in many parts of the world, most especially in South Africa. South Africa, is a leading producer of ilmenite in the world, accounting for about 37% of 6.2 million metric tons of the global production. Hence sourcing and processing of TiCN powder directly from South African ilmenite will be an added advantage. It is on this premises that the urgency for the processing of South African ilmenite to its final products, e.g. titanium containing hard ceramic products, such as TiC, TiN and/or TiCN powders or composite, and titanium metal, is being hung. Hence, this study develops a mechano-chemical processing route for the synthesis of titanium containing hard ceramic powders from ilmenite concentrate, which could be used for the production of cutting tools made of TiC and TiCN composite materials. The study also determines the possibility of sintering bulk TiCN based cermets with different metal matrices. For the synthesis of titanium carbide and titanium nitride/carbonitride powders, mixtures of ilmenite concentrate and graphite were milled in a planetary ball mill (PM 100) for different time intervals of 0, 30, 60 and 120 min, and carbo(nitro)thermally reduced under argon and nitrogen gas in a high temperature laboratory furnace (Thermal Tech., USA), respectively. These carbo(nitro)thermic reductions of mixtures of ilmenite concentrate and graphite result in the formation of Fe –TiC and Fe – TiCN powder composites in which globules of TiC and TiCN particles are embedded in the iron matrix,.. , Ph.D. (Engineering Metallurgy)
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