The Influence of chemical pre-treatment on particle fracture pattern and mineral liberation

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2018
Camalan, Mahmut
The conventional approach in mineral beneficiation is to increase ore fineness for achieving sufficient degrees of mineral liberation. However, achieving finer products requires higher grinding energies, and finer products generate problem in slurry flow at further processing steps. Then, the emphasis should be given to foster breakage along grain-boundaries between minerals, so that sufficient liberation can be achieved without excess breakage. The purpose of this study is to assess if the aqueous species can make surface complexes at the grain boundaries to promote grain-boundary fracturing, and consequently chromite liberation. For this purpose, chromite ore samples were treated under water, dilute surfactant and electrolyte solutions at varying pH and temperature. The treated samples were broken in drop-weight tester, and then the liberation spectra and mass distribution of the resultant progenies were evaluated with the ones of untreated feed. Besides, some microscopic and spectroscopic tools were used to find evidence for structural changes at the grain boundaries in the case of improved liberation. Results show that hydrolysis of silicates tends to improve grain-boundary fracturing since it preferentially dissolves Si-layers which are located near to or at the grain-boundary regions. However, protonation tends to remove Mg-layers in silicates and hinder grain-boundary fracturing since Mg-layers are accumulated at the bulk texture. Aqueous salt and surfactant species enhance grain-boundary fracturing, and consequently chromite liberation if they form surface complexes and dissolve Al-layers at the grain boundaries. Grain-boundary fracturing yields exposed chromite surfaces and enriched chromite content in coarser progeny classes.

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Citation Formats
M. Camalan, “The Influence of chemical pre-treatment on particle fracture pattern and mineral liberation,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.