Master of Science
Hart, Brian. R
Linnen, Robert. L.
As grades of new base metal deposits decline and environmental restrictions on their extraction, increase, the mining industry is looking for new methods of processing minerals. This thesis, investigates the manner in which an aliphatic nitrile (TECFLOTE S11) is adsorbed onto the surface of sulphide mineral surfaces, to understand how TECFLOTE S11 can improve the extraction of base metals from their ores.
Bench tests, including micro-flotation, were conducted and their products examined by Time of Flight – Secondary Ion Mass Spectrometry (ToF-SIMS) to establish where the TECFLOTE S11 was adsorbed onto the mineral surface. The tests showed that the adsorption of TECFLOTE S11 onto chalcopyrite was greater than on to pyrite surfaces. While the results did not provide a definitive model for the adsorption of TECFLOTE S11 on sulphide mineral surfaces, a number of attachment mechanisms are proposed.
Summary for Lay Audience
When copper is extracted from its ore, the extracted rock is crushed and ground to the consistency of coarse flour, before it is pulped with water to create a slurry. Specialized chemicals called collectors are added to the slurry. The collector alters the surface chemistry of the copper mineral surface so that it does not mix well with water, which is called hydrophobic. When air is blown through the slurry, the now hydrophobic copper mineral, adheres to the air bubbles and floats to the surface of the slurry. This process is called froth flotation.
For almost a century, the mineral processing industry, has relied on sulphur-based chemicals called xanthates, to be the workhorse collector in the flotation of copper minerals. In 2018, a new family of collectors (TECFLOTE) were introduced to improve the efficiency of the flotation process and produce a higher copper content to the finished product. TECFLOTE is different from xanthates in that the sulphur atoms are replaced by a carbon atom that is triple-bonded to a nitrogen atom, which is called a nitrile.
Bench tests involving various methods of mixing the TECFLOTE chemical with copper sulphide (chalcopyrite) minerals were conducted and the surface of the sulphide mineral examined by Time of Flight-Secondary Ion Mass Spectrometry (ToF-SIMS) to determine the adsorption of TECFLOTE on the mineral surface. ToF-SIMS, bombards the surface with ions from a heated bismuth source, to eject ions from the surface being examined. The time for these secondary ions to reach a detector is measured and the ions identified because lighter ions travel faster than heavier ions.
The investigation determined that TECFLOTE, adsorbs onto the chalcopyrite in quantities larger than the amount that is adsorbed onto iron sulphide (pyrite) surfaces. This difference in adsorption allows chalcopyrite to be selectively separated from pyrite and produce a high-grade copper end-product. The investigation also found that the method of introducing the TECFLOTE to the slurry affected its adsorption on the chalcopyrite surfaces, which permitted a model of the adsorption mechanism of TECFLOTE to be developed.
Holness, Trevor, "An investigation of the adsorption mechanism of an aliphatic nitrile (TECFLOTE S11) on sulphide mineral surfaces." (2020). Electronic Thesis and Dissertation Repository. 7507.
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