Enthalpy of adsorption of MBT, MBO and MBI and modified MBT onto pyrite surfaces: A computational and experimental approach

P. P. Mkhonto, X. Zhang, B. McFadzean, J. Taguta, P. E. Ngoepe

Research output: Chapter in Book/Report/Conference proceedingConference contribution

1 Scopus citations

Abstract

The adsorption of heterocyclic collectors such 2-mercaptobenzothiazole (MBT), 2-mercaptobenzoxazole (MBO), 2-mercaptobenzimidazole (MBI) and their derivatives on pyrite form a basis in understanding the flotation reactivity that may be applicable in a wide range of sulphide minerals. This study uses a computational and experimental approach to determine the heat of adsorption of MBT, MBO, MBI and modified MBT collectors onto pyrite surfaces. Computational calculations found that the adsorption energies were in the order: MBO > MBI > MBT. The heterocyclic collectors were adsorbed in their thiolate form on the surface. In the case of the pyrite (100) surface, the MBT adsorbed through the exocyclic sulphur atom, while MBO and MBI adsorbed through the exocyclic sulphur and N atoms onto the 5-coordinated Fe atom. The (111) surface was found to be more reactive and different adsorption mechanisms were predicted, where the MBT exocyclic sulphur atom bridged on the 5-coordinated Fe and surface 2-coordinated sulphur atoms, while the N atom adsorbed on the 5-coordinated Fe atom. In the case of MBO and MBI, dissociation of the exocyclic sulphur atom from the collector occurred with subsequent interaction with the surface 5-cordinated Fe and 2-coordinated S atoms. This resulted in the collector carbon atom adsorbing on the surface 2-coordinated S atom, while the N atom adsorbed on the 5-coordinated Fe atom. The adsorption of the modified MBT was found to be more exothermic than the MBT, which showed that introduction of a -CS 2 group on the exocyclic sulphur atom improved the affinity of MBT on the surface, and was thus a better flotation collector. The computational results were supported by experimental enthalpy of adsorption measurements and microflotation tests. The chemistry of the heterocyclic thioamides is complicated by the fact that they can exist in a number of tautomeric and ionic forms at different pH's. This is discussed in relation to the flotation and calorimetric data.

Original languageEnglish (US)
Title of host publicationIMPC 2018 - 29th International Mineral Processing Congress
PublisherCanadian Institute of Mining, Metallurgy and Petroleum
Pages1787-1797
Number of pages11
ISBN (Electronic)9787030227119
StatePublished - 2019
Externally publishedYes
Event29th International Mineral Processing Congress, IMPC 2018 - Moscow, Russian Federation
Duration: Sep 17 2018Sep 21 2018

Publication series

NameIMPC 2018 - 29th International Mineral Processing Congress

Conference

Conference29th International Mineral Processing Congress, IMPC 2018
Country/TerritoryRussian Federation
CityMoscow
Period9/17/189/21/18

Bibliographical note

Publisher Copyright:
© IMPC 2018 - 29th International Mineral Processing Congress. All rights reserved.

Keywords

  • Computational modelling
  • Enthalpy of adsorption
  • MBI
  • MBO
  • MBT
  • Microcalorimetry
  • Modified MBT collectors

Fingerprint

Dive into the research topics of 'Enthalpy of adsorption of MBT, MBO and MBI and modified MBT onto pyrite surfaces: A computational and experimental approach'. Together they form a unique fingerprint.

Cite this