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Characterization of structure-function properties relevant to copper-activated pyrite depression by different
Madan Kumar Chapagai1, Brenton Fletcher2, Michael J Gidley1
1Centre for Nutrition and Food Sciences, Queensland Alliance for Agriculture and Food Innovation, The University of Queensland, St Lucia, Queensland 4072, Australia.
Carbohydrate Polymers
|April 14, 2023
Summary
Oxidized wheat starches effectively depress copper-activated pyrite during flotation. These modified starches, unlike normal wheat starch or high-amylose wheat starch, enhance solubility and surface binding, improving mineral extraction efficiency.
Area of Science:
- Mineral Processing and Extractive Metallurgy
- Materials Science
- Polymer Chemistry
Background:
- Flotation is crucial for ore mineral extraction, with starch acting as a depressant for copper-activated pyrite.
- Understanding the structure-property relationships of starches is key to optimizing this process.
Purpose of the Study:
- To investigate the adsorption and depression properties of various wheat starches on copper-activated pyrite at pH 9.
- To establish structure/function relationships for normal wheat starch (NWS), high-amylose wheat starch (HAW), dextrin, and oxidized wheat starches.
Main Methods:
- Comparison of adsorption isotherms and flotation performance with kinematic viscosity, molar mass distribution, surface coverage, and functional group analysis.
- Evaluation of oxidized starches (peroxide and hypochlorite treated) alongside NWS, HAW, and dextrin.
Main Results:
- Oxidized starches, despite minor differences in molar mass and functional groups, showed improved solubility, dispersibility, and surface binding compared to NWS and HAW.
- While NWS, HAW, and dextrin adsorbed more at high concentrations, oxidized starches were more effective depressants at the low concentrations used in flotation.
- Effective depression relies on stable chelation between Cu(I) and starch ligands.
Conclusions:
- Oxidized wheat starches are superior depressants for copper-activated pyrite at pH 9 due to enhanced surface binding and chelation.
- Modification of starch, particularly oxidation, offers a pathway to improved selectivity in flotation processes.
