Oxidative Dissolution of Low-Grade Ni-Cu Ore and Impact on Flotation of Pentlandite

Musuku, Benjamin; Saari, Eija; Dahl, Olli

doi:10.3390/min12111406

Cited by 2 publications

(10 citation statements)

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“…These dissolved metals serve as catalysts, enhancing the rates of surface oxidation reactions. Consequently, the increase of this simple index should indicate a tendency for enhanced mineral surface oxidation [3]. Figure 2a compares the T/pH index to plant performance, and Figure 2b the distribution of sulphur species in the process water.…”

Section: Total and Dissolved Calcium And Magnesiummentioning

confidence: 99%

“…Then, the quality of the recycled process water is also characterized by the increased concentration of dissolved metals and higher-oxidation state sulphur compounds. A more detailed study at the Kevitsa plant also showed that the change in the quality of the recycled process water resulted in a clear increase in the surface oxidation of sulphide minerals during grinding, which then apparently reduced the flotation recovery of pentlandite [3]. Given the context, the rationale for this work arises from the question: how much do these significant changes in mineral surface oxidation during grinding affect the chemistry of the aqueous phase of the pulp just prior to flotation.…”

Section: Introductionmentioning

confidence: 98%

“…In a closed process water loop, the process water quality increasingly changes with the number of loops and seasonal temperatures. Recent studies have shown, e.g., a cyclic pattern for water parameters such as conductivity, pH, redox potential, metals, and sulphur oxyanion species [1][2][3]. In particular, the possible impacts of thiosalts on the flotation of sulphide minerals have been widely studied by numerous researchers [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

“…At Kevitsa mine, the weak flotation performance of pentlandite during the warm summer months has been related to the changing properties of the recycled process water [2]. Not only does the temperature of the recycled process water increase towards the warm summer months, but the temperature increase also speeds up oxidation reactions in the tailings pond during the summer months, resulting in a significant drop in the pH of the recycled process water [3,11]. Then, the quality of the recycled process water is also characterized by the increased concentration of dissolved metals and higher-oxidation state sulphur compounds.…”

Section: Introductionmentioning

confidence: 99%

“…Therefore, the study focused on the following plant streams: recycled process water, mill discharge, and hydrocyclone overflow. This study was based on previous findings showing that in the warm season, extensive oxidation of pentlandite minerals occurs before the flotation process begins [3]. It is expected that changes in the aqueous phase composition caused by oxidative dissolution of sulphide minerals can be verified with this approach.…”

Section: Introductionmentioning

confidence: 99%

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Influence of Water Quality on Sulphide Ore Oxidation and Speciation of Sulphur Anions during Autogenous Milling

et al. 2023

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Earlier studies at the Kevitsa Cu-Ni concentrator plant have indicated that seasonal variations of the properties of the process water affect the oxidation of the surface of the minerals, and further, the pentlandite flotation performance. However, it is not clear whether the differences in flotation performance are solely due to changes in the mineral surface oxidation, and/or also due to surface oxidation-induced changes in the aqueous phase of the pulp. This paper investigates the effects of the mineral surface oxidation of Kevitsa Cu-Ni ore on the properties of the aqueous phase of the slurry. A systematic study was formulated to monitor the surface oxidation related changes in the mill circuit of the Kevitsa concentrator plant. The study was timed to coincide with a seasonally observed drop in the concentrator plant’s flotation performance, which happens during the summer months (June, July, and August). Both physicochemical parameters, as well as sulphur oxyanions in the plant process water, mill discharge, and hydrocyclone overflows were monitored. Also, the bubble size in selected rougher and cleaner cells was monitored. The results show that season-related changes in mineral surface oxidation cause clear differences in the aqueous phase chemistry of the mill circuit. The increased concentration of reduced sulphur species in the mill discharge is an indication of extensive oxidation of the ore during milling. Also, the bubble size of the flotation cells reacts to the observed seasonal change. The findings of the study confirm that the consequences expected, based on the theory of mineral surface oxidation, are observable downstream in the aqueous phase of the milling circuit. Based on these results, it is not yet possible to say whether the poor flotation performance is caused solely by the oxidation of the mineral surface or also by the properties of the aqueous phase of the slurry after milling. However, the results show that the plant needs both to find ways to limit oxidation rates in the summer, and to consider installing a more robust frother, capable of maintaining efficacy during the warm season. The findings of this study may help the plant to develop ways to enable a timely response to changes in the recycled process water quality, to prevent harmful impacts on pentlandite flotation. The former could be achieved by lowering the temperature of the process water and flotation air, whereas the latter could mean using a different frother.

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Section: Total and Dissolved Calcium And Magnesiummentioning

confidence: 99%

Section: Introductionmentioning

confidence: 98%