Control of grinding conditions in the flotation of chalcopyrite and its separation from pyrite
Introduction
It has been known for a long time that grinding conditions have a significant influence on the subsequent flotation of sulphide minerals. For chalcopyrite flotation, there is agreement that mild steel grinding medium results in a lower chalcopyrite recovery than stainless steel grinding medium in the presence or absence of collectors Rao et al., 1976, Forssberg et al., 1988, Van Deventer et al., 1991. The depression of chalcopyrite flotation by mild steel medium was attributed to the iron hydroxide species on chalcopyrite surface, which was closely related to the anodic iron oxidation (Yelloji Rao and Natarajan, 1988). The rate of anodic iron oxidation was found to decrease by nitrogen purging during wet grinding of chalcopyrite minerals (Natarajan, 1996). However, whether nitrogen purging during grinding with iron grinding media can improve chalcopyrite flotation needs to be confirmed.
Although mild steel grinding medium is detrimental to chalcopyrite flotation, it is favoured for chalcopyrite selectivity against pyrite. Yuan et al. (1996) found that chalcopyrite selectivity against pyrite was reduced when the minerals were ground in an oxidising environment with a stainless steel medium, but was restored when ground in a reducing environment with mild steel medium. A similar observation was found by Van Deventer et al. (1991). Clearly, it is desirable to investigate the effect of grinding with low iron content media on chalcopyrite separation from pyrite. Yuan et al. (1996) also indicated that air-sparged mild steel grinding gave no advantage in selectivity compared with ordinary mild steel grinding. However, oxygenation during conditioning and flotation is considered an important factor in the selectivity of flotation operations. As reported by Houot and Duhamet (1990) and Kuopanportti et al. (2000), oxygenation had a favourable effect on the separation of chalcopyrite from pyrite and the oxygen demand increased with the proportion of pyrite in mineral systems.
In this study, a specially designed mill which allowed the control of chemical conditions during grinding was used. The effects of two types of iron media, mild steel and 30 wt.% chromium (with approximate 70 wt.% iron), and three types of purging gases (nitrogen, air and oxygen) on chalcopyrite flotation and chalcopyrite separation from pyrite were investigated.
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Materials and reagents
Chalcopyrite and pyrite samples were obtained from Willyama, Earth History Supplies, NSW, Australia and Huanzala Mine, Peru, respectively. The samples were crushed through a rolls crusher and then screened to collect the +0.6−3.2 mm particle size fraction. The processed samples were then sealed in polyethylene bags. The chemical composition of these samples analysed by ICP-MS is shown in Table 1.
Two types of grinding media were used. The tapered cylinder mild steel grinding medium was supplied
Effect of grinding conditions on chalcopyrite flotation
The effect of grinding media and gas purging on chalcopyrite flotation is shown in Fig. 1. It can be seen that 30 wt.% chromium medium produced a higher chalcopyrite recovery than mild steel medium. This is consistent with reports in literature that mild steel medium depresses chalcopyrite flotation Rao et al., 1976, Forssberg et al., 1988, Van Deventer et al., 1991. Meanwhile, for both mild steel and 30 wt.% chromium grinding media, gas purging had little effect on chalcopyrite flotation.
The
Conclusion
Grinding conditions had a significant effect on chalcopyrite flotation. This effect was closely associated with the presence of iron oxidation species and metal deficient sulphide present on the chalcopyrite surface. Iron oxidation species from grinding media played a dominant role in depressing chalcopyrite flotation, whilst the presence of metal deficient sulphide improved chalcopyrite flotation. As a result, 30 wt.% chromium medium produced a higher chalcopyrite recovery than mild steel
Acknowledgements
Financial support for this work from AMIRA International as well as scholarships to Y. Peng from the University of South Australia are gratefully acknowledged. Pasminco Mining, Elura, Australia and Magotteaux, Australia are thanked for the supply of grinding media.
References (22)
- et al.
Interaction between finely ground galena and potassium amylxanthate in flotation: I. Influence of alkaline grinding
Int. J. Miner. Process.
(1990) - et al.
Effects of galvanic interaction on collectorless flotation behaviour of chalcopyrite and pyrite
Int. J. Miner. Process.
(1997) - et al.
Effect of oxidation on collectorless flotation of chalcopyrite
Int. J. Miner. Process.
(1997) - et al.
Influence of different grinding methods on floatability
Int. J. Miner. Process.
(1988) - et al.
Importance of oxygenation of pulps in the flotation of sulphide ores
Int. J. Miner. Process.
(1990) - et al.
A model of conditioning in the flotation of a mixture of pyrite and chalcopyrite ores
Int. J. Miner. Process.
(2000) - et al.
XPS and FTIR study of the influence of electrode potential on activation of pyrite by copper or lead
Colloids Surf., A Physicochem. Eng. Asp.
(1999) Laboratory studies on ball wear in the grinding of a chalcopyrite ore
Int. J. Miner. Process.
(1996)- et al.
Measurement of oxidation in a base metal flotation circuit by selective leaching with EDTA
Int. J. Miner. Process.
(1996) Surface layers in base metal sulphide flotation
Min. Eng.
(1991)
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