Novel approach for processing complex carbonate-rich copper-cobalt mixed ores via reverse flotation
Novel approach for processing complex carbonate-rich copper-cobalt mixed ores via reverse flotation
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DOI：
10.1016/j.mineng.2020.106710
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发表时间：
2020-11
影响因子：
4.8
通讯作者：
Q. Dehaine;L. Filippov;I. Filippova;L. Tijsseling;H. Glass
中科院分区：
文献类型：
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作者：
Q. Dehaine;L. Filippov;I. Filippova;L. Tijsseling;H. Glass
目前全球钴的主要生产来源绝大多数来自刚果民主共和国铜钴沉积物矿床的开采。随着氧化表生矿化的逐渐枯竭，许多作业逐渐开始在深部开采硫化矿。氧化物和硫化物之间的过渡区的矿石通常同时含有氧化物和硫化物矿化，这极难通过常规浮选进行处理。这些混合矿石单独通过浮选处理是复杂的，因为碳酸盐矿物，如白云石和菱镁矿，可能占脉石的很大比例。因此，混合矿石通常通过浮选硫化物，然后使用控制电位硫化（CPS）进行氧化物浮选，并通过酸浸进行进一步加工。与富含碳酸盐的混合矿石相关的主要挑战是钴的回收率低，主要是由于钴存在于氧化物矿物中，碳酸盐脉石矿物的可浮性，其可占精矿的50%，以及与CPS的工业应用有关的技术困难。本研究调查了经典的两步CPS浮选路线的替代方案，包括在中性或酸性pH下碳酸盐脉石的直接反浮选，以及两步组合硫化物反浮选路线。后者包括在中性pH下的硫化物浮选阶段，随后是在pH 4.5-5下的酸性反浮选阶段，提高了铜和钴的总回收率。使用油酸钠以及磷酸和硫酸的混合物（比例为4：1）进行反浮选可获得最佳性能。总的Cu-Co回收率分别达到93.5%和85.1%。据推测，磷酸通过表面钝化作为铜钴氧化物矿物的助熔剂，同时使菱镁矿和白云石能够选择性浮选。需要进一步研究磷酸对这些矿物浮选的影响。总的来说，结果表明，在硫化物浮选之后，酸性反浮选阶段增加了总体铜钴回收率，同时产生了适合于通过浮选或酸浸进一步处理的精矿。因此，建议的组合方法可能是铜-钴氧化物-硫化物混合矿石浮选厂中上述CPS阶段的可行替代方案，特别是在混合矿石含有显著比例的碳酸盐脉石矿物的操作中。
The vast majority of current global production of cobalt from primary sources originates from extraction of Cu-Co sediment-hosed deposits in the Democratic Republic of Congo. With the progressive depletion of oxidic supergene mineralisation, many operations are progressively starting to extract sulphide ore at depth. Ore in the transition zone between oxides and sulphides usually hosts both oxide and sulphide mineralisation which is extremely difficult to process by conventional flotation. These mixed ores are complex to process by flotation alone because carbonate minerals, such as dolomite and magnesite, may represent a significant proportion of the gangue. Hence, mixed ores are usually processed through flotation of sulphides followed by oxide flotation using controlled potential sulphidisation (CPS) and further processing via acid leaching. The main challenges associated with carbonate-rich mixed ores are the low recovery of cobalt, mostly due to cobalt present in oxide minerals, the floatability of the carbonate gangue minerals, which can make up to 50% of the concentrate, and technical difficulties with regards to industrial application of CPS. This study investigates alternative options to the classic two-step CPS flotation route, including direct reverse flotation of the carbonate gangue at neutral or acid pH, as well as a two-step combined sulphide-reverse flotation route. The latter, including a sulphide flotation stage at neutral pH, followed by an acidic reverse flotation stage at pH 4.5–5, increased the overall copper and cobalt recoveries. The best performance is achieved with reverse flotation, using Na-Oleate and a mixture of phosphoric and sulphuric acid (ratio of 4:1). Overall Cu-Co recoveries of 93.5% and 85.1% respectively were achieved. It is postulated that phosphoric acid acts as a depressant of the Cu-Co oxide minerals through surface passivation while enabling selective flotation of magnesite and dolomite. Further investigation into the effect of phosphoric acid on flotation of these minerals is required. Overall, the results suggest that, following flotation of sulphides, an acidic reverse flotation stage increases the global Cu-Co recovery while producing a concentrate which is suitable for further processing by flotation or acid leaching. Hence, the suggested combined approach could be a viable alternative to aforementioned CPS stage in Cu-Co oxide-sulphide mixed ores flotation plants, especially in operations where the mixed ore contains significant proportions of carbonate gangue minerals.