2023 Fiscal Year Research-status Report
Development of a waste-on-waste environmentally friendly process to recover cobalt, nickel, and copper from slag using pyrrhotite-rich flotation tailings
| Project/Area Number |
23K19023
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| Research Institution | Akita University |
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Principal Investigator |
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| Project Period (FY) |
2023-08-31 – 2025-03-31
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| Keywords | cobalt / copper / recovery / roasting / low temperature / phase conversion / leaching |
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| Outline of Annual Research Achievements |
The main purpose of this research was to develop a new process that involves the co-extraction and recovery of Co, Ni, and Cu from flotation tailings and Cu-Ni smelter slag material, while simultaneously removing these heavy metals for a reduced environmental loading.
In this regard a low-temperature roasting and atmospheric leaching experimental conditions were successfully established while using low-grade copper-cobalt ore in the experiments. The sample had a metal content similar to mining waste and thus provided a convenient way to conduct preliminary studies.
Since this research aimed on lowering the energy requirement of roasting, a low roasting temperature of 180 °C was achieved through the addition of sodium metabisulfite additive, yielding more than 90% copper and cobalt extraction from the low-grade sample.
The established preliminary roasting conditions, also confirmed the conversion of ferrous Fe phase to ferric iron, in this form iron can be easily removed in a stable solid form for safer environmental disposal considerations.
In the next research stage, the optimized roasting conditions will be applied to the mining waste material (tailings and slag) to extract copper, nickel, and cobalt, and remove these heavy metals before safe disposal of this mining waste.
The results of this preliminary research were presented at the International Symposium on Earth Science and Technology (CINEST 2023) in Fukuoka, Japan.
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| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
A slight delay in the progress of research was encountered because of challenges in obtaining and shipments of mine waste (flotation tailings) from a copper-nickel mine from overseas into Japan. These challenges were successfully resolved, and the flotation tailings were received at Akita University, Japan. Nonetheless, the delay was usefully utilized, as the preliminary studies still progressed using a comparable ore sample while waiting for the sample’s arrival. The experimental conditions obtained from the preliminary study will be applied to the mining wastes in the next research phase.
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| Strategy for Future Research Activity |
Conduct further roasting experiments using flotation tailings and smelter slag and employing the selected experimental conditions from the preliminary study. The tailings will be added in place of, or with an additive e.g. sodium metabisulfite or sodium sulfate to enhance the sulfation of metals and obtain highly soluble mineral phases.
Leaching experiments will be conducted on the roasted products under simple atmospheric conditions using water or a very dilute acidic solution.
Metal elution tests of the leach residues will be done to ensure a reduced environmental loading of the waste generated.
The results of this research will be presented in at least 2 domestic conferences because the current results are insufficient to apply for an international conference as initially planned.
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| Causes of Carryover |
Due to a slight delay in the research as a result of delayed arrival of flotation tailings sample, the purchasing and use of experimental consumables was also not as frequent as initially planned.
Therefore, the amount carried over will be used to purchase the required research consumables such as roasting additives (sodium sulfate, etc), experimental utensils such as sample bottles, pipette tips, etc.
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