2017 Fiscal Year Research-status Report
ガルバニックマイクロエンカプセレーション―酸性鉱廃水の発生抑制のための新しい方法
| Project/Area Number |
17K12831
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| Research Institution | Hokkaido University |
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Principal Investigator |
タベリン カーリット 北海道大学, 工学研究院, 助教 (60626125)
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| Project Period (FY) |
2017-04-01 – 2019-03-31
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| Keywords | galvanic interaction / pyrite oxidation / acid mine drainage |
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| Outline of Annual Research Achievements |
The most important achievements of this study to date are as follows:
1. pH is an important parameter for galvanic interaction to occur; that is, the extent of this process is more substantial under slightly acidic conditions.
2. Between metallic aluminum and zero-valent iron, we observed that the latter was more effective in suppressing pyrite oxidation.
3. Addition of phosphate in the pyrite and zero-valent iron system produced iron-phosphate coatings on pyrite that limited its oxidation.
4. Formation of iron-oxyhydroxide precursor minerals like schwertmannite was observed between 3 and 4, which could be a promising way of forming protective coatings on pyrite.
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| Current Status of Research Progress |
Current Status of Research Progress
2: Research has progressed on the whole more than it was originally planned.
Reason
Although suppression of pyrite oxidation occurred via galvanic interaction using metallic aluminum and zero-valent iron, this effect was only temporary because a protective coating was not formed. The biggest difficulty that we encountered was the strong effects of pH not only on galvanic interaction but also on the formation of the coating. To put it simply, acidic conditions favored galvanic interactions but limited coating formation. Similarly, higher pH enhanced the precipitation of metallic oxides that could be used as a coating material, but galvanic interaction became negligible. To solve this conundrum, we are planning to use phosphate to induce coating formation and also evaluate the potential of schwertmannite, an iron-oxyhydroxysulfate mineral stable under acidic conditions.
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| Strategy for Future Research Activity |
We are evaluating the mechanisms involved in the suppression of pyrite oxidation by metallic particles and why coating formation was very limited. Our approach is to do batch leaching experiments coupled with electrochemical studies. Also, we are doing experiments to understand how phosphate and zero-valent iron suppressed the oxidation of pyrite. Finally, we are trying to evaluate whether it is possible to apply the phosphate and zero-valent iron system directly during ball milling to induce the formation of a hydrophilic coating on pyrite and limit its floatability during flotation. Finally, we are looking for other potential materials like bimetallic particles as well as coating materials like metal-phosphates and silicates, which are also sometimes stable under a wide range of pH.
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| Causes of Carryover |
We did not buy a UV-Vis spectrophotometer as originally planned because we got one from another laboratory, so about 1 M JPY will be used for the procurement of a new flow-through column setup that will be used for stability tests of treated residues. The rest will be used to attend conferences and to buy consumables like filters, pipette tips, sampling bottles and sampling tubes as originally planned.
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