Accelerated Carbonization Could Make Mining Waste
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An international group of scientists recently carried out experiments that allowed them to attain an equivalent of roughly 30 years of passive carbonation of mine tailings in a 4-week period.
In a paper that was published in the Economic Geology journal, the scientists state that the sped up process of carbonation on the tailings increases the carbon capture for environmental benefit significantly and could possibly retrieve valuable battery metals.
The lead author of the study, who is also a researcher at the Australian Nuclear Science and Technology Organization, Jessica Hamilton, stated in a media statement that the integration of carbon capture with the recovery of minerals such as cobalt and nickel would make some lower grade mines more operational.
The team of researchers carried out two experiments for their research.
The first involved tailings from an asbestos mine that were partially saturated having a direct reaction with mining flue gas that contained 10% carbon dioxide in dinitrogen.
On the other hand, the second experiment involved the researchers using laboratory columns to simulate a heap leaching treatment. Irrigating the tailings from the mines using acid caused the minerals to dissolve and produce a solution that was both rich in calcium as well as magnesium. This in turn, reacted with the carbon dioxide to form solid carbonate minerals.
This analysis used an X-ray Fluorescence Microscopy to provide visible microscopic proof of the distribution of trace minerals and any important changes to the microstructure after irrigating them using diluted sulfuric acid.
The X-ray Fluorescence Microscopy (“XFM”) showed chromium, iron, nickel, manganese and cobalt at different depths in the column. The strongest concentration of these metals was in the area where the pH of the sulfuric acid leaching solution was neutralized.
Hamilton stated that the XFM allowed the researchers to see the distribution of different elements at a fine-scale in addition to observing the concentrated geochemical environments where the minerals were precipitating and the coatings on grains.
It should be noted though that the approach one would like to use is dependent on the available resources as well as the local mineralogy.
Heap leaching is a good option if one does not have active brucite but there is waste acid available. If you have both a carbon dioxide source and brucite, then you can try the reaction with the gas. The best part about it, though, is that the two options can be used together.
The acid that is produced in mines or during mineral processing as a by-product can also be used and neutralized.
These techniques are suitable for waste from diamond, platinum, copper, chromite, some nickel as well as documented chrysotile mines.
It would be interesting to hear the comment of Bullfrog Gold Corp. (CSE: BFG) (OTCQB: BFGC) (FSE: 11B) regarding the commercial-scale practicality of this new method of salvaging minerals from mine waste.
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