Tackling Tailings: Repurpose and Remediation

XPRIZE

A likely goal for the Zero-Waste Mining XPRIZE is the complete elimination of tailings.

One possible approach to tackling tailings is repurposing and/or remediation of tailings after the mining process.

What are some recent innovations that are attempting to repurpose and remediate tailings? What barriers to widespread implementation are they encountering?

Why hasn’t this issue been dealt with already? What important aspect of the issue isn’t being worked on?

Share any ideas, links, articles, or projects that you have seen!

DavidPoli

In the course of our research we've heard about companies that have experimented with creating construction materials out of tailings, but they've had difficulty doing it economically. What are some pros and cons of this kind of technology? What other solutions are out there?

BryanNamba

In addition to hearing about creation of new materials, it would also be interesting to hear to what degree other valuable metals/minerals (other than the primary metal/mineral the mine is for) are extracted from tailings currently.

SimonJowitt

Tailings are currently reprocessed for gold (e.g. in the Witwatersrand in South Africa), zinc, copper, all sorts. Our recently publications have highlighted that there are a lot of tailings around the world that contain significant amounts of potentially extractable metals, either because of initially inefficient processing or because the original mining wasn't focused on metals that have subsequently become critical to our way of life (e.g. indium). Although the extraction of these metals doesn't remove the tailings issue, it could be a profitable or at least cost neutral way of dealing with tailings. Equally, some tailings ponds naturally sequester CO2 (e.g. http://www.largeigneousprovinces.org/14oct). It depends on the materials being mined in many ways - and characterisation of tailings is therefore very important.

BryanNamba

@SimonJowitt Thank you for sharing this information and the link to the C02 article! It's very helpful.

cedwards

Our concept for repurposing and remediation of mine tailings revolved around using talings high in silica, melting the tailings using concentrated solar thermal (CST) energy into a basic form of glass as a substrate for CST mirrors, and using those mirrors to increase the solar thermal energy available in a beneficial feedback cycle. The subsequent growth in CST can then be used for electrical energy generation, and/or for more direct solar thermal processing of tailings, all performed at the mine site. In addition to the production of glass for solar energy mirrors, we envision the high silica content tailings being processed into a highly valued sorbent material called MCM-41. We have identified core research in CST melting of high silica content tailings into glass, and in the production of MCM-41. It turns out that even with other impurities, up to some level the tailings can be effectively and directly melted to make glass and MCM-41, without pre-separation steps. Glass is a good material to produce from tailings because it will help trap a number of the most polluting elements into the long lasting glass matrix. Any MCM-41 sorbent produced can be directly used in the mine for pollution mitigation, with the option to sell it on the market.

Granted this approach may only work well with a subset of mines and types of minerals mined, given the need for tailings with significant percentage of silica. Maybe the idea can spark some other ideas that will work for a greater number of mines and extracted mineral types.

We have science paper references and more detailed information for anyone that may be interested - just leave a message in this thread.

RPSINGH

One of our student Ms. Saba Sarin did her doctoral on this topic recently and demonstrated clearly that flyash can be put back in AMD-prone worked out areas of an opencast colliery to reduce pH to such a level that it start supporting vegetation .

DavidPoli

@cedwards Your work with CST and MCM-41 sounds fascinating. We'd very much like to see more detailed information. Thanks! And @RPSINGH, we will for sure look into Ms. Sarin's work.

cedwards

@DavidPoli Here's a concept brief we created for submission to the GoldCorp Disrupt Mining 2019 challenge, in which we made the semi-finalist round.
https://drive.google.com/file/d/1a7MppYK0nhe8bEUIWwRPvIsgBx8195eh/view?usp=sharing

Let me know if the link doesn't work for you. Some of the references are really key to understanding the viability of the proposal. Here are a couple of news articles about the challenge, the semi-finalist submissions, and our submission:

https://goldcorp.com/English/investors/news-releases/news-release-details/2019/Six-Semi-Finalists-to-Showcase-at-DisruptMining-Innovation-Expo/default.aspx

https://canada.businesschief.com/technology/3106/Canada's-Envisioning-Labs-and-Hydrostor-Inc-among-Disrupt-Mining-2019-semifinalists

DavidPoli

@cedwards The link works! Thanks for the references. We'll review and let you know if we have any questions.

santosr

We are turning mining tailings, steelmaking slag and CO2 into bricks, mortar and paint. It is a protoyping project that started earlier this year, and that I intend to carry forward to disseminate awareness about possibilities with waste and CO2 valorization.
Pardon the bricklaying of our first prototype, below.

DavidPoli

@santosr Thanks for bringing your expertise to our community! At this point in our process, learning more about different concepts and technologies for waste valorization is very important in order to help us decide whether our prize (or any potential future prize) will focus on that stage in the mining value chain.

Did you mean to post a picture of your prototype? It doesn't appear to have worked. Could you provide any links to descriptions or papers about your technology? Any further information will be greatly appreciated!

santosr

I will try again:

NickAzer

Thank you @santosr @cedwards @RPSINGH @SimonJowitt! We have a new discussion on zero-footprint mining - we would love to see any input you might have there!

rossguenther

Ceramext™ technology has developed a newly patented hot-forging processes that can repurpose mine tailings and other waste materials into advanced impermeable high strength patented ceramic compositions. Many new patented ceramic compositions are derived from waste materials including reservoir sediments, mine tailings, quarry fines, biomass ash, garbage incinerator ash, and coal fly ash. These waste materials, without using binders, can produce high quality floor, wall and roof tiles, building cladding, bricks, pavers, and other ceramic products suitable for marketing at competitive prices.

Climate change and increased populations have made it challenging to maintain some reservoir water capacities due to the need for sediment removal and lack of disposal sites. In California, more than 100 reservoirs can no longer be dredged due to mercury contamination in mine tailings exacerbated by dredging. The fine sands and silts from the sediments, whether dredged or dry mined when the reservoir is periodically drained, can be turned into patented high quality ceramics using Ceramext™ technologies. At the temperatures necessary for Ceramext production, mercury is volatile and can be safely recovered in the kiln flues using activated carbon filters in the vapor phase.

For more information on this technology see www.ceramext.com

DavidPoli

@rossguenther Thanks for your intro to the technology! We'll read a little more and let you know if we have any questions.