Rare Earth Minerals recovery from mining waste

A rather negatively-oriented article recently highlighted the developments in the Rare Earth Mineral industry in China. Unfortunately the article is rather light on technical details, choosing to highlight the environmental impacts. According to the article there have been many ‘pirate’ operations extracting Rare Earth Elements (REE), and extraction techniques include in situ leaching where chemicals are pumped into soil to dissolve and extract the elements from the soil. It is mentioned that other extraction techniques are in use and under development with lower impacts.

As posted earlier, LKAB in Sweden is studying the recovery of REE from iron ore tailings, and NW Russia have existing commercial operations doing this. The waste chemical mentioned in the article on China, “ammoniacal nitrogen” sounds like a potential resource for fertiliser production, or at least can be treated in an analogous manner to the treatment of sulphate in mining waste water being studied in the SEESIMA project WP5.

An article with more technical detail on the Chinese REE industry can be found here, This article focuses on the ion absorption type of REE deposits, which are only found in China. Although only representing less than 3% of China’s REE deposits, they have a higher content of medium and heavy REE and simpler extraction, being easily extracted by ion exchange with ammonium sulphate solutions. This is the basis for the in situ leaching processes, which avoided the environmental impact of open excavation.

Experimental work on sulphate reduction underway

Breakdown of sulphur-containing minerals often results in the release of sulphate (such as with acid mine drainage). One way to combat the environmental problems that this causes is to use certain types of bacteria that reduce the sulphate back to sulphur or sulphide compounds.

Sulphate reduction and metal sulphide removal experiments are going on at the University of Oulu. Sulphate reducing bacteria are cultivated in bottle scale and tested for utilization of KemiCond treated sewage sludge and succinate. At the same time synthetic mining water is treated, and iron is recovered as FeS. Furthermore, tests with other low-cost carbon sources and real mining waters, as well as reactor experiments are planned to be started in the autumn 2019.

sulphate reduction experiment over 2 weeks
Sulfate-reducing bacterial consortium cultivated in synthetic mining water at 6 °C with succinate as a carbon source.
continuous flow reactor for sulphate reduction experiments
Continuous up-flow reactor built up for biological sulfate reduction experiments

For more details, contact Hanna Virpiranta

Resources about mining for schools

An EU EIT Raw Materials project is developing a “briefcase” of resource material for school teachers to introduce the importance of minerals for society.

The Briefcase project brings the opportunity to learn more about minerals through hands-on experience. The specific target audience will be primary schools which include from 6 to 14-year-old students and their teachers. The project is orientated for Wider Society Learning (WSL) and aims to raise students’ knowledge of mining activities and mineral applications.

The Briefcase of mineral applications - educational resources
The Briefcase of mineral applications – educational resources

The aim of the project is to raise awareness of minerals knowledge among children during their visits to the museum. A real briefcase that contains minerals and products was created in 2003 to help students recognise mineral ores and their uses in daily life.

Read more here

New EU project on bioleaching

Recently a new EU innovation project, ‘BioLeach’, was launched, with funding from EIT Raw Materials and project partners from Slovakia, Italy, Hungary, Spain, Germany, Poland, Portugal and Ireland. The project is led by Dr Darina Štyriaková, of the Faculty of Mining, Ecology, Process Control and Geotechnologies of the Technical University of Košice in Slovakia. The aim of the project is to develop biotechnologies to achieve ecological exploitation, improve the quality of local minerals and reduce the European countries’ dependence on imported minerals.This includes the study of bioleaching. More details about the project can be found here:

Bioleach project participants
Participants in the EU Bioleach project

Visit to Bangor University

Bangor University

In February 2019 Dr. Tiina Leiviskä and MSc. Hanna Virpiranta made a visit to Bangor University in Wales, U.K. to collaborate with Prof. David Barrie Johnson’s group: “Bangor Acidophile Research Team” (BART). Hanna stayed there for two weeks working alongside with other visiting and post-doctoral researchers of the team. She acquired a lot of knowledge of e.g. operating sulfate-reducing bioreactors, plating of anaerobic microbes, and conducting bioleaching experiments, that she can exploit in her further research.

The Bangor Acidophile Research Team (BART) is based in the School of Biological Sciences at Bangor University. The group performs research on microbes which inhabit extreme environments, earning them the nickname ‘extremophiles’. The research has a particular emphasis on highly acidic environments, which has relevance for the SEESIMA project for the leachate of acid mine drainage and biomining. The research work is concentrated on the following areas

  • commercial mineral leaching operations (‘biomining’)
  • acid mine drainage
  • geothermal areas
  • acidic industrial wastewaters

The research activity focuses on the microbiology and molecular biology of these acidic environments, and the research group also develops novel bioengineering solutions for remediating acid mine drainage and industrial wastewaters.

The December 2011 issue of Scientific American listed Biomining as one of ten ‘world-changing ideas’.

LKAB investing in tailings valorisation

LKAB are planning to invest 45 million kronor in pilot plants for recovery of phosphorus and Rare Earth Minerals (REE) from the waste rock from their iron ore mining operation. This development was announced on 20 February 2019, read more here

The pilot plant trial is based on the CleanMAP process developed by Easy Mining, a daughter company of the waste treatment company RagnSells. Details of the CleanMAP process are given here. This seems to be based on the US Patent 8658117 B2, which however only refers to “known processes” for the digestion of apatite with sulfuric acid, hence presumably the traditional use of concentrated sulfuric acid. This patent does not mention the procedure for separation and purification of the rare earth elements. An example of a method to recover rare earth elements from digestion of apatite with strong acid is given in the patent by Genkin et al US 1001 1891.

Kick-off Meeting In Oulu

participants in SEESIMA kick-off meeting
Kolarctic CBC Seesima Kick-off meeting at University of Oulu, 22 Nov 2018

The formal kick-off meeting was held in Oulu on the 22-23 November 2018, with a nominal project start date of 15 Oct 2018.

On the first (half) day the project administration was gone through with the Kolarctic Management Authority representatives.
On the second day the project workplan was discussed in detail to prepare a operational plan.