Quarrying & Mining Magazine

Silica harvested from geothermal waste

This article first appeared in Q&M‘s April-May issue.

Australian company Environmetals (EVM) is investigating the feasibility (including production costs) of producing commercial silica from geothermal power generation. PETER OWENS reports.

Environmetals has operated two pilot plants here and one in Japan aimed at recovering marketable amounts of colloidal silica.
The Kiwi pilot plant was based on the Contact Energy Wairakei geothermal field from February 2014 to September 2015 and processed over 25,000 tonnes of geothermal fluid from the feed stream of the binary power station. More importantly, it also produced more than one tonne of colloidal silica that was shipped as samples to potential customers here and in Japan and England. Reports indicate that these samples were well received.
While the Wairakei plant was closed in September 2015 another pilot plant was operated at the Norske Skog pulp and paper mill site on the Kawerau geothermal field. Environmetals says trials will continue at Kawerau on various fluid streams over the next few months to provide data for final design of the proposed first commercial-scale plant treating 5000 tonnes per day of geothermal fluid.
These pilot plants have not gone unnoticed. In January 2015, Japan’s Geothermal Energy Research & Development (GERD) visited NZ to learn more about Environmetals’ silica extraction technology. In October last year GERD applied to its government for an Environmetals trial extraction plant at the Kakkonda power station in Japan.
The board of Environmetals is well-known in the Australian and New Zealand minerals industry. The chairman is Bill Turner who ran several successful mining companies in Australia and Africa. Another Australian director, Peter Bradford, manages the big Perth-based miner Independence Group NL and has run, or helped manage, other companies in Australia, Canada and Africa, while a third director is Adam Peren who has had 30 years’ involvement in NZ’s financial markets. John Lea, a New Zealander and the managing director of Environmetals, is also a chemical engineer.

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