MINTEK conducts Ozone research

With a history extending as far back as 1934, Mintek has become a leading provider of minerals processing and metallurgical engineering products and services to industries world-wide. Mintek is committed to innovation and world-class research and development expertise which is supported by a physical infrastructure of modern laboratories, pilot plants and workshops.

They offer an extensive range of products and services which provide the industry with proven solutions and capabilities.

Wendy van der Merwe, Principal Scientist in the Measurement and Control division of Mintek has been working on Ozone treatment for some time, and in mid 2010 installed equipment in order to research the feasibility of using Ozone for cyanide destruction, regeneration, and pre-oxidation.

"I wanted to look at feasibility of commercialising Ozone as a cyanide destruction technique” she comments. “Ozone has been used in the past but there has been little understanding of the chemistry and how to optimise the process. That’s how I became involved. We needed Ozone generators to produce the Ozone required for our tests, and Ozone Service Industries were forthcoming and demonstrated a strong competence in this area.” I dealt with both the MD Ian Wright and Plants and Projects Manager Jaco Coetzee who worked with me on the installation and operating of the Ozone product”.

Coetzee comments: “For the trials Mintek are using an Aquazone CD 2000 ozone generator capable of supplying 30 grams of ozone per hour. Bottled oxygen is being used as the feed gas and Mintek utilised their own mixing and dosing system for the trials. OSI also supplied a BMT ozone analyser for the trials to measure differing concentration of ozone levels”

Mintek funded the labour costs of the research as the output of the project is aimed at having a direct positive impact on the environment and the minerals industry, and OSI provided the ozone generator. “This is why we were able to do the Ozone feasibility project for cyanide destruction” explains van der Merwe. “I had old equipment in the past, but OSI were able to provide modern equipment in order to conduct the research. The equipment was installed mid last year, and has been used under test until now. We have written a paper where Ozone was used for pre-oxidation of gold ore. Gold mining companies are now mining refractory gold ore which requires pre-treatment to liberate ‘locked’ gold”.

Van der Merwe wanted to look at a three pronged approach for ozone use which would make commercialising the process more feasible; these being pre-oxidation, cyanide destruction and the potential complex procedure of the re-generation of free cyanide. “Cyanide is expensive - so regeneration is definitely beneficial” continued van der Merwe. “Water treatment is becoming increasingly important and topical. Environmental regulations are becoming stricter, and mining companies are being put under more pressure to treat their waste water. Ozone is a very strong oxidant and is environmentally friendly - most other cyanide destruction processes add something to the system, which can necessitate further treatment but Ozone does not. It also assists with the treatment of arsenic for example”.

There will be a paper detailing all the research conducted by Mintek scientists regarding their use of Ozone later this year.