Industrial Application of Bacterial Iron Oxidation In-Situ Recovery of Uranium
Abstract
The technology of bacterial iron oxidation during in-situ recovery (ISR) of uranium has been developed and proposed for industrial use. The technology has been confirmed by the results of pilot tests at a uranium mine in Kazakhstan for 12 months. The aim of the research was to develop a technology for bacterial iron oxidation during underground «in-situ» recovery of uranium based on a new type of flow bioreactors. Two bio-technological installations with a volume of 20 m3 bioreactors installed in 40-foot containers were developed. Bioreactors with strapping, air compressors, pumping station and control and measurement equipment are installed in the geo-technological field and connected to the underground borehole uranium in-situ recovery main system. The capacity of the plants was more than 150,000 m3 / year for leaching solution. After passing the leaching solution through bioreactors, the redox potential of the solution rose from 360 mV to 430-450 mV in the flow mode. The content of trivalent iron increased from 0.1 g / l to 1.5 g / l and higher. The process of bacterial oxidation of iron was carried out at a solution temperature of 10-120C (the optimal is 25-350C), which made it possible to eliminate energy consumption for heating the solution. The test results showed an increase in the uranium content in the productive solution by 10-20 % after passing the leaching solution through the ore-bearing layer for 1 month. This confirmed the potential of using the technology for underground borehole in-situ recovery of uranium. The economic costs of using the technology are 6-8 times lower than when using chemical oxidizers (hydrogen peroxide). For the first time, the obtained industrial results open up new prospects for the application of bio-technological methods for underground borehole in-situ recovery of uranium and other metals.
