I. Factors influencing the application of bacterial leaching to a Canadian uranium ore

Conclusions

In the bacterial leaching of Elliot Lake ore, the over-all extraction rate that can be obtained is determined mainly by the particle size of the leach feed. On sizes coarser than 4 mesh, where 32 weeks or more is required to reach a uranium extraction of 70%, the extraction rate is related mainly to the rate at which the solutions penetrate the particle to depth. Since this relationship is logarithmic in nature, the time taken to extract appreciable amounts of uranium is increased greatly for a moderate increase in particle size. Regardless of the particle size, the over-all uranium extraction rate is increased when the iron concentration in the leach solution increases. The addition of nutrient improves the leaching rate for particles coarser than 8 mesh.

The relatively slow leaching rates observed on the coarser particles in this work would necessitate the crushing of the ore to about 10 mesh if bacterial leaching were used as a primary method of treating the Elliot Lake ores. However, it might have an application in the treatment of coarsely crushed ores which could not be treated economically in any other way.

Bacterial leaching will extract 70–80% of the uranium contained in the tailings from the treatment of Elliot Lake ore by flotation. The use of bacterial leaching would appear to be of considerable interest in applications such as this, where it is employed to supplement more intensive recovery methods.