CLARIFICATION OF A FILTRATE FROM A PRECIOUS METAL EXTRACTION PLANT (LA3)

ISSUE

Following some process modifications, a precious metals extraction plant encountered filtration problems at the hydrometallurgy pretreatment sector. This step rendered chemical species that made the next step - filtrate clarification on a filter-press, almost impossible. Moreover, the species also caused more filtration problems at the subsequent gold retrieval step.

STS Canada was assigned a design engineering to optimize the filter's performances that ensure the removal of the undesired species.

TECHNOLOGICAL CHALLENGE

Submit a filtration method that would provide the means to clarify the filtrate from the belt filter, down to a concentration lower than 10 ppm in suspended particulate matter. The proposal would also have to use the plate filter on site.

RECOMMENDED SOLUTION

Laboratory testing made it possible to:

• Select an efficient flocculant (which was already in use at the location) and to optimize its dosage
• Select a filter aid to improve the cake's properties
• Select an appropriate filter media with small enough pores to get a clearer filtrate (<10ppm)
• Validate the process parameters that would allow the use ofthe onsite plate filter

RESULTS

Recommendations for the plate filter modifications, i.e. floculant and filter aid quantity, filter media type, allowed to get the desired filtrate clarity (10 ppm) at the belt filter located further into the clarification process (hydrometallurgy sector).