WATER MANAGEMENT
constituents at non-toxic levels are needed .”
Through rigorous testing and treatment process evaluation for a recent greenfield project , BQE Water developed and is implementing an ion exchange system to meet the end-of-pipe total cyanide target of < 10 ppb . In this system , most of the removed cyanide is recycled back to the metallurgical process . “ The ability to implement treatment ahead of the actual need is key . In stark contrast to this , BQE was retained to provide emergency response treatment services involving a fast-tracked temporary system to turn cyanide heap leach solution into nontoxic water for environmental discharge . The system combines the site ’ s equipment not designed for the intended purpose , with off-the-shelf rental equipment . While the effluent discharge criteria are similar in both projects , the inability to plan caused the cost of the temporary system to escalate such that in less than a year , the cost of the emergency response exceeded the estimated ‘ life cycle ’ cost of the planned treatment expected to operate for decades .”
In addition , while the use of reverse osmosis in the temporary system lowered the concentrations of most toxicants below the respective discharge limits , meeting effluent toxicity criteria consistently proved to be complex . “ The industry can leverage BQE ’ s expertise and experience from these two projects to holistically assess the best options for minimising risks and costs of managing water and cyanide throughout the project life cycle .”
He also says that the industry wide adoption of BQE ’ s disruptive non-biological selenate removal technology , Selen-IX™ , continues with a fifth plant built in less than four years . The technology removes selenium below 1 ppb and produces stable solid residue suitable for re-use . Concurrently , new semi-passive biological systems were installed at other sites . Kratochvil : “ However , unlike with Selen-IX , the biological systems lack proof of the long-term stability of selenium solids trapped inside these systems which are designed to remove selenium from water initially but eventually turn into selenium solids waste storage repositories in perpetuity . Regulators assessing environmental risks now consider time horizons of hundreds of years prior to issuing approvals and / or setting bonds .”
To help clients better understand long-term risks associated with selenium re-dissolution from semi-passive systems , BQE Water completed a study and published a peerreviewed article identifying biochemical pathways towards selenium re-mobilisation . The empirical evidence of selenium re-dissolution was subsequently obtained using selenium biosolids from an active biological treatment system . “ Selecting the best solution for managing selenium in mining projects can be a complex task and requires access to state-of-the art research data and technology . The ability of Selen-IX to eliminate concerns about long-term solids stability is an important consideration .” IM
International Mining | MARCH 2025