By Jack Caldwell - Mining Engineer - Robertson GeoConsultants

Here is a conundrum for those interested in heap leach pad operation. My questions arise from this report in a Zambian newspaper:

Over 3,000 residents of Mufulira’s Butondo township have resolved to take Mopani Copper Mines to court over the acid mists the company has continued to release from its Heap Leaching Mining Project in Mufulira, affecting their health. Residents of Mufulira’s Butondo area on Thursday last week started moving children to other towns to protect them from the acid mists released by Mopani’s Heap Leaching mine that is allegedly affecting their health. Butondo Section E community spokesperson Agness Nkonde said the acid mists the residents were exposed to were unbearable. Nkonde said parents feared that the acid mists might cause serious health complications, especially to children.ZEMA said it would not hesitate to close Mopani Copper Mine’s MufuliraWest Heap Leaching Mine if investigations being undertaken reveal that they had been releasing acid emissions indiscriminately without following the recommended exposure limit. ZEMA Northern Region manager Patson Zulu said the authority is currently investigating and tests were being undertaken to ascertain the levels of acid mists Mopani was releasing to the environment, particularly to the affected residents of Butondo section E.

Thus the question: how do you operate a heap leach pad so that it emanates potentially detrimental acid fumes? Or put another way, what should you do at your heap leach pad so that you do not emit acidic fumes that might affect neighbours?

Is it the heat of Africa that causes dripping lixiviant to turn to mist and waft away over nearby townships? Are they spraying the fluids instead of dripping them?

I have not hitherto come across this problem with heap leaching. Please email me to help us understand and help others avoid a similar issue elsewhere.