Leandro Herrera

Biological process for sulfate and metals abatement from mine effluents

A biological process was developed, aimed at treating water containing 1–2 g/L sulfate, typical of effluents in diverse mining operations. The original inocula was adapted from sanitary fill culture, to reduce sulphate, utilizing hydrogen gas as energy source and carbon dioxide as sole carbon source. Cost analysis, when compared to a lactate process, indicated the superiority of the hydrogen process. Experiences with an experimental 1 L reactor led to reaction rates ranging from 32 to 83 mg/L per h. Degradation rates could be accelerated by increasing the feed sulphate concentration; however, this strategy is not feasible, because concentrating sulphate is a fairly expensive process. The suspended solids in the effluent had good sedimentation and flotation properties, giving a process with few postreactor separation processes, previous to environmental discharge. Process economic analyses for a typical mine operation indicate that sulphate, and consequently metals, can be removed from the effluent to an environmentally acceptable level by increasing the production cost of a pound of copper by a fraction of a USA

A new spectrophotometric method for the determination of ferrous iron in the presence of ferric iron

cent. The most sensitive parameter was not the cost of hydrogen gas at the plant site but a source of acid (H+). A process flow diagram was developed and the transport phenomena is currently being modeled to optimize gas transfer processes, postulated as the controlling step of the process.