Microbial Consortia for enhanced Copper Recovery

Important results from the project

Biomining is a more environmentally friendly metal extraction process from e.g., sulfidic ores that exploits ‘acid loving’ microorganisms and is typically performed in massive, engineered heaps for the dissolution of copper minerals. However, commercial biomining of chalcopyrite (the largest remaining copper resource in the world) is not extensively employed due to slow metal release and limited copper recoveries. This project’s primary goal was to test two methods for increased chalcopyrite dissolution efficiency in pilot scale.

Expected long term effects

Designed consortia of ‘acid loving’ microbes that showed good laboratory scale copper extraction efficiencies and the concentration of chloride that inhibits ‘strong iron oxidizers’ such as Leptospirillum species were identified. Two bioheaps were then constructed that are presently producing copper at a similar rate such that it is too early to give a definitive answer to which best releases copper. The project’s results are then hoped to be tested in even larger scale in industrial copper biomining.

Approach and implementation

The project’s overarching goal was to test two hypotheses for increased dissolution of copper from chalcopyrite ore in bioheaps via maintaining a culture of ‘weak iron oxidizers’ that more efficiently release copper from the ore and the addition of chloride to selectively inhibit the growth of ‘strong iron oxidizers’ that counterintuitively reduce copper release. To achieve this, experiments were performed at increasing scales to take the hypotheses from laboratory reactors, through medium sized column bioreactors, to pilot bioheaps.