This video covers biomining techniques, specifically bioleaching and bio-oxidation. But before we discuss these techniques, we go through the underlying mechanisms behind microbial metal oxidation/leaching by using Fe-sulfide oxidation as a prime example. Metal sulfide deposits contain valuable metals that we can collect through bioleaching, but only specific microbes are able to oxidize such metals and some of these microbes do a better (more efficient) job than others, so we study these microbial processes to pick the best species for biomining. Once we chose the most efficient microbial species for dissolving the target metal in a sulfide deposit, and we identify the metabolic needs of the species so we can maintain optimal bacterial growth, we can move forward with the bioleaching process by using either dump bioleaching or heap bioleaching (both discussed in the video). However, when using iron sulfide dissolving microbes in bioleaching, the runoff that is not collected often creates an environmental hazard known as acid mine drainage because the microbes are acidophiles (they grow best in acidic conditions) and the process they induce to dissolve the metal sulfide only increases the acidity, creating a highly corrosive and dangerous effluent. I talk more about the environmental concerns of acid mine drainage (AMD) in the video. Lastly, we briefly touch on everyone's favorite metal, gold (Au), and the biooxidation process necessary for obtaining such a refractory metal, and how biooxidation differs from bioleaching. Hope you enjoy! :)
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0:00 Fe oxidation (rusting)
2:00 steps of pyrite oxidation
5:25 how acidity affects pyrite dissolution
6:58 role of microbes in mineral dissolution
8:33 how microbes mediate pyrite dissolution
10:15 other microbes could do the opposite
11:24 direct vs indirect microbial role
12:17 role of EPS in microbial weathering
13:25 different microbes oxidize different sulfide minerals
14:02 acid mine drainage- environmental impact
15:28 what is bioleaching?
17:23 dump vs heap bioleaching
18:24 how we grow bacteria for bioleaching
20:42 we also use fungi for bioleaching
21:57 can we biomine gold?
23:18 upcoming videos & references!
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6 авг 2024
