Michelle McCann was the guest speaker in our class last week. She came to tell us about her life as a metallurgical engineer, particularly her job at Newmont. At Newmont, she is doing and loving being on the field as a metallurgical engineer, something she thought she never would do. Her job dealt with getting gold out of waste. She told about the way that they get gold out of low level ores and ores with organic carbon. This process is called bio-oxidation. Bacteria break down the ore, allowing the gold to be collected later. The conditions that must exist for these bacteria to survive is oxygen, a temperature above 60ºF, and food... ferrous sulfate. There were a few different ways of breaking down the ore. The first is bio-CN, treatment of the ore with a cyanide solution to collect the gold after bio-oxidation. Bio-thio is the treatment with a sodium thiosulfate solution to allow the gold in the ore with organic carbon to be harvested. The last was direct thiosulfate, again to harvest from the ore with organic carbon. She said these methods were very low cost ways to get gold out of waste ore. I found these methods interesting, using living creatures to get minerals out of the ground. I figure that fewer chemicals are needed to get the gold, so there is less chance of pollution, and danger to the surrounding environment.