How is Gold's atomic structure and bonding related to the separation techniques used to distinguish it from other substances?
I'm just confused on what I'm actually searching for, I have read so many blogs on Gold extraction, refinement, occurences and more topics, and either I'm skipping the important parts or the answer's just not there. What can I search to find what I'm looking for? The separation technique I chose is flotation, can someone lead me in the correct path and/or give me a few hints on what to start of with? Thanks in advance, much appreciated!
Answer
There are differences in gold extraction for different mines - depending on the chemical nature of the raw ore, the impurities present, the availability of resources etc.
A good example of gold extraction comes from the Super Pit mine in Kalgoorlie, Western Australia; their gold extraction process is outlined in their website Mineral Processing, which is outlined below:
Crushing and grinding: this is a physical process where the mined raw ore is crushed, ground and water added to make a slurry.
Flotation: chemicals are added to the slurry to remove everything other than gold and pyrite. Water is also removed at this stage. The slurry is agitated forming air bubbles, which then rise through the slurry, carrying mineral grains. From Introduction to Mineral Processing:
The ability of a mineral to float depends upon its surface properties. Chemical modification of these properties enables the mineral particles to attach to an air bubble in the flotation cell. The air bubble and mineral particle rise through the pulp to the surface of the froth or foam that is present on the flotation cell.
Roasting: water is re-added and the concentrated slurry is roasted to remove $\ce{SO2}$
CIL: or carbon in leach, chemicals are added to dissolve the gold and have close to pure gold precipitate on the carbon.
Elution: A mixture of caustic soda and cyanide is used to liberate the gold from the carbon.
For your specific request for resources about flotation, the example process below is for a sulphide copper ore containing iron bearing pyrite:
Suggested additional resources about flotation:
Froth Flotation – Fundamental Principles
A great resource is the book Handbook of Flotation Reagents: Chemistry, Theory and Practice (chapters are behind a paywall).
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