There are two kinds of gold panning: gold in the river and gold in the ore.
The pollution in the river is not too much , the gold in the sand, after pumping, filtering, precipitation can get a certain purity of gold, but to get much more pure gold, will add some nitric acid, and etc. for reaction.
The minerals are crushed into sand, fed with mercury (which sticks to gold) and then heated with nitric acid.
Gold diggers scoop up silt from rivers or lakes and wash it in pans to find natural gold. Gold rush used to be a means to get rich in the eyes of many adventurers. There have been several gold rush waves in history.
In mercury alchemy, miners dig out gold-bearing ore by grinding the ore, grinding the ore powder on an iron wheel, and using the principle of specific gravity to separate the gravel from the gold sand by hand with water. This is just a gold panning process. The process of alchemy is more complicated. The gold sand must first be “adhere to gold” with mercury, using a “physical reduction process”.
To separate gold and sand by using mercury, and then gradually fire, recovery of mercury, both environmental protection and cost savings, and then add several times of silver, gold replacement, finally heated to 1300℃, and then the pure gold solution into the gold mold made of pure gold bars. However, some gold mining and alchemy plants can directly release toxic wastewater and waste containing mercury into natural water, causing pollution around and downstream.