The extraction of gold by washing or dressing alone using a pan or batea is the oldest recovery process employed by the man. The recovery of gold was used in civilized countries and the main disadvantage was the gold loss, which was around 40-50%. This problem was partially solved when gold panning was coupled with amalgamation. In California, gold prospectors used a pan to test gold-bearing rock and to extract the finest gold on a small scale. It was made of black sheet iron, usually Russian sheet iron; in Australia the pan was generally made of sheet tin. In Mexico and South America a wooden dish in the shape of a flattened cone 16 inches in diameter and 2 inches deep was known as batea. Similarly shaped wooden dishes were used by uncivilized or semi-civilized tribes in some parts of the world (e.g. Borneo, Malay Penninsula, and Africa).
The gold pan was used in prospecting for gold in cleaning gold-bearing concentrates and in the hand-working of very rich deposits. It is a shallow pan which varied from 15 inches to 18 inches in diameter at the top, and from 2 inches to 2 ½ inches in depth, the sides having a slope of about 30o. it weighed from 1 to 1.5 kg. Most the time, the pan was made of heavy-gauge steel with the rim turned back over a heavy wire to stiffen it. Where amalgamation was to be done in the pan, it was either made of copper or had a copper bottom. When used by a skilled operator, it has a capacity of from half a yard to 1 yard in 10-11 hours.
The object of panning was to concentrate gold and heavy minerals by washing away the lighter. To do this most efficiently, all material should be of as even size as possible. The pan was filled about three quarters full of gravel to be washed, and then it was submerged in water. The first large gravel was picked up by hand, then the clay was broken, up, after which the operator raised the pan to the edge of the water, inclining it slightly away from him, moving it with a circular motion combined with a slight jerk, thus stirring up the mud and light sand and allowing it to float off. This was continue until only the heavier material remained, such as gold, black sand and other minerals having a high specific gravity. These concentrates were stored until a large quantity was obtained, after which the gold is separated from them. It was picked out by hand, amalgamated with mercury, sometimes in a copper-bottomed pan. In some case where the separation was extremely difficult and the quality and quantity justified, the concentrates were shipped to a smelter. Basically, panning was learned by watching an old miner or experienced operator at work, learning certain tricks in the trade from him. A clean six or eight inches frying pan made an excellent prospecting or clean-up pan. It was well to burn out an iron pan after having used mercury in it, and then polish it with a soft rock or piece of brick, otherwise it was difficult to see small colors or flakes of gold.
The batea was cone-shaped and was the equivalent of the pan. Basically, it was made of wood or sheet metal. It varied from 15 to 24 inches in diameter and had an angle from 150o to 155o at the apex. Many prospectors claimed that wood could hold fine gold better than metal. A shallow wooden chopping bowl was used as a substitute for the batea. This was used in the same manner as the pan.
Pan Batea
