Some mine or factory production of gold, silver products, refined gold and silver is not finished, but not high fineness of coarse gold, silver or coarse gold and silver without isolation of crude gold. Since these products are not directly sold in the unit for purification, it is necessary to carry out smelting ingots.
The casting of crude gold, crude silver and high-quality gold can be carried out by referring to the above-mentioned melt casting method of finished gold and silver ingots. However, since these semi-finished products or intermediate products contain more base metal impurities, in order to remove most or a part of the impurities by smelting as much as possible to increase the content of gold and silver, the amount of flux and oxidant added should be appropriately increased during the casting, and smelting The time should also be extended appropriately. The specific operation should be increased or decreased depending on the raw material.
After the crude gold and the combined gold are oxidized and slag removed and the slag is removed, the metal liquid surface generally does not have a burning block to remove oxygen. Although they also condense gas when they condense, and there may be bubbling on the surface of the ingot, but a large amount of fine metal balls are not carried out due to a large amount of gas being ejected, causing splashing loss. Casting, in order to isolate the slag, may be added to the crucible, a gate to the grass to adsorb slag level I, and cast in a preheated to a level above 100 ℃ cast iron mold. After the ingot is condensed, poured asbestos board, excluding flash burr weighing storage. Since the crude gold and the combined gold ingot also contain a considerable amount of base metal such as silver and copper , the cast ingot does not have to be acid immersed to avoid affecting the appearance.
The crude silver usually contains no gold or gold. The wood and grass handles should be added to the metal surface of the crucible before casting to remove some of the dissolved oxygen in the silver liquid to prevent a large amount of gas from escaping when the ingot is condensed, resulting in silver. Splash loss.
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