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Some gold is extracted from gold ore, and another is extracted from electronic waste such as mobile phones and computer motherboards. So, how is gold extracted? Here we will introduce the method of refining gold precious metals. At present, the concept of gold refining is mainly to remove impurities, improve the purity of gold, and meet the quality standards to meet the requirements of market transactions. At present, the main methods for gold refining include chloride purification, aqua regia purification, electrolysis purification, chloramine purification, etc.
1. High temperature chlorination refining process:
The crude gold is melted in the smelting furnace, and then chlorine gas is passed into the roasting body. Due to the different chemical affinities of various metal impurities (Fe, Zn, Pb, Cu, Ag, etc.) with chlorine, the impurities are selectively chlorinated and removed. To purify gold.
This process has a wide adaptability range to the composition of the alloy, but the control of the chlorination process (chlorine gas dosage, time, temperature, ventilation speed) is difficult to accurately control, and the product quality is difficult to stably meet the standards; secondly, a small amount of gold will volatilize during the chlorination process , causing the loss of gold; in addition, for raw materials with low gold content, it is very uneconomical to apply this method.
2. Purification process of aqua regia:
Use aqua regia for impure gold (purity >90% gold). Dissolve to generate chloroauric acid. Use sodium bisulfite as the reducing agent to reduce the chloroauric acid into gold powder and precipitate. Then purify, wash, dry, add flux and smelt at high temperature to obtain a golden yellow color, reaching pure gold. Craftsmanship. This technology has low investment, simple process, low cost and high gold recovery rate.
