This article containing silicon element gold, gold-containing waste liquid and chemical treatment of some gold alloys are described below. 1. Recovery of gold in gold-containing silicon electronic waste parts The gold-containing silicon-containing components that are discarded in electronics industry products and equipment hinder the recovery of gold due to the presence of silicon. In order to recover gold by the wet process, it can be treated with a silicon etchant to separate the gold sintered on the silicon wafer, and then collected and sent for purification. Silicon etchants are acidic and basic. The acidic silicon etchant is prepared according to nitric acid: hydrofluoric acid 1:6-9, diluted to 2 to 3 times, and immersed in silicon at room temperature. The alkaline silicon etchant uses 10% to 30% NaOH solution and is heated to 80-100 ° C to digest the components to remove silicon. Second, the withdrawal of Koka alloy scrap Kovar alloy gold-plated scrap is a waste product produced in the electronics industry. Common methods for recovering gold from such waste materials are: Nitric acid etching method. It etches the alloy matrix by dilute nitric acid, so that the gold plating layer is loosely detached into gold powder for recycling. Since this method corrodes the alloy matrix, the matrix is ​​often unusable. Cyanide etching method. In this method, a concentrated solution of 75 to 200 g of lanthanum NaCN (or KCN) is used, and gold is eluted at 85 ° C or higher. Anti-imitation salt (m-nitrobenzoic acid) or other additives should usually be added to the immersion liquid during the operation. Gold entering the solution is typically recovered using a zinc displacement process. Iodine etching method. This method uses an aqueous solution of KI:I 2 = 1 :2.1 and adds a catalyst KIO 3 0.5 g ∕L. The gold-plated waste parts are first treated with acetone, and then added to the immersion liquid at room temperature for 1 to 1.5 hours. The base after de-golding can be used for re-plating. If the gold in the immersion liquid is recovered by electrolysis, it can be electrolyzed by a graphite cathode at a cell voltage of 2 V for 40 to 60 minutes. Electrolytically, solution I - will be oxidized on the anode I 2, the gold extraction solution can be reused for return demetallization. Electrolysis method. The electrolytic gold withdrawal of the corroded gold-plated parts is usually a non-corrosive medium. If the alloy substrate has no other defects, it can be re-plated. The test cell uses a rigid polyvinyl chloride tank or a porcelain tank, the anode is drilled with a polyvinyl chloride basket, and the cathode is a stainless steel plate. The electrolyte contains CN2~3g/L, which can be prepared by itself. It can also use gold-plated waste liquid with citric acid, ammonium citrate and tartrate, or silver- plated waste liquid after replacing silver with zinc powder. During the operation, the cell voltage increases with the increase of current density. When the current density is 1.0-1.5A∕dm 2 , the corresponding cell voltage is about 0.9-1.3V, and a satisfactory de-golding effect is obtained. If the surface of the de-gold alloy is required to be smooth and easy to be re-plated, or gold-plated or silver-plated waste liquid is used as the electrolyte, in order to avoid dilution and increase the liquid volume, the waste liquid may have a higher CN - concentration. Third, the treatment of gold-containing alloys There are many types of gold-containing alloys, which are widely used in various industrial sectors. Waste materials, corners or debris of these alloys are used in all sectors where these alloy materials and components are used and manufactured. The method of recovering precious metals from these waste materials has the method adopted by the Brinston factory. For alloys containing high gold (20% to 50%), low silver (less than 35%) or no silver, it can be directly treated by electrolysis. Alloys containing low gold may also be treated by acid leaching. Only the aqua regia treatment method containing gold alloy is introduced here. (1) Gold- platinum alloy. First dissolved in aqua regia, add hydrochloric acid to evaporate to the syrup, diluted with distilled water, add saturated ammonium chloride solution to make platinum precipitated ammonium chloroplatinate, and then calcined into crude sponge platinum. The filtrate was reduced with ferrous iron . (Ii) gold iridium alloy. It is a refractory metal, preferably it is heated at 600-750 ° C with sodium peroxide (or simultaneous addition of caustic soda) under constant stirring for 60-90 min to melt. After melting, the melt was poured onto an iron plate to form a sheet, which was cooled and then leached with cold water. At this point, a small amount of sodium salt of strontium enters the solution, and most of it remains in the leaching slag. The dilute hydrochloric acid is poured into the leaching residue to heat and dissolve the hydrazine, and the mixture is filtered, and the chlorination of the chlorination gas to the filtrate is carried out to make it tetravalent. Further, a saturated ammonium chloride solution was added to form a precipitate of ammonium chloroantimonate, which was calcined to obtain a crude sponge. The insoluble slag of the mash is treated with aqua regia, and the gold in the filtrate is reduced with ferrous iron. (3) Gold, palladium and silver alloys. It is first treated with dilute nitric acid (acid: water = 2:1), and the filtrate is treated with hydrochloric acid to precipitate silver. Pd(NO 3 ) 2 in the raffinate is complexed with ammonia, acidified with hydrochloric acid, and reduced with formic acid to produce powdered palladium. The gold in the nitric acid insoluble slag is recovered. (Iv) gold or a gold palladium boron boron palladium-bismuth alloy. First, heat it with dilute aqua regia (acid: water = 1:3), and slowly heat to evaporate to remove the sputum. After cooling, a little hydrochloric acid was added to wet, and the water was heated and heated to leaching palladium. After filtration, ammonium chloride chloropalladate was prepared by adding ammonium chloride to the filtrate, and calcined to a crude sponge palladium. The residual liquid after palladium is reduced with gold by ferrous iron. (E) gold arsenic, antimony or bismuth alloy of gold and antimony. After boiling and dissolving with dilute aqua regia (acid: water = 1:3), gold is then reduced from the filtrate. (6) Gold borogal alloy. After boiling and dissolving with dilute aqua regia (acid: water = 3:1), gold is reduced from the filtrate. 4. Recovery of gold from gold-containing waste liquid The gold-containing waste liquid includes cyanide waste liquid, chlorinated waste liquid and aqua regia waste liquid. And a variety of washing water. The gold-containing cyanide solution is usually replaced by a zinc powder (zinc wire or zinc block). Gold chloride solution was heated substitution method is more copper wires (or chips). The gold-containing aqua solution is, in most cases, reduced using an inexpensive and easily prepared aqueous solution of ferrous sulfate or ferrous chloride. Of course, the gold in these waste liquids can also be recovered by activated carbon adsorption, ion exchange, or even solvent extraction. The NaBH 4 method is also effective. Various gold-containing washing waters can also be used in principle to recover gold from the replacement or reduction method. 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