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Major gold-bearing waste, scrap and recycling methods

Source: website    AddTime: 2014/9/3    Hits:     Label:

1, gold plated pieces of waste water and rinse water (electrolysis, replacement method, adsorption)
2, aqua regia etching (reduction method, a precipitation method)
3, electroplating components, chemical plating elements (fire assay solution retreat, electrolysis, thermal expansion of the Act)
4, gold - antimony alloy, gold - silicon alloy, gold - molybdenum - silicon alloy, gold - boron - platinum alloy (roasting, leaching, dissolution method)
5, gold plaque, gold, statues, etc. (electrolysis, calcination method, etching method)
6, fountain pens factory throwing ash, jewelry factory, gold plant, such as throwing ash (pyrometallurgical smelting, wet separation)
7, the ancient building demolition waste, precious metal smelting workshop waste, gold smelting furnace demolition block (panning method, re-election, cyanidation)
8, all kinds of waste ceramics and toys (chemical stripping, electrolysis, cyanidation, aqua regia dissolution method).

Second, gold - aluminum recovery of gold
An aqueous solution of hydrogen iodide and iodine can be leached into the solution of the gold selective, and then he recovered from the solution, the leaching process is carried out under 40-70 degrees, leachate from 100 parts of water, 1 - 10 parts of iodide hydrogen, and 1 - 10 parts of iodine composition, the leaching solution is heated to distill out the iodine, and precipitate gold.

Three: from the golden - platinum alloy of gold
According to gold and platinum are insoluble in nitric acid, sulfuric acid, and soluble in aqua regia characteristics, dissolved in aqua regia, platinum chloride recovered by separation, then the recovery of gold from the solution treated, the procedure is: the gold platinum alloy into the acid vessel, adding aqua regia, the metal dissolution, evaporation, nitrogen gas until the time to make the solution was cooled, filtered and the filtrate and washings were combined and solid ammonium chloride (reagent grade) to colorless precipitate until the residue together with the filter paper together into the high-temperature vessel, and calcined into white platinum sponge, and then high-temperature flame can melt. After the filtrate separation of platinum, gold was gold trichloride status, available sulfur dioxide gas reduction and precipitation out of gold, gold dust washing will collect drying, melting can be.

Gold-plated pieces in gold recovery
A, dissolved retreat France Fire
Electrolytic lead is to slightly melt temperature (melting point of 327 degrees), and scrap to be treated is placed within the lead, the gold into the lead, the gold scrap removed after withdrawal, used to recover nickel and tungsten, and then casting lead into the stereotype with cupellation or electrolytic recovery of lead, recovery of gold from the anode mud.
With ash blowing, it will get the lead under which additional gold silver, gray blown silver alloys, silver alloys will get water for quenching method to obtain gold and silver grains were separated by silver nitrate, which is coarse powder, melting you can get thick gold.

Second, the electrolysis
The biggest advantage of the method is that it gives less discharge or no discharge of cyanide, the cyanide effluent nipped in the production cycle.
One kind of waste from the plating electrolytic recovery of gold cyanide method, device types are: dissolution chamber solution circulation, drum and basket-style. Three types of common features are: have the same cell, a graphite anode and a stainless steel tank cathode. The electrolytic solution was 50 g / l of sodium cyanide was added. Fertilizer exposed to the air, while in contact with the electrolyte, scrap gold corroded into solution at a rate of 21 microns / hour, when the gold reaches a certain concentration, on DC power, 0.3 A / dm 2 under the conditions of electrolysis gold deposited on the cathode, when operating at 20 degrees, each batch of waste treatment time was 3 hours.

III: Thermal expansion method
The method is based on the gold alloy tube with different coefficients of thermal expansion, thermal expansion method applied to the gold plating and the voids between the tubes, and then boiled in sulfuric acid completely out of the gold layer, and finally the dissolution and purification, the production process is as follows: take one kilograms transistor, at 800 ° C for 1 hour, cooled, with a resistance wire heater into pickling tank, add 6 liters of 25% sulfuric acid solution, boiled for 1 hour to gold layer off, while generating sulfate precipitation, the solution was cooled and drained away gold transistor, clarifying tank solution, taking the upper acid backup. Precipitated sulfates containing powder and diluted with water until all dissolved sulfate, clarified by decantation the solid-liquid separation. Solid precipitate outside powder also contains, in addition to silicon and other impurities dissolved in aqua regia, by evaporation, dilution, filtration step, the solution was treated with zinc replacement gold acid, i.e. with purity of 98% pure gold.

Gild scrap gold recovery methods
Gild scrap visible to the different substrate, using different methods gold recovery.
A: Electrolysis
Law suit laced with gold scrap copper, chunks can be hung on the hook, put a small basket, baskets together with large pieces of scrap anode placed configured with concentrated sulfuric acid electrolyte, with lead plate as the anode, the current density is controlled at 120 - 180 A / m and 2.
Since the waste deposited on the surface of the base or salt causes poor electrical properties, the tank resistance increased rapidly, in order to maintain a constant current density, cell voltage gradually from 5 volts to 25 volts, or 50 volts.
Electrolysis result, gold was deposited on the bottom black mud, mud attached to the metal part of the copper surface, it is easy wash.
After a period of electrolysis, the electrolyte is diluted with water, heated to boiling for 24 hours, filtered, washed with water, drying the obtained precipitate, that was thick gold metallurgy.
Two: calcination
This law applies to copper and brass with gold scrap. The scrap gold from the sulfur composition with concentrated hydrochloric acid and dilute slurry coated well, painted a good scrap pieces into tubs, tubs placed in a fume hood to stand for 30 minutes and then placed in a furnace with pliers , the temperature at 700-800 ° calcined for 30 minutes, the heating effect and coatings result, gold paste is formed between the base metal of copper and copper sulfide layer scale, and use these pliers hot metal from the furnace out, put a bucket filled with water, the result of gilding along with scales of copper and brass from falling down.
Gold is not completely off the place, the available wire stripped, drained the bucket of water filtration, the precipitate collected, dried, and then smelting can.
Three: etching method
For Jinbian, gold, signboards and other scrap. Gild objects sequentially every 10-15 minutes with a hot concentrated caustic solution immersion wetting, when the child begins to greasy soap role, wash down with a sponge or brush the paste, wash the paste to precipitate collected in bins bottom of the barrel, careful filtration, drying, melting that was thick gold.
Gold throwing ash, emery method for recovering gold
Polished gold pen nib manufacturing plant generated throwing ash, leftover gold plant litter, jewelry factory as polished, open-chain beat the dust generated by other processes all contain gold, they can be used pyrometallurgical smelting, wet separation methods recycled.

Pyrometallurgical smelting
Will gather up gold dust, weed out the sand and rubble and other debris, according to the following ratio of ingredients Ingredients (grams): gold dust, 100, 150 lead oxide, sodium carbonate, 30, saltpeter 20. The above materials and mix well into the crucible, and then covered with a thin layer of borax into the crucible melting furnace, you can get gold and other precious lead. Will be the lead dust that was blowing thick gold, thick gold obtained in which contain platinum, iridium, available dissolved in aqua regia and further separation can be.
First, the recovery of waste from a variety of gold gold
For gold silicon, although recovery in many ways, the most convenient and feasible approach should be first placed on wafer temperature of about 500 degrees calcined for 1 hour, cooled grinding crack, if a large quantity can consider using a ball mill, silicon into a powder inside can be seen after the fine gold, can use water to rinse it, collect gold, and then dissolved in aqua regia, dissolved in aqua regia gold aqua regia filtered, filter out impurities, water, hydrochloric acid and then to the king catch nitrate, nitrate rush to aqua regia viscous liquid was accounted for after the additional part of the water, add hydrochloric acid to adjust ph1 - 2, then the replacement of zinc or zinc tablets of black powder, gold powder was filtered washed repeatedly with water until no chlorine ion, then boiled with nitric acid powder 0.5 hours, you can see dark yellow powder, filtered, washed, can melt.

Second, the various pieces of gilded gold recovery
1, first with 20% nitric acid pretreatment off excess base metal, then use aqua regia dissolves. Principle: boiling state, iron, nickel, copper and other metal and nitric acid, is dissolved in nitric acid, and the gold is not react with nitric acid, gold will be deposited on the bottom of the container.
Note: Do not use the configuration nitrate inside the city's tap water, because the water is usually chlorinated and contain some chloride, nitrate mixed with chloride ions in solution, will become low concentrations of water in cooking will dissolve gold and gold losses.
2, gold see is dilute nitric acid boiled for 30 - 60 minutes later, the gold plating on the surface has been completely stripping, standing, cooled, drained upper nitrate liquid (you can pour a bucket inside the left to the next to continue to use, Yellow gold layer at the bottom of specimens, washed several times into the water, 5 times the aqua regia, 10 - 30 minutes until all the gold is dissolved in aqua regia, the filtered water insoluble impurities king to give gold aqua regia.
Aqua regia configuration: that 3 parts by volume of hydrochloric acid plus 1 part by volume of nitric acid
Note: If you do not have time to dissolve the gold in aqua regia, hydrochloric acid and hydrogen peroxide can be used at a ratio of 4:1 dubbed gold dissolution solution, and this solution was dissolved with aqua regia gold effect, like, the advantage is you can catch nitrate exempt tedious process, but replacement Gold is also needed concentrated by evaporation, the purpose is the destruction of the oxidizing acidic solution, to reduce the amount of zinc, the replacement is easy.
3, catch nitrate: gold dissolution after aqua regia, in the ventilation or fume hood, heated to a boil, evaporate aqua regia do not take tobacco and slightly sticky date (middle additional small amount of hydrochloric acid, hydrochloric acid is generally with the king's equal amount of nitric acid in water), and then diluted with a small amount of purified water and adding a little hydrochloric acid.
4, the replacement after aqua regia gold rush nitrate plus some hydrochloric acid, and then adding an excess of zinc powder device response can be seen from the bottom of the container to be zinc replacement out of the yellow gold mud, replace the end is no longer a plus zinc yellow and black material produced so far, that indicates the amount of zinc powder is sufficient.
5, tossed away the upper layer of liquid hydrochloric acid, collecting the underlying gold precipitate with filter paper in the funnel filter out excess hydrochloric acid water, and then rinse several times until no HCl added up (be sure to wash acid). After the acid wash, beaker Riga concentration of 30% of the nitric acid, boil 15-30 minutes, you can see yellow with gold dust.
6, tossed away the upper nitric acid, washing with water several times, filtered with filter paper powder.
7, melting powder, the powder placed into an alumina crucible, melted directly with guns alternately add a little sodium nitrate and borax, melted get golden-yellow.

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