Recover gold from gold-containing waste materials

In the production and use of gold or silver products, or gold or silver-containing products, a large amount of waste is generated and old products are used. The gold and silver grades of these waste materials are much higher than ore and the process is simple. It is also economically cost-effective and is therefore the second resource for extracting gold and silver.
The nature and shape of precious metal scrap vary widely, from solid to liquid; from metal plates to powder dust; some are close to pure metals, some are extremely low; some contain other metal impurities, some contain non- Metal impurities, sometimes mixed with some garbage, sundries, etc. Therefore, for professional recycling plants, waste collection must first be pretreated to become a high-quality material suitable for metallurgical processing, obtain high technical and economic indicators, and obtain high-quality metals.
In order to vigorously recycle precious metals from used raw materials, Johnson Marseille converted the gold refinery in Brinds, England, into a precious metal recycling plant specializing in waste materials in 1997. The plant is large, technologically advanced and capable. One of the recycling manufacturers dealing with various precious metal scraps, the waste disposal process is shown in Figure 1. The inside of the dotted line in the figure is the preprocessing and sampling process.
Figure 1 Johnson Marseille Chemical Company's flow chart for processing precious metal scrap
First, the pretreatment of waste materials
In the waste recycling plant, waste pretreatment includes the following processes.
(1) Weighing: The material is generally weighed in the future, for materials with high precious metal content, such as jewelry waste, utensils, enamel, profiles, etc. Accurate weighing is especially important. At present, the electronic scales are automatically weighed and accumulated at home and abroad.
(2) Primary selection: According to the appearance of the waste, the first selection is carried out by visual inspection, or by the grade of the waste. At the same time, remove debris, garbage and dust from the waste. Sorting is mainly done by hand.
(3) Classification: First, according to the type of precious metals contained, the materials are divided into gold-containing materials, silver-containing materials, other single precious metal materials and various precious metal materials. Or according to the characteristics of the material, it is further divided into magnetic materials, non-magnetic materials, low-grade materials, dust, garbage, liquid waste and various resin wastes, etc., so as to facilitate the recovery of sampling. However, some wastes have similar shapes, but their precious metal content may vary greatly. Therefore, the incoming materials should be carefully and carefully checked and classified. After sorting, mark the same material to avoid confusion.
Second, the sampling and analysis of waste
Pretreatment of the waste includes incineration, drying, grinding, sieving and mixing, followed by sampling. Sampling and composition analysis is a very important task for waste recycling plants. Sampling and analysis should be as representative as possible. Sampling, depending on the type, has different sampling methods. Table 1 shows the recycling business guide for gold-containing waste. Table 2 lists the gold content in various electronic industrial wastes. Table 3 lists the gold content in various alloys. The gold content in some gold-containing scraps is shown in Table 4. In addition, the gold content in various gold plating solutions is as follows: acidic gold plating solution 4 to 12 g/L, neutral gold plating liquid 4 g/L, and alkaline plating liquid 20 g/L. As well as gold-palladium catalyst is used in petrochemical 0.3% to 0.6%; platinum-based and palladium-based pulp slurry Waldo 85%. Thermocouples, platinum- iridium glass fiber leakage plates contain gold.
Table 1 Main gold-containing waste recycling business guide
Material type
Source
Pretreatment
Sampling method
Polished sand
Silver work
dry
Mechanical mixing and sampling (bulk)
Manual groove reducer (small batch)
Ingot - silver, gold
Primary and secondary producers
Drill or saw into standard strips or smelting, deposition sampling
Gold scrap
Processing jewelry
Ibid.
Foundry waste - gold, silver
Processing jewellery and silver work
Melt into a sample block, drilled, crushed
Cuttings, smelting, sediment sampling
Waste coins, coinage waste - gold, silver
Currency billet processor and mint
Melt, cast sample block, drill, crush
Cuttings, smelting, sediment sampling
Concentrate-mining
Mining Company
dry
Mechanical mixing and sampling
坩埚-platinum group metal
Laboratory, electronics and glass industries
Smelting, sediment sampling
Dental gold alloy
Processing dentistry and laboratory
Ibid.
Gold and silver alloy
Primary and secondary producers
Casting sample blocks, drilling and crushing cuttings
Drill cuttings - silver
Precious metal industry users
Processing jewellery and silver work
Magnetic separation
Melt, cast sample blocks, drill, crush drill cuttings or smelting, grinding, sorting, separating, sediment sampling
Debris
Precious metal industry users
Precious metal smelter
Grinding and screening
Mechanical mixing and sampling (bulk), optional (small batch), smelting, drilling and sieving of metal particles
Medal waste - gold, silver
Mint, billet processing
Smelting, sediment sampling
Milling chips - silver, gold, platinum group metals
Precious metal industry users
Processing jewellery and silver work
Magnetic separation
Burning sample blocks, drilling and crushing drill cuttings, depositing samples or sawing, casting sample blocks and sawing samples
Metal scrap of platinum group metals
Industrial users, processed jewelry
Drill or saw into a standard strip
Ceramic industry waste
Ceramic industry
Incineration, grinding, screening
Mechanical mixing and sampling (bulk) hand selection (small batch)
Residue - gold, silver
Intermediate product collector, refiner
Dry and incinerate and sieve
Ibid.
Residue - Platinum Group - High and Low Grade
Industrial users, semi-finished product collectors
Ibid.
Ibid.
Electric contact waste - platinum group
Electric contact processor and user
Grinding and screening
Dissolve the sample block and saw it
Electronic waste
electronics industry
Burning, grinding, screening
Various methods for special materials
Slag - from smelting
Processing jewellery and silver work
Precious metal smelter
Grinding and screening
Mechanical mixing and sampling (large batch), hand-selected (small batch) smelting, drilling and sieving out metal particles
Laboratory utensils - platinum group
Laboratory, electronics industry
Ibid.
Lcmcl strips - gold, silver
Processing jewelry
Casting sample blocks, drilling, crushing drill cuttings
Slag, slag-silver and gold
Precious metal smelters, jewelry processing and silver work
Grinding and screening
Mechanical mixing and sampling (bulk) hand selection (small batch)
Mud - silver and gold
Photographic, electroplating, semi-finished producers and refiners
Drying, grinding and sieving
Ibid.
Chips - metal materials - gold, silver, platinum
Industrial users, processed jewellery and silver workers
Magnetic separation
Cast sample blocks, drill, crush drill cuttings or smelt. Drilling, sampling
Cleaning materials - jewelry grinding
Processing jewellery and silver work
Incineration, grinding, screening
Mechanical mixing and sampling (large batch), hand selection (small batch)
Car shavings - gold, silver, platinum group metals
Industrial users, processed jewellery and silver workers
Magnetic separation
Casting sample blocks, drilling, crushing
Cuttings or smelting. Grinding, screening
Note: The guide is taken from Lu Yiyuan, Bin Wanda, Precious Metallurgy, Central South University of Technology Press, P452~456, 1990.
Table 2 Gold content in various electronic components
Scrap name
Model specification
Use
Unit
ω(Au)/g
é”— Ordinary diode
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Silicon rectifier component
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Thyristor rectifier
Silicon rectifier diode
Silicon rectifier diode
Silicon steady voltage diode
Silicon double-base diode
Silicon double-base diode
Silicon double-base diode
Silicon high frequency small power transistor
Frequency low power
Silicon high frequency power
High frequency transistor cap
High frequency transistor cap
Low frequency and high power
Low frequency and high power
Low frequency and high power
High frequency transistor transistor holder
High frequency transistor transistor holder
High frequency and low power
High frequency small power switch
Reed relay
Silicon single NAND gate
Black and white video tape recorder
Transistor three-tone record player
Mercury vapor analyzer
Trace oxygen analyzer
2AP1~30
2CZ1A~11
2CZ1A
2CZ5A
2CZ20A
2CZl00A
2CZ200A
2CZ300A
2CZ500A
2CZ600A
2CZ700A
2CZ800A
2CZl000A
2CZl200A
2CZl500A
3CT5A
2CZ20A
2CT50A
2CT200A
2CT5A
2CZl0A
2CZ20A
2CZ50A
2CP6A-6K,
10-2, 41-60
2CP1A-2,
21-29, 31-33
2CW21A-S22A
-W1-59-20
BT32-33
BT31
BT31-35
3DG
3DG4.6, 8.3DK 2
3DG401-410, 3DK 4
Figure non-30
Figure non-32
3DD50.75
3DD300
3DD150G 4 F 6
B 1
P 6
3AG-1-50
3AG-1-50
AJAg
5TZ14.2, 72
CDLS-1
SD-1
UGY
SXE1 type
Gold wire lead
Gold antimony films
Kim Min
Kim Min
Kim Min
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold bismuth , gold boron palladium
Gold bismuth, gold boron palladium
Gold bismuth, gold boron palladium
Steamed gold, gold boron palladium
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Gold film
Steamed gold, gold wire lead
Steamed gold, gold wire lead
Gold wire, gold enamel
Gold plated, gold wire, steamed gold
Gold plating, steaming gold hot pressing
Gold plating, steaming gold hot pressing
Electroless gold plating
Electroless gold plating
Steamed gold, gold plated, gold wire
Steamed gold, gold plated, gold wire
Steamed gold, gold plated, gold wire
Electroless gold plating
Electroless gold plating
Gold and silver alloy
Gold and silver alloy
Gold plated piece
Electroplating gold
Gold silk platinum
Gold nickel contact
Gold piece gold wire
Gold piece gold wire
Ten thousand
support
Million
Million
Million
only
only
only
only
only
only
only
only
only
only
Ten thousand
Ten thousand
Ten thousand
only
only
only
only
Ten thousand
Ten thousand
Ten thousand
Ten thousand
Ten thousand
Ten thousand
Ten thousand
Ten thousand
Ten thousand
10,000 only 51
Ten thousand
Ten thousand
Million
Million
Million
support
support
Million
Million
Million
4
station
station
station
station
2
0.04
43.847
128.75
397.68
0.35
0.4
0.5
0.64
0.7
0.78
0.8
1.0
1.5
2.2
93.76
401.71
919.789
838
0.02
0.03
0.04
0.17
23.47
48.5
48.5
6.27
4
3.8
10.5
52
10
13
400
800
1.400
10.24
20.48
0.5
0.5
60
60.2
1.85
0.1
1.5
15
Note: The data in this table are taken from Lu Yiyuan, Bin Wanda, Precious Metallurgy, Central South University of Technology Press, P457~459, 1990.
Table 3 Main components of various alloys
Gold alloy name
Brand
chemical composition/%
Copper alloy of gold and silver
Gold, silver alloy of gadolinium
Gold, silver and copper alloy
Gold, silver and copper manganese alloy
Gold, silver, copper and manganese alloy
Gold, silver, copper, manganese and nickel alloy
Gold nickel copper alloy
Gold nickel chrome
Gold nickel chrome
Gold nickel chrome
Gold nickel chrome
Gold nickel chrome
Gold nickel chrome tantalum alloy
Gold nickel chrome tantalum alloy
Au-Pd alloy, iron-aluminum
AuAgCu35-5
AuAeCuGd35-5-0.5
AuAgCuGd35-10-0.5
AuAgCuMn33.5-3-3
AuAgCuMnGd33.5-3-2.5-2
AuAgCuMnNi33.5-3-2.5-2
AuNiCu7.5-1.5
AuNiCr5-1
AuNiCr5-1.25
AuNiCr6-2
AuNiCr3.5-2.5
AuNiCr7-0.6
AuNiCrGd7-0.5-0.4
AuNiCrRh7-0.6-0.4
AuPdFeA138-8.5-1
Au60, Ag35, Cu5
Au59.5, Ag35, Cu5, Gd0.5
Au54.5, Ag35, Cu10, Gd0.5
Au61.5, Ag33.5, Cu3, Mn3
Au59, Ag33.5, Cu3, Mn2.5, Gd2
Au59, Ag33.5, Cu3, Mn2.5, Ni2
Au91, Ni7.5, Cu1.5
Au94, Ni5, Cr1
Au93.75, Ni5, Cr1.25
Au92, Ni6, Cr2
Au94, Ni3.5, Cr2.5
Au92.4, Ni7, Cr0.6
Au92.1, Ni7, Cr0.5, Gd0.4
Au92, Ni7, Cr0.6, Rh0.4
Au52.5, Pd38, Fe8.5, Al1
Note: The data in this table are taken from Lu Yiyuan, Bin Wanda, Precious Metallurgy, Central South University of Technology Press, P459, 1990.
Table 4 Gold content in some gold-containing wastes
Scrap name
ω(Au)/%
Copper plated
Gold plated triode
Gold plated flat
Double tube
Gold-containing resin
Gold-plated circuit board
Gold plated wire
Golden mud
Gold plated wall panel
Tin-antimony alloy containing gold
Wang Shui non-slag
0.18~3.84
0.03 to 0.3
0.2 to 2.68
0.22
2.93~15.6
0.08~0.14
3.13~7.80
32.59
1.43
79.71
1.0 to 2.0

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