First, the precious metal production and consumption Overview
Among the precious metals, the largest production is silver . In 1983, the world used raw materials to produce 9,800 tons of silver, including silver recovered from recycled raw materials, totaling 15,300 tons. Recycled raw materials accounted for 56% of the original biomass. In order to return to the recycling of silver-containing waste materials, there is a concept for the use of silver in various industrial sectors. The same is true for other precious metals.
The US silver consumption structure is the most representative. The main data of this structure are as follows (%):
Photosensitive material | 38 |
Electrical and electronic equipment | twenty four |
solder | 7 |
catalyst | 6 |
Silver plated items | 5 |
coin | 2 |
other | 15 |
In the production of various photographic materials, silver- zinc batteries and other batteries, the amount of silver is increasing. Although the US's original silver production dominates the world, about 53% of its silver demand comes from recycled silver, and 9% of it is coin remelted silver. There are 46.66 million tons of silver coins and silver ingots in the hands of American residents, and 26,440 tons of silver jewelry.
The precious metal with the second highest output is gold. In 1983, the total capital produced by capitalist countries was 1,040 tons, of which South Africa accounted for 680 tons.
The consumption structure of capitalist world gold (% of production) is listed below:
Consumer goods | %(Ton) |
Coin | 18.6 (179) |
jewelry | 12.5 (120) |
Electronic equipment | 8.43 (81) |
Denture | 6.45 (62) |
Medal and logo | 1.56(15) |
Other decoration | 7.0 (67) |
The rest of the gold enters the national reserves of countries. For example, in 1983, the Indonesian gold reserve increased from 9 tons to 74 tons, and South Africa's gold reserves increased by 65 tons. The United States has stopped selling gold from reserves, and Canada sold 67 tons in 1983.
The world reserves a total of 55.968 million tons of gold, of which 34.214 million tons are the gold reserves of the capitalist countries, and 18.662 million tons are owned by the private sector.
Gold used in the electronics industry and decorations is a regenerative gold. The amount of gold recovered from recycled raw materials in the United States was 62.5 tons in 1980, 68.4 tons in 1981, and 43.0 tons in 1982.
The capitalist country's primary platinum production in 1981 was 76.8 tons, of which South Africa's minerals produced platinum accounted for 67.8 tons. US recycled platinum production is ≈5.3 tons, accounting for 6.9% of total platinum production. In 1981, the production of primary palladium was estimated at 38.9 tons, of which 27.9 tons were produced in South Africa. The production of recycled palladium accounts for 12% (average) of the market supply of palladium. According to the forecast. The consumption level of platinum group metals in capitalist countries and developing countries in 1985 and the average growth rate of platinum group metals in 1985-1990 were:
Pt | Pd | Ru | Rh | Ir | Os | |
Consumption level (tons) | 68.5 | 74.5 | 5.35 | 3 | 1.52 | 0.08 |
Average growth rate (%) | 2.9 | 7.4 | 3 | 1.8 | 3.5 | 1.4 |
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Table 1 shows the 1985 platinum group metal consumption structure.
Table 1 Platinum group metal consumption structure (%)
department | Pt | Pd | Rh | Ru | Ir | Os |
auto industry Petroleum purification chemical industry Electrical engineering Jewelry industry Glass industry Pharmaceutical industry Other | 17.3 7.5 11.2 10.8 35.5 6.5 3.7 7.5 | 6 1.1 12.18 36.2 4.8 0.2 36.2 2.7 | - - 33.4 61.5 - - 0.9 4.2 | - - 22.9 36.2 10.4 21.9 0.1 8.5 | - - 10.3 50.4 20.5 0.6 3.3 3.3 | - - 35.7 - - 64.3 - - |
The main users of platinum and palladium are the automotive industry (complete exhaust gas combustion catalyst), the chemical industry (corrosion resistant equipment and catalysts) and the electrical industry. In recent years, the consumption of platinum group metals has declined in the automotive industry, and has increased significantly in the electrical industry.
It should be noted that the amount of gold, platinum and platinum copper entering the regenerative non-ferrous metallurgical industry is not large. This situation can be considered as clean, because the precious metal is corrosion resistant and the loss is relatively small. Many precious metals have entered the national reserves of countries. The amount of various precious metal products in the hands of residents returning to the renewable non-ferrous metallurgical industry is extremely limited.
Figure 1 shows the process of precious metals from raw ore to the preparation of concentrates. The refined materials are stored in the national treasury, and are reserved for further processing into semi-finished and finished products by professional processing enterprises, and then used in various technical and industrial sectors and people's lives. The materials, parts and products that have been scrapped will eventually become the raw material storage of the recycled precious metal plant.
Figure 1 Example of precious metal turnover
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It should be noted that the accumulation of recycled raw materials is not limited to the use of various products and materials, but also in the implementation of industrial processes of various processing enterprises (waste and waste generated in production). In this connection, the processing enterprises can be divided into recycling enterprises; the second category - the production process is an open circuit enterprise, and all production wastes containing precious metals are sent to the regenerative precious metal plant.
The main role of the regenerative precious metal plant is to produce secondary refined products that have been handed over to the national reserve. In addition, the refined products produced are used to produce the semi-finished products required by the corresponding processing enterprises. Intermediate products with higher precious metal content require more advanced processing techniques, so these intermediate products are generally sent to refineries from reclaimed precious metal plants. Intermediate products with low precious metal content or low-grade raw materials produced by the reclaimed precious metals plant are sent to a smelter whose production process includes the preparation of precious metal concentrates. Some of the recycled raw materials are pure and can be sent directly to the refinery without being sent to the regenerative precious metal plant. Refined metal as a processed product.
Second, the way to return to the precious metal recycling plant waste
The return system for recycled raw materials containing precious metals is regulated by the corresponding regulations in the (former) Soviet Union. The regulations include a series of rules and measures designed to ensure the statistical, complete recovery and pre-treatment of waste. This regulation has been used in all recycled precious metal processing enterprises as well as the use of these processing enterprise products (instruments, batteries, radios, thermocouples, spent catalysts, waste precision machinery and waste aerospace - aerospace technology equipment, processed intermediate products, used jewelry and teeth) The relevant enterprises in the industrial and technical sectors of the material waste are promoted and implemented. According to the regulations, the transfer of recycled raw materials to the corresponding reclaimed precious metal plants and refineries is equivalent to handing over the precious metals to the national treasury. For this reason, the identification of the content of recovered components in the recycled raw materials is the responsibility of these recycled precious metals plants and refineries.
Before the recycled raw materials are sent to the regenerative precious metal or refinery, the types and contents of the recovered metals (alloys, composites, mud, salt, powder, waste batteries, waste parts, and photographic materials) should be classified. . Each recycled material should be registered, indicating the type, precious metal and other ingredients. The type and content should be filled in based on the data analyzed in advance or the manufacturer's instructions.
In many processing companies engaged in the production of photosensitive materials, certain types of catalysts (mainly carriers) and electroplated layers, there are often a large number of intermediate products (such as solutions) that are unsuitable for transportation. Therefore, the pre-selection of precious metals should be included in the production process of each processing enterprise to produce dry salts, replacements, mud, ash and other products. An important feature of this precious metal-containing preselection process is the avoidance of irreparable loss of useful components in the intermediate product.
In the (former) Soviet cities, there are professional outlets and workshops for the centralized recycling and pre-selection of photographic materials processing waste (wrap film and photo-used waste film, waste x-ray film, fixer, rinse water). Each professional outlet and waste supply unit does not perform settlement according to the amount of precious metal in the scrap, but is responsible for the identification and classification of the feed. The main task of each professional network is to prepare silver-containing concentrates (ash, salt) for transportation to the regenerative precious metal plant with minimal loss.
Before shipping, renewable raw materials should be such that the intact during transport packaging (polyethylene with which the seals container-lid, polyethylene bags, sacks, boxes) packaging. For large quantities of waste (slag, mirror fragments, furnace fragments) with a gold content of not more than 0.05% and a silver content of not more than 1%, the reclaimed precious metal plant can be sent in a convertible car without packaging.
Raw materials entering the regenerative precious metals and refineries should meet the following requirements:
(1) The thickness of waste products, ingots, various metal and alloy scraps (excluding undisassembled waste batteries) shall not exceed 150 mm and the length shall not exceed 400 mm;
(2) Powder, salt, mud, ash, etc., shall be ground and sieved, the mesh opening shall not be greater than 1 mm, and the product (metal and non-metal) shall be supplied as a separate waste material;
(3) All kinds of waste products (excluding undisassembled waste lead storage batteries) should be removed from plastic, ceramics and other materials covering the metal to be recovered;
(4) The limit content of moisture and other volatile components should not exceed 10% by weight;
(5) It must not contain explosive, toxic, flammable or radioactive substances.
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Third, the characteristics of the basic types of waste
The main characteristics of the precious metal-containing renewable raw materials are: the types are extremely complicated; the content of recovered elements varies widely; the metal and non-metal components - the metal mixture with different salt and dispersion, the uniform distribution of the recovered elements and the local distribution of metal and non-metal dense The materials of the associated components of the material are diversified.
1. Silver-containing recycled raw materials
Silver-containing recycled materials include:
(1) Waste batteries of silver zinc, silver cadmium and silver magnesium . The battery electrode is a silver-on-copper or silver-plated grid in which silver (Ag, Ag 2 O) and zinc-containing powders are added, respectively. These electrodes are also equipped with a silver plated plug and silver wire. In a silver-magnesium battery, the positive electrode is made of a silver mesh or a silver foil coated with a layer of silver chloride.
(2) Waste electrical contacts
(3) A scrapped powder metallurgy method containing silver products, including cermet contacts.
(4) A spent catalyst containing 70% to 80% or less of silver.
(5) Containing 0.5% to 20% of immersion silver waste ( pumice , quartz sand, dust, fine powder, fabric, cotton, etc.).
(6) Metal silver sludge (containing 2% to 90% of silver) obtained by separating silver from waste silver plating solution and pickling solution (for example, by adding zinc or adding aluminum to precipitate).
(7) Waste metals with various metals ( iron , steel, tungsten, molybdenum , non-ferrous metal alloys) and non-metal (glass, plastic, ceramic) with silver plating. The metal silver plating layer has a thickness of 10 to 1800 μm.
(8) Metal and non-metallic powders (containing 10% to 99.9% of silver).
(9) Wastes produced in the production of various parts and products, including ingots (containing less than 60% of silver) cast from such wastes.
(10) Waste film ash from metal silver.
(11) Films containing metal silver (colloid) and photographed used waste. The base of these wastes is triacetate or trinitroacetic acid film, animal gum polyvinyl alcohol.
(12) Retired but unused film and photographic materials with a latex layer on a paper or acetate substrate containing colloidal silver halide in addition to animal glue and polyvinyl alcohol.
(13) Silver sulfide (sometimes mixed with metallic silver) prepared in the process of depositing metal from a fixing solution (containing 30% to 50% of silver). The precipitate contains iron, alumina, silica and organic inclusions.
(14) In the motion picture film silver bromide photographic paper manufacturers and plant regeneration plant preparation of silver, a silver thiocyanate, and a silver chloride precipitate. The ingredients include latex, alumina, potassium carbonate, and cullet (containing 35% to 50% of silver). Silver thiocyanate from waste liquor bismuth (silver 40% to 50%, 10% to 15% bismuth) in the preparation.
2, gold-containing renewable raw materials
From the perspective of subsequent metallurgical treatment processes, gold-containing renewable raw materials can be divided into two categories: the first category is gold, silver and base metals, and the second category is gold, platinum group metals, silver and base metals. The materials belonging to the first category are:
(1) High-quality gold waste products, waste jewellery containing less than 30% of silver, containing less than 15% of copper, and waste industrial products of silver-copper alloy.
(2) A gold (and silver) replacement precipitate (containing 50% or less of gold) obtained from a waste gold plating solution by a zinc substitution method.
(3) Waste industrial products and jewellery with gold plating. The thickness of the coating is 2-10 microns, and the matrix material is insoluble metal (W, Mo), nickel , copper, iron and alloy (such as Kovar nickel alloy).
(4) Gold-containing (20% or less) material obtained by incineration of gold-coated wood (Au about 0.1%, Ag 0.1%) and stripped from solid objects.
(5) Oxides containing iron, aluminum, silicon, and chromium , and silicon carbide abrasive powders and abrasive pastes (Ag 1% to 8%, Au 5% to 18%).
(6) The slag produced during the smelting (testing) of the semi-finished product and the recycled raw material contains Au 0.1% and Ag 1%.
For materials belonging to the second category, see the section “Recycled raw materials containing platinumâ€.
3. Platinum-containing recycled raw materials
All platinum-containing recycled raw materials are usually processed in refineries and smelters. Platinum-containing renewable raw materials used as raw materials for refineries include:
(1) Waste products made of platinum or alloys of precious metals and non-ferrous metals.
(2) Regenerated precious metal materials which have been preselected with platinum group metals, including spent platinum catalyst with support and spent palladium catalyst (platinum and palladium content not less than 10% to 15%).
(3) Furnace lining and flue bricks impregnated with precious metals (containing 0.7% to 2.0% of silver, containing 0.3% to 0.5% of gold and platinum group metals), and the components include clinker, magnesite, quartz and clay .
The recycled raw materials entering the smelting plant are usually a large batch of materials with a low platinum group metal content (for example, various spent catalysts having a platinum and palladium content of 0.05% to 0.5%).
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