I. PGE minerals
1. Palladium: It is mainly smelted from natural cymbal. The color is silvery white, the appearance is similar to platinum, and it has metallic luster. The hardness is 4~4.5. The relative density is 12. The melting point is 1555℃. The chemical properties are relatively stable. Because the output is higher than platinum and gold, the value is low, and it is rarely used to make jewelry.
2. Rhodium gold: mainly extracted from natural rhodium, it is a rare precious metal. The color is silvery white, metallic and opaque. Hard 4 ~ 4.5, relative density 12.5. High melting point, 1955℃. Stability of chemical reward. Rhodium gold is mainly used in electroplating industry because of its corrosion resistance and good luster. When electroplating on other metal surfaces, the coating is firm in color, not easy to wear and has good reflective effect.
3. Iridium gold: mainly extracted from natural iridium or iridium ore. The color is silvery white, with strong metallic luster and hardness of 7. The relative density is 22.40, which is brittle, but it can be pressed into foil or drawn into filaments at high temperature, and its melting point is as high as 2454℃. Chemical properties are very stable and insoluble in water. It is mainly used for manufacturing scientific instruments, thermocouples, resistance twill, etc. High hardness Fe-Ir and Ir-Pt alloys are often used to make pen tips and platinum jewelry.
4. Platinum: It is made of natural platinum, crude platinum ore and other minerals. Because "platinum" is a combination of "gold" and "white" and its color is silvery white, it is also called "platinum". The color is silvery white, metallic luster, hardness is 4 ~ 4.5, and relative density is 2 1.45. High melting point, 1773℃. It is malleable and can be drawn into extremely thin platinum wire and rolled into extremely thin platinum foil. Chemical properties are extremely stable, insoluble in strong acid and strong seal, and do not oxidize in air. Widely used in jewelry industry and chemical industry, used to manufacture advanced chemical vessels, platinum crucibles and catalysts for accelerating chemical reactions.
Second, the types of platinum
1. Pure platinum: the highest purity platinum. It is often used to make engagement rings to show the purity and eternity of love. In foreign countries, many people think that setting diamonds with gold may lead to the yellowing of diamonds, thus greatly reducing the price of diamonds. Diamonds inlaid with platinum can keep the pure white color of diamonds, especially as engagement rings. Diamonds inlaid with platinum are white and crystal clear, symbolizing eternal and long-lasting pure love. However, although the hardness of platinum is higher than that of gold, it is still not enough to set diamonds and jewels. It is often necessary to mix other metals to make a K- platinum alloy to embed diamonds.
2. Platinum Platinum: an alloy of iridium and platinum. The color is also silvery white and has a strong metallic luster. High hardness. It is an excellent platinum alloy jewelry material with high relative density and clear chemical composition. According to the difference of hinge and platinum content, it can be generally divided into three types: relative density and melting point of components.
10% iridium platinum alloy 2 1.54 1788℃
15% iridium platinum alloy 2 159 182 1℃
5% Ir-Pt alloy 2 1.505438+0779℃
3. Platinum: A white alloy made by melting gold and other metals. Because platinum is scarce, expensive and has a high melting point, it is rarely used to produce true K platinum in general countries. At present, in order to meet the demand of consumers for platinum, gold, palladium or nickel, silver, copper, zinc and other metals are selected to be smelted into a white alloy, which is called "K platinum". The fineness of K-gold platinum is the same as that of K-gold, the bundle mass is 24, and the share of gold in the mass is "K number of K-gold-Bobai". For example, 18K platinum and 14K platinum, in which the platinum content is 75% and 58.5% respectively.
Third, platinum jewelry.
People's understanding and utilization of platinum is far behind that of gold, with a history of only about 2000 years. Archaeological data show that in more than 700 BC, the ancient Egyptians were able to process platinum into platinum ornaments with high technical level. Long before Columbus discovered the New World, white gold ornaments were also popular among Indians in Central America. However, people in other areas know nothing about platinum. Until the beginning of16th century, the Spanish colonial empire was gradually formed, and a large number of Spanish adventurers flocked to Africa and America to search for gold and treasures. At that time, when searching for gold in the rivers of Ecuador, it was repeatedly found that there was a white metal mixed with gold, which was actually precious platinum. However, due to the underdeveloped science and low recognition ability at that time, faced with dazzling platinum, those colonial rulers called it "inferior broken silver" and abandoned it. 1748, Antonio Roya, a famous Spanish scientist, discovered silver-white natural platinum in Pinto River Gold Mine. After careful study, he found that natural platinum has very stable chemical properties, excellent ductility, high melting point and high relative density, which is obviously different from metallic silver. Anthony was the first scholar to study platinum in detail. 1780, a skillful craftsman in Paris made platinum rings, brooches and platinum necklaces for King Louis XVI and Queen of France. Therefore, Louis XVI and his wife became the first people in the world to own platinum ornaments on record. Since then, the reputation of platinum has greatly improved, and it has leapt above gold ornaments, and it has been favored by the royal family, dignitaries and wealthy businessmen. Due to the scarcity of platinum relative to gold in nature, according to incomplete statistics, the total global platinum reserves are about10.4 million tons (the total platinum group mineral resources reserves are about 310.4 million tons). Although more than 60 countries have discovered and mined platinum, their reserves are highly concentrated in South Africa and the former Soviet Union. Among them, the South African (azania) platinum reserves are about 6.5438+0.2 million tons, and Transtuva platinum mine is the most famous and largest platinum mine in the world. The reserves of platinum in the former Soviet Union were 1.866 tons. Natural platinum with a weight of 8-9 kg was found in the platinum mine of Ural placer, and natural platinum with a weight of 427.5 g was obtained in the primary mine. Their total reserves account for 98% of the world's total reserves. Every year, the annual output of platinum in the world is only 85 tons, far less than that of gold. In addition, the high melting point of platinum makes it more difficult to purify and smelt platinum than gold, and consumes more energy. So its price is more expensive than gold. Platinum is elegant and luxurious, symbolizing purity and nobility. Therefore, people regard it as a symbol of love and make engagement rings to show that love is pure and eternal. If diamonds are set in silver-white platinum supports, sparkling diamonds and dazzling platinum complement each other, setting off the whiteness, preciousness and elegance of diamonds.
Platinum jewelry is mainly popular in developed countries and regions such as Europe, America and Japan. Among them, the Japanese prefer platinum jewelry most, and its sales account for about 75o% of the world's platinum jewelry, so it is called "the country of platinum".
China's platinum group mineral resources are few, and the reserves are less than 1% of the world's reserves, which can only meet a few percent of the demand and are mainly used in industry. The production of jewelry platinum started late. At present, only a few local manufacturers produce similar products.