All About Palladium

Palladium - where is it mined, what is it and what does metal look like? All these questions arise quite often, because the name of the chemical element remains at everyone’s ears thanks to jewelers and stock exchanges. No less interesting are the methods of extraction and properties, the test and comparison with platinum. To find the most complete answers, you need to study as much as possible information about palladium - a metal that originated in the depths of space.

The chemical element Palladium, designated by Latin letters Pd, is known to every schoolchild. This noble metal belongs to the group of platinoids. In the periodic table, he was assigned atomic number 46. Palladium looks like a silver-white metal; it is extremely rare in nature. Most often, it can be found in multicomponent minerals.

A sample of palladium in jewelry is most often indicated for other metals. Typically, gold or silver is used for these purposes. Commemorative coins of high value are made of 999th pure metal. In bullion and products, the following assay marks are most often found: 500, 850, 900, 950 and 990.

The metal got its name thanks to a chain of randomness. According to the legends of ancient Greece, the Palladium was the wooden face of the goddess Athena Pallas, who fell from the sky - the talisman guarding the walls of Troy. When in 1802 an astronomer from Germany discovered a new celestial body (an asteroid), he gave him the name Pallas.After some time, a chemical element was also discovered, which received a similar name due to the popularization of a long-forgotten myth in Europe.

However, palladium fully lives up to its name. The appearance of the new metal was also not without a series of hoaxes. For example, its appearance was announced about a year before the actual discovery of the chemical element. Moreover, instead of a scientifically based view, a sample was sent to a merchant specializing in the sale of minerals in London. The ingot set up as a lot caused general excitement, and then it was still acquired by a chemical scientist.

Of course, the new owner of the "palladium" did not buy it at all for the purpose of enrichment. In an effort to expose the fake, a chemist named Cenevix made every effort to prove the artificial origin of his acquisition. It was announced that this is an alloy of mercury and platinum synthesized according to the previously approved method of the Russian scientist Musin-Pushkin. In response to the exposure, a new message appeared in the press: the seller was offering a substantial reward to someone who could synthesize palladium.

Following this, a mysterious anonymous person appeared. It turned out to be William Hyde Wollaston, known by then as one of the pioneers of UV radiation, the designer of a goniometer and refractometer, that is, a well-known and respected person. It was he who, in the course of experiments with crude platinum, was able to separate from it first palladium, and then rhodium, which are present in the composition in the form of impurities. As evidence, Wollaston provided experimental results.

Interesting that for the first time it was possible to isolate palladium from ore obtained in South American lands. As a matter of fact, here too could not do without a chain of happy coincidences. Initially, the goal of Wollaston's experiments was to separate pure platinum from impurities of mercury and gold. To do this, he used a solution of nitric and hydrochloric acids, known as "royal vodka", and then precipitated the element he needed with ammonia. The experimental results were quite unexpected - the liquid turned pink.

In further attempts to find the causes of unusual staining, the chemist used various substances. In addition to pure platinum, he managed to get the same palladium - the metal is lighter than mercury, an unusual light silver color. From the remaining sediment a year later, he also isolated another chemical element called rhodium.

When the history of palladium was revealed, there was no doubt about the existence of a new metal. Scientific calculations and the exact results of chemical experiments easily confirmed the words of Wollaston. Since 1805, palladium has been recognized by the world community.

Palladium - metal with the symbol Pd and established amu 106.42 (1) was included in the short periodic system when it was created. The pure color is silver-white, close to silver or mercury. The metal consists of stable isotopes of the following types: 110Pd, 108Pd, 106Pd, 105Pd, 104Pd, 102Pd. The 107Pd isotope is also present among the components, having radioactivity with a very long half-life of substances.

Palladium isotopes can be a by-product of a nuclear reaction. The metal itself is not at all radioactive. Its chemical and physical characteristics have the following meanings:

• boiling point - 2940 degrees;
• melts at a temperature of 1554 degrees;
• density is 12.02 g / cm3;
• hardness is low - it is a soft metal with an index of 373 MPa;
• does not dissolve in water;
• there is no reaction to ammonia hydrate, dilute acids and alkalis.

Palladium has high ductility and ductility, lends itself to broaching in the wire. Its mechanical properties can be improved by adding rhodium, ruthenium, nickel or cobalt to the alloy. The reagent in which palladium is dissolved is “royal vodka”.In this, it is similar to platinum. Palladium itself is valuable as a chemical reagent, because it dissolves hydrogen, and more volatile matter is actively evaporated in air.

Palladium in its pure form is not magnetized. But products from it may possess such properties. Nickel and cobalt are sensitive to the magnet in palladium alloys. When combined with gold, the latter brightens it, gives a light silver tint, even in the amount of 1-2%. Titanium even in minimal proportions increases its resistance to hydrochloric and sulfuric acids.

The formula of palladium oxide is PdO, oxidation occurs upon contact with oxygen only when heated above 300-350 degrees. After that, a characteristic tarnished film appears on the surface. With further heating to 850 degrees and above, decomposition into pure elements occurs, the original properties are restored.

Unlike many other platinoids, palladium is found in a native form, this form is called allopalladium. In its pure form, it is obtained only by chemical means. Palladium is present in the sun, in iron meteorites, its share reaches 7.7 g per 1 ton. The main reserves in the earth's crust are concentrated in Russia, Transvaal, and Colombia.

Approximate volumes of palladium in the bowels of the earth are estimated at 6%, in this it exceeds gold. Nevertheless, metal is still classified as rare and precious. Chemical isolation involves the concomitant mining of platinum, minerals or metals. Most often it is necessary to separate it from elements related to the properties.

For example, Palladium platinum in the Norilsk deposit contains up to 40% palladium, and porpecite (a type of native gold mined in Brazil) - up to 10%. The main deposits and reserves of this metal are concentrated in Russia: on the Kola Peninsula, in the mountains of the Urals. There are undeveloped, conserved objects. These include the Norilsk deposits of this valuable metal.

Palladium is produced in various ways. Pure metal can be recovered through the industrial mining of platinum-bearing ore groups. Deposits of the primary (primary) and loose types are used. Palladium is mined along the way, in South Africa and the Russian Federation, mainly from deposits of platinum and nickel. Pure metal is obtained at refineries where it is isolated and concentrated into ingots or stored in powder form.

In indigenous deposits, only associated palladium mining is possible. On loose or secondary it is obtained in pure form. If the development of deposits is carried out by open pit mining, the ore is extracted using earthmoving equipment. In the mines in the thickness of the ore layer, holes are drilled, explosives are laid. After its detonation, the soil is finalized, rises to the surface, sent for enrichment.

The processing of mineral rock in order to isolate valuable metals and other components is a long and laborious process. It is called enrichment. On average, per ton of such raw materials accounts for no more than 6 g of a valuable substance. To increase this proportion helps to artificially increase the proportion of metals by making a platinum-containing concentrate. The ore processed in this way gives up to 1.4 kg of palladium per 1 ton of raw material.

Further receipt of palladium occurs in refineries. It is here that the isolation of the chemical element in its pure form is carried out.It occurs by eliminating impurities through refining, after which palladium is turned into powder or fused into granules, ingots. The entire production - from industrial mining to the release of finished metal from the plant - takes about 6 weeks.

All existing varieties of palladium alloys are standardized by GOST requirements. The following proportions are established in the Russian Federation: 50% or 85% palladium. In Europe and North America, the main alloy has the 950th sample, that is, it contains 95% pure palladium and 5% platinum. The highest concentration is found in Russia - 999 g of metal per 1 kg, used in the minting of jubilee and commemorative coins, medals.

In alloys with a predominance of palladium, the following groups of metal combinations can be distinguished:

• with platinum;
• with iridium;
• with copper or cobalt and silver;
• with pure silver;
• with titanium.

The use of these compounds in many respects depends on which tasks are posed. For instance, palladium-silver alloys are most often used in jewelry. Compounds with gold or platinum are also used here. Palladium-iridium alloys are used for the manufacture of industrial semi-finished products, they are formed through deformation processes, hot and cold methods.

The difference between metals is often sought both in groups derived from the same ore, and in unrelated species. This is especially often done when choosing jewelry, when you need to distinguish palladium from silver, white gold or platinum, determine which alloy option is better. It is better to talk in more detail about what to consider when comparing palladium with other metals.

1. Externally, palladium is practically indistinguishable from silver. Moreover, the difference in price is significant: 1 g of palladium costs like 100 g of silver. At the same time, silver darkens over time, but no palladium.
2. With platinum, the main difference is in specific gravity. Palladium is lighter, less dense (almost twice), it dissolves in heated nitric acid. When checking with reagent from aqua regia and a 10% concentration of potassium iodide, palladium will have a reaction, but not with platinum.
3. Today, palladium is compared with gold except in the investment sphere. Here, this rare metal is confidently ahead of a more widely known competitor. In the presence of a palladium ligature, gold does not lose value.

Precious palladium is widely used in various fields. For example, in oil production it is used as a catalyst. The metal finds a similar application in organic synthesis or during hydrogenation, in working with fats. Hydrogen is purified through palladium by diffusion of materials; alloys of palladium and yttrium are most often used. In its pure form, it is used for the reversible accumulation of this substance.

In the medical industry, dentures are made from palladium; it is part of pacemakers. For brachiotherapy of cancer, the palladium-103 isotope is used.

The use of this platinoid in electronics is highly appreciated. In the form of chloride, it is used as an activator in metallization in electroplating, it helps to precipitate copper. In electrical contacts it is used as a non-oxidizable and insoluble element. This metal can be found in ceramic capacitors used in the manufacture of television and radio equipment.

In jewelry manufacturing, palladium is best known as a master alloy for making white gold. As an independent component, palladium is alloyed with silver and platinum in a proportion of 50:50 or 85:15 parts. Engagement rings and other jewelry are valued; diamonds look spectacular in a palladium frame. This metal also acts as a raw material for the production of coins and medals, issued in a limited edition, for commemorative events.

When choosing palladium jewelry, it is very important to pay attention to their composition. In EU countries where nickel is prohibited, only metal of the 950th sample is presented in an alloy with platinum. In Russia, additives are still found in the form of this toxic metal, which can provoke a severe allergy.

It is worth considering that the modern jewelry industry mainly represents men's jewelry with this metal. Palladium cufflinks and tie clips look noble and elegant. Signs and palladium crosses look interesting.

Women's jewelry is most often made in a combined version, with enamel inserts, with precious stones. Rings, earrings, bracelets and pendants from it look interesting - you can choose options to your liking.

Palladium jewelry is still quite rare, but this metal is present in many alloys. Accordingly, it is worth considering its features when caring for metal products. The main recommendations will remain the same as for platinum.

1. Dry cleaning with soft cloths is periodically recommended.
2. Wet care with severe contamination is performed using a mild soap (alkaline) solution.
3. Special wipes for cleaning jewelry are produced. They can be used if you do not want to carry out liquid treatment.
4. The appearance of scratches on palladium is practically excluded. If it is still damaged, professional polishing will be required, it will not work to polish it manually.
5. It is not recommended to store products made of platinoids, including palladium, together with silver and gold. Such carelessness can lead to damage to softer metals.

For how to separate gold, palladium and platinum in the presence of copper, see the next video.