(ORDO NEWS) — In the finale of the classic western McKenna’s Gold, Gregory Peck’s character rides off into a brighter future on a horse with a pair of large leather trunks stuffed with gold ingots strapped to his back.
Until now, this scene did not cause me any questions, but now I think that in reality this horse would have broken his back.
That there are films half a century ago – and in modern action films there are often scenes where a robber quickly runs away from his pursuers, carrying huge bags or suitcases stuffed with ingots of gold or platinum in both hands. In fact, this is absolutely impossible. After all, silver, gold, platinum are very heavy …
To see this in practice, and not just by studying the table of densities of precious metals, you need to get to where gold is available in large quantities.
A measured bank ingot the size of a chocolate bar weighs 1 kg! I put a bar of platinum in my palm and can’t believe my eyes. A metal parallelepiped, close in size to a piece of laundry soap, pulls the hand like a weight. The brand gives accurate information: 3.359 kg!
The chance to weigh almost four kilograms of precious metal in the palm of your hand is not for everyone. Fortunately, this chance was given to us by the Yekaterinburg Non-Ferrous Metals Processing Plant (EZOTsM), also operating under the Plaurum brand.
This is one of the few enterprises in Eurasia engaged in the extraction of precious metals in the purest form from natural raw materials. Then these metals are turned into bank ingots, used in instrument making, nuclear energy and the jewelry industry. The plant’s products are known not only in Russia, but also in many countries of the world.
Measured bank bullion of gold and silver Unlike heavier standard bullion bars, they are weight standards and weigh exactly 1 kg
First trial by fire
Gold occurs naturally in primary and alluvial deposits. Primary deposits were formed in the earth’s crust due to magmatic processes. They contain native gold in the form of veins, which are usually mined using a quarry or mine method.
However, when the vein comes to the surface, nuggets can be found right on the ground. But this is a rarity. Alluvial deposits, derived from primary ones, are formed after a long-term impact on the latter natural factors. Alluvial deposits are located in the channels of mountain rivers, on the shores of lakes and mountain slopes.
To get the noble metal out of them in the form of golden grains of sand, the rock must be washed out, extracting concentrate from it (translated from German – “washed ore sediment”). The extraction of gold-bearing concentrate is carried out by gold mining companies and artels of miners.
The concentrate – enriched raw material – already contains a large percentage of gold and looks like a coarse-grained powder of a dirty yellow color. It is in this form that it enters the EZOCM and, before turning into gold of the highest standard, goes through a whole technological chain. We happened to see its beginning in the smelter.
The master puts a crucible with slip gold into the induction furnace. As the powder heats up, it slowly settles, as if sugar or ice chips are melting. Finally, the last grains melt, and the melt boils in the crucible. This is how the receiving smelting goes: a small batch (they say “place” at the plant) concentrate came to the plant from the miners’ artel.
The task of the first heat is to evaluate the chemical composition of the raw material and choose the optimal scheme for extracting pure gold from it.
Melter Evgeny Vetoshkin takes a long tube of quartz glass with a black rubber pear at the end and lowers the other end directly into the melt. Due to the rarefaction created by the pear, part of the metal is sucked into the tube, where it solidifies.
Then the tip of the tube breaks, and a metal rod falls out of it – a sample. “It is rather difficult to take a representative sample from a frozen ingot, because due to the large amount of impurities, the main component to be determined, in our case, gold, will not be evenly distributed throughout the entire volume of the ingot,” says Dmitry Serikov, Head of Production at EZOCM JSC.
Bowl of fire – The crucible for melting is the main tool for the production of non-ferrous metals. After the end of its service life, it is ground into powder, from which particles of precious metals are extracted
Boiling Gold and “Frost Stone”
The melt continues to “boil”, while the master pours a scoop of white powder into the crucible. Then another. This is a ground mineral cryolite (“frost stone” in Greek), which acts as a flux.
The concentrate contains base impurities, as well as organics – all this cryolite draws into itself, forming a block of slag that is easily separated from the ingot. The float is finished. The crucible is removed from the furnace and its contents are poured into a mold (mould).
Due to the special shape of the mold, the ingot, resulting after cooling, resembles an artillery shell. The “warhead” is a cone with a rounded end in the color of yellow metal, the “sleeve” is a gray cylinder of slag.
“Looking at the resulting ingot,” says Dmitry Serikov, “it can already be said that the gold content in the raw material was high. What exactly and what else is contained in the ingot.
The melter takes a solidified flammable sample, makes a thin strip of foil out of it on a special rolling mill, and then sends it to the laboratory by pneumatic mail. There, the metal is dissolved in acid and, by examining the solution, the chemical composition of the sample is determined with high accuracy.
The picture shows the end of the melting of silver. Liquid metal flows into a barrel filled with water and cools there in the form of granules. A stream of silver in water is stirred with a wooden spatula
Disappears in acid
Mined gold is never 100% pure. Native gold always contains silver. If silver is more than 25%, then such a mineral is called electrum. Primary ore rich in such minerals is smelted after beneficiation to produce doré. An alloy containing both gold (about 70%) and silver (about 30%) is sent to refineries.
Doré is thus the raw material for the production of both precious metals. If the share of, for example, silver in the batch of gold concentrate received at the plant goes beyond 5%, a special technological operation is needed to remove the excess.
This is vacuum distillation. The alloy is heated in a furnace under high vacuum to the temperature of evaporation of silver from its surface, followed by trapping of these vapors on a special condenser funnel.
Then the next smelting is ahead of the gold: it is turned into granules. Due to the presence of too many impurities in the metal, the granules, when cooled, acquire a torn shape resembling popcorn. But the form is not important here – soon it will not exist at all.
The granules are sent to the refinery (usually the minimum batch is 50 kg), where the metal is completely dissolved in aqua regia (a mixture of nitric and hydrochloric acids). Refining is a chain of chemical reactions, and its product is a “metal sponge” – a precipitated, sticky dark brown powder.
The Yekaterinburg plant works not only with gold, but also with silver and platinum group metals. The weight of a standard silver bank bar is 28–32 kg. It is incredibly difficult to tear off the silver “brick” from the floor
But, despite this appearance, the “sponge” is already pure gold. It again enters the melting shop, where it turns into granules – now even, rounded. Granules can be used as finished products for the production of gold-based technical alloys used in the production of industrial parts (contacts, conductors, etc.), they can become a component of jewelry alloys.
Here, in the smelting shop, bank ingots are made from them – measured (from 50 g to 1 kg) and standard (about 12 kg). “An ingot is an investment tool and at the same time a weight standard,” says Dmitry Serikov, “that’s why when melting, we cast exactly one kilogram of melt plus 0.04 g into the mold.
This is insurance in case of a slight error in the scales anywhere in the world where our ingot.” Bank bullion consists of gold of the highest standard.
This means, that it contains 99.99% pure gold and only a maximum of one thousandth of impurities, from which you still can’t get away. Nevertheless, the composition of these impurities is regulated, and depending on their total amount and the amount of each element, different grades are assigned to gold.
A story is told at the plant about how one of the directors of the EZOCM led a tour of the workshops and, as a small attraction, offered the tourists to pick up an inverted standard bank gold bar with one hand and put it in their pocket. In this case, they say, a participant in the tour could take the ingot as a gift.
But no one, of course, managed to perform such a trick: a standard bank ingot has the shape of a truncated pyramid, and the fingers simply slipped off the inclined faces of the 12-kilogram “brick”.
Granules of pure gold, which will go to bank bars or industrial parts, and will also become part of jewelry alloys
Bit by bit
Most of us have little idea of the true properties of gold, because we communicate with it mainly through miniature and light jewelry. And so we don’t know that gold is not only heavy, but also a very soft metal.
It is distinguished by unique plasticity, it is possible to roll the thinnest foil from it and pull ultra-thin wire, but the constructive material from it is useless. Therefore, jewelry gold of the 585th test of the precious metal contains a little more than half (58.5%).
Everything else is strengthening alloying components: copper, silver, nickel. There is no “white” or “red” gold in nature: in its pure form it is always yellow, and different colors appear in jewelry alloys depending on the presence of one or another alloying additive. If, however, we make, say, a ring of gold, which goes to bank ingots.
With each contact with foreign objects, gold easily gives up part of its mass. And therefore, special measures have been taken at the EZOCM against losses. The person who took the ingots in his hands goes to wash his hands.
But the water does not go down the drain, but settles in a special tank, after which precious metals that have got there are released from it. Filter traps are installed on ventilation systems. Nothing – not wiping materials, not old work clothes, not gloves – leaves the factory until they are burned and sent to the ashes for refining.
Old crucibles that have worked their way out, keeping the smallest traces of precious metals on themselves, are ground into sand, from which particles of gold, silver, platinum are then washed out… And all these measures allow saving a tangible amount of precious raw materials.
The last point of our acquaintance with the enterprise was the pantry, where precious metal ingots are very prosaically laid out on the shelves.
How much all this costs, it’s scary to even imagine. However, where does the money? Getting acquainted with the unique production and weighing a “brick” of gold in the palm of your hand is an invaluable experience.
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