This post first appeared on Russia Insider
In the first half of 2019 alone, production grew by a whopping 10%. Russian gold manufacturing is booming.
Recently, the Ministry of Finance has published data on the production of precious metals in Russia. The production of refining gold is a record high. Refining is the process of obtaining chemically pure gold. In the first half of 2019 alone, it grew by more than 10% and exceeded 110 metric tons.
On today's show: All is not gold that glitters. How do Russian scientists get precious metal from waste?
“Pyrite cinders can act not only as a source of precious metals but also as a source of iron.”
Transparent gold for a new generation of optoelectronics.
“These films conduct current like bulk gold. But, at the same time, they are absolutely transparent.”
What properties of artificial gold are superior to those of natural gold
“ In terms of the electrical properties, these films are in no way inferior to bulk gold and, in some sense, they're even superior.”
Natalya Popova, anchor: “Scientists strictly follow the golden rule — measure thrice and... No, not cut once but extract. Gold from ore.”
Research Institute of Comprehensive Exploitation of Mineral Resources of the Russian Academy of Sciences. Very soon, this ground ore will become gold.
Victoria Getman, Senior Researcher: "We send the dried concentrate to the geoanalysis laboratory. This concentrate is analyzed for the gold content."
Doctor of Science Victoria Getman doesn't perceive the phrase "be worth its weight in gold" as a figure of speech. To get only 3-5 grams (0.09-0.16 troy ounces) of valuable metal, you have to process a whole metric ton of ore.
Tamara Matveeva, Complex Extraction Department: "Gold is extracted from refractory sulfide gold-bearing raw materials. These ores are characterized by small inclusions of gold, up to micron sizes."
Gold is included in the structure of sulfide minerals. Therefore, its extraction is an especially complicated process. To increase the efficiency of gold recovery, scientists have developed unique reagents — thermomorphic polymers which have become a good alternative to import supplies.
“These clay minerals and carbonaceous matter are natural sorbents of gold.”
The main method for gold extraction is flotation.
“After grinding, we pour the pulp into the flotation chamber. That is, this is the initial mixture of ore with water.”
Useful minerals have hydrophobic properties. They adhere to air bubbles that are in the flotation pulp, float to the surface and pass into the concentrate.
“We add a reagent to increase the flotation activity of minerals. After the minerals reacted with the reagent, we can start the process of extracting the concentrate. To do this, we turn on the air intake and foam remover. Bubbles formed which particles of gold or a gold-bearing mineral attached to.”
The main method for processing gold-bearing concentrates is the leaching process. This is a selective dissolution of a valuable component, which is transferred from the solid phase to liquid.
“The stand consists of an upper tank which contains gold-bearing material and a lower tank which contains solvent. Using a metering pump, gold-bearing material is irrigated. The solvent transfers it to the liquid phase.”
Gold-containing materials are obtained from the so-called product solution using sorption methods. These materials are smelted into ingots. Some of them are supplied to the jewelry industry. Others will be sent to bank vaults.
Gold is a symbol of wealth and power. At all times, it was the engine of the world economy and often became the cause of the most bloody wars. Today, gold mines are a thing of the past. This precious metal can be obtained in the most unexpected ways. Did you know that gold can be extracted from industrial waste?
These piles are pyrite cinders. It is a by-product of the production of sulfuric acid and pyrite concentrate. Around the world, a threatening amount, millions of tons, has been accumulated over decades. Pyrite is an iron sulfide. When it is burned, sulfur dioxide is released, which is used to produce acid. Pyrite cinder is formed as a by-product.
Andrey Smorokov, a graduate student in the nuclear fuel cycle department of Tomsk Polytechnic University joined the group of initiators of the creation of a pyrite cinder laboratory when he was a student. He and his colleagues found out how to extract gold and other valuable metals from this waste. But a whole metric ton of pyrite cinder yields only 6 grams of gold (0.19 troy oz). But there are other valuable elements scientists are interested in.
Andrey Smorokov: "Pyrite cinders can act not only as a source of precious metals but also as a source of iron. That is, it can be used in metallurgical production, but it is necessary to carry out preliminary cleaning."
The extraction of valuable components is carried out using solid-phase sintering with subsequent conversion to acid solutions which then undergo the hydrometallurgical process.
- This is the source material for the operation of this installation, right?
- Yes, this is the feedstock mixed with the reagent that is fed to this unit.
- Can we start the process now?
- Oh, sure. Here we have a dosing hopper. We feed our mixture in here. From here, we feed cinder first and then we feed ammonium chloride from the second hopper.
-Within three to four hours at a temperature of 350°C (662°F), pyrite cinder and ammonium chloride are mixed and ground. Orange is an indicator of a large amount of iron. The next stage of processing is hydrometallurgical separation, the separation of each of the components using chemical reagents.
- The product obtained after grinding is dissolved in water in this mixing device. The result is such a solution.
- What's in it?
- There are ferric chlorides, cuprous chlorides, and all other valuable components. Then we filter this. We separate the reacted part, which is soluble in water, and the unreacted part, mainly silicates and gypsum.
The purified and filtered solution is sent to the separation of precious impurities.
- We get this solution.
- It's cleaned of iron, right?
- Yes, but it still contains copper, zinc, gold, silver, and other non-ferrous metals. The resulting iron precipitate is filtered off, calcined, and then sent to metallurgical production.
The method created in Tomsk is unique. It has no parallel in the world. Possibly, it'll be Russia that will be the first country to build a pyrite cinder processing plant with a capacity of up to 500 thousand metric tons per year.
- Can you say that the development of science is a priority for Tomsk?
Sergey Zhvachkin, Governor:
- We're the only Russian city whose charter states the importance of the university for the city. You can create a university or its departments. But it takes decades to create a science school.
- Can you name something created in Tomsk that has some feasible results?
- For example, Sibur. Do you know what they are doing now? Accelerated polymer degradation. Or a decrease in the half-life of uranium. Our scientists, together with Gazprom Neft, are studying the Paleozoic problems. Today, we have all the large companies — Rosatom, Rosneft, Gazprom, Gazprom Neft, Inter RAO.
- That is, companies come for scientific personnel. Personnel is the basis.
- The Soviet slogan goes "Personnel is everything" and it's true. Many Danish, Dutch, American, Japanese companies want to get our specialists. We graduate unique specialists. If a young man starts working for Roscosmos in the fourth year, he's never going to quit because it's an interesting job. If he works at Rosatom, he will also never leave for Denmark or Sweden, for example, because the decision of the future is complex for scientists.
Transparent and flexible electronics of the future. This unique invention of Russian scientists will help in creating more advanced neurointerfaces between the brain and the computer. This is quasi-two-dimensional gold.
Alexey Arsenin, Laboratory of Nanooptics and Plasmonics: "This is a material whose atoms are very tightly connected in one plane, but the bond between its layers is weak. If we take several lattices of the material, they are very weakly connected with each other and can be separated. But the atoms in one plane are difficult to separate."
The first two-dimensional material that became known to mankind is graphene. Andrey Geim and Konstantin Novoselov, MIPT graduates, received the Nobel Prize for their research of graphene. But two-dimensional gold still could not be obtained. During sputtering, the atoms of most metals are assembled into particles resembling droplets, which gradually come together forming a metal grid. Only after the grid is full, a solid surface appears.
Alexey Arsenin: “You can't get one layer of gold. It is necessary to obtain a layer of single atoms on the surface of some material. We were able to obtain two-dimensional metal films by sputtering metals in high vacuum.”
For the first time, two-dimensional gold was obtained here, in a clean zone of the MIPT core facility.
Elena Titova, Laboratory of Optoelectronics Employee: "First, we took substrates of silicon and a layer of silicon oxide. Then, molybdenum disulfide was sprayed on top of them by chemical vapor plating. This is important because it contains sulfur and gold is able to form stable compounds with sulfur."
Her colleagues say that Lena spends literally days and nights in this laboratory. She is an expert in the optoelectronics of two-dimensional materials. It seems she's found the perfect material for the most precise optics.
Elena Titova: “Gold was deposited on a molybdenum disulfide layer by electron beam evaporation. The resulting films with a thickness of only 3-4 nanometers had the same properties as bulk gold, that is, they were solid, unlike gold deposited on other substrates.”
These thin films of quasi-two-dimensional gold are characterized by high transparency and good electrical conductivity, in contrast to thin films of gold deposited on a silicon oxide substrate, where it is first deposited in splatters and then a solid film is formed at a thickness of at least 20 nanometers.
Elena Titova: “This is a crucible with a gold target inside. A high-energy stream of electrons hits here. At high temperature, the gold evaporates and deposits on the surface which is held above.”
This technology opens up new opportunities in the field of electronics. Very soon, a new class of optical materials and even contact lenses with an integrated display may appear.
Analysts say there's only a 20-year reserve of gold in the bowels of the Earth. But Russian scientists aren't worried about the fact. They've already synthesized its analogs and now can extract gold from coal and even sulfuric acid. It sounds like alchemy but it's science.
This post first appeared on Russia Insider
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