How are diamonds mined?

Diamond stands out among any other natural substances for its extraordinary hardness, and at the same time it is quite rare. These and other extraordinary properties make such a rock very popular all over the world. Therefore, it is important to know how they are extracted in nature.

The paradoxical feature of diamonds is that they are very hard, although they are composed of carbon. The same carbon, only with a different crystal lattice, forms graphite (the softest of rocks). All diamonds that are mined are formed by extremely tightly combined atoms. Exceptional strength does not prevent the mineral from being brittle: upon a sharp impact, the crystal breaks. It is believed that the origin of diamonds took place at a depth of tens or hundreds of kilometers, over hundreds of millions of years.

Most often, in order to mine diamonds on an industrial scale, kimberlite pipes are sought. These geological formations are named after the city of Kimberley, in South Africa, where this type of deposit was first discovered. The formation of the mineral in the depths of the earth occurs at very high temperatures and pressures. Science has not yet worked out the final version of the origin of diamonds.

Geological structures containing diamonds are gradually being destroyed by wind and water. Crushed stone, pebbles, gravel and other surrounding rocks are moved around. There are only assumptions of varying degrees of reliability. As a result, loose deposits are formed. Another type (but much rarer) is an especially hard form of carbon, which appears in places where meteorites fall.

Each of these cases has its own range of shades, however, it is important to pay attention to the value of specific colors. Rare (and therefore valued) transparent blue, green and pink coloration. The cost of stones that are 100% colorless is even higher.

Regardless of which version certain specialists adhere to, they all agree on one thing: important stages of stone formation take place at great depths. From there, together with the magmatic flows, the substance enters the top. At a certain moment, explosive tubes actually appear. Their depth does not exceed 1500 m.

Almost everyone knows about industrial diamond mining in Yakutia and South Africa. But it is also being conducted:

• in the Arkhangelsk region;
• Western Australia;
• Canada;
• Congo;
• Botswana.

There is practically no mining from placers. They play only a small role in the global supply of rough diamonds. And the stability of the supply of products mined on the surface is questionable. The open pit method (quarry) is usually practiced when extracting diamonds from a depth of 600 m or less. In deeper pipes, rough diamonds can be extracted mainly with the help of mines.

They are trying to postpone the construction of mines until the last moment. Usually these are areas either in the permafrost zone, or in particularly hot areas. Often, at great depths in workings, it is required to continuously pump out underground water. The rock from the quarries and then from the mines is transported by large trucks to the factories. There, this raw material is purified with water.

Modern quarries have already reached almost the maximum depth to which they can go. Experience has shown that the small working width and the steepness of the sides complicate the matter further. From the very beginning, it is planned to extract diamonds by the open method with a breakdown by stages. This technique makes it possible to more often monitor changes in rock properties and production in general. Accordingly, it facilitates the selection of optimal methods and schemes of work.

In order to correctly select the side parameters at the very beginning of development, it is necessary to use exploration wells. The samples taken from there are subjected to physicochemical tests according to a special program. Additionally, experience is taken into account when working out similar open pits. The contours of the sides are optimized during design. They cannot be conducted very gently, otherwise the work becomes much more difficult.

For all intermediate contours, the properties of rocks are continuously refined taking into account samples taken from each batch. Sometimes full-scale tests are practiced right on the board of the quarry. Particular attention is paid to assessing the degree of rock cracking. Additionally, they study how they behave on steep slopes. The angle of inclination of the real side is laid in projects from 50 to 55 degrees.

Usually the process takes months, but sometimes it takes several years. Special calculations are necessarily used. Only they allow us to conclude where the solid deposits are located, and where random finds were made.

Quarries as well as mines or mines are most often built in hard-to-reach places. Therefore, a residential and industrial infrastructure is being created around. A number of examples are known when a deposit became a city-forming object for a fairly large city. Since it is unprofitable to trade in raw materials, processing plants are being built. From them, the diamonds, finally separated from the waste rock, are transported to the cutting enterprises.

They also naturally try to organize cutting nearby. The deeper the deposits, the more money will have to be invested in their development and field development.

For a very long time, it was possible to obtain diamonds only from India. But no matter how rich the mass was deposited there in due time, natural processes, by the end of the 17th century, these reserves were already largely exhausted. Production productivity dropped sharply. However, the development of technology has made it possible to turn the tide. The situation changed dramatically after the discovery of kimberlite pipes.

To understand more deeply how mining takes place, we must return to the question of the appearance of diamonds in nature. The prevailing theory is that they form at depths over 100 km, where very high temperatures and pressures develop. The rock rises upward during volcanic eruptions.

Finding suitable objects and setting up production on them is possible only at significant costs. The preparatory process is already expensive, complicated and long. It is believed that for every 2 carats of rough diamonds extracted, more than 1,000 kg of rocks have to be processed. Quarries are created first by blasting. Boreholes are drilled and explosives are placed there, then the rock is crushed layer by layer.

Deepening of workings is carried out until the production of minerals stops. Separation of valuable raw materials from ore is a big problem. The following approaches are used:

• the work of the fat plant;
• search for the required crystals in X-rays;
• immersion of rocks in special suspensions.

The fat method involves mixing the extracted rock with water, and then pouring it onto a surface lubricated with special grease. Crystals are retained on the fat. A more advanced technique is X-ray transmission. In most cases, the suspension method is used. In a liquid with a high density, waste rock is drowned, while pieces of carbon appear on the surface.

In the recent past, Brazil was the leader in diamond mining, followed by Australia. But Australian diamond deposits are gradually depleting themselves. Angola is also among the six leading states. However, in Canada, Botswana, much more valuable gems are extracted.

Both placers and mines are rapidly being developed. We have to systematically update the network of mines and open pits. The deeper the same quarries, the less likely it is to find a significant amount of raw materials. Therefore, an increasing number of open pits more than a kilometer deep are being closed due to unprofitability. The mining method of mining is more complex and dangerous, however, it is economically profitable.

The largest diamond deposit in our country is Mir in Yakutia. Its development has been going on since the late 1950s. From 1957 to 2001 there, a quarry of a mineral was extracted for 17 billion dollars (at current prices)... To ensure such a result, it was necessary to crush, lift and remove about 350 million cubic meters. m. waste rock. By the end of the 1990s, the amount of production reached such dimensions that dump trucks had to drive 8 km from the point of production to the warehouse. In 2001, due to the excessive complexity of the quarry, it had to be mothballed.

And in 2009, the use of the Mir mine began. The water circulating underground is not just pumped out - it is redirected through pipes into special faults discovered by geologists nearby. In 2013, the deposit produced another 2 million carats of excellent diamonds of technical quality. The enterprise operates 7 days a week, the duration of the miner's shifts is 7 hours.

The harvesters used in the mine are equipped with booms with cutter bits. The teeth, although made of hardened metal, are subject to very heavy wear. Therefore, each shift starting work inspects the working part of the tools. If necessary, it is replaced immediately. The crushed rock is transported to the exit of the mine using conveyor belts.

In a number of diamond mines, separate bottom parts are deliberately left intact during development. Their thickness can reach several tens of meters. If these structures were developed, it would be almost impossible to avoid the flooding of the fields. Additionally, layers of waterproof materials are used for protection. The movement of rocks in mines and quarries is carried out using colossal trucks (sometimes with a capacity of more than 100 tons).

In the past, the situation was very different. Until the 19th century, no mechanical devices were used. The "queen" of diamond mining was an ordinary mountain shovel or pickaxe. Sometimes they simply rowed river sand and manually passed it through a sieve. But such methods have long lost their feasibility.

And among the two methods - open-pit and mine - the second option turns out to be more attractive. Much attention is paid to safety rules in the daily work of diamond miners. No one is allowed underground without a helmet with a built-in flashlight and without a self-contained breathing apparatus. It is strictly forbidden to leave it more than 3 m away from you. Ventilation must be provided, thanks to which it is normally easy to breathe underground.

Russian diamond mining enterprises (especially those located in Yakutia) are perhaps the most high-tech in the world. They use transport designed for very severe frosts. Very strict temperature requirements are imposed on other equipment as well. It is believed that it is possible to commission a new field from scratch for $ 3 or 4 billion. Whether this amount includes the costs of primary geological prospecting - no company reports.

But later, when a quarry or mine is ready, it will be much cheaper to use them and develop workings. The greatest challenge with the underground method is maintaining an optimal working environment. The main shafts for lifting rock can be used in case of accidents. Recreational niches are being prepared in different places of the mines.

For more information on how diamonds are mined in Russia, see the following fideo: