Salt deposits

The Ileck deposit

In the unique nature created Iletsk deposit mining of edible common rock salt is conducted.

The first scientific exploration of the Iletsk salt was conducted by M.V. Lomonosov. He wrote: “The Iletsk natural salt is harder than other ones and if ground up gets a very white colour and does not absorb the air humidity. For these reasons one should prefer this salt to other ones”. The Iletsk salt is the natural crystal mineral, ecologically pure product of the early stage of drying up of ancient seas. A long time ago on the territory of the Orenburg region there was an enormous sea which after thousands of years dried out. As a result there occurred a very valuable and useful product “the Iletsk salt” which consists of ecologically pure 270 million-year-old crystal minerals. The salt consists of biologically active macro- and microelements in balanced ratio.The Iletsk salt was recognized as the best in the world and was awarded with the European gold prize at the exhibition in Paris in 1996.

The Iletsk rock salt mine represents a salt cupola with a salt core brought out to the surface. In horizontal section the salt body has the shape similar to ellipse, the size of which according to the geological surveys is on the horizon 160 m. long axis 1850 m., short axis 825 m., on the horizon 215 m. long axis 1920 m., short axis 840 m. Up to 600 m. deep the size of the major deposit extends to 2150 m.* 880 m.

Until 1889 in the Iletsk rock salt field an open-cut mining was practised. From 1889 till 1926 salt was mined underground in the “Old Chamber” 140 meters deep below the surface. Since that time 60 million poods (960 thousand tons) of salt was mined. Since 1924 deposit extraction of the mine №1 had been conducted until the flooding in 1979. During the exploitation period 12 million tons of salt was mined.

Since 1964 alongside with the active mine №1 deposit extraction of the mine №2 280 meters deep had been started. Since 2004 mining works 330 meters deep had been started with extracted deposits estimated at 20 million tons.

In the postwar years building of a new highly mechanized mine was launched in the field. In December 1964 it was brought into operation and it has been operating up to the present day.

At present mine №2 is operating in the field, the annual capacity of which is equal to 1 250 000 tons a year. Explored balance deposits – 568 406 000 tons of salt.

The Baskunchak deposit

The kettle hole of the Baskunchak lake represents the western and the deepest submerged wing of the inside Baskunchak basin which is situated between the northern and southern cupolas of the Baskunchak salt massif. The formation of the kettle hole has begun in the quaternary period and has been going on up to the present moment.

The present-day deposits in the Baskunchak lake include the upper salt deposit which is the object of common salt mining. It has the shape of a lens pinching out in the direction of lake shores, fills up the whole large area of the Baskunchak kettle hole and lies straightforward on the daylight area. The salt deposit is formed by cemented rock salt crystals. The space between crystals in the deposit is filled up with silt and NaCl brine, the so called intercrystal or bottom brine. The average composition of the brine in g/l: K+Na — 104,6; Са – 7,72; Mg — 12,27; НСО3 — 0,14; SO4 — 0,98; Сl — 204,45. The top of the deposit is an almost perfect horizontal plane.

The formation process of the Baskunchak common salt deposit cannot be considered as completed. Loading of common salt in the lake is still going on. It is due to the continual sagging of the kettle hole, its being drainless, active consumption of ground and surface waters carrying quite a big amount of sodium chloride, hot and dry climate providing excess of evaporation over the atmospheric precipitations, which is one of the main conditions of salt deposition from the lake brines. Continuous emission of sodium chloride into the solid phase determines the surprising possibility of the field to restore the resources upon their completion which in the end characterizes natural resources of common salt as inexhaustible.

The technological stages of salt mining include processes of layer destruction, harvesting the destructed salt, concentration, dehydration, loading and transportation. All processes excluding transportation are combined into one technological straight-line and are performed with the help of a salt-mining harvester fixed on the railway platform with independent source of energy supply.

Salt layer operation by harvester is performed by means of consecutive passes. After passes are made a trench (breach) is formed, filled up with brine. In order to decrease losses of destructed salt and to provide normal conditions for absorption of salt pulp between the trenches blocks 0.15-0.20 m. wide are left.

After the extraction of salt in one trench on the full depth they pass to the next trench. For this purpose the railways are moved one step forward which corresponds to the width of the harvester pass and the block between the trenches.

Field location

 

The Usolie deposit

The Usolie rock salt deposit (the eastern part) which is a part of the vast Angara-Lena river basin, covers the territory of the present-day river basins of the upper and middle current of the river Angara, heads of the rivers Lena and Nizhnyaya Tunguska.
In geological structure the Usolie deposit consists of lower cambrian, jurassic and quaternary deposits represented by Usolskaya, Belskaya Budayskaya and Angarskaya suites. Usolskaya suite is the main object of mining in CDPS Usolie and represents rock salt layers, the capacity of which ranges from 11,5 m. up to 84,8 m. The salt layers are located in Usolskaya suite in the interval of 880-1400 m.
The history of salt mining technology development in Usolie mine field covers more than three hundred years. Thus, in 1669 salt production mines were launched in Eastern Siberia by Onisim Mikhalev. Up to the end of the 17th century the salt-producing plant was run by a few different owners, it was owned either by merchants, or dukes, or a monastery.
The cost of the final product was in those years very high, the productivity of salt furnaces was extremely low. Brines had low salt concentration, about 9-12%. It was extracted from the first drill hole 190 meters deep. Until 1862 salt had been produced in 8 black furnaces located in chaotic order, unless the workers’ labor was considered by the chief of the plant Tarasov as harmful and “unfavorable for health”.
The way to improvement of expensive and difficult technologies of evaporated salt production was very long and thorny. Specialists went on duty trips to Eastern Siberia, to the Usolie deposit in order “to establish more optimal ways of salt production”. Thus, in 1875 in order to investigate the state of affairs in the Usolie salt production plant the Finance Ministry sends the mining engineer L. Pershke who gave numerous efficient suggestions for technology improvement. It was him who expressed the idea of brine concentration to the full degree in coolers, which was brought into operation in 1910. As a result the salt concentration there reached 15-18%.
The first drill hole which gave rich brine was drilled in 1924, its depth was 692 meters. However, even it broke only the upper salt layer.
At present brine production is conducted in the eastern part of Usolie field, which is situated on the left bank of the Angara River, close to the town Usolie-Sibirskoe, the Irkutsk region, bordering on the town from the North West.
At present the deposits of the field are equal to more than 4 billion tons of salt, it is one of the largest in the country.