How gypsum is mined. What is gypsum and where is it mined
The scale of the mine and chambers is amazing. Discovered in 1929, the Novomoskovsk gypsum deposit is considered the largest in Europe, and according to some estimates, in the world. When asked whether it is possible to compare the volume of mine workings with the volume of the Moscow metro, the company's employees smile: the scale of these underground facilities is simply not comparable.
Our journey with Ilya Varlamov
begins with an inconspicuous entrance to the shaft with a cage.
2. Before the descent, we were given a protective suit, helmet and boots. As it turned out, not in vain)
3. Also, everyone received an individual lamp and the so-called "self-rescuer" - an oxygen device that must be used in an emergency.
4. Descent 130 meters underground. The mined rock, gypsum stone, is an 11-meter layer at this depth.
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7. In total, there are five shafts in the mine. They serve to lower people and equipment into the mine, ventilation, and lifting of the extracted raw materials. Some of them are not in use today.
8. The first barrel was built in 1947. Rock transportation in those years was carried out only by trolleys. The next stage of evolution is diesel transport. Now dump trucks drive through the mine, and the extracted raw materials are fed up by a special conveyor, in the belt of which "ladles" are arranged. The rails now carry only explosives to the underground warehouse.
9. The total length of underground tunnels is over 500 km! It's like from Moscow to the border with Ukraine. You can't do without an underground car park.
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11. Each chamber exceeds the volume of the Moscow metro station by two to three times. If we compare the volume of mine workings with the metro, then only with all the metros of the CIS, taken together.
12. The main highways are illuminated.
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14. Due to the strength of the extracted rock, there is no need to lay tubing in the mines or somehow strengthen the arches of the tunnels.
15. The whole technological process looks like this:
– bottomhole drilling with special drilling rigs,
- loading drilled holes with explosives,
- blasting faces,
- ventilation after blasting,
– loading of gypsum stone into dump trucks and delivery to the crushing complex,
- splitting up,
- lifting crushed stone to the surface,
– loading products into railway cars, or delivery to production using a complex of conveyor galleries.
16. Gypsum stone is quite durable and cannot be mined with conventional excavation equipment. To do this, wells are drilled in the face and loaded with explosives, which are produced directly at the enterprise.
17. Six large holes are drilled in the center of the chamber, which are not charged, but create a compensation surface that facilitates the work of the explosion.
18. In 2000, the manual labor of drillers was completely eliminated.
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22. Face drilling is carried out with a special drilling rig Smaq BW 50.
23. Remote control of the installation.
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31. Drilling vertical holes.
32. After the explosion, dust settles in the mine workings, the explosives will check for the presence of unworked charges, and after that the loading of the gypsum stone into dump trucks begins.
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Read about the work of dump trucks, crushing complex and underground conveyors in the second part of the story tomorrow.
Taken from chistoprudov to the Underworld. Part 1
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Sulfate class, CaSO 4 .2H 2 O. In its pure form it contains 32.56% CaO, 46.51% SO 3 and 20.93% H 2 O. Mechanical impurities are mainly in the form of organic and clay substances, sulfides, etc. Crystallizes in monoclinic. The crystal structure is based on double layers of anionic groups (SO 4) 2- bound by Ca 2+ cations. The crystals are tabular or prismatic, form twins, the so-called dovetail. very perfect. Aggregates: granular, foliose, powdery, concretions, fibrous veinlets, radial-acicular. Pure gypsum is colorless and transparent, in the presence of impurities it has a gray, yellowish, pinkish, brown to black color. Glass luster. 1.5-2. 2300 kg / m 3. Let's noticeably dissolve in (2,05 g/l at 20 °C). Mainly chemogenic in origin. It precipitates at t 63.5°C, and in solutions saturated with NaCl, at a temperature of 30°C. With a significant increase in salinity in drying sea lagoons and salt lakes, anhydrous calcium sulfate begins to precipitate instead of gypsum - anhydrite similarly occurs when gypsum is dehydrated. Also known is hydrothermal gypsum, which is formed in low-temperature sulfide deposits. Varieties: - translucent fibrous aggregates, cast in reflected light with a beautiful silky sheen; gypsum spar - lamellar gypsum in the form of transparent crystals of a layered structure, etc.
The use of gypsum
Gypsum is used in raw and burnt form. 50-52% of gypsum stone mined is used to produce gypsum binders for various purposes (GOST 195-79), obtained by roasting natural gypsum, 44% of gypsum is used in the production of Portland cement, where gypsum is used as an additive (3-5%) to regulate the timing cement setting, as well as for the production of special cements: gypsum-aluminous expanding cement, stressing cement, etc. Agriculture consumes 2.5% of gypsum in the production of nitrogen fertilizers (ammonium sulfate) and for gypsuming saline soils; in non-ferrous metallurgy, gypsum is used as a flux, mainly in smelting; in paper production - as a filler, mainly in the highest grades of writing papers. In some countries (, etc.), gypsum is used for the production of sulfuric acid and cement. The ability of gypsum to be easily processed, well tolerated by polishing, and usually high decorative properties make it possible to use it as an imitator in the production of facing slabs for interior decoration of buildings and as a material for various handicrafts.
In the southern regions of the USSR, clay-gypsum with a CaSO 4 .2H 2 O content of 40 to 90% is used in the national economy. Loose rock, consisting of gypsum, and is called earthy gypsum, and in Transcaucasia and Central Asia - "gazha" or "ganch". These rocks in their raw form are used for gypsuming of soils, in burned form - for plastering, as an astringent.
Gypsum deposit
In the USSR, the largest deposits are located in the Tula, Kuibyshev, Perm regions of the RSFSR, in the Caucasus and in Central Asia. At 150 deposits of gypsum and 22 deposits of clay-gypsum, drywall and ganch, reserves of 4.2 billion tons have been explored by industrial categories (1981). There are 11 deposits, the reserves of gypsum in which exceed 50 million tons (including Novomoskovsk - 857.4 million tons).
Gypsum is developed by quarries (Shedoksky, Saurieshsky combines, etc.) and mines ("Novomoskovsky", "Artyomovsky", "Kamskoe Ustye", etc.). In the USSR, 42 deposits of gypsum and anhydrite and 6 deposits of gypsum-bearing rocks are exploited with an annual production of about 14 million tons (1981), of which 60.2% are in the territory
Depending on the natural mining and geological factors, the production and extraction of gypsum is carried out by an underground or open pit method.
The production of gypsum, or rather the process of processing natural rocks to a gypsum material that meets the technical parameters, is carried out by qualified personnel at special enterprises. As a rule, industrial facilities are built in the area of gypsum deposits.
Open pit mining and production of gypsum
The open-pit mining method is characterized by high labor productivity, which, against the background of minimizing the loss of gypsum raw materials, is an indisputable advantage of the process. The technological focus of production is based on the extraction, transportation and grinding of gypsum stone.
Gypsum production technology is provided by work in several stages:
- Crushing of gypsum rocks. To date, at this stage of work, the explosive method is used.
- Grinding It is achieved by grinding gypsum to the required consistency, which contributes to the convenient use of the material in the future.
- Drying and roasting. The final stage of production associated with the heat treatment of the material.
Open-pit mining of material is carried out with the help of continuous mining miners, which crush gypsum with a rotating cutting drum. The mechanism of the device consists of segments fixed with bolts and holders with built-in cutters, which are equipped with durable hard alloy inserts.
The supply of the mined gypsum stone to the combine with the subsequent transportation of the material to the primary conveyor is provided by segments arranged in the form of an auger. The size of the loaded pieces of rock, the size of which should not exceed 300 mm, is adjusted due to the design features of the drum of surface miners.
The operation of the mechanism is based on the principle of a free arrangement of segments, coupled with a different configuration and size of the teeth. The leader among manufacturers is the German engineering concern Wirtgen.
The dimensions of the gypsum stone after the first stage of crushing are 30-50 mm. Subsequently, the material is crushed to the state of cereals. It should be noted that recently hammer crushers have been widely used, thanks to which the process of grinding gypsum is carried out in one stage.
The next stage in the production of gypsum is the transformation of gypsum gravel into powder, which takes place in roller-pendulum mills. Due to the impossibility of processing wet gypsum, drying of the material occurs at this stage. The adjustable speed of the gas flow from the flue boilers makes it possible to grind gypsum with high precision. At the same time, an increase in the flow rate makes the material coarser and vice versa. Gypsum is subjected to heat treatment for 1-3 hours at a temperature of 130-160 °C.
Underground mining and production of gypsum
Despite the fact that open-pit mining is carried out at most gypsum deposits, more than half of the total amount of material obtained is provided by enterprises whose activities are based on the underground mining method.
The technology of the underground method in the extraction and production of gypsum is based on the extraction of minerals from the rock formation by autonomous chambers with the maintenance of the roof. Cleaning activities are provided by core drills, scraper winches, deep hole drilling machines, dump trucks and self-propelled trolleys. Excavated cavities are used to store various materials.
As a rule, a useful layer of gypsum deposits is a heterogeneous and heterogeneous layer, often containing various impurities of clay, sand or carbonate rocks. Therefore, during processing, it is necessary to enrich the material. The method is a variant of selective grinding, which is based on different degrees of crushing of strong and weak components.
The most efficient selective grinding process occurs in impact mills and crushers. The advantage of this method is to ensure the maximum difference between the energy costs for crushing weak mineral components and strong crushed materials. The main parameter of the selective crushing process is the speed of the working rotor of the crusher or mill.
Raw gypsum is loaded into the boiler using a screw conveyor. Water vapor is discharged through special pipes. As a result of grinding and drying, gypsum enters the bunker. The final and ready-to-use material is a binder that is used as a component in.
An important factor in the production of gypsum is the installation of a multi-stage cleaning system. This is a mandatory requirement for any plant whose personnel work in conditions harmful to the lungs of dust emitted during the processing of the material.
The photo below shows a gypsum adit near Moscow. The volume of production is so great that all the tunnels of the adit are several times larger than the Moscow metro.
Gypsum- mineral, aqueous calcium sulfate. The fibrous variety of gypsum is called selenite, and the granular variety is called alabaster. One of the most common minerals; the term is also used to refer to the rocks he composed. Gypsum is also commonly called a building material obtained by partial dehydration and grinding of the mineral. The name comes from the Greek. gypsos, which in ancient times meant both gypsum itself and chalk. A dense, snow-white, cream, or pink, fine-grained variety of gypsum is known as alabaster.
See also:
STRUCTURE
The chemical composition is Ca × 2H 2 O. The syngony is monoclinic. The crystal structure is layered; two sheets of 2- anionic groups closely associated with Ca 2+ ions form double layers oriented along the (010) plane. Molecules of H 2 O occupy places between these double layers. This easily explains the very perfect cleavage characteristic of gypsum. Each calcium ion is surrounded by six oxygen ions belonging to the SO 4 groups and two water molecules. Each water molecule binds a Ca ion to one oxygen ion in the same double layer and to another oxygen ion in the adjacent layer. PROPERTIES
The color is very different, but usually white, gray, yellow, pink, etc. Pure transparent crystals are colorless. Impurities can be dyed in different colors. The dash color is white. The luster of the crystals is glassy, sometimes with a mother-of-pearl tint due to microcracks of perfect cleavage; selenite is silky. Hardness 2 (standard on the Mohs scale). Cleavage is very perfect in one direction. Thin crystals and cleavage plates are flexible. Density 2.31 - 2.33 g / cm 3.
It has significant solubility in water. A remarkable feature of gypsum is the fact that its solubility reaches a maximum at 37-38°C with increasing temperature, and then drops rather quickly. The greatest decrease in solubility is established at temperatures above 107 ° due to the formation of a "hemihydrate" - CaSO 4 × 1 / 2H 2 O.
At 107°C, it partially loses water, turning into a white powder of alabaster, (2CaSO 4 × H 2 O), which is noticeably soluble in water. Due to the smaller number of hydrate molecules, alabaster does not shrink during polymerization (increases in volume by approx. 1%). Under p. tr. loses water, splits and fuses into white enamel. On charcoal in a reducing flame it gives CaS. It dissolves much better in water acidified with H 2 SO 4 than in pure water. However, at a concentration of H 2 SO 4 over 75 g/l. solubility drops sharply. Very slightly soluble in HCl.
MORPHOLOGY
Due to the predominant development of (010) faces, crystals have a tabular, rarely columnar, or prismatic appearance. Of the prisms, (110) and (111) are the most common, sometimes (120) and others. Faces (110) and (010) often have vertical shading. Intergrowth twins are frequent and are of two types: 1) Gallic according to (100) and 2) Parisian according to (101). It is not always easy to tell them apart. Both of them resemble a dovetail. Gallic twins are characterized by the fact that the edges of the prism m (110) are parallel to the twin plane, and the edges of the prism l (111) form a reentrant angle, while in the Parisian twins the edges of the prism Ι (111) are parallel to the twin seam. It occurs in the form of colorless or white crystals and their intergrowths, sometimes colored by inclusions and impurities captured by them during growth in brown, blue, yellow or red tones. Intergrowths in the form of a “rose” and twins are characteristic - the so-called. "dovetails"). It forms veinlets of a parallel fibrous structure (selenite) in clayey sedimentary rocks, as well as dense continuous fine-grained aggregates resembling marble (alabaster). Sometimes in the form of earthy aggregates and cryptocrystalline masses. It also forms the cement of sandstones.
Common are pseudomorphs after gypsum of calcite, aragonite, malachite, quartz, etc., as well as pseudomorphs of gypsum after other minerals.
ORIGIN
A widely distributed mineral, it is formed in natural conditions in various ways. Sedimentary origin (typical marine chemogenic sediment), low-temperature hydrothermal, found in karst caves and solfataras. It precipitates from sulfate-rich aqueous solutions during the drying of sea lagoons and salt lakes. Forms layers, layers and lenses among sedimentary rocks, often in association with anhydrite, halite, celestite, native sulfur, sometimes with bitumen and oil. In significant masses, it is deposited by sedimentation in lacustrine and marine salt-bearing dying basins. In this case, gypsum, along with NaCl, can be released only in the initial stages of evaporation, when the concentration of other dissolved salts is not yet high. Upon reaching a certain value of the concentration of salts, in particular NaCl and especially MgCl 2, anhydrite will crystallize instead of gypsum and then other, more soluble salts, i.e. the gypsum in these basins must belong to the earlier chemical sediments. Indeed, in many salt deposits, layers of gypsum (as well as anhydrite), interbedded with layers of rock salt, are located in the lower parts of the deposits and in some cases are underlain only by chemically precipitated limestones.
In Russia, thick gypsum-bearing strata of Permian age are distributed in the Western Urals, in Bashkiria and Tatarstan, in Arkhangelsk, Vologda, Gorky and other regions. Numerous deposits of the Upper Jurassic age are established in the North. Caucasus, Dagestan. Remarkable collection specimens with gypsum crystals are known from the Gaurdak deposit (Turkmenistan) and other deposits in Central Asia (in Tajikistan and Uzbekistan), in the Middle Volga region, in the Jurassic clays of the Kaluga region. In the thermal caves of Naica Mine, (Mexico), druze of gypsum crystals of unique size up to 11 m long were found.
APPLICATION
Today, the mineral "gypsum" is the main raw material for the production of α-gypsum and β-gypsum. β-gypsum (CaSO 4 0.5H 2 O) is a powdered binder material obtained by heat treatment of natural two-water gypsum CaSO 4 2H 2 O at a temperature of 150-180 degrees in apparatus communicating with the atmosphere. The product of grinding β-modification gypsum into a fine powder is called building gypsum or alabaster, with finer grinding, molding gypsum is obtained or, when raw materials of increased purity are used, medical gypsum. During low-temperature (95-100 °C) heat treatment in hermetically sealed apparatus, α-modification gypsum is formed, the grinding product of which is called high-strength gypsum.
In a mixture with water, α and β-gypsum hardens, turning back into dihydrate gypsum, with heat release and a slight increase in volume (approximately 1%), however, such a secondary gypsum stone already has a uniform fine-crystalline structure, the color of various shades of white (depending on raw materials), opaque and microporous. These properties of gypsum are used in various fields of human activity.
Gypsum (English Gypsum) - CaSO 4 * 2H 2 O
CLASSIFICATION
| Strunz (8th Edition) | 6/C.22-20 |
| Nickel-Strunz (10th edition) | 7.CD.40 |
| Dana (7th edition) | 29.6.3.1 |
| Dana (8th edition) | 29.6.3.1 |
| Hey's CIM Ref. | 25.4.3 |
PHYSICAL PROPERTIES
| Mineral color | colorless turning into white, often colored by minerals-impurities in yellow, pink, red, brown, etc.; sometimes there is a sectorial-zonal color or distribution of inclusions over growth zones inside the crystals; colorless in internal reflexes and through. |
| Dash color | white |
| Transparency | transparent, translucent, opaque |
| Shine | glassy, close to glassy, silky, pearlescent, dull |
| Cleavage | very perfect, easily obtained from (010), almost mica-like in some samples; according to (100) clear, turning into conchoidal fracture; by (011), gives a splintery fracture (001) |
| Hardness (Mohs scale) | 2 |
| kink | smooth, conchoidal |
| Strength | flexible |
| Density (measured) | 2.312 - 2.322 g / cm 3 |
| Radioactivity (GRapi) | 0 |
price
practicality
appearance
ease of manufacture
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environmental friendliness
final grade
It is a sedimentary mineral found in nature in the form of layers of sedimentary rock. These are crystals of white, transparent color, having various shades from yellowish to red. A mineral is formed due to the evaporation of water saturated with calcium.
Today, gypsum is widely known as a building material used for finishing and plastering. It is also used in architecture and landscape design.
Mining what gypsum is made of
Gypsum is mined in deposits by undermining gypsum-containing rock. Further, the ore is transported to the factories in the form of gypsum stones. They are crushed in special crushers, and then dried to evaporate the moisture present in them.
Dry fractions are crushed in mills to a state of powder and sent to a kiln for roasting. The powder is fired for 1-2 hours at a temperature of 150-160 degrees. The output is a finely dispersed mixture of white color, completely ready for use.
Place of Birth
Gypsum is distributed throughout Russia. The main places of gypsum production are the Vladimir, Arkhangelsk and Irkutsk regions, Central Asia, the Volga region, Bashkiria and the Western Urals. Other countries include Spain, Tunisia, Greece and Morocco.
Gypsum deposits arise due to the following factors:
- Weathering of salt deposits.
- In places of salt lakes, it is formed in the form of a chemical precipitate.
- It is a companion rock in old deposits of oil, sulfur and anhydrites.
- Often, mineral deposits are found at the mouths of ancient rivers.
On the video - how gypsum is mined and processed at the Foreman plant:
Compound
According to its chemical composition, it is an aqueous solution of calcium sulfate. Its chemical formula is Ca? 2H2O. When heated to 140 degrees, water is released from its crystal lattice, resulting in the formation of the so-called semi-aqueous gypsum.
If you continue heating the mineral, then building (baked) gypsum is formed. This material is used in powder form. If water is again added to such a powder, then the water will join the calcium sulfate, and the material will become hard.
sump
To separate gypsum and sand from the water mixture, special devices called gypsum settlers are used. They allow you to collect gypsum and sand in a separate container, and send water to the drain system. The sump must be connected between the sink and the drain pipe.
Plaster additives
Since gypsum consists of a rather fragile substance - calcium, various substances and impurities are added to it to improve the quality of the resulting material.
Impregnation
Gypsum surfaces are porous, so they require impregnation with special compounds. The pores are filled, and after drying, the surface is considered ready for further painting. As an impregnation, natural drying oil is usually used.
If it is not there, then you can use a solution of liquid glass or PVA glue. After applying the composition, it is necessary to wait for it to dry completely, and only then proceed to painting the surface.
plasticizer
With the help of additives such as plasticizers, it is possible to change and also control the degree of its fluidity. In addition, some types of plasticizers are capable of imparting additional strength to finished gypsum products. In general, there is an increase in the rate of production of gypsum products, more efficient and rational use of equipment.
Water repellent
Water-repellent compositions intended for introduction into gypsum mortars serve to reduce the water absorption of gypsum while maintaining its vapor permeability. This avoids the appearance of condensation on the surface of the gypsum, even when a sharp temperature difference occurs.
In addition, such additives increase the strength of the hardened product or gypsum surface and protect it from the formation of mold and fungi. The water repellent penetrates into the pores of the gypsum and begins to act immediately after drying.
The principle of operation of the water repellent
varnish
Lacquers are used to finish finished gypsum surfaces. The fact is that it is necessary to reduce the absorbency of gypsum, that is, to close its pores. To do this, it is recommended to impregnate the surface with drying oil or varnish. It is better to use water-soluble varnishes based on acrylic or resin.
Such a composition penetrates deep into the pores of gypsum, and on its surface forms a thin and durable film with good adhesion. Such a surface will be reliably protected from moisture. For example, there are several varieties of gypsum varnish: Izoplen, Dulux Trade Acrylic, Izo Sol.
Glue
Some types of glue are used as additives in gypsum mortars. This not only increases the strength of finished products, but also increases their water resistance. Most types of glue contribute to a slower setting of the solution. PVA glue, bone glue, wallpaper paste (CMC) and other types of adhesives are usually used.
Paint (pigment)
In order to give unusual colors, powdered iron oxide pigments are used. They are available in powder form in various colors. Pigments do not dissolve in water, organic solvents and other liquid media, so colored gypsum will not lose its color over time.
Such pigments do not fade in the sun and do not change their color. Pigment powder is mixed with dry gypsum and evenly distributed throughout its volume.
Retarder
Gypsum tends to set very quickly, so it is recommended to use retarders that can increase the pot life of the gypsum mortar. The amount of such an additive depends on its type. As additives, sodium tartrates are used, which are salts of tartaric acid, as well as sodium citrates (salts of citric acid).
In practice, it is more profitable to add ordinary citric acid to the solution water. In addition, PVA glue, liquid glass, animal glue, Dextrin, or ready-made dry mixes are also used as moderators.
Modifier
Polymer additives introduced into the gypsum solution are able to modify it, creating gypsum polymer composites. Depending on the amount of modifier introduced, the properties of the hardened product change.
With a minimum amount of them, strength increases and resistance to destruction in the open air increases. If you introduce a lot of modifier, then the product will acquire water resistance, frost resistance, and also its wear resistance will increase.
Usually modifiers are produced in the form of a dry white powder. To use the modifier, it is necessary to dissolve the powder in water, which will be used to mix the gypsum.
How modifiers act on the strength properties of gypsum mortars
How to dissolve gypsum
Dry gypsum mix is dissolved with ordinary water. The higher the temperature of the water, the faster the reaction of the transition from a liquid solution to a solid state. After hardening, gypsum does not dissolve with water.
However, if you store a hardened gypsum product or just a piece of hardened gypsum in high humidity conditions, then gradually the strength of the gypsum decreases, and the gypsum becomes brittle. For reuse, the hardened gypsum is calcined in an oven to remove excess moisture, and then ground into powder.
How to increase strength and make it stronger
To increase the strength of gypsum surfaces or products, it is recommended to introduce special additives into the solution. These are polymer fiber, various types of glue (CMC, PVA, bone glue), fluff lime, borax, liquid glass. Excellent results are obtained by reinforcing gypsum surfaces with a polymer mounting mesh.
To give a gypsum product strength comparable to that of ceramics, it is immersed for a day in a saturated solution of potassium alum. Then the product must be heated to a temperature of 550 degrees. You will be surprised by its durability.
How to make plaster at home
Gypsum is widely used in everyday life for the manufacture of various products. To prepare it at home, you need to prepare dry gypsum powder, water and dishes for stirring the composition. Water is poured into the dishes, and then the dry mixture is slowly poured into it, constantly stirring the solution.
Everything must be done carefully, but quickly, since the gypsum can harden before anything is made from it. The entire cooking process should take no more than 2 minutes. It is recommended to use cold water.
The concentration of the solution should be as thick as liquid sour cream. If the solution is too thin, then add a little more dry mixture. But be careful, since it is impossible to add water to dilute an excessively dry solution.
The resulting mixture must be used as soon as possible. If the solution has hardened, then it is already unacceptable to use it. Therefore, work with small portions of the gypsum mixture.
The video will tell you what is used as a plasticizer for gypsum when creating products from it with your own hands:
How much does this building material cost on average?
The cost of dry gypsum powder is quite affordable for the population. It depends on the packaging of the powder, the manufacturer and the cost of transport delivery to your region. The average price of 1 kilogram of building gypsum is from 50 to 90 rubles. Medical plaster is more expensive. Its cost can reach up to 150 rubles per kilogram.
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