Where is basalt used? Basalt stone: properties of this rock with a photo

Foreword

Basalt is an igneous rock formed as a result of a volcanic eruption.

Basalt is an igneous rock formed as a result of a volcanic eruption. Being a widespread rock, basalt lines almost the entire surface of the ocean floor. It is formed as a result of melting of the upper mantle, and in its structure strongly resembles it chemical composition. It is mainly composed of silica, iron and magnesium. The origin of basalt can be somewhat different in nature and includes three different types - these are volcanoes located on the hot spots of tectonic plates, igneous basalt flows and underwater oceanic ridges.

Hot spots of tectonic plates are the progenitors of large basalt volcanoes. A hotspot is an unusual upwelling of deep mantle flows - plumes, usually at the center of tectonic plates. These hotspots form the largest naturally occurring volcanoes called shield volcanoes. The Hawaiian and Galapagos Islands are a striking example of island archipelagos formed as a result of the activity of large basalt volcanoes. Shield volcanoes rise above other volcanoes, significantly exceeding them in height and width.

In fact, one of the Hawaiian volcanoes, called Mauna Key, is the highest mountain in the world, considering its length from the base to the top, while Everest can be called the highest mountain in the world. The largest volcano in solar system is considered to be a basalt shield volcano called Olympus Mons, located on the planet Mars.

Another source of origin for basalt is extensive lava flows. Basalt lava is not particularly viscous, so it flows easily and quickly, spreading over long distances and forming a large amount of basalt rock. Some of these magmatic eruptions cover vast areas of the earth's surface, and even today, there is still a possibility that eruptions of this magnitude could happen again. Basaltic lava flows covered more than one and a half million square kilometers of Siberia, the so-called Siberian traps.

The Columbia River Basalt Group is another powerful basalt flow that has produced basalt cliffs that are over 1,800 meters wide. Mara (black areas) on the moon are formed from basalt, and basalt flows are a possible source of their origin. According to scientists, powerful basalt flows are also involved in the formation of the surface of Mars.

Melting basalt rocks

Some people mistakenly believe that basalt is a sedimentary rock, which is absolutely wrong, since the mechanism for the formation of basalt is fundamentally different from the nature of the formation of sedimentary rocks.

Who cares - the origin of basalt in the video:

Basalt is the most common igneous rock natural mineral, it turns out from volcanic rocks, after an eruption occurs, its temperature can reach several 1000 ° C.

The stone is quickly recognizable, as it can be dark, black, gray-black, smoky. Most often it has the following appearance: a dark heavy mass, where small light feldspar rectangles and bottle-green eyes of olivine are visible. The mineral is very hard, has a high density equal to 2530-2970 kg / m2, a high melting point, varying in the range of 1100-1250 ° C,

Under natural conditions, the stone can be seen in the form of flows emanating from an avalanche that appears during the eruption through the existing volcanic cracks. There are several types of this stone: some contain olivine, others do not - they are called tholeiite containing particles of quartz in their composition. Stones with the presence of olivine can be found on the Pacific islands.

Mineral deposits have been discovered in India and America. Many stones are found in the Italian volcanoes Vesuvius and Etna. Today the stone is mined in Kamchatka, in Ireland, Scotland and Iceland. In Ukraine, you can also find their traces.

Basalt - properties and its wide application

The composition of the stone contains: volcanic glasses, microlites, titanomagnetite, magnetites and also clinopyroxene. The mineral has a porous, glassy and latent crystalline aphyric structure.

The properties it has basalt, characterize it as the most reliable and protective element for facing works. The stone has the following properties:

• fire resistance;
• strength;
• durability;
• soundproofing;
• thermal insulation;
• ecological purity.

It contains augite, calcium feldspar and its varieties. Sometimes an admixture of olivine is found.

Thanks to the mineral, high-quality additives to gravel, strong fibers are made, from which heat-insulating and sound-proofing materials are made. Mainly used to create high-quality plates.

Widely used stone in the construction field in the form facing materials, with its help sculptures and various statues are made, and it is also used for the exterior decoration of most buildings. The stone has an unusual property, able to withstand both high and low temperature indicators, and therefore it has a wide application in the street.

Cladding made from this stone, creates a beautiful appearance of any building. It will remain the same for many years as it was the day it was installed. Its service life spans many decades. It is easy to install, no ties or other reinforcements are needed for this. The stone itself has excellent characteristics that allow you to enjoy the environmental friendliness and durability of the material used and the masterpieces created with it.

Of the large number of slabs available, the most common are slabs containing basalt. They have high strength and lend themselves well to cutting and sawing. They build the most complex and serious structures. These plates are environmentally friendly and do not exert a large load on the foundation.

Plates of this mineral are effectively engaged in the regulation and absorption high level noise in residential buildings and other public places.

The mineral has a wide range of useful properties that can not only improve the appearance, but also prevent adverse consequences after construction has been completed and further operation has begun. The properties of noise and sound insulation make it possible to provide good living conditions in residential buildings.

The rock of this mineral has a high fire resistance, can withstand temperatures above 1500 degrees Celsius and is used in the form of fire protection. Minerals can withstand the action of alkalis, acids, paints, have high resistance to abrasion. Serves as an indispensable natural filler for creating concrete blocks.

The main criterion is still environmental friendliness. this mineral. In molten form, the mineral is used to create steps, stairs, tiles and other building materials. Stone powders are used for the manufacture of reinforced and pressed products.

The black color of the mineral interacts remarkably with silver. They make unusual jewelry which are a great addition to evening wear. Light shades of stone are used to make luxurious bracelets, beads, belts, necklaces, as well as various sets.

Basalt - the main origin and process of change

Basalt It is obtained as a result of the melting of rocks, such as: lherzolites, harzburgites, wehrlites. The main composition is determined by the chemical and mineral compounds that contain the protolith and retain the degree of its melting.

There are the following types of minerals:

• oceanic ridges;
• continental;
• intraplate.

This type of stone is easily changed as a result of hydrothermal processes. Especially visible are the changes in the stones that pour out at the bottom of the seas and oceans. They vigorously combine with water, while many useful components stand out and settle from them.

In the process of metamorphism, stones can turn into green schists, it all depends on the conditions. And if pressure is applied to them, they can generally acquire a bluish color.

It is traditionally believed that the word "basalt" comes from the Greek "basis" ("base"). "basal" in modern understanding means "lower". Therefore, basalt is the base rock; the stone upon which all things rest...

Another version is also interesting. In one of the African dialects, the word "basal" means "boiling". Basalt, according to the Ethiopians, is a mineral that first boiled in the mouth of a volcano, and only then poured onto the surface of the Earth.

The version, in general, is not too far from the truth. Basalt stone shows the properties of volcanic rock as often as the qualities of the base material of continental plates. It is widely distributed on the planet, but is found mostly in places of noticeable volcanic activity.

Basalt deposits

Beautiful young basalts are easily found in the vicinity of the Kamchatka and Kuril volcanoes. Black and black with green rocks of Vesuvius and Etna are extremely good. Dark gray, almost black basalt erupts in Hawaii.
There are many different basalts in India too: the Hindustan tectonic plate, crashing (and continuing to crash deeper and deeper) into the Eurasian plate, like a bulldozer knife, raked sedimentary deposits into a pile (Himalayan mountains) and twisted out the layers of the lower, basal rock.

Australian basalts are valued by scientists: on this continent (and one more cliff in Canada), basalt monoliths have been preserved that “saw” our planet as hot and not yet very round.

The decorative properties of basalt of West African origin are considered the most outstanding. Mauritanian varieties of stone are famous for their dark green background and original color blotches. And although such basalt is somewhat less frost-resistant than its smooth-colored counterparts, the demand for it as a building material has not decreased for several centuries.

The smoky shade of gray basalt from China is called "twilight". It is used both for finishing works and for paving roads, construction of various structures. Chinese and Siberian basalts are recognized as the most durable and resistant to destructive atmospheric influences.

Basalt - weathered?

Basalt and granite are the most durable of stones, but they are also powerless before prolonged weathering. The complex chemical composition of basalt is "responsive" to changes in the acidity of sediments.
The absorption of moisture - the more powerful, the more gases were released during the eruption of volcanic basalt - leads to the destruction of the strongest rock by ice crystals.

Basalt is exposed to abrasive wear. The streams of water and the wind carrying the sand gradually wear down the outer layers of the rock. However, for the complete destruction of some basalts, it takes more time than our planet exists.

Bubbly basalt - hardened lava foam

To foam such a heavy rock (the density of basalt sometimes exceeds 3.3 grams per cubic centimeter), it is necessary to pre-saturate the molten stone with vapors and gases. Not all areas of pronounced volcanic activity can "boast" of a similar composition of erupted basalts.

However, where gas-saturated basalts hit the Earth's surface, mineralogists and gemologists find crystalline geodes and colored layers in cavities. In most cases, almond-stone basalt (this is the name of the rock similar to Swiss cheese) gives the seekers the most beautiful agates, crystallized, geologically interesting compounds of calcium and copper.

Application of basalt

Basalt stone melts when heated to a temperature of 1250˚С, and when molten, it is easy to mold. Cast basalt products are popular with both builders and decorators. But basalt wool is in the greatest demand. Assembled in mats, it is reliable, durable, resistant to external influences heat-insulating and sound-absorbing material.

Basalt crumb is not only a bulk additive to asphalt and concrete. The dielectric properties of basalt make it possible to use the crushed mineral as a backfill for high-voltage converters.

The high resistance of basalt to aggressive environments makes it possible to manufacture chemical production apparatuses and acid-resistant powders from natural stone.

The aesthetic properties of basalt make it possible to create small and large-scale sculptural groups, interior and jewelry from a strict and solemn stone. The use of basalt as an expressive architectural material expands the possibilities of artistic rethinking of space.

Basalt Jewelry

Basalt black goes well with the soft sheen of silver. Jewelry sets made of intricately faceted tropical night-colored basalt are worn as pretentious additions to evening dresses.

Finds its use and light basalt. Beads, bracelets, necklaces and belts made of polished basalt figurines make amazing sets.

Basalt pillars - natural curiosities

The volcanic origin of basalt has led to the formation of curious formations - correctly faceted stone pillars. Basalt magma, frozen in the vent of the volcano, eventually cracks along several vertical planes.

As a result of erosive exposure of the magma shaft, basalt massifs are subjected to intense weathering, which first leads to the appearance of huge "clusters" of stone pillars of a geometrically perfect shape. Even edges can give a basalt monolith the appearance of a four-, five-, six-, and even seven-sided rod of many meters in length.

The history of construction describes cases of using basalt pillars in the construction of capital buildings.

BASALT, a ceramic material with high mechanical, physical, electrical and chemical properties and obtained by thermal processing of rocks of the same name.

1. Basalt as a rock. Basalt, or rather basalts, are among the characteristic igneous (effusive) basic rocks of deep origin and young, predominantly Tertiary, age. Basalt gained its wide popularity for the picturesque fragments it forms in the form of 6-sided (and sometimes 3- or 5-sided) prisms 3-4 m long with planes perpendicular to the faces (Fig. 1); it is also found in the form of limestone natural stairs, shell-shaped spherical parts and other extremely picturesque rocks.

Basalt is a dark-colored rock, sometimes grayish-black, sometimes with a bluish tint; sometimes it is greenish or reddish. The very name "basalt" is of ancient origin and in the Ethiopian language means "dark", "black". This breed is very homogeneous in its fine build. Dense and extremely hard, it has in different occasions grain different order. Coarse- and medium-grained varieties are called dolerites, fine-grained varieties are called anamesites, and very fine-grained varieties are called basalt proper. The difference in texture of basalt with identical bulk composition is explained by the conditions of solidification of igneous magma (cooling rate, pressure, etc.). The petrographic composition of basalt can vary significantly, but the minerals that make up the basalt are replaced by petrographic equivalents, as a result of which basalt as a rock retains its habitus very steadily. Under the microscope, basalt appears as a glassy groundmass (“basis”) with a microfluidic composition. The basis contains numerous crystals of feldspar, olivine, magnetic iron ore and other less typical minerals. Depending on the content of mineral inclusions cemented by the basis, basalts are distinguished: plagioclase, leucite, nepheline and melilite. Actually, it is customary to call the first basalt, that is, those containing calcareous-soda feldspar, augite and olivine. Basalt is chemically related to gabbro (G.) and diabase (D.). The bulk chemical analysis of plateau-forming basalt is characterized, according to Washington, by the following data:

Basalt is inherent in significant radioactivity: it contains from 0.46∙10 -3 to 1.52∙10 -3% of thorium and from 0.77∙10 -10 to 1.69∙10 -10% of radium. Less deep varieties of basalt are more acidic and gradually pass to dacites, trachytes, etc. According to the latest views, basalt is a material that forms a solid shell of the earth: under the continents 31 km thick, and under the oceans - from 6 km or more; this shell floats on a viscous-liquid underlying layer of basalt ("substrate"). Thus, it is assumed that basalt is everywhere. As for the very surface of the earth, the outcrops of this rock are very numerous. Outside the USSR, they are: in the Auvergne, along the banks of the Rhine, in Bohemia, Scotland and Ireland, on the island of Iceland, in the Andes, in the Antilles, on the island of St. Helena and in various other areas. There are many deposits of basalt in the northern, western and southeastern parts of Mongolia. Within the USSR, basalt is distributed in the Caucasus and Transcaucasia, as well as in northern Siberia, in the basin of the river. Vitim. In the near future, the following deposits may practically be of the greatest interest: Berestovetskoye - Volynsk district of the Ukrainian SSR, Isachkovsky - Poltava district of the Ukrainian SSR, Mariupol - Mariupol district of the Ukrainian SSR, Chiaturskoye, Beloklyuchinskoye, Manglisskoye and Saganlugskoye, Adjaris-Tskhalskoye - Georgian SSR, Erivanskoye - Armenian SSR, as well as Olonets diabase from the shores of Lake Onega.

2. Properties of natural basalt. The direct application of natural basalt and its further processing require sufficient knowledge of the mechanical, physical and chemical properties his. However, these properties are significantly related to the composition and texture of basalt and therefore vary significantly depending on the deposit. If we talk about basalt in general, then its properties can be. are characterized only by the limits of the corresponding constants. The data given below for basalt are partly compared with the data for diabase and gabbro. Apparent specific gravity(piece): 2.94-3.19 (B.), 3.00 (D.), 2.79-3.04 (G.). The true specific gravity (powder) is about 3.00 (B.). Porosity in % volume: 0.4-0.5 (B.), 0.2-1.2 (D.), 3.0 (G.). Water absorption: 0.2-0.4% by weight and 0.5-1.1% by volume (B.). The mass of 1 m 3 of dry basalt is about 3 tons. Compressive strength in kg / cm 2: 2000-3500 (B.), 1800-2700 (D.), 1000-1900 (G.). If the compressive strength of dry basalt is more than 3000, then wet basalt is more than 2500, and at a frost of 25 ° it is more than 2300. Wear strength (“hardness”, calculated by the formula: p \u003d 20-w / 3, where w is the mass, lost under normalized conditions at 1000 revolutions of the abrasive disk) is characterized by the numbers 18-19 (B., D., G.). Impact strength (“compactness”) when testing normalized samples: 6-30 (B., D.) and 8-22 (G.). Basalt is harder than steel. Young's modulus in (D cm -2) x10 -11 is 11 (G.) and 9.5 (D.). The volumetric compression ratio per 1 kg at a pressure of 2000 kg / cm 2 is 0.0000018 (B.) and 0.0000012 (D.), and at a pressure of 10000 kg / cm 2 it is 0.0000015 (B.) and 0.0000012 (D.). The beginning of melting of normal olivine basalt is at a temperature of about 1150°, and the liquid-melting state begins at a temperature of about 1200°. Molten rock ceases to be fluid when cooled to 1050°. More acidic rocks have a higher melting point, and it rises with the content of silicic acid. In particular, the basalt of the Adzharis-Tskhali deposit (dacite-basalt - according to Abih or trachyandesite - according to new definitions) softens at 1180°, has the consistency of thick honey at 1260°, and completely liquefies at 1315° (experiments of the author in the Department of Materials Science of the GEEI). The specific heat capacity of Syracuse basalt for various temperatures is shown in the following table:

The heat of crystallization of basalt during the transition from an amorphous state to a crystalline state 130 Cal. During crystallization, the volume decreases by 12% compared with the volume of basalt at a temperature of 1150°. The specific thermal conductivity of basalt in gram-calories is about 0.004. Thermal expansion coefficient of basalt: 0.0000063 (at 20-100°), 0.000009 (at 100-200°) and 0.000012 (at 200-300°).

In chemical terms, basalts are resistant rocks: atmospheric agents, in Gary's experiments, weathered from 1.5 to 0.8 mg / cm 2 of basalt in 18 months, while gray limestone lost 22.7 mg / cm 2 under the same conditions. The process of weathering of basalt and diabase is presented by a comparative diagram (Fig. 2).

The number on the upper horizontal line shows the number of grams of weathered rock that must be taken so that it contains the component corresponding to the designation of the horizontal in question, as much as this part is contained in 100 g of fresh rock. That. all points to the right of the vertical 100 mean depletion of the corresponding part, and those to the left - enrichment. Consequently, during weathering, basalt is enriched in silica and alumina and becomes poorer in alkalis, alkaline earths and iron in all forms, while diabase is enriched in oxide iron and sodium. This circumstance speaks, apparently, against diabase as an insulating material.

3. Bases for processing basalt. The properties of natural basalt make it an excellent building material, more durable than granite. Basalt has been used for a long time. However, the extreme difficulty of processing basalt and dividing it into relatively narrow prisms forced us to come up with a special way of giving it geometric shapes.

It was natural to think about the fusion of this rock, since it itself is of fiery origin. But it is not enough to melt basalt: upon rapid cooling, castings from it give a vitreous mass similar to natural hyalobasalts, fragile and technically inapplicable (Figs. 3 and 4).

The main task of basalt production is the restoration of fine-grainedness in remelted basalt, the so-called regeneration (Fig. 5).

The idea of ​​the possibility of remelting and restoration in original form rocks arose in the 18th century. Already in 1801, the Scot James Goll achieved the remelting of basalt and, in particular, established that basalt and lavas, being melted and quickly cooled, give glass, while when they are slowly cooled, a stony mass is obtained, with traces of a crystalline structure; this is the basic position of the fiery processing of lavas. Particularly remarkable are the experiments of the Scot Gregory Watt, who expanded the scale of smelting. The melting of a block of basalt more than 3 tons lasted 6 hours, and cooling under the cover of slowly burning coal took 8 days. Watt described the products of this slow cooling: black glass on the surface; as they deepen into the frozen mass, grayish balls appear, grouped into bundles; then the structure becomes radiant; even deeper, the substance has a stony and then granular character, and, finally, the mass is penetrated by crystalline plates. That. the possibility of melting and regenerating igneous rocks was found out. But due to the lack of a sufficiently large need for remelted basalt for industry, the described experiments were forgotten. In 1806 Dobré and then in 1878 F. Fouquet and Michel Levy returned to the smelting and regeneration process. They managed to reproduce almost all rocks of fiery origin and found out that this does not require either extreme temperatures or mysterious agents, but the whole point is to establish the proper regime of melting and annealing. After cooling, the molten silicate turns into glass, the melting point of which is lower than the melting point of the original mineral. To restore the latter, it is necessary to anneal the vitreous mass at a temperature exceeding the melting point vitreous body, but lying below the melting point of the crystalline mineral. The temperature range of these melting points is the area in which the regeneration of silicate or aluminosilicate is possible; this interval m. b. pretty insignificant. When it is not a matter of one mineral, but of a combination of 5-6 minerals that make up a crystalline rock, then the annealing regime would have to be set with a number of steps, and each mineral would have its own stoppage of the cooling progress. However, in practice, these steps are so close to each other that we can limit ourselves to two stops. In relation to basalt, the first annealing, with a red-white glow, gives the crystallization of ferrous oxide and peridot, and the second, with cherry-red, crystallization of other minerals of the rock.

The first experiments in the industrial smelting of basalt were undertaken in 1909 by Ribb, and various applications for smelted basalt were found by engineer L. Dren. In 1913, for the industrial implementation of smelting processes, the Compagnie generate du Basalte was formed in Paris, and in Germany - Der Schmelzbasalt A.-G., in Linz on the Rhine; then both societies united under the common name "Schmelzbasalt A.-G.", or "Le Basalte Fondu". Currently in France there are two plants that produce Ch. arr. electrical and building products, and in Germany one serving the chemical industry.

4. Production of melted basalt. Breaking. The occurrence of basalt is different, and therefore its breaking is not always uniform. Slab-like basalt of mantles or rocks is quarried by blasting. Prisms of columnar basalt can be separated by means of wedges and levers. Development is carried out in tiers, removing successive layers in rows of natural bundles.

Splitting up . Broken basalt is stored outdoors. For smelting, it is crushed in Black or Getz crushers. Then the pieces are sorted by size, and the fines go to the concrete masses.

Remelting. Crushed basalt enters the smelting furnaces, which use various methods of heating. The most suitable ovens are electric, gas (gas generating or with lighting gas) and ovens with oil burners. The electrosmelting plant consists of a fixed electrode furnace and a mobile receiver on wheels, which serves to transport the molten basalt to the casting workshop; this receiver also represents a small electrode furnace. Both types of ovens are powered by two-phase current. The bottom of the furnace is made of refractory material and has a nozzle on the side for discharging the molten mass, while from the receiver it descends into molds or molds for casting by simply tilting the receiver. In other furnaces, the throat is made inclined, so that the loading of the hearth and the descent of the molten mass are carried out in a continuous process. The productivity of the described furnaces is from 3 to 50 tons per day. The Paris plant - of a large-scale handicraft type - has 4 furnaces with a capacity of 80 kg each, operating continuously and heated by city gas; melting is carried out at 1350°. Another French plant, in Puy, runs on electricity. Continuous production capacity - 8 tons per day.

Casting. The molten basalt is poured into molds or molds directly from the furnaces or taken to the casting shops. For casting, either sand trusses or steel molds are used. The first ones are much cheaper, but not applicable in all cases, because the products come out of them dull and rough. Steel molds give products a shiny surface, but are relatively expensive. With careful casting, the casting is clean; otherwise, streaks and irregularities are visible, which in many cases do not prevent, however, the use of the product.

Heat treatment. Almost immediately after casting, the products, still cherry-red, are removed from the molds and transferred to annealing hearth furnaces, similar to ordinary hardening ones. Depending on their purpose and size, the products are aged in the oven from several hours to several days. Initial temperature annealing at about 700°. The oven is covered and slowly cooled; languishing in the furnace lasts, depending on the size of the products and their required qualities, from several hours to 10-14 days. There are up to 35 such ovens at the Paris plant.

Finishing . After cooling, the products are ready for use. To give them a proper look, they are cleaned with steel brushes. If greater accuracy of planar faces is required, then finishing is carried out on circles having a basalt base.

production cost. The production of fused basalt does not require highly skilled labor or expensive equipment. The main costs of production in our conditions are for the delivery of material, if it is brought from the Caucasus, and for energy. When working with gas, 1 kg of finished basalt products requires about 900 Cal, i.e., about 1/4 - 1/3 m 3 of gas; when working with electrical energy Approximately 1 kWh is consumed per 1 kg of products. That. the cost of basalt products, for example, insulators, is much lower than porcelain. In France, the selling price of basalt insulators is 10-15% less than porcelain, and for larger ones - 25-30%. The larger the products, the greater the price discrepancy between basalt and porcelain. However, there are reasons to consider the above discrepancies in selling prices to be significantly underestimated due to the increase in the profit of basalt production as a new business.

Production of smelted basalt in the USSR. With enormous technical and economic advantages behind it, and in some cases, as in the electrification of railways, being almost indispensable, the basalt industry attracted the attention of technical and industrial circles. Experiments with the smelting of basalt and other rocks, undertaken on behalf of the Glavelectro VSNKh in the Department of Materials Science of the GEEI and then at the State Electrotechnical Institute, experiments on the smelting of diabase in the Mining and Metallurgical Laboratory and the interest of the Supreme Economic Council of Georgia and Armenia in this industry can be considered harbingers of the rapid development of basalt business. From an economic point of view, b. a very favorable natural combination of favorable factors was noted: the possibility of extracting basalt very often territorially coincides with the availability of sources of hydroelectric energy for its processing, i.e. with a regional power plant, which requires basalt insulators, and with centers of electrochemical production that need fire and acid-resistant basalt equipment. The indicated coincidence, in connection with the profitability of small basalt plants and the comparative high cost of transport, gives reason to foresee in the future a network of small basalt plants throughout the country.

5. Properties of processed basalt. Melted and regenerated basalt generally has the properties of natural, but in an improved form (see Fig. 3 and 5).

Mechanical properties: a) compressive strength - about 3000 kg / cm 2; b) wear resistance, tested with a Derry mill, powdered with sand, was found to be 0.9 mm average after 1000 revolutions; c) having a high viscosity, basalt does not break easily, and basalt insulators and other products can practically be considered unbreakable. Compared to porcelain, basalt is 2-4 times less brittle; various meanings this value depends on the annealing mode; the presence of impurities brittleness m. highly elevated; d) tensile strength was tested on basalt supports for the third bus of electrical railways. and for comparison, the same sandstone supports were tested; rupture of basalt products was observed at 3700-4700 kg, and the rupture of the same sandstone products - at 1200 kg.

Thermal properties: a) remelted basalt resists temperature changes, even abrupt ones; a plate of basalt 8 mm thick, immersed alternately in boiling water and cold, did not show any signs of cracking; insulators exposed to the sun and then exposed to a thunderstorm, as well as insulators tested according to the rules of the French Union of Electric Syndicates (sudden transfer from water at 65 ° to water at 14 °), showed no change in electrical properties; the upper limit of the thermal interval can be further increased; b) at the moment of solidification, basalt allows for stamping or other introduction of iron parts of any volume into it and adheres firmly to them without requiring cementation; c) basalt endures significant heating without revealing breaks, cracks, "fatigue" or "aging"; d) due to its low thermal conductivity, basalt can serve as a thermal insulator.

Hygroscopicity. Being quite compact and doused with autogenous glaze, basalt is quite waterproof and non-hygroscopic.

Electrical Properties: a) basalt has a significant electrical strength: for bridge basalt, it turned out to be about 32 kV / cm with a plate thickness of 18 mm, and for special electrical basalt, both heat-treated and vitrified, it turned out to be from 57 to 62 kV / cm with the same thickness; b) when a breakdown occurs and a powerful arc is formed, the basalt insulator is still not damaged by this, because after the arc stops, the place of the breakdown swims, and the insulator heals without a trace; c) basalt insulators, when processed, are covered by themselves with glass-like basalt glaze 1.5-2 mm thick, gradually turning inward to granular basalt; this glaze is an excellent barrier to surface electrical leakage and protects insulators and other products from hygroscopicity and from the action of atmospheric agents; having a composition identical to the composition of the insulator itself, the glaze adheres to it as a homogeneous body and therefore is not in danger of cracking or peeling off. In addition, when this glaze is forcibly damaged, a substance of the same composition is exposed, so that the indicated damage is not fatal for the insulator.

Chemical properties. In chemical terms, basalt products, according to French information, are very stable; in table. 1 provides data on the effect of various reagents on processed basalt.

Data from further tests are given in table. 2.

Appearance . Remelted, but not annealed, basalt resembles glass: it has a brilliant fracture, brown-black color and is fragile. After annealing, remelted basalt acquires a black or dark color, matte fine-grained fracture and the viscosity of natural rock. external view products depends on the material of the mold and the mold (see paragraph 4).

So, in terms of mechanical strength, thermal and chemical resistance, high and unique electrical properties, cheapness and relatively easy workability, processed basalt should be recognized as one of the most remarkable materials in electrical engineering.

6. Application of recycled basalt. The basalt industry is still too young to foresee all the uses of the new material at present. So far, the following have been outlined: a) in networks of strong currents of high and low voltage - linear insulators in the open air (Fig. 6),

support insulators, insulators of the third bus of electrical railways. etc. and subways (Fig. 7), output insulators at high voltage;

b) in low current networks and in radio communications - telegraph and telephone insulators, pull insulators and other insulating parts for antennas; c) in the electrochemical industry - insulating stands for batteries, dishes, bathtubs, etc.; d) in the general chemical industry - acid-resistant equipment, including all kinds of dishes, bathtubs, taps, propellers, etc., equipment for temperatures up to 1000 °; e) in construction - insulating bridges (Fig. 8), bridges, stairs, wall and floor cladding, especially when there are acidic vapors, etc.

Line insulators. In view of the exceptional interest of basalt in electrical engineering, we present test data at the Paris Central Electrical Laboratory of ten insulators with iron pins embedded in them, five of which were previously subjected to a thermal test (see paragraph 5). During a dry test, the first sparks sliding over the insulator appeared at 32.5-38 kV, the arc formed at 35-43 kV, the skirt was broken at 40 kV, and the necks at 37.5-39.5 kV. A wet test under artificial rain produced an arc at 18-20 kV followed by 30 sec. the insulator broke. An oil test established the breakdown voltage at 35-58 kV. The test of pull insulators with alternating voltage, which was raised before the breakdown and then, immediately after the breakdown, began to be raised again until a new breakdown, and so 4 times, gave the results presented in Table. 3.

Telegraph type insulators. A test of high-current basalt insulators, similar to telegraph ones, was carried out at the Moscow Scientific Testing Telegraph Station, and the surface electrical resistance of basalt insulators was found to be significantly higher than that of the corresponding porcelain insulators; but when tested in the rain, the resistance of basalt recovered somewhat more slowly than that of porcelain. This probably depended on the rough surface of the high current insulators tested, for which telegraphy requirements were not taken into account.

7. Other uses of basalt. In addition to the use of natural basalt as a building material and crushed stone, and the use of thermally processed basalt in various industries, basalt and related rocks are also used as an integral part in ceramic and glass production. Thus, Borjomi andesite has been used for several years in the manufacture of glass for bottles for Borjomi mineral water, giving it strength and dark color. The English porcelain factory of Wedgwood has long been producing earthenware with a black, unglazed in mass and easily polished shard, the so-called. "Basalt" (Basalt) or "Egyptian" (Egyptian), - the mass for it contains basalt.

Natural stones and rocks have long gone out of the category of only finishing or ballast materials. Thanks to new technologies and chemical processes such classic stones, like basalt or granite, are subjected to deep processing to obtain artificial stone structures with durability and hardness rock.

What is the mineral basalt

From the point of view of chemistry and mineralogy, natural material basalt is a complex structure in which crystalline formations and fine-grained inclusions of magnetite, complex silicates and metal oxides are intertwined. Basalt rock is of igneous origin, so its structure is more like a complex mixture of amorphous volcanic glass, micron crystals of feldspar, quartz, carbonates, sulfide ores.

Basalt stone is easy to distinguish from other volcanic rocks, primarily due to its black, smoky black, greenish color. This stone has found wide use in construction and production of special materials for the chemical industry due to a number of specific properties:

• The material is very heavy and hard, the density of basalt rock can vary from 2.5 to 3 kg per dm 3 , high hardness provides good resistance to abrasion, including under the action of abrasives and water flows.
• The high melting point makes it possible in some cases to use the rocks included in basalt to obtain fire-resistant and refractory materials.

Important ! by the most simple use is the slicing of massifs of basalt into facing stone and plates. Due to the specific natural color of the rock, black or black-green finishes are widely used for wall cladding of basement floors and porches.

The main areas of application of basalt

The most irrational way is to use basalt as ballast, crushed stone for road construction, filler for concrete castings, and foundations. In individual deposits basalt stone has a relatively high water absorption coefficient, due to which screenings from such stone can be used for the manufacture of exceptionally strong concrete foundations, walls, arches, load-bearing columns.

Products of deep processing of basalt

The most well-known materials from basalt, obtained by remelting the rock, are heat insulators, various grades of fiber material, and felt. Mineral fibers from basalt rock have a very high resistance to high temperatures and open flames. For example, a heat-insulating mat made of basalt fiber only 5 cm thick can withstand direct heating of a gas burner without destruction and burnout, while the temperature reverse side the heat insulator does not rise above 50 ° C.

In addition, basalt fiber does not give sharp chips, like fiberglass and glass wool, so it is safer for human skin, and any dust from basalt insulation is easily removed with water. Nevertheless, when handling any heat insulators made of basalt, it is necessary to use respirators and goggles. A few micron thick fiber material produces a large amount of dust, which has a pronounced irritating effect. After completion of work, it is necessary to thoroughly wash the face, hands and other exposed areas of the body in order to get rid of basalt dust, which easily penetrates even through protective gloves.

Basalt felt is considered the most suitable and durable material for arranging the protection and thermal insulation of chimneys, chimneys, fireplace inserts and stoves. Previously, asbestos fiber was used for such purposes, which was abandoned in favor of basalt. Due to the high melting point of basalt, the production of fiber requires significant costs, so thermal insulation based on it stands out for a relatively high price.

The remelting of basalt rock gives not only fiber for the production of heat and thermal insulation, in a similar way high-temperature casting from the melt is produced:

1. Shaped parts and elements, tiles, non-standard floor coverings designed for laying in places with high traffic intensity. Due to the high hardness and wear resistance, the service life of such coatings significantly exceeds the wear parameters of clinker tiles, various types of sintered materials made of ceramics, dolomites, marble, calcite and other types. decorative stone and rock.
2. The high density of basalt stone makes it possible to cast a specific type of products for high voltage electrical networks from the melt. Insulators based on basalt rock have dielectric characteristics much higher than ceramic or glass ones. But not all types of basalt stone have similar properties; rock with exceptionally high density, up to 3 tons per cubic meter, is suitable as a raw material. It is necessary to extract such a rock from a depth of at least 70 meters of the seam in the mine.
3. In addition to mechanical properties, fused basalt products are highly resistant to alkalis and acids at high temperatures, therefore, shaped castings are often made from basalt for the construction of various types of apparatus, product pipelines, and tanks in the chemical industry.

Finishing decorative forms of basalt

In addition to industrial use, basalt is increasingly used as an ornamental stone due to its black with shades of gray, smoky, sometimes greenish color. by the most famous view basalt decor is considered to be Italian-made facing tiles. Basalt tiles of a specific texture with a beautiful pattern can cost at the level of marble or marble-like limestone finishes.

Recently, finishing materials made of natural basalt stone with a specific smoky surface shade have appeared on the market. Due to the characteristic texture natural stone from China is increasingly in demand in the decoration of stairs and the creation of monuments, sculptures, facing fountains. Cheaper varieties of basalt stone are used to build decorative fences, columns, entrance groups, verandas. Increasingly, basalt stone is used as a material for the construction of monuments, steles, elements of tombstones and crypts.

High abrasion resistance makes it possible to use basalt in the form of paving stones for paving pedestrian areas and roadways. At the same time, the service life of such a coating can reach tens of years. In addition to paving stones, cast slabs are used, which in some cases successfully replace the finishing of stairs and steps made of porcelain stoneware, natural granite, gabbro and more expensive finishing materials.

Conclusion

Despite all the advantages of basalt, it is not recommended to use it for interior decoration, since this rock, like other heavy rocks igneous origin, may have an increased radiation background. Therefore, careful checking and monitoring of the level of radioactivity of this finishing material is required before its use.