Metallurgy of antiquity. Origins of ore metallurgy. Copper - the first metal mastered by man The first metal mastered by man was iron
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For many thousands of years, stone products have been the main tools used by man. The craftsmen who processed the stone, like a sculptor, guessed a new quality in it and, cutting off the excess, produced the necessary object. However, ancient man, in essence, only reproduced natural processes, destroying rocks.
The design of products, which has been mastered for several thousand years, required the development of spatial thinking and the development of fundamentally new skills in the manufacture of composite, from several parts and connecting elements, tools. But in this case, before the eyes of the master was the source material of natural origin. Even in the process of mastering the production of ceramics, the natural processes of firing clay in a fire flame were imitated. The manufacture of products from ore metal is a revolutionary technology, a technology that could not be “peeped” in nature! This is the first fully artificial technology in the history of civilization. How did a person learn to receive and process metals? Consider a modern version of this amazing process.
What do the lobster shell and the "supersteel" of the near future have in common? Scientists have found that the chitinous base of the shell, consisting of carbon, hydrogen and nitrogen, is a honeycomb structure of polymer crystals with dimensions of the order of a nanometer, the free space of which is filled with protein. This allows the material to both float in water and have a strength higher than many grades of special purpose steel. It remains to study and apply natural technology in practice. So, the analysis of natural processes and structures is the key to the success of innovative technologies of the 21st century. However, people learned to master this key in ancient times, and the development of metallurgical technologies is a clear example of this.
native metals
Neolithic civilization was preceded by a long formation and slow development of tools and tools used by man. The history of primitive human society was inextricably linked with stone. The most primitive stone products were ordinary river pebbles, chipped at one end. The age of the oldest stone tools dates back to a period of about 2.5 million years. The most important event was the development of flint tools.
Flint was the first to find and embodied the form of such fundamental products for technical progress as an ax, a sickle, a knife, a hammer. The use of native metals most likely began in the Mesolithic (Middle Stone Age), i.e. several tens of thousands of years ago. By this time, the skill of finding, extracting stones and making them not only tools, but also jewelry for primitive man had become commonplace and turned into a kind of industry.
It was in the process of searching for stones suitable for the manufacture of new products that people drew attention to the first nuggets of metals, apparently copper, which are much more common in nature than nuggets of precious metals - gold, silver, platinum. Native (telluric, from the Latin word "tellus" - earth) copper is still found today in many regions of the world: in Asia Minor, Indochina, Altai, and America. Until now, there are copper nuggets weighing several kilograms. The largest manifestation of native copper is considered to be a continuous copper vein found on the Kyusinou Peninsula (Lake Superior, USA). Its mass is estimated at about 500 tons.
Not only noble metals can be present in native form under terrestrial conditions. It is known that nuggets of iron, mercury and lead are found in nature, much less often - nuggets of such metals and alloys as zinc, aluminum, brass, cast iron. They are found in the form of small leaves and scales interspersed in rocks, most often in basalt. In the 20th century, native iron was found, for example, on Disko Island off the coast of Greenland, in Germany (near the city of Kassel), in France (Auvergne department), in the USA (Connecticut). It always contains a significant amount of nickel, impurities of cobalt, copper and platinum (from 0.1 to 0.5% by weight of each element) and, as a rule, is very poor in carbon. Finds of native cast iron are known, for example, on the Russian Islands (in the Far East) and Borneo, as well as in the Avaria Bay (New Zealand), where the native alloy was represented by cohenite - iron-nickel-cobalt carbide (Fe, Ni, Co)3C.
Observation of the change in the shape of nuggets under the blows of hard stones prompted a person to use them for making small jewelry by cold forging. Forging is the oldest method of working metals by pressure. Mastering the method of processing native metal by forging was based on the skills and experience of making stone tools by “upholstering” the stone with a stone hammer. Native copper, which primitive people at first also considered a kind of stone, did not give chips characteristic of stone when struck by a stone hammer, but changed its size and shape without disturbing the continuity of the material. This remarkable technological property of the "new stone" has become a powerful incentive for the search and extraction of native metal and its use by man. In addition, it has been observed that forging increases the hardness and strength of the metal.
At first, ordinary pieces of hard stone were used as a hammer. A primitive craftsman, holding a stone in his hand, struck them at a piece of native, and later - smelted from ore metal. The evolution of this simplest forging method led to the creation of a prototype blacksmith's hammer equipped with a handle. However, metal processing by cold forging had limited possibilities. In this way, it was possible to shape only small objects - a pin, a hook, an arrowhead, an awl. Later, the technology of forging copper nuggets with preheating - annealing was mastered.
Gold nuggets, a metal much more ductile than copper, provided great opportunities for the development of the first metalworking technologies. Gold played an outstanding role in the formation of the mining and metallurgical production of civilization. Placer deposits were the first gold-bearing deposits developed by man. Gold nuggets were found in the mass of alluvial sands and gravels, which were the products of the destruction of gold-bearing rocks, which were exposed to river flows for a long time. Apparently, the oldest jewelry made of gold were nuggets processed in the form of beads by cold forging. These polished beads looked like colored stones strung together in various combinations.
During the extraction of gold from veins, technologies were created, which were then used in the development of deposits of other ancient metals. Gold became the first metal from which they learned to cast products, get wire and foil, gold was first refined. In essence, all metallurgical technologies applied in the era of the Ancient World to silver, copper, lead, and tin were originally worked out on gold.
However, the basis of civilization until the 3rd millennium BC. e. the stone remained. A characteristic feature of early Neolithic technology was the transition to large stone tools. Their appearance is associated with the development of new technological methods of stone processing - drilling, sawing, grinding. Composite ("liner") tools were invented, in which stone material was used only for the working part, and the handles were made of wood, horn or bone. Gradually, the repair of tools was developed - their correction as the working part wears out. Mining arose, in which fire was used to destroy rocks. An amazing technical achievement of people of the Neolithic era is the extraction of flints in mines with a vertical shaft up to 10 m deep and short drifts. Thus, at the beginning of the Neolithic revolution, people had a variety of knowledge about natural substances and materials, methods for their processing.
Thermal technologies of the Neolithic
The most important distinguishing feature of a productive Neolithic economy is the creation of a food supply. When solving the problem of making dishes for its storage, ceramic products are invented and thermal technologies are gradually developing. The first pottery items were baskets made of twigs coated with clay and fired at the stake. Then special kilns for firing were created - forges.
Neolithic stove adapted for natural draft
Modern reconstructions reproduce the Neolithic method of firing pottery as follows. The horn was built in the steep bank of the river, in the walls of ravines or hills, and consisted of two branches. The horizontal sleeve served as a firebox, and the vertical one was filled with pots. When the forge was filled with pre-dried pots, the top of the forge was covered with scrap pottery and a low fire was built using raw wood. Such a fire was maintained until the separation of vapors ceased, after which the fire was increased to a red heat. The pots were in this fire for at least 6 hours. Then the top of the hearth was covered with sand, the firebox was covered with clay and the unit was left in this state for several days. After that, a hole was made in the firebox and gradually enlarged. Finally, the top of the hearth was opened and the finished pots were taken out. Such ancient kilns for firing ceramics were found in Mesopotamia, North Africa, and Eastern Europe. The heating temperature of products in them reached 1100 °C.
To master the metallurgical technology of extracting metal from ore, which requires reliable provision of high temperatures, a furnace with artificial blast was needed. For the first time such furnaces were created for pottery production. Thus, a person got acquainted with the ore metal during the firing of clay pots. There was a process of metal recovery from substances deposited on the walls of pottery for their coloring. It is known that copper carbonates - malachite and lapis lazuli, mercury sulfide - cinnabar, yellow, red and brown iron ocher are bright mineral paints, and applying color patterns to ceramics is one of the oldest art forms.
The process of gradual development of new metals and materials by civilization
The first ore metal mastered by man was copper. This happened, apparently, about 10 thousand years ago. Pins, awls, drills, beads, rings and pendants found in the settlements of Chaionu Tepesi and Chatal Huyuk, which are located on the Konya plateau in Turkey, are currently considered the oldest products from ore copper. These finds date back to the 8th-7th millennium BC. e.
Beginning of the era of metals
The real era of metals began in Eurasia in the 5th millennium BC. e. It is characterized by rarities found in the north of the Balkan Peninsula and in the Carpathian region. In archeology, these territories are usually attributed to the most important Balkan-Carpathian metallurgical province of the Copper-Stone Age.
In the early 70s of the last century, incredibly rich and expressive monuments were discovered there: the Varna “golden” necropolis and the huge Aibunar mine, where, according to calculations, at least 30 thousand tons of copper ore were mined. More than 3 thousand various gold and about 100 copper items were found in the Varna burials. Particular attention is drawn to gold jewelry and objects decorated with complex ornaments, however, massive copper tools, tools and weapons are of no less interest to specialists.
The gold and copper of the Balkan-Carpathian metallurgical province posed an unexpected problem for researchers of ancient metal: what were the general efforts of this metallurgical production aimed at? For casting and forging metal tools in order to increase productivity, as described in most well-known textbooks, or for something else? The calculations of archaeologists have shown that already from the first steps of mining and smelting production, the overwhelming share of its energy was directed to the creation of those products that served the symbolic spheres of public life - jewelry, attributes of power and ritual objects. The giant part of the metal served as a kind of evidence of the social significance of the dead. Thus, for several millennia, metals performed mainly a social, and not a production function.
In the 5th millennium BC. e. in most of the territory of Eurasia, oxidized copper ores were actively developed, the veins of which came to the surface. The mine workings were narrow slots that were formed as a result of excavation of the rock of ore-bearing veins. If a miner came across a powerful ore lens, the gap turned into a cavity at the mining site. The oldest copper mines have been found in Mesopotamia, Spain and the Balkan Peninsula. In the era of antiquity, the island of Cyprus became one of the largest deposits of copper; from its late Latin name "cuprum" came the modern name of copper as a chemical element. The Russian name for the metal comes from the ancient Slavic word "smida", which meant metal in general. Note that the term "smida" dates back to those ancient times when the ancestors of the Slavs and Germans were still a single Indo-Aryan people. Subsequently, in the Germanic languages, the term "smida" began to be used to refer to a person working with metal, and was fixed in the form "smith" (English) or "schmidt" (German) - "blacksmith".
The development of underground ore deposits was mastered in the 4th millennium BC. e. The depth of mine workings reached 30 m or more. Fire, water and wooden wedges were used to crush the rock. A fire was lit near the developed site, the rock was heated, and then quickly cooled, pouring abundant water. Wooden wedges were driven into the formed cracks, which were also poured with water. Swelling, the wedges split the rock. Fragments of ore rock were again heated in the flame of a fire, cooled sharply and crushed with hammers and picks directly in the mines. Crushed ore was taken from the mines in leather bags or wicker baskets. Then it was pounded in large stone mortars to the size of a pea. Ancient metallurgists used charcoal, dense woods, and bones as fuel for smelting metal.
The most ancient method of processing copper ore is crucible smelting: the ore was mixed with fuel and placed in crucibles made of clay mixed with bone ash. The dimensions of the crucibles were small, their height was 12–15 cm, and holes were provided in the lid for the release of gases. In the pottery hearths of the Neolithic times described above, a temperature (up to 1100 ° C) was reached, sufficient to obtain copper containing up to 2% wt. natural impurities of arsenic, nickel, antimony. Subsequently, for the smelting of copper, pit furnaces began to be arranged. In this case, a clay crucible with ore and coal was placed in a shallow pit with a layer of charcoal poured over it. Of particular importance was the choice of the place of melting, which was supposed to provide an intensive flow of air into the unit to fan the fire and achieve the required temperature.
The amount of copper produced in crucibles was small and, as a rule, amounted to several tens of grams, so they gradually switched to the production of copper in pits directly from the ore. To do this, copper ore mixed with charcoal was placed in pits up to 30 cm deep, the bottom of which was lined with stones. A certain amount of charcoal was poured over the charge layer, and tree branches and a small amount of earth were placed on top in such a way as not to impede the flow of air into the heap. They tried to place the smelting place on the slopes of hills in order to use the natural movement of air. This was the first "industrial" metallurgical unit.
Upon completion of the smelting, unburned fuel was removed, and the resulting metal was crushed into pieces convenient for use. This was done immediately after the solidification of the metal, since at this stage copper is especially brittle and easily broken into pieces with a hammer. To give raw copper a marketable appearance, it was subjected to cold forging. Very early it was discovered that copper is a soft and malleable metal, easily compacted and freed from coarse inclusions with the simplest mechanical processing.
With many advantages, copper, even naturally alloyed, had a very significant drawback: copper tools quickly became dull. The wear resistance and other properties of copper were not so high that copper tools and tools could completely replace stone ones. Therefore, throughout the Copper-Stone Age (4th millennium BC), stone successfully competed with copper, which was reflected in the name of the era. The decisive step in the transition from stone to metal was made after the invention of bronze.
As indicated in the previous chapter, individual copper crafts (mainly jewelry) appeared very early. At present, archeology cannot indicate exactly where ores were first smelted or where bronze, an alloy of copper with other metals, was first obtained. In all likelihood, people first used copper of native origin, which was processed as a special kind of stone with plastic properties. But when it was discovered that pieces of copper ore begin to melt when heated strongly, and when cooled again become solid, the process of smelting metal was discovered. The new property of copper began to be used to create tools with a premeditated shape, i.e., the casting process was invented.
With the development of copper smelting, interest in it increased as a new material for the manufacture of tools, and not just jewelry. However, copper of native origin is rarely found on the surface of the earth. In the V millennium BC. e. began to develop oxidized copper ores, the veins of which came to the surface. The development of sulfide ores belongs to a later time. The workings were narrow cracks that were formed as a result of excavation of the rock of ore-bearing veins. If a miner came across a powerful ore lens, the gap turned into a cavity at the mining site. In the IV millennium BC. e. began to move to the development of underground deposits. On the Balkan Peninsula, for example, mine workings reached a depth of 27 m. To break off pieces of ore, it was necessary to first heat the rock, then pour water over it. As a result, cracks were obtained, into which wooden wedges soaked with water were inserted. As the wooden wedges swelled, they tore the ores to pieces. On the Balkan Peninsula, socketed kayla wedges made of deer antler were found in the workings. It is believed that miners used them to extract copper ore from veins.
The process of enrichment of ores took place near the mines. At first, the dry method of enrichment was known: the mined ore was separated from the waste rock and crushed with stone hammers. Later, the wet method of enrichment began to be used. The crushed ore was placed in wooden trays with water. The trays shook, as a result, pieces of ore, as heavier ones, settled to the bottom, and lighter waste rock floated to the top. She was raked, and pieces of copper ore remained in the tray. Sulfide copper ores were fired for a long time before smelting.
Ore was also smelted not far from the mines in special clay furnaces. To obtain a higher temperature in the furnace, people blew air through the blower tubes. In the III millennium BC. e. leather bellows were invented. Ingots of metal smelted from copper ores served as a subject of exchange; as a rule, metallurgists were not engaged in jewelry and blacksmithing.
In the V millennium BC. e. a person got acquainted with other non-ferrous metals: silver and gold.
The first alloy, as the researchers suggest, was billon - an alloy of copper and silver. From it in Southern Turkmenistan at the turn of the 5th-4th millennium BC. e. forged jewelry (pins). An alloy of copper with arsenic became known in the 4th millennium BC. e. Arsenic alloys appear in the Transcaucasus a thousand years earlier than the tin bronzes of Western Europe. From the III millennium BC. e. in the countries of the Ancient East, bronze was more often obtained from an alloy of copper with various proportions of tin. Compared with copper, bronze alloys are distinguished by their fusibility, high casting qualities, and high strength. Depending on the purpose of the casting, from 1-2% to 8-10% tin was added to the metal. The more tin was added, the more fragile the product was.
If the ore was smelted in the immediate vicinity of the mining sites, then copper and bronze products were cast in the settlements. To obtain a bronze alloy, copper and tin or copper and arsenic, taken in certain proportions, were placed in clay crucibles, which were placed in a furnace. Molten metal from crucibles was poured into molds made of sand, stone, wood. At first, open and then closed sash forms were used. Weapons, tools and various tools were cast in molds. Art and jewelry items were cast on a wax model. The model was sculpted from wax, on which finely elutriated clay was applied in layers until the clay wall became strong. Special holes were left in the clay mold to melt the wax and pour the bronze alloy inside. Upon cooling, in order to remove the object, the clay was broken, and to obtain a new casting, the whole process had to be repeated again. Products cast on a wax model are of artistic value.
Non-ferrous metal ores were little available for development; tin deposits - the main raw material for bronze alloys - were known in antiquity on a rather limited scale. The metal had to be transported from the ore mining site over very long distances. All this prevented the widespread introduction of non-ferrous metals into production. According to F. Engels, “...bronze provided suitable tools and weapons, but could not displace stone tools; only iron could do it, and they still did not know how to extract iron ”(Marx K., Engels F. Soch., vol. 21, p. 161).
The special properties of the new material were quickly mastered, more productive tools and weapons were created, which could not but affect the development of agriculture and crafts.
As you know, the main material from which primitive people made tools was stone. No wonder the hundreds of thousands of years that have passed between the appearance of man on earth and the emergence of the first civilizations are called the Stone Age. But in 5-6 millennia BC. e. people discovered metal.
Most likely, at first, a person treated metal in the same way as a stone. He found, for example, copper nuggets and tried to process them in the same way as a stone, that is, with the help of upholstery, grinding, squeezing flakes, etc. But the difference between stone and copper quickly became clear. Perhaps, even initially, people decided that there would be no sense in metal nuggets, especially since copper was quite soft, and the tools that were made from it quickly failed. Who came up with the idea of melting copper? Now we will never know the answer to this question. Most likely, everything happened by accident. An annoyed person threw a pebble, which seemed to him unsuitable for making an ax or an arrowhead, into the fire, and then was surprised to notice that the pebble spread out in a shiny puddle, and after the fire burned out, it froze. Then it took only a little thought - and the idea of melting was discovered. On the territory of modern Serbia, a copper ax was found, created 5,500 years before the birth of Christ.
True, copper, of course, was inferior in many respects even to stone. As mentioned above, copper is too soft a metal. Its main advantage was fusibility, which made it possible to make a wide variety of objects from copper, but in terms of strength and sharpness, it left much to be desired. Of course, before the discovery, for example, of Zlatoust steel (Article "Russian Bulat from Zlatoust"), several more millennia should have passed. After all, technologies were created gradually, at first - insecure, timid steps, by trial and countless mistakes. Copper was soon replaced by bronze, an alloy of copper and tin. True, tin, unlike copper, is not found everywhere. It is not for nothing that in ancient times Britain was called the "Tin Islands" - many peoples equipped trading expeditions there for tin.
Copper and bronze became the basis of ancient Greek civilization. In the Iliad and the Odyssey we constantly read that the Greeks and Trojans were dressed in copper and bronze armor and used bronze weapons. Yes, in ancient times, metallurgy largely served the military. They often plowed the land in the old fashioned way, with a wooden plow, and, for example, drains could be made of wood or clay, but the fighters entered the battlefield in strong metal armor. However, bronze as a material for weapons had one serious drawback: it was too heavy. Therefore, over time, a person learned to smelt and process steel.
Iron has been known since the Bronze Age on Earth. However, raw iron, obtained as a result of processing at a low temperature, was too soft. Meteoritic iron was more popular, but it was very rare, it could only be found by chance. However, meteoritic iron weapons were expensive, and it was very prestigious to have them. The Egyptians called daggers forged from meteorites that fell from the sky Heavenly.
It is generally accepted that iron processing was widespread among the Hittites living in the Middle East. They are about 1200 BC. e. learned to smelt real steel. For a while, Middle Eastern powers became incredibly powerful, the Hittites defied Rome itself, and the Philistines, mentioned in the Bible, owned vast territories in the modern Arabian Peninsula. But soon their technological advantage faded, because steelmaking technology, as it turned out, was not so difficult to borrow. The main problem was the creation of furnaces in which it was possible to reach the temperature at which iron turned into steel. When the neighboring peoples learned to build such melting furnaces, steel production began literally throughout Europe. Of course, much depended on raw materials. After all, only relatively recently people have learned to enrich the raw materials with additional substances that give steel new properties. For example, the Romans mocked the Celts, because many of the Celtic tribes had such bad steel that their swords bent in battle, and the warriors had to run back to the back row to straighten the blade. But the Romans bowed before the products of gunsmiths from India. And among some Celtic tribes, steel was not inferior to the famous Damascus. (Article "Damascus steel: myths and reality")
But, in any case, humanity entered the Iron Age, and it could no longer be stopped. Even the widest spread of plastics that occurred in the twentieth century could not displace metal from most areas of human activity.
Student Supplement #2
on the topic "Minerals and alloys in the design
Station "Revolution Square"
Moscow Metro"
Copper is the first metal mastered by man
The role of copper in the development of human culture is special. The use of copper and bronze as the most important materials lasted for millennia. Copper, like noble metals, sometimes forms nuggets. Scientists believe that it was from them that the first metal tools were made 10 thousand years ago. Due to the softness and rather widespread occurrence of copper in nature, man began to use it long before iron.
Historians have established that in ancient Egypt, when building pyramids, artisans used stone tools (made of granite and dolerite) and copper tools. The metal was remarkably hard. This allowed Egyptologists to suggest that already in the III millennium BC. e. The Egyptians had some special recipe for mechanical processing of copper, which gave the metal high strength.
The addition of tin to copper significantly increases the strength and hardness of the material. This was known as early as 5000 years ago, and possibly even earlier. The production of copper alloys was the greatest achievement of ancient metallurgy and gave its name to an entire era - the Bronze Age.
The change of epochs among different peoples, in different parts of the globe took place unevenly, and the chronological framework of the epochs can only be indicated approximately:
STONE → COPPER AGE → BRONZE → IRON
AGE (chalcolith) AGE AGE
4th-3rd millennium 4th-1st millennium beginning of the 1st millennium
BC e. BC e. BC e.
The spread of bronze in the advanced cultural centers of metallurgy began at the end of the 4th millennium BC. e. The oldest bronze items were found on the territory of Mesopotamia (in Sumer), Turkey, Iran. At the end of the third millennium BC. e. bronze appeared in Egypt, India, and in the middle of the II millennium BC. e. in China and Europe. In America, the Bronze Age, the Bronze Age covers the period from the 4th to the 10th centuries. n. e. The leading metallurgical centers here were located on the territory of modern Peru and Bolivia.
In addition to bronzes - copper-tin alloys, the ancients also used copper-zinc alloys - brass, which are stronger and more malleable than bronze. It is noteworthy that people of ancient times were not familiar with zinc as a substance. In its pure form, this metal was isolated only in the middle of the 18th century by electrolysis. So, during excavations in Thebes, papyri were found, which describe the secret of making "gold" from copper. In fact, they are, in all likelihood, about obtaining brass by adding natural zinc compounds to copper. Brass resembles gold in its color and brilliance.
Methods for obtaining copper
The low chemical activity of copper makes it possible for it to exist in nature in its native state.
More than 200 minerals are known that contain copper in their composition, including chalcopyrite (copper pyrite) CuFeS2, malachite (CuOH) 2CO3, chalcocite (copper luster) Cu2S, cuprite Cu2O.
Pure copper is obtained by various methods. Hydrometallurgical method - extraction of metals from ores using reagents (H2SO4, KCN, etc.) in the form of compounds soluble in water, followed by processing of these solutions to isolate metals in a free form.
When ore containing CuO is treated with dilute sulfuric acid, copper goes into solution in the form of sulfate:
CuO + H2SO4 = CuSO4 + H2O
Then it is removed from the solution either by electrolysis or displaced from sulfate with iron:
CuSO4 + Fe = Cu + FeSO4
All methods of obtaining copper from compounds are based on redox processes.
Chemical properties of copper
In dry form and at normal temperature, copper almost does not change. At elevated temperatures, copper can react with simple and complex substances.
Interaction with simple substances:
Cu + Cl2 = CuCl2
2CuO + O2 = 2CuO
Interaction with complex substances:
Cu + 2H2SO4 = CuSO4 + SO2 + 2H2O
Cu + 4HNO3 = Cu(NO)3 + 2NO2 + 2H2O
Copper and its alloys
Copper has a melting point of 1083oC.
There are two groups of copper alloys: brass– copper-zinc alloys, bronze- alloys of copper with other (except zinc) elements.
Aluminum" href="/text/category/aluminij/" rel="bookmark">aluminum, Mn - manganese, C - lead, B - beryllium, Mg - magnesium, Cp - silver, F - iron, Msh - arsenic, Su - antimony, K - silicon, N - nickel, T - titanium, Kd - cadmium, O - tin, F - phosphorus, X - chromium, C - zinc.
All bronze is marked with the abbreviation "Br", indicating this category of copper alloys. After designating the class of copper alloy "Br" come letters to help identify the added elements.
For example, BrO5Ts6 means that this bronze alloy contains 5% tin and 6% zinc, and the designation BrO5Ts2N5 indicates that the alloy includes 5% tin, 2% zinc and 5% nickel. The BrO10Ts2 marking identifies a bronze alloy containing 10% tin and 2% zinc.
At the Leningrad state copper-working plant "Krasny Vyborzhets" (1924), the so-called artistic red bronze with a zinc additive not exceeding 6% was used for casting. Red bronze is not sensitive to temperature changes.
But the projects at the plant were cast 80 sculptural figures for the station "Revolution Square" of the Moscow Metro.
Varieties of marbles in the design of metro stations
Each metro station is like a mineralogical museum, each of them has its own exposition.
The basement of the Ploshchad Revolyutsii metro station is lined with black Armenian marble-like limestone with “golden” veins, which has turned into a huge pedestal, and the arches are made of dark red marble-like limestone shrosha. The arches were built from solid stones carved from marble blocks. The walls of the pylons are lined with red shrosha, gray-blue ufaley, yellow-pink marble-like biyuk-yanka limestone. The track walls of the station were decorated with gray Ufaley marble, with a cornice made of red shrosha, and a plinth-carpet mosaic of olive-black marble-like sadakhlo and dalu limestones. The floor of the station hall is a checkerboard alternation of dark gray Zhezhelevsky granite and black gabbro, and the platforms are finished with the same granite and labranite.
On the walls of the platforms are fixed bronze arrows with the inscriptions "Exit to the city" - these are the oldest surviving signs of the Moscow metro.
The following types of marbles are most common in construction practice:
Ufaleysky(Ufaley), gray-blue.
Marbles of Georgia. Shroshinsky (Shrosha), dark red with white streaks.
Sadakhlinsky(Sadakhlo), dark black with white and yellowish-golden streaks.
Marbles of Armenia. Davalinsky (Davalu), black with golden streaks. This marble is usually used in combination with marbles of other colors for pedestals and plinths of marble cladding.
“Seven metals were created by light according to the number of seven planets” - one of the most important postulates of medieval alchemy was concluded in these simple verses. In antiquity and the Middle Ages, only seven metals and the same number of celestial bodies were known (the Sun, the Moon and five planets, not counting the Earth). In the opinion of the then luminaries of science, only fools and ignoramuses could not see in this the deepest philosophical regularity. A coherent alchemical theory said that gold was represented in heaven by the Sun, silver was a typical Moon, copper was undoubtedly related to Venus, iron was personified by Mars, mercury corresponds to Mercury, tin to Jupiter, lead to Saturn. Until the 17th century, metals were designated in the literature by the corresponding symbols.
Figure 1 - Alchemical signs of metals and planets
Currently, more than 80 metals are known, most of which are used in engineering.
Since 1814, at the suggestion of the Swedish chemist Berzelius, letters have been used to designate metals.
The first metal that man learned to work with was gold. The most ancient things made of this metal were made in Egypt about 8 thousand years ago. In Europe, 6 thousand years ago, the Thracians, who lived in the territory from the Danube to the Dnieper, were the first to make jewelry and weapons from gold and bronze.
Historians distinguish three stages in the development of mankind: the Stone Age, the Bronze Age and the Iron Age.
In 3 thousand BC. people began to widely use metals in their economic activities. The transition from stone to metal tools was of tremendous importance in the history of mankind. Perhaps no other discovery has led to such significant social changes.
The first metal to become widespread was copper (Figure 2).
Figure 2 - Map-scheme of the territorial and chronological distribution of metals in Eurasia and North Africa
The map clearly shows the location of the oldest finds of metal products. Almost all known artifacts related to the period from the end of the 9th to the 6th millennium BC. (that is, before the culture of the Uruk type was widely spread in Mesopotamia), come from only three dozen sites scattered over a vast territory of 1 million km 2. About 230 small specimens were recovered from here, and 2/3 of them belong to two settlements of the pre-ceramic Neolithic - Chaion and Ashikli.
Constantly looking for the stones they needed, our ancestors, one must think, already in antiquity paid attention to reddish-green or greenish-gray pieces of native copper. In the cliffs of the banks and rocks, they came across copper pyrite, copper sheen and red copper ore (cuprite). At first, people used them as ordinary stones and processed them accordingly. They soon discovered that when copper was worked with a stone hammer, its hardness increased significantly, and it became suitable for making tools. Thus, the methods of cold metal working or primitive forging came into use.
Then another important discovery was made - a piece of native copper or surface rock containing metal, falling into the fire of a fire, revealed new features that were not characteristic of stone: from strong heating, the metal melted and, cooling, acquired a new shape. If the form was made artificially, then a product necessary for a person was obtained. This property of copper was used by ancient craftsmen first for casting jewelry, and then for the production of copper tools. This is how metallurgy was born. Melting began to be carried out in special high-temperature furnaces, which were a slightly modified design of pottery furnaces well known to people (Figure 3).
Figure 3 - Metal smelting in Ancient Egypt (blowing is supplied by furs sewn from animal skins)
In southeastern Anatolia, archaeologists have discovered a very ancient pre-ceramic Neolithic settlement of Chayonyu Tepesi (Figure 4), which struck with the unexpected complexity of stone architecture. Scientists found among the ruins about a hundred small pieces of copper, as well as many fragments of the copper mineral - malachite, some of which were processed into beads.
Figure 4 - Chayonyu Tepesi settlement in Eastern Anatolia: IX-VIII millennium BC The world's oldest metal was discovered here
Generally speaking, copper is a soft metal, much less hard than stone. But copper tools could be quickly and easily sharpened. (According to the observations of S.A. Semenov, when replacing a stone ax with a copper one, the cutting speed increased approximately three times.) The demand for metal tools began to grow rapidly.
People began a real "hunt" for copper ore. It turned out that it is not found everywhere. In those places where rich deposits of copper were discovered, their intensive development arose, ore and mine business appeared. As the discoveries of archaeologists show, already in antiquity the process of ore mining was staged on a large scale. For example, near Salzburg, where copper mining began around 1600 BC, the mines reached a depth of 100 m, and the total length of the drifts extending from each mine was several kilometers.
The ancient miners had to solve all the problems that modern miners face: strengthening the vaults, ventilation, lighting, lifting the mined ore up the mountain. The galleries were reinforced with wooden supports. The mined ore was smelted nearby in low clay furnaces with thick walls. Similar centers of metallurgy existed in other places (Figures 5.6).
Figure 5 - Ancient mines
Figure 6 - Tools of ancient miners
At the end of 3 thousand BC. ancient masters began to use the properties of alloys, the first of which was bronze. The discovery of bronze should have been prompted by an accident, inevitable in the mass production of copper. Some grades of copper ores contain an insignificant (up to 2%) admixture of tin. Smelting such ore, the craftsmen noticed that the copper obtained from it is much harder than usual. Tin ore could get into copper-smelting furnaces for another reason. Be that as it may, observations of the properties of ores led to the development of the value of tin, which they began to add to copper, forming an artificial alloy - bronze. When heated with tin, copper melted better and was easier to cast, as it became more fluid. Bronze tools were harder than copper ones, sharpened well and easily. Bronze metallurgy has made it possible to increase labor productivity several times in all branches of human activity (Figure 7).
The production of tools itself has become much simpler: instead of long and hard work pounding and grinding stone, people filled ready-made forms with liquid metal and got results that their predecessors never even dreamed of. The casting technique has been gradually improved. At first, casting was carried out in open clay or sand molds, which were simply a depression. They were replaced by open forms carved from stone that could be reused. However, the big disadvantage of open molds was that only flat products were obtained in them. They were not suitable for casting products of complex shape. The way out was found when closed detachable molds were invented. Before casting, the two halves of the mold were tightly connected to each other. Molten bronze was then poured through the hole. When the metal cooled and solidified, the mold was dismantled and the finished product was obtained.
Figure 7 - Bronze tools
This method made it possible to cast products of complex shape, but it was not suitable for figured casting. But even this difficulty was overcome when the closed form was invented. With this casting method, an exact model of the future product was first molded from wax. Then it was coated with clay and fired in a kiln.
The wax melted and evaporated, and the clay took an exact cast of the model. Bronze was poured into the void thus formed. When it cooled down, the mold was broken. Thanks to all these operations, the craftsmen were able to cast even hollow objects of a very complex shape. Gradually, new techniques for working with metals were discovered, such as drawing, riveting, soldering and welding, which supplemented the already known forging and casting (Figure 8).
Figure 8 - Golden hat of the Celtic priest
Perhaps the largest metal casting was made by Japanese craftsmen. It was 1200 years ago. It weighs 437 tons and represents the Buddha in a pose of appeasement. The height of the sculpture together with the pedestal is 22 m. The length of one arm is 5 m. Four people could freely dance on an open palm. We add that the famous ancient Greek statue - the Colossus of Rhodes - 36 m high and weighed 12 tons. It was cast in the 3rd century. BC e.
With the development of metallurgy, bronze products began to displace stone products everywhere. But do not think that it happened very quickly. Non-ferrous metal ores were not available everywhere. Moreover, tin was much less common than copper. Metals had to be transported over long distances. The cost of metal instruments remained high. All this prevented their wide distribution. Bronze could not completely replace stone tools. It turned out that only iron could do it.
In addition to copper and bronze, other metals were widely used.
Beads and pendants found in Asia Minor during the excavations of Chatal-Khuyuk and seals and figurines found in Yarym-Tepe (Northern Mesopotamia) are considered the oldest products made of lead. These finds date back to the 6th millennium BC. The first iron rarities, which are small kritz found in Chatal-Hyuk, also date back to the same time. The oldest silver items were found on the territory of Iran and Anatolia. In Iran, they were found in the town of Tepe-Sialk: these are buttons dating back to the beginning of the 5th millennium BC. In Anatolia, in Beydzhesultan, a silver ring was found dating back to the end of the same millennium.
In prehistoric times, gold was obtained from placers by washing. It came out in the form of sand and nuggets. Then gold refining (removal of impurities, separation of silver) began to be used, in the second half of the 2nd millennium BC. In the 13th-14th centuries, they learned to use nitric acid to separate gold and silver. And in the 19th century, the amalgamation process was developed (although it was known in antiquity, there is no evidence that it was used to extract gold from sands and ores).
Silver was mined from galena, along with lead. Then, after centuries, they began to be smelted together (approximately by the 3rd millennium BC in Asia Minor), and this became widespread even after 1500-2000 years.
Around 640 BC e. began to mint coins in Asia Minor, and around 575 BC. e. - in Athens. In fact, this is the beginning of stamping production.
Tin was once smelted in simple shaft furnaces, after which it was purified by special oxidizing processes. Now in metallurgy, tin is obtained by processing ores according to complex integrated schemes.
Well, mercury was produced by roasting ore in heaps, in which it condensed on cold objects. Then ceramic vessels (retorts) appeared, which were replaced by iron ones. And with the growing demand for mercury, they began to receive it in special furnaces.
Iron was known in China as early as 2357 BC. e., and in Egypt - in 2800 BC. e., although as early as 1600 BC. e. iron was looked upon as a curiosity. The “Iron Age” in Europe began around 1000 BC. e., when the art of iron smelting penetrated into the states of the Mediterranean from the Scythians of the Black Sea.
The use of iron began much earlier than its production. Sometimes they found pieces of a grayish-black metal, which, reforged into a dagger or spearhead, gave a weapon more durable and ductile than bronze, and held a sharp blade longer. The difficulty was that this metal was found only by accident. Now we can say that it was meteoric iron. Since iron meteorites are an iron-nickel alloy, it can be assumed that the quality of individual unique daggers, for example, could compete with modern consumer goods. However, the same uniqueness led to the fact that such weapons ended up not on the battlefield, but in the treasury of the next ruler.
Iron tools decisively expanded the practical possibilities of man. It became possible, for example, to build houses cut from logs - after all, an iron ax felled a tree not three times like a copper one, but 10 times faster than a stone one. Hewn stone construction also became widespread. Naturally, it was also used in the Bronze Age, but the large consumption of a relatively soft and expensive metal strongly limited such experiments. The possibilities of farmers have also expanded significantly.
For the first time, the peoples of Anatolia learned to process iron. The ancient Greek tradition considered the people of Khalibs to be the discoverer of iron, for whom the stable expression “father of iron” was used in literature, and the name of the people itself comes from the Greek word Χ?λυβας (“iron”).
The Iron Revolution began at the turn of the 1st millennium BC. e. in Assyria. From the 8th century BC e welded iron quickly began to spread in Europe, in the III century BC. e. replaced bronze in Gaul, appeared in Germany in the 2nd century AD, and in the 6th century AD it was already widely used in Scandinavia and among the tribes living on the territory of the future Russia. In Japan, the Iron Age came only in the 8th century AD.
At first, only small quantities of iron were received, and over the course of several centuries it cost sometimes forty times more than silver. The iron trade restored the prosperity of Assyria. The way was opened for new conquests (Figure 9).
Figure 9 - Furnace for iron smelting among the ancient Persians
Metallurgists were able to see liquid iron only in the 19th century, however, even at the dawn of iron metallurgy - at the beginning of the 1st millennium BC - Indian craftsmen managed to solve the problem of obtaining elastic steel without melting iron. Such steel was called damask steel, but due to the complexity of manufacturing and the lack of necessary materials in most of the world, this steel remained an Indian secret for a long time.
A more technological way to obtain elastic steel, which did not require either especially pure ore, or graphite, or special furnaces, was found in China in the 2nd century AD. Steel was reforged many times, with each forging folding the workpiece in half, resulting in an excellent weapon material called Damascus, from which, in particular, the famous Japanese katanas were made.