For several hundred years, the Russian Federation has been among the world leaders in the production of cast iron. This alloy is used in various industries, used to create art and decorative products. Experts say: cast iron is an integral part of human life, it is deservedly considered one of the most popular materials. Today we propose to talk about ferrous metallurgy, the production of pig iron and steel, their impact on humans. Let us turn to the chronicle of the foundry as a whole: historical facts and interesting information await you!
History: Copper-Stone Age
Cast iron is a metal whose history dates back thousands of years, its roots go back to the era of BC. In general, historians date the first evidence of the emergence of metallurgy VI-V millennium BC. Then man still used stone to create tools, but he already came across copper nuggets. Taking the nuggets for ordinary stones and processing them in the way that was applied to any stones - just hitting each other - a person understood: these stones do not crack, but only deform, and therefore they can be given almost any shape. Historians would later call this method cold forging. So copper has become a substitute for stone, making fishing hooks, spearheads and daggers has become much easier, moreover, the quality of such products far exceeded the quality of analogues of stone and bone. At the same time, the processing of wood improved, it became possible to produce small parts. By the way, scientists have proved: in those areas where copper was actively used, the appearance of the wheel occurred much earlier. This is proved by the fact that the development of mankind is inextricably linked with the development of metallurgy.
Bronze Age
When people learned to create bronze - an alloy consisting of copper and tin, humanity entered the Bronze Age. Today, historians cannot answer the question of how exactly a person invented such an alloy. Most researchers believe that this happened by pure chance, when tin fell into a container with molten copper. The fact remains: for a thousand years, people fought with bronze swords and cooked in bronze pots.
Iron Age
Historians say iron was much easier to mine than copper or tin. The thing is that it is found in the form of oxide and nitrous oxide everywhere. So why didn't people start using iron before? The answer is simple: the production of this metal is an incredibly complex and time-consuming process that takes place in several stages. The study of this process took more than one century of development. Therefore, it is not surprising that the metallurgists of those times were popularly considered to be true sorcerers burning magic things.
The first mention of cast iron
The country in which the production of pig iron began is today considered China. Historians say that this happened around the fifth century BC. In China, coins, household utensils, and various weapons made from cast iron were extremely popular. Many cast-iron castings have survived to our times, for example, a magnificent cast-iron lion, whose height is 6 meters and its length is 5. Scientists have proved that this statue was cast at a time, which undoubtedly testifies to the great skill of the first Chinese metallurgists.
An interesting fact: around the world, the beginning of the production of malleable cast iron is considered the 19th century AD, although it is reliably known that in China they made swords from it even before the birth of Christ!
The origin of production in Russia
When did the production of pig iron in Russia begin? Archaeological excavations carried out on the territory of large cities of the Golden Horde prove: the emergence and development of this production in Russia began back in the days of the Tatar-Mongol yoke! A certain role in this was played by the proximity of the Mongol kingdom to China.
In almost all Tatar-Mongolian cities Rusich lived, who had their own workshops and shopping arcades here. They not only adopted the knowledge of local masters, but also shared their own. After the Horde fell, technology continued to evolve and improve. Already in the 16th century, during the reign of Vasily the Third and Ivan the Terrible, the production of foundry pig iron began to be actively used in artillery, mainly made from it cores and small guns. Then, historians say, cast iron was also used in casting bells. The main production took place in cities such as Moscow and Tula. It is worth noting that until the XVII century, Europe did not know such technologies, and therefore Russian plants could actively export various tools and cores from cast iron to European countries.
Active development
During the time of the Petrine era, the active development of the production of pig iron and steel began. The tsar understood: an increase in metallurgical capacities would lead Russia to development. Peter I had everything necessary for the realization of incredible plans: both materials and production technologies. It was with this king that the active construction of factories began in Siberia, in the Urals. Over the entire reign of Peter the Great, the production of pig iron and steel was increased by 770 times, 16 large metallurgical plants appeared in Russia. Development continued after the death of the emperor, at the end of the 18th century there were more than a hundred factories on the territory of the Russian Empire, the country became a world leader in this field. Along with the development of the industry, the metal application industries also developed. Not only weapons were now made from cast iron, but also dishes, monuments, gates and fences.
It is worth noting that domestic blast furnaces used for the production of cast iron were recognized as the best in the world. They were characterized by the greatest productivity, even at minimal cost. In the 19th century, foundries were separated from domain ones, which allowed not only to specialize the process, but also to mechanize it. It was during this period that pipe foundries and workshops appeared producing malleable cast iron.
Russia is a world leader
In the XX century, Russia did not slow down and remained the leader in casting iron. In the USSR, of the total amount of metal casting , pig iron was about 75%. It was the number one raw material, its main consumers were the defense industry and agriculture. It was from cast iron that specialists made parts and various units for equipment. It is worth noting that even today Russia maintains a leading position in terms of production and use of cast iron. Not only bulky products are made of it, but also such delicate work as gate elements, decorations, stove castings and souvenirs!
Cast iron production: necessary equipment
Let's start with the definition. Cast iron is usually called an alloy of iron with carbon, and carbon should be at least 2% here. So how does the cast iron production process go? First of all, this requires a huge blast furnace. Its dimensions are striking: the height of such a furnace is 30 m, and the internal diameter is 12 m. The widest part of the furnace is called steaming, the lower, through which hot air enters the furnace, is the forge, the upper is the mine. By the way, on the top there is a special hole - the top, which is closed with a special shutter. The principle of operation of the blast furnace is countercurrent: air is supplied to it from below and materials from above. Materials necessary for the production of pig iron include flux (without it, slag cannot form), coke (it is necessary for heating water, its melting and reduction) and ore (which, in fact, is the main raw material).
For production, you will also need:
- trolleys;
- conveyors
- bunkers;
- special crane, etc.
Raw materials
Acquaintance with alloys, the production of pig iron and steel begins back in school - this topic is provided for in the chemistry work program. The textbooks discuss the composition of iron ore: it is the ore substance itself, that is, iron carbonates, silicates and oxides, and waste rock, consisting of dolomite, sandstone, limestone and quartzite. It should be noted that in different ore different amounts of ore substance may be present. It is by this criterion that the ore is divided into rich and poor. The first is sent for enrichment, and the second can be immediately used in production.
In order to produce a ton of pig iron, it will take: three tons of ore, a ton of coke, twenty tons of water. The amount of flux depends on the type of ore.
Types of Iron Ores
Before we get to know the process of cast iron production, we offer information on the types of iron ores. It could be:
- Brown iron ore. It is characterized by a content of 25-50% of iron in the form of so-called aqueous oxides. The waste rock is clayey.
- Hematite (it is also called red iron ore). This is anhydrous oxide, the content of harmful impurities is minimal. Iron is about 45-55%.
- Magnetic iron ore. The iron content here is about 30-37%. The waste rock is a siliceous mass.
- Siderite (its second name is spar iron ore) is extremely easily oxidized, turning into the form of brown limestone.
Production technology
Cast iron production technology consists of several stages. It all starts with the preparation of ore: it is sorted by chemical composition and, of course, size. Large raw materials are crushed, and small particles or ore dust are granulated. At the same stage, enrichment of poor ores occurs. In addition, in the preparation process, a significant part of the waste rock is removed , respectively, the iron content in this case increases. The next stage of cast iron production technology is fuel preparation. It all starts with coke. During this stage, the coke is screened - all unnecessary detail is removed from it, which can lead to loss of fuel. The next stage in the blast furnace production of cast iron is the preparation of fluxes. Pluses are crushed, a trifle is sifted out of it. After this procedure, all materials are loaded into the furnace. Then the blast furnace production of cast iron begins directly: the furnace is charged with coke, an agglomerator (the so-called flux sintered ore) is added, and coke is introduced again.
The temperature required for smelting is maintained by blowing heated air. In the process of coke combustion, carbon dioxide is formed in the furnace. CO 2 passing through coke becomes CO. Next, carbon monoxide restores the bulk of the ore. In this process, the iron becomes solid, passing into that part of the furnace, in which the air is very hot. Here, iron dissolves carbon within itself. Actually, this is how iron production in a blast furnace looks like. Liquid iron from the furnace falls into special ladles, from which it is poured into previously prepared forms. Pouring into special collectors-mixers is possible, in which the alloy will remain in liquid form for some time. Along with the blast furnace production of pig iron, silicon, manganese and a number of other impurities are being reduced.
Types of cast iron
There are only two types of cast irons: white and gray. The difference between them is the chemical composition and the heat treatment process. So, white cast iron is the result of very fast cooling, while gray cast iron is obtained as a result of slow cooling. White is characterized by qualities such as fragility and hardness. They are extremely difficult to cut, in its process pieces are broken off from them. Therefore, white cast irons are used only as blanks for the production of other types of cast iron. For example, as a result of firing this type, malleable cast irons are obtained. Please note: the name “malleable” has nothing to do with the forging process. According to historians, it appeared due to the fact that previously horseshoes were made of cast iron with such characteristics. This type is actively used in agricultural engineering and in the automotive industry. The main difference between gray cast irons is ductility combined with high strength. This allows you to use them in areas such as machine tools, agriculture and the automotive industry, domestic use.
By the way, there are so-called half cast irons. They have intermediate properties of white and gray species. In addition, by adjusting the cooling rate of this alloy, you can get a variety of castings, which will differ in strength, ductility and other properties. Cast iron with special properties include:
- antifriction used for the manufacture of bushings, shafts, bearings;
- wear-resistant, necessary for the creation of pumping equipment, various parts for the nitrogen industry, furnace casting;
- heat-resistant, which are used in the manufacture of furnace castings, tube complexes and gas turbine engines;
- heat resistant, suitable in order to make of them kiln parts fittings and boilers;
- corrosion resistant, indispensable for the manufacture of various parts in the chemical and aviation industries, which are used in aggressive environments.
Cast iron specifications
The following qualities are characteristic of high-quality cast iron:
- excellent heat capacity;
- good resistance to corrosion;
- increased heat resistance.
These and other characteristics allow cast iron to be used both in everyday life and in heavy industry. Particularly popular are cookware made of cast iron of Russian production. Not only pans and pans are made from this material; fondue, roasters, baking dishes, stewpan and grills are found.
It is worth noting that dishes from this material are equally well suited for frying pancakes, cooking stews, cereals, for stewing pilaf. The fact is that cast iron heats up quite slowly, but it perfectly stores heat and evenly distributes it. Experts say: different companies are involved in the production of cast iron cookware. All of them produce products of approximately the same quality. Of all this diversity, the products of the St. Petersburg Neva plant stand out especially. This plant is one of the largest manufacturers of cast iron cookware in the Russian Federation.