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Steel making at the moment falls into two flows “iron ore steel” and “scrap steel” or full flow and short range. The former is represented by blast furnaces and converters in integrated steel complex while the latter is electric arc furnace based.Around a third of crude steel worldwide is produced by electric furnace, since it helps reduce burden on environment, boosting recycling economy and other advantages like short procedures and construction period and low investment. And it should become a mode for sustainable steel development.
Steel is an alloy that consists mostly of iron and has a carbon content between 0.2% and 2.1% by weight, depending on the grade. Carbon is the most common alloying material for iron, but various other alloying elements are used, such as manganese, chromium, vanadium, and tungsten. Carbon and other elements act as a hardening agent, preventing dislocations in the iron atom crystal lattice from sliding past one another. Varying the amount of alloying elements and the form of their presence in the steel (solute elements, precipitated phase) controls qualities such as the hardness, ductility, and tensile strength of the resulting steel. Steel with increased carbon content can be made harder and stronger than iron, but such steel is also less ductile than iron.
Alloys with a higher than 2.1% carbon content are known as cast iron because of their lower melting point and cast ability. Steel is also distinguishable from wrought iron, which can contain a small amount of carbon, but it is included in the form of slag inclusions. Two distinguishing factors are steel's increased rust resistance and better weld ability.
Though steel had been produced by various inefficient methods long before the Renaissance, its use became more common after more-efficient production methods were devised in the 17th century. With the invention of the Bessemer process in the mid-19th century, steel became an inexpensive mass-produced material. Further refinements in the process, such as basic oxygen steel making (BOS), lowered the cost of production while increasing the quality of the metal. Today, steel is one of the most common materials in the world, with more than 1.3 billion tons produced annually. It is a major component in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons. Modern steel is generally identified by various grades defined by assorted standards organizations.
There are many types of heat treating processes available to steel. The most common are annealing and quenching and tempering. Annealing is the process of heating the steel to a sufficiently high temperature to soften it. This process occurs through three phases: recovery, re crystallization, and grain growth. The temperature required to anneal steel depends on the type of annealing and the constituents of the alloy.
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Quenching and tempering first involves heating the steel to the austenite phase, then quenching it in water or oil. This rapid cooling results in a hard and brittle martensitic structure. The steel is then tempered, which is just a specialized type of annealing. In this application the annealing (tempering) process transforms some of the martensite into cementite, or spheroidite to reduce internal stresses and defects, which ultimately results in a more ductile and fracture-resistant metal.
When iron is smelted from its ore by commercial processes, it contains more carbon than is desirable. To become steel, it must be melted and reprocessed to reduce the carbon to the correct amount, at which point other elements can be added. This liquid is then continuously cast into long slabs or cast into ingots. Approximately 96% of steel is continuously cast, while only 4% is produced as cast steel ingots. The ingots are then heated in a soaking pit and hot rolled into slabs, blooms, or billets. Slabs are hot or cold rolled into sheet metal or plates. Billets are hot or cold rolled into bars, rods, and wire. Blooms are hot or cold rolled into structural steel, such as I-beams and rails. In modern foundries these processes often occur in one assembly line, with ore coming in and finished steel coming out. Sometimes after a steel's final rolling it is heat treated for strength, however this is relatively rare.
The metals are very useful and versatile. They have many uses in cars, trucks, ships, aeroplanes, ovens, cutlery, railway tracks, crockery and it can also be used for packaging. The beauty of metal recycling is that it can be recycled again and again without changing its properties. The most important metals which are used are (nonferrous) aluminum, tin, brass, copper and (ferrous) steel and iron. Sorting of metals during recycling becomes easier than that of plastic recycling as the magnetic properties can be checked.
The Process of Metal Recycling
The process of metal recycling is no different from the usual recycling procedure. The metals are sorted on the base of their properties. For example, if we would have to separate ferrous metals; then their magnetic proportion will help with separation. It is important that we should have basic knowledge about metals so that we can help in keeping the land green. The recycling process involves following steps:
1. Collection and sorting: The first step in metal recycling is the collection of all the materials which are made up of metals. There should be an organized system for the collection of metals. Containers should be used to collect them. For that there should be recycling centers in all big cities and there should be recycling bins at home and in the shopping malls that should be taken directly to industry.
The second important step is sorting the kind of metals which are good for recycling. The quality of metals matters a lot when it comes to recycling. A good recycled product can only be made if the original metals are of good quality. So leave nothing to check the quality of metal.
2. Processing: The next step is to compact the metal. All the appliances are squeezed and squashed in the machines so that they don’t occupy that much space in conveyor belts.
3. Shredding: After crushing and breaking the metals, shredding of metals takes place. They are broken down into small sheets or pieces so that they can be processed further with ease. The small size has large surface area and it can be melted with less energy required. Steel is usually changed into steel blocks or ingots while aluminum is processed into sheets.
4. Melting and Purification: The next step is to melt all this scrap metal in a large furnace. Each metal has a specially designed furnace depending on its properties. The melting utilizes a lot of energy in the form of fuel still the fuel required is less in this case as compared with the making from raw material.
Then after melting the metals are purified by using different methods. Electrolysis is also used for metal purification. These metal blocks are then transported to different mills for their remaking into other products. Recycling saves almost 75% of energy.
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auto-feeding system burning system, pyrolysis system, heavy and light oil separate system, cooling system, exhaust gas recycling system, dedusting system, auto slag discharging system ,and also to offer scrap shredder operators a set of resources that is unmatched by other suppliers of ferrous metal scrap and auto shredding equipment to make the right shredder facility to meet your needs and match your budget.
about Recycling
Saving of raw materials and energy by not having to first extract the iron from the ore. Avoiding the pollution problems in the extraction of iron from the ore. Not having to find space to dump the unwanted iron if it wasn't recycled.
(Offsetting these to a minor extent) Energy and pollution costs in collecting and transporting the recycled iron to the steel works
The supply and sale of machinery and equipment, and turnkey project setup recycling of metals., To achieve a green target., beautiful, And a healthy environment, perform duty CAIL towards nature.