15-12-2012, 12:02 PM
A PRACTICAL TRAINING REPORT On CHALIYAMA STEEL PLANT,CHAIBASA(JH)
CHALIYAMA STEEL PLANT.docx (Size: 1.03 MB / Downloads: 73)
About us
RUNGTA MINES LIMITED
Rungta Mines Ltd. (RML) the flagship company of S R Rungta Group, which has been in the mining business for the past 6 decades, was incorporated by Late Mr. S R Rungta in 1962, to support India's steel industry. Today, the group is headed by Mr. N.L. Rungta, (CMD), and has operations in the mineral rich belt of Bihar & Orissa and is involved in the mining of iron ore & manganese ore. The company's vision & mission is to utilise its core values & strengths, complemented with the vast experience gained, to help it keep pace with the changing times and respond to domestic & international market forces by maintaining consistent quality & despatch schedules, making RML synonymous with reliability.
RML's management is conscious about its social responsibilities & obligations towards its employees & the community at large by promoting education, family welfare, health care, recreation and a clean, pollution free environment.
The company's other activities include mining of limestone, dolomite, fireclay & bauxite, while associate companies are engaged in the field of real estate, construction & financing.
What is steel:-
Steel is an alloy made by combining iron and other elements, the most common of these being carbon. When carbon is used, its content in the steel is between 0.2% and 2.1% by weight, depending on the grade. Other alloying elements sometimes used are manganese, chromium, vanadium andtungsten.[1] 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 thehardness, 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 good castability.[1] 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 weldability.
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 inexpensivemass-produced material. Further refinements in the process, such as basic oxygen steelmaking (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.
BLAST FURNACE:-
A blast furnace is a type of metallurgical furnace used for smelting to produce industrial metals, generally iron.
In a blast furnace, fuel, ore, and flux (limestone) are continuously supplied through the top of the furnace, while air (sometimes with oxygenenrichment) is blown into the lower section of the furnace, so that the chemical reactions take place throughout the furnace as the material moves downward. The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top of the furnace. The downward flow of the ore and flux in contact with an upflow of hot, carbon monoxide-rich combustion gases is a countercurrent exchangeprocess.
Blast furnaces are to be contrasted with air furnaces (such as reverberatory furnaces), which were naturally aspirated, usually by the convection of hot gases in a chimney flue. According to this broad definition, bloomeries for iron, blowing houses for tin, and smelt mills for lead would be classified as blast furnaces. However, the term has usually been limited to those used for smelting iron ore to produce pig iron, an intermediate material used in the production of commercial iron and steel.
OTHER METHODS OF IRON REFINING
Although almost all the iron and steel manufactured in the world is made from pig iron produced by the blast-furnace process, other methods of iron refining are possible and have been practiced to a limited extent. One such method is the so-called direct method of making iron and steel from ore, without making pig iron. In this process iron ore and coke are mixed in a revolving kiln and heated to a temperature of about 950° C (about 1,740° F). Carbon monoxide is given off from the heated coke just as in the blast furnace and reduces the oxides of the ore to metallic iron. The secondary reactions that occur in a blast furnace, however, do not occur, and the kiln produces so-called sponge iron of much higher purity than pig iron. Virtually pure iron is also produced by means of electrolysis (see Electrochemistry), by passing an electric current through a solution of ferrous chloride. Neither the direct nor the electrolytic processes have yet achieved any great commercial significance.
BASIC OXYGEN PROCESS
The oldest process for making steel in large quantities, the Bessemer process, made use of a tall, pear-shaped furnace, called a Bessemer converter that could be tilted sideways for charging and pouring. Great quantities of air were blown through the molten metal; its oxygen united chemically with the impurities and carried them off.
In the basic oxygen process, steel is also refined in a pear-shaped furnace that tilts sideways for charging and pouring. Air, however, has been replaced by a high-pressure stream of nearly pure oxygen. After the furnace has been charged and turned upright, an oxygen lance is lowered into it. The water-cooled tip of the lance is usually about 2 m (about 6 ft.) above the charge although this distance can be varied according to requirements. Thousands of cubic meters of oxygen are blown into the furnace at supersonic speed. The oxygen combines with carbon and other unwanted elements and starts a high-temperature churning reaction that rapidly burns out impurities from the pig iron and converts it into steel. The refining process takes 50 min or less; approximately 275 metric tons of steel can be made in an hour.
A RED-INGOT
An ingot, red-hot and malleable from the high temperature of the soaking pit, is lifted out of the furnace for further processing. As the steel is worked and reheated, it becomes stronger.
The first pair of rollers through which the ingot passes is commonly called the blooming mill, and the square billets of steel that the ingot produces are known as blooms. From the blooming mill, the steel is passed on to roughing mills and finally to finishing mills that reduce it to the correct cross section. The rollers of mills used to produce railroad rails and such structural shapes as I-beams, H-beams, and angles are grooved to give the required shape.
Modern manufacturing requires a large amount of thin sheet steel. Continuous mills roll steel strips and sheets in widths of up to 2.4 m (8 ft.). Such mills process thin sheet steel rapidly, before it cools and becomes unworkable. A slab of hot steel over 11 cm (about 4.5 in) thick is fed through a series of rollers which reduce it progressively in thickness to 0.127 cm (0.05 in) and increase its length from 4 m (13 ft.) to 370 m (1,210 ft.). Continuous mills are equipped with a number of accessory devices including edging rollers, descaling devices, and devices for coiling the sheet automatically when it reaches the end of the mill. The edging rollers are sets of vertical rolls set opposite each other at either side of the sheet to ensure that the width of the sheet is maintained. Descaling apparatus removes the scale that forms on the surface of the sheet by knocking it off mechanically, loosening it by means of an air blast, or bending the sheet sharply at some point in its travel. The completed coils of sheet are dropped on a conveyor and carried away to be annealed and cut into individual sheets. A more efficient way to produce thin sheet steel is to feed thinner slabs through the rollers. Using conventional casting methods, ingots must still be passed through a blooming mill in order to produce slabs thin enough to enter a continuous mill.
TIN PLATE
By far the most important coated product of the steel mill is tin plate for the manufacture of containers. The “tin” can is actually more than 99 % steel. In some mills steel sheets that have been hot-rolled and then cold-rolled are coated by passing them through a bath of molten tin. The most common method of coating is by the electrolytic process. Sheet steel is slowly unrolled from its coil and passed through a chemical solution. Meanwhile, a current of electricity is passing through a piece of pure tin into the same solution, causing the tin to dissolve slowly and to be deposited on the steel. In electrolytic processing, less than half a kilogram of tin will coat more than 18.6 sq. m (more than 200 sq.ft.) of steel. For the product known as thin tin, sheet and strip are given a second cold rolling before being coated with tin, a treatment that makes the steel plate extra tough as well as extra thin. Cans made of thin tin are about as strong as ordinary tin cans, yet they contain less steel, with a resultant saving in weight and cost. Lightweight packaging containers are also being made of tin-plated steel foil that has been laminated to paper or cardboard.
Other processes of steel fabrication include forging, founding, and drawing the steel through dies
WROUGHT IRON
The process of making the tough, malleable alloy known as wrought iron differs markedly from other forms of steel making. Because this process, known as puddling, required a great deal of hand labour, production of wrought iron in tonnage quantities was impossible. The development of new processes using Bessemer converters and open-hearth furnaces allowed the production of larger quantities of wrought iron.
Wrought iron is no longer produced commercially, however, because it can be effectively replaced in nearly all applications by low-carbon steel, which is less expensive to produce and is typically of more uniform quality than wrought iron.
CLASSIFICATIONS OF STEEL
Steels are grouped into five main classifications.
Carbon Steels
More than 90 % of all steels are carbon steels. They contain varying amounts of carbon and not more than 1.65 % manganese, 0.60 % silicon, and 0.60 % copper. Machines, automobile bodies, most structural steel for buildings, ship hulls, bedsprings, and bobby pins are among the products made of carbon steels.
Alloy Steels
These steels have a specified composition, containing certain percentages of vanadium, molybdenum, or other elements, as well as larger amounts of manganese, silicon, and copper than do the regular carbon steels. Automobile gears and axles, roller skates, and carving knives are some of the many things that are made of alloy steels.