PLANTS & PROCESS
MS Agarwal Foundries Pvt. Ltd.
• Induction Furnace
• Billet Casting Process
• Rolling & TMT Process
• Cut & Bent Steel
Iron ore is reduced directly in solid state using coal as reductant and is known as Directly Reduced Iron (DRI) or Sponge Iron. Lime stone or Dolomite is used as desulphurising agent. Normal operating practice is to feed the kiln with desired proportion of iron oxide, coal and Dolomite. The charge is preheated and the reduction of iron ore is effected by reducing gases derived from coal gasification. The reduction is carried out in a rotary kiln (which is inclined and rotates at a predetermined range of speeds) at a stipulated temperature (850°C -1050°C). The inclination and the rotary motion of the kiln ensure that the raw materials move from the feed end to the discharge end of the kiln and during this movement the actual reduction of iron ore to iron takes place. The material discharged from the kiln is taken to a rotary cooler for cooling and the cooled product is separated from the coal char. Sponge Iron is substituting scrap with following advantages:-
1) Uniform Grain Composition & uniform Size & higher bulk density compared to scrape.
2) Low levels of residual elements
3) Capability to maintain undesirable impurities like Phosphorous & Sulphur levels much lower to the standards prescribed by the governing bodies.
4) Lower refining requirements of steel manufactured.
Sponge Iron / Direct Reduced Iron (DRI) is so named because iron ore reduced to metallic iron without melting first. It is basically a manufactured high ferrous content change material for iron and steel making. It is produced in lump or pellet form, compacted and briquette form known as hat Briquette Iron (HBI). It is the main substitute for steel form known as Hat Briquette Iron (HBI). It is the main substitute for steel scrap in steel making. Sponge iron production requires small quantity of energy, as no melting process is involved. The DRI assumed nick name Sponge Iron due to its appearance of sponge under microscope. The technology is available indigenously
The reduction process is carried out in a rotary kiln (which is inclined and rotates at a pre-determined range of speeds) at a stipulated temperature (850oC – 1050oC). The inclination & the rotary motion of the kiln ensure that the raw materials move from feed-end to the discharge-end of the kiln and it is during this movement that the actual reduction of iron ore to iron takes place. The material discharged from the kiln is taken to a rotary cooler for cooling and the cooled product, after being discharged from the cooler moves on to the next step in the production process viz. product separation and handling system.
For direct reduction of ore in the inclined rotary kiln, ore and coal normally pass through an inclined kiln in a counter current direction to the flue gases in the freeboard. The flat section, running nearly half the length of Kiln is called preheating Zone, where Iron Ore, Coal and Dolomite are heated up to reaction temperature. In this zone, moisture of the material is driven off. After material heating, ore reduction and carbon gasification takes place in close association with each other in the second half of the kiln, which is called reduction zone. The volatile constituents of the coal and carbon monoxide from the bed material are burnt, over the entire length of the kiln under controlled air supply, thereby providing necessary heat required for the metallization process. The basic reactions for the process are as follows:
The rotary kiln discharge is cooled in a rotary cooler connected to the kiln, screened and subjected to magnetic separation in order to remove the non magnetic material from the sponge iron, Schematic line diagram / outlay indicating various sections including the positions of Kiln & WHRB boilers is as under -
The overall process requires duration of approximately eight to ten hours inside the kiln, during which iron ore is optimally reduced and discharged to a rotary cooler for cooling below 120°C, before coming out into the finished product circuit, flowchart of the process is given below:
The greatest advantage of the Induction Furnace is its low capital cost compared with other types of Melting Units. Its installation is relatively easier and its operation simpler. Among other advantages, there is very little heat loss from the furnace as he bath is constantly covered and there is practically no noise during its operation. The molten metal in an Induction Furnace is circulated automatically by electromagnetic action so that when alloy additions are made, a homogeneous product is ensured in minimum time. The time between tap and charge, the charging time, power delays etc. are items of utmost importance are meeting the objective of maximum output in tones/hour at a low operational cost.
The molten steel from the IF or the ladle metallurgical facility is cast in a continuous casting machine (6/11 2 stand Billet Caster) to produce cast shapes including billets. In some processes, the cast shape is torch cut to length and transported hot to the hot rolling mill for further processing. Other steel mills have reheat furnaces. Steel billets are allowed to cool, and then be reheated in a furnace prior to rolling the billets into bars or other shapes.
1. The process is continuous because liquid steel is continuously poured into a 'bottomless' mould at the same rate as a continuous steel casting is extracted.
2. Before casting begins a dummy bar is used to close the bottom of the mould.
3. A ladle of molten steel is lifted above the casting machine and a hole in the bottom of the ladle is opened, allowing the liquid steel to pour into the mould to form the required shape.
4. As the steel's outer surface solidifies in the mould, the dummy bar is slowly withdrawn through the machine, pulling the steel with it.
5. Water sprays along the machine to cool/solidify the steel.
6. At the end of the machine, the steel is cut to the required length by gas torches.
The hot Billets are then subjected to rolling mill operations where with the help of different dies fitted at a number of passes, these are given desired shapes. The technology has been in use since many decades with ongoing modifications aimed towards higher efficiency and better quality.
Billets and Blooms from Own Induction Furnaces/LRF are the main Raw material for the Plant. The billets are carried in to the rolling Mill through Direct Hot Charging process.
In Roughing Mill, there are 2 Stands driven with the help of Electric Motor, Flywheel and Gear Boxes. Several passes are cut into the Rolls to reduce the material in size and shape. There are also two passes in Intermediate Mill and two passes in Continuous Mill. The cutting of passes in the rolls is very important and it varies with the size, shape and quality of the material to be rolled. PASS DESIGN in a Rolling Mill is very important aspect and experienced FOREMAN or ENGINEER is appointed to take care of it. The material (Billet/Bloom) fed into the bottom passes with the help of Main Roller Table and Turning walls and in the top they are fed with the help of Tilting Table. Approximately 4/6 passes have been provided in No. 1st Stand as per the size to be rolled. After that the material is transferred by sliding rails and Skew Rolls to 2nd Stand and 1 pass is provided in the 2nd Stand.
From Stand No. 2 the material is taken to 1st stand of Intermediate Mill via Roller Table and Y Table. Intermediate Mill has 2 Nos. Stands driven by Electric Motor. The 1st stand is opposite 2nd Stand of Roughing Mill. For top pass feeding `Y' Table is provided. Next the material is transferred to 2nd Stand of Intermediate Mill by sliding rails Skew Rolls. The material elongates each time it passes through the rolls and area reduction takes place. From Stand No. 2 of Intermediate Mill the material is taken to Continuous Mill No-1 via a Roller Table and then it’s going to Continuous Mill No-2 via a Roller Table. Final shape is given in this Stand and accurate adjustment is required. The material is fed into the mill with the help of roller table automatically and it acquires the desired shape and size and further travels to Cooling Bed via a Roller Table. The temperature at finishing stage is 800/1020 C approx. The rolls and guides and fiber bearings in the mill are cooled with the help of water recirculation.
Thermo Mechanical treatment process involves rapid quenching of hot bars through a series of water jets after the bars comes out of the last rolling mill stand. The short time in the water jacket provides intensive cooling of the surface layer, transforming it into a hardened structure. The bars are then cooled in the atmosphere, so that the temperature between the core which is still hot and th cooled surface layer, is equalized.
The Heat extracted form the core tempers the peripheral hardened structure while the rebar core cools down slowly to turn into a ferrite pearlite aggregate.
The strength of the bar is carefully controlled by optimizing the water pressure for their specific alloy chemistry and bar diameter.
The composite structure of the ductile ferrite pearlite core and the tough surface rim of tempered matensite provide an optimum combination of high strength, ductility and toughness.
The Cooling Bed is Duplex type and fabricated with structural material and in the center C.I. plates are provided with few individually driven rolls in between. After finishing pass the material comes to Cooling Bed via Roller Conveyor. Then it is shifted to one side of the Cooling Bed by Manual Shifting arrangement. When one side is filled up, the other side is used. The first side material is cleared while the other side is being used and vice a versa. The material is cleared via Roller Conveyor and cut into required specific length with the help of Shearing Press.
Inspection is done at every stage of Production by Quality Assurance Department. First, the Raw Material is checked, rolling temperature and finishing temperature is monitored and weight per meter of the rolled section is checked periodically. From the finished material, samples are taken for Physical and Chemical Testing in Laboratory. Care is taken so that sub-standard material is not supplied to customers. After the testing, material is kept ready for Dispatch.
After cutting the inspected material to specific length it is transferred to stockyard and staked properly with the help of crane. Wherever, straightening is required, it is taken to a straightening M/C, and straightened and then properly staked. From the stacked material samples are taken for quality checks and suitable grading is done, as per Indian Standards. The material is then ready for dispatch.
Cut & Bent Steel:-Time is Money and is precious. We value our client’s time and wanted to provide some innovative key to unlock cutting & bending time of steel and finally came out with a customized solution - cut & bent steel, which is tailor-made as per your blue print and can be directly used on site as it is a readymade smart steel.
The Re-Bar Cut & Bend Division produces steel reinforcement bars and stirrups in the required lengths and bent shapes, for use in reinforced concrete structures. The production process is automated through the use of specialized machinery to enable high volume production with minimum labor requirements. The advantages of using factory-cut and bent steel reinforcement bars and stirrups are realized in labor requirements, machinery requirements, waste steel, time, and quality consistency. There will be less manpower requirements on site; labor is only required for putting the steel in place. There will be no machinery requirement on site for cutting and bending of reinforcement steel. There will be less steel wastage since the cutting is taking place in a controlled factory environment where cutting patterns can be optimized. There will be significant time saved since the automated factory can cut and bend many steel bars in one go, and the automated cutting and bending activities themselves are much faster than the manual ones. Finally, since the cutting and bending is carried out on machines, the measurements and consistency in the bending of multiple bars and stirrups will be spot-on, which cannot be practically achieved in manual Process.
It is a customized steel as per project requirement, delivered at the construction site, according to cut and bend blueprints, in compliance with the client's working schedules and in individualized bundles. In order to deliver the service, we need to know the variety of diameters needed, duration of construction and total steel consumption.
Advantages of using MS Agarwal Foundries Innovative Smart Steel