NATIONAL TMT 500/500D
Higher Bond Strength: NATIONAL TMT incorporates ribs that are cut by the Automatic Rib cutting Machines producing uniform ribs. This results into the bars that have an excellent bonding with the concrete.
Superior Weldability: Lower carbon content in the NATIONAL TMT ensures better weldability than the conventional cold twisted bar.
Bending: The tough outer surface and soft core of the NATIONAL TMT, results in rebar with excellent bendability. The bar can be bent around the mandrels that are much smaller than those specified in IS 1786. This results in an enhanced speed at the sites.
Higher Corrosion Resistance Properties: NATIONAL TMT is being produced through TMT Tempcore (crm Belgium) Process, therefore there are no torsional residual stresses in the bars. This results into a superior corrosion resistance characteristic.
Close Dimensional Tolerance: NATIONAL TMT comes with an optimum section weight that is lower than the nominal. Superior Seismic Resistance Characteristics: Concrete beams, columns, and joints reinforced with the NATIONAL TMT are subjected to a repeated reverse loading in elastic strains to evaluate the performance, thus they simulate conditions that are similar to an earthquake. The bars in these tests have been proven for maintaining uniformity and ductility till failure.
SPONGE IRON/MS.BILLET
Captive Power plant
-captive power plant (cpp) will be 30*2 MW at generator terminals.
-Combined capacity (WHRB) Waste Heat Recovery Boiler40 TPH.-01NO. 10 TPH.
-02NOs Fluidized bed PF Boiler of 90*2 TPH
-Water consumption estimated 20MCUB./ Hr.
-Air cooled heat exchanger.
-Flue Gas Cleaning System with Inbuilt on line monitoring Instruments as per norms of the Pollution Board e.g. N2-ppm, CO2-ppm,O2-ppm,S-ppm,CO-%.
-Compressed air system300nm cub./Hr.
-Operating Logic of DCS-Yecocava3000 control.
-Protection Systems Numerical/ Microprocessor type.
SPONGE IRON PLANT
-Rotary Kiln 100TPD. 2Nos. -length of Kiln 52 meters, dia 3mtr. And rotation0.7/minut.
-length of Kiln cooler22x3 mtrs.
-Rotary Kiln 350TPD. 1Nos.
-length of Kiln 72 mtr., dia 4mtr. And rotation0.7/minut
-length of Kiln cooler52x4 mtrs
-Typical analysis of sponge iron produced in coal based process is given below.
Total iron Fe (T) 91 – 93%, Metallic iron Fe (m) 80 – 84%,
Metallization (Mtz) 90–92%, Gangue 3 – 4% Carbon(C)0.25%,Sulphur(S)0.02-0.04%, Phosphorous(P)0.035 - 0.05%
IMPORTANT FEATURES OF SPONGE IRON
The coal based rotary kiln process of making sponge iron is the focus of the present write up. Although many different processes and process concepts have been emerging in this area, there were rapid births and deaths of these processes and process concepts in the middle of the twentieth century. But those operating successfully at present have many features in common. Some of the common or slightly differing features are:
(i) System of sealing to prevent air ingress into the reactor,
(ii) System of throwing or slinging coal from the discharge end of the reactor,
(iii) System of weigh feeding and proportioning of raw materials
(iv) System of introducing a controlled amount of air at regular intervals of length in such a way that it does not oxidize the reduced product in the bed,
(v) System of temperature sensing at regular intervals of the length of the reactor and recording of the same.
(vi) System of indirect cooling of sponge iron-char mixture in a rotary steel cylindrical shell using water from the outside.
(vii) System of treating waste gases and maintaining desired flow profile through pressure control.
Brief on the sponge Iron process
In coal based process of making sponge iron, non–coking coal is used as reducing agent along with lumpy rich grade iron ore and the reduction is carried–out in an inclined horizontal rotary kiln that rotates at a predetermined speed. A temperature profile ranging from 800 to 1050 deg centigrade is maintained along the length of the kiln at different zones and as the material flows down due to gravity the ore is reduced. The hot reduced sponge iron along with semi burnt coal, discharged from the kiln is cooled in water–cooled cylindrical rotary cooler to a temperature of 100–200 deg centigrade. The discharge from the cooler consisting of sponge iron, char other contaminations are passed on through magnetic separators. sponge iron being metallic is not attracted by magnets. With this principle, sponge iron is separated. Letter the sponge iron is screened into two size fractions i.e –3 mm. while + 3 mm fraction directly goes for usage, -3 mm fraction is either can be used directly where ever it is possible or is to be briquetted by using molasses and hydrated lime as binders.
The main reactions in this process are as follows :
Fe2 O3 + CO = Fe3O4 + CO2
Fe3 O4 + CO = FeO + CO2
FeO + CO = Fe + CO2
Other reactions for reduction:-
C + O2 = CO2
CO2 + C = 2CO
RAW MATERIAL
As is typical in any metallurgical process, sponge iron manufacturing is highly sensitive to raw material characteristics that would help obtain the rated capacity and the desired product quality. Hence, it is essential to examine the chemical and physical characteristics of raw materials, both individually and in combination. The basic raw materials for the production of sponge iron are Iron ore, non-coking coal and dolomite. Several tests are conducted in the company laboratory to ascertain their suitability in a rotary kiln.A state-of-the-art modern R&D facility has been established along with a chemical laboratory to conduct the monitoring process.
Dolomite is an important ingredient and acts as a desulphuriser removing sulphur from the feed mix during the reduction process.It is mixed in small proportions along with other raw materials before charging into the kiln.Control of sulphur content is an essential pre-requisite for the manufacture of good quality steel.
NATIONAL CRS FE 500/FE 500D
Longer life due to higher corrosion resistance Can be bent and re-bent around very small mandrels Yield strength coupled with good ductility and bendability Suitable for application in highly corrosive/marine environment Seismic Resistance.
