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Chikhale M.,Iron Ore Business Unit | Tyagi K.,Iron Ore Business Unit | Kumar R.,Steel Authority of India Ltd SAIL
IMPC 2014 - 27th International Mineral Processing Congress

Ore characterisation including mineralogy and beneficiation testwork of an ore is very important for determination of possible products and their quality. The results of such study help in ascertaining the beneficiation process route for the ore. The present study deals with ore characterisation study and beneficiation testwork on the samples of hematite iron ore with goethite impurity. The characterisation study reveals that the hematite is under alteration stage to goethite which has become an integral part of hematite. High goethite/limonite content is enhancing the loss of ignition content of the ore and reducing its Fe content. The findings indicate that in case of hematite iron ore associated with goethite and limonite, it is difficult to achieve high grade of concentrate above 65% Fe. It depends on the amount of goethite and limonite minerals and their association with hematite. These minerals contain aluminous impurities and hence, their rejection becomes essential. Separation of limonite and of goethite to limited extent is possible. In case of goethite, effective liberation is not achieved where it occurs as surface alteration product of hematite grains. The gangue mineral reported are clay and gibbsite, and are closely associated with iron minerals. The test work results indicate the grade and recovery of Fe along with alumina and silica content in lumps, sinter fines and pellet feed fines that can be achieved for the different ore types vis-a-vis the percent of available hematite in the ore. The recovery of iron is dependent on the hematite available and the loss of iron values in tailings is more because of rejection of limonite and goethite. Source

Sahoo B.K.,Indian Institute of Technology Kharagpur | Sahoo B.K.,Steel Authority of India Ltd SAIL | De S.,Indian Institute of Technology Kharagpur | Meikap B.C.,Indian Institute of Technology Kharagpur | Meikap B.C.,University of KwaZulu - Natal
Journal of Industrial and Engineering Chemistry

The transporting of slurries in pipelines depends largely on rheological behavior of the solid-liquid suspension. These rheological properties of slurries are very much influenced by the slurry concentration, particle size distribution and, surface characteristics. The present invention is concerned with the effect of these parameters on slurry rheology using microwave (MW) energy. Microwave pre-treatment for rheological behaviour of iron ore-water slurries (IWS) were carried out in an online Bohlin viscometer. Detailed experimental work for Indian iron ore were conducted at power level of 900. W and 30, 60, 90 and 120. s various exposure times in microwave oven. The microwave treated and untreated test samples were ground for rheological characteristic of slurries. It was seen that microwave-treated ore have better rheological properties as compared to untreated ore. This type of slurry is shear thinning and easy to transport as it exhibited pseudo-plastic behavior. The result showed that microwave-treated iron ore have a density lower than that of untreated ore after grinding. Statistical design analysis was employed to develop empirical equations and found to be encouraging and highly considerable. © 2014 The Korean Society of Industrial and Engineering Chemistry. Source

Sarkar B.,Steel Authority of India Ltd SAIL | Jha B.K.,Steel Authority of India Ltd SAIL
Journal of Materials Engineering and Performance

An experimental steel of the composition (in wt.%) 0.04C-0.81Mn-0.38Si-0. 15Ti-0.01S-0.013P-0.043Al was hot rolled into 4 mm plates at three different temperatures of 1100, 1000, and 900 °C. The yield strengths of these plates were in the range of 434-484 MPa while the ultimate tensile strength varied from 508 to 586 MPa. Elongation values ranged from 13.0 to 17.8%. Hole expansion ratios (k) varied from 23 to 30.7%. In particular, the plate rolled at 1000 °C showed a yield strength of 484 MPa, an ultimate tensile strength of 586 MPa, a total elongation of ∼15%, and a hole expansion ratio of ∼23%. Transmission electron microscopy showed the presence of fine precipitates of titanium carbosulfide (∼10-50 nm). Therefore, maximum precipitation strengthening was obtained in the plate that was hot rolled into a thickness of 4 mm at 1000 °C. © 2011 ASM International. Source

Saxena A.,Steel Authority of India Ltd SAIL | Kumar S.,Steel Authority of India Ltd SAIL | Prakash K.,Steel Authority of India Ltd SAIL | Datta R.,R and C Laboratory | And 4 more authors.
Materials and Manufacturing Processes

API X-70 grade plates and hot strips microalloyed with Nb, V, and Ti have been developed simultaneously from two units of SAIL at Bhilai and Bokaro Steel Plants, respectively. Suitably designed steel (C: 0.1% max., Mn: 1.7% max., Nb: 0.06% max., V: 0.04% max., and Ti: 0.02% max.) was processed through vacuum arc degassing (VAD), and cast into 240mm thick slabs and hot rolled into 20mm thick plates, deploying an appropriate thermomechanical controlled processing (TMCP) technology. The tensile properties (YS: 473-531MPa, YS/UTS: 0.74-0.88, %El: 32-48%) and Charpy impact toughness properties (CIE: 113-159J at 0°C) were found to be quite attractive, owing to their fine microstructure of ferrite (∼10m) and low pearlite (volume fraction of ∼12%). In case of hot strips, the chemistry was suitably modified with leaner alloy chemistry (C: 0.08% max., Mn: 1.5% max., Nb: 0.06% max., V: 0.05% max., and Ti: 0.02% max.) and slabs were control rolled into 10/12mm thick strips followed by accelerated cooling prior to coiling. The mechanical properties of hot strips varied within a narrow range of YS: 535-557MPa, YS/UTS: 0.86-0.88, %El: 33-50%, and Charpy impact toughness property: 150-180J at 0°C showing appearance of finer ferrite grains: 8m. Examination of precipitates in both plates and hot strips revealed presence of fine NbV(CN) and complex M4C3 type coarse carbides. The mechanical properties of Electrical Resistance Welding (ERW) pipes manufactured using hot strips satisfied all specified requirements of American Petroleum Institute (API) norms. Both the products are now ready for their commercial exploitation. © Taylor & Francis Group, LLC. Source

Srikanth S.,Steel Authority of India Ltd SAIL | Saravanan P.,Steel Authority of India Ltd SAIL | Joseph A.,Indian Institute for Plasma Research | Ravi K.,Steel Authority of India Ltd SAIL
Journal of Materials Engineering and Performance

Plasma nitriding under glow discharge nitrogen plasma has been undertaken on laboratory scale for surface engineering of commercial low carbon steels. The treatment has been shown to confer exceptional improvement in surface properties, viz., hardness and corrosion resistance. The results have been discussed in light of microstructural changes occurring on steel surface and its interior as a result of Fickian nitrogen diffusion and correlated with influences of nitriding-temperature and alloying elements (Mn, Nb, and Si) in steel. © ASM International. Source

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