Production of Ferro-Chrome Jul10

Production of Ferro-Chrome...

Production of Ferro-Chrome Ferro-chrome (Fe-Cr) is an alloy comprised of iron (Fe) and chromium (Cr) used primarily in the production of stainless steel. The ratio in which the two metals (Fe and Cr) are combined can vary, with the proportion of Cr ranging between 50 % and 70 %. Fe-Cr is frequently classified by the ratio of Cr to carbon (C) it contains. The vast majority of Fe-Cr produced is the ‘charge chrome’. It has a lower Cr to C ratio and is most commonly produced for use in stainless steel production. The second largest produced Fe-Cr ferro-alloy is the ‘high carbon Fe-Cr (HC Fe-Cr) which has a higher content of Cr and is being produced from higher grade chromite ore. Other grades of Fe-Cr are ‘medium carbon Fe-Cr’ (MC Fe-Cr) and ‘low carbon Fe-C (LC Fe-Cr). MC Fe-Cr is also known as intermediate carbon Fe-Cr and can contain upto 4 % of carbon. LC Fe-Cr typically has the Cr content of minimum 60 % with C content ranging from 0.03 % to 0.15 %.  However C content in LC Fe-Cr can be upto 1 %. Ferro-chrome (Fe-Cr) alloy is essential for the production of stainless steel and special steels which are widely used and are of high quality, typically characterized by a high corrosion resistance and a low tendency to magnetization. The processing cycle of Fe-Cr involves the chemical reduction of the chromite ore. Smelting of HC Fe-Cr ferro-alloy HC Fe-Cr and charge chrome are normally produced by the conventional smelting process utilizing carbo-thermic reduction of chromite ore (consisting oxides of Cr and Fe) using an electric submerged arc furnace (SAF) or a DC (direct current) open arc electric furnace. In SAF, the energy to the furnace is predominantly supplied in a resistive...

Production of Ferro-Silicon Jun27

Production of Ferro-Silicon...

Production of Ferro-Silicon Ferro-silicon (Fe-Si) is a ferro-alloy having iron (Fe) and silicon (Si) as its main elements. The ferro-alloy normally contains Si in the range of 15 % to 90 %. The usual Si contents in the Fe-Si available in the market are 15 %, 45 %, 65 %, 75 %, and 90 %. The remainder is Fe, with around 2 % of other elements like aluminum (Al) and calcium (Ca). Fe-Si is produced industrially by carbo-thermic reduction of silicon dioxide (SiO2) with carbon (C) in the presence of iron ore, scrap iron, mill scale, or other source of iron. The smelting of Fe-Si is a continuous process carried out in the electric submerged arc furnace (SAF) with the self-baking electrodes. Fe-Si (typical qualities 65%, 75% and 90% silicon) is mainly used during steelmaking and in foundries for the production of C steels, stainless steels as a deoxidizing agent and for the alloying of steel and cast iron. It is also used for the production of silicon steel also called electrical steel. During the production of cast iron, Fe-Si is also used for inoculation of the iron to accelerate graphitization. In arc welding Fe-Si can be found in some electrode coatings. The ideal reduction reaction during the production of Fe-Si silicon is SiO2+2C=Si+2CO. However the real reaction is quite complex due to the different temperature zones inside the SAF. The gas in the hottest zone has a high content of silicon mono oxide (SiO) which is required to be recovered in the outer charge layers if the recovery of Si is to be high. The recovery reactions occur in the outer charge layers where they heat the charge to a very high temperature. The outlet gas form the furnace contains SiO2 which can...

Production of Ferro- Manganese Jun19

Production of Ferro- Manganese...

Production of Ferro- Manganese Ferro-manganese (Fe-Mn) is an important additive used as a deoxidizer in the production of steel. It is a master alloy of iron (Fe) and manganese (Mn) with a minimum Mn content of 65 %, and maximum Mn content of 95 %. It is produced by heating a mixture of the oxides of Mn (MnO2) and iron (Fe2O3) with carbon (C) normally as coke or coal. Fe-Mn in a blast furnace (BF) with considerably higher Mn content than was possible earlier was first produced in 1872 by Lambert Von Pantz. The Fe-Mn produced had 37 % Mn instead of 12 % being obtained earlier. Metallurgical grade Mn ores having Mn content higher than 40 % are usually processed into suitable metallic ferro- alloy forms by pyro-metallurgical processes, which are very similar to the iron pyro-metallurgical processes. In its production process, a mixture of Mn ore, reductant (a form of C) and flux (CaO) are smelted at a temperature which is higher than 1200 deg C to enable reduction reactions and alloy formation. Standard grades of Fe-Mn can be produced either in a BF or in an electric submerged arc furnace (SAF). The electric SAF process, however, is far more flexible than the BF process, in that slags can be further processed to Si-Mn and refined Fe-Mn. The choice of process is also dependent on the relative price of electric power and coke. In a three-phase SAF, the electrodes are buried in the charge material. The raw materials are heated and the Mn oxides pre-reduced by hot carbon mono oxide (CO) gas form the reaction zones deeper in the furnace. The exothermic reactions contribute favourably to the heat required. Efficient production of HC Fe-Mn depends on the degree of pre-reduction which occurs...

Redsmelt process for ironmaking Apr19

Redsmelt process for ironmaking...

Redsmelt process for ironmaking Redsmelt is a new ironmaking process based a two reduction steps. These are (i) pre-reduction of iron bearing materials in a rotary hearth furnace (RHF), and (ii) smelting of the hot pre-reduced iron (DRI, direct reduced iron). Originally a submerged arc furnace (SAF) has been used for the second step. SAF has now been replaced by a coal and oxygen blown converter (oxy-coal reactor) known as ‘New Smelting Technology’ (NST). The RHF reduces green pellets made out of iron ore, reductant fines and binders to produce hot, metallized DRI which is charged to the NST for its smelting to hot metal. Redsmelt process has been conceived to be consisting of a cost-effective and environmental-friendly technology. The important highlights of the process are as follows. The process does not need any prepared charge materials The process does not need electrical energy, since the DRI smelting is carried out using chemical energy The smelter is having high productivity resulting into limited investment cost The process can use practically all the residues generated during various processes of the steel plant (including sludges and oily mill scales), thus it solves the increasing issue of steel wastes treatment The off-gas coming from the smelting reactor is used as a fuel in the RHF, with optimization of the overall energy utilization. This results into effective reduction in energy consumption A Redsmelt demonstration plant with two step smelting reduction process was built and tested in Piombino works (Italy) for the production of hot metal. The demonstration plant was commissioned in the year 2003. The two production steps in the demonstration plant have been based upon pre-reduction of iron-bearing materials in a RHF and smelting of the hot DRI in an oxy-coal converter. The plant has been designed...

Submerged Arc Furnaces Jul15

Submerged Arc Furnaces...

Submerged Arc Furnaces  industrial utilization of electrical energy started with the development of the dynamo machine by Werner von Siemens. Electric arc furnaces have been used for many years both for the melting of scrap iron (open arc furnaces) and for reduction processes (submerged arc furnaces). In case of the submerged arc furnace (SAF), ore and reducing agent are fed to the furnace continuously from the top so that the electrodes are buried in the mix and the arc is submerged. The furnace is named submerged-arc furnace since the arc is submerged. The most common physical arrangement consists of a circular bath with three vertical electrodes arranged in a triangle. Six electrode furnaces with circular or rectangular baths are also used but they are less common. Submerged arc furnaces have found their application in more than 20 different main industrial areas such as ferro alloy, chemical industry, lead, zinc, copper, refractory, titanium oxide, recycling, phosphorus etc. A typical schematic diagram of a submerged arc furnace for ferro chrome production along with material balance is given at Fig.1 Fig 1 Typical schematic diagram of a submerged arc furnace for ferro chrome production along with material balance.  History  The increasing demand for ferro alloys and deoxidation agents in steel making in the beginning of the twentieth century led to the development of the first submerged arc furnace. The construction of the first SAF was started in 1905. This 1.5 MVA unit was installed in Horst Ruhr, Essen, Germany for the production of calcium carbide. It was successfully commissioned in 1906 and was based on DC (direct current) technology. Since then a large number of SAFs (both with DC and AC based furnaces) have been commissioned with diverse applications. Today, the majority of submerged arc furnaces are...