SMELTING

As ores move through the submerged arc furnace during processing it passes through a number of reaction zones.

In the upper furnace zone the particulates are present as “loose charge” and product gas from the lower furnace consisting of principally CO and CO2 passes through this packed bed. Reactions between the gases and the solid ores result in the partial reduction of the ores and the formation of iron and alloy, and in some cases metal carbides resulting Decomposition of limestone fluxes e.g. CaCO3, and other minerals, Gasification of carbon; reaction with air and CO2, Gaseous reduction of ores and partial metallization of iron and oxides.

In the lower furnace zones, a series of reaction steps take place involving the slag phase; Dissolution of ores spinel in slag, Reduction of the slag phase to form alloy, Alloy/slag separation.

Although the overall reaction is described by the removal of oxygen by solid carbon, this reaction can take place through a number of pathways involving; carbon monoxide formation from solid carbon or carbon dissolved in alloy; reaction of CO gas with slag; metal on diffusion in the slag phase.

Each of these mechanisms contributes to the overall recovery of desired alloy. Optimization of the process to enhance the rates and extent to which these reactions proceed, and to maximize recovery. Production rate and energy efficiency is assisted by improved understanding of the various reactions and reaction mechanisms operative in the process, and by taking action through feed selection and preparation, and adjustment of process conditions.
Mughal Iron and Steel Industries Limited (MISIL) utilizes the renowned MCC-SERIES (one of the largest equipment manufacturers in China) for smelting process. Chorme One, Manganese One and Silica Manganese are used as raw materials to produce Ferro Chrome, Ferro Manganese, Ferro Silicomanganese and Ferro Silicon at Shalimar Steel.

Manganese alloys are mostly used in steelmaking and foundry activities. Some 30 % of the manganese used today in steelmaking is still used for its properties as a deoxidant and a sulphide former. In this last case it combines with sulphur avoiding the formation of iron sulphides, which sulphides are low melting point phases which become liquid at hot rolling temperatures and which, consequently, generate surface cracking. The other 70% of the manganese is used purely as an alloying element. Steels usually contain from 0,2% to 2% manganese depending on grades as manganese is the cheapest alloying element among those which enhance some key mechanical properties like strength and toughness. In the specific case of stainless steel it can substitute expensive nickel in some austenitic grades called 200 series.
There are two families of manganese alloys called ferro-manganese (FeMn) and silico-manganese (SiMn). Silicomanganese adds additional silicon which is a stronger deoxidant. Nitrogen, boron, titanium, phosphorus are elements which can be controlled depending on requested specification. A very specific application of refined manganese alloys is a constituent in the coating of welding electrodes.

Ferro-Chrome is an alloy of chromium and iron containing between 50% and 70% chromium. The ferrochrome is produced by electric arc melting of chromite and chromium ore. The production of steel is the largest consumer of Ferro Chrome, especially the production of stainless steel with a chromium content of between 10 and 20%. Ferro-Chrome with chrome content below 56% is known as ‘charge chrome’ and produced from a chrome containing ore with a lower chrome content.
Alternatively, High Carbon Ferro-Chrome produced from higher grade ore, is more commonly used in specialist applications such as engineering steels where a high Cr to Fe ratio and minimum levels of other elements such as sulfur, phosphorus and titanium are important

Ferro Silicon is an atomised alloy, which is formed by combining iron and silicon with a silicon content range of 15% to 90%. Ferro Silicon is a universal “heat-blocker” used in the production of carbon and stainlesssteels. This additive is used with other ferro alloys in the deoxidising process of steel, as well as in the production of silicon itself. Ferro Silicon is used in the production of cast iron, as Ferro Silicon can accelerate graphitisation. Ferro Silicon replaces the need for ferro manganese, spiegeleisen and calcium silicides in the manufacturing process.
Ferro Silicon, as an additive to the production process of ferrous metals, will impart several desirable properties upon the resultant alloy. Some of the primary benefits of adding Ferro Silicon to an alloy is to improve the corrosion resistant properties of the new compound, as well as to add to the high temperature heat-resistance properties of the new alloy, for example, in the production of silicon steel for use in transformer cores.