Iron Nuggets

Iron Nuggets  The process of production of iron nuggets is capable of directly producing solid, high density, highly metalized iron nuggets from dry green balls. These green balls are made out of iron ore fines, pulverized coal, fluxes and binders. The pulverized coal is reductant which is added to the system to supply the carbon required for the reduction and carburization. Binder (bentonite) in conjunction with the finely ground iron ore particles serves to improve the properties of green balls in wet and dried conditions. The flux is limestone, which fluidizes the slag and also prevents excessive iron losses in the slag. The iron nuggets are produced using a direct reduction process. The reduction process is carried out in a rotary hearth furnace, using coal as the reductant and energy source. The direct reduction of iron by this process is more energy efficient and more environmentally friendly than traditional iron making processes. The process for producing iron nuggets by ITmk3 is described in the article having link http://ispatguru.com/itmk-3-process-of-making-iron-nuggets/ Iron nuggets are an ideal feed material for steelmaking and iron casting. This material consists of essentially all iron and carbon, with practically no gangue (slag) and low levels of metal residuals. Fig 1 shows sample of iron nuggets. Fig 1 Iron nuggets  Iron nuggets are a premium grade iron product with superior shipping and handling characteristics. They can be shipped in bulk either inland in railway wagons or trucks or in the ocean going vessels. Iron nuggets can be stored outside with no special precautions. They can be handled as a bulk commodity using conventional magnets, conveyors, bucket loaders, clams, and shovels. The physical properties of iron nuggets are as follows. Colour – Gray Shape and appearance – Pebble shaped elliptical structure Size – 5...

Stainless Steel Manufacturing Processes May04

Stainless Steel Manufacturing Processes...

Stainless Steel Manufacturing Processes Stainless steels contain from 10 % to 30 % chromium. These steels also contain varying amounts of nickel, molybdenum, copper, sulphur, titanium, and niobium etc. The majority of production of stainless steel was through the electric arc furnace (EAF) till around 1970. With the use of tonnage oxygen in steel production, the EAF stainless steel making practice changed. Oxygen gas could be used for improving the decarburization rate. This could be achieved by injecting high oxygen potential but it was accompanied by the adverse reaction of extensive oxidation of chromium to the slag. This necessitated a well defined reduction period in which ferro silicon was used to reduce the oxidized chromium from the slag. Production of stainless steel started by duplex process with the successful development of argon oxygen decarburization (AOD) converter process. Though duplex process with AOD converter is the prominent one, there are several duplex processes are being used today for making stainless steels. In these processes there is an EAF or similar furnace that melts down scrap, ferroalloys and other raw materials to produce the liquid steel. This liquid steel, which contains most of chromium and nickel as well as some other alloying elements, is the charge of the converters. The converters are used to achieve low carbon stainless steels. The versatility of the EAF-AOD duplex process led steelmakers to re-examine the use of different converters for melting of stainless steels. This led to the development of several other converters for duplex processes. The development work to make stainless steels using conventional BOF (basic oxygen furnace) had begun in the late 1950s and early 1960s. By the mid 1960s, some steelmakers were using existing BOF converters for a partial decarburization followed by decarburization in a ladle under...

CONARC Process for Steelmaking Apr17

CONARC Process for Steelmaking...

CONARC Process for Steelmaking CONARC process for steelmaking was developed by Mannesmann Demag Huettentechnik (now it is SMS Siemag). The objective for the development of this process was to utilize the benefits of both the conventional top blown converter steelmaking and electric arc furnace (EAF). The name of the process CONARC sums up the fusion of the two processes (CONverter ARCing). The technology of this process is based on the increased use of hot metal in the electric arc furnace and is aimed at optimizing energy recovery and maximizing productivity in such an operation. The process was developed for using any kind and mix of raw materials like hot metal, direct reduced iron (DRI) and scrap to ensure highest quality requirements for the production of all grades and qualities of steels covering a wide range from carbon steels to stainless steels. Depending upon the requirements of the finished products, CONARC process is followed by a ladle furnace or a vacuum degassing unit. Major equipment for the CONARC process The basic equipment of CONARC process consists of two identical refractory lined furnace shells, one slewable electrode structure with one set of electrodes serving both the furnace shells, one electric supply (transformer etc.) for both the shells, and one slewable water cooled top oxygen lance system serving both the shells. Alternatively two stationary top lances, one for each furnace shell for the blowing of oxygen can also be used. Option is available for introducing bottom stirring devices integrated to the bottom of each of the furnace shell. Options are also available to introduce burners and injectors systems in the shell for the injection of fuel, carbon and oxygen as per the process requirements. The other important systems include raw material and flux feeding systems and gas...

Direct Reduced Iron

Direct Reduced Iron Direct reduced iron (DRI) is also known as sponge iron. It is produced by the reduction of iron ore (in the form of lumps or pellets) by either non-coking coal or a reducing gas produced by reforming of natural gas. The reducing gas can also be produced by the gasification of coal. The reducing gas is normally a mixture. The majority gases in this mixture are hydrogen (H2) and carbon mono oxide (CO). These gases act as reducing agents. The reduction process is conducted at high temperature but substantially below the melting point of iron. Since the reduction reaction takes place in solid state, the lump or pellet retain their original shape, but are considerably lighter due to the removal of the oxygen from the ore. Hence the produced direct reduced iron has a highly porous structure. This porous structure gives DRI an appearance of a sponge and because of it, DRI is also known as sponge iron. Iron content in the DRI is in two forms. One is in metallic form which is known as metallic iron, Fe (M), and the second form is iron present in residual iron oxides, Fe (O). The total iron Fe (T) in DRI is the sum of these two iron components. Metallic iron is the aggregate quantity of iron, either free or combined with carbon (as cementite) present in DRI. Metallization of DRI is a measure of the conversion of iron oxides into metallic iron (either free or in combination with carbon as cementite) by removal of oxygen due to the action of the reductant used. Degree of metallization of DRI is the extent of conversion of iron oxide into metallic iron during reduction. It is defined in percentage of the mass of metallic iron divided by the mass of...

Discharge options for Direct Reduced Iron and its Hot Transport Dec14

Discharge options for Direct Reduced Iron and its Hot Transport...

Discharge options for Direct Reduced Iron and its Hot Transport The two main methods of producing direct reduced iron (DRI) are (i) gas based process in a vertical shaft furnace and (ii) coal based process in a rotary furnace.  In both the processes the reduction reactions take place in solid state and the maximum furnace temperatures are in the range of 850 deg C to 1050 deg C. In the coal based process, the produced DRI is mixed with char that is needed to be separated from DRI. Hence DRI-char mixture is cooled in a rotary cooler and then char is separated from DRI by the magnetic separation process. In the case of vertical shaft furnace processes, since char is not present along with DRI, there are three discharge options available. These are cold DRI (CDRI), hot briquetted iron (HBI), and hot DRI (HDRI). Most of the vertical shaft DRI furnaces have been built for the production of CDRI. In these furnaces the DRI produced after reduction is cooled in the lower part of the furnace to about 50 deg C. CDRI is temporarily stored in Silos for passivation before it is transported to a nearby steel melting shop for its use later. CDRI has got the property of auto ignition and need special precautions during transport and storages as required by the International Maritime Organization (IMO). CDRI is most suited material for the continuous charging in the EAF. HBI is now being produced since more than 30 years. It is the desirable method of preparing DRI for storage and transporting it by sea going vessels. For the production of HBI, hot DRI is discharged from the vertical shaft furnace at a temperature of around 700 deg C. The hot DRI is sent to...