Romelt Process for Ironmaking Mar20

Romelt Process for Ironmaking...

Romelt Process for Ironmaking Romelt process for ironmaking is a smelting reduction process for the production of hot metal (liquid iron). The process has been developed by The National University of Science & Technology ‘MISiS’, Russia (formerly known as Moscow Institute of Steel and Alloys). The development work of the process started in 1978 when a group of ‘MISiS’ scientists led by Vladimir Roments began working on designing of this process. The first patent in Russia was obtained in 1979. A pilot production plant having a hearth area of 20 sq m and with a capacity 40,000 tons of hot metal per year was commissioned in 1985 at the Novolipetsk Iron and Steel Works (NLMK). The pilot plant was designed by Moscow Gipromez. The design of the reliable Vanyukov’s furnace was taken as the prototype for this new method of manufacturing hot metal. The process was tested and mastered at this pilot plant between 1985 and 1998. During this period forty-one campaigns were carried out, each of which included startup and slowdown, with full tapping of hot metal and slag from the furnace. More than 40,000 tons of hot metal was produced in the pilot plant during this period and used further in basic oxygen furnace (BOF) for steelmaking. The first industrial plant for hot metal production based on Romelt technology is being built at Myanmar. The plant has been designed by Leningrad Gipromez and being supplied by Tyazpromexport, a subsidiary of Rostec. This plant has a capacity of 200,000 tons per year and is based on the processing of iron ore without its beneficiation from Pang Pet ore deposit. Pang Pet ore deposits have Fe content of up to 29 %. The plant will use non-coking coal from Kye Thee coal fields. The...

Development of Smelting Reduction Processes for Ironmaking Mar08

Development of Smelting Reduction Processes for Ironmaking...

Development of Smelting Reduction Processes for Ironmaking Smelting reduction (SR) processes are the most recent development in the production technology of hot metal (liquid iron). These processes combine the gasification of non-coking coal with the melt reduction of iron ore. Energy intensity of SR processes is lower than that of blast furnace (BF), since the production of coke is not needed and the need for preparation of iron ore is also reduced. SR ironmaking process was conceived in the late 1930s. The history of the development of SR processes goes back to the 1950s. The laboratory scale fundamental studies on the SR of iron ore were started first by Dancy in 1951. However, serious efforts started from 1980 onwards. There have been two separate lines of development of primary ironmaking technology during the second half of twentieth century. The first line of development was centred on the BF which remained the principal process unit for the hot metal production. In general, this line of the development did not encompass any radical process changes in the furnace itself. It proceeded through a gradual evolution which involved (i) increase in the furnace size, (ii) improvement in the burden preparation, (iii) increase in the top pressure, (iv) increase of hot blast temperature, (v) bell-less charging and improvements in burden distribution, (vi) improvements in refractories and cooling systems, (vii) injection of auxiliary fuels (fuel gas, liquid fuel, or pulverized coal) and enrichment of hot air blast with oxygen (O2), and (viii) application of automation as well as improvements in instrumentation and control technology. The continued success of the ironmaking in BF reflects the very high levels of thermal and chemical efficiencies which can be achieved during the production of hot metal and the consequent cost advantages. In fact,...

Corex Process for Production of Iron Feb22

Corex Process for Production of Iron...

Corex Process for Production of Iron During the late twentieth century, several new initiatives have been taken for the development of the smelting reduction technology which can become alternative route for the production of liquid iron (hot metal) since the conventional blast furnace (BF) ironmaking depends on metallurgical coal, which is required for producing BF coke needed for the production of hot metal in the blast furnace. Metallurgical coal is not only costly but is associated with environmental issues during its conversion to BF coke in the coke oven batteries. Smelting reduction process is that process which is based on smelting reduction technology and hence in this process the production of hot metal is carried out without the use of metallurgical coke. Corex process is one of these initiatives. It is the first and the only commercially established smelting-reduction process based on non-coking coal which is available as an alternative route to the blast furnace for the production of hot metal. Corex process was developed by the Austrian technology supplier VOEST in the late 1970s, and its feasibility was confirmed during the 1980s. The first pilot plant was installed in Kehl, Germany, in 1981. Commercialization, however, was reached together with the South African steelmaker ISCOR where the C-1000 (C – 0.5 M) module was commissioned in November 1989 at its Pretoria works. This first generation reactor which is called melter-gasifier had a hearth diameter of 5.5 m and a hot metal production rate ranging from 40 tons per hour to 60 tons per hour. The plant rated capacity was 300,000 metric tons per year. The general applicability of this first generation process was limited and a lot of technical problems had to be solved. Nevertheless, it helped to overcome the critical demonstration stage for...

Coal based Direct Reduction Rotary Kiln Process Feb14

Coal based Direct Reduction Rotary Kiln Process...

Coal based Direct Reduction Rotary Kiln Process The coal based direct reduction rotary kiln process was developed for converting iron ore directly into metallic iron without the melting of the materials. The process has the advantage of low capital expenditure and no requirement of coking coal. The metallic iron in this process is produced by the reduction of iron oxide below the fusion temperature of iron ore (1535 deg C) by utilizing carbonaceous material present in the non-coking coal. As the iron ore is in direct contact with the reducing agent throughout the reduction process, it is often termed as direct reduced iron (DRI). The reduced product having high degree of metallization shows a ‘honeycomb structure’, due to which it is often called sponge iron. Coal based DRI plants are flexible with respect to plant location since non-coking coal is widely distributed in large deposits and is easy to transport. Most plants employ reduction process which is carried out in rotary kilns. These plants use wide variety of raw materials and non-coking coal. The quality of these materials has direct bearing on the process as well as the product. Some plants do not use iron ore directly. These plants use iron ore pellets in the rotary kiln. Raw material mix consisting of iron ore, dolomite and non-coking coal is fed at the one end of the rotary kiln and is heated by coal burners to produce DRI. The product DRI along with char (sometimes called dolo char) is taken out from the other end of the kiln. Apart from this, primary air and secondary air are supplied to the kiln to initiate the combustion and sustain the reaction process in the kiln. Raw materials The main raw materials for the production of DRI by...

Steel Scrap and Scrap Sorting and Preparation Processes Jan23

Steel Scrap and Scrap Sorting and Preparation Processes...

Steel Scrap and Scrap Sorting and Preparation Processes Recycling of steel scrap is receiving increased impetus these days due to the focus of an emerging environmental initiative since the increased consumption of scrap reduces the needs for additional resource extraction and hence reduces the environmental impact. Recycling of steel scrap is also a part of wise management of iron resources. Recovery of 1 metric ton of steel from scrap conserves iron ore, coal, and limestone.  As per the world steel association, the integrated steelmaking route, based on the blast furnace (BF) and basic oxygen furnace (BOF), uses 1,400 kg of iron ore, 800 kg of coal, 300 kg of limestone, and 120 kg of recycled steel to produce 1,000 kg of crude steel and the electric arc furnace (EAF) route on average uses 880 kg of recycled steel combined with varying amounts of other sources (DRI, hot metal, and granulated iron), 16 kg of coal and 64 kg of limestone, to produce 1,000 kg of crude steel.  On an average, recovery of 1 ton of steel from scrap conserves an estimated 1,030 kg of iron ore, 580 kg of coal, and 50 kg of limestone. Steel scrap recycling also saves the energy consumption.  In the production of steel, 99.9 % of scrap melted is consumed in the production of new steel while producing negligible environmentally undesirable waste. Steel scrap is classified in three main categories namely (i) home scrap, (ii) new scrap, and (iii) old scrap depending on when it becomes scrap in its life cycle. Home scrap is the internally generated scrap during the manufacturing of the new steel products in the steel plants. It is also known as runaround scrap and is the material in the form of trimmings or rejects generated...

Rolling of hot strip and strip defects Jan14

Rolling of hot strip and strip defects...

Rolling of hot strip and strip defects Rolling is one of the most important industrial metal forming operations. Hot Rolling is employed for rolling of steel slabs to hot strips in hot strip mills.  Like any other hot rolling operations, rolling of hot strip is also a plastic deformation of the material of the slab caused by compressive force applied through a set of rolls. The cross section of the slab is reduced by the hot rolling process. The material gets squeezed between a pair of rolls, as a result of which the thickness gets reduced and the length gets increased. Rolling of hot strip is done at high temperature because of requirement of large deformations. Hot rolling results in residual stress free strip. Normally, oxide scaling is accompanied with the hot rolling, due to which dimensional accuracy is inferior when compared with the dimensional accuracy of the cold rolled strips. For rolling of hot strip, the slabs are heated initially at 1100 deg C to 1300 deg C. The temperature in the last finishing stand of the hot strip mill varies from 700 deg C to 900 deg C. It is always to be above the upper critical temperature to produce uniform equiaxed ferrite grains. The objective during the rolling of hot strip is to decrease the thickness of the slab with an increase in the length and with very little increase in the width. The material in the centre of the strip is constrained in the direction across the width of the strip and the constraints of undeformed shoulders of material on each side of the rolls prevent extension of the strip in the direction of the width. This condition is known as plane strain. The material therefore gets longer and not...