Chemistry of the Ironmaking by Blast Furnace Process Nov22

Chemistry of the Ironmaking by Blast Furnace Process...

Chemistry of the Ironmaking by Blast Furnace Process Liquid iron (hot metal) is produced in a blast furnace from the burden materials through a series of chemical reactions which are taking place at various levels in a blast furnace. When the burden materials descend from the top through the blast furnace stack, they are preheated by the ascending hot gases. Due to this preheat, the coke burns with great intensity when it reaches the level   of the tuyeres and comes in contact with the hot blast air. However due to the very high temperature (1650 deg C) and the large quantity of carbon (coke), the carbon dioxide formed is not stable and reacts with additional carbon to carbon monoxide. Hence the combustion of carbon in the blast furnace can be represented by the following equation: 2C+O2= 2CO This reaction is the main source of heat for the smelting operation and also produces the reducing gas (CO) that ascends into the furnace stack where it preheats and reduces most of the iron oxide in the burden as it descend to the hearth. Any moisture present in the hot air blast also reacts with the carbon of the coke. This reaction consumes heat and produces more reducing gas which is a mixture of CO and H2. Hence where high blast temperatures are available (1000 deg C to 1200 deg C), it is advantageous to keep the moisture content of the hot air blast uniformly at a high level by the steam additions in order to increase the amount of reducing gases ascending the furnace stack. C+H2O=CO+H2 The advantage of above reaction is that there is the introduction of hydrogen gas in the furnace reducing gases which decreases of the density of the ascending gases. This results...

TMCP Steels

TMCP Steels TMCP stands for Thermo Mechanical Control Process and TMCP steels are those steels which are produced by this process. TMCP is a microstructural control technique combining controlled rolling (thermo mechanical rolling) and controlled cooling (accelerated cooling). These steels are sometimes microalloyed. Thermo mechanical control process is normally used to obtain excellent properties for steel plates such as high strength, excellent toughness along with excellent weldability through maximizing of grain refinement. These steels have almost same formability and weldability compared with mild steels. The superior mechanical properties introduced to the steel through this processing route are virtually equivalent to those obtained by heat treating conventionally rolled or forged steel and hence Thermo mechanical control process is used as a substitute for heat treatments that require additional material handling and furnace facilities. TMCP technology was developed early in 1980s and major Japanese plate rolling mills have started to produce TMCP steels by middle of 1980s. TMCP steels production When TMCP is chosen as the process route, the input material (i.e. the slab) is heated to a temperature regularly used for hot rolling operations (around 1200 deg C). The roughing operation during rolling in the rolling mill is carried out in a normal way, but the finish rolling is carried out at a lower temperature (around 750 deg C to 800 deg C) than the temperatures used in a normal rolling process. Plastic deformation at this lower temperature promotes fine grain sizes and retards precipitation. The final hot working may continue down to temperatures below the critical temperature of transformation from austenite to ferrite. This requires heavy rolling equipment capable of deforming the steel at low hot working temperatures. The optimum precipitate size and dispersion is obtained when the finish rolling temperature is around 775...

Occupational Health and Safety Management System...

Occupational Health and Safety Management System The importance of managing occupational health and safety in an organization on a sound footing is recognized by all interested parties such as employers, employees, customers, suppliers, insurers, shareholders, contractors, regulatory agencies and the wider community. There is a necessity for an organization to control and improve its occupational health and safety (OH&S) performance. Every organization needs to have sound health and safety policies and show a strong commitment for the health and safety of its employees. This can be achieved by establishing and implementing an occupational health and safety management system (OHSMS) within the organization. OHSMS is a network of inter related elements. These elements include responsibilities, authorities, relationships, functions, activities, processes, practices, procedures, and resources. These elements are used to establish OH&S policies, plans, programs, and objectives. OHSMS is a systematic and process driven approach for controlling and monitoring OH&S risks that can arise from an organization’s day to day activities. OHSMS also addresses to those OH&S risks which may be there due to the changing statutory provisions. The system helps the organization to be proactive rather than reactive, therefore helping the organization to improve its OH&S performance more effectively while protecting the health and welfare of the employees on an ongoing basis. There are the three basic aspects of OHSMS in an organization that are given below. For an effective OHSMS, it is vital for an organization to handle these basic aspects with significance since these three basic aspects provide the important foundation for the successful implementation of OHSMS. Hazard identification – It is the process of recognizing that a hazard exists. A hazard is a source or situation that has potential to cause harm in terms of human injury or ill health. Risk assessment – It is the process...

FASTMET and FASTMELT Processes of Ironmaking Nov15

FASTMET and FASTMELT Processes of Ironmaking...

FASTMET and FASTMELT Processes of Ironmaking Kobe Steel in collaboration with Midrex Technologies, Inc., a subsidiary of Kobe Steel in the USA, has developed the FASTMET process which is a coal based direct reduction process of iron making. The FASTMET process converts iron ore pellet feed, iron ore fines and/or metallurgical waste from the steel plant into direct reduced iron (DRI) using pulverized non coking coal as a reductant. The process uses a rotary hearth furnace (RHF) for the reduction reaction (Fig 1). The end product DRI can be hot briquetted (HBI), discharged as hot DRI into transfer containers, or cooled if cold DRI is needed. FASTMELT process is the FASTMET process with addition of an Electric Iron Melting Furnace (EIF) to produce liquid iron or hot metal. Hot DRI is directly discharged from the RHF into EIF and is melted to produce hot metal. Fig 2  A simplified cross section and plan view of a RHF The first commercial FASTMET plant was commissioned in April 2000 at Nippon Steel’s Hirohata works. A total of 5 plants have since been commissioned. The details of these plants are given in Table 1. Tab 1 FASTMET commercial plants Unit NSC Hirohata no. 1 NSC Hirohata no. 1 NSC Hirohata no. 1 JFE Fukuyama KSL Kakogawa RHF feed rate ton/Yr 190,000 190,000 190,000 190,000 16,000 Raw materials BOF dust BOF dust BOF dust BF dust, BOF dust BF dust, BOF dust, EAF dust Product application BOF feed, DRI BOF feed, DRI BOF feed, HBI BOF feed, DRI  BF & BOF feed, DRI It can be seen that this process is being presently used for utilization of the metallurgical waste of the steel plant. Besides metallurgical waste the process can also use iron ore fines having size which...

Microalloyed Steels

Microalloyed Steels Microalloyed steels are a type of alloy steels that contains small amounts of alloying elements (usually 0.05 % to 0.15 %). These steels are also sometimes called high strength low alloy (HSLA) steels. Though the work of strengthening steels through addition of small percentage of alloying elements started as early as 1916 in USA, the term ‘Microalloying’ (believed to be of Russian origin) was adopted by Prof. T. M. Noren-Brandel in 1962 and became pervasive as a result of the landmark conference ‘Microalloying 75’.  Strengthening by microalloying elements permits a dramatic reduction in carbon content which greatly improves weldability and notch toughness. Microalloyed steels have been developed originally for large diameter oil and gas pipelines. The technology of microalloying involves the addition of a fraction of a percent of the microalloying elements to simple low carbon mild steel. The use of ‘micro’ alloy concentrations, which produce remarkable changes in mechanical properties, distinguishes the technology from ‘alloying’ in the conventional sense (low alloy steels family) where concentration of the alloying elements may range from 0.25 % to one or two or possibly several percent. Microalloyed steels are designed to provide better mechanical properties and/or greater resistance to atmospheric corrosion than conventional carbon steels. They are not considered to be alloy steels in the normal sense because they are designed to meet specific mechanical properties rather than a chemical composition. Microalloyed steels are a family of steels that contain 0.07 % to 0.12 % carbon, upto 2 % manganese and are strengthened by the elements niobium, vanadium and titanium added either singly or in combination. These elements are sometimes used in conjunction with other strengtheners such as boron, molybdenum and chromium, nickel, copper and rare earth metals. The microalloying elements are used to refine...