Cleaning of Blast Furnace Gas Jan22

Cleaning of Blast Furnace Gas...

Cleaning of Blast Furnace Gas The process of liquid iron production in the blast furnace (BF) generates gas at the furnace top which is an important by-product of the BF process. This top gas of the blast furnace is at the temperature and pressure existing at the BF top and usually contaminated with dust and water particles. This top gas is having substantial calorific value and is known as raw BF gas or contaminated BF gas. The composition and quantity of this top gas depend on the nature of the technological process in the blast furnace and the type and the quality of the raw materials used for the iron production in the blast furnace. In order to further use the raw BF gas, it is necessary to clean it by using certain process systems which reduces its content of the solid particles. The top gas contains carbon mono oxide (CO) and is known as blast furnace gas after its cleaning. It is used as fuel gas for heating blast air in the hot blast stoves as well as supplemental fuel in the steel plant. For the BF gas to be used as fuel gas, it is necessary that the raw BF gas is cleaned and cooled to reduce gas volumes and moisture content. Prior cooling and reduction in gas volume is also necessary since it results in substantial savings in delivery costs throughout the extensive distribution system of the steel plant. Typical analysis of the blast furnace gas for a blast furnace operating with pulverized coal injection (PCI) is given in Tab 1. The process systems for the gas cleaning are either wet gas cleaning system or dry cleaning system. High-efficiency gas cleaning systems are vital for the reliable operation and long campaign...

Cast irons and their Classification...

Cast irons and their Classification  The term ‘cast iron’ represents a large family of ferrous alloys. Cast irons are multi-component ferrous alloys, which solidify with a eutectic. The major elements of cast irons are iron, carbon (2 % or more), silicon (1 % to 3 %), minor elements (less than 0.1 %), and often alloying elements (less than 0.1%). Cast iron has higher carbon and silicon contents than steel. The structure of cast iron displays a richer carbon phase than that of steel because of its higher carbon content. Cast iron can solidify according to the thermodynamically metastable Fe-Fe3C (iron carbide) system or the stable iron-graphite system depending principally on composition, cooling rate, and melt treatment. Cast iron in its basic form is a brittle material which has a very little impact strength. It has a little or practically no toughness when compared to low carbon steels.  It has a fraction of the tensile strength of low carbon steels.  When a cast iron piece fails it does not deform in a noticeable way and appears to snap apart or break in a manner consistent with a snap.  There is no early warning of a failure. The graphite phase which is pure carbon acts as a natural defect in the material.  The iron is so saturated with carbon that graphite forms (free carbon) and causes the cast iron to be weaker.  Much smaller amounts of carbon is combined with iron (Fe) in the form of iron carbide (Fe3C, cementite) which is hard and brittle. During the solidification process, when the metastable route is followed, the rich carbon phase in the eutectic is the iron carbide and when the stable solidification route is followed, the rich carbon phase is graphite. Referring only to the binary Fe-Fe3C or...

Managing the Safety and Health at Workplace...

Managing the Safety and Health at Workplace  An organization’s performance depends on the performance of its employees and the employees’ performance show vast improvement if the work is carried out by them in a workplace which is safe and has a healthy environment. Safe and healthy workplaces are always the most efficient. In fact the two go hand in hand. Also, a bad accident due to the lack of safety and healthy environment at the workplace can bring a serious damage to the organization. Safety and health at the workplace is part of the organizational management, just like production and quality. Safety and health affects production, quality, and the financial results. So it is required to be managed in the same way as other aspects such as product development, distribution, marketing, sales targets or any other management issue in the organization. It is important that management plans for it, invests in it, manages it and regulates it. In short, safety and health at workplace is an intrinsic part of the organizational management. Safety and health at the workplace is essential for preventing injury and illness to the employees at the workplace. Therefore, it is about protecting the organization’s most valuable asset which is its workers. By making available safe and healthy working environment at the workplace, the organization reduces the lost work hours and hence the cost which is associated with it. It also eliminates the interruption to the operations with resultant increase in productivity and quality. A safe and healthy workplace raises employees’ morale and thus is one of the keys to organizational success. Safe and healthy workplaces have more satisfied and productive employees (i) who produce higher quality products or/and services, (ii) return to work more quickly after an injury or illness,...

Evolution of Blast Furnace Iron Making Jan10

Evolution of Blast Furnace Iron Making...

Evolution of Blast Furnace Iron Making The origin of the first smelting of iron is concealed in the unrecorded history of human civilization. The first evidence of iron implements being used in ancient times actually comes from Egypt where an iron tool was found in a joint between two stones in a pyramid. The origin of many prehistoric iron implements was probably meteoric iron. Meteoric iron contains 5 % to 26 % nickel (Ni) while smelted iron contains only traces of Ni and hence iron artifacts made from meteors can be differentiated from objects of smelted iron. More than 4,000 years ago, people discovered meteoric iron. But it was another 2,000 years before the production of iron from mined iron ore began. The earliest finds of smelted iron in India date back to 1800 BCE (Before Common Era).  The smelting of iron is said to have taken place among the Calybes of Armenia, subjects of the Hittite Empire, at about 1500 BCE. When their empire collapsed around 1200 BCE, the various tribes took the knowledge of iron making with them, spreading it across Europe and Asia. The knowledge of ironworking in all of Europe and Western Asia is ultimately traced to this source. The Iron Age began with the discovery of smelting of iron. Beginning of iron smelting As with the reduction of cop­per sulfide ores, the first reduction of iron oxide was probably accidental. It was the powers of observation that led these ancient metallurgists (who were the miners, chemists, and technologists of their day) to realize that iron could be produced in simple furnaces by direct carbon (C) reduction of the oxide ore. The first recorded depiction of a smelting process was found on the wall of an Egyptian tomb dating to...