Blast Furnace Tap Hole and Tapping of the Furnace Apr23

Blast Furnace Tap Hole and Tapping of the Furnace...

Blast Furnace Tap Hole and Tapping of the Furnace The operation of a blast furnace is a continuous process. The blast furnace continues to produce liquid iron (hot metal) and slag as long as it is in operation. The hot metal and slag accumulate in the hearth of the furnace, but since there is a limit to the amount that can be accumulated before it interferes with the furnace operation, hot metal and slag must be removed from the furnace at regular intervals. The tap hole also known as iron notch, is used for tapping the hot metal from the furnace. It is located slightly above the floor of the hearth. Regardless of the specific tap hole configuration or operating philosophy, due to the addition of dynamic (often periodic) and more intense process conditions (exposure to higher temperatures leading to accelerated corrosion,  greater turbulence, and elevated rates of mass and heat transfer), and higher concurrent thermo-mechanical forces (from thermal or flow shear stresses), the performance and longevity of the blast furnace is intimately linked to the performance of the tap hole. Hence tap hole is very critical to the blast furnace. It is the heart and the lifeline of the blast furnace since without a tap hole a blast furnace cannot exist. The criticality and relevance of tap hole continues even in the modern automated blast furnaces. Tap hole is an essential part of a blast furnace. Large furnaces usually have 2 to 4 tap holes and the drainage of hot metal and slag is practically continuous by periodically drilling and plugging the tap holes with one of the tap holes is always open and two alternate tapings usually overlap for some period of time. Medium or small sized blast furnaces have normally one...

Blast Furnace Tap Hole Mass...

Blast Furnace Tap Hole Mass Blast furnace tap hole mass is a prepared ready to use refractory product, made of a bond of aggregates, additives, and plasticizers. It is used to close the tap hole of a blast furnace after tapping so that no material can leak out, and to keep it plugged until the tap hole is opened for next tapping. It is applied to ensure periodical and stable tapping from the blast furnace and also to protect the inner surface of tap hole bricks. Its functions are (i) to enable smooth operation of the tap hole, (ii) to maintain constant tap hole length,  (iii) to control the liquid flow out of the blast furnace, and (iv) to ensure separation of hot metal and slag. Blast furnace tap hole mass is normally developed and designed to suit the operating parameters of the blast furnace and to maintain stable tapping time and tap hole depth even under severe operational conditions with high productivity coefficients (ton/cu m/day) or high hot metal temperatures. Requirements of blast furnace tap hole mass Typical requirements from the blast furnace tap hole mass include the following. It should be soft and plastic (workable) enough to inject when pushed by mud gun, but ‘hard’ enough to effectively displace tapping liquid and to deliver a substantial quantity of tap hole mass only to plug to the required depth in the tapping channel. It should be curing to the required strength (often described as sinterability) and without shrinkage to ensure a tight seal within the tap hole (not prematurely in the mud gun), in the required mud gun dwell time and plug to next tap time. It should effect safe tap hole closure (i.e., without subsequently self opening) and without tap hole and...

Safety Awareness and Safety Training in Steel Industry...

Safety Awareness and Safety Training in Steel Industry A safe working environment for all the employees and an accident free working place is the top most priority for the management of an iron and steel plant. Historically, iron and steel making consisted of dangerous processes and accidents were always considered inevitable. Today, many steel organizations in the world recognize that this is no longer an appropriate statement for a modern and technically advanced steel industry. There is no area, process or type of work in an iron and steel plant that cannot be accident free. Safety requires a permanent 100 % commitment from everyone. Most importantly, it requires a strong commitment from top management of steel organization, which should set the culture in which safety is the number one priority and in which safety is not compromised with any other objective. Many steel organizations are improving their safety performance and some plants have gone without any lost time injuries or fatalities for many years. These organizations know that such performance needs excellence in all aspects of their operations. This excellence also produces superior operational performance. The most successful steel organization is also the safest. Safety in workplace is of prime importance in the iron and steel plant. Safety depends very much on the employee’s  reaction to potential hazards. The responsibility for the management is to provide the safest possible physical conditions, but for safety, it is always necessary to obtain everyone’s cooperation in the safety programs. Accident prevention committees, departmental safety representatives, safety incentives, competitions, suggestion schemes, slogans and warning notices etc, can all play an important role in spreading the safety awareness amongst the employees. Involving all persons in site hazard assessments, behaviour observation and feedback exercises can promote positive safety attitudes and ...

Generation of Hot Air Blast and Hot Blast Stoves Apr18

Generation of Hot Air Blast and Hot Blast Stoves...

Generation of Hot Air Blast and Hot Blast Stoves            A hot blast stove is a facility to supply continuously the hot air blast to a blast furnace. Before the blast air is delivered to the blast furnace tuyeres, it is preheated by passing it through regenerative hot blast stoves that are heated primarily by combustion of the blast furnace top gas (BF gas). In this way, some of the energy of the top gas is returned to the blast furnace in the form of sensible heat. This additional thermal energy returned to the blast furnace as heat reduces the requirement of blast furnace coke substantially and facilitates the injection of auxiliary fuels such as pulverized coal as a replacement for expensive metallurgical coke. This improves the efficiency of the process. An additional benefit resulting from the lower fuel requirement is an increase in the hot metal production rate. All of these have a significant effect in terms of reducing the hot metal cost. History of hot blast stoves The use of blast furnaces dates back as far as early as fifth century B.C. in China. However, it was not until 1828 that the efficiency of blast furnaces was revolutionized by preheating them using hot stoves in conjunction with the process, an innovation created by James Beaumont Nielson, previously foreman at Glasgow gas works. He invented the system of preheating the blast for a furnace. He found that by increasing the temperature to 300 deg F (149 deg C), he could reduce the fuel consumption from 8.06 tons to 5.16 tons with further reductions with higher temperatures. In 1860, the cooperative use of hot stoves with blast furnaces was further transformed by Edward Alfred Cowper by recycling the top gas...

Grinding Mills and Their Types...

Grinding Mills and Their Types  In various fields of the process industry, reduction of size of different materials is a basic unit operation. The basic idea is to reduce particle sizes of material under handling by cutting or breaking those to smaller pieces. The usual reason for size reduction is normally the need for smaller size, but it can also be desired shape, size or number of particles. The functions of mechanics in machines made for size reduction are usually based on the principles namely (i) compression, (ii) impact, (iii) attrition, and (iv) shear. (Refer article under link  http://ispatguru.com/crushers-and-their-types/ ) Grinding mills are size reductions machines that often follow crushers in the processes where finer products are desired after crushing. Different grinding machines are usually named as mills, for example rod mills, ball mills, and attrition mills. Because of the name, verb milling is also been used as a synonym for grinding. Milling, sometimes also known as fine grinding, pulverizing or comminution, is the process of reducing materials to a powder of fine or very fine size. It is distinct from crushing or granulation, which involves size reduction of a material to a smaller size. Milling is used to produce a variety of materials which either have end uses themselves or are raw materials or additives used in the manufacture of other products. A wide range of mills has been developed each for particular applications. Some types of mills can be used to grind a large variety of materials whereas others are used for certain specific grinding requirements. Material grinding is quite often an integral part of an industrial process, whether carried out on a large or small scale and in some cases the grinding mill may be the single most costly item for...