Monday, July 29, 2013

Pakistan Steel's Railway Department.


Pakistan Steel has its own railway department provided with Soviet make Locomotives, gandolas and bogies as an integral part of the project. Pakistan steel’s railway department has its own repair and maintenance locomotive workshop within its premises.

The Blast furnace molten slag is dispatched through specially designed slag cars to slag dump yard for onward processing to make it salable to market..

 Specially designed bogies are used for transportation of molten pig iron ladles from iron making department to  steel making department and to pig casting machine.

  In high production and energy efficient integrated iron and steel plants, the transport of molten pig iron between the blast furnace and steel plants is performed in a so-called torpedo vessel ( torpedo ladle) worldwide shown below rather than using hot metal ladles shown above.

Self tilting Torpedo vessel provides the following major advantages over usage of hot metal ladles:

-          Reduces the huge loss of Physical temperature of hot metal ( enormous energy ) due to transportation and handling of hot metal ladles between Iron making and Steel making departments which could be preserved & utilized for melting additional amount of scrap in LD-Converter.

-           Eliminates the number of pig iron ladles and their maintenance cost. Torpedo vessel of capacity 300 tonne may take the hot metal of two consecutive tappings of Blast furnaces of the existing volume of B.F. of  Pakistan Steel.

-          Eliminates the excessive use of overhead charging cranes in steel making department for pouring pig iron ladles into / out of 1300Ton Mixer. Self tilting torpedo vessel directly dispenses molten pig iron into converter charging ladle thereby reduces the time of Overhead charging cranes to half. This would help to enhance the efficiency and hence the production capacity of steel making department.

-          The usage of torpedo vessel is expected to save the temperature of hot metal 80-1000C which reduces the amount of hot metal required per (batch) heat and allows more scrap convert to steel. A vessel of capacity 300 tonne may be sufficient for three consecutive batches ( heats) of 130 tonne charge (Scrap + Hot metal) of LD-Converter and may eliminate the use of hot metal storage vessel ( 1300 ton Mixer) and its yearly Capital repair cost in steel making department.

Few steel plants have used Torpedo vessels for pre-treatment of hot metal to remove harmful elements Sulphur, Phosphorus  and Silicon  but these operations tend to decrease the physical temperature of hot metal and cause the excessive wear/ consumption of refractory lining of the Torpedo vessel and substantial increase in cost of operation. The said chemical elements in hot metal at Pakistan Steel are kept controlled within required limits through control of Blast furnace charge materials as such pretreatment of hot metal would not be needed currently.

Provision of this energy efficient hot metal transport vessel  may be deemed as a part of future revamp package (Phase- II expansion program). Briefly the addition of Torpedo vessel facility will be needing  modification of existing Blast furnace Cast house platform, utilization of space available for installation of second 1300 tonne Mixer at steel making department, up gradation of rail track and hauling capacity between Blast furnace and steelmaking department to endure the heavy load of this huge transport vessel.

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