The refractory lining of the bottom in a basic electric arc furnace is made of___________________?

Related Mcqs:

1. A furnace is made of a refractory brick wall of thickness 0.5 metre and thermal conductivity 0.7 W/m.°K For the same temperature drop and heat loss, this refractory wall can be replaced by a layer of diatomaceous earth of thermal conductivity 0.14 W/m.K and thickness ______________ metre?

   A. 0.01
   B. 0.1
   C. 0.25
   D. 0.5

2. The usual energy consumption in electric arc furnace steel making is _____________ KWh/ton of steel ?

   A. 60 – 100
   B. 400 – 700
   C. 1200 -1500
   D. 2000 – 2300

3. Electrolytic reduction cell used for conversion of calcined Al2O3 to Al is a carbon lined furnace operating at 800-900 °C. The purpose of electric current supplied to the furnace is to___________________?

   A. Achieve very high purity of aluminium (99.9%)
   B. Keep the electrolyte in liquid condition by the generation of heat
   C. Electrolytically dissociate alumina
   D. Both B. & C.

4. One face of a furnace wall is at 1030°C and the other face is exposed to room temperature (30°C). If the thermal conductivity of furnace wall is 3 W. m-1. k-1 and the wall thickness is 0.3 m, the maximum heat loss (in W/m) is____________________?

   A. 100
   B. 900
   C. 9000
   D. 10000

5. Basic open hearth furnace (BOF) is not used for producing ______________ steel?

   A. Killed
   B. Rimming
   C. High alloy
   D. None of these

6. Coating provided on the electrodes used in the arc welding is not expected to_________________?

   A. Add alloying elements
   B. Prevent electrode from contamination
   C. Stabilise the arc
   D. Provide protective atmosphere to weld

7. Which of the following mainly decides the current to be employed is arc welding ?

   A. Electrode size
   B. Plate thickness
   C. Voltage across the arc
   D. Welded portion length

8. The refractory brick which has good thermal shock resistance at high temperature but cracks on cooling below 400°C is__________________?

   A. Magnesite
   B. Chrome
   C. Silica
   D. Fireclay

9. Absolute zero pressure can be attained at a temperature of___________________?

   A. 0°C
   B. 50°K
   C. 0°R
   D. None of these

10. Fog is an example of colloidal system of___________________?

    A. Solid dispersed in gas
    B. Solid dispersed in liquid
    C. Liquid dispersed in gas
    D. Gas dispersed in liquid