JNTU Question Papers-B Tech-Supplementary Examinations-February 2008

JNTU  B.Tech IV Supplementary Examinations, February 2008

STEEL MAKING

(Metallurgy & Material Technology)

SET-III

 

1. (a) Explain the oxidation stages-occurring in the Acid Bessemer Converter.

(b) Give the slag-composition obtained in a Acid Bessemer converter.

(c) What is the refractory-living material for Acid-Bessemer converter? Give reasons for why is it being used?

 

2. (a) What is the purpose of third blow in a Kaldo converter just before metal tapping?

(b) How is the refining controlled by the speed of vessel rotation and oxygen flow rate?

(c) How is it possible to obtain steels with low P, S, C and N using Kaldo-process?

 

3. (a) Explain the physics of bubble formation of carbon-monoxide the refractory metal interface?

(b) With the help of diagram, explain the active-sites and inactive-sites of cobubble nucleation t refractory-metal interface.

 

4. (a) Write the ’P’ Oxidation reaction? How is it fixed up in the slag-phase?

(b) Explain the formation of tricalcic phosphate and tetracalcic phosphate with the help of chemical – reactions?

 

5. (a) Explain the differences between an active-mixer and an inactive mixer.

(b) What is difference in charge composition between Blast Furnace hot metal and Active Mixer-metal.

(c) What is the advantage of Active mixer practice over ladle desiliconisation.

 

6. (a) Explain how the charging is carried out in a typical electric are furnace?

(b) Why some amount of light scrap is preferred at the bottom of arc furnace?

 

7. Explain the Bottom-teeming method of liquid steel with the help of a neat diagram.

 

8. Explain the following.

(a) Duplex-processes of steelmaking

(b) Triplex-processes of steelmaking

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