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1. If cupola furnaces _____ the oldest type of furnaces, they will be rather reliable. (to be)
2. If limestone is added to the metal, it _____ with impurities. (to react)
3. If the slag _____ metals from oxidation, they will be rather reliable. (to protect)
4. If cupola furnaces are lined with refractory bricks, they _____ the furnace shell from abrasion. (to protect)
5. If the refractory _____, it will become part of the slag. (to break down)
5. Turn the following sentences from Direct Speech to Indirect Speech:
1. The scientist told the students: “Cupola furnaces are the oldest type of furnaces used in foundries.”
2. The engineer stressed: “Limestone is added to react with impurities in the metal.”
3. The metallurgist said: “Limestone combination is called slag.”
4. The scientist agreed: “The slag protects the metal from oxidation.”
5. The metallurgist affirmed: “Cupola furnaces are lined with refractory.”
6. The scientist told the students: “The refractory is protecting the furnace steel from abrasion.”
7. The metallurgist admitted “Over time the refractory will break down and will become part of the slag.”
6. Answer the following questions:
1. What type of furnaces are cupola furnaces?
2. What is produced with cupola melting?
3. Why is limestone added to cupola furnaces?
4. What is slag?
5. How does the refractory protect the furnace?
6. What do the air emissions systems usually use?
UNIT 3
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