FURNACES

Electric Arc Furnaces. Electric arc furnaces are often used in large steel foundries and steel mills. The metal is charged into the furnace, with additives to make recovery of slag easier, and heat to melt the metal is produced with an electric arc from three carbon or granite electrodes.

The electric arc furnace is lined with refractories which slowly decompose and are removed with slag. Electric arc furnaces also usually employ air emissions equipment to capture most air pollution.

Induction Furnaces. Induction furnaces are the most widely used type of furnace for melting iron and are increasingly popular for melting non-ferrous metals. They are popular because they provide excellent metallurgical control and are relatively pollution free. Coreless induction furnaces are used for smaller (5-10 ton) operations. In coreless induction furnaces, refractory lined crucibles are surrounded by water-cooled, copper coils.

For larger quantities, channel induction furnaces are used. In these furnaces the copper coils are surrounded by inductors to promote metal melting. Channel furnaces are commonly used to hold the molten metal prior to casting.

Induction furnaces use alternating currents to create heat and melt the metal. The refractories are usually made of silica, alumina or magnesia. They break down over time and become part of the slag.

2.Find in the text English equivalents to the following words and word combinations:

дугова піч, сталеливарний завод, виділення шлаків, повітряні викиди, індукційна піч, тигельна індукційна піч, тигель, мідна спіраль, руйнування, шлак.

3.Make up sentences from the following words. Translate them into Ukrainian.

1. Arc, large, steel, mills, steel, foundries, and, electric, furnaces, are, often, used, in.

2. Furnaces, coreless, induction, smaller, operations, are, use, for.

3. Quantities, for, larger, furnaces, are used, induction, channel.

4. Fill in the gaps with the following verbs in appropriate tense form according to the meaning:

to make, to surround, to use, to employ, to remove, to line, to use, to charge

1. Electric arc furnaces _____ in large steel foundries and steel mills.

2. The metal _____ into the furnace.

3. The electric arc furnace _____ with refractory which slowly decompose and _____ with slag.

4. Coreless induction furnaces _____ for smaller operations.

5. Refractory lined crucibles _____ by water cooled, copper coils.

6. Electric arc furnaces usually _____ air emissions equipment to capture most air pollution.

7. The refractory _____ of silica, alumina or magnesia.

5. Answer the following questions:

1. Where are electric arc furnaces used?

2. What do electric arc furnaces usually employ?

3. What is the most widely used type of furnaces?

4. Why are induction furnaces popular?

5. When are channel furnaces used?

Section 3

1. Read and translate the following text:

CUPOLA

Cupola furnaces are the oldest type of furnaces used in foundries. They are tall and roughly cylindrical and are most often used for melting iron and ferroalloys.

Alternating layers of metal and ferroalloys, coke, and limestone are fed into the furnace from the top. Coke makes up 8 - 16% of the total charge to provide the heat that melts the metal. Limestone is added to react with impurities in the metal and floats to the top of the metal as it melts. As in steel melting, this limestone/impurities combination is called slag. By floating on top of the metal while it melts, the slag protects the metal from oxidation.

Cupola furnaces are lined with refractories, or hard, heat resistant substances such as fire clay, bricks or blocks. The refractory protects the furnace shell from abrasion, heat and oxidation. Over time the refractory breaks down and eventually becomes part of the slag.

Cupola furnaces are usually attached to emissions control systems to capture air emissions. Usually, the air emission systems use either high energy wet scrubbers that use water to remove air pollution from the gas stream or dry bag house systems that use fabric filters to capture the emissions.

2. Find in the text English equivalents to the following words and word combinations:

вагранка, кольорові сплави, кокс, домішки, захищати метал, окислення, глина, цегла, скрубер вологого очищення, повторювальні ряди, пиловловник, вловлювати викиди.

3. Match the following English words with their meaning:

4.Put the verbs in brackets in right tense. Translate these sentences into Ukrainian.

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

Section 1

1. Read and translate the following text:

Date: 2015-01-02; view: 1175