Aluminum production from bauxite ore

Aluminum is produced from bauxite ore in three steps:

I.

1. First the alumina _____ from bauxite ore.

2. Then finely crushed bauxite _____ with sodium hydroxide and placed in a digester.

3. Dissolved aluminum oxide and ore residue _____ as the result of the reactions at high temperatures and pressures in the digester.

4. The residues including silicon, lead, titanium, and calcium oxides, _____ a sludge in the bottom of the digester.

5. The aluminum oxide _____ off and condensed.

6. Starches and other ingredients _____ to remove any remaining impurities from the oxide.

7. After that the solution _____ to a precipitation tank.

8. There the aluminum oxide _____.

9. The crystals _____, vacuum dewatered and _____ to a calcinator for further dewatering.

II.

1. Then aluminum oxide _____ to aluminum metal.

2. In this process the aluminum oxide _____ in an electrolytic cell with molten cryolite.

3. A carbon rod in the cell _____ and the reaction results in carbon monoxide, carbon dioxide and aluminum.

4. The aluminum _____ to the bottom.

5. It _____ from the tank and sent to a melting or holding furnace.

III.

1. The molten aluminum _____ with desired alloys to obtain specific characteristics.

2. It ___ into ingots for transport to fabricating shops.

3. In the fabrication shops, the molten aluminum or aluminum alloys _____ into casts and cooled.

4. Molten aluminum _____ to remove oxides, impurities and other active metals such as sodium and magnesium, before casting.

5. Chlorine _____ through the molten aluminum to further remove impurities.

Task 8

Answer the following questions.

1. What can be made of aluminum?

2. What are the main demands to the place of location of the primary aluminum producers?

3. How can aluminum be produced?

4. Name all the furnaces mentioned in the text.

Task 9

Make up a dialogue according to the text ‘Primary aluminum production’.

Task 10

Pick up 5-7 key words and make up sentences with them.

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