The First Non - Ferrous Metals
Non-ferrous metals are the metals not composed of or containing iron. As it has been said before, copper was one of the first metals to be used. In its natural form, copper occurs in the ground as copper ore, a mineral. But this ore contains only 0.5 - 1 per cent of the metal. The rest is rock. The world produces 9.6 million tonnes of copper a year. This means that more than a thousand million tonnes of ore have to be removed from the ground and the pure copper extracted.
Most copper is extracted from a compound of iron, sulphur, and copper called sulphide ore. Hot air is blown into a furnace to separate the copper from the iron and sulphur. The iron and sulphur react with the oxygen to form iron oxide and sulphur dioxide, leaving molten copper metal. This copper, known as blister copper, is about 98 per cent pure. A process called electrolysis is needed to separate the remaining impurities. During this process a slab of blister copper is suspended in a solution of copper sulphate and sulphuric acid, where it acts as a positive electrode (anode). When electricity is passed through the solution, the copper in the anode is dissolved. The pure copper collects at the negative electrode (cathode) and the impurities fall below.
Copper is a good conductor of heat and electricity. We use it to make cooling utensils and all sorts of pipes for carrying hot water, both in homes and in industry. We also use it to make different kinds of electrical devices, such as lightning conductors and the electric coils in motors. Copper does not rust easily, so it lasts a very long time.
Such metals as lead and tin were widely known in Roman times. Lead is a soft malleable, ductile, bluish-white, dense metallic element, extracted chiefly from galena and used in containers and pipes for corrosives, in solder and type metal, bullets, radiation shielding, paints and anti-knock compounds.
Some Roman aqueducts still stand today because they were lined with lead and lead does not rust. Many thousands of tonnes were used in a single aqueduct. So much lead was used in water-supply systems that eventually the Romans suffered some lead-poisoning.
Tin was the fifth metal discovered by man. It is a malleable, silvery metallic element obtained chiefly from cassiterite. It is used to coat other metals to prevent corrosion, and forms part of numerous alloys such as soft solder, pewter, type metal and bronze. For example,pewter, an alloy of lead and tin, was widely used in Roman times to make cups and dishes.
Task 1.
Phonetic Exercise
Practise after the speaker and learn to pronounce the words given below:
sulphur /’s/\ lf'/; sulphide /’s/\ lfaid/; pure /’pju:э/; electrolysis /ilek’trolisis/; sulphuric /s'l’fju'rik/; cathode /kжрoud/; anode /’ж noud/; galena /g'‘li:n'/; corrosive /k'‘rousiv/; cassiterite /k'‘sit'rait/; pewter /’pju:t'/; aqueduct /’жkwid'kt/.
Task 2
Lexical Exercises
Exercise 1.Find the English equivalents for the words and word-
combinations given below. Use them in the sentences
of your own.
цветные металлы; содержать железо; извлекать; железо и сера вступают в реакцию с кислородом; электролиз; сляб; анод и катод; электрообмотка; молниеотвод; галенит; припой; гарт; касситерит; предотвратить коррозию; мягкий припой; сплав на оловянной основе; олово; система водоснабжения; ржаветь; акведук.
Exercise 2.Match the English words and word combinations given
below with their Russian equivalents.
1. to be composed of 1. едкое вещество
2. sulphide ore 2. оседать на дно
3. sulphur dioxide 3. состоять из
4. blister copper 4. длиться долгое время
(зд. долговременный)
5. fall below 5. электроприборы
6. electrical devices 6. двуокись серы, сернистый ангидрид
7. to last a long time 7. противорадиационный экран
8. corrosive 8. свинцовые отравления
9. radiation shielding 9. покрывать металлы
10. lead-poisoning 10. пузырчатая медь
11. to cover metals 11. серный (железный) колчедан, пирит
Exercise 3.Answer the following questions.
1. What is a non- ferrous metal? 2. What is most copper extracted from? 3. Why is copper so widely valued? 4. Were lead and tin widely known in Roman times? 5. How did the Romans use lead? 6. What are the properties of tin? 7. Why is tin widely used for coating other metals?