Iron is the only metal that can be found in almost every part of the world. It’s the fourth element in abundance on the earth, being exceeded by oxygen, silicon and aluminum. It is the cheapest of the heavy metals as well as the strongest and most magnetic of known substances.
Iron for commercial use is obtained by extraction from its ores. The value of an iron depends upon several factors, that is percentage of iron it contains, the amount of impurities and moisture present and the cost of mining, smelting, and transportation. The principal iron ore is hematite or red hematite (Fe2O3) which contains 70 per cent of metallic iron. The red hematites are the most desirable of all the iron ores. When this oxide contains water it is called limonite or brown hematite (Fe2O3 x H2O), containing 70 % of pure iron. The brown hematites are generally low in sulphur but are often associated with manganese.
Magnetite (Fe3O4) occurs abundantly and it has the greatest percentage of pure iron (72, 4 %).
Siderite (FeCO3) or carbonate ore has been used as an ore but because of its small iron content (48, 3%) it is nit often used now.
The most common impurities in iron ore are silica, titanium, and phosphorus. The ores containing the smallest amounts of these impurities are the most valuable.
Дополнительные слова и словосочетания:
1) abundance, n – изобилие, обилие
2) abundantly, adv – обильно
3) be low in… – иметь низкое содержание
4) commercial, a – технический, промышленный
5) limonite, n – лимонит
6) magnetite, n – магнетит
7) mining, n – горное дело
8) moisture, n – влага
9) siderite, n – сидерит
X. Прочтите текст и дайте краткое содержание текста в 4-x предложениях.
XI. Установите, какие из приведенных утверждений, соответствуют содержанию текста.
1. Для промышленного использования железо добывают из железосодержащих руд.
2. Марганец восстанавливается в доменной печи из оксида марганца.
3. Самые распространенные примеси железной руды – кремнезем, титан, фосфор.
4. Сварочное железо очень легко обрабатывать.
5. Все вещества находятся в одном из трех агрегатных состояний: твердом, жидком или газообразном.
XII. Вставьте подходящие по смыслу слова.
1. Magnetite occurs ….. and it has the ….. percentage of pure iron.
a) smallest, most valuable;
b) abundantly, greatest;
c) greater, outstanding.
2. Iron for commercial use is obtained by…..
a) alloying elements;
b) extraction from its ores;
c) by open-hearth process.
3. The ores containing the smallest amounts of ….. are the most valuable.
a) natural gas;
b) engineering metals;
c) these impurities.
XIII. Укажите, какие из данных предложений, соответствуют содержанию текста.
1. About two thirds of all elements found in the earth are metals.
2. Iron is the cheapest of the heavy metals as well as the strongest and the most magnetic of known substances.
3. The addition of small quantities of ferro-silicone and ground ferro-manganese generally gives beneficial results.
4. The ores containing the smallest amounts of impurities are the most valuable.
5. Molten steel is poured into large moulds and solidified.
XIV. Закончите следующие предложения в соответствии с содержанием текста.
1. It’s the fourth element ….
a) in the charge which dissolves in the molten iron;
b) that makes the fracture look grey;
c) in abundance on the earth.
2. Iron is obtained by …..
a) extraction from its ores;
b) the chemical reaction between the charge and gas;
c) covering the bottom with several layers of clay brick.
3. Siderite or carbonate ore has been used as an ore, but …..
a) because of it’s small iron content it is not often used now;
b) it’s reduced to the elemental state by carbon;
c) it may be made by melting pig iron and scrap in the cupola.
XV. Выберите из текста предложения, в которых дана характеристика основных железных руд.
XVI. Составьте план к тексту на русском языке.