Текст 15.

WHAT IS NICKEL?

Nickel (symbol Ni, atomic weight 58.71, atomic number 28) is a lustrous, silvery-white metal discovered in 1751. It has a melting point of 1453°C, relatively low thermal and electrical conductivities, high resistance to corrosion and oxidation, excellent strength and toughness at elevated temperatures, and is capable of being magnetized. It is attractive and very durable as a pure metal, and alloys readily with many other metals.

Reflecting these qualities, nickel is widely used in over 300,000 products for consumer, industrial, military, transport/aerospace, marine and architectural applications. The public may recognise nickel in coins, as it is used for this purpose in pure or alloy forms by many countries, or as bright and durable electrolytically-applied coatings on steel (nickel plating). The biggest use, however, is as an alloying metal along with chromium and other metals in the production of stainless and heat-resisting steels. These are mostly used in industry and construction, but also for products in the home such as pots and pans, kitchen sinks, etc. Stainless steels are produced in a wide range of compositions to meet special industry requirements for corrosion and heat resistance, and also to facilitate a clean and hygienic surface for food and other processing.

In fact, about 65 per cent of nickel is used to manufacture stainless steels, and 20 per cent in other steel and non-ferrous (including “super”) alloys, often for highly specialized industrial, aerospace and military applications. About 9 per cent is used in plating and 6 per cent in other uses including coins and a variety of nickel chemicals.

Nickel occurs in nature principally as oxides, sulphides and silicates. Ores of nickel are mined in about 20 countries on all continents, and are smelted or refined in about 25 countries. Primary nickel is produced and used in the form of ferro-nickel, nickel oxides and other chemicals, and as more or less pure nickel metal. Nickel is also readily recycled in many of its applications, and large tonnages of secondary or “scrap” nickel are used to supplement newly mined metal.

Only about 1 million tonnes of new or primary nickel are produced and consumed annually in the world, compared with over 10 million tonnes of copper and nearly 800 million tonnes of steel.