Light metals
Density less than 4500 kg/m3, such as aluminum, magnesium, potassium, sodium, calcium, strontium, barium and so on.
Heavy metal
Density greater than 4500 kg/m3, such as copper, nickel, cobalt, lead, zinc, tin, antimony, bismuth, cadmium, mercury and so on.
Precious metals
It is more expensive than common metals, has low crustal abundance and is difficult to purify, such as gold, silver and platinum group metals.
semimetal
It has properties between metals and nonmetals, such as silicon, selenium, tellurium, arsenic and boron.
Rare metal
Including rare light metals such as lithium, rubidium and cesium;
Rare refractory metals, such as titanium, zirconium, molybdenum, tungsten, etc.
Rare dispersed metals, such as gallium, indium, germanium, thallium, etc.
Rare earth metals such as scandium, yttrium and lanthanide;
Radioactive metals such as radium, francium, polonium, and uranium and thorium in the Arabic family of elements.
Throughout history, the materials used in the production tools have been constantly improved, which is closely related to the development of human society. Therefore, historians have used the material of objects to mark the historical period, such as the Stone Age, Bronze Age, iron age and so on. By the end of the 17th century, there were 8 kinds of non-ferrous metals that were clearly recognized and applied by human beings. The Chinese nation made great contributions to the discovery and production of these nonferrous metals (see history of metallurgy). After entering the 18th century, the rapid development of science and technology promoted the discovery of many new non-ferrous metal elements. In addition to the above 64 non-ferrous metals in the 17 th century has been recognized in the application of 8, in the 18 th century a total of 13. Thirty-nine species were discovered in the 19th century, and four more were discovered in the 20th century.
Nonferrous metals are essential basic materials and important strategic materials for the development of national economy, People's Daily life, national defense industry and science and technology. Agricultural modernization, industrial modernization, national defense and scientific and technological modernization are inseparable from nonferrous metals. For example, aircraft, missiles, rockets, satellites, nuclear submarines and other sophisticated weapons and atomic energy, television, communications, radar, electronic computers and other cutting-edge technologies required by the components or components are mostly made of non-ferrous metal in the light metal and metal ene; In addition, there is no production of alloy steel without nonferrous metals such as nickel, cobalt, tungsten, molybdenum, vanadium and niobium. The use of nonferrous metals in some applications, such as the power industry, is also considerable. Now many countries in the world, especially the industrial developed countries, compete to develop the non-ferrous metal industry, increase the strategic reserves of non-ferrous metals.
The non-ferrous metal industry includes departments of geological exploration, mining, ore dressing, smelting and processing. The content of non-ferrous metals in the ore is generally low, in order to get a ton of non-ferrous metals, often to mine hundreds of tons or more of ore. So mine is the important foundation that develops nonferrous metal industry. Nonferrous metal ores are often multi-metal symbiosis, so it is necessary to extract and recover useful components reasonably and make comprehensive utilization so as to make rational use of natural resources. Many kinds of rare metals, precious metals and sulfuric acid and other chemical products are recovered in the process of processing nonferrous metal ores or intermediate products as well as slag and soot. A large amount of waste gas, waste water and waste residue are usually produced in the production of nonferrous metals, which contain a variety of useful components, sometimes toxic substances, and some nonferrous metals are also toxic. Therefore, in the process of producing nonferrous metals, we must pay attention to comprehensive utilization and environmental protection.
