- PeterrLv 61 十年前最愛解答
The modern era in steelmaking began with the introduction of Henry Bessemer's Bessemer process in the late 1850s. This enabled steel to be produced in large quantities cheaply, so that mild steel is now used for most purposes for which wrought iron was formerly used. This was only the first of a number of methods of steel production. The Gilchrist-Thomas process (or basic Bessemer process) was an improvement to the Bessemer process, lining the converter with a basic material to remove phosphorus. Another was the Siemens-Martin process of open hearth steelmaking which like the Gilchrist-Thomas process complemented, rather than replaced, the original Bessemer process.
These were rendered obsolete by the Linz-Donawitz process of basic oxygen steelmaking, developed in the 1950s, and other oxygen steelmaking processes.
List of steel production by countryOne third of world's steel is currently produced in China. Arcelor-Mittal is however the largest company by steel production. As steel is a commonly recycled material, the industry estimates that of new metal produced each year, 42.3 % is reprocessed from scrap and other sources. The long service life of steel in applications such as construction means that there is a vast "store" of steel available to reuse. However, new metal derived from raw materials is also necessary to make up demand. As a metal, steel can be recycled with no loss of its physical properties and with considerably less material and energy than is required to refine it from iron ore; recycling one ton of steel saves 2,500 pounds of iron ore, 1,400 pounds of coal, and 120 pounds of limestone. Three fourths of all United States steel, for example, eventually is reprocessed into new products.
A pile of steel scrap in Brussels, waiting to be recycledIn terms of mass, more steel is recycled every year than aluminum, paper, glass, and plastic combined, making it the most recycled material in the world. Commonly recycled products include steel cans, automobiles, appliances, and debris from demolished buildings. A typical appliance is about 65 % steel by weight and automobiles are about 66 % steel and iron. Because of this large proportion of recyclable steel, some areas have laws prohibiting the disposal of appliances in landfills.
Many types of modern steels exist for different purposes. Made with varying combinations of alloy metals, their properties range to fulfill many purposes. Carbon steel, composed simply of iron and carbon, accounts for 90 % of steel production. High strength low alloy steel has small additions (usually < 2 % by weight) of other elements, typically 1.5 % manganese, to provide additional strength for a modest price increase. Low alloy steel is alloyed with other elements, usually molybdenum, manganese, chromium, or nickel, in amounts of up to 10 % by weight to improve the hardenability of thick sections. Stainless steels and surgical stainless steels contain a minimum of 10% chromium, often combined with nickel, to resist corrosion (rust). Some stainless steels are nonmagnetic.資料來源： wikipedia
- SeedeeyeeLv 51 十年前
A blast furnace is a type of metallurgical furnace used for smelting. Fuel and ore are continuously supplied through the top of the furnace, while air (oxygen) is blown into the bottom of the chamber, so that the chemical reactions take place throughout the furnace as the material moves downward. The end products are usually molten metal and slag phases tapped from the bottom, and flue gases exiting from the top of the furnace. This type of furnace is typically used for smelting iron ore to produce pig iron, an intermediate material used in the production of commercial iron and steel. Blast furnaces are also used for non-ferrous smelting processes, particularly in the production of lead.