basic oxygen process, method of producing steel from a charge consisting mostly of pig iron. The charge is placed in a furnace similar to the one used in the Bessemer process of steelmaking except that pure oxygen instead of air is blown into the charge to oxidize the impurities present. One desirable feature of this process is that it takes less than an hour, and is thus much faster than the open-hearth process, another important method of steelmaking. A second advantage is that a major byproduct is carbon monoxide, which can be used as a fuel or in producing various chemicals, such as acetic acid. The basic oxygen process also produces less air pollution than methods using air.

Multiples

Prefix	Abbreviation	Power of 10	Equivalent
deka- or deca-	da	101	ten
hecto-	h	102	hundred
kilo-	k	103	thousand
mega-	M	106	million
giga-	G	109	billion
tera-	T	1012	trillion
peta-	P	1015	quadrillion
exa-	E	1018	quintillion
zetta-	Z	1021	sextillion
yotta-	Y	1024	septillion

Fractions

Prefix	Abbreviation	Power of 10	Equivalent
deci-	d	10-1	tenth
centi-	c	10-2	hundredth
milli-	m	10-3	thousandth
micro-	μ	10-6	millionth
nano-	n	10-9	billionth
pico-	p	10-12	trillionth
femto-	f	10-15	quadrillionth
atto-	a	10-18	quintillionth
zepto-	z	10-21	sextillionth
yocto-	y	10-24	septillionth

BASIC: see programming language.

In geology, any igneous rock dominated by the silicates pyroxene, amphibole, olivine, and mica. These minerals are high in magnesium and ferrous iron, and their presence gives mafic rock its characteristic dark colour. It is usually contrasted with felsic rock. Common mafic rocks include basalt and gabbro.

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Steelmaking method in which pure oxygen is blown through a long, movable lance into a bath of molten blast-furnace iron and scrap, in a steel furnace with a refractory lining called a converter. The oxygen initiates a series of heat-releasing reactions, including the oxidation of such impurities as silicon, carbon, phosphorus, and manganese; carbon dioxide is released, and the oxidation products of the other impurities form molten slag that floats on the molten steel. The advantages of using pure oxygen instead of air in refining iron into steel were recognized as early as the 1850s (see Bessemer process), but the process could not be commercialized until the late 1940s, when cheap, high-purity oxygen became available. Within 40 years it had replaced the open-hearth process and was producing more than half of all steel worldwide. Commercial advantages include high production rates, less labour, and steel with a low nitrogen content.

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Modification of the Bessemer process for converting pig iron into steel. The original Bessemer converter was not effective in removing the phosphorus from iron made from the high-phosphorus ores common in Britain and Europe. The invention of the basic process in England by Sidney G. Thomas (1850–1885) and Percy Gilchrist overcame this problem; the Thomas-Gilchrist converter was lined with a basic material such as burned limestone rather than an acid siliceous material. The introduction of the basic Bessemer process in 1879 made it possible for the first time for such high-phosphorus ore to be used for making steel.

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