Page 197 - Chemistry ICSE Class X

Metallurgy 183

What are minerals and ores
Naturally-occurring compounds of metals mixed with earthly materials
are called minerals. A mineral may contain a small or large percentage of
metal in it. The metal content of a mineral may also vary from place to place.
A mineral from which a metal can be extracted on a commercial scale
economically and easily is called an ore.
Some common ores of iron, aluminium and zinc are mentioned below.

Metal Oxide ores Carbonate ores Sulphide ores Fluoride ores
Iron Haematite (Fe O ) Siderite (FeCO ) Iron pyrites (FeS ) —
2
3
3
2
Magnetite (Fe O )
4
3
Limonite (Fe O .3H O)
2
3
2
Aluminium Bauxite (Al O .2H O) — — Cryolite (Na AlF )
3
2
6
3
2
Corundum (Al O )
3
2
Zinc Zincite (ZnO) Calamine (ZnCO ) Zinc blende (ZnS) —
3
How are ores classified
1TGU CTG ENCUUKſGF QP VJG DCUKU QH V[RG QH VJG metal compound present in it.
For example, if the metal is present as its oxide in an ore, the ore is called an ůƵŵŝŶŝƵŵ ; ůͿ ŝƐ ƚŚĞ ŵŽƐƚ ĂďƵŶĚĂŶƚ
oxide ore. Some common types of ores are given in Table 7.5. ŵĞƚĂů ŝŶ ƚŚĞ ĞĂƌƚŚ͛Ɛ ĐƌƵƐƚ͕ ŝƌŽŶ ;&ĞͿ
ĂŶĚ ĐĂůĐŝƵŵ ; ĂͿ ďĞŝŶŐ ƚŚĞ ƐĞĐŽŶĚ
ĂŶĚ ƚŚŝƌĚ ŵŽƐƚ ĂďƵŶĚĂŶƚ ŵĞƚĂůƐ ŝŶ
Table 7.5 Some common ores of metals
ƚŚĞ ĞĂƌƚŚ͛Ɛ ĐƌƵƐƚ͘
Oxide ores Carbonate ores Sulphide ores Halide ores dŚĞ ĞdžƚƌĂĐƟŽŶ ŽĨ ŵĞƚĂů ĨƌŽŵ Ă
ŵŝŶĞƌĂů ĐŽŶƚĂŝŶŝŶŐ ǀĞƌLJ ƐŵĂůů
Bauxite Limestone Galena (PbS) is Rock salt (NaCl) ƉĞƌĐĞŶƚĂŐĞ ŽĨ ŵĞƚĂů ŵĂLJ ŶŽƚ
(Al O .2H O) is (CaCO ) is a a sulphide ore of is a chloride ore of ďĞ ĐŽŵŵĞƌĐŝĂůůLJ ƉƌŽĮƚĂďůĞ͘ &Žƌ
3
2
2
3
an oxide ore of carbonate ore of lead. sodium. ĞdžƚƌĂĐƟŽŶ͕ ŽŶůLJ ƚŚŽƐĞ ŵŝŶĞƌĂůƐ
aluminium. calcium. ĂƌĞ ƵƐĞĚ ǁŚŝĐŚ ŚĂǀĞ Ă ƌĞĂƐŽŶĂďůĞ
ĂŵŽƵŶƚ ŽĨ ŵĞƚĂů ŝŶ ƚŚĞŵ͘ dŚĞƌĞĨŽƌĞ͕
Haematite (Fe O ) Calamine Copper glance Cryolite (Na AlF ) an ore is a mineral but a mineral
3
2
3
6
is an oxide ore of (ZnCO ) is a (Cu S) and copper KU C ƀWQTKFG QTG QH may not necessarily be an ore.
2
3
iron. carbonate ore of pyrites (CuFeS ) aluminium.
2
zinc. are sulphide ores
of copper.
Cuprite (Cu O) Cinnabar (HgS) is ůů ŵĞƚĂůƐ ǁŚŝĐŚ ĂƌĞ ŶŽƚ ĂīĞĐƚĞĚ ďLJ
2
is an oxide ore of a sulphide ore of ǁĂƚĞƌ ĂŶĚ ďLJ ƚŚĞ ŐĂƐĞƐ ƉƌĞƐĞŶƚ ŝŶ
copper. mercury. ƚŚĞ Ăŝƌ ŽĐĐƵƌ ŝŶ ĨƌĞĞ ƐƚĂƚĞ ŝŶ ŶĂƚƵƌĞ͕
ǁŚĞƌĞĂƐ ƚŚĞ ŵĞƚĂůƐ ǁŚŝĐŚ ƌĞĂĐƚ
ǁŝƚŚ ǁĂƚĞƌ͕ ĐĂƌďŽŶ ĚŝŽdžŝĚĞ͕ ŽdžLJŐĞŶ͕
What is gangue ĂŶĚ ŽƚŚĞƌ ĐŚĞŵŝĐĂůƐ ǁŚŝĐŚ ĞdžŝƐƚ ŝŶ
ŶĂƚƵƌĞ͕ ŽĐĐƵƌ ŝŶ ƚŚĞ combined ĨŽƌŵ
Ores usually contain large quantities of unwanted earthly materials. Such ĂƐ ĐŽŵƉŽƵŶĚƐ͘
unwanted earthly material present in an ore is called gangue. Gangue
may be acidic or basic in nature.
dŚĞ ŵŽƐƚ ĐŽŵŵŽŶůLJ ƵƐĞĚ ŽƌĞ ŽĨ
What is a flux ĂůƵŵŝŶŝƵŵ ŝƐ ďĂƵdžŝƚĞ ; ů O ͘Ϯ, KͿ͘
Ϯ ϯ
Ϯ
ĂƵdžŝƚĞ ƵƐƵĂůůLJ ĐŽŶƚĂŝŶƐ ŝƌŽŶ ŽdžŝĚĞ
A substance which during smelting combines with the earthly impurities ;&ĞKͿ ĂŶĚ ƐŝůŝĐĂ ;^ŝK Ϳ ĂƐ ŝŵƉƵƌŝƟĞƐ͘
Ϯ
RTGUGPV KP VJG QTG VQ HQTO C HWUKDNG UNCI KU ECNNGF C ƀWZ 6JGTG CTG VYQ V[RGU
QH ƀWZGU
ƒ #EKFKE ƀWZ G I UKNKEC 5K1 )
2
ƒ $CUKE ƀWZ G I NKOG %C1 NKOGUVQPG %C%1 )
3