FLUX : PYROMETALLURGY:

The substance used in metallurgical process to decrease melting point of an ore or a substance used to react gangue (impurities present in ore) to form Slag.

Type of flux: Fluxes are of two types’ viz., acidic flux and basic flux.

(A) Acidic flux: It is an acidic oxide (oxide of a non-metal) like SiO₂, P₂O₅, and B₂O₃ (from borax).

It is used to remove the basic impurity like CaO, FeO, MgO etc. The acidic flux combines with the basic impurity and forms a slag. 

(B) Basic flux: It is a basic oxide (i.e., oxide of a metal) like CaO (obtained from lime stone, CaCO₃), MgO (from magnesite, MgCO₃), haematite (Fe₂O₃) etc. It is used to remove the acidic impurity like SiO₂, P₂O₅ etc. The basic flux combines with the acidic impurity and forms a slag. 

Thus, slag can be defined as a fusible mass, which is obtained when a flux reacts with an infusible acidic or basic impurity present in the oxide ore.

METALLURGY-INTRODUCTION:

Minerals and Ores:

The biggest source of metals is earth’s crust. Metals are also found in rocks, sea water, some impurities, etc depending upon their chemical nature. Less electropositive metals have less affinity for oxygen, moisture and hence occur in free or native or uncombined state, e.g. Au, Pt, Ag, etc. While the metals with higher electropositive character occurs in combined state as compounds.

Minerals:

The naturally occurring chemical substances in the earth’s crust which are obtained by mining are known as minerals.

Ores:

Minerals which can be used as a source for commercial recovery of a desired substance are termed as ores. Earthy substances associated with ores are called gangue.

List of Important Ores:

Sl No	Name of the Element	Ores	Chemical Formulas
1	Aluminum (Al)	Bauxite	Al2O32H2O
		Corundum	Al2O3
		Kryolite	Na3AlF6
2	Calcium (Ca)	Dolomite	MgCO3CaCO3
		Lime Ston	CaCO3
3	Copper (Cu)	Copper Glance	Cu2S
		Copper Pyrite	CuFeS2
		Malachite	2CuCO3Cu(OH)2
4	Gold (Au)	Calve rite	AuTe2
		Sybarite	AgAuTe2
5	Iron (Fe)	Hematite	Fe2O3
		IronPyrite	FeS2
		Magnetite	Fe3O4
		Siderite	FeCO3
6	Lead (Pb)	Anglesite	PbCl2
		Galena	PbS
7	Phosphorous (P)	Floreopetite	3Ca3(PO4)CaFe2
		Phosphorite	Ca3(PO4)CaFe2
8	Potassium (K)	Karnalite	KClMgCl6H2O
		Salt Petre	KNO3
9	Magnesium (Mg)	Dolomite	MgCO3CaCO3
		Karnalite	KClMgCl26H2O
10	Mercury (Hg)	Calomel	Hg2Cl2
		Cinnabar	HgS
11	Silver (Ag)	Silver Glance	Ag2S
12	Sodium (Na)	Rock Salt	NaCl
		Sodium Carbonate	Na2CO3
13	Tin (Sn)	Classiterite	SnO2