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Ferromanganese

As is the case with ferrochromium production, metallic fines are also generated by the ferromanganese industry. In addition, because molten manganese exhibits a substantial vapour pressure, the fumes produced by ferromanganese furnaces are characteristically rich in manganese oxide (Mn3O4), which has a distinctly red colour. Such metallic fines and fumes are also difficult to reprocess in conventional submerged-arc electric furnaces with the result that they are often left to accumulate on dumps where they pose a potential problem to the local environment.   

AMRT in conjunction with a major ferromanganese producer, again Samancor in South Africa, have demonstrated that one could produce a commercial grade of medium carbon ferromanganese by merely re-smelting a mixture of these two types of fine material in a melt reduction furnace. This time no carbonaceous reducing agent was included, except for some slag-modifying flux, whereupon the level of carbon dioxide present in the off gas becomes far less. The principal reaction involved was: 

Mn3O4 + 2Si = 3Mn + 2SiO2

which drew a mere 510 kWh per metric ton of dust/fume mixture in electrical energy. The experimental results appear in the following table.

AMRT melt reduction furnace technology as applied to smelting a mixture of metallic ferromanganese fines and manganese oxide fume generated by Samancor, South Africa

 

Furnace inputs

Furnace outputs

 

Metallic FeMn-Si fines (%)

MnO fume (%)

Metal (%)

Slag (%)

Gas (% by volume)

Mn

63.5

68.94

84.6

20.4

8.1

Fe

13.1

0.2

12.4

0.01

 

Si

16.5

 

0.54

 

 

Al

0.4

 

0.00

 

 

SiO2

 

1.0

 

41.4

 

CaO

0.01

0.2

 

19.0

 

MgO

0.1

0.2

 

10.0

 

Al2O3

0.2

0.1

 

1.2

 

P

0.15

 

0.07

0.2

 

S

0.02

 

0.01

0.01

 

C

2.0

1.0

2.4

 

 

CO2

0.0

 

 

 

1.0

H2O

0.0

1.0

 

 

2.8

Since the volume of off gas (furnace gas) generated in this process was substantially far less than that generated in conventional ferrochromium furnaces, the mass of manganese being volatilized was far less; although this secondary fume itself could be recycled to the melt reduction furnace.

Examples of materials that have been produced by or processed in AMRT’s melt reduction furnaces are:

Copper

Cobalt

Nickel

Tin

Zinc and lead oxide and sulphides

Ferrochromium

Ferromanganese

Ferrotitanium

Precious metal-bearing wastes

Ancillary processes and procedures associated with AMRT’s furnace operations

 
 
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