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MVTfGAXESE DEPOSITS OF INDIA: ECONOMICS. [P ART III 
have a low heating power owing to the surplus oxygen burning CO to C02- 
In this case it may be necessary either to add bituminous coal to the 
charge to furnish gas for the boilers and stoves, or to calcine the ore 
beforehand to reduce the Mn02 to MngO^.. 
Ferro -manganese has of recent years also been manufactured in 
the electric furnace. One of the drawbacks of ferro-manganese for some 
purposes is the large amount of carbon it contains. A recent paper by 
Messrs. E. G. L. Roberts and E. A. Wraightl, entitled ' The Preparation 
of Carbon-free Ferro-manganese ', describes experiments carried out to 
determine the commercial possibility of refining ordinary ferro-manganese ; 
the authors consider that the most hopeful method consists in treating 
the molten alloy with manganese oxide. The paper is valuable for the 
review it gives of the attempts to make metallic manganese and to manu- 
facture and refine ferro-manganese. 
I have given the foregoing brief account of the manufacture of ferro- 
manganese, because the question of the manufacture of this alloy in India 
has already arisen, and because it is very difficult to get any definite 
information on the subject. The details of the manufacture seem to 
be more or less secret. From the figures given above, however, we can 
form a rough idea as to the possibility of manu- 
manganesf irindia. facturing ferro in India. Let us take the aver- 
age ore of the Central Provinces to contain : — 
Manganese . . . . . . . . . . 52 
Iron . . . . . _ , _ . . 7 
Silica .. .. .. .. .. 6| 
Phosphorus . . . . . . . . . . O'lO 
Assuming that the loss of manganese in smelting this, without admixture 
with any other ores, would be 20%, then the composition of the ferro 
obtained would be : — 
Manganese . . . . . . . . . . 79'2 
Iron . . . . . . . . . . 13-3 
Carbon and silicon .. .. • .. ..7-5 
assuming the total of carbon and silicon to be that given in the last line. 
By picking out the less ferruginous ores the ferro-manganese could easily 
be raised to the 80% grade if this were desired. Assuming that for every 
ton of ferro-manganese 2| tons of Giridih coke would be required, then 
as this contains about 14 % of ash, which we can assume as equivalent 
to 6% of silica^, the total amount of limestone required for fluxing the 
1 Jour. Iron Steel Inst, No. II for 1906, pp. 229 286. 
2 No analyses of the ash of Indian coals seem to be available- 
