584 
MANGANESE DEPOSITS OF INDIA: ECONOMICS. [PaRT III : 
Ferro-manganese contains 27 to 86% (or sometimes even 90) of manga- 
nese and 6 to 7% of carbon. Standard ferro-manganese contains 80% 
manganese. [ According to 0. Simmersbach^, on passing above 27% of 
manganese, the Fe — Mn, alloys loose their magnetic properties and 
assume different crystalline characters.] 
According to Penrose^ : — 
' Spicgeleisen was formerly made by using a manganiferous iron ore in a blast- 
furnace, or by inserting small quantities of manganese 
Manufacture of spiegeleisen ... " , ° ' , .1 
and ferro-manganese. ^ 'be iron ore charge. vVnen the amount of man- 
ganese became large, however, great difificulties were 
experienced on account of the high temperatures required to smelt the metal and 
the loss due to the combination of the manganese with the slag. The more manga- 
nese contained in the charge the higher the temperature that is required, and a white 
heat is needed to reduce oxide of manganese alone. Consequently, in the early 
manufacture of ferro-manganese, the metal was reduced either in graphite crucibles 
as in Prieger's method in Germany, or in a Siemen's furnace as in the Hender.son 
method in England, which was later improved by the Terre Noire Company of 
France. These processes were expensive, the loss was considerable, and the product 
limited. More modern appliances, however, and greater experience in the use 
of manganese -ores have considerably facilitated the reduction of the metal, and now 
ferro-manganese is readily made in any properly arranged blast-furnace, with a 
high temperature and a strong hot blast. Coke is the best fuel, as it admits of a 
sharper blast and gives a stronger heat, but charcoal can be used, and Wm. P. 
Blake describes the manufacture of ferro-manganese with that fuel from a highly 
siliceous ore at Reschitza, in Hungary. 3 The other desirable features in the process 
besides those mentioned are : a highly basic slag, secured by large charges of lime ; 
an abundance of fuel ; and sufficient time. The basic character of the slag causes 
the saving of a considerable part of the manganese, which with a less basic, or an 
acid slag, would combine with the latter and be lost. If the slag is too basic, how- 
ever, other difificulties are met ; and even with all precautions, a loss of 4 to some- 
times over 15 per cent of manganese, the quantity varying according to the amount 
of the metal in the product to be obtained, is often sustained in smelting the ores' . 
According to 0. Simmersbach, in the article already cited, while 
100% (of the metal obtained) of coke is required for the reduction 
of iron, 250% is required for the reduction of manganese. The charge 
must be calculated so that the oxygen of the earthy bases, lime, magnesia, 
and alumina, is at least as great as the oxygen of the silica. A certain 
proportion of barytes or flour-spar is also necessary, according to seme 
authorities. A practical rule for fluxing given by Phillips and Bauerman^ 
is to give twice as much lime (in the form of limestone) and J as much 
1 ' Uber die HersteUung von Ferromangan', Berg- und Hultenrndnnische Rundschau, 
I, pp. 305-308, (1905) ; abstract in Trans. Min. & Geol. Insl. Ind., I, pp. 133-135, (1906). 
2 Lnc. cit, p. 1 1. 
3 Trans. Amcr. Inst. Min. Em/., IV, p. 217- (1875-187G), 
4 ' Elements of Metallurgy,' (1891), p. 286. 
