Peat and its Uses as Fertilizer and Fuel

by Samuel W. Johnson

At Pillersee, in Austria, spathic iron ore has been reduced by a mixture of fir-wood charcoal, and air-dry peat in the proportions of three parts by bulk of the former to one of the latter. The use of peat was found to effect a considerable saving in the outlay for fuel, and enabled the production to be somewhat increased, while the excellence of the iron was in no way impaired. The peat was of the best quality, and was worked and moulded by hand.

When the ore is refractory and contains impurities that must be fluxed and worked off in slag, a large proportion of air-dry peat cannot be used to advantage, because the evaporation of the water in it consumes so much heat, that the requisite temperature is not easily attained.

At Achthal, in Bavaria, air-dry peat was employed in 1860, to replace a portion of the fir wood charcoal, which had been used for smelting an impure clay-iron-stone: the latter fuel having become so dear, that peat was resorted to as a make shift. Instead of one "sack," or 33 cubic feet of charcoal, 24 cubic feet of charcoal and 15 cubic feet of peat were employed in each charge, and the quantity of ore had to be diminished thereby, so that the yield of pig was reduced, on the average, by about 17 per cent. In this case the quality of the iron, when worked into bar, was injured by the use of peat, obviously from an increase of its content of phosphorus. The exclusive use of air-dry peat as fuel in the high furnace, appears to be out of the question.

At Ransko, in Bohemia, kiln-dried peat, nearly altogether free from water, has been employed in a high furnace, mixed with but one-third its bulk of charcoal, and in cupola furnaces for re-melting pig, full-dried peat has been used alone, answering the purpose perfectly.

The most important metallurgical application of peat is in the refining of iron.

Dried peat is extensively used in puddling furnaces, especially in the so-called gas puddling furnaces, in Carinthia, Steyermark, Silesia, Bavaria, Wirtemberg, Sweden, and other parts of Europe. In Steyermark, peat has been thus employed for 25 years.

Air-dry peat is, indeed, also employed, but is not so well adapted for puddling, as its water burns away a notable quantity of iron. It is one of the best known facts in chemistry, that ignited iron is rapidly oxidized in a stream of water-vapor, free hydrogen being at the same time evolved.

In the high furnace, peat-coal, when compact and firm (not crumbly) may replace charcoal perfectly, but its cost is usually too great.

When peat or peat-coal is employed in smelting, it must be as free as possible from ash, because the ash usually consists largely of silica, and this must be worked off by flux. If the ash be carbonate of lime, it will, in most cases, serve itself usefully as flux. In hearth puddling, it is important not only that the peat or peat-coal contain little ash, but especially that the ash be as free as possible from sulphates and phosphates, which act so deleteriously on the metal. The notion that, in general, peat and peat charcoal are peculiarly adapted for the iron manufacture, because they are free from sulphur and phosphorus, is extremely erroneous. Not infrequently they contain these bodies in such quantity, as to forbid their use in smelting.

In the gas-puddling furnace, or in the ordinary reverberatory, impure peat may, however, be employed, since the ashes do not come in contact with the metal. The only disadvantage in the use of peat in these furnaces is, that the grates require cleaning more frequently, which interrupts the fire, and, according to Tunner, increases the consumption of fuel 8 to 10 per cent., and diminishes the amount of metal that can be turned out in a given time by the same quantity.