IMPROVEMENTS IN PUDDLING.
A few years ,ago, the pig metal was always refined in the finery-furnace by the pneu matic process before use in the puddling-furnace. It has been found practical and more economical, however, to deoxidize the metal at one process by "boiling" it in the pud dling operation. This simply consists in the rapid ebullition of the gases produced by the more highly carbonized and, consequently, more fluid cast iron. The "boiling" process is more tedious and laborious than common puddling of refined metal, on account of the stirring necessary to burn out the larger amount of carbon in the pig metal.
Mr. Hall, of the Bloomfield Iron-Works, Tipton, England, first introduced the boiling process about thirty years ago.
Mr. James Nasmyth patented an improved process of puddling in 1854, which con sists in the introduction of a small quantity of steam at a low pressure into the molten metal on the hearth of the furnace as soon as melted. The steam has both a mechanical and chemical action on the. iron : being introduced at the bottom of the melted metal, the steam is instantly rarefied and diffused upwards, violently agitating the iron and causing the exposure of fresh surfaces to the oxygen passing through the furnace and the action of the steam.
The mode of applying the steam is by means of a small pipe, bent at the end, which enters the furnace for the purpose of passing down through the melted metal. This pipe is held horizontal by the puddler, and is swung on a ball-joint, which connects with a perpendicular pipe leading from the boilers. The workman can thus pass the
horizontal steam-pipe over the entire hearth of the furnace. So rapid is the operation of steam, thus applied in decarbonizing the metal, that in the course of eight or ten minutes the mass begins to thicken, and the operation is then finished by the "rabble" of the puddler. The time saved by this simple process is considerable, and that during the hottest and most laborious part of the process. It is possible this mode of puddling may be superior to the machinery formerly described, and in connection with the gas puddling-furnace, which has been in use in Silesia, Germany, for twenty-four years with great success, the operations of decarbonizing pig metal in the puddling-furnace would be much simplified and economized.
The Silesian gas-furnace is much the same as the common reverberatory furnace, except that it is much larger, and that the fireplace is occupied by a gas-generator cn the Siemens principle, which gives an intense heat and saves 33 per cent. of the fuel, while the puddling process is shortened and simplified.
In these furnaces the decarbonization is effected by the pneumatic process, the air being blown into the metal from each side of the furnace, on the same principle first applied in the Bessemer converter,—the charges being about 40 cwt. instead of 4 and 5 as used in hand-puddling. The make is improved, while the saving of metal, fuel, time, and labor is very great.