942 IRON 



Sommorostro brown haematite, containing about 65 per cent, of iron. The gasos were 

 generated from oak- and beech-wood charcoal. The iron was obtained in spongy 

 masses, having the form of the pieces of ore from which they were reduced. The 

 sponge was protected from oxidation by cooling under charcoal-dust. Three charges 

 were worked daily; these consisted in tho aggregate of 72 cwts. of ore, with 18 cwts. 

 of charcoal, and produced 26J cwts. of iron-sponge. Gurlt's fusion-furnace was not 

 employed at Bolueta, but the sponges were weldedin the Catalan forgo. Every 100 Ibs. 

 of finished bar-iron represented a consumption of 285 Ibs. of raw ore, and 174 Ibs. of 

 wood-charcoal. It is maintained that the loss of iron is compensated by the saving in 

 fuel ; hence the process has been recommended where fuel is dear, and a supply of 

 pure and porous ores is readily accessible. 



Sicmcns's processes for the direct production of malleable iron. Tho production of 

 wrought iron or steel directly from the ore has recently been brought prominently into 

 notice by Mr. Siemens, who has adopted several methods based upon the use of his 

 regenerative gas-furnace for this purpose. The following are some of the methods 

 employed, as described by the inventor : 



A Method of producing spongy iron by means of a rotative furnace. This furnace 

 consisted of a long cylindrical tube of iron of about 8 feet diameter, mounted upon 

 antifriction rollers ; the brick lining of it was mounted with longitudinal passages for 

 heating currents of air and gas, prior to their combustion at the one extremity of the 

 rotary chamber. The flame produced passes thence to the opposite or chimney end, 

 where a mixture of crushed ore and carbonaceous material was introduced. By the 

 slow rotation of this furnace, the mixture advanced continually to the hotter end of 

 the chamber, and was gradually reduced to spongy iron. This dropped through a 

 passage constructed of refractory material on to the hearth of a steel melting furnace, 

 where a bath of fluid pig-metal had been provided. The supply of reduced ore was 

 continued till the carbon in the mixture was reduced to the minimum point before 

 indicated. The rotation was then arrested to prevent further descent of reduced ore ; 

 spiegel was added, and the contents of the melting-furnace tapped into a ladle, and 

 thence into ingots, 



This rotary furnace was erected by Mr. Siemens at the Landore Works, in 1869, and 

 it was so far successful, as the reduction of the ore was accomplished in a compara* 

 tively short time. A difficulty, however, presented itself, which led to its immediate 

 abandonment ; it was found that the spongy metal produced absorbed sulphur from 

 the heating gases, and was rendered unfit for the production of steel ; the spongy iron, 

 moreover, upon its introduction into the steel melting furnace, floated upon the metallic 

 bath without being readily absorbed into it, and was in great part reoxidised and 

 converted into slag by the action of the flame in the furnace. 



These experiments proved that the successful application of reduced ores could not 

 be accomplished through their conversion into spongy metals, and fully explained the 

 want of success which had attended the previous efforts of Clay, Chenot, Yates, and 

 others to produce iron directly from the ore. On the other hand, Mr. Siemens observed 

 that in melting iron ores no sulphur was absorbed from the flame ; and it occurred to 

 him that by melting ores mixed with fluxing materials in a furnace so arranged as to 

 accomplish its fusion in a continuous manner and on a largo scale, the fused ore might 

 be acted upon by solid carbonaceous matter, so as to separate the metallic iron in a 

 more compact form, while the earthy constituents of the ore would form a fusible slag 

 with the fluxing material. Experiments proved that this reduction by precipitation 

 of the iron could be accomplished only at an intense heat, exceeding tho welding heat 

 of iron, but that the iron so produced was almost chemically pure, although tho ores 

 and the fuel used might contain a very considerable percentage of sulphur and phos^ 

 phorus. 



The furnace used for carrying out this process of fusion and precipitation consists 

 of a reverberatory gas-furnace, having two bods formed by tho ore itself : on the 

 upper bed a lake of fused ore is formed, which can be let off into tho lower bi-d ly 

 piercing the intervening bank of unfused ore ; tho lower bed is divided into two 

 compartments, each provided with a door, uecd alternately. Tho dense carbonaoeool 

 material, such as anthracite or hard coke, to bo \ised for the precipitation of the iron 

 in the lower bed, is reduced to a state of powder and mixed with about ;m equal 

 weight of pulverulent ore. This mixture is spread over tho bottom surface of the 

 working bed, and tho fluid ore is let in upon it. By stirring with a rabble it is 

 transformed into a pasty and foaming mass, which in the course of from 40 to 60 

 minutes is shaped into a metallic ball in n. bath of fluid cinder, which may l>o 

 shingled in tho usual manner and formed into bar-iron, or transferred to tho pig- 

 iron bath of a steel melting furnace, where it readily dissolves. Tin; accomplishment 

 of this process involves, however, a certain dogreo of manual labour and skill, as, 

 if it bo carelessly conducted, the yield of iron will bo unsatisfactory. Tho analysis 



