210 



DEPHOSPHORIZATION OF IROK 



been completed. Its rapid combustion is the 

 cause of the high temperature at the end of 

 the process. After the reduction of the sili- 

 con, and while the carbon is being reduced 

 from 2'72 to 0'16 per cent., the diminution of 

 the phosphorus is only from 1*32 to 1*18 per 

 cent. Then a rapid combustion of phosphorus 

 takes place, leaving only a trace. The Ger- 

 mans succeed in more completely dephosphor- 

 izing pig-iron than the English. In the Hoerde 

 works pig containing 2*75 per cent, carbon in 

 combination, 0'50 per cent, manganese, 0'9 per 

 cent, silicon, 0'31 per cent, sulphur, 1-51 per 

 cent, phosphorus, gave on analysis after three 

 minutes' afterblow 0*13 per cent, of phospho- 

 rus, and in twenty-five seconds longer O'lO per 

 cent., with 0*17 per cent, manganese, 0'12 per 

 cent, sulphur, and of carbon a trace; and 

 after the addition of the spiegeleisen the steel 

 produced gave 0'19 per cent, of carbon, 0'57 

 per cent, of manganese, O'lO per cent, of sul- 

 phur, and 0-10 per cent, of phosphorus. In 

 Bolckow, Vaughan & Co.'s works a new six- 

 ton converter is in use, especially adapted to 

 this process. The lime and iron are lifted up 

 by the force of the blast, but do not cling to 

 the nose of the converter, and the metal can 

 be poured into the converter when turned 

 upon its side. The converter is first heated 

 with coke, then about 16 per cent, of the 

 weight of the metal of well-burned lime mixed 

 with some coal is put in and blown until well 

 heated, and then the molten pig-iron is poured 

 in, and a blast of twenty -five pounds' pressure 

 is turned on. It is decarbonized in about ten 

 minutes. The method of sampling is still used 

 in these works. After two and a half minutes 1 

 afterblow a sample is taken out, beaten into a 

 sheet, cooled, and broken. If not ductile 

 enough, the blast is continued some time longer 

 before the spiegel is added. Another process 

 is in use in the same establishment, which can 

 be applied to Cleveland pig of different quali- 

 ties, while special grades are required for the 

 other. This is called the transfer system. The 

 metal is desiliconized in a converter with a 

 silicious lining, and then poured into another 

 with a dolomite lining, the silicious slag being 

 carefully kept out, in which the afterblow of 

 about three minutes is conducted, enough lime 

 having been placed in the converter to absorb 

 the phosphorus. Not expecting that the basic 

 lining will through any improvements in the 

 process become as lasting as the silicious lin- 

 ing, Mr. Holley, who has adopted the basic 

 process in the United States, has devised an 

 apparatus which works by means of an hy- 

 draulic ram, by which the converter-shells can 

 readily be lifted off their trunnions and newly 

 lined ones set in. The acid lining was not 

 brought up to its present state of perfection 

 without passing through a long period of ex- 

 perimentation and gradual improvement. The 

 acid linings also are subject not only to wear 

 from the mechanical action of the charge, but 

 are chemically attacked by the various slags. 



The silica linings have been perfected to the 

 point where sixty charges can be got out of 

 each pair of converters in twenty-four hours. 

 This is their duty in the Bessemer works of the 

 United States, where appliances have been de- 

 vised for rapidly shifting interchangeable con- 

 verter-bottoms, and for removing a burned-out 

 converter, and placing a new-lined one on the 

 trunnions, which are not yet introduced in Eu- 

 rope. The repairing of the fixed linings just 

 above the tuyeres, and the removal of the in- 

 crustations of slag which accumulate on certain 

 parts of the lining, are the main problems in 

 maintaining acid linings in order ; and the con- 

 ditions of the basic lining are precisely similar, 

 only the chemical decomposition is much more 

 rapid and general, so that the difficulties are 

 increased about threefold. The bottoms and 

 tuyeres employed in the basic process can stand 

 ten to fifteen charges, being nearly equal to the 

 silica bottoms ; but the lining near the tuyeres, 

 and in other parts of the converter, is soon 

 eaten out by the decay and abrasion ; and the 

 converter must frequently be cooled off, and 

 the lining repaired by inserting new bricks, or 

 by patching, occasioning a stoppage of twenty- 

 four hours, which is a more serious drawback 

 in the United States than in Europe, where the 

 average output of Bessemer converters is less 

 than half that of American steel-works, and 

 where the plant can be suffered to lie idle dur- 

 ing the repairs of ordinary converters, whereas 

 American iron-masters are obliged to employ 

 mechanical contrivances to keep their whole 

 force and plant busy every hour. The basic 

 lining is seldom run above sixty charges with- 

 out a thorough overhauling being necessary; 

 and some of them must be repaired every time 

 a new bottom is set. The adaptation of the 

 basic process to American methods, until the 

 basic materials can be obtained with enduring 

 qualities equal to those of the acid linings, re- 

 quires a contrivance of the nature of that 

 devised by Holley, by which converters that 

 are disabled can be replaced without loss of 

 time by sound ones. Holley's converting plant 

 differs from a system which is being tried in 

 the Cleveland Steel "Works, by Richards, in 

 that the latter apparatus is designed to trans- 

 port the entire converter, taking it off the pil- 

 low-blocks and conveying it, by means of an 

 overhead traveler, to the repair-shops, replac- 

 ing it by a fleshly-lined converter by the same 

 apparatus; while Holley contemplates making 

 the shell of the converter detachable, and lift- 

 ing it out rapidly by a lift, lowering it to the 

 ground-level, and rolling it to the repair-shop 

 in a car. 



In many parts of the United States phos- 

 phoric ores, adapted to the basic process, are 

 abundant, and usually very cheap. In some 

 districts, especially in the South, they are com- 

 mon in the same localities in which coal and 

 excellent dolomite are found in great quanti- 

 ties. The occurrence of all the materials for 

 cheap steel-making in immediate proximity in 





