390 



METALLURGY. (PROCESSES AND APPARATUS.) 



in such a way that leakage of water into the fur- 

 nace is prevented. When a tuyere becomes dam- 

 aged or leaks, instead of water entering the 

 furnace, air tends to enter the tuyere and to de- 

 stroy the vacuum, and the molten iron and slag 

 usually close up the hole immediately. The vacu- 

 um system possesses several collateral working 

 advantages, among which is the rapidity with 

 which a defective tuyere can be removed and 

 replaced by a sound one. 



Electrical furnaces are described by C. E. Ja- 

 cobs having pure carbon block linings, reenforced 

 by magnesia or chalk blocks or other poorly 

 conducting material, with which a temperature 

 approaching 4,000 C. may be obtained and com- 

 mercial work carried on at temperatures of from 

 2,500 to 3,000 C. In such furnaces at high 

 temperatures silicids of the alkali-earth metals 

 CaSi 2 , BaSi 2 , and SrSi 2 are formed when oxids, 

 carbonates, sulfates, or phosphates of the metal 

 are mixed with silica in suitable proportions 

 with carbon to reduce them; or by mixing al- 

 kali-earth silicates with carbon. These sili- 

 cids are white or bluish-white, with metallic 

 appearance, oxidize slowly, and decompose water 

 with evolution of hydrogen. With dilute hydro- 

 chloric acid, calcium silicid forms calcium chlo- 

 rid and silico-acetylene Si 2 H 2 as a yellow 

 crystalline solid. When heated in a close tube 

 these substances give hydrogen and amorphous 

 silicon. Barium silicid treated with water is a 

 cheap and convenient source of hydrogen when 

 it is desired to obtain that gas on a large scale; 

 and is efficient in operations of reduction. It 

 can be used in perfectly neutral solutions. Melt- 

 ed with iron containing sulfur or phosphorus, the 

 alkali-earth silicids form sulfids or phosphids 

 of the alkali metal, while the silicon unites with 

 the iron. By oxidation the sulfids or phosphids 

 become sulfates and phosphates, and pass injo 

 the slag; and it is represented that in this way 

 sulfur and phosphorus have been entirely re- 

 moved from iron. 



An electric furnace for steel smelting was com- 

 pleted at Gysinge, Sweden, in 1900, and on the 

 experimental trial was found to produce steel of 

 excellent quality, but not on the scale then 

 adopted. Larger furnaces, working on a commer- 

 cial scale, have since been erected. The steel 

 produced is described by F. A. Kjellin, engineer 

 of the works, as being of superior quality and 

 characterized by strength, density, uniformity, 

 toughness, and ease of working in a cold, unhard- 

 ened condition, even when containing a very high 

 percentage of carbon. Compared with other 

 steels it has less tendency to crack or warp when 

 hardened. The manufacture of special steels, as 

 nickel, chrome, manganese, or wolfram, is not 

 considered likely to meet with any difficulties. 

 The chrome steel and wolfram as produced at 

 Gysinge have proved to be excellent for lathe 

 tools. When used for permanent magnets, the 

 Gysinge wolfram has been found to give stronger 

 magnets than other wolfram steel, and has not 

 wasted in the hardening. The furnace also prom- 

 ises to be economical in operation. 



The Chartier oil-melting brass-furnace consists 

 of a cylindrical iron casing lined with fire-brick, 

 set on axial trunnions, turned by a hand wheel, 

 fed at one end by an oil air-burner. The products 

 of combustion pass out through a hopper into 

 which the brass to be melted is dropped. With oil 

 at 4 cents a gallon, the cost is 15 cents per hour. 

 Natural gas may be used. The furnace at the 

 J. W. Paxson Company's mills, Philadelphia, 

 melts (300 pounds of copper-tin bronze ingots in. 

 one hour, and 600 pounds of turnings in two hours. 



Processes and Apparatus. The Stassano 

 electrometallurgical process aims at replacing the 

 heat of the combustion of coal in the ordinary 

 metallurgy of iron by the electric arc. The 

 roasted and powdered ore is first passed through 

 a magnetic separator in order to prepare a ma- 

 terial rich in iron. This is analyzed, and the 

 amount of carbon required for its reduction is 

 calculated. The mineral is next mixed with the 

 necessary amount of powdered wood charcoal and 

 tar, the percentage of carbon in which is known, 

 and a slag-forming material, and is made into 

 briquettes. These are then introduced into the 

 electric furnace. The chemical reaction is at first 

 very lively, but becomes quieter after a time, and 

 the amount of heat necessary continually de- 

 creases. A furnace of 150 horse-power will yield 

 in from one-half to three-quarters of an hour 

 nearly 30 kilograms of wrought iron. By varying 

 the amount of carbon added according to the 

 analysis which has been made previously, it is 

 possible to prepare a cast-iron of a certain fixed 

 percentage of carbon. A plant is at present work- 

 ing at Darfo in the province of Brescia, Italy, 

 and uses a fall of 30 meters of 5 cubic meters of 

 water per second. 



In a new welding process by S. Baldy, Sr., of 

 Chester, Pa., a master-mold having been made 

 from the original pattern, a number of fusible 

 patterns are cast in it. The fusible pattern is 

 then put into an iron flask, which is filled with 

 sand by means of compressed air. On exposure in 

 the drying-oven, the fusible flask is melted out, 

 after which the casting is made in the dried mold. 

 Skilled labor is not required in this process, and 

 the resultant castings are seamless and without 

 fins. It is practicable by this process to produce 

 utensils in exact duplicate. 



In the process of Petersky and Ivanoff for 

 utilizing petroleum in the production of pig-iron 

 in connection with a certain amount of solid fuel, 

 the solid fuel is placed in a special generator, into 

 the lower part of which the treated gases from 

 the combustion of petroleum are introduced. The 

 fuel charged from above gradually falls to the 

 bottom and becomes heated. Dry distillation re- 

 sults, and the gaseous products are drawn off 

 from the upper part of the generator and utilized 

 for fuel, while the resulting coke continues to 

 descend. The products of combustion entering the 

 lower part of the generator pass over the in- 

 candescent coke, are deoxidized, and are thus 

 available as reducing agents which can after- 

 ward be used in a second furnace. This furnace, 

 which is used for producing iron, resembles an 

 ordinary blast-furnace, from which it differs 

 merely in having a tube running down the center. 

 The ore and fluxes are placed in the space between 

 the walls of the furnace and the central tube, the 

 latter being chargod with a quantity of coal suf- 

 ficient to supply the iron with the requisite 

 amount of carbon for converting it into pig-iron, 

 and also, if necessary, with fluxes for changing 

 the composition of the slag. 



As an example of a new departure in the 

 processes by which the materials used by engineers 

 are formed into machines or tools, Mr. W. J. 

 Taylor, in the British Association, instanced the 

 formation of a milling cutter between 3 and 4 

 inches in diameter, with deep teeth on its 

 periphery and on both faces. This cutter had been 

 formed cold from a blank of tool steel by hy- 

 draulic pressure, and was said to serve its pur- 

 pose as well as any cutter milled from a solid 

 blank. In operations of this nature, time was of 

 considerable importance. Some remarkable work 

 had been done, in cycle-making and other in- 



