INSPECTION AND Charter Perpetual. Issues Policies of Insurance after a Careful Inspection of the Boilers, COVERING ALL LOSS OR DAMAGE TO BOILERS, BUILDINGS AND MACHINERY ARISING FROM ESTEAM BOILER EXPLOSIONS. THE BUSINESS OF THE COMPANY INCLUDES ALL KINDS OF STEAM BOILERS. Full information concerning the plan of the Company's operations can be obtained at the COMPANY'S OFFICE, HARTFORD, CONN. OR AT ANY AGENCY. J. M. ALLEN, Pres. W. B. FRANKLIN, Vice Pres. J. B. PIERCE, Sec'y. BOARD OF DIRECTORS. J. M. ALLEN, President. CHARLES M. BEACH, of Beach & Co. NEW YORK CITY. " GEN. WM. B. FRANKLIN, Vice Pres. Colt's GEO. CROMPTON, Crompton Loom Works, HON. THOS. TALBOT, Ex-Governor of Mass. WILLIAM S. SLATER, Cotton Manufacturer, NELSON HOLLISTER, of State B'k, Hartford. GENCIES. Office, 285 Broadway. PHILADELPHIA. BALTIMORE. BOSTON, Mass. " PROVIDENCE, R. I. CHICAGO, Ill. ST. LOUIS, MO. 404 Market St General Agent. D. C. FREEMAN, General Agent. W. G. LINEBURGH, General Agent. Feb. '81 ly Knowles Patent Steam Pumps THE STANDARD. Every Variety of Steam Pumping Machinery, viz.: Knowles Steam Pump Works, 86 LIBERTY STREET, NEW YORK. BLAKE'S IMPROVED STEAM PUMPS. MORE THAN 13,000 IN USE. Improved Compound Duplex Pumping Engines for Water-Works. GEO. F. BLAKE MANUFACTURING CO., june '81 ly 88 LIBERTY STREET, NEW YORK. THE Franklin Institute is not responsible for the statements and opinions advanced by contributors to the JOURNAL. THE DIRECT MANUFACTURE OF IRON PROM ORE, OF THE PROCESS FOR COMMERCIAL IRON FOR By CHARLES M. Du Puy, C.E. Read before the Franklin Institute, June 17, 1881. I have the honor to read a third paper before this venerable and respected Institute upon the manufacture of iron. It may be remembered that in the fall of 1878 I explained a method of producing wrought iron direct from ore by reducing it with carbonaceous matter and fluxes. The mixture filled into thin sheet iron cases, and charged into reverberatory furnaces, is subjected to a gradually increasing heat for three or four hours, when it becomes changed to metal interspersed with slag, but still surrounded with the iron cases, more or less intact. One or more of these metallic lumps, pressed into the shape of a ball, is then shingled and rolled to a bar at the same heat. About 50 tons of iron was made by this method from ore, then piled, reheated, rolled, cut up, and melted in crucibles to steel. After a very careful test of this steel for various purposes, the stock was pronounced WHOLE NO. VOL. CXII.-(THIRD SERIES, Vol. lxxxii.) 1 by skillful manufacturers equal to the best American or Swedish iron for the finest grades of steel. A year later I read a second paper reporting the result of further investigation. During this interval a variety of ores had been worked. They were deoxidized not only with charcoal, as the first had been, but also with bituminous and anthracite coal. Some of these samples reduced with mineral coal, after reheating and rolling to bars, were converted to crucible cast steel and forged to tools. The result proved that whether deoxidation was produced with charcoal, with bituminous, or with the wasted anthracite coal slack dust of our mines, a high quality of steel was always produced, the tools from which have withstood the severe test of turning chilled rolls and planing hard cast iron. With this brief reference to former papers, which have been printed in your JOURNAL, I pass on to detail further progress. Since that period various practical operations have been conducted for weeks together at different rolling mills, in charging ore mixtures in sheet iron cases upon the hearths of reverberatory furnaces. After having fully demonstrated that a simple and cheap combination of fluxes with ore and carbon will always produce a uniform and satisfactory quality of metal for steel purposes, my attention has been closely directed to the commercial side of the operation. My aim has been to prove that this system can take its place in economic competition with the other older methods now in use. In the course of these experiments I discovered that sheet iron cases may be dispensed with, without prejudice to the yield and quality of the metal. This discovery is important, as it sums up a large saving in the cost of production. I early found that complete reduction in reverberatory furnaces could not be accomplished through a thickness of three or four inches of pulverized ore mixtures in as many hours, and yet, unless the process is hastened to a much shorter time, experience has proved that the waste of fuel, metal and labor will determine its commercial uselessness. It was to overcome this difficulty that annular sheet iron cases were adopted, with a thickness of not more than five inches between the outside and inside walls of the metal mixture. By this arrangement the heat was not required to travel over 2 inches in order to penetrate throughout the mass. Although sheet iron cases are now dispensed with, the mixture is still moulded by preference into cylindrical annular shapes, as the pipe form is considered best for their rapid and cheap manufacture by machinery, as drain pipe are usually made. It is quite important to have the mixture moulded to shapes, so that by standing them on end throughout the furnace hearth a sufficient paying quantity can be operated upon at one heat, while at the same time there is presented large surface areas for heat penetration. Pulverized ore mixtures, leveled over the hearths of reverberatory furnaces, have often been reduced and balled, and if not over two or three inches of thickness, iron is usually made, but as the mass is heated only from the upper surface, the bottom being cold, the prolonged high heat required to penetrate this non-conducting mixture causes excessive waste both of material and labor, together with a small yield of metal. In previous papers I attempted to explain that the greatest impediment to commercial success of direct processes has been, if I may be allowed so to express it, the failure to realize the low heat conductivity of ore mixtures. The reducing heat has been expected to penetrate more rapidly than the nature of the material will conduct it. The thin annular cylindrical shape overcomes this difficulty. They are made about 15 to 18 inches high, 8 inches diameter and 23 inches thickness, and placed throughout the hearth so as almost to touch each other. Thus arranged, the furnace will produce as much wrought iron from ore at a heat of no longer duration than is required to produce the same quantity from pig iron. It is not necessary to be confined to the annular cylindrical shape, although, perhaps, it may ultimately be found the best. Any form that may be easily handled-that will have sufficient base to afford a firm support in the furnace—and that will be thin enough to present large surfaces for heat penetration, will answer the purpose. They may be moulded to form on end, the shape of the letter C, a cylinder almost closed. They may be S shape or D shape on end. Many forms may suggest themselves, as easily moulded by machinery, which will be thin, and yet present large surface areas for penetration. Formerly, in making my experiments I used reverberatory furnaces with sand bottoms, similar to those for heating iron piles. In one respect these bottoms are favorable, for the silica becomes quite hot, and gives off its heat to the metal mixture placed upon it, but further |