[D8949AAG], Letter from J W McGenniss to John Birkinbine, January 24th, 1889


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[D8949AAG], Letter from J W McGenniss to John Birkinbine, January 24th, 1889

Editor's Notes

Since my exceedingly interesting visit with you to Mr. Edison's Laboratory it has occurred to me that his remarkable process of separation might be used to advantage in reducing certain losses in Rolling Mill practice which are at present endured for want of a proper cure.##In the Bessemor Department the slag from the Speigel cupolas contains often as high as 25% Metallic Maganese, part of which is present I suppose as compound silicate and part as "Shot," which I think could be readily recovered.##Of course the amount of this slag is comparatively small, but where a mill has need of a separator for other purposes the Spiegel slag could be saved until a sufficient quantity had accumulated to make it worth while to run it through. There is too a loss in what is known as "ladle" slag often amounting to 30% of the Speigel added in the converter, -that is suppose 1.25% Mn. is desired in the steel to obtain this it would be, necessary to add an amount of Speigal 45% Spiegel equal to 5% of the metal in the converter (or a propotionally greater amount of a lower grade speigel). Of this amount of Mn. 1.25% goes into the steel and the reminder combined with various impurities goes to the slag.##Whether it would be possible to separate to the Mn. In this condition I do not know, but it might be interesting to make the trial. Then too the "Spittings" from the converter are generally carelessly swept up from the ground and in most cases are mixed with a large amount of dirt which the separator could undoubtably remove. Then in the mill the scale and mill cinder is usually collected in such a way wa to contain considerable foreign matter and as all this material is sent either to the blast or puddle furnace it could be bvastly improved by "magnetic treatment." Just what the loss is in blast furnance making Speigel I do not know, but it is not unreasonable to suppose that the slag will contain from 10 to 15% of Mn. And it would be pssible to recover at least a part of this. The Penna. Steel Co. would have all these materials and as the "Heads" in case of the Speigel slags would be worth from $25 to $50 it would probably be worth while to make the experiment.##There are no doubt many other places about individual mills where separation of desirable from undesirable could be made which would suggest themselves at once to those directly interested, and I have no doubt but that a little inquiry among mill men would develop many cases similar to those cited. I am more and more convinced of the practicability of the separator, and only hope that W.H. Walbam and C. will b e given an opportunity to dispose of part at least of the ore products.##Again thanking you for the opportunity you afforded me for meeting Mr. Edison and seeing his interesting plant I remain





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Thomas A. Edison Papers, School of Arts and Sciences, Rutgers University
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