[D8845AGO], Letter from Malvern Wells Iles, Holden Smelting Co to Thomas Alva Edison, December 12th, 1888


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[D8845AGO], Letter from Malvern Wells Iles, Holden Smelting Co to Thomas Alva Edison, December 12th, 1888

Editor's Notes

[TAE marginalia: "Write for 10 lb samples we say we will see what can be done." E] "In a brief conversation with Mr. P.D. Dyer, Agent for the 'Western Edison Electric Light Co:, I learned to-day that you have made some experiments for the thorough pulverization of ores and similar substances by electric appliances, and that you had in a measure been successful in the treatment of Iron Pyrites and such other metalliferous substances which were attractable by Magnets; and to-day (12th.) a copy of 'The Engineering and Mining Journal' contains a short article of the Edison Magnetic Separator, which I have perused with much interest. ### Some years ago (1879) I discovered whilst working upon Leadville slags both chemically and mechanically some very interesting properties which is the cause of the present letter. ### I found that the slag I was then operating upon was markly magnetic, that is to say a certain portion of it. I extended my observations until it included a test upon all the slags then being produced by the ordinary process of argentiferous lead smelting. Every slag I have been enabled to find made in various sections of the United States shows this same property. ### By taking finely powdered slag which has passed through the ordinary 80 mesh sieve and passing a horse shoe magnet through the slag, magnetic particles are readily extracted, and by repeating this operation a number of times there will be left entirely non-magnetic particles. I have notices by taking the entire quantity of magnetic particles and repeating the operation there is left an exceedingly small residue which is non-magnetic, showing concentration can be readily increased by repitition of the process. ### It has been demonstrated that one of the chief, and I might add, one of the main reasons why some slags contain a larger amount of silver than others is due to the fact that they contain minute particles of matte (Fe2,S.) disseminated through it. ### In the case of the Leadville slags, it has been demonstrated (by the late Mr. Anthony Guyard) that the magnetic property in Leadville slags was due to magnetite (Fe.3.0.4) In cases where much matte is produced, the writer has found that the magnetic property is due to two causes ie: magnitite and matte. The usual mattes then produced by argentiferous lead smelting being magnetic, it would seem that some advantage could be taken of this property, and I think econimically. This suggesting has been offered by Mr. O.H. Hahn in the Mineral Resources of the United Stares for 1883 and 1184. ### By thorough pulverization of our slage I find but little difficulty in concentrating the matte particles by means of water, and such concentrates have the lustre and other physical properities of the usual iron sulphide. I might add that I have operated upon a large quantity and find this concentration to be entirely practical and is complete. My idea is in a few words may be briefly stated as follows: ### Finely powder the slags which are thrown away in the usual slag dumps by means of either electrical appliances or the ordinary stamp mill. As a perliminary pulverization the slags can be partially granulated by pouring whilst fluid into large basins or large receptacles of water which will materially lessen the cost of pulverization; then by means of powerful magnets and of the mode you have already partially developed to extract both the magnetite and the artificially as formed iron sulphide, known to the smelters, as matte. In the first place the magnetite would be valuable as a flux and the matte is certainly the main carrier of the silver existing in the slags. This we have demonstrated by experiments extending over a period of eight months. By a series of experiments in order to ascertain whether it were possible to form by the blast furnaces practice the so-called silicate of silver, I will add, however, that we were unable to obtain such a compound, an believe its existence is yet to be demonstrated. ### You will readily see that by the extraction of magnetite and matte that the most valuable constituents contained in slags would be effectually extracted. ### There are of course, various methos now in use for catching or saving the major portion of the matte produced by the silver lead smelters. ### Without going into details I may briefly say the methods are to break off the matte-cake from the bottom portion of cones of sollidified slag or to catch the matte in various forms of settling pots or basins (which the Germans term fore-herths) or by some of the recently patented appliances called matte-pots or improved slag pots. I will say, however, that they are all crude and imperfect and the aggregate loss of silver in this country per annum is something very startling. ### It would not be my idea to use magnetic appliances except for slag dumps, yet I have no doubt but what electricity could aid us in the more thorough extraction of matte from the slag whilst it was still in the molten condition. ### In conclusion I will say that should you ever come to Denver, I will be glad to show you through our works and endeavor to more fully convey to you some data, which I fear I have poorly succeeded in doing in this letter. ### If you would like to look into this matter, I will be pleased to send you ample slag or matte for experimentation. If you think this field sufficiently profitable to look into, I should be glad to take active steps in this direction and still further confer with you about the subjects detailed above." Very truly yours, Malvern W. Iles




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