US 734240 A
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UNITED STATES retested i ly 21, 1908.
GEORG CARLPROPFE, OF HAMBURG, GERMANY.
PULVERIZING AND CLEANING MINERAL S.
SPECIFICATION forming part of Letters Patent No. 734,240, dated July 21, 1903.
Application filed November 18, 1902.
To aZZ whom it may concern.-
Be it known that I, GEORG CARL PROPFE, a
subject of theGerman Emperor, residing at Hamburg,Germany, have invented a new and useful Process of Pulverizing and Cleaning Minerals, of which the following is a specificrackling is only slight and the mineral remains in pieces. I have found that with many kinds of fluor-spar the mineral falls completely into powder fine as dust. Many kinds of fluor-spar and many parts of the fluor-spar do not, however, fall hereby, as I have also found out, because they contain silica and sulfate of calcium or on account of other foreign matter. I have applied these observations to the method of pulverizing and eventually at same time cleaning fluor-spar, which further becomes white by this method of pulverizing. It is well known that in consideration of their value the grinding of such minerals is rather costly, as the mills suffer much wear and tear from the mineral, so that also in this respect the method described below offers considerable advantages.
The method of pulverizing and eventually at same time cleaning fluor-spar is as follows:
1. In working comparatively pure I fluorspar the mineral is heated till a noise is no longer heard audit is ascertained by drawing samples that the mineral has been completely or almost completely transformed into fine powder. Avoid too great heating, by which the mineral melts. The heatingis then interrupted. Should it be deemed necessary,
owing to the purpose of application, the cooled powder is separated from the pieces still in it--for instance, by means of sieves. If necessary,the pieces remaining on the sieves can be ground by themselves.
2. With such fluor-spar as is mixed with quartz, silicates, or sulfate of calcium it is first treated as explained under 1. If such mixed fiuor-spar is to be cleaned, separate the pow- Serial No. 131,901. (No specimens.)
der from the pieces by means of sieves or in any othersuitable manner. In this way a considerably cleaner fluor-spar in powdered form and an unclean fluor-spar in pieces is obtained. The latter may eventually be ground and applied to suitable purposes.
The importance of the method described above from an industrial point of view consists therein that only by this method can the most of the impurities to be found in floor-spar, in particular the disturbing silicates which interfere with the manufacture of hydrofluoric acid, be separated from the fluor-spar parts, and even lower qualities of the mineral can be turned into a good product. For most purposes for which fluor-spar is used the pulverized mineral can also be better used. Therefore the pulverizing by heating without at the same time cleaning is of itself of technical value.
I have further found that many other minerals behave in the same manner as fluor-spar on being heated or made red-hotfor instance, sulfate of barium and some minerals which contain ore. The method of pulverizing these minerals is the same as that described for fluor-spar. 7
It is hereby also possible-for instance,with sulfate of barium-to separate the mineral from foreign matter by separating the powder formed from the pieces by means-of sieves or some similar process. From this the general applicability of the method for various minerals which crackle on being heated or made red-hot is apparent.
Having thus fully described my invention, what I claim as new, and desire to secure by Letters Patent of the United States, is
The process herein described for pulverizing and cleaning minerals consisting in subjecting the mineral to the action of heat, whereby it is pulverized, cooling the powder thus obtained, and finally cleaning the powder by separating all lumps of mineral and all impurities by means of sieves, substantially as described.
In witness whereof I have hereunto set my hand in presence of two witnesses.
GEORG CARL PROPFE.
E. H. L. MUMMENHOFF, OTTO W. HELLMRICH.