Preparation of uniform black powder granules

DETAILED DESCRIPTION We claim: 1.
A method for the production of black powder granules of a given uniform grain size comprising compressing black powder meal, coarse crushing the compressed black powder and grinding the coarse ground black powder particles with little relative movement of the particles to each other in a gap between a conical, spirally grooved rotor and a conical, oppositely spirally grooved stator.
2.
The method of claim 1 in which the said gap is continuously adjustable for variation of grinding fineness.




Description:
STATE OF THE ART The known method for producing black powder granules of a given size comprises compressing the black powder dust or meal consisting of potassium nitrate, sulfur and carbon, coarse crushing the compressed black powder with a crusher and grinding the crushed black powder in a roller mill which normally consists of three pairs of rollers which have progressively narrow gaps from the charging end to the finish end with a connecting conveyer bottom.
The grinding is thereby effected so that the coarse crushed, compressed black powder is ground in steps as it passes through each pair of rollers which results in the formation of a relatively high proportion of black powder meal which must be recycled.
The yield of useable black powder of the so-called good grain is relatively low per pass.
The stepwise grinding has been employed because the gap of a pair of rollers can be made narrower than the gap of the preceding pair of rollers only by a certain amount to enable feeding a relatively large amount of material into the roller gaps without jamming.
When it is desired to change the grain size of the final black powder, major adjustments are necessary because of the series connection of the several roller pairs or several preset rollers mills must be provided to obtain black powder of different grain sizes.
Another disadvantage of the known method is the large amount of floor space required if several different roller mills are installed and even if a single roller mill with several conventional roller pairs is used