US2136205A - Blasting powder - Google Patents

Description

Patented Nov. 8, 1938 UNETED STATES PATNT OFFCE BLASTIN G POWDER Land 8. Byers,

Glendale, Calif.

3 Claims.

This invention relates to blasting powder and has for its object an improvement in explosive compositions suitable for general blasting purposes which will have important advantages over i black powder.

Among the advantages of my improved powder over blasting powder may be mentioned a lesser density with same heave or moving power, greater rate of decomposition upon explosion, more resistant to water or moisture, much less subject to ignition from shock or friction, not subject to ignition from contact with ordinary flame, no poisonous fumes, and with all cheaper and quicker to manufacture.

Briefly described my improved blasting powder may be said to comprise a loose mass of sodium nitrate kernels, each of which is entirely enveloped by an adherent layer of explosive agents adapted to form a substantially balanced fortified and sensitized entity complete itself, and exhibiting all of the characteristics above enumerated.

My improved blasting powder consists of the following ingredients:

Percent by weight 5 Pelleted sodium nitrate 90 to 80 A liquid nitro body (liquifiable at modcrate temperatures) 3 to 6 Ammonium nitrate 3 to 6 Potassium perchlorate 3 to 6 Powdered aluminum l to 2 (1) Minus 6 mesh, plus 8 mesh (2) Minus 8 mesh, plus 10 mesh (3) Minus 10 mesh, plus 12 mesh,

and so on up to minus 36 mesh, plus 40 mesh.

The finer mesh pellets are employed where increased rate of combustion or greater brisance in the blasting powder is desired, and vice versa.

This pelleted sodium nitrate is placed in a suitable tumbler or inclined rotating pellet coating bowl, and while under rotation the liquid nitro body (preferably D. N. T. or M. N. T., T. N. T.) is added to the revolving and rolling mass, preferably in the form of a fine spray to form a slightly sticky film of this explosive material about each pellet of the nitrate.

As soon as the nitrate pellets are evenly coated the previously finely powdered and intimately 5 mixed remaining ingredients are dusted in while the rolling is continued until each individual sodium nitrate pellet is completely enveloped and enclosed in a layer of the thoroughly mixed powdered ingredients evenly distributed thereover, and bound thereto so as to form a substantially dry granular mass each grain of which is a complete explosive unit.

The coating of the nitrate pellets as described should be carried out at a temperature sufficiently 15 above the setting point of the particular liquifiable nitro body being used so that this binding agent will remain in fluid condition until the completion of the coating operation.

Instead of the particular nitro bodies set out, others such as the nitro glycerine, benzenes, naphthalenes, etc. may be used, but those given in the formula are preferred.

Also, the specific nitrate or perchlorate and oxidizable metal used as the coating layer may be varied within the knowledge of explosive engineers, but after my experiments I feel that the above simple formula will meet all requirements in a blasting powder of this kind, though any such modifications as suggestedare intended to be included in the scope of my appended claims.

' I am aware of pelleted nitrate of sodium as such being used in explosives of the dynamite class, also the coating of ammonium nitrate pellets with trimethylal-ethyl-methane-trinitrate, and also with other substances, but I am not aware of a blasting powder being heretofore produced in which each granule is a complete explosive unit in itself formed of a central kernel of sodium nitrate entirely enclosed in the fortifying, sen- 40 sitizing and flame supporting agents in even dissemination and in adherent relation about its surface in proportions to make of each a substantially balanced explosive unit. Nor do I know of any comparable powder no matter of what constituted which has all of the valuable properties in comparison with black powder, as above set out.

Percussion tests of my improved blasting powder as above described, made under Bureau of Explosives requirements, Falling weight test, gave zero results with the 8 pound weight and 7 inch drop (steel on steel anvil) and actually required in excess of a 12 inch drop before explosion could be induced.

Similarly, frictional impact tests as per Bureau of Mines requirements Anvil friction test, both with the fiber and steel shoe, produced neither explosion, nor ignition-in fact no distinguishable crackling, and furthermore Bureau of Mines tests for fumes reported Poisonous fumes nil.

The safety of my improved blasting powder over black powder is particularly outstanding in ignition tests, for not only does the improved powder withstand ignition from ordinary flame contact, such for instance as burning a box of matches on top of a pile of it, but it will not ignite if a teaspoonful of black powder is placed on top of a pile of it and the black powder ignited.

Having thus described my improved blasting composition, what I claim is:

1. A blasting powder comprising a loose mass of pellets having a sodium nitrate center coated with a viscous film of an explosive nitric ester liquefiable at moderate temperatures forming a araaecs binder holding an outer layer of an intimate mixture of powdered ammonium nitrate, potassium perchlorate and powdered aluminum, so as to make each pellet a complete explosive unit.

2. A blasting powder comprising a loose mass of pellets having a sodium nitrate center coated with .a. viscous film of an explosive nitric ester liquefiable at moderate temperature forming a binder holding an outer layer of an intimate mixture of a finely divided explosive including a nitrate salt, a perchlorate, and an easily oxidizable metal.

3. A blasting powder comprising a loose mass of substantially uniform size pellets having a sodium nitrate center coated with a viscous film of an explosive nitric ester liquefiable at moderate temperatures forming a binder holding an outer layer of an intimate mixture of a finely divided explosive including an oxygen yielding salt, and an easily oxidizable metal.

LAUD S. BYERS.