US2672411A - Gelatin blasting explosives - Google Patents

Description

any.

Patented Mar. 16, 1954 UNITED STATES PATENT OFFICE GELATIN BLAQZSZ EXPLOSIVES Great Britain No Drawing. Application May 31, 1950, Serial No. 165,368

Claims priority, application Great Britain July 29, 1949 4 Claims.

The present invention relates to improvements in gelatine blasting explosive compositions of the a liquid explosive nitric ester-nitrocellulose jelly "fail to propagate their detonation satisfactorily when initiated by commercial detonators in shotholes where they are subjected to hydrostatic pressures substantially in excess of 3 atmospheres. It is also known that the replacement or partial replacement of woodmeal in such explosive compositions by porous vegetable tissue materials of unusually low'bulk density, for example, bagasse, flaked steam treated cereal grain products, and ground-cork, increases the sensitiveness and velocity of detonation at atmospheric pressure of the resulting gelatine blasting explosive compositions and enables them to be detonated at somewhat higher hydrostatic pressures, but the incapacity for and velocity of detonation still diminish markedly as the hydrostatic pressure is increased, with the result that these explosives cannot be relied uponto detonate satisfactorily in bore-holes sunk under depths of oil or water as great as would fre- "quently' be encountered in well blasting or seismic prospecting operations. The aeration resulting from the mechanical mixing operation in the production of liquid explosive nitric esternitrocellulose gelatine blasting explosives persisting for some time after the mixing operation is known to have the effect of rendering the sensitiveness to detonation of the freshly made gelatine blasting explosive compositions higher than that possessed by it after the density of the composition has risen to its normal value as a result of the escape of air bubbles. The favourable effect on sensitiveness to detonation and velocity of detonation experienced as a result of' the employment of porous vegetable tissue ingredients of unusually low bulk density is usually attributed to the entrapment of air in their pores or to their levitating effect on the composition, and the deterioration. in these properties of the gelati'ne explosives containing them under increasing hydrostatic pressure may likewise be attributed to the reduction in volume of the entrapped air as a result of the pressure transmitted through the continuous liquid nitric ester-nitrocellulose Jelly to the structure of the vegetable tissue material, whether or not this results in its actual collapse. It will be readily understood that the 'fiimsier the structure of the porous vegetable tissue material the more easily will the beneficial effects experienced at atmospheric pressure as a result of its use in a liquid nitric ester-nitrocellulose gelatine blasting explosive composition be lost when the explosive is subjected to hydrostatic pressure. Moreover there is a limit to the amount of porous vegetable tissue material of unusually low density that can be incorporated into a gelatine blasting explosive without destroying the-continuity of the matrix essential for the waterproof properties and bulk. strength characteristic of gelatine explosives.

it is an object of the present invention to provide gelatine blasting explosive compositions of the kind comprising a porous vegetable tissue material and an oxidising salt distributed through a continuous matrix of a liquid explosive nitric ester-nitrocellulose jelly which will detonate satisfactorily under greater hydrostatic pressures than can be attained by the use of the customary porous vegetable tissue materials of unusually low bulk density.

According to the present invention a gelatine blasting explosive of the kind comprising a porous vegetable material ingredient and an oxidising salt distributed through a continuous matrix of a liquidexplosive nitric ester-nitrocellulose jelly is characterised in that the porous vegetable material consists of dried substantially deproteinised, ale-oiled peanut meal obtained by aqueous alkaline extraction washing and dewatering of a peanut product from which the oil has been removed in known manner as for instance by expression or byextraction witha volatile solvent or by expression followed by extraction with a volatile solvent. The dried substantially de-proteinised de-oiled peanut meal, which is preferably one made from peanuts from which the brown testa has first been removed, a; porous material consisting mainly of cellulose, and constitutes a commercially available by product from the manufacture of peanut protein. Peanut protein is used in the manufacture of certain protein textile artificial filaments. The. deproteini'sed d'e-oiled peanut meal is desirably screened so as to reject any meal. passing a B. S. S. screen or retained on a 16 B. S. S. screen. Advantageously the washed, and cen trifuged material may be worked through a coarse screen before the final drying step and if necessary may be milled thereafter before the final screening.

The de-proteinised de-oiled peanut meal so obtained has a bulk density of approximately 0.46 gram per cc. under a packing pressure of 25 lbs. per sq. in. and approximately 0.51 gram per cc. under a packing pressure of '75 lbs. per sq. in. and its density is thus higher than that of ordinary woodmeal, which exhibits bulk densities of approximately 0.35 and approximately 0.41 under these pressures. Its absorbency for nitroglycerine under a pressure of 75 lbs. per sq. in. is approximately 150%, the corresponding figure for ordinary woodmeal being about 250%. The corresponding approximate figures for bulk density and nitroglycerine absorption for bagasse and for ground cork are respectively as follows:

Density at 25 lbs. pressure-017 and 0.16 gm.

per cc.

Density at 75 lbs. pressure-0.25 and 0.29 gm.

per cc.

Absorbency-328% and 110%.

It contains 44% carbon, 4.5% nitrogen and 6% hydrogen.

In putting the invention into effect the deproteinised de-oiled peanut meal may be incorporated into the explosive composition in the conventional manner employed for other vegetable tissue materials. The oxidising salt may be an alkali metal nitrate but it is also possible to employ the de-proteinised de-oiled peanut meal in ammonium nitrate gelatine explosives.

The invention will be further understood by reference to the example, in which the percentages are by weight. is made to a test in which three cartridges in file each 10.5 in. long and of 2 in. diameter separated by gaps A.; in. in length and enclosed in a tele scopic cardboard tube are fired under varying water pressures and the velocity of detonation of the third cartridge is observed. In these tests the cardboard container is punctured so as to ensure that the cartridges, which are enclosed in conventional waxed paper wrappers, are separated from one another by water, and the first stancy of velocity of detonation under pressures ranging from 50 lbs. per sq. in. upwards and can be detonated satisfactorily under higher pressures.

Example The ingredients of the gelatine explosive composition are as follows:

Per cent Mixture of nitroglycerine and ethylene 'glycol dinitrate in the ratio 80:20 by weight 57.5

Blasting Soluble nitrocellulose 2.5 De-preteinisied ole-oiled peanut meal passing 16 and retained by 100 mesh B. S. S. screen 13.0 Sodium nitrate 26.4

Chalk 0.3 Di-ammonium hydrogen phosphate 0.3

The ingredients are mixed in known manner In this example reference in a McRobert mixer until the nitrocellulose has become well gelatinised and the other ingredients are well distributed through the jelly. The density of the composition after storage for two days is 1.51 grams per cc. In the triple cartridge test under varying heads of water the explosive composition gives the following figures for the velocityof detonation in the third cartridge:

Meters per sec. 50 lbs. per sq. in 2400 100 lbs. per sq. in 2210 200 lbs. per sq. in 2580 250 lbs. per sq. in 2580 300 lbs. per sq. in 2580 450 lbs. per sq. in 2500 The explosive is thus suitable for use in seismic prospecting and for well blasting at substantial depths, using a No. 8 commercial lead azide tetryl aluminum detonator.

By way of comparison the compositions, densities, and performances in the triple cartridge tests are given below for two gelatine explosive compositions not in accordance with the invention containing the same percentages of liquid explosive nitric ester and nitrocellulose of the same consistency. Ihese compositions are made by using vegetable tissue materials of unusually low density, and by adjusting the proportion of sodium nitrate to compensate for the difierent absorptive capacities of the vegetabl tissue materials employed.

Percent Percent :20 mixture of nltroglycerine and ethylene glycol dinitratc Blasting Soluble" nitrocellulose Bagasse Starch Flaked steam treated cereal grained product Sodium nitrate Chalk Di-ammonlum hydrogen phosphate Density in gIIL/CG 125 lbs/sq. in.7,l50 m. p. s.

150 lbs/sq. in.-3,300 m. p. s.

400 lbs/sq. in.2nd and 3rd cartridges failed to detonate.

501bs./sq. in.7,l00 m. p. S.

l001bs./sq. ln.-2,900 In. p. s. I

150 lbs/sq. in.-2,050 m. p. s.

300 lbs/sq. in.2nd and 3rd cartridges failed to detonate.

In the foregoing example the term Blasting Soluble nitrocellulose means the product of nitration of purified cotton cops by the pot process to a nitrogen content of 11.95 to 12.25%. The product is at least soluble in ether alcohol solution and has a viscosity of to 300 c. g. 5. units in solution of three grams in 100 ml. acetone (95%) at 20 C.

What we claim is:

1. A gelatine blasting explosive comprising a porous vegetable material ingredient and an oxidising salt distributed through a continuous matrix of a liquid explosive nitric esternitrocellulose jelly, said porous vegetable material consisting of dried substantially protein-free, oilfree peanut meal.

2. A gelatine blasting explosive composition as claimed in claim 1 wherein the dried substantially protein-free, oil-free peanut meal is one made from peanuts from which the brown testa has first been removed.

3. A gelatine blasting explosive composition as claimed in claim 1 wherein the protein-free, oilfree peanut meal is one which passes a 16 B. S. S. screen and is retained on a 100 B. S. S. screen.

4. A cartridge containing a gelatine blasting explosive comprising a porous vegetable material ingredient and an oxidizing salt distributed through a continuous matrix of a liquid explosive nitric ester-nitrocellulose jelly, said porous vegetable material consisting of dried substantially protein-free, oil-free peanut meal.

JAMES TAYLOR. JAMES V. GREGG.

6 References Cited in the file of this patent UNITED STATES PATENTS Number Name Date Botts et a1 Jan. 24, 1933 Woodbury July 10, 1934 Chapman Feb, 26, 1935 Williams et a1. Sept. 6, 1938

Claims (1)

1. A GELATINE BLASTING EXPLOSIVE COMPRISING A POROUS VEGETABLE MATERIAL INGREDIENT AND AN OXIDISING SALT DISTRIBUTED THROUGH A CONTINUOUS MATRIX OF A LIQUID EXPLOSIVE NITRIC ESTERNITROCELLULOSE JELLY, SAID POROUS VEGETABLE MATERIAL CONSISTING OF DRIED SUBSTANTIALLY PROTEIN-FREE, OILFREE PEANUT MEAL.