US2325064A - Explosive composition - Google Patents

Description

EXPLOSIVE COMPOSITION Robert W. Lawrence, Wilmington, Del, assignor to Hercules Powder Company, Wilmington, Del, a corporation of Delaware No Drawing. Application June 29, 1940, Serial No. 343,162

h Claims.

This invention relates to explosive compositions of improved power and safety and more particularly to explosive compositions containing a liquid sensitizing agent which isinsensitive to impact, and to explosive compositions which do not contain liquid explosives sensitive to friction.

Explosive compositions which have been used by the prior art have normally been divided into two classes; first, sensitive explosives which contain nitroglycerin or admixtures of nitroglycerin with other nitric esters which are sensitive to,

impact, and explosive compositions containing no explosive sensitizer which is sensitive to impact. The art has found the use of nitroglycerin explosives extremely useful in blasting operations. However, for a number of operations, it is preferable to use explosives that are relatively insensitive to detonation and are completely or almost completely insensitive to impact and to friction. The insensitive explosives usually comprise an explosive salt such as ammonium nitrate in admixture with other salts such as sodium or potassium nitrate and carbonaceous materials such as wood pulp, starch, ivory meal and similar substances together with a sensitizer such as dinitrotoluene, trinitrotoluene, or other materials that are insensitive to impact. These types of explosives are used in many operations where it is especially desirable to eliminate the hazards introduced by the use of sensitive explosives.

It is an object of this invention to provide an explosive which is relatively safe to handle. A further object of this invention is to provide an explosive insensitive to impact but which may be detonated with a commercial blasting cap. A further object of this invention is to provide an explosive composition that does not contain a liquid xplosive sensitive to impact or friction.

A further object of this invention is to provide an explosive composition that is relatively safe during packing operations and during the loading of bore holes. A further object of this invention is to provide an explosiv which is insensitive to impact and which is eap insensitive. Another object of this invention is to provide an explosive composition that contains a liquid nitroparaflin as the sensitizing agent. Other objects will become apparent hereinafter.

In general, the objects or" this invention are accomplished by compounding an explosive composition which contains an admixture oi oxidiz dill wood flour, ivory meal, balsa or bagasse, coal and the like; and a liquid nitroparamn, such as, for example, nitromethane, nitroethane, dinitroethane, dinitropropane or other liquid nitroparafilns which has an oxygen balance not lower than about -100%.

The manufacture of explosives of this invention is carried out in any of the various man ners well known to the art, and may include, for example, a procedure comprising the screening into a mixer, such as a Talley mixer, an amount of an oxidizing salt, such as sodium, potassium or ammonium nitrate, alone or in admixture with one another along with an amount of carbonaceous or reducing material, such as wood flour, balsa, bagasse, etc. The Talley mixer bowl contains the desired amount of a liquid nitroparamn alone or mixed with other nitroparamns to obtain a mixture of the desired oxygen balance and sensitivity. The Talley mixer after the lngredients are thoroughly mixed is dumped and the explosive composition packed into normal cartridges that may be manufactured from paper, plastic or metal. The cartridges may be of any convenient diameter, but normally will have a diameter greater than about 2 inches as the type explosives of this inventionare generally found most useful in quarrying work or in large operations where the large diameter cartridges are desired. 7

The liquid nitroparaffins in themselves are not explosives; i. e., they will not detonate with a commercial blasting cap. However, balanced explosive compositions containing liquid nitroparamps produce a quantity of explosive energy approaching that of explosive compositions containing the same percentage of nitroglycerin. The oxygen balance of the nitroparafi'ins'is very low, and, therefore, care in compounding an explosive composition must be exercised as, if the oxygen balance of the final explosive composition is tOOrlOW, dimculty in eiiecting detonation is experienced. Thus, for example, nitromethane ing salts, such as, for example, ammonium, so-

dium or potassium nitrate; with a reducing or has an oxygen balance of -39.3%; nitroethane,

an oxygen balance of 96%; dinitroethane, an oxygen balance of -26.7%; and dinitropropane, an oxygen balance of 59.'7%. nitroparamns having a smaller proportion of oxygen than nitroethane have such low oxygen balances that they preferably are not to .be used alone in explosives, but they may find use in conjunction with the lower nitroparafins, For example, suitable mixtures may include a solution containing two parts of nitromethane and one part of nitrobutan by weight withan oxygen The liquid balance of 81% or a solution containing equal parts by weight of nitromethane and nitropropane with an oxygen balance of 87%. Therefore, my invention does not contemplate Ammonium nitrate.

1 Tested on impact machine, 2 kg. falling Weight; P=partial shot or slight crackling.

1 gested by impact of 30-06 bullet from U. 8. Army rifle at 120 yer s.

I When primed with a No. 6 blasting cap.

' Not tested.

Did not shoot.

Other cap sensitive explosive compositions may be prepared in which the nitromethane is replaced by dinitroethane or dinitropropane.

It has been found that other explosive comthe use of nitroparaflins or mixtures of nitropositions may be prepared, with nitroparafiins, parafiins having an oxygen balance lower than which are not sensitive to detonation by a com- 100% alone in explosive compositions. mercial blasting cap but are sensitive to detona- As a specific example of carrying out my lntion by a booster charge. Thus, for example, it vention, I may admix 69 parts by weight of is possible to produce an explosive composition ammonium nitrate with 29 parts by weight of 10 which furnishes a, high amount of power when nitromethane and two parts by weight of balsa it detonates, but which is so insensitive that a pulp. The admixture after thorough incorporabooster, such as a half stick of 40% dynamite or tion is packed into cartridges, and is sensitive to a charge of trinitrotoluene or tetryl must be used detonation by a No. 6 blasting cap and is found to prime the composition. In general, this type to be a very desirable explosive. Further, the of insensitive explosive composition is prepared same mixture when tested by the halved carby decreasing the percent-of the nitroparamn tridge method of propagation will cause detonapresent or by using a nitroparafiin having a lower tion across a gap as great as 10 inches. It is oxygen balance or by combining these two feabelieved that the nitromethane causes detonatures. tion of the composition by interreaction with To illustrate the type of explosive compositions the oxidizing materials, especially the ammonium which are compounded to be insensitive to detonitrate. The reaction may be initiated by a nation by a commercial blasting cap, Table 2 is blasting cap but not by an impact and thus prO- given wherein the composition and properties of vides for the production of a very safe'but cap an extra and straight dynamite are listed. sensitive explosive composition. However, this Table 2 theory is not to be construed as l miting this invention. Sam 16 A B A further advantage of the above type ex- 9 plosive over the nitroglycerin containing ex- P t P t plosive composition is that nitromethane does Iiitmcthxme ii g 3% f; not cause the operators to develop headaches mluonillmn me 7 when the explosives are handled; and, urthe ZZ g eE SwJ ETFKIIIIII 212 by itself it will not freeze above 15 F. so that 100 0 100 0 when a composition containing nitromethane is D used in normal operations, freezing can not occur ggg i ggi ig g 1 g until this temperature is reached, and often will sensli ti izglggsgim F d F d not occur until a much lower temperature is a we reached. If freezing of a nitromethane powder Primed with Suck 40% dynamm Shot shot 9 h effect is mt hazatdmls as the i 40 To illustrate gelatin type dynamites containmg of nitroglycerin powders since the explosive ing nitroparamn Table 3 is given wherein the is much less Sensitive to thawing Operations composition and properties of a gelatin explosive Furthermore, the freezing point can readily be are listed lowered by addition of suitable proportions of y Y other liquid nitroparafilns. Table 3 In order to point out the invention more speciiically. the following examples are given of Sample A explosive compositions containing liquid nitroparaflins in varying proportions as the sensitiz- I Per cent ing ingredients. The compositions of a number ggggggigggg; of explosives are given in Table 1, and their Sodium nitra various properties are listed.

Table 1 833$311111111:131:iiiifiiffifii: "95 Sample sensitiveness:

Primed with No.8cap Failed Primed with M stick 40% dynamit Shot A B C D Weight strength .per cent. 40. 5

Nltromethane per cent" 29. 1 Determined with ballistic mortar.

It will be understood by those skilled in the art that similar explosive compositions may be prepared by using mixtures of nitromethane with the higher nitroparamns such as nitropropane and nitrobutane, and that the sensitiveness of such explosive compositions may be controlled by varying the composition of the nitroparamn mixtures as, for example, by altering the nitromethane and nitroethane content. 7

It has been found that the explosives containing nitroparamns such as nitromethane, nitroethane and the like are advantageous because they are highly insensitive to impact and friction and in consequence are especially adapted for packing into metal cans. These nitroparaflin explosive compositions that are cap sensitive may |e manufactured and packed with automatic ma-- :hinery'into a metal can without the danger which this type of operation entails when nitro- :lycerin containing explosive compositions which we sensitive to impact and friction are manufacured and packed with automatic machinery.

The advantages of the nitroparaffin explosives aver the Mom explosive compositions are in- :ensitivity to impact, lack of causing headaches,

arge operations such as open pit mining and marry blasting, where the explosive'compositions nay be used in large diameter cartridges of netal, paper or plastic.

The term oxygen balance used in the specifization and claims is well known and accepted by ;he art. The oxygen balance of an explosive :ompound is calculated by determining the total Weight of the compound and dividing this weight .nto the difference between the weight of the Jxygen required to completely oxidize the elements of the compound and-the weight of the axygen actually present in the compound.

The halved cartridge gap method is a standard explosive composition test and is described fully in Bulletin 346 issued by the U. S. Bureau of Mines.

It will be understood that the details and examples hereinbefore set forth are illustrative only, and that the invention as broadly described and claimed is in no way limited thereby.

What I claim and desire to protect by Letters Patent is:

1. An explosive composition comprising an oxygen deficient liquid nitroparafiin containing not more than two nitro groups and having an oxygen balance in excess of about -100% in admixture with an oxidizing salt and a carbonaceous material. I

2. An explosive composition comprising an oxygen deficient liquid nitroparafiin containing not more than two nitro groups and having an oxygen balance in excess of about 100% in admixture with ammonium nitrate and a carbonaceous material.

3. An explosive composition comprising nitromethane having an oxygen balance in excess of about -l% in admixture with an oxidizing salt and a carbonaceous material.

4. An explosive composition comprising nitroethane having an oxygen balance in excess of about -100% 'in admixture with an oxidizing salt and a carbonaceous material.

5. An explosive composition comprising between about 5% ,and about 45% of nitromethane having an oxygen balance inexcess of about --100% in admixture with an inorganic nitrate and a carbonaceous material.

6. An explosive composition comprising between about and about of nitroethane having an oxygen balance in excess of about in admixture with an inorganic nitrate and a carbonaceous material.

ROBERT W. LAWRENCE.