US2530490A

US2530490A - Method of making incendiary compositions

Info

Publication number: US2530490A
Application number: US555766A
Authority: US
Inventors: William F Van Loenen
Original assignee: Kaiser Aluminum and Chemical Corp
Current assignee: Kaiser Aluminum and Chemical Corp
Priority date: 1944-09-25
Filing date: 1944-09-25
Publication date: 1950-11-21
Anticipated expiration: 1967-11-21

Description

Patented Nov. 21, 1950 METHQD OF MAKING INCENDIARY COIVIPOSITIONS William F. Van Loenen, Los Altos, Calif., assignor, by mesne assignments, to Kaiser Aluminum & Chemical Corporation, a corporation of Delaware / No Drawing. Application September 25, 1944,

Serial No. 555,766

9 Claims. 1

The present invention relates to an incendiary composition or incendiary and to a method of creating incendiary conditions including the step of promoting a reaction between the incendiary composition and an oxidizing liquid.

In my copending application Serial No. 492,989, filed July 1, 1943, now Patent No. 2,509,710, I have set forth the production of magnesium metal from magnesium oxide by carbothermic reduction according to the process disclosed in Patent No. 1,884,993 (Hansgirg). Therein a mixture of magnesium oxide and carbon is converted into magnesium vapor and carbon monoxide by the heat of an electric arc furnace. This gaseous mixture is discharged from the region of the are at a high enough temperature '(above 1800 C.) that reversal of the reaction does not occur, and is then suddenly cooled and diluted by injecting large volumes of a shock chilling agent, which may be hydrogen, natural gas, hydrocarbon vapor or even a spray of liquid hydrocarbon.

In one particular practice of the process natural gas is employed. The magnesium vapor is condensed to magnesium metal in the form of extremely fine dust. Some of the vapor recombines with carbon monoxide with the result that the solid material precipitated in the condensing chamber comprises a substantial proportion from 30 to 60% of magnesium dust with the remaining '70 to 40% comprising carbon, magnesium oxide and other impurities. A typical sample of a normal run shows 47% by weight of magnesium metal dust. The magnesium dust obtained as described and of the characteristics shown herein is, for convenience, designated carbothermic magnesium dust.

This condensate, i. e., the magnesium dust with admixed impurities, while it requires coalescing of the magnesium dust to produce compact metal,

asphalt is added when it is desired to make the mass somewhat cohesive, particularly where it is desired to tablet the material into compact pellets or briquettes. Where the shock chilling is produced by oil spray, the shock chilling oil wets the precipitate and inhibits ignition while forming carbothermic magnesium paste.

Experiments proved that this carbothermic magnesium paste, 1. e., magnesium dust and impurities wet with oil and with or without asphalt or other binder is not spontaneously reactive with dry air. However, water vapor or spray will ignite the carbothermic magnesium paste and this paste-water combination provides an inex- A small percentage of the magnesium (approximately 5%) exists as one or both of the carhides-MgCz and MgzCs. There is generally a trace of sodium which is believed to be in elemental form and possibly minor traces of other carbides such as calcium, silicon and aluminum originating from the ash constituents from the metallurgical coke in the reduction furnace i and/ or from the minor ash constituent in the petroleum coke used for reduction. With the exception of occasional carry over of particles from the reduction furnace all of these materials have an ultimate particle size below the resolving Electron micropower of optical microscopes. photographs reveal agglomerates several microns in diameter and ultimate particles in the neighborhood of 0.1 micron.

The hydrocarbons which may be employed for wetting the magnesium dust may advantageously consist of distillate and 50% asphalt designated as Orcutt-l20. A typical analysis of a mixture of such hydrocarbons which has proved successful is as follows:

Distillate Gravity API at F Flash point Pensky-Marten closed cup F' 180 Viscosity Saybolt seconds Universal at F. 60

O'rcutt-IZO asphalt Gravity API at 60 F 10.2 Flash point Pensky-Marten closed cup F- 430 Viscosity Saybolt seconds Furol at 210 F.

To produce a mixture of crude dust and hydrocarbons, safe for shipment and suitable for compounding incendiary fuels, the shock chilled dust is conveyed in a closed atmosphere under natural gas to pug mill type extrusion presses where it is I thoroughly mixed With the desired hydrocarbons and extruded through a die plate into open drums. The limitations on this equipment are such that practical concentrations can be made between 55% and 70% solids, the balance hydrocarbons. For reasons of safetyit is undesirable to include low flash hydrocarbons at this stage. Various mixtures of fuel oils, or asphalt cut-back with fuel oils, or kerosenes in a considerable range, are practical from a production standpoint. This magnesium material when thoroughly wetted with hydrocarbons is not easily ignited nor will it flash or explode. However, if allowed to air dry or come in contact with water, acid, or perspiration, it will sooner or later ignite when such liquid has cut through the protective layer of hydrocarbon so as to react with the finely divided magnesium.

The construction of well known incendiaries, particularly those of the known stick form, involves the use of cast solid magnesium metal which is difficult to ignite except by thermite or a similar igniting charge. Incendiaries and flares of magnesium powder have therefore been made by-first producing magnesium in solid metal form and then subdividing it. By my method the raw powder coming from the shock chilling step of the carbothermic process may be directly substituted for the far moreexpensive method at present utilized. Also, the magnesium metal as employed in the carbothermic magnesium paste isof a state of subdivision far greater than that which it is practicable to produce by mechanical comminution.

According to my invention the magnesium powder even in the impure form as recovered from the vapor produced by carbothermic reduction, and with or without other materials, may be directly applied to incendiary use without going through the stage of first producing the coalesced or solid metal. A great advantage of using such a'flnely divided metal is that the desired ignition may be secured from mere contact with such simple media as air and water. Any substance which gives upoxygen freely enough to produce ignition, i. e., rapid combustion, may

be used.

The finely divided magnesium'produced in the carbothermic process has a particle size of substantially less than one micron, and as heretofore stated is capable of spontaneous combustion with the atmosphere unless wetted down with a material such as hydrocarbon oil. 'It is obvious that a particle size on the order of that mentioned cannot be achieved on a commercial scale by use of mechanical means. The fine particles, because of their pyrophoric qualities, would present a considerable fire hazard if mechanically produced, and the high cost and complicated equipment necessary to mechanically produce such particles in an inert atmosphere would be impractical. Thus additional advantages of this invention are that it utilizes an incendiary material of finely divided magnesium of a particlesize never before attainable on a commercial scale, and yet such finely divided magnesium is capable of rapid and economic production, and can be bothermic magnesium paste and may partake of the incendiary reaction, after the same is imtiated.

It is to be understood that after the carbothermic magnesium zpaste is once ignited, it will continue to burn 'by =reaction with the oxygen and/ or nitrogen of the air, and tends by the heat and flame produced to ignite adjacent combustibles. Water applied to extinguish it is of no use as it reacts readily with the magnesium, accelerating combustion. Such common extinguishers as carbon dioxide actuallyaccelerate combustion.

Additional reagents which tend to sustain combustion of the magnesium powder, such as ferric oxide, barium oxide and other similar metal oxides, ,potassium chlorate, sodium nitrate, and :other similar metallic salts containing combined oxygen, sulfur, gasoline or carbon, and mixtures thereof, may be added to .the carbothermic magnesium pasta-and after ignition is instituted as by the liquid oxidizing agent, the further combustion may be sustained or aided by such reagents. Where a liquid, such as water, is employed to produce igm'tion,-the resulting gas, such as hydrogen, is combustible and tends to spread the fire. Similarly, liquids which by deoxidation by the finely divided magnesium produce com-' bustible gases, tend also to spread the fire by producing a flame reaching into adjacent space for oxygen to support its-combustion.

While plain water is the simplest liquid capable of oxidizing the described magnesium, there may be situationsor conditions'of use calling for the addition of "antifreeze agents-or of liquids which will withstand low temperatures without solidification. Thus alcohols, such as'methanol, aldehydes and organic acids may be employed. Also inorganic compounds such as chlorates, permanganates, particularlyof the alkali metals, may be dissolved in the liquid or associated therewith. Wetting agents to accelerate the wetting of the incendiary material with the liquid may be used.

If it is desired to ignite the magnesium powder in a bodyof water, or under similar conditions,

particularly where it is; desired to ignite an oil slic-kon a body-of watenit is advantageous to 'add an-agent which willcause heat and/ or gas generation, 'such as quicklime and/ or carbides and/or phosphides; The addition of gas generating agents to the finely divided magnesium powder is particularly advantageous due to their gas generating properties, because the pressure generated causes the casing containing the incendiary material to burst more rapidly than I under condition wherein the incendiary material does not contain gas generating agents, with consequent dispersion of the incendiary charge over the adjacent area in a very efiective manner. An additional feature of the invention is that thefinely divided magnesium dust is colloidal in Y comminuted magnesium whichdoes not ,give good In the use of carbothermic magnesium results. paste with the gels or alone there is-an additional advantage that the reaction between the colloidal magnesium particles and the oxidizing liquid takes ,place progressively throughout the mass to liberate jgreat quantities of heat to destructively distill the hydrocarbons in admixture therewith and give off large'quantities of inflammable gases with sufficient violence to induce air circulation and mixing to thereby burn the gases substan- I tially to completion. It is to be *notedthat the volume basis than light hydrocarbons, which is important in many instances, e. g. the storage capacity of an airplane. Another point of importance is that the generation of gases within the asphaltic mass of the incendiary yields a swelling ash whichis useful.

The present invention is a continuation-in-part of my application Serial No. 492,989, filed July 1, 1943, now Patent No. 2,509,710. 1

The primary object of the invention is to form an incendiary composition including magnesium as one ingredient thereof, and more particularly to the employment of a wetting agent and/or anti-freeze agent in combination with the oxidizing liquid necessary to promote early ignition.

, Another object is to providean incendiary composition including a carbothermic magnesium paste mixture which combines with a liquid oxidizing agent to create incendiary conditions, in the presence of a wetting agent to promote an early reaction between the magnesium of the paste and the liquid oxidizing agent.

A further object is to provide a method of creating incendiary conditions comprising the step of bringing the oil or oil-asphalt modified magnesium dust formed in the thermal reduction of magnesia by carbon, into contact with a liquid capable of oxidizing the magnesium modified by the addition of a wetting agent and/or an antifreeze agent.

Another object is to modify a liquid capable of oxidizing the described magnesium by adding a wetting agent and/ or an antifreeze agent thereto so as to make said liquid more adaptable for reacting with carbothermic magnesium paste,

In carrying out the invention, it is preferred to employ the carbothermic magnesium paste mixture, as heretofore described. The paste mixture has been treated with a hydrocarbon oil preferably having a flash point of 100 F., or over, or with an oil-asphalt mixture to reduce its activity in air.

When it is desired to promote ignition the carbothermic magnesium paste is reacted with an oxidizing liquid, such as water. The water penetrates the oil surrounded particles of magnesium and finally ignition results.

I have found that the reaction between the carbothermic magnesium paste and water, or other oxidizing liquids, can be materially speeded up by introducing a wetting agent into the water. The wetting agent added to the water causes a more rapid penetration of the water through the oil surrounding the magnesium particles of the paste to bring about a more rapid ignition of the mixture.

Any suitable wetting agent known to the art may be employed. For example, alcohol sulfates, sulfonated compounds, such as sulfonated alcohols may be employed. Also wetting agents may be employed which are in addition effective antifreeze agents. Examples of agents of the antifreeze and wetting type are acetone, glycerol and diethylene glycol.

The invention also contemplates the employment of the combination of an agent primarily known for its wetting properties with an agent primarily known for its anti-freeze properties, as an additive to the liquid oxidizing agent. For example, a sulfonated alcohol may be combined with diethylene glycol, or other dihydric or trihydric alcohols having distinct properties as anti-freeze agents.

The wetting agent and/orantifreez'e a ent is added to the oxidizing liquideither in small or the oxidizing liquid, while the antifreeze is pres-: ent in amounts up to 30% by weight of the oxi dizing liquid. It is preferred that the oxidizing liquid plus the additive freezes at around 45 F.

to 60 F. to make it more adaptable for freezing climates or for bombs transported at great heights.

In the employment of compounds which have in suflicient quantity to keep the freezing point' of the mixture at about 45 F.

The concept of this invention embraces the feature of providing an incendiary composition including magnesium as one ingredient thereof, for example, the magnesium as formed in the carbothermic process disclosed in the Hansgirg Patent No. 1,884,993, i combination with an oxidizing liquid including a wetting agent and/ or an antifreeze agent. The magnesium is suitably modified by oil or an oil-asphalt mixture to reduce its activity in air.

A further concept of the invention includes the feature of a method of creating incendiary conditions comprising the step of bringing water, or other liquid capable of oxidizing the described magnesium, to which has been added a. wetting and/or antifreeze agent, into reaction with a carbothermic magnesium paste mixture. Any wetting agent or antifreeze agent known in the art may be employed so long as it is compatible with the liquid capable of oxidizing the described magnesium to permit a carbothermic magnesium paste-oxidizing liquid reaction to occur to ignite the mixture.

It is to be understood that the term incendiary as used herein is not intended to be limited to incendiaries as applied to bombs or the like, but instead is intended to include any application wherein such material is useful, such as fireworks, flares, signals, etc.

The incendiary of the invention is ideal in many applications because it vastly increases the chances of self-sustaining combustion.

What is claimed is:

1. In the method of creating incendiary conditions comprising bringing pyrophoric, finely divided magnesium into contact with an oxidizing agent, the improvement which comprises bringing carbothermic magnesium dust coated with a mixture of asphalt and liquid hydrocarbon into contact with a liquid capable of oxidizing said magnesium and containing a wetting agent.

2. Method as. in claim 1 wherein the liquid capable of oxidizing the said magnesium is water.

3. Method as in claim 1 wherein the liquid capable of oxidizing the said magnesium has a freezing point substantially lower than that of water.

4. In the method of creating incendiary conditions comprising bringing pyrophoric, finely divided magnesium into contact with an oxidizing agent, the improvement which comprises bringing carbothermic magnesium dust coated with a mixture comprising asphalt and liquid hydrocarbon into contact with a liquid capable of oxidizing said'magnesium and containing a wetting agent and an anti-freeze agent.

5. In the method of creating incendiary condiease-49o tionszzeomnrising brin ing pyrophoric, finel divided magnesiumiinto contact with an.:0xidizing agent. the improvement which comprises bringmg carbothermic magnesium dust coated with a mixture of asphaltand liquid hydrocarbon into contact with water containing a wetting agent and :an anti-freeze agent,

16. .Method .aS [in claim ,5 wherein the wetting agent zistalso. an anti-,ireez e agent.

'1. Method as in claim 5 wherein the wetting agentzis-azsulfonated alcohol.

8. Method as in claim 5 wherein the anti-freeze agent is x.diethylene glycol.

19. ;In.-,the'method-of creating incendiary conditions comprising bringing pyrophoric, finely di- 16 contact with as, liquid ncapable :of oxidizing vsaid Dhe following references are of :record in th file of :this patent:

UNITED STATES PATENTS Number Name Date 841,172 Nienstadt .Ju1 y,15,, 1907 1,308,463 Webb t. v July 1, 1919 1,399,953 Fulton -1 Dec. .13, 192.1 1,408,056 Wohl ;Feb..'28, .1922 2,328,202 Doerner Aug. 31,119.43

FOREIGN PATENTS Number Country Date 12% 3.96 Great Britain 1 Apr. 10, .1919

Claims

1. IN THE METHOD OF CREATING INCENDIARY CONDITIONS COMPRISING BRINGING PYROPHORIC, FINELY DIVIDED MAGNESIUM INTO CONTACT WITH AN OXIDIZING AGENT, THE IMPROVEMENT WHICH COMPRISES BRINGING CARBOTHERMIC MAGNESIUM DUST COATED WITH A MIXTURE OF ASPHALT AND LIQUID HYDROCARBON INTO CONTACT ITH A LIQUID CAPABLE OF OXIDIZING SAID MAGNESIUM AND CONTAINING A WETTING AGENT.