Method for treating destabilized, fire-involved elemental phosphorus

Destabilized elemental phosphorus, for example resulting from fire involvement due to exposure with air, can be treated by placing the destabilized elemental phosphorus in the presence of a weakly basic aqueous solution of an alkali metal hypochlorite as a blanketing agent. Sodium hypochlorite is preferred.

BACKGROUND OF THE PRESENT INVENTION 
1. Field of the Present invention 
The present invention relates to a method of treating elemental phosphorus, 
e.g., the safe storing of destabilized elemental phosphorus after it has 
become fire involved. 
2. Description of the Prior Art 
Elemental phosphorus (also commonly referred to in the art as "P.sub.4 ") 
is a well known, highly pyrophoric material. When elemental phosphorus is 
exposed to air it spontaneously combusts. If phosphorus is inadvertently 
spilled, it is taught that it should be immediately covered with water, 
i.e. as a blanketing agent, to quench the fire that will result. See, for 
example, Accident Prevention Manual for Industrial Operations, 6th 
Edition, page 1367 (1969). 
Although the quenching of a phosphorus fire by use of water overcomes the 
immediate problem of combustion of the phosphorus, a number of serious 
dangers still exist. For example, the burning of the phosphorus produces 
phosphorus pentoxide, phosphorus trioxide, and other by-products which, 
when dissolved in the water which is used to douse the fire, form 
polyphosphoric, phosphoric, and phosphorous acids which can lead to attack 
of the metal surfaces of any containers (tanks, drums, and the like) into 
which the fire-involved elemental phosphorus and water quenching agent are 
thereafter placed, thereby causing the generation of hydrogen gas. Also, 
phosphine gas is sometimes produced when elemental phosphorus is exposed 
to moist air, and this compound also poses a spontaneous fire hazard. The 
presence of any produced hydrogen gas can lead to the danger of explosion 
due to burning, especially in the presence of self-igniting phosphine in 
any container or drum containing the doused phosphorus material. This 
danger of secondary explosion is exacerbated when the build-up of hydrogen 
is ignited by the spontaneous burning of the phosphine gas. 
The need therefore exists for a method of insuring that the destabilized, 
fire-involved elemental phosphorus material with its concomitant dangerous 
by-products (phosphorus-based acids, phosphine, hydrogen, and the like) 
are present in an aqueous blanketing solution under conditions which do 
not give rise to such dangers as corrosion of containers holding such 
compositions, explosion dangers, or fire dangers. Recently, it was 
reported in "The Disposal of Fire Damaged White Phosphorus Drums", by J. 
P. Lafornara et al., Control Hazard. Mater. Spills, Proc. Natl. Conf. 
1980, pp. 58-64 that only two options exist for disposal of drums of fire 
damaged phosphorus: namely, burial or controlled detonation (see p. 62). 
SUMMARY OF THE PRESENT INVENTION 
The present invention relates to the storing of destabilized, previously 
fire-involved, elemental phosphorus in the presence of a weakly alkaline 
aqueous solution of an alkali metal hypochlorite as a blanketing agent to 
prevent such dangers as secondary explosions of any containers or drums 
containing the water, destabilized phosphorus, and any of the 
aforementioned undesired by-products. The hypochlorite of choice is sodium 
hypochlorite in view of its cheapness and ready availability.

DETAILED DESCRIPTION OF THE PRESENT INVENTION 
As mentioned before, the present invention involves the storing of a 
destabilized elemental phosphorus material, which has been previously fire 
involved, in a blanketing layer of aqueous alkali metal hypochlorite under 
weakly basic conditions. One hypochlorite of choice is sodium hypochlorite 
in view of its ready availability and cheapness. Generally speaking, the 
concentration of the sodium hypochlorite in the aqueous blanketing 
composition can be on the order of about 3-5% by weight, and the solution 
should be weakly basic, having pH of about 7.5-10 or so. 
After the phosphorus fire has been doused with water, the destabilized 
elemental phosphorus material (and its dousing water blanket) resulting 
from the fire involvement, due to exposure with oxygen in the atmosphere, 
is placed in the presence of a weakly basic, aqueous solution of the 
alkali metal hypochlorite as a blanketing agent. This hypochlorite active 
ingredient in the blanketing composition acts to continuously and 
progressively react with any undesired phosphine that might be present 
while the weakly basic nature of the solution neutralizes any 
phosphorusbased acids that are present due to the contact of water with 
the P.sub.2 O.sub.5 and P.sub.2 O.sub.3 values generated by the oxidation 
of the elemental phosphorus upon its exposure to oxygen in the air. If 
necessary, pH adjustment of the aqueous hypochlorite blanketing agent by 
addition of trisodium phosphate and/or caustic can be employed. The weakly 
basic, hypochlorite-based blanketing agent of the present invention 
provides an intrinsically more safe system than simple water immersion of 
the elemental phosphorus as suggested by the prior art. The hypochlorite 
blanketing agent used herein is readily available and cheap in those cases 
in which sodium hypochlorite is selected as the hypochlorite agent. 
The present invention will be further illustrated by the Example which 
follows. 
EXAMPLE 
A 1.0 gram (0.032 gram atoms) chunk of white phosphorus was placed in a 150 
millimeter diameter by 100 millimeter deep crystallization dish. It was 
ignited in air by heating with a bunsen burner. 
The fire was doused by means of a 3% NaOCl solution. The solution was made 
by diluting 150 milliliters of commercial CLOROX bleach, which is a 5% 
solution of NaOCl in NaOH, with 100 milliliters water to give a 3% NaOCl 
solution. When 200 milliliters of solution was poured over the burning 
phosphorus, the fire extinguished immediately, and the phosphorus was 
completely covered. The solution pH was 4.0. Adding the remaining 150 
milliliters of NaOCl solution raised the pH to 7.5. Active hypochlorite 
was present as evidenced by its bleaching action on pH paper. 
The residual phosphorus had a red crust on it that disappeared on standing 
about one month at room temperature under the hypochlorite solution. After 
three months, the solution pH was 4.0 and the phosphorus residue was 
clean. It burned readily when dried in air. 
This experiment demonstrated that a phosphorus fire would be rapidly 
quenched to give a non-acidic mixture that would not attack steel drums 
and generate hydrogen. That the unreacted phosphorus would be clean and 
recoverable for reuse was also shown. 
The foregoing Example is set forth for illustrative purposes only and 
should not be construed in a limiting sense. The scope of protection that 
is sought is set forth in the claims which follow.