Addition of Aluminium

The oxidation of aluminium is highly exothermic producing —1590 kj, as shown in Reaction 5.13. 

In an explosive composition the aluminium reacts with the gaseous products particularly in oxygen-deficient compositions where no free oxygen exists as shown in Reaction 5.14. 

The volume of gas does not change in the first two reactions, i.e. 3 moles - 3 moles. Consequently, the increase in the output of heat from the oxidation of aluminium prolongs the presence of high pressures. This effect is utilized in explosive compositions for airblasts, lifting and heaving, or large underwater bubbles. However, there is a limit to the amount of aluminium that can be added to an explosive composition as shown in Table 5.18. 

The heat of explosion Q increases with an increase in the quantity of aluminium but the gas volume V decreases, resulting in the power Q x V reaching a maximum value of 381 x 10at 18% aluminium. 

The same effect can be observed for other explosive compositions containing aluminium, where a maximum value for the power can be achieved by adding 18-25% aluminium. 

---

The addition of aluminium to the liquid slowed down the reaction. An amorphous cement was formed and there was no crystallization in the bulk of the cement. However, after some time crystallites were formed at the surface. Thus, the presence of aluminium exerts a dedsive influence on the course of the cement-forming reaction. This effect is to be attributed to the formation of aluminophosphate complexes (see Sections 6.1.2 and 4.1.1). These complexes may delay the predpitation of zinc from solution and also introduce an element of disorder into the structure, thus inhibiting crystallization. It is significant that zinc, which does not form complexes, has little effect on the nature or speed of the reaction. 

During preparation of 1,5-dibenzoylnaphthalene, addition of aluminium chloride to a mixture of benzoyl chloride and naphthalene must be effected above the m.p. of the mixture to avoid a violent reaction. 

Addition of aluminium chloride to a large volume of recovered nitrobenzene containing 5% of phenol caused a violent explosion. Experiment showed that mixtures containing all 3 components reacted violently at 120°C. 

A mixture containing 51% of calcium nitrate and 12% ammonium nitrate with 27% formamide and 10% water is detonable at —20°C [1]. Addition of aluminium powder improves performance as a blasting explosive [2],... 

The first result in Table 2.2 is the value found directly. The next set of three results shows that recovery of fluoride after deliberate addition to the spiked samples is excellent. The fifth result is that obtained from an acidified sample. The sixth, seventh, eighth, and ninth sets of data show that the expected fluoride concentration is still obtained after deliberate addition of aluminium or iron in the form of their alums. Aluminium (III) and iron (III) form very strong fluoride complexes [70] and, provided that sufficient time is allowed for equilibration (as noted by Baumann [64] for very low fluoride concentrations), total flu-... 

It is prepared by the gradual addition of aluminium chloride to a slurry of lithium hydride in ether. The precipitated LiCl and unreacted LiH are fdtered off. 

Freundlich isotherm the bulk concentrations Ci, (7a, necessary to produce precipitation will evidently follow no regular order, but be dependent on the variables a and n of the isotherm expression. Thus on the addition of aluminium chloride to arsenious sulphide... 

Scheme 5.1-11 The effect of the addition of aluminium(lll) chloride to antimony(lll) chloride.

Originally the addition of aluminium was limited to explosives with a positive oxygen balance, i.e. mixtures containing a considerable amount of an oxygen carrier. However, during World War II, the Germans extended the use of aluminium by adding it to nitro compounds, for example to a mixture of TNT with hexyl. 

It was also observed that the increase in lead block expansion caused by the addition of silicon is a half or two thirds smaller than that caused by the addition of aluminium. 

The addition of aluminium to increase the heat of the explosion and, in consequence, the power of the explosive, as practised for some time, is now believed to be too dangerous. Ammonium nitrate explosives with aluminium are permitted only for rock work in opencast mining (e.g. quarries) or underground, where there is no methane. 

If the power of oxyliquits is to be increased to obtain rock explosives, this may be achieved by the addition of aluminium. 

Table 5.18 Effect of the addition of aluminium on the heat of explosion and volume of gaseous products for TNT/Al. These values have been obtained experimentally...

Yellow ochre may be " improved, besides by artificial organic dyes, also by vegetable colours or by chrome yellow. These are detected by treatment with sodium hydroxide from the alkaline solution of vegetable colours, the corresponding lakes are precipitated by addition of aluminium sulphate the same alkaline solution, acidified with acetic acid, gives a yellow precipitate in presence of chrome yellow. 

The main difficulties in these experiments consist in the choice of suitable solvents and in the partial insolubility of the polymer after addition of aluminium bromide. 

Upon addition of aluminium, it could be seen that not only the crystal size for a given reaction time tended to be smaller compared to an aluminium-free synthesis run, see Table VI, but that the crystal morphology was significantly affected. 

Addition of aluminium-strip effects the precipitation of metallic osmium, which is collected in an asbestos-packed tube and dried at dull red heat in hydrogen, cooled in carbon dioxide, and weighed. 

A strongly reducing fuel-rich nitrous oxide—acetylene flame is superior to other flames for sensitivity and freedom from interferences. Optimisation of burner height is important as absorption signal is fairly dependent on observation height. In aqueous systems interference from calcium has been controlled by the addition of aluminium or Na2S04. Reduced sensitivity has been reported in the presence of acetone vapour from depleted acetylene cylinders. 

Preparation.—The main source of rubidium compounds is the residual mother-liquor obtained in the extraction of potassium chloride from carnallite. The solution contains rubidium-carnallite, RbCl,MgCI2, a substance transformed by addition of aluminium sulphate into rubidium-alum, RbAl(S04)8,12H20. Separation from the potassium and caesium salts also present is effected by fractional crystallization of the alum,8 of the chloroplatinate 8 Rb2PtCl8, of rubidium-iron-alum,4 and of the double chloride with stannous chloride5 or with antimony trichloride.6... 

Ferric sulphate is slowly soluble in water, and dissolves more readily in the presence of ferrous sulphate,4 but its solubility is lowered by addition of aluminium sulphate.5... 

Addition of aluminium and gallium trichloride to phosphorus ylides 96a-96c leads to the formation of the heterocyclic salts 97a-97c (Scheme 34). 

---