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An aqueous slurry explosive blasting composition comprising an aqueous suspension of water-soluble crystalline oxidizing salt consisting predominantly of ammonium nitrate, which salt has been comminuted in a saturated aqueous solution in the presence of a water-soluble crystal-growth inhibiting surf

An aqueous slurry explosive blasting composition comprising an aqueous suspension of water-soluble crystalline oxidizing salt consisting predominantly of ammonium nitrate, which salt has been comminuted in a saturated aqueous solution in the presence of a water-soluble crystal-growth inhibiting surfactant having a hydrophobic portion and a hydrophilic portion in its molecule, in intimate admixture with liquid water-immiscible hydrocarbon fuel sensitizer. The surfactant maintains the oxidizer salt in a finely divided state and also ensures that the liquid hydrocarbon remains uniformly distributed throughout the explosive mass as a stable coating of droplets on the salt particles thereby enhancing the explosive sensitivity of the composition. The preferred fuel is diesel oil and preferred surfactants include sodium carboxymethyl cellulose, long chain aliphatic amines, polyacrylic acids, sulphonated nuclear aromatic compounds, sulphonated dyes, sulphonated polymers and long chain alcohol sulphonates and phosphonates.

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1. An aqueous slurry blasting explosive composition comprising an aqueous suspension of water-soluble crystalline oxidising salt consisting predominantly of ammonium nitrate, which salt has been comminuted in a saturated aqueous solution of said salt in the presence of a water-soluble crystal-growth

1. An aqueous slurry blasting explosive composition comprising an aqueous suspension of water-soluble crystalline oxidising salt consisting predominantly of ammonium nitrate, which salt has been comminuted in a saturated aqueous solution of said salt in the presence of a water-soluble crystal-growth inhibiting surfactant having a hydrophobic portion and a hydrophilic portion in its molecule, in intimate admixture with liquid water-immiscible hydrocarbon fuel sensitiser, the hydrocarbon fuel having been mixed with the aqueous suspension at a temperature below that at which all the oxidising salt dissolves in the solution. 2. A composition as claimed in claim 1 wherein the aqueous suspension contains from 10 to 40% by weight of water. 3. An explosive composition as claimed in claim 1 wherein the oxidising salt is comminuted to average particle diameter of less than 45 microns. 4. An explosive composition as claimed in claim 1 containing from 6 to 20% by weight of water and from 30 to 80% by weight of oxidising salt. 5. An explosive composition as claimed in claim 1 wherein the liquid hydrocarbon fuel is selected from the group consisting of benzene, toluene, xylene and fuel oil. 6. An explosive composition as claimed in claim 1 comprising from 1.5 to 5% by weight of liquid hydrocarbon fuel. 7. An explosive composition as claimed in claim 1 wherein the crystal-growth inhibiting surfactant is selected from the group consisting of water-soluble polysaccharide derivatives, long chain aliphatic amines wherein the aliphatic group contains more than 6 carbon atoms, polyacrylic acid, sulphonated nuclear aromatic compounds, sulphonated dyes, sulphonated polymers, long chain (C6 to C18) alkyl sulphonates, long chain (C6 to C18) alkyl phosphonates and mixtures of any two or more of these surfactants. 8. An explosive composition as claimed in claim 7 wherein the crystal-growth inhibiting surfactant is selected from the group consisting of sodium carboxymethyl cellulose, long chain aliphatic amines wherein the aliphatic group contains from 6 to 18 carbon atoms, sodium methyl naphthalene sulphonate, acid magenta and sodium lignosulphonate. 9. An explosive composition as claimed in claim 1 comprising additionally a deflocculant selected from the group consisting of water-soluble polysaccharide derivatives, polyacrylic acid, polyvinyl pyrrolidone, sodium lignosulphonate, salts of condensates of naphthalene sulphonic acid with formaldehyde and mixtures of any two or more of these deflocculants, the chemical nature of the deflocculant being different from that of the crystal-growth inhibiting surfactant. 10. An explosive composition as claimed in claim 9 wherein the deflocculant is selected from the group consisting of sodium carboxymethyl cellulose and the sodium salts of condensates of naphthalene sulphonic acid with formaldehyde. 11. An explosive composition as claimed in claim 9 wherein the surfactant/deflocculant combination is selected from the group consisting of sodium methyl naphthalene sulphonate/sodium carboxymethyl cellulose; sodium methyl naphthalene sulphonate/sodium salt of a condensate of naphthalene sulphonic acid with formaldehyde; sodium carboxymethyl cellulose/sodium salt of a condensate of naphthalene sulphonic acid with formaldehyde; acid magenta/sodium salt of a condensate of naphthalene sulphonic acid with formaldehyde and sodium methyl naphthalene sulphonate/sodium lignosulphonate. 12. An explosive composition as claimed in claim 1 wherein the surfactant is present in an amount in the range from 0.05 to 2.0% of the total weight of the comminuted oxidising salt. 13. An explosive composition as claimed in claim 9 wherein the deflocculant is present in an amount in the range from 0.05 to 2.0% of the total weight of the comminuted oxidising salt. 14. A method as claimed in claim 1 wherein the deflocculant is selected from the group consisting of water-soluble polysaccharide derivatives, polyacrylic acid, polyvinyl pyrrolidone, sodium lignosulphonate, salts of condensates of naphthalene sulphonic acid with formaldehyde and mixtures of any two or more of these deflocculants. 15. A method of preparing an aqueous slurry blasting explosive composition comprising the steps of comminuting water-soluble crystalline oxidising salt consisting predominantly of ammonium nitrate in a saturated aqueous solution of oxidising salt in the presence of a crystal-growth inhibiting surfactant having a hydrophobic portion and a hydrophilic portion in its molecule to form an aqueous suspension of comminuted oxidising salt and intimately mixing liquid water-immiscible hydrocarbon fuel sensitiser into the suspension at a temperature below that at which all the oxidising salt dissolves in the solution. 16. A method as claimed in claim 15 wherein the crystal-growth inhibiting surfactant is selected from the group consisting of water-soluble polysaccharide derivatives, long chain aliphatic amines wherein the aliphatic group contains more than 6 carbon atoms, polyacrylic acid, sulphonated nuclear aromatic compounds, sulphonated dyes, sulphonated polymers, long chain (C6 to C18) alkyl sulphonates, long chain (C6 to C18) alkyl phosphonates and mixtures of any two or more of these surfactants. 17. A method as claimed in claim 15 wherein a deflocculant is added to the aqueous suspension of comminuted oxidising salt, the chemical nature of the deflocculant being different from that of the crystal-growth inhibiting surfactant. 18. A method as claimed in claim 17 wherein the deflocculant is selected from the group consisting of water-soluble polysaccharide derivatives, polyacrylic acid, polyvinyl pyrrolidone, sodium lignosulphonate, salts of condensates of naphthalene sulphonic acid with formaldehyde and mixtures of any two or more of these deflocculants.