Improvements in or relating to methods of concentrating ores

摘要

The separation of acidic materials from other ore constituents by flotation, stratification, tabling and like processes is effected in the presence of N-alkyl polyalkylene polyamines or their acyl derivatives of the formul : or salts thereof, where n is an integer not greater than 6, x an integer not greater than 5, y is zero or an integer not greater than 4, R is an alkyl or substituted alkyl group of from 8-32 carbon atoms, and R1 is hydrogen or an alkyl or substituted alkyl group. The temperature at which acylation is effected determines whether the acyl derivative is a straight chain compound or an imidazoline. The compounds may be prepared by treating polyalkylene polyamines such as diethylene triamine, triethylene tetramine, tetraethylene pentamine, dipropylene traimine or mixtures thereof, made by heating an alkylene chloride with ammonia under pressure, with an alkylating agent having from 8-32 carbon atoms such as lauryl or cetyl bromide to form mono- or di-alkyl derivatives. Further alkyl or substituted alkyl groups may be introduced using such alkylating agents as methyl bromide, ethyl iodide, ethylene chlorhydrin, esters of chloracetic acid or of chlorhydrins, and benzyl chloride. The N1-acyl derivatives may be prepared by heating with fatty acids, especially those having at least 9 carbon atoms, e.g. lauric, palmitic, stearic, oleic, ricinoleic, capric, myristic, mixtures of fatty acids from fats and oils, the glycerides themselves, such as vegetable and fish oils, or carboxylic acids such as talloel or naphthenic acid. The process is particularly useful in the separation by froth flotation of silica or silicates from non-metallic ores such as phosphate rock. The compounds are used in amounts ranging from 0.2 lb. per ton of ore, either alone or with other promoters, or materials such as hydrocarbon oils, fatty acids or esters. They may be used in aqueous solutions or emulsions or in organic solvents such as alcohol. In Examples: (1) N-cetyl triethylene tetramine acetate is prepared by heating the polyamine and cetyl bromide at 150 DEG C., extracting the alkylated base, and adding acetic acid. Such compounds may be acylated. Thus N-decyl diethylene triamine is heated to 185 DEG C. with fatty acids of coconut oil to form the N1-acylated compound. The same product can be made by alkylating the amide formed from diethylene triamine and coconut oil fatty acids; (2) the hydrochloride of N-ethoxy-N1-stearoyl diethylene triamine is made by refluxing the monostearoyl amide with ethylene chlorhydrin; (3) coconut oil and mixed polyethylene polyamines are heated to form the mono-fatty acids amide which is alkylated with 2-brom-octane; (4) m -heptadecyl-N-2-aminoethyl imidazoline, prepared by heating equimolar quantities of stearic acid and diethylene triamine to 270 DEG C., is refluxed with ethylene chlorhydrin to give the hydrochloride of the N-(2-ethoxy-aminoethyl) derivative; (5) the reaction product of coconut oil and mixed polyethylene polyamines is heated with 2-brom-octane to give the alkylated m -alkyl imidazoline. Results are given of flotation tests on deslimed phosphate rock using pine oil with N-(N1-hydroxyethyl aminoethyl)-m -heptadeyl imidazoline hydrochloride, N-stearoyl-N1-hydroxyethyl diethylene triamine hydrochloride, N-lauroyl-N1-octyl diethylene triamine hydrobromide, N-(N1-octyl aminoethyl)-m -dodecyl imidazoline hydrobromide or cetyl triethylene tetramine acetate as promoter. The treatment of rake classifier sands from cement plants and of iron ores also is referred to.