Recovery by Flotation of Mineral Particles of Colloidal Size.

Abstract

In the early stages of the development of the flotation process for concentrating ores, the belief arose that at last a process of ore concentration was available for the successful treatment of the finest particles (1), which in water suspension are collectively known as "slime." It was thought that all mineral particles that are too fine to be recovered by gravity concentration and yet comprise a wide range of sizes float equally well. And, indeed, it is true that flotation is applicable to a wider size range than any of the three principal methods of gravity concentrationjigging, tabling, and vanning. Nevertheless the introduction of ball-mill grinding made it increasingly obvious that particles of all sizes do not float equally well or rapidly. The presence of an upper size limit beyond which flotation is impossible was recognized even before the advent of selective flotation (as contrasted with collective flotation). The existence of a lower size limit beyond which flotation is difficult was suspected, but the limitations of laboratory sizing technique made it difficult to more than surmise that particles of colloidal size are refractory to modern selective flotation operation (2).Definite reduction in floatability with reduction in particle size beyond a critical size of maximum floatability was recently demonstrated (3). The size limits within which recovery by flotation is good were found to be more or less peculiar to each mineral. In general, however, the optimum size of mineral particles for concentration by flotation is between 50 and 10 microns, and the recovery is markedly lower for particles finer than 5 microns.

The Action of Potassium n-Amyl Xanthate on Chalcocite.

“…Effect of time of grinding A series of experiments was made to determine the effect of time of grinding on the reaction-product relationships. The usual experimental TABLE 4 The effect of time of grinding on the reaction products Tests using general experimental procedure, treating with 5.4 milliequivalents of potassium n-amyl xanthate for 15 minutes. Amounts expressed as milliequivalents per 200 g. of chalcocite.…”

“…fifteen minutes. Experimental results are given in table 4 and plotted in figure 4. In the longer grinding tests a considerable vacuum was noted on opening the pebble mill, indicating reaction of oxygen with the mineral during grinding. Increasing difficulty in filtration of the treated pulp was encountered with increasing fineness of grinding.…”

Foaming and gas holdup of esterified nanoparticle dispersions in the presence of sodium chloride

“…It should also be noted that the agglomeration of the particles could result in a greater capture efficiency of particles by bubbles. This effect has long been noticed in the flocculation-flotation process [21,40].…”

Characterisation of frother properties in coal preparation process water

“…Naturally hydrophobic particles like graphite and coal tend to coagulate in solutions containing inorganic electrolytes (Botsaris and Glazman, 1989;Paulson and Pugh, 1996). The formation of coagulates may result in a greater capture efficiency of the particles by the bubbles (Gaudin and Malozemoff, 1933;Matis et al, 1993).…”