Depolarizing Magnetite Pulps

In classification of pulps bearing magnetized ferromagnetic particles, depolarizing is of great importance. If size separation is to be effective, particles must be individual rather than in flocs. Depolarizing is also practiced in heavy medium separations in which ferrosilicon or magnetite is the medium. Properties of Ferromagnetic Materials: Experimental work, described below, has shown that … Read more

Comparison of Overflow and End Peripheral Discharge Mills

In a previous article the authors outlined a study of the variables in rod milling and also reported data from a series of open circuit grinding tests on a massive limestone in a 30-in. x 4-ft end peripheral discharge rod mill. As a second part of the experimental program, an analysis is now presented for … Read more

Method of Preparing Closely Sized Micron and Submicron Fractions

Study of light adsorption, reaction rates, electrophoresis, particle packing, and corrosion is hindered by lack of a suitable method of preparing small amounts of closely sized materials in the micron and submicron range. Most fractionation methods depend on some form of particle movement through a viscous media in which velocity of a particle, relative to … Read more

Belts and Concrete Ore Passes

Conveyors were first used underground at Miami Copper Co., in the latter part of 1947. At that time some of the stoping area was too heavy and too close to the haulage level to use conventional haulage. To get the haulage drifts out from under the stoping area belt conveyors were used for the additional … Read more

How to Control Flotation Reagents

Reagent control in flotation is more an art than a science. Operators vary the amount of reagents used according to the metallurgy obtained. The amount of collector may be increased, for example, if tailings losses are high and decreased if concentrate grades are low. Often control decisions are based on only one assay, such as … Read more

Placing Concrete in a Deep Mine

In U. S. underground mines concrete work is not widely used. Timber and steel are cheaper, and there are few serious water problems. But in the Union of South Africa men dig deeper, more persistently, and probably more profitably than anywhere else on earth. Some gold mines near Johannesburg are below the 10,000 level and … Read more

Ball Mill Shell Liner Performance

Grinding Practice—These tests were run in the 9 ft diam by 8 ft long grate discharge ball mills at Climax. Each mill functions in closed circuit with a 78 in. Akins duplex high-weir classifier, and a circulating load of 300 pct is maintained. The size of the mill feed is 6 pct on 3/8ths, which … Read more

Mine Ore Mining Methods

Iron king mine, producing gold-silver-lead-zinc ore, is 10 miles east of Prescott, Ariz. At present the 1806 level is being developed. The echelon pattern of ore deposit continues at depth but is less pronounced, and the orebody is now more or less continuous over 2600 ft of strike length, with widths 5 ft to as … Read more

Mineral Flotation with Ultrasonically Emulsified Collecting Reagents

An emulsion is a two-phase system consisting of two incompletely miscible liquids, the one being dispersed as finite droplets in the other. The dispersed liquid is known as the internal or discontinuous phase, and the surrounding liquid is termed the external or continuous phase. Apparatus and Experimental Procedure: Ultrasonic emulsification was performed in three steps, although … Read more

How to Measure the Tensile Strength of Rocks

Principle and equipment are the same as for the test for tensile strength of hydraulic-cement mortar. The test specimen has the shape of a briquet. While in the original cement mortar test the briquet is cast in a special mold, it is prepared from rocks in different ways, depending on how easily they can be … Read more