Grinding

Rod Milling Variables

Several constructive and fundamental studies have been made in the analysis of data obtained from experiments carried on with batch ball and rod mills. The operating characteristics of ball milling in small continuous circuits have also been appraised. It is from these analyses that some of the theories of comminution have been developed. Data presented … Read more

Ultra-Fine Grinding and Classification

Fluid jet mills-employing a compressible fluid to grind materials to the sub-sieve range, was developed in the early 1930’s, and the subsequent acceptance of these units was the result of their ability to pulverize solids that, because of physical properties, could not be processed by other attrition methods, such as ball, pebble, and hammer mills. … 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

Aerofall Mill Liner Design

According to the manufacturer, a distinctive feature of the Aerofall mill, as compared to the conventional mill, is the special feature of its wedge shape “deflector” liner design (Figures 2 and 3) which was claimed to provide “keying” action in the mill that produces an important part of the crushing and grinding action in the … Read more

Grinding with Low Speed Under-Loaded Ball Mill

The small ball mills and rake classifiers in the London concentrator were replaced by one large ball mill and one hydraulic classifier. This new ball mill was designed oversize so that it could be operated at slower than normal speed. The proper operating conditions were established and the results published. In 1953 this study was … Read more

Single Stage VS Two Stage Grinding

Homestake crushing and grinding-practice was completely revised during the period of 1951-1953. During the conversion, both crushing, plants at the head frames, the Ross and the Yates, were rebuilt. The flowsheet changes at each plant involved replacing the two 8K gyratories with a single thirty inch gyratory for primary crushing to four inch. The gyratory … Read more

Retention Time in Continuous Vibratory Ball Milling

Basic Principles: In a batch mill the length of time during which the material is ground is a direct measure of the energy expended on the material, except possibly for exceedingly fine grinding. The following analysis pertains to a continuous mill operating under these conditions. dE = -C dx/x n…………………………………………..(1) where dE is an infinitesimal … Read more

Grinding Ball Wear & Radioactive Tracer Technique

This paper summarizes the results of an investigation sponsored by The Coates Steel Products Company. The objective was to determine the relative effects of certain chemical and physical properties on the wear resistance of grinding balls when grinding cement. In making this study, a number of types of balls were used in both dry and … Read more

Cement Plant Grinding Mills Power Consumption

To calculate theoretical horsepower required by a grinding mill to reduce feed material to a certain size from Bond grindability test data, it is necessary to apply the “Bond Third Theory of Comminution.” The first step in this procedure is to calculate from the following formula the work index, which is the kw-hr required to … Read more

Grinding Iron Ore in a Wet Autogenous Mill

The Cretaceous plant at the Hill Annex mine of the Jones & Laughlin Steel Corp. was designed with a wet autogenous mill for grinding low grade iron ore so that it could be concentrated by spirals and flotation cells. The plant, on the west end of the Minnesota’s Mesabi Range, went into operation in June … Read more