Crushing & Screening

Screw Crusher

The Freeport Sulphur Co. built a portable crusher in 1944 that solved a problem that none of the crusher manufacturing companies contacted were able to do. Two of these crushers have now been in service for 6 years, giving satisfactory service in handling a million tons per year, and having a capacity of over 2000 … Read more

Hardness and Toughness of Rocks

The speed of drilling rock has become an important factor in mining operations, while the placement of holes, kind, and quantity of explosive used are equally important. These are a function of the rock hardness and toughness. Both of these factors must be considered in compiling a table that will enable a mine operator or … Read more


Le concassage constitue la premiere etape de la comminution. Son objectif n’est pas la liberation des mineraux, mais simplement la reduction de dimension afin de faciliter la manipulation ulterieure du minerai. II est normalement fait a sec en deux ou trois etapes. L’alimentation provient de la mine et a une dimension pouvant aller jusqu’a 1.5 … Read more

Crushing Chestnut to Produce Buckwheat

The crushing of chestnut-size (1-5/8 by 13/16 inch) Pennsylvania anthracite in four commercial crushers (impact, jaw crusher, hammer mill, and gyratory types) was studied by the Bureau of Mines to determine which could produce the largest proportions of buckwheat Nos. 1 and 2 sizes (9/16 by 3/16 inch). Single pass dry and wet crushing techniques … Read more

Crushing Granite

The quarry is located in the western part of the Piedmont Plateau. Geologically, this province is described by Watson as an area of highly metamorphosed sedimentary and igneous rocks of Paleozoic and pre-Paleozoic age. The Piedmont region of South Carolina has extensive areas of granite and gneiss that are suitable for aggregate. The gneisses have … Read more

Conveyor Belt Fire Hazard

This investigation showed that neoprene, polyvinyl chloride, and rubber belts ignite readily when subjected to an impinging flame. Although pre-heating of the belt is not necessary for ignition, preheating does increase the probability of developing a self-sustaining flame after ignition. The time and total quantity of heat required to ignite neoprene were greater than those … Read more

Impact Crushing Size Distribution

Although the comminution process has undergone much experimental study, there is not yet an adequate theoretical basis for predicting the mean size and size distribution of the product from a comminution machine. This lack is hardly surprising, since most of the considerable body of knowledge concerning the deformation of solids becomes inapplicable when the stresses … Read more

Bin Hopper Flow Design & Engineering

A detailed Bin Hopper Flow Design & Engineering Study: The mining industry in the United States alone produces nearly 4 billion tons of new bulk materials annually that has a mine-mouth value in excess of 20 billion dollars. The potential for realizing substantial savings in mining and processing costs through improved materials handling systems design … Read more

How to Test the Strength of Rocks

This paper reviews the progress made in testing the strength of rocks, ores, coal, salts, and other minerals as they are encountered in mine operations. It attempts to correlate the results of these physical measurements with technological properties more useful to the mining engineer: abrasive hardness, grindability, and behavior in comminution on one hand, and … Read more

Dedusting and Dust Collection

It is generally accepted that no method of coal cleaning except froth flotation is effective in cleaning dust. In the majority of coals mined in the United States the dust sizes contain a high percentage of impurities, hence the removal of the dust from the coarse sizes lowers the impurity content of these sizes. Dedusted … Read more