The variables involved in a complex process like flotation can be classified as follows: a. Disturbance variables – which are undesired properties of the process input which affect the value of the process output but which are not subject to adjustment. They are the result of changes in the properties of the feed, like changes … Read more
The pelletizing process for low grade iron ores has undergone continual changes since its inception over twenty years ago. These changes have necessitated filtration equipment changes in order to produce a product suitable for balling. With modern techniques it is now possible to produce pellets of 68% Fe from ores containing as low as 26% … Read more
A bewildering number of continuous thickeners and clarifiers are used in mineral industries and other heavy industries. General types are: Conventional Thickeners Thickeners with Flocculating Feedwells Solids Contactors Tray Thickeners Lamellas Conventional Thickeners with Lamellas High Flow, Fluid Bed Thickeners These units must be adapted to varied applications. They must provide operating flexibility to meet … Read more
Grinding facilities are arranged either as single-stage circuits, or in a two-stage configuration with ball mills. Another major concentrator, designed with an autogenous mill, ball mill, crusher (ABC circuit), is presently under construction and scheduled for start-up late this year. The host rock of the Island Copper deposit is a highly fractured fine-grained andesite. A … Read more
It is the goal of the Bureau of Mines to help maintain an adequate supply of minerals to meet national economic and strategic needs. Among the activities designed to attain this goal is that of advancing minerals technology by making improvements in metals and minerals processing. Toward that end, the Bureau of Mines has been … Read more
The Greenwich Collieries Co. is a subsidiary of the Pennsylvania Mines Corporation, and a wholly owned subsidiary of the PP&L Co. which serves the northeastern portion of Pa. PP&L annually consumes about 11 million tons of coal per year and is the largest consumer of both bituminous and anthracite coal on the eastern seaboard. Sulphur … Read more
The combustion of pulverized coal is a century-old practice. Many people have investigated coal dust and the residual fly ash particles that remain after combustion. But the combustion process and fly ash formation mechanism are not understood. Working at our Maysville, Kentucky lime plant, the Dravo Lime Company Research team has collected samples of partially … Read more
A closed grinding circuit, typified by a ball mill-cyclone combination, is often required to treat a feed comprised of a variety of minerals of differing properties. Usually, the individual behaviour of the minerals is not assessed, a procedure which requires sizing and metal or mineralogical assaying of each size fraction. Further, sizing is frequently by … Read more
Laboratory and industrial grinding tests have shown that the process of size reduction can be significantly influenced by chemicals added to the powder or slurry being ground. The terms grinding aid or grinding additive refers to a substance which when mixed into the mill contents causes an increase in the rate of size reduction. The … Read more
The calculation of open pit operations’ capacities has been the subject of many studies using computer simulations. The common problems of simulation are that if one desires a realistic picture of an operation the programming work becomes long and expensive and that the program requires a large computer and long time to run. The method … Read more