Grinding

Particle Size Distribution of Grinding Mill Products

This report briefly reviews the essential features of moment analysis and describes extension of this method to size reduction by ball mill grinding. Method of Analysis of Size Distribution Data Size analyses of mineral products are usually made by screening with a set of sieves having mean apertures arranged in the Tyler scale, which is … Read more

Optimizing Grinding and Regrinding Capacity in Mill Design

The intent of this paper is to try to answer the complex question: “How much grinding capacity should be designed into a new mining – milling project?” Much work has been devoted to the technical aspects of grinding, the “how” of grinding. But, in the writers’ opinion, the economically important subject of optimizing grinding capacity in … Read more

Electric Drives for Large Ore Grinding Mills

Ore grinding mills are really just slowly rotating barrels, but barrels that are growing in size so fast that the application of electric drives for them is rapidly approaching a technology like that for wind tunnels or pumped storage drives. This application is particularly worthy of care because some 40% of the 75 megawatts of … Read more

Coarse Grinding in a Ball Mill

Rod mills were developed as a logical substitute for the rolls crusher when larger tonnages had to be handled, on a continuous basis. Today, with even larger tonnages to process, the trend is to install larger equipment, automate the plant and develop the highest availability possible, in order to cut costs. The rod mills, because … Read more

Basic Control Strategy for Mineral Processing

The principle purpose of applying control to any process is to improve its profitability. Even when considering the impact of a plant on its surrounding ecology this is still true, since the sanctions felt most immediately from violations of the regulations are the economic penalties or fines which result. Economic performance can be improved within … Read more

Semi-Autogenous Liners

The never ending search for lower unit costs led Pima Mining Company’s management to study various alternatives shortly after Expansion III was completed. It soon became apparent that a considerable amount of ore assaying 0.35% copper had to be moved in order to maintain mill feed at the desired 0.54% copper content. New Mill Flowsheet … Read more

Low-speed Gearless Converter Drive

The first motors of this type were built to drive ball mills in the cement industry, which are very similar to those employed for ore processing. Here, too, the tendency is to build units of ever increasing capacity. In the case of conventional drives with mechanical gearing, this involves correspondingly increasing difficulties. Technical principle A … Read more

Grinding and Concentration of Conglomerate Copper Ore

The conglomerate ore analyzed approximately 1.2% copper. The specific gravity of the ore was 2.72 and the bulk density was 108 pounds per cubic foot (determined on “as is” ore). The Bond laboratory ball mill work index was determined as 22.0 at 65 mesh. Autogenous Grinding Tests Crude ore was fed manually to the mill, … Read more

Simulation of Dry Ball Milling using Specific Power

The energy-size reduction relationship was the dominant form of mathematical model used in the description of tumbling mill grinding processes. Typically, in these models some single measure of product fineness (e.g. the 80% passing size, the size modules, the specific surface area) is chosen as the dependent variable and the energy input per unit mass … Read more