How to Assay Ores Concentrates and Bullion
Many mineral samples are sent to Government agencies with the request that they be assayed or chemically analyzed. It should be emphasized that there are no Federal agencies, except for the U.S. Mints, where assays and quantitative analyses are made for the public. Many of the States maintain a Bureau of Mines, a Geological Survey, […]
Bowl Concentrators
Bowl concentrators have been used only to a limited extent in small placer operations. The two most popular designs were the Ainlay and Knudsen bowls. There is little difference in design and operation between the two, except for riffle design and minor variations in bowl size and shape. They were used primarily as cleaners, but […]
Shaft Sinking
In shaft sinking for coal mines, the cost item greatly influences the method adopted. This holds true especially when soft material must be traversed. The average life of a coal mine is short. This is due either to the limited area of the coal basin or to the great expense of maintenance and haulage underground […]
Electrolytic Zinc
I want to emphasize the point brought out: if solutions are absolutely pure, the tank-house troubles are very few. If you have one part in two million of antimony, you will have trouble, and lots of it, in the cell room; that is about the gage you might take of the degree of purity to […]
Grinding Circuit Control Strategy
Figure 4 is a schematic diagram of a ball mill/cyclone control system. This diagram shows the instrumentation and the calculated variables used in the control strategies. The prior detailed process analysis study produced two major conclusions: Reduce mill feed size Reduce ball charge size The reduction of the mill feed size could be reduced by […]
Sinter Reduction
First, the relation between straight lime basic sinter’s susceptibility to disintegration and basicity was examined under various boundary conditions. Some selected results are shown in Figure 2: for variable fuel rates disintegration is governed by various influence factors: first, there is the well-known maximum as a function of basicity. More surprising is an additional effect: […]
Belt Conveyor Design
Idlers: Due to the efforts of the Conveyor Equipment Manufacturers Association, the basic idler elements—idler roll wall thickness, bearing sizes and shaft sizes—have been standardized into classes. There is also a substantial dimensional commonality as well. Belting: Again, the rubber manufacturers have standardized, either by agreement through industry associations, or by following the leader and […]
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 […]
How to Determine the Strength of a Mine Roof
In an earlier phase of the investigation, an experimental room was progressively mined to an areal dimension of 50 by 100 feet. As the dimensions of the room were increased, the roof separated into horizontal layers that were loaded only by their own weight. The maximum stress and the elastic behavior of the lowest roof […]
Manganese Removal Case Study
The Problem Relatively low manganese levels in water can result in tainting of taste as well as discoloration of the water and the surfaces it comes into contact with. The Drinking Water Inspectorate (DWI) in the United Kingdom have set a maximum allowable limit of 50ppb, well below the WHO guidelines of 400ppb. While the […]