Photoelectric Charging & Electrostatic Separation
Electrostatic separation is used when froth flotation fails, such as with oxidized ores, or where there are similarities in response with magnetic and gravitational methods, or when the use of water is to be avoided. Theoretically, for fine-size particles the electric field has an advantage over the magnetic field in that the viscosity-limited particle velocity […]
Effect of Preheating Iron Ore Pellets
The production of pre-reduced iron ore pellets involves the expenditure of considerable capital and energy. Both prereduced and oxide pellets can be produced in similar equipment by using reducing and oxidizing processes, respectively. However, the throughput for a 5-m-ID by 50-m-long kiln with a preheating grate is 425,000 metric tons per year of ore, according […]
Electrodynamic Separator
Several years ago, the Bureau of Mines initiated a program to develop effective methods for reclaiming and recycling metal and mineral values contained in urban solid waste. The Bureau’s initial work at its College Park (Md.) Metallurgy Research Center dealt with establishing reliable methods for sampling and characterizing the residues left from the incineration of […]
Applied Mining Geology
The geologic notes are taken as soon as possible after the ground is broken so that any mistake in the mining may be corrected at once, or any particularly advantageous procedure may be suggested before any useless work is done. Taking the notes underground is a comparatively simple matter, but a few necessary precautions may […]
Small Scale Metal Recycling Plant & Equipment
Of the 220 million tons of refuse collected annually in the United States, it is estimated that about 30 million tons are incinerated, generating about 7 million tons of residues. In previous work, the Bureau of Mines developed a continuous mechanical process capable of converting 85 percent of municipal incinerator residues into potentially useful products. […]
How to Remove Pyrite from Coal
In recent years, coal research has been directed toward environmental problems of the electric power generation industry. A major problem of coal-burning power-plants is reducing the air pollutants in stack gases. In most of these plants, the chief pollutant is SO2, which results from the combustion of sulfur compounds present in the coal. Stack-gas cleaning […]
How to Separate Copper from Scrap by Melting
The secondary metals industry has been a major segment of the domestic economy for years. Many secondary commodities (heavy melting steel and lead storage batteries are familiar examples) have become so well established and recycled so promptly that industry commitments for metal would be impossible without them. Although some recovery and refining processes developed for […]
Copper Smelting
Throughout this century the major production of copper (as it relates to Copper Smelting) and most other nonferrous metals has been through pyrometallurgical methods, treating sulfide ores by various batch processes. The predominant copper process is reverberatory furnace smelting of sulfide concentrates to produce matte and slag, followed by treatment of the matte in converters […]
Permanent Magnets
The magnetic properties of rare earth-cobalt intermetallic compounds have been studied by various investigators. It was not until Strnat and Hoffer investigated single crystals of YCo5 and reported an extremely high magnetocrystalline anisotropy that systematic studies of the magnetic properties of rare earth-cobalt alloys were undertaken. These studies determined that RCo5 compounds (R = one […]
Kaolin Attrition Grinding
Fine grinding research has resulted in the development of an attrition grinding process: that has been successfully used for ultrafine grinding of various solid materials. The process was initially developed and patented by the Bureau at the Tuscaloosa Metallurgy Research Laboratory to grind coarse paper-filler kaolins to finer, paper coating-grade clay. The fundamental objective of […]