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: … Read more

Double Cycloning

In conventional closed circuit grinding practice including classification in one hydrocyclone, or in a group of hydrocyclones in parallel, classification takes place in a single stage. Under conditions where the fineness of the overflow product is expressed e.g. as 95 % – x microns, the normal sharpness of size separation (recovery) at size x into … Read more

Carbonaceous Gold Ore Mineralogy

Mineralogy and Occurrence of Gold: The term “carbonaceous” has been loosely applied to ore constituents of widely varying characteristics. Laboratory investigations by A. S. Radtke and B, J. Scheiner (1970) of the U. S. Geological Survey and the U. S. Bureau of Mines on carbonaceous ores from Carlin showed that they contained: (1) an activated carbon … Read more

Titanium Castings by Sand Molding Process

Objective To produce industrial-grade titanium castings by processes that are nonpolluting and lower cost than the currently used rammed-graphite process. Approach Foundry-grade zircon and olivine sands, bonded by waterglass or bentonite, are used to make shell or rammed molds which require relatively low-drying temperatures and do not generate noxious fumes during drying or casting. Procedures … Read more


Thiourea (H2NCSNH2) is an organic compound, the crystals of which dissolve in water to yield an aqueous form stable in acidic solutions. The unique feature of thiourea is that, in aqueous solution it reacts with certain transition metal ions to form stable cationic complexes. For example, the following generalized reaction illustrates the complexing role of … Read more

Sulfurous Acid Leaching of Kaolin for Preparing Alumina

The Bureau of Mines is conducting a program to evaluate technology for the recovery of alumina from domestic resources. Bauxite, the major alumina ore, is mainly imported. In recent years, bauxite-producing countries have formed an organization that attempts to control the supply and price of bauxite. The United States has only limited reserves of bauxite … Read more

Ferrous Scrap Steel

For the past decade, the Bureau of Mines has addressed the problem of using low-grade scrap, such as the ferrous fraction of municipal refuse, to produce steels of acceptable quality. The investigations are a part of the Bureau’s 65- year commitment to minimize the requirements for mineral commodities by devising new technologies for the recovery … Read more

Copper & Nickel Solvent Extraction

Nickel and copper were co-extracted from ammoniacal ammonium sulfate leach liquors (pH-9.5) with LIX 64N extractant in a laboratory-size mixer-settler continuous circuit. Three extraction stages resulted in >99-pct extraction of nickel, substantial copper extraction, and essentially no cobalt extraction from leach liquors. A crowd stage reduced the ammonia loading on the solvent by maximizing nickel … Read more

Sodium Silicate Uses & Applications

The practical application of common alkaline inorganic chemicals such as lime, soda ash, caustic, silicates and phosphates, in the beneficiation of minerals, is well known within the industry. These materials have been found to be useful throughout the flotation circuit. This paper discusses the chemistry of the soluble sodium silicates in relation to their use … Read more

Sludge Dewatering by Pressure Filtration

Pilot test results with 30% refuse slurry suggested the installation of two (2) Passavant Pressure Filters, Model 20 with 150 chambers each and a cake thickness of 40 mm. Each filter plate is 2m x 2m in size and the total cake capacity of each filter is 762 cu. feet. The sludge pumping requirements, per … Read more