High Speed Vertical Screw Bulk Unloading
The Siwertell screw unloader operates at an average rate of 600 t/h with a peak capacity of over 800 t/h. The unloader consists of three screw conveyors that dig the bulk cement from the hold and deliver it to the dockside belt conveyor. The unloader will be discussed in much greater detail later in this […]
Hydraulic Mining Methods
Although hydraulic mining was introduced in the United States before the turn of the century, it has not gained the degree of acceptance found in other countries such as Russia, China, Germany and Canada. The hydraulic mining research program, which was initiated in 1958 by the Bureau of Mines and the subsequent research by other […]
Wire Ropes & Mine Hoisting
Although wire rope has been in use for over 100 years, it is a complex structure that is still not well understood. Wire ropes are made in diameters from less than 1/32 to more than 7 in and can have as many as 900 individual wires. The mining industry uses a lot of wire rope, […]
Biological Leaching of Manganese Ores
Biological leaching of low-grade ores has been gaining interest and acceptability in recent years. Sulfide ores, which are subject to oxidation of specific bacteria such as Thiobacilli, are being bioleached commercially. Other ore types, especially oxides and silicates, have been examined for their leachability by microorganisms. Ehrlich (1980), Holden and Madgwick (1983), Groudev (1987), and […]
Selective In Situ Leach Mining of Manganese Ores
The Bureau of Mines is conducting research to develop cost effective, environmentally compatible advanced mining technologies for the selective extraction of critical and strategic metals. Critical and strategic metals (e.g. manganese, cobalt, and chromium) are essential to domestic steel, aerospace, electronic and defense-oriented industries. The United States no longer has high-grade deposits of these minerals […]
Thiol Type Collectors Adsorption Mechanisms
The formation of metal xanthate can be considered to comprise an initial electrochemical reaction (E), MS → Mn+ + nS° + ne……………………………………………………………[1] followed by a chemical reaction (C), Mn+ + nX- → MXn………………………………………………………………..[2] Thus, the xanthate adsorption mechanism is controlled by both Eh and pK, and consequently, one can expect that the same may be applied to […]
Unsaturated Setting Affects in Situ Copper Leaching
Hydraulic properties and characteristics of copper ore associated with the Casa Grande deposit at the Casa Grande mine are investigated by the Bureau of Mines to assess permeability and its impact on flow capacity during in-place, copper leaching operation. The copper ore is a heterogeneous, unsaturated, and fractured medium in which the permeability is dominated […]
How Froth Affects Column Flotation
The importance of the froth phase in establishing flotation performance has long been recognized. If the froth phase is insufficiently stable, mineralized bubbles which enter the froth layer rupture prematurely, causing valuable particles to drop back into the pulp. On the other hand, too stable a froth may result in nonselective entrainment of excessively large […]
Hydrophobic Coagulation
A novel ultrafine coal cleaning process has been developed at Virginia Tech that is capable of producing superclean products. Compared to other selective aggregation processes, such as oil agglomeration and selective flocculation, this process relies on the natural hydrophobicity of the coal surface to induce the selective coagulation of coal particulates in an aqueous suspension. […]
Improve Flotation Kinetics by High Intensity Agitation
Flotation is the most widely used beneficiation technique in the minerals industry. The kinetics of flotation is governed by the rates of bubble-particle attachment and bubble-pulp separation. Both processes interact significantly in a conventional flotation unit operation, making it virtually impossible to optimize one of the processes without sacrificing the effectiveness of the other. In […]