- 行业: Mining
- Number of terms: 33118
- Number of blossaries: 0
- Company Profile:
The U.S. Bureau of Mines (USBM) was the primary United States Government agency conducting scientific research and disseminating information on the extraction, processing, use, and conservation of mineral resources.
Founded on May 16, 1910, through the Organic Act (Public Law 179), USBM's missions ...
Two horizontal timbers separated by striking wedges and supporting an arch center. The latter is lowered by slacking the wedges.
Industry:Mining
Two impedances having resistive components that are equal and reactive components that are equal in magnitude but opposite in sign are known as conjugate impedances.
Industry:Mining
Two insulated-copper leading wires wrapped together with paraffined cotton covering.
Industry:Mining
Two kinds are available, flexible and rigid ducts. Flexible ducts generally consist of flexible tubes made from fabrics coated with rubber or polyvinyl chloride, a nonflammable substance. They are available in varying lengths. Flexible ducting is suited for face ventilation in a variety of mining methods. It is suited also to crooked 3488 workings of limited extent. It has a higher resistance and a greater tendency to leak than rigid ducting. Rigid ducts are made of steel or fiberglass in lengths suitable for underground transport. This type of duct does not have to be accurately aligned and is therefore used, in the smaller sizes, in subsidiary work, particularly in crooked headings. For main tunnels where leakage must be minimized, flanged joints are used with suitable gaskets.
Industry:Mining
Two nitrides are known: TaN, melting point, 3,090+ or -50 degrees C; Ta<sub>2</sub>N , which loses nitrogen at 1,900 degrees C.
Industry:Mining
Two or more endless chains to which crossbars are attached at spaced intervals, each having affixed to it a series of pointed rods extending in a vertical plane on which work is carried. Used principally in spraying or washing operations where the least amount of area of the product is contacted.
Industry:Mining
Two or more fault sets that were formed at the same time. Compare: fault set
Industry:Mining
Two or more mineral species having identical or closely related structures; e.g., hematite group or zeolite group.
Industry:Mining
