See:actinolite
Highly porous, granular aluminum oxide that preferentially absorbs liquids
from gases and vapors, and moisture from some liquids.
McGraw-Hill, 1
Carbon, mostly of vegetable origin, and of high adsorptive capacity.
Syn:activated charcoal
See:activated carbon
A clay whose adsorbent character or bleaching action has been enhanced by
treatment with acid. CCD, 2
With a view to applying the coal plow to seams too hard to be sheared by
the normal cutting blade, German mining engineers have developed various
types of power-operated cutters. One consists of a series of
compressed-air picks mounted above each other; another, of a resonance
pattern, houses two high-speed motors eccentrically mounted and rotating
in opposite directions. The latter imparts a vibration to the cutting edge
equivalent to 2,500 blows per minute with a stroke of 3/16 to 1/4 in (4.8
to 6.4 mm) and a force of approx. 200 st (181 t). Mason
See:Huwood slicer
a. A substance that when added to a mineral pulp promotes flotation in the
presence of a collecting agent. Syn:activator
b. Reagent used particularly in differential mineral flotation to help
cleanse the mineral surface so that a collector may adhere to it and
permit or aid its floatability. Frequently used to allow floating minerals
that had been previously depressed. Mitchell
a. In the flotation process of mineral dressing, the process of altering
the surface of specific mineral particles in a mineral pulp to promote
adherence of certain reagents. Pryor, 3
b. The changing of the passive surface of a metal to a chemically active
state. CF:passivation
c. In the flotation process of ore beneficiation, the process of altering
the surface of specific mineral particles in an ore pulp to promote
adherence of certain reagents. Henderson
d. The process of making a material radioactive by bombardment with
neutrons, protons, or other nuclear particles.
See also:activation analysis
A method for identifying and measuring the chemical elements in a sample
to be analyzed. The sample is first made radioactive by bombardment with
neutrons, charged particles, or other nuclear radiation. The newly
radioactive atoms in the sample give off characteristic nuclear radiations
that can identify the atoms and indicate their quantity.
See also:activation
a. In flotation, a chemical added to the pulp to increase the floatability
of a mineral in a froth or to refloat a depressed (sunk) mineral. Also
called activating reagent. CTD
b. A reagent that affects the surface of minerals in such a way that it is
easy for the collector atoms to become attached. It has the opposite
effect of a depressor. CF:depressor
c. A substance that is required in trace quantities to impart luminescence
to certain crystals. CCD, 2
d. Ions that are photon emitters. Van Vlack
e. Any agent that causes activation. See also:activating agent
Bennett
Surface-active substance that immunizes solids against a parting liquid.
Hess
The minimum value of lateral earth pressure exerted by soil on a
structure, occurring when the soil is allowed to yield sufficiently to
cause its internal shearing resistance along a potential failure surface
to be completely mobilized. See also:surcharge
CF:passive earth pressure
An entry in which coal is being mined from a portion thereof or from
connected sections. USBM, 1
One liable to further movement. CF:passive fault
a. The surficial deposit that undergoes seasonal changes of volume,
swelling when frozen or wet, and shrinking when thawing and drying.
AGI
b. A surface layer of ground, above the permafrost, that is frozen in the
winter and thawed in the summer. Its thickness ranges from several
centimeters to a few meters. AGI
a. The area, on and beneath land, used or disturbed in activity related to
the extraction, removal, or recovery of coal from its natural deposits.
This term excludes coal preparation plants, areas associated with coal
preparation plants, and post-mining areas. SME, 1
b. The area in which active mining takes place relative also to extraction
of metal ores, industrial minerals, and other minerals of economic value.
All places in a mine that are ventilated and inspected regularly.
Federal Mine Safety
a. In nuclear physics, the rate of decay of atoms by radioactivity. It is
measured in curies. Bennett
b. The ideal or thermodynamic concentration of a substance, the
substitution of which for the true concentration, permits the application
of the law of mass action. See also:ionization constant
See:absolute age
The breaking load obtained from a tensile test to destruction on a sample
of rope. Hammond