A sheet of brattice or other material erected in a roadway or face to
remove a combustible gases layer. It is usually set at an angle of about
45 degrees from the horizontal and inclined in the direction of airflow.
See also:pocket of gas
An annular steel ring attached to the upper end of a deflecting wedge,
having a slightly smaller diameter than that of the borehole in which the
wedge is inserted, serving as a stabilizing ring to hold and center the
wedge in the borehole. Also called rose ring. Long
a. Any organic or inorganic material that is used as an electrolyte to
disperse nonmetallic or metallic particles in a liquid, (i.e., basic
materials such as calgonate, sodium silicate, soda ash, etc., are used as
deflocculants in clay slips).
b. A basic material such as sodium carbonate or sodium silicate, used to
deflocculate. Syn:deflocculating agent
a. To disperse a clay suspension so that it has little tendency to settle
and has a low viscosity. ACSG, 2
b. To break up from a flocculated state; to convert into very fine
particles. CF:peptize
a. The thinning of the consistency of a slip by adding a suitable
electrolyte. ASTM
b. The process of making clay slips or suspension using electrolytes or
deflocculants.
An agent that prevents fine soil particles or clay particles in suspension
from coalescing to form flocs. Syn:deflocculant; dispersing agent.
ASCE
A state of colloidal suspension in which the individual particles are
separate from one another, this condition being maintained by the
attraction of the particles for the dispersing medium (for example,
hydration) or by the assumption of like electrical charges by the
particles, thus resulting in their mutual repulsion, or both. It is
generally possible to deflocculate a gel to such an extent that it loses
its gel strength entirely, thus becoming a Newtonian fluid, in which case
it is known as a sol. The relative contribution of hydration and
electrostatic repulsion to the deflocculation of a suspension accounts in
large measure for the wide variation in viscosities and gel strengths of
suspensions partially flocculated by different means; as, e.g., a partial
flocculation of drilling fluid by cement on one hand, and by salt water on
the other. Some suspensions can be deflocculated repeatedly by mechanical
agitation alone, thus giving a reversible gel-sol, sol-gel transformation
known as thixotropy. Brantly, 1
a. A general term for the process of folding, faulting, shearing,
compression, or extension of the rocks as a result of various Earth
forces. AGI
b. See:strain
Parts of a crystal that have rotated differently during deformation to
produce bands of varied orientation within individual grains.
ASM, 1
Crossbedding with foresets overturned or buckled in the down current
direction, usually prior to deposition of the overlying bed. Foreset dip
angle may also be altered by subsequent tectonic folding.
Pettijohn, 1
A crystal bent or twisted out of its normal shape, so that the angle
between its crystal faces may differ widely from those on the regular
form. See also:distorted crystal
An agent, e.g., butanol, that destroys or inhibits froth. Pryor, 1
Progressive loss of gases in a substance leading to the formation of a
more condensed product. Applied primarily to the formation of solid
bitumens from liquid bitumens, but also used in connection with coal
formation. Tomkeieff
A substance that can be added to molten metal to remove soluble gases that
might otherwise be occluded or entrapped in the metal during
solidification. ASM, 1
a. Removing gases from liquids or solids. ASM, 1
b. In pyrometallurgy, addition of deoxidants (phosphorus, aluminum,
silicon, etc.) to remove hydrogen from molten metals before casting.
Pryor, 3
a. The equipment for extracting gas from an oil-well drilling fluid. The
presence of gas reduces the density of the fluid. Nelson
b. The pumps and equipment used in methane drainage. Nelson
Method of demagnetization in which a substance is passed through a coil
that carries alternating current of progressively diminishing strength.
Pryor, 3
a. The general lowering of the surface of the land by erosion, esp. by the
removal of material through the action of flowing water.
b. Breakage of coal incidental to mining, handling, transport, or storage.
c. The excessive crushing of coal during cutting, loading, and
transportation. All face machines cause degradation, and this has become a
problem at collieries where the market calls for the larger sizes. The
degradation of a coking coal is of lesser importance.
See also:gradation; fragmentation. CF:aggradation
Syn:breakage of coal
Screens used for removing the small sizes, caused by breakage in handling,
from sized coal just before it is loaded for shipment. Degradation
screening is usually necessary where a sized coal is picked, mechanically
cleaned, stored, conveyed, or otherwise handled so that breakage occurs
after it is sized on the main screens. This applies particularly to
domestic coal, which should reach the consumer in as attractive condition
as possible. Mitchell
Illite that has lost much of its potassium as the result of prolonged
leaching. AGI
Removal of oil and grease films from metal surfaces before electroplating,
galvanizing, or enameling. Pryor, 3