Prospecting undertaken after scout prospecting has disclosed the existence
of values. Preliminary prospecting helps to determine approx. the extent
of the payable ground. Griffith
A quick investigation of surface or near-surface conditions; no special
equipment is employed. Tests are carried out on site for approximate
classification of soil and are limited to visual or other simple tests.
See also:detailed soil survey; general soil survey. Nelson
The detonation of an explosive charge earlier than warranted. Premature
explosion may be due to carelessness, accidental percussion, a faulty
fuse, or degenerated explosives. See also:safety fuse; hangfire.
Nelson; Pryor, 3
An obstruction or block in a core barrel or bit that prevents the entry of
core into the barrel before the bit can be advanced far enough to cut a
length of core to fill the barrel. Long
The detonation of an explosive charge or the initiation of a blasting cap
before the planned time. Meyer
a. The hardening of cement in a shorter time than normal or estimated.
Long
b. This may be caused by the addition of catalysts to cement to increase
setting time or by downhole temperatures and pressure that cause cement to
set prematurely.
Tin of such high purity as to rate a special bonus in the metal market.
Pryor, 3
Aggregate that has been coated with bituminous binder before spreading.
See also:penetration macadam; tarmacadam. Nelson
a. The treatment of ore or coal to reject waste. See also:concentration;
ore dressing; preparation plant.
b. The process of preparing run-of-mine coal to meet market specifications
by washing and sizing. Jones, 1
In bituminous coal mining, a foreman who is in charge of the operations of
washing and sizing coal for market at the washery plant. DOT
Strictly speaking, a preparation plant may be any facility where coal is
prepared for market, but by common usage it has come to mean a rather
elaborate collection of facilities where coal is separated from its
impurities, washed and sized, and loaded for shipment.
Syn:cleaning plant
BCI
Mining operations to facilitate mining proper after having explored a
deposit and having made it accessible both in strike and dip. This work is
executed almost entirely within the deposit and includes making: (1)
inclines and transfer stations with manways; (2) sublevel drives between
the levels; and (3) various crosscuts, chutes, minor shafts, raises,
winzes, and other works. Stoces
a. To shear or undermine coal so that it can be readily blasted loose.
Fay
b. Arkansas. To make a cartridge for a blast. Fay
c. Arkansas. To charge a blasthole. Fay
The lead or stagger that exists between planing blades in the same
vertical plane of a plow. Nelson
A semimetallized pellet developed by the U.S. Bureau of Mines from
taconite concentrates. The process involves rolling the concentrates into
pellets, then drying, calcining, and roasting the pellets in a reducing
(oxygen-deficient) atmosphere. During the heat-hardening stage, the
pellets are partly converted to metal. Use of these pellets causes a
considerable increase in pig-iron production. See also:iron ore
An arrangement by which a gear level can be moved, but the resulting speed
shift will not take place until the clutch or the throttle is manipulated.
Nichols, 1
Eng. Stone of suitable thickness for shaping into a tile stone without
frosting; occurs in Stonesfield slate series and Chipping Norton limestone
of the Cotswolds. Arkell
a. The present value of a mine may be considered to be a sum of money that
may be allowed for the purchase, development, and equipment of a mine,
with the expectation of receiving for this capital expenditure, during the
estimated life of the mine, the return of this capital plus a substantial
profit commensurate with the risk involved in the venture. Hoover
b. The present value of a property is the amount that, if invested now in
its purchase, would find its repayment with commensurate profit in the
estimated series of annual dividends. Actuarially, it is the discounted
sum of each and all those dividends, after allowance for any estimated
further capital expenditure on necessary works and equipment.
Truscott
For mine timbers that are exposed to severe conditions of damp,
ventilation, and stress, any of several chemicals used to impregnate them
to resist dry or wet rot. These include copper sulfate, creosote, salt,
sodium fluoride and silicofluoride, and zinc as chloride or sulfate.
Pryor, 3
a. A smooth blasting method in which cracks for the final contour are
created by blasting prior to the drilling of the rest of the holes for the
blast pattern. Once the crack is made, it screens off the surroundings to
some extent from ground vibrations in the main round. Langefors
b. See:controlled blasting
See:filter cloth