The so-called transition group of the British Coal Measures, between the
Middle and Upper Coal Measures in the Carboniferous System. They include
the Newcastle-under-Lyme Group and the Etruria Marl, and the Blackband
Group in north Staffordshire, England. CTD
A material made by sintering together lumps of limestone and certain kinds
of iron oxide, such as iron ore or mill scale, at a temperature of 1,450
degrees C in a rotary furnace. Though fusion does not occur, the iron
oxide rapidly penetrates the limestone completely and forms dicalcium
ferrite. Osborne
a. A landing, such as in a shaft mine.
b. A platform on which mine cars stand.
c. A step in a process.
d. A time-stratigraphic unit next in rank below a series and corresponding
to an age; it generally consists of several biostratigraphic zones. It is
the most important unit for long-range correlation.
In flotation, this refers to deliberate use of insufficient reagent in the
early part of the treatment to increase selectivity of conditioning,
followed by further addition at a later point in the process.
Pryor, 4
A method of crushing in which there is a series of crushers, each one
crushing finer than the one preceding.
Comminution in successive stages. Pryor, 4
See:feeder conveyor
A precise method of orienting underground workings in which plumblines are
transferred down a deep shaft in stages of 400 to 600 ft (120 to 185 m).
While shaft sinking is in progress, the lines can also be employed to
orient the shaft itself and to keep it plumb. BS, 7
Draining a mine by means of two or more pumps placed at different levels,
each of which raises the water to the next pump above or to the surface.
In mineral processing, development of the desired condition of the
particles by defined states, such as comminution to successively fine
sizes (possibly coupled with staged concentration or gangue elimination)
between such stages of communition. Pryor, 3
Winding, usually in compound shafts, where the wind is divided into two or
more stages, and underground winding engines are installed to deal with
the lower stages. Sinclair, 5
A system of working minerals by removing the strata above the beds, after
which the various beds are removed in steps or stages.
When shot firing in thick coal seams, two rows of holes may be necessary.
These are usually staggered to a triangular pattern to distribute the
burden. A similar pattern is often adopted in quarry wellhole blasting.
Nelson
To arrange boreholes in a row, in such a manner that those in one row are
placed opposite the spaces between the boreholes in the next row.
Long
Usually a short hole drilled, charged, and fired to shatter the rock near
the collars of the cut holes. Nelson
a. A temporary flooring or scaffold, or platform. Zern
b. One or more working platforms, fixed at defined levels in deep trenches
or similar excavations, on to which excavated earth is thrown by shovel.
Hammond
A gemstone with color altered by a coloring agent, such as a dye, or by
impregnation with a substance, such as sugar, followed by chemical or heat
treatment, which usually produces a permanent color; e.g., green
chalcedony. CF:burnt stone
See:heterogenite
Iron-base alloy containing enough chromium to confer a superior corrosion
resistance. ASM, 1; Newton, 1; CTD; Camp
Inclusions and intergrowths in mica arising from foreign materials,
resulting in a partial or total loss of transparency. Skow