An opaque variety of thompsonite from the Lake Superior region.
a. An automatic electronic device capable of accepting information,
applying prescribed processes to it, and supplying the results of these
processes. The term is generally used for any type of computer.
See also:analog computer
b. In seismic prospecting, one who with one or two assistants, carries on
the routine work of transforming the "wiggly lines" on the reflection
records into the form in which they are finally used. Where corrected
record sections are prepared, he or she must compute the corrections and
must assemble the other information to be fed into the playback so that it
will turn out properly corrected records. In addition to handling
corrections, the computer must mark the records, read and plot times, and
otherwise maintain the flow of data. Such individuals are not used in
processing modern digital seismic data. Dobrin
The process of controlling single or multiple mining machines in which
sensors and computers are used to replace or enhance manual control of all
or portions of the formerly manually controlled machine operations.
A mineral, (Mg,Cu,Zn)SO4 .5H2 O , containing 5.60% ZnO,
9.40% MgO, 9.00% CuO, and 39.07% H2 O ; from the Comstock Lode, NV.
Syn:zinc-magnesia chalcanthite
A tungsten carbide drill bit for percussive boring. The cutting edge is
concave, while in the conventional type the edge is convex. The new bit
remains sharper for a longer period before regrinding becomes necessary
and gives a higher penetration speed. Also called saddleback tip.
See also:plug bit
See:concave bit
A coalfield that is totally buried beneath newer deposits, usually Permian
and Trias strata, which repose unconformably on the coal measures in the
basin. A good example of a concealed coalfield is that of Kent, in
southeast England. See also:coal basin; exposed coalfield.
Nelson
The clean product recovered in froth flotation.
a. The heavy explosive charge loaded into the enlarged chamber at the
bottom of a quarry blasthole. See also:chambering
b. Means that the height of the charge is small compared with the burden
that can be given quantitatively. Langefors
See:concentrator
A device consisting of a riffled deck, usually inclined in two directions
to the horizontal, to which a differential reciprocating motion in a
substantially horizontal direction is imparted; the material to be
separated is fed in a stream of water, the heavy particles collect between
the riffles and are there conveyed in the direction of the reciprocating
motion while the lighter particles are borne by the current of water over
the riffles, to be discharged laterally from the table. BS, 5
a. The ratio of the dry weight of sediment to the weight of water sediment
mixture of which it is part. Sediment concentration is commonly expressed
in parts per million (ppm).
b. Separation and accumulation of economic minerals from gangue.
See also:ore dressing; preparation. Bateman, 2
An electrolytic cell, the electromotive force of which is due to
difference in concentration of the electrolyte or active metal at the
anode and the cathode. Osborne
The ratio between the density in a liquid of two minerals that are to be
separated (Mh and M1 being the heavy and light one,
respectively); C = Mh - 1/Ml , where water (sp gr, 1) is the
liquid. This ratio indicates the grain size above which separation by
gravity methods should be commercially practicable. Above 2.5 fine sands
(down to below 200 mesh) can be tabled. At 1.75 the lower limit is 100
mesh; at 1.5 about 10 mesh, and at 1.25 only gravel sizes can be treated.
Pryor, 1
Essentially, to secure the maximum output of coal from the minimum length
of face with due regard to safety and development. To measure the degree
of concentration at a colliery the following data are collected: (1) the
total length of coalface; (2) the total length of main haulage roads; and
(3) the total output. In general, the greater the dispersion of the
workings, the greater the manpower employed and the higher the costs of
production. See also:face concentration; geographical concentration;
overall concentration. Nelson
Weight or tonnage ratio (K) of the weight of feed (F) to the weight of
concentration (C) produced: K = F/C, for a two-product treatment.
Pryor, 3
A table on which a stream of finely-crushed ore and water flows downward;
the heavier metallic minerals lag behind and flow off in a separate
compartment. Weed, 2
a. A plant where ore is separated into values (concentrates) and rejects
(tails). An appliance in such a plant, e.g., flotation cell, jig,
electromagnet, shaking table. Also called mill; reduction works; cleaning
plant. Syn:concentrating plant
b. An apparatus in which, by the aid of water, air, and/or gravity,
mechanical concentration of ores is performed. A concentration plant.
Fay
c. A general term for a worker, who tends concentrating tables, vanners,
and other types of equipment used to separate valuable minerals from waste
material. DOT
See:parallel fold; similar fold.
See:portable concentric mine cable
Diamonds set in bit face in concentric circles so that a slight uncut
ridge of rock is left between stones set in adjacent circles.
CF:eccentric pattern