coal Flashcards
(314 cards)
stage in coal production when the mined coal is processed into a range of clean,
graded, and uniform coal products that are suitable for the commercial market
Coal preparation
other term for Coal preparation
(beneficiation)
collected
from the coal streams to power plants on a regular basis not only for determination of
heat balance but also to document compliance with air pollution emission regulations
operating samples
coal handling system,
crushing is limited to a top size of
6 or 4 mm
devices most commonly used for
crushing are the
rotary breaker, the roll crusher, and the hammer mill.
e typical sizes of individual field samples vary from
3 to 15 kg.
he purest form of probability sampling and each member
of the population has an equal and known chance of being selected and bias is minimized
Random sampling
s often used instead of random sampling and, depending
on the material to be sampled, can be as good as the random sampling method
Systematic sampling
commonly used probability method that is superior to random
sampling because it reduces sampling error and is used to select a sufficient number of samples from, say, each level of the coal pile – sufficient refers to a sample
size large enough for us to be reasonably confident that the stratum represents the
population
Stratified sampling
typically used in exploratory research
where only an approximation of the data will suffice
convenience sampling
common
method of sampling and the sample is assumed to be repetitive without and foundation
for this belief and the confidence that the chosen sample is truly representative of the
coal pile is low
Judgment sampling
similar to stratified sampling and then convenience
sampling or judgment sampling is used to select the required number of samples
from each stratum.
Quota sampling
a method used when the desired sample
characteristic is rare and does introduce bias because the technique itself reduces the
likelihood that the sample will represent a good cross section from the population.
Snowball sampling
sample that represents a quantity, or lot, of coal and is
composed of a number of increments on which neither reduction nor division has been
performed
The recommended maximum quantity of coal to be represented by one gross sample is 10,000 tons
gross sample of coal
statistical term defined as the mean square
of errors;
Variance
square root of the variance is more generally known as the
standard
deviation or the standard error of sampling
function of the size of increments collected and the
number of increments included in a gross sample, improving as both are increased,
subject only to the constraint that increment size not be small enough to cause selective rejection of the largest particles present
precision of sampling
) For raw,
dirty, or poorly cleaned coal, the minimum number of increments is
35.
reserved for the collection
of sample increments from a free-falling stream of coal as opposed to the collection of increments from a motionless (stopped) conveyor belt
Stream sampling and flow sampling
only the coal near the top surface has the potential to be
included in the sample thereby violating the basic tenet of obtaining a representative
sample. increments must not be collected predominantly from
any given location relative to the dimensions of the rail car.
car-top sampling
consists of one or more pipes, arranged like the spokes of a
wheel. Openings located at the tips collect the sample as the device is rotated through
coal on a moving belt.
spoon sampler
used as a sampling device for penetrating a stationary
mass of coal and withdrawing material from its interior
auger drill
that includes all other coals, including
unknown coals
B
includes coals that have been cleaned in all sizes and allows smaller weight laboratory
samples to be retained
A