Sampling Flashcards

obtaining objective, reliable information on a population

a mechanical function and depends on:
• sampling method,
• site accessibility,
• geology,
• objectives of the project, and
• requirements for statistical analysis.

determined by the nature and geometry of mineralization (i.e.
size, shape, orientation, and distribution)

determined by the coefficient of variability (ratio of
std. dev to the mean) or in other words, the degree of
homogeneity/heterogeneity of mineralization

the taking of representative
fractions

processing of the samples
collected through reduction in size and quantity

sample analysis

Quick approximation
- Randomly picked

churn drill
suitable for soft and medium formation
- relatively short holes (10-50 m)

low cost, speed and mobility
soft and loose ground
inaccurate due to wall collapse & contamination

3 m with 10-15cm hole diameter

up to >30 m or more depending
on subsoil

Jackhammers, wagon drills
air-driven drills with depth of drilling limited to 6 m
for development of tunnels, advance mining faces and
breaking big boulders in road and other construction areas.

extensively used for mineral exploration, dam sites + other
foundation test works, mine development face, drainage of
mine workings, mine vent., oil structure investigations & oilgas wells

usually 10 feet (3.05 m) long through which water is
pumped to cool the bit + flush the rock cuttings

a cylindrical
hollow tube made of special alloys with a crown at one end

– (bentonite, barite)
prevents damage of drilling
tools, serves as lubricant

attached between the lower end of the drill rods
and the reamer shell. It holds the core inside while drilling and
brought to the surface.

best core recovery condition or non-coring bits in
blast hole drilling

average core recovery, where the inner and outer
tubes are connected and rotate simultaneously

complex core barrels and expensive type used in
broken, friable and sheared formations

saves considerable time and energy.

withdrawing the core and inner tube assembly (core barrel) from the hole without pulling out the hollow drill rods by a separate hoisting unit fixed at a different pulley.

refers to circulating air down to the bit head outside the drill rods and returning it up through inside the bit,
core barrel and drill rods.

- commonly used for open pit excavation of iron ore, bauxite,
limestone, rock phosphate, and coal seams.
- 10-15 cm large diameter vertical blast holes at high speed and
low cost

from diamond drills or from the casing drills

from air-flushed diamond, rotary, auger or
percussion drilling, and

or sludge from churn drills, diamond
drill, or wet rotary or percussion drilling

Usually in scanty outcrops
- Soil samples are collected on a relatively closely spaced
rectangular/square grid pattern at specified intervals

- for analyzing whether it would be useful in
the detection of concealed mineralization with a thin cover

Commonly during initial stage of surface geochemical
exploration
- Excavating 1x1 m2 pits in rectangular or square grid
patterns covering the entire target area w/ varying depths
depending on extent of weathering and nature of rocks

10m and 3-5m deep

Trenches are often cut across
the orebody after the
probable configuration of
mineralization is outlined
either by pitting or by
rock/soil sampling

center, then 4 more from
halfway to the corners

collection of representative
broken material generated by
pitting, trenching, mine
production etc.

few handheld spade or mechanized shovels full of
mineralized fragments and fines collected from the mine
face or stope draw points

Usually less-consolidated materials
(weathered) but stratified
- Scooping by hand spade or by auger
drills

For uniformly distributed mineralization (veins, stringers,
disseminations)
- cutting of channels across mineralized body in fresh surface
exposures/underground mine workings ( face, walls and
roof)

For hard, dense irregularly distributed/disseminated mineralization

- chipping off same-sized fragments of about 1x1 to 2x2 cm size covering the entire surface exposure, underground
mine face, wall and roof in a regular grid interval (25x25 cm)

Handful of the broken ore
material picked up randomly
every 5th/10th… moving car
transported by mine-car from
underground operations,
dumpers/trucks

Cross-Belt & Falling stream Sampling

normally of large volume (100 -1000
tonnes) representing all the distinctive
characteristics of the orebody

- From different parts of stockpile of trial
pit (surface), trial crosscuts
(underground) and ROM of regular
production

Coning & Quartering

Riffle Splitter

- Pitting, Trenching, Stack and Placer sampling

Diamond drill core, RC drill cuttings, Sludge, Channel and Chip sampling

Grab, Muck, Car, Bulk sampling

Chip or Grab Sampling

Chip + Channel Sampling

Chip sampling

Large number of chip samples

Bulk Sampling

Channel Sampling