Mineral Processing: LIBERATION Flashcards
1
Q
- an inorganically formed, naturally
occurring homogenous solid having a
definite chemical composition and an
orderly crystal structure.
A
Minerals
2
Q
- is a mineral deposit w/c can be
ECONOMICALLY EXPLOITED to become a
source or supply of a particular material
A
Ore
3
Q
all minerals having NO
ECONOMIC VALUE
A
Gangue
4
Q
also known as Mineral Dressing, Ore Dressing, Mineral
Beneficiation, Milling
A
Mineral Processing
5
Q
- Mechanical Separation of valuable
minerals from valueless minerals
A
Mineral Processing
6
Q
“de-stresses” the transition between the
mineral source, to the final metal product
A
Mineral Processing
7
Q
- To bring valuable mineral or the
final product into suitable
technical condition as required
by the process - Undesired constituents of the
original ore must be removed or
reduced below the specified
units
A
TECHNICAL
8
Q
- To provide the cheapest way to
eliminate the unwanted
minerals - Reduce unit material handling
costs
A
ECONOMIC
9
Q
- Concentration of desired mineral =
A
Freight Savings
10
Q
Waste Rock Minimization =
A
Improved
Metal Purity!
11
Q
Effective Material Reduction =
A
Reduced
Treatment Charges!
12
Q
- particle size reduction by breaking,
crushing, or grinding of ore, rock, coal, or
other materials - It is a critical component in most mineral
processing flowsheets and can serve
several purposes - Goals: LIBERATION and SEPARATION
A
COMMUNITION
13
Q
- Segregation of Materials into products
characterized by difference in size - Screening and Classification
A
SIZING
14
Q
- Separation of valuable minerals
- Based on the physical characteristics of
minerals
A
CONCENTRATION
15
Q
- Solid/liquid separation by thickeners and filters
A
DEWATERING
16
Q
- Bins, conveyors, feeders, pumps, etc.
A
AUXILIARY OPERATIONS
17
Q
- output is the mineral form of the valuable
minerals and its liberation size - identification of the mineral form by
comparison with known samples of
minerals and linear testing under the
microscope
A
ORE MICROSCOPY
18
Q
- A beam of electrons is focused on to a
point on the surface of the sample - The elements being detected both
qualitatively and quantitatively by their
resulting x-ray spectra
A
ELECTRON PROBE ANALYSIS
19
Q
- Measure the average spacing between
layers or rows of atoms - Determine the orientation of a single
crystal or grain - Find the crystal structure of an unknown
material - Measure the size, shape and internal
stress of small crystalline regions
A
XRD
20
Q
- Mineral Dressing consists of two steps:
A
LIBERATION AND SEPARATION
21
Q
impracticable if the 1st step
has not been successfully accomplished!
A
SEPARATION
22
Q
The essential prerequisite for the
separation of an ore into valuable and waste
fractions
A
LIBERATION
23
Q
Incomplete liberation limits either ____________
A
GRADE OR RECOVERY
24
Q
Uncrushed rock
A
Grains, Grain size
25
# **
Crushed rock
Particles, Particle size
26
Particles can consist of a single mineral;
FREE PARTICLES
27
When a particle consists of 2 or more
minerals, this is called
LOCKED PARTCLES
28
The percentage of a mineral or phase
occurring as free particles
DEGREE OF LIBERATION
29
the percentage of minerals that exist as locked particles
DEGREE OF LOCKING
30
– Happens when the interface between
grainsis weak
– Fracture at the grain boundaries; liberation
at the mineral grain
INTERGRANULAR
30
* Multiple separating tests
*Microscope counting techniques
* Polarized light mineragraphy
QUANTIFYING F
31
– Fracture occur across the grain; occurs
when mineral has weak structure
– Most common liberation problem
TRANSGRANULAR
32
– Localized stresses (@ the surface)
–Occurs when insufficient energy is applied
to cause significant fracture of the particles
ABRASION
33
* Contains both valuable and gangue
minerals!
* A large proportion of the difficulties
experienced in mineral separation are
associated with the treatment of these
particles
MIDDLINGS
34
– Impact
– The applied energy is well in excess of
which is required for fracture
– Under these conditions, many parts of the
particle is overloaded
– Comparatively large number of particles
with a wide range of sizes
SHATTER
35
– Slow compression
– Occurs when energy applied is just
sufficient to load comparatively few regions
of the particles to the fracture point
– Only a few new particles produced
CLEAVAGE
36
# TYPES OF MIDDLINGS
further size reduction increase liberation
RECTILINEAR
37
# TYPES OF MIDDLINGS
further reduction will increase liberation but a significant part are still very hard to liberate
SHELL
38
# TYPES OF MIDDLINGS
difficult to liberate
VEIN
39
# TYPES OF MIDDLINGS
very fine reduction treatment
OCCLUSIONS
39
* Occurs by preferential fracturing
* No further liberation may be obtained by
additional comminution
* Possible if mineral has:
– Macrostructural weakness (coal beds)
– Microstructural weakness (schists)
– Microstructural differences in physical
properties of adjacent minerals (galena and
quartz)
LIBERATION BY DETACHMENT
39
* An empirical relationship between energy
consumed during size reduction has been
proposed by Hukki;
Energy-Size Reduction Relationship
39
* Concerned with the relationship between
energy input and the particle size made from
a given feed size
* Various theories were put forward; none
was individually satisfactory
COMMINUTION THEORY
40
considered to be proportional to one side of
that area; therefore, it is inversely
proportional to the square root of the
diameter
crack length in unit volume
41
# Applicability of **Energy Laws**
- For Crushing (>1cm)
KICK's
42
# Applicability of **Energy Laws**
-For Fine Grinding (10 - 1000μm) →
RITTINGER’s
42
# Applicability of **Energy Laws**
-For Rod Mill and Ball Mill grinding →
BOND's
43
# Applicability of **Energy Laws**
For ranges approaching grinding limit →
No practical application!
43
* For crushing, it is often taken as the ratio of
the feed opening (gape) to the discharge
opening (set) of equipment
## Footnote
clue work: "ratio"
Reduction Ratio
