Fire Assay and Metallurgy Flashcards
1
Q
General prod for ore High in Silicates and Carbonates
A
If high amts of silicates do not add silica or borax glass. bc molten Quartz is a strong acid
2
Q
If High in Sulfides, Carbonates and lead
A
Ground and roasted to remove sulfide fumes.
Low in lead add 12 g of litharge
3
Q
Fire assaying means
A
quantitative det of metals inores unsing heat and dry fluxes
4
Q
How is Fire assay done
A
Sep metals from constituents and weighing in its pure form
5
Q
Au and Ag is very soluble in
A
Molten metallic lead
6
Q
Au and Ag is completely insoluble in
A
Slags of suitable composition
7
Q
Difference of metal bearing alloy of lead and slag
A
Their SG
8
Q
Used to completely remove precious metals from lead
A
Controlled oxidizing fusion involving differential filtration
9
Q
Dilute nitric acid’s (HNO3) effect on Au and Ag
A
Au is completely insoluble in nitric acid
Ag is soluble
10
Q
What does a flux do
A
Converts compounds infusible a cert temp to another compound that melt at that particular temp.
Ex. Sodium carbonate lowers melting temp of quartz
11
Q
What do Agents do
A
Dry subs for separation of metal from subs combined with it
12
Q
Whys is Slag formation done
A
to form immiscible layers w/ diff SG to sep metals from assoc substances
13
Q
What is Dore
A
Alloy of Gold and Silver, product of cupellation
14
Q
5 Steps in Fire Assay
A
- Sampling
- Charging/Fluxing
- Fusion
- Cupellation
- Parting and Weighing
15
Q
Purpose of using assay ton
A
basis for amount of ore in a charge
16
Q
Why is charging/fluxing done
A
Ensure efficient slagging and separation
Assay crucible is used to contain it
17
Q
Fusion procedure
A
Melt together of ore and fluxes at 1000 C for 40-50 mins
18
Q
What is a Lead button
A
Lead with Au and Ag
19
Q
What is Cupellation
A
Lead is separated from Dore by using cupel to absorb PbO
20
Q
Composition of Cupel
A
Bone Ash, cement, and other refractory material
21
Q
How is Ag and Au separated in “Parting”
A
Using Nitric acid (HNO3) to dissolve Ag and leave Au bead
22
Q
What is “Inquartation”
A
add of known quantity of Ag to dore bead to ensure efficient parting
23
Q
Griffith’s law says that…
A
NO Stress req for bond breakage, stress is req to prov energy to prod new surface.
24
Q
What can close up cracks
A
Uniform compression loading
25
What propagates cracks
Tensile stress from differential stress
26
List all the gold projects
D iwata Gold project
A pex
M asbate Gold
N orth Davao Gold project
27
3 Benefits of Mineral Processing
F reight Savings
Improved Netal Purity
Reduced Treatment Charges
28
When is Batch grinding done
for lab scale or SSM
29
Differential Grinding means
Hard ores are ground finer than softer ones
30
Reduction ratio of 15-20:1
Ball mills
31
3 types of Rod Mills by discharge location
End Peripheral
Center Peripheral
Overflow
32
Kind of Ball Mill with a length much longer than its diameter
Tube Mills
33
2 Types of Ball mill accdg to Discharge
Grate Discharge Mill
Overflow
Discharge mill
34
2 Types of Ball Mills (Ball)
Standard steel ball mill
| Pebble Mill
35
Ball Mills are often operatedin what circuit
Closed to minimize over-grinding
36
Reduction ratio of AG/SAG mills
250ish
37
AG/SAG mills with L:D of 1:3
Cascade mills
38
Whys is AG/SAG product good for flotation
Smooth surface means the reagents and bubbles can adsorb easier
39
What is used to determine capacities of equipt
Bulk Density
40
Advantage of Overhead eccentric
Uses less space
41
Dirr of Gape and Length
Gape is the dist bet the jaws, while length is width of jaw
42
Largest rock is what % of the gape
80%
43
Operation time limit for a jaw crusher
18 hrs/ day
44
Throw for coarse materials and for hard, brittle rocks
Longer for coarse, shorter for brittle
45
Capacity is measured where? Discharge capacity?
Max opening of swing jaw.
| Closed side setting
46
Used to control feed volume of ROM of crusher
Surge Bins
47
Removes tramp metals from crusher
Magnetic separator
48
Particle size control for crusher
Grizzlies/Vibrating Screens
49
Regulates flow of ore to crusher
Feeder conveyor
50
Fixed Crushing surface in GC
Concaves
51
Movable Crushing surface of GC
Mantle
52
Vertical shaft that holds Mantle
Spindle
53
Sweeps out conical path for spindle
Spider
54
Relation of crushing force and throw
Larger crushing force, Capacity decreases though
55
GC capacity is measured where
Discharge zone
56
Delivers ore to GC
Dump trucks or Apron fed
57
What does scalper do
Separate fines
58
Storage space underneath GC
Under-Crusher hopper
59
Which liner is replaced more frequently in GC
Mantle
60
What feed char is JC effective
Blocky ores
| Muddy, sticky, and wet
61
Ore char for GC
Slabby
Slow-crushing
Hard, abrasive minerals
62
Larger operating cost bet crushers
JC but higher capital cost
63
Taggart Crusher Selection Criteria
If Mt/hr < 161.7 x (gape in meters)^2 use JC
64
Maximum 2ndary Crusher feed size
15 cm
65
Spindle placement of CC and GC
Non-Suspended for Cone
| Suspended for GC
66
UG drilling hole diameter
1-4 in
67
Surface drilling hole diameter
6- 18 in
68
Crushing action for CC and GC
Impact for CC
| Slow Compression for GC
69
Feed method for CC
Non-choking
70
Difference of Standard and Shorthead per feed size
Standard - coarser
| Short-head finer
71
Char of Short head CC per liner, slope of head, length of parallel sxn
Liner - Smooth
Slope - Steep
Length - Longer ii sxn
72
Gyradisc Crusher per deg of crushing, Crushing method, Liner angle
3rd Degree
Inter-particle
Flat angle liner
73
Gyrasphere Crusher per shape of crushing head and spring placement
Spherical crushing head
74
Why are roll crushers not used in operations
BC low feed rate due to preponderance for choking (Starvation-fed)
75
When are Toothed/Slugger Roll Crusher used
Softer, sticky materials
| Larger Rr reqt
76
Crushing action of Toothed/Slugger Roll Crusher
Compression and ripping
77
What mat'l chars. are Hammer mill used for
mat'l wc behave plastically on slow-compression
78
Hammer mills use this to transfer kinetic energy to particles
Beater
79
When are Impactors useful
Coarser crushing
80
Tidco Barmac crushing mechanisms
Impact
High intensity grinding
Multi-particle pulverizing
81
Used for crushing coal
Coal breakers (cylindrical trommel like)
82
"Mechanized Mortar and Pestle used in the olden days
Stamp mills
83
How does a Sieve bend work
Slurry moves tangentially to curved screen
84
Hukki Screen works by
1. Feed is fed up top, water jet from below
2. Mixture is slowly rotated on Cylindrical screen
3. Oversized passes thru bottom, undersized passes thru screen
85
How does Reciprocating Screen work
Horizontal gyratory motion stratifies and spreads material
86
How many products does a Gyratory screen outputs
4 (OS, 1st Grade fraction, 2nd grade fraction, Fines)
87
How does Morgensen Screen work
Multiple inclined screens with reduc
88
For removing wood chips and carbon from slurries
Delkor Linear Screen
89
Delkor Linear screen uses what for filtration
Multi-filament screen cloth on rollers
90
Classification separates based on these char
1. Particle size
2. SG
3. Geometry
91
Define Viscous resistance
shear forces bet medium and mineral surface
92
Define Turbulent Resistance
due to displacement of fluid by mineral (eddy currents)
93
When does Free settling happens
Large volume of medium rel to particles (<15% solids)
94
Newton's law is used for what sizes
d <= 50 microns
95
Stoke's law size range
d >= 5 mm
96
2 minerals w/ same SG (falling velocity)
larger diameter, higher the velocity
97
2 minerals w/ same diameter
higher SG, higher velocity
98
Free settling ratio
da/db = ((Db-Df)/(Da-Df))^n
```
n = 0.5 for stokes
n = 1.0 for Newton's law
```
99
Hindered settling condition
When pulp density is >15%
100
Hindered settling velocity formula
v = k*sqrt(d*(Ds-Dp))
101
Term for finers particles carried away by current
Scouring action
102
What does Teeter Condition mean?
when pulp density is high, each mineral is covered with thin film of water
Slurry acts as viscous fluid where only coarse particles can penetrate
103
How can Teeter Condition be induced
By inc pulp density thru choke points or smaller passages
104
In a Series sorting column w/c one has the fastest current, w/c has the largest vol
Fastest current 1st column
| Largest vol last column
105
How do Settling cones fxn
Product is allowed to settle with the heaviest particles passing thru bot
Water is fed up top to remove the fines
106
What is the material in the overflow of a Rake or Spiral classifier
Fines
107
Material in discharge of a Rake or Spiral classifier
Coarse
108
Diff of Rake and Spiral classifier
Rake uses a scrapers to drag material, spiral uses a screw
109
Steep Spiral Classifier at steep slopes are used in what
Dewatering as well as classification
110
3 Factors affecting HC performance
1. Diameter of vortex finder
2. Mechanism of feed (Char of feed mat'l)
3. Spigot diameter (overflow)
111
Coagulation means
altering stability of suspended colloidal solids (opposite charges attract) using London-Van der Waals forces
112
Flocculation means
form't of aggregates by polymeric molecules to form bridges by taking adv of oppositely charge particlesWh
113
Which Coagulant pH have w/c charges
Acids +
Bases -
inorganic salts +-
114
What is floc
mass of particles linked together by flocculants
115
Explain the zones formed in thickener
Zone A - Clear solution
Zone B - Pulp of feed consistency
Zone C - Transition zone
Zone D - Pulp in compression
116
Upwards flow rate of thickener
Pulp feed rate - Underflow discharge rate
117
What are tray thickeners
Series of vertically mounted thickeners
118
High Capacity thickeners use this to speed up process
Flocculants
119
What is a Lamella Thickener
Thickener w/c uses nest of inclined plates to lower distance bu increase effective area
120
Solid Bowl Scroll Centrifuge uses
horizontal Screw to separate liquid and solids
121
Filter Medium fxb
Support for filter cake
| Initial layers of cake is the true filter
122
How does Leaf filters work
Perforated metal framework is connected to a vacuum, this leaf will be the site cake deposition
123
How does Rotary Drum filter work
Horizontal drum part submerged in slurry is connected to a vacuum
Slurry is sprayed and cake is deposited due to vacuum suction
Rotation causes the cake to be scraped away
124
How does Disc filter work
Same as Drum but saves floor area
125
Horizontal belt filter works by
Slurry on a conveyor passing thru filter and washed several times to ensure collection
126
Tube press works by
Inflatable bladder presses slurry towards central cylindrical pump
127
Concentration Criterion
(Dheavy - Dfluid)/(Dlight - Dfluid)
Ease of Gravcon is high if >= 2.5
128
What is the dominant force acting on fine particles
Surface friction
129
Elutriation is the
use of water pressure from the bot to separate particles by their SG and size
130
What is a Warman Cyclosizer
Combination of Hydrocyclone and elutriation to hasten separation of particles
131
How does Jigging work
The water is lifted (pulsion) to loosen bed so heavier particles can settle thru interstices
The suction stroke presses the bed against the screen allowing more heavy fines to pass while tails overflow
132
Hutch water means
Constant upward vol of water to prevent compaction of bed
133
How do Pinched sluices and troughs
Pinched portion increases speed w/c affects the fines the most
Splitters sep fines and coarse, lights and heavies accdg to distance of throw
Pwede rin riffles ginamit
134
Reichert cone fxn by
Feed enters around the cone
| Heavies drop thru annular slot
135
Humphrey Spirals are used for
Heavy mineral sands mostly
136
Humphrey Spiral uses wash water to
carry low density particles towards outer radius
137
In Shaking table, flowing flowing film affects what (SG or Size) more
Larger particles
| Momentum acts on high SG more than size
138
Rutile is extracted for what
Titanium (TiO2)
139
Ilmenite formula
FeTiO3
140
Lithare (PbO) use and pH
Provide lead to collect metals
| Strong basic flux
141
Use of Na2O or Soda ash
Powerful basic flux
| Comb. with silicates to form slag
142
Use of Borax (Na2Ba4O7)
Acidic flux that lowers fusing point of slag
143
Use of Silica
Acidic flux. Prevent attack from fire assay crucible when caused by deficiency in silica
144
Use of Flour
Source of carbon
| Reduction agent for litharge to lead
145
Nitre descrp and use
Powerful oxidizing agent
| Used for sulfide ore
146
Particle size of ore used in fire assay
- 100 mesh or 149 microns
147
Concentration of Nitric acid
25% wrt to water
148
What is Chiddy assay
To det Au in cyanide soln
Au is ppted with lead
then Cuppelled
149
Scorification process
Au and Ag is dissolved w/ molten lead at high heat
Pb button and slag is formed
This is separated
Use for arsenic, bismuth, and antimony containing ores
150
Cupellation temp
850-1000 C
151
"Freezing" in fire assay
form't of thick concentric rings of PbO
Problem bc it stops oxidation in cupellation
Speiss forms
152
3 Stages of Fusion
1st - preliminary heating
2nd - melting/chem rxns
3rd - quiet fusion/settling of immiscible layers
153
Annealing in fire assay entails:
Hammer the Dore flat while heating in flame
| 25% HNO3 at 1:1 ratio by vol for parting
154
Shallow, circular fire clay dish
Scorifier
155
What causes a viscous and stringy slag
Too acidic slag
156
Causes lumpy slag
too basic slag
157
Causes Unreacted reagents
Improper fluxing
| lack of time and heat
158
Caused by low temp at 3rd stage of fusion
Improper slag/button sep
159
Too much or littel Pb button
improper amts of OA or RA
160
Cause of Non-homogenous slag
improper fluxing
161
Problem with Matte and Speiss
may carry Au and Ag
162
Corroded Crucibles cause
Silica in crucible reacts with fluxes
163
Prevents charge sticking to crucible
NaCl
164
Color of the furnace for proper fusion
dull red
165
Signifies Pb oxidation and absorption is proceeding efficiently
Dendritic PbO that volatilized away
166
Signifies end of Cupellation
Wink
- spark from the last Pb mol leaves the dore
- w/c releases latent heat
167
Litharge melting point
883 C
168
Mercury vaporizing point
369 C
169
What is Spelter
Impure Zinc
170
Ratio of weight of sample and size of ore particle
Weight of sample prop to sq of diameter of largest particle
171
Wt of 1st sample to total weight
5%-20%
172
of lines of force passing thru a unit area
Magnetic flux density or
| Magnetic Induction
173
Force that induce lines of magnetization
Field Intensity
174
Intensity of Magnetizatino
Response of a material to magnetization
175
2 ways to remove entrained particale in Mag Sep
Alternating polarity of magnetization
| Low freq vibration
176
In Hight Tension sep, w/c stick anmd w/c is repelled
Stick - Insulators
| Repelled - Conductors
177
Bronze is an alloy of
Copper and Tin
178
Brass is an alloy of
Copper and Zinc
179
Crystal system of Martensite
BCT
180
Austenite alloy comp
Iron
Nickel
Chromium
181
Ferritic Stainless steel alloy
Iron and Chromium
