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Mining > Fire Assay and Metallurgy > Flashcards

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

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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

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3
Q

Fire assaying means

A

quantitative det of metals inores unsing heat and dry fluxes

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4
Q

How is Fire assay done

A

Sep metals from constituents and weighing in its pure form

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5
Q

Au and Ag is very soluble in

A

Molten metallic lead

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6
Q

Au and Ag is completely insoluble in

A

Slags of suitable composition

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7
Q

Difference of metal bearing alloy of lead and slag

A

Their SG

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8
Q

Used to completely remove precious metals from lead

A

Controlled oxidizing fusion involving differential filtration

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9
Q

Dilute nitric acid’s (HNO3) effect on Au and Ag

A

Au is completely insoluble in nitric acid

Ag is soluble

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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

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11
Q

What do Agents do

A

Dry subs for separation of metal from subs combined with it

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12
Q

Whys is Slag formation done

A

to form immiscible layers w/ diff SG to sep metals from assoc substances

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13
Q

What is Dore

A

Alloy of Gold and Silver, product of cupellation

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14
Q

5 Steps in Fire Assay

A
  1. Sampling
  2. Charging/Fluxing
  3. Fusion
  4. Cupellation
  5. Parting and Weighing
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15
Q

Purpose of using assay ton

A

basis for amount of ore in a charge

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16
Q

Why is charging/fluxing done

A

Ensure efficient slagging and separation

Assay crucible is used to contain it

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17
Q

Fusion procedure

A

Melt together of ore and fluxes at 1000 C for 40-50 mins

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18
Q

What is a Lead button

A

Lead with Au and Ag

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19
Q

What is Cupellation

A

Lead is separated from Dore by using cupel to absorb PbO

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20
Q

Composition of Cupel

A

Bone Ash, cement, and other refractory material

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21
Q

How is Ag and Au separated in “Parting”

A

Using Nitric acid (HNO3) to dissolve Ag and leave Au bead

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22
Q

What is “Inquartation”

A

add of known quantity of Ag to dore bead to ensure efficient parting

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23
Q

Griffith’s law says that…

A

NO Stress req for bond breakage, stress is req to prov energy to prod new surface.

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24
Q

What can close up cracks

A

Uniform compression loading

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25
Q

What propagates cracks

A

Tensile stress from differential stress

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26
Q

List all the gold projects

A

D iwata Gold project
A pex
M asbate Gold
N orth Davao Gold project

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27
Q

3 Benefits of Mineral Processing

A

F reight Savings
Improved Netal Purity
Reduced Treatment Charges

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28
Q

When is Batch grinding done

A

for lab scale or SSM

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29
Q

Differential Grinding means

A

Hard ores are ground finer than softer ones

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30
Q

Reduction ratio of 15-20:1

A

Ball mills

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31
Q

3 types of Rod Mills by discharge location

A

End Peripheral
Center Peripheral
Overflow

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32
Q

Kind of Ball Mill with a length much longer than its diameter

A

Tube Mills

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33
Q

2 Types of Ball mill accdg to Discharge

A

Grate Discharge Mill
Overflow
Discharge mill

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34
Q

2 Types of Ball Mills (Ball)

A

Standard steel ball mill

Pebble Mill

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35
Q

Ball Mills are often operatedin what circuit

A

Closed to minimize over-grinding

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36
Q

Reduction ratio of AG/SAG mills

A

250ish

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37
Q

AG/SAG mills with L:D of 1:3

A

Cascade mills

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38
Q

Whys is AG/SAG product good for flotation

A

Smooth surface means the reagents and bubbles can adsorb easier

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39
Q

What is used to determine capacities of equipt

A

Bulk Density

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40
Q

Advantage of Overhead eccentric

A

Uses less space

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41
Q

Dirr of Gape and Length

A

Gape is the dist bet the jaws, while length is width of jaw

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42
Q

Largest rock is what % of the gape

A

80%

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43
Q

Operation time limit for a jaw crusher

A

18 hrs/ day

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44
Q

Throw for coarse materials and for hard, brittle rocks

A

Longer for coarse, shorter for brittle

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45
Q

Capacity is measured where? Discharge capacity?

A

Max opening of swing jaw.

Closed side setting

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46
Q

Used to control feed volume of ROM of crusher

A

Surge Bins

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47
Q

Removes tramp metals from crusher

A

Magnetic separator

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48
Q

Particle size control for crusher

A

Grizzlies/Vibrating Screens

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49
Q

Regulates flow of ore to crusher

A

Feeder conveyor

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50
Q

Fixed Crushing surface in GC

A

Concaves

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51
Q

Movable Crushing surface of GC

A

Mantle

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52
Q

Vertical shaft that holds Mantle

A

Spindle

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53
Q

Sweeps out conical path for spindle

A

Spider

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54
Q

Relation of crushing force and throw

A

Larger crushing force, Capacity decreases though

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55
Q

GC capacity is measured where

A

Discharge zone

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56
Q

Delivers ore to GC

A

Dump trucks or Apron fed

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57
Q

What does scalper do

A

Separate fines

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58
Q

Storage space underneath GC

A

Under-Crusher hopper

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59
Q

Which liner is replaced more frequently in GC

A

Mantle

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60
Q

What feed char is JC effective

A

Blocky ores

Muddy, sticky, and wet

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61
Q

Ore char for GC

A

Slabby
Slow-crushing
Hard, abrasive minerals

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62
Q

Larger operating cost bet crushers

A

JC but higher capital cost

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63
Q

Taggart Crusher Selection Criteria

A

If Mt/hr < 161.7 x (gape in meters)^2 use JC

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64
Q

Maximum 2ndary Crusher feed size

A

15 cm

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65
Q

Spindle placement of CC and GC

A

Non-Suspended for Cone

Suspended for GC

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66
Q

UG drilling hole diameter

A

1-4 in

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67
Q

Surface drilling hole diameter

A

6- 18 in

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68
Q

Crushing action for CC and GC

A

Impact for CC

Slow Compression for GC

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69
Q

Feed method for CC

A

Non-choking

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70
Q

Difference of Standard and Shorthead per feed size

A

Standard - coarser

Short-head finer

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71
Q

Char of Short head CC per liner, slope of head, length of parallel sxn

A

Liner - Smooth
Slope - Steep
Length - Longer ii sxn

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72
Q

Gyradisc Crusher per deg of crushing, Crushing method, Liner angle

A

3rd Degree
Inter-particle
Flat angle liner

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73
Q

Gyrasphere Crusher per shape of crushing head and spring placement

A

Spherical crushing head

74
Q

Why are roll crushers not used in operations

A

BC low feed rate due to preponderance for choking (Starvation-fed)

75
Q

When are Toothed/Slugger Roll Crusher used

A

Softer, sticky materials

Larger Rr reqt

76
Q

Crushing action of Toothed/Slugger Roll Crusher

A

Compression and ripping

77
Q

What mat’l chars. are Hammer mill used for

A

mat’l wc behave plastically on slow-compression

78
Q

Hammer mills use this to transfer kinetic energy to particles

79
Q

When are Impactors useful

A

Coarser crushing

80
Q

Tidco Barmac crushing mechanisms

A

Impact
High intensity grinding
Multi-particle pulverizing

81
Q

Used for crushing coal

A

Coal breakers (cylindrical trommel like)

82
Q

“Mechanized Mortar and Pestle used in the olden days

A

Stamp mills

83
Q

How does a Sieve bend work

A

Slurry moves tangentially to curved screen

84
Q

Hukki Screen works by

A
  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
Q

How does Reciprocating Screen work

A

Horizontal gyratory motion stratifies and spreads material

86
Q

How many products does a Gyratory screen outputs

A

4 (OS, 1st Grade fraction, 2nd grade fraction, Fines)

87
Q

How does Morgensen Screen work

A

Multiple inclined screens with reduc

88
Q

For removing wood chips and carbon from slurries

A

Delkor Linear Screen

89
Q

Delkor Linear screen uses what for filtration

A

Multi-filament screen cloth on rollers

90
Q

Classification separates based on these char

A
  1. Particle size
  2. SG
  3. Geometry
91
Q

Define Viscous resistance

A

shear forces bet medium and mineral surface

92
Q

Define Turbulent Resistance

A

due to displacement of fluid by mineral (eddy currents)

93
Q

When does Free settling happens

A

Large volume of medium rel to particles (<15% solids)

94
Q

Newton’s law is used for what sizes

A

d <= 50 microns

95
Q

Stoke’s law size range

96
Q

2 minerals w/ same SG (falling velocity)

A

larger diameter, higher the velocity

97
Q

2 minerals w/ same diameter

A

higher SG, higher velocity

98
Q

Free settling ratio

A

da/db = ((Db-Df)/(Da-Df))^n

n = 0.5 for stokes
n = 1.0 for Newton's law
99
Q

Hindered settling condition

A

When pulp density is >15%

100
Q

Hindered settling velocity formula

A

v = ksqrt(d(Ds-Dp))

101
Q

Term for finers particles carried away by current

A

Scouring action

102
Q

What does Teeter Condition mean?

A

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
Q

How can Teeter Condition be induced

A

By inc pulp density thru choke points or smaller passages

104
Q

In a Series sorting column w/c one has the fastest current, w/c has the largest vol

A

Fastest current 1st column

Largest vol last column

105
Q

How do Settling cones fxn

A

Product is allowed to settle with the heaviest particles passing thru bot
Water is fed up top to remove the fines

106
Q

What is the material in the overflow of a Rake or Spiral classifier

107
Q

Material in discharge of a Rake or Spiral classifier

108
Q

Diff of Rake and Spiral classifier

A

Rake uses a scrapers to drag material, spiral uses a screw

109
Q

Steep Spiral Classifier at steep slopes are used in what

A

Dewatering as well as classification

110
Q

3 Factors affecting HC performance

A
  1. Diameter of vortex finder
  2. Mechanism of feed (Char of feed mat’l)
  3. Spigot diameter (overflow)
111
Q

Coagulation means

A

altering stability of suspended colloidal solids (opposite charges attract) using London-Van der Waals forces

112
Q

Flocculation means

A

form’t of aggregates by polymeric molecules to form bridges by taking adv of oppositely charge particlesWh

113
Q

Which Coagulant pH have w/c charges

A

Acids +
Bases -
inorganic salts +-

114
Q

What is floc

A

mass of particles linked together by flocculants

115
Q

Explain the zones formed in thickener

A

Zone A - Clear solution
Zone B - Pulp of feed consistency
Zone C - Transition zone
Zone D - Pulp in compression

116
Q

Upwards flow rate of thickener

A

Pulp feed rate - Underflow discharge rate

117
Q

What are tray thickeners

A

Series of vertically mounted thickeners

118
Q

High Capacity thickeners use this to speed up process

A

Flocculants

119
Q

What is a Lamella Thickener

A

Thickener w/c uses nest of inclined plates to lower distance bu increase effective area

120
Q

Solid Bowl Scroll Centrifuge uses

A

horizontal Screw to separate liquid and solids

121
Q

Filter Medium fxb

A

Support for filter cake

Initial layers of cake is the true filter

122
Q

How does Leaf filters work

A

Perforated metal framework is connected to a vacuum, this leaf will be the site cake deposition

123
Q

How does Rotary Drum filter work

A

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
Q

How does Disc filter work

A

Same as Drum but saves floor area

125
Q

Horizontal belt filter works by

A

Slurry on a conveyor passing thru filter and washed several times to ensure collection

126
Q

Tube press works by

A

Inflatable bladder presses slurry towards central cylindrical pump

127
Q

Concentration Criterion

A

(Dheavy - Dfluid)/(Dlight - Dfluid)

Ease of Gravcon is high if >= 2.5

128
Q

What is the dominant force acting on fine particles

A

Surface friction

129
Q

Elutriation is the

A

use of water pressure from the bot to separate particles by their SG and size

130
Q

What is a Warman Cyclosizer

A

Combination of Hydrocyclone and elutriation to hasten separation of particles

131
Q

How does Jigging work

A

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
Q

Hutch water means

A

Constant upward vol of water to prevent compaction of bed

133
Q

How do Pinched sluices and troughs

A

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
Q

Reichert cone fxn by

A

Feed enters around the cone

Heavies drop thru annular slot

135
Q

Humphrey Spirals are used for

A

Heavy mineral sands mostly

136
Q

Humphrey Spiral uses wash water to

A

carry low density particles towards outer radius

137
Q

In Shaking table, flowing flowing film affects what (SG or Size) more

A

Larger particles

Momentum acts on high SG more than size

138
Q

Rutile is extracted for what

A

Titanium (TiO2)

139
Q

Ilmenite formula

140
Q

Lithare (PbO) use and pH

A

Provide lead to collect metals

Strong basic flux

141
Q

Use of Na2O or Soda ash

A

Powerful basic flux

Comb. with silicates to form slag

142
Q

Use of Borax (Na2Ba4O7)

A

Acidic flux that lowers fusing point of slag

143
Q

Use of Silica

A

Acidic flux. Prevent attack from fire assay crucible when caused by deficiency in silica

144
Q

Use of Flour

A

Source of carbon

Reduction agent for litharge to lead

145
Q

Nitre descrp and use

A

Powerful oxidizing agent

Used for sulfide ore

146
Q

Particle size of ore used in fire assay

A
  • 100 mesh or 149 microns
147
Q

Concentration of Nitric acid

A

25% wrt to water

148
Q

What is Chiddy assay

A

To det Au in cyanide soln
Au is ppted with lead
then Cuppelled

149
Q

Scorification process

A

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
Q

Cupellation temp

A

850-1000 C

151
Q

“Freezing” in fire assay

A

form’t of thick concentric rings of PbO
Problem bc it stops oxidation in cupellation
Speiss forms

152
Q

3 Stages of Fusion

A

1st - preliminary heating
2nd - melting/chem rxns
3rd - quiet fusion/settling of immiscible layers

153
Q

Annealing in fire assay entails:

A

Hammer the Dore flat while heating in flame

25% HNO3 at 1:1 ratio by vol for parting

154
Q

Shallow, circular fire clay dish

155
Q

What causes a viscous and stringy slag

A

Too acidic slag

156
Q

Causes lumpy slag

A

too basic slag

157
Q

Causes Unreacted reagents

A

Improper fluxing

lack of time and heat

158
Q

Caused by low temp at 3rd stage of fusion

A

Improper slag/button sep

159
Q

Too much or littel Pb button

A

improper amts of OA or RA

160
Q

Cause of Non-homogenous slag

A

improper fluxing

161
Q

Problem with Matte and Speiss

A

may carry Au and Ag

162
Q

Corroded Crucibles cause

A

Silica in crucible reacts with fluxes

163
Q

Prevents charge sticking to crucible

164
Q

Color of the furnace for proper fusion

165
Q

Signifies Pb oxidation and absorption is proceeding efficiently

A

Dendritic PbO that volatilized away

166
Q

Signifies end of Cupellation

A

Wink

  • spark from the last Pb mol leaves the dore
  • w/c releases latent heat
167
Q

Litharge melting point

168
Q

Mercury vaporizing point

169
Q

What is Spelter

A

Impure Zinc

170
Q

Ratio of weight of sample and size of ore particle

A

Weight of sample prop to sq of diameter of largest particle

171
Q

Wt of 1st sample to total weight

172
Q

of lines of force passing thru a unit area

A

Magnetic flux density or

Magnetic Induction

173
Q

Force that induce lines of magnetization

A

Field Intensity

174
Q

Intensity of Magnetizatino

A

Response of a material to magnetization

175
Q

2 ways to remove entrained particale in Mag Sep

A

Alternating polarity of magnetization

Low freq vibration

176
Q

In Hight Tension sep, w/c stick anmd w/c is repelled

A

Stick - Insulators

Repelled - Conductors

177
Q

Bronze is an alloy of

A

Copper and Tin

178
Q

Brass is an alloy of

A

Copper and Zinc

179
Q

Crystal system of Martensite

180
Q

Austenite alloy comp

A

Iron
Nickel
Chromium

181
Q

Ferritic Stainless steel alloy

A

Iron and Chromium

Mining (14 decks)

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