[MetE 127] LE 1

chungus life chungus life

False

True or False: Valuable minerals NEED to be 100% liberated for effective separation.

separation

The degree of liberation depends on the _____ technique employed.

Describe the general flowsheet for separation.

moderate; most

Roughing uses a _____ separating force to recover as of the liberated valuable mineral and remove _____ of the unwanted mineral.

strong; remaining; incompletely liberated

Scavenging uses a ____ separating force to recover as much as possible the _____ valuable minerals which are generally _____.

low; upgrade, removing

Cleaning uses a ____ separating force to ____ the rougher concentrated by _____ misplaced gangue minerals.

Characteristics of the ore, more specifically, of the minerals to be separated

Separation technique mainly depends on?

Optical response; hand sorting or automation that utilizes reflected light.

What is the (usual) operation employed and property utilized when the mineral characteristic is color and luster?

Difference in response to comminution; Air separation

What is the (usual) operation employed and property utilized when the mineral characteristic is texture and hardness?

Gamma Ray Emission; Automation triggered by scintillation counter

What is the (usual) operation employed and property utilized when the mineral characteristic is radioactivity?

Frictional force developed in stream flow; Flowing film table

What is the (usual) operation employed and property utilized when the mineral characteristic is shape?

Difference in buoyant effect; Gravity separation

What is the (usual) operation employed and property utilized when the mineral characteristic is specific gravity and mass?

Magnetism; Magnetic fields

What is the (usual) operation employed and property utilized when the mineral characteristic is specific ferromagnetism?

Mobility of electrons on particle surface; High voltage separator

What is the (usual) operation employed and property utilized when the mineral characteristic is surface conductivity?

Adsorption of specific cations and anions to modify surface tensions; Froth flotation, flocculation or agglomeration.

What is the (usual) operation employed and property utilized when the mineral characteristic is surface activity?

simplest; most economical

Gravity concentration is generally accepted as the ____ and ____ of all concentration methods.

significant

In using grav conc, difference in specific gravity should be ____

Difference in response to opposing forces of gravity and resistance by viscous media

How are mineral particles separated using gravity concentration?

Ease and efficiency is high when it is ≥ 2.5

What is the concentration criteria for gravity concentration?

decreases

Efficiency of gravity separation ____ in the finer particle sizes

1. Dense media separation

2. Separation in vertical currents

3. Separation in streaming currents

What are the categories of gravity concentration?

Particles are immerse in a bath of intermediate density where they are allowed to sink?

Explain dense media separation

Takes advantage of different settling rates

Explain separation in vertical currents

makes use of ‘flowing/thin film’

Explain separation in streaming current

How does elutriation work?

Separation of particles by stratification by pulsing action pf water (pulsion stroke then suction stroke)

How does jigging work?

relatively coarse particles w/ fairly closely-sized particles

In what situation is jigging usually utilized?

Heavy particles settle first as differential initial acceleration is only dependent on densities for shorter depths

Explain Differential Initial Acceleration (DIA)

Slurry is so viscous that only coarse particles can penetrate

Explain hindered settling

At the end of the stroke, when the bed contracts, the coarser particles interlock leaving interstitial spaces

Explain Consolidated Trickling

Remote locations where hauling equipment would be hard and where there is only limited amount of material present.

Where is panning most applicable?

How do t he rifles of a sluice help in gravity concentration?

Humphrey’s Spiral

Stratification by combined effects of centrifugal force, differential settling rates, interstitial trickling, and hindered settling.

Specific gravity

Steepness of the spiral affects cut-point in ____

concentration grade

Pulp density and particle size dictates ____

Allows for multi-layers of particles subjected to tabling

How do rifles increase capacity of shaking table?

Small;dense

____, ____ particles are not as affected by the flowing film (water flow) but affected by momentum of strokes (table motion).

Large, less dense

____, ____ particles are more affected by flowing film and less responsive to momentum of stroking.

• Can separate minerals that are near densities

• Easy to control

Advantages of dense media separation

• Highly dependent on particle size

• Expensive fluids/media

• Some fluids are toxic

Disadvantages of dense media separation

• fine, dense minerals

• easily removed from wanted mineral by washing

• no reaction w/ ore constituents

• resistant to corrosion

Characteristics of mineral for suspension use

Gravitational/Static Baths

Feed and medium are introduced, and the floating minerals are removed by paddles or by overflow

Centrifugal / Dynamic Vessels

Provides high centrifugal force and low viscosity of medium, finer seperations achieved

How does the cone separator work?

How does a drum separator work?

1st compartment has low SG medium to float lightest particles. 1st drum feeds the 2nd compartment. 2nd compartment has high SG medium to separate middlings from true heavies/sinks

How does a two-compartment drum separator work?

Used for cleaning coal

How does a Norwalt Washer work and what is it used for?

• Vorsyl Separator

• LARCODEMS

• Tri-flo separator

What are the 3 centrifugal vessels?

• De-sliming stage

• Reclaiming circuit for media recovery

• Densifiers

Elements of a dense media circuit

Floatation

is a physico-chemical-mechanico separation process that utilizes the difference in surface properties of the valuable minerals and the unwanted gangue

• Mineralogical Characteristics

• Chemical Variables

• Process Variables

Factors affecting circuit performance

Agitator

This promots collision of particles and bubbles which result in the attachment of particles to bubbles.

Froth

Collection of bubbles; governed by the

equation:

Frothing

maintenance of a body of bubbles at

and above the upper surface of the pulp

It changes the density of the mineral. It maintains a body of ore particles above the pulp long enough to permit separation.

Purpose of frothing

greater

The ____ the contact angle, the greater is the work of adhesion

increases

Hydrophobicity ____ with contact angle

Collectors

reagents which adsorb on mineral surfaces rendering them hydrophobic or aerophillic

Non-polar

minerals characterized by relatively weak molecular bonds. They are composed of covalent molecules held together by van der Waals forces.

Polar

minerals with strong covalent or ionic surface bonding are known as ____ types and are naturally hydrophillic

sulphide > sulphates > carbonates > halites > phosphates

Types of minerals frorm least to most polar

Frothers

added to stabilize bubble formation in the pulp phase

Alcohols (-OH)

most widely used frother as they have no collector properties

Regulators

modify the action of the collector

Activator

These reagents alter the chemical nature of the mineral surfaces so that they become hydrophobic due to the action of the collector

Depressant

Used to increase the selectivity of floatation by rendering some minerals hydrophillic

adsorption due to chemical reaction

Physical Adsorption

function of electrical behavior of ions

Xanthates

Applied for flotation of Sulfide minerals;No collector action for oxides

Dithiophosphates

Aerofloat; applied also to sulfide minerals

Carboxyl

Applied to alkali earth minerals

negative

In general, surfaces tend to attain (____) zeta potentials when base is added (OH-)

Positive

(____) zeta potential is attained with increasing acidity (H+)

Critical Micelle Concentration

When the concentration at the surface of the mineral has become equal to the bulk solution

1. Bubble-particle approach

2. Thinning of water film

3. Equilibrium contact

Stages of bubble particle contact

rupture

For bubble – particle attachment to occur: Disjoining pressure must be overcome prior to the ____ of the water film