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Performance Characterization of New Frothers for Sulphide Mineral FlotationCape Town, 14th November 2017

D. ChipfunhuG. BournivalS. DickieS. Ata

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For flotation to take place, 3 individual consecutive sub-processes have to take place in collection zone:

1. Collision (Ec) – Bulk hydrodynamics and kinetics, frothers affect collisionefficiency (bubble size, bubble rise velocity, flotation rate)

2. Adhesion or Attachment (Ea) – thermodynamics, surface forces, collectorsaffect attachment efficiency. But frothers may affect induction time

3. Stability (Es) – hydrodynamics and thermodynamics, disruptive forces, particlesize and specific gravity

4. Froth recovery factor – froth stability

Frothers are critical for all the sub-processes and froth recovery

Frothers in flotation

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Frother characterization

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Performance characterization of frothers mainly:

Bubble size (CCC) and other hydrodynamic characteristics

Froth/Foam stability (foaminess)

Water carrying capacity

These do not correlate well with flotation performance

We propose to use further fundamental parameters to characterize frothers

Coalescence times

Damping of bubble surface oscillation after coalescence

Detachment of particles after coalescence and correlate to flotation performance

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Materials and Methods

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In this work we have evaluated frother performance through two phase systems:

Foaminess (dynamic foam stability) in foam column

Bubble size and critical coalescence concentrations

Coalescence times and damping constant

Three phase liquid-gas-solid system

Particle detachment after coalescence (two phase)

Flotation test work

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Materials and Methods

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Quartz and chalcopyrite mixture ~3% Cu used for flotation test work. Chalcopyrite was

aged in under room temperature for six months. Flotation carried out in Denver cell,

30% pulp density, pH 9 with no collector

Three frother formulations from BASF were compared against MIBC and TPM

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Foam column – Foam volume

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5ppm (●); 10ppm (■); 20ppm (♦); 50ppm

(▲); 100ppm (x).

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Foam column - Foaminess

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MIBC (♦), TPM (■), BASF’s frother 1 (▲), BASF’s frother 2 (●) and BASF’s frother 3 (x). A - 5ppm; B - 10ppm; C - 20ppm; D -50ppm and E - 100ppm

Σ = 𝐻𝐻𝑚𝑚𝑚𝑚𝑚𝑚𝐴𝐴𝑄𝑄

; Σ is foaminess, Hmax

is maximum equilibrium foam

height, A is foam column cross

sectional area and Q is the

volumetric air flow rate

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Flotation – Recovery Time Profiles

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BASF’s frothers give higher recovery compared to MIBC and TPM

BASF’s frothers provide better dose efficiency and recovery

MIBC (♦), TPM (■), BASF’s frother 1 (▲), BASF’s frother 2 (●) and BASF’s frother 3 (x).

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Flotation – Grade versus Recovery

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BASF’s frothers provide higher recovery and grade compared to MIBC for all frother concentrations investigated

MIBC (♦), TPM (■), BASF’s frother 1 (▲), BASF’s frother 2 (●) and BASF’s frother 3 (x).

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Coalescence times and damping constant

Increased bubble stability compared to MIBC and tripropyleneglycol methylether (TPM)

Improved bubble stability – lower oscillation than MIBC and TPM

MIBC (♦), TPM (■), BASF’s frother 1 (▲), BASF’s frother 2 (●) and BASF’s frother 3 (x).

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Particles detachment

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00,20,40,60,8

1

0 10 20 30Det

achm

ent (

1-R

)

Concentration of frother, ppm (v/v)

Less particles detach from the bubble after coalescence event for BASF frother 1, 2 and 3 compared to MIBC and tripropyleneglycol methylether (TPM)

Particles detachment decreases with increasing frother concentrations

MIBC (♦), TPM (■), BASF’s frother 1 (▲), BASF’s frother 2 (●) and BASF’s frother 3 (x).

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Conclusions

Two phase parameters such as foaminess and froth stability are poor predictors of flotation performance

We have formulated frothers that give improved flotation performance. BASF frother formulations produced improved flotation recovery and grade.

We have characterised our frothers and explained flotation recovery based on fundamental parameters of coalescence times, damping constant and particle detachment after coalescence

Empirical approach produced high performing frothers

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