Role of Physicochemical Aspects of Fibrous Particles in Suspension Rheology and Mineral Beneficiation

P. Patra

Columbia University,Cytec Industries.

Center for Particulate & Surfactant Systems (CPaSS)IAB Meeting

New York City, N.Y. August 2009

Goal-ObjectiveGoal-ObjectiveGoal Develop scientific understanding on rheology of concentrated

mineral suspension - - PParticles of varying physicochemical propertiesarticles of varying physicochemical properties

Objective Determine contributions of• Physical factors

Morphology, Rugosity, Particle size Entanglement of fibers – Network formation and hydrodynamics

• Chemical factors Strength of network:

• Electrostatic, chemical interaction and hydrophobic interaction

Impact

Paints PetroleumMineral

Processing

Cosmetics

Food IndustriesDesired properties of suspensions•Higher solids content, • Varying morphology

Coarse /Fibrous particles,

• Low yield stress and viscosity, • Static and dynamic stability.

http://www.fotosearch.com

http://readyfiber.com

Cement

http://www.fotosearch.comhttp://www.mine-engineer.com/www. petroleum-

industry.usca9425.htmlhttp://www.rexart.com/

Materials and MethodsSpiking Experiment:

Examine rheological property of the pulp

Fibrous particles

Flotation

Rheological characterization

Yield Stress

Grind

Coarse particles - Copper Ore Fibrous particles – High Fiber Ore (Fibrous minerals )

Fibrous particles – Nylon Fibers

Chemically Inert

Coarse particles

Ore mixture

Spiking Experiments: Copper Ore mixed with Fibrous Ore in varying amountsSpiking Experiments: Copper Ore mixed with Fibrous Ore in varying amounts

Rheological behavior is affected with fibrous minerals in the suspension

Video on Pulp Rheology

•Fibrous minerals form a strong network due to

• multiple contact among fibers - entanglement

• Network causes• the rheological properties• inferior dispersion of particle s and air bubbles

• reagents-mineral interactions• bubble-mineral interactions

Network Formation by Fibrous Particles in Suspension

SEM of pulp – Copper ore +Fibrous oreSEM of dry fibers in Fibrous ore

SEM of fibers (fibrous ore ), taken from suspension

Correlation of Rheological Properties to the Processing Efficiency

•Rheological properties of pulp is affected if it contains particles of fibrous morphology• Processing efficiency is significantly affected by the rheological properties of suspension• Reagents can negate the chemical factors contributing to rheology

Effect of Particle size (Aspect ratio [AR]) on Rheology of Suspension

Rheological properties of suspensions are significantly affected with particle size (fiber length)

Aspect ratio = .027

Aspect ratio = 0.0015

Video on Pulp Rheology

Summary and Conclusions•Rheological properties of suspension

Severely affected by Fibrous morphology – even at small concentrations of fibrous particles Dependent on

Length of the Fiber Diameter/thickness of the Fiber Strength of network formation by fibrous particles

• Processing efficiency can be improved Addition of chemical reagents

Can improve rheology of mineral suspension

Future plans• Additional physicochemical aspects to be studied

• Surface chemical properties• Rugosity of particles• Particle-particle and particle-reagent interactions• Rheological model to relate experimental results

•Conduct fundamental and applied studies•Conduct solution chemistry studies to determine species responsible for adverse affect on rheology and separation efficiency•Correlate rheological results to the selective separation of valuable minerals

AcknowledgementsCytec Industries,

Inc.Vale Inco