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Comminution

The process of comminution is the crushing and grinding of a material / ore to reduce it to smaller or finer particles. The comminution process reduces particle sizes by breaking, crushing, or grinding of ore, rock, coal, or other materials.

The process is most often used in the field of mining and / or mineral processing, where mineral ore is broken down into small particles, by hammer, roller / vibrating disc mills and jaw, gyratory and cone crushers.

Comminution is a critical component of many mineral processing flowsheets when separating the precious metals from waste rock, before it goes onto further mineral processing.

Benefits of effective comminution:

  • Reduces energy consumption
  • Saves costs of chemical processing
  • Improves speed of mineral processing

Get to know more about comminution in the mineral processing industry below.

What is the purpose of comminution?

The main purpose behind comminution is to make the removal of minerals / materials from the ore or waste materials easier, as the particles are smaller and thus more exposed for further treatment.

Main objectives of comminution:

  • Increase surface area (increase the rate of reaction in further separation processes)
  • Break a material into very small particles (separate the valuable ore from waste material)
  • Achieve intimate mixing
  • Dispose solid wastes more easily
  • Improve the handling characteristics of the material

Comminution in mineral processing

Comminution in the mineral processing industry is a physical pre-treatment method that involves ore milling, grinding and breaking.

These mechanical methods increase the accessible surface area of the ore and its precious metals / materials through particle size reduction and size distribution.

This is a crucial part of most mineral processing flowsheets and serves several purposes, including:

– Separation: Increasing available surface area for chemical reactions
– Liberation: Liberating valuable minerals that are within waste ore / rock
– Concentration: Producing a particle size to meet product specifications

Additionally, during this process, the aim is to conserve mass, sort minerals by grades and collect the different minerals in their specific concentrations.

Comminution is essential to mineral beneficiation when forming mineral components into elements that use the least energy consumption (including thermal, physical and chemical treatments).

Comminution techniques

There are various comminution methods for mineral processing. Crushing and grinding are common comminution processes, where the main aim is the liberation and reduction of the size of the ore.

Crushing techniques make use of cone, jaw or gyroscopic crushers, yet grinding techniques are more often performed by milling, such as SAG or ball milling.

Although there are various technologies being researched and developed at Multotec, to increase both cost effectiveness and reduce energy consumption, the main principles and mechanisms for comminution tend to remain the same.

 

Ensuring the ideal particle size

To get the ideal particle size, different types of crushers and mills are used. The chosen equipment is dependent on the material’s feed properties (ie. ore hardness) and application requirements (ie. throughput & maintenance).

For coarse feed materials, primary crushers are used:

– Jaw crusher (for 1m > P80 > 100 mm)

– Cone crusher (for P80 > 20 mm)

– Hammer crusher

For intermediate feed size ranges (100mm > P80 > 20mm):

– Autogenous (AG) mills

– Semi-autogenous (SAG) mills

For finer size ranges (20mm > P80 > 30 μm):

– Ball mills

– Vertical roller mills

– Hammer mills

– Roller press or high compression roller mills

– Vibration mills

– Jet mills

For yet finer grind sizes (sometimes referred to as "ultrafine grinding"), specialist mills are used.

 

Mill Linings

Comminution of ore becomes more effective with durable mill liners..

Get max. protection against wear & increase efficiency, reduce downtime & lower overall plant costs.

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Magnetic Separation

Ore sorting can be increased with magnetic separation.

Efficiently remove ferromagnetic and paramagnetic particles or tramp metal from dry solids or slurries.

Read more

Conveyor System Solutions

Conveyor systems solutions can help speed up ore sorting.

Reduce downtime, operating costs & wear, while increasing the lifespan of your loading points.

Read more

 

Mill Linings

Our mill linings are designed to increase efficiency, reduce downtime and lower the overall costs of your milling plant.

With a complete range of components, from centre cones to trunnion liners, we utilise leading engineering tools to customise liners to your requirements.

Our liners deliver:

  • Reduced weight for reduced wear on bearings & torque
  • Improved installation safety
  • Excellent sealing properties eliminates particle lock-up
  • Increased throughput (blinding of grate plates eliminated)
  • Reduced noise levels for improved working conditions
  • Real-time MultoScan condition monitoring to predict liner life & maintain efficiency

Ball mill grinding circuits are energy efficient and are often used in comminution mining.

Multotec is a leading specialist in rubber wear linings, offering full plant audits, installation and maintenance and condition monitoring services for your grinding mill liners.

SAG Mill Liners

Multotec SAG mill liners use rubber composite components to deliver superior impact and wear resistance in all semi-autogenous milling applications.

Benefits:

  • High impact resistance
  • High absorption of impact energy
  • Increased throughput from rubber grates
  • Minimal blinding of the apertures
  • MultoMet & HD MultoMet liners available
  • Hardox® 500 (bendable & weldable abrasion-resistant steel)
  • HD MultoMet lifter bars enable optimum H2A

In applications that feature large ball and feed sizes, or with large mill diameters, we offer MultoMet™ or HD MultoMet™ SAG mill liners and heavy-duty grate plates.

Our SAG mill liners are custom designed to your application requirements.

Magnetic Separation

Multotec offers a complete range of magnetic separation equipment, ideal for separating ferromagnetic and paramagnetic particles from dry solids or slurries, as well as removing tramp metal.

We customise magnetic separation solutions for your process to improve your downstream processing efficiency while lowering your overall costs of production.

  • Recover up to 99.99% of medium
  • Recover fine particles down to 15 micron
  • Get flexible magnetic recovery options
  • Increase efficiency with oil-cooled electromagnets

Our Dry and Wet Drum Separators, WHIMS, Demagnetising Coils and Overbelt Magnets are in mineral processing plants across the world.

Energy efficient comminution or comminution circuit designs that bring energy savings.

 

Conveyor System Solutions

Multotec’s conveyor system solutions reduce downtime, belt slippage and wear.

Our conveyor belt system solution range works to increase the lifespan of your loading points by absorbing the energy of ore transfer and providing superior wear resistance with our range of Multolag™ ceramic products.

Features:

  • Reduced wear with low friction
  • Increased plant availability
  • Reduced downtime & operating costs
  • Easy-to-maintain belt tracking
  • Reduced overheads with increased product wear life

Frequently Asked Questions

What does Comminution mean?

Comminution is the reduction of solid materials from a larger to a smaller average size of particles, through crushing, grinding, cutting, breaking, vibrating or other processes.

What are the mechanisms of size reduction?

Mechanical comminution methods of particle size reduction include:

  • Impact  - using a single rigid force (like a hammer)
  • Compression - using two rigid forces (much like nutcracker) to disintegrate the particles
  • Shear  - the particles are compressed between the edges of two, moving and hard surfaces

Why is size reduction important?

Size reduction is important as it helps mineral processing methods with easier handling, an increased surface area per unit volume, as well as the separation of entrapped components.

What are the size reduction laws?

There are three physical laws that describe the energy needed for size reduction.

These include:

  • Bon’s Law
  • Rittinger’s Law
  • Kick’s Law

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