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Teaching new employees about processing equipment

Teaching new employees about processing equipment. What it is and how it works. What are these?. Storage tanks, surge tanks, float cells, or leach tanks?. Some recent questions. How do you separate magnetite from beach sands? How does a dense media system work?

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Teaching new employees about processing equipment

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  1. Teaching new employees about processing equipment What it is and how it works

  2. What are these? Storage tanks, surge tanks, float cells, or leach tanks?

  3. Some recent questions • How do you separate magnetite from beach sands? • How does a dense media system work? • What are the key parameters to control in cyclone separation of solids, for a SAG mill discharge? • Can somebody give me a good orientation of how a cyclone separation works? • Does anyone have any experience in Magnetic separation in the aqueous phase?

  4. What it is and how it works • We use some large and unusual equipment. • Understanding it is important to good operations • How do you teach a new employee. • This presentation will be an introduction • in particular to gravity separating equipment.

  5. Jigs • Principles of particle motion under pulsed-flow hindered-settling conditions. • Separating mechanisms are: • hindered settling, • differential acceleration, • and consolidation trickling.

  6. Jigs • The particles became rearranged in layers of increasing density from bottom to top. • Jigging can be applied to a wide size-range of particles with top sizes up to 200 +mm.

  7. Jigs

  8. Dense Media Vessels • Feed is slurried in a medium with a specific gravity close to that of the desired separation. • The lighter fraction floats • and the heavier fraction sinks. • Heavy medium are suspensions of magnetite or ferrosilicon in water.

  9. Dense Media Vessels

  10. Dense Media Cyclone • Similar to a vessel, a slurry of ore and medium (magnetite or ferrosilicon dispersed in water) is admitted at a tangent to the cyclone. • The higher specific gravity moves along the wall of the cone and is discharged at the apex. • The lighter particles of lower specific gravity move toward the longitu­dinal axis of the cyclone and through the vortex finder.

  11. Dense Media Cyclone

  12. Tables • Separation is by flowing film. • The feed fans out over the table deck by: • differential motion • and gravitational flow • The particles become stratified in layers behind the riffles.

  13. Tables • This stratification is followed by the removal of successive layers from the top downward by cross-flowing water as the stratified bed travels toward the outer end of the table

  14. Tables

  15. Water-only Cyclone • Similar in operation to Dense Media cyclones, but with no media, using only water and inertia, because of the wide angle or angles in its conical bottom. • Predominately used in coal, and a few other applications.

  16. Water-only Cyclone

  17. Launders/Sluices • Launders/Sluices have been used for mineral processing almost as long as jigs (or perhaps longer). • They are simple to build and operate, but require a relatively large amount of space for processing anything more than a few pounds an hour of material.

  18. Launders/Sluices

  19. Spirals • Spirals are a more recent development than launderers and date from the mid 20th Century (CE). • While essentially a spiral launder the force on the particles from the centripatel action enhances separation.

  20. Spirals

  21. Centrifugal Concentrators • Particles >0.5 mm a water based gravity separation process is very efficient. • 0.5 mm to 0.1 mm efficiency drops off, but the devices can still be effective. • < 0.1 mm or with a small density difference, the speed with which the particles will move apart maybe less than the speed at which the water is flowing.

  22. Centrifugal Concentrators • One solution - increase the force on the particles by speeding up their movement. • Centrifugal concentrators can increase the force to 50 to 150 times • They can separate particles which previously where impossible to separate by other than flotation or chemical processes.

  23. Centrifugal Concentrators

  24. Flotation • Flotation - a physicochemical method. • It involves chemical treatment of a pulp to create conditions favorable for the attachment of particles to air bubbles. • Some particles are not readily wetted by water (hydrophobic), • While others are readily wetted by water (hydrophilic).

  25. Flotation • By the addition of chemicals these proper­ties can be enhanced. • Air bubbles are created by the agitator mechanism which draws air down the shaft. • The air bubbles carry the hydrophobic particles to the surface of the pulp • Form a froth which is skimmed off • The hydrophilic particles remain in the pulp.

  26. Flotation

  27. What are these? • Float Cells

  28. More Information • Agricola, Georgius. (1556). “De re metallica.” Translated 1950 translated by: H. C. Hoover, L.H. Hoover. Dover, NY. • Albrecht, M. C. (2013), “A Mining Engineers Notebook”, http://www.smatdogmining.com, 2013

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