Dewatering
Concentrates and tailings produced by the methods outlined above must be dewatered in order to convert the pulps to a transportable state. In addition, the water can be recycled into the existing water circuits of the processing plant, greatly reducing the demand for expensive fresh water.
Filtration is the separation of a suspension into a solid filter cake and a liquid filtrate by passing it through a permeable filtering material. Important factors in this process are the properties of the suspension (e.g., size distribution, concentration), the properties of the filtering materials (e.g., the width and shape of pores), and the forces applied to the suspension. Filtration is carried out in gravity filters (screens, dewatering bins), in centrifugal filters (screen centrifuges), in vacuum filters (drum
Exercise 46 Define whether sentences are true or false
1. The soluble constituent may be solid or hard ore. 2. Filtration is the separation of a suspension into a solid filter cake and a liquid filtrate by passing it through a non- permeable filtering material. 3. The resulting solution is called the extract or sometimes the miscella. 4. Methods of mechanical separations fall into four general types. 5. Still tanks, deaerators, foam breakers are used to separate solid from gas 6. Settling tanks, liquid cyclones, centrifugal decanters are used to separate liquid from liquid 7. The separation usually involves selective dissolving, with or without diffusion. 8. The solvent is he liquid used to leach away the soluble material. 9. Concentrates and tailings produced by the methods outlined above must be dewatered in order to convert the pulps to a transportable state. 10. Filtration is carried out in gravity filters in centrifugal filters, in vacuum filters or in pressure filters
Exercise 47 Complete the table using the information from the text.
Exercise 48 Complete the diagrams. a) Classes of mechanical separation methods
b) Classes of leaching process
Exercise 49 Put these words in order to make sentences:
1. to the separation such/ a heterogeneous/ applicable/ mixture/ Obviously/ techniques/ are / only/ of phases in/. 2. are /Both /extraction/and solvent /often /extraction /called /leaching 3. make/ Such devices/ containing to/ 8 to 15 percent /moisture/ produce/ it cakes/ possible/ filter. 4. called/ solution /The resulting /is /or sometimes/ the extract/ the miscella 5. used to /The liquid /leach away/ is termed/ the soluble material /the solvent. 6. solid/ constituent/ The soluble /or liquid / may be 7. have been /variety/ and devised /A wide / of separation /devices/ are in use/ 8. of a soluble fraction/ The removal/ a solution/ in the form of/ from an insoluble, with it /which/ permeable solid/ is associated 9. fractions/ homogeneous/ may be /The separated /or heterogeneous 10. four/ of mechanical /separations/ general classes / Methods /fall into.
Exercise 50 Explain the following terms:
The miscella ________________________________________________________ ___________________________________________________________________ The solvent__________________________________________________________ ___________________________________________________________________ Infusion ____________________________________________________________ ___________________________________________________________________ Density ____________________________________________________________ ___________________________________________________________________ Diffusion___________________________________________________________ ___________________________________________________________________ 7 MINERAL PROCESSING EQUIPMENT
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