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بليزززبحث عن Column Flotation

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    انيس فقيها
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    جديد

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    بليزززبحث عن Column Flotation

    السلام عليكم أخوتي الأعزاء:
    أحتاج اي معلومات أو بحوث عن Column flotation
    مع جزيل الشكر.

    من مواضيع انيس فقيها :


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  2. [2]
    هانى شرف الدين
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    عضو شرف


    تاريخ التسجيل: Nov 2005
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    وسام الشكر

     وسام كبار الشخصيات

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    مرحبا بك معنا

    هذا البحث قد يفيدك

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    الملفات المرفقة

  3. [3]
    alshangiti
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    مشرف وإستشاري هندسة المناجم


    الصورة الرمزية alshangiti


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    Separation by flotation


    Flotation is a mineral separation process, which takes place in a water-mineral slurry. The surfaces of selected minerals are made hydrophobic (water-repellent) by conditioning with selective reagents.

    The hydrophobic particles become attached to air bubbles that are introduced into the pulp and are carried to a froth layer above the slurry thereby being separated from the hydrophilic (wetted) particles.

    In addition to the reagents added, the flotation process depends on two main parameters.
    • Retention time needed for the separation process to occur determines the volume and number of flotation cells required.
    • Agitation and aeration needed for optimum flotation conditions, determine the type of flotation mechanism and the power input required.

    Size of cells – lengths of banks

    As flotation is based on retention time we have two alternative approaches:
    • Small cells and longer banks
    • Fewer large cells and shorter banks
    The first alternative is a more conservative approach and is applicable to small and medium tonnage operations. Using more smaller cells in flotation means:
    • Reduced short circuiting
    • Better metallurgical control
    • Higher recovery
    The second alternative is becoming more accepted for high tonnage operations using large unit volume flotation machines. Modern flotation equipment gives opportunities to use larger cells and shorter circuits.
    • Effective flow pattern minimizes shortcircuiting
    • Improved on line analyzers will maintain good metallurgical control
    • Less mechanical maintenance
    • Less energy input per volume pulp
    • Lower total cost
    Flotation circuit layout

    Flotation circuit designs vary in complexity depending primarily on the type of mineral, degree of liberation of valuable minerals, grade (purity) of the product and the value of the product.

    Typically the first rougher stage would comprise 10-40 % of the total rougher volume and will produce a good grade concentrate with but only medium recovery.

    The second rougher stage comprises 60-90 % of the total rougher volume and is designed to maximise recovery.

    The scavenger cells would have a cell volume equal to the total rougher stage and are included when particularly valuable minerals are being treated or a very high recovery is needed.

    Cleaner cells are used to maximise the grade of the final concentrate. Typical cleaner retention time is 65-75% of that for rougher flotation and will be at a lower percent solids. Less cells per bank than for rougher duties can be used.


    Flotation process.

    Reactor Cell Flotation System (RCS)

    The RCSTM (Reactor Cell System) flotation machine utilises the patent protected DVTM (Deep Vane) Mechanism. Flow pattern characteristics are:
    • Powerful radial slurry flow patterns to tank wall.
    • Primary return flow to underside of impeller.
    • Secondary top recirculation.
    Flotation enhanced due to:
    • Maximum particle-bubble contacts within the mechanism and tank.
    • Effective solids suspension during operation and re-suspension after shutdown.
    • Effective air dispersion throughout the complete cell volume.
    Features of the RCSTM (Reactor Cell System)
    • Active lower zone for optimum solid suspension and particle – bubble contact.
    • Upper zone with reduced turbulence to prevent particle – bubble separation.
    • Quiescent cell surface to minimise particle re-entrainment.
    • Circular tank with low level slurry entry and exit to minimise slurry short circuiting.
    • Automatic level control by dart valves.
    • Separate source of low pressure air.
    • Double internal cross-flow froth launders.
    • Application : The majority of mineral flotation duties.
    DR Flotation Cell System

    The Reactor Cell System Flotation Machine is the preferred choice for many mineral flotation applications. The DR design may be specified for certain applications, particularly where de-slimed coarse particles have to be handled such as in glass and potash processing.

    Flotation System DR - Design
    • Open flow tank with intermediate and discharge boxes
    • Near bottom located impeller/diffuser
    • Separate source of low pressure air
    • Level control by weir or dart valves (automatic as option)
    • Recirculation well
    • Reversible impeller direction of rotation
    Column Flotation Cell System

    Flotation column work on the same basic principle as mechanical machines such as RCSTM. However, in column flotation there is no mechanical mechanism. Separation takes place in a vessel of high aspect ratio and air is introduced into the slurry through spargers.


    Metso flotation columns.

    In certain cases such as cleaning duties or handling of very fine particles column flotation will offer the following advantages:
    Improved metallurgical performance
    • Low energy consumption
    • Less floor area
    • Less maintenance
    • Improved control
    Features of column flotation

    The CISA Sparger consists of inline Static Mixers and a Recycle Slurry Pump. Tailings Slurry is pumped from the base of the column through the static mixers where air and slurry are mixed together under high shear conditions to create the bubble dispersion.

    As the air/slurry mixture passes through the stationary blades located inside the mixer the air is sheared into very small bubbles by the intense agitation.

    The bubble suspension is introduced near the column base. Slurry Level Control is achieved by using Dp or ultrasonic sensors to automatically adjust the Tailings Control Valve. Wash Water addition improves grade by removing mechanically entrained particles.

    Applications for flotation columns
    • Copper
    • Graphite
    • Lead
    • Phosphate
    • Zinc
    • Coal
    • Iron
    • Fluorspar

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