SPS Vibroscreens (Vibrating, Classifying and Clarifying Screens)

Vibroscreens are used either for wet solid-liquid separation or for dry solids classification

The Vibroscreen is a circular unitised gyratory screen. It is the largest of its type available today, with three-component multi-plane mechanical vibration. It handles wet & dry screening of particles ranging from 10mm down to 400 mesh in size. It gives very high capacity per sq.ft of screening area & consumes minimum energy. The motivation is through a motor with a double extended shaft, fitted at both ends with eccentric weights.

The whole base-unit drive assembly is mounted on a circular base with rugged springs which allows the unit to vibrate freely, and comprises carbon steel base and a motor table, support springs and spring mounts, top and bottom eccentric weights, a lead scale indicator, and a heavy duty motor for operation on 400-440V, 3-Phase 50 Hz power supply. The springs prevent transmitted vibration reaching the floor area on which the machine stands. The screen deck assemblies and spacing frames are mounted on top of the base unit and are connected together by stainless steel quick release circle clamps. Screen deck assemblies can be mounted one on top of the other within the vibroscreen assembly. The Vibroscreen is suitable for all types of screening operations within these four broad categories.

Dry Separation
This involves separation of different materials on the basis of their particle shape.

Dry Classification
This involves separation of solid particles into precise sized fractions.

Solid-Liquid-Separation
This involves dewatering of solids and clarification of liquids.

Solids Classification
This involves separation of solid-particles into sized fractions in a liquid medium.

TAKEN BELOW Highest screening efficiency is achieved by controlling the patterns of movement of solids on the screen surface. Control is achieved by varying the position of the bottom eccentric weight as shown in the diagram.

Operation

VIBROSCREEN OPERATION

The material is fed on to the centre of the top screen and the oversize material is moved by the multi-plane motion to the periphery of the screen to be discharged through a tangential outlet. The undersize particles and / or liquids pass through the screen to produce fine sized fractions or clarified liquid.

Top Eccentric Mass If the mass of the top eccentric is increased, this will increase the horizontal throw on the screen and will cause the oversize material to discharge at a fast rate.

Bottom Eccentric Mass An increase in the bottom eccentric mass will increase the vertical component of the motion. In the case where 'near size' blinding of the screen is a possibility, it is desirable to promote maximum vertical component of the motion in order to dislodge particles which may be held (pegged) in the interstices of the screen.

Bottom Eccentric Lead Angle

The tangential component of the motion imparted to the solid on the screen is controlled by the angular position of the top and bottom eccentric weights. The screening pattern can therefore be controlled by altering the angle of the eccentrics and some general examples of the type of control are shown in the diagram below.

Note : Ball tray with rubber balls are specified where there is a problem of near size blinding. The balls hold the screens open by their repeated impact on the underside of the screen. However, where blinding is caused by fibres stapling around the screen wires, cylindrical kleen rings of PVC/HDPE are used, operating with a close fit on the screen for effectively anti-blinding the screen by shearing the fibres and prevent a build-up.

Salient Features

High Capacity, Minimum Space

By varying the angular displacement of the bottom eccentric weight, the screening pattern can be optimised for each job, thus giving a high capacity per square foot of screen surface.

Adaptability

Discharge ports can be rotated to meet layout requirements and individual frames between screen decks can be tailored to suit the needs of that fraction.

No Transmitted Vibration

Motion is transmitted through the screening assembly and vibration is completely absent from the screen base. No special foundations are required and many screens are operating suspended from ceiling hangers. By the same token, the machine can be made portable and its operation is silent.

Long Screen Life

Pennwalt have developed a special screen holding device and a taut screen cloth is achieved on assembly. The cloth does not flex and moves rigidly with the screen assembly.

Minimum Screen Blinding

The vertical component of the vibration given by the bottom eccentric weight ensures that blinding of the screen by particles close in size to the screen cloth aperture is minimised. Ball trays / Kleen Rings can be added if necessary to alleviate screen blinding.

Low Operating Costs

The Vibroscreen uses only low power motors, since all their energy is used to create screen motion and none is wasted in vibrating a massive frame and foundation.

Applications

Large or small, wet or dry, there is a place for Vibroscreens in your industry. Detailed below are some of the uses that Vibroscreens have been put to. Pennwalt Vibroscreens are backed by a full technical advisory service to help solve separational problems in industry.

Applications in Process Industry
Abrasives Ceramic Powder Calcium Nitrate
ABS powder Crushed Bones Paints
Aluminium foil (granulated) Cellulose Powder Potassium Chlorate
Aluminium Powder Detergent Powder Sand
Aluminium Swarf / Coolant Dextrose Silicon Carbide
Ammonium Phosphate Insecticides Starch Slurry
Ammonium Nitrate Metal Powder Steel shots/grits
Baby Food Ossein Spices Turmeric Powder, Chilli powder, Coriander/Dry Ginger Powder
Calcined Petroleum Coke Polymer Resin/Pellets (nylon, PVC, LDPE, PP Polystyrene, Polyester) Sulphur Powder
Cattle Feed Pulp and Paper Mill Sugar Powder
Catalyst Pellets (a) Recovery of fibre Sodium Sulphate
Ceramics (b)Black Liquor STPP and Soda Ash
(a) Ceramic Slurry  (c) Milk of lime   Tea: (Black Tea)
(b) Glazed Slip (d) Starch/Talcum Slurry

Table Salt

Bentonite clay powder (e) Paper Coatings. Carbon Pellets.
Bauxite (f) White Water  
Carbon Activated Pentaerythritrol Polyethylene Pellets
Polystyrene Beads Graphite Powder Bauxite
Sodium bicarbonate Talcum Powder  
Resin (Ion Exchange) Sugar Mill
(a) Raw Juice
(b) Milk of lime
(c) Sugar Seeds
(d) Sugar
Borax (Anhydrous)
Vermiculite   Wood Charcoal


Applications in Food Industry
Screening of Ground Almonds. Screening of Coconut Shell Powder Screening of maida flour.
Screening of papaya cubes. Screening of Soya & maida flour, Dry potato powder. Screening of Starch powder.
Separation of waste threads, jute, coriander seeds etc. from Sugar granules. Screening of Turmeric pigment. Screening of Refined Table Salt.
Separation of solid fat from ghee. Clarification of Alkaline Extracts of Soya Flakes. Sorting of Orthodox Tea.
Screening of Castor Seed Extraction. Meat Meal. Biscuit Pieces.
Animal Blood (Removal of bone chips and contaminants).   Bone Meal.
  Coffee Powder. Copper Sulphate.
    Citrus Pulp / Juice
Citrus Skin / Oil and water emulsion   N.P.K. Fertilizer
Lactose   Milk Powder
Fish Press liquor Peas (frozen) Soya Flour
Chilly Powder Turmeric Powder  
Tobacco   Green Tea
Wheat Flour    
Clarification of bottle washing caustic solution (BREWERIES) Skim Milk powders Fish Meal


Applications in Chemical Industry
Classification of Anhydrous Aluminium Chloride. Classification of Polyester Beads.
Clarification of Sea Weed Extract. Degritting Milk of lime slurry.
Removal of metallic bits by screening Salicyclic Acid. Screening Hydrate Lime.
Screening of Acrylate Powder. Screening of Calcium Carbonate Powder.
Screening of Calcium carbide. Screening of Chalk Powder.
Screening of effluent overflow from Hydrocyclone. Screening of Gum Powder.


Miscellaneous Applications
Removal of broken pellets from pelletiser. Clarification of fermented Maize Slurry.
Clarification of steeping press liquor. Grading of dried yeast (Brewers).
Screening of Rice Straw. Screening of Crimson paint.
Screening of backwater from paper-mill. Screening of cottonstem chip.
Removal of coarse fibres from paper mill effluent. Screening of Refractory Grog.
Screening of coconut shell powder. Rubber particles.
Screening of Crushed Silica Sand. Screening of polyester chips to remove strands.Screening of Detergents

General Specifications


Model 'A' 'B' 'C' 'D' 'E' 'F' 'G' 'H' 'J' 'K' 'L' 'M'
'C/C'
'O' 'P' 'R'
24" 437 551 666 780 895 685 799 913 1028 114 355 451 622 152 400
30" 437 551 666 780 895 685 799 913 1028 114 355 559 762 152 490
38"  623 763 940 1112 1283 959 1131 1303 1474 182 439 639 973 203 608
48" 647 793 964 1136 1307 983 1155 1327 1498 209 463 820 1206 203 743
60"  647 857 1066 1276 1485 1098 1307 1517 1727 172 463 956 1524 203 914
72" 749 997 1244 1492 1740 1264 1511 1751 2006 190 460 1100 1803 203 1035
84"  749 1084 1368 1652 1936 1338 1592 1846 2190 269 460 1330 2078 203 1240