Coarse Aggregate Scrubbing and Feed Preparation

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Lester Ward
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1 Coarse Aggregate Scrubbing and Feed Preparation AGG1 Nashville, TN By: Stephen Shortsleeve & Matthew Lear Feed Prep - Typical Equipment Wash Screens Rotary Scrubbers (+/- Trommel) Log Washers Aggregate Conditioners (Blade Mills) Coarse Material Screw Washers Attrition Cells High Pressure Washers 1

2 Plasticity of Clay 3/14/2016 Application High Log Washer Aggregate Conditioner Attrition Cell Med Coarse Material Screw Washer Rotary Scrubber High Pressure Washer Wash Screens Low Size, Inches Wash Screens Pre-wetting in a slurry box Use Lowest effective pressure for rinse/wash 3 10 USGPM/ STPH psi 4 2

3 Rotary Scrubbers 5 Purpose Why use a Rotary Scrubber / Trommel? Removal of light, loamy clays Removal of deleterious material Typical Feed size up to High Capacities Not typically recommended for tough, plastic clays by itself 3

4 ROTARY SCRUBBER PROCESS Feed should be pre-scalped to remove <3/8 material Feed & Water enter the feed chute of the scrubber. As the drum rotates, lifter bars on the inside lift the solids to the 11 o clock position The material then cascades to the bottom of the drum ROTARY SCRUBBER PROCESS As the drum rotates, lifter bars on the inside lift the solids to the 11 o clock position The material cascades to the bottom of the drum 4

5 GENERAL ARRANGEMENT CHAIN/SPROCKET CYLINDER TRUNNION BASE DRIVE FEED CHUTE CYLINDER DESIGNED FOR 4-POINT SUPPORT SPLIT DESIGN MACHINED FOR CONCENTRIC SURFACES 5

6 LINER OPTIONS DEWATERING OPTIONS 6

7 Desanding Options 13 7

8 SELECTION So what do we need to know? SCRUBBER/TROMMELS are highly specialized so each application must be reviewed by a scrubbing specialist. - Type of Material to be Processed - Type of Deleterious Material to be Removed - Desired Capacity - Feed Size - Sample of Feed Material 8

Log Washers Samuel Calvin McLanahan patented the Log Washer on January 27, 1891

! Screen out Sand Fractions Capture solids from overflow(?

9 Log Washers Samuel Calvin McLanahan patented the Log Washer on January 27, Design / Application Considerations Screen out Oversize!! Screen out Sand Fractions Capture solids from overflow(?) Eliminate rear overflow for maximum retention time Watch for (concreted) build up in corners Follow with a Rinse Screen 9

10 In Operation Log Washers - Influence of Slope As % deleterious material increases Increase slope Typical 0 14 degrees Steeper slope increases retention time 10

11 Log Washers - Influence of Slope Spray Water usgpm at 75 psi 11

12 Straight vs Spiral Paddles Straight Paddles = More Power transmitted to material Spiral Paddles = Faster Conveyance Shaft Arrangement One Piece Shaft Paddle Base Paddle Flanged Connection Typical 12

13 Typical Arrangement 25 Log Washer in Action 26 13

14 Aggregate Conditioners 27 Why use an Aggregate Conditioner? To Condition material prior to further wet process (Wet Screen, Sand Tank, Screw Washer, Helps to break down deleterious material in sand and gravel Feed Size: 4 x 0 14

15 AGGREGATE CONDITIONER PROCESS Similar in appearance to Coarse Material Screws ALL material and water that feeds the Aggregate Conditioner MUST exit through the discharge opening opposite the feed end There is NO overflow outlet Combination of paddles and flights arranged in an alternating pattern AGGREGATE CONDITIONER PROCESS Typically run at an incline of 0 to 5 degrees Higher capacities when compared to Coarse Material Screw Washers Feed to Aggregate Conditioners should range from 65% to 70% solids by weight Typically, the feed has the consistency of a concrete slump 15

16 Paddle & Flight Arrangement 16

17 Design Features Twin Seal Pak Bearings Submerged Rear Bearings Duo Cone Seals Weep hole Grease Cup Outboard Mounting 17

18 Typical Arrangement Typical Arrangement 18

19 SELECTION What do we need to know? What is the required capacity (TPH)? What is the max feed size? What type of deleterious material needs to be removed? product? Sample of Feed Material Feed Processing 19

20 Coarse Material Screw Washers 39 PURPOSE Removal of light, loamy clays, dirt, crusher dust, and coating that cannot be removed by wet screening alone Can remove organics Feed Size: 4 x 4 mesh Typically is followed by a rinse screen. 20

COARSE SCREW WASHER PROCESS 4 x 4 mesh feed and water are introduced in the feed end of the unit Paddles and screw flights provide a light scrubbing and agitation This scrubbing along with rising

21 COARSE SCREW WASHER PROCESS 4 x 4 mesh feed and water are introduced in the feed end of the unit Paddles and screw flights provide a light scrubbing and agitation This scrubbing along with rising current water breaks down and washes off light coatings and light clays Organics removal (i.e. wood, leaves, etc.) The cleaned product is then conveyed to the discharge end of the box A rinse screen typically follows the Coarse Material Screw Washer Design Features 21

22 TWO PIECE PADDLES & SHOES Twin Seal Pak Bearings Submerged Rear Bearings Duo Cone Seals Weep hole Grease Cup Outboard Mounting 22

23 Portable Unit Typical Arrangement 23

24 Multiple Products Material Handling 24

25 Special Stainless Steel Box SELECTION So what do we need to know? What is the required capacity (TPH)? What is the specification of the product the customer wants to produce? What is the max feed size? Has the / will the -4 mesh material be removed? Product may need to be run over a rinse screen 25

26 Attrition Cells 51 Gearbox Motor Shell Baffles Paddles Outlet Shaft Hubs Inlet Drain 26

27 Shaft & Paddles Paddles pump up or down Alternating arrangement down up down up down Attrition Cell Paddles 54 27

28 Typical Flowsheet Typical Arrangement 28

29 High Pressure Washers Questions?? 58 29

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