2/28/2018. Optimizing Cone Crusher Performance Jeff Gray. Three Focus Areas

Transcription

1 Optimizing Cone Crusher Performance Jeff Gray Three Focus Areas Part 1: Compiling application data Part 2: Cone Installation characteristics Part 3: Symptoms and solutions 1

2 Part 1: Compile Application Data Feed Gradation Desired Output Gradation Finish Product Specification, if applicable Operating Modes and Frequency of Use Material Characteristics Replacing an Existing Crusher Good Input data via sampling creates a reliable simulation and helps expose opportunity for enhanced performance. T-400 C-10 Sampling DATE 2" 1 1/2" 1" 3/4" 1/2" 3/8" 1/4" 1/8" #20 #40 #80 #200 TPH Setting 7/ / / / AVG Feed Gradation Average of 3-4 belt cuts in each mode 3 minimum (tertiary crusher feed) Longer cut on coarser material (secondary crusher feed) 2

3 Feed Gradation Special attention if a common bin feeds two crushers. May need to put cone in clear mode to let feed pass through to discharge belt for sampling. Feed Gradation Be conscious of screen efficiency in replacement crushers Sample the raw feed and the recirculating load off of the sizing screen AggFlow may provide a higher screening efficiency than reality. Verify by sampling the overs from the deck feeding the crusher if possible Urethane, rubber media effect Screen may have mechanical limitations that prohibit using the ideal speed and stroke Does moisture or rain affect feed to cone? Fine crushing Desired Output Gradation What are target products? What do you need more of? What is the best selling product? What are you making that you don t need? 3

4 Finish Product Specification Verify required specifications of finish products Confirm if state specifications are modified to meet specific customer requirements Concrete rock Finish Product Specification Define cubicity requirements ASTM D 4791 Superpave spec for hot mix asphalt <10% flat & elongated particles using a 5:1 ratio Are they being met in existing equipment? Sample existing process Finish Product Specification Understand the operational variables in the plant that affect cone feed and ultimately finish product gradation. 4

5 Operating Modes Define operating scenarios that affect feed to cone Maximum base mode or no base Maximum concrete/asphalt rock mode Pulling rip-rap Pulling 3 x1 gabion rock Railroad ballast Pulling a small percentage of a low volume product is always better that turning it on and off Operating Modes Production Recipe Max Concrete Rock Secondary 1.30 Tertiary cone 0.87 Finish screen downhill All base pull for product Wire cloth: Top 1.00 Middle 0.50 Bottom 4mesh Max Asphalt Rock Secondary 1.20 Tertiary 0.62 Finish screen uphill 25% base forward Wire cloth: Top 0.75 Middle 0.38 Bottom 8mesh Material Characteristics Compressive strength Los Angeles Abrasion test Lower number = harder rock Limestone Basalt Weight of material lbs./ft3 Fracture shape tendency Geology Affect of moisture or rain Sand and gravel deposits Very round Flattened 5

6 Replacing an Existing Crusher Gain understanding of performance in all modes Sample before decommission Information on liner profile and countershaft speed is helpful The better understanding we have of the past, the better chance we can improve the future Part 2: Installation Characteristics How is feed brought to cone? Control of Feed Level Recirculating Feed Sampling Process Centering Feed Mixing Feed How is Feed Brought to Cone? Conveyor Chute off screen Vibrating pan feeder Belt feeder 6

7 How is Feed Brought to Cone? What s the best method in your opinion? All can be done successfully but here is my ranking Pan feeder from bin Quick feedback from level sensor Belt feeder from bin Second place only because of the moving parts and skirting Some like them because they can fix them Conveyor No other option in portable spreads If conveyor comes from a surge tunnel with feeders, not so bad Keeping feed centered can be challenging Off screen Limited level control unless feed is very uniform Mays sacrifice optimum cone capacity Control of Feed Level Hopper over cone Supported from crusher upper frame with overflow Sits on crusher feed hopper Needs to move with upper frame Allow 2-3 above the nut cap Is visibility needed? See material in overflow chute See material in hopper Control of Feed Level Sensor types Laser Radar Ultrasonic Tilt Switches Presence detector 7

8 Control of Feed Level Variables that determine what level sensor is used Distance from target Range of measurement Lump size of particles Flow of material into bin or chamber Dust Radar common in bins Laser common in crusher chambers Control of Feed Level Control of Feed Level Tilt Switch overflow protection Radar Sensor used for bin level 8

9 Recirculating Feed Where is it introduced? Conveyor Bin Both into cone hopper Blending with raw feed How is it mixed Ratio to raw feed High recirculating load crushing (fine) Account for variation during start-up Takes time for circuit to stabilize Role recirculating feed plays in total feed gradation Sometimes needed to get a well graded feed Sampling Process Planning for sampling Logistics of crashing the plant for sampling Understand shutdown timing sequences Any transfer point issues? Room under crusher for crusher to crush out load in hopper What will need to be shoveled off prior to start-up? Feed sample out of bin Lift upper frame Feed sample out of surge pile Feed & discharge sample off conveyor Coarser material feed sample Safe access for sample Transport of buckets Centering Feed Design in ability to center the feed Left to Right Front to Back Vibrating feeder with circular discharge spout Stop and Start feed to understand how crusher loads up and empties out Illustrates distribution around head and segregation Crusher load up Crusher empties 9

10 Mixing Feed Cones are not mixers Well graded & distributed feed = maximum production Simple test Fine Coarse Shovel Calibration Mixing Feed Deflectors Part 3: Symptom - Solution Symptoms operational or mechanical problems that exist Solutions changes or checks to eliminate or reduce symptoms 10

11 Upper frame bounce Why do manufacturers allow the upper frame to lift? Feed gradation sudden change (loss of voids) Screen cloth blinding Setting may be tighter than you think Hole worn in chute, flop gate opened Hydraulic relief cylinder or accumulator issue Steel in crushing circuit Feed off center Most obvious when feed is first brought to crusher Upper frame bounce Liner profile to coarse or to fine for feed gradation Upper frame bounce Well Graded Feed: 90 to 100 percent passing the closed side feed opening. 40 to 60 percent passing the mid point of the crushing chamber. 0 to 10 percent passing the crusher setting. Inter-Particle Crushing 11

12 Inconsistent finish product gradation Variable crusher loading In and out of choke feed condition Choke feed height variation Variable feed gradation to crusher Coarse products pulled ahead of crusher Crusher auto adjusting open Poor Cubicity Not able to consistently choke feed crusher To High of reduction ratio Ideally 3:1 to 5:1 Higher reduction ratios = less inter-particle Closed Side Feed crushing = poor cubicity Opening CSFO Poorly graded feed Ideally feed gradation should have material from CSFO down to closed side setting Watch affect of base product being sent to finish plant May not see a crusher Closed Side Setting CSS Open Side Feed Opening CSFO Poor Cubicity The further in the process elongated particles carry, the harder they are to remove Look at each stage of crushing Choke feed on secondary is as beneficial as tertiary A trickle fed jaw in slabby limestone Not uncommon in older crushing circuits to just send +3 to a secondary 12

13 Poor Cubicity The wrong chamber with the ideal reduction ratio may not produce the best cubicity because interparticle crushing is less prevalent. Poor Cubicity Geology Rock have differing strengths in different directions due to cleavage which is a tendency to break along smooth planes parallel to zones of weak bonding can present cubicity challenges Limestone - sedimentary Slate metamorphic, fine grained homogeneous High Amp Draw Reduce fines or near size in chamber Speed crusher up Change liner to crush higher in the chamber 13

14 Want a finer output gradation Adjust CSS No CSS adjustment Adjust choke feed height higher Increase speed (within MFG limits) Re-crush more material around the CSS Reduce throw of crusher (if possible) Lengthen parallel zone on liner Want a coarser output gradation Adjust CSS No CSS adjustment Adjust choke feed height lower Decrease speed (within MFG limits) Shorter parallel cone on liner Poor throughput new liner Wrong feed opening most likely Usually low amp draw even when choked Poor shape Ensure feed is well distributed/centered Ensure feed is blended 14

15 Pockets wear into upper liner Material not entering feed opening easily Head spin can enhance Coincide with low amp draw and poor cubicity Belly at bottom of liner Excess near size Tighten CSS Look at screen efficiency May coincide with upper frame bounce and high amps Proper CSS for liner Mantle and concave wear and same rate 15

16 Concave curls over TPH drops Liner is not designed to run at tight setting 3/8 CSS Mantle ski slopes TPH drop Liner is not designed to run at coarse setting What issues do you have? 16

17 Thank you! 17