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Optimizing cone crusher performance on clay (3 replies and 3 comments)

Dzapasi
1 week ago
Dzapasi 1 week ago

We have an HP300 crusher in our operations carrying out tertiary crushing duty where it reduces material of P80 - 32mm to P80 - 16mm.  The ore feed is kimbelite ore which is resulting in a clayish product build up in the crusher discharged chute and crusher cavity which in the last experience resulted in materiel build in the chute blocking it out and resulted in wearing out the counter weight, the socket and the head bush of the crusher. The crusher is in a closed circuit with a wet screen but we are not adding any water into the crusher its mainly crushing material with surface moisture in the range of 8-12%. The question is there anyone out there who has had such experience with a cone crusher and before making a decision to go to the market and buy a replacement crusher, what remedial actions to optimize performance. We have currently shut of the water on the wet screen and are running the plant in dry mode but it comes with many problem of dust generation,  and we go into the wet season the little rain on the ore wil resulting in the screen caking up the reason we intended to move to wet screening but now have revered back to this undesirable state despite its disadvantages. 

AJNeale
1 week ago
AJNeale 1 week ago
1 like by David

Clay in a cone crusher - the bane of operators for generations.  One option is to look at a rotary scrubber with trommel or a rotary scrubber with a separate vibrating screen, either ahead of the primary crusher, or after the primary crusher (depending on the top size of the material going to the primary crusher).  Water is added to the feed end of the scrubber, and can also be added to the vibrating screen.  The fines (-8 mm to -10 mm depending on your grinding circuit feed size, can then be pumped directly to the grinding circuit.  While these units are not cheap, they allow you to take out all the fines and bypass the entire crushing plant, and "voila" many of your crushing problems go away.  The downside is that the fines bypass any weightometers in the crushing plant so you have to estimate these tons by other means in order to complete your metallurgical accounting.  If you can give us an estimated feed rate to the crushing plant we (the collective 911 Metallurgical Group) might have some additional ideas for you.  Best Regards - Andrew 

Dzapasi
4 days ago

Hi AJNeale thanks for the feedback, just to clarify a little bit more the feed to the crusher is closed with a screen (the one in wet operation) and the feed to the crusher is between 7-11% passing the CSS of 16mm. we are currently ruuning all proces in dry mode s o that the tertairy does not cake up but once we go into the rainy season which we are in now clogging problems manifest on the screen which we were trying to avoid by wet screen. in dry mode the caking in the HP300 disappears but in the wet season that we are in now the screen cloggs then the materail is all short circuited to the crusher with fines now ( increase in percentage passing CSS of 16mm) resultantly the caking in the crusher resurfaces.

David
1 week ago
David 1 week ago

Hello Dzapasi, since the silence is killing me and likely you too, I will take a run at this. I have some experience with high moisture crushing but am nowhere near 'an expert'. This will give you some things to review/consider.

As you see here, cone crushers and clay, do not get along.

The following factors will detract from crusher capacity and performance:

1. Sticky material in crusher feed.
2. Fines in crusher feed (smaller than crusher setting) exceeding 10% of crusher capacity.
3. Excessive feed moisture.
4. Material cleanliness
5. Feed segregation in crusher cavity.
6. Insufficient scalper and closed circuit screen capacities.

You may want to review your crusher liner shape. A cone crusher concaves may be straight (smooth), modified straight, or non-choking. Curved concaves are useful in crushing rocks containing sticky, moist, or dirty material that may otherwise clog the crusher. The modified straight concaves are a compromise between the straight and the non-choking concave types. These shapes do not affect the crusher capacity very much. These liners were originally designed for high-speed gyratory crushers and may be (or not) adapted to cones?

Frequent Chute Cleanup

It is lots and lots of work but you may have to demand more frequent cleanup of places where you know material will stick. Hammers, air lances, long bars or other tools. Have you tried teflon lining of some chutes or sidewalls?

Crusher Capacity VS Crushing Rate

Are you crushing too fast? Do you have spare capacity or wasted operating time during which you could crush slower which would allow you to handle those fines a bit better? What is your current crusher operating time? I have seen plant complaining of wet ore and cone crusher packing while they were only crushing 50% of the time ie: the cone was needlessly being over loaded. The cone was overloaded AND so was the screening deck before the crusher = bad screening = extra fines + extra wets into the cone.

Screening Media Patterns

What are you screening with?  Steel? Square holes? Polyurethane? Are you screening well?

I have had good success using these to screen out wet sticky cone crusher feed.

Dust Control

Are you dust sprays "sprays" or fire hoses?  Some over use and waste water with poor spray design which makes everything muddy/sticky.

Can you share some photos/videos of your situation?

++ As Andrew mentions, consider something like https://www.911metallurgist.com/blog/crushing-grinding-wet-ores

Crushing and Grinding Tropical Ores

Dzapasi
4 days ago

Thanks David have pulled out some pointers and the points above gave me a lot of ideas especially on the screening media we currently use sq polyU panels and comparing with VR they are definety worth a try. On the utilization aspect we aim to run the crusher as much as possible as it has to generate a stockpile for down stream plants so the current problems on the tertiary crusher are resulting in the circuit producing less than downstream capacity. i will forward some photo's on the effects of the clayish material in the crusher crushing cavity and discharge. the liner change out i have forwarded to OEM to confirm if they have such liners to assist with our challenge. thanks once again.

Craig Lockhart
6 days ago
Craig Lockhart 6 days ago
1 like by David

Hello Dzapasi,

There is likely not a problem with your cone crusher, so replacing it will not gain you anything unless your Omnicone is already mechanically beyond hope.

The problem is with the inability of your screen to adequately wash the fines out of your crusher feed, likely combined with poor drainage through the deck beyond the spray zone(s).  The most common cause of this that I am aware of is insufficient water application, usually a combination of inadequate volume and inefficient or incomplete spray pattern coverage.  There should be several spray applications down the length of the deck starting after the first set of open panels and at least 2 additional applications (spray bars) evenly spaced to about 2/3 to 3/4 of the way down the deck (leave the last 1/4 to 1/3 of the deck for draining water) - there should be alternating spray and drain intervals down the deck to achieve the best wash for minimal water volume.  Your crusher feed should contain no more than ~4-5% moisture, provided you can remove the fines that are transporting the excess.  To determine the best moisture content you can expect, try wet-screening (washing) a bucket of crusher feed at 12 mm and immediately check the moisture content of the oversize. 

If your deck is inclined, consider reducing the angle to slow the flow of material down the deck.  Screen panels with "dams" on them as shown in the second photo in David's reply will help spread the material evenly across the deck and also slow it down to help both washing and draining.

On the underside of your mantle, you may be able to attach blades to knock buildup off of the eccentric support arms before it can contact the balance weight or get into your eccentric seal.  You may also be able to find (or have cast) eccentric arm liners with steeper angle to better shed buildup.  For buildup in the chutes, consider lining the areas that build up with UHMW polyethylene to better shed sticky material.

Best of luck with your optimization efforts,

Craig

 

Dzapasi
3 days ago

Thanks Craig the pointer to the water distribution on the screen really open up some avenues of areas we will need to optimize, the pointer to the UHMW polythene has confirmed a liner change idea we were throwing around so thanks for firming up this area.

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