• To participate in the 911Metallurgist Forums, be sure to JOINLOGIN
  • Use Add New Topic to ask a New Question/Discussion about Crushing.
  • OR Select a Topic that Interests you.
  • Use Add Reply = to Reply/Participate in a Topic/Discussion (most frequent).
    Using Add Reply allows you to Attach Images or PDF files and provide a more complete input.
  • Use Add Comment = to comment on someone else’s Reply in an already active Topic/Discussion.

Eliminating the problem of shale through crushing and screen ... (7 replies)

Marshal Dienes
10 months ago
Marshal Dienes 10 months ago

There is a lot of shale that reports to our crushing and screening coal plant and because of its flat shape it goes through two stages of crushing (using double roll crushers) without being crushed and therefore creates problems downstream. How can I ensure that the flat un-sized shale does not reach the washery?

Jean Rasczak
10 months ago
Jean Rasczak 10 months ago

You can consider passing your raw coal stream through a Bradford Breaker. This will solve the slabbing problem. You can acquire this equipment from Osborn in Jet Park, Boksburg.

Carmen Ibanz
10 months ago
Carmen Ibanz 10 months ago

Your problem is generated by two factors: 1) Coal crystalline structure; 2) Specific breakage process of the roll crushers. I met a similar situation (magnetite ore) generated by the particular form of the ground particles resulted from high pressure grinding process with a significant negative impact on the screening efficiency. Joe’s remark is right: You are obliged to break the coal by impact, using the Bredford equipment, hammer mills or impactors, depending on your process and product required parameters. Additional CAPEX!

Sugar Watkins
10 months ago
Sugar Watkins 10 months ago

Rotary breakers (Bradford breakers) sound like a perfect solution gentlemen. i actually proposed this before to senior management but it seems as though it will take a bit of time before introducing it to the circuit. As a result i need to find a solution that will work in the meantime.

Bill Rico
10 months ago
Bill Rico 10 months ago

As you are looking for a short term solution you could try what we practiced in India - provided you have enough affordable manpower. Exposed to Sodium Vapour lamp illumination shale can be identified when the coal is moving on a slow moving conveyor picking belt because of the difference in reflectivity of shale and coal.

Zander Barcalow
10 months ago
Zander Barcalow 10 months ago

A quick fix, but with other impacts, would be to close up the setting on your crushers. This will shift your size distribution downward, but should reduce the amount of shale slabs.

Marshal Meru
10 months ago
Marshal Meru 10 months ago

Have you checked your crusher tooth if they are worn-out? It could be that they need to be replaced. High shale throughput tend to increase the wear-rate.

Ace Levy
10 months ago
Ace Levy 10 months ago

As suggested by seniors use a slow moving belt conveyor for the purpose of stone picking by the help of casual Labour. Which ultimately reduces the wear and tear in crusher teeth. Otherwise check your crusher nitrogen gas cylinder working pressure. Or the gap between the crusher. Or it may happen due to over feeding.

Please join and login to participate and leave a comment.