First things first:

You have not mentioned the type of coal you are processing/crushing/screening.

Second:

What is the desired size of the crushed coal product?

Third:

Are you feeding a coal stoker, or making coke or

grinding to minus thirty mesh for power generation in a forced draft boiler?

Single roll crushers and double roll crushers all have their advantages and disadvantages, the biggest being continuos maintenance for either type involving bearing failure and hardfacing of the roll and loss of size control of crushed product and plugging the crusher from oversize material.

With any machinery the simpler it is the easier it is top take care of- case in point

The Pennsylvania Crusher companies

Bradford Breaker- it combines a rotating drum with

lifting paddles and screens to allow breakeage and screening of product at the same time to the desired size of product with few moving parts and also easy repairs and they have in use since 1905.

the simpler the better and it save s a lot of maintenance and labor as it is a breaker and screen in one unit.

I do not represent the Penncrusher Company.

google Penncrusher or Bradford Breaker. ■

Sir

We could supply both these machines

Simon Pearson

www.anglo-crushers.8m.net

Tel + 44 1484 543300

cell + 44 7887714523 ■

Ok, it all comes down to the size of your budget for plant.

As I said before they are a maintenance intensive piece of equipment.

One crusher has no advantage over the other as it all relates to incoming product size to be reduced and its hardness.

You have either two or four bearings to always worry about and if the crusher goes down because of one bad bearing you are in trouble and you will be down for a long time unless you are set up with an overhead crane and complete replacement roll and bearing set ready to be installed to replace the bad roll or rolls.

As far as production goes you are stuck unless you have paralell crushiing circuits to bypass the system that is broken and in need of repair.

I personally would not have a single or double roll crusher in plant-simply based on my experience with a double roll with a stationary roller and a sliding gauge roller crusher roll in rock salt.

You have not mentioned the percentage of slate or limestome waste in your incoming bituminous coal either and this is also a huge factor in your searching as well.

As I have stated previously the Bradford Breaker is a simple and easily maintained crusher with few moving parts and Pennsylvania Crusher will crush samples to proof their equipment for your purpose.

The penncrusher folks have been making these machines since 1905 so they must be doing something right in my opinion as a mine equipment mechanic. ■

DEAR SIR,

FOR YOUR CRUSHING AND SCREENING PLANT,WE CAN GIVE YOU

SHEET METAL FABRICATED BELT CONVEYORS.

NORMALLY MOST OF MANUFACTURER ARE PROVIDING CONVENTIONAL STRINGERS FABRICATED OUT OF ROLLED CHANNELS .

WE HAVE SUPPLIED THESE CONVEYORS TO ALL MAJOR ROAD CONSTRUCTION COMPANIES IN INDIA.

THESE CONVEYORS ARE HAVING FOLLOWING ADVANTAGES :-

1)THE CONVEYORS SUPPORTS DONOT REQUIRED ANY FOUNDATION WORK.

2) THE CONVEYOR STRUCTURE WILL BE STURDY AND ROBUST TO

TAKE MORE LOAD.

3) THIAS CONVEYOR IS EASY TO ALIGN AND WORK SMOOTHLY IN ONE LINE.

4) THE WEIGHT OF SHEET FABRICATED STRUCTURE WILL BE MORE AS COMPARED WITH ROLLED SECTION.

THANKS

BALVINDER SINGH

M/S C.M.L.ENGG PROJECTS P LTD

S-18,PRATAP MKT,JUNGPURA-B

NEW DELHI-110014

PH:-011-24379086/55650794

FAX:011-24371017

E-MAIL:rajputeng@rediffmail.com

balvinder2000@rediffmail.com

mobile :-09899777763 ■

It is obvious that u intend to crush Indian coal with ~30+% ash. Roll crusher is ot ideal for this type of coal. Wear is too high and you will be hardfacing rolls very frequently.

Better solution is to use impactor. Here again you will be hardfacing hammer heads but less frequently. For such coals u have to use equipment suitable for hard limestone or basalt.

Vinayak Sathe Tel: +91 832 2538294 ■

Dear Shri Venkateswaran l,

In case of single roll crusher, the rotating roll is dragging the material against the stationary anvil. So, the material crushing is by compression and attrition. The material velocity in crushing zone will be somewhat less than the roller peripheral speed. So, it will have a rubbing action on the roll. This moving material is also rubbing with the stationary anvil. So, single roll crusher is generally not used for very difficult and very abrasive material. If used, its life will be comparatively less.

In case of double roll crusher, both the rotors are drawing the material inside. Therefore, material crushing peak pressure occurs when there is no relative motion between material and rollers periphery. So, it can be said that the crushing is more by compression and least by attrition or sliding. Therefore, such crusher can handle very difficult material. Also, by adopting differential rotor speed, they become self-cleaning while handling sticky material. Thus, they are also used when material is tending to clog. Therefore, if you have money you can opt for double roll crusher. If economy (initial investment) is dominant, then opt for single roll crusher. Both the crushers are used in practice.

Regards,

Ishwar G Mulani.

Author of Book : Engineering Science and Application Design for Belt Conveyors.

Author of Book : Belt Feeder Design and Hopper Bin Silo

Advisor / Consultant for Bulk Material Handling System & Issues.

Email : parimul@pn2.vsnl.net.in

Tel.: 0091 (0)20 25882916 ■