What is the difference betwixt a mobile crusher & a semi-mobile crusher? Either the gadget is mobile or it is fixed. Beware erroneous manufacturing jargon!

The only consideration is the mobility of the outbye equipment. If that can't move readily then your expenditure was all for nought.

Haulage cost is not part of the crushing cost...is it?

When quarrymen talk about haulage cost they invariably include loading cost. Loading cost is not usually variable & must be distinguished at all costs, HO HO. If you can keep the crusher up against the eg. working face then the loading cost will always be the same & the haulage cost becomes concentrated in the conveying mode. If you still have to haul to the crusher in vehicles then you have hurled loot at a complicated machine which isn't doing its job. ■

Metso Minerals & FLSmidth would be happy to oblige. Krupp are also in the business of impressing potential clients with sophisticated simulations. They all do a fine job if you can catch them in a good mood. ■

My theory is if you are looking to go portable, then make the equipment move easy, fast, and in as few loads as possible. It is worth spending the money to invest in such things as hydraulic pin-on jacks, pony motors on the machine for leveling, etc. Every application is pretty much company and/or site specific. So you should really judge the application(s) you are looking at putting the plant in before you really decide. Are you going to be crushing in just pits or doing site work such as roadway demolition? That should answer the main question of tracked machine vs. on axles. What kind of tonnages per set are you looking at? Larger tonnages should require a larger machine which equals more loads which equals more mobilization cost. There are quite a few variables that are required when looking at a plant, but in my opinion I would make it as portable as possible for your applications. ■

You want a Monte Carlo simulation model. I don't believe Metso or FLS or Krupp have such skills. They have not exhibited this knowledge in any of our associations.

The most published work is from Prof. John Sturgul from his many mine plant simulations using Monte Carlo:

Phone: (208) 885-7939

Email: sturgul@uidaho.edu

Title: Academic Faculty

Department: Mechanical Engineering

Office: MCCL 405B

Campus Zip: 3024

If he is incognito, you can email me at the below address. However, he is a lot less expensive than anyone I know. He does not make comprehesive models unless asked. ■

Since you have not mentioned much information or desired product size or end use:

Your opportunity cost is primary!!, your desired size of crushed ore is secondary; which relates to the market for the limestone.

The finer the crush the more ore can be hauled from a to b in one load.

Another consideration is the use of a skid mounted or crawler mounted feeder breaker such as those built by WR Stamler, Long Airdox; Roscoe, Mclanahan etc they allow you to break material to a very, very small run of mine size and be powered by a portable generator or 480 volt trailing cable.

All that would be needed is a mobile take away conveyor fed with a front end loader with a side tipping bucket to feed a very small mobile crushing and final screening plant for your use.

The same front end loader can be used for feeding the feeder breaker as well.

You could contract out crushing for other firms with the mobile breaker as they are easy to transport and maintain and very easy to operate with basic 480 volt electrical controls for the flight chain drive-forward or reverse and a continous rotation in one direction drive for the breaker pick assembly.

These units have two 480 volt three phase motors with reduction gearboxes powering the flight chain and the breaker pick assembly.

As an example the model 33 frame size WR Stamler feeder breaker will break and feed 900 tons per hour of ore at its maximum throat size, it will break and feed 450 tons plus per hour at the six inch run of mine ore size delivering it on a 36-42 inch conveyor mounted in a linear fashion to carry away broken rock at 300 plus feet per minute.

The electricaly powered belt feeder breaker operates at one delivery speed to offer consistant feeding and crushing at all times

reducing the possibilty of spills of material.

The real beauty of owning a feeder breaker for surface primary crushing is cost savings as you could do primary crushing for months in advance and rent a secondary crusher(such as a "pegson" or other brand with a screening plant for a few days around the clock and not have to own the secondary crusher screener and not having to maintain it is also a plus as well.

A decision tree is warranted here.

Disclaimer:

I do not represent any of the above mentioned firms.

lzaharis

questions or comments;

lzaharis@lightlink.com ■

Take into consideration for the following factors:

capacity

crushing ratio

final particles

performance

maintenance

after service

You can get more details by visiting http://www.sbmchina.com/products/Crushing/. ■

I thought I already mentioned all of this in my previous post. ■

If the question is simply mobile vs semi-mobile, then the primary consideration should be how often you need to move it - if you are planning on moving the thing around a pit regularly, then a track mounted unit would be more appropriate, but if its for contract crushing where the plant will be stationary for maybe a few months, then a trailer-type unit like a MACS plant (built by Cedarapids) is probably the way to go.

Once you decide on this, it's probably better leaving it up to the vendor to work out what crusher / screen combination you will need. Any vendor selling this sort of stuff will be able to model rocsk in vs rocks out with the equipment they are selling. ■

Hi Faisul

I am amused by some of the replies to your thread. Please don't be misguided by some of the comments.

We are nearly complete with an investigation into the overburden stripping system for one of the largest if not the largest open cast coal mine in the world here in South Africa.

We have to decide whether to go mobile, movable, semi-fixed or fixed.

We also have to decide if we will primary crush only or secondary crush as well, or even put in an impact crusher to do the job.

We also have to decide if its worth the bother or should we truck or partially truck even with the high diesel cost.

I know of several attempts to use mobile crushers which have failed miserably.

There is (or probably was) a "mobile" crusher installation here at a limestone mine in Beestekraal. They never moved it to my knowledge. They simply raised it up and down once a week to see if the hydraulics still worked.

For another example the mobile crusher with 54/74 gyratory with shiftable conveyors etc. they put in here in Phalaborwa.

We put in a fixed crusher station for them to replace it.

On the other hand, I have seen some nice mobile crusher stations working in the limestone quarries in Kent in England using Hazemag impact crushers.

So we do a very thorough investigation before we recommend to the client what to use.

We use our own in-house simulations and costings and thoroughly investigate the practicality operability and flexibility of all possible systems.

What we often have found is that semi-fixed installations, that we move it roughly 5 year intervals, are the best as we have demonstrated with our semi-fixed, but moveable crusher station here at the Namakwaland plant where our dual carry conveyor is.

We are giving a lecture at the end of the month at the "Mine Haulage Conference" in Johannesburg and covering this in some depth.

Its called "To Convey or not to Convey think...... Suitability, Flexibility, Conveyability Availability"

Cheers

LSL Tekpro ■

We still do not know what he is doing with his limestone or for that matter if he has any deposits of same.

WR Stamler and Long Airdox Roscoe Belt feeder breakers have been in use since the 1950's.

The Mclanahan units have been on the market for a few years with hydraulic drives through reduction gear boxes as final drives for the chain drives and breakers.

Regarding proper maintenance; if it is not done for the sake of saving time and increasing production rates over quota's and a machine fails because a simple repair was not done; all the screaming and disgust over broken machinery solves nothing. ■

Dear Zenith..

Horses for courses as they say.

Your little mobile crushing plant is fine for quarry type applications, but its not so good for feeding a conveyor system which transports stuff away.

As such, its not the mobile crushing plant that is the problem, but its the hastle of the mobile link conveyor, the shiftable conveyors and extendable conveyors that have to keep up with it.

That is why semi-fixed applications have a very good track record and do have their place.

(Look at the whole system, not just the bit on the end)

Cheers

LSL Tekpro ■

For the first and last time place your advertising on the new products page of the forum!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

These pages are ment for asking questions and offering real

world answers for real world problems and offering real world answers and not for advertising products.

If you wish to advertise with us place your product line on the forum mast head by contacting the folks at bulk on line and spend your yuan doing so!!!!!!!

It is insulting to the other advertisers on the forum and forum members as they follow the forum web sites rules in regard to advertising and you apparently have no desire to do so! ■