Hi Shakee

You can extract at 4000t/h or whatever, if you want to. 1000t/h is nothing out of the ordinary

The thing is though, that the hopper above must have a compatable capacity, especially so it is not always running empty.

The rule of thumb is that the hopper's minimum capacity is about 15 minutes throughput.

At 1000t/h this is a minimum of 250 tons

Cheers

LSL Tekpro ■

An apron feeder uses gear reduction to provide the end user

with a slow balanced feed rate to avoid flooding the transfer

point and stoping the belt from an over weight condition.

AN apron feeder draws from the rear of the hopper to the front

en mass and pulls the entire load forward for discharge on to the

conveyor or dumping into a rail car ■

Other reasons for apron feeders is that they normal can take higher outlet loads and give higher pull out forces than belts and serve wider outlets. A degree of progressive extraction can be secured by tapering the hopper outlet or, in some cases, fitting inverted wiers ■

Hi Shakee..

Belt feeders are getting more popular as extraction devices, and are being used in fairly heavy duty applications.

In Chile at the copper mines, I have seen them under primary tips, and use belts with thick top cover.

I have used an ordinary belt feeder under a rail wagon unloading hopper with no problem. This was for coal.

When you have a direct vertical drop of dense material of large lump size, then you have to design the hopper for minimum impact. I have used belt feeders under an 8000ton -80mm lump size Platimum ore silo. No direct impact on the belt so it works fine.

So use apron feeders if you have regular direct vertical imact of heavy lumps.

Cheers

LSL Tekpro ■

Belt feeders can be designed and supplied for very abusive applications including receiving face blasted copper ore and waste from end dump haulage trucks and feeding the coarse bulk material to the primary gyratory crusher. I have done this both at 2000 t/h and 3000 t/h. It takes special care in design, beginning with the belt then the cushioned rolls, typically large diameter with thick split lagging. The hopper design is very important in mitigating wear and tear but, this does not spare the requirement that the feeder must, at its surface absorb the energy of the free falling maximum lump size. Once in operation it always helps to train the operator to manage the speed so that the load on the feeder does not go bare thus minimizing the direct impact from free falling material.

Joe Dos Santos ■