You wouldn’t take your garbage back in the house, so why send pebbles back through your grinding mill?
Pebbles exiting AG/SAG mills are an expected occurrence – like garbage generated by a typical household – and an unfortunate artefact of processing (both ore and food). Some households make more garbage while others less, but little thought is given about the composition of garbage – if it’s labelled “garbage” it’s garbage, right? Where else do you put garbage other than at the curb, waiting to be picked up and taken away?
The same consideration is given to mill pebbles: the hard, coarse material that exits grinding mills or else it would restrict flow and throughput – heaven help us, it restricts throughput. And yet, what do we do? We put them right back in the same device that rejected them – why, we don’t do this with our household garbage? This is the question we should be asking: why are we potentially bringing garbage back into the house?
The simple answer is because there’s nowhere else we’re prepared to send them. If we didn’t put the garbage on the curb, where would it go? Getting back to the mill side of the story, it’s quite common for pebbles to represent 10%, 20% even 30% of the plant feed – that’s a lot of potential garbage. So why do we put up with this? Labels are very powerful things: if it’s calling material “garbage” or calling material “ore”, we inherently assign value to everything contained within the label.
As recycling has improved everyone’s “to the curb” efficiency and reduced wastage, so can we look at our pebbles – do they ALL need to go back into our mills? Pebbles are not all garbage – there is an element of good and element of bad – a portion that can be recycled and a portion that needs to go to the dump. How many of us truly knows how much of our pebbles should be recycled?
Having access to a lab-scale XRT sensor, SRK Consulting can now assess the true value of your mill pebbles. What fraction can be recycled and what fraction should go to the curb and not restrict throughput. SRK can complete a review of your mill pebbles and finally answer the question: “Are they worthy of being returned to your mill?” Let’s find out together.
