eRocks

1. Introduction
Rock breakage behaviour has been studied since the 1920s and has been used to quantify the working limits of rock. The energy required for breakage has also been used as a means of quantifying rock comminution characteristics. A great number of different laboratory and in-situ tests have been developed since the 1920s.

The needs of an extractive metallurgist differ from a civil engineer in that they require information related to ease of breakage and any subsequent liberation of any desirable components of a rock matrix.

1.1 Comminution
Comminution processes are linked closely to liberation and involve the size reduction needed to produce a suitable product for further concentration processes. Comminution methods are described by a variety of different terms, essentially dependent upon the size of their products. The major categories in the comminution process are blasting, crushing and grinding.

1.1.1 Cost
The costs involved in comminution are high as the processes are very energy intensive compared to other stages of mineral beneficiation. It has been estimated that the cost of comminution can range from 40% to 70% of the total mineral process operation costs [Walkiewicz et al 1991, Wills 1992] and that, at best, comminution is only 1% efficient with the majority of energy input being lost in the form of heat.

Comminution processes are very physically demanding on equipment and the cost of regular maintenance is high with the need for new mill liners and grinding media. Mill maintenance requires plant down time, which is also a costly factor.

1.1.2 Sliming
Sliming occurs as a result over overgrinding, an effect that leads to the production of untreatable fines which can subsequently be lost to the tailings. The presence of slimes within a process circuit can also have a detrimental effect on additional downstream processes. The removal of fine material from a process adds cost and it is therefore desirable to keep slimes to a minimum.

That is 700M from top to bottom. And I am told that the mine goes a further 450M below that level.

So I think you will agree that that is one big ass hole.

Dr Rock

The physical and mechanical properties of rock can be measured by a variety of standard tests, and studies have shown that there should be a fundamental connection between breakage in comminution and rock ‘strength’. The current study aims to develop the Ring-loaded strength (RLS) disc test, used as an industry standard for the characterisation of brittle ceramics, for determination of comminution behaviour from borehole core samples. The test procedure is simple, reproducible and can yield 250 separate measurements from a 1-metre length of drill core. The 19mm diameter of the test specimens has allowed for the re-coring of explorations drill cores and hence provided additional valuable information.

An examination of the mode of fracture using Thermal Stress Analysis and a high-speed camera has shown that the RLS disc test is tensile in nature and therefore a good indicator of the grinding characteristics of an ore due to the tensile based regimes that are present during comminution processes.

A comparison of the RLS to the Mode I fracture toughness obtained from the Chevron Bend test has shown that a significant positive linear relationship exists between the two parameters. It has been found that the RLS can be used confidently to predict the Mode I fracture toughness across a range of strengths and textures. A similar comparison of the RLS to the Bond Work Index has shown that for fine and medium grained samples where no flaws are present the correlation between the two parameters is highly positive.

The Tomb is my PhD thesis that I did in less than three years, aren’t I a clever chap. Truth be told I could probably have have done it in just over two years but I was enjoying the muck about environment, and the funding

The title of my thesis is a nice and slick, roll of the tongue one, Ready?

Are you sure?

OK…….

The Use of the Ring-loaded Disc Test for the Prediction of Rock Comminution Behaviour

Now that buggers my anonymity as anyone could easily track my ass down, as there is only one thesis of that name in the whole world. So there you go.

Wanna see the abstract? OK here you go……Read it and weep

Well this is the inaugural post on eRocks, the site dedicated to all things rock and mineral related, with maybe the odd bit of massive machines and big big holes.

If you are here expecting to read about Black Sabbath, Motorhead and other heavy rock music stuff you are going to be shit out of luck my friend.

So who or what is eRocks?

eRocks is presented by yours truly, a former rock crushing student who moved on to study rock breakage for a good number of years. Those time breaking rocks were indeed a good laugh. Along the way I got to skank two free trips to Australia and got to drink a lot of beer as a good friend did his research for a large continental lager company, ahhh Fridays were fun.

So what am I going to ramble about, well for the true rock crushing lovers (there must be 1 or 2??) out there I will be slowly putting my tomb of wisdom online, so the world can read my thesis. Most people theses just gather dust, I would like to change that. I will maybe get a few rock related buddies to talk about their mining exploits too.

If I can work out how to use a scanner I will get some of the pictures I have up online, nope not the rude ones, but the ones with really big holes in the ground or colossal crushing machines.

So for now, like any good cliff hanger you will have to wait for the next rock musing.

Cheers

Dr Rock