When looking at a milling system you should always start with what are the big miners doing in this field and can their methods be adapted to the scale you wish to work at.
Pretty well all major mines start off with freshly mined rock laid out on the ROM(run of mine) pad next to the milling circuit.
Any oversize rocks are put aside for a specialist team to reduce in size enough that they can be handled by the milling circuit.
Usually the rocks are fed through a jaw crusher followed by a gyrator crusher and then a rod or ball mill, size screening is carried out between stages.
Smaller scale operators with reduced throughput often run jaw crushers of various settings in series and eliminate the gyratory crusher.
Prospectors with a lot of largish samples will often run a jaw crusher followed by a hammer type mill, this needs to be run dry and will generate a lot of dust.
Prospectors with smaller sized and lesser numbered samples often run a jaw crusher set to coarse milling and then use a jackhammer with a flat plate welded to a cut off piece of drilling steel to finely crush the sample in a piece of steel pipe with a flat plate welded across the bottom.
This generates much less dust than any rotary mill but dust will still be generated.
The only way to minimise dust is by using a ball mill or similar for the final comminution stage, jaw crushers can be used on wet feed but not rotary mills such as hammer type mills.
Deano
