Mineral processing – Milling
Practical Action
• The Chilean Edge Mill. Used commonly in Chilean gold ore processing, the edge mill
has two large steel rimmed concrete wheels (these would have been stone in previous
centuries) which roll around a circular concrete track and grind the gold ore beneath
them.
Figure 6: Chilean edge mill
Final product size can be very small and the final size is a function of the time in the
crusher. Grinding is usually carried out wet, the ore being washed in and out of the
circular track by the water.
• The See-Saw Crusher. Very heavy stone or steel ‘see-saw’ crushers are rolled over the
material which is to be crushed with the aid of a lever arm. The material is placed on
a flat stone or steel surface and the product is similar to that from a roller crusher
Figure 7: See-saw crusher
• Other traditional mills include pestle and mortar type mills and stamp mills, amongst many
others.
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