Mineral processing – Milling
Practical Action
areas of the world for small grinding operations. Over short periods of time humans
can provide a significant amount of power (eg 250 Watts for a few minutes), but this
tails off over time. The most efficient way of harnessing human power is to convert it
to rotary motion.
Health and safety and the working environment
Health and safety precautions within the mining, quarrying and processing industries are of
utmost importance. This is an industry where there are many risks of injury, death or serious
health problems occurring if care is not taken. Many developing countries have regulations
which cover health and safety issues within the mining or quarrying industries and any good
manager will be well aware of their requirements. It is worth bearing in mind also that legal
action can be taken against a company who not comply with the relevant regulations. Below is
a summary of some of the common causes of health risk within a milling plant.
Dust
The most serious long term health threat from mineral processing is that posed by dust inhalation.
During any dry milling process a great deal of dust is produced and it can often be very harmful to
breathe, especially over long periods of time. Common ways of reducing dust in the work area are:
• Minimisation of the generation of dust at the source
• Containment of the generated dust and prevention of its dispersal
• Good selection and siting of dust abatement equipment
• Good handling of the collected dust
There are a number of ways of achieving the above but it is beyond the scope of this brief to
discuss them in any detail. Where dust reduction methods do not achieve the desired results,
personnel working in the area should be provided with respiratory equipment such as dust
masks.
Machinery protection
Rotating machinery is potentially dangerous and hence safety is very important when people
are working near mills. All rotating parts of the machinery which are exposed, and with which
people could come into contact, should be guarded. All shafts, belts, chains, wheels, etc.,
should be protected to avoid accidental contact. All guards should be regularly checked to
make sure they are in place and secure. All electrical equipment should also be correctly
installed with no loose wires, cables or switchgear.
Training for personnel
All personnel working in the area around the mill should be given proper training to ensure
that they are aware of the dangers involved. Such training only takes a short time and can pay
great dividends. Health and safety posters are useful as reminders to workers.
Maintenance of machinery
Regular maintenance of machinery is important not only to ensure reliability and to reduce
running costs but also to minimise the health and safety risks. Before starting any machine, all
moving parts should be inspected to ensure that they will not come loose or fall off during
operation. Be sure that the mill is properly at rest and power switched off before carrying out
any maintenance work.
Adherence to the health and safety standards
Above all, if the health and safety standards are observed properly, then there is little likelihood of
serious problems occurring within the milling plant.
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