Crushers and
Screens
Product
focus
This restored 19th century waterwheel and
tin stamps at Geevor Tin Mine in Cornwall,
England, were used for breaking tin ore.
From chunk to riches
Compiled and edited by Benjamin Brits
Documented back to 40 BCE, the crushing and breaking of rock, ore, and minerals is one of the oldest processes
undertaken by man, preceding its partner — screening — by centuries. Today, we find strings of crushers feeding
screening machines as one, and in mobile form.
T
he term ‘crushing’ refers to the process of
reducing raw materials to a functional ‘next
form’; that is, crushing large rocks to form
smaller rocks, gravel, or sand. ‘Screening’ refers to
the process that separates material into different
grades based on particle size. Crushing and
sorting (or screening) have always been essential
processes in the treatment of rocks and minerals
to prepare them for various further uses.
At its core, the crushing and screening
process turns chunks of raw material into
valuable — and sometimes extremely valuable
— end products, such as precious metals.
Over the centuries, individuals, families, and,
more recently, large corporates have become
exceptionally wealthy due to the crushing and
screening process.
Historically, crushing and screening were
separate processes, not as we see them
today working in tandem (depending on
the application). The first industrial-type
screening date from the gold rush of the
1850s. Although the mining of minerals dates
back much further than this, it was typically
the search for nuggets or larger sized minerals
that could be hand-picked. The first screens
were made from wood or grass woven into
a mesh-like form. Steel wire-woven screens
only entered the picture in the 1820s and were
primarily used in agriculture.
From early hand processing thousands of
years ago to modernised mechanisation, the
process of crushing and screening has become
essential to many industries today, from scientific
research and development to infrastructure and
recycling, particularly because of the volumes of
end product that are required, or that need to be
moved or processed.
Muscle power went a long way
The earliest crushers were hand-held stones
whose weight, used against a stone anvil,
provided a boost to the manual process. Quern-
stones and mortars are examples of this type
of hand-grinding crushing device, similar
to the mortar and pestle we still use in our
homes today. Throughout most of industrial
history, until the early 1800s, the majority of
ore crushing and sizing/screening was done
by hand, and the greater part of crushing
was driven by muscle power, with the initial
application of force concentrated in the tip of a
pick or sledgehammer-driven bit or chisel.
If hand crushing was impractical, a heavy
rock or weight would be raised by men or
animals using a rope, and allowed to drop onto
the rock to be crushed. Use of the trip hammer
— a waterwheel-powered hammer raised by a
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