During the late-1980s crawler-mounted crusher units established
their position in the aggregates industry. Between 1986 and 1994
about 700 units were delivered to customers all over the world for
surface operations, mainly in Scandinavia and central Europe.
The crawler-mounted units are popular among smaller crushing
operators because they are versatile and easy to move between
sites. In large quarries the greatest benefit is obtained by
combining a primary crawler-mounted crusher unit with mobile
belt conveyors which eliminates the need for costly haulage by
dump truck. Savings of up to 40 per cent in production costs prior
to secondary crushing have been achieved. Today the environmental aspect in quarrying is assuming ever
greater importance. Besides being costly the dump trucks are also
the major source of dust and exhaust fumes within a quarry. A
complete face crushing system consisting of a crawler-mounted
crusher unit and mobile belt conveyors can be electrically driven
and can be equipped with dust encapsulation and dust collectors. A mobile crushing unit is not a new idea. From the mid-1950s
onwards the mobile and self-propelled units have been built
equipped with crawlers, tyres or walking mechanisms, with
weights usually of 500-1000 t. Due to their massive size these
unit are not mobile in the same way as the today's mobile units. It
is not feasible to move them more than a few times a year unlike
today's fully mobile units which are often relocated once an hour.
This means that the massive units can not continuously follow the
production face and their loading always requires a certain
amount of haulage. Today the mining industry is facing new challenges. With low
mineral prices and high labour costs, increasing productivity is
essential for survival. New standards are also being set for the
labour safety and the environment. Large research programs have
been launched to meet these challenges. However, technology
which can partly solve these problems already exist and is only
waiting to be introduced into underground applications as well - the mobile crushing unit followed by belt conveying. As in
surface operations the elimination of truck haulage also brings
considerable savings in operating costs in underground mines and
reduces the amount of dust and exhaust gases generated. An
additional benefit especially in underground applications is
improved safety. In an underground mine most accidents are
caused by moving vehicles.