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In-Depth Information
Chapter 4
Waste Rock Behavior at High Pressures:
Dimensioning High Waste Rock Dumps
Currently, the dumps housing waste rock constitute the highest structures ever
built by man, playing an indispensable role during the lifetime of mines. This
chapter presents recent experiences related to the design and operation of very high
waste rock dumps (HWRDs) with special emphasis on the characterization of the
mechanical behavior of certain waste rocks subjected to high confining stresses and
in situ
forced leaching. To achieve this characterization, a large-sized triaxial
apparatus was recently built in Chile, allowing confining pressures of up to 3 MPa to
be applied on samples 1 m in diameter with a maximum particle size of up to 0.2 m
(8”). The waste rock was characterized by means of triaxial compression tests in
drained and undrained paths, as well as in oedometric tests. The results obtained
were used to conceive and dimension HWRDs; adopt dumping strategies; analyze
the possible occurrence of static liquefaction and earthquake effects; and, finally,
facilitate eventual closure of these facilities through appropriate methods.
4.1. Introduction
As the production in many of the world's largest open-pit metallic mines has
increased dramatically, the demand for waste rock dumps of greater capacity has
become high and pressing. Production levels of over 150,000 tons of treated mineral
per day or more than 200,000 tons per day are no longer uncommon and,
consequently, 300,000 tons to more than 400,000 tons of waste rock per day need to
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