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Iron recovery from the waste generated during the cutting of granite
Junca, E.; de Oliveira, J.R.; Espinosa, D.C.R. & Tenório, J.A.S.
Abstract
Metallic iron is present in the waste left when
granite blocks are cut. Thus, the purpose of this study was
to characterize this waste using chemical and particle size
analyses. To achieve this, X-ray diffraction and scanning
electron microscopy coupled with electron back-scattered
diffraction were used. To find the method with the best
metallic iron recovery from the waste of ornamental rock,
three distinct methods were examined: magnetic separation,
table concentration and cyclone processing. The first
method involved three steps: (1) use of a wet high-intensity
magnetic separator, where only the equipment’s remaining
magnetic field was present; (2) the material from the first
step was then submitted to separation again, this time using
a magnet for rare earth particles; and (3) this material after
two separation processes was finally submitted to ferromagnetic
separation. The second method used a concentration
table set at various inclinations, oscillation
frequencies and wash flow rates. Meanwhile, for the third
method, the cyclone tests, only the water pressure was
varied. After each test, a chemical analysis was performed
to determine the metallic iron present in each sample. The
tests revealed that magnetic separation presents the best
results. Using this technique, a ferrous concentrate with
93 % metallic iron content and a granite concentrate with
only 0.6 % metallic iron were obtained. On the other hand,
in the table concentrator tests, the ferrous concentrate only
had a metallic concentration of 13.6 %. In separation by
the cyclone processing, the product barely contained
metallic iron (7.2 % maximum).
Keywords
Granite waste; Solid waste; Recycling; Waste management
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