engleski

Use of silico-manganese slag for the production of industrial aggregate

Silico-manganese slag is an industrial by-product of manganese production in the former TEF factory, Šibenik, Croatia. The crushing and separation facility has been used to produce industrial aggregate fractions. Test samples were taken from stockpiles of the slag and crushed aggregate fractions deposited in the Crnica area, near Šibenik. Analyses of the mineralogical, chemical, radiological, physical and mechanical properties of the manufactured aggregate were performed in order to determine the composition, possible use in civil engineering, and potentially hazardous effect on the environment. The samples of silico-manganese slag were investigated using X-ray powder diffraction, scanning electron microscopy (associated with an energy dispersive spectrometer), gamma spectrometry and leaching tests. Silico-manganese slag contains a silicate glassy phase with various micro- to nano-crystalline phases, which originated in the reaction with the melt or in subsequent crystallization. These crystalline artificial/synthetic phases include akermanite, pyroxene, cristobalite and ramsdellite, which are the equivalents of minerals originating in high-temperature contact metamorphic areas or in basic volcanic rocks. Nodules or grains of silico-manganese alloy are also identified in the glassy matrix. The potentially hazardous properties of slag may be due to radioactivity or from the release of heavy metals. Tests of radioactivity showed that aggregate is not, globally, dangerous, and tests on the leaching of heavy metals gave values lower than the maximum permitted values. The results of all the tests performed show that the aggregate can be used for the production of asphalt and concrete, according to the EU standards. This provides a good example of converting waste material from the ferroalloy industry into secondary raw material, as has been described earlier.

silico-manganese slag; industrial aggregate

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