Comminution of amethyst quartz waste for coarse and fine aggregatess

In the northern region of Brazil, enormous amethyst quartz waste is generated in mining, currently with no final destination, being stored without commercial value. However, it can be used to produce artificial aggregates, aiming to provide a solution to the storage problem of this material. To reduce the waste, crushing and grinding were used, investigating the factors influencing comminution, such as mineralogical properties and size settings, filling, speed and grinding time. Fragmentation was carried out on a laboratory-scale using a jaw crusher and ball mill. The factors in crushing depend on the gap and set, constants, while in grinding, with constant critical speed, the filling factor, the balls:sample ratio and grinding times were considered variables. The fineness modulus for fine aggregates was used. Based on the particle size distribution of crushing and grinding products, the production of coarse particles in crushing is the highest (75%), being considered as coarse aggregates, while the production of fine particles in grinding is lower (25%) and is considered as fine aggregates. The banded quartzite influences the comminution, more favorable to produce a coarse aggregate. The distribution of particle size shows that within the coarse aggregates, 40% corresponds to G1 gravel. Crushing is determined by the size settings and grinding by the grinding time. For longer grinding times, there is a greater reduction in grain sizes, and for shorter times, the reduction is smaller. The waste could be fed into comminution to produce coarse and fine aggregates for civil construction, achieving a long-term sustainable supply of aggregates in the required quantities.