TECHNOLOGICAL INNOVATIONS AND NEW PRODUCTS OBTAINED FROM A VIRTUOSOS MANAGEMENT OF MINING WASTE

The mining industry (raw materials production and technologies connected to exploitation and dressing plants) is one of the most important for Italian economy The exploitation works, and the consequent waste production, represent an evident hazard for the population, as well as an important environmental and landscape impact for touristic areas. For those reasons a systematic reuse of the rock waste, as secondary raw materials (SRM), should be essential. To justify the construction of new treatment plants it is important to guarantee: a sufficient quantity of waste/resources, the constancy of their supply and the convenience of the transport system. An interesting example, connected to quarry waste valorisation as SRM, is the one of Montorfano and Baveno granite quarry disposal sites (Lake District, VCO – NE Piedmont and some analogue samples concerning Gruppo Minerali Maffei spa (GMM spa). The excavation technique produced, during the past, a huge amount of wastes, stocked on the lower hill side of the massifs. In 1995 a primary Italian company (Gruppo Minerali Maffei spa) invested in granite quarry waste valorisation as SRM. The technical principle and the project planning for such a recovery (dressing plant project) is based on physical-chemical characteristics of the rocks and on the quantity of waste to be treated and valorised (BOZZOLA ET AL., 1995). The new exploitation of the dumped materials is useful for the production, by specific mineral dressing treatment (crushing, sieving, magnetic separation, etc…) of SRM for ceramic industry (GP – Grès Porcelain stoneware production) (DINO ET AL., 2005). The main product coming from Montorfano quarry dumps (waste represented by 33% quartz and 62% feldspar) is F60P: 60% of feldspar, mostly K-feldspar, whose production is about 140.000 t/year. The waste produced during the enrichment phase (powder granite, ferromagnetic minerals, etc..) are also treated to obtain by-products which are used in other applications. In fact to the F60P production, different by-products have to be added, commercially known as: SNS - sand (as pre-mix for building uses), NGA - coarse black sand (used for industrial sandblast), SF - wet feldspar (for ceramic industry) and SF100 and SF200 (used as filler in cement industries). The total amount of the by-products is about 70.000 t/year. Nowadays, this is an interesting economic reality with a subsequent save in the raw material costs. In order to guarantee the highest safety in the superposed yards and the stability of the quarry fronts, the material layer is depleted exploited from the top to the base of the whole volume. The same Company (GMM spa) is also involved in different kind of mineral waste valorisation. The paper wants to show interesting examples concerning waste recovery in order to let industrial companies, Public Administrations and citizen know that it is possible to treat and valorise waste with economic and environmental benefits (waste is a resource for the future).