Abstract In the county of Pedra Lavrada - PB, various mineral occurrences of pegmatite are observed with prominence at Alto Dois Irmãos - PB, where quartz, feldspar and mica are mined. The understanding of mineral constituents is fundamental to define their industrial employment and to implement improvements in the beneficiation process. The proposal of this research is the detailed characterization and proof of that part of the ore (quartz) considered waste, presenting low poisoning (Fe2O3) and high silica (SiO2) content, to enable its industrial use. Besides that, to minimize the environmental impact through the reuse of this waste, and to determine the correct utilization of the milling equipment. For the pegmatite characterization, done were density determination tests, mineralogical identification by X-ray diffraction (XRD), chemical analysis by fluorescents X-rays and morphological analysis by scanning electron microscopy (SEM/EDS). Then tests were done for the Work Index (WI) calculous and consequently the empirical determination of the dimensions (LxD) of the pebble mill. The sterile presented a medium density of 2.66g/cm³, majority chemical composition of silicon and oxygen and quartz as the main mineralogical stage, indicating that this material has high purity. The. The Work Index (WI) was 15.9 kwh/t showing that this material can be considered resistant to breaking in the grinding process. The necessary energy to the milling was defined in 11.52 kwh/st, that corresponds to 57.28 HP. This power allowed the mill selection with diammeter and length of 1.83m, that provides the production maximization and the energy saving.

Abstract Ferricyanide Fe(CN) 6 3- is one of the most stable cyanometallic complexes present in the gold mining effluents. This cyanocomplex is hard to degrade by natural attenuation and generates a negative impact on aquatic environments. Although free cyanide (CN-) can be obtained by acidifying the solution, the CN- is lethal for all forms of life. The oxidation of Fe(CN) 6 3- in a typical photocatalitic system was evaluated with the addition of H2O2. To verify the degradation, chemical parameters, such as free cyanide, the formation of ammonia, nitrate, and total iron were analyzed at the end of the process. Different parameters were evaluated to analyze the behavior of the degradation: 1. dark stage adsorption using the catalyst, 2. the TiO2 dosage, 3. Addition of H2O2, 4. UV radiation power (120 and 200W) and finally a test of TiO2 with solar radiation. The photolysis effect from a ferricyanide solution at 100 mg L-1 at alkaline pH 13, showed that the complex studied is highly stable since under UV irradiation conditions (l> 300 nm), a low rate of dissociation was observed. After 24h of irradiation, the cyanocomplex was under 20%, whereas degradations up to 70% were obtained in a heterogeneous photocatalysis system with TiO2. The best result was achieved with the H2O2 and TiO2 photocatalytic system, and the stoichiometric concentration was about 2.5 times less than the peroxide used in the gold mining industry, reaching 83% degradation. The photocatalytic process obtained less toxic byproducts than the original synthetic ferricyanide used as mining wastewater.