Victor Vazquez

Detoxification of cyanide using titanium dioxide and hydrocyclone sparger with chlorine dioxide

Abstract The extraction of gold and silver from minerals and concentrates with cyanide is an important hydrometallurgy process that has been studied for more than 120 years. This technology, which consists of the dissolutions of the precious metals in cyanide solutions, followed by the recovery of the values by cementation, activated carbon or ion exchange resin. Most of the wastes in the industrial effluents’ milling are known to contain high contents of free cyanide as well as metallic cyanide complexes, which give them a high degree of toxicity. Appropriate methods for the treatment of cyanide solutions include cyanide destruction by oxidation using a photoelectrocatalytic detoxification technique with titanium dioxide microelectrodes. This is one of the most innovative ways for the treatment of wastewater containing cyanide. Another is the use of chlorine dioxide (ClO2) with a gas-sparged hydrocyclone as the reactor. The results show that photodegradation of cyanide was 93% in 30 minutes using a 450 W halogen lamp, and in the case of ClO2 the destruction of cyanides was 99% in 1 minute. In both cases, excellent performances can be achieved with the high capacity of these technologies.

Synthesis and characterisation of strontium hexaferrite using an electrocoagulation by-product

Strontium ferrite (SrFe12O19) was synthesised in a solid phase reaction by applying the conventional ceramic method. The precursor powder, containing magnetic iron species generated by the electrocoagulation technique, was allowed to react with strontium carbonate in the solid phase. The molar ratio of the precursor to strontium carbonate was maintained at 12:1 (Fe:Sr), yielding strontium ferrite (SrFe12O19). The electrocoagulation sludge generated was characterised by X-ray diffraction, scanning electron microscopy and vibrating sample magnetometry. The strontium ferrite obtained was characterised by X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, thermogravimetric analysis, differential thermal analysis and vibrating sample magnetometry. The combined results of these analyses showed that the strontium ferrite obtained was of excellent quality with excellent magnetic properties.