E. Godočíková

Mechanochemical route for sulphide nanoparticles preparation

Abstract Well-crystallized ZnS, CdS and PbS nanoparticles were successfully synthesized by the mechanochemical route from the corresponding acetates and Na 2 S. X-ray powder diffraction and scanning electron microscopy were used to characterize the as-obtained products. The SEM measurements show the aggregates of small nanocrystals in which particle sizes of 5–18 nm were estimated by Scherrers formula. Simple flow chart of the preparation of sulphide nanoparticles was presented.

Structural and temperature sensitivity of the chloride leaching of copper, lead and zinc from a mechanically activated complex sulphide

Abstract The hydrometallurgical processing of complex concentrates represents an ecologically attractive alternative with respect to classical pyrometallurgical technologies. The structural and temperature sensitivity of chloride leaching of copper, lead and zinc from a complex CuPbZn sulphide concentrate of Slovak origin which was mechanically activated in an attritor was studied. Mechanical activation influences the leaching kinetics and the recoveries of copper and zinc, but only the leaching kinetics of lead. It has been found that the reaction is sensitive to the increase in surface area and decrease in crystalline phase content of the studied concentrate due to mechanical activation. The demonstration of a linear relationship shows the structural sensitivity of the reaction. For copper and zinc, the reaction temperature sensitivity for the optimum mechanically activated sample in the temperature region 323–363 K showed a change in the rate-determining step at 343 K. Lead showed no change in mechanism over this temperature range. The suggested order of structural sensitivity galena>chalcopyrite>sphalerite is in accordance with their temperature sensitivity.

Mechanochemical transformations and reactivity in copper sulphides

Mechanochemical transformations of copper sulphides were induced by processing in a Fritsch Pulverisette 6 planetary mill. The main changes during high-energy milling are the phase transformations of the djurleite Cu1.94S which is the main phase in a starting material. Digenite, which is in fact a group of copper sulphides (Cu1.80S, Cu1.765S and Cu9−xS5, respectively) together with chalcocite (Cu1.96S and Cu2S, respectively) are the main phases among the mechanochemical products. The reactivity of the products is compared to their physico-chemical transformations during high energy milling.

Preparation of Nanocrystalline Copper and Copper Silicon Sulphide by Mechanochemical Route

The composition and properties of powders prepared by high-energy milling of copper sulphides with silicon have been studied by methods of X-ray diffractometry and surface area measurement. The combination of several methods was utilized to develop a coherent picture of the process. The overall process of mechano-chemical transformations in copper sulphide-silicon system proceeds via complicated mechanism with several overlapping steps. Phase transformations in copper sulphide phases, the formation of elemetal nanocopper with X-ray determined particle size of 23 nm and creation of ternary sulphide Cu8SiS6 with anomalous surface area values are the main products of the mechanochemical reaction.

Mechanochemical preparation of metal/sulphide nanocomposite particles

The mechanochemical reduction of stibnite (Sb2S3), copper sulphide (Cu2S), galena (PbS) and auripigment (As2S3) with elemental Fe has been studied. Metallic Sb, Cu and Pb are obtained due to the reducing power of iron. The metal/sulphide nanocomposite particles have been characterised by XRD, SEM and TEM methods. The reduction processes are very straightforward and fast and can be carried out at ambient temperature.