Abstract
	The investigations of the use of several effective oxidants for acid oxidative leaching of chalcopyrite were described in the literature. The use of ozone as gaseous oxidant was published just a few years ago with very hopeful results. Among them, the most important one is that the process is most effective at the room temperature and such way it is not necessary to heat and to cool the large amounts of diluted solutions. 
	The direct oxidative leaching of chalcopyrite in sulphuric acid solutions by using of atmosphere containing ozone was studied in this work with special attention to evaluate the effect of time during which the bubbles containing ozone were in contact with leaching pulp. The copper leaching efficiency increases with liquid column height i.e. with increasing time when the bubbles are in contact with pulp. The same effect can be achieved by increasing of ozone concentration in working atmosphere. Only marginal effect on the copper leaching efficiency was observed with the increasing leaching medium acidity, although at the concentration of 1 M H2SO4 the leaching efficiency was slightly lower in comparison with the other results. This phenomenon was not fully understood yet.
	The results of this study are based on the chalcopyrite leaching experiments using powerful ozonizer  FISCHERŪ and the X-ray diffraction phase analyses as well as the scanning electron microscopy observations.