Education of the republic of uzbekistan tashkent state technical university named after islam karimov

Keywords: 
zinc, ferrite, silicate, vital, oxide, lime, thermodynamics, beneficiation, roasting, 
charge, Gibbs energy, free energy. 
INTRODUCTION. 
The zinc oxide obtained in the roasting process interacts with iron 
oxide (Fe
2
O
3
), forming zinc metaferrite. 
ZnO + Fe
2
O
3 
= ZnO

Fe
2
O
3
(1) 
At a temperature of 650 °C, the reaction proceeds very intensively. Therefore, carrying 
out firing at a temperature of 700-750 °C does not exclude ferrite formation. It does not dissolve 
in weak sulfuric acid and remains in the residue from the leaching of the roasted concentrate, 
which leads to direct losses of zinc[1-3]. 
Sulfurous and sulfuric anhydrides relatively quickly destroy zinc ferrites. Therefore, 
under conditions of sulfating roasting, the requirements for combating their formation are most 
effective. 
When firing in a fluidized bed, due to the high concentration of sulfur dioxide and weak 
contact between the solid particles of the concentrate, separated by gas, the cinder is obtained 
with increased content of water-soluble zinc [2,4]. 
Ferrite formation during roasting is most efficiently prevented by obtaining zinc 
concentrates with a minimum iron content [5]. 
Silicates decomposed by sulfuric acid are the source of the appearance of colloidal silica 
in the pulp during leaching of roasted zinc concentrates, arise mainly in the process of roasting of 
concentrates as a result of the interaction of silica-containing nonmetallic minerals with heavy 
metal oxides formed during roasting of sulfides. The formation of silicates during firing in a 
fluidized bed at a temperature of 950 °C is at least 60% [4]. 
The degree of formation of silicates increases with an increase in temperature and a 
decrease in the size of the reacting substances. Thus, silica, like iron, is a harmful impurity in 
zinc concentrates, so their content should be minimal. 
In our opinion, a cardinal solution to this problem can be the preliminary binding of oxide 
compounds of iron and silicon into vital compounds and the prevention of their interaction with 
zinc oxide [6].