4831621682

97

•*

Iron oxide. fo :

F *%)♦ . 3 wl%)

i

Dmpc on

eral

Iron

>rit !nS)

Fe (6 wl%) * (2wt°,

Figurę 4.5 Lead, zinc and iron bearing minerał phases in the stndied calamine

tailings.

During themial treatment, various mineralogical transformations takeplace. Therefore, calamine tailings samples fired at different ternperatures (500, 800 and 1050^:'C) were analyzed by X-ray diffraction. When the fiiing temperaturę was increased to 500^:'C, the gypsum disappeared and transfoimed into anhydiite whereas magnetite (Fe^OT) and hematite (Fe20?) appeared as a result of iron hydroxides dehydration and oxidation reactions (Figurę 4.4). At 800°C, the carbonate (calcite and dolomite) minerals disappeared. The increase in firing temperaturę to 1050°C allowed the formation of augite (Ca(Fe,Mg)Si20r.) and other compounds in both calamine tailings. In addition to anhydiite (CaSCh), hematite, magnetite and ąuartz (SiO:). gehlenite (Ca2Al2Si2C>7) was fonned in the case of CPMT.

Figurę 4.6 displays a summary of the fonned phases during firing process as identified by XRD and ąuantified by TOPAS 4.2 program based on Rietveld analysis. The amounts of anliydrite, hematite and quartz decrease when the temperaturę increases from 800 to 1050^,;,C. This observation may be explained by the decomposition of