The Research On Synthesis And Formation Heat Of The Chrysocolla

Abstract:Chrysocolla is one of the main copper oxide mines. However, due to insufficient thermodynamic data of Chrysocolla, there is no research work on flotation and leaching conditions for it from thermodynamic view. Therefore, in this paper, the thermodynamic properties of Chrysocolla are carried out to establish a theoretical foundation for chrysocolla flotation and leaching. The main research work in this paper is obtaining the basis thermodynamic data of the chrysocolla.It is difficult to obtain the high purity chrysocolla in nature, so, firstly, a detailed study on synthetizing the high-purity chrysocolla is carried out. And the best conditions for synthetizing chrysocolla are as follows:1) The conditions for recursor preparation:Droping Na2Si03solution into Cu(NO3)2solution slowly at the temperature of35℃and the reaction was stirred for about4hours;2) The conditions for hydrothermal reaction:the hydrothermal reaction lasted about6hours at120℃in a mixed solvent, which mixed by40ml (0.1mol/L) Na2Si03and20ml (0.1mol/L) NaOH. The dropping order of the reactants in the precursor preparation stage and the extra mineralization agent in hydrothermal synthesis stage are play a key role for formating chrysocolla. The structure and polymorph of the sky blue synthetic product were characterized by infrared spectroscopy and X-ray diffraction spectrometer, and the composition of the product was studied by chemical analysis. The results showed that the synthesized product in terms of appearance, structure, crystal, ingredient is the same as the chrysocolla reported in the literature,indicating that the product obtained is chrysocolla.In this paper, the experimental program for determining the heat formation of chrysocolla was obtained by thermochemical cycle establishment. And the results are as follows:1) The dissolving conditions for SiO2, CuO and Chrysocolla in HF solution were obatined:SiO2particle size should be smaller than600mesh; the concentration of the HF solution should be higher than26.58%; the amount of HF solution should be excessive10times. Powdery Chrysocolla samples and CuO can be completely dissolved in HF solution under the conditions obtained above.2) The experiment was carried out in a improved μRC calorimeter, which was got by changing the glass reaction vial into a teflon vial. And the energy equivalent calorimeter (K=1.1322KJ/mol) was calibrated by the standard substance KC1.3) The standard molar reaction heat of SiO2+CuO mixture and chrysocolla samples was measured by the fluorine calorimeter respectively,then,was calculated base on the Gates Law and is-1089.91kJ/mol.