Abstract:
In this work eight samples of copper ores were obtained from Hofrat Elnahas, Southern Darfur and numbered from 1 to 8. Copper content in all the samples was determined using different analytical techniques including volumetric titration using Iodometry, AA spectrometry,UV-Vis spectrophotometry and XRF spectrometry.Copper ores were then analyzed electrogravimetrically after complete dissolution in acids. With XRF complete analysis of the eight samples was performed. The Cu content in the samples (1-8) was found to be:
5.54%, 4.94%, 2.00%, 1.69%, 1.59%, 1.45%,0.97%and 0.85%, respectively. Several elements, S, Si, Ca, Al, Mg, and Fe, and other minor elements Zn, Mo, Pb, Sr, Zr and U were detected.
The Cu content in the eight samples were determined iodometrically and was found to be 5.43%, 4.04%, 2.02%, 1.63%, 1.46%, 1.44%, 0.92% and 0.86% , respectively.
The UV-Vis spectrophotometric results were, 5.30%, 4.07%, 1.95%, 1.55%, 1.30%, 1.22%, 0.98%, and 0.79%, respectively, and those for AA spectrometry were: 5.33%, 4.00%, 1.85%, 1.45%, 1.40%, 1.30%, 0.91 %and 0.83 %, respectively.
In the present work an electrogravimetric procedure for determination of copper in copper ores was developed.
The conventional electrogravimetric procedure used for determining copper in alloys or Cu sheets was modified. In the treatment of the sample solution a simple filtration step was introduced .The effects of the experimental conditions of the electrolysis of the Cu solution , including pH, temperature, voltage, current and time, were investigated. The dissolution of the ore samples was carried out in a mixture of HNO3 and H2SO4 acids. Whereas HNO3 acted as a buffer solution, H2SO4 kept the solution acidic, so that Fe and other metals above hydrogen in the electromotive series could not be deposited. The pH was 0.5, the voltage was 2.5, and the applied current was 1.0 ampere, temperature was 70ْC, while the solution was moderately stirring for only 90 minutes. Under these conditions the smoothly deposited copper on the platinum cathode was pinkish in color and silky in nature and free from impurities.
The average content of copper in the eight samples(1-8) were 5.42%, 4.05%, 2.01%, 1.64%, 1.47%, 1.44%, 1.08% and 0.86%, respectively .
The developed electrogravimetric procedure for the determination of copper content in copper ores gave results which are in good agreement with those obtained by the titremetric, UV-Vis and XRF methods. It had the advantages of simplicity, low cost, precision, accuracy and free from interferences.