Experimental Studies of the Effects of Anode Composition and Process Parameters on Anode Slime Adhesion and Cathode Copp
- PDF / 4,738,511 Bytes
- 14 Pages / 593.972 x 792 pts Page_size
- 41 Downloads / 223 Views
ANODES used in copper electrorefining come from smelters and the existence of impurities in copper melt leads to inclusion formation in grain boundaries within copper anodes.[1] Some of these inclusion particles are soluble and the impurities inside are dissolved into electrolyte during electrorefining. However, most of the inclusions are refractory and become anode slimes as copper around them dissolves.[1] These anode slime particles can vary in size and density.[1,2] Large and heavy slimes are difficult to transport in flowing electrolyte and usually settle down, but small slimes can suspend in electrolyte and be entrapped in cathode copper, resulting in cathode contamination.[3–5] The mineralogy and structures of inclusions and anode slimes have been studied by researchers. According to Chen and Dutrizac’s work, the major inclusions and phases in anodes are Kupferglimmer structure, Cu2O, Cu2(Se, Te), selenide spheroid, NiO, Group VB WEIZHI ZENG, Graduate Research Assistant, and MICHAEL L. FREE, Professor and Associate Chair, are with the Department of Metallurgical Engineering, University of Utah, Salt Lake City, UT 84108. Contact e-mail: [email protected] SHIJIE WANG, Principal Advisor, is with Rio Tinto Kennecott Utah Copper, Magna, UT 84044. Manuscript submitted April 1, 2016. Article published online June 30, 2016. 3178—VOLUME 47B, OCTOBER 2016
elements-enriched compounds.[6–11] They also indicated that the major phases and structures in anode slimes include (Cu, Ag)2Se, Kupferglimmer structure, lead sulfate, Group VB elements-enriched compounds, euhedral NiO crystals.[6,9–15] Besides, the precipitation of dissolved impurities and its effect on cathode purity has also been studied. Precipitates that are amorphous and have compositions of Bi-As-O and Sb-As-O, are referred to as floating slimes and can cause cathode quality deterioration.[16] Crystalline precipitates that are formed by homogeneous precipitation of arsenic, antimony, and bismuth, can be used to remove dissolved impurities from the electrolytic solution.[17,18] Furthermore, the slime adhesion on the anode is significant for impurity control in electrorefining and some studies on it have been done.[2] In addition, flow studies involving slime particles have been performed by both experiments and simulations.[3–5] In our previous research, the sintering and coalescence of slime particles and its effects on anode slime adhesion and cathode purity were studied.[2] Significant findings can be summarized[2]: the sizes of slime particles can be increased by their sintering/coalescence; anode slime adhesion increases from room temperature to a peak adhesion temperature [the peak adhesion temperatures are around 333.15 K (60 °C) for most anodes] and then decreases as cell temperature goes up further, due to the effects of slime particle sintering/coalescence; METALLURGICAL AND MATERIALS TRANSACTIONS B
slime particles tend to fall off the anode after the peak adhesion temperature because of their larger and larger sizes (these slime particles are generally larger
Data Loading...
