Electrodeposition of zinc from sodium zincate/hydroxide electrolytes in a spouted bed electrode
- PDF / 1,109,881 Bytes
- 12 Pages / 612 x 792 pts (letter) Page_size
- 26 Downloads / 189 Views
I. INTRODUCTION AND PREVIOUS INVESTIGATIONS THE electrodeposition of metals from aqueous solutions is an important step in the production of zinc, copper, and other metals. The electrolytic cells used for this purpose are simple and have undergone only minor, evolutionary changes in design and operating practice over the past century. In other areas of electrochemistry, new cell designs have been developed and successfully exploited. A novel cell design that may significantly improve the electrodeposition of zinc is one employing a particulate electrode known as a spouted bed electrode (SBE). Early work on a similar electrode has been described by Scott and Wright,[1] while the application of this electrode to copper electrowinning has been examined by Scott and Wright, Salas-Morales,[2] Robles,[3] and Stancovic and Stankovic,[4] as well as by Salas et al.[5] Since the summer of 1993, research and development on the use of the SBE for zinc electrowinning (from the acid sulfate electrolytes common in the zinc industry) has been carried out at Berkeley in a collaborative effort with PASMINCO, the Australian zinc company.[6,7,8]. More recently, investigations of zinc electrodeposition from alkaline (KOH) electrolytes have been conducted with support from the International Lead-Zinc Research Organization (ILZRO). These latter investigations have been oriented towards the recovery of zinc (and electrolyte) from the spent electrolyte taken from zinc-air batteries.[9] In these studies at Berkeley, much of the experimental work has been carried out using the cell depicted in Figure 1. The cell is shown in front view in the upper half of the figure, and an exploded plan view appears in the lower half. The zinc particles are contained within a 95-mm-wide, 178mm-high (approximately) bed between a current feeder, at V. JIRICNY, Staff Scientist, is with the Institute of Chemical Process Fundamentals, Prague, Czech Republic. A. ROY, Graduate Student, and J.W. EVANS, Professor, are with the Department of Materials Science and Engineering, University of California, Berkeley, CA 94720. Manuscript submitted February 3, 1999. METALLURGICAL AND MATERIALS TRANSACTIONS B
the back of the cell, and a diaphragm separating the particles from an anode compartment containing the anode and anolyte. Within the zinc bed is a draft tube. Catholyte is pumped into the cathode compartment through the bottom and flows up the draft tube, sweeping particles with it. These particles fall out of a spout at the top of the draft tube and land on the top of the bed in the “annular region” on either side of the draft tube. There they descend with other particles forming a slowly moving packed bed until they fall through one of the two gaps at the bottom of the bed and are again swept up the draft tube. With the current feeder connected to the negative side of a DC power supply and the anode to the positive side, current can be passed and, with an appropriate electrolyte in the cathode chamber, zinc can be deposited onto the particles so that they grow from
Data Loading...
