Anode and method of operating an electrolysis cell

Abstract

The invention relates to an anode for electrowinning process in an electrolytic cell, and the method of operation thereof, having cell walls and a cell bottom for holding an electrolyte and electrolyte feeding means, which anode comprises a hanger bar for supporting the anode, a conducting rod for distributing the current, an anode body having at least partly conductive structure. The anode body allows electrolyte penetration and is at least partly covered by electrocatalytic coating, when in connection with the anode there is arranged a non-conductive element, which is restricted to the conductive structure of the anode body, at least from its one side, and which non-conductive element is arranged at a distance A from the electrolyte surface level, when the non-conductive element provides a means for attaching the anode to the cell.

Description

FIELD OF THE INVENTION[0001]The invention relates to a new kind of anode to be used in electrowinning. The invention also relates to a method of operating an electrolysis cell to be used in the electrowinning of metals.[0002]Electrowinning is a process where a metal dissolved in an electrolyte is reduced on a cathode by means of an electrical current. In electrowinning a current is passed through the anode through the electrolyte solution containing the metal value so that the metal value is extracted as it is deposited in an electroplating process onto the cathode. When an electrical current is applied to the sulfate based electrolysis system, metal is precipitated on the surface of the cathode and water decomposes on the anode where acid and oxygen are formed. Electrowinning takes place in an electrolytic cell that contains a number of anodes and a number of cathodes arranged in an alternating manner. The commercial use of electrowinning requires a large number of cathodes and ano...

AI Technical Summary

Benefits of technology

The technical effects of this patent are: the invention provides an anode for electrowinning that can be easily attached in the electrolytic cell, avoids anode warping, and achieves good mixing of the electrolyte. Additionally, the invention results in more even copper growth on the cathode surface and improves the attachment of the anode in the cell. The use of a flow-through anode with vertical electrolyte feeding also allows for better electrolyte mixing and prevents metal ion concentration gradients. By coating only part of the anode surface with the electrocatalytic coating, the attachment and anchoring of the anode in the cell can be improved.

Problems solved by technology

One type of anode used in electrowinning has been lead based anode, which could have a negative effect on the quality of copper deposited.

One significant disadvantage of using such lead based anodes is that during electrowinning operations small amounts of lead are released from the surface of the anode, which causes the undesirable particulates to be suspended in the electrolyte.

One issue in electrowinning processes is a rather high cell voltage leading to increased energy consumption.

The current density on the cathode side is limited by the quality of the copper deposited, as due to the increased overvoltage on the cathodes more impurities are deposited with increasing current density.

In addition, increasing the current density also leads to an increase in the corrosion rate of lead from lead anodes and consequently more lead circulates in the electrolyte and lead can be included in the cathodes, necessitating an increase in the frequency of cell cleaning to control lead and decreasing the production rate.

Still problems can occur when using cathodes with great length.

When using lead anodes with jumbo cathodes i.e. cathodes of great length, warping of the anode during electrowinning may occur and cause short circuits to the process.

There can be problems especially with the first and last anodes in a cell, with current flowing only on one side of the anode, which may cause warping or creep deformation of the anode.

Warping leads to an increased number of short circuits and a lower current efficiency.

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