2024 - Sustainable Industrial Processing Summit
SIPS 2024 Volume 14. Intl. Symp on Advanced Materials, Manufacturing, Magnesium and Aluminum
| Editors: | F. Kongoli, F. Marquis, N. Chikhradze, T. Prikhna, E. Suhir, Y. Yang |
| Publisher: | Flogen Star OUTREACH |
| Publication Year: | 2024 |
| Pages: | 258 pages |
| ISBN: | 978-1-998384-30-3 (CD) |
| ISSN: | 2291-1227 (Metals and Materials Processing in a Clean Environment Series) |
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STUDY OF ELECTROLYTIC PURIFICATION OF WASTEWATER FROM COPPER IONS USING BOTH FLAT STEEL CATHODES AND CATHODES MADE OF CARBON-GRAFITE MATERIALS
Tsisana Gagnidze1;1IVANE JAVAKHISHVILI TBILISI STATE UNIVERSITY, Tbilisi, Georgia;
Type of Paper: Regular
Id Paper: 354
Topic: 43
Abstract:
During the processing of polymetallic ores, a large amount of waste is formed containing heavy metal sulphides, which, as a result of natural leaching, enter the mine and mine wastewater, polluting the environment. The toxic effect of heavy metals on living organisms leads to disruption of enzymatic reactions .
This work is devoted to the study of the possibility of electrolytic purification of wastewater, primarily from copper (II) ions, which are characterized by high toxicity and are one of the main sources of pollution of the hydrosphere. The electrolysis method ensures minimal costs for their further processing and creates the possibility of implementing resource-saving and low-waste processes.
However, the difficulties of cleaning dilute solutions from heavy metal ions by means of electrodeposition are associated with the low speed of the process and the presence of side reactions. Therefore, the development of the method and the creation of effective designs of industrial devices that allow the intensification of the electrolysis process open up the prospect of using the method to extract metals from dilute solutions.
To extract copper with a high degree and high current yield from dilute solutions, we have developed a special design of an reactor with a high hydrodynamic regime [1].
In the reactorr, the radially arranged electrodes have the shape of a Leprechaun. In the center of the electrolyzer, there is a mechanical stirrer of an original shape, which directs the flow of liquid between the electrodes with a strong centrifugal force. The shape of the electrodes maintains the flow of liquid in a circular motion along the wall of the cylindrical reactor. The reactor operates on the hydrocyclone principle and the flow of liquid moving at high speed along the electrodes removes the cathode product, which, after passing through the corresponding windows of the reactor, is collected at the bottom of the conical body (collector), from where it is periodically unloaded. The reactor achieved a significant improvement in the intensity of forced convection and a solution to the problem of removing copper powder from flat stainless steel cathodes.
Large-scale laboratory tests have shown that a cascade arrangement of two such reactors, one of which operates at high current values (I-15A, Cu-1.08g/l, Q-85.2%, ɳ-62.1%, W-3800 kW∙hour/t), and the other at lower ones (I-4.0A, , Cu-0.16g/l, Q-68.6%, ɳ-27.5%, W-7339 kW∙hour/t), allows a total extraction of up to 95.4% of copper from quarry water with a current efficiency of 54.9% with a residual copper concentration in the solution of 0.05 g/l and a specific energy consumption of 4175 kW∙hour/t, which corresponds to 5-10% of the cost of copper.
As the research results showed, the bottleneck in the design of the above reactor with flat steel electrodes is the process of extracting copper with a concentration of Cu≤0.16 g/l (second reactor).
In order to intensify the reactor process at very low copper concentrations in solution Cu≤0.16 g/l, we designed a new electrochemical reactor, in the center of which a volumetric-porous flow-through cathode block with a mechanical stirrer is located [2]. The cathode block consists of perforated cylindrical graphite on which a carbon material with high physical, chemical and operational properties is wrapped along its entire height. The mechanical stirrer facilitates the free passage of liquid through the pores of the carbon-graphite material, thereby reducing the hydrodynamic resistance of the solution flow and increasing the rate of metal deposition by reducing the cathodic polarization in the thickness of the carbon material.
It has been experimentally established that when using an electrolyzer with flat steel cathodes from dilute solutions (Cu≤0.16 g/l), copper extraction in 1 hour is 19.6% with an extraction rate of 2.22 g/h˖m2, while in an electrolyzer with cathodes made of carbon-graphite materials, all other things being equal, it is 83-84% with an extraction rate of 15.1 g/h˖m2, as a result of which the intensity of the process increases by 6.8 times.
It is important to note that electrolytic copper can be extracted from the surface of a carbonaceous material by repeated chemical or electrochemical regeneration without changing its electrode properties.