King, Steven;
(2025)
A lower energy cost process for the recovery and refining of silver.
Doctoral thesis (Ph.D), UCL (University College London).
Abstract
The current industrial process for the refining of silver from crude lead bullion is characterized by high energy consumption, high labour requirements, and unrealized opportunities for recycling of key reagents. Acknowledgement of the limitations of the existing process prompted the examination of cleaner, lower cost, more energy efficient alternatives. During the project, a new silver-refining process has been developed under my supervision, at Britannia Refined Metals. The new process addresses these concerns and having secured a favourable business case is scheduled to be constructed as a demonstration plant. The redesigned dezincing unit demonstrates dezincing kinetics 44% greater than the original unit, as well as a higher purity and recovery efficiency of zinc. The new Britannia Silver Process has been operated as a ¼ scale experimental facility to examine all aspects of the new operation and its integration into larger full-scale plant. The extended operation demonstrated a 37% reduction in energy usage and a 31% reduction in carbon footprint, as assessed at Scope 1 resolution, compared to the original process, per unit of produced silver at equal or better purity. Initial work examined the morphologies encountered in crystallization and confirmed the presence of octahedral and triangular platelet morphologies, as well as faceting of crystal faces. These morphologies were previously only encountered in aqueous systems. The morphologies are consistent with growth in a kinetically controlled regime. Subsequent work was carried out to examine the use of inoculant species as a means of modifying silver crystal morphology and achieving further improvements in the Ag % content of final crystals. Of the inoculant species trialled, cadmium produced a significant modification to crystal morphology with silver crystals presenting as long columnar twinned octahedrons. This morphology did not however result in an increase in the final Ag % of the product. The morphology and inoculant work confirmed the ability to generate controlled morphologies and faceting of octahedral crystals as research firsts for molten metal systems.
| Type: | Thesis (Doctoral) |
|---|---|
| Qualification: | Ph.D |
| Title: | A lower energy cost process for the recovery and refining of silver |
| Language: | English |
| UCL classification: | UCL > Provost and Vice Provost Offices > UCL BEAMS UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Engineering Science > Dept of Chemical Engineering UCL |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10211917 |
Archive Staff Only
 |
View Item |
