Project Summary and Introduction to this Site.
SummarySite Features
This project (coded SEFAP 193) investigated the potential for metal extraction and recovery from glaze/slip/casting waste produced by the ceramic industry in Staffordshire. The project was supported by a grant from Staffordshire Environmental Fund on behalf of the Landfill Tax Credit Scheme.
Work on this project was carried out in the 2000 – 2001 period, and it was expected that this report would be published in 2002. However, the Centre for Environmental Technology at Staffordshire University that had originally undertaken the project ceased to exist as a unit shortly after the end of the project, and relevant staff left the University or were redeployed. As a result, the project report has been delayed until now.
To give the report some currency, this project website has been constructed to “house”and promote the report. The site features a community forum and a set of relevant web resources, and it is hoped that this will provide a stimulus for discussion and information exchange among interested parties within the Staffordshire ceramic community, and elsewhere.
Specifically, this project …
• Investigated the current (2000 – 2002) solid waste disposal practices operated by the major ceramic producers, and took a view about the application of any such technology.
• Assessed the most significant ceramic waste streams, in terms of category of waste and composition, and optimisation of metal extraction rate and efficiency.
• Provided some information about the economic potential for target metal removal.
A total of 14 local ceramics companies were contacted in the course of this project, and waste samples were analysed from 13 of these. Many local ceramic manufacturers are now beginning to develop environmental policies along with awareness for the need to recover what was once considered waste and reuse it. However from the extraction with water and ease with which certain ions leached out into solution we can see that there are environmental concerns with the landfilling of ceramic wastes that are not fully understood.
Zinc was identified as the metal of main interest in the waste samples. Although not all samples contained zinc, those that did so contained amounts that were significant and opened up the possibility of recovery. The wastes from colour manufacturers also contained quantities of other valuable metals such as chromium, cobalt and manganese. Interestingly despite pressure from environmental legislation, lead was found to be present in several of the wastes.
The removal of the majority of zinc from the wastes was relatively easy, requiring sufficient acid to keep the solution at pH at 3 or below. The efficiency of removal of zinc was unaffected by scaling up the experiments to small pilot-plant scale.
The concentration of zinc extracted was insufficient to make precipitation viable i.e. the final solutions from acid extraction contained 5-8g/L of zinc. It would require a ten-fold increase to make precipitation economically viable. The nature of the waste was such that it was not possible to simply increase acid concentration and decrease volume.
Other components of the waste were co-extracted with zinc, and these precipitated with the zinc with the addition of hydroxide. Thus if a waste recovery operation required pure zinc hydroxide, the precipitate would require further treatment.
Acknowledgements.
We gratefully acknowledge the support and patience afforded by Staffordshire Environmental Fund that made this study possible. We would also like to thank the companies involved for their time and for providing waste samples. Special thanks are due to Armitage Shanks for providing invaluable advice and support at each stage of the project.
back to topSite Features.
- This site features the full text of the project report in WORD or PDF
format - Please visit the download page to obtain
a copy.
- We also feature a selection of resources and
links which we hope will be of use to site visitors, especially those
from the local ceramic community.
- We also have an online forum for you to air any views you have on this site.