The immobilisation of inorganic pollutants in fly-ash and other waste components

[摘要] ENGLISH ABSTRACT: This project involves the use of fly-ash and its pozzolanic activity to study the immobilisation of heavy metals. By using a waste to treat other waste the cost of treatment can be reduced significantly and in some cases products suitable for applications such as pre-formed building materials, road construction, landfilling, etc. can also be produced.Results from this study showed that products with yield strengths in excess of 18 MPa can be produced, depending on the additive and amount of additive used. These results were obtained with under atmospheric conditions and with material or product additions never exceeding 20% in total.The reaction products of the pozzolanic reaction were similar to the products of the cement hydration reactions, thus showing that fly-ash has the potential of replacing Portland cement in many of the solidification and stabilisation applications that are currently used in practice, with the added advantage that waste is being treated and that lower production costs are being obtained.The fly-ash matrices were also successful in the immobalisation of not only the heavy metals present in fly-ash, but also the metals present in spent catalysts, other waste products and the nickel present in wastewater. These immobalisation results can possibly be improved if more work is done on refining the conditions of the system.This project, although only a small contirbution to this emerging field of research, addresses many of the aspects that are often reserched. It refers to possible immobilisation mechanisms and it addresses the immobalisation of solid pollutants, something that is, reasonably novel, since waste water has been considered to be more of a hazard in the past and is something that needs to be rectified. Finally the project shows that much work still needs to be conducted before the immobilisation techniques and mechanisms of all the metals in this system are fully understood.

[发布机构] Stellenbosch University