Fabrication of re-usable materials based on mineral particulates

There is an increasing need to develop so-called sustainable materials that can be re-used easily and economically, for example, buildings and packaging from consumer items. This requires a radically different approach to material fabrication than is currently used. First, this proposal investigates possible approaches to this by using natural protein materials (peptides) that can be synthesised as molecules to bind particles together to form reversible material structures. These materials change their configuration and hence the forces binding the structure together can be modified by an external trigger. We plan to synthesis peptides that will fabricate new and advanced materials from minerals in the form of tiny particles (kaolonite, copper metal, copper oxides etc) contained in gel networks that the peptides can be formed into. We will investigate the disassembly of the materials by using changes to the chemistry (pH) to cause the peptides to release couplings to their specific mineral surfaces. The research challenges for us are to: synthesise the peptides in sufficient quantities; understand the fundamental science, through atomic force measurement, how they couple with the different minerals; fabricate the new materials structures; produce a mechanical and chemical model for this behaviour. Secondly, the proposal investigates more efficient methods for providing very small particles to be recycled from existing mineral stockpile so that they can be re-used to become into new materials (and thereafter re-used again!). There are significant reserves of these materials that could be reused but the challenge is to separate out the desired mineral from the mixture in an efficient and low cost way. This will be based on recent new capabilities in mineral flotation. This is a process in which a mineral immersed in water is separated according to its surface wettability attaching to the gas bubble and becoming levitated to the surface of the mixture to form a foam that can be removed. We propose a fundamental study aimed at improving the rates of attachment of tiny particles to carrier gas bubbles; the use of a special gas bubble (called an aphron) that has a double layer of surfactant at the gas/liquid interface; and techniques based on varying the washing rate of the foam containing the floated mineral). Again measurement using atomic force microscopy will be required for improving our understanding and development of models. Fundamental measurements will suggest methods for optimising design of separation equipment to significantly enhance the rate of separation for particles that would not normally be recoverable due to their small size. These ideas will be tested practically.