Cake filtration is an integral part of the processes of a whole range
of industries from sewage treatment to pharmaceutical manufacture and it
has been practised for many centuries by apothecaries and dye extractors.
In common with many other unit operations involving particles or
powders it has not been the subject of the kind of intensive research with
which chemical engineers are familiar in the process dynamics field. It
can be seen in the review of the literature that much of the work which has
been done has been of an empirical nature and only in recent years has a
more analytical approach to the investigations been adopted.
It was as a result of the literature review that this research work
began. It seemed quite clear that in order more fully to understand the
phenomena related, not only to filter cakes, but also to the transmission
of force and flow of fluid through fixed beds of particles some technique
was needed to permit a microscopic examination of the interiors of these
beds without disturbing their activity during the relevant operation.
This, therefore, is a report on the development of one such technique
which, it is hoped, will assist in a better understanding of packed bed
phenomena. A wide range of filter cakes and wet and dry compacted beds has been
investigated in order to test the efficacy of the technique. In this
respect the results are not exhaustive but are indicative· of a general trend
in the structure of the·various beds, particularly filter cakes.
There is room for much more work to be done and some areas where it is
felt advances can be made are indicated in a later section.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.