Denis Fletcher Kelsall [1918-1982]

By Helen WolffMay 15th, 2014

Denis Fletcher Kelsall was a chemical engineer. He was Chief of the CSIRO’s Division of Chemical Engineering from 1974-1978, and of its successor, the Division of Mineral Engineering, from 1978-82. During this latter period he was also Chief of the Division of Applied Geomechanics from 1979-81.

He was elected a Fellow of the Australian Academy of Sciences and Engineering in 1976.

Kelsall’s distinguished career commenced in the late 1930s when he graduated from Cambridge with First Class Honours.

After a short period with I.C.I. he volunteered for duties with the Royal Air Force and served as a pilot in coastal command.

After the war he joined the Atomic Energy Establishment at Harwell and was seconded to work on isotope separation techniques at Chalk River, Canada. This was followed by another secondment to the Canadian Bureau of Mines where he Was introduced to the mysteries of mineral separation techniques.

International recognition

Returning to A.E.R.E. at Harwell, he commenced his studies on hydraulic cyclones and he was awarded the 1952 Moulton Medal of the Institution of Chemical Engineers for his first paper on the subject. That institution recognised his scientific worth but, as he often pointed out to aspiring chemical engineers, it would not accept him as an Associate Member at that time due to his lack of experience.

He was later given the 1977 Robert Richards Award of the American Institute of Mining, Metallurgical and Petroleum Engineers, principally for his work on cyclones, the only time this award has been made to a non-American.

In 1953, he left Harwell to work for Rhoanglo Mines Services in Rhodesia (now Zimbabwe) and during the next five years he worked at the Kitwe Laboratories where he gained a deep appreciation of the constraints imposed when working in an industrial environment. During his career at CSIRO he constantly sought to expose the research staff to similar rigours in order to temper their esoteric thoughts with the realities of the commercial world. Whilst in Rhodesia he studied flotation processes to such effect that Professor Aplin, Professor of Metallurgy and Mineral Processing at Pennsylvania State University, has said that this work alone would have also justified the Richards Award.

Early CSIRO study

On joining CSIRO, in 1958, he was put in charge of the Unit Operations Group and was thus responsible for research in a diversity of problems such as non-Newtonian mixing, water desalination, wool dyeing and cheese drying. After his appointment, the character of the Group’s work slowly changed. With the assistance of McAdam, he first developed the cydosizer to enable the determination and isolation of size fractions in the sub-sieve range. This having been accomplished, he turned his attention to studying breakage in grinding mills, the cyclosizer being an essential tool in these investigations. In collaboration with Reid, Stewart, Weller, Restarick and Heyes, he published some 17 papers, the contents of which formed the basis for mathematical models of grinding. These models were subsequently used for in-depth analysis of mineral beneficiation plants throughout Australia by his own team and internationally by many other workers.

In his early years with CSIRO he was expressly forbidden from working in the field of flotation despite his previously demonstrated competence in the area. He did not regard his freedom to study desalination and cheese drying as adequate compensation, and often pondered the somewhat tortuous logic that imposed this constraint on his activities. In 1970, the transfer of some of the staff from the Ore Dressing Section to the Division of Chemical Engineering coincided with the removal of this constraint and flotation studies were combined with the grinding work to produce a more logical research scenario which is now known as diagnostic metallurgy.

Appointed Chief

In 1974, he was appointed Chief of the Division of Chemical Engineering which by that time, was attempting to cover too wide a search field with limited resources, both mental and physical. He countered this by concentrating the research effort in a strictly limited number of fields where achievement was being demonstrated and the work was relevant to the stated aims of the Mineral Research Laboratories. Research in other areas rapidly declined as, to quote one of his many cliches, people got the message’.

The result has been the creation of a highly productive Division, working at the difficult interface between scientific research and industrial application, an achievement recognized both nationally and internationally. Using another cliche from the amateur theatrical field in which Kelsall participated, ‘It will be a difficult act to follow’. In 1979, Dr Kelsall accepted an additional challenge by becoming Chief of a second Division-Applied Geomechanics.

Deterioration in health forced him to relinquish that post in 1981 and thereafter he gave full attention to mineral engineering.

‘Scientific missionary’

In the 1970s, he became an Australian citizen but this action in no way diminished his espousal of the twin advantages of being born in the north of England and
attending ‘The University’, Cambridge being the only one worth considering.

Indeed he remarked to the Duke of Edinburgh during a recent visit that he, Kelsall, regarded his status in Australia as being that of a ‘scientific missionary’. By all accounts His Royal Highness did not smile. However it may be of some consolation to native-born Australians that when talking to ‘Poms’ both here and overseas, he was very much the Australian, deriding warm English beer, south of England accents and parochial British attitudes, with all the vehemence of an Ocker Earls Court expatriate Australian.

He fought against his long illness with the same grim determination that characterised his conflicts with hierarchies, both scientific and institutional. It was unfortunate
that in this, his final battle, as in some of his other fights, the odds against him were too great.


Adapted from a submission by Alan B. Whitehead to CoResearch, CSIRO’s staff newsletter (no. 252, June 1982), p. 2

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