In a conventional settling thickener pulp is introduced into a large tank, solids settle under gravity and clear liquid overflows from the top. The concept of introducing pre-flocculated pulp below the surface into the settling pulp bed was probably first pioneered by the Australian Sugar Research Institute in the 1960’s. It was demonstrated that significantly higher throughputs could be achieved using the principle. Enviro-Clear Inc. was the first company to market a commercial unit incorporating the principle. Whilst working with Delkor Pty Ltd in South Africa I was involved in testing and commissioning of Enviro-Clear units.  Whilst throughputs of up to10 times that of conventional units could be obtained, high flocculant consumption was a drawback. The units were also expensive requiring a separate external deaerator tank and they also suffered from a lack of process control. Sudden increases in underflow density often resulted in the rake mechanism tripping out which usually meant that the unit had to be emptied hosed out and restarted from scratch

Whilst on a flight from Tasmania to Sydney on 5th March 1983 I did a sketch in my diary of an Enviro-Clear thickener then superimposed my high rate thickener concept on it with an inbuilt open deaerator/feedwell flared at the bottom and an inverted cone deflector cone fixed to the rakes to deflect the pulp downwards at an angle of 30 to 45 degrees from the horizontal. The idea was to produce a larger reaction zone.

See the reproduction of the diary page below.

 The diagram from the current Outotec brochure shows the open internal deaerator/feedwell and cone deflector as drawn in my diary sketch. It is these features that have enabled the SUPAFLO other rival high rate thickeners.

In order to test the principle I borrowed a 3.5inch Enviro-clear laboratory test unit and modified it by removing the horizontal deflector plate and replacing it with an inverted cone. The test showed that the concept did work..

I the had a 100mm unit fabricated from clear shinkolite tubing, purchased variable speed Masterflex pumps and did further test work to establish parameters. This design has obviously stood the test of time because the test unit depicted in the current Outotec brochure is identical  to the one I had made in 1983.



The Rum Jungle uranium mine was shut down in 1971 leaving behind a major environmental problem. It was decided that the rehabilitation of the site was necessary to stop the dumped tailings from washing into the nearby river.

Samples of the tailings were laboratory tested in the 100mm unit and a quotation submitted for the supply of 5.5metre diameter Supaflo thickener. In September 1983 a firm order was obtained from the project engineers and a draughtsman was engaged to prepare detailed fabrication drawings of the unit. These were completed in December 1983. The unit was fabricated in Sydney and shipped to Rum Jungle, which is 65kms south of Darwin in early 1984 in a road/rail container. The unit was erected & ready for commissioning in July 1984.


I flew to Darwin on Sunday 29th July 1984 to commission the unit. The following description is taken from a report I wrote subsequently. “ It became apparent that no plant start up was likely before Tuesday or Wednesday so I decided to make a modification to the unit which I had considered as a result of experiments with the 100mm unit.

The deflection cone had been fabricated with a diameter of 700mm whereas the downpipe was 1000mm & the flared section 1400mm. I removed the 2 halves of the cone & took them to an engineering company in Darwin. I had intended to have them enlarged to 1400mm but the boot of my hire car would only accept them at 1200mm so I settled for that.

In order to obtain a pulp injection velocity of around 3 meters per minute the gap between the cone and the flared section was set at 180mm. Feed to the unit commenced on Thursday 2nd August 1984. When the unit filled it was apparent that the sealing between the adjustable weir plates & the shell was unsatisfactory so I drove into Darwin and purchased tubes of silicone sealant and used this to close the gaps.

After further delays the plant was restarted at 5pm on 3rd and was then run continuously until 4am on Saturday 4th August. During this time a bed was established in the unit and clear overflow obtained. Initially the feed to the unit contained 9% solids (design figure 3%) but with continuous operation it came down to 5 to 6% and at this level operation improved considerably. It could be seen through the sight glass that there was a sharp interface between the bed and the clear overflow & the bed was being subjected to a very gently rolling motion. Which is what is required to achieve good flocculation of the incoming feed.

Due to problems in other parts of the plant a shutdown was necessary at 4am. It would be hard to put into words the joy (& relief) that I felt as I drove back to Darwin in the early hours of Saturday morning. My concept worked!!

Since a lengthy shutdown was likely I flew back to Sydney. In a subsequent phone conversation with site personnel they advised that the unit was operating very well with clear overflow. They commented, “at least we are on to a winner there”

The plant operated until 1986 when the project to remove heavy metals from & neutralize the tailings was completed. The picture below shows the effect of the rehabilitation.



At the end of my report on the successful commissioning of the Rum Jungle unit I made the following comments:-

“The thought occurs that I might possibly get a patent for a design whereby the pulp is injected at an angle of 30-45 degrees into the pulp bed. The argument would be that in a pulp bed a gradual increase in pulp density occurs from top to bottom, which causes the upflow of liquid. When incoming pulp is injected horizontally into this pulp bed as in the Enviro-Clear thickener the rising liquid stream tends to force very fine particles straight out of the surface of the bed causing dirty overflows. However when the pulp stream is injected downwards as in the Supaflo, fine particles get pushed deeper into the bed and have a better chance of flocculating and not escaping from the bed.
I never did apply for that patent – a pity in the light of subsequent developments.
In many ways the Rum Jungle unit was a huge gamble. Little did I imagine that 35 years later over 1500 Supaflo units would be in operation worldwide.
It makes me very proud that I pioneered the concept.


At that time we were associated in business with Larox Oy of Finland who were given a license to sell the Supaflo where they had representatives. In late 1984 they sold a unit to Sunila in Finland. In April 1985 they attempted to commission it without success. When the SOS came for help I was away from the office so Neil Jagger got on the 1st available flight to Finland. After spending 2 weeks at Sunila he failed to get it working. The unit was shut down pending further on site inspections and tests.
In September 1985 I visited Sunila and it was fairly obvious why the unit had failed to operate. I wrote a lengthy report the salient points of which were: – 1. Larox had attempted to convert a conventional thickener to a high rate unit. The thickener had only radial launders in the form of a square. The area inside this square represented only 16% of the total surface area of the tank. Thus the liquid rise inside the square was much too high. The effect was to drastically reduce the effective diameter of the unit. They were advised to remove the radial launders and fit a peripheral one 2. No pulp bed level detector had been fitted making pulp bed level control impossible. 3. They were also advised to lengthen the downpipe.
I do not know if these modifications were ever carried outwas


I first tested samples of ironsands from NZ Steel in November 1984. On the basis of the tests I tendered for the supply of a 9.5m unit and after flying to Auckland in March 1985 secured an order. The unit was erected and ready for commissioning on 11/2/86.
My 2 weeks at the site proved a nightmare. I probably averaged 18 hours a day at the site.
Problems were numerous but probably the biggest stemmed from the fact that the original sample as tested was not truly representative of the actual feed, it had been made up synthetically. Also our engineer had chosen to introduce feed to the feedwell tangentially which resulted in the entire thickener contents rotating. To stop this it was necessary to insert a baffle in the feedwell. Another problem was the presence of coarse heavy material in the feed. This accumulated on top of the deflector cone, closing off the plate gap. These could only be removed by emptying the unit and hosing the course material out. Plant modifications were necessary to remove the coarse material from the feed pulp.
The 2 weeks proved invaluable for subsequent Supaflo design. The need for multiple flocculant injection points and the use of adjustable length sparge pipes helped flocculant dosing problems. The problem was finally diagnosed by cylinder flocculation tests, which demonstrated the fragility of the flocs. Hence flocculant needed to be added as late as possible before the feed entered the pulp bed.
It was at NZ Steel that one of the major advantages of the open, internal feedwell was first noticed. Due to their different S.G.’s the level of clear overflow outside the feedwell was always higher than inside it. This facilitated gravity dilution of the incoming feed pulp using adjustable weirs. I note that Outeco claim the world’s first systems to auto dilute feed. This was done at NZ Steel over 30 years ago!
I have copious notes on the commissioning but sufficient to say when I left the site on Saturday 21/2/86 the thickener was working satisfactorily. The present so-called “floc-miser” feedwell owes its origins to the NZ Steel experience,



 1. Lebong Tandai Indonesia

My greatest wish in the early years was to secure an order for a CCD circuit. Successful pilot testwork was done in December 1984 at Roxby Downs (see below) where the 1 metre unit was incorporated into their pilot CCD circuit so I was confident it could be done. In May 1986 I attended the Institute of Mining and Metallurgy annual conference in Singapore. There I made contact with metallurgists from the Indonesian company PT Lusang who were re-developing a gold mine at Lebong Tandai in Sumatra. It had been worked by the Dutch years before but they had left behind gold bearing tailings, which presented an ideal CCD leaching situation. However, as I was to find out on my site visits, the mine location was unique being in a river gorge with steeply sloping sides.

Aerial View of Lebong Tandai

There was insufficient level ground to accommodate large diameter conventional thickeners. The preferred treatment method when I made contact was a horizontal belt filter with counter current washing. I managed to convince them that Supaflo thickeners could do the job and would require much less level ground than conventionals.
I returned to Sydney on 17/5/86 and took the first available flight to Jakarta on 25/5/86 taking with me the 100mm test unit. The journey to Lebong Tandai is an all day adventure. First a flight then a drive over very rough road followed by a 2 hour ride up a river in a canoe with an outboard motor before a final hour on a narrow gauge railway.

The narrow gauge railway

The on site tests were successful and I returned via the same route and back to Sydney on 31/5/86,

After a lengthy meeting with PT Lusang personnel I got an order for 4x 4.5metre Supaflos. However supply had to be on the basis of local fabrication to our drawings with rakes, feedwells and drives supplied from Australia. Whilst I didn’t like this scenario it was necessary to get around Indonesian local content rules for steel imports.
They were in a hurry to get the plant operating and supply had to be quick. The units were erected and ready to go by November 1986. I spent 3 weeks at Lebong Tandai from 18/11/86 to 6/12/86 supervising final erection details and commissioning the units. We had also supplied for the first time, closed loop control systems whereby underflow withdrawal rates were controlled by the rake torque and floc dosing rates by the bed level detector.
An interesting sideline occurred prior to the commencement of commissioning. The local people insisted that the plant would not work unless the gods were placated. To do this they slaughtered a steer and buried his head in the middle of the site. It must have worked because the commissioning went very well thereafter.

I should mention that they roasted its body on a spit and had a grand barbecue. During the following months the operators were able to considerably increase throughput. Mine personnel were delighted with the success of the installation.

2 Olympic Dam – Australia

When Rio and Fluor were building the first pilot plant at Olympic Dam I got permission in June 1984 to take the 100mm test unit to the Olympic dam site which was very rough at that time with accommodation provided by pre-fabricated “dongas”.
Rio personnel were able to witness the successful operation of the test unit in their site laboratory. At this stage a 1metre diameter pilot unit was under construction and the Rio personnel said they would like it at Olympic Dam as soon as it was available.

In December 1984 I returned to the site and commissioned the 1m unit. Rio personnel then operated it so successfully that they phoned me on 13/12/84 to say that after I left they had achieved up to 10 times the throughput of the conventional thickeners.
The 1m test unit was returned to site again in January 1985 and again for a 4 month period commencing in July 1985. During this period they were able to put the unit series with 3m conventional thickeners in a CCD circuit, taking the full flow from these units – great news
In June 1986 a tender was submitted for the supply of 5 x 14.5meter diameter Supaflos and in August 1986 an order for these units was obtained. A 6th unit was ordered shortly after.




I made 2 visits to Zimbabwe in connection with a Larox Oy bid to supply 3 Supaflos. On the second visit in August 1986 the units were successfully commissioned.

The mine was shut down in 2006 – suffering a similar fate to economic farming in Zimbabwe



Monday 29th August 1988 was, by far, the worst day of my life.

On that day fellow director Neil Jagger supported by 3 employees, David Taylor, Ian Arbuthnot and Jonathon Trope confronted me with an ultimatum. Either I agreed to sell my half share of Supaflo Pty Ltd to him or all senior staff would resign and take most of the junior staff with them to form a new company making high rate thickeners. I was shocked and disbelieving that these 4 young men who had every reason grateful to me for the friendship and career opportunities I had given them should turn on me in this fashion.


Briefly: – Jagger I first met Jagger in 1977 when we were both working for Delkor Pty Ltd in South Africa. I returned to Australia to establish Delkor Australia in 1978. I subsequently left Delkor in 1979 and became Managing Director of Enclear P/L a company formed in conjunction with Bulk Materials P/L to market the Enviroclear thickener.

Jagger Phoned me on 23/3/80. He had been sent to Australia by Delkor on a 1 year contract ending on 31/12/80. He had a 2year temporary work permit but was keen to settle permanently in Australia and sounded me out about a possible job with Enclear.

He pestered me throughout 1980 but I was unable to commit to employing him. However I finally agreed to employ him on a casual rate of $20 per hour for a 4 month trial period and he started with Enclear on 8/1/81. In order to obtain permanent residency I gave him a written Contract of Employment in May 1981.

In November 1982 I sold my shares in Enclear and formed Larox Pty Ltd with Larox Oy of Finland. I gave Jagger a 15% shareholding in the company. Because he had no capital I loaned him the $30,000 which was his share of the $200,000 needed to establish the company. It was agreed he would pay it back interest free out of future profits. The reader will understand why I described his actions in 1988 as the worst act of treachery I have ever experienced.

Taylor I had known for over 10 years both workwise and socially. He was out of work when I offered him a job in about 1981.  Arbuthnot and Trope I interviewed in South Africa in September 1985. I subsequently offered them jobs in Australia, going to great trouble with the Department of Immigration to expedite their applications for residence permits.

I was given little time to consider my options and rushed off to the office of the company’s accountant, Warwick Pollard, who was obviously a party to the conspiracy.

To this day I have difficulty understanding why I gave away my life’s work. Without the benefit of legal advice I was pressed into signing a document that gave away everything I had worked for including all my rights to royalties from future sales of Supaflos. I was paid only for my shares in Supaflo Pty Ltd., but nothing for the ongoing rights to manufacture Supaflo thickeners.

It was a foolish mistake but I was confused and deeply hurt that these men could turn on me so fiercely. In the months and years that followed I came to bitterly regret signing. I did learn that Jagger got the support of the others by promising them shares in the ‘new’ Supaflo Pty Ltd. I also learned that the threat to take all of the junior staff was a bluff – they were never consulted.

I all my working years I still consider the action by Jagger as the worst act of treachery I have ever encountered.

The real tragedy is that these men, through incompetence, allowed the manufacturing rights of an Australian invention to fall into the hands of the Finnish company Outotec OY. I would never have let that happen. They have also changed the name as though it is their invention.

I believe Jagger got to be a President of Outeco Oy and is probably today a very wealthy man.


After the unfolding of these events I went through a few very bad years. Initially I found myself walking around in a daze wondering how this could have happened to me after all the personal sacrifice I had made particularly at Rum Jungle and New Zealand Steel. I had spent many weeks away from home getting orders and commissioning units. It all seemed like a bad dream from which I would eventually awake. I hated and despised Jagger for what he had done and thought of ways to get back at him. Such ways existed, I had been with him on several trips to Finland and could have divulged his behaviour there but I couldn’t bring myself to do so.
I suffered a chronic depression, my marriage broke up and I was really in the pits.
Fortunately I met my present wife, Elspeth, in 1990. She is a psychotherapist and she got me over anger and into a new life.
I discovered I had other talents besides inventing thickeners. Initially I opened a gymnasium for older exercisers, selling this & retiring when I turned 70. I also became an avid cyclist

We lived for 5 years on the beautiful Scotland Island north of Sydney until unfortunately I developed Emphysema as a result of the years I smoked until my 40th birthday. We subsequently moved to Bayview Gardens a spacious Over 55’s estate with access to aged care. We also spend up to half of each year in our lovely house in Caunes-Minervois in the south of France.

Now 85 I suppose I could dwell on all of the lost royalties I should have got from the 1000+ Supaflos Outotec Oy have sold but at least I have a clear conscience about the way I have dealt with my fellow men throughout my entire life. Others might have trouble with their consciences and problems sleeping at night – I hope so. I Am on Facebook where many photos of my recent life can be found. Click on the link below. In particular I am proud of the picture of me with Chum Mey who was one of the few survivors of the Pol Pot torture camp in Cambodia. We met him when we cycled from Saigon to Bangkok in 2012.

John’s Facebook Profile

The reader might ask why I have chosen to do this site after all these years. In fact I originally did it 10 years ago and this is to bring it up to date.. It came to my notice that Jagger got an award in 2002 from The Institute of Mining & Metallurgy for “revolutionizing of the development and implementation of new thickener technology.” What a joke – he should give the award back because his contribution to the invention of the Supaflo was minimal.

All of the events described here are documented in my diaries from the eighties.