I’ve been exchanging more emails about Risdon with the ever-insightful Byron Deveson. At my suggestion, he bought a copy of a 10-page pamphlet entitled “A Brief Guide to the Risdon Plant of the Electrolytic Zinc Company of Australasia Ltd, March 1949” online from an Australian bookseller: this includes maps and layouts of the buildings around the zinc works at Risdon, and also descriptions of the history and the various industrial processes involved.

One particular paragraph on page 3 leapt out at me, because it contained an unexpected fact that may change how we look at the Somerton Man case:-

“The flash-roasting furnace in which the charge is roasted when suspended in air as a dust has been in operation at Risdon for only four months.”

The pamphlet was written in March 1949: so four months before (i.e. around November 1948), an entirely new flash-roasting furnace that took powder as its input was coming online at the plant. At the Electrolytic Zinc Company’s AGM at the end of November 1948, the chairman had noted that: “The cost of the flash roaster and the new acid plant at the Risdon works had so far been about £560,000. That would give some idea of the magnitude of these additions to the Risdon plant.

Byron Deveson’s opinion (and I do hope he won’t mind being quoted on this): “The fluidised bed calciner could pump out lots of fumes while it was being commissioned. The air coming out of the roaster has to be scrubbed very thoroughly, and there would be lots of it and malfunctions during the commissioning phase are quite likely.

Moreover, according to page 7 of the March 1949 pamphlet:

“A contact sulphuric acid plant began operating at Risdon in December 1948 …”

This leads Byron to the further conclusion that “it is quite likely that the roaster gases that were discharged from the cyclones were probably vented into the atmosphere for several months before the acid plant was completed. And the lead dust particles would have not been noticeable but the lead concentration could have been quite high.

The Somerton Man is now looking to me likely to have been the victim of industrial lead poisoning incident at Risdon in the period after the flash roaster was initially put into commission (October / November 1948) but before the acid plant started operation (December 1948). If this is correct, the most productive place to be looking for answers should be in the Eletrolytic Zinc Company’s staff records archives (which still exists and is held in Hobart).

Essentially, if the Somerton Man had been working there in November 1948, he certainly wasn’t being paid during December 1948: that should be sufficient to narrow the search down to two or three people. Pretty good odds! 🙂

4 thoughts on “How the Risdon roaster might explain everything…

  1. Helen Ensikat on December 11, 2014 at 7:01 am said:

    Nick, it looks like the Risdon plant took on 18 displaced Eastern European refugees in October of 1948. My family were Lithuanian refugees around the same time, and I know it was all to easy to disappear and never be seen again the the general upheaval – may be worth following up? I’ll email you the link as it keeps triggering the spam filter.

  2. B Deveson on December 11, 2014 at 10:18 am said:

    Nick, the following booklet describes the operations of the west coast mines (Rosebery) in 1948.
    The ores were concentrated by froth floatation (a wet process), the concentrate dried and then placed in large containers for transport by rail to Burnie (a port on the north coast of Tasmania).
    “Operations of Electrolytic Zinc Company of Australia [sic] Limited, West Coast Department : Rosebery-Hercules Mines, Tasmania Electrolytic Zinc Co. of Australasia. West Coast Department. Book.1948.” This booklet can be viewed online at the State Library of Victoria’s site, or search Trove (books) for “Rosebery-Hercules”.

    It appears unlikely that anybody would have been exposed to high levels of lead dust in either the Rosebery mine or the ore treatment plant at Rosebery. Industrial accidents excepted of course. My reasons for believing this are 1) I have not been able to find any cases of lead poisoning at the west coast mines. 2) you can see from the photograph of the ore being mined that water sprays were used to stop the production of dust. The mere fact that the photograph is so clear demonstrates that the mine air was free of dust. As anyone who has taken flash photographs underground will know, any significant quantities of dust in the air will result in very murky photos. 3) the type of plant used at Rosebery to concentrate the ore is not the type of plant that would generate significant dust. 4) the west coast of Tasmania is very wet and the annual rainfall at Rosebery is 2.19 meters (86 inches).

    It is not clear if the containers (bins) would have been emptied into the ship at Burnie, or if the bins were loaded and taken to Risdon. If the bins were emptied, then dust containing lead was probably produced and we would have to include stevedores at Burnie in the list of SM possibles.
    The photo of the mine yard showing the bins suggests that there was very little dust around the plant. And the west coast is very wet and it is said to rain every day of the year. Wuthering heights in dense, cold climate rain forest is the best description of the setting.

    At Risdon the acid plant was completed after the roaster, so how were the roaster gases disposed of while the acid plant was being built? Vented into the air most likely. If anyone thinks that this could not happen (the venting of large quantities of sulphur dioxide into the air) the calcining furnaces at Zeehan had only closed in mid 1948, and the furnace gases had been simply discharged through a chimney.

    Risdon roaster gas would have carried some fine grained lead particles because the cyclones would not remove particles smaller than about 10 microns (just too small to see with the naked eye). From my experience testing aerosol inhalers, particles in the size range 2.5 to 10 microns are trapped in the lungs. These particles are then cleared by the lungs and end up in the stomach. The fine grain size means that these particles will be significantly dissolved in the acid conditions of the stomach.
    So, it is quite likely that the roaster gases that were discharged from the cyclones were probably vented into the atmosphere for some time before the acid plant was connected to take the gases containing sulphur dioxide. While the lead dust particles would have not been noticeable the lead concentration could still have been quite high. I will see if there were any complaints of sulphur dioxide gas coming from the Risdon plant in 1948.

    From the Wikipedia article “Fluidized bed” it seems that the roaster at Risdon was one of the first to roast metal ores. So there would have been little or no operational experience with this type of roaster and it is likely that there would have been discharges of gas containing lead dust and sulphur dioxide at times.

  3. B Deveson on December 11, 2014 at 10:21 am said:

    Advocate (Burnie) 30th June 1948 page 1

    ZEEHAN SMELTERS TO CLOSE DOWN NEXT WEEK
    Roasting at the Electrolytic Zinc Co’s, smelters at Zeehan will be discontinued in a week’s time. The last rail load of concentrates will leave Rosebery tomorrow for the Zeehan plant, and it is expected that roasting of this ore, together with supplies on hand, will take about a week.
    The entire output of concentrates from Rosebery will in future be despatched to Risdon, where completion of extensions to the roasting and acid plants demand great quantities of concentrates.
    About 50 per cent of the production-500 tons weekly-has in the past been railed to Zeehan for reduction to calcines which have then gone to Risdon for the production of zinc.
    The recovery of sulphur, which is lost in the atmosphere at Zeehan, is a feature of the Risdon plant. The acid produced from the sulphur is used mainly in the manufacture of super-phosphate.
    The Zeehan roasting plant has been in operation for the past 12 years and employs approximately 30 men. For the time being they will be engaged in cleaning up calcine dumps and in the dismantling and removal of portion of the plant. On the completion of this work they can be readily absorbed at Rosebery.

    So, for a period of five months (first week in July 1948 when the Zeehan smelter closed, till December) zinc concentrate containing lead was despatched to Risdon at a rate of 500 tons a week. This material, 10,000 tons would have built up in the stockpiles at Risdon and the staff would have been under pressure to start roasting this material as soon as possible/ The supplies of calcine to the electrolytic zinc recovery plant would have been curtailed and this would have increased pressure on the staff to get the roaster working as quickly as possible.

    Note: “For the time being they will be engaged in cleaning up calcine dumps and in the dismantling and removal of portions of the plant. On the completion of this work they can be readily absorbed at Rosebery.” I think this is another place where the workers could have been exposed to much dust containing lead so we should include the thirty Zeehan workers in the list of SM possibles.

  4. B Deveson: this was happening back in June/July 1948, so it seems fairly likely to me that the Zeehan workers wouldn’t have been significantly exposed beyond about July/August. Risdon is still top of my list for where we need to be focusing to find out what happened. 🙂

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