Application Of Air To Asbestos Milling At The New Jeffrey Mill Of The Canadian Johns-Manville Company, Limited, Asbestos, Que

Our plain-English summary of Application Of Air To Asbestos Milling At The New Jeffrey Mill Of The Canadian Johns-Manville Company, Limited, Asbestos, Que, by H. Rozovsky (1955).

The study

• Author: H. Rozovsky
• Published: Canadian Mining And Metallurgical Bulletin, Pp. 1-10, August (1955)
• Type of article: Conference paper
• Our copy: from Johns-Manville's own medical library, J-M no. 001873. The article is still under copyright, so we describe it here rather than post it.

In plain English

This paper was an engineering description, not a health study. The author described air handling at the new Jeffrey mill of the Canadian Johns-Manville Company in Asbestos, Quebec. This dry mill could handle over 14,000 tons of ore per day and needed at least 2,500,000 cubic feet of air per minute. Air lifted fibre off screens, carried it through cyclone collectors and controlled dust. Fans and cotton bag filters on the 12th floor cleaned the air before its return to work floors or outdoors. The author noted that dry milling produced enormous quantities of airborne dust and fibre, with screens the greatest single source. Twenty-seven dust counts were taken with the Greenberg-Smith impinger one month after operations began, before all dust control features were installed. The lowest, on the filter floor, was 0.14 million particles per cubic foot. The permissible level was given as 3.0 million particles per cubic foot. The average of the counts is garbled in the available text and cannot be read reliably. The author reported that the systems seemed to be working well and that regular dust surveys were planned.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Technical engineering paper describing the ventilation, air handling and dust control systems of an asbestos mill; not a study of workers' health
• Who was studied: The new Jeffrey mill of the Canadian Johns-Manville Company at Asbestos, Quebec, a dry mechanical asbestos mill able to handle over 14,000 tons of ore per day; no workers were studied
• Exposure: Airborne asbestos dust and fibre produced by dry mechanical milling of asbestos ore (no fiber type named); dust measured as particle counts by the Greenberg-Smith impinger method
• Main results:
  • The author identified screens as the greatest single source of dust in the mill
  • 27 dust counts were made by the Greenberg-Smith impinger method, one month after operations began
  • The lowest dust count, on the filter floor, was 0.14 million particles per cubic foot
  • The permissible level was stated as 3.0 million particles per cubic foot
  • On a winter day with an outside temperature of 15 degrees F, heat from electricity and ore kept most floors at 63 degrees F, with relative humidity of 37 per cent
• The authors' conclusion: The author concluded that the various phases of the operation seemed to be working well, that operating pressures were low, and that a programme of dust control surveys would be carried out at regular intervals when the full mill went into operation
• Limitations the authors state:
  • The dust counts were taken before all dust control features had been installed

Topics

Medical terms in this study, explained in our Lexicon: Canadian Johns-Manville, Midget Impinger, Dust Control, Million Particles per Cubic Foot (mppcf).

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