Document M26eJ7b1GXmLypbrd1ykNq7L

i r(MFviMIKiUWM%V*<NI C* GOVERNMENT OF WESTERN AUSTRALIA G^Z/ ^-------- ^ GOVERNMENT CHEMICAL LABORATORIES Ta. No. 23 1927 ADELAIDE TERRACE PERTH "* **' ............ tou*,,. DDL/Hi. Commissioner of Public Health, Public Health Departcent, PERTH. l#tbSeptember, 1962. Attention: Dr. D.Letfaam Physician, Occupational Health Report on Samples from Wittenoca reeelred 17th July 1962. The samples received consisted of the following:Lab. No. 6242/62, marked "A.B.A. Dust Sample, No. 1" Lab. No. 6243/62, marked "A.B.A. Dost Sample, No. 2" Lab. No. 6244/62, a filter pad frcei a respirator. As discussed with Dr. D. Letham, no work has.been carried out on Lab. No. 6244/62. HiCrOSCOpiC ' Lab. No. 6242/62 "A.8.A. Dust Sample No. 1" Semple consists of quartz, hematite (iron adde), chalybite (iron carbonate), dolomite (calcium magnesium carbonate) and magnetite (magnetic iron oxide) with a little blue asbestos and organic matter. The particles range in size up to 12m in diameter. The average particle size is of the order of 1a. ''i The asbestos fibres range 19 to 10a.in length. Lab. No. 6243/62 "A.BJU Dust Semple No. 2* Sample consists of magnetite, quartz, blue asbestos, chalybite, dolomite and hematite. The particles range in size to 600,1/ in diameter. The average particle size is of the order of 2-3^. The asbestos fibres ere up to 600c*.in length but would average about 10 K. / C 41 98 Cor.tir.u-'-i C 4199 Sizing The dusts were sized by air elutriaticn in & Roller Particle Size Analyzer with the following results:- Fraction microns +50 -5C + 30 -30 +10 -10 +4. -4 Lab. No* 6242/62 Lab* No* 624.3/62 per cent - - 11*4. 88.6 16.2 17.3 7.0 17.5 42.0 Remarks Lab. No. 6242/62 The +4-jUfrection was obtained by direct weighing and tie H/* fraction'ey difference. ^ Sample required washing with petroletB ether to remove-a contaminating oil which prevented sizing by Roller machine due to formation of agglomerates. Microscopic examination of final products showed good separation into the two fractions. Lab. NO. 6243/62 Microscopic examination showed reasonable separation within tne' normal size ranges, except for a small amount -cf asbestos fibres with lengths 7 to 10 times the nasinal particle diameters. Asbestos fibres were more evident in the coarser sizes with carbonates, quartz and magnetite being identified in eaoh range. Composition The percentages of acid-soluble iron, carbon dioxide and eeid-inseluble material have been determined chemically in these samples. The percentage of magnetite has been estimated by magnetic separation, and by cicroscopio examination. The add-insoluble aaterial, which is essentially asbestos and quartz, has been divided semiquaatitatively into its components. 3y combining those techniques, a very approximate composition of the dusts is obtained as followsj- Lab. No. 6242/62 Lab* No. 624.5/'? per cqr.t by weight 7 53 12 4: 27. 00 L t