Document 3eY12XXwREgJ4gX6yneD0kmpn

SPECIAL MATERIALS, IWC. WISCONSIN 3628 W. PIERCE STREET, MILWAUKEE, Wl 53215 PHONE: (1) 383*2020 800*550*0604 TWX 910*262*3106 SPECIAL MIL September 10, 1979 Mr. Horace Beasley Director of Purchasing CEMENT ASBESTOS PRODUCTS COMPANY ll*00 - 20th Street South Birmingham, AL 35205 Dear Horace: Confirming our meeting last week, we are shipping today via UPS samples of ML-6, washed and unwashed blue asbestos. We are also attaching a report from General Mining and a report from the South African Asbestos Producers Advisory Committee (SAAPAC) covering the health and technical aspects of using blue asbestos and washed blue asbestos. This information is extremely valuable and should help you in controlling dust levels in your plant and improving the strength of pipe. I expect Mr. Pat Hart to be in the United States in the latter part of October. We sincerely hope that your tests could be completed so that the effect on next year's production could be known at that time. Thank you for your consideration. Very truly yours, SPECIAL MATERIALS, INC. WISCONSIN R. C. Wareham RCW/ms Enclosures CAP CO JEN 0011014 File 13.1.8. CAPE BLUE ASBESTOS PREMATURE PREJUDICE? 1. For more than 20 years particular attention has been' focused all over the world on potential health hazards associated with Cape blue asbestos. ^ 2. It has been stressed repeatedly at almost every conference since Lyon in 1972 (3, 4, 5, 6) that there is no difference between all the commercial asbestos fibre types in relation to asbestosis and bronchogenic carcinoma. This has also been confirmed at the three latest scientific conferences on health hazards of asbestos, namely, the Johannesburg Asbestos Sym posium of October 1977, the Washington Conference in December 1977 of the Society for Occupational & Environmental Health and the Science Week Conferences organised by the New York Academy of Sciences in June 1978. 2.1 It is only in conjunction with mesothelioma that some countries, e.g. U.K., Ireland, Holland; Japan, Norway and Sweden, accept a higher risk for crocidolite for which assumption to date no conclusive scientific evidence has been produced. (7) 2.2 It would appear that the known and proved number of primary diffuse mesothelioma cases all over the world is still confined to under 5 000 as indicated by Professor J.C. McDonald at the Johannesburg Asbestos Symposium in October 1977, (8) where he presented an updated version of a paper specially prepared for the 18th International Congress on Occupational Diseases at Brighton in September 1975. 2.2.1 /2 CAP CO JEN 0011015 2.2.1 In general, this paper did not give additional information to that presented at the Brighton Conference, except for quoting and over emphasising the incidence of the disease in personnel employed during World War II in two gas-mask factories, one in'England and the other in Canada, with high rates of cases at relative low exposure. However, during discussions it was proved that those exposures were not'as low as indicated by Professor McDonald, but were in fact very high. Crocidolite was dustier to handle and the gas masks had contained loosely bound pads. (9) 2.2.2 Those 5 000 cases have been reported throughout the world over a period of 15 to 25 years. (McDonald quotes a period of 15 years from 1960 to 1975, whereas other researchers cover up to 25 years). However, the annua) incidence of lung cancer amongst males in the U.K. amounts to just over 25 000 (102) and in the United States of America to more than 50 000 cases (55). According to Selikoff at the Johannes burg Asbestos Symposium (10, 11) and sub sequently confirmed by Dr. R. Saracci for the IARC of Lyon at the Washington Conference, lung ' cancer is in fact a far bigger risk than meso thelioma, mainly in conjunction with smoking. 2.2.3 Where employment records were available (2 721 cases only) 665 of mesothelioma cases could be attributed to asbestos exposure (12) depending on cohorts examined or reviewed. 2.2.4 However, there was positively no asbestos ex posure in 345 of the cases. It seems strange that hardly any attention has been paid to this phenomenon although for several years it had been /3........ CAPCO JEN 0011016 been known that in two villages of Eastern Anatolia, Turkey, pleural and peritoneal meso thelioma were of higher incidence than reported anywhere else in the world. All soil samples were negative of asbestos. At the New York Conference it was confirmed that recent mineralogical studies established that certain zeolite minerals, namely, erionite and chabazite, were the causative agents for these diseases in that region. 2.2.5 The ecology of mesothelioma is still unknown and there is as yet no reliable method of early diagnosis of the disease. (13) 2.2.6 Looking back one is amazed when realising that it was through scantily deduced and by no means subsequently proven constant association with this still relatively rare tumour that Cape blue asbestos was incriminated as being the most hazardous of all asbestos fibres. This occurred mainly in South Africa where blue asbestos was considered the sole causal agent, but not so in other countries. 2.2.7 . Hammond and Selikoff report a high incidence of cases among insulation workers who, they emphasise repeatedly, were exposed largely to chrysotile and amosite. (14) Apparently, crocidolite v/as not used in the U.S.A. for insulation purposes. The largest asbestos manufacturer in the U.S.A. never used crocidolite for insulation at any time, employing it only in two product lines, namely, AC pipes and packing. (15) The whole concept of asbestos exposure was queried at the Johannesburg and Washington Conferences. According to Dr. George Wright it was intellectual arrogance to speak about asbestos exposure "being characterised solely by the number of fibres of varying sizes present in the environment" of the working place. "In the real world of those exposed in the workplace /4........ CAP CO JEN 0011017  . workplace nothing could be further from the facts". No people anywhere in asbestos mining, milling and/or manufacturing were exposed to asbestos only. There were various risks other 'than asbestos which, except for the synergistic effects of cigarette smoking, had so far been completely ignored. (16) Past exposure was incredibly high by modern standards, definitely in the hundreds, peak periods in the thousands. (17, 18, 19, 21, 22, 23) Host exposure estimates were vague to the extent that today one should not even bother to consider them. Except in the case of asbestos mining, it is unusual for workers to be exposed to one type of asbestos only in the course of a lifetime, and except for very few and fairly small applications, blue asbestos fibres are never used on their own but mainly in relatively small quantities as supplementary fibres with fibrous mixes of the asbestos-cement industry. Although Cape crocidolite has been used in the asbestoscement industry all over the world for more than half a century, few confirmed cases of mesothelioma have been reported from these factories. For a number of years before and after World War II, blue asbestos was used extensively in Britain for insulation pur poses. Nevertheless, it has been confirmed by Greenberg and Davis that under industrial conditions prevailing in Wales and Englad, the significance of crocidolite in the ecology of meso theliomas could not be determined. "(24) Professors A. and J.C. McDonald maintained that mining environments /5 CAP CO JEN 0011018 environments may well be free from carcinogens of the kind found in factories, ports and industrial cities. Moreover, fibre as produced at mills almost certainly differs in length and diameter from that used in application and processing. (25, 26) Many observers completely ignore the fact that in the earlier reports of Wagner there were only a few cases of occupational exposure, the balance being environmental where other pollutants, tubercular scarring, climatic conditions, ethnic factors, etc. could have been the cause of the disease or would have had synergistic effects. On the assumption that mining and milling would undoubtedly have been the heaviest industrial exposure-to Cape blue asbestos in South Africa, it is worthwhile to look at Professor Webster's figures as quoted at the Johannesburg Asbestos Symposium in October 1977. 10.1 The South African Asbestos Tumour Reference Panel had 712 cases on its register, which included all the known cases since 1956. 10.2 Occupational exposure had been established in only 420 cases and in 10% of these there was no suggestion of asbestos exposure. 10.3 Actual mining exposure accounted for 33% of these cases, or roughly 20% of the total. 10.4 There were another 20% environmental cases, mainly from the north-western Cape, 20% non-mining industrials and 30% with no knowledge of any exposure or details of occupational history. 11. At /6 CAP CO JEN 0011019  -6 11. At the New York Conference it was emphasised that : .11.1 '* Respirable asbestos fibres are ubiquitous anywhere in the world. Many short fibres found in human lungs may have nothing to do with commercial types but may have been completely untreated natural fibres inhaled from the ambient atmosphere. 11.2 There must be an exposure level which can be tolerated otherwise we would have had many more cases of mesothel ioma apart from more interstitial fibrosis on mines and mills. 11.3 In British ships much use was made of blue asbestos for the spraying of decks and bulkheads. Thousands of people must have lived constantly under these conditions. One and a half million men have served in the British Navy between World War I and now. This means there does exist a level of exposure which is safe; unless respirable fibre is released through stripping or demolition,there appears to be no risk. 12. CONCLUSIONS: The main arguments against crocidolite were and are still being taken from initial South African investigations of limited in- ' dustrial and mainly environmental exposure. Anywhere else in the world, industrial asbestos exposures were mixed and in most cases extremely heavy. No valid conclusions can, there fore,be drawn regarding the specific involvement of this particular type of asbestos. When sunmarising the dis cussions of the special session at Lyon dealing with malignancy and fibre type, Rossitter states that each commercial variety of asbestos fibre, except antliphyllite, has been associated with excessive mesothelioma. (27) This has been confirmed at subsequent conferences. There /7 CAP CO JEN 0011020 7 There are still many serious gaps in the medical knowledge of asbestos-related, diseases apart from the fact that many medical evaluations are not internationally comparable by reason of differences in diagnosis and incompatibility of statistical information and documentation. The absolute carcinogenicity of the various asbestos"fibres is unknown. According to Langer the present emphasis on croci- dolite is premature. (28) , FB/WA Johannesburg ^.November, 1978 CAP CO JEN 0011021  REFERENCES 1 McCullagh, S.F. 1 bis Berry, G. 2 Wagner, J.C. 3 Wagner, J.C. 4' 5 6 7 8 9 10 11 12 13 14 15 Webster, I. Sluis-Cremer, G.K, Irwig, L. Kleinfeld, M. Wagner, J.C. Berry, G. Skidmore, J.W. Timbrel1, V. McDonald, J.C. Wright, G. Elmes, P.C. Selikoff, I. McDonald, J.C. Elmes, P.C. Selikoff, I. Selikoff, I. Hammond, E.C. Gluckman, J. Enterline, P. 16 Wright, G. 17 Elmes, P.C. 18 Du Toit, R.S.J. 19 Robock, K. 21 Wiles, F. 22 Sluis-Cremer, G.K. 23 McDonald, J.C. McDonald, A. 24 Greenberg, M. Davies, T.L. Med J Austr 2. 1974 p.47 Proceedings Johannesburg Asbestos Symposium (OAS) p.56 JAS p.110 NY Head Sc Vol 132 (1965) Art 1 p.231 IARC No. 8 p.197/8 ' JAS p.54 (4) JAS 60 ' JAS p.135 J.Occ. Ked 15, 1973 p.299 British J Cancer Vol. 29, 1974 P.267/8 JAS p.67 - 79 JAS p.81 ^ OAS p.15 JAS p.91 JAS p.123 OAS p.67 JAS p.16 OAS p.80 Proceedings Johannesburg Pneumoconiosis Conf. 1969 p. 184 Proceedings Johannesburg Pneumo coniosis Conference 1969 p. 143 Am.Rev. Resp Dis. 113, 1976 p. 176 JAS p.96 . JAS p.105 OAS p.45 OAS p.27 JAS p.104 JAS p.51 Preventative Med. 6, 1977 p.434 Brit. J Ind Med. 31, 1974 p.103 2/ CAP CO JEN 0011022 * -2 25 26 27-. McDonald, J.C. McDoanld, A. McDoanld, J:C. Rossitter, C.E. Du Toit, R.J.S. Ou Toit, R.J.S. 28 Langer, A.M. Mackler, A.D. Pooley, F.D. Prev. Med. 6, 1977 p.440 JAS p.125 Proceedings Lyon Conference IARC No. 8 p.226 JAS p.-O JAS p.35 JAS Conclusions p.13ff Envir. Health Persp. 9, 1974 p.79 CAPCO JEN 0011023 NEW THRESHOLD LIMIT VALUES FOR CROCIDOLITE AND AMOSITE ASBESTOS prbposed by the American Conference of.Governmental Industrial Hygienists A commentary by Richard Gaze, BSc., PhD., FRIC CROCIDOLITE The proposal is that the TLV should be 0.2 f/cc-1- ie one tenth of that proposed for chrysotile. While there is no scientific evidence to justify a one tenth ratio in terms of hazard, there is a general philosophy that crocidolite is the most'hazardous form and particularly so far as mesothelioma is concerned. The evidence for this conclusion originates from Wagner's work in South Africa (1) and the reported lower incidence of mesothelioma in the Canadian chrysotile mines (2). This has been followed by reports of mesothelioma among workers from the Wittenoom mine in Australia (now closed) (3) and among workers in war-time plants assembling gas mask filters containing Australian crocidolite (4). A difficulty in finding confirmatory evidence has been that in most situations, long term exposure to single asbestos types is very difficult to isolate. Careful analysis of the evidence provided from mixed exposures has provided some confirmation that in such exposures to mixed dusts, the incidence of disease appears to be higher when crocidolite is present. (Newhouse (5); Enterline (6); Weill (7) ) This is believed to be the essential evidence indicating that crocidolite is the most dangerous form of asbestos, which view is summarised in the report of the Advisory Committee on Asbestos Cancers to the IRAC in 1972 (8) and by Wagner (9). Experience of control in the use of asbestos leaves no doubt that a TLV of 0.2 f/cc is equivalent to a ban on the use of crocidolite as a raw.material in very nearly all if not all industrial operations. By far the major use of crocidolite today is in the manufacture of asbestos cement pressure pipe.. This is a valuable product, being used throughout the world for'water distribution and the handling of sewage. It is of particular importance today since while cast iron and plastic pipes may also be used, asbestos cement pipes ive by far the lowest total energy content i. their composition and manufacture. A high proportion of manufacturers regard crocidolite as an essential component if these pipes (and particularly those with the higher diameters) are to be produced economically. If this use is to continue, then a higher TLV must be accepted for crocidolite or an exception made in some way (as in the Benelux countries). The question then arises whether there is in fact any CAP CO JEN 00110241 hazard when crocidolite is used for this purpose in modern processes. -The following factors should be taken into consideration : * 1) The evidence accumulated from the mining and use of crocidolite in the past involved techniques and processes resulting in exposure to dust concentrations at a level which would be entirely unacceptable and indeed unimaginable today. The stripping of - crocidolite sprayed insulation from warships for example, produced fibre dust concentrations of many hundreds and indeed thousands of fibres per-cc. (10) 2) With one exception (7) these processes are no longer used and can in no way be compared with the wet asbestos cement processes used to manufacture pressure pipes. Weill's account of the history of workers in asbestos cement plants in New Orleans (7) includes measurement of dust concentrations in current operations but not for the past under conditions to which his workers were exposed. 3) It is important to summarise the present evidence available from asbestos cement plants that have been using crocidolite for the past thirty to forty years. Austria Haider (11) reports no excess of mesothelioma in the regions in which asbestos cement industries were situated. Austria has the oldest asbestos cement industry in the world, excellent public health records, and has used crocidolite regularly since before the last war. Switzerland Rllttner (12) reports that of four cases of mesothelioma identified in Zurich from 1961 to 1976, only one had proven exposure as an asbestos cement worker. This country alsohas a long history of asbestos cement manufacture and has regularly used crocidolite. Germany Robock (13) reports only five cases of mesothelioma from the German asbestos cement industry (also a long term user of crocidolite) and these arise from one factory only where exceptional conditions existed. CAP CO JEN 0011025 -3- Belgium Lepoutre (14) reports that among current employees in a very large plant - also a long term user of crocidolite and with high dust levels in the past - there is no excess of lung malignancy and only one mesothelioma. United States From New Jersey, Borow (15) has reviewed the history of seventy-two cases of mesothelioma among workers at a large plant. The evidence unfortunately cannot be linked clearly with any one process since textiles, insulation and other products were made in addition to asbestos cement. The position is further confused by evidence . from a similar plant in Illinois, of similar age and manufacturing similar products (with crocidolite). No comparable excess of mesothelioma has been found at this plant (16). Weill (7) concludes that workers exposed in the New Orleans asbestos cement plants were subject to higher risks of respiratory malginancy in departments where crocidolite was used. The comparison is nol entirely convincing however because the t\ processes one using crocidolite and one not - are different. They use different raw materials and raw material processing methods, different forming techniques and manufacturing different products. Bearing this in mind together with the small overall numbers of those affected and the uncertainties of level of exposure in the past, more evidence is needed before more than a tentative conclusion can be drawn. / United Kingdom For various technical reasons, crocidolite has not been used to any significant extent in asbestos cement manufacture. The reputation that crocidolite has acquired in the United Kingdom stems from its use in entirely different processes associated - as we now know - with very high dust levels. Conclusion It is clear that the evidence upon which a TLV for crocidolite equivalent to a ban on its use - is proposed relates almost entirely /4 CAPCO JEN 0011026 -4- to conditions in the past which do not apply today. Thus none of the excessively dusty processes such as insulation and acoustic spray, gas mask filters, mattress making and lagging now employ crocidolite. Evidence from the asbestos cement side - the only major remaining use for crocidolite - is by no means as unfavourable and the contention of those who use it that at the same fibre levels, there is no greater risk with crocidolite than with chrysotile, has not been satisfactorily answered. It must be accepted that under similar conditions crocidolite is liable to produce more dust than chrysotile so that extra precautions may be necessary in order to achieve the same fibre dust levels but there is not yet evidence to indicate that provided this is done in asbestos cement manufacture, there is undue risk. As has been stated, the only significant use of crocidolite in the United States and elsewhere is in asbestos cement manufacture and so far as the United States alone is concerned, only in the manufacture of asbestos cement pressure pipes. For use in such processes, there is not adequate justification for the application of a separate standard for crocidolite. II. AMOSITE The proposal is that the TLV should be 0.5 f/cc -`ie intermediate between that for chrysotile (2.0 f/cc) and that for crocidolite (0.2 f/cc). ^ This stems from a philosophy that amosite occupies such a position and this has gradually developed over the past ten years, being expressed in the report of the Advisory Committee on Asbestos Cancers to the IARC in 1972 (8), by Wagner (9) and Enterline (6). It is in fact very difficult to find hard evidence for such a conclusion and it is indeed very much more slender than that advanced in connection with crocidolite. In spite of contrary evidence that has been brought' forward to indicate a different conclusion, the 'feeling' that amosite should have a special intermediate position has persisted. The evidence such as it is, is derived from Selikoff's studies of insulators and the workers in the factory where amosite insulation materials were produced (17). Amosite was the preferred fibre for these insulations and working conditions were undoubtedly bad by today's standards. Much of the exposure took place in war-time when there was a tremendous demand for the materials, particularly from the Navy, and precautions were minimal. As is now well known, many workers have suffered, the symptoms appearing a considerable time after exposure to the dust. /.5 CAP CO JEN 0011027 -5- There is virtually no other evidence. In considering this evidence, the following should be borne in mind : 1) The processes and products with which Selikoff's workers were involved are no longer used. The use of amosite is now confined to wet processes or to other processes . where dust levels can be readily controlled. 2) The dust levels developed in manufacture and use (including stripping) of these products were around two orders of magnitude higher than those encountered in asbestos processes today. 3) Over 907. of the world's supply of amosite comes from the Penge mine in South Africa. This mine has operated for over fifty years and in spite of intensive search, and in spite of the fact that conditions must have been bad by today's standards in days gone by, only two . cases of mesothelioma related to pure amosite exposure have come to light. (Webster (18)- ) 4) ' McDonald's examination of miners exposed to fibrous grunerite (amosite) in the Homestike mine did not reveal any excess of pulmonary cancer among miners with long service and regular exposure to this dust. (19) 5) Experiments with animals do not reveal conclusive differences between the toxicity of different fibre types. In these careful experiments, inhalation of amosite dust did not produce a greater incidence of lung cancer or mesothelioma than when other types of asbestos were used. (Davies (20) ) Conclusion The evidence for placing amosite at a TLV of one quarter of that of chrysotile is exceedingly slender and based largely upon a 'feeling'. The effect of this TLV, if applied to amosite, would be disastrous and few manufacturers would be able to use this valuable raw material. The facts do not justify such an extreme step. RG/WFG 24.7.1979 f '* I CAPCO JEN 0011028 1) Wagner, J.D.; Sleggs, C.A.; Marchand, P.: ' Diffuse Pleural Mesothelioma and Asbestos Exposure in the Korth West Cape Province. Brit. J. Indust. Med. _17 : 260-271, (1960). 2) McDonald, J.C. : Exposure Relationships and Malignant Mesothelioma. Asbestos Symposium. Johannesburg 1977. Edited by H.W. Clen. pp. 67-78 3) Palfreyman, R. Private communication. 4) Jones,J.S.P.; Pooley, F.D. ; Smith, P.C.: `Factory Populations Exposed to Crocidolite Asbestos. Insern., voL 52. 1976. pp. 117-120. 5) Newhouse, M.L. : A Study of the Mortality of Workers in an Asbestos Factory. Brit. J, Indus. Med. _26: 294-301, (1969). 6) Enterline, P.E. : Type of Asbestos and Respiratory Cancer in the Asbestos Industry. Arch. Environ. Health, _27, 312-317 (1973) 7) Weill, H.; Rossiter, C.E.; Waggcnspacl:, C.; Jones, E.N.; ' Ziskind, M.M. : Differences in Lung Effects resulting from Chrysotile and Crocidolite Exposure. Inhaled Particles IV, W.H. Walton, ed., Perganon Press, New York, p.78-9 (1977). 8) Report of the Advisory Committee on Asbestos Cancers to the Director of the International Agency for Research on Cancer. Lyon, October 1972. / 9) Wagner, J.D.; Gilson, J.C.; Berry, G.; and Timbrell, V. : Epidemiology of Asbestos Cancers. ' Erit. Med. Bull. _27: 71-96, (1971) 10) Harries, P.G. : A Comparison of Mass and Fiber Concentrations of Asbestos Dust in Shipyard Insulation Processes. Ann. Occup. Hyg. J14, 234 (1971) 11) Haider, N. : Comment in Discussion. Asbestos Symposium. Johannesburg 1977. Edited by H.W. Glen. pp. 89-90 12) RUttner, J.R. Ibid, p.86 13) Robock, K. Ibid, p.91 14) Lepoutre, J. Ibid, p.104 15) Borow, M. ; Conston, A. ; Livornese, L.; Schalet, K. : Mesothelioma following exposure to Asbestos : A Review of 72 Cases. Chest. 64, 641-646 (1973) 16) Wright, G.W. Private communication CAPCO JEN OO11029 -212) Selikoff, 1. J.; Lee, D.H.K.: "Asbestos & Disease". Academic Press p.315 18) Webster, I. : Comment in discussion. Asbestos Symposium. Johannesburg 1977. Edited by H.W. Glen. p.79 19) McDonald, J.C.; Gibbs, G.W.; Liddell, F.D.K. and McDonald, A.D. : Mortality after long exposure to Cumraingtonite. - grunerite. Am. Rev. Resp. Dis., 118, 271-277 (1978) 20) Davies, J.M.G.; Beckett, S.T.; Bolton, R.E.; Collins, P. and Middleton, A.P. : Mass and Number of Fibres in the Pathogenesis of Asbestos-related Lung Disease in Rats. Br.J.Cancer_37, 673 (1978) t \ CAP CO JEN 0011030 (as [v.:.:'-i:rr.r; cr ix-1 hratip/- RrcEMi nr.vri.ri'^r.fJT''. .-t: ti:f. FAhrijin/n?-t zv:> packa.v; i.-n ny iiLijr f.r.p.r.'-.Tns nror lii&O . * "" isinsn Thu world asbestos industry in general and tho blua fibre section in particular is-under constant prsssure from the authorities and media uitn respect to the health issue. 7hc industry, faced with a .multitude of results arid often dubious interpretations, has reacted in the only, correct nannsr in celling for an overall improvement in duct control and a general lowering af tho dust standards in end around the factories, Conorsi Mining; as a major producer of bluo aches too ar.d in keeping ui\h t-n overall company policy which treats el] mineral .'us;;: ss r.rti.r.i-:..* injurious to hncltfi, ha? embarked over the lost few yacre on an i.f.Lc?\r campaign to improve conditions not only in its c-wn mills but also to in;.- ./..! tho product and its packaging os far as possible so ac to (ac.ilit.*';.* 1-.,, ;-r duf.t levels in consumers factories. Somij of tbs'more recent and most significant developments in tho lost feu years are described in the following sections. a. .WAKiif-c^r rw oFjiwtJn.fi.ji.) nr?E to ncnucc rite nnnr .".-.n rjr fpiT.iLf'rECU. 1.1. Background. t Meet cf the producers in the blur; asbecvc-s industry incsrpor.ctc a reck sorting stage in the rocovBry pi.-nsr.-,,. Because '.he bonded ironstone host rock is so herd ; is cruiviti-'J to re due? the tonnage of barren rock milled on t:v.?.:h as possible. Thi*. ,;uL only caves on wur.r and tear of the mec`.-= ;i::c but also reduces ths amount of fibre degradation in th? Hi ng process. In order to carry out tho sorting opor A ton, which is e.-nentj r.l.V, a manual activity, as efficiently cc p-.-:-?it>lo it is ndvi;a;];; t.; separate the coarse ere from tho R.O.fi. flnoc ami to hand sort only the coarse fraction. To further improve efficiency it dnsirnbic to uosh the rock so os to i.r:./ th-i difforonco Isct>v-m waste arid ore as distinct as possible. k Gecsus;.- of the need to dry tho arc fo`; to tho mill the natural tendency has always been to usa water . sparingly os povcihlo on ills cac.rso rock or.d not at all on i': . R.O.i;, fjn>v; (minus 25 ns-*.) which wore sent straight to lhr .* *yon*. ....... Recant experiments carried out under t*" nusoircs of tho feuih African Asbestos Producers Advisory f:*.:.iittco (H.A.A.P.A.C.) indicated however Ihct washing of tnc ::tos could bu carried out or.d resulted in improved dust control it* the milling oporcliin. CAP CO JEN 0011031 Gu-iornl I'Uriing ir.-.;nrtlj..tuly cit-bsi knd 3'i`r.i, intenaivj ti-.t prr.jr.vi to study iri ciffpt.h the besefits of washing the total I'.Q.ft ere as it v.'.'c- npp.-.rcnt l!,-1 curtain 1; iiMr.it benefit;; could 000:11.; both on tho willing side and in the con:vj;.isrs facturio:-. Tbr.se benefits uero expected tr< be . * , . (a) Easier drying cf mud-free fines. (b) Getter removal of Micro fibre end rc.r.k dust from finished fibre products. (c) `.'slier dust control in all subraquent handling operatic::;;, (tl) A potential improvement in performs;*,e:> of the fibres in aebsslos cement products. (ei) Removal of significant porcinirace of the r.sailor and al .lnc|..c!.ly more iiijuiioua fine ,\;bs-stc.s freebie,os. These arc discussed further in the vallowing sections. . 1.2. The fired frv rJ.nss Washing. From the moment the charge of dynamito explodes; in the rook face underground until the mined ora reaches the surface stocl;piloy tho process of producing Micro fibre and fine riu=t continues. Tho heavy blast require:- to liberate tho fibre frow tho hard rock creates fines. 7hs ore is transferred in various ways by mechanical loaders or scrap .-u s or shovi.'.?_uri by'hand via various ore passes end tips until it fiiy i-ir:h.'-tho main shaft and is hoisted to surface;. .\ All the tine the rock and fines are shuffled to.ether r-rcavlag additional fine material. A further complication is the uratir in the mine. This arises from both natural underground sources as well as the ustor introduced during thr- mining activity i.c. as coding mater for drills, dust suppression etc. This uaiai mixes uitli tho fines end rock and causes mud contamination of all the free fibres in the ore. With tho previous sorting plants this iif.tor-logged finoa f;.--:!i:n was diverted straight to the dryers for preparation for willing. During tfv< drying process ths tcndsr.ry was to bake the rock rut--., mud and micro fibres J.nto tho exposed fibres thus nenccsitat-r.? intensive dry dedusting in tho milling prouaas. This dry de dusting process is not only relatively inefficient but dec results in a cnrluln amount of fibre length being oi-.o.;n!*id with the dedustor undors. With finer uaching, which tokos place jiwi'.-'diately after tho hoisting of the R.O.fl. ore and boforo any drying of thr ore trkcr. place, this fino notorial is washed euny from the fine rock r.:v? free fibre thus presenting n much clcr.n.;r fino fraction to l!v. dryers. Although some dust is obviously generated during the subsequent milling operation the oust content of the final fIbro products is reduced. CAP CO JEN 0011032 3 This aspect ui.ll bo dealt wish m c laser section. 1.3. O^ncriotion of thn l:?-:h,;.':r! ?? :~f . t The principle upon uhich she washing process is based is to sal exposure. All the hoisted ore is subjected to high pressure water jots on a caries of vibrating screens with progressively diminishing cporturcs. As cosh oversize fraction is cleared it is removed from the process end passed to the mill eitr.er . via tho sorting plant and/or the dryer. The last screen is a combination washing and dcwatorlng screen where tho dust, mic.rofibre and oxcess water are finally removed from the washed fines, with tho water boing recycled after the contaminants havo settled out. Schematically, the layout is as * allows. CAPCO JEN 0011033 4 1.4. Kegel. <_ f.if'i',a Frti't the outset It must bo recorded that tlio results bi.lnw eve prEliminary end based on short u::pcrj.i.ior,tril be fere: ana oft or plant runs. Variations i.n tho quality of the ere froc; underground ns well os tho foot that coma unretlit.d fines r still hoing i.iiK.'ij end thu bn.--.jo f.throe recover u:l from these I!^-ri. in with current pio.duei.ii..i havo pvt .ontiid t, clear pisturr of tin full effect of trashing on .vrirkuteblo grades being obtsj llp.'Mvur certain positive results hoys emerged t.nd era coi.ir.!..-nisei on below. The pattern t-Merging nri fashed one unvoshed basic fj.bre g-td'-c based on Moffett analysis is illuntrctud in table. 1 f.-sJew. basic Grotto 4 I't.r-i i'.*] 14 35 111 53,4 10,6 4,1 H2 20,7 32,3 9,2 25,0 ^33,7 n,i f1/. 19,5 20,6 12,3 H2Q 59,5 7,0 3,2 nuvrrr (ihuitv.tfT;.>:) 100 -100 i! 4 14 1,0 34,0 jj 50,4 7,1 3,1 24,7 |i 29,6 25,6 2.4 25,6 jj 35,4 32,1 4,1 36,5 jj 10,4 22,7 1,7 20,6 jj .to, 6 3,1 *Tf* l'.I 300 3,7 (3,2 ' 111,5 3,(1 2, ii 2,7 3,7 4,1 4,7 2.0 j^ 37 4:3. ' : fSi.11 0 R1 R2 R3 R3F 55,0 46,5 55,9 37,0 6,0 21,0 13,5 3.1,7 3,5 3,0 4,5 ' 3,5 3,4 2,7 9,1 2,6 29,5 jj 50,0 27,0 jj 45,2 23,5 j! 47,5 13,5 || 24,5 12,0 19,3 12,9 27,3 3,5 5,0 5,3 12,5 2.6 w- . 2; 6 27, 2,6 31, *' 9 It is apparent that the reduction i.n tho Minus 105 Po'.'t tt :**: v * - Li'iif.Ii .is s niocsuro of the dust end ricr. fibre content of the banjo fibjo is mure significant in cert: in grades of fibre. Thus the i`2 and i-14 grades on roll A and K3 end R2F' grr.dr.c on mill Ei shei-.' n far greater dsurcaeo than the other basic giv This is hnvavar te bs er.pcctcd so lhauu grades riontcin ' cat i f tho frao fibre contained in the nill feed or.d me tlicrefero :.c prono to coritai.-ination from fines. Tic- other grr.rti uhjcli a;*: basically milled oijt of rock uould ler.u l-v bo unaffected by tuo vigshing process. All tho basic grader, are houcvr.r .hlendad into the final soiling grades at so-nc stage in t.lio fiberjration process arid an imp' cv-:t.:;it in any of the bm.jo grades must tianslato into on improvonent jn the dust, and fine fibre content of the fibre sold. CAP CO JEN 0011034 5 A core in c/cpm jin-`-.L'U.cv-tioft is at nics-onl being under*. r.,;-n t.o establish rv.-lIIv whet f 1 celion cf ikIiius 100 wrtc!isl ir- hf-i rcr.ir.ivcd from l:.e washed fibre, Typical results ;-o far oia illur.Lrated bolcw. RcKtTT (PEZCLt.iiVJz:) Grade 4 14 35 100 400 -400 3F washed 35,0 33, a 9,3 0,0 5,1 13,3 - unwashed 23,4 27,3 14,4 yV. Q ut G,4 22,6 It is obvious that the foir.asset reduction in finn civet in fraction `.bat is finer (by fOrncii .-.n-lyvi s) when -b'.O This micro fibre fraction ir- cji;enily l.oing c-;!:jI Id scopic investi gstiori. 7 ec Ms era end micrc.c-cepic invert.-.!.'.lie: wore also :r i;.i E."plas of Lrcs.'c end bionic;] err:cos in ;:n otca:to !'.11;1 the difference;-* between ihr- ursbvif c'-d wri.wrhcu i w/e, ti- successful pn-cantstiori, chi eh if- i'.iu=tr-sto'j .'.`..v icier on in the report, wee p:epereo as vol.icc;.:- 'Iqucls weights of the two types of firms were dispersed in a snail f.nuwr.t cf us tar in e nlt:;s petrio dish cr.c -.11 -...-fir; tu wry by e: rporetj.on, Ar- u.,=c p:;ijot tar -.-as used to produce an image or; a end photcarr-phs Ir.Krn. Thu f \ a: r-p-f^r'= urr.iplc r- ur.rc- then subjected tc? micrrco.vic c;:. -i.r.'.ti-.n at various mar.nifjcEticrn and - r-;:ri;.-r- of pi,o'.s- . grcp.ns taken of various sea Liens of the samples. Phederrophs taken from the overhead irr lor whew a c'isriirct dif f s-rance bs t-.r an the two samples ir t,.-.? form cf a lmrer coricentration rr fine dual which appd:-,r os s olr-j'J of fin-? matr-rial around the edge, of the dish. Th? tr.irrcFCopi :. photograph? l-are fa'--'. l*i th? rmi-ic r.f .7 r.: to confirm that this consisted of r.r;i'ihrws nr- evil duct and that -.he lower cloud cancer;:: '.f.cn would therefore represent a clamor and nare useful r: -c, r.cnclucloric.. Although er stated earlier the full rf -ct cf t-h**- nshlf-.i of fines ui.ll not fcc firmly established .* 'il all the sorting p3-:.;`.s aro ('edified r.rri otislir.g c.tc-r.kpil*:? :i,' wnnuchr:! ore sn:i bacLc fibre grades ere- worked away, there ir Montii;:: c:-/icenee that tne of feet pf wr.t'-ipg will trenr-ietc i ever all reduction in `.he. r.inuo 100 content of for p.\cr.-plo I'.Lf (: -dr or bntvcrn 6 and 7 percent units. CAP CO JEN 0011035 Tht: -typical shipment vnv.eo would then fell rxvnrr! + 7- inc-tood of the* cm rent 77.;: + 3, The rlTuct of U>iu on civ. t .V-voir; in tin asbestos foment factory no well os thu of feet cn ..ucc-i in an A/C product will hays to bo investigated,- , 2.1. 2.?,. PcaU-rtOUflf?. Bluo sofcsstos fibre has always been nero difficult to bag than Chryec.-ti.le asbestos. Tho inherent physical characteristics of tho fibro* cause it to recover .vie original fiberized vt-iur,`.o whenever tlio packing fores is removed. With earlier pressure pcc!:in\ tcchniiiyp the fibre woe cam;*; c.; ad into o bog and o deep spp.'.ud to 1!:-j top of the bon i:u o ..? v.o prossure kai was withdrawn. Th.'. cl ana would tiu n iu.-l-.: ; long enough for the bag to be c>\:ri cir.s.v.j. On :v. :.v: *,n i lo: -a the fibre would then expand sliebtly until cu-.u-inoi] Ly Ihu s. material itself. This system was used for nany years until it was dee-in;--:' to increase thn surface* area of ficsfeo*s blended fibre. i:..s r.i--:.iv.-;-: resulted from a decision to offer customers a fibre with o nights: degree of opening so that a uinin-um amount of t;.x'-t:,.ent wot recuirad in tho customers own plo.it thus redlining the ;/. l-ant.' fo'.- QCTiorating fibre dust in the fibre i.-i.oi-xiutmt.-iii. r Th.;- increased surface area however brotj'..kt new pi-cbl.:...--; Jri !.h.-.fe tho poly-woven baas cocaine so stxr.tckaO that the r.l :.-:t kn... >; would result in burst bags and exposure o<` fib:;;:. T'r.ir '.-lor, t... .* certain ox tent csuriivcd by palletising thu begs one! uo-.-.o-ii.g t.'.:unit with a plastic shroud. The advent of tho now regulation in the 11,5,A, which spooi containerization for all. asbestos shipped into the country br.-w-i-t with it a new problem. With prsssurs [larking the shipping .*.. of blue fibre could bo reduced to around 1.110 eu ft par ton enabled around 9 tons to to packed into a slnnsoid container. In ardor to obtain n.-xi.r.un csrr.s.vie hsna'fAfc this voltiii.:; !irJ 1. Vs reduced t-/ nearly DC'# to fscilitato the ..ontodnrrizntion of i! c inquired maximum of 10 tons per box. Paling. Gonorol Mining embarked nr. a crash protj'vni on new p;->t:l. >ninn techniques to devrvl.cp a suitable pack fur enntsi nuri::.*' inn. This led finally to tho development of Sim baling tuchiwquu which was subsequently offurud to ond adopti'd by thn rest of t:*s South African bluo fibre producers. noe.lr.nlly the principle used in a modification of the normal balin'.: process ond w-arks oc fallows: *? / CAP CO JEN 0011036 7 ( in--chad films Is loo.'.n)y screu packed into vary strung polyi.ovnn hags. 6 Of these boga oach containing SO kg. f>re sleeked on top nT cnr.li other in the baling chamber. ' Tuo Iiyrlvr.oticsl.ly opw.itt-d dcubio action doors "squEfiaa" the* bulky t*nQ into the char.ibur. *| ]to floor of th chamber is then rai-oetJ via a 11.2 ton hydraulic ran end prnsscc tin:, six bogs op against a fixed c'ir-:.:!?cr ht-oci. Thu bogs afft kept under pressure si.d 3X5 trm round mire streps cn placed ecourrJ the cainproorr.il unit and larked uith me:.:!! buckles, On mle-vina the* pleasure the fibre in the begs r:-:i;ounm slightly arid kicks bsek firmly nnn.inot the straps thus producing a very rigid halo. Six of thann bale:; urn then po.lletireb to for-.n 1,11 tori unite* Ten of' these unit:-. then nr-h-.-. up a cuitainev load, Cuntn^r.r.ation hes feeil.lt.-the door te deer dr' i-e.*-/ of b.ius fibre pr;d vocv.Ay lap:uvrei dust central in the '.-ncine, off loading and roiling operal lens. ft more rcount improvement has Irrun the addition of a iih uire. strap cn each bat a irh.ich doeveorus the overall hrlg-it of a nnl.'loti'-'nd lord thus making it easier te fit the unite :nto a Container. This has reduced the possibility of ripping o;*-~u tiia top bale on ti'.p ridgo above the cio-are of the cciritsisv-.-r. This tcv:: of the l-iggast p-nhlen r.rnac ushen leading eor:lcl.;ar.; with c fork lift in' Tho afl.e.chsd photographs illustrate the late at haling .r-r-ehincs end the units produrud. A3.so included a-.-r: r.cime cr.:r.pc.ri?ons of the. old and neu typo units cheuing tho ccjiu.i durable height end voluna.* cavings that have been achieved. Pa-ksni ro_ Rate fork in continuing on the risvotepicul o! suporie' quality pelyViVjcr: lu'go and l**rt ship.vnnts of vatic.typer, o*. pulywoven beg.-. x'o currently in t|;o pipeline. In addition a sai.ilU'lc pulpabln papal* sack h-.a been developed to withstand the haling process. This ci.l.t f.'icil.it.:;te the contii.h'ieririd rluj'.rntc of Lino csbecl fibre to these cur.tof.-ors uho nice to dump In;** sealed hag end h.:* * ill car.My into the hyvrapulpr.-cs, The rod::- if on in r!u:.t level:; hi the incoming' fibre ser.'..':: i-hcu.lu ha substantial. Vent :.:ij-!.sjiifca nro s ru.'-.i/ in thr pipaf A .ir. CAPCO JEN 0011037 1ST llSfiSKltiC scF.iiru COARSE NATLRIAL / UAMIS! c:- r:tiEr- CAP CO JEN 0011038 HASHING PLAi!Y CAP CO JEN 0011039