Document 7Ogv5O1XMbEVdqOajdbLRxmoo

G's>W' / *. VJ Physical Properties end Technical Applications'of. Asbestos llinerals M. S. EADOLLET, Health Research Institute, -Fs+ffsigh Dickinson University, MadisunrKsv.' Jersey, U.S.A. ABSTRACT The study of the physical properties of asbestos minerals requires a care ful isolation of ti.c fibur iron litc wall rock and, at i later stage, a compari son of these uhysiral properties with those cf fibers that have parsed through the milling and uencficiatiun p: n.-esses. Olio effects of mineral impurities, ioss of fiber length nut! the formation of. extreme fines (ashes! ic and/or associated miueia!'/ often slmw up i:t the formation of sp.-cir! asbestos products as vrll aj in the commercial uctinn of asbestos papers, milltU, asl.r-stoa central pioducts, plasties er.d iusuiatioi. materials, and in the filtration of hl'i.-.ii plasma and wines. Nur.'.ei ous isst inethc-i-t have boon developed in Canada and in England, for use in (ho asbestos industry. Spe cial treatments of asbestos fibers hare beer, used to improve t*-eir phy sical and chemie:-.! properties and to eliminate impurities. Numerous problems connected with the use of asbestos fibers are dis cussed, such as the effects of Asbestos on filtratem. surface rr?a. surface treatment., Ls.iug organic or inorganic materials, the surface charge cn the fiber, the presence of magnetite am! air pollution clin'ination. Introduction use/ of tjte'rtiaiaris.K. tlia author _ ., --would-hope liiiit it m.av hi* cf some Tins J-APKB w intended to oxter se,vics ij; s,,-.cst;np Wi2a t0 comment on the p.ij&tca. punyties of asbestos minerals it. reiatioii to ihe many diverse industiiaftises of ' these min'-rats. A.s the author is a chemical engineer, the material is presented fi 0:11 an ei:-' gmocr's point of view. However, in dustrial hygiene -work it. the" as bestos industry has ct'iniitd work by many physician.-, and blc'-jyists These medical scientist;; tend to focus their i:;lertsls on the re sponse ol` tissues in max and in exporimantal iir.irm!.-:, but often have limited familiarity with ihe chem istry, physics r'd technic?.: aspects of the niir:cr-Vvi.'.':;il l.iT'eria! with which they work. Siniik.riv, er.gir.oar-; familiar with the n.r.t.'"ia::, often have limited ind<v`*-tar.di!.y of the laujfii.vge and techniques nf the medical scientists. This gap inny da!ay asking t!iu right ques tions to arrive at solutions for in dustrial hygiene problems. Al though the prc-s-Ti't paper is con cerned with the pse-periies and (i103e invest.-'; vi in" questions as to how those mnfenals behave- ir: biological systems, how they me diate btinugival- responses and hew such '1 esp-riscx miiy b; ir-iiunuzud. The author d-cs noi. propose to pres^ju... lljeut -os - /or - bioiogiv.'.l mcctiaiiij-r.'.s. and trust!- that ;-,U co'iteayi.ies n industry will no*, slop reading at this point, a> the pn~;-r >s ini'enc'i.-d piimrri'y for them Jl might be .icle-1 at the out.-ev tha-:. in *:. lilion li. !ii--. coiieitlnrati-iii of dificr.--.;1 >roI''.r,.n:-.; of *Uff-ier.t vai :ry0/ r.-d-cste:;. vh'ch influciice the!.- s..k-i-ility rnti use for vu.rioi.r ii.-.:. s'.ri:.'iiriix-:-'!. the ver.r.-or- of . .-.besto.- fihcic v-jfh jrj. cr-iiiiiic or -.-t-.-nic cer.i::o-:iid.. car: improve t:b-.-i pvupu'.'ties for spccia' uses. S!ich .1. r-fijcing the i.ydrc-!'-sis of ch.ryso'.ile in water. Rraele.fibers can uffcci texture au-I fiilratior. propt-vtie:. r.:.d ir.rrr.ara pro duction rates of ashc-elos ce'iHhl products, lu-ytrs. miiibnf-vds ar.d other wet process isrodr.cls. Biological studW on finely ground asbestos, when dispersed in 0.9 per cent sodium chloride solution and then sterilized and ir.jertvd into hamr-ters, show that by reducing the <l-..'=c, the tissi> d imr.ge can be irrgely avoided. In tb'-e experim-pts, Aiiaena asbes tos fibers were carefully extracted from t::c wall rock, finely ground, ami. examined rlieniieolly a:.d mierns- Copically fur an..- miner:1.: imparities th.it r. igi.t he pres ml so that any affiol the h.-Msiers we-:id he di- rcc-. (':- to pre.v.-i:ee of t!,o The h-v.! Ari-. -r. fih-r ia- c'-.ve'i wire e.e I:.-.;--- rr.j .v-s :iset; fi: er v.k:!, 1.-.*..:! in lian.-.'-r-,. SUBMITTED TO THE CU.M.: in b,,x>tciiibar ci 3 t1!JR. ORIt'INAT.T.T I'ilESENTED: in part at the Copfcr-rsco on I-uysi;-* and Ohou-isliy of Asbestos Mine.a:.--. C>\-lorn, July 20, 1U07. This work -..as supported in part by U.S. Public Health Service E-.'sc.'.reh Ci-anl UICnin! fi-.ia the Bivisixn of Ui b;.:i and lndustri.il H'.-.iiti:. KriV". 0-IP:- : 1.r.'.i: ::r.:... As- l.-xl.iS c;-l.t. I'--.,,!-.tl si. i-'iitr: Lh-VL-'t::-. Sri'..-. I-..-O - !' "It, A-,', ex-'-- II......................... S. Selcidiun trad Propp.raii.-ju f fiiiripi;*; For fund::mani:-.! stiuliss on the physical nr bii.k-gic.-.l prcp-.vl-V.- uud technical use. of asi..`.<:c..-. err.l--, seli-ci?o:i a*su i.-ivp-.-idi-i! i.*f crude uie.- is the first .:l.;p. Tl.-it should be dune by sii.iior.ne ty.i-i- iiiod to examine u.-j ore d.-pv-dt mi.' its r-x-.kiyicr.! f-jriK.nio:!. t-i cote till j-i- :--;ei:ce t'yk-.--. las. v in;;. hi tii..:.: 15 s.r'i a::::-.;-;::s in r-tl-- I'k.'-y ASARCO ELP 0003525 asl-eitos fiber-. This type of exam The amount of extraneous mate writer in an Arizona underground ination often furnishes valuable rial in a bag of commercial asbes mine brings out an interesting lends to the physical properties of tos fiber is rather surprising. From point. The area containing soft the crude asbestos and the com Hu viewpoint of the quantity of fiber (chrysctiie) was free of mercial fiber, and its use in indus pure asbestos, it can vary from a faults and the fibers were well try. few per cent to TO or 00 per cent, formed, with a strong flexing and Asbestos fibers in the form of depending upon the grr.de. "'his ex I ensile strength. .About 20 feet crudes or in drill core should bo traneous material consists of away, where a series of faults co- opened by hand for laboratory tests broken pieces of wall rock, magne Ctirrcd, harsh chrysolite was noted. to avoid fractures. If further proc tite, brucite, small sizes of asbes These fibers were not weil formed, essing is necessary, they can be tos fibers, dusts and closely as showed a weak flexing and tensile opened by a very mild widowing sociated minerals in various forms. strength and,'after processing, lost action. The method of mechanical Asbestos mill surveys have been length and produced a considerable opening of the crudes will vary, de made by checking the flow rates amount of fines and dust. The soft pending- upon the variety of asbes throughout the mill and collecting fiber contained 13 p:1' cent mole tos. For example, soft chrysctilc samples at each station for a pe cular w liter and the harsh fiber 12'- may require more vigorous treat riod of several days. The samples por cent. Filtration tests showed ment than crocidolitc or amosite, are composited, weighted and tested the soft fiber to be slimy cud dif and anlhophyUite and tremolite re by the various test methods avail ficult to filter; the harsh liber quire even milder treatment to able to obtain some idea as to was not slimy and filtered rapidly. yield comparable fiber lengths. which milling unit is damaging the This type of harsh fiber was re- 3Iore research should be applied fiber and producing fines and dust. commended far the fiUraitou of to the process of opening asbestos The McXott net classification*'1 wines, either as straight fiber or in ores so that the maximum fiber method provided the best evidence a hlcnd with soft chvysotile or cel length can be preserved and less of this. At the completion of the lulose fiber for filter pads. When fines produced. survey, the mill foi emau is told the filter pads contain 100 per cent Although samples prepared di which equipment is damaging the soft chrysotile asbestos, the fil rectly from ores are valuable for fiber. He can then regulate the trates are. relatively tree from col fundamental studies, most tests in equipment to improve, change or loidal particles. As the quantities industry are necessarily trade with eliminate the trouble spots. of cellulose or harsh chrysolite are commercially milled samples. These increased in the asbestos blend, the milled samples can, of course, con Fiber Testing tain a variety of associated min filtration rates iueiease and the fil trates are not as free* of colloidal erals that can affect properties and uses. Milling and Bcneficiation In milling plants, large quanti ties of ore, consisting of fiber, wall rock and many associated Minerals, are crushed together. Some kind of mechanical separation u therefore necessary later in the milling process. Preliminary sorting of crudes from the rock is helpful in 1 educing contamination. Water washing processes have been in stalled in some cases to reduce lionfibrous materials and to direct the cleaner fibers to one milling line and the dirtier fiber ami shorts to another milling line. In any case, a complete elimination of the as sociated minerals is extremely dif ficult. They can be objectionable in the manufacturing of some prod ucts. The bulkiness or degree of open ing of a fiber will govern the abil ity to pressure-pack the fiber prod uct for shipment. For purposes of industrial liygic-r.e, pressure pack ing is of value in reducing dust in the atmosphere and on the packing Neutron activation analysis'" has been used on several occasions to identify trace elements in samples of chrysotilc, amesito and crecino.lite. For example, one series of examinations showed that chrysotilc, amosite and crocido'ite all contained manganese 5G and sodi um 4; antimony 122 was present in amosite; chromium ?! was pre sent ir. chrysolite and amesite. but not in crocidoiitc-; iron 50 was present in all three samples; anti mony 124 was present in ail three fibers; scandium 4G was present in all three; and cobalt GO was present ouiy in chrysolite. Apparently the radioactive sodium 24 was produ ced from the magnesium which is a normal constituent of asbestos, `and the radioactive cobalt GO came_ from the nick-'l which i# an impu-` rity in the chrysctiie. These trace elements become important if the snmnle of asbestos is to be used in the filtration of wines, beers, blood plasma and pharmaceuticals and in biological studies. Therefore, a pre liminary acid treatment le remove trace elements would be desirable before utilizing asbestos for such filtration purposes. Attention to trace elements in samples of asbes impurities. Test methods'111" have been de veloped for determining the filterability, surface aica, colour, grit, dust, length, degree of opening, wet classification, tensile strength, magnetic rating, volume resistivi ty and conductivity of ashc.stjs. They do hot give the idoatiuention methods for d..ter!r.ini'g the as sociated minerals pr-'sonl. These methods arc printed in the form of a booklet and are avai'uble for dis tribution by I'm Quebec Asbestos Mining Association and by ('ape Asbestos ribcis Ltd., I.mxion. Some of the other tests involve the use ci -.he el-'ctvc;; inwrcscons. X-ray diffraction, different8::! ther mal and infrared spectral data to show differences in the fibers that are net shown by other test, meth ods. The effect of opening asbestos fibers"1 and measuring their pro perties as the fibers are opened more and mere siu.-v s wiir.t can happen in a factory where pi Mes sing is necessary before the filer cun bo made into a commercial product. For example, an African blue crocidolitc, Rhodesian chryso lite, Canadian -semi-harsh cliryso- floor.' tos may be of particular importance The hooding of equipment whereever possible will also reduce at mospheric dusts and improve work ing conditions. in biological studies for effects of asbestos on tissue, particularly in tests for carcinogenicity. ' A set of samples taken by the wDetormiiic-J by thermo-gravimetric analysis u?iug the Thcrmoanalyscr. (Settlor Instrument Carp.. Prince ton. X.J.) f C'hW) Eansiifl fzt April, 1ES3 433 ASARCO ELP 0003526 J v tile, Canadian soft chrysotiie and a Surface treatment of a slimy chrysotiie fines to any one of them Canadian harsh clu-ysoti'e show, as soft chrysotiie can be accomplished brought about complete floceuleticn the processing continues, that (X) by.the heat-treatment process, by in a short time and filtration was the length lias a tendency to de an acid treatment or by the addi improved. crease, (2) the dust or fines con tion of sodium silicate"11 and flash In the early forties, a Swiss en tent increases, -(3) the buoyancy drying'1". Wetting agents'such as gineer developed a method for the increases, ( J) the density decreas polyacrylamid (Separan XP10) clarification of raw sewage in sera- es and (5) the surface areas in and aromatic sulfonate (Tamol N) tion tanks. He added chrysolite as crease. Therefore, the plant fore have been used to floe the asbestos bestos to cause flocculation and, at man must know just what degree fiues, improve filtration and re the same time, increase the surface of opening is necessary to obtain duce fiber losses.- area "so that bacteria could grow the best workable slurry for his In some cases, dispersing agents rapidly and aid in the digestion of machine to produce a satisfactory such as Soda Lig or Blanccl are. the sewage prior to filtration. Ac I- product. added to the tanks containing t.he tually, with the chrysotiie being The presence of magnetite can asbestos slurries so as to keep the electropositive and the sewage elec \ J 1. be a serious problem, depending up asbestos from settling and present tronegative, it was a case of using on the use of the fiber, especially a well-dispersed suspension that an appropriate amount of fiber to in the electrical insulation field. can be picked up by the wot ma neutralize the negative charge and Magnetic- rolis and a sudden flash chine process. The amounts of obtain a quick flocculation product of high-intensity heat have not these reagents are kept small -- that settled rapidly and was later been too successful in removing or just enough to accomplish the de removed by filtration. converting the magnetite to ferric sired effect. Excessive amounts Oil-.vell drilling produces chips oxide, which is non-raagnctic. can cause frothing at the pumping of rock particles and mud. In some Methods of testing for magnetite station and defeat the purpose of cases, clays and/or asbestos fibers have been proposed'*1 <?1but flocculating or dispersing. There are added to form a viscous mud to there is still room for more inves are times when it is necessary to collect these Jiai tides so that they tigation. open the fiber by additional grind can he brought to the surface ing. In that case, such agents as where they are removed by screen Decevasol OT or Alkanol, when ing or filtering: the cleaned mud Fiber Treatment and Effects added in the proper amounts, can is returned to the well. In this speed up the opening. ' case, the positive, charged asbestos The field of sonics offers some interesting possibilities for openingasbestos fibers. 1-afcc.ratqry tests show that it can be accomplished. The treatment of asbestos fibers, auch as amositc or crocidolite, by inorganic or. organic liquids may alter tlie physical and chemical pro perties suffi'-:o:itly so lha* new ap plications may be found. By soften ing the stiff wiry properties of these, two fibeis. their importance in textiles vi!i be greatly increased. Adsorption of organics by chrysotile asbestos was reporcr.d by T. J. Weeks and J. P. Leiinvcbcr at the Oxford conference cu asbestos in July of 190T. They used a BriceFhocnix differential reflactometer to measure the changes in the so lute concentration. Opening in water using a Waring blender1" is a convenient method to prepare fibers for some types of tests in the laboratory. The sam ples should he -washed with alcohol and ether to remove any polycyclic hydrocarbons and the bon?.o (a) pyrene sometimes found associated with asbestos. The reaction with soaps such as stearates or olcalcs"'1 can produce a water-rep'.-'.luni effect cu the sur face of the chrysotiie -- in the form of a thin l:i\er of magnesium stearate or ol.'utc. Textile ehryso- There is one point that must be remembered. Doss the use cf those agents in the presence of asbestos cement lower the strength of the finished asbestos cement products? If so. it may be necessary to avoid them entirely or-use leaser quanti ties. Asbestos fibers carry a surface charge -- cither electropositive or electronegative. Baring the nine teen thi'tics, chrysotiie, nmosite, anthophvliita, c'-ocidolite, .trcmokle and. actinolitc were ground to a fine powder and tested in a cafapheresis cell using the ultr.-ur.-'croscope. Chrysotiie- was observed to have an electropositive charge in distilled water, and all amphiboles were electronegative'"'. It has been suggested that the electropositive charge on commercial chrysotiie is due to aluminum or iron ions and that the charge on pure chrysotiie approaches the electronegative side.* Chrysotiie fines can be neutral ized or brought to the iso-electric point by the addition of cloclronegativo particles. This can be fol lowed by the movement of particles, as observed in the cataphoresis celi under a given potential. Per exam ple, although diatomaceous earth, cement ami other particles were all electronegative, the addition of may have helped in forming large floes that hold the drillings. The colloidal properties of asbes tos"*1 and zefa potential measure ments"'1 have shown that the charges do wrist and can be re versed by adding -ime ii.org?.ni<* reagents or l-y changing in the pi I. Hodgson"*1 measured the charges on crocklc!-tc and amositc. The crocidolite had a weak charge oi r-IOmV and amositc a weak charge of --2Cr.iV. vherras Martinez and Zuci.er -'131 hr\vcd that chrysctik had a strong positive charge o -t-lCOniY, which may be a rather high value. In < he production cf certain type* of cebulcs-e paper ot. <.!ij)g addition of chryso tiie asbestos, with its electroposi tive charge, was helpful in retain ing the negative-charged TiO, and at the same time furnished a high surface area. In the case of another type of paper, the asbestos must have the rubber latex deooaited on it while in suspension. Here again, the negative-charged latex is held by the electi-<ipositive chrysotiie during the sheet forming process. Physical Proper* ic-o and Applications of Asbestos Chrys'.fille asba.510:5 is the prii cipal fiber u.-cd in many product: t:!e fibers ;-t ore mM-s were treated because cf its pi ivsic.-.l ] ir-iprrti; by soap, v.-ilh t::. roving l--.ter used and avaiia For ?erne pu: Co-'orii!;-: electric..! iu- nitM-ik, T. >1.. "Control of Colloid Sinhuiiy Tbrf-a^h Zvt- i'(''.;:f {*0503, it i' sum::s.-.ed bv sever. amphiboles tii.-.i I:eve si ml ASARCO ELP 0003527 pc:<ic-s that give them particular icles, and metallic particles from advantages over c!;rysi.f:Ic. The ad metallurgical and snic-lting plants. vantages of ehrysotile asbestos, Extremely fine asbestos fibers may however, are generally greater than be added as a precoat to the bags Us disadvantages and, consequent* to increase the efficiency of re ly, chrysolite is used in most prod moval of particles polluting the air. ucts requiring asbestos. Chrysotile These fine particles of asbestos asbestos can have a large surface may be precoated onto glass fiiter area, high strength, resistance to bags or cloth filter bags iu the bag- elements of the air, and flexibility, house installation prior to placing and it mixes well with resins and them in use. cements and does net support com bustion. The texture of asbestos fibers varies from very soft and silky to Miscellaneous semi-harsh, or even to a harsh, Technical Applications splintery, brittle type. Quite often, The presence of grit, whiskers, the fiber source of the ore will re fiber bundles (unopened), magne veal what has happened during the tite, brucito and micaceous mate original crystallization period. The rials in commercial fibers may be presence of dykes, faults, mineral impurities ar.d crystal formation objectionable when incorporated in a binder to be used in a spray also furnish clues. Host harsh as gun, such as for sprayed ur.dor- bestos fibers have less water- of coatings, and coatings for heat and crystallization, and this is partic sound insulation and fire protec ularly true of harsh chrysotiles. tion. The asbestos must have bulk The soft chrysotiles are slimy in and fluidity with the binder. water, hydrolyze slowly and are Caulking compounds are sensi extremely difficult to dewater; the tive to texture, foreign materials harsh fibers can be dewatered ra and changes in grades of asbestos, pidly. Advantage of this knowledge caa be utilized in blending a harsh or semi-harsh fiber with the strong soft ehrysotile, as in the produc especially when applied by a gun. Wall-joint fillets using asbestos must have good bulking value, good coverage, a smooth texture and be tion of asbestos papers and asbestos free of whiskers, grit, magnetite cement products, blonds of amphiboles such as amosite or crocidolitc with slimy soft ehrysotile can be very effective in increasing pioduetion rates, provided that the and micaceous materials. Asbestos in paints must be free ' of grit and whiskers, ami must be uniform in texture for ihe lest ap plication. strengths of the end products con Plastics and molding powders are taining these blonds are not seri ously affected. very sensitive to the.physic.il pro perties of asbestos, even to the Thin asbestos papers for elec presence of moisture, l-ra.-iie. as trical insulation should be free from grit, unopened filer bundles, sociated minerals, iror. and offcolour fibers. For example, the magnetite and'brucite. If these im purities a>-e present, they wiil ap pear on the surface of the paper and produce weak spots whan the paper is wound or wrapped around a wire carrying electrical current. fibrous structure will increase the impact strength, allow a wide range for adjusting the quantity of fiber, furnish, good binder reten tion and good workability, impart hardness and toughness to the Air pollution is an important .moldings, increase heat and fire problem today. Its study involves resistance, reduce deformation, the collection of large volumes of make cold molding possible by con air in and around plants, mines, trolling the flow under pressure in mills, subways, tunnels and points the molds, permit the blending of of heavy traffic congestion. If as mineral and organic fillers, impart bestos is thought to be involved, a good finish, improve electrical then sufficient solids must be ob properties and reduce the coat of tained for tests by ail available molding. The presence of ir.;:: in procedures, including electron mi asbestos will produce off-colour croscope, spectrographic, infrared plastic products, and a chelating and neutron activation analyses. agent may be necessary. A stabil New micro tost methods must be izer for asbestos in plastics should developed to complete this type of function as a heat stabilizer, as an investigation successfully. antioxidant and as an ultra-violet- Asbestos, glass, cotton or wool, light absorber tc be ideal. in the form of textile filter bags, The thermal insulation'1"' proper are sometimes used in plants to ties of asbestos have proved to be recover fly ash, radioactive part important in missiles and sa* ami us special packings it; at:.cue energy equipment. In asphalt paving'1'1, ihcstrrr.grIt, reinforcing and ah-orptive properlies of asbestos have resulted in an improvement in the plastic strength, tensile strength and sta tic compression and a decrease in the cracking properties of thin films of asphalt filler mixes. Other Applications of Asbestos In many asbestos products, it is Hie reinforcing effect of asbestos that is needed and not the non-fib- rous materials, which would be con sidered as expensive fillers. If fil lers are needed in a product along with asbestes, they can be pur chased at a lower price and under a manufacturing specification. The foreman in a plant that is using, asbestos to produce a commercial product must have some idea of the quantity of pure asbestos that is available in a given grade of fiber. Then, he will knew whether to use rao-'e or less fiber ia his formula. Although it is true that the extra neous material may aid filtration, it- will contribute little toward the strength of th-' product, and is thus an expensive method ef obtaining Inis effect. In the case of manu facturing floor tile and pie-stirs, it is important to know how much true f;er is present to obtain the maximum re"nforcing effect. Toe much tine fiber will dry up the mix and require nor.: expensive resins; cu the ctne. hand, the fore man can reduce the quantity of fiber ar.d -.lie !c-m- ivdu to obtain the consistency desired. Commercial gr-.dcs <<f asbestos fibers have been hi.proved daring the past ten years, so chat there is less extraneous material present in a bag of fiber today. In general, ehrysotile asbestos has the widest use in cotnmeicial products such r.s asbestos cement, flooring materials (asphalt and vhiyl tile), papers, millboards, roof ing felts, textiles, automotive prod ucts (brake linings, clutch facings and packing; and many miscella neous items. Fortunately, the phy sical properties of chrysolite make this fiber ideal; however, some am- phiboles (crocidolite and amosite) are becoming important and are re placing ehrysotile in some prod ucts. In the spinning and weaving of asbestos fibers the softer varieties -- i. they do not break (CIM) rialalin far April, IS S3 <!35 ASARCO ELP 0003528 i i . j. : 5 up in tho processing: equipment. Soft chrysolite, causes the least trouble; harsh chrysotile will show considerable loss due to its brittle ness. Crocidolite can.be spun into yarns and cloths by modifying the textile equipment so that the stiff and wiry properties of crocidolite can be handled. Amesite is of lowflexing strength and is usually formed into mats and later treated with resins, depending upon its use in industry. The tensile strength and flexibility of asbestos are also Important in spinning and weaving applications. Where acid-resistant packings are required for acid pumps, croci dolite, the most resistant of the fibeis, can be made into all-blue yarn and impregnated with a re sin to form gaskets or, if required, it can be formed into millboards. Crocidolite and aniosite fibers, when in the form of cloth, pack ings, yarns ar.d baggings, and when treated with inorganic binders, can withstand temperatures higher than 4S0F. Reinforced plasties using croci dolite show good chemical and water resistance. For heat insula tion, amositc is very useful due to its open volume and the fact that it contains air pockets. It is also used In reinforcing magnesium- or cal cium silicate in.-utstion, where the filtration problem is greatly im proved by the presence of this fiber. Antiiophyllito asbestos n3s good heat lesistance and acid resistance. It has bean treated.with resins and used in plastics. Although this fiber docs not have the strength of chrysolite, crocideiite or araosile, it has good bulking properties. Some anthcphyllites are mostly iron-free ar.d almost, white in colour and arc desirable in some types of plastics. Tremolite, after an acid and caustic wash, js considered as a good fiber for .use in the chemical laboratory for filtering chemicals and is sold for that purpose. The physical properties of actinolito- are not too attractive. It is a weak fiber, usually associated with other minora:*, and would be considered as a cheap filler in in dustrial use. Sumo Curry-ovc-v c? Ind a?t j-l.v.-rlcnr a to Biologic;:! E>:pvr:1::rnIrtior. I'eoj.le in the asbestos industry have long bwn fas.iilir.r with th.; slimy suspensions formed by soft chrysotile in water in contrast to tho rapid set! ling of harsh fibers. As indicated ir. the preceding dis cussion, it is this difference in physical properties that favours the use of harsh fibers in'certain products, such as asbestos cement, where it is desired to have water filler away rapidly for faster set ting. As also mentioned above, the author had taken a set of samples of harsh and soft chrysotile ores from a mine in Arizona. Fibers were hand-picked from these sam ples. The wall rock was cut away and the fibers were washed and processed to mean lengths of 30 microus in a Waring blende-.:-'". An aliquot of the processed soft fibers was heated until it lest the property of forming slimy suspen sions in water. The samples were then turned over to Dr. V/m. LI. Smith at Health Research Institute, Fairleigh' Dickinson University, Madison, New Jersey. Dr. Smith's group has found thaf the injection of sterilized saline suspension:: of some preparation* of asbestos into the pleural space, the space sur rounding the luncs cf hamsters, elicited scar formation, (fibrosis) and, occasionally, tumors (meso thelioma s)a". Working with the specially se lected and cleaned fibers of Ari zona chrysottlcs, this group obser ved that the slimy character of sus pensions of soft chrysotile in water carries over and persists in depots of this material in ii:c- pleural space of hamsters, whereas t'.osols of harsh chrysotile become dry. There was much move c tons'c-.sear formation aid more rapid de velopment of tumors around the depots of harsh c.hrysot'h than around the soft ones. Tbs heated aliquot of soft elirysotile induced no more rapid development of. tu mors than the unhealed aliquot, but tended to cause thicker scars than tho unhealed soft chryso tile"" In hamsters injected with a large (25 mg) dose of liiush chrysotiin. tumors developed in 21 par cent of the animals. With a smaller (JO mg) dose, tumors arose in only 9 per cent of animals. Further reduc tion in dosage to 1 mg elicited no tumors at all'"'. In hamsters injected with 10 mg of amosilo. the yield of tumors was again 9 par cent. When cnly 1 mg of amosilo was injected, muse of the animals developed tumors'"'. .The finding Unit hamster.- would - ' injected with asbestos provided a test spe cies of demonstrated susceptibility. The follow-up experiments with graded doses afford evidence that tumor risks in operations where they may exist in the asbestos in dustry cm* he avoided by appropri ate measures to i educe the amount ox- exposure. Different varieties of asbestos fibers have been assembled and prepared as standard samples by Dr. it. E. G. Rendull, Pneumoconio sis Research Unit, Johannesburg, South Africa, in collaboration with Dr. V. Timbrell, Medical Research Council, Llandough Hospital, Pcliartli, Glamorgan, Wales. The Pneumoconiosis Research Unit is making these samples available to those interested in wc-rk on tho biological effects of asbestos. CONCLUSIONS This review illustrates that any operator- using asbestos minerals must keep is: mind many factors that may influence his final produet The undesirable effects of mineral impurities may nead con trol. Fundamental studies an the changing physical and chemical properties of asbestos have de veloped new use:-, an:: undoubtedly will de velop more. Improved milling techniques can improve the quality of asbestos fibeis by preserving the length and producing er fines. Treatments of asbestos with hu 1 or with inor ganic or crganic compounds ca-i aise improva fiber: xor specie1 ur-c-s. By taking advantage ,-,f the dif ferent texture-: of different asbes tos fibers, such as harsh, rcr.iiharsh oy soft, improvements can bo made in wot processes. Many methods for physical auc! chemical tests of asbestos minerals have liven propesad by the Quebec Asbestos Mining Association and by Capo Asbestos Go., Ltd., Lon don, .and a>-e available from those sources. Electron microscopy, Nvay diffraction, and differential thermal and infrared spectral anal yses bring out differences not shewn by the usual test method?. Some biological differences in re sponse tc harsh ar.d soft chrysotile were noted. Harsh fibres induced more extensive sear tissue forma tion in hamsters than soft fibre?. Tissue damage was pru;>arU<-.:ir.! to the amount of fibre injected. 43o T:.s l-y}:v: Vl.. ::-i nv(::i^Ivri ASARCO ELP 0003529 11) Manual of Testing Procedure* for Chrysolite Asbestos Filets, Asbestos Textile Diitilute, Que bec Asbestos Mining Associa tion, Thetford Asbestos-Cement Products Association. . (2) Private communication, Enybes- tos Manhattan Inc. (3) Test Methods for flint and Amositc Aslectcs Filers, Cape Asbestos Fibers Ltd., London. (4) Badollet. it. S., "Processing As bestos Fibers -- Effect Upon Physical Properties," C./-V. Transaction!}, vol. LIII, April, 1950. (5) Nicodcmus, P. 0.. "The Signif- icance of Iron in Asbestos Mate rials Used for Electrical Insula tion Purposes," AJd.TJI. Bull., Apr., 59, p. 02. (6) American Society for Testing Materials Test Metlied D 111S57, Magnetic Rating of Asbes tos Used for Electrical Pur poses. (7) Badollet, M. S.'v and Edgerton, X. \V., "The Magnetic Content of Asbestos by Magnetic Separa tion," C.I.M. Annual General Meeting. Quebec, March, 1901. (8) V/romski, J,, "Magnetic Rating of Asbestos Fibers by a Magne tic Force Method," S.P.I7. Jour nal, Vol. 19, Mo. 11, Nov., 1903. A., "Preparation of Asbestos Fibers for Experimental Use," A'cio York Academy of Sci ences, Vol. 132, (Art. 1), -lot455, December 31, 19':5. (10) Badollet, M. S., U. S. Patent 2,003,219, Jan. 19. 1937. (11) Martinez, Edward, "The Effect of Sodium Silicate on Filtration Rate of Asbestos Fiber," C./..U. Bulletin, Ycl. 57, pp. 1042-1014, Oet., 1904.. (12) Pundsack, F. L., and Rcimshusael, G. P., "Method of Improving the Filtration Characteristics of Asbestos," U.S. Patent 3,173,831. March 18.19G5. (13) Badollet, M. S., "Asbestos -- A Mineral of Unparalleled Pvopcttics," CJM. Transactions, Vol. LIV, pp. 151-100, 1951. (14) Pundsack, F. I,., "The Proper ties of Asbestos, I. The Colloidal and Surface Chemistry of Chrysctile," Jour. Phys. Chcm., Voi. 59, pp. 892-S05, 1955. (15) Martinez, E., and Zucker, G. T,., "Asbestos Orebody Minerals Studied by Zeta Potential Meas urements," Jour. Phys. Chcm., Vol. 64, pp. 924-923. 1000. (16) Hodgson, A. A., "The Surface Properties 'of Asbestos Fibers," Asbestos Mag,, pp. 2-14, Mov, 1965. Hodgson, A. A., "Fibrous Sili- i.i'.j;'i!r'!cs,- me Buyal In.:: tints of Chemistry, Lecture Series, X amber 1, Al>! 23-30, 9-10, 20, 1005. ** (17) VAillery, R. G,, "Effects of Chrysotiie Additions to Coltulo- sic Paper," Tappi, Voi. IS 92A-5S. 1905. 11 (13) Xatmnmn, A. 'V., ``Properties of Asbestos SuitnbU for Use in Ccltulosic I'apor," Tuppi, Vol. 43, Aug., 1905. CIO) Fcigley, D. A., "Beater Satura tion of Asbestos Fibers," ILL Patent 2,759,313, Aug. 21, 1950. (20) Badollet, M. S.. "Asbestos.." En cyclopedia o* Chemical Tc-li- nologij, 2nd Edition, p. 746, l'n- tersciencc Publishers, Xow York, 1003. (21) Smith, V/. E., Mi!!e:% I.., Elsas- ser, E. E., and Hubert. D. D.. "Tests for Carcinogenicity of Asbestos," Ann. S'cio York Acad. Sci., 132, (Art. 1), pp. 450-433. 1905. (2?) Smith, W. E., Badollet, M. S., Miller, L., Hubert, D. D.. Laa ger, A. M., a.:d Churg, J., "Com parison of Eiologlcal Responses to Harsh and Soft Chrysolite," (in press). (23) Smith, \V. Y... Hubert, D. D.. Miller, L.. Badolh-t, U. S., and Cliurg, J., "`Tots for Threshold f.evels of Ca. einogeuicity of As bestos,'- (in press). * * ** --? f 1 fj r-. 1 ,vi f L-V) X.y 4 t\ f <.v-iaO "V 4 ?. f fl v-\ ya S I (** f"** fi*- /w it J ,'1J:) J- 4' o Sao Paulo, July 7-12, 1039 l'iiE CexcRESi of the Brazilian Society for Metals is to take place during the week of July 7 to 12. i960, and the program is to consist basically of the follow ing: I--Open Sessions, with subjects freely discussed. II--Technical Lectures, comprising specific technical subjects, delivered by world-wide experts, ill--Technical Papers to be presented by the authors, followed by intensive discussion. These technical papers may cover any branch oi metallurgy -- extractive or transforming, ferrous or non-fer rous ir.etal3 or physical metallurgy. At present, the program is still at a tentative stage and the following topics were suggested: For Open Sessions 1 -- Training personnel for the metallurgical industry. 2 -- Materials for cutting and forming tools.3 -- Development iu the production of copper and nickel and its alloys. 4 -- Problems and techniques relating to the operation of blast furnaces aiming at ihc lowest possible coke rates. 5 -- Problems i,dated to the supply o* cast iron, ar.d malleable and nodular castings !o tiie automotive incv.si.iy. For Technical Lectures: 1 -- Six exam pies of rather startling research in physi cal metallurgy. 2 -- Mew developments in the extractive nivtailurgy of non-ferrous metals. 3 -- Investment and financing problems- fer the metal lurgical industry. 4 -- Strategy cf research in the metallurgical industry. 5 -- Present state of continuous processes in steel pro duction. 6 -- Precipitation in steels. 7 -- X*:w ceramics. 8 -- Solidification of metals and alloys. -9 -- New techniques in mechanical forming -if metals. 10 -- Present status of techniques of continuous casting. So far Prof. Robert F. Mcl.1. Prof. Arthur G. Quarrell and Prof. ICai Grjothein have already confirmed their presence and accepted the invitation to deliver lectures. Several technical papers from foreign au thors are expected. For additional information, contact the Organizing Committee: P.O. F.ox U-703, - Sao Paulo, Brazil, S.A. (Ci:.i) far Atrif, TC3 . 437 ASARCO ELP 0003530