Document 99jaV0oXmNweN5vVMX6BJKR9e

FILE NAME: Rogers Corporation (ROG) DATE: 1960 Sept DOC#: ROG036 DOCUMENT DESCRIPTION: Report from Society of Plastics Industry - Asbestos Reinforced Plastics  \ **)**. * . t b . *bydt f i a H fg| li S3&b "-,. ; v i3 'v . * . Fit>rC h .r .ctoriotlc* JPUittof.C&aracterJftica . / v . lUfarmce " ? f e - ;V. :* . ;' - - *'.>; by .*.Afeto CranntU -v .0-'; , . V i Socloty.of aatlca Indotry,..'inc. '' 250 Park w w iV ' " ' Na. York IT, No York , %* U: >. * > ,`,**.iAt** ' ', v/.Vtrv >'. .- .. 0CC042J5314 ., i '!$. . -!V"*, ', vV.->./;tMf" <' J&v , . - ;ip V # .* 1 . r ? co; :.4 un en un - T* '`.*'41. *>V' R Q G -98 WS\ INTRODUCTION TU* ta U itb provide* industry with n m * t m iU U i information u i dot* concernios A i " * o asbestos u a r*isiere*m*Bt in "reinforced plastics". A .R .P . (Aabesto* Reinforced Plastics) provide* industry with material* capable of meeting various properties ox require ment*. Typlcel ARP Properties o r Requirement* Heat Jtealstance Low thermal conductivity Chemical Resistance Cryogenic Resistance High i t U b u i (BJ High mechanical strength Varying electrical characterietlcs High tougbneae V n a d s compound ingredient Gunk molding compound*" 3 Typical ARP Product* Cooking handle utensils Switchboards ` - ... Sleetrle Motor Casing . Lamp Socket*......... Domestick Industrial slectrlcal panel* Commutator Ring* ,,\\V ;; Cable insulator* Auto body fa Railwaybd? parts . Housings for auto heaters It s ir eonditionsrs . Underground-conduits Bower pip** Noise insulator* ' ..Helmets ; ' . Chin gripe _ * ; Incinerator* Blackout or bombproof shelter* MlsaUo nose cons Roeket motor structures and insulation Missile blast tubes Brake Usings friction material for automatic equipment Clutch facings Gaskets Yalres Rooting A dd proof tanka. Gas vast tubes or pipe* Aircraft ducting Chemical f ilte rs . T&ii bulletin doe not discuss fibirglas* o r glass fiber reinforced plaatlc* which represents alarge and cod tinning growing industry. Tbs subject of glass fiber has bean reviewed in ntentrou* BPS bulletin* and litem turo. Also, this review doe* se t Include discuselont on other fiber uecd la "reinforced pl**tio*,,i such as, cotton, nylon, rayon, sisal, quarts, alumioumsUlcate; etc. 0 c C0 4 2 3 5 9 1 5 The principal reaeon* for preparing tibia bulletin w e attributed to the growing demand for A .R .P . end that an education 1* required la better uaderalandtng asbestos as applied to re inforced plastic*. Raw msbeetoa can introduce a multiplicity of problems If Its variables are pot understood. These variables include condition* such aa Chemical analysis, grading,' ' classification, and trading conditions, Various specifications a r t available, but it ha* been determined in certain industries where A ,R .P . la need that new specification* for the uas of ssbtftos in reinforcedpUetlce will gradually evolvo based on new industry rsqulroments.l l . S5Ool,J o, CO "O ( cn cn HISTORY ' Asbestos bat been on* of mankind*e moat ''creative" material*. Engineers and chemists bay* continually used asbestos in the manufacture of many different product!. In the peat . 2,000 y ean atbeato* haa bean uaed for many diverelfled product* end application*. Serious nee of uebeitoa occurred during the turn of the la st century. It1* ueea, ecientlfic and genera! bay* become extensive in many sphere* and new use* are coneiantiy found for It. It'a use ia utually classified'according to the type of product. Oroupinga euch a* building m aterials, plastics, textile*, and heat insulator* ara-eomatimas used! however, product* can overlap in the* main groupa *>a* an example, an aebaatoe paper product can be used for heat insulation and also in building construction. To io n * people the word asbestos only ldeniifiea * fireproof cloth. Asbestos occurs in rock m asses. These fibsvbeartog rooks provide for fibers of various lengths. The shorter fibers are more abundant than the lougsr'onee. They are m ad in the largest single asbestos industry! namely, cement products euch as riding shingles, flat sheets, roofing shingles, end corrugated sheets. The longer fibers*-are prim arily used to manufacture textile product* euch a* yarn, cloth, tap s, felt, end lap. The textile Industry is reported to constitute the second largest u*a for asbestos but generally lose their Identity since they go lets other products. Principal source or method of obtaining asbestos fo r the textile industry Involve* hand picket operation* at the mins. Special fibarising processes at foe textile m ill are of prime importance in manufacture of textile products. Textile asbestos products are used in different field* including textile, packings, gaskets, plastics, brake linings, filters, electrical cable*, and thermal iaaulstorb. General restores The importance and commercial value of aebaatoe ia attributed to We Incombustibility and it'wunique fibrous structure. It is a spinnable o r filling agent, unburoebl' rock, created by nature by euch a process that man haa not been able to reproduce it in this highly scientific world, ft is * m ineral silk, undecayed end unaltered by time or weather. Asbestos h a t the characteristic* of silk o r cotton, hut it will not bum, Asbestos 1 a great enemy of heat, flame, chemicals *sd acid*, ft is resietent to moisture and corrosion. Asbestos fibsr* can be individually fibertsed and handled sim ilar to other fibers euch as animal origin (wool and silk, e tc ,} and those o f vegetable origin (cotton, flax, e tc ,). To the physicist* end being both fibrous end crystalline, makes it a wondrous m aterial, This rock type m ateriel la a natural scientific product which haa become indispensable to mankind eiaco It le need in many different field* of industry. The Greok word asbestos moans indestructible, unquenchable and eternal. It haa been found in almost all parte of the globe, including Canada, Italy, U .S .A ., South and Central America, i 2. 3 3 ti I r % ?0 : CO ro .o ; I un on 4 *:7MMAGEB LESSCUEARTHAN THJSNOTICE[TEDUETOTHB y' . Chino, Japan, Spain, Newfoundland. Australia, Portugal, Hungary, Russia, Control Africa, and Southern Africo Commercial volila la principally concentrated in the arena of Conodo, Russia, Control Africo and South Africa* The CanoriIan asbestos ia generally considered to be superior to other inaofar aa eoaaatial proportiea of InfuslblUty, tenoilo strength, /Inones and .elasticity la concerned. Many theories exlat concerning rite formation of aabaatoi. The theories baaically dilier depending on the source of Information* given though aobeetoe hao bean known for agea, it1 geologies) Malory and formatton are etiU mattera of conjecture. One of the theories invplvo the result of volcanic activity which occurred many hundred! of -thouisnda of year ago, The ignlouo rode had acidic intruaivee that formed granites and feldepar'dlhoa,. The ultra-basic intrusive formed dunlte which eventually formed poridotlto and pyroxena peridot! after coming in contact with olivine and oxide. Through the agei. these n d t i paeeed through various stage of physical and chemical change to form .. miners)* known as serpentina. This change occurred during the time when preeeure was . created bn the rocks causing cracks la the rock. Jn turn, these cracks were filled with :hot ground watera'derived from the infiltration of rain or surface waters. The continual ; .infiltration of (his water under heat and pressure acted as a solvent The watov'became contamihated tyifo different minerals. Crystals' developed and were deposited In the cracks t of the rock,' . Most recks era made of crystals. Crystals hold ona of the most secrat of all nature1s mystaris a, These crystals form basic pattens* The minerals which make up the crystals era important and produce the specific different type asbestos fibers, ;d ! G -i f so ,4 o CO ro A .o ; The rode formation In Canada la a variety of the olivine which is composed of iron, magnesia, and silicate, Water containing carbon dioxide and aglt in solution penetrated the rocks. This gradual flow o f highly contarnlasted minsral water Changed the original rock from iron ' .............. V containing mineral to magnasis - allies - water* According to the geologist, this reaction n ' took plica thouaanda of feet below present elevation. -Since it is believed that asbestos developed deep within the earth where could be subjected to pressure and heat, it is believed that la the case of the North-American Continent, the glacier* or massive ice'formation eventually removed the earth and exposed asbestos on the surface of the earth. During the formation of asbestos with thf continual praasurs reportedly moving the rock formation and causing rocks to crack, foe crystals or ilbsra developed various patterns in the cracks. The reeultant veins of eebeeto* rock were predominately broken eo-fost more offoe short asbestos fiber ore available. Ore Deposit OCC01Z3S917 Asbsitos is made available to industry either directly from the mines or through distributors. At least 90% of the aibestoa ie obtained directly from the mines. Meat of foe asbestos ( ..... 3. iu n en CD r j companies which mine asbestos, us the asbestos to produce products *rh secondary in te rest in supplying raw asbestos to other eoxapaniea. There a re Iso manufacturing companies U d 1 speciallae in the manufacture and production of asbeatea products without directly owning . mines. The United States la the'W orld't largest producer o f aabeetoe products. Tbs main source of asbestos for the United State* is Canada. The Canadian minea a r t favorably located for supplying the United Statea consumers. Canada provides approximately 90% of the asbestos used. Domestic asbestos contributes approximately flv# percent. i The enormous te rrito ry of USSR contains asbestoa deposits to such an extent that they should v ba considered one of the principle producers of asbestos in die world. These deposits a re generally considered second of importance to the Canadian. P rio r to World War I> Russia occupied aacond place among ths world' asbestos producers. Its largest asbestos mine* are situated iu the U ral Mountains. Deposits also 1 s t in Siberia. Gredins j With the gradual p rogress in developing highly engineered products with asbestos, the } asbestos industry hue required tba minea to ant up special methods of classifying asbestos { - t In aecordshce with length of fiber. E xact measuring of actual Staple length of nnbeatoa fiber is one of the m ore difficult tasks by the m enufacturer. Asbestos differs from cotton, rayon, and other fibers which are possible to comb. By combing the fibers, the actual length can ba m easured. Staple length i of chryeotile asbestoa fibers of any one Of the various types varies from 3/0 " to l n and ] down to microscopic m easurem ents. Oxading of asbestos is generally on the b asis of length rath er than quality. Qualities which ana a lio important to fho fibers in addition to length a re flexibility and fineness. The m ere flexible and fine fibara a re used fo r spinning and weaving textile products. The' shorter milled fibers era used in various products such aa asbestos cement, tile, and brake linings, j In 1931, a committee w as organised by th e M inister of Minea of the Province of Quebec. The j comznitteo on "Uniform Classification and Grading of Asbestos Minas Products" had the project of rev llln g th s chrysoUla asbestos grades. / The Canadian Asbestos Producer I have se t up what is referred to as "Quebec Standard Asbestoa Testing Machine" for classifying m illed asbestos. This method is bated on the' m echanical sieving o<fibers, T hais has been a general trend to adopt ths Canadian Standards Classification! however, many of the old m ines ln Canada still retain their own methods which a re specifically tailored to their custom ers. The classification divides chryeotile into two m ain Claeses a t crude send m illed asbestos, ! The Crude Asbestos consists of the head selected cxoee-veinlng m ateriel essentially in it's native o r unfibezleed form . The Milled Asbestos consists of ell grades produced by mechanical treatm ent of asbestos ore. These two main divisions are subdivided into different groups ranging from group No. } to No, 9. ^ un on UD Q SC O U ifcS X S CitaiDcatlon o chrysotUe iibutM according to Grovpa ara u follow# iilsg Grada Asbestos *Y Group No. 1 Crudo No. J Constato btiicaQf o crudo JI d 3/4 iacfa stsplo and longos ,Group No, 2 Crudo No. 2 Consisto bssically oi fcrudo 3/8 indi tapio p to 3/4 lnch Crudes, Run-of-MIne Consist baaictly o dnoortod' crudos "Vyftc ... S Crudes. Sundry Conilata o crudos othsr than pscliod abovo 'tir$ ..-ATi MUled Aabaatot Standard Designation o radaa.1: 'Guareatod Mtnlnaa ghlpotno Tost ;h;v] *,. C. >;V Group1fte'3;(gpiin}lng Piteeo) irs iv ' ^ 3K' V?fT:, ' su. . ;fWj ' . . -3Ty- - - V ; I0.-9 -3.3 7.- -.7 : : . 4 .-7 ' . 2 -8 1 -9 ",0 -8 -1.3 0.3 -1.5 . -0.5 -4 -J 4 -2 -4 2 -6 -2 GroupNo. 4 (Shingle Fibreal .!rj (N4W8r *i pj ] . V' 4*.v. -- - ; GroupNo, S.fPapdr librea) -V. 53t ` V o, -7 -6 3 .o '- - s : -8 -3 ' .-4 . -8 . -3 \;<0. * -4 -3 -8 -9 -4 . 4 -to -.0 a : - 10. -4 o . - 1.5 -5. >5 0 -0.5 - 10.5 -5 0 -0 -12 4 0 -0 -11 -5 0 -0 -10 -6 Si Group No. 6(Waste) 6D Croup No 7 (Shorts or Refits) 7G *j-'j 7P OCCO1 2 3 5 9 1 9 0 - 0 - 7 - ;-9 0 - JO - 5 - 11 o - ..o - 4 - 12 'V J, r' ' vi u n -- .i C D lONOS^ * * .* < Group No. 7 (Shorn or Rcubo) continued.... 7H '7K' * 7M 7R n w 0*0 0- 0 0- 0 0- 0 0- 0 0- 0 - 3 - 13 2 - 14 1 - 15 0 - 16 0 16 0 - 16 Group No. 7 (Float*)* 7RF . 7TF a6 teat ' no teat*' Group No. 8 (Sand and Gravel) S Under 50 pounds per cubic foot loose m easure *? . ~ Under 75 pounds per cubic foot loose measure Group No. ' 9 9* Over 75 pounds per cubic foot loose m easure r' ' ' h 7V,' * *. V ~ . . i *'* * **.' . - 1>E* J The"suffix "F*! delineates.1.1Floats" In the case o ths 7R and 7T grades. OCCQ1235920 to tho Croup No. 1 and No. 2 the length of tho Cxnde i i b e i t n can he measured hy m tn n of combing to tho cnee of the milled aebeetoe, the Quebec Standard Teating M 'chine le need. It conelate of three atacked acreene and a pan reeling on a table. T h is. -rren e are driven bp an eccentric gear eo that an elUpltlcal motion la produced on the > m e. Each acrean maaaurea 24 1/2 Inch x 14-3/4 inch with the boxer each 3-1/2 Inch In depth. The top hex which la identified as Box 1 conaiats o f a w ire screen with 1/2 inch openings, Box 2 has a 4-meh w ire, Box 5 bar a ID-meah w ire and Box 4 ta a d are d rocepticel which collects all m atter filtered through the other three boxes. The motion of the boxer and the time that fibres era subjected to motion are fixed. The test'proceduro Is to introduce 16 ounces of aebeetoe on tits top tray. After two minuter of motion the fibre in each tray ia weighed. The root fibre retained on the firs t acrean end the less fibre falling into the pan producer a higher grade product. As an example, Group No )X pacifies 4-7-4-1. This means that in a sample of 16 ounces, Box No. 1 retained 4 ounces. Box 2 retained 7 ounces. Box 3 retained 4 ounces and one ounce fell In tin bottom pan. The Quebec Albeatee Mining Association has aat up standard teating proceduies which j include tbs use of a standard approved machine. They specify tits method of taking samples | for tilting. T h u tasting Croup No. 3 fibres, `a composite sample shall be made up from ! each and every lo t of 1Q0 bag* included In the number to be tested. Each composite sample j hall be made up by taking a handful (about 4 ounces) from every fifth bag of the one hundred bags, to the case of Group No, ' 4, 3, o r 7 fibres, a composite sample shall be made up from each end every lot of two hundred begs included to the number to be tested. Each composite sample so nude up shall first be allowed to approximate average work-room temperature and humidity, and then shall ba thoroughly mixed on a smooth topped table while paning It through the hands with a gentle rubbing action in order to break up and saparatl all d o ts and lumps. It is than divided into halvas, quarters, e tc ., as necessary, and a represented one pound lot shell be weighed accurately and placed in the testing machine. Tho greatest iner sale in use of flbteo baa bean in to* shorter lengths that comprise approximately 50 per cant of Canadian asbestos production. Tho claesifloation of ahorti and floats follows til's sam e principal* a t the shaker teefi however, other factors such as bulk, grit percentage, viscosity, a te ., have a bearing on nomenclature used. The Group No. 7 shorts o r refuse consists of m aterial tasting 0-0-5-11 and below. The .term refuse is a hallway freight classification designation and does not m*an that shorts and floats i r e "bypTQdtrcie'oi asbestos milling.--A* tho name im plies, fie ( are fibres so fine and light that they are collected by air floatation. They arm predpltated into float chambers by gravity settling or collected by filtering media. Shorts sad floats have shown a remarkable increase fat use for several reasons: quality Improvements which have developed new uses and improved finished products thus causing tb s shorter to supplement sous' of the longer fibre applications and the expanding m arkets .fo r relatively new o r growing industries such as vinyl tile, plastics, asphalts, and 7. 0CC0-1Z35321 0; co; .foo ;; iLTi rU 1 i aabesto- cement. Other methods of classifying fibre* have different Identification* depending on the type j asbestos, length of fibre, fiberiiatlon, end other ehereeterlstie*. In some esses, the j mine* edd additional letter* or number* to the Quebec Standard Testing Machine . . . nomenclature. As an example, the Aabeeto* Corporation, Ltd, includes e number system-' to designate degree of crudeness or openness. Manufacturers of asbeatea product* obtain fibre* from snore than on* eource h a rd e r to eliminate potential problem* inkerentfwben only one eource la available. Since aabeeto* fibres from different mines sometimes behave different in proceaaea, the manufacturer^ - have to keep close controls on manufacturing p ro c e s s for tha various type fibres. This la a skill obtained through continuous uee of the different fibre*. ; The class sad grade of asbestos need in the manufacture of different products varyi however, the general tread can be identified, long fibre* air* used for yarn, cord, braid, and textiles! for packing and gasket*! Ipr felted long fibre paper o r felts, and for filtration; and i asbestos-cement goods where'maximum strength la.reqnirad. The medium length fibres i Including Croups No, 3, -4 and 5 / a ra used as reinforcing filler in asbestos- cement products! J asbestos paper and millboard! a* tha banding agent in magnesia insulating compounds) \ ) filtration pad! and sheets and molded brake blocks' and' linings. The short fibres and floats * Sirs used ee fillers in paints,, asphalt, puttys, .plaster, stucco, plastic molding*, and othare. The Group No,! s 8 and 9 generally contain largsgportlana of minute reek and sand which ere not detrimental to the finished p ro d u cts,. In Northern British Columbia, the Caseiar asbestos grades are identified as follows: Crude |1 - Basically of crude 3/4" staple and longtr AAA - Extra long textile fibre c AA - Long textile fibre A Textile fibre AC- Long shingle fibre -AX- Medium long shingle fibre . AS- Shingle, fibre AX- Short shingle fibre *. ,-c ' >' . LTV Asbestos producing'countries other then Canada do not use the Quebec Testing Method, Their designations do not tally with the Quebec Classification,. If m aterial from another country -were tested on tha Quebec machine, there would only be a comparison of rotative value hut . never an exact comparison according to grades, -Classification of asbestos fibre available' from different part* of the world are reviewed. [ i UJ 8. i 0CC0423S922 L-d* Classification pt Africa Ghryaotile CltGl C6G2 C&C3 ChG4 CbGS Long, crudy textile fibre Textile fibre Long shingle fibre Shingle fibre Short shingle fibre or paper stock F rom mine* in the Shabani d ie triet of Southern Rhodesia ) VRA/-Z YRA/-3 YRA/-4 Textile fibre Long ehingle fibre Shingle fibre ) F ro m the Mash&ba ) dietriet of Southern ) Rhodesia HVL/2 ' Textile fibre HYL/3 Long abingle fibre HYL/4 Shingle fibre . ' HVL/5 Short shingle o r p ap er lock ) From the Havelock ) Mine in Switzerland -, ` ."'i'MsauU - Grade 4 ) .Shingle fibre* ;r'-XisauU - Grade 5 ) V * ' . A * *........ . F rom the Msauli Min* n e a r Swaziland b o rd er in the Transvaal !V :^ :-v v ;* - VC-. Classification oi Russian Ghrysotlltt Grade T ffii. . Texture Mark According to U .S.S.R . Standard January 1, 1952 r - Textile Herd (crudy)' J-l 2 Long (Magie Hard J-2 C S em i-hard P-2 Shingle Hard J-3 S em i-hard PJ-3 F -1 Soft M-3 Short ehingle. Hard J-4 It paper stock S em i-hard P-4 Soft . M-4 Paper Stock Hard J-5 S em i-hard P-5 Soft M-5 Hard J-6 S em i-hard P -6 Soft. M-6 Unguaranteed K- 6 Unguaranteed K-7 0CCQ1235923 7-370 7-450 7-520 & i p ' A S*' $ g W -' .At w'S p t Hi V*?- fr;:/ jig#! r . 'U * .J m -n M w s Grade CU nlcation ol Russian Chryaplll True Texture Mash. According to U.5.S.R. Standard January 1 1982 Unguaranteed 8- 750 i Classification ol Auatrallan G hrvotilc x. .. -Grada 4 - .Inch fibre and longer Orada 3 * 1 inch to 2 inch librae Grade 2 - l/2 inch to 1 inch fibre Grade 1 - 1/4 inch to 1/2 inch fibres C larification of African Amosite Group 1 Produced from hand-selected long fibre at Penge Mine only. SS Long over 2" in length s. Group 2 Produced a t Penga fro m run-of-mlne fibre efter longeet -f '. has been haad-aelecred. t O il Mlnue 5" pin 3 /4 ". OX Aa above but graded by color. Group 3 Generally minus 2> 1/2" plus 5/8" MO From Penga mine M From Penga mine - somewhat shorter W$ From Walterreden Min* K3 From Kremollenboog Mine Group 4 Generally mlnue 1/2". 82 From Penge Mine BK From Kremellenboog M ine X SW Group S GW . From Weltevreden Mine Generally minus 1/2" Front Weltevraden {fine OK . From Xromellenboog Mine b addition to the above grades th e n are several from the Plateraburg Field, of which WXG from the Mallpedslft a re a la probably the moat uniform ly prepared. The latter ia lim ila r in length to Group 3. The other grades listed in the foregoing grouping are produced in the Penge area, of which the A m ors Mine la the la rg e st producer. The screen lie shown ere not n ecessarily exact, hot have been included in order to give ism s indication of the relative lengths of fib res of the different grade*i- 10< 0CCO Z3r.9"4 . H O fte Cara BIoo (Crocido]Ita) plus 2-1/4 lachea - plus 1-3/4 - 2-1/4" C - piu* 1-1/4 * 1-3/4" No. 1 o r B - plus 3/4" - 1-1/4" No. 2 or A and R2 plua 1/2" * 3/4" No. 3 o r 8 MS sud R j -p lu s 1/4" - 1/2 ' X. 9B0| H and SS - Varloua charter grada* {he loager grades down to Ne 2 o r A .are m eati/ hsad-cohbed. Tranaeael Blue /Croeldolltal ` 136*- Piu* 1-1/2"' . Tj 7/8"-1-1/2" Tj - " 1/2" - 7/8" T - 1/ 4 - 1/ 2 "Long" - M U and NC300 shout 1/4 to 3/8" T+ - sud "shorts" moatly tona 1/4" Most of th aber* nusnber* hay* iallan lato dlsuse The preaent practica i* to rea* la rg a i/ te "long" and "ehorP1ior th bulk o t Rie Traneveal production. .There te no ; reeognltlon eznong th major producer* that greetar etonderdlsettoa le deiireble.' AutraUan Bine Onde NO. 1 Long fibre - 1 in. end over No. 2 Piu 3/8 to 1 to. * No. 3 ` Miami 8/8 to. 0CCOJZ3E3Z5 i v ' > J Cn I * i Minina. Milling and Processing - The method of mining, milling and processing et **b*to depend* on the type of asbestos being handled aa well ae It1* specific physical characteristics such a t a soft versus h a rsh fiber. Since Chryaotile fiber i c c m t f to t approximately 9S% of all the asbestos weed, title dlseustlon will pertain to Canadian chrysoUJe. Originally, when the mines were opened, the mining operation Involved predominately manual labor in open pit operatlona. In the past thirty yeare the. mining operations have become highly mechanlaed with the nse of era se *, cable hoists, etc, I Hand cobbing la the oldest method need In mining asbestos. This particular method 1 still used- to obtain the long aabeetoa fibers. Hie operation Involves releasing fiber from the rook by means of hammering away (he rock from the ends of fibers. F ib ers Identified as crudes #1 and #2 a ra hand cobbed. These type fibers a re not processed through the standard crushing units during the milling operation of the shorter fibers. > The content of fiber In the reck mine ranges between 3% to 10%. Workable mines- are considered profitable when the recovery la only 3% of raw aabeetoa. Variables such a s availability of labor, transportation facilities and size of deposit determine whether e low asbestos content mine w ill be profitable, fit Canada rich areas are considered to recover V, approximately 9% to 12%. The asbestoa. ae obtained from the mines by blasting and quarrying, la sold either a t "Crude11or "M tiled". Crude asbestos consists of hand-picked asbestos in it'a natural nnfiberlasd condition. The Crude generally contain* 9 to 15% rock, dust o r short fiber `i o . CO to Which has to be removed by the m anufectarar in their own plant. 1 :9 ': Tim Milled asbestos is made up of the sh o rter fibers. Different processes or system s are used by the mines to process the m illed fibers in order to release rock and fiberfxe bundles of S hare. Asbestos fiber Is found in rock deposit* classified us cro ss-fib er, slip-fiber and m a as- fiber. Asbestoa usually,occurs aa cross-fiber In which the fiber runs a t relatively rig h t angles .to.the .walls of the rock. The fiber length rarely exceeds 2 t 1 inches. V The arerag e long fiber asbestoa loir ebrysotile Is 3/4". la some cases a bead occurs in the fiber which results In a weak fiber at Ike point of bending. In slip-fiber* * the fibers lie In the direction parallel to the seam or crack In the rock. Generally, this type fiber la weaker than the cross-fiber'. It is considered unsuitable for spinning. j j In the m ass-fib er classification, there la e complete absence of any orientation of fiber. The asbestos is distributed at random. This type of formation generally occurs with * fits emphibole varieties of asbestos. The fibers tend to be soft. j lt 12. 0X 01331^6 --I --i * When la rg e cross-fiber vein occur it 1 relatively simple for a miner to hand cobb in o rder to obtain erode fiber*. The long fiber adhering to ro ck i aemetimee dried over team coila in order to simplify extraction of the fiber from the rock. M oil o f the fiber vein* are toe narrow to be separated profitably by hand. The rock con taining aabeetoe la sent to a m ill located near the mine whereby mechanical means separation is accomplibed. The proportion of long fiber o r crude aabeetoe extracted from the rock ie approximately 8 to lp% of the aeheatoa which is removed. The remaining aabeetoe consist! of medium end sh o rt fib ers. Markets in industry ex ist for all lengths of fiber. It is difficult to ascertain the true value of a mine by only spot checking. The width of an asbestos vein s t say one point dess not provide n tru e picture of the length of fiber which I t contains. To obtain reliabla values i t is necessary to remove or blast the rock from many different locations. The mining experts Judge die various types and grades of asbestos according to length and s o ftn e s s c f fiber. Other properties a re also taken into consideration since various typo asbestos conditions a re desired for the specific and products involving fab rics, brake linings, packings, asbestos-cement, and others. Since m ost ol the suibestos mines a re located in mountatoeeua or rough terrain , an important consideration in developing a mine is to determ ine the availability and transportation oosts of the asbestos to the customer. Another m ajor consideration is to set up proper operations involving'the hauling of large quantities of rock. Many asbestos m ines handle tons per hour of m aterial or o re. This high tonnage ra te la neeessacy since the yield'of the average ,,asbestos mine can be less than 51k.' (fining requirem ents a re such that the short asbestos fibers tend to become the m ost profitable products. Two methods of mining exist. The open p it mines is the m ore desirable method. To open a quarry or open-pit mine, It la firs t necessary to remove surface m atter. After removal a t surface m atter standard blasting techniquea are used to loosen the asbest:>* containing rocks, ......................... Underground mines ere used. Various methods of tunneling are need. Open-pit operations are performed by methods such as side bill cut, overhead cableways, sp ira l benching, multiple handling, and others which a re generally identified, by the physical m ethod of mining. With a hillside exposure, mining the ore la a aimple and cheap opera tion. It Ie m ined in te rra c e s cut out from the rock end in caves. This type of operation is found principally in the rich asbestos deposits. The overhead cable operation ie used In wide end deep p it mines. C arriages which remove the o re are connected to hoists, hi turn, they ere connected to track cables which are installed over the open-pits. It ie reported tin t the largest commercial cable way system ever Installed was a t the King Mine of the Asbestos Corporation, l t d . , at Thetford Mines, Quebec. ' Q C C O W l^ 4" 13. Spiral and multiple benching la related to the more conventional open pit method identified u inclined cable or truek haulage technique. In the Inclined cable operation, the floor of the mine {a Inclined to the aurface. 'Whan caUea are need, the inclined angle is approxi mately 20 degreea. For truek operation*, the angle i i approximately 15 degree* or leea. In the spiral benching operation, the pit develop* Into the form of a large bowl. The multiple benching technique la uaed where apiral benching la not feasible. Generally, barren rock formation! are located in the large asbeetoa deposit or area. The barren rock formation doea not permit continual apiral operation* ao that different spiral benching operatione occur in the one area. Thl* type of operation la referred to ae multiple benching. Underground mining operations occur end generally tie in with open pit operation*. Different techniques are need. In moat case*, mines era developed where asbestos occurs on the surface of the ground. New methods of finding asbestos deposits are being developed in order'to find asbestos ore not exposad to the surface. In mining operations wood ia not used because caatamination would bo detrimental to the manufacturing plants. Milling Asbestos - After the asbeetoa ore ia mined, the material goes through repetitive crushing operation* to separate the asbeetoa and rook. Crushing and screening operations occur. These operations are referred to as "milling". Special mill equipment-is required for these Operations, The methods used In the various mines are basically the same but generally differ* in regard to siae which depends on mine capacity and type of fiber. j `tO ; CO , 4 OK -: In milling the two major objectives are to separate asbestos from the rock and.prevent reduction in the length of the asbestos fiber. - The veins of asbestos fiber depends mainly gn fiber length. Tha objective of preventing reduction in length ia vital. Extraction of the fiber from the rock requires repetitive crushing of fh* ore. After each Brushing operation, free fiber is removed by air-suction. Xuorder to successfully remove asbestos, the m aterial must be dry. Tha mined asbestos contains moisture which varies depending on weather conditions and eeaaen of the year. The moisture is removed by mesas of mechanical driers. The dry fiber cea then easily be removed by air-suction. !l h I ___ f The primary crusher, usually of the jaw type, has the capacity to handle roeks up to 48" in siae, weighing up to a ton or more, and crushing them to agproxtmttalyS* to d" in UQ width. Crushed rock le carried to trommel screens. These acrqens are large revolving cylinders with various alas openings. Tha trommel screens only permit the relatively small rocks j of approximately B" to 6" width to continue through to the secondary stage of crushing. This type crusher ie generally a gyratory or cone type crusher. 14. OCCO1 2 3 5 3 2 8 < * (' Crushed rock U dried In tower or rotary drier* which very in temperature from ZOOF. to 1,000F. After the drying operation the rocke which range I eie* from I to 3" ere fed into a third crushing unit which ia either of the gyratory type o r cone type The crushed ore end ber a re fad to heavy shaker or bumper ecrease which are operated by mean of eccentric drives. Powerful a ir suction hoods remove fiber. The rock peaces over the end of the screens i The undereies m aterials pass through the screen and is fed to a ftbarieer for further treatment. i V, Additional shaking acraana are need to eaparate Obere Into long, medium end short categories.' Duplex shaking screens are used. The long fibers remain on the top of the screen. The medium fiber* in the lower screen and the sho rt fiber passes through both screens. i The rock which was passed over the end of the heavy shaking screens continues to other j crushers. The cyelo ia repeated whereby the crushed rock passes over shaking screens and in ta rn fiber is ramoved by air-suction. j After the fourth crushing cycle, the remaining roek ia further separated by means of i fibsrise r . The fiberUers break the rooks by means of impact or direct blow of high speed ) ham mers. The cruebed atone is again fad through the shaking screen in order to remove additional fiber. J The milling operations are continuous. A fter the crushing and suction operations, the ! asbestos is cleaned, graded and put in hage for shipment, During the operation fiber collectors which are conical cylinder perform the firs t stop in the cleaning operation. Current* of a ir c a rry the fibers into designated areas where additional cleaning n occur over serosas. Jt- The process of separating asbastos from rock during the milling operation takes into account tits specific gravity dilforenco of the two m aterials. After the fluffing or Bheriaing operations, the dry asbestos can be taken away from the rock by means of a ir currents. A method which 1 not generally used involves the wot-mOling operation. In the wetmfiling operation thefiborieed asbestos will float on water. Grading of aabeatoa fiber la conducted In spatial designed graders. Long rotary wire screens of various sis* m esh are used. The else mesh determines the langte of fiber. l Ia general, the graded fiber la stored In burlap or jute bags of 100 lb. The fibers are compressed in order to reduce bulk. OCCO 35929 CD I 15, I inq.T<*`"<fy" 1 .( r Hoalth ad Safety factor - With th development of the ubeitoa Industry, contamination of the air with small asbestos fiber p u tte lu produced hygienic problems. Hygienic measures were not well advanced when the first mining operations were developed. Since the dry processing method is . ussd in mining and milling asbestos^ small fiber particles ars picked up by air currents and din tributed throughout tho manufacturing plants lad in the neighborhoods. The asbestos partlclss or dust which developed could become harmfiU to the people who were constantly exposed to it. Aebastosis is a special type of sDicosls but doe* not occur nearly as often. Approximately 10 years la required for a person to develop aebeetosis if ho is constantly ex posed to fits dust. However, since protective measures are provided by the different manufacturing plants, it is extremely ra te that a person develops asbestos!#. ( Chemical analysis can bo made of dust in order to determine concentration of asbestos dost particles. Information is available as to what the maximum concentration of dnat should bo to eliminate any problems. Various safety measures are available such as well ventilated araaa. special mskat sad water eprldder systems. Proper filterafion techniques are available which will collect dust partides. With proper precautions! there is no problem. Periodic medical examinations of workmen are preformed In order to keep constant check an thsir health. Apparatus used in con nection with the asbestos industry should ho ssalad off against outside air as much as possible and should work with a draft under negative pressure. The passage of the duet into lungs through the respiratory system is dangerous. It is important that proper pre cautions be taken by all companies which handle asbestos. 7*0: 0 ); J\> iO : t f ' 'I 0CC04235930 u -i CD 16, *c. i i 4