Document Yr08pok4N0O4YZoD70YQDEMoN

'> l:x ] !i l ft a Tlie D e t e c t i o n and D e t e r m i n a t i o n Oi C h r y s o t i l c i n USP T a l c Harry A . Rose N \ Abstract ___] A procedure for the determination of chrysotile Jn talc lias been developed. It depends on the adsorption of a su Ifonphthalem dye by chrysotile but not by talc, fhe final measurement is a spectrophotometric determination of the dye left in solution after the adsorption step. \ Tlu 'de use of talc as a dusting powder and as a diluent in tapi/uh: contents has caused concern about 'i, possible impurities m the talc and especially the possible presence of asbestos. Cralley et a_l. (l) found asbestos in a number of cosmetic talcs. Merliss (2) implicated asbestos m talc as a cause of stomach cancer in Japan. Talc is a hydrated magnesium silicate which may ideally be represented as Mg 3 (OH)2S i 40 i 0 . It may be contaminated with other minerals such as quartz, dolomite, chlorite, and the various forms of asbestos. Of the asbestos minerals,, chrysotile is currently of most p h y s l o 1o;,ical concern. Chrysotile is also a hydrated magnesium silicate which may ideally be represented as M g c (oil) 8C i 4()10. The structure of both minerals is apparently made up of sheets of silicon and oxygen atoms interspersed with sheets of magnesium and oxygen atoms, the difference being in the added magnesium and oxygen in the crysotile structure. USP XVIII (3) is rather vague about the chemistry of talc and apparently would admit a talc containing some chlorite. The concern is for rather gross impurities such as excesses of pH or water-soluble iron. Thus, a rather substantial contamination of the talc with chrysotile could occur, and unless the product became gritty, no cause for rejection would appear. \ -4- iiic vcu'uiii;; soJul.iun was made by taking 20 ml. of the :to>i. solution plus 40 ml. of 95^ ethanol and diluting to 100 mi. with pit 4.2 acetate buffer. This working solution when diluted 10 ml. to 25 ml. with pH 4.2 acetate buffer should have an absorbance of .325 at 422 mp. 1 he chrysolite was obtained from the Johns Manville Hoscarrh Center and was used as received except for irlucli"n in particle size to that of the talc being i<at cl . 1 rowed.re - Weigh three 0.2000 0.0010 gram samples .C tiie i.n . To sample number two, add about 3 mg. of chrysolite and to sample number three about 6 mg. of ehryso i ile, both accurately weighed. To each sample add 10 si. of 50/,' ethanol-water. Also, provide a 10-ml. .sample of the 50,/ ethanol-water to serve as a blank. All sample.'., .mid the blank are given an ultrasonic treatment lor two minutes at 70 watts of power. After the samples have cowled to room temperature, add 10 ml. of working dye solution to each sample and the blank. Mix and allow to stand n .r 30 minutes writh occasional shaking. The samples and bianii are then centrifuged followed by filtration through u 45 p. millipore filter. A 10-ml. aliquot of \ each filtrate is diluted to 25 ml. with pH 4.2 acetate buffer. Honifier Cell 0 i.sruuter, Model W185D, from Heat Systems UUnt-.uiiirs, Inc. of Plainville, N.Y. The micro tip adapter was used. \ A The o.M ical absorbance is then determined at 422 mg. in a su i!a b ]e spectrophotometer. The absorbance is then plotted against mg. of chrysotile added. (See Figure 1) by extrapolation to a baseline, the level of which is '' ' ' k T o ,k . the t!.rvi,.T ; le y>-) ea;. ie by j_ l.; i' ` '.'S'*, . !'<u. u i # -G- j :i1 ilio a;n,ay in Figure 1 would indicate 1.1 m^. chrysotile in- a l'iHj-i.ij'. sample, or 0.55)'. Kli Lilly and Company has been fortunate in beinfj able . ` j >. c L j'iit'.n: ii' \na. Les m r . . n.i >.*>.. n-e. nn m ... ' . ' .ic hi \- a .1)>:>, . ,a ' n -> .J - 11 .a -; > ii< t! . ` -, ' . . "i-/; - . .>t . 1 ,, *1 t` , , ' ( ` 1> 1 ;u n 1 '- '!' i - i. .11 ` t, ' - 'ih . _ `;n . V- . , ( i a A l i . i l i Ai- I ; ; ,* 'v ' i V .. 1 ... ir. ? '' * ! -7REFERENCES (i) E. J. C r a 1ley, M. M. Key, D. II. Groth, W. S. Lainhart and It. M. Ligo, Amor . Ind. Uyg. Ass. J. , 29, 350-354 U DCS) . (2) K. It. Merliss, Science, 173, 1141-1142 (1971). (2) in.' United States Pharmacopeia, 18th Revision, Mack Publishing Co., Easton, Pa., p. 708. (4) A. L. Rickards, Anal. Chem., 44, 1872-1873 (1972). \ \ -8ACKNOWLEDGMENTS AND ADDRESS <2 The author wishes to thank the Johns Manville Research Center and Dr. John M. Hayes of Indiana University for providing the samples of chrysotile. Analytical Development Department, Eli Lilly and Company, Indianapolis, Indiana 46206. \ \ -9- lifiine Exti'apola ted graph of additions of chrysotile plotted against absorbance. \ \ 9 2IO! IN SAMPLE ADDED MG . C H RYS 0' 23 TO S A M P L E TILE ., EXHI--TT F C o m m e n t s R e g a r d i n g A n a ^ ^ i c a l P r o c e d u r e s for A s b e ^ ^ s Determinatd on ' v7e b e l i e v e t hat the d e g r e e of p o l a r i z a t i o n in the microscope should be defined. In our studies we employed a Leitz Ortho-Lux microscope w h i c h p e r m i t s a c o n t i n u o u s r a n g e of p o l a r i z a t i o n s to be used in c o n j u n c t i o n w i t h the two r e f r a c t i v e i n d e x fluids specified in the regulation. We found that the count of asbestos particles changed w h e n the degree of p o l a r i z a t i o n was changed in the microscope. W h e n the m i c r o s c o p e is set at 4 00X w i t h e i t h e r refractive fluid, one experiences serious depth of field problems which make it difficult to d e t e r m i n e axial r a t i o s for a n u m b e r of sizes of particles. It is par t i c u l a r l y diffi c u l t to focus on large particles as when one por tio n of the p a r t i c l e is in focus the o t h e r p a r t is out of focus and d i s a p p e a r s . This in tur n m a k e s it d i f f i c u l t to determine the exact size of the p a r t i c l e s ince the w h o l e p a r t i c l e is not in focus at any one time. A m a g n i f i c a t i o n of 100 X w o u l d give a b e t t e r depth of field y e t this c h o i c e of m a g n i f i c a t i o n w o u l d a l s o m a k e the particle size selection process somewhat more difficult. One of the s i g n i f i c a n t p r o b l e m s that we e n c o u n t e r e d was the large number of counts obtained and the time employed making these counts u s i n g e i t h e r r e f r a c t i v e i n d e x fluid. P o s s i b l y a w a y to more easily perform counts and be able to determine sizes more accurately would be to use a d e v i c e suc h as a h e m a c y t o m e t e r , a microscope slide with a grid w h i c h is p r e s e n t l y used to p e r m i t c o u n t i n g of blood cells in a specified volume and area. In some of the talc we have been examining, we have found quite high levels of the c h r y s o t i l e a s b e s t o s fibers and question the limit of no t more than 100 fibers pe r m i l l i g r a m slide. Perhaps the data on w h i c h these limits hav e b e e n set c o u l d be p u b l i s h e d in the Federal Register. In s u m m a r y , we f ound the a n a l y t i c a l m e t h o d as written to be ambigu ous, time c o n s u m i n g and the a p p a r e n t l y a r b i t r a r i l y set limits to be s o m e w h a t _t i g h t . We feel the p r o c e d u r e c o u l d be run more easily at. 100X m a g n i f i c a t i o n on a set a m o u n t of a d i s p e r s i o n at a set concen t r a t i o n d e l i v e r e d fro m a m i c r o p i p e t t e w i t h the count being made in a given area, for example, on a hemacytometer. EXHIBIT C # D escription of Modified Method to R evise Proposed Section 1 2 1 .2006(c)(2) Determine the Nz of the ta lc . Place 1 milligram of talc on a slid e . Mix talc with refractive index liquid which has an Nd value most nearly equal to Nz of talc (liquid should b e equal to or slig h tly le s s than Nz in ta lc ) . Spread p a rticles ev en ly and p lace a co v er g la ss (c a . 18 mm square) on the sam ple. Fibers counted by this method should meet the following criteria. (1) Length to width ratio of 3 or greater; (2) len gth of 5 ;um or greater; (3) w idth of 5 )um or l e s s . Count and record the number of asbestos fibers found in the 1 milligram sample as determined from a scan with a polarizing m icroscope at a magnifica tion of approxim ately 4G0x. Chrysotile fibers w ill have indices le ss than the liquid in both extinction p osition s. Amphiboles w ill have indices greater than the liquid in both extinction position s. Check the extinction and sign of elongation for tentative identification. For specific identification of asbestos fib ers, make additional mounts in appropriate refractive index liq u id s , and refer to the optical cry sta ll ographic data in the ta b le . A count of not more than 1000 amphibole ty p es of asb esto s fib ers and not more than 100 ch ry so tile asb esto s fib ers per m illigram -slide constitutes the maximum limit for the presen ce of these asbestos fibers in ta lc . These lim its assu re a purity of talc at least 99.9 percent free of amphibole types of asbestos fibers and at least 99.99 percent free of chrysotile asbestos fib ers. If 100 or more c h r y so tile fib e r s are cou n ted , the 2V of talc should be determined from the interference fig u re. If th is value exceed s 10 there is a p o ssib ility that talc is b ein g counted as c h r y so tile . In th is c a s e , . the sample should be rem easured according to the above procedure in 1.574 refractive index liq uid. Chrysotile fibers w ill have indices le ss than the liquid in both extinction p osition s. \ Optical Data for rites Chlorites are 14A layer-silicates with a wide range of chemical compositions and an equally wide range of optical propterties. The hypothetical formula would be Mg^Cpd)gSi^Q^g. Aluminium replaces silicon and magnesium. 'Ferric and ferrous iron replace magnesium. Nx SL Nz 1.606 1.641 1.570 1.580 1.618 1.622 1.637 1.658 1.581 1.615 1.643 1.662 1.662 1.658 1.658 -- 1.661 - 1.581 1.589 1.618 1.621 1.622 1.626 - 1.642 m ' 1.667 1.581 1.586 1.607 ' - . ' Kx . 1.670 -' <1.63 1.600 1.578 1.660 . 1.619 1.646 1.572 1.620 njl Nz 1.685 - . 1.664 - 1.620 >1.650 1.603 1.610 1.580 1.586 1.660 1.606 1.623 - 1.625 1.646 1.655 1.572 1.595 1.575 - 1.621 1.625 Extinction-parallel or inclined; elongation - positive or negative. Data from W.A. Deer, R.A. Howie and J. Zussman, 1965, Rock-Forming Minerals, Longmans, London. Optical Data For the Epidote Minerals The indices,birefringence, and optic angle vary rapidly with composition. There is a continuous series from Ca^Al (OH)SioO.. 2 (clinozoisite) to about 40 mol. % Ca2Fe3 (0H)Si30 2 (pistacite) . 3 _ Nx 1.718 1.712 1.722 . 1.722 1.729 1.754 1.739 1.756 NZ 1.720 Nz 1.723 1.723 1.735 1.742 1.750 1.743 1.760 1.763 1.780 1.772 . 1.795 1.765 1.800 1.789 1.829 t 2-. Nz Nx \I X Ny rx Epidoce crystals have the Ny coinciding with the long direction, thus the needles will appear to have positive or negative elongation depending upon which side they are resting. They will have parallel extinction. Data from Alexander N. Winchell and Horace Winchell, 1964, Elements of Optical Mineralogy, Part II, John Wiley & Sons, New York. Optical Properties of Kaolinite and Chrysotile Kaolinite . Kaolinite is a 7A layer-silicate with the formula Al,(OH)gSiO.q . The composition is subject to little variation but water adsorbed between the layers affects the optical properties. Nx NZ Nz 1.560 1.565 1.553-1.563 1.559-1.569 *1.562 1.566 *1.553-1.565 1.559-1.569 **1.553-1.563 -- (more water) 1.526 1.566 1.560-1.570 1.568 1.560-1.570 1.560-1.570 1.543 Extinction Parallel or Inclined 1-3 Chrysotile Elongation Positive 0 1.542 ***1.493 ***1.508 ***1.528-1.559 ***1.53-1.54 ***1.542 ***1.542 1.543 1.504 1.512 1.530-1.564 . 1.543 (calc.) 1.55 1.517 1.522 1.537-1.567 1.54-1.55 1.555 1.555 Parallel Positive -V C -f f -,- ;V, "v*T*' \ Nx ***1.546 ***1.546 ***1.548 't 1.550 1.557 1.560 Nz 1.557 1.557 1.560 '3' Extinction t ` Elongation Data from: N. Winchell and Horace Winchell,-(1964), Elements of Optical Mineralogy, . John Wiley & Sons, Inc., New York. *W.A. Deer, R.A. Howie, and J. Zussman, 1965, Rock-r-Foruling Minerals, Longmans, London. **Ralph 2. Grim, 1968, Clay Mineralogy. McGraw-Hill Book Co., New York. $ ***Federal Register, Vol. 38, No. 188. f# INVESTIGATION OF THE WINTERBORO TALC DEPOSI TS, TALLADEGA COUNTY, ALA. by Avery H. Reed, Jr.^Z CONTENTS Introduction and summary.................................. Acknowledgments........ ........ 2 Location and accessibility....... '.......... ............. Physical features...................... ......... ......... History and production.................................... Property and ownership............... ................... . Description of the deposits.... ..."..............h Character of the ......................................... Sampling and analysis. 1 ......... .....'............. ...... Work done by the Bureau of Mines.......................... Metallurgical testing...... :......... ............... *'.... . V. * . \ . 2 2 3 3 '3 5. 5 5 6 ' . . * - . *t . .-ILLUSTRATIONS . . . * Follow s Fig. 1. County index map, Alabama.......................... 2 2. Sketch map of southeastern part.of Talladega ^ County, showing Winterboro talc area............. 2 3 . -Map showing property ownership and locations of - drillholes .... ......... ..................... 2 L. Vertical sections through drill holes T.-132-T.-135 . and T.-131-T.-122...... ..................... . b 5. Vertical sections, through drill holes T.-131, . - T.-128, T.-129, and T .-13^ and T.-117, T.-119A, T.-118A,T.-1L8, T.-133U, and T.-133B...,--- - ^. $. Vertical section through drill holes T.-126,,T.-129 T.-118A, T.-lb9, T.-120, T.-136A,. 136, and T.-121 k 7 . Vertical section through drill holes T.-137C to ... T.-137G*............... ;......................... 8 . Graphic drill-hole logs of holes T.-ll to T.-133C.. 9 . Graphic drill-hole logs of holes T.-133D to T.-150A 6 6 '/ / 1 l/ Mining engineer, Bureau of Minesf Tuscaloosa Branch. Report of Investigations L66l \ The talc i3 not homogeneous for any area nor for any sample. In general, t.h A^L'A\^,m"rr,nr~ArA. n? ntv:r.hv talc that,"contains varying amounts Qt'.ral or vclToT'Tray 'r.tirvltely ml7:ed with it. an avenge section through the deposit shows, from the surface down, red and yellow clay, red and yellow clay with fragment? of talc, talc with red or yollov clgy relatively pure talc, brown clay, and dolomite. These uni to are gradational, with no sharp contacts to distinguish them; the contact between talc with clayyvnd relatively pure talc is especially irregular. The talc is quite soft and is intensely fractured. None of it appears to be suitable for crayons or other uses that require strength. The talc from the south deposit is harder and loss fractured than that from, the north - depos it. * The talc ranges in color from white and cream to yellow, gray, and blue. No appreciable amount of white talc is present, and an average sample from any large area grinds to a light cream color. The specificgravity of a representative sample of the north deposit was determined as 2.63, crushed and dried, by B. H. Clemmons, metallurgist, Southern Experi ment Station, Tuscaloosa, Ala. Few minerals other than talc and clay minerals are present. Occasional quart?. _str inyers and limonite grains are found, especially near the edges of the deposits. ' *. . . * ' f SAMPLING AND ANALYSIS . Overburden was fishtailed and carefully logged; when fragments of talc were found, coring was started immediately and continued through the talc ^ section. Holes with low talc recovery were redrilled. . Cores that contained talc from holes that showed ? feet or more of talc wore carefully cleaned and analyzed for talc, Fepih, AlpO,,, and CaO. Sample intorvals from the cores were selected g o as to determine the maxi mum amount of high-grade talc present in each core. . , Talc cores from holes that sheared less than 5 feet of talc hr from isolated situations were not analyzed. The *talc from these holes was generally low-grade and thoroughly mixed with clay. ., Twenty-seven samples from 12 holes were assayed. Of the 75 holes drilled, 4l penetrated talc or talc fragments. . WORK DONE .BY THE BUREAU OF MINES .. The Bureau of Mines investigated the Winterboro talc deposits by dril I m g 75 holes totaling 3370.4 feet. . .^ Holes were drilled within and around the two known deposits, and with in the area between these deposits, . , 3571 5- 1 iV 'V.y. ; W ETUM PKA PR IN T IN G CO. Pristen and Publiihen Wetompka, Ala. 1941 a LETTER OF TRANSMITTAL University, Alabama March 25, 1941 Honorable Frank M. Dixon, Governor of Alabama, Montgomery, Alabama. Sir: I have the honor to transmit herewith the manuscript of a report entitled "The Talc Deposits of Talladega County, Alabama" by Lynn McMurray of the Tennessee Valley Authority and Edgar Bowles of the Geological Survey of Alabama. It is requested that this be printed as Circular Number 16 of the Geological Survey of Alabama. Respectfully, STEWART J. LLOYD, Asst. State Geologist W TM PK A PRIN TIN G CO. Printer* and Publisher* Wctampkm, Ala. 1941 \' LETTER OF TRANSMITTAL University, Alabama March 25, 1941 Honorable Frank M. Dixon, Governor of Alabama, Montgomery, Alabama. Sir: I have the honor to transmit herewith the manuscript of a report entitled "The Talc Deposits of Talladega County, Alabama" by Lynn McMurray of the Tennessee Valley Authority and Edgar Bowles of the Geological Survey of Alabama. It is requested that this be printed as Circular Number 16 of the Geological Survey of Alabama. Respectfully, STEWART J. L L O Y D ^ t Asst. State Geologist 12 C E O L O C I C A L S U R V E Y OF A L A B A M A BENEFICIATION OF TALC ORE FROM TALLADEGA COUNTY INTRODUCTION This report deals with laboratory tests which were made on a talc ore frmn Talladega Comity, Alabama. These tests were in cort^^^iinn wiiji ;tn in''C?t>i^nt!0!! of td!c ores in the Tennessee Yai^Hand nearby region in an attempt to prepare products which could be ti^cal in the ceramic, textile, paper, cosmetic, and other ind"-tries requiring a high grade talc. Initial investigations showed th.ii onl y some of these ores were amenable to beneficiation methods. The beneficiation methods which proved most applicable were froth flotation and acid leaching. Many of the talc ores were found to contain appreciable percentages of serpentine and chlorite, which p;e\euted them from becoming white on acid leaching. The acid leaching removes only the soluble iron from the ore. All of the talc ores, however, could be froth floated to a high purity, but only those which could be acid leached were suitable for refine ment to high quality products. As the Talladega County deposit could be acid leached, it ap peared that a laboratory investigation toward the development of a sui^iie flowsheet would be well warranted. CHARACTER OF THE ORE Three samples, totaling 600 pounds, were taken from the depos so that a reasonable accurate cross-section of the ore body w a; A `-lined. The mineralgica! and chemical analyses of these sampw" . -kewr. in Table I, indicate the rather uniform character of the ore body. \ h. TALC DEPOSITS OF TALLADEGA COUNTY, ALABAMA 13 TABLE I Chemical Analysis of Talc Ore from Talladega County, Alabama Sample No. 1 ___ 2 ___ 3 ___ MgO 31.25 , 29.12 SiO, 61.74 60.78 31.05 62.50 FejO ALOj CaO 1.60 0.50 0.22 2.12 1.98 0.42 FejOj, ALO, CaO 1.80 Loss at 900" C 4.84 5.41 3.75 Mineralgica! Analysis of Composite Samples Shown Above Sample No. Talc Garnet Quartz Iron Oxide Clay, etc. Composite (1, 2, and 3) 93% 2% 2% 2% 1% The talc as it occurs is surprisingly pure, but the presence of small amounts of garnet, quartz, and iron oxide prevents its use as a high grade talc product. A physical study of the talc ore reveals that the garnet is liberated at 100 mesh and the quartz at a much coarser sizing. The iron occurs in streaks, pockets, and coating on the crude ore lumps. Grinding to 200 mesh is required to liberate this iron so that it will come in contact with the acid during leaching. As es sentially all talc products require grinding to minus 200 mesh or less, this offers no additional treatment over that already necessary for marketable products. No serpentine or chlorite or dark colored minerals, other than garnet and iron oxide, occur in the ore. BENEFICIATION TESTS The froth flotation problem was the separation of the garnet from the talc. The quartz and appreciable amount" of the iron oxide could be easily depressed in the flotation cell. With any reagent combination used, a small amount of garnet contaminated the concentrates. In the laboratory garnet was removed by a magnetic separator, but the necessary fineness and dry condition n ncTni!1f` cnrV i in 'rtn im a rp l'il fc