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FILE NAME: Johnson & Johnson (JAJ) DATE: 1971 DOC#: JAJ043 DOCUMENT DESCRIPTION: Excerpt - Text from Colorado School of Mines Research Institute : METHODOLOGY ! s 1 f i 1 ^ 1 11 i * . I1* ' . . r*.* %u' *<1* . mj r 'L t f i COLORADO SCHOOL 0F MI.N'Ei S RESEARCH INSTITUTl 1 . r 11 1 * . Ii ^INTRODUCTION * * i This report covers methods that have been developed,, are presently being used, or jare being investigated by the Colorado.School -of Mines Research Institute relative to the examination of talc samples. The main emphasis of this study was to develop methods to-accurately determine the . mineralogy, particle size, and particle shape distribution of finished prod* ) . uct 'talc samples, ,' ' i Protected Document-Subject*) Protective Order JNJAZMJM00MM2 .' C O L O R A D O S C H O O L OF 1C H I N S T I T U T E h .9 t ' MICROSCOPE! TECHNIQUES ' ' 1 .. ' . . .GENERAL . , ' ' ( ' ' ... i A Leitz polarizing microscope is the microscopic tool used in the examination of talc, samples. The lens system .of the polarizing microscope is in many, respects sim ilar to the lens sy.stem of the usual compound m icro -' scope hut has several modifications such a s : (1) polarizing.devices, both t f . ` above and below the stage,. (2) a rotating stage, and (3) accessories such as ' a- mica plate, a gypsum plate, and a quartz wedge (etc. ). This type of microscope is extensively used to examine mineral fragments, sinali cry s- * , tals (etc. ). It i's extremely useful in the determination of optical properties . of individual crystals,, m ineral associations,.and size and shape of m ineral' K grains. The microscopic procedures herein outlined were all performed.at - 500X in an index oil having a refractive index of 1.600'. This oil was chosen . because the refractive index of the a and b axis of the platy talc examined s>.\ , . , * ' approached i . 590. When the index of the oiL matches that 'of-the mineral r- being observed the m ineral is.not visible in ordinary light. The spread of ` .0.01 between die, 1.600 oil.used and the 1.590 of the tale made the tale min-. . ' 4 erals barely visible- in' ordinary light, thus facilitating their identification. ` * , The other nontalc minerals were dearly visible due to observable negative - o r positive reliefi. Otier optical'properties 'suedi; as optical sign, .interference figures, .. extinction angles, birefringence (etc.} were.also used for mineral identifica- I tlcin.- 10X oculars were used in ell studies. One ocular contained a cross Protected OoeumwW IuNeetto Protective Order JNJAZ5S_000006063  1,.H* ***' --rf.. M I* COUOflADO SCHOOL OP MINES' RESEARCH INSTITUTE hair and one contained a graduated scal that was calibrated from astage ' micrometer. j ` The lower resolution limits of our optical microscope is approx!I mately 0.5 m icrons, therefore all data procured refers to particles above that size. SAMPLE PBOOUHEMENT AMD PREPARATION FOR . FOI^T COUNTING Many attempts were made to split a representative sample from a' . standard finished product (-325 mesh, Tyler) using a variety of standard sample splitting devices. None were satisfactory due to severe dusting and \ i 1 m aterial caking problems in the devices. Xt was found that a small sample . . . t* procured from dear the center portion of the submitted sample proved the best method for obtaining a representative sample for microscopic analysis. Assays have shown this type of sampling to be representative. .. I ' 1 The preparation of the sample for microscopic examination can be- outlined as follows: .. i' : ' . ' 1. Place a dean, dry standard glass microscope slide bn a flat 1 . ' . ' ! . . surface.- It is extremely important that the slide be washed with acetone of alcohol and wiped clean with a tissue that will not leave adherent, fibers on the slide. ` . t ** I-' 2. Place one drop of the 1.600 refractive index oil near the center ! |of the slide. ' J ; j-' 3. Place the-talc sample in the oil and gently s tir the. slurry until the particles are evenly distributed by visual observation. ! ! JNJAZMJDQOOMOei <0 I ' [ / 4, Place a clean, dry 2 cm x 2 cm glass coyer glass on the slurry of oil and talc. . j" , :9 5. Place the sample on the. rotating microscope stage containing ' ! f a standard mechanical stage mechanism to control the amount of horizon- tal and vertical movement .during the microscopic examination. 6. Calibrate the mechanical stage so that the entire 2 cm x 2 cm cover glass area will be traversed during the 500 grain point count. . 7. Adjust the microscope Lights in such a manner that will produce I transmitted light. Xt was found a blue filter between the Light source and the sample produces better results in regard to mineral identification (etc. J., 0. Observe the sample at iOOX. It will become apparent upon close * , t * . . observation that many plates will be standing on edge giving the. effect of needles. / * 1 ^ i 9-' With a dissecting needle gently touch the cover glass, 'this will usually cause the plates to rotate and lay flat. Much caution must be used in ' j` l * . this procedure that no extreme downward exertion be applied. Too much ' downward exertion will cause*a squeezing-effect and many particles will be moved to the outside of the cover-glass. ! ` ` . " 10. Now observe the sample at 500X and move the elide so as to sta rt the examination at one corner of the cover glass. Using the intervals I determined in No. 6 (above) move the elide and make determinations of the (/particle un' derthe cross hai.r at 1each move-m1ent interva.l.j. 11.. It may be necessary to use the dissecting needle occassiohally i . ! j throughout the examination to touch the cover glass to help orient the grains. ^ ! Again much caution-must be used so as not to produce a "squeezing effect." < ` *Vf\- .. , i t *. | I Doeument-SuSitct to ProtMtlvt Qrdbr "rr; ,i* *>. . JNJAZM_00000*08S _ i _: I--*A/.* .'.-* *l CO LO R A D O SCHOOL OF MINES RESEARCH INSTITUTS V. V *.V' :* ' <r.11`.1 .>..< . II` I 5 'MINERALOGY . i Each particle examined Is Identified by using standard optical . techniques and placed in one of the following categories. (It is advisable to make tablesf sim ilar to the one shown in Figure 1 to record all data. I J * | Enough of these sheets are necessary to accommodate 500 grains.) I 1. Plates (talc and/or chlorite) -- Particles that .could positively . L f be identified as plates. I 2, Talc Shards These are thin pieces that could definitely be II ! defined as being pieces broken off of plates. This entails a very detailed stuify of each piece to determine if ragged edges (etc.) are present. These ' . particles have Length/wtdth ratios of 5:1 or-less. Ik.,,i* 3 ':.l / :/ 3. Talc Needles -* Tt hese are p,articles that have (a) parallel extinc- . l * , tlon, -(b) refractive indices approaching 1.590, and (c) length/width ratios .greater than 5:1. j I f ' if ` . . ..r , } -V 4. ' Nontalo Needles* -- These a re particles that had: -(a) nonparallel extinction, (b) refractive indices above or below the 1.400 oil used, and (c) t* leagth/width ratios greater than 5:1.. 5. Quartz- - - This m ineral was' identified by staihdard optical tech- ; i, i ' I r * . !.* niques. '* 6. Carbonate -- .This m ineral was identified by standard optical h II techniques. !. 7, Diamond-Shaped Particles These are .minute.(1-2/x) particles' * N. that are definitely diamond shaped and'have refrgctive'^indices above 1.500.. These were tentatively Identified as carbonate or pyroxenes. Protected Document-Subjectto Protective Older JNJAZSBJKBODCOW . C O L O R A D O S C H O O L OF MINI'S.' A S 8 8 A A 6 H I N S T I T U T I I 8. Other Particles -- These are birefringent particles'usually in ' /. the 1,0-0.5 micron range that could not.be positively identified optically. - ' . ' i! . 9* Dark Opaque. -- These are particles that do not transm it light. 10. Granular Masses -- These are m asses of nearly submicro-' scopic particles that appear to be tightly bound to each other, and not merely 1 " ` . poorly dispersed masses of fine particles. ; i PARTICLE SIZE AND SHAPE : . On the table shown in Figure 1 the following was recorded unde*. r', each mineralogies! category noted: (1) maximum length of each.particle observed/ (2). maximum width of each particle observed. These m easure-' ments were recorded as direct ocular micrometer measurements. They' were later converted to millimeters or microns for size distribution analy-' ses. PARTICLE SIZE AND SHAPE DISTRIBUTION. . . * * . - * .* i* The size distribution of particles Is dependent upon the ultimate- " I , information desired (shortest dimension, area, number of grains/ etc.); ' , * , *i , 1 * r The things that have to be decided.before making .the distribution may be- outlined as follows: ' i 1 } i 'I - 1. What type of size data, is needed: I (a) Size based upon sm allest dimension; l . " * . (b)' Size based upon longest dimension. , ' . , * . * * * *\ (c) Size based upon square mm or square micron area.' . 2. ..What upper and lower size lim its and size increments are-'needed in the study. Protected Document-Subjectto P ro te g e Order t Ji.-c*. ' ' * . v - n . . t . . - | i . . I*. . K *`VJU rr?I;' / C O L O R A O O i C H O O L OP MINCS R S S t A R C H INSTITUT S 8 ` . .. ' : . 1. ; 3. ' Is the study to-be confuted to individual 'mineral groups or a ' 1 . . combination joi-mUieral groups. . ` ' ' -' ," < 4. Is the data to be presented as number 'of particles or the p e r - ' ' ! * ..**' ' * . centage of particles In each category (etc. ). . /'In' our studies a Pacific `Data Systems 1020 tape computer was used ' 1 ' . -L ; ' for the conversion of ocular units to- m illim eters or microns and the sorting '/ ` of particles into each size range required... . ' ' n. The distribution of particles based on'particle shape involves only . .;' / . the ratio of length to width based upon the ocular units; the conversion to . ** '' i .* , I , . .. m illim eters or microns is not necessary. Again lim its must be set and Again we used a Pacific .Data System 1020 computer to sort the ratios obtained - ;' i . . . * . , into the desired categories. ' J? i 1 . * If the volume or weight percent of various types of grains is desired from optical microscopy,, bare must be exercised.to insure that the most . v. , * meaningful type of data are obtained, If grains are simply counted without ' ' regard .for their size then the data are not applicable to volume or. weight i'A * | percent analysis unless all of the jpartid.es have the same volume and specific 1 g ravity.. This.may be illustrated by the following example. A sample con- , * ! * ' * *t. 4 4 . . sis ts of 2. grains In which-grain A has a volume of 100 cubic microns and grain- B has a volume of l cubic micron./ On the basis of grain count alone, each . grain comprises 50% of the.sample.. However, on a weight basis there is 100 '. tim es as much of grain-A as there is -of grain (assuming equal specific . V"'- . gravities). Ideally, the volume of each grain should be measured and its V . * . * i f weight computed from its specific gravity. However, this is not practical by .'. PretMted Doeumnt-Subj*etto Protect* Order JNJAZBS_OI)OOMMB ;i l'nfiilo.i t ' C O L O R A D O S CH O O L O f MtNBS RBSE A-RCH INSTITUTE 9' r i ' . ^.. optical microscopy since only 2 grain dimensions are observed. The ' best approach, therefore, is to measure the observed cross-sectional grain area for quantification of each grain type. This was.the approach used in our determinations of various talc products. < X-RAY ANALYSIS TECHNIQUES 4 * GENERAL - Brindley, 1961, states , * j . "The basic principle underlying the . , * identifi- i cation of m aterials by. x-ray or by;' electron diffraction is that each crystalline t . , substance has its own characteristic atomic structure which diffracts x-rays i' * or electrons, in a characteristic pattern. The recognition 6f the pattern ! ... I g. * ' . \\ establishes uniquely the diffracting substance." * * t The two methods of x-ray analysis most generally used are x-ray. ' powder diffraction techniques utilizing a scanning goniometer and circular ' jpowder camera techniques. Basically both methods produce sim ilar data I although one may be superior to the other in certain instances. In both tech- |j niques a generator of x-rays is needed. In our studies Cu- radiation filtered I !. v j with a Ni filter and a goniometer scanning speed of 2"/minute were utilized * ' . * n , I** V in the powder diffraction. Cu radiation was also used in the circular powder `> j camera work. \ ' POWDER DIFFRACTION TECHNIQUES UTILIZING " o M m E -------i ------- ---------- '------- ---- In this process about 0.5 g of sample is pressed into a standard i1..1 .. sample mounting plate This sample is then scanned, using a goniometer, at 1 I 2'/minute and the diffracted x-rays that Indicate- "d" spacings (lattice specings) Protected Document-Subjectto Protective Order JN JA Z 96.000006070 , H' J. jiLi-. , ..COLO RAD O SCHOOL OF MINIS RgSEARCH INSTITUTS 10 t. I . . ' . '. I . ' ** t t; are tracted on a graph, that is moving in phase with the speed -of the gonio- 1I m eter. The advantage of this type of analysis is that a relatively large sample can be examined. This increases the chance of a representative . ' I t I sample being analyzed. The disadvantage is that because the goniometer is moving at 2^minute, minor to trace amounts of m aterial.may not be detected. CIRCULAR POWDER CAMERA TECHNIQUES i * . In this process a very sm all amount (0 .1 g) of sample is-either I ' 1 mounted on the end of a glass filament or mixed with.a m aterial invisible to' i, > the x-ray beam and rolled into a needle containing the'm ineral fragments, or .if packed into a' glass capillary tube. This sample is then placed in the center , of the powder camera and rotated in the collimated x-ray beam. 'Hie diffrac- , tion lines in this technique are recorded on a piece of strip film placed on the i peripheral inside edge of the cam era. The advantage of this method is that i i : j the exposure time can be varied, thusly producing a situation where very - .-i ` . . minor amounts of m aterial can be detected. The disadvantage is that because 4. i of the small sample size much care must be exercised to assure a represen- tative sample is being analyzed. It is advised that both methods be used to-' examine samples in question. / / * ` ' ELECTRON MICROSCOPE TECHNIQUES * * I * . * ` ' : . 8NBRAL *iI , * The electron microscope-is a tool used to show directly the morphology of very small particles'.- This technique is usually used on finely dispersed r II m aterial resting w * Protected Doeum tiifc-StfbM to Protective Order JNJAZSS.DOOOOfi071  I 5! , amu >--ntyi ifiIftiVrttjili1 . C O L O R A D O S C H O O L - OP M I N E S R E S E A R C H I N S T I T U T E II r- l1 . * . j .-P-O--S--S--I-B--L-E--'-U--S-E--S- ' I \ . ' This tool has been used extensively to observe the -morphology of ' Submicroscopic particles in various samples. Although some wprk has ' . been done on the. morphology of submicroscopic' particles, in talc samples, I . . i * I th is tool will probably prove invaluable in regard to particle shape in the 1 submicroscopic fractions of talc. Again, as in circular powder cam era - I analyses, there may be serious problems in the procurement of a rep re- . i . . ; :- ' . '` i sentative-sample If the tool is used for size distribution (etc.). -This may be m ore of a problem in electron microscopy than in powder camera analyses since a sm aller amount of sample is .Used in electron microscopy. . ELECTRON DIFFRACTION TECHNIQUES . *. * \ * -. ' ' , " J 5* GENERAL ... t ./ ` . .. :. ; This technique Is sim ilar to.x-ray diffraction but utilizes electrons >> for diffraction rather than x-rays. The combination of electron diffraction ' i ,.' . e\ * * 4 * ! - . , I' and the electron, m icros cope provides-a means to identify both the shapes and .A -crystal- type of observed particles'. It is possible to isolate single grains and do single crystal electrbn'dlffraction analyses to identify individual grains. POSSIBLE USES ' ' * . 1 . I : This tool,' coupled with the electron microscope, could prove invalu- ` able in the identification.of submicroscopic particles. . 'V. *! y- . ELECTRON PROBE MTCROANALY-ZER TECHNIQUES" * * , . . t. * >,' The electron probe microanalyzer concept is an outgrowth of the ' following: (l) electron microscopy, which introduced teehninncn t- >p Protected Document-Subject to Protective Order JNJAZ65_000006B72 iB . .1? ' , K ' 'i- ; X jL. yV',. .. ' ' ' C O L O A A O O SfcHOOU 0 P M|N6S r e s e a r c h i n s t i t u t e !* 12 and controlling electron btsams;' (2) x-ray spectroscopy which provides a relatively simple instrumental method for chemical analysis; and (a) light optical microscopy, which provides for viewing a specimen and visually ' selecting areas for analysis. P ossible! u ses ' ' *' Since this, technique is capable of making nondestructive, chemical analysis on particles down to approximately 1 micron in size, it can be very useful in chemically analyzing small particles. The technique is also cap able of making 1 micron wide line scans across particles to determine com .. t positional variations. A visual .display, showihg'the distribution of various' ***. elemen. ts -over iselected are. as. o.f a- specime.n, can be provided.. Photographs*` Of the elemental distribution can be made for permanent records. NONMICROSCOPIC TECBNQIIJBSTO DETERMINE 1 . PARTICLl SDgg A N g ^ A P S iSUTfON- * J \ GENERAL ' ..IV` f * , f * ,* * The possibility of-size distribution analyses of-tale using nonmicro- - scopic methods has been a m atter of much debate and examination. Li$xt v ' - i ' optical xtflcir6scoplc methods of particle size and shape distribution, is % theoretically accurate but it is time consuming and is limited to particle size .1. ; ; . . / abo.veOr.,5 m, i*cro*n. i *`*I . . POSSIBLE USES /. ' fi . / Many types.of particle size and shape methods have been examined and most contain numerous pitfalls. In regard to standard sedimentation * u * (StokSs law), particle shape, differential particle sizes, and.temperature Protected Document-Subject to Protective Order JNJAZ65JD000QM73 I ft.iU -rf-- - #'/v ` t'thiHMflcildrtli * ' * C O L O R A O O 8 Q H O Q 1. O f M i n e s K 8 S S A R 0 H I N S T I T U T E 13 . play such a critical role that the validity of results is debatable. Studies f i . ' at fcSMRI have indicated that even th most gentle dispersion and centri- I fge techniques tend to produce fines in talc. Some methods have been investigated that do not involve agitation (etc. ). These methods basically involve mounting a specimen on various media ahd scanning them with Various light or radiation sources. These methods appear most usable at this point in time but one major drawback can be recognized. As was m en tioned in the section on light microscopic examination of talc samples many of the talc plates tend to stand on edge giving the shape effect of needles.. These particles are properly oriented in the light optical microscopic exam- . . I?* , ' * illation before measurement. It is debatable if this degree of proper orlen- ' .' / ' ' tation can be achieved in the'sizing devices mentioned above. i 4. Protected D ocuintnt-Subjeet to Protective Order I II . JNJAZ6C_OOOOM074