Document Z40bKbE5RY2939pOydQkX61V7

FILE NAME: Johnson & Johnson (JAJ) DATE: 1959 Aug 31 DOC#: JAJ032 DOCUMENT DESCRIPTION: Report - Ultrasonic Comminution of Talc Presented to J & J Research SUMMARY REPORT D o cu m en t-S u b ject to P rotective O rder JNJNL61_00M 01389 BATTILLE FIELDS OF RESEARCH AlRONAUT.CAl ENGINEERING AGFICUITURA'. .SCIENCES AIR AND S I XLAV. POlllM ION CONTRO! ANALYTICAL CHEMISTRY mOCHi'MISTEY PIOfilYSiCS CIRAMCS CKtM 'CAl 11'O .N iniN C CORROSION TICHNCLOCY iCONOoUCS r i l l . . C A I FN C N ltR IN r u r c r P 'O it v iiA i c n c in u r in g i : f.'Tpc^ci uA*irr y iiU'KCH'ilCi KTRACTIVf. M lTAlUlPCY to o :- a n d io o d p r o c i s s in c lO N ST PRODUCTS. FOUNDRY PRACTICE. FUTI. AND COMBUSTION FiRAnne ARTS TLCMNOIOvY H`C-H-UMPCRA1USE ME)AUURC.Y INDUSTRIAI PHYSICS INFORMATION PROCESSING IN OkCA N IC CHIM W RV INSI RUMI NTATION 1I0 HT AUOYS AND BARE MITAIS MECHANICAL IN.UNI l PINO METALLURGY MINI RAIS I'kOf.l ` SING NONOfSTRUCTl`*I INi-TtC.llON NUCLEONICS OPl RATIONS Ri MARCH ORGANIC CHEMISTRY ORGANIC COATI NC-S ftTFOll.UM LN.-I.NL.IKNS PlIVSiCAt CHIMI:.T#Y PROCI SS ATT ALI :Rl.( PRODUCTION [NC-lNtlMNC. 'U:1' AND PAN R ra d io iso to pi;, and sa n a tio n I ACTOR TfO'NOiOGr If.ISStk AND I !ASDCS SOI ID STATI DtviciS SYMlMS ENGINE) RING u x ia rs and ii wss lltlORlTICAl ANi- v.KH.WCS THERMODYNAMICS V iC iniN G YtCIINOLO-Yi P rotected D o cu m en t-S u b ject to P rotective O rder JN JN L 61_000001370 BUSINESS CONFIDENTIAL SUMMARY REPORT on ULTRASONIC COMMINUTION OF TALC to JOHNSON AND JOHNSON RESEARCH August 31, 1959 by J. N. Antonovich, W`. E. Chase; and L. Et Walkup BATTELLE MEMORIAL INSTITUTE 505 King Avenue Colunibua 1, Ohio Battelle is not engaged in research-for advertising, sates promotion, or publicity purposes, and this report may not be'reprodueed in full or in part for such purposes. BUSINESS CONFIDENTIAL itected Docum ent-Subject to Protective O rder JNJNL81J000001371 BUSINESS CONFIDENTIAL Battelle Memorial Institute so s K I. H 0 A V E N U E COLUMBUS I, O H I O October 8, 1959 Mr. W. H. Ashton Research Department Johnson and Johnson New Brunswick, New Jersey Dear Mr. Ashton: Work on the project "Ultrasonic Comminution of Talc" has been terminated, as requested during your July 27, 1959, phone conversation with Mr. Macdonald of our Minerals Beneficiation Division. ; We are submitting a report on the work done. On the basis of incomplete data, it appears that the ultrasonic comminution of tale can be developed into a useful process for producing high-quality powder. The data Ire not sufficient as yet, however, to de fine all the param eters that influence the ultrasonic grinding process. We would be glad to undertake this further work if Johnson and Johnson should decide on the basis of this report to reopen the study. The adaptability of various transducers to determine mini mum equipment and operating costs for processing talc with vibratory energy also should be included in any further work. We enjoyed working on this project. If there are any questions concerning the report, we would be glad to answer them. Very truly yours, LEW:mar Enc. (6) cc: Dr. W. H. Lycan Mr. C. V. Swank --- - -- --- -------r J Applied Physics Division .) DEDICATED e cted D o cu m en t-su b ject to P rotective O rder SCIENCE JNJNL81 000001372 BUSINESS CONFIDENTIAL TABUE OF CONTENTS SUMMARY.................................................................; ............................................ 1 INTRODUCTION.................................................................................... w . . . 1 EXPERIMENTAL. PROCEDURE ...................................................................................... 2 EXPERIMENTAL R E S U L T S ...........................................................................................4 DISCUSSION............................................................................................................. 11 CONCLUSIONS AND RECOMMENDATIONS................................................................ 12 LIST O f PIQURES Figure 1. Assembly for Comminuting Tele With 20-Kc V ib ra tio n s .................... 3 Figure 2. Relationship Between Amount of Minus 10-Mesh Talc Comminuted to Minus 200 Mesh, and Treatment Time at Various Ultrasonic Power L e v e l s ..........................................................................................5 Figure 3. Relationship Between Comminution Rate and Solids Content of a Minus 10`Mesh Tale Slurry Exposed to 20-Ke V ibrations.............................. 5 Figure 4. Relationship Between Comminution Rate and Ultrasonic Power for Batch Grinding of 10-Mesh' Talc to Minus 200-Mesh Talc . . . . . 6 Figure 5. Relationship Between Comminution Rate and Ultrasonic Power for Grinding a Simulated Recirculating Load of 10-Mesh Talc to Minus 200-Mesh T a l c ................................................................................................6 Figure 6. Relationship Between Exposure Time to Reach Equilibrium and Ultrasonic Power When Grinding a Simulated Recirculating Load of 10-Mesh Talc to 200-Mesh T a l c .................................................................. 6 Figure 7. Photomicrograph of Minus 200-Mesh Plus 10-Micron Fraction of Ultrasonically Ground T a lc ...........................................................................10 UST OF TABLES Table 1. Size Distribution of Comminutsd Talc When Treated With 1. 28 Kw per 50-Gram Load ................................................................. .... 7 Table 2. Distribution of Particle Sines in Flotation Feed Obtained From Com minuted Talc When Treated With 1.28 Kw per 50-Gram Load . . . . 7 Table 3. Flotation Results Obtained From Ultrasonically Comminuted Talc . . 8 . Table 4. Particle-Sine Distribution of Series I and Seriss II Samples . . . . 9 Table 5. Mineral Character of Series I and Series U S a m p le s.............................. 9 A TTIU I MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL cted D o cu m en t-S u b ject to P rotective O rder JNJNL61JKM 001373 BUSINESS CONFIDENTIAL ULTRASONIC.COMMINUTION OF TALC by J. N. Antonevich, W. s . Chase, and L. E. Walkup SUMMARY A study was made of the process param eters affecting ultrasonic comminution of plus 200 minus 10-mesh talc to plus 10-mieron minus 200-mesh talc. It was found that the rate of comminution in a batch process and a process in which the oversijse fraction was recirculated increases linearly with ultrasonic power. At a given power level, the process using a recirculating load was three times more efficient than the batch process. A talc slurry having approximately 40 per cent solids appeared to give optimum com minution rates. On the b asis of line power consumed by the m agnetostrietive transducer assem bly used in this study, having an o v er-all efficiency of approxim ately 15 p er cent, the total energy required to grind 1 pound of minus 10-mesh talc to minus 200-mesh tale ranged from 3 to 4 kw hr. The use of fluid dynamic tran sd u cers can possibly reduce to tal energy requirem ents by a factor of 10. Ultrasonic grinding appears to be selective in producing platy talc preferentially; the ground plates appear to be thinner than those produced by conventional grinding methods, and about 80 per cent of the individual plates have rounded corners. There is an indication that some of the im purities in platy talc, although not the carbonate, are finely ground during ultrasonic grinding and can be rejected by simple classification. In one instance a product p rep ared in this way contained 98 per cent platy talc. The application of ultrasonic or sonic energy to grinding talc into a high-quality powder appears to be technically feasible. Additional studies will be needed to define the practical limitations of the process. INTRODUCTION P rio r to this project, exploratory experiments had been conducted using ultrasonic techniques to comminute talc. They indicated that plus 200 minus 10-mesh talc can be comminuted to minus 200 mesh at a power rate of 1800 kwhr/ton. Microscopical ex aminations of the ultrasonically ground talc showed a high-quality talc, in that individual talc platelets were intact having rounded corners and appearing to be in the thinnest possible platelet form. There appeared to be some degree of selective comminution, i. e . , only talc appeared to be comminuted --other m inerals in the raw ore were not ap preciably broken down. BATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL itecta d D o cu m en t-S u b ject to P ro tectiv e O rd er' JN JN L 81_000001374 BUSINESS CONFIDENTIAL 2 The apparent high quality of the ultraaonically comminuted tale and the reasonable power cost estimate of 1 cent per pound (on the basis of 1 cent per kwhr for power) warranted further investigation. On April 1, 1959, an investigation was undertaken on the effects of frequency, power level, and initial particle size on the comminution rate and final particle size of talc exposed to vibratory energy. This report describes the work done toward establishing the important process param eters affecting the comminution of plus 200 minus 10-m esh talc to plus 10-micron minus 200-mesh high-quality talc. BXPgWMIiNTAL PROCEDURE Investigations were made into the process param eters affecting ultrasonic com minution of plus 200 minus 10-mesh talc to plus 10-m icron minus 200-m esh highquality talc. These process param eters include the solids content of the talc slurry, and the ultrasonic power level as they influence the ultrasonic comminution of talc in a batch process and in a process in which the oversise fraction is recirculated. A Sheffield-Cavitron Model 1000 A power oscillator and 20-kc transducer (Sheffield C orp., Dayton, Ohio) were used to generate ultrasonic power. Figure 1 shows the experimental arrangement used for m ost of the experiments. It consists of a stainless steel chamber 4 inches, deep, having an inside diameter of 1-3/4 inches. This chamber was inserted within a coil of 1/4-inch copper tubing, and was restrained and gasketed within a steel enclosure constructed about the coil. The temperature of the talc slu rry was maintained constant by running tap water through the copper tubing. This eliminated the possibility of tem perature influencing foe comminution rate. The chamber assembly was fitted over a standard double-cylinder mechanical transformer or horn (Sheffield No. 35-258) having a 1-1/ 2-inch-diam eter radiating face. A nO -ring was used as a seal between the cylindrical chamber and the horn. Relative power supplied to the transducer was monitored by an ammeter in the plate circuit of the power oscillator driving foe transducer. It was assumed that the power output of the oscillator was directly proportional to the plate current, and that the oscillator was 50 per cent efficient. With these assumptions, maximum power de livered to the transducer would be 1 kw, .the rating of the transducer-oscillator-com bination. The total maximum power conS.umed from the line would be 2 kw. Slurries of desired solids content, composed of plus 200 minus 10-mesh talc and deionised water, were placed in foe chamber to form a column 3 inches deep. This depth was chosen as it appeared to produce a resonant column with 20-kc vibrations at any concentration of talc investigated. A resonant column is desired for maximum energy transfer from foe transducer to foe slurry. The natural agitation accompanying the ultrasonic treatm ent of low talc concentra tion was sufficient to obtain reproducible comminution results. At high solids content, results were not consistent. To obtain consistent results, a stirring motor had to be used to keep talc from settling on foe vibrating face of foe double-cylinder mechanical transfo rm er. BATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL P rotected D o cu m en t-S u b ject to P rotective O rder JNJNL61 OOOOOf BUSINESS CONFIDENTIAL 3 Tole slurry el chamber, Copper cooling coil Cooling coils Water couplant Gasket 0 - ring seal / D ouble-cylinder------ -- mechanical transformer Radiating face \ ------- Transducer A-SS4.0. FIGURE 1. ASSEMBLY FOR COMMINUTING TALC WITH 20-KC VIBRATIONS BATTELLI MEMORIAL in st it u t e BUSINESS CONFIDENTIAL D o cu m en t-S u b ja et to P ro tectiv e O rder \|NJNLB1_000Q01376 business confidential 4 The criterion used lor comminution was the weight of talc ground sufficiently to pass through a 200-mesh sieve. In the case of batch treatments the talc was exposed to 20-kc vibrations for 5, 15, and 55 minutes. At the end of each exposure, the talc was sieved, dried, and weighed to determine the amount of talc reduced .to minus 200 mesh. In the case of recirculating-load treatm ents, a given concentration of plus 200 minus 10-meeh talc was given a series of 5-minute treatm ents. At the end of each 5minute period, the fines passing through a 200-m esh screen were collected, dried, and weighed. An amount equal to the fines removed was added to the-remaining talc to maintain a constant concentration of talc for each time period of treatments. EXPERIMENTAL RESULTS A series of experiments was made to determine the comminution characteristics of talc treated in batches. Figure 2 shows the relationship between the amount of a 25-gram talc load comminuted to minus 200 mesh and the time of treatm ent at various power levels. A series of experiments also was made to determine the influence of solids con tent on the ultrasonic comminution of talc. Figure 3 shows the relationship between comminution rate and the solids content for a fixed time of exposure and power level. For the experimental arrangem ent used, a talc Slurry having a 40 per cent solids con tent appeared to be b est. At other power levels and s tir ring conditions, it is possible that other concentrations would be found better. An ideal arrangement would be one in which the energy density and particle distribution throughout the slurry is uniform. Under such conditions, the rate of comminution might be directly proportional to the solids content as indicated by work reported on the ultrasonic dispersion of Progesterone*. Figure 4 shows the relationship between maximum batch-comminution rate and electrical power used in processing the talc. The relationships shown are linear for talc loads having 20 and 35 per cent solids content. A series of experiments also was made to establish the comminution character istics of talc when e recirculating load was exposed to ultrasonic vibrations. Conditions of a recirculating load were approximated by treating the load for 5-minute periods, removing fines and adding an equal amount of coarse talc at the end of each time period, until the amount of fines removed was constant. Figure 5 shows the relationship obtained between comminution rate and electrical power for a simulated recirculating load. Figure 6 shows the approximate time re quired to reach equilibrium in the simulated circulating load at various power levels. Twelve pounds of minus 10-mesh talc was batch treated using an equivalent of 1. 28 kw per 50-gram load in'the experimental arrangement. Each batch, or charge, B., andSktven, S. M.. "AStudyofSiipsnioawithOiuuousd". J. Am. Ritrm. Alice.. ScientificEdition. XLV1I. (1) (Jan. 1888), reprinted In Ultroonlc New, (7), 13-16(1851). ATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL P rotected D o cu m en t-S u b ject to P ro tectiv e O rder JNJNLBijDOOOOl BUSINESS CONFIDENTIAL 5 FIGURE 2. RELATIONSHIP BETWEEN AMOUNT OF MINUS 10-MESH TALC COMMINUTED TO MINUS 200 MESH, AND TREATMENT TIME AT VARIOUS ULTRASONIC POWER LEVELS Frequency of vibration, 20 kc; weight of ta lc , 25 grams; solids content of slu rry , 19 p er cent; transducer rating, 1 kw FIGURE 3. RELATIONSHIP BETWEEN COMMINUTION RATE AND SOLIDS CONTENT OF A MINUS 10-MESH TALC SLURRY EXPOSED TO 20 KC VIBRATIONS Exposure tim e, 15 minutes; transducer driven at 50 per cent rated power; volume of 8lurry, 118 cm^; tale ground to minus 200 m esh 8 ATT KU S MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL D o cu m en t-S u b ject to P rotective O rder JN JN L 61J)00001378 BUSINESS CONFIDENTIAL 6 FIGURE 4. RELATIONSHIP BETWEEN COMMINUTION RATE AND ULTRASONIC POWER FOR BATCH GRINDING OF 10-MESH TALC TO MINUS 200MESH TALC Transducer rating is 1 kw. FIGURE S. RELATIONSHIP BETWEEN COMMINUTION RATE AND ULTRASONIC POWER FOR GRINDING A SIMULATED RECIRCULATING LOAD OF 10-MESH TALC TO MINUS 200-MESH TALC Transducer rating is 1 kw. The solids content of the talc slurry is 33 per cent. Exposure of load was made in 5-minute increments. -- r IOA / MJ MHI 1/ 10 J / // 0 --t----- to o ao loo JWtf Sowtr.Hf* c-> FIGURE 6. RELATIONSHIP BETWEEN EXPOSURE TIME TO REACH EQUILIBRIUM AND ULTRASONIC POWER WHEN GRINDING A SIMULATED RECIRCULATING LOAD OF 10-MESH TALC TO MINUS 200-MESH TALC Transducer rating is 1 kw and the solids content of the circulating slurry is 33 per cent B A T T IU I MIMOBUl INSTITUTE BUSINESS CONFIDENTIAL P rotected D o cu m en t-S u b ject to P ro tectiv e o rd er JNJNLB1 000001 BUSINESS CONFIDENTIAL 7 was treated for 5 minute to obtain an ultrasonically processed talc that could be used for preliminary beneficiation experiments. A screen and sedimentation analysis of the 12 pounds of ultrasonically ground talc was made. Results were obtained as shown in Table 1. TABLE 1. SIZE DISTRIBUTION OF COMMINUTED TALC WHEN TREATED WITH 1. 28 KW PER 50-GRAM LOAD Size Fractions Plus 200 m esh' Minus 200 mesh plus 10 micron Minus 10 micron Weight P e r Cent 42.8 45.8 11.4 IS O Table 1 shows that by the particular experimental arrangement used on the 12 pounds of talc, about 46 per cent of the talc was produced in die desired size range of minus 200 m esh plus 10 m icrons. The plus 200-mesh fraction accounts for over 42 per cent of the feed. This portion should be removed by screening to be returned and blended with new feed. By tide procedure a closed grinding circuit can be simulated. Information on how the ultrasonically ground talc responds to flotation was obtained from a few prelim inary flotation experiments on the 12-pound batch. The ultrasonically ground product was wet screened to remove the 200-meah oversize. Based on the fig ures obtained on the screen and sedimentation work, die size distribution of the flotation feed was calculated after the plus 200-mesh fraction was removed. Table 2 shows the calculated values. TABLE 2. DISTRIBUTION OF PARTICLE SIZES IN FLOTATION FEED OBTAINED FROM COMMINUTED TALC WHEN TREATED WITH 1. 28 KW PER 50-GRAM LOAD Size Fraction Minus 200 mesh plus 10 micron Minus 10 micron Weight P e r Cent 80. 1 19.9 ATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL lo t e c t e d D o cu m en t-S u b ject to P rotective O rder JNJNL61 000 BUSINESS CONFIDENTIAL The minus 200-m esh fraction was then cydoned and the resulting minus 200-mesh plus 10-micron fraction was floated. Five flotation experiments were made. The first flotation experiments showed that acicular particles of talc floated with the platelets. Therefore, modifications in the beneficiation procedure were made in an attempt to eliminate these acicular particles. These modifications consisted of using greater dilution during cycloning and in using smaller quantities of reagents during flotation. Table 3 shows the best flotation separation obtained with talc ground ultrasonically. TABLE 3. FLOTATION RESULTS OBTAINED FROM ULTRASONICALLY COMMINUTED TALC Product Cyclone overflow Float 1 Float 2 Flotation underflow Total Weight Per Cent 33.0 39.2 11.6 16.2 100.6 Microscopie Count, per cent Nonplaty Platy (Mostly Acicular) (a) (a) 97-98 2-3 96 4 (a) (a) It is emphasized that neither the gripd nor the flotation conditions were considered^ as being optimum in these five exploratory experiments. Two other ultrasonically ground samples were submitted to B attelle's Minerals Beneficiation Division for flotation experiments. These two sam ples, Series I and Q, were made in a simulated recirculating ultrasonic grinding circuit using 90 and 46 per cent of the rested power of the ultrasonic transducer, respectively. A representative fraction of each of the two samples was treated by sedimentation to determine the amount of minus 10-micron m aterial present. Table 4 shows the distribution of sines in these fractions. Table 4 shows that the Series II samples contained 32.4 per cent of the m aterial finer than 10 m icrons, compared with 4?. 9 per cent finer than 10 microns in the Se ries I samples. The lower energy level produced fewer minus 10-micron particles. The sedimentation products were examined under die petrographic microscope to determine the m ineral character. Table S sum m arises these observations. (ATTILLI MIMOIIAL INSTITUTE BUSINESS CONFIDENTIAL P rotected D o cu m en t-su b ject to P rotective o r d e r JNJNL81JKMM01 BUSINESS CONFIDENTIAL 9 TABLE 4. PRTICLErSIZE DISTRIBUTION OF SERIES I AND SERIES II SAMPLES Product Series I; minus 200 mesh plus 10 micron Series I; minus 10 micron Total Series II: minus 200 mesh plus 10 micron Series II; minus 10 micron Total Weight P er Cent 56.1 43.9 100.0 67.6 .32.4 100.0 TABLE 5. MINERAL CHARACTER OF SERIES I AND SERIES II SAMPLES Product Series I; minus 200 mesh plus 10 micron Series II; minus 200 mesh plus 10 micron Series 1; minus 10 micron Series II; minus 10 micron Sedimentation Products, per cent Platy Talc Nonplaty Talc Carbonate Tremolite ------- U" . 98 Al 41 Trace 98 <1 +1 Trace None 72 fines and <1 A4 shards None 70 fines and <1 AS shards 25 nonplaty BATTELLC MEMOWIL institute BUSINESS CONFIDENTIAL tected D ocum ent-Subject to Protective Order JN JN LS1_0000013S2 BUSINESS CONFIDENTIAL 10 Microscopic examination showed that both minus 200-mesh plus 10-micron sam ples (Series I and II) were excellent products. Each contained a large proportion of well-developed platelets, i. e. , thin, flat, circular, or rounded. Figure 7 shows a photomicrograph of Series I sedimentation products. 75X N61292 JRlane-iFolarized Light. FIGURE 7. PHOTOMICROGRAPH OF MINUS 200-MESH PLUS 10MICRON FRACTION OF ULTRASONICALLY GROUND TALC Recirculating load exposed to 46 per cent of rated power of ultrasonic transducer. Attention is directed to the data of Table 5, which show that talc of very high platy content was obtained simply by sedimentation of the ultrasonicaliy ground talc. The carbonate content of these products, however, is still greater than 1 per cent. A flo tation step would be required to eliminate it. These limited experiments should not be taken as conclusive, but there is an indication that at this power level the nonplaty talc is broken down to the minus 10-micron range preferentially by ultrasonic grinding. If further experimental work verifies this trend, it might be possible to produce a highgrade finished talc product from a low-carborate feed simply by grinding and classifica tion for removal of fines, without the necessity of introducing a beneficiation step such as froth flotation. This same trend has been shown in ball-m ill grinding, but to a lesser extent. For instance, the classification for removal of fines from the Italian No. 2 talc, which has been carried out in the talc pilot plant, has increased the platy content from 90 to 95 per cent. This is the same talc on which the ultrasonic grinding BATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL Protected Docum ent.-Subject to Protective O rder JNJNL61JTO0001 BUSINESS CONFIDENTIAL 11 was done. There ie no instance however, where talc of 98 per cent platy quality has been produced without the use of flotation, other than the data of Table 5. No cyclone or flotation experiments were made on the Series I or II samples, because the development .work was curtailed as requested by the Sponsor. DISCUSSION Assuming that the conditions used to obtain the above data on the ultrasonic com minution of a circulating load of talc are optimum and that electrical power costs are 1 cent per kwhr, the cost of comminuting I pound of 10-m esh talc to minus 200-m esh talc would be from 3 to 4 cents. Therefore, the power cost to process a pound of talc would be alm ost constant if an electrical generator, such as a rotary generator having low standby losses, could be used. It is estimated that the over-all efficiency of power transformation from electrical to 20-kc vibratory power of the experimental assembly was 15 per cent. In general, the efficiency of electrical power oscillators of the type used is about 50 per cent, and for the type of ultrasonic transducer used 30 per cent. It is conceivable that systems for comminuting talc can be designed with higher over-all efficiencies. This would reduce processing costs. For example, if sonic frequencies are used, in particular 15 kc, then an over-all efficiency in the neighborhood of 30 per cent might be obtained, halving processing costs. A more promising approach would be to use fluid dynamic transducers, which in general have reduced the cost of ultrasonic processes, when applicable, by a factor of 10. A simple experiment had been per formed using a blender (230-watt O sterizer, John Oster Mfg. Co., Milwaukee, Wie.) to determine this possibility. Rough estim ates indicated that a batch of 10-mesh talc could be ground to 200-m esh talc by this method at a power expenditure of 1 kwhr per pound. It can be.assumed that for a circulating load the power expended per pound of processed talc would be much less. The quality of ultrasonically processed talc appears to be a function of the vibra tory energy level to which it is exposed. Observations made of talc-w ater suspensions after various ultrasonic comminution conditions indicated that batch samples exposed to power levels above 440 watts for any time period produced a colloidal suspension of some of the particles. In general, as the time of exposure or power level increased, the amount of particles colloidally suspended increased. It was also observed that par ticles other than talc found in the suspension were not notably fractured at any of the energy levels used. Although work was interrupted before a relationship between initial talc particle size and its ultrasonic comminution rate could be determined, the litera ture indicates that the sm aller the initial particle size the sm aller will be the size of the suspended p articles after ultrasonic treatm ent for a given time period. The litera ture appears to substantiate the possibility of controlled comminution by the ultrasonic process. In the ultrasonic dispersion of Progesterone it was found that the extent of dispersion was directly related to the ultrasonic intensity applied, and that the extent of dispersion was a function of time of .application and initial particle size. In a closedflow circuit ultrasonic comminution process the minimum particle size can be controlled through the rate of flow of talc slu rry and- the rate of comminution by the ultrasonic in tensity or power. ATTELLE MEMORIAL INSTITUTE BUSINESS CONFIDENTIAL D o cu m en t-S u b ject to P ro tectiv e O rder JNJNLB1J300D01384 BUSINESS CONFIDENTIAL 12 CONCLUSIONS ANO RECOMMENDATIONS Ultrasonic comminution appears to be a promising method of.producing talc pow der of a high and controllable quality. The power required to comminute 1 pound of plus 200-mesh talc minus 10-mesh talc to minus 200-mesh talc is estimated at 3. 5 kw. using magnetostrictive transducers. The applicability of fluid dynamic transducers would be expected to reduce processing costs by a factor of 10 or m ore. The minus 200-mesh plus 10-micron talc produced by an ultrasonic comminution is unique in that almost 80 per cent of the platelets are rounded. Other grinding pro cedures such as roller or pebble milling yield only a few per cent rounded platelets. Ultrasonic comminution, -at the energy levels and the laboratory techniques tried, produced a minimum of 33 per cent of the weight finer than 10 m icrons when comminu tion was carried to the point where a ll the m aterial passed a 200-mesh sieve. P a rt of the objective of obtaining a sm all amount of minus 10-m icron particles was not obtained. It is believed that standard grinding methods can be controlled to produce less than 20 per cent of the weight finer than 10 m icrons, but the particles larger than 10 microns do not contain more than a few per cent of rounded platelets. A 98 per cent platy talc representing 67 per cent of the original weight was ob tained by ultrasonic comminution followed by sedimentation for removal of minus 10m icron particles. This product contained 0.69 per cent CO2 (1. 44 per cent dolomite) as the principal contaminant. If elimination of dolomite is important, acid leaching or flotation would be effective. It is recommended that Johnson and Johnson consider continuing this work to com plete studies on the effect of initial particle sise of talc and frequency of vibration on the comminution rate of talc. These studies would establish the upper practical lim it of particle sizes that can be ground ultrasonically and indicate the practicability of using high-efficiency lower frequency transducer in producing high-quality talc. Work also should be continued to complete the analysis of talc ground under various grinding con ditions to definitely establish its quality as compared with talc powder produced by conventional grinding processes. JNA-.WEC: LEW/mar ATTILLI MEMORIAL- INSTITUTE BUSINESS. CONFIDENTIAL P rotected D o cu m en t-S u b ject to P rotective O rder JNJNL61 000601 ( I II i V*' II I t I I , i i ! : i ri r > y I it i Ptotocted-Documtrt^-3ubicrtoProtrt}w-Ordr - - ------------ - ..........................-- ---------- ----------------------------------- - JNJNls8t_p00Q013l6