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FILE NAME: Concrete (CONC) DATE: 1938 Aug DOC#: CONC002 DOCUMENT DESCRIPTION: Journal Article - Inhalation of Dust and Control of Dust Hazards tny reporta equivalent preferred .97 a share increased shipments Away burgh. 00 nd Cement c Lockhart is home in ;sts, he destional and tee of both l Carnegie \ the board trustee of uberculosis ustee of the Pittsburgh mmittee of ber, he vrai c r *xth rfa ly itv a. -iro. Section <j "1 c:e .491434 Charter Member Associated Business Papers C o n c r e t e , with which has been com bined Cement Age, New York, and Concrete Engineering, Cleveland, is devoted to the Proper Use of Concrete and the Manufacture of Cement. CEMENT MIL 1 * i --------------------------------------------------------------------- / Volume 46 August. 1938 Number 8 Published Monthly bv C o n cr ete P u b l ish in g C o rporation 400 West Madison Street Chicago, Illinois Telephone CEXtral 8822 Louis Brookman. Jr,. Business Manager L. Moeller. Circulation Manager Harold O. Hayes, Promotion .Manager R epre sentatives Sew York City E. Macdonald Bacon 17 Wert 45th--Room 909 Longacre S-SZ1} Detroit Parker & Tarbell 419 Curtis Bidg.. 2842 W. Grand BWd. Madison 1340 San Francisco: Don Harwiy Room 1009,133 Montgomery St. Exbrook 6029 Los Angeles: Don Harway & Co. 318 West Ninth Street Tucker 9706 The Cement Mill Edition o f Concrete The Cement Mill Edition of C oncrete is edited exclusively for those interested in the manufacture of Portland cement and related product*. It* pages are devoted to discussion* of plant design, management, operation, production effi ciency, chemical research and control, quarry operation, progress and news of the industry. The Cement Mill Edition also contains all the material published in the corresponding Regular Edition and so provides news of the uses and merchandising of the materials whose manufacture is discussed io the Mill Edition. The Regular Section furnishes ndl operating officials and mill executives valuable points of con tact with the users of the materials they produce. The subscription price is $4.00 a year in the United States and its possessions, sad Mexico. One dollar additional for postage in all other countries. Current copies, 50 cents each. . x ' Charter Member N o r m a n M. S t in e m a n , Editor } . C . W it t , Consulting Editor A. C. B a m b e r g e r , Assistant Editor CONTENTS Handling and Processing Raw Malarial* at Peerless' Detroit Plant 214 How a Texas Pioneer Produced C e m e n t____________________ 215 Inhalation of Dust and Control of Dust Hasarde-- By W. C. Jam 218 Cebu Plant In Philippin to Double Its C apacity_____________ 218 Relation of Cement Composition to Quality of Concret _____ 218 Prvntiag Silicosis--Som Results of Recent R esearch _______ 219 P. C- A- Holds Spring Meeting in Atlantic C ity ______________ 220 June Sees Fw Accidents-- Bat F oot Are F atal_______________ 221 Biq Expansion of Producing Capacity in India In 1908..... .....-- 221 . Huron Establishes Distributing Plant at Green Bay . _____ 222 Andreasen's Method for Determination o( Fineness________ _ 222 Heats of Hydration and Transition of Calcinai S a l a t s ________ 222 E d ito ria l_____________________ 223 The lune Campaign Direct Finng of Rotary Kilns Dust and Machinery How Welding Is Applied to Plant Maintenance and Repairs 224 Award Jury Selecting Winning P ap e rs------------------------ 228 MIR E q u ip m e n t_________________ 227 Men and M i l l s ______________________________________ 228 AD *} Copyright. 1933 Concrete Publishing Corp CONCRETE is .r.dexed m INDUSTRIAL ARTS INDEX which may be consulted m any Tecnn-.cn of Pubuc Librsry. Audit Bureau of Circulations C O N C R E T E -- C em ent Mill Section -- A ugust, 1938 Page 213 LL Inhalation of Dust and Control of Dust Hazards B y W. C. JAMES Safety engineer Portland Cement Association Chicago. Illinois T HE first |*art o f this article, published in the July issue, discusses the concentration of industrial dusts and points out the harm less character of cement d u st; but the need fo r m ore knowledge about dust is em phasized. The present concluding part takes up matters such as the effect o f duration of exposure, and the adoption o f preventive m easures.-- Editor. T HE United States Public Health Service has developed a formula for calculating the actual exposure in terms of particle hours. They recommend in Bulletin 217, **The Determination and Control of Industrial Dust.'1that the par ticle concentration in any area he multi plied bv the number of hours an empioiee norks in that area: that this prod uct be calculated for each hour of the working day and that the total of these products be divided bv the number of working hours to give the eqimalent of continuous exposure during the day. Equivalent Exposure For example, a man may spend two hours a day in a concentration of 200 million particles per cubic foot; three hours in a concentration of 10 million particles; one and three-quarter hours in a concentration of 40 million particles and 15 minutes in concentration of 1200 million particles. The man's exposure would be calculated: The application of this formula in a practical problem is apparent. If you find, from a study of concentration and silica content, that in two or three areas in your plant atmospheric dust exceeds safe limits, you will make an analysis of the exposure by the P.H.S. method and attack that point where emplovee ex posure is the greatest. How Long in Developing How long does it take silicosis to de velop? The answer to such a question must be equivocal. Much depends on the physical condition of the worker. A man whose respiratory passages have been damaged so that dust is not readily ex cluded by the usual protective mechan ism, may contract silicosis more readily than a man with normal nasal and bron chial passages. Also a man whose lungs have been damaged b\ pneumonia or tuberculosis may develop silicosis more quickly. We are probably all familiar with the reverse of this; i.e., that a man with silicosis has much less resistance against tuberculosis than a man with mi affected lungs. This fact, incidentals, suggests one of the outstanding diffet ences between the action of silica and other dusts. Medical authorities state that not only does the silicotic lesion in the lung resemble the lesion in tuber culosis, the silica actually stimulates the activity of tuberculosis and, at the same time, conceals its symptoms until it ifar advanced. The seriousness of such a condition may readily be imagined. \ tubercular with significant quantities of silica in his lungs may be rapidly getting worse, yet diagnostic symptoms are often lacking. Frequently only a careful X-rai examination can reveal the presence of tuberculosis in a silicotic. Mr. P. N. Bushnell, speaking before the Metals Sec tions of this Congress last yeat, emphasited the fact that the real danger from silicosis is not silicosis at all, but tu berculosis. First or even second degree silicosis, uncomplicated by tuberculosis, usually causes relatively slight disahilitv. seldom pronounced enough to interfere with working capacity. No worker should be deprived of an opportunity to earn a living at his regular job because his Xray shows some signs of nodulation. The job should be cleaned up by approve! engineering methods, of course, but d i charge of workers who are perfectlv capable, simply because of a non- sjmptomatic condition which hysterical opinion has magnified out of all propor tion, is certainly not the solution of the problem. Inert dusts do not produce the typical nodular lesion, nor do they cause any increased susceptibility to tubercu losis. In the cement industry, for e u n - Hours per day a 2 3 2-Y, Vi Dust Concentration b 200 10 40 1040 Particle-hoars (millions) a and b 400 30 no 260 8 800 Total Hours 800 particle hours in millions per cubic foot rr 8 hours 00 million partici es per cu. ft. dailv exposure Paoer read before ibe Q uarti Section of the All-Ohio 5afei> C o n gres Mav 11. 1935 P age 216 pie. only 4 per cent of the X-rays of 1700 employees revealed old tuberculosis lesions and 96 per cent of these lesions ere healed or quiescent. Studies of ab senteeism over a two-year period, cover ing the majority of mills in the industry, confirms the X-ray evidence. The mor tality rate from tuberculosis of 0.07 per 1000 employees in 1937 is only 8 per cent of the tuberculosis mortality rate of 0.87 per 1,000 employed males estab lished by the National Tuberculosis Association in a comprehensive survey in 1930. Factors That Control The various factors which may influ ence the length of time required to de velop silicosis, if we may recapitulate, are ( l ) intensity of dust concentration, i2 l proportion of free silica in the dust, 1 31 proportion of working time em ployees spend in the dusty atmosphere, ( 4 I condition o f employee's upper respi ratory tract, and (5) condition of em ployee's lungs. In any case, it is extremely doubtful that first-stage silicosis will develop in less than seven years, except in the pres ence of active tuberculosis. Dr. Gardner says that for silicosis to develop in five years, the exposure must be intense. The National Silicosis Conference report, to which we have previously referred, savs with admirable skepticism, `"There are reports of a few cases of the disease de veloping in as short a period as one and one-half years. In these instances, the individuals were exposed to excessive concentrations of extremely fine silica in almost a pure state." The report then states that exposure to low concentrations of silica may sometimes continue for thirty years before the condition devel ops to the stage where it can be called silicosis. In such cases, possibly another 15 or 20 years would be needed before any disability would be noticed. A great majority of the cases have had at least seven years' exposure. Thus it will be seen that silicosis is a very slowly de veloping disease, which, in the absence of infection, is not especially dangerous. In the presence of infection, however,-the picture may be different. Control of Dust Hazards No attempt has been made to separate the two sections of this paper, as indi cated by the title, since the discussion of the problem is too intimately bound up with the methods of solving it. There are, however, some details of prevention which should be mentioned. It might be worth while to think about the methods of determining dust concen trations. The quick sampling, easy count ing devices on the market now probably fill a definite need, but their use is not altogether an unmixed blessing. The standards mentioned in this paper are all based on the United States Public Health Service's impinger technique with light field count. It is a complex technique requiring skill and experience to operate successfully, but it is the standard count ing method in the United States and re sults of short-cut methods have not been shown to be correlative with it. After dust control has been instituted and the im pinger technique has shown that concen trations are within safe limits, a simpler technique might be permitted for periodic checks on the efficiency of the control system. But don't be surprised if your counts with the simplified technique soar way above the impinger counts. The dark field illumination will uncover a large number of particles, apparently too small to have any effect, that are screened out by light field methods. The result is similar to the effect of a strong beam of light in a dark room. This difficulty can be overcome to some extent by taking im pinger samples and samples by the other technique simultaneously, as soon as dust control equipment Is installed, thus get ting as much correlation as possible be tween two techniques at the beginning. Remove Dust at Source A general paper of this type is not a suitable place to discuss the relative merits of different types of dust control systems. There are, though, a few prin ciples which can be properly mentioned. Wherever possible, dust should be re moved at its source, before it reaches the workroom atmosphere. Methods of ac complishing this vary with the process and should be decided upon by competent engineers after a careful study. In mill ing processes, closed, dust-tight systems with adequate separators and collectors may be adequate. Water sprays are some times effective where they can be used. In the quarry wet drilling is often all that is necessary to bring concentrations down to safe limits. Sometimes more elaborate dust traps are needed, either independ ently or conjunctly with wet drills. Some processes are not amenable to control at the source. In such cases em ployees should be required to use respira tors or masks of approved type. All of these methods have their place. The right one for each location must be determined by a thorough engineering survey. C O N C R E T E -- Cem ent Mill Section -- A ugust, 1938 The importance of good housekeeping can not be too strongly emphasized. Much o f the dust nuisance can be elimi nated bv systematic, routine and thor ough clean-up programs. The advan tages are obvious. The plant is much better looking and, in addition, the at mospheric dust is reduced. Medical control is equallv important. The onlv sure wav to know that a hazard does not exist is the careful observation of the workers over a period of years. Pre-employment examinations are. of course, also important for proper place ment of applicants. Salient Features ol Problem In this paper we have presented some of the salient features of the silicosis problem. We have, first of all, empha sized that only two pneumoconioses are actual diseases, silicosis and asbestosis. We have pointed out that there are three causative factors of silicosis and all three must be present simultaneously to produce the disease. 1. Lncombined silica in small par ticles, of which the most danger ous is probably quartz. 2. Sufficiently intense concentrations of the dust to be hazardous. This concentration is set at five million particles flight field countl of quartz less than ten microns in greatest diameter, if the quartz constitutes a high percentage of the material. Studies in the cement in dustry have demonstrated that, in cases, appreciably higher concen trations of quartz can be tolerated when inert dusts, as clay or lime stone, are intermixed with silica. 3. Exposure by the employees over a sufficiently long period to high concentrations of silica of the nec essary fineness. The influence of silica on tuberculosis is strong, whereas inert dusts have no effect on this disease. Serious disability from silicosis, especially in the first two stages, usually results from infection, rather than from the uncomplicated di sease. If the working environment is ade quately clean, a silicotic need not be de nied work as long as he is free from in fection and is capable of doing his job. Medical Control Is Important Methods of control of the disease in clude pre-emplovment and periodic med ical examinations, removal of dust at point of origin, emphasis on good house keeping and the use of respiratory pro- (Continued on page 222) Page 217 INHALATION OF DUST (Continued from page '217) Huron Establishes Distributing Plant at Green Bay tective equipment where removal of dust from the atmosphere is not possible. It should be emphasized that control. especiallv engineering control, of the silicosis hazard is the phase of the prob lem that is of greater importance to those HURON Portland Cement Company ha? put into operation that conipane's twelfth packing and distributing plant at the Leicht dock at Green Bay. Wisconsin. Prev iouslv -built distributing plants owned bv Huron are located at Detroit. Oswego. Buffalo. Cleveland. To ledo. W\andotte. Saginaw, Alpena. Mus kegon, Milwaukee, and Duluth. Cement for the Green Bay packing and distributing plant is brought from the Huron's Alpena cement plant in the cornpain s own bulk-cement lake steamers, the largest of which has a cargo capacity of 40.000 bbl. At Green Bas the bulk cement is trans ferred to the cement company's boat Samuel Mitchell, which is lashed to the dock and will serve temporarily as a ' warehouse until the necessary con struction and installations on shore can be completed. The Samuel Mitchell brought the first cargo of bulk cement totalling 15.000 bbl. Dredging opera tions are enlarging the slip in which this boat is docked, and when this phase of the work is completed the floating ''ware house"' can be moved further in. thereby enabling other boats to dock directly back of it, to unload their cargo. A cement packing machine having a capacity of 1,000 sacks an hour has been installed on the dock alongside the Samuel Mitchell. From the hold of the ship, cement is pumped into a steel bin over the packing machine, and is fed to the packer for sacking as required, to fill orders from the trade, the cement being forwarded either by rail or by motor truck. Cement can also be shipped from the Green Bay distributing plant in bulkcement railway hopper cars, although this type of railway rolling stock is not, as yet. generally available. Only a few railways have supplied themselves with such rolling stock, and they have onlv a small number of these special cars. With twelve packing and distributing plants operating at ports on the Great Lakes, the cement company's bulk-cement carriers will make regular stops and un load whatever cement is required. of us who are interested in the practical methods of eradicating the disease. Dr. A. A. Riddell of the Ontario De partment of Health, whose work in the gold fields of Ontario has won for him an international reputation, put the prob lem squarely up to the engineers when lie said: ` `Silicosis is an occupational disease declining in importance. Its pre vention is not a medical problem. As it occurs exclusively through the inhala tion of dust containing silica, its preven tion depends on the eliminaton of dusts industrially produced. This is a problem for the industrial engineer. Engineers have met the problem so energetically and with such intelligence that the occur rence of silicosis in many operations now considered hazardous will cease entirely during the next fifteen or twenty years." Heats of Hydration and Transition of Calcium Sulfate HEATS of hydration and transition of calcium sulfate are discussed m a detailed report by Edw in S. Newman and Lansing S. Wells, published by the National Bureau of Standards as Re Andreasens Method for Determination of Fineness search Paper RP-1107, and appearing also in the June (19381 issue of the Journal of Research of the -National Bu reau of Standards. The heats evolved in the hydration to IN a report presented to the TwentySecond General Meeting of the Asso ciation of Japanese Portland Cement En gineers, Prof. Toosaku Yoshioka, of the Imperial University at Kyoto, gave con firmation to the correctness of results from the use of Andreasen's pipette method for the determination of fineness of powdered materials. From his experience in the fineness determination of Japanese clayey mate rials for the last three years, he has come to recognize the value of Prof. Andreasen's pipette method as one of the best of present methods for scientific as well as technical determination of fineness of powdered materials. He tried to introduce this method to the field of cement research and factory control, and explained about the prin ciples, apparatus and manipulation, and concluded that this method would be worth attention for cement chemists be cause of the simplicity of the apparatus, easiness of manipulation and correctness. He also mentioned a few points neces sary to get fair results; i.e. complete elimination of bubbles adhering to the particles, by placing the suspension in a vacuum vessel, placing the whole ap paratus into a thermostat to prevent tem perature fluctuations and avoid convec tion disturbances, and recovery of solv ents when ethyleneglycol, alcohol, etc. are used. The Association of Japanese Portland Cement Engineers has its offices in the Teikoku Building, in Osaka, Japan. C a S 0 4.2H,.0 at 25 C. of C a S 0 ,.l/2 H ;0 prepared by treating gypsum with steam in the autoclave, and o f C aS 0 4 pre pared by heating gypsum at 1,000' C., have been determined and found to be 4,100 plus or minus 30 and 3,900 plus or minus 20 cal/m ole, respec tively. The heat evolved in the hydration to C a S 0 42H -0 of soluble anhydrite pre pared by dehydrating gypsum at 75 C. is not less than 6,990 cal/m ole. During the progress o f this work no indicationwere found of more than two anhydrouforms of calcium sulfate; soluble anhy drite. and a modification formed rapidly at high temperatures, the latter being identical with natural anhydrite. The heat evolved in the transition of soluble anhydrite to natural anhydrite is not less than 3,000 cal/m ole. Paqe 222 A u q u at 1938 -- C O N C R E T E -- Cem ent Mtn c *.