Document MJY9E8DKMwy0VRYvkw05vNw69

FILE NAME: CERAMICS (CER) DATE: 1938 Aug DOC#: CER018 DOCUMENT DESCRIPTION: Trade Journal Article - Inhalation of Dust and Control of Dust Hazards ; 2 \~q ' c i . ! C - 1 .-1 c -.B .1 9 1 4 3 4 J O u rler Member I CEMENT MILL SECTION of foremet Id ta Ce* t training ihe "vie*' too mnchy-'i^V rw t*i lflificill> ' ^ wuhirro'.' y U on the v bring hi ^ weight to ! I, the op* , J pOfttiOB i i>d. it bu*_ ce for the * . being re^ hie w eigh ti^jT . - L I * ^ m A 4yi any report! equifllrtl t preferred ' 97 o hire increed hipment Away burgh, one .id Cement c Lockhirt A home *!*, he deationil ltd *1 of both .1 Cimegic 4 the boerd tru*tee of Tuberculosis *u#tee of the Pittfburgh mmittee of ther. he w f t r* **;tlh W|' lr ilv . -iro. ,, ctlon Auociaied Businet* Papers Co 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. Published Monthly by Concrete P ublish ing Corporation 400 West Madison Street Chicago, Illinois Telephone CENtra! 8822 ___________________________________ / Volume 46 A ugust 1938 Number 8 N orman M. S tinem a n, Editor J. C. Witt, Consulting Editor A. C B aMBERCER, Assistant Editor Louis Brookmsn. Jr.. Business Manager L Moeller, Circulation Manager Harold 0. Hayes. Promotion Manager Representatives New York City E. Macdonald Bacon 17 West 45th--Room 909 Longacre 3-3-60 Detroit Parker ft Tarbell 419 Curtis Bldg- 2842 W. Crand Bled. Madison 1540 San Francisco: Don Harway Room 1009. 1S5 Montgomery St. Exbrook 6029 Los Angele: Don H irviy ft Co. 318 West Ninth Street Tucker 9706 The Cement Mill Edition of Concrei The C*meai Mill Edition of Cr ii ediW n c lu iM r for there interested in the m-noisctarc of Portland cement and related predeca. It, page, are devoted ta discnsiioos of plaot detign, manegement, operation, prediction efi- eiencr. cbenical research nnd contrai, canny op eration.progress tad new, of the indnecry. The Cement Ml Edition aire conmina nil the material pohliahod in the corresponding Regular Edition and an pro.idea ntwa of the naca and merchandiatng of the material, whoa* manofactor, ia discussed In ihn MO Edilio. . The Regolo, Section fnreiahe* jnO npereting oficiala and mill caccaim , .aluabla pointa of con tact with the m en of the material, they predace. The (ubteription price i* M 0 year fat the failed State, and it* noiteuiotu, nod Mcaico. One dollar additional fee poauge la all other countries. Carrear copies. SO cent* each. . Charter Member CONTENTS HaadlUy and Pracaatlny Raw MattrUl i ? N rU u ` Datoli PUal 214 How T u u R o tw f Prodaaad C a a i__________ __21$ labalafloa I tKul ad Castrai ai ZXial Haaarda--By W. C I ta ) 211 Cab PUal la Pklflppiaaa ta Dambla Ita G apadry_____________211 RaUgaa al Camaat Campadttan la QuQty al Cam erata_____ 211 Pravaada SlttcaaU--Sama Xaaalto d Bacasi R aaatick_____ 211 P. C A. Hald Spila M attia la Allasdc O ty ______________220 luaa Saaa Tarn Accidaala--Bai Farnr Ara Fami______________ 221 81 rr p aaalaa al Pradada Capadty la ladU la 1931________ 221 Mura EsUbtiakae DUMbaR PUal al Craaa Bay______ ___ 221 Aadraaaaa*! Matbad lar DataraaUatee d FU assM ___________ 222 Haat I H ydnttaa aad T r ia d lm alC ald a* S a Jato __________222 E A tsiU ]________________________________________________ 223 Tfca Iurta Campataci Diract Firtng d Rotary U n a Dui: ad Madunary H ov Waldla la Appfiad la PUal K aU launca ad l a p i l l i 224 Awaid Jary Salacca W laaU P ip a r ________- - 331 M fl E a lp m a a t_________________________________________ U T Maa aad MUU __ jj| . . y/ Copyright. 1923. Concrete Publishing Core- CONCRETE la tndaaed in INDUSTRIAL ARTS INDEX, which ca y b . consulted In any Toctuucai or Public Library. Audit Bureau of Grculntion* C O N C R E T E -- Coment Mill Section -- August, 1931 Pnn 213 EMENT MILL Inhalation of Dust and Control of Dust H azards By W. C. JAMES Salety Enginle Portland Cameni AscocUUon Chlcge. dinota THE first part o f thia article, publithed in the July iitue, diKuiMi the concentration of industrial duat* and point! out the harmleu character of cement duit; but the need for more knowledge about dust it emphasized. The present concluding part takes up matters such as the effect of duration of exposure, and the adoption of preventive measures.-- Editor. THE 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," that the par ticle concentration in any area be multi plied by the number of hours an em ployee works 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 by the number of working hours to give the equivalent of continuous exposure during the day. Equivalent Expoauro 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 employee ex posure is the greatest. How Long in Davoloping 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 by pneumonia or tuberculosis may detelop 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 m, affected lungs. This fact, incidentally, suggests one of the outstanding differ ences between the action of silica and other dusts. Medical authorities slate 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 is far 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 ,\-ra\ examination can reveal the presence of tuberculosis in a silicotic. Mr. P. N. Bushnell, speaking before the Metals Sec tions of this Congress last year, empliasired the fact that the real danger frmtsilicosis is not silicosis at all. but tu berculosis. First or even second degree silicosis, uncomplicated hv tuberculosis, usually causes relatively slight disability, 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 .\ray shows some signs of nodulation. The job should be cleaned up by appro* ef engineering methods, of course, but di charge of workers who are perfect! capable, simply because of a non symptomatic 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 industrv, for e\.tt*i- Hour* per day a 2 3 i? Dual Concentration h 200 10 40 1040 Pirtide-bowi (millions) aeadb 400 30 110 20 8 800 Total Hears 00 particle Ware in millions per cubic foot s boars HU million particles per eu. ft. daily expotare. Ta* drsfttae U * pesUc sown f , 0 " wsd before the Quarry Section of the All-Oh Safely Conyresi. Mar 11.1935. Paga 216 August ISM -- C O N C H E T E -- Comont Mill Section pie. onk 4 per cent of the \-.av s of 1<00 employees revealed old tuberculosis lesions and 96 per cent of these lesions were 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 employee* 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. factor* That Control The various factors which may influ ence the length of time required to de velop silicosis, if we may recapitulate, are (11 intensity of dust concentration, i 2 ) proportion of free silica in the dust, 1 3 1 proportion of working time em ploi ees spend in the dusty atmosphere, I 4 I condition of 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 savs that for silicosis to develop in five vears. the exposure must be intense. The National Silicosis Conference report, to which we have previously referred, says 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 (he 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 bad at least seven years' exposure. Thus it will be seen that silicosis is a very slowly de veloping disease, which, in tbe absence of infection, is not especially dangerous. In the presence of infection, however, the picture my be different. Control of Dust Hasarda No attempt has been made to separate the two sections of this paper, as indi cated bv 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 wav above the impinger counts The dark field illumination will uncover a large number of particle*, 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 tv,o techniques at the beginning. R em ora 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 svstems. 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 accomp!:shing this vary with the process and should be decided upon by competent engineers after a careful study. In mill ing processes, closed, dust-light 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 independentlv or conjunctiy with wet drills. Seme 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 ont for each location must be determined by a thorough engineering survey. C O N C R E T E -- Cameni Mill Section -- AuquaU 1938 The importance of good housekeeping can not be too strongly emphasised. Much of the dust nuisance can be elimi nated by 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 equally important. The only sure way to know that a baiard 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 Feature* of Problem In this paper we have presented some of the salient features of the silicosis problem. ^Ie have, first of all, empha sised that only two pneumoconioses are actual disease;, silicosis and asbestos*;. We have pointed out that there are three causative factors of silicosis and all three must be present simultaneously to produce the disease 1. Uncombined silica in small par ticles. of which the most danger ous is probably quarts. 2. Sufficiently intense concentrations of the dust to be harardous. This concentration is set at five million particles (light field counti of quart! Its than ten microns in greatest diameter, if the quarti constitutes a high percentage of the material. Studies in the cement industrv have demonstrated that, in cases, appreciably higher concen trations of quarti can be tolerated when inert dusts, as clay or lime stone, arc intermixed w-ith silica. 3. Exposure by the employee* over a sufficiently long period to high concentrations of silica of the nec- essarv finenei. 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. I f 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 la Important Methods of control of the disease in clude pre-employment and periodic med ical examinations, removal of dust at point of origin, emphasis on good house keeping and the use of respiratory pro- (Conlinutd on paf t 222) Pa<je 217 INHALATION O F DUST /Continued jrom page JITJ Huron Establishes Distributing Plant at Green Bay tective equipment where removal of dust from the atmosphere is not possible. It should be emphasiied that control, especially engineering control, of the silicosis haiard is the phase of the prob lem that is of greater importance to those HURON Portland Cement Company hat put into operation that com pany'* twelfth parkin; and distributing plant at the Leicht dock at Creen Bar. Wisconsin. Previously-built distributing plants owned by Huron are located at Detroit. Oswego. Buffalo. Cleveland. To ledo. Wyandotte. Saginaw. Alpena. Mus kegon. Slilwaukee. and Duluth. Cement for the Creen Bay packing and distributing plant is brought from the Huron's Alpena cement plant in the corn- pan "s own bulk-cement lake steamers, the largest of which has a cargo rapacits of 40.000 bbl. ' At Creen Bay 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 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 tacking 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 Creen 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 only a of us who are interested in the practical methods of eradicating the disease. Dr. A. A. Riddell of the Ontario De , jrtment 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 he 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 dust` industrially produced. This is a problem for the industrial engineer. Engineers have met the problem to energelicallv and with such intelligence that the occur rence of silicosis in many operations now considered hazardous will cease entire! during the next fifteen or twenty years." struction and installations on shore can small number of these special cars. 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 Hith twelve packing and distributing plants operating at ports on the Creat Lakes, the cement company's bulk-cement carriers will make regular stops and un Heats of Hydration and Transition of Calcium Sulfate boat is docked, and when this phase of load whatever cement is required. HEATS of hydration and transition of calcium sulfate are discussed in a detailed report by Edwin S. Newman and Lansing S. H ells, published by the National Bureau of Standards as Re- Andreasen's Method for Determination icarch Paper RP-110T, and appearing also in the June 119381 issue of the of Fineness Journal of Research of the National Bu reau of Standards. The heats evolved in the hvdrstion to IN a report presented to the TwentySecond General Meeting of the Asso ciation of Japanese Portland Cement En gineers, Prof. Toosaku Yoahioka, 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 hit experience in the fineness determination of Japanese clayey mate rials for the last three years, he has come to recognise the value of Prof. Andreaten s pipette method as one of the best t f 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 princopies, 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; U . 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. CaSO4.2H.-O at 25* C of CaSO,.1/2H.0 prepared by treating gypsum with steam in the autoclave, and of CaSO* 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/mole, respec tively. The heat evolved in the hydration to CaS042H-0 of soluble anhydrite pre pared by dehydrating gypsum at 75* C is not le u than 6.990 cal/mole. Durine the progreu of this work no indication* were found of more than two anhydrou* forms of calcium sulfate; soluble anhy drite. and a modification formed rapidly a: high temperature*, the latter being identical with natural anhydrite. The heat evolved in the transition of soluble anhydrite to natural anhydrite is not lets than 3,000 cal/mole. Page 222 Auguat. 1938 -- C O N C R E T E -- Cornant Mill Section