Document KJZ6Y3YkDzZ8Dkmd419v1kjDX

FILE NAME: Trade Publications (TR) DATE: 1939 Mar DOC#: TR036 DOCUMENT DESCRIPTION: Trade Journal Article - Appraising the Risks From Industrial Dusts Charter Member CEMENT MILL SECTION of 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. Volume 47 March, 1939 Number 3 Published Monthly by Concrete P u blish in g C orporatio n 400 West Madison Street Chicago, Illinois Telephone CENtral 8822 Louis Bcookman, Jr., Business M anager L. Moeller, Circulation M anager Harold 0 . Hayes, Promotion M anager R e p re sen tativ es New York City E. Macdonald Bacon 17 West 45th--Room 909 Longacre 3-5260 Detroit Parker & Tarbell 419 Curtis Bldg., 2642 W. Grand Blvd. Madison 1540 San Francisco: Don Harway Room 1009,155 Montgomery St. Exbrook 6029 Los Angeles: Don Harway & Co. 318 West Ninth Street Tucker 9706 The Cement M ill Edition o f Concrete The Cement Mill Edition of Concrete is edited exclusively for those interested in the manufacture of Portland cement and related products. Its pages are devoted to discussions of plant design, management, operation, production effi ciency, chemical research and control, quarry op eration, 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 in the Mill Edition. The Regular Section furnishes mill operating officials and mill executives valuable points of con tact with the users of the materials they produce. The subscription price is 44.00 a year in the United States and its possessions, and Mexico. One dollar additional for postage in all other countries. Current copies, 50 cents each. Charter Member N o r m a n M. S t in e m a n . Editor J . C. W it t , Consulting Editor A. C . B a m b e r c e r , Assistant Editor CONTENTS U se M any T y p es of C oavey in q Equipm ent in Cement Plants .... 127 Higher Efficiency i u Heat Utilization S e d u c e s Fuel Requirements 129 Grinding M edia Com pared in Efficiency ........ ........ .................. 130 New Facts About Primary Crushing . .... ...................................... 131 A ppraising the S isk s from Industrial Dusts . ---- ... 132 Effect of G la ss Content of Clinker Upon Heat of Hydration......... 132 Editorial Discussion ............................... ...... ..... .......... _ . Conveying Equipment in Cement Plants Preventing Dust Through Enqineennq Control Heat Loss Through the Kiln Shell Identification of Industrial Dusts ...............133 Stanford T. Crapo Closes C areer_______ _____ .... .. _ ............ 134 Vulcanite Converts Old Boiler House to Other U s e s ...................134 Selecting a Cetnent*MUl Motor for Low Running C o st. ........... 135 Production and Shipments in 1938 Almost Equal 1937 ....._...... 135 Protective Devices, Clothing and Equipment for Rock Workers-- By Charles F,, L e w is__ ______________________ ____ _____ 135 Colorado Portland's Fort Collins Plant Badly Damaged by Blast. 138 Mill Equipment ...... .......................................................................... 133 Men and Mills .... ............:___ ___- ....................--........................ 14Q Advertisers' ndex. Page 40 Copyright. 1939. by Concrete Publishing Corp. CONCRETE is indexed In INDUSTRIAL ARTS INDEX, which may be consulted in any Technical or Public Library. Audit Bureau of Circulations C O N C R E T E -- Cement Ml Section -- March. 1939 Page 125 10. The shape distribution of the below the -- 1.05-in. size remains about products from jaw and gyratory crushers constant. was similar. A typical shape distribution of the products shows that the crusher oversize is composed principally of pieces of intermediate shape. At the size of the crusher opening about 80 per cent 11. The shape distribution of the product from the swing-hammer crusher is the same in all sizes. The product con tained between 80 and 90 per cent cubes and about 1 per cent slabs at each size. of the product consists of cubical mate 12. Slabs are formed principally by rial and only 1 or 2 per cent of slabs. radial cracks caused by compression and At succeeding smaller sizes the per are preponderant in the smaller sizes. centage of cubical material decreases and The larger sizes are predominately cubi the percentage of slabs increases. The cal pieces, resulting from impact cracks -- 1.05-in. size is composed of about 60 through the material normal to the crush per cent cubes and about 8 to 10 per cent ing faces. slabs. The shape distribution in the sizes 13. Crushing is caused largely by compression in the jaw crusher, the gyra tory crusher, and the single-roll crush ers. While large pieces in the single-roll crusher are broken by the impact of the slugger teeth, the crushing is finished by compression as soon as the pieces are re duced sufficiently to be nipped between the roll and the concave. Crushing is caused entirely by impact in the swing- hammer crusher. 14. Comparison between the Blake- type and gyratory crushers indicates that the size distribution and the shape dis tribution of their products is similar un der conditions of feed and operation. Appraising the Risks From Industrial Dusts T WO bulletins outlining " how" meas ures for combating industrial disease and for guarding the health of industrial employees are being distributed by Air Hygiene Foundation to its member com panies. One of the bulletins deals with the sub ject of lead poisoning--a problem with which the cement manufacturing industry is not concerned. The other bulletin is a guide for appraising risks from indus trial dusts. This publication, headed Identification of Industrial Dusts, points out that the inorganic materials found in industrial dusts are largely minerals, al though many artificial substances are also encountered. Chemical analyses of mix tures of such materials seldom reveal the percentages of the various minerals pres ent. However, each mineral has charac teristic optical properties that can be de termined microscopically with the aid of polarized light. This method of identifying minerals by their optical properties is known as optical mineralogy. The identification of industrial dust is accomplished best by using petrography as the basis of analytical work and supplementing it whenever necessary with chemical deter minations, the bulletin states. Characistics of a few " minerals commonly found in dust" are listed, and dusts are classified in four general groups for purposes of identification. The bulletins are part of a series pre pared by the Preventive Engineering Committee of Air Hygiene Foundation, of w'hich committee Prof. Philip Drinker, of Harvard, is chairman. Others issued this year include one on the " Use and Care of Respirators." another on " Design of Exhaust Hoods," and one on " Design of Duct Work for Exhaust Systems." Offices of Air Hygiene Foundation are at 4400 Fifth Avenue, Pittsburgh, Penna., with John F. McMahon as executive as sistant. Effect of Glass Content of Clinker Upon Heat of Hydration T HE Portland Cement Association Fellowship established at the Na tional Bureau of Standards, Washington, D. C., has published a new bulletin as Paper No. 36, under the authorship of William Lerch and under the title of Effect of Glass Content Upon the Heal of Hydration of Portland Cement. In the investigation reported, the heat of hydration was determined, by the heat- of-solution method, for a number of port- land cements prepared from clinker which had been subjected to various heat treatments to produce different glass con tents. The results indicate that, when different cements are ground to about the same degree of fineness, the quantity of heat evolved between 7 and 28 days will be dependent on a number of factors. The composition of the cement and the glass content of the clinker are two of the most important of these factors. The glass content not only influences the heat of hydration directly, but also influences it indirectly, through its effect upon the true compound composition. No consistent relation was observed be tween the glass content and the quantity of heat evolved at the age of 3 days. At 7 and 28 days the quantity of heat evolved for any given composition increased con sistently with increasing glass contents. Reasons are advanced to explain why the difference in glass content, together with the changed compound composition re sulting therefrom, may affect the heat of hydration of the cement at various ages. Gypsum and Lime Plants In United States COMPLETE maps of the principal gypsum plants and the lime plants of the United States have been compiled and published by J. H. H, Muirhead, 230 West 108th Street, New York City. Each map includes the name and loca tion of each plant, the names of the com panies being grouped by states. It is a matter of interest to observe that gypsum plants are found in 31 states, and lime plants in 44 states. Allis-Chalmers Branch Office in Newark A LLIS-CH ALM ERS Manufacturing Coin ' d p a n y , of Milwaukee, has established a new branch office and warehouse in the Indus trial Office Building. 1060 Broad Street, New ark, N. J. The new office will he a branch of, and under the jurisdiction of, the New York district office of the company, and will pro vide additional service in the Newark area for motors, pumps, texrope drives, power trans mission units, and other equipment in the company's line. C. A. Pihl has been appointed as Newark branch office manager. Page 132 March, 1939 -- C O N C R E T E -- Cement Ml Section CEMENT <fitmal h'acuAAion Conveying Equipment in Cement Plants An article in this issue emphasizes the great ex tent to which conveying equipment of many different types is used in the process of cement manufacture. In the average plant it may be said that the material of which cement is made is carried along the mill stream in or on some form of mechanical conveyor from the time it leaves the crusher until the final prod uct is shipped from the plant. This is literally true except, of course, for the stops made to undergo further processing. In a few notable instances where the rock is transported from the quarry to the plant by means of cableways, the conveying activities actually start at the quarry. Throughout its plant operations this industry utilizes belt conveyors, screw conveyors, pneumatic pumping systems, bucket elevators, apron conveyors, and vari ous other types, some of which are special type de veloped for special uses. Mechanical conveying is both effective and econom ical, for it acts continuously and keeps the materials constantly on the move between successive stages of processing. committee. In the case of the cement manufacturing industry, these measures are necessary, not for the purpose of preventing silicosis, but for the purpose of preventing damage claims in court. Copies of Bulletin No. 21, Part 2, may be obtained either through the Division of Labor Statistics, United States Department of Labor, or from the Government Printing Office at Washington. Identification o f The preventive engineering comIndustricd Dusts m i t t e e of the Air Hygiene Foun dation has prepared a number of valuable treatises on industrial dusts, which have been published as Bulletin No. 2. Part 7 of this se ries, recently issued in a separate form under the head ing Identification of Industrial Dusts, classifies this problem in a way that permits uniformity both in the methods of tests and in the analysis of results. For the purpose of identification, industrial dusts are classified into four different groups. Only two of the groups are involved in cement manufacture. One of these is the group composed chiefly of soluble ma terials, limestone being mentioned as one of the ma terials. The other is the one composed of insoluble and Preventing Dust The prevention of silicosis may. Through Engi- ` n one sense- be regarded as a neeringControl matter of comparatively small concern to the cement manufac turing industry, for the reason that the rock dust and cement dust particles present in the atmosphere of ce ment plants do not actually produce this disease. On the other hand, while the assertion just made . can be proved from the medical and scientific stand points, this does not necessarily mean that courts and ?juries can be convinced of these facts. In a word, the human element that enters into this phase of the subject is one that can be counteracted only by taking measures to prevent the presence of dust -particles in the atmosphere wherever workers are em. ployed, or to reduce the quantity o f such dusts to a point where their presence is not ordinarily noticeable. It is this angle that gives importance to the final [report of the committee on the prevention of silicosis through engineering control, serving under the auspices .of the United'States Department of Labor, of which * committee the chairman is Warren A. Cook, of the Connecticut State Department of Health. The final re port of this committee has been published by the De partment of Labor as Bulletin No. 21, Part 2. Plant design and renovation, good plant housekeeo+ ing and maintenance, and the installation of dust-col- lecting systems at the sources of the dust, are among i the major preventive measures recommended by this inorganic materials. The conclusion reached by the writer of this paper is that identification of industrial dusts is accomplished best by means of petrography as the basis of the ana lytical work, supplementing it wherever necessary with chemical determinations. Heat Loss Through the Kiln Shell Heat lost by radi at i on through the kiln shell re mains as one of the big problems for cement mill technologists to solve. Much thought has been given to it, and much progress has been made, more especially through the practice of placing a layer of insulation blocks between the fire brick and the shell of the kiln. This has been common practice for more than ten years. It has been found necessary, however, to omit the insulation blocks throughout the burning zone, even though this is the zone of greatest loss of heat through the shell, because the inslation blocks can not stand up under the high temperatures encountered in this section of the kiln. Here, then, is a possibility for at least a partial solution of the problem-- the develop ment of a refractory lining that will remain intact under the maximum temperatures attained in the burn ing process in cement m a n u fa c tu re . The magnitude of this problem may be judged from the amount of the loss of heat-- estimated by various authorities at values ranging from 158,000 to 227,000 B.t.u. per barrel of clinker. C O N C R E T E -- Cement Mill Section -- March. 1939 Pag 133 40 CONCRETE March, 1939 I Advertisers' Index | "TIME TESTED" COLORS Our Cement and Stucco Colors Comply with the Recommendations and Specifications of the Portland Cement Association and the American Concrete Institute. Write for our Color Chart R EICH AR D CO U LSTO N INC. 9 5 M&DI5QN AVE., NEW YORK,N.Y. For Better Concrete Pipe-- Use WELDED Reinforcing Mesh-- The Allan Portable Spot Welding Outfit can be uaed right on the job speedily, efficiently, dependably--on all rise of wire. 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