Document aB1Dz8Dbw4jGwgaYOz56D64GY

FILE NAME: Concrete (CONC) DATE: 1941 Feb DOC#: CONC013 DOCUMENT DESCRIPTION: Journal Article - Aim Dust-Abatement Efforts at Finest Particle Sizes Established 1904 with w hich has been com bin ed C em ent A ge, New York, and Concrete E ngineering, C leveland CEMENT MILL EDITION P ublished m on th ly by CONCRETE PUBLISHING CORP. 4 0 0 W est M adison Street C hicago, Illinois T elep h on e CENtral 8 3 2 2 Jo r FEBRUARY . 1941 Volume 49 No. 2 CEMENT MILL SECTION UNTHE INTERESTS OF Those engaged in the manufacture of Portland cement and related products. Its pages are devoted to discussion of plant design, management, operation, production, efficiency, chemical research and control, quarry operation, progress and news of the industry. The Cement Mdl Edition also contains all the material published in the Regular Edition. thus providing mill operating offi cials with progressive data on the uses and merchandising of their products and estab lishing for them valuable points of contact with the user of the materials thev produce. Subscription price is S3 00 a year in the United States and its possessions and Mexico. One Dollar additional for postage in all other countries. Current copies, VO cents each. NO RM AN M. STINEMAiN E ditor J. C. WITT C onsulting E ditor Louis B rook m an, Jr., P u blisher L. M oeller, C irculation M anager D . T . Papineau, P rom otion M anager ________% Ik U M ue Slurry-D rying Heat R ecuperator Saves Fuel and Increases O utput -............................................................................ ..118 P e m ia n e n te P la n t to P r o d u c e B y -P r o d u c ts ............. 119 E ffect o f T em perature onH igh-A lum inaC em ent 120 Free T esting Service for W ar M inerals O ffered bv Calaveras ........................................................................... 120 R eporting and K eeping R ecords o f A bsence D ue to S ic k n e s s ......................................................................................... 121 W hat H appens D u rin g B u r n in g o f C lin k er? . - .. 122 A im D u st A batem ent E fforts at F in est P articles Sizes .. 123 P ow erful Electric M otor D rives B ig K iln at Perm anente P la n t .................................................................................. 124 C alifornia Portland C elebrates F iftie th A nniversary at C o lto n P la n t ...... 124 V ibrations from Quarry B lasts C ause N o D am age to B u ild in g s ......................... ..................................................................... 1 2 5 W e ld in g Is K ey to E ffic ie n t P la n t M a in te n a n c e ...................1 2 6 E d ito r ia l D is c u s s io n ................................................................................. 1 2 7 X 81 Ta*k tor 1941 Statin th Export Problem How the Industry V*||| Expand Individuals A ffected in D ifferent W ays by Silica Dust ...128 Production and Shipm ents in 1940 Pass Mark o f 130 M illio n B a rrels .............................. 129 R e g io n a l S a fe ty C o n fe r e n c e s S c h e d u le d f o r 1 9 4 1 ............. 1 2 9 N a tio n 's Q u a r r ie s P r o v id e M ore E m p l o y m e n t ....................... 1 3 0 M isso u r i P o r tla n d 's F iftie th A n n iv e r s a r y .................................... 1 3 0 M ill E q u ip m e n t ......... 131 M en a n d M ills .................................................................................... 1 3 2 R epresentatives New York City E , M acdonald Bacon IT W est d o th -- R oom 9 0 9 Longacre 3-5260 San Francisco: D on Harway 155 M ontgom ery Street Exbrook 6029 A dvertisers' Index, P age 9 8 CHARTER MEMBER Associated Business Papers Audit Bureau of Circulations I n d e e d In IN D U ST R IA L A R TS IN DEX Los A ngeles: D on Harway & Co. 3 1 8 W est N inth Street Tucker 9706 C opyright, 1941, by C oncrete P u b lish in g Corp. C O N C R E T E -- Cement Mill Section -- February. 1941 Page 117 Home#) fgj; Ri i7 g Si, Show ing m echanical details oi recuperator g jru m , where the j l m n is precipitated Iby paddle-! mounted mi the d i a t t ot the ifscrew t o n 'e u i i This sor*;u u i i n e u i i - ha tt t o t a l s at a ?speed exceeding -<*o i.p.m.. w\th the re lit'suit that the s l u m i> atomized and ^spraved through tile hot kiln 'ij-es pa-^- ingsluwlv through the dium Phe^pra\ing action pi nj<*< t? die d u n * again-t the .`hot shell ot the di tim when* the - 1lu r \ dried vei v q u u h 1' au-<* <*t the hiirhU heated condition M the 'h ell. The p a d dles mounted hi (in- -halt .l the m rew conveyor for the pm })<- <p{ pr'jc<.tui`_r the slurrv. now - f u c tin- a<Uhti.tnal p u r pose of knot k:ir_ the di led >(11111 " if the .shell. M oisture Not Ail R em oved On the jver.t:- m-Ltilaliirii. the tem perature of die kdn p a --inti tin outrii |; .t h e drum and i ',n i " ,.in c rmusture it" in the spraved -lntiv a ill liavi- diiipped W- about 250 dee 1' 'u till- mm- these ea-e- gfS p a ssth r o u g h (hr -e< umi -( "I putt hide- at the tar end ut the drum Not all ill" 1-I u 1 1- 1cm. w d i 1 mu the s(urr\ --or the tiltei - akr i> it misfit more propei K he tei nied at tlif- >enii-<lr\ jft stage. Xssumiiuz a <a-e utuM* the u u slurr\ ha- a uioi-tme -ihiku hri (" around >6 to 10 pt*i <-in. the im u-tute "i the sem idiv "a k e " aiound It' to 19 per <rtu Thi- ake now leaves the drum. htn hit: the eel ot a l i n e d product, but a< tuall' I- af i eadv mill caled, contamm a n m n d [0 to 19 per cent of nui 1-tu 1< Wf~f- Inasmu h a- tin- Imat i et u ptu atm ir 'tallation ai o e the il i>i hai i e end " the kiln, the - mi di \ pi tahu t mu-t h tran-moj t. d hr `crii -*nd "t the kill hi- i> a. 1 ,,mji -in < 'v uu*an - Id a -f'\ t" o o n \ f \ 1]r ^ hih* it t\. hou'tn a l K J |j i" 1 1 to ill in I't illr Mit .f tin- slurry, there are several reasons why this 15 not done. E x perience has shown that no slurry-drying or slurry-filtering operations should go too far in the m at ter of driving out the moisture. As a matter of fact, 15 per cent is about the lowest allow able limit, [f dry in g is c a r ried to a point where the moisture con tent is less than the limit just named, the dried product acts like cement rook or other kinds of raw materials. Good Performance In contrast, when the semi-drv prod uct still c o n ta in s i r o m 15 to 19 per cent ot moisture it enters the kiln in a some what puffed condition, due to the action <d the c a r b o n d ioxide in the effluent aases. Under this condition the heat in the kiln penetrates the p r o d u c t readilv . and CO-j gas escapes without difiicultv. and the burning activ ities are aided. A tvpical installation of the heat re cuperator here illustrated is that hooked up with a kiln 230 ft. long and having d iam eters of 10 ft. a n d 11 ft. 3 in., located in a Western cement plant. Before the recuperator was installed the kiln turned out a daily production of around 1,650 hbl. of clinker, operating with slurry con taining U per cent of moisture. The same kiln, after being equipped with this lecupcrator and having the moisture conte nt o f the p ro d u c t reduced to L9 per cent, had an average dailv production of 1.1125 hbl. fuel consumption, prioi to the instal lation. was 1 L. f ga llo n s ot nil per barrel. \fter the installation was put in opera tion the average was <1.6 callous per barrel. Irknottlwlgrrierit: The heat rccuperatoi here described and illustrated is known as the Cultm-Atng recuperator, n ian u fa ctiu ed bv T r a v l o r Engineering & Manulai turinc Co.. Vlleutnwn. Pennsylvama. P erm anent Plant to Produce By-Products T HE new 12.(KH)-l>arrel-per-day plant of the Permauente Corporation near Los Altos. Calif., has set what is probably an all-tim e low in raw-grinding cost, says Oliver Bowles, in a re p o rt to the Lb S. Bureau of Mines. Grinding is done in two stages, the first consisting of ball mills in closed circuit with Dorr classi fiers. giving a minus 18-mesh product. The second stage consists of ball mills in closed circuit with Dorr bowl classi fiers. giving a product of which 96 per cent is minus 200-mesh. The power con sum ption is said lo be 10 to 11 kilowatthours pel barrel of cement. Most cement plants make nothing ex cept cement, or cement and lime, at the most. The Perm anente Corporation is pioneering in the field of bv-products. which eventuallv mav include limestone for beet-sugar factories and concrete ag gregate. lime, stone sand, solid carbon dioxide, and potash. The stone for beetsugar use must be chert-free. The chertv limestone is sim ilar in appearance to the pure stone, hut under a fluorescent light llieehert assumes such a distinctive color ation that it can be removed bv hand on a picking belt, and in this wav the work is greatlv s 'm / l i 'i H . C O N C R E T E -- Cement Mill Section -- February, 1941 Page 119 Fumes from Coatings Aim Dust-Abatement Efforts at Finest Particle Sizes In general, all rods and all coatings gave off a visible fume or smoke in which the qualitative composition was predict able from the analvses of the rods. In addition, we looked for any volatile fluorine compounds, as well as carbon monoxide, chlorine or hydrochloric acid, and especially oxides of nitrogen. THE Report of the Preventive Engi neering Committee of the Air H ygiene Foundation was presented b y Prof. Philip Drinker, of Harvard, Committee Chairman, at the fifth annual meeting of the Foundation, held at Pittsburgh on November 12, 1940. An abstract of the report is given here. The report deals with fumes from w elding oper ations as w ell as with the elimination of fine particles of stone dust.--Editor. DURING the past fiscal vear of the Air Hygiene Foundation, one fel lowship has been maintained at the H arvard School of Public Health. The incumbent is B ernaid D. Tebbeiis. who is a candidate for the Dot tot ate ot Sci ence Degree at Hat \ aid. He has wotked on two problem -, one involvin'.? a -tudy of particle -ire m lelation to ili< u-is. a nd the other coiupi img a -tudv of the gases and visible Inine evolved in art welding with coated md-. Study of Particle Size For the studies on paitiele -i/e and silicosis, dust samples ol iinelv-ground flint. 99.3 per cent SiO? were p r e p a te d in fractions of 3.3. L7. l.O. a nd 0.6 microns. As stated m o u r 1939 tep o it. the o b ject of Mr. Tebbens work with si/.ed pat tides was to stud' the relationship of size to potency i with respect to silicosis I. It was generally admitted that the potencv increased as the size decreased : hut. mi far as we knew, no studies had been made (and certainly none published l which at tempted to answer this question with pathological proof, We aie indebted to Dr. R. Z. Schulz, of the D epartm ent of Pathology. Harvard Medical School, for his co-operation in this work. Engineers are concerned with particle size in the c ausation of silicosis, because we. and not the phvsieians. are responsi ble for dust control and to r m aking esti mates or counts of dust corn d u ra tio n s . From the lesults of Tebhen. and Schulz, it is evident that methods and ap paratus designed to abate dustiness nr to esti mate dust concentrations should be d i rected especiallv against the particles well below la n d not above I l micron in size. W elding with Coated Rods A part of Mr. Tebbens' fellowship work has been devoted to a study of the natuie and quantity of the fumes and gases liberated during arc welding with coated rods. Not all electric welding to day is done with coated rods, hut their use is increasing lapidlv. fn the case of alloy steels and ot non-ferrous metal, coated rods are the rule and not the ex ception. In general, the primary pur pose of the coating is to shield both the arc and the hot metal Im m reaction with constituents of the air. Time would not permit tudving the full list of the coatings used on modern welding rods, or the products they give off in the arc. VVith the h e lp ot welding experts from the General Electric Companv. who supplied all the equipment needed l o r this studv. we selected a n u m ber of representative rods, of which the makers gen eralh furnished the approxi mate analvses. In tlio-e few cases where aualvses weie not available, it was not difficult to deteuuiue the essential ingre dients and to check them against the p r oduc ts ot c om bustion in the arc. F.verv effort has been m ade not to divulge anv trade or manufacturing secrets regard ing the exact nature ol the coatings. .1. Lou Carbon Steel Electrodes: -- Seven different electrodes were studied in three sizes, a '32. 1 i. and 3 /1 6 of an inch. The coatings contained the fol lowing: F errom anganese, the Mu serv ing as a deoxidizer. Various silicates, including asbes tos. with small amounts of free silica. Sodium silicate as binder. Titanium dioxide as an arc stabil izer. Carlmhvdrates to furnish a leducing atmosphete. 8. Steel Allots and Xon-Ferrous A l lo ts :--The coatings of these rods all contain fluorides, usually carbonates, and some silicates. The coating of rods for welding aluminum contained chlo rides. while one allov rod contained hoiates. Welding was done in a gas chamber equipped with a special exhauster and a hood placed near the welding work. Reads were welded across small metal plates, and the gases and fumes from the arc were drawn into the hood by the exhauster. Samples of gas and of the visible fum e were taken fro m the flue pipe and analyzed. From a considerable eries of such analyses, it was possible to construct a table. Som e Rules lor W elding In general, we believe that modern electric welding is a safe job. providing that the worker observes eertain rule. He must avoid ultra-violet light from tile are. Hi kin. especiallv hands, face, and neck, must he protected. We have no fault to find with the conventional -afetv practice with regard to thee item. He should not weld in confined paces, like tank, miles well ventilated, or un less he is supplied with an a ir mask. if llie r o i u e i i ti a t i o n of visible tunics is kept within reasonable limit.- In mean ot a p p io p ria te ventilation, th ere will he no nk of puiouiii2 from N ( ) ;. fhidoe not mean that NOj "a- and visible Imne aie given off in anv constant ratio. I hev are not. Rut low concentrations of visible fume-, such as 2(1 to 23 mgs. eu.in., preclude anv possibility ot harm from breathing gaeou- impurities. Ventilation r e q im e m e n ts I (J t ot u n heated lank with lateral exhaust were loundtovaiv as follows: ( ulUuilrd hood-: rt = lf.3 ( w1,11ti i * I * I 1,-nmii i " - I\ rf.-OUv 11 I'lanfied lined-: t j i -- 1.9 ( width i 1 i Irnetli i " " <velocity 11 The optim um height of flange is that equal to tank width, and the optimum flange inclination is the m axim um allow able without interfereme with industrial operations. Slot velocity or slot width aie unsatisfactoiy criteria of hood performance, fh e important factoi is the quantity of air handled. The depth ot liquid surface below the slot does not affect greatlv the charac teristic of hood performance, but mar have an important effect on evaporation and entrainment of liquid. c o n c r e t e -- Cement mui Sect n -- February. 1941 Page 123 9i CONCRETE February, 1941 ADVERTISERS' INDEX A cqua-Pruf, Inc.................................... 92 Advance Cast Stone Co......................................................... - 6/ Aeroil B urner Co., Inc.................................................................. 86 Allan Mtg. & W elding- C om pany............................................ 94 American A ggregate Co................................................................ 94 Anchor C oncrete Mchy. Co........................................................ 82 Anchor Div. of Consolidated Concrete Machinery r* Corp.............................................-............................... 57-64 IncF Autom atic S pring Coiling Co.................................................... 85 Bassett F oundry C o .................................................................. 57 Besser M anufacturing Co.. . ........................... 57-64 Incl Bism arck H o t e l ...................................................... Blystone C o rp .................................................................... Butler Bin Co.............................................................. Calcium Chloride A^sn........ 71 Celotex Corp.. T h e ................................................................... 79 C. H. & E. Mfg. Co.................................................................... 85 Classified L i n e r s ................... 86 Colorcrete Industries. In c ............................... 53 Commercial Shearing & Stam ping Co................................. 37-78 Concrete E quipm ent Co.......................................... 85-95 Concrete Pipe M achinery Co...................... IK Concrete T ran sp o rt M ixer Co...................................................... 78 Consolidated Concrete M achinery C orp................ 57-64 Incl. C onstruction M achinery C om pany.......................................... 82 Connell, E. L., Co........................................................................ 86 Douelas F ir PI w o o d A ssn........................................................ 99 Dunli Mfg. C o ..W . E ...................................................................... 43 Flint & W alling Mfg. Co.. Inc...................................................... 84 Gclbman. LouiA .................................... 75 H arbor Plyw ood C orporation.......................................................69 Hauck M fg. Co................................. _ .............. 86 Haydite C orp..................................................................................... 94 Heltzel Steel Form & Iro n Co................................................... 30 Hotel Sherm an .... ..................................................................... 74 Ideal Div. of Consolidated Concrete Mchy Corp. ............................................................................................57-64 Incl. Jaeger M achine Company. T h e................................................. 19 Johnson Co., C. S............................................................... 84 Jo ltc re te ..................................................... 75 Kent M achine Com pany........................................................... 37-47 Kirk &: Blum Mfg. Co., T he............. *................................. ...... 92 K oehring Company ..................................................................... 27 K oudelka Supply & Mch. Co..................................................... 86 K ram er Corp., T he....................................................................... 29 L ackey, H . W ................................................................................ 8 6 / heh'igh Portland Cement Co..................................................... - 51 L iving-Stone Co............................................. - ............................. 86 Lone S tar Cement C orp.................................................- .......... 25 Mall T ool Co............................ . ..................................... ..... 87 M arquette Cement Mfg. Co.............................................................. M aster Builders Co.. T he .......................................................... 100 M edu8s6a Portland Cement Co...................................................... 32 8M3 epham , Geo. S.. & Corp............................................................ 93 Mil3e1s Mfg. C o.. . ...................................... ............................... 67 M ultiplex Concrete Mchy. Co............................................ 44-4$ Xoble, T hos. W ............................................................................ 86 O lsen, Eugene F ........................... .......................37-41 Incl. P o rtlan d Cement Association............ ........................................ 81 Price B rothers Com pany...................................... ............................. Professional S e rv ic e ....................................................................... 86 Ransom e Concrete Mchv. Co.................................................... 55 Reed Co.. R. F............................................................ 87 R icketson M ineral Color W o rk ? ................................................86 Roeth Vibrator Company ........................................... 85 Ryerson, Jos. T., & Son....... ... . ....................... 93 Sasgcn Derrick Co............... 97 Schaefer. Albert F ........................... ................. . . . 86 Schwalbe. L E ............................................................ 37-95 Sm ith Co.. T. L............................... 76-77 S p e c ia ltie s ............................. 86 Stearns Mfg. Co. .. . 37-41 Incl Sullivan Co.. The . . . . . ....................... 86 Swenson Pulverizers . . ................................... 98 T am m s Silica Co..................................................... .................. -- 86 T ym stone S tu d io ....................................................................... 48-49 Universal Div of Consolidated Concrete Mchy. C orp................................................................................ 57-64 Incl. U nion Steel Products C o ................................................................98 Universal Form Clamp Co............................................................ 73 W appat, Fred W ............................................................................ 97 W ayiite Company. T h e ............................................................ 67 W illiam s, C. K., Co...................................................................... 93 S ptw Up Your Pre-Cast Concrete U N IO N Joist Production with CHAIR STIRRUPS UNION ST EE L PRODUCTS CO. 4IS N. Berrien 9 1 Albion. Mich. SEE THIS ROLL CRUSHER AH Steel Construction . . . Dust Tight Roller Bearings . . . Small Diameter Crushing Rolls SWENSON PULVERIZERS, Cherry Valley, III.