I S D U S T R I A L A N D ENGINEERING C H E M I S T R Y
556
.
is the most successful equipment for calcining small stone. The increased market for hydrated lime has encouraged its use, for the fine material produced in the rotary is best adapted for manufacture into hydrate. Another factor that encourages the calcination of limestone fines is the gradual overcoming of the deep-root'ed preference for lump lime. The prejudice against pulverized quicklime arises from t'wo sources-( 1) the tendency for impurities to be concentrated in the fines, and (2) the great'er liability of air-slaking. The first of these objections is being met by improved quarry methods, particularly by cleaner separation of overburden aiid carity-filling impurities. The second objec,tion is being met by shipping quicklime in air-tight bags or drums. -1pebble quicklime screened from the product of the rotary kiln is now being marketed successfully. The writer has recently observed that unscreened quicklime produced in the rotary kiln is being shipped in considerable quantities. The Bureau of Mines has been studying this problem of utilization of fines for the past four years. About two years ago a series of t'ests was undertaken under the immediat'e direction of W. ?*I. Myers, of the Konmet'allic Minerals Station, and K.W. Hyde, of t,he Dwight-Lloyd Sintering Machine Co., to determine an adapt'at'ioii of the sintering machine t o lime-burning.' Briefly stated, it mas found that, the sintering iliachine could be adapted for successful calcination of spalls with fuel ratios comparable with present practice, and t,hat the sintering machine possessed some decided advantages over present lime-burning equipment. The chief probable advantages are the ability to calcine fines, a comparatively low investment, ease of operation, little loss of time for repairs and replacements, and a low maintenance expense. Present Tendency toward Increased Fines The point should be emphasized that the problem of utilizing spalls will probably become more urgent as time 7
Xye+s, B U Y . I l t n e s , R e p h Iiir'esti8elion.r 2762 ( J u l y , 1926).
T'ol. 19, s o . 5
goes on. There are two pronounced tendencies in the liiiie industry, both of which lead to increased production of fines. The first is the tendency toward underground mining. Bench work in mines may possibly be conducted without any great increase in spall production, but assuredly the driving of tunnels into the solid face requires heavy blasting in closely spaced drill holes, with excessive shattering and the inevitable production of a high percentage of fines. The underground miner certainly loses the advantage held by many open-pit operators of reducing spall output by simply pushing out the rock with low-grade explosives in widely spaced holes. The second tendency toward iricreasirtg spall product,ion is the employment of rock cru pointed out previously, hand sledging is a n effective iiieans of keeping down the percentage of fines. Although the power breaker is at a disadvantage in this respect. adi-aiitage3 of the mechanical equipment in other respects are gradually leading to its wider use. A wider eniploynient of tlie 4e:ini shovel and the power breaker seems inevitable, and humaii ingenuiby \Till be directed toward overcoming their disadvant'ages. The power shovel is sadly deficient in it.; ability to select rock for quality, and this has beeii R rtroiig point in favor of hand loading, but already this problem has been solved with fair satisfaction by the use of the picking belt. Thus it niay be seen that the tendency in iiioderri limerock production is toward iiiweasing fines. How ia this problem to be met-by the rotary kiln, by the sintering machine, by some other equipment, or by fiiidiiig n wider and more profitable market than now exists for the uncalcined fines? Great improvements mill no doubt be m a d e in rotary kilns. T i d e possibilities are also seen in the sintering machine. The writer is confident that the limeproducing industry will eventually solve this probleni as it has many other problems. History is repeated in that the ii-aste of today is the wealth of tomorrow, and may we not yet find through the evolution of equipment that the chips, spalls. arid dust now regarded as waste will p r o w to lie the forms best adapted for calcination?
Bridging the Gap between Research and Profits in the Lime Industry' By W. E. Carson RIVERTON LIME CO., RIVERTON, VA. 111 the lime bubiness-and it is rife inaiiufacturer to kiioiv something about his protlrict and with it-ij per cent of that romance can be traced to realize that his business had in it the elements of a n induhtry, the chemist. for through his research and efforts this and to inculcate within liini a respect for the product he \\--as ancient nidnstry is being reestablished and brought forward manufacturing. kt that time lime production v a s i n tlie hands of either a farmer who had a deposit, of limestone 011 as a qentient and living organism. Twenty-five or thirty years ago the lime industry was his land or a building supply dealer who had purch:~-etl :I asleep. and it4 awakening has been due to the persistent quarry and put up a little plant with the purpoie of getting n efforts of such men as those of which the AMERICASCHE~IICALcheaper grade of lime than he could purchase. Therefore. SOCIETY is composed. It has been a matter of great interest the rescue of this industry from extinction might surely lie t.o see the awakening of manufacturers to the idea that the termed a romance. For about twenty years it was necessary to centrnlize oiir burning of h i e is not alone dependent on the fire senses, but that other elements. such as intelligence, enter into it, and educational program on these embryo lime producer3 to get that the long-used statement t h a t "lime is lime" is not them to believe that their product should be del-eloped a' R manufacturing industry, and t o put in better machine accurate. The Sational Lime Association contributed to this awaken- better methods of manufacture, and acquire trade ethi That we succeeded, the lime indust'ry itself today stands ing when a few forward-looking manufacturers got together to form an association to develop and bring forward the as testimony, but while we have made great strides n-e have merits of lime. To our amazement, we found that before not yet been able t o dril-e home to a large number (if lime attempting our proposed program we had to educate the lime manufacturers the last and most important step-the iiecessity of chemical control aiid of preparing their product to 1 Received March 29, 1927.
I
F T H E R E is roiiiaiice
May, 1927
IAVDUSTRIALA S D E S G I S E E R I S G CHEMISTRY
557
done-namely, t h a t each individual see to it that the coinpany with which he is connected will not buy lime from any plant that does not employ a chemist, and that the purchase of this chemical commodity, lime, is not left entirely t o t’lie purchasing agent, whose sole thought’ is to chisel out a slightly lower price without considering the fact that limes differ as much as do human beings. are business men, and I cannot see why l l r , Chairman-we An analysis does iiot coiiinience to tell the whole story in you should have taken up so much of our time this morning by having one of those engineers, or chemists, or whatever you regard to lime. Many manufacturing plants, antl large ones might call them, t o appear before us, a s who wants t o listen t o a t that, buy their lime entirely on analysis, and do not consuch stuff a s they get off. 5l.Iy F a t h e r manufactured lime before sider the question of manufacture. This is one of the greatest me, a n d 1’11 bet he never heard such stuff a s was pulled this mistakes that the purchasers of lime for cheiiiical purposes morning. Let us quit this sort of talk, and attend t o business at our meeting. are making. We know that the reactions of a n o\-erburiied liiiie, a iiiediuni burned lime, and a lime that is burned a t In 1910, the iollon-iiig appears: low temperature, although having the sanie analysis, are l f r , Chairmail--I wish you would see t o it t h a t no more of entirely different. 111 causticizing, where quick settling i. them highbrows appear before t h e Association : I don’t know hould he lmriied to , d i a~ low ~ plasticity whether you pay these men for making speeches--if you do, iiie in tlie Steffeii process iii wgar-refiniiig you are just wasting the money of the Association--if you don’t, alioulcl 1ial-e a high plasticity cur\-e. These curl-es are 011you are wasting our time. \\-hat we want t o do is t o talk common sense a n d n o t about CO2 a n d such stuff-who cares whether CO?, tainerl with the aid of the pla.ticinieter mid the p1:isticinieter CO.{ or CO1 is in limestone or not--what we \\-atif. t o know is caii only he handled accurately itrid properly intcqretetl tly where \\-e can buy our coal cheap, etc. a technically trained man. This is a iiiethod hy whicli tlie In 1911, N r . Charleh K a r n e r offered a very allle paper oil user of lime can kiiow tlie temperature a t which lime should “Conihustiuti in Lime Kiln Practice.” The f’ollon-ing is be burned, and lie should study the huriiing in ortlcr to detertaken from tlie discu4oli of his paper: mine the best heat for his process. 111 other ~ ~ ( i r t lnot s . 01:ly should lie know the cheiiiical coiitent 1 1 f the h i e . Iiut also N r . Chairman -1 was astonished a t h l r . IVarner taking up whether that liiiie should stay as long :is po>sihle before the t h e timc of this -Issociation with the paper t h a t he offered, all fire or be niored from it at once, and this type of iiir-estigsti\-e full of scientific stuff; why, this is the sort of bull t h a t is gotten off by those chemist chaps. nork and control (:a11 (iiily lie effected h y tlie plant cheiiiist LVe all appreciate the good work you are doing, in bringing us In e\-ery order for chemical liiiie the matter of a d > manufacturers together, h u t why waste our time on such disshould enter. but :I plasticity nuiiiher should also Ile includ cussions? Chemistry is all right for college professors, b u t let me tell y o u , the quickest way t o ruin business is t o s t a r t euperiIn coiiiiiiercial m e clieiiiical control ia just as nwessary :is menting on it. I know a m a n outside of St. Louis who went in tlie cheiiiical industry. In oiie instance. failure to hydrate broke Iiecause he did not take the advice of his old foreman, b u t lime completely so that it was put o n the iiiarket crmtainiiig listened t o these chemists, who said they could b u r n lime with free lime caused great damage which n-ould have been avoided gas. So\\-, e\-eryliody knows t h a t you can’t burn lime except had the lime plant heen under cheiiiical coiitrol. In adriiixwith wood. tures wit,li cement and cenieiit niortars. quicklime i. destrucIn 1913 a iiieiiiber protested that we n-ere beclouding the til-e. making an unsound concrete and iiiortar. a d yet there real issue in the liiiie industry by discussing such questions: are a large iiuniher of hydrates that carry sufficient free liiiie as tlie effect of sulfur in its reaction o n lime. In the following t o make a n unsound lime-cement mortar, and 110 lime plant, year, :t spirit of tolerance toward “them rcieiitific chaps” uiiless under cheiiiical control, caii be sure of the iafety and hegall to ti(, -howii. for a request was made that a glossary be soundness of its hydrate. prepared to lxiiig the geiieral terms used in the lime industry But, alas! cheiiiists cost iiioney, :tiid laboratories are into line n.itli rheiiiical terms, and at, this meeting Dr. Lazell. expensive, hence the lime iiianufacturer who competes (111 an eiiiiiieiit lime clieiiiist, v a s requested to prepare an article price only. will not, eiiiploy liini. relying on the old adage oii hydrntcd hiie, to lie published a t the expense of the that “lime is lime.’’ Therefore. if we are to bridge the g:tp lietween research antl profits in the liiiic husiness, the AMEI~II I I T that tiiiie there has been a steady growth ill the C . i S cHEJIIC11, ~ O C I E T T 1lilISt trike 21 t)(Jltl stand ill eOl1I ~ e l i ~t1i:it f wietitific lriiowledge is a necessity it1 tlie Iiialiudeniiiing the purcliaGe ( ~ fliiiie for aiiy purpose Eroni :lily facture i ~ liiiie. i hut it is only iii a liiiiitetl nunibcr of plants plant that is iiot v-illing to spend nioney through the withat : i i y1.t +ciciitific kiionledge is being applied to the product ploymetit of a cheiiiist. K h O will ~vatclithe Iirocliictioii :uid it-elf. Limt tii:inufacttlrers have spent large s w t s of mol~ey to tlewlop tlict liest fire-resistant brick that it is possible t(J shipnient of lime and see t i , it that tlie particulsr type of liiiie needed for a specific gr(~ces.*is prepared. The liiiie 11-c i i i tlicJir 1)roc’es.;;they h a w iiir-estigated what is the liest cox1 t o U T : they lis\-e studied tlie m e of rotary kilns, gas industry needs just 4uch encourageiiiei~t and Imliciiig to kiln-, m i [ l fl:iiiic kilns; they have worked out the right aize make it a oiie hundred per cent iiidustry. o f -toiic, t o 11c u-ed; they h:iw eiiiployed iiieclianicul experts New Resistant Glass t o de\.e1op Iiiachinery to handle their product ; and they -1 glass t h a t withstands pressure, heat, and acids 1)etter t h a n 1in1.e lmriight u p their plaiith to a iize aiid efficiency that any yet known is being 1)roccssed iiicccssfully in Germany. iii:ike< tlir, liiiie iiitlustry ritrik a 5 orie ~ ithe ’ tii:ijor industriw. I t was first used for the manufacture oi glass tube water gages antl -411 tlii- 1i:i.G heeii done with the r - i m ( i f increasing output glass liars. The newest tulieq produced b y this method will :?lid declen-iiig mst of’ iiianufacturr. resulting in 1-he productain a cold-water pressure of 2i1, 45, :,ti 8,). and 100 atmospherts. This glass is also used in wenvini. ant1 silk spinning mills to tion a i i t l .-de iii’ lime a t a 1-ery low pricse. often. unfortunately, replace bobbins of wood, which Irequent!y liecame splintereti without regard t c J quality. - h i d this bring.; me t o tlie iiiaili and m l g h 2nd tore the thread? of the material. The dye irom tlionglit that I ivich to einpliasize-a thought which if it can colored threads could not he entirely removed from the woodeii lie trm.l:itetl into nccoiiipli~2itiielitwill he ( ~ fmore value to hobbins and impurities often resL:ltcdwhet1 colors were changed. our iiidiistry niirl the iiiore tliaii one huntlred antl fifteen Original a t t e m p t s t o s:il)stitiite g l a v hars for the wooden Imbwere unsuccessfiil because the glass med would n o t withindustrie. into which lime eiiter;. or tlie hix Ii~uitlrc~d different, bins qtand ducttiations of temperature. T h e new glass, howevcr. type- oi I I - P o f lime. tliaii iiiiy r ~ t l i wolie tl~iiigthat caii lie will stand a sudden chan:ge from 1 t i i ) ’ t o 0’ C. without damagt,.
meet tlie clieiiiical requireiiient of the process i i i which it is t o be used. few excerpts from the minutes of some of these meetings may be of interest in showing the attitude t h a t we had t o meet in the early days. Going back t o 1909, bhe following appears in the minutes:
