556 I S D U S T R I A L A N D ENGINEERING CHEMISTRY T'ol. 19, s o . 5

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. -1 pebble quicklime screened from the prod- uct 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, BUY . I l t n e s , R e p h Iiir'esti8elion.r 2762 ( J u l y , 1926).

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 an 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 dis- advant'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 lime- rock 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 uncal- cined fines? Great improvements mill no doubt be made in rotary kilns. T i d e possibilities are also seen in the sintering machine. The writer is confident that the lime- producing 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 row 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.

F T H E R E is roiiiaiice 111 the lime bubiness-and it is rife with i t- i j per cent of that romance can be traced to the chemist. for through his research and efforts this

ancient nidnstry is being reestablished and brought forward as a qentient and living organism.

Twenty-five or thirty years ago the lime industry was asleep. and it4 awakening has been due to the persistent efforts of such men as those of which the AMERICAS CHE~IICAL SOCIETY is composed. It has been a matter of great interest t.o see the awakening of manufacturers to the idea that the burning of h i e is not alone dependent on the fire senses, but that other elements. such as intelligence, enter into it, and that the long-used statement tha t "lime is lime" is not accurate.

The Sational Lime Association contributed to this awaken- ing when a few forward-looking manufacturers got together to form an association to develop and bring forward the merits of lime. To our amazement, we found that before attempting our proposed program we had to educate the lime

I

1 Received March 29, 1927.

inaiiufacturer to kiioiv something about his protlrict and realize that his business had in it the elements of an induhtry, and to inculcate within liini a respect for the product he \\--as manufacturing. kt that time lime production v a s i n tlie hands of either a farmer who had a deposit, of limestone 011

his land or a building supply dealer who had purch:~-etl :I quarry and put up a little plant with the purpoie of getting n cheaper grade of lime than he could purchase. Therefore. the rescue of this industry from extinction might surely lie termed a romance.

For about twenty years it was necessary to centrnlize oiir educational program on these embryo lime producer3 to get them to believe that their product should be del-eloped a' R manufacturing industry, and to put in better machine better methods of manufacture, and acquire trade ethi

That we succeeded, the lime indust'ry itself today stands as testimony, but while we have made great strides n-e have not yet been able t o dril-e home to a large number ( i f lime manufacturers the last and most important step-the iieces- sity of chemical control aiid of preparing their product to

May, 1927 IAVDUSTRIAL A S D ESGISEERISG CHEMISTRY 557

meet tlie clieiiiical requireiiient of the process i i i which it is to be used.

few excerpts from the minutes of some of these meetings may be of interest in showing the attitude tha t we had to meet in the early days. Going back to 1909, bhe following appears in the minutes:

Chairman-we are business men, and I cannot see why you should have taken up so much of our time this morning by having one of those engineers, or chemists, or whatever you might call them, t o appear before us, as who wants t o listen t o such stuff as they get off. 5l.Iy Fa ther manufactured lime before me, and 1’11 bet he never heard such stuff as was pulled this morning. Let us quit this sort of talk, and attend t o business at our meeting.

l l r ,

In 1910, the iollon-iiig appears: l f r , Chairmail--I wish you would see to it t ha t no more of

them highbrows appear before the Association : I don’t know whether you pay these men for making speeches--if you do, you are just wasting the money of the Association--if you don’t, you are wasting our time. \\-hat we want t o do is to talk common sense and not about CO2 and such stuff-who cares whether CO?, CO.{ or CO1 is in limestone or not--what we \\-atif. to know is where \\-e can buy our coal cheap, etc.

In 1911, N r . Charleh Karner offered a very allle paper oil “Conihustiuti in Lime Kiln Practice.” The f’ollon-ing is taken from tlie discu4oli of his paper:

N r . Chairman -1 was astonished a t h l r . IVarner taking up the timc of this -Issociation with the paper tha t he offered, all full of scientific stuff; why, this is the sort of bull t ha t is gotten off by those chemist chaps.

LVe all appreciate the good work you are doing, in bringing us manufacturers together, h u t why waste our time on such dis- cussions? Chemistry is all right for college professors, bu t let me tell you, the quickest way t o ruin business is to s ta r t euperi- menting on it. I know a man outside of St. Louis who went broke Iiecause he did not take the advice of his old foreman, bu t listened to these chemists, who said they could burn lime with gas . So\\-, e\-eryliody knows tha t you can’t burn lime except with wood.

In 1913 a iiieiiiber protested that we n-ere beclouding the real issue in the liiiie industry by discussing such questions: as tlie effect of sulfur in its reaction on lime. In the following year, :t spirit o f tolerance toward “them rcieiitific chaps” hegall to ti(, -howii. for a request was made that a glossary be prepared to lxiiig the geiieral terms used in the lime industry into line n.itli rheiiiical terms, and at, this meeting Dr. Lazell. an eiiiiiieiit lime clieiiiist, v a s requested to prepare an article oii hydrntcd hi ie , to lie published a t the expense of the

I I I T that tiiiie there has been a steady growth ill the I ~ e l i ~ f t1i:it wietitific lriiowledge is a necessity it1 tlie Iiialiu- facture i ~ i liiiie. hut it is only iii a liiiiitetl nunibcr of plants that : i i y1.t +ciciitific kiionledge is being applied to the product it-elf. Limt tii:inufacttlrers have spent large swt s of mol~ey to tlewlop tlict liest fire-resistant brick that it is possible t(J 11-c i i i tlicJir 1)roc’es.;; they h a w iiir-estigated what is the liest cox1 to U T : they lis\-e studied tlie m e of rotary kilns, gas kiln-, m i [ l fl:iiiic kilns; they have worked out the right aize o f -toiic, t o 11c u-ed; they h:iw eiiiployed iiieclianicul experts to de\.e1op Iiiachinery to handle their product ; and they 1in1.e lmriight u p their plaiith to a iize aiid efficiency that iii:ike< tlir, liiiie iiitlustry ritrik a 5 orie ~ i ’ the tii:ijor industriw.

-411 tlii- 1 i : i . G heeii done with the r - i m ( i f increasing output :?lid declen-iiig mst of’ iiianufacturr. resulting in 1-he produc- tion a i i t l . -de iii’ lime a t a 1-ery low pricse. often. unfortunately, without regard t c J quality. - h i d this bring.; me to tlie iiiaili tlionglit that I ivich to einpliasize-a thought which if it can lie trm.l:itetl into nccoiiipli~2itiielit will he ( ~ f more value to our iiidiistry ni i r l the iiiore tliaii one huntlred antl fifteen industrie. into which lime eiiter;. or tlie hix Ii~uitlrc~d different, type- oi I I - P o f lime. tliaii iiiiy r~ t l iw olie tl~iiig that caii lie

done-namely, tha t each individual see to it that the coin- pany 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 to 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.

An analysis does iiot coiiinience to tell the whole story in regard to lime. Many manufacturing plants, antl large ones a t that , buy their lime entirely on analysis, and do not con- sider the question of manufacture. This is one of the greatest mistakes that the purchasers of lime for cheiiiical purposes 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 low temperature, although having the sanie analysis, are entirely different. 111 causticizing, where quick settling i.

hould he lmriied to , d i ~ ~ a low plasticity iiie in tlie Steffeii process iii wgar-refiniiig

alioulcl 1ial-e a high plasticity cur\-e. These curl-es are 011-

tainerl with the aid of the pla.ticinieter mid the p1:isticinieter caii only he handled accurately itrid properly intcqretetl tly a technically trained man. This is a iiiethod hy whicli tlie user of lime can kiiow tlie temperature a t which lime should be burned, and lie should study the huriiing in ortlcr to deter- mine the best heat for his process. 111 other ~~( i r t l s . not 01:ly should lie know the cheiiiical coiitent 1 1 f the h i e . Iiut also whether that liiiie should stay as long :is po>sihle before the fire or be niored from it at once, and this type of iiir-estigsti\-e nork and control (:a11 (iiily lie effected h y tlie plant cheiiiist

In e\-ery order for chemical liiiie the matter of a d > should enter. but :I plasticity nuiiiher should also Ile includ In coiiiiiiercial m e clieiiiical control ia just as nwessary :is in tlie cheiiiical industry. In oiie instance. failure to hydrate lime completely so that it was put on the iiiarket crmtainiiig free lime caused great damage which n-ould have been avoided had the lime plant heen under cheiiiical coiitrol. In adriiix- tures wit,li cement and cenieiit niortars. quicklime i. destruc- til-e. making an unsound concrete and iiiortar. a d yet there are a large iiuniher of hydrates that carry sufficient free liiiie t o make an unsound lime-cement mortar, and 110 lime plant, uiiless under cheiiiical control, caii be sure of the iafety and soundness of its hydrate.

But, alas! cheiiiists cost iiioney, :t i id laboratories are expensive, hence the lime iiianufacturer who competes (111 price only. will not, eiiiploy liini. relying on the old adage that “lime is lime.’’ Therefore. if we are to bridge the g:tp lietween research antl profits in the liiiic husiness, the AMEI~I-

deniiiing the purcliaGe ( ~ f liiiie for aiiy purpose Eroni :lily

plant that is iiot v-illing to spend nioney through the wi- ploymetit of a cheiiiist. K h O will ~vatcli the Iirocliictioii :uid shipnient of lime and see t i , it that tlie particulsr type of liiiie needed for a specific gr(~ces.* is prepared. The liiiie industry needs just 4uch encourageiiiei~t and Imliciiig to make it a oiie hundred per cent iiidustry.

C . i S cHEJIIC11, ~ O C I E T T 1lilISt trike 21 t)(Jltl stand ill eOl1-

New Resistant Glass -1 glass tha t withstands pressure, heat, and acids 1)etter t h a n

any yet known is being 1)roccssed iiicccssfully in Germany. I t was first used for the manufacture oi glass tube water gages antl glass liars. tain a cold-water pressure of 2i1, 45, ti:, 8,). and 100 atmospherts.

This glass is also used in wenvini. ant1 silk spinning mills to replace bobbins of wood, which Irequent!y liecame splintereti and m l g h 2nd tore the thread? of the material. The dye irom colored threads could not he entirely removed from the woodeii hobbins and impurities often resL:ltcd whet1 colors were changed. Original a t tempts to s:il)stitiite g l av hars for the wooden Imb- bins were unsuccessfiil because the glass med would not with- qtand ducttiations of temperature. The new glass, howevcr. will stand a sudden chan:ge from 1 t i i ) ’ to 0’ C. without damagt,.

The newest tulieq produced b y this method will