M cGraw-Hill Company, Inc. D evoted to th e O p e ratm g , Techm cal a n d B usiness
James H. McGraw, President _ , R. Dawson H a l l
E. J. Mehren, Vice-President P roblem s o f th e Coal-M inm g ln d u s tr y Engineering E ditor
Volume 26 NEW YORK, OCTOBER 16, 1924 Number 16
T h e O ld , O ld Q n e s tio n
T
H E D IF F IC U L T Y and perh aps in justice of curin g overdevelopment of coal by arb itrarily prohibiting the sin king of new m ines is illustrated by the case of N orth Carolina. T h at state needs morę power. The dem and already h as reached a point th at ju stifie s the development of home deposits of coal, in spite of facto rs which have limited their exploitation up to this' year, according to the sta te ’s geological survey. The Deep R iver field with a present potential output of only 100,000 tons annually is especially at the fore.Should this field be encouraged to increase its output du rin g the next few y ears to the million-ton m ark which seem s, to the state survey, to be “ a reasonable vision ” ? Who is there to say N orth Carolina nay, especially if she em barks broadly and intelligently upon a program of byproduct coking? It is the old, old ąuestion which has no answer.
Y e s , I t C a n B e D o n e , M r. L e w is
T
H E R E really is such a thin g as fe arless, righ teous control of a labor union. The International P ress- men’s Union of N orth A m erica proves it. So we respectfully invite the attention o f Joh n Lew is, “ the m ost pow erful labor leader,” to the fa c t th at P resident B e rry of the pressm en, who whipped back into line the New Y ork locals a fte r a strike in violation of contract and who then m ade them pay the cost of that strike, has been upheld by the International a t its Knoxville convention. Such a thing a s punishing contra ct violators is, therefore, possible, and we don’t want Mr. Lew is to overlook it.
No, we haven’t forgotten th at P resid en t Lew is booted A lexander H ow at and the whole k it and caboodle of How at office holders out of the union when they struck in K an sas in spite of L ew is’ orders. T h at w as con- siderable, of course, but we m ust add that defense of the sacredn ess of contract w as not the only thing th at m otivated our dogged faced (the first adjective has two syllables, not one) m iner chieftain . H ow at w as and is a radical whose policy is to destroy everything a t all costs. He would gleefully destroy the m in ers’ union if he could. In fa c t there w as some sligh t dan ger of th at very th in g fo r radicalism ju s t then w as on the gain.
So Mr. Lew is, in sm acking H ow at fiat w as defending the contract with one hand but with the other, and with every political force at h is command, he w as defending his own union organization.
The ąuestion th at occurs to us is : Why h asn ’t the dogged (tw o syllables a g a in ) faced m iner presiden t risen a s gallan tly to the defense of the sacredn ess o f other con tracts th at have been broken repeated ly?
There w ere plenty o f opportunities. B u t Mr. Lew is and h is state ch iefs have not m ade the rank and file understand th at the whole force o f the organization is behind sig n a tu re s on contracts. M r. B e rry h as m ade
New Y ork understand this, and his rank and file sup- port him. What ails the rank and file of m in ers? A re they contract violators by naturę or is it ju s t th at President Lew is is a fra id of them ?
S e a r c h in g f o r th e C a u s e s
D
URING recent years we have noted considerable progress being made in the more efficient and sa fe use of electricity in the m ines. E lectric drives have been applied to eąuipm ent which previously had been driven by steam engines because of fire or explo- sion hazards. H igher voltages have been introduced into the mines. Some companies have successfully applied electrical eąuipm ent which not long ago w as considered highly dangerous.Much of the credit fo r the success of th is work is due to the careful and considerate engineering of some few of our leading engineers and also to the work and in vestigation s of the B u reau of M ines. E xperi- mental work, research, in vestigation and te sts o f the B ureau have shown the d an gers of the use of certain types of ap p aratu s when they come in contact with gaseous m ixtures. T ests, recom m endations and ap- provals m arkedly have reduced hazards of electrical eąuipment. Today we have perm issible electric lam ps, controllers, headlights, locomotives, fu se s and portable storage battery power u n its; also, recom m endations and su ggestio n s which, if followed, greatly reduce liabilitiy of accident from other sources.
O th e r s S u f f e r T o o
C
OAL M IN IN G isn ’t the only in du stry su fferin g the pains o f overdevelopment. Consider oil. A lw ays reckless, alw ays prodigal, the host which produces A m erican oil rushed men, money and m achinery around the country in the boom day s du rin g and im m ediately a fte r the war, sinking 25,000 wells and h alf a billion dollars in twelve m on ths! The country had to have th at oil and it got it. Since then the host has been busy try in g to save itse lf from inundation by the flood it produced. The b est protection the oil host could raise apparently, w as a counter flood of m ore oil.The resu lts of th is policy are m any and d istu rb in g.
C hief among them is w aste. W here the coal producer leaves an average o f only a little over one-quarter of the total deposit in the ground, the oil man leaves three-ąuarters. And there are oil lo sses in handling and consumption th at rival the w ell-advertised w astes o f coal. While, o f course, strenuous efforts are m ade to check th is heavy loss of oil, the dom inating idea in the head of every oil man i s : “ W here can I b rin g in more good w e lls?”
“ It is all too evident,” sa y s G eorge O tis Sm ith, director of the U. S. G eological Survey, “ th at the oil bu sin ess is trav elin g ‘in h igh ’ w ith the g e a r sh ift locked. E very th in g is speeded u p ; the u rge o f ever-
533
in creasin g consumption stim ulates the provision of su rplu s capacity in wells and refineries; then a lively competition among producers leads to an artificial stim ulation o f demand, and the m erry round goes on.
It is a pace th at kills— and loses money.”
So the coal man with the w eight of non-producing m ines crush in g him down is not the only fuel producer h arassed by overdevelopment. H is industry h as much g rie f in common with the oil m an’s. Somehow the less spectacular coal industry seem s to us the sounder of the two. Its w astes are probably less, its fu tu rę is better assured because its resources are, and its financing has no $300,000,000 a year of fraudulent stock promotion charged ag ain st it by the Postoffice D epart
ment, as had the more alluring oil.
m -
“ S t a n d a r d iz a t io n ” M e a n s S o m e t liin g N o w
A
L L T H IS T A L K about stan dardization which the , country has heard these la st few years is not m ere high-flown language. There has been much definite accomplishment, thanks largely to the energy and resources of Secretary Hoover’s D epartm ent of Commerce at W ashington. Already the lumber industry has reduced the number of lumber-yard item s by 60 per cent, a sim plification that is counted on to check to a considerable degree the w aste in th at industry conservatively estim ated at $250,000,000 yearly. Woven wire fencing m an ufacturers have reduced their styles and sizes from 552 to 69. Hollow building tile types, sizes and w eights have dropped from 36 to 19; forged tool varieties are down 46 per cent and so on. The list of sim plifications is a long one.U nfortunately there is not yet any extensive reduc- tion to report in in dustries directly servin g coal mines, nor in coal m ining practice itself, although Col. R oberts’
committee of the Am erican M ining Congress is keeping the subject alive. The cam paign o f education is a long, uphill fight and can ’t be won in a day. B u t it can be won. E xcessive stores of repair p a rts in mine stockrooms is one thing th at is going to help the advocates of standardization. Some m ining companies have already realized the cost of capital frozen up in such stocks. Others are w aking up to it. T hus perhaps the propaganda has sunk deeper than we realize.
T h e I n t a n g ib le S o m e t h in g
T
H E R E M U ST be co-operation in any organization.No one w as ever heard to contradict the m any and freąuen tly repeated statem ents to th is effect. But, there is som ething in a highly successful mine-operat- ing organization which came before and made co- operation possible. We seem to have no single word by which it is adeąuately expressed. It is in reality an urgen t desire on the p art of the salaried employees to promote the generał w elfare of the business.
There m ust be a good reason fo r th is desire. In some cases it seem s to be prompted by nothing more than a sincere respect or high regard fo r superiors, coupled perhaps with a sense of obligation because of fa ir treatm ent accorded or fav o rs received. In other cases, ownership of dividend-paying stock of the em- ploying company is the secret. A gain, we find rare in stances where a personnel is made up alm ost entirely o f men who are fa r above the average in gu ard in g the em ployer’s interest.
C arefu l an aly sis of successful organizations would
perhaps disclose other s e c r e t s f o r prom oting the terest of those who are in position s to make
the average coal-mining company. T here ^ u®t be g ° management, and therefore real co-operation b u = befo this can be secured the m anagem ent m ust in some w ay furnish an incentiv, for the employee to en te rlam a t all tim es a desire fo r the generał good of the firm.
L e t C o a l A lo n e ; T h a t ’ s A ll
W
E A G R E E with P resid en t H utchinson of the N ational Coal A ssociation th at the one m ost lm- portant thing the coal industry needs is to be let alone— ju st let alone. It seems such an easy boon fo r the country to gran t, yet what is the use of expecting the country to gran t it? The whole coal in dustry surely knows that the only way it can protect its n g h t to mind its own business is to fight fo r it. Im agin e hay- ing to fight fo r a privilege which ought to be u n iv e rsa l!
But there are worse plights. One of them i s to be com- pelled to accept the deserts of him who will not defend his own ju st cause.
I f there are any thinking men in the coal in dustry who believe th at they are secure a g a in st such b itter deserts, let them take heed of the straw s in the gu sty wind of the present national political cam paign. Gov- ernment-ownership sentim ent is abroad in the land.
The body of propaganda to which it belongs is rolling up a vote which next month will asto n ish some of these coal mine owners who lunch at the club togeth er and easily convince each other th at sound con servatism is bound to prevail. They are not counting even the union coal miners, who are certainly goin g to poll a heavy radical vote along with other dissatisfied elements.
T his is not a prophecy th at the n ext presid en t of the United S tates will be a radical. B u t it is a prophecy that a radical sentim ent fo r governm ent ow nership will register heavily at the polis next month and will be persistent in the next C ongress. It m ay not pu t forth an immediate demand fo r public ow nership of
coal
mines. A low-price year like 1924 is a poor one in which to tell the people they can run m ines better than the owners. B ut it is not such a bad y e a r totalk
them into running railro ad s and otherUtilities.
And coal is always next a fte r railro ad s. T h at is the point.Mr. Hoover has some sound argu m en ts a g a in st gov- ernment ownership of such Utilities. H e points out that utility service is better in A m erica than in any other country, and that the 2,700,000 employees are paid w ages givin g the h igh est stan d ard o f living and comfort on earth. He show s th at our railro ad s under government control durin g the w ar lost $1,600,000,000 that was paid in tax es by the people and th at the roads sińce then have not m anaged to b rin g th eir average earnings even up to 4 per cent. T here is alread y com- mission control over rate s and issuan ce of stock by Util
itie s; why should we have more control than th a t?
I f the Utilities were to be bought by the governm ent, a tax revenue of $600,000,000 would be stopped and the country would have to m ake it up in added ta x burden.
Many a sane labor unionist sees the tru th of these things, yet it cannot be denied th at the governm ent ownership nostrum is “ goin g good” rig h t now. The coal industry should aw ake to th is fa ct. S ittin g back and view ing with alarm from club windows will accom- plish little. A hot b attle to be let alone is im m ediately ahead. The sooner the in d u stry pitches into th at fight the better its chance o f being let alone.
October 16, 1924 C O A L A G E 535
Proper Handling and Storage Reduce Oil Losses
H ig g le d y - P ig g le d y O il S t o r a g e I s W a s te f u l— A t S o m e P l a n t s O n e F o u r t h o f th e L u b r ic a n t P u r c h a s e d I s L o s t — S t o r a g e U n d e r g r o u n d in T a n k s w ith M e t e r in g P u m p s C o n s e r v e s L u b r ic a n t s
By Al p h o n s e F . Br o s k y Assistant Editor, Coal Age
Pittsburgh, Pa.
I
T W OULD not be f a r from the truth to say that at least 25 per cent of the oil purchased by the coal industry is w asted. Although unąuestionably the m ajo r portion of this loss resu lts from too-generous an application of oils and g rea ses to the moving p arts of machines, the fundam ental cause of w aste lies in the methods employed in storin g, issuin g and otherwise handling the lubricants before they are actually applied.The prim ary requisite fo r preventing much of th is known w aste is adeąuate facility fo r storin g lubri
cants. System in the m anagem ent of mines today is being extended to include th is im portant item of pro- duction cost. Ten y ears or more ago it w as a common sig h t at the mines to see barrels of oil scattered about with no pretense at orderliness. Sp igo ts were not alw ays closed tig h tly ; som etim es they were not used at all.
Results of Careless Storage at Min e s
The direct result of all th is carelessness, chaos and confusion w as th at the ground on which the b arrels stood fa irly seeped oil. Men were allowed to help them selves to a s much lubricant a s they wanted as often a s they desired. And when only a galion or two th at reąuired coaxing to pour out rem ained in a barrel, this
Container
w as abandoned a s empty and a fulibarrel
tapped. T h is word picture of carelessness and w aste is true to life and m ay yet be seen a t many mines.The accom panying illustration s show several meth
ods used fo r sto rin g oil a t the m ines. Each h as its place though a s f a r as possible they have been arran ged
in an ascending scalę o f m erit, F ig . 1 exhibiting the most w asteful method and F ig . 4 the one m ost satis- factory and economical.
Enough already has been said concerning the slovenly methods depicted in F ig . 1. I f a company feels th at it cannot afford to erect an oil house furn ish ed with reservoirs and pumps, it a t least can provide a rack constructed of rails restin g on p ierś as shown in F ig . 2. B y so doing a noticeable improvement over conditions existin g in F ig . 1 is effected.
Oil Stored in Ta n k s According to Grade
A still better method of sto rin g oil is shown in F ig . 3. Here oil is emptied from the b arrels in which it is received into tanks restin g upon or raised slightly above the floor of the oil house. Three grad es of oil are kept in a like num ber of tanks. In th is p articu lar instance one grade is fo r engines, another fo r pit cars and a third fo r conveyors.
The methods illu strated in F ig . 4 are those used a t the Lew is Mine of the Hudson Coal Co., near Clarks- burg, W. Va. They are recommended a s fa cilitatin g not only the sto rag e but also the handling and issu in g of lubricating oils. A better arrangem en t would be difficult to conceive.
The oil house a t the Lew is mine is 15-ft. sąu are inside and is constructed of concrete blocks. It is provided with a cellar in which three steel oil drum s are installed 5 ft. below the fr o st line. The floor of th is building is of concrete reinforced with 40-lb. rails.
Each o f the three tanks h as a capacity of 283 gal.
f ig. i Slovenly Storage
E v e ry th in g should have its place a t a m ine, in such a lo- c a tion th a t the w orker w ill n o t be unnecessarily ex- posed to dang e r in reaching it. Plac- in g these oil b a r rels between a m a in line a n d a m in e tra c k renders the oiler’s jo b u n necessarily hazard- ous. They were p ro bab ly p 1 a c e d here fo r the sole reason th a t th is w as a convenient d u m p in g p o in t fro m the fre ig h t car.
Fig. 2—Orderly Open-Air Oil Storage
I f an under-cover storage cannot be afforded this picture shows the next best alternative. Here not only has order supplanted chaos b u t the barrels are supported a t convenient he igh t above the ground where their spigots are readily accessible.
and holds a p articular kind of oil or that intended fo r some specific purpose. The pumps are so arran ged that they m ay be adju sted to m easure out a given ąuan tity of oil, and float g a g e s indicate the ąuan tity rem aining in the tanks at all tim es. A s little space is occupied by the pum ps there is sufficient accommodation inside the house fo r storin g b arrels of oil and grease.
Good Location of Oil House Saves Labor
Mines producing large tonnages of coal are big con- sum ers of oil. A t such plants provision should be m ade fo r elim inating all needless labor entailed in handling barrels between the railroad car and the oil house. One excellent plan fo r th is purpose w as adopted by the Jam iso n Coal Co. a t its No. 7 minę a t Bar- rackville, W. Va., now owned by the Bethlehem Mines Corporation. A t th is p articular plant the oil house w as located on the sam e spur as, and about 60 ft. from the supply building. The floor of the structu re w as a t an elevation slightly lower than the floor o f a rail
road car, so that a bridge plank could be laid between the two levels.
All in all the layout w as one which greatly lightened the labor of tra n sfe rrin g barrels from the c ars to the oil house. One end of the building w as occupied by tanks and pumps, somewhat sim ilar to those shown in F ig . 3, while the rem aining space w as used fo r
Fig. 3—Inexpensive Yet Efficient Storage
A s m a li flre-proof b u ild in g an d three storage tanks fltted w ith a p u m p is about a ll th a t is necessary for this k in d of a storage Its chief shortcom ing lięs in the fa c t th a t the oil is unprotected fro m cold an d in Winter m a y become decidedly slugeish A
wooden incline facilitates ra is in g fu li barrels to the r a c k above tne lanKs.
Fig. 4—Modern Oil-Handling Equipment
SPmhu,nStv ^ere enl pl.oyed for storing an d issuing oil stro n g ly re- im a.n . u p-to-date gasoline flllin g station . The storage tanks are located In a cellar below the fro st line The E f S^ h ? r ‘ded W ith, m e' ers, an d the ta n k s w ith in d ic a t in f so th a t a n accurate check can be ke pt on the ą u a n tity draw n from the ta n ks a n d th a t re m a in in g on hand .
in a heavy lo ss; it is w ise to con struct a fireproof building fo r storin g oil. T h is should be placed a t a distance o f at least 60 to 100 ft. from any ad jacen t structure.
(3) The arrangem en t inside the oil house should insure sufficient w arm th in the w inter m onths to m ain- tain the fluidity of a medium or heavy oil a t or n ear the consistency attained in sum m er.
(4) Oil should be em ptied from the b arre ls in which it is received into sto rag e tan ks from which it should be removed by pum ping.
I f these recom m endations are adopted eith er wholly or in part, an appreciable sav in g will be realized.
Furtherm ore, the poten tiality o f the fire h azard will be lowered. T h is is a con sideration th a t cannot be disregarded a s the d an ger o f fire is ever present.
the storage of b arrels which were rolled onto fo u r slightly elevated track s constructed of ordinary mine rails.
A few recommendations fo r the better handling o f oils as Luggested by the best practices now in generał use may be enumerated as fo llo w s:
(1) Oil should be kept under lock and key and issued by the man in charge of supplies only upon presen ta- tion of a properly signed reąuisition.
(2) A s a precaution ag ain st the spread of fire, oil should not be stored in the regu lar supply house o r in any other building which, if burned, would re su lt
October 16, 1924 C O A L A G E 537
Details o f Actual Mining in Alabama Coal Beds
•
T h ic k n e s s o f B e d a n d I t s P it c h D e te r m in e t h e P la n o f M in in g — O n M o d e r a t e I n c lin a tio n s C a r s A r e T a k e n t o th e F a c e — I n S t e e p B e d s C h u t e s o r C o n v e y o r s a r e U s e d
By Milton H. Fies
Vice-President, De Bardeleben Coal Corporation, Birmingham, Ala.
J
U S T a s a thin seam w as treated in detail, as an ex- ample of a fiat A labam a bed, a m easure of medium thickness will be considered a s being typical o f the medium pitching class. D eposits of th is type in A labam a are found principally in the Cahaba field. Condi- tions here encountered are extremely variable. Ali the beds pitch; in seam s now being worked the dip varies from 5 to 49 deg., the roof over the coal v aries from fa irly good to b a d ; in some instances, en tries and road- w ays in rooms are cross-collared. The rooms are tim- bered closely with heavy capboards over the props.
The bottom varies from hard to soft. With these ex- trem es in mind, it is m an ifest th at the sy stem s of m ining and tim bering followed differ from mine to mine, or even from section to section in the sam e working.
Coal beds in th is field are opened on slopes that follow the coal from the outcrop (see F ig . 14). At in tervals o f from 200 to 300 ft., depending on the thickness of the m easure, en tries or lifts are turned rig h t and left from the slope on the strike. The slopes have one or two a ir courses paralleling them, with a p illar 25 to 50 ft. thick between. When two a ir courses are driven, one is brushed, if the thickness of the coal m akes it necessary, to a height of 6 ft. so th at it may serve a s a manway. T h is p assag e is usually 10 ft.
wide. The other a ir course is from 6 to 13 ft. wide and is driven to the height o f the coal. A ir courses parallel the cro ss entries, generally on the dip side.
The en tries are driven “ w ater level” ; th at is, follow ing the undulations o f the seam s on sligh tly risin g grad es, to fa cilitate tran spo rtatio n and drain age. Rooms are turned off the lifts to the rise on 35- to 60-ft. centers.
The coal is won, where the pitch is not too steep and the thickness o f the bed perm its, by delivering the car a t the face with mules or by the g rav ity method.
On Moderate Pit c h es Cars are Jigged to Face
The generał practice is to use the g rav ity method in beds o f th is class, where the pitch v aries from 5 to 20 deg. Room s are driven to the rise and double tracked, the track being placed close to rib s and ex- tended to w ithin about 10 ft. of the room face. Pulleys, from 8 to 12 in. in diam eter, are clevised to posts set about 5 ft. in advance o f the room track s. A rope of ample length to provide fo r room advancem ent and encircling the pulleys, is attached to the loaded and empty cars. An im provised brak in g device (see F ig . 15), situ ated m idw ay between and in line w ith the pulleys, enables the m iner to regu late the speed o f the outgoing car, a s it pulls the incom ing empty to the face. Such a method reąu ires g re a t care in the layin g o f room track s, in the settin g o f pulley tim bers and in the use of the rope.
Note— Th ird p a r t of a rtic le entitle d "A la b a m a Coal-M inine P ractices,” presented a t the B irm in g h a m m eeting o f the A m e rican In s titu te of M in in g a n d M e ta llu rg ic a l Engineers.
In advancing rooms three lengths of rope are u sed;
these ropes are 150, 250, ańd 350 ft. long. There are two links in each rope, which are fasten ed to it by clamps, the surplus rope being thrown on the mine c a r s;
these links are moved along the rope a s the room ad- vances. When the room h as progressed beyond the point where one length of rope can be used, th is length is moved to some other room and a longer one substi- tuted. The ropes are I to i in. in diam eter, depending on the pitch.
It has been found th at patent brake pulleys are not
Fig. 14—A Mine in a Bed of Medium Pitch
A slope is driven from the outcrop d irectly dow n the pitch.
F ro m this levels are turned to either side a n d double-tracked, double-necked rooms tu rn e d up the pitch. A ir courses are driven below the levels. Cars are jig g ed to an d from the face.
successful. S p ra g s are used in the wheels of loaded cars where the pitch is 12 deg. or over. On th is pitch wooden room ra ils are generally used as the dam p steel raił does not give enough friction , even though the wheels are spragged.
A modified plan of m ining a bed o f medium pitch is shown in F ig . 16. The mine is developed through a slope, together with an a ir course and a manway.
Level or strike headin gs driven double, spaced 700 to 800 ft. a p a rt and av erag in g about 10 ft. wide, are turned rig h t and le ft off the slope. A u x iliary slopes, or “ dips,” are turned off the headin gs about every 600 ft. The system of m in ing employed is the room- and-pillar panel plan with all wide work parallelin g headin gs and au x iliary slopes parallelin g the m ain slope. H oist h eadin gs are driven to the rise a distance o f 100 to 120 ft. off the h eadin gs fo r the purpose of handling coal from dip panels. Rooms, av e rag in g 24 ft.
wide with intervening 20-ft. p illars, are turned rig h t and le ft off dip slopes and a b a rrie r p illar approxi- m ately 40 ft. thick is m ain tained between the strik e entry and the first room turned off d ip slopes.
Coal is hauled, by rope, out of dip slopes by an elec-
D-Door %=Curłam II K 10vcrcas iI -WoodSbpping t-L 're Brołtice -*-Direch'on ui nu
A błock of4 or5rooms dr!ven to the air course about 270fi, the4 or5rooms are brohen into o t course for the futurę cnring ofthe rooms
AirCcurse Slanf every 25Off The loaded car pulls the empty fo łhe face.
A brake controts the speed. Before the bad/s cuf-off,łhe empty m rhe foce /s securelyscokhed.
A biocie of4 rooms /s tvorked,a200-ftpillar ofcoahs left, and then4more rooms are worked.
Thebbcks are removed onthe retreaf
Fig. 15—Gravity System or Jig in Operation
B ra k in g is applied to the rope by the extrem ely sim ple yet efficient raeans here shown. The speed of the incom ing an d outgoing cars m a y thus be controlled. Sprags in the wheels are also employed if the pitch is sufficiently steep to w a rra n t their use.
tric hoist placed directly in line with them but to the rise from the heading. From main p artin g s in head- ings, coal is hauled to a side track, and thence up the m ain hoistin g slope to the surface. Coal is undercut with machines in rooms off dips, but solid shooting is used fo r breaking down coal in all narrow work.
Longw all Min in g Practicedto Some Extent
There are some modifications of th is system , but they consist chiefly of semi-longwall operation. The applica- tion of th is system is the sam e a s th at later described a s applying to thick seam s steeply pitching. Where thin and thick beds are mined on medium pitches, the method used is the sam e as th at described fo r m easures of medium thickness except as to the handling of rock in the thin seam s and the depth of rooms in the thin and thick coals.
A t one mine in the Cahaba field, a longwall system of m ining has been practiced sińce 1906. T h is is em ployed in the Montevallo seam, a typical section of which w as shown in F ig . 1, Cocd Age, Oct. 9, page 474.
(T h is seam is of medium thickness and medium pitch.) T h is particular mine, F ig . 17, w as first developed through a slope on a room-and-pillar system , the rooms being cut together a fte r they were necked and driven up the pitch. T h is system w as continued until the slope had advanced about 2,400 ft. when the mine w as changed to the longwall system . A fte r the slope w as driven through the basin, which w as only 200 ft. wide, the bed began to slope upward on about a 12 deg.
pitch, and the w alls were advanced on the rise. E lec
tric h oists are used to puli the cars up the pitch. One m ain hoist raise s the em pties to a common point of dis- tribution, from which hoists located along the entries leadin g to the w alls puli the cars to the face and drop back the loads. These hoists are eąuipped with 27£-hp.
m otors and have a rope speed o f 400 ft. per minutę.
The w alls are 300 ft. in length and have been mined advancing. Experience has proved that if they are kept w ithin 30 to 50 ft. of each other, when the weight com es on it is eąualized between them. It h as also been found th at if the walls are kept 250 ft. part, the fa lls m ay be handled on each wali independently!
Thus, when the wali fa rth e st advanced ge ts a fali, it does not affect the coal through which the adjoin in g wali m ust be driven. The system o f advancing the walls
and the location of the h oists fo r handling the em pties are shown in F ig . 17. _
When the walls are driven to the rise, a break occu every 100 to 150 ft. unless a slip or cleavage line ap-
•p ears in the roof. T h is n aturally b rin g s on a break more ąuickly. Cover over this mine av erages 600 f t
Cribs are built along roadw ays and tim b ers are placed a s indicated in F ig . 18. T im bers are set on 4-ft. cen- ters staggered, with 2 ł by 4-in. strap s. These
are l i in. in diam eter fo r each linear foot of length and are left in place. I f the gob is inadequate, soft-wood cribs (usually of old tim ber or so ft pine) are built be- hind in staggered position and le ft in place to serve a s a cushion. The perform ance and condition of the roof determines whether or not the crib s m ust be b u ilt, where slips or cleavages occur, more crib s are required.
I f the roof has a tendency to fali m ore quickly than is normally the case, additional cribs m ust be built to counteract this feature.
D ouble R ow s o f C ribbing P r o te c t Roadw ays H eadings are advanced 100 ft. under the coal in the bottom, the m easure con sistin g o f altern ate coal, rash , and slate. The coal over the heading is then removed as the wali advances. The roadw ays are protected by cribs set in double rows. The conveyor used along these faces is of the shaker type. T h is is an E n g lish machinę, known a s the M avor & Coulson sh aker, o r the reciprocal longwall conveyor. I t is m ade in sections, each 9 ft. long, which are connected by eyelets and bolts. The m otor driving the conveyor is placed be-
Fig. 16—Modification of Mining Used on Medium Pitches A slope, an aircourse a n d a m a n w a y are d riven dow n the Ditch
™°nu . le ’e„vels are tu rn e d fro m the slope a t in tervals o f fro m 700 to 800 ft. Room -and-pillar panel m in in g w ith all w ide w ork paralle ling the heading s a n d a u x ilia ry slopes paralle lin ir th « m a in slope, is the system followed.
October 16, 1924 C O A L A G E 539
W- WallAdvomcmg H- Mafn Hoist L-WallHoisf
F ig. 17—Longwall Mine in the Cahaba Field
L o n g w a ll extraction has been follow ed in this oper- ation for eighteen years, altho ug h the m ine w as a t flrst developed on the room-and-pillar system. E lec
tric hoists are used underground for car distribution.
O peration is conducted advancing.
tween the rows of cribs and is connected to it by m eans o f a rope.
There h as been much discussion am ong engineers as to the proper place fo r connecting the driving mechan- ism to th is type o f shaker. A t this mine, experim ents to determ ine the proper location showed th at it w as more successful to drive the pan from the discharge end. The m ining m achinę cuts its k e rf in the rash directly over the bottom coal. Experience h as demon- strated th at it is m ost satisfacto ry under th is system o f m ining to make the length of cutterbar on the m a
chinę 1 ft. fo r every foot of height of coal. In other words, a 4-ft. bed would require a 4-ft. cutter bar.
Coal in th is mine is hard, w ithout any bu tts or faces.
With the system o f m ining described, it yields 67 per cent o f lump coal over 4 in. in size, 9 per cent of lłx 4 -in . egg, and 7 per cent of ł x l j- in . furn ace nut, or a total of 83 per cent of dom estic sizes.
A thick bed, known as the H enry Ellen or Mammoth,
Fig. 18— Details of Longwall Timbering
Props, three-piece sets a n d cribs are used to support the roof.
The cribs are chiefly ennployed however to ease the roo f down.
S h ak in g chutes are u tilize d to move the coal fro m the faces or w alls to the m ine cars. These are m o to r d riven the m otor being placed n e ar the discharge end.
in the Cahaba field, is shown in F ig s. 19 and 20, which illustrate the method employed in m ining steeply pitch- ing m easures. T h is seam is 11 ft. thick with an 18-in.
rash p artin g about the middle of the bed, and 3 to 4 in.
o f slate p artin g near the top. The pitch varies accord- ing to location along the outcrop and distance from the surface. The bed is steeper near the outcrop and flattens out somewhat as it n ears the m ain fau lts, or limestone m easures. The average pitch is about 26 deg. The seam is worked through a slope driven straigh t down the pitch with en tries or headin gs driven at about righ t angles thereto. F rom these rooms are turned straig h t up the pitch, as shown. In headings and airw ays, the coal is loaded directly into cars.
Chutes are used in the rooms and cars are loaded from them by opening the chute end gate. The c a rs are hauled to the sidetrack a t the slope by m ules and raised to the su rface by electric or steam hoists.
Y w w ///^ ft/7 ^ 7 7 ///^ 7 7 7 7 7 7 7 & ///////? /\ Rasn
Fig. 19—Working a Thick Steep Bed
This shows a cross-section th ro u g h a n a irw ay , a h e a d in g an d an ad vancin g room. The coal is here w orked in benches, the slate being gobbed in the room a n d retained by crib work. Chutes lined w ith sheet iron convey the coal fro m the face to the he a d in g where a car is loaded by s im ply ra is in g the chute end- or discharge-gate.
The coal is shot from the solid with perm issible explosives. C uttin g sh ots are placed in the center of the w orking face in the top bench of coal. Slab, or de
pendent shots, are placed a t in tervals of 3 to 4 ft.
each w ay tow ard the rib s. A fte r the top coal h as been shot down and loaded out, the middle p artin g of rock is removed with pick and shovel a fte r which the bottom bench is drilled and shot up w ith a few ligh t ch arges placed near the bottom of the bed. The top bench is carried 12 to 15 ft. in advance of the bottom bench in both headin gs and rooms. T h is bed g iv e s off a la rg e ąu an tity of methane a t the face of the coal, hence an efficient system o f ventilation is required.
V entilation is effected by m eans o f a m otor-driven exhaust fan connected to the a ir sh a ft by a duet fitted with explosion doors over the sh a ft. The a ir intake is through the slope and m anw ay and is conducted throughout the mine on a sp lit system , by m eans of overcasts, b ra ttices and regu lato rs, con structed of rock, concrete or wood, accordin g to the perm anency desired.
A andB = Method o f Secunng Wat!
CandD=Method o f ' Secunng High Top
\Cuł
i Coal
A i r w a g oFHeadtng Above
Lm eC uriain.
c p ?
rtoom Crosscu+s..
Z/rre Curtain Line Curiatn łoKeepHeodir
Headmg Cross cuts Cur tains'
A inyo y
'' Brattlćes Woodand Rock
F ig. 21—Semi-Longwall in a Steep, Thick Bed
Room -and-pillar m in in g w as flrst tried b u t w as n o t successful.
P a n e l lo n g w a ll faces were th e n opened, a lte rn a te panels being le ft in place, the slope a n d m a n w a y in a ll cases b ein g protected by he a vy p illars. T his system is m ore or less of a n experim ent a n d d ifficulty is feared w hen retreat on the panels le ft in place is attem pted.
DrawRock 3to4i'n
C oal 26 in.
Fig. 20— Plan of Entry and Rooms in Pitching Bed
T his also shows ho w the yario us w o rk in g places are ventilated.
A s gas in fa ir q u a n tity is freaue n tly encountered it is often necessary to b u ild line brattices or c urta in s in rooms or headings in order to th o ro u g h ly sweep the faces.
A t tim es, it is n ecessary to use a line b rattice or cur- tain from the la st open crosscut (see F ig . 2 0 ), to the face of the w orking place. E lectric cap lam ps are used in th is bed and the coal is brought down by “ shot fire rs” a fte r the men have le ft the mine. An average m iner will load out from 12 to 20 tons o f coal per sh ift.
In m edium -thick beds o f the th ird class, the differ- ence in m in ing method lies in room depth and in han
dling rock on en tries. There are no thin seam s o f th is c ja ss mined in the state.
A sem i-longw all method of m ining has been applied in a few cases to thick steeply pitching beds. F ig . 21 illu strates th is method. A slope w as driven on the seam which pitched 35 deg. but flattened in the lower w orkings to about 25 deg. On the first two entries, room s were turned up the pitch, the coal shot from the solid and loaded through chutes into 3-ton cars. T h is method w as not a success, fo r the coal w as alm ost completely sh attered by the solid shooting. Accord- ingly, a sem i-longw all system w as adopted. A section o f th is seam is shown in F ig . 22. E n trie s w ere turned
j] Roęk 4 tri.
v i
” I C oal 18 m.
Rock6t'n.
C oalSih.
F IG . 22
Section of Coal Bed
This is a section of the coal in the m ine shw on in F ig . 21. I t exhibits the p arting s characteristic of A la b a m a measures.
so as to provide w alls 200 ft. long.
A lternate panels are le ft solid with the idea o f advancing with one panel and retre atin g with the other.
The w alls are undercut, beneath the bottom rock, with chain m achines o f the longwall type fitted with a 54-ft. cutter bar.
These machines cut up the pitch.
Each cuts about 100 ft. o f face in approxim ately 2i to 3 hr. T his is about a s much as the men can
“ rock down” in a sh ift.
In addition to the regu lar ropes on the machinę, there is a safe ty rope by which it is lowered on the pitch a fte r cutting. T h is rope is attached to a carefully placed face jack and w inds around a drum on the re a r o f the m a
chinę; a friction mechanism attached to th is drum is operated
by the machinę runner. When cuttin g on a pitch over 25 deg. th is rope is kept taut, as a precaution in case the feed rope should break. On pitches o f 25 deg. or less, the undercuttings in the k e rf will hołd the machinę should the feed rope break.
A s the wali advances, ordinary mine tim b ers about 6 in. in diam eter are set about 4 or 5 ft. ap art. These are left in place until they begin to show w eight, when fo u r rows of large breakin g tim bers 10 in. in diam eter and larger, are set to w ithin 3 or 34 ft. of the face.
N ext all the sm aller tim bers are removed and a break follows. A fte r the first break, it is n ecessary to tim ber fo r additional falls, each tim e the face advances from 50 to 100 ft. On the lower entry of each wali, p illars 18 ft. wide and 25 ft. long w ith 10-ft. cro sscu ts are left to protect the entry. When the wali advances be- yond a crosscut, the chutes are curved into the la st one left open. The coal is loaded into the chute by the m iner and flows by g ra v ity into mine cars.
Table VII—Output per Man per Day, Tons
Average P ro du ctio n
Thickness of Coal, inches per M an , Tons
28-30 (m achinę m in ed ) ... 2.16 36 (m achinę m in ed ) ... 3.90 44 (m achinę m in ed ) ... 4.35 84 (solid shooting) ... 4.65 42 (steam shovel) ... 8.57
This system may, with conservatism , be said to be in an experim ental stage. The operator an ticip ates some difficulty while retre atin g on the altern ate panels.
It is planned to drive “ r a ise s” through these panels at a distance of 1,000 ft. apart. Then, if trouble de- velops while retreatin g, a wali will be advanced from a
“ raise” tow ard the face. T h is system is used on medium-thickness beds of medium pitch. Where the pitch is under 18 deg., the chute is replaced with a conveyor, which consists, in m ost cases of a chain traveling in a trough. The movement o f the chain is sufficient to b rin g the coal to the mine car on the entry.
A s an indication of the influence o f the thickness of bed on the average production per man, including com
pany men, Table V II is subm itted; these figures have been compiled by a large producing company and cover several m onths’ operation.
D D D
October 16, 1924 C O A L A G E 541
Conveyor That Facilitates Concentrated Mining
A d e ą u a t e T r a n s p o r t a t io n N e c e s s a r y t o O b ta in O u t p u t fr o m A n y M in e — F le x ib le S e c t io n a l C o n v e y o r M a k e s T h is P o s s ib le — A b ilit y Q u ic k ly to L e n g th e n o r S h o r te n S u c h a M a c h in ę I s a P r im a r y R e ą u i s i t e
By N. D. L e v i n
Colum bus, Ohio
T
r a n s p o r t a t i o n within the mine is one process in coal production th at causes much delay and loss to both mine owners and workmen.In many cases the men have to w ait h alf or more of th eir time fo r cars in which to load, when they would fa r rather be w orking and m aking money. With the ordinary room-and-pillar system no more than one or a t m ost two men can work in each room ; conse- ąuently a great number of rooms are reąuired in order to obtain the desired output. T his m eans a corre- spondingly larg e investm ent if the mine covers an extensive territory.
The Je ffrey M anufacturing Co., of Columbus, Ohio,
The rivets take no more stre ss than th at reąuired to hołd the chain togeth er; the sh ear is taken by the lugs on the side strap s. T h is is the stro n gest chain fo r its weight that h as yet been devised.
The single chain positioned in the center of the trough is easy to get at fo r connecting or disconnecting.
When it is desired. to add a section to the conveyor the procedure is as follow s: The chain is disconnected near the taił end of the conveyor, and laid out on the floor back of the conveyor, as shown in F ig . 3. The sections are held together by bolts or by pins, a s shown in F ig . 4.
There is a connection on both sid es a t each end o f
Fig. 1— Conveyor Taił Section Detached
P a rtic u la r atten tion should be directed to the type of ch a in employed. P la c in g lugs on the side links relieves the rivet or pin fro m the stress of p u llin g the chain.
Fig. 2— Details of Chain Construction
H ere the side links w ith their forged lugs readily can be seen as w ell as the grooved pins and the locking device. A ham m e r ls used fo r disconnecting the chain.
Fig. 3— Inserting a Conveyor Section
W h e n it is desired to lengthen the con- veyor the flrst step is the disconnection o f the chain. The loose end is next straight- ened out in line w ith the conveyor.
recently developed a type of conveyor th at m akes con
centrated m ining possible under many and varied conditions. One of these m achines and some of its applications are described in th is article. T h is con- veyor is so constructed th at it can be lengthened or shortened ąuickly. The stan dard sections are m ade 6 ft. long, a s th is is the av erage advance of an under- cuttin g machinę. If, fo r instance, the conveyor is used to take the coal aw ay from a “ shortw all loader”
th at m akes, say, one advance per hour, the machinę m ust be lengthened eight tim es in a sh ift.
It accordingly is evident th at each extension m ust be accomplished ąuickly and easily or otherw ise too much tim e would be lost, and the delay incurred would offset any advan tage derived from the use of the machinę. In design in g th is conveyor, therefore, asid e from reliability and the lowest possible cost, the ability to attach or detach a section ąuickly w as given first consideration.
It is evident th at it will reąu ire less tim e to uncouple one chain than tw o ; conseąuently th is conveyor w as made with a sin gle stran d o f chain. The coupling links shown in the accom panying illu stratio n s can be taken out or p u t in place in an instant.
The chain is built up o f fo rged side strap s, the sam e type a s is employed in coal-cutting m achines.
every section. The pin or bolt— whichever is used—
first is pulled o u t; then the taił section is draw n back 6 ft. In F ig . 5 two men are shown tak in g hołd of h is taił section to move it back. I t is ligh t enough so th at two men can easily carry it, or, if n ecessary, one m an can d rag it.
The lower trough or pan is put in place first, a f t e r which the upper trough is added. F ig . 6 shows a man in the act of pu ttin g the upper h a lf of the section in position. A fte r th is is done the fo u r pin s are pu t in place to hołd the conveyor together. N ext 12 ft. o f chain is added and coupled to place. All p a rts o f th e conveyor are light, so th at one m an can do the w ork if necessary, but two men can perform it easily.
The bottom o f the upper trough on which the coal rides is only 3 in. above the floor o f the mine, so th a t th is conveyor is extrem ely Iow. T h is is o f g re a t im por- tance when w orking in Iow coal. Another fe atu re o f the conveyor is th at it readily a d a p ts itse lf to rolling bottom.
F ig . 7 is a shop view o f one of th ese conveyors with 12-in. wooden blocking placed underneath a section joint. T h is m akes m ore of a sudden hump than would be encountered in a mine, yet the machinę will c a rry coal over th is obstruction.
F ig . 8 is a view of the conveyor taken from the d is-
Fig. 4— Disconnecting Taił Section
The ta ił or rear te rm in a l section m a y be disconnected b y with- d ra w in g the pins or bolts th a t jo in It to the conveyor proper, thus completely freeing it.
ch arge end. The size of the electrical eąuipm ent shown on the left is varied to su it the length o f the conveyor and the duty it will be called upon to perform . F ig . 9 is a view looking tow ard the disch arge end, and F ig . 10 shows the taił section by itself. T h is is the p art th at ordinarily is moved back when a stra ig h t section is to be added. On the right-hand side is shown a sm ali wheel, in the circum ference o f which rad ial holes b av e been drilled. These are used fo r slackening the chain when it is to be disconnected. A sligh t puli on a b a r inserted in one of these holes will give sufficient slack to couple or uncouple the chain ąuickly.
The conveyor is reversible, th is provision being n ecessary inasm uch a s no track is laid in the entries or room s where th is m achinę is used, and consequently tim ber and other m ateriał m ust be handled by the conveyor.
B y reference to F ig . 12 a good idea m ay be obtained
Fig. 6— Inserting a Straight Section
Top a n d bottom pans are moved separately, the b o tto m pa n being p u t in place flrst. E ith e r is lig h t enough as to be read ily handled by one m a n . This is a decided a d v a n ta g e in restricted m ine passages or where speed in m a k in g a change is essential.
of the way in which th is conveyor is used. A “ short- wall loader” is shown a t A. The sectional conveyor carries the coal from th is machinę and d isch arg es it a t the point B, either into cars or onto a conveyor on the lateral entry as shown. A t the face C is a “ conveyor loader” which disch arges into another sectional con- veyor at D. T h is latter conveyor carrie s the coal to the point E. The driving units fo r these conveyors are located a t B and E respectively. E ach tim e the face C is loaded out, the conveyor is shortened a t D.
The sections removed are loaded out on the conveyor to E, tran sferred to the conveyor serv in g the “ shortw all loader” and are used fo r adding on to th is conveyor at the point A.
When the shortw all loader has driven through to the next lateral entry a t the point K, the conveyor is not taken out, but is left in place. The head and taił ends are removed and their positions reversed. T hus the
F IG . 5
Moving Taił Section Back
L ig htn e ss is an essential character- istic of a n y porta- ble conveyor. The ta ił section of th is m a c h in ę is o f such s m a li w e ig h t th a t tw o m en can easily carry it or one m a n can d ra g it a lo n g the m ine floor. As m a y be seen in t h i s illu stra tio n , h a n d h o 1 d s are provided to facili- tate m o v in g this section. L ittle tim e is consum ed in le ng th en in g t h i s conyeyor.
October 16, 1924 C O A L A G E 543
F IG . 7
Uneven Floor Is No Obstacle
H u m p s a n d hollows m a k e little difference to this conveyor as it is suffl- ciently flexible to s u r m o u n t them . A jo in t is here supported on two 6x6-in.
blocks.
end that w as n earest to the “ shortwall loader” is placed at B and the driving or disch arge end is put a t the point K. When the face C h as advanced to the point E, the conveyor is ready to receive the coal from this face and tran sp o rt it to the point K. The sam e type
Fig. 10— Taił Section of Conveyor
The ta ił sha ft is provided w ith an overhungr disk w ith holes drilled rad ially in its circumference. This affords enough slack.
to perm it of coupling or un co uplin g the Chain.
narrow, usin g a “ shortw all loader” d isch argin g to a sectional conveyor. When the rooms have been driven to their fuli depth slabbin g cuts are m ade by m in ing machines and the coal loaded into the sectional conveyor.
In F ig . 11 is shown a room being driven 10 ft. wide with a shortwall loader, A. B is a sectional conveyor.
To the righ t is shown a room th at h as been driven to its fuli depth. A shortw all machinę is shown a t C m aking a slabbing cut. D is the sectional conveyor th at took the coal aw ay from the shortw all loader when the narrow room w as being driven and is now in position to be used fo r takin g aw ay coal m ade by the slabbin g cut. £ is a conveyor installed on the entry and em-
Fig. 8— Yiew as Seen from Head End
The m o to r an d drivingr m achinery are w ell incased. The power o f the m otor m a y be varied to su it the w ork to be done or the w eight of coal to be transported.
of conveyor, i f desired, can be used along the face C in stead o f the “ conveyor loader,” the coal being loaded into it by hand. T h is latter method reąu ires puttin g enough men along the face to load out a cut in one sh ift.
In m ines w here it is desirable to m ain tain the pres- ent room -and-pillar system the room s m ay be driven
F IG . 9
Looking Toward the
Head End
A lth o u g h the bottom plate of the coal p a n is only 3 in. above the floor, m a k in g the Oomplete conveyor Iow, its ca p a c ity is large, as m a y be ju d g e d fro m th is view.
Fig. 11— Room Driving and Pillar Slabbing
The rooms are driven n a rro w a n d th en w idened o u t b y slab b in g cuts taken off the p illa r ribs. C ars are loaded in trip s on the heading, w here unless grades are favo rab le each locom otiye rem ains w ith its trip , successively s po ttin g the cars u n til th e entire trip is loaded.
ployed in g ath erin g coal from several room s and d isch argin g it into a trip of c ars at F. T h is conveyor m ay be extended to the n earest entry if desired.
M any different sy stem s of m ining by m echanical m eans are being contemplated a t the present tim e, and it is believed th at th is sectional conveyor will find a place in practically all of them. A sav in g will be afforded by its use because of the com paratively large ąu an tity o f coal th at can be taken from a territo ry of given size. T h is will resu lt in a lower cost of mine upkeep. No track is reąuired where the conveyor is employed, and it is not necessary to take up bottom, shoot down top or remove rock in the en tries in order to make room fo r cars.
Alberta Experiments in Making Briquets From Coal Dust Hitherto Wasted
In the fourth annual report of the Scientific and In d u strial R esearch Council of the Provińce of A lberta is found a detailed account of experim ents in the manu- fa ctu re of b riąu ets from the fine coal dust usually w asted in the production of coal in A lberta. T his work has been carried on at the U n iversity of A lberta sińce December, 1922, and P ro f. E d g a r Stansfield, sec- re ta ry of the Council, in describin g it and in outlining the conclusions reached sa y s:
“ In m aking b riąu ets the coal is crushed to a suitable size, i f dust is not used. A batch is then weighed out, tra n sferre d to the m ixer, and heated. U sually, in our te st plant, 18 lb. o f coal is handled in one run.
T he binder also is weighed out, melted and poured into the m ixer, and the tem perature and m oisture con- tent of the m ixture regulated as required. U sually two or three m inutes is found to be sufficient tim e to com- plete the m ixing, but th is v aries with the tem perature and therefore with th e fluidity of the mix.
“ F ro m the m ixer the batch is tra n sferre d to a fluxer, from which it is allowed to run into the feed hopper of the press. A s the rear plunger is drawn back, some o f the m ateriał in the hopper fa lls into the die box.
H ere it is caught, sąueezed between the two plungers, and finally ejected from the die box by the rear plunger, which has a longer travel than the fro n t one and m akes only h alf a s m any strok es per m inutę. The b riąu ets fali onto a m oving belt, are disch arged at the fron t, collected in a box, and tested.
Tw e n t y-five Briquets Made Per Min utę
“ The p ress m akes about twenty-five b riąu ets per m in
utę. T h eir size can be controlled by a regulation of the feed, but they usually w ere m ade to w eigh about 4 oz.
“ The b riąu ets are classified by inspection, by th eir specific grav ity , by drop test, and by rattler test. Of these, the specific-gravity and the rattle r te st seem to be the m ost satisfacto ry . Com parison of b riąu ets m ade from the sam e coal with the sam e binder show th at the ąu ality of the b riąu et in creases w ith the specific g rav ity .
“ In the drop test, six briąu ets are given a 10-ft.
drop onto a concrete floor, and the b reak age deter- m ined. In the ra ttle r te st tw enty b riąu ets are placed in a Container, which is revolved 200 tim es a t 32 r.p.m.
T he m ateriał rubbed off the b riąu ets a s they revolve is then w eighed, and the percen tage determ ined.
“ T e sts were m ade to determ ine the best siz in g of
the coal, best tem perature fo r m ixing, m inim um tim e reąuired fo r m ixing, best tem perature fo r p ressin g , also the effect of the addition of steam to the m ix, and changes of p ressu re in the press.
Soft Coal-Tar Pitch Used in Test Work
“ S o ft coal-tar pitch w as used fo r m ost o f these te sts fo r the sake of uniform ity and because it is in some ways the easiest binder to use fo r te st work. Com- parative tests w ere m ade with other binders. While we are not prepared a t present to tabulate fu li resu lts of our experim ents, certain broad conclusions m ay be mentioned.
“ The ąuantity o f binder reąuired v a ries with the type of coal. Thus, a carbonized lign ite reąu ires fro m two to three tim es as much as a coking bitum inous coal.
“ The higher the tem perature, the less tim e reąu ired fo r m ixing.
“ Although blowing steam through the m ix h as ad- vantages and is generally employed in com m ercial w ork a better briąuet generally can be m ade under laboratory conditions without steam .
“ Increase of tem perature a t the p re ss resu lts in in- crease of density of the briąuet, but a lim it is placed upon the tem perature by the in creasin g tendency to stick to the plunger and by the fria b ility of a hot briąuet as it leaves the press. The tendency to stick to the plunger can be reduced by steam .
Size of Particles Affects Qu a lit y of Briquet
“ Increase of p ressu re n aturally in creases the density of the product, but a larg e in crease in p ressu re is reąuired fo r a sm ali in crease in density.
“ The effect of the size o f particles in the crushed coal used on the ąu ality of the b riąu et m ade probably is fa r less in a coking bitum inous coal than it is w ith either anthracite or carbonized lign ite. I f the p a r ticles are too larg e or larg e particles are presen t in too great ąuan tity, the b riąu et is coarse and friab le.
F in e r crushing gives a sm oother and more shiny b ri
ąuet, but excessive dust in creases the am ount o f binder reąuired.
“ The departm ent does not intend to continue the m anufacture o f b riąu ets th is autum n,” concluded Pro-
•fessor Stansfield, “ but m ore attention will be paid to suitable binders fo r the variou s g rad e s of coal.
Whether our resu lts will form a b a sis o f a fu tu rę in- dustry fo r northern A lberta depends on so m any fac- to rs th at we can say nothing about it. We are concerned only w ith the scientific side o f the problem and not its com m ercial application.”
Fig. 12— Concentrated Mining by Conveyors
B o th heading d riv in g a n d p illa r w ith d r a w a l are here shown.
The method is thus rap id and the o u tp u t large. C ars are loaded a t a single po in t on a heading not show n in th is d ra w in g . U nless grades are layorable the locomotive does n o t uncouple fro m the tr p.
