C oal A ge
McGr a w- Hil l D e v o t e d to th e O p e r a tin g , T e c h n ic a l a n d
P u b l i s h i n g C o m p a n y , I n c . n ■ n l i r .1
t v X* r- o j B u s in e s s P r o b le m s o f th e w „
J a m e s H . M c G r a w , P resid en t _ ‘ J o h n M . C a r m o d y
E . J . M e h r e n , V ice-P resident C o a l M i n i n g I n d u s t r y E d ito r
V o lu m e 3 2 N e w Y o r k , A u g u s t , 1 9 2 7 P lu m b e r 2
A n Approach to
A
G E N E R A T I O N ago when Carnegie, Frick and Phipps were laying the foundations o f their success and their fortunes, the iron and steel business was more disor
gan ized than even its worst critics would claim fo r coal today. Out o f the bitterest competition American industry has known birth w as given to the U n ited States Steel Corporation. Im m ediately there began to develop a degree o f order that not only revitalized the industry but led to the rehabilitation o f old plants and the creation o f new ones. In less than ten years after the corporation was formed the great Gary steel plants were begun and built out o f earnings.
M
E N w hose industrial life coincides with that period recall what an influence the fam ous Gary dinners had on this entire developm ent. N o member o f the informal group controlled as much as fifty per cent o f the country’s production, yet the vision o f the leaders brought a degree o f stability previously unknown in the industry. Guided by sound legal advice they worked out their marketing problems within the law. N o where else has there been maintained so intelligently a balance between production and consumption. T h is has meant stability and order. It has led to investment security.
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H R O U G H it all, small business has prospered. E ven in periods o f slow demand when the temptation to get all theSTABILITY
business going must have been strong, heads were kept cool and prices maintained at a live and let-live level. M a n y times a price war would have eliminated small com peti
tors. A wiser policy prevailed. In the end they all prospered. U n d e r the leadership o f the U n ited States Steel Corporation, not only have plant and equipment been kept abreast o f modern scientific enterprise, but provisions for safety and housing have advanced rapidly. A hazardous industry has been made com paratively safe. H o u s in g facilities for employees, unknown a genera
tion ago, have been provided in scores o f communities. M o d er n cities o f from 5 ,0 0 0 to 6 0 ,0 0 0 inhabitants have risen about steel mills. Pension systems and stock ownership plans have been d evelop ed and fostered.
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H E R E is som ething in this story for the coal industry to think about. W i t h out coal not one ton o f steel can be made.Coal is the life blood o f industry. It should share in every w ave o f prosperity. W h y does it not do so? W h y is coal so frequently sold w ithout profit to those w h o own it, or mine it, or sell it? It is fo r those w ho do it to answer to themselves and to others in the industry w h o suffer because o f this practice.
Obviously, scattered effort by too many small units cannot save the industry. It has been tried for years. O rganization and co-opera
tion have shown the way in other industries.
W h y not in the coal industry?
T h e A rt is t Fi nd s R o m a n c e in th e P re p a ra ti o n of C o a l
DISPATCHING Results
A t Nemacolin
IV. H. Gates
S u p e rin te n d en t, N e m a c o lin M in e, B u c k e y e C oal Co., N em a co lin , Pa.
Alphonse F. Brosky
A sso c ia te E d ito r , C oal A g e
cipal flat entries from w hich room entries are tu rn ed . W ith in a radius of about i/2 m ile of the hoisting sh aft, w here traffic congestion w ould be m ost likely to occur, g rad e crossings are elim inated and b ridge crossings used. W h e re track s cross each o th er on grade, N achod autom atic block signals show ing red, orange and green lights are installed. A s already indicated, all haulage is regulated by a dispatcher th ro u g h an elaborate telephone system .
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H E R E is 'no job req u irin g m ore constant and alert application to d u ty at N em acolin th an th a t o f this dispatcher. Since loaded and em pty trip s fo r the m ost p a rt travel over individual tracks, g ettin g the trip s to and fro m the side track s generally occasions him little w orry. I t is the proper p ro -ratin g of available em pties betw een various sections of th e m ine, in o rd er th a t progress in the cleanup m ay be kept as nearly u n ifo rm as possible, th a t taxes his re so u rcefu l
ness. H e has no control of the speed w ith w hich cars at the faces a re m ade ready fo r the re tu rn trip to the sh aft bottom . T h a t responsibility rests en tirely w ith the forem an and his as
sistants. B ut he is given the responsi
bility of prom ptly replaciflg loads w ith em pties. E quitable d istribution of em pties in this m ine is vitally / necessary because the m in er is e x pected to clean up his place every day.
S tatem ent o f the fact th a t m ine car distribution is m ore o r less flexible is not intended to im ply th a t locom o
tives do not operate on schedule, fo r they do, so fa r as is possible. D elays due to various causes are bound to occur. T hese tend to th ro w the en
tire tran sp o rtatio n system off balance, in w hich condition it w ould stay, w ere it not fo r the d ispatcher’s skill in ad ju stin g it to every change.
Scheduling o f trip s is, and can be
V
I S I T O R S a t the N em acolin m ine generally like to linger a bit in the underg ro u n d office of the tra n sp o rtatio n dispatcher. H e re they see a w ide-aw ake young m an equipped w ith the p arap h ern alia of a telephone operator, seated at a desk, to the le ft of w hich, w ithin convenient reach, is a sw itchboard. H e is all business. S pread out before him is a dispatching sheet on which he en ters penciled figures w ith his rig h t hand, and at intervals plugs, w ith his le ft hand, connections on the sw itchboard w ith one or an o th er of 61 underg ro u n d telephones, while he listens o r talks to som eone at the o th e r end o f the line.
M ost visitors express astonishm ent at the d isp atch er’s com m and of ac
cu rate in fo rm atio n reg ard in g the lo
cation and m ovem ent of every loco
m otive, to g eth er w ith the num ber o f em pties and loads a t various points in the mine. In this he is aided by the tabulated record on the sheet be
fo re him , w hich he keeps balanced up to the m inute fo r ready reference.
T h ey m arvel a t the speed w ith which he decides questions o f dispatching strategy. S tan d in g in the door-w ay they m ay have heard one side o f a telephone conversation sim ilar to the fo llo w in g :
“ W ell! N inety-one? Y es sir!
B oth finished. [P au se.] W hy, N inety-one has been gone 15 m in
utes. N in ety has been gone 50 m inutes.”
I
N T E R P R E T E D , this conversation is an an sw er to an assistan t fo re m an who telephoned as to the w hereabouts o f tw o g ath erin g locom otives assigned to his section. T h e d is
patcher told him these locom otives had finished up fo r the day, and e x actly w hen they had ceased hauling.
A gain, v isito rs m ay have heard th i s :
“ H ello ! N o, n o t yet, A n d y ! N o m ore trip s today. W h a t? [T h e dispatcher pauses and figures up.]
Coal 180 and slate 17. [H e pauses again as if listening and figures w ith
"H e llo ! N in e ty -O n e I s D ue in 11 M in u tes.”
lightning-like speed.] D elivered 214 em pties today.”
A ndy, an assistant forem an, w anted to know the record of his section fo r the day and w as enlight
ened thereon before he had hung up the receiver.
T h e dispatcher neither w astes breath nor minces w ords. H e gives o ut inform ation and issues ord ers in few w ords w ith staccato accent. H e m ust function w ith deliberation fo r the sake of accuracy, and yet w ith speed because individuals other than the m an to whom he is talking m ight be w aiting to com m unicate w ith him.
H e is compelled to clear his lines prom ptly not only in preparation fo r the next incom ing call but also to allow him self tim e fo r balancing the figures entered on the sheet d u rin g his last call.
N em acolin m ine is in a large tra c t of P ittsb u rg h seam coal, 96 in. thick, and is now producing about 6,000 tons a t day by a concentrated block system of m ining. T he practice is to req u ire each m iner to clean up his face every d a y ., Practically the en
tire length of the main haulw ay is double-tracked, as are also the prin-
65
66 C O A L A G E — V ol.32, N o .2 considered, positive only in so fa r as
it re fe rs to the tim e o f travel from station to station under norm al con
ditions. T h ere are too m any vari
ables, at least under present system s o f m ining, to perm it of precise dis
patching. All men do not w ork at the same rate, neither does any one m an labor u niform ly throughout the hours of the day, nor do conditions rem ain the same fo r any appreciable period. T h is being so, it is a fa r fetched notion to expect in a dis
patcher a m an who will function as a m achine by follow ing exact stan d ard s o r schedules. C onditions affect
ing his job are ever changing, ju st as the mine m ap changes.
E
X C E P T IO N , pointing to the p re cision o f railroad dispatching, m ight be taken to this argum ent. T he rebuttal is clearly t h i s : O n railroads the tim e allowed fo r the m aking up of train s is not standardized. I t varies between wide lim its as does also the tim e required fo r gathering and m aking up a trip of m ine cars. T h ere is, however, a m arked difference between railroad and mine tran sp o rtatio n , fo r instance, in the length of the re spective hauls. In the fo rm er the tim e du rin g which rolling stock is in use fo r the tran sp o rtatio n of a given cargo is generally so g reat th at an appreciable variation in the tim e of m ake-up is largely absorbed and con
sequently not nearly so outstanding as in m ine transportation.
A few im portant points o f attack in w orking out a successful system of dispatching a re : F irst, to safeguard against causes fo r avoidable delays;
second, to establish lim ited s ta n d a rd s ; third, to choose fo r the dispatching jo b a quick-thinking m an who possesses the fu rth e r qualifications of a retentive m ind, vision and fam iliarity w ith the m ine w orkings and the jobs of the m en he serves.
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H E »dispatcher a t N em acolin is a certificated m an who has served in m any capacities above and below ground. H e th erefo re know s why certain delays occur and how best to m eet emergencies. I n other w ords, he can intelligently p u t him self in the other fellow ’s shoes. A m an should be trained in o ther branches o f mine operation before he goes into tra in ing as a dispatcher. T he duties on this job should n o t fo r a m om ent be considered as being those of a clerk, fo r a dispatcher in his field m ust display as m uch resourcefulness as m ust a mine forem an. C ertainly he has m ore decisions to make. T h e degree
of success in dispatching achieved by a coal com pany is largely dependent upon the type o f m an chosen to reg u late it.
A dispatcher m ight well be given an o p p o rtu n ity a t intervals to visit all sections o f the m ine and th u s ac
quaint him self w ith the changes in conditions w hich a re constantly tak ing place. T h is thought is based on the belief th a t the m ore fam iliar a dispatcher is w ith w hat is going on
W H Y D I S P A T C H I N G ? D is p a tc h in g d o e s m o re th a n e x p e d ite h a u la g e a n d w o r k a t t h e fa c e . I t m e a n s k e e p in g s u c h c lo se ta b o n s c h e d u le s a n d p e r f o r m a n c e t h a t “b u c k - p a s s in g ” is e a s ily d is c e r n e d a n d so o n e lim in a te d . D is p a tc h in g s p o ts w e a k n e s s e s in o p e r a tio n a n d b r in g s th e m in to s u c h p r o m in e n c e t h a t t h e i r re m o v a l is in e v ita b le .
back a t the face the m ore intelli
gently will he handle his job.
A qualification he cannot be w ith out is ability to handle m en. H e m ust be diplom atic and m ust com m and th eir respect. H e cannot suc
ceed in this unless he is patien t and cool-headed. T h e telephone brings him in close contact w ith the bosses and indirectly w ith the m iners, the level of whose earnings it is w ithin his pow er to elevate. It is non
sensical to say th a t the average m iner will load so m uch coal and no m ore.
Give him m ore cars and his p ro ductivity autom atically will be in
creased up to a point considerably h igher than th a t generally th o u g h t to be the lim it. T h e m iner is disposed to suffer, th ough reluctantly, a tem po
ra ry curtailm ent o f high w age-rate w ork, as th ro u g h the handling of draw slate, but he will n o t tolerate long periods o f idleness w aiting fo r
S ig n a ls? Y e s !
cars. W ith this as a reason, he is justified in picking up his d in n er pail and sta rtin g fo r th e outside. A rem edy fo r this situation is the em ploy
m ent of a dispatcher.
A t the N em acolin m ine a t the close o f a sh ift, m an trip s are m ade up by the dispatcher. C rew s on gath erin g locom otives are in stru cted to haul back to the sh aft, on th eir w ay to the m otor barn, as m any em pty cars as are needed to accom m odate those m iners who have cleaned up th eir w ork and are ready to s ta rt fo r the outside. T h e m iners look fo rw ard to this service and do w hat they can to facilitate it. F re q u e n tly a m iner will w alk to a sidetrack, his w ork com pleted, and in fo rm the dispatcher either directly o r th ro u g h the side
track a tten d an t as to how m any men in the vicinity of his place will have cleaned up th e ir places by a certain tim e, and ask w hen a m an trip will be ready.
H e re again, the success of a plan hinges on the dispatcher. I f his ju d g m en t is good and he m anages to provide a sufficient num ber o f em pties fo r the purpose, o r e x erts him self to accom m odate the m iners in this w ay, he w ins praise n o t only fo r him self bu t fo r the com pany as well.
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H E R E are o th er w ays in which the dispatcher m ay function to establish a closer u n d erstan d in g betw een the m in er and th e m anagem ent.
A t the N em acolin p lan t th e dispatcher is charged w ith the du ty o f directing the d istribution of requisitioned sup
plies. A t the close o f each sh ift the assistan t bosses m ake out requisitions fo r supplies needed in th e ir respective sections. T h ey leave a copy of the requisition w ith the dispatcher and give the original to the m ine forem an who, a fte r acting on it, hands it to the yard m aster. T h e dispatcher needs this in fo rm atio n fo r m aking out his estim ate of cars fo r the n ex t day. T h e follow ing d ay the supplies are loaded into cars w hich are grouped, fo r g reatest convenience in handling, w ith em pty-car trip s and then low ered dow n the slope to the supply track. T h e slope-bottom a t
ten d an t borrow s fro m the dispatcher the copies of the requisitions and checks them ag ain st the supplies loaded. T h e n he re tu rn s them to the dispatcher in the sam e o rd e r as th at of the supply cars. I t is then up to the dispatcher to see th a t the supply cars a re correctly routed.
D u rin g his visit to N em acolin the e d ito r talked to a m iner of foreign b irth w ho had started w ork there only
A u g u st, 1 9 2 7— C O A L A G E 67 a few days before. A sked how he
liked the plant, the m iner said, “ F in e ! N ever catch-em place like th is before.
Las n ight I tell-em boss I need post and ties. T o d ay I get-em on job.
Son-uv-a-gun ! A nd lotsa cars, too ! Boss he tell me not to m ake pig of self cause I got-em plenty cars. H e tell me to w ork fa ste r slow. I u n d e r
stand. H e w ant me to get use to dif- fren w ay and n o t kill self a t s ta rt.”
T hen, w ith a pleased g rin on his face, he added these w ords w ith accelera
tion : “ B ut I w ork lika hell, anyw ay, you b e t!”
T he average distance from the sh aft bottom o f the sidetracks now in use a t N em acolin is about 1.9 miles. T h e longest haul is 2 l/ 2 and the sh o rtest is 1J4 miles. In the te rrito ry w ithin a 2-mile radius o f the sh a ft bottom the com pany has found it economical to m ake sidetracks small and num erous, establishing them as close to the faces as possible.
Coal is gath ered by 24 locomotives, m ost of w hich are 9-ton cable- reel units provided w ith perm issible features, the rem aining units being of the storage b attery type. T h e av er
age d ay ’s w ork p e r g a th e rin g u n it is 85 cars o r about 250 tons, since the cars used hold 3 tons each. Seven 13-ton locom otives are used to haul the coal from th e sidetracks to the sh aft bottom .
B
E Y O N D the 2-m ile lim it the comp any believes it is desirable to es
tablish larg e interm ediate sidetracks of p erm an en t construction, relaying trip s from the tem p o rary sidetracks at the face to the p erm anent side
tracks by single 13-ton locomotives and from the p erm anent sidetracks to the sh a ft bottom by tw o 13-ton loco
m otives in tandem .
T h e re a re 1,200 m ine cars in serv ice in this mine. W ith o u t the dis
patching system it is calculated th a t between 1,800 and 2,000 cars would be req u ired fo r the p resen t p roduc
tion. E ach d ay a reserve of 600 to 800 loads is provided an d le ft stan d ing on the sh a ft bottom and au x iliary storage track s fo r skip operation d u r
ing the early h o u rs o f the follow ing day. I f 800 loads are le ft over, only 400 cars are available fo r o th er use.
A n allowance o f about 125 cars is re quired fo r slate, supplies and fo r those th a t are shopped, leaving 275 em pties fo r the first tu rn in the m orning. T hese em pties, of course, are placed p rio r to the beginning of the day sh ift, and an y surplus is placed on the sidetracks.
Going in on the first trip in the
m orning, the m ain-line locomotives haul a m an trip m ade up of em pties tu rn ed loose from slate and supply service d u rin g the night. O n the re
tu rn trip these locomotives pick up at the au x iliary storage tracks w hat
B ridged Crossing S a ves T im e, P reve n ts Collisions
loads are le ft on them from the day before.
O n the first m orning trip in, the g ath erin g locom otives travel light.
B efo re the m iners are ready fo r a second car adequate cars have been dum ped and placed on the side tracks to m eet th eir needs. G enerally the sh aft bottom is cleared of standing coal w ithin 2 y2 hours of the start.
A dispatcher is on du ty d u rin g the night as well as d u rin g the day. Since traffic is light d u rin g the night, the duties o f the dispatcher serving a t this tim e are m ore like those o f a telephone operator.
T h e dispatcher uses a daily esti
m ate of the em pties each section will need fo r determ ining w hen and w here, and also how m any, cars should be distributed a t various in te r
vals d u rin g the day. A prelim inary estim ate is subm itted to the d is
p atcher by the firebosses who m ake it up a fte r checking in the w orkers on th e ir respective sections. T he section bosses subm it a final estim ate upon com pleting their first m orning inspec
tion of the w orking places. W ith the dispatching sheet before him, the d is
patcher know s at all tim es how near a section is to clean up and regulates distribution of em pties accordingly.
H is m a jo r objective is to have all sec
tions of the mine cleaned up a t a p p roxim ately the sam e tim e. W h en a certain section falls behind its rate of production, he sends e x tra em pties to the side track s serving it until it is caught up. T o do this he m ay have
to curtail the car supply to sections on o r ahead of schedule. O rd in arily , he tries to m aintain a t all tim es a re serve o f i y 2 em pties fo r each m iner, either on the side track or in trip s in m otion.
M
A I N - L I N E traffic is closely regulated by the dispatcher. A block signal and a telephone are in stalled a t every im p o rtan t intersection.T h e crew s on m ain-line locom otives move from station to station u nder telephone orders. U n d e r this arra n g e m ent the dispatcher is in position to g ra n t p rio rity o f m ovem ent to trip s plying to a section th a t has fallen be
hind its production schedule. It also enables him to re-ro u te trip s in case of a fall o r w reck, perhaps bypassing em pties by w ay of a load track , o r loads over an em pty track . F u rth e r, he is in position quickly to clear any
• tra ck in case o f an em ergency.
W h ere the w orking places are e x tensive o r the faces are advanced fa r from the m ine opening and a con
siderable tonnage is being gotten or anticipated, im m ediate attention should be focused on dispatching of tran sp o rtatio n as a m eans o f increas
ing efficiency. Suffice it to say, dis
patching has trem endous possibilities fo r bringing about b etter regulation o f haulage. Com panies th at have m ade it a general practice, and others w ho are try in g it out, realize w hat can be expected of it.
A t N em acolin it has assisted m a
terially in the effecting of a substan
tial increase in the average daily o u t
p u t p er loader. Sim ultaneously, it has bettered the general efficiency of the plant. A lso it has kept low the num ber of rolling-stock units in the face o f increasing production. O ne of its m ost po ten t influences is the m an n er in w hich it serves to bare w eak spots in operation. D ispatching also serves an o th er p u rp o se in th a t it elim inates “ buck-passing” by defi
nitely allocating responsibility.
M
U C H thought is being given to the dispatching o f o ther allied phases of operation. A s dispatching th u s fa r has been confined to haulage, the practical lim its an d n a tu re o f its application to face jobs have not yet been determ ined. T o all appearances, dispatching o f face jobs possesses possibilities as w ide o r w id er th an those in h eren t in d ispatching o f h au lage, and developm ent o f a technique suited to its requirem ents is assured fo r the fu tu re. F irs t of all, how ever, dispatching o f haulage m u st be m astered.
Longwall with Conveyors
Gives 20 Cent More Lump
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H O U G H tim ber costs a re high, the com pensation of a better p roduct m akes longwall advantageous at M ine No. 153 of the C on
solidation Coal Co., V an L ear, Ky.,- w here a 1,000-ft. longwall face has been in operation fo r about a year.
A s shown by F ig. 1, this long face is laid out in 250x750-ft. blocks. It w as originally started as an advancing wall, but this plan fo r various reasons was abandoned. T h e five single en tries w ere then driven th rough the block, and the w ork proceeded on the retreat.
T h e M iller C reek o r No. 1 seam, which is th a t w orked in this mine, ranges in thickness from 34 to 44 in., the thicker coal being present in the local dips only. T h e im m ediate roof is a h ard gray shale o r slate, and above this is a heavy bed of sand
stone, the thickness o f g ra y slate ranging from 2 to 20 ft. and the total thickness o f overburden from 240 to 430 ft.
T he coal is free from im purities and has pronounced planes of cleav
age alm ost parallel to the long face.
T he coal is structurally strong and resists crushing to a rem arkable degree.
Serving this 1,000-ft. face are fo u r shaking or jigging conveyors, driven by an equal num ber of 15-hp. electric m otors. T h e conveyors discharge the
J. C. A b ra m
coal into the mine cars a t entries No.
1, 3, 4, and 5 (F ig . 1 ).
Because the seam is thin, 30 in. of bottom rock had to be lifted on these fo u r entries in o rd er to place the mine car low enough to receive the dis
charge of the conveyors, and also to provide headroom fo r the trolley lo
comotives. T h e entries w ere driven 22 ft. wide. B ottom rock w as taken 10 ft. in w idth, leaving a bench on either side, this berm being used for tim ber storage and giving room in w hich the longwall m achines can cut out.
A s indicated in F ig. 2, cribs and props are used as a m eans o f roof
r i g . 1— L ongw all S y s te m at V an Lear, K y .
By J. C. Abram
S u p e rin te n d en t and M in in g E n g in e e r H o o v er sv ille Coal Co.
H o o v er sv ille, Pa.
control. T h e crib tim ber is round and 2 ft. long. Lines of cribs and props are placed alternately parallel to the long face. T h e cribs are set in th eir row s on 10-ft. centers, and a round prop is placed betw een adjacent cribs. T h e lines of props are set on 3 j/2-ft. centers, 5 ft. behind the cen
te r line of the crib row s. W h e n all coal has been loaded into the con
veyor, a line of props or cribs is placed w ithin 3 ft. of the solid coal, leaving sufficient clearance fo r the longwall m ining m achine to m ake its undercut.
F o u r longwall m achines are used to serve the 1,000-ft- face. T h e cu tter b ar is long enough to give an average 5-ft. undercut. T h e conveyor line, having pans 10 and 12 ft. long, is placed behind the line props o r cribs as indicated in F ig. 3, center B.
U p to the present, no attem pt has been m ade to recover crib o r prop tim ber. A bout 90 p er cent of the props at D , Fig. 3, w ere either crushed o r broken w hen the conveyor w as m oved from betw een C and D to B . H eavy p ressu re upon cribs a t C, Fig. 3, rendered th e recovery of these alm ost im possible by the tim e the new line of cribs had been placed.
Conveyor m ovem ent w as accom plished by unbolting the individual sections and m oving them to a new location. T h e conveyor w as advanced and the long face u n d ercu t by long
wall m achines at night, the ro o f be
ing tim bered and the coal loaded by a day crew.
Provision w as m ade fo r the sto r
age of em pty cars by placing a solid line o f cribbing along both sides of the entries ex ten d in g back into the goaf. F ro m 10 to 18 cars, averaging 1.7 tons o f coal, w ere hauled p er trip.
By leaving the crib tim b er the ro o f w as protected. A s only fo u r m a jo r breaks w ere observed in a period o f 68
A u g u st, 1927 — C O A L A G E 69
. t7 lo tercuf_S'c/eef__
Conveyor-..
o [ p D j i p o D o O o D o D o
■
o i> o o d > d > o o o o o o o o o o
K " 7 '- - H M 3 ’S ,«r
Fig. 2— Face T im bering and T racks
th ree m onths in close p ro x im ity to the long face, it m ay be assum ed th at the non-recovery o f cribs caused the settlem ent to occur slowly, keeping a continuous o r traveling w eight upon the coal, th u s reducing the labor of m ining, and p e rm ittin g the coal to be taken dow n w ithout blasting.
S ix ty p er cent of all coal from this long face passed over a 5-in. screen.
N o g reat difficulty has been ex p e ri
enced in keeping the space open be
tw een the face of the coal and the conveyors. (S e e F ig. 3 ) . B reaks in the im m ediate ro o f occur w ith every cut, b u t are of a shallow n a tu re and easily supported by the cribs and props. A f te r each m a jo r break in close pro x im ity to the face, it was observed th a t the labor of m ining or tak in g dow n the coal w as m uch m ore difficult. O th e r m a jo r breaks in the upper strata, th an these fo u r m en
tioned, have occurred so fa r back in
Fig. 3— Cross Section at Face
T
the goaf as to have no apparent e f fect at the long face.
T o the n o rth of the present w ork
ing, a 1,800-ft. longface is in the developm ent stage. T h is will be served by nine entries on 225-ft. cen
ters. Som e of these entries are being driven w ith the aid of conveyors and
by these m eans are being extended much m ore rapidly th a n those th a t have been driven w ith o u t them . A s these entries are d riven 22 ft. w ide and bottom is taken 10 ft. in w idth, the conveyor is placed upon one o f the 6 -ft. benches and serves fo r the dis
charge of coal only. A n angled pan n ear the point of discharge drops the coal into the mine cars. (S ee Fig. 4 ) . T he bottom rock is loaded w ithout the interposition of any conveyor.
T o the m ajo rity o f m ining execu
tives it would appear th at the tim ber cost of this system of m ining would be excessive. It is adm itted th a t the tim ber cost is high, but in this con
nection it m ust be rem em bered th a t 60 per cent of the coal is sold a t the top m arket price. U n d e r o rd in ary conditions, the shortw all w ork in this field will produce only 40 per cent of big lum p coal. T h e g re a te r realiza
tion, due to an increase o f 20 per cent in the quantity o f lum p coal, m ore than com pensates fo r the high cost of tim ber in the long-face system .
E x p erim en ts have been m ade w ith
Bench
different plans of tim bering, b u t the system described in this article has been found the m ost satisfacto ry of any of those tried. T h e com pany does not claim to have reached the m illennium in longw alling but by the introduction of refinem ents, it is hoped th a t success will be attained.
Bench X . ______________________________________________________________________________
Fig. 4— D riving E n try in S olid w ith Coal C onveyor on Bench
K eep s the Coal M o vin g fr o m the Face
BETTER TRACKS
Stimulate Coal Production
By S. W . Blakslee
D ivisio n S u p e rin te n d en t, Pa. Coal & C o ke C orporation, E h re n fe ld , Pa.
H
A U L A G E requirem ents of the present day are entirely d if ferent from those of the past, since m ines are being m ade larg er p ro ducers and m ethods of w orking are being considerably altered in m any instances. L a rg e r locomotives, bigger cars, better track, together w ith m ore precise control of trip s and d istrib u tion of cars at th e face, are now required, particularly since mechanical loading has become a practice.
T he problem s of tran sp o rtatio n are m ore involved at the E h ren feld No. 3 m ine than a t-a n y o ther plant of the P ennsylvania Coal & Coke Corp. because, here, the hauls are longest and the tonnage is biggest.
In 1919 we w ere confronted at this m ine w ith a dim inishing tonnage. I n vestigation proved conclusively th at transportation m ethods and facilities w ere largely responsible fo r this condition. M iners w ere quitting daily and those le ft on the job w ere not being provided w ith a sufficient num ber of cars. T h e cars and loco
m otives on hand w ere in fairly good repair and adequate fo r the produc
tion of a m uch g reater ton n ag e;
pow er supply w as sufficient fo r all needs and yet delays w ere constantly occurring, due to w reck-producing track betw een the tipple and the w orking faces.
T
H E average haul from face to tipple was 4.2 miles. T h e m ine is divided into three distinct sections and the coal from them passed through a common sidetrack located 1.5 miles from the d rift m outh.D ouble track o f com paratively light steel, considering th at 13- and 15-ton locomotives ran on it, extended from this main sidetrack to the tipple. T h e main entry had been driven 35 to 40 years before w hen m ore atten tio n w as given to drainage th an to track tangents, w ith the result th a t in 3 miles of track not one tangent was m ore than 250 ft. long.
A s all traffic passed over th is sec
70
tion of track, a decision w as reached to replace it w ith a good g rad e of 70-lb. relaying rails. T h is w ork w as started early in 1920 u n d er the direc
tion of a fo rm e r railroad section fo re
man. W h e re local sw am ps did not perm it economical sw itching, some bal
last w as used. R ails w ere laid on 6 x 6-in. x 5-ft. oak and chestnut ties set on 18-in. centers. R ails w ere joined together w ith 6-hole angle bars, bolts w ere locked w ith w ashers and the jo in ts staggered. A ll curved rails w ere jacked— not sp ru n g — into place.
O n all curves the gage w as slightly increased and the outside rail ele
vated as necessary, rail braces of the Coover and A nchor types, spaced at intervals o f 30 in., being used as stiffeners. A ll o f this w ork w as done on the night sh ifts and S undays, w ith the result th a t no loss o f tonnage was suffered.
S
IN C E the com pletion of this job a total o f 2,400,000 cars o f coal and rock has passed over this track. T h e result has been : ( 1 ) Locom otive d erailm ents num ber but th ree and in no instance has the track been the cause.
(2 ) R u n n in g tim e of trip s has been decreased 28 p er cent. ( 3 ) T h e life of
locomotive wheels has been increased 40 to 45 p er cent. ( 4 ) T h e labor cost of hauling coal has been de
creased 40 per cent.
A
F T E R this jo b w as com pleted it became evident th a t the im provem ent w as going to pay big dividends and consequently plans w ere m ade to extend 70-lb. track into each section of th e mine. Since th a t tim e about 20,000 ft. o f old, 40-lb., track has been
replaced by the heavier “ iro n .” which brought resu lts as good as those derived from im provem ent o f the m ain haulw ay. M ore attention has also been given to tracks in room s and in b utt and panel entries. By these im provem ents in track we have been in a position to raise the to n nage at this m ine about 75 p er cent
above th a t of 1919 and reduce the labor costs of tra n sp o rta tio n a p preciably.
Som e of o u r stan d ard practices are listed briefly as follow s : A ll m ain line track is laid w ith 60- o r 70-lb.
rails ; all level panel entries w ith 40-lb. rails, except w here the grade exceeds 3 per cent, w hen 60- o r 70-lb.
rails are used ; all room entries w ith 30-lb. rails w here the tra c k is level and w ith 40-lb. rails w here th e g rad e exceeds 3 p er cent. L ock w ash
ers are used on all track except th a t m ade up of 16-lb. rails.. A ll sw itches off m ain haulage roads are equipped w ith sp rin g sw itch-throw s. Ju m p - over sw itches and hom e-m ade frogs and sw itches have been elim inated and only m an u factu red room tu rn outs and sw itches are installed. W o rn
frogs are repaired in place by a w eld
ing process. A ll locom otives are equipped w ith re-railers o f the A nch o r type, w hich is also used to serve the purpose of a runaw ay switch.
A
R E R A I L E R is used a t each end of m ain sidetracks, w here cars are o ften derailed w hen sw itches are split, o r th ro u g h excessive bum ping, p u sh ing, etc. A “ fro g iro n ” is used on fro g s at m ain sidetracks and on planes w here atten d an ts and rope rid ers are employed. T h is is hom e-m ade and designed to fit th e fro g snugly, closing the opening on one side of the point. W e have found th is device useful in the prevention of w recks caused th ro u g h the picking o f the fro g point by sw inging cars. (B o th o f these devices will be show n in detail in th e S eptem ber issue.).A g ang o f five m en w orking on the night sh ift is regularly em ployed to take care o f the track , to atten d the drainage and to clean the ro ad bed on the m ain haulw ays. All m ovem ents of m ain haulw ay locom o
tives betw een term inals and m ain side-tracks are governed or dispatched by telephone.
LONGWALL or ROOM
Which?
By R. Dawson H all
E n g in e er in g E d ito r , Coal A g e N e w Y o r k C ity
W
H E T H E R the room -and- p illar m ethod should contin u e to flourish now th at m echanical loaders and face convey
ing have been introduced is, perhaps, th e m ost hotly debated of all subjects b efo re the m ining public. B oth sid e s- a re ard en tly zealous fo r the m ethods they advocate, b u t th e re are m any w ho fran k ly align them selves w ith neither, and who are w aiting to find w ho is rig h t, and w hether the claims o f both a re not a little e x trav ag an t and only tru e fo r certain kinds of ro o f and certain depths of cover.
I t is ju s t as well, th ere fo re, to de
scribe situations as I found them and to leave decision to the reader. B ut it m ust be cem em bered one m ust alw ays in q u ire w hen speaking of longw all o r longface, ju s t w hat kind of longwall o r longface is m eant, fo r th e re a re so m any interm ediate and new ly-planned m ethods (a t least they a re new ly planned in the U nited S ta te s) th a t lie so equivocally be
tw een the tw o extrem es th a t one can
n o t safely take any stand as to the rig h t w ords to use. T h e re is the single-V system , fo r exam ple. A scraperw ay is driven up, as n arro w as the n arro w est o f room s. T h e n it is w idened, and th e pillars are draw n back. S u rely th a t is a room -and-pil- lar w orking.
B u t no! W h o would attem p t to
draw back, by o rd in ary m ethods such as room -and-pillar operators practice, pillars o f such w idth w ithout leaving cautiously one pillar som ew hat behind the o th er? H e re a place 125 ft. wide is draw n a t a time. W ith the tw o-, three- o r fo u r-V system s the w idth th ro w n open is even g reater. T h e w idth m ay be nearly 400 ft.
Som e of the longwall o f w hich we hear, that, fo r instance, at Indianola, has pillars draw n in steps, each step only 130 ft. wide. Is th a t longw all?
T h e pillars are perhaps only 30 or, say, 40 ft. w ider than was form erly the practice in some regions w ith room -and-pillar w orkings.
T h e re are places, how ever, w here blocks 1,000 or even 1,800 ft. long are being draw n, w ith roads splitting the pillars and serving as passages dow n which the coal can be tram m ed.
A s stated, th ere are others w here the w idth is only 130 ft.
A t the same tim e th ere a re some places barely 50 ft. wide, yet even these some people are term in g long
wall. N o w onder some are saying that longwall m ust be defined defi
nitely. W ith thi sas a preface, it will be well to leave the persons in ter
viewed to speak fo r themselves.
F o rem o st am ong those who have practiced longwall operation is the V alley Sm okeless Coal Co., w hich has been using th at system at its No. 3
m ine, a t F ern d ale, n ear Joh n sto w n , Pa. A t th a t operation, T . M . D o d son has proved th at, even w ith the ro o f as flexible and difficult to break as it is in the Joh n sto w n field, long
wall can, if properly practised, be m ade an en tire success.
“ C areful observations,” said M r.
D odson, “ have convinced us th a t at
Fig. 2— S m a ll Scoop o f P . C. & C. Corp.
the m ine of the V alley Sm okeless Coal Co., as elsew here, the ro o f does not break dow n close to th e coal pil
lar. W h a te v e r m ay be the u pper lines o f fra c tu re and how ever m uch such a fra c tu re m ay pass over th e solid coal, the fact rem ains th a t a t th e edge of th e pillar, th e rock ten d s to “cornice o u t” like a shelf, leaving a space into w hich a m an m ay craw l and into w hich m any have craw led long a fte r the room o r w orking has caved to the surface.
“ T h is w as th e conclusion draw n in a report m ade by R. Y . W illiam s, w ho in 1924 w as given a roving com m is
sion to visit w orkings in various p a rts of the co u n try and to re p o rt to th is com pany. H is opinion w as th a t in w orkings on the V -system w hat was needed w as not to attem p t to su p p o rt th e ro o f on the w eak tips of th e p il
lars, but to w iden o u t th e m ouths of the V ’s and to invite falls w ith in the w ide openings, keeping the actual
71 F ig. 1— M e th o d o f Operation o f S m a ll Scoop, Pennsylvania
Coal & Coke Corporation
72 C O A L A G E — V 01.32, N O.Z
Fig. 3— Original T h re e -V S y ste m , P . C. & C. Corp.
w orking faces open by the use of rigid supports.
“ H ow ever, we did not adopt th at method as the mine w as not suffi
ciently developed to p u t M r. W il
liam s’ suggested V -plan into opera
tion. W e finally decided to w ork a panel longwall system , w ith each panel 300 ft. wide, but w ith every alternate panel w orked advancing tow ard the boundary and the ones ad jacent to it held fo r w ork on the retreat.
“ T he panel th a t is to be m ined re
trea tin g has two roads th rough the center w ith a 50-ft. pillar between them and it has tw o other roads so located on either edge th a t the inby rib o f each will be the outby o r o u t
side rib of the other panel as its long
wall extraction advances.
“ Because of the n atu ral tendency of the roof to ‘cornice o u t’ fro m the su rro u n d in g ribs, th e w orkm en a t the longw all face get protection which, indeed, would be inadequate in itself w ithout artificial support, b u t w hich can be m ade am ple by the use of wedge jacks, w hich provide the roof w ith rigid, support. A n d let m e lay stress on the w ord ‘rig id ’ fo r if the support be flexible o r yielding th ere will be dow nw ard p ressu re on the face of the coal. W ith a rigid sup
p o rt form ing itself a fulcrum , the load on the face of the coal is lightened ra th e r than increased.
F u rth e rm o re , the ‘cornice effect’ w ith the aid of cribs m akes possible the m aintenance of roads, at least fo r short distances, along the rib on the side of the longw all.”
In discussing the relative a d vantages o f longw all and room -and- pillar w orkings, C. L aw W atk in s, vice-president and general m anager, P ennsylvania Coal & Coke C o rp o ra
tion, said : “ I t all depends on w hat you term ‘longw all.’ I f in it is in cluded the single-V system , it can be used w ith advantage at some of our mines. B ut a retre a tin g longwall w ith a long face w ould req u ire so m uch tim ber fo r its su p p o rt and so m uch labor fo r its installation th a t it would not pay. Its efficiency in cu t
ting, shooting and loading w ould be fritte re d aw ay in the costs of tim ber and tim ber erection. In fact it could hardly be operated a t all w ithout packwalling.
“T h e V system , how ever, is p ra c ticable, but really th a t is h ard ly even modified longwall. I t is m erely room -and-pillar w ork w ith extrem ely n arro w room s and w ide pillars, w orked on an inclined line. T he three-V system , as w orked a t N orton,
F ig. 5— W h ere the L in e o f P rops A lo n g the Face Converge at M in es
o f P . C. & C. Corp.
Va., and later a t o u r m ines, has, how ever, the draw back th a t synchroniza
tion is necessary. T h e various pillar points betw een the roadw ays should be kept in line, and all m ining of pil
lars should be com pleted a t the sam e time. I t som etim es happens th a t w ork on a V will have to be delayed, w aitin g fo r the ro o f to fall. T h is necessitates holding the en tire crew in o rd er to finish the delayed V.
“ T h e single-V system in w hich one room is driven, say, 10 ft. w ide and then w idened at the face and then backw ard into the sem blance of a V , gives b etter resu lts as o u r experience has show n. P illars are le ft betw een the V -shaped room s but they are th in and do not constitute m ore th an 5 p er cent of all the coal. Som e additional coal is lost by reason o f rolls and clay spars and perhaps in all an 85 per cent recovery is m ade, but th a t is as m uch as w as recovered w hen the o rd in a ry room -and-pillar operation w as in use.
“ T h e system has been so successful w ith us th at it has been introduced not only into o u r C am bria C ounty m ines, but into those in In d ian a C ounty also. I t does not follow , how ever, th a t this single-V system should be installed everyw here.
W h e re coal has p artin g s an d needs scrupulous cleaning, and w here th e scraper breaks it, m aking picking difficult, it is not well to attem p t operation in th a t m anner. W h e re the floor is friable some kind o f bot
tom would have to be p u t on the scraper to prevent it from b ringing clay as p a rt of its burden. W h e re th ere are rolls in the floor th e condi
tion is even w orse. F u rth e rm o re , if the coal is friab le the scrap er m ay crush it and m ake its sale difficult.”
S. W . Blakslee, division su p erin tendent, is an enthusiast re g ard in g scrap er loading. H e em phasized its safe ty and the satisfaction of th e m en w ho operated th e system w hich does so m uch to ease the d ru d g e ry of loading. T h e tim ber cost also, w hich
! II II 11---II--- 1 i— i r
Fig. 4— S in g lc -V M ethod, P. C. & C. Corp.
A u g u st, 1927 — C O A L A G E 73
Fig. 6— Loaded Scoop at Face; P. C. & C. Corp. M ine. F our P osts, Indicated by A, A r e One E n d o f a B reak R o w
in som e form s o f longface w orking is discouraging, he said, is only about 4c. p er ton h ig h er th an w ith room - and-pillar m ethods o f operation.
H e described the m ethod adopted w hen single V ’s are used as is now the general practice of his com pany. “ T he scraperw ays o r developm ent entries are d riv en n arro w and 325 ft. long on 120-ft. centers. T h e V ’s are started rig h t a t the airco u rse o f the heading beyond and then w orked re trea tin g tow ard the loading entry. Yes, the aircourse is aflowed to cave w ith the V b u t so f a r the rock has never blocked the a ir m aterially.
“ O u r aim is to keep the face at an angle o f about 32 cleg, from the scraperw ay as th a t m akes the lengths of each of the tw o faces 100 ft. W e find we can load one cut from each face o r the equivalent of one 200-ft.
face every day.
“ H e re is o u r system (see Fig. 1).
O nly a few sheaves and no snatch blocks are required. T h e full lines represent the path of the ropes when w orking the rig h t-h an d face. In this case one sheave is used on the head- rope and six on the tailrope. T he path taken by the rope w hen loading o ut of the left-h an d face is indicated
by the dotted line. T he headrope is perm itted to run against the corners at A and B , and the tailrope is carried betw een the first and second row of tim bers.
“ H e re ,” M r. Blakslee rem arked,
Fig. 7— Double D rum , Friction T ype, P . C. & C. Corp. M ine
“ is o u r scraper (see Fig. 2 ) . W e have turned in the corners o f the side pieces. T hese rounded corners tend to m ake the scraper stay out of the loose coal and run in the cleaned
path, th u s causing less breakage of th e coal. A sh arp edge w ould dig into th e loose coal a t th e side of the road and tend to tu rn th e scoop into it, b u t w ith the rounded edge the scoop goes ahead and m inds its own business. T h e bottom s of the side plates have curved steel ru n n e rs to prevent the scraping o f th e bottom rock.
“ T h e face is tim bered a t n ig h t by the n ight sh ift. A f te r every cut a row of 6-in. round posts is set on 4 j4 -ft. centers, 7j/2 ft. fro m the face.
E v ery 75 to 80 ft. we set a break- row consisting o f tw o lines o f 6 -in.
posts 18 in. a p a rt w ith th e posts staggered and set on 2-ft. centers.
“ A fte r the V has progressed so th at the break-row has been extended to the full w idth of th e room o r panel, and before the ribs have advanced m ore than 15 ft. from the ends o f the break-row , the tim bers in the gob back of the row are chopped in o rd er to allow the roof to come down. T h a t usually takes tw o or th ree hours and som etim es, as you can see, breaks are not obtained ju st w here we w ant them (see F ig. 4 ) .
“ E v ery day approxim ately 168 tons is loaded from th e chute a t each V. T h e loading of the tw o 100-ft.
faces of each V is easily com pleted as a rule in 8 hr., but w hen it takes longer the m en continue a t w ork till all the coal is loaded o u t ready fo r the night sh ift. T h e m en are paid the union scale. (T h e se m ines are now sh u t dow n like all th e union m ines in C entral P en n sy lv an ia.)
“ So successful has been the o p era
tion o f scrapers as com pared w ith the old hand m ethods w ith room -and- pillar th a t the com pany has loaded about 600,000 tons o f coal in th a t m anner and steadily increased the num ber o f m ines th u s operated, th e re by reducing its op eratin g deficit.”
J. F. M acW illiam s, electrical en
gineer. said. “ In some of the m ines
Fig. S— B rcak-R ozv w ith Cave B ehind I t on R ig h t, P . C. & C. Corp. M in e
74 C O A L A G E — V ol.32, N o .2
Fig. 9— S h a kin g Conveyor. H a n d-L oading Face, Union Pacific Coal Co., E arly T rials
where the M iller seam is being ex
tracted, the regular room -and-pillar system reigns, but m echanism has been introduced to aid in the loading of the coal. L orain chain conveyors are being used in the roadw ays. Cross conveyors of the drag-belt type are being made in the shops. T h ey are driven by air-drill m otors using com pressed air. A bout 4,000 ft. of these cross conveyors have been con
structed. T w o com pressors have been installed on the su rface at E h ren feld , arid air will be sent into the m ine by vertical pipes. T he chain conveyors are driven electrically, w hich is feasible as they a re in the entry. H ow ever, they will be p ro vided w ith perm issible m otors to assure th eir safety. T h ese conveyors deliver the coal to the entry. W hen operated continuously they will de
liver 24 tons p er h o u r on a level grade."
T h e quantity o f tim ber used in longface w orkings, and the cost of setting that tim ber, have been greatly em phasized by those w ho have favored the room -and-pillar m ethod of operation. B ut G. F . O sier, vice- president and general m an ag er o f the P ittsb u rg h T erm in al Coal C orpora
tion, on being interview ed, while acknow ledging th a t w hat w as gained in the cost o f ex traction by longface was lost in expenditures fo r tim b er
ing. nevertheless believed th a t this m ethod had proved desirable a t N o. 9 m ine. A vella, P a.
H e favored th e system , because w ith it the en tire q uantity o f coal w orked had been recovered and be
cause the product w as m ore biocky v h e n th u s m ined. E ickhoff con
veyors w ere used. T ru e , the roof w as bad. so m uch so th a t posts had to Iv set every 6 ft. betw een th e con
veyor and the face to m aintain the draw slate w hich w as 14 in. thick.
A t one tim e he thought it would be best to let the draw slate dow n and post u n d e r the rash w hich is 5 ft.
thick, but w hen this w as tried the posts pushed up into the rash and the tim bering failed o f its function. F o r this reason it w as found better to post well and leave the draw slate undisturbed. T h e posts along the face w ere relatively so few th a t they w ere little in the w ay of the loaders.
N o packw alls w ere built. A single line o f props w as placed on 24 to 30 in. centers behind the conveyors. T h a t done, the ro o f broke w ithout difficulty.
T h e posts w ere of 8 in. diam eter in
stead of 4 in. as is usual in room -and- pillar w orkings a t th a t m ine. T he coal w as 3 ft. thick.
A t the A rd en m ine w here room - an d -p illar m ethods a re used, some old pillars have been w ith d raw n by E ickhoff conveyors. T h e use of this m ethod saved m oney w here the coal w as thin, because it w as not neces
sary to m ake height fo r cars, to lift
m uch fallen rock or to lay track as would have been m an d ato ry had any o th er kind of equipm ent been em ployed. In som e cases the conveyors w ere used to assist in d riv in g places across room pillars n ear th e ir ends.
A s soon as the cro sscu ttin g w as com pleted, the ends of the pillars w ere e x tracted and the coal bro u g h t out by conveyors. T h is proved a profitable experim ent.
W . L. A ffelder, a ssistan t to the president, H illm an Coal & Coke Co., stated th a t he believed th a t the u lti
m ate solution fo r the economical m ining of coal from 3 to 5 ft. in thickness w as to be fo u n d in th e use of hand-loaded conveyors in room - and-pillar w ork, ra th e r th an in lo n g face m ethods. H is conclusion w as based upon results obtained d u rin g the past year and a half a t one of his com pany’s m ines in central P en n sy l
vania in w hich a num ber o f L o rain conveyors are in use.
R oom s 35 to 40 ft. w ide and 250 ft. in depth are driven on 75-foot centers. Inasm uch as only one m ain conveyor is used in a b u tt entry, operations in any b u tt are lim ited to advancing o r re tre a tin g in only one room. T h e chain pillars betw een tw o b u tt entries a re rem oved by pick w ork and the coal is loaded by hand into m ine cars. T h e m ain conveyor, driven by a 15 hp. m otor, is carried n ear the rib side of th e room and coal is delivered to it fro m th e a d vancing room face or from th e open end of th e re tre a tin g rib by a suffi
cient num ber o f 12-ft. rubber-belt face conveyors, driven by } i hp. m o tors. N o coal is recovered fro m the gob side o f a room w hile retreatin g .
T h e conveyors are w orked on single sh ift only, but operation of them on double sh ift is contem plated.
T he com plete cycle o f d riv in g up a room and b ringing back a rib re
F ig. 10— Azeaiting Scraper at U. P. C. Co. M ine
A u g u s t, 1927 — C O A L A G E 75 q u ires about six w eeks if the m ine is
w o rk in g steadily. T h e cover over the coal in the sections in w hich the conveyors are used ranges betw een 250 and 300 ft. in thickness.
Clarence R. C laghorn, consulting m ining engineer of B altim ore, M d., the first m an to em ploy conveyors in coal m ining, in this respect preceding both the B ritish and th e G erm ans, in a w ritte n com m unication states :
“ T h ro u g h experience I have arriv ed at some decided im pressions as to the conditions u n d er w hich longw all can be m echanically w orked in com
petition w ith o u r custom ary roorn- an d -p illar system . F o r instance, e x cept in ex trem ely th in coal o r u nder peculiar ro o f conditions, I do not th in k th a t longw all advancing, w ith subsidence, can ever be as economical as room -and-pillar w ith conveyors. I believe th a t w hen we come to longwall in th is country, as w e undoubtedly will in the fu tu re , it will be some fo rm o f straig h t-fac ed longwall, w orked on the re tre a t and w ith caving.”
P . M. S nyder, president, C.C.B.
Sm okeless F u el Coal Co., rem arked th a t he is m aking an ex p erim en t in th e use of conveyors in the m ining o f coal from the P ocahontas No. 4 seam w hich is fro m 36 to 40 in.
thick. H e has hopes th a t his m ethod o f o peration will be successful w ith coal o f this thickness w hich is such as n o t to p erm it o f th e use of cars at th e w o rk in g faces w ith o u t the shooting o f bottom o r the b rushing o f top rock. T h e bottom is of slate an d requires heavy shooting, and it is difficult w ith o u t excessive cost to stow all th e rock. M uch of it has to be b ro u g h t to th e su rface, hauled up to th e hill tops and deposited th ere because th e valleys do not supply a suitable place fo r its dum ping.
P . C. G raney, th e general m an
ager, and C. E . B ergendahl, chief en
gineer, described th e m ethod th a t w as being adopted. T h e room s are d riv en w ith a m ain conveyor— L orain chain type— placed n e a r one rib, the room being 40 ft. w ide and 280 ft.
long. T h e conveyor comes in 6 -ft.
lengths w ith occasional 3-ft. sections fo r use w h ere needed.
T h e coal is b ro u g h t to th is m achine by face belt-conveyors. T h ese are 12 ft. and 20 ft. long. T h e com pany finds th a t th e 12-ft. lengths a re the easier o f th e tw o sizes to handle. T h e m ain conveyor can be reversed so th a t tim ber can be carried into the w o rk in g face. A t S totesbury, about 8 in. of ra sh has to be rem oved to get to good top, but at H elen m ine the
ro o f is free of bone and has excellent characteristics. T im b er is set sys
tem atically behind the face conveyors as fast as they are moved forw ard, which is done each tim e a cut is cleaned up.
T im b ers are set 4 ft. ap a rt and in row s on 4-ft. centers. ' T h e pillars are mined, from th eir ends, the room s usually being on 60-ft. centers leav
ing a 20-ft. pillar, which is brought back as soon as the room is driven up, w ith exceptions to be noted later.
T h e detail as to the pillar w idth is not finally settled, but will be fixed by the experience obtained.
T h e cars are pushed into the entry by the locomotive and then spotted u nder the end of the m ain conveyor in trip s of 15 to 20 by m eans of small hoists w here the grade is adverse.
W h e re the grade is favorable o r can be m ade so, the cars are spotted by gravity, the hoist being the m ore positive, especially w here the cars are heavy as a t S totesbury. W h e re de
sirable, the cars are directed from the loading point to the nearest crosscut and into the o ther headings o f the entry. T o date, at H elen, eight places have been driven up but no pillars draw n because o f p roxim ity to the outcrop, not because the ro o f was bad. T h is m ethod was followed to protect th e m ine against caves which w ould b rin g in su rface w ater. A t S totesbury five places in a row have been driven u p and the pillars draw n im m ediately. F o u rteen days a re con
sum ed in d riving and five to six days in com ing back w ith the pillar. T h e conveyor sections a re carried o u t by the conveyor itself as the pillar re treats. W h en the pillar is back to the
heading stum ps, all the sections are already assem bled for m oving.
A n u n d ercu ttin g m achine is kept at the face of the w orking. L im iting of the activity of the face c u tte r to a single place is m ore th an com pen
sated by the saving effected in the use of a locomotive. F u rth e rm o re , the use o f the conveyor has reduced costs by m aking it unnecessary to lift bot
tom or shoot top. S ix -fo o t extensions of the conveyor a re m ade in 20 m in.
F ro m 2 l/> to 3 cuts a re m ade d u rin g each 24 hr.
R oom s are driven by the use of a blow er and tubing. F iv e m en includ
ing the sp o tter are em ployed p e r sh ift and tw o sh ifts are w orked per day.
M echanization of the loading proc
ess m eans m uch m ore th a n m erely buying equipm ent and p u ttin g it to w ork. I t involves, as well, the p roper balance o f m en and m achines and the correct application of the equipm ent to the w ork in g m ethod pursued.
T h e solution of th e problem o f w hat system o f m ining to adopt m ay be, and probably is, a local one, de
pending on roof, coal, floor and cover. T oday, how ever, th e re seem to be few clear indications to guide the individual o p erato r in choosing a system . E v ery region m ay have to find a m eans o f overcom ing its own in h eren t difficulties. A lm ost every coal field in th e past has believed it
self different and practiced its ow n peculiar m ethods. I t is tru e th a t som e differences exist, b u t too o ften they are largely im aginary. O nce in a w hile a brave th e o rist breaks th ro u g h his environm ent, boldly tran sp lan ts a m ethod o f m in in g and m eets success.
Fig. 11— B reak B ehind C onveyor Face, S u p erio r M ine, U. P . C. Co.
