C o a l A g e
A McGr a w- Hill Pu b l ic a t io n— Es t a b l is h e d 1911
D E V O T E D T O T H E O P E R A T IN G , T E C H N IC A L , A N D B U S IN E S S P R O B L E M S O F T H E COAL M IN IN G IN D U S T R Y
New York, S e p te m b e r, 1 9 3 0
Vo l u m e 3 5 . . . . Nu m b e r 9
Mechanization— Top and Bottom
W E R E confirm ation of th e w isdom of the C oal D ivision o f th e A . I. M . E . in fe a tu rin g p re p a ra tio n problem s a t its P itts b u rg h m eet
ing necessary, g o v ern m en t statistics on m echanically cleaned bitum inous coal, m ade public Sept. 6, unm istakably furn ish it.
M echan ical p re p a ra tio n in 1929, B ureau of M in es figures show, ran a d ead h e a t on to n nage w ith m echanical loading. In b o th cases, in stallatio n s o f equipm ent la te in th e y e a r fo re sh a d o w much g re a te r increases in volum e in 1930.
S U B S T A N T I A L T O N N A G E S in b o th de
v elopm ents have been con cen trated in re la tively few states. In th e case o f m echanical loading, fo u r states accounted fo r 74.9 p e r cent' o f th e volum e so h an d led u n d e rg ro u n d last y e a r; eig ht states con trib uted 95.3 p er cent o f th e bitum inous tonnage p re p a re d m echanically du rin g the same p erio d . T h e to ta l q u a n tity o f s o ft coal so cleaned was 3 7 ,1 4 3 ,0 0 0 net tons.
C E R T A I N S T A T E S which loom larg e in u n d e rg ro u n d m echanization, how ever, play a sm all p a r t in m echanical cleaning. T h is is n o t su rp risin g despite th e fact th a t m echani
cal lo ad in g is gen erally accepted in m ost fields as the fo re ru n n e r o f m echanical cleaning.
B ut the situ a tio n is signi’ficant— as sp o ttin g ou t those a re a s in which an early swing fro m o ld er m eth o d s m ay be expected. T h e sound
ness o f this view point is em phasized by m any o f th e m o d ern iza tio n p ro g ra m s now u n d e r way.
C O M M E R C I A L co n siderations also will p ro m o te f u rth e r expansion even in d istricts w here physical conditions, n a tu ra l o r induced by m echanized load ing , a re no t a sp u r to such to p w o rk s m echan ization . M echan ically p re p a re d coal is acqu iring a sales value which, if n o t y et ad eq u ately reflected in prices received, is evident in to n n ag e. E a c h increase in this o u tp u t im presses a d d itio n a l sales value on th e p ro d u ct.
B O T H F O R M S o f m ech anizatio n, th e re fo re , m ust continue to advance— one th a t costs m ay be lo w ered and la b o r lig h ten e d ; th e o th e r, th a t th e p ro d u ct m ay be im pro ved.
W ith th e in d u stry realizin g, p e rh a p s as n ev er b efo re, th e d o m in a tin g p o sitio n o f th e con
sum er, no o p e ra to r can afford to ign ore these
iessons of th e p o stw a r trend s.
A Coa l M in e Fr om on H ig h
Jerome (Pa.)Mines,Hillman Coal 8CCoke Co.EFFICIENCY AND SIMPLICITY
4- Goal in N e w M in e
O f Pond Creek Pocahontas Co.
I
N M cD ow ell C ounty, W .V a ., the P o n d C reek P ocahontas Co., w hich is controlled by the sam e in te re sts as the Isla n d C reek Coal Co., has opened a new m ine know n as P o n d C reek P ocahontas N o. 3, notable f o r sim plicity and efficiency o f equipm ent, rap id developm ent to ra ted tonnage, a n d excellent n a tu ra l conditions. T h e tipple w as p u t into operation F eb . 3 of this y ear, loading 30 to n s on th a t day, w hen b u t 500 ft.of headings had been d riv en fro m the bottom o f th e slope and a ir sh aft.
B y A u g . 15 th e m ine h ad reached a p ro d u ctio n of 2,400 tons.
T h is m ine is n e a r B artley, 16 miles fro m Iaeger, on the D ry F o rk branch o f th e N o rfo lk & W e s te rn R .R . in the T u g R iv e r d istric t. I t is in a tra c t of 3,600 acres, ow ned in fee, in w hich th e com pany has fo r several y ears been m in in g th e P ocahontas N o. 4 seam th ro u g h a 585-ft. sh aft.
T h e new m ine is in th e Beckley seam, w hich in th is locality lies 390 ft.
above th e P ocahontas N o. 4 and 90 ft. below th e railro ad trac k s at the
Sim plicity and
point selected f o r the opening. V alue w as first attached to th e Beckley seam on th e tra c t w hen several test holes to the N o. 4 seam p en etrated a consistent thickness o f clean coal above. C ore drillings m ade la ter to prove th e Beckley seam indicate th a t th ere is available ap p ro x im ately 2,500 acres of coal, w ith o u t p a rtin g and lying practically level, av erag in g 52 in. in thickness.
B y p ro x im ate analysis th e Beckley coal is alm ost th e sam e in every p a r ticu la r as th a t fro m th e P ocahontas N o. 4 seam . I t has th e advan tag e o f being m uch h a rd e r, and th e re fo re stands handling. T h e yield in a typical m onth w as : L u m p ov er 7£ in.
ro u n d , 16.53 p e r c e n t; egg ( 2 ^ x 7 ^ in .) , 24.47 p e r c e n t; stove ( l x 2 i in .) , 15.55 p er c e n t; n u t ( £ x l in .) , 11.34 p e r c e n t; and £-in. slack, 32.11 p e r cent. L um p, egg, and stove to tal 56.55 p e r cent.
E n try is by a rock slope 300 ft.
Compactness A re Features o f the T h orou gh ly
By J. H. EDW ARDS
Associate Editor, Coal Age
long on a pitch o f 18 deg. T h is slope is equipped w ith a 42-in. belt con
v eyor th a t ex ten d s beyond th e p o rta l th ro u g h a gallery 200 ft. long across D ry F o r k C reek to th e tipple. T h e conveyor drive, consisting of a 75-hp.
T y p e F T R induction m otor, m ultiple V -b elt connection an d tw o tra ctio n pulleys g eared w ith o u t differential, is located a t th e p o rta l of th e slope o n a low foundation. In th e slope is a supply tra c k w hich parallels th e belt conveyor.
S teel cars o f th e lift-e n d g ate type hav in g w ood bottom s w ere selected.
T h ese have a capacity o f 95 c u .ft.
level full and stan d 28 in. above th e rail on w heels equipped w ith E n te r p rise solid-roller bearings. T h e slope bottom is equipped w ith a n electric reciprocating car feeder, au to m atic eager, cross-over dum p, 9 -to n bin, M odern T ip p le
S e p tem b er, 1930 — C O A L A G E 515
^..Vvv W»-> ;-v
\V . o;s .-V ''-^.-vV ;v
.■X' S w v :Xv-.j.
- \ B i k « s i C ^ t a f f i O e i r s i i i f ;
W * «ft As^sv-ts S m
IKo'v <A\hn\\m the SN.»V*-( IViw W UvU^wt
W nl\ .«
.W x.'tl'l, NU* UK' Fu
IM w (Ko IW k
I'he Picking T ab le Screen Is W ell Illu m inated From W ind ow s and Sk yligh ts
T h e M ain Conveyor D rive Is Located on the G round at the S lo p e Portal
- *#.>s
recip ro catin g coal feed er to th e belt, and g rav ity kick-back fo r the em pties.
W h e n the d u m p er pushes th e car- feed er b u tto n a “d u ck ” engages the bottom of th e c ar and m oves th e trip fo rw a rd one car length, a t w hich p oint a lim it sw itch causes th e “duck”
to re tu rn autom atically to sta rtin g position. W ith an o th er button, the d u m p er can stop th e m ovem ent a t any p o in t if necessary.
H ead in g s a re d riv en 15 ft. wide, and room s 26 ft. w ide on 60-ft.
cen ters to a d ep th of 300 ft. A stro n g sand-rock top m akes posting unnecessary. T h e only chance of e x tra n e o u s m a tte r g ettin g into the coal is fro m a -f-in. vein of slate w hich clings to the sand-rock top.
W h a t little falls and is n o t cast aside
by the loader, is easily rem oved in the tipple by h and picking because it rem ains in fa irly larg e layers. E x perience to date indicates th a t the best shooting practice is to d rill th e usual center hole and tw o side holes. T w o to th re e l^ x 9 -in . sticks o f M onobel N o. 9 are used in th e cen ter hole and l \ sticks in each rib hole.
M in in g equipm ent consists o f fo u r Jeffrey 35-B B u n d e rc u tte rs w hich stand 33 in. above the rail w hen m ounted on th e tru ck . G ath erin g equipm ent consists of five . Jeffrey cable-reel locom otives, inside fram e, sta n d a rd type, 26^ in. high, w ith a speed of 4 m iles p e r hour. F o r m ain haulage th e re is one 10-ton outside- fram e locom otive, 32 in. high, a rra n g ed fo r tandem op eratio n w ith
a sim ilar locom otive to be p urchased w hen th e need arises. A n “ M S A ” low -pressure, 800-lb. hopper, rock d u ste r, 32 in. high, com pletes th e in side equipm ent.
S ix ty -p o u n d rail is used on m ains, 40-lb. on flats, an d 25-lb. on. b u tts and in room s. Steel ties a re used in room s, 4x6-in. w ood ties on flats and b u tts and 5x7-in. ties on m ains.
A t an a ir s h a ft located 200 ft. fro m the slope p o rta l th e re is a Jeffrey 5 x l0 - f t. reversible fa n operating, e x hausting, d riv en by a 25-hp. squir.rel- cage m otor w ith m anual control. A t p re se n t the fa n is o p eratin g a t 80 r.p.m . an d delivering 100,000, cu.ft.
of a ir ag ain st a ¿ -in ..w a te r gage. T h e d rive is a m ultiple V -belt w ith a co u n ter s h a ft on slide ra ils-b etw een
Bottom Plan, P ond Creek P ocahontas N o .
A ir s h a ft
S e p te m b er, 1930 — C O A L A G E
Loading From a Slab bing Cut in a Room ; Car U sed Stands O n ly 2 8 In. A b ove Rail
m o to r an d fan sh a ft. T h is provides m axim um flexibility in su b stitu tin g la rg e r m o to rs as h ig h er fa n speeds becom e necessary and m akes f o r con
venience in a d d in g a n a u x ilia ry m o to r if th a t should becom e advisable.
I
N A S M U C H as the m ine liberates som e gas, closed lights a re used an d a n afir-flow c o n ta cto r device opens th e 275-volt d.c., feed er b reak er th u s cu ttin g po w er off th e inside circuits in case th e fa n stops. T h e substation is located outside, close to th e fan , and both th e sub statio n building and th a t housing th e fa n d rive a re bu ilt of co rru g ated asbestos b oard m ounted on steel fram in g . T h e substation contains one 200-kw . T y p e H C C sy n chronous c o n v erter w ith m anual contro l. F o u n d atio n s and ducts have been provided fo r th e installation of a n additional u nit.
C onsidering th a t th e m inim um rate d capacity is 250 to n s p e r h o u r an d th a t th e re a re five loading track s fo r loading as m any sizes, th e tipple, b uilt by th e R o b e rts & S c h a e fe r Co., is o u tsta n d in g as a com pact stru c tu re . I t contains a M arc u s picking table screen fitted w ith a rescreen in g sec
tio n p ro v id in g fo r picking ru n of m ine w ith o u t th e use o f m ix in g con
veyors. T h e lum p is picked on th e m ain table and th e egg and stove sizes o n th e side w ings. D irectly u n d e r the M arcu s a re tw o A rm s v ib ratin g screens. T h e s tru c tu re is equivalent to th a t o f a fo u r-tra c k tipple except f o r a sm all o verhanging ad d itio n a t th e end o f th e building accom m odat
in g th e discharge end of a 24-in. belt
conveyor and a chute fo r loading n u t on a fifth tra ck .
P ick ed sizes are loaded ov er th re e o u tdoor, individual-covered, belt-type load in g boom s w hich use th e sam e w id th o f b elting as th e slope con
veyor. B ecause th e tip p le b u ild in g is n a rro w , th e w indow s in each side opposite th e picking tables, to g e th e r w ith th e skylights above, allow n a tu ra l lig h t to strik e th e picking table advantageously fro m th re e d irections.
R u g g ed n ess of equipm ent is co n sidered o f p rim e im p o rtan ce in th e tipple design, th e re fo re a N o. 10 M a rcu s d riv in g head w as installed.
T h is is th e heaviest m ade an d is one size la rg e r th a n is sta n d a rd fo r th e size of screen used. I t is d riv en bv
I
a 25-hp. T y p e F T R induction m o to r connected by a sh o rt-c e n te r flat belt w ith idler. O n e 15-hp. m o to r drives all th ree loading-boom conveyors, b u t clutches a re pro v id ed so th a t an y boom can be cu t o u t of service.
A s the tipple h ad to be built on loose g ro u n d beside th e creek, it was a problem to p ro v id e a secure fo u n d atio n f o r th e heavy M arcu s d riv e to be located ab o u t 24 ft. above the track . T o su p p o rt th e f o u r con
crete colum ns c a rry in g th e d riv e floor, a co ncrete m a t o r fo o te r 26x34 ft. and 3£ ft. th ick w as laid 11^ ft.
below th e su rface . T h is re sts on 38 w ood piles of 6-in. tip d iam eter an d 14 to 16 ft. long. T h irte e n to n s of re in fo rc in g w as used in th e fo o te r and colum ns. E x c e p tin g fo r floors o f concrete, th e rem ain d er o f th e tipple is of steel.
O n e six -ro o m house, six eight- room houses, and th re e b o ard in g houses have been built. T h irty a d d i
tional houses, th re e b o ard in g houses, an d a sto re a re now u n d e r co n stru c tion. A n u n u su al fe a tu re is th a t C a lifo rn ia redw ood sid in g is used fo r all. T h is m aterial should last th e life of th e m ine even if n o t painted.
C om position roofing is th e sta n d a rd fo r all buildings. E v e ry house is equipped w ith bathroom , sta n d a rd flush toilet, kitchen sink, and h o t- w a te r tan k . A ll are u n d erp in n ed w ith 1-in. oak lum ber.
A ll equipm ent a t th e m ine is b ra n d new . S eco n d -h an d m ach in ery could have been secured a t b a rg a in prices b u t w as considered a p o o r in v e st
m ent. E v e ry th in g w as p lan n ed to su it the condition. Efficient an d reliable op eratio n w as th e first co n sideration.
Four o f T h ese M ach in es A re C utting 2 ,5 0 0 T o n s o f C oal P er D ay
518 C O A L A G E — V ol.35, N 0.9
MECHANICAL CLEANING
+ O f Bituminous Coal Establishes N e w Tonnage Record
By H. O. ROGERS and F. G. TRYO N
M
e c h a n i c a l c l e a n i n g of bitum inous coal by w et and d ry processes established a new reco rd in 1929, the total o f cleaned coal produced being 37,143,- 000 tons, an increase o f 29.0 p e r cent over th e preceding year. P neum atic cleaning reg istered an increase of 54.3 p e r cent and w et w ashing o f all types a gain of 25.2 p e r cent.T h e se figures a re based on in fo r
m ation fu rn ish e d by the bitum inous coal o p erato rs, in the g ath erin g of w hich m a n u fa c tu re rs w ere asked to supply com plete lists o f installations.
In view of the rapid expansion of m echanical cleaning, th e re m ay be o th er plants not rep o rted . Included in the tonnage fro m w et w ashing is th a t o f five central w asheries operated by steel com panies: T h is is show n separately, because h ith erto such data have n o t been available. C entral w asheries located n ear the m ines and operated by m ining com panies are listed u n d e r th e heading “ A t the M in es.” T h e statistics do not em
brace the large tonnage of anthracite w hich is cleaned mechanically, nor B ra d fo rd b reak e rs and spiral sep
a ra to rs, although both o f the latter m ay p ro p erly be listed am ong devices fo r cleaning coal. F inally, hand- picking of bitum inous coal is not included.
In T a b le I I th e tonnage handled by each o f the principal types of w ash in g equipm ent is show n. O f the g ra n d total m echanically cleaned in 1929, pneum atic m ethods accounted f o r 15.7 p e r cent and w et m ethods fo r 84.3 p e r cent. Jig s continue the d o m in an t type of equipm ent in w et w ashing, co n trib u tin g over h a lf the
total tonnage last year. C o n cen trat
in g tables produced 3,660,000 tons individually, and in com bination w ith jig s produced 746,000 tons.
T able I — B itum inous Coal M echan ically C leaned by W et and P neum atic M ethods in the U n ited States, in N e t T o n s o f
Clean Coal
Per Cent of
1928 1929 Increase
B y wet methods
A t the m in e s .... a 2 l , 188,911 26,772,000 26 .3 A t central wash
eries operated
by consumers. a3 ,807,943 4,527,000 18.9 Total w e t .. 24,996,854 31,299,000 2 5 .2 B y p n e u m a t i c
m ethods... 3,786,185 5,844,000 5 4 .3 Grand total 28,783,039 37,143,000 29 .0 (a) Revised.
N e x t to the jigs, the larg est to n nage w as contributed by th e g ro u p
“ L a u n d ers an d U p w a rd - C u rre n t Classifiers.” T h is g ro u p accounted
Statistics Section, Coal Diwsion U. S. Bureau of Mines Washington, D. C.
fo r 7,103,000 tons. I t includes a n u m b er of diversified types, such as R h eo lav eu r lau n d ers, C hance sand- flotation cones, an d M enzies h y d ro sep a rato rs, as well as tu b w ashers.
M o st o f the g ro w th in recent y ears has been in th e groups, “ L a u n d e rs and U p w a rd - C u rre n t C lassifiers’*
and “ P n eu m atic P ro cesses.”
U n doubtedly, th e figures re p re senting the to n n ag e o f coal cleaned in 1929 a re less th a n th e capacity o f th e plants now installed. M an y plan ts did n o t begin to pro d u ce un til late in th e y e a r; o th ers o p erated a t less th an capacity. T h e to tal p ro d u ctio n o f all coal— cleaned a n d n o t cleaned
— a t the m ines provided w ith cleaning facilities is show n in th e last colum n o f T ab le I I . T h is p ro d u ctio n is tw o o r th re e tim es th a t o f cleaned coal pro p er, in dicating a fu rth e r larg e
T able I I — Bitum inous Coal M echan ically C leaned in 1929, Classified by T yp e o f W ash in g E quipm ent
(N ote that central washeries operated by consumers are included)
Total Pro
duction a t Number *— Cleaned Coal— » M ines Served
i of N et Per by Cleaning
Plants Tons Cent Plants
Wet methods:
Jigs... 150 19,598,940 5 2 .8 33,832,453
Jigs in com bination with concentrating tables... 9 746,185 2 .0 1,062,212 Concentrating tables... 14 3,659,976 9 .9 6,721,855 Launders and upward-current classifiersa... 55 7,103,086 19.1 21,481 *89 Unspecified... 9 190,808 0 .5 311,994 Total w e t... 237 31,298,995 8 4 .3 63,410,003 Pneumatic methods... 43 5,843,979 15.7 15,732,139 Grand to ta l... 280 37,142,974 100.0 674,606,590 (a) Includes Rheolaveur and also C hance processes. (6) T he total excludes duplication? where th e game mine is served by both wet methods and pneum atic methods.
S e p tem b er, 1930 — C O A L A G E 519
T able III— Bitum inous Coal M echan ically C leaned by W et and Pneum atic M ethods in 1929, by States, in N e t T o n s o f C lean Coal
(Central washeries operated b y consumers in Colorado and Pennsylvania are included) Per C ent of S tate O utput W et
M ethods (tons) A labam a... a 13,586,000 Arkansas and M ontana... 83,000 Colorado... 1,271,000 Illinois and Indiana... a 1,025,000 K entu ck y... a80 2,000 M ichigan and O h io . ... 362,000 Penn sylvania... 8,629,000 T ennessee... 308,000 W ashington... 968,000 W est Virginia and Virginia... 4,426,000
Pneum atic M ethods (Tons .
(a)
Grand to ta l... 31,299,000
(a) (a) 2.470.000
3,21*3,000 5.844.000
Total Tons 13.586.000
83,000 1.271.000 1.025.000
802,000 362.000 11.099.000 308.000 968.000 7.639.000 37.143.000
M echanically Cleaned
7 6 .8 1. 6
1 2 . 8
1.3 1.3 1.5 7 .8 5 .4 3 8 .4
5. 1 7 .0 oT o conceal individual operations the tonnage cleaned by pneumatic methods is combined with that by wet methods in Alabama, Illinois and Kentucky.
T ab le I V — Growth o f T otal T o n n a g e o f Bitum inous Coal M echanically Cleaned, 1906 to 1929, in N e t T o n s o f C lean Coal
(D ata for central washeries operated by consumers are not available before 1927)
Total Per Cent
of
W et Pneum atic at National
M ethods M ethods M ines Pro
Year (Tons) (Tons) (Tons) duction
1906... ... 9,251,946 9,251,946 2 .7
1 9 0 7 ... ... 11,269,518 11,269,518 2 .9
1909... ... 14,443,147 14,443,147 3 .8
1912... ... 17,538,572 17,538,572 3 .9
1913 . 22,069,691 22,069,691 4 .6
1915 . ... 20,873,727 20,873,727 4 .7
1917 . 25,483,696 25,483,696 4 .6
1918 ... 22,017,293 22,017,293 3 .8
1919... ... 16,884,062 (a) (a) 6 3 .6
1920... ... 17,984,289 (a) (a) 6 3.3
1921... ... 13,628,724 (a) (a)
(a) 6 3 .4
1923... ... 20,140,385 (a) 6 3 .8
1927... ... 21,119,441 3,650,584 24,770,025 4 .8 1928... ... c 2 l , 188,911 3,786,185 24,975,096 5 .0 1929... ... 26,772,000 5,844,000 ^2,616,000 6 .2
(a) D ata on pneum atic cleaning, which began in 1919, are not available for 1' th ose years, however, was small. (6) Includes an estim ate for th e tonnage cleanec figures.
W ashed at Central Plants
Operated by Consumers
N o data N o data No data N o data N o data N o data N o data No data N o data N o data N o data N o data 2,922,022 c3,807,943 4,527,000
Grand Total N o data N o data N o data N o data N o data N o data N o data N o data N o data N o data N o.data N o data 27,692,047 28,783,039 37,143,000
T ab le V — G row th o f Bitum inous Coal M echanically C leaned at the M in es by W e t and Pneum atic M ethods, by States, in N e t T o n s o f C lean Coal
(N o te th a t central washeries operated by consumers in Colorado and Pennsylvania are excluded, because of lack of data in the early years)
State 1907
Alabam a... 3,750,418 Arkansas and Oklahoma ... 150,507 Colo., N. Mex. and M o n t... 567,217 Georgia and Oregon... 154,959 I llin o is ... 2,465,767 Indian a... 21,659 K entu cky... 88,678 M aryland... 9,856 M ich ig a n ... ...
M issouri... 72,227 Pennsylvania and O hio... 2,583,202 Tennessee... 543,333 T ex a s...
W ashington... 644,501 W est Virginia and Virginia... 217,194 Other States...
1913 7,210,588
47,292 1,301,428 92,662 3,664,928 65,499 162,880
*145,840 118,681 5,669,622 624,426 21,761 1,343,120 1,539,541 61,423
1917
! 1,408,051 989,405 83,344 4,651,154 48,065 211,689 34.693 174,642 37,617 3,466,860 630,621 23,817 1,475,529 2,248,209
1927 13, i 53,643
14,896 637,409 560,642 250,282 309,262
*155,190
‘ 3,578.739 344,562 820,481 4,944,919
1929 13.586.000
10,000 513.000 527.000 498.000 802.000 157.000
’ 7,6 0*8,0 Ó Ó 308.000 968,600 7.639.000
T otal at m ines... 11,269,518 22,069,691 .25,483,696 24,770.025 32,616,000
crease, culm in atin g in a peak of 25,- 480,000 to n s in 1917.
T h e re a fte r the to n n ag e cleaned by w et w ash in g declined, and it w as n o t until about 1924 th a t the decline w as checked. Since then, active in terest in p re p a ra tio n and the in tro d u ctio n o f im proved equipm ent have led to rap id expansion. In 1929 th e to n nage cleaned by w et w ash in g a t the m ines rose to a new high record, e x ceeding by 1,288,000 to n s th e p rev i
ous hig h m ark set in 1917.
P n e u m a tic cleaning w as first a p plied on a com m ercial scale in 1919.
In the y ears follow ing it has g ro w n by leaps and bounds. A s a resu lt of the com bined p ro g ress in both w et and pneum atic m ethods, th e to tal to n nage cleaned at the m ines now show s a large g ro w th ov er 1917.
T ab le V gives a clear view o f the change in tonnages w ashed by states.
B ecause o f th e lack o f d a ta fo r the e arlier years, it is necessary to e x clude th e cen tral w asheries operated by steel com panies. A labam a an d th e V irg in ias show a co n sisten t increase back to th e earliest record. Illinois, on th e o th e r hand, increased rap id ly from 1907 to 1917, an d th e re a fte r sh arp ly declined. P en n sy lv an ia show s a large increase in th e p erio d b efo re th e W o rld W a r, follow ed by a re cession ; how ever, it has re g istered a larg e increase since 1927. C olorado and W a sh in g to n , am o n g o th e r o f the states w h ere w ash in g is im p o rtan t, recorded an increase up to 1917, w hen follow ed a perceptible decline.
In 1929, to p ro d u ce th e 37,143,000 to n s o f cleaned coal, a total o f 3,442,- 000 tons o f re fu se w as rem oved.
T h is m eans th a t o f th e to tal m aterial treated by cleaning plants, 8.5 per cent w as re fu se a n d 91.5 p e r cent w as m arketable product.
increase in cleaned coal fo r 1930.
A labam a led the states w ith a total o f 13,586,000 to n s o f m echanically cleaned coal. P en n sy lv an ia w as sec
ond, w ith 11,099,000 tons, and W e st V irg in ia (in clu d in g fo r statistical purposes V irg in ia ) w as th ird , w ith 7,639,000 tons. D evelopm ent of pneum atic cleanipg has been g re ate st in so u th ern W e st V irg in ia and Pennsylvania. T h re e o th e r states re- ' p orted production by pneum atic m ethods, but th eir tonnages cannot be shown.
T h e long-tim e tre n d ' in w ashing is show n in T able IV . F o r coal w ashed a t the m ines, the reco rd dates back to 1906, in w hich y e a r a total o f 9,251,000 to n s of coal w as cleaned ' by w et m ethods. F o r th e n e x t ten ..years w ashing show ed a steadv in-
T H E S T A T I S T I C S on th e o u tp u t o f bitum inous coal cleaned m echanically last y ear, m ad e public by th e U . S.
B ureau o f M ines a t W a sh in g to n , D . C., Sept. 6, m ake a p a rtic u la rly a p p ro p ria te in tro d u c tio n to th e m eeting o f the C oal D ivision of th e A . I. M . E . a t P itts b u rg h , P a ., Sept.
11-13, w here p re p a ra tio n w as one o f th e m a jo r p r o g ram them es.
T h ro u g h th e courtesy an d co -op eratio n o f th e D ivision, a b stra cts o f a num ber o f th e p a p e rs p rese n ted a t th e P itts b u rg h m eeting a re published in this issue o f C oal A g e , beginning a t page 527. A b s tra c ts o f o th e r p a p e rs a n d a sto ry o f th e discussion ta k in g place a t th e m eeting will be published in O ctob er.
■ 520 C O A L A G E — V ol.35, N o .9
White Old Cream
L i Gr e e n Yellow
Ugfo Slug
P in k
Dark Ian Dark Red Dark Green
< < T ’M N O T fam iliar w ith w h a t’s in p a in t,” rem ark ed a m ine su- J L p erintendent, “b u t I do know w h a t it does. I ’ve seen m any a p ain ted w ooden bridge outlive bridges o f steel w hich w ere n o t properly m aintained. N otice how well p re served are som e of those old covered w agons a fte r a h undred years o r m ore. Iro n m ay be strong, b u t it is n o t durable unless regularly painted.”
H is com m ents explain w hy large coal com panies in both the an th racite and th e bitum inous fields take such pains in p ainting equipm ent and stru c tu ra l su rfaces in preparation plants and o th er buildings. B u t there is fa r m ore to p ainting than w as
pointed out by th e su p erin ten d en t.
O f im portance v irtu ally equal to the preservation quality of p ain t a re its pow ers to please the eye and to illum i
nate by reflection o f n atu ra l and a rti
ficial light. Finally, painting, p a r
ticularly in light colors, encourages cleanliness.
T o m ake w ork su rro u n d in g s pleas
ing to the eyes of em ployees should be the goal of every in d u strial. T h a t objective is doubly salu tary to those w ho directly serve the public as does the coal industry. • A few y ears ago several of the m odern b reak ers in the
a n th racite field w ere painted in colors w hich gave a m axim um o f illum ina
tion and pleased th e eye. T h e results inspired the ex ten sio n of a stan d in g invitation to the public to visit these plants.
E xam ples of this p ractice a re the M arv in e b reak er o f the H u d so n Coal Co. and the B ak er b rea k er of the Glen A lden Coal Co. Signboards facing m ain highw ays invite passing m o to rists to inspect these plants. R e
g a rd in g the value of this practice, a su rfa c e forem an rem arked : "“W h en w e take a v isito r th ro u g h this breaker, he sees a huge s tru c tu re built som ew hat like a greenhouse, w ith w hite-painted gallery ceilings.
H e is im pressed and gets a new view of the m iner, the o p erato r, and th e in d u stry a t large. I f we could send a continuous stream o f people th ro u g h this p lan t, the trouble w ould be rapaid, even though they g o t in o u r w ay .”
Illum ination has become a science to which p ain tin g has m ade a substantial contribution. W ith o u t paint, n atu ral and artificial light cannot be p ro p erly diffused and reflected. F ig . 1 show s graphically th e relative light-reflect
ing values of v ario u s p ain t colors.
W h ite n a tu ra lly has th e highest r a t
ing. I f black w ere listed, th e g ra d a tion o f tin ts dow nw ard w ould end R elative L ight-R eflecting Q ualities o f Paint Colors, Per Cent
PAINTING
+ Has a Place in M i ne Modernization
By T. J. M ALO N EY
Nczv Jersey Zinc Co.
New York City
S e p te m b e r, 1 9 3 0— C O A L A G E 521
L e f t — P u m p R o o m s , T o o , Sh ould Know the
Paint Brush
Center — In W ell- R egulated P l a n t s Floors A re Kept
Painted
R igh t — P ain tin g Induccs O rderliness in Plant Interiors a t about zero, w ith g ra y in about the
m iddle o f th e scale. B ecause light reflection is low in th e d a rk e r shades, they should n o t be used in places difficult to illum inate. T h e degree to w hich tin ts of a p a rtic u la r color are lig h ter o r d a rk e r th a n a chosen sta n d a rd determ ines th e reflection ran g e of th a t color. T h e re is no definitely fixed g ra y , green, o r blue.
In recent y ears cleanliness has taken on a new m eaning in in d u stry . M odern p lan ts a re covered w ith p ain ts w hich can be easily w ashed, and the process is repeated frequently.
P lan t-k eep in g schedules call fo r w ashing o f th e w indow s m onthly.
E v e n the floors a re painted and th e re a fte r scrubbed regularly. C lean
liness is suggested by w hite and light tinted paints. A light w all has a psychological effect on w orkm en, e n couraging them to keep th e su rfa c e clean, fo r any d irt splotch is im m edi
ately noticeable to th e eye.
F la t p ain ts an d eggshell pain ts of quality can be as easily w ashed as p ain ts th a t p roduce a glossy surface.
T h e pigm ents in these pain ts consist o f finely divided particles w hich give a sm ooth, even su rfa c e to flat p a in ts ; they also resist yellow ing as well as glossy paints. C ertain gases, such as h ydrogen sulphide, su lp h u r dioxide, and am m onia, are ruin o u s to all pain ts except those specially com pounded to
resist th e ir chem ical attack. N e ith e r zinc oxide n o r lithopone, th e p ig m ents com m only used in light in te rio r paints, are discolored by these gases.
N u m ero u s pigm ents a re com p ounded fo r p rotective purposes.
These, com bined w ith th e p ro p e r vehicle, should re su lt in a p ain t w hich is chem ically p erm anent, o f high physical stren g th , capable o f keeping
o u t air and m oisture, elastic, and ru st inhibitive. Som e pigm ents— g rap h ite is one— stim ulate r u s tin g ; they, th e re fore, should n ev er be used in a p rim ing coat. F ollow ing is a list o f p ig m ents th a t ra te high as ru st in hibitors : zinc d u st, sublim ed blue lead, red lead, carbon black, zinc chrom ate, and basic lead chrom ate.
S u itab ility of a p ain t fo r galvanized su rface s largely depends on its p h y s
ical p ro p erties. In addition, fo r iron and steel su rfaces, it m ust have chem
ical p ro p erties to p rev en t corrosion.
T h e o u tstan d in g req u irem en ts o f a pain t fo r galvanized sheet a r e : ( 1 ) T h a t it be highly distensible ov er a long period o f ex p o su re to w e a th e r
in g ; (2 ) th a t it have the p ro p e rty o f th o ro u g h ly w ettin g the su rfa c e even a fte r the film has o x id ize d ; ( 3 ) th a t it adhere tenaciously. A p ain t o f zinc d u st and zinc oxide has g re a t affinity fo r galvanized iron. B est resu lts are
o btained w hen it is used both in the p rim in g coat and in th e finish coat.
Its light g ra y color is pleasing and show s little d irt.
T h a t ro ta ry dum ps, conveyors, and sim ilar equipm ent re q u ire a p ro te c tive covering is p roved by th e fact th a t the m a n u fa c tu re r alw ays pain ts them . U su ally th re e o r fo u r coats a re applied— one o r tw o p rim e r coats, a coat o f p rotective p a in t o f an o th er color to show up any “ h olidays” or spots w hich have n o t been com pletely covered, and finally a d a rk colored enam el o r lacq u er finish. R ep ain tin g o f som e of this eq uipm ent is difficult, b u t th e jo b can be done to econom ic a d v an tag e even a t the expense o f a reasonable loss of o p e ra tin g time.
A ssu m in g th a t all stru c tu ra l iron a n d steel is p ain ted p rim a rily fo r protection, p ro p e r p re p a ra tio n o f the su rfa c e fo r p a in tin g is fundam ental.
R u s t u n d e r a coat of p a in t is unseen and will d e stro y n o t only the p ain t film over it b u t th e m etal itself.
M ill scale will also ru in a paint job.
A few m onths a f te r p ain t has been applied over th is scale it is liable to crack and peel. E x a m in a tio n will show th a t the m ill scale is peeling and ta k in g th e p ain t w ith it. I t is best to let the su rfa c e w e ath e r fo r a period to allow the scale eith er to ru s t o r fall off. T h e n go over it w ith w ire b ru sh es and scrap ers and rem ove all rem ain in g scale and p ow dered ru st.
N ew galvanized sheets p resen t a sm ooth su rfa c e w ith no pores o r pits into w hich a p a in t can p e n e tra te fo r m echanical anchorage. E x tre m e changes in te m p e ra tu re also have a m arked effect on the adherence o f th e p ain t. A s a re su lt o rd in a ry p ain t will peel in larg e sheets, leaving th e T h is Breaker Is O pen to Public Inspection. O f Course,
It Is P oin ted In side and O ut
522 C O A L A G E — V o l.35, N o .9
b are m etal exposed. F u rth e r diffi
culty m ay be encountered due to the adhesion o f lubricants used in the sheet m a n u fa c tu rin g process.
A ll th in g s considered, w eathering fro m tw o to six m onths is the best m ethod o f p re p a rin g galvanized s u r
faces. T h is will o rd in arily rem ove an y g rease p resen t and a t th e sam e tim e roughen o r etch the su rface of the m etal. R em oval of the grease allow s the p a in t to come in direct contact w ith the m etal and the ro u g h ened su rfa c e provides m echanical anchorage. H o w ev er, sandblasting is a m ost effective p re p a ra to ry tre a t
m ent fo r all conditions of the s u r
face. I t cleans and etches in one op
eratio n , it is su p erio r to any chemical tr e a tm e n t; b u t it is costly and lim ited in application.
N o single m ethod o f chemical su rfa c e tre a tm e n t can be depended upon to produce universally good re sults w ith every paint. A practical and econom ical chemical m ethod of cleaning and etching in a single op er
ation a su rfa c e contam inated w ith grease is to apply liberally a m ix tu re o f d e n atu red alcohol (65 vol
u m e s), toluol (3 0 v o lu m es), carbon tetrac h lo rid e (5 v o lu m es), and hydrochloric acid (5 volum es).
S p ra y p a in tin g is economical on su rfac es th a t dem and little blocking
out. S p ray guns can be used to ad vantage on in te rio r w alls and ceilings as well as the e x te rio r su rfa c e o f buildings, tanks, stacks, and stru c tu ra l steel. B ut b ru sh in g has by no m eans been displaced entirely.
W h e re in terio rs m u st be painted w hile operations are in progress, b rushing o ften is indispensable. B e
cause o f the intricacy o f its shape, m achinery is best repainted by brush.
P a in tin g schem es used in som e of the breakers in the hard-coal fields m ay well serve as exam ples o f the best m ine-plant p ain tin g fro m the stan d p o in t of cleanliness, protection, illum ination, safety, and economy.
T h e B ak er b reak er is a show place of the industry. A ll ceilings are painted w hite fo r illum ination and ap p ear
ance. W alkw ays a re covered w ith ru b b er m ats and the floors are painted a b rig h t orange. R oofing and stru c tu ra l m em bers are covered w ith gloss p ain t in light colors. All m achinery is black and lubrication cups are red fo r contrast. B rig h t
oran g e p a in t is applied to the w ooden ro ck er arm s on th e shaking screens.
T h is p lan t is as clean and well kept as an y p o w er plant.
A n exam ple o f a w ell-painted p o w er house is the O lip h a n t p lan t of th e H u d so n Coal Co. In the engine room ceilings a re painted w hite, as are th e w alls, w hich a re finished w ith a black dado to a heig h t o f ab o u t 5 ft. above the floor. A ll m achinery and stru c tu ra l m em bers are black. A gloss p ain t is used in every case.
T h e w alls a re rep ain ted every five y ears by b ru sh and sp ra y g u n ; they are w ashed dow n once a year. T h e p um p room , w hich is in th e basem ent below th e engine room , also is done in black and w hite, th e la tte r color also being used fo r w ater and steam lines. T h e pum ps a re covered w ith a h e a t-re sistan t paint.
In te rio rs o f m ine shops should be painted in lig h t colors. I t is o f in
te re st to note th a t even blacksm ith shops a re being painted today at som e plants. T h is is largely possible because sm oke and gas from the fo rg es are n o t allow ed to escape into th e in te rio r of th e building. T h ese shops need all th e light th a t can be m ade available and should be painted w hite. I n supply room s ceilings, w alls, and racks should be painted w hite.
S ep tem b er, 1930 — C O A L A G E 523
ENGINEERING FORETHOUGHT
+ Expedites Operation of Kansas Stripping
A T T H E N o. 15 o p eratio n of the Z A P itts b u rg & M idw ay Coal -L- M in in g Co., located a t M ineral, 22 m iles so u th w est o f P itts b u rg , K an., 22 in. o f coal u n d e r a p p ro x i
m ately 26 ft. o f o v erb u rd en is being stripped. In th e tak in g o f this seam ab o u t 16 cu.yd. o f o v erb u rd en m u st be handled fo r every to n of coal m ined. A t th e average daily ra te of output, w hich is ab o u t 1,500 tons, th is p lan t will produce ab o u t 250,000 tons in 1930 and w ill have a life of about 21 years. I t is a new operation, w hich w as s ta rte d in N o vem ber o f last y e a r and began to load coal the first of th is year.
P u m p in g has been alm ost entirely elim inated by th e su b stitu tio n of n a tu ra l d rain ag e ditches ov er th e en
tire area of th e p ro p erty and in the p it itself. T ra n sp o rta tio n has been simplified by avoiding the laying of tra c k into th e pit. In stead , th e tra c k is k e p t on the high wall an d th e coal tra n s fe rre d fro m th e lo ad er to the cars by a skip o r bank m achine.
T ra c k s are a rran g ed in a loop w hich facilitates the h an d lin g o f th e en tire o u tp u t w ith absolutely no in terferen ce betw een trip s. A t th e p rep ara tio n - p la n t end the flow of coal fro m the dum p h opper and also over th e sh a k in g screens is controlled by a variable- speed transm ission.
T h e seam m ined is th e M ineral.
I t lies 320 to 330 ft. above th e M is
sissippi lim estone and 80 to 90 ft.
above the C herokee seam , fro m w hich o rig in ates m o st o f th e strip p ed coal in the K an sas field. O n the p ro p e rty th e dip of th is form ation is about 22 ft. to the m ile in the direction of N o rth 70 deg. W e st. B eing on a p rairie, th e p ro p e rty is flat and th e cover over th e coal u n ifo rm ly thick w ith a m axim um o f ab o u t 35 ft. T h is last figure gives a ratio of o verburden to coal w hich is about the economical m ax im u m w ith the efficiency o f p re s
ent types of m achines u n d er co n d i
By ALPHONSE F. BROSKY
Associate Editor, Coal Age tions encountered on the p ro p e rty and
the e x istin g sta te o f th e m arket. O n ly a few y ears ago th e m ax im u m strip - pable cover fo r th is p ro p e rty w as held to be about 30 ft. D irectly above th e coal is 8 to 30 in. o f h a rd black slate and above th a t is 8 to 12 ft. of shale w hich is capped w ith clay m e rg ing to soil fo r the rem ain in g distance to th e su rface. T h is o v erb u rd e n is of such a n a tu re th a t it m u st be blasted. T h o u g h so ft, th e shales are distinctly stratified, an d fo r this re a son th e spoil m aterial stacks well.
B ecause of th e shape o f th e p ro p erty, the coal will be strip p ed fro m fo u r tra c ts consecutively. In each case a stra ig h t box cut w ill be esta b lished on th e b o u n d a ry line and m ade to sw eep evenly across th e tra c t.
M aintenance o f th e stra ig h t cu t is possible because o f th e u n ifo rm ity o f the fo rm atio n s and th e flatness o f th e surface. T h e w id th o f th e p it w ill be k ep t to ap p ro x im ately 65 ft. and its m ax im u m len g th will be ab o u t 5,200 ft. in N o. 1 pit.
Coal is uncovered by a 12-cu.yd.
B u c y ru s-E rie 385-B electric shovel w ith a 7 8 -ft. boom and a 52-ft. stick.
T h is u n it handles ab o u t 137,000 cu.yd. p e r m o n th p e r 8 -h o u r sh ift.
A s th e shovel is do u b le-sh ifted d u rin g th e six w arm m onths and trip le sh ifte d d u rin g th e six cold m onths, its m o n th ly capacity is tw o to th re e tim es th a t given fo r th e sin g le-sh ift ra te of operation. Incidentally, th e ratio of ru n n in g tim e betw een th e strip p in g u n it on the one hand and th e loader and the tipple on th e o th e r is such th a t w hen the fo rm e r operates 24 h o u rs a day, the la tte r ru n 8 h o u rs
a day.
T im e studies show th a t d u rin g only 21 p e r cent o f th e to ta l o p e ra tin g tim e o f .th e strip p in g shovel is th e bucket in th e bank. F o r th is reason it has been im p o rta n t to m inim ize th e angle of sw ing of th e bucket. U sually, it is kept to 90 deg. o r less. M aterial re q u irin g th e fa rth e st reach o f the bucket is deposited n e arest to the
•This Sh ovel H an d les A b ou t 137,000 C u .Y d. Per M onth at a S in gle-S h ift Rate
524 C O A L A G E — V ol.35, N o .9
A Bulldozer Blade Rem oves Dirt Left on the Coal by the S h ovel
V ariable-Speed Transm is
sion o n Shaker Screen
T h is A u xiliary Shaker Rem oves Fines From Coal G oin g to the Crusher
s tra ta are such th a t the high wall stan d s well, haulage tra c k s are not ca rried into th e p it b u t are m aintained on th e su rfa c e w ithin a few feet of th e b rin k . T h is system of tra c k lay
o u t b rin g s a nu m b er of operating econom ies. I n it th e sh iftin g of track is sim plified, th e roadbed is m ore solid, g ra d e s are elim inated, and op-
G ood Coal Is Separated From Impurities in T his Rotary Breaker shovel to fo rm a pilot o r secondary
wall, over and behind w hich the m ain m ass of the spoil is piled. T h is p ra c tice keeps th e angle of sw ing u n ifo rm and relatively n arro w . A n o th er p ra c tice th a t is closely follow ed is to root as m uch as possible of the m aterial into th e pit. D ue to th e soundness o f the shale s tra ta im m ediately over the coal, p re p a ra tio n f o r loading is ad eq u ate a f te r the su rface of the coal has been cleaned w ith a scraper blade propelled by a caterp illar tracto r.
B ecause of th e flatness of the s u r
face of this p ro p e rty and because the
T ip p le at Pittsburg &
M idw ay N o . 15 Stripping
S e p tem b er, 1930 — C O A L A G E 525
eratio n o f th e shovels is not im paired by th e presence of track .
W ith this a rran g em en t, it is neces
sa ry to tra n s f e r coal fro m th e p it to cars on th e hig h w all by a skip o r a b ank m achine. Coal is loaded by a 2^-yd. horizo n tal th r u s t ty p e of shovel. B y reaso n o f its p e rfo rm an c e ch aracteristics, chiefly its crow ding action parallel to th e b ed d in g planes of th e coal, th is u n it gives a m a x i
m um o f coarse sizes. A s th e capacity o f th e skip is 7 to n s, th re e passes of th e shovel fill th e skip.
R em ote loading th ro u g h th e agency o f th e skip has an ad v an tag e in th a t th is u n it can be spotted n e a r the loader. I n consequence, th e sw ing o f th e lo ad er can be k ep t to less th a n 45 deg. T h e capacity and speed of these tw o u n its are so p ro p o rtio n ed th a t th e skip can be raised to th e s u r
face track , em ptied into th e cars, and re tu rn e d w hile th e loader is filled and placed in to position ready to em pty in to th e skip.
In the accom panying sketch is show n the general layout o f th e tra ck s schem atically. I t will be noted th a t n e a r th e p it th e shape of the tra c k system is an elongated loop w hich is fu rth e r subdivided into tw o sm aller loops by a sh o rt cross line m idw ay of th e p it ex trem ities. A single tra c k ru n s fro m the loop to the tipple dum p. T h is tra c k is o f sta n d a rd gage and is laid w ith 70-lb. rails.
T h e tem p o ra ry track , th a t n e a rest to a n d paralleling th e pit, is slued by a tra c to r. T h is loop layout altogether elim inated in terferen ce betw een trip s, o f w hich th ere a re b u t tw o. A trip consists of th re e 35-ton S a n fo rd -D a y 8-w heel dro p -b o tto m cars w hich are hauled by a 25-ton V ulcan gasoline locomotive. W ith stability an d ru g gedness o f th e tra c k and th e absence o f grades, th e larg e ca r has speeded tra n sp o rta tio n and p roved econom i
cally advantageous. T h e drop-bottom fe a tu re has speeded u p th e unloading o f th e car, a trip being em ptied over a 180-ton dum p h opper in about 35 seconds. T h is h opper is su p erim posed by tw o track s and so th e cars
can be dum ped w ith o u t sh iftin g , th o u g h rev ersed end fo r end.
L ittle p u m p in g is req u ired f o r th e d rain a g e o f th is p ro p erty . D ep e n d ence is placed en tirely on ditches fo r the rem oval o f w a te r fro m both the su rfa c e and th e open pit. In o rd e r to do this effectively, th e su rfa c e has been closely co n to u red an d a to p o graphical m ap p re p a re d w hich show s practically all irre g u la ritie s in th e s u r
face. A stru c tu ra l m ap of th e coal bed also has been p re p ared on close co n to u r in terv als fro m th e d rill logs.
O n th e su rfa c e ditches a re e stab lished so as to follow th e co n to u r lines, a p rim a ry d itch being placed a t in terv als of ab o u t 640 ft. T h is ditch breaks into th e w atershed.
I t is m ade as m uch as 18 ft. deep an d is d u g w ith a D iesel d rag lin e u sin g a f-y d . bucket. T h e a re a betw een th e p it and the m ain ditch is d rain ed by a secondary d itch w hich is m aintained w ith in 10 to 15 ft. of th e hig h wall.
T h e seco n d ary ditches a re excavated by a tra cto r-p ro p elled d itch er. W h e re th is secondary ditch crosses a d ra w o r a ravine d escending into th e pit, an ea rth w o rk dam is th ro w n u p by th e strip p in g shovel an d th e w a te r im pounded in th e area, w hich seldom exceeds one acre, is rem oved by a sm all p o rtab le pum p. S im ilarly, in th e p it, ex cep t fo r sm all sw ags w hich are pum ped, w a te r is conducted aw ay fro m the w o rk in g a re a by ditches.
M ax im u m efficiency in th e p re p a ra tio n o f coal on th e tipple has been gotten by th e in stallatio n o f variable- speed tran sm issio n u n its in th e d riv es of th e recip ro catin g fe e d e r u n d e r the d um p h o p p er an d th e sh ak er screen, coal being tra n s f e rre d fro m one to th e o th e r by m eans o f an ap ro n -ty p e conveyor. T h is a rra n g e m en t allow s an ex act a d ju stm e n t o f the feed into
th e tipple. D u rin g perio d s w hen the to n n ag e com ing fro m th e p it is re la tively low these u n its m ay be slow ed d o w n ; if th e coal en ters the p la n t w et o r ‘if a larg e to n n ag e is to be handled the d riv es can be speeded up. T h is is accom plished sim ply by tu rn in g a handw heel on th e tran sm issio n .
T h e u n it used fo r th is p u rp o se is th e R eeves variable speed tra n s m is sion, a N o. 3 f o r th e feed er an d a N o. 6 fo r th e sh a k e r screen. In the m ain, this m echanism consists of tw o p a irs o f bevelled disks, each spline m ounted on one o f tw o parallel sh a fts, w hich a re connected by a V -sh ap ed belt to fit a V -sh ap ed th ro a t fo rm ed by th e disks. T h is tra n s m is sion can be seen in one o f th e accom p an y in g illu stratio n s. A d ju stm e n t o f th e speed is accom plished by sh iftin g levers w hich increase th e g ap betw een one p a ir of disks a n d sim ultaneously d ecrease th e gap betw een ih e oppo
site pair. In consequence, w ith one s h a ft being d riv en a t a co n stan t speed fro m th e source o f pow er, th e speed o f th e opposite s h a ft can be increased o r decreased by th e 'a d ju s tm e n t of these disks so th a t th e V -b elt tu rn s on a la rg e r o r sm aller diam eter.
A single-roll c ru sh e r is installed in th e tipple a t th e head end o f th e co n v ey o r fro m th e d um p h o p p er an d is . used to cru sh th e m in e -ru n coal w hen th e m ark et dem ands sm aller sizes.
B e fo re e n te rin g th e c ru sh er, how ever, the m in e-ru n is passed ov er an a u x iliary sh ak in g screen an d th e m inus size is bypassed. T h e tipple also is pro v id ed w ith ra p id sh ak ers w hich sep arate m inus 1-J-in. coal into th re e sizes, l^-xf-in. an d -Jx-^j-in. and f^xO -in. Coal clinging to re fu se r e jected fro m th e picking table is d i
v e rte d to a ro ta ry b re a k e r w hich yields a 1-J-xO-in. clean coal.
A Sk ip Is U s ed to Transfer the C oal From the P it to Cars on a H ig h W all
526 C O A L A G E — V o l.35, N o.9
PROBING PROBLEMS
+ O f Pneumatic Cleaning of Bituminous Coal
By TH O M AS FRASER
Consulting Engineer, Hydrotator Co.
Hazleton, Pa.
A
N U M B E R o f u n fo re seen p ro b lem s have been b ro u g h t to light - in th e few y ears th a t d ry m e th ods of tre a tm e n t have been in com m ercial use. T h e pneum atic concen trato rs first adapted to coal had already been developed to a fa ir efficiency— low ra tin g s n o tw ith stan d in g
— in o re dressing. T h e y w ere m ore p e rfe c ted relatively th a n the general technology of d ry cleaning. F o r this reason, the m a jo r difficulties en
countered w ere in the accessory op
eratio n s ra th e r th a n in th e functioning o f th e cleaners them selves. T h e cru d ities o f a new technology w ere fu rth e r agg rav ated , in som e cases, by m eagerness o f ap p ro p riatio n s, w hich precluded adequate storage bins and o th e r facilities recognized as indis
pensable to o lder types o f cleaning plants.
D ry cleaning is now sufficiently established th a t w e m ay critically e x am ine equipm ents and operations au x ilia ry to th e pneum atic table and its fu n ctio n in g . T h e processes have now been so sim plified, w ith respect to p re-sizin g o f th e raw coal and the q u an tity of a ir circulated, th a t stinting o f ex p en d itu res fo r a u x iliary equip
m ent is n o t necessary to keep the p er-to n cost o f installation in line w ith com plete an d w ell-designed plants of o th e r types. F u rth e rm o re , sufficient o p era tin g experience has been ac
cum ulated to a scertain th e conditions m ost conducive to effective operation
F ro m a p ap er p resen ted a t th e P it t s bu rgh m e e tin g o f th e A .I.M .E ., S ep t. 11.
and
of dry-cleaning m a c h in e s; a t least the essentials o f a definite technology o f d ry cleaning have been established.
T h e real problem s in d ry cleaning have been relatively few b u t difficult.
T h ey a r e : ( 1 ) P r o p e r sizing o f raw coal to su it th e cleaning p ro ce ss; (2 ) h an d lin g o f raw coal w hen it is d e
livered w et fro m the m in e ; ( 3 ) d u st collecting; and ( 4 ) m aintainance of u n ifo rm ity in cleaning p erfo rm an ce.
I t is ap p a re n t th a t these problem s concerned n o t th e design an d a d ju s t
m ent o f th e cleaning m achines b u t ra th e r th e servicing o f these m achines and th e conditioning o f the raw coal b e fo re trea tm en t.
S izing o f th e ra w coal, w hen dry, has becom e a fa irly sim ple m echan
ical op eratio n since th e in tro d u ctio n of m o d e m co n cen tratin g m achines capable o f h an d lin g a w ider ran g e o f sizes. Y e t th e cleaning o f ex trem ely fine sizes still involves som e screening difficulties even w hen th e coal is dry.
T h e p ractice o f tre a tin g unsized feed on s tra tify in g tables, w hile elim inating altogether th e necessity fo r presizing of th e feed, has in tro d u ced a new condition calling fo r a certain degree o f u n ifo rm ity in size com position.
T h is m ay also be considered a m atte r o f size control a n d involves som e conditioning of th e ra w coal b efo re treatm ent.
ROBERT MacLACHLAN
Plant Superintendent Champion No. 3 Preparation Plant Pittsburgh Coal Co.
Library, Pa.
M o st of th e difficulty in screening lies in th e h an d lin g of w et coal. E x cessive m o istu re m ay also affect the op eratio n o f pneum atic tables, p a r
ticu larly if th e m o istu re fluctuates.
H o w ev er, th e cleaning o peration is n o t affected, as a rule, un til th e m o istu re m easu rab ly exceeds the p ercentage th a t causes tro u b le in fine screening. I n e ith er w et o r d ry processes, w ater, in one w ay o r a n other, accounts fo r m uch of the op
era tin g trouble. T h e re fo re , if th e coal can be delivered in a u n ifo rm ly d ry condition, a d ry p lan t should provide a sim ple an sw er to th e clean
in g question.
A fte r being in su red a p ro p erly con
ditioned feed, u n ifo rm p erfo rm an ce depends largely on th e m echanical equipm ent available to supply an u n in terru p ted , u n ifo rm flow of ra w coal, a ir, and pow er. M ain tain an ce of favorable o p eratin g conditions w ith o u t in te rru p tio n is necessary to u n i
fo rm ity o f p ro d u ct, w hich is fully as im p o rta n t a s 'p u rity .
F o r sizing d ry sm all coal p re p a ra to ry to a ir cleaning, p ractice is v ir
tually stan d ard ized on high-speed v ib ratin g screens. T h e h ig h -fre quency stro k e o f sm all am plitude has established its su p e rio rity fo r capacity and freed o m fro m blinding. V ib ra t
in g screens o f the inclined, g ra v ity -
S e p tem b e r, 1 9 3 0— C O A L A G E 527
