Skip to main content

Full text of "Design of a 500 ton bituminous coal washing plant"

See other formats

Design of a 500 Ton Biti 
Coal Washing Plai 

Illinois tostirase 

of Technology 


AT 54 

Sawtell, H.J. 
Design of a 500 ton 
bituminous coal washing 

For Use in Library Only 





H.J. Sawfell 








June I. 1906 









To make the operation of the plant more easily under- 
stood, and to show the development reached in this work. a 
short account of the action of the machines is here given 
with a short history tracing the development from the crude 
early machines to those now in use. The descriptions are 
necessarily brief. 

By coal washing is meant the process of separating the 
impurities with which the coal is mixed as it comes from 
the mine by means of special machines which use water as 
an accessory. 

The coal as it comes from the mine consists of coal 
proper^ jand impurities, such as slate, sulphur in the form 
of pyrites or calcium, 'and magnesium sulphate, bone coal, 
and fire clay. With some exceptions these substances have 
a higher specific gravity than the pure coal, which is about 
1.28 or 1.30, and it is this fact that makes their separa- 
tion possible. 

The principle of the washer is demonstrated when two 
substances of different specific gravities are shaken to- 
gether in a box. The heavier substance will settle in a 
flayer on the bottom, while the lighter substance will re- 

main in a layer on top. This would not occur in a 
vacuum; water is a better medium than air. 

The method of washing to separate materials of diffe- 
rent specific gravities is a very old one. It has been 
used in mining operations for a long time. In its use with 
precious metals the process is reversed, it being desired to 
save the heavier substance and get rid of the lighter. 

Almost every conceivable arrangement has been used; 
the process has been developed from the simple trough washer 
to the senfcative jigs. Some have tried air as the medium, 
others use centrifugal force, but none have proved as satis- 
factory as the jigging method. 

The simplest washer is known as a trough washer, and 
consists of an inclined trough with cross riffles at regul- 
ar intervals. The coal is fed at the top and is given suf- 
ficient force by the water flowing down the trough to carry 
the coal over the riffles with it, leaving the slate on the 
recesses. At the bottom is a draining screen which sep- 
arates the coal from the water. The slate is removed at 
intervals by an attendant with a rake. This is a very 
crude and imperfect method, and requires an excessive amount 
of water. 

An improvement on the simple trough washer is the 
Elliott trough washer. This consists of an inclined trough 
in which a flight conveyor operates. The coal and impur- 
ities are fed at the center of the trough. Water enters 
at the top. The flights on the conveyor act as the riffles, 

the water washing the coal over the flights. The 
impurities are carried up the trough and are discharged 
at the top end. The coal passes down the trough to a re- 
ceiving car, passing over a draining screen before it enters 
the car. The process is thus continuous and requires but 
little attention. Its marked simplicity is a feature, but 
a large quantity of water is required and the work, rather 
expensive because of its imperfect separation. 

Another washer along this line is known as the Scaife 
trough washer. This consists of an inclined semi-circular 
trough, about two feet in diameter, and twenty-four feet 
long, provided at intervals with riffles. Running along 
the center of the trough is a shaft provided with fingers 
which act as stirrers. The shaft is given a reciprocating 
motion. The raw coal is fed at the upper end. The im- 
purities remain on the riffles, the washed coal being dis- 
charged at the lower end. When the riffles are full the 
supply of coal is shut off, the good coal remaining in the 
trough is washed off and the trough cleared by dumping the 
refuse into a box below. The process in intermittent, but 
the advantages claimed for it are its simplicity and the 
lack of a screen to wear out. The fingers or stirrers 
which are the only parts subject to much wear being easily 
replaced . 

The Campbell bumping table consists of a shallow 
trough 2 l/2 x 8 f t . x about 6 or 8 inches deep, open at 
both ends. It is hung in an inclined position, and by 


means of a cam is thrown against a bumping post at the 
upper end. The coal is sluiced on with water and as the 
bumping table is thrown against the post the impurities are 
thrown off the upper end while the pure coal is washed off 
the lower end with the water. 

The Robinson washer is of different construction. The 
coal and refuse are fed at the top of the vessel which is of 
the shape of an inverted cone. Water enters at the bottom 
with sufficient force to carry the coal over one side with 
it. The impurities settle in the bottom. A vertical shaft 
with stirring fingers attached keep;'the mass agitated thus 
allowing a better separation. 

An arrangement of German origin drops the raw coal 
past a blast of air which is of sufficient strength to force 
the pure coal to one side allowing it to drop into a bin. 
The impurities drop past into a refuse bin. 

A separation by means of centrifugal force has been 
used in the anthracite fields. A spiral trough is revolved 
to throw the slate in the coal, which is fed at the upper 
end, off the trough allowing the pure coal to slide down 
into a bin at the bottom. This is merely a rough separation. 

Jigs have to a large extent replaced the older methods 
of washing, being more economical and thorough. 

The Luhrig jig is typical and is widely used, giving 
excellent results with economical working. The two cross- 
sections here shown are for nut and fine coal treatment. 
The nut coal jig consists of a box or chamber separated 





- at about the center by a partition extending about half 

way down from the top. On one side is a plunger which is 
actuated by an eccentric through a connecting rod. On the 
other side is a screen on which the raw coal is fed. The 
screen is inclined, the coal being fed at the upper end. 
The plunger imparts a pulsating motion to the water which 
fills the entire box and this motion agitates the body of 
coal. The impurities being heavier settle in a layer on 
the bottom on the screen. The mass gradually works to the 
lower end where the coal is washed over the sill with the 
water. The impurities pass through an opening under the 
sill which is known as the slate valve. Below this slate 
valve is a conveyor trough into which the impurities fall 
and are carried by the screw conveyor to an elevator boot. 
The elevator raises the impurities to a trough or conveyor 
which leads to the refuse heap. This slate valve opening 
can be regulated so as to keep a uniform bed of impurities 
on the screen and thus prevent good coal from passing through 
the slate valve and being wasted. The coal is sized before 
being fed to the jig so that very little passes through the 
screen. Most of the material that does pass through the 
screen is very fine and is refuse, so a draining valve is 
placed in the bottom of the box to allow this waste material 
to be run off. This draining valve is connected to a sluice 
way which leads to the refuse settling tank. A continuous 
supply of water is fed at the rear of the jig through the 
pipe shown. 

The fine coal jig is of about the same construction 
and operation, but differs in the manner of handling the 
waste materials. In these jigs it is necessary to handle 
coal from that which will pass through a 3/4 inch round 
perforation down to a fine dust. The box is divided as 
in the previous case with the plunger on one side and screen 
on the other. Cn the screen is placed a layer of feldspar 
which has a specific gravity higher than the coal, but lower 
that the impurities. The pieces have a diameter larger 
than the openings in the screen. The coal is fed in the 
same manner and works its way across the screen to the sill 
where it overflows with the water into the sluiceway in front. 
The refuse works its way through the layer of feldspar into 
the hoppered bottom of the jig box from where it passes through 
the refuse gate into a sluiceway by gravity and is carried to 
the refuse settling tank. These jigs can be placed in a 
battery up to twelve, so that one shaft and sluiceway will 
serve the entire battery. In the operation of these jigs 
it is very important that the coal treated in each jig be of 
uniform size. 

The Hartz jig is about the same as the above in general 
operation. It differs in construction, being made of sheet 
steel with semi-circular bottom. 

Berard's machine is another of similar operation. 
This machine was introduced as early as 1851 in London. 
It was used in Pennsylvania for a few years s» 1873. 

The Stutz jig has a few special appliances, the bottom 




being of special shape. In the improved machine the 
pulsating mechanism is placed directly under the screen on 
which the coal rests. A plant with this machinery capable 
of handling 6C0 tons per day of 1C hours has been estimated 
to cost $16C00.0C. The cost of washing has been given as 
2 cents per ton, but this does not include interest and de- 

The Stein jig has a special method of arrangement and 
handling the coal. The jigs, which resemble the others, 
are double. Coal is fed at the side of one jig. It passes 
over this bed to the next jig from which it is discharged in- 
to a sluiceway. There is thus obtained a long path and a 
thorough separation is accomplished. One result gives a 
reduction from 35^ to 1C$ ash and Z% to 1.35# sulphur. 

The Stewart jig operates a little differently than the 
others. This jig consists of a box with a perforated bot- 
tom which is suspended in a tank of water from eccentric rods 
by means of which it is given the pulsating motion. The 
bottom is inclined. The coal is fed at the upper end and 
works its way across the screen where it is washed over the 
sill with the water. The refuse passes through a valve in 
the front of the jig into the hoppered bottom of the jig 
from which it is discharged by an elevator. The coal that 
is fed to the jig is not sized. The capacity of each jig 
is higher than that of the Luhrig jigs, but with small size 
coal the operation is not as economical. 

The Diescher washer is similar to the Stewart. The 


jig has a different shaped bed and has some variations 
in the mechanical construction. 

The special feature of the New Century jig is the 
plunger. By means of a spring a quick stroke is accomplish- 
ed which seems to be very effective in separating fine coals. 

Luhrig, New Century, and Stewart type jigs are common- 
ly used in the Illinois coal fields. In the selection of 
jigs for this plant the Luhrig type were selected because 
of the economical construction, operation and high efficiency 
The entire plant, in fact, has been equipped with Luhrig ap- 
paratus . 

The elevators with the exception of the raw coal, are 
Luhrig type. A cut here given shows the type of bucket 
and method of discharge. The buckets are perforated to 
allow as much water as possible to drain off before the 
coal is placed in the storage bin. This moisture remain- 
ing in the coal is a serious problem, and will be mention- 
ed later. The head wheels are cast iron. The elevator 
is driven from the head-end by means of a chain-drive from 
a jack shaft. The speed reduction is accomplished by re- 
ducing from the jack shaft to a counter shaft and again by 
means of a spur and pinion from the counter to the head 
shaft. The head and counter shaft are supported on a 
Luhrig take-up which facilitates the fitting of the chain 
when construction or repairing. This take-up consists of 
a sole plate on which the bearings rest. They are spaced 



to accommodate the gears and are held thus by a spacing 
rod. By means of a take-up screw both bearings are moved 
at the same time, thus allowing adjustment of the head wheel 
without disturbing the gears. 

The raw coal screen is shown by the sketch. It forms 
a compact and efficient method of grading the coal. Shaking 
screens are sometimes used, but they require more room and 
seem to have no greater advantages, altnough claimed by some 
to have. The screens are driven by means of gears and 
pinions. The jackets are supported by spider arms. The 
rinsing and resizing screens are all single jacketed. 

An important feature in coal washing is to have coal of 
uniform size fed to each jig. This is especially true of 
fine coal. The separation of the different sizes is nicely 
accomplished in the hydraulic grading box. This consists 
of a long box with honpered divisions across the bottom. 
The coal is sluiced into the box at one end, the larger 
sizes being heaviest settle in the first compartment and 
are sluiced to the first jig. The next size collects in 
the next compartment, and so on through the six grades. 
In this manner each jig can be regulated to a nicety to 
wash its product, and excellent results are obtained. 

An important feature of tne Luhrig system is the re- 
covery of the sludge. In the older style washers the 
water used in the jigs was allowed to run off carrying with 
it much fine coal in the form of dust. Mr. Karl Luhrig 
saved this by allowing the water with the fine coal to pass 
into a large settling tank, known as the sludge tank. 

The fine coal is here allowed to settle. A slowly 
moving conveyor then carries it to an elevator pit located 
at one end of the tank. 

At the end opposite to that at which the elevator is 
located is the suction pipe for the centrifugal circulating 
pump. The water at this end is clear enough to allow its 
use in the jigs. The water is thus used over and over 
again. The only water that is lost is that which is used 
in sluicing away the refuse. Enough fresh water is added 
as rinsing water to counteract this loss and keep the quant- 
ity constant. Tie fjji-tf 
He. s /'? i. 
" In the design of this plant the following conditions are 

to be met. 5CC tons of raw coal are to be washed in 8 hours, 
washing the product from the mine that passes through a 3" 
round perforation producing 5 sizes of washed coal as follows: 

Size Percent Thro. Cver 

#1 Nut 



1 3/4" 

,f2 " 


1 3/4" 


#3 - 




#4 Fine 




#5 " 




Sized according to Illinois Coal Operators' Association 
standard. All perforations in screens to be round. 

It is assumed that the mine will produce from 800 to 
100 tons of raw coal per day, and that 50^ will pass through 
the 3" perforations. 


The following is an analysis of the coal which is from 

the Illinois coal field and is taken as a basis for the 

design of the plant. 

In the raw coal there is 25$ ash, that is, in the coal 

passing through the 3" perforations. The coal analysed in 

specific gravity solution gives the following results: 

#1 Sink 

24$ F. 
19$ A. 

Raw coal 

61$ Floats 

7% Ash 

9 $A. 

39$ Sink 
50$ Ash 

26.25$ S. 
66 $ A. 

' #1 

1.35 sol. 

1.45. sol. 

^6$ S. 

66$ A. 


Cr 12.8$ raw coal lies between 1.35 and 1.45, and 
carries 19$ ash. 


The coal will be taken from the mine tipple where it 
will pass through a 3" round perforated screen and be carried 
to the raw coal bin by an inclined flight conveyor which will 
be operated independent of the washery machinery to allow the 
bin to be filled in case the washeniis shut down. 

From the raw coal bin coal will be fed to a continuous 
bucket conveyor by means of a Link Belt revolving feeder 
which will put a uniform load on the elevators and keep a 
uniform amount fed to the jigs. The coal will be lifted 
by this elevator to a triple jacketed revolving sizing 
screen which will separate ,'1, 2, and 3, which will pass 
to their respective jigs while 4 and 5 will pass through 


into the hydraulic grading box. 

Each size of coal will be washed separately, two 
jigs being provided for #1, three for #2, two for #3, and 
six for #4 and 5. 

After passing through their respective jigs #1, 2, and 

3 washed coal will be sluiced to draining screens located 

directly over bins for their storage. These draining 

screens will also act as resizing screens so that any coal 

that has been broken and is undersize will be separated 

here and pass with the water to a redraining screen where 

sizes over #4 will be separated and returned to the boot of 

the raw coal elevator. It will thus be allowed to take its 

proper place in the rewashing. The fine coal and water 

passing through the redraining screen will pass into the 

hydraulic grading box. From the grading box the uniform 

sizes will pass into the fine coal jigs, six in number, and be 

washed separately. The washed coal will pass over the 

sill of the jig and be sluiced to a large revolving screen. 

#4 will pass over A into a sluiceway leading to the boot of 

the Luhrig elevator which will carry it to the top and empty 

it into the bin. #5 which consists of much dust and fine 

[he. screen 
particles will pass through A with the water into the sludge 

recovery tank located directly beneath the screen. As the 

fine coal settles it will be carried to the elevator pit by 

a flight conveyor. A Luhrig elevator will lift the coal 

to the #5 bin. 


The nut coal will be rinsed by a spray of water on the 
draining screens; #4 by a spray on the separating screen, 
and #5 by a spray on the coal as it is being lifted to the 
bin from the sludge tank. 

The refuse passing through the slate valves of the nut 
coal j^gs will be carried by a screw conveyor to the boot of 
a Luhrig elevator which will lift the slate to a sluiceway and 
by which it will be sluiced to the refuse heap. The impur- 
ities from the fine coal jigs will pass to a settling tank 
from which it will be elevated by a Luhrig elevator to the 
refuse sluiceway. 

The nut coal jigs will be connected with the refuse 
settling tank so that the fine particles passing with the 
impurities through the screen and settling in the bottom of 
the jigs can be run off when necessary. 

The water for the nut coal jigs will be taken from 
the end of the sludge tank opposite to that at which the 
elevator is located. It will be lifted by a centrifugal 
pump to the jigs. The pump will be belted to a pulley 
on the engine crank shaft. 

Fresh water for rinsing the coal will be supplied 
from an outside source and will be supplied to the screens 
by a steam pump. 

The sludge and settling tanks will be provided with 
large size drain pipes so that the water could be run out 
in case of a shut-down in winter. 

The building will be heated by steam. The various 
gates and valves will be provided with steam connections 

to prevent their freezing in winter. 

The building will be lighted with electricity to 
allow night work. The raw coal storage bins will have a 
capacity of 200 tons, and the washed coal storage bins a 
capacity of 270 tons. 

Revolving feeder and gate for raw coal bin. 

1 Link-Belt revolving feeder, complete. 
Also 1 "Spellman" gate complete with levers, etc. 
for delivery of raw coal from bin to raw coal elevator. 
Raw Coal Elevator. 

One continuous bucket elevator 60 ft. 
centers for lifting coal from raw coal bin to raw coal 
sizing screen. This elevator is to be made up of 16" 
x 12" x 18" #10 steel continuous buckets, carried by double 
strand of 18" pitch bar link rolling chain, complete with 
necessary head, counter, and foot shafts, bearings, collars 
sprocket wheels, patent spur equalizing gears, driving pul- 
ley on countershaft, and sprocket wheel on foot shaft for 
driving revolving feeder, also flat steel track for chain. 
Raw Coal Screen. 
One triple jacketed revolving screen for raw coal, 
inner jacket 12 ft. long; middle jacket 11 ft. long, and 
outer jacket 10 ft. long, complete, with 5 15/16" rough 
turned screen shaft, spiders, rings, steel cone, and 
covering of l/4" plate with 3/4" round perforations, and 


1" round perforations for outer anil middle jacket, 
respectively, and of 3/8" plate with 1 3/4" round perfor- 
ations for the inner jacket, also bearing and countershaft 
with bevel gear drive. 

Nut Coal Jigs. 

Seven Luhrig nut coal jigs, complete with shafts, ec- 
centrics, etc. These jigs to be in one battery. 

Refuse Elevator from Kut Coal Jigs. 

One #5 Luhrig elevator, 15 ft. centers, complete, with 
all necessary head, and foot mechanism, chain and buckets, 
angle guides, back lining, and driving countershaft with 

Nut Coal Draining Screens. 

Five 31''t. diameter x 6ft. long nut coal draining 
screens, complete, with bearings, spiders, and coverings 
of #10 plate - two to have 1 3/4" perforations, two to have 
1" perforations, and one to have 3/4" perforations. 

Also one 3'C" x 6'C" screen with covering of #10 plate 
and 3/4" perforations for over size coal in redraining. 
These screens to be complete with counter shaft, etc. 
Fine Coal Jigs. 

Six Luhrig fine coal jigs, complete, with shafts, 
eccentrics, feldspar beds, etc. These jigs to be in one 
battery . 

Fine Coal Draining Screen. 

One 4'0" x 10*0" revolving screen, complete, with 
shaft, bearings, spiders, rings, and covering of f/-lC steel 
plate with l/4" round perforations. 

#4 Fine Coal Elevator. 

One ,;'l Luhrig elevator, 38 ft. centers, complete, 
with all necessary head and foot mechanism, chain and bucket 
angle guides, back lining, and driving countershaft with fit- 
tings . 

Sludge Recovery. 
One conveyor, about 46 ft. horizontal centers, and 1C 
ft. vertical centers, complete , with necessary head, counter 
and corner shafts, bearings, collars, sprocket wheels, gears, 
and Sstrands of £730 chain, each 122 ft. long, fitted with 
3/16" steel flights, having reinforcing angles and wearing 
shoes ;also necessary steel tracking. 
#5 Coal Elevator. 
One #4 Luhrig elevator, 55 ft. centers, complete, with 
head and foot mechanism, chain and buckets, angle guides, 
back lining, and driving countershaft with fittings. 
Fine Coal Refuse Elevator. 
One #4 Luhrig elevator, 43 ft. centers, complete, 
wit$i head and foot mechanism, chain and buckets, angle 
guides, back lining, and driving countershaft with fittings. 
Gates for Washed Coal Bins. 
Five Link^Belt steam- jacketed gates, complete. 

Bin and Sluice Lining. 
Necessary #12 steel plate linings for bottoms of raw 
and washed coal bins; #12 steel lining for chutes, and #14 
steel lining for sluiceways. 
Pumps . 
One #8 Morris Imperial standard double suction 


horizontal pump, complete, with pulley, for circulat- 
ing water for jigs. 

Cne #25 - 7" x 5" x 10" "Gardner" low service duplex 
steam pump for fresh water. 

Necessary piping, with valves and fittings, from 
sludge recovery to pump, and to jigs, grading box and 
refuse sluice. 

Necessary piping from fresh water pump to sludge 
recovery, draining screens, and to refuse sluice. 

Steam piping to steam gates from steam lire in engine 
room. Also steam piping to steam coils for heating build- 

Necessary 12" vitrified sewer pipe for draining sludge 
and refuse pits . 

Engine, Line Shaft, etc. 

Cne 13" x 18" double class "A" H. S. & G. #122 
horizontal engine, 160 R.P.M., 130 H.P., with 80 lbs. 
steam pressure, complete, with usual fittings, and a 
90" 4-groove split flywheel, sheave for 1 3/8" manila 
rope, also pulley for driving centrifugal pump. 

Necessary line shafting, jack shafting and counter- 
shafting, with rope transmission to main shaft, rubber 
belt to jack shafts and chain connection to the various 
appurtenances, elevators, conveyors, screens, etc. 


The lumber used for the building will be #1 common 
yellow pine, and for hart tc.i lumber of suitable quality. 
All lumber to be surfaced four sides. The building, with 
the exception of the bins, and sludge tank, will be cover- 
ed with drop siding and complete with corner fc>oar<ls,window 
casing, frieze, etc. The roofing will be 2-ply composition, 
and necessary gutters will be provided. The building to be 
complete with all necessary doors, windows, and stairways, 
the windows being glazed. All exposed wood work is to be 
painted . 

With the building are to be provided all necessary 
timber supports for machinery, and all necessary tanks, 
chutes, sluiceways, elevator casings, etc. 
Foundations are to be concrete. 

Many coals of poor quality in the raw state are made 
excellent fuel coals be washing, others of low quality and 
value are relatively increased. The substances that go to 
make up the ash in the furnace are removed by washing. It 
is thus that the quality is increased. As coal is now 
bought to a large extent on the heat unit basis it behooves 
the coal operators to have as small a percent of ash as 
possible . 

By the removal of the impurities which to a large 
extent form the clinker in the furnace, such as pyrites 
and clay, the capacity of the furnace is often increased. 

Another advantage of washed coal is that it is of uniform 
size when delivered, which is also condusive toward an in- 
creased furnace capacity by giving a uniform fire bed. 

In the manufacture of coke the treatment of the coal is 
an important matter. Coal of excellent coking qualities, 
but which contains too much ash or an excess of sulphur can 
often be improved by washing to make a very high-class coke. 
In the design of this plant the coal has been treated only 
with reference to boiler fuel. 

One disadvantage encountered in the treatment of coal 
is the amount of water that is retained by the coal, especial- 
ly by the #5 size. It is very difficult to lower the per- 
cent of water which is often as high as lC^jwhere the coal 
has plenty a chance to drain, as in being transported quite 

a distance the coal drains quite thoroughly in the large 
sizes. The percentage of water above given includes the 
water that is contained in the pores of the coal as it comes 
from the mine. Often this runs as high as &fo . The water 
added from washing remains on the outside and drains off 
quite readily in the large sizes, but the #5 size contains 
so much fine stuff that it packs very close and holds the 
moisture. Attempts have been made to reduce the moisture 
but have as yet been unsuccessful in most cases, the treat- 
ment being too expensive. 

In the preparation of this paper much valuable inform- 
ation has been obtained from Mr. A. J. Sayers, of the Link- 
Belt Machinery Company, Chicago; John Fulton's book on Coke 

has been found to be very instructive, as well as 
Richards' on Cre Dressing. The plant and mine of the 
Consolidated Coal Company, at Collinsville , Illinois, was 
visited. This plant is of about the same capacity and gen- 
eral arrangement as the one given in this design, employing 
Luhrig apparatus. At East St. Louis, Illinois, the plant 
of the Bessemer Washed Coal Company was inspected. This 

plant washes coal which the operators buy from the mines in 


the Illinois coal fields. The mine owners .often glad to get 

rid of the slack which can be washed and sold at a profit. 
This plant uses the Stewart type jig with Luhrig recovery. 
From the descriptions here given the importance of coal wash- 
ing can be seen, as also the magnitude to which it has now 
developed. As the better beds of coal are used up the treat- 
ment of the poorer grades to make them fit for market b© wash- 
ing is bound to occur. 

In prepairing the design of this plant it was first at- 
tempted to have the machinery arranged to allow for expansion. 
As an entirely new equipment would be necessary, and also 
alterations in the entire plant, it was thought that it would 
be better to have a nearly independent plant than to try to 
arrange any additions. As the Stewart jigs have a larger 
capacity than Luhrig, and with large size coal they are 
quite as economical as the Luhrig, it was thought at first 
to install a fewer number of nut coal jigs by using the 
Stewart type. It was found, however, that this had been 
tried, but had not been particularly successful, so this 

1 | 



or a 

500 Ton uiTumnous COAL 


Armour Institute of TecbnoJcxjij • 
6ca/e^' = |-0" TTaq, 2-/906 




■hT ., 


ti i;mS 



■■■■» figl 

?■ fii^TTTnill J i 

H 1 



[ illl llB 




y has 

s are 
at the 

;n and 

led as 

ns of 



HI— U| 

* \l\ ,-^ssa. m "-U 

1 ! ill/- >f*l It 





1 . l|ynl^H|H y^= 

aHteHsri tenfe 

I m! il' 

i ""HErJji- 


j|h - -3--^jj*— 3-; ^jj» — J1?:; r "" ^"y 


ft 1 



1 1 
i i 
i i 
i i 

i - 


/ v- 



was dropped and the entire plant equipped with Luhrig 
apparatus. The plant of the Consolidated Coal Company has 
been operating for about a year, running sixteen hours per 
day, and is giving excellent satisfaction. No results are 
obtainable as to the efficiency of the plant as yet, but the 
fact that it was installed by the Link-Belt Machinery Company 
will insure a high mark. 

Calculations . 

In the design of this plant the speed of the screen and 

elevators, and sizes of jigs, tanks, etc, were determined as 

far as possible from results found to be satisfactory in 

practice . 

Raw Coal Elevator. 

This elevator will be required to lii't about 6C tons of 

coal per hour, or 1 ton per minute. Each bucket will hold 

about 4C lbs. 2000 . 50 buckets per minute. 

Each bucket is 18" deep. 50 x 18 = 75 ft. per minute = 

speed required. Assuming this as 80^ of capacity, for full 

capacity a speed of about 100 ft. per minute will be required 

The head wheels being 36 inches in diameter, about 11 
R.P.M. will be necessary. With the arrangement of shafting 
as shown there are 3 reductions between the line shaft at 
150 R.P.M. and the head shaft at 11 R.P.M. 

With equalizing gears of 46.75" and 8" diameter the 


With 24" and 36" sprockets on chain drive from jack 

shaft to countershaft the speed will be raised to 9S E.P.M. 

36 x 66 = 99 R.P.M. 

With 48" and 32" pulleys froir jack to line shaft the 

speed of 150 R.P.M. on line shaft will be met. 

48 x 99 = 148.5 


The belt could be counted on to slip enough to give 

about 11 R.P.M. at head shaft. 

Raw Coal Screen. 

80^ of coal will pass through first screen, which 

equals 48 tons, allowing 4.3 sq.ft. per ton hour; 

48 x 4.3 = 2C6 sq.ft. required. 

Screen is 12 ft. long. 

2C6 = 5.5 ft. = diameter. 

TT x 12 

57% will pass through next screen; 

.57 x 120CCC . 684GC lbs = 34.2 tons per hour. 

Allowing 6 l/2 sq.ft. per ton hour. 

34.2 x 6.5 = 222 sq . ft. of screen; 

second screen 11 ft. long. 222 . 6.5 ft. diameter. 

11 x 3.14 

48/£ will pass through third screen. 

.48 x 1200CC = 576CC lbs. = 28.8 tons per hour. 

Allowing 8.7 sq . ft. per ton hour 

28.8 x 8.7 = 25C sq . ft. screen. 

Screen is 10 ft. long. 250 = 8 f t . diameter. 

10 x 3.14 


With screen running at 9 R.P.M. a peripheral speed of 

226 ft. per minute is reached. 

To obtain 9 R.P.M. at screen three reductions are used: 

66_i52_x_9_ =52.5 R.P.M. speed of countershaft. 

66.52 and 11.38 = diameters of gear and pinion respectively. 

Belt to jack shaft. 52. 5 x 38 = 100 R.P.M. speed of jack 


shaft - 38 and 20 = diameters of pulleys. 

Eelt to line shaft: 48_x_ 1CC_ = 150 R.P.M. - speed of line 

shaft. 48" and 32" - diameters of pulleys. 

Nut Refuse Elevators. 

From 100 R.P.M. on jack shaft to 6 R.P.M. of head shaft 

through two reductions: 24 x 48 = 11.5" diameter of the 


sprocket on jack shaft. 2 4 x 9.55 = 39.63" diameter of 


spur gear on head shaft. 

Fine Coal Elevators. 

Using same gears as above. Then it is necessary to 

reduce from 150 to 24 through two reductions. 

150 on line shaft to 81 on jack shaft - 

81 on jack to 24 on counter shaft. 

24 x 48 = 14 l/4" diameter of jack shaft sprocket. 

150 x 24 = 45" = diameter of pulley on line shaft. 


Nut Goal Jigs. 

75 R.P.M. of eccentric shaft frorr 150 on line shaft. 

150 = ratio 2 to 1, which can be had by using 26 and 18 

inch pulleys. 

Fine Goal Jigs. 

125 R.P.M. of eccentric from 150 R.P.M. of line shaft. 

150 - ratio of 6 to 5, which is given by 36 and 30 inch 


pulleys . 

Resizing Screens. 

150 R.P.M. on line shaft to 22.5 through two reductions 

150 x 22 = 69 R.P.M. 

69 = ratio of 3 to 1 for bevel gears, which is obtained 


15.28 and 5.09 inch diameters resp. 

#4 and #5 Screens. 

150 R.P.M. to 15.7 R.P.M. through two reductions: 

16 x 150 = 60 R.P.M.; 16 and 40 inch.* diameters of 


1 1.75 x 60 = 15.7 R.P.M.; 11.75 and 45 inch. = the di- 

ameters of sprockets. 

4 x 3.14 x 15.7 = 197 ft. per minute peripheral velocity of 


Scraper Conveyor. 

60 R.P.M. of jack shaft to 4 R.P.M. of scraper shaft 

through two reductions. 


60 x 11 . 14 = 26.7 R.P.M.; 11.14 and 25 inch. = diameters of 

bevel gears. 

7.24 x 26.7 = 4 R.P.M. ; 7.24 and 47.9 = diameters of pinion 

and spur gear. 
/="€ e cJ £ f 

At 11 R.P.M. 66 buckets will be filled per minute. 

With three divisions on feeder 66/3 r 22 R.P.M. necessary. 

Foot shaft runs at 11 R.P.M. , which gives a ratio of 2 to 1. 

With 30 and 15 teeth on sprockets this ratio is obtained; 

sprockets are 24 3/4" and 12 l/2" in diameter resp. 

The horse power supplied is very liberal, but as fuel 
is a small item it was deemed best to allow plenty of power. 
The power will be used as follows : 

Each jig has been allowed 1.75 B.P. 

13 jigs will require 15 x 1.75 = 22.75 H.P. 

Each small elevator has been allowed 5 H.P. 
4 elevators require 20 H.P. 

For the centrifugal pump 1 H.P. has been allowed for 
each foot lifted, which is 30. 

For the raw coal elevator 10 H.P. has been allowed. 
Then allowing 20 H.P. for the screens, shafting and scraper 
conveyor a total of 103 H.P. is reached. 

The H. S. & G. Company's nearest size would be 50 H.P. 
which when placed double would give 100 H.P. It would be 
necessary to run overload with this size so the next size 
was selected which is 65 H.P. giving 130 H.P. when placed 
double. The engine is not protected by placing it in an 
enclosed room so that it is subjected to quite rough treat- 
ment; thus an excess of power at the start is not unreasonable.