The Democratic advocate. [volume] (Westminster, Md.) 1865-1972, 1909-11-26

will produce the desired analysis OF
the finished product The clay or
shAle has been excavated. transported
70 the Cement Mill and there dried In
Cylinders much like those used for the
stone and then reduced to size OF
three-eighths inches and under for
mixing with the rock. In some &C.
ment Mills the clay Is reduced before
drying, then after passing through the
dryers. the crushing process Ia con-
tlnued until the material Is reduced 70
the proper size for mixing with the
crushed stone.
There are great variety OF mills
which are used for reducing the mix
ture OF rock and clay TO the required
tneness. For clay ard ghnie, disln-
trgratorB, rolls. hammer mills. dry
pans and bHll mills are used For re-
ducing rock, dry pans, rolls. ball
mills. hammer mills and the various
forms OF crusher are used.
The place In the operation where
Z the mixture OF the two materials takes
/ place Is not the same ia all mills. In
some. the mixture IL made Just ca the
materials come from the quarry. In
/ others, the mixture is made Of the dry
and partially finished materials. In
all mills. the mixture Is made before
the final pulyerizing takes place.
/ For final pulyerizing variety Of
mills are suitable. The kinds most
used are tube mills. Fuller mills.
Gritin mills and Kent mills. Tho
dried OF partially reduced mixture ID
+ sent to the mills. which grind Il 70
such aneness that II ~ much iika
ionf The uaHni requirements aEs 10
Rrlnl IL until eyonty-eight per cent
viii pass q screen that has two hun
grcd openings per square inch. made
WITH wire that uaa diameter Of Ou24
inch After the mineral has boon
ground 10 the required fineneaA. ii is
sent to the Mlua The kilng are large
resolving cylinders. lined with IRE
hrtrk and inclined 40 that % tho ma.
terlal IL raised on one side Of the kilns
ia Us turning Il Is. 81 the same flme.
thrown towards the lower end or front
OF the kiln. The inclination varies
slightly in different factories. but IL
usually about three-quariera of an
inch per foot in length The cylinders
for the kilna vary In length. diameter
and number a. bearings The present
+ dimensions most In demand are kiina
Of one hundred and twenty Ave feet
Ia length, eight feet ia diameter for
about one-baif the length. and seven
feet six inches for the remaining par-
ton. and run on two Heta OF hearings.
The rear endH Of the kilns communi-
cate with stacks which carry on the
waate gases and serve 20 inrreaae the
drAught The front ends Of the kilna
are protected by brick housings in
which there are placed holes for tho
entrance Of the fuel pipe aud for OBJ
serving the process 81 cllukering
The rear ends of the stacks are also
protected with brick or concrete houa-
insH for the purpose Of collecting the
dust which Is blown through the kllns
and might otherwise BE- wasted. and
nlso 90 serve na support for tho
dust, which Is blown through The ktlnR
and might otherwise be- wasted. and
stacks. II takes the material from
three-quartera 10 one and ons-hRif
hours TO travel from the kiinh 10 the
font This time ~ dependent upon
the diameter oi the kiln and the RAJ
pidity With witch Il turna and us In
clination
The fuel most used in burning co..
ment 10 powdered coal. which IL forced
/ into the klinB by means Of air under
pressure As soon M the mixture Of
coal and air enters the combustion
zone Of the kiln. the coal almost i'm
mediately combines with the oxygen
OF the air producing a high temper
AZURE fame 81 great length. The
+ greater the pressure OF air used for
/ forcing the coal into the kilns the
greater the length OF the fame The
proper cilnker temperature varies be-
tween $500 degrees Fahrenheit and
5000 degrees Fahrenheit Ia the kiln,
the hour-like mixture OF lime. rock
and clay loses all It's volatile gnses.
combined water and everything that
can be transformed ~ such temper
allure. A gradual change takes place
In the mixture throughout the length
OF the kiln, the compounds OF the lime
gradually uniting vita those OF the
clay, until finally az the place Of the
most Intense heat the union between
the compound is complete and a ce.
ment clinker Is formed. which issues
from the kiln in the form Of rough,
red hot balls. varying In size from
rice 10 black walnut AZ the clinker
coois II becomes very dark In color.
and when fully cooled II varies in col
OF from brownish-black 10 jet-blaok
II is very heavy for a given volume.
since II has a specific gravity OF three
this Is three times az heavy az water.
The clinker after II comes from the
kiln is sent TO coolers. whereby a
forced draught OF air cools Il and Il Is
placed In piles where II " ready TO
become cool enough 70 be handled
with safety TO the men and the grind
ing mills.
n The elinker is then transported and
elevated to the Weighing and mixing
machines for the addition OF gypsum.
This Is added for the purpose OF reg
ulating the set from quick to slow
one and one-half to two per cent. on
the gypsum being required.
After mixing with the gypsum the
clinker is sent to the grinding mills
for pulverizing, where Il is ground
line enough for ninety-two to ninety
four per cent. Of II TO pass a screen
having ten thousand meshes per
square inch
After grinding. the cement is sent
to bins for storage and is ready for
shipment to consumers, provided II
passes what is known as the Sound
ness Test" II II ib not found to be
sound cement, II Is permitted to re-
main in the bins and age until It will
pass the age for soundness and
strength required Of standard grades
of cement.
From the beginning OF the operation
until the Cement is loaded In the cars
and has the o. X Of the chemist for
shipment, 1t is watched and controlled
as to its physical and chemical qualiy
ties Should anything go wrong at
any point in the operation. he must
know II at once and should know what