Note: Descriptions are shown in the official language in which they were submitted.
li33021
BACKGROUNV OF THE INVENTION
-
The pre~ent invention relates to a method of producing
improved ~ementinq m ixture~ from energy-conserving raw mat-
erial~, and the product~ produced by practicing the method.
Cementina material~ which are most commonly U8ed in broad
applications (~uch a~ concrete paving, dam~, grain elevato~,
airport runwa~, and ~eaport in~tallations) are concrete mix-
ture~ pozzolan-cement mixture~ or lime-pozzolan mixturefi. While
Portland ~ement i8 in general u~e and may be more easily used,
it i~ le~ durable then cement~ ~ontaining both Portland cement
and a ~ood pozzolan.
~ hen portland cement hydrate~, calcium hydroxide i8 liber-
ated. ThiR chemical in it~elf contributes nothing to strength
or water-tightne~s and i~ readily removed by leaching. When
a pozzolan i~ pre~ent, ho~ever, it combine~ ~ith the calcium
hydroxide, contribuing both to ~trength and water-tightne~.
while s~liea i~ the principle con~tituent of all pozzolanF,
mofit contain ~ub~tantial quantitie~ of alumina and iron oxide.
It al~o appear~ that ~ ood pozzolan~ contain a ~mall pOE-
centaqe of the alkalie~ ~uch as ~odium oxide and potas~ium ox-
ide.
The pozzolan, ~y combininq with the free lime in the port-
land cement, render~ it more sound and le~s ~u~cepti~le to the
action of corrosi~e 6ulPhate and a~id waters. A~ the pozzolan
it~elf i~ ~table in the pre~ence of these water~, the mixture
of pozzolan-portland cement is considerably more resiRtant to
~ulphate and acld brine~ than neat portland cement.
,~,
113302~
Pozzolan ha~ a ~peoific qravity of 1.50 eO 2.8, depending
upon ~he ~ource, a~ compared to 3.11 to 3.14 for portland
cement. Thi~ difference in specific qravity results in a ligh-
ter weight slurry for the pozzolan-cement aB compared to a
~lurry of ~imilar con~istency with portland cement.
Heat of hydration of any mixture of pozzolan and portland
cement i~ le~s than that of the game weight of corresponding
portland cement. The rate and amount of heat generation accomp-
an~ing thi~ reaction i~ dependent upon th~ character and fine-
ne~s of the pozzolan. when a type 11 cement i~ employed at 70F,the heat qeneratad by the pozzolanic reaction up to the age
of 28 day~, on the averaae, about half aY qreat ao that of the
cement which wa~ rep~aced~
Concrete~ containing pozzolans in normal amounts are likely
to have appreciable ~maller compre~ive strength~ at early ages
than corresponding concrete~ wlth ~traiqht portland c~ment.
~ther thingR being equal, the finer and mor~ active the pozz-
olan, the more rap~d the ~ain in strength at early ageas.
If moi~ture i~ availabl~, however, ultimate ~tren~th~ of
concrete6 containina coar~er, le~ rapidly reactive pozzolan~
may equal or exceed ultimate strength~ of con~rete~ containing
finer, more active Pozzolan~. Cement literature state~ that
the e~rly ~trenqth~ of portland-pozzolan cement are le~ than
the ~traight cemant ~lurrie~. The ultimate ~tr~ngth more than
the ~tra~qht cemsnt slurrie~.
Probably the mo6t important factor that ha~ led to the u#e
of pozzolan~ in concrete ha~ been the increased re~istance that
i~ gained to the attack bY chemical agencie~, and in particular
by ~ea ~ater~ M~ch experimental work has been done to ~how the
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1133021
increafied ~hemical re~istance obtained by the u~e of pozzolans.It ha~ been reported that, after ten years immer~ion, the use
of burned clay pozzolan~ ha~ rendered even the leane~t mortars
parti~ularlv immune from attack by oulphate waterP. From the~e
re~ult~, the re~i~tance of pozzolanic cement~ to the action
of sulphate ~aters ~eemed to be considerably higher than that
of portland cement.
A ~uitable pozzolan u~ed in appro~iate amount sub~tantially
increases ro~istance of concrete to sulphate attac~, as comp-
~0 ared ~ith corre~ponding concrete~ containing Type 1, Type 11,or Type 111 c~ment~.
Al~o in qeneral, resi~tance of concrete~ to weakly æ id,
or low pH, water~ may be ~ub~tantially increa~ed with a good
pozzolan a~ a replacement in the order o~ 25 per cent or greater.
owing to the scarcity of good natural pozzolans, attempts
have been made to produc^e pozzolan~ out of inert materials.
Such attemptR have consi~ted mainly of thermic processes at
variou~ temperature~. Such proceo~es, however, have had limited
succeso, because of the chemical impuritie~ left therein
after proce~sing and their chemical reactivity when added to
cementing mixtures, and ~ubsequent thereto.
The manu~acture of portland cement i8 a highly energy in~-
en~ive procedure involving the reeovery, cru~hing, pulverizinq,
~creenin~ and calcination of the cement raw material~, and the
~olinq, intermixinq and fine qrinding of the resulting cement
clinker therefrom.
Due to the increa~inq pres~ure of negative factor~ affect-
ing por~land cement production, ~uch a~ environmetal consider-
ations, governmental regulation~, low return on investment
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1133021
hiah capital, energy and raw material costs and the high debtcomponent, all combine to form a deterring factor, thought
likely to curtail cement production in the future a~ compared
with other more profitable inve~tment~.
There have been ~everal improvements in the manufacture
of cement~ (1) longer kiln~, u~inq wa~te heat from the clinker
cooler ~iln and the preheater to dry material~ durinq grindings
(2) preheater ~y~tem~ and (3) u~ed by the Japane~e, a flash
furnace which provides about 90X calcination of raw material
feed prior to enterino the kiln, thereby increa~ing the capac-
ity of the kiln lOOX.
The pre~ent invention differs from the above c~ment prod-
ucing ~yRt~m~ in that they refer to the manufacture of port-
land c~ent utilizinq raw materials containing their natural
im~urity content together with an external ~ource of heat
enerqy which i~ in ~hort ~upply. while the method of the pres-
ent invention u~e~ i~proved raw material~ containing therein
a ~ufficient amount of heat enerqv to effect its o~n calcin-
ation.
~he present invention relate~ ~n part to canadian Patent
No. 597,757, but differ~ from the forementioned patent in
that the ~a~te coal materials utilized are cleansed of the
wat~r ~o~uble chemical ~ub~tance~ and renovable extraneou~
matter ~berein prior to their calcination, thereby providing
an improved raw Material having a more predictable and control-
a~le che~ical ingredient content.
In the case~ referred to above, the negative factor~ in
the production and utilization of portland cement are concer-
n~d with energy fihortaqe~, high enerqy and raw material cost~,
and utilization problem~- If these neqative factor~ were to be
1i~33021
mitiqated at a rea~onable increa~e in co~t which ~ould not
ne~ate the economic advantage of using improved raw cement-mak-
inq material~ a~ compared to conventional raw cement-0aking
material~, Ruperio~ cementing materials ~ould be produced at
a considerable ~avinq in material C08t~ manufacturing and
eneray expenditure.
The e~sential comPonent~ of portland cement are the oxides
of calcium, silicon, aluminum, and iron.
Varioua ra~ material~ may ~e used as the source of the~e
ingr~dient~ including~
L~me~tone~ Calciu~ carbonate, and ~ome mag-
nesia, silica, alumina, and iron
Clay and ~hale~ Alum~num ~ilicate~, clay, mica,
quartz, and other mineral~
~laq~ ~ime, alumina, magne~ia, mangan-
ese, and pho~phorus
Sand and ~and~tone~ Silicon dioxide (~ilica)
Gyp~ums Hydrated calcium ~ulfate
Iron ore, iron dustt Ferric oxide
Other po~ible material~ include, diatomite~ fluorspar,
pumice, flue duRt, pitch, red mud and rock, hydrated lime,
tufa, cinder~, and sludge.
~y the same token, in the coal mininq indu~try there is
a considerable amount of ~aste coal material Sfrom 25 to ~OX
of the coal material mined) left after the mining and proc-
e~ing of the marketable coal, and these coal mat~rials, in
-- 5 --
1133021
mo~t cases are diccarded a~ wa~tes. while the~e ~a~te coal
material~ cost a~ much in inve~tment caPital, con~truction,
recovery, labour, and enerqy costg per ton to produce,as
marketable coal material~, to date, no concentrated effort
ap~ears to have been made to utilize the materials or any
~ati~factory ~olution for reducinq the ~tockpiles of these
materialfi and cleanina up the contamination which has res-
ulted therefrom. Thi~ materia~, which i~ hereinafter referred
to a~ coal material con~i~t~ of low qrade coal, ~hales, bone
coal and orqanic material, and its chemical comPO~ition i8
either predominantly ~iliceoug or ~iliceoug and aluminou~.
The~e coal material~, a~ ~uch, have limited value for u~e as
raw cement-makinq materials because of the hiqh percentage
of impurities therein, but it ha~ been di~covered that when
they are crushed and ~creened, then Rubjected to a cleansing
process to remove the impurities therefrom a chan~e of physical
and chemical content take~ Place and the re~ultant product of
cleanYinq was found to have improved cement-making propertie~.
It ha~ been found, that the~e coal material~ may contain from
one third to three quarter~ a~ much B.T.U. heat value as the
marketable coal, a~ well a~ a requisite amount of the es~en-
tial chemical inqredient~ of portland cement. But it ha~ al~o
been found ~hat these coal materials, similar to raw clay~
and ~hale~, contain a hiqh percentaqe of imPurities~ however
it has been found that when thefie coal materials have been
cru~hed, screened then subjected to an expanding procedure
followed by a thorouqh leachinq that a~ much as 30 per cent
by weight of the coal material may be removed a~ water soluble
and adherinq ~u~stances therefrom. The resultinq ~oal material
in it~ cleansed state may be utilized a~ an improYed cementin~
material in one of three ways. (1) As an improve cement-
makinq raw material ~ource with its own calcinin~ fuel
-- 6 --
1133021
eneray ~ource, (2) A~ a pre-calcined and impurity-free addit-
ive ~uitable for u~e as an improved cement-makina material
ha~in~ pozzolanic propertie~ therein, and al80 having the
ability to increaRe the cement producina capacity of the cem-
ent kiln uithout the aid of additional cement producing fac-
ilitie~ ~hen added thereto, resultina in a dramatic reduction
in fuel energy requirements. (3) A~ a filler-aqgregate pozzol-
anic mixture hainq pozzolanic proPertieR therethrough, prov-
idinq thereby both fil~er and agaregate material~ having
pozzolanic properties suita~le for ufie a~ cement replacement
additive mixture~ to provide cementating miXturQs having a
hi~her utilizatlon value, lo~er C08t of purcha~e and tran~-
portation, and a superior con~truction material in both lime
and cement application6.
SUMMARY OF THE INVENTION
In the pre~ent invention, a method of produ~ing improved
cementing material~ i~ di0closed ~hich compri~es the steps of
cru~hin~ and ~creening low carbon content coal materials to
produce th~refrom coal particles having a maximum diameter of
3/8 of an inch. The coal materials first ~eing ~ubjected to
one or more wetting and dryinq cycle~ follo~ed by a thorouqh
leachina ~ith one, or a combination of, the air, vapour or
liquidR selected from the group compri~ing hot or cold air,
steam, hot or cold water J and an acid or a bace, to remove
water soluble and extraneous adhering ~ub~tance~ therefrom.
The impro~ed coal material~ are ~eparated into first, 8econd,
and third portion~. The f irst portion beinq added to a cement
kiln mix 2~ an improved raw material additive containing
therein it~ o~n fuel energy ~ource in a sufficient amount to
effect it8 own calcination. The ~econd portion being pre~
-- 7 --
11;~30Z~
calcin~d utilizinq it~ own fuel ener~y ~ource to effect it8
o~n calcination, at a te~perature of from 350F. to 850F.
The ~econd portion pre-calcined material~ being added to
ce~ent making mixture8 in a cement kiln a~ pre-calcined
and improved cement-makin~ materials having pozzolanic proper-
ti~, thereby ~aving fuel energy cOfit~ while providinq a more
durable cement product. Thethird portion being calcined util-
izing its own fuel energy ~ource to effect its own calcination,
at a temperature of from 800F. to 2000F., to make of it act-
ive pozzolanic ma~erial. The third portion calcined material~are recru~hed, ~creened and pulvOE ized to produce fine partic-
ulate pozzolanic material Pa~ina throuqh a 325 mesh ~creen
leavinq not more than 12X retained thereon, and larqer sized
pozzolanic aqqreqate material havin~ a maximum ~ize of 3/8 of
an inch and a minimum ~ize retained on a 325 mesh screen. ~he
impxoved cementing materialfi may be pre-calcined utilizing
their own fuel heat source comprising carbon and volatile
combu~tible~ th~rein, and the calcination of the 0aterial
carried out in a kiln, open pit, or other suitable mean~.
In a fir~t embodiment of the pre~ent invention, a clean~ed
cement-making raw material ~uitable for u~e afi a ~ub~titute
mixture for raw clay~ or shale~ used for the manufacture of
portland cement i~ produced. In the fir~t em~odiment, the first
portion of the cru~hed, ~creened and cleansed coal materials
are added to a ~ement raw material mixture in ~ub~titution
for conventional clayR or 6hale~ used in cement kiln mixture~
in the manufacture of portland cement~ in a proportion of at
le~t 50X of the kiln mixture. The coal materials are ~elected
from a group consi~ting of low carbon csntent coal, bone coal,
coal shale, clayey coal, red dog, near coal, oxidized coal,
leonardite, burned and unburned waste coal, bro~n coal, bitum-
-- 8 --
li;~3021
inou~ coal~ ~ubbituminou~ coal, liqnite coal, and uastes the-
reof. The burninq of t~e ra~ cement making materials into ce~ent
clinker i~ carried out at normal cement making temperatures
and iR advantaqeously pra~ticed by utilizing the inherent
B,T.U. heat value of the clean~ed coal-material additives
thereby effectinq a saving in fuel energy consumption. A second
embodiment of the pre~ent invention re~ults in an improved pre-
calcined cement-makinq additive ~uitable for increasing the
cement making capacity of cement ~iln~ while at the same
time effectinq a dramatic decrease in fuel energy C08tSo In
the gecond em~odiment the gecond portion crushed, screened
and clean~ed coal materials are soft burned to p~oduce a cal-
cined product from which organi~ impuritie~ have been driven
off by calcination, thereby effecting a fiecond cleansing of
the product of clean~in~ and calcination. The ~oft burning
of the cleanRed 2nd portion coal material i~ advantageously
carried out in a kiln, open pit or other ~uitable mean~, util-
izing its o~n fuel enerqy ~ource to effect it~ calcination,
and i~ done at a temperature of ~50F. to 850F. for fr~m one
hour to one ~onth dependin~ on the mean~ of calcination. The
exact temperature of calcination ~hould be determined for
cleansed coal material~ from each particular ~ite. The re~-
ultant calcined material may be of two different group~, with
the fir~t group being predominantly ~iliceous and containinq
not le~ than 70 per cent silicon dioxide and the ~econd qroup
con~i~ting of siliceou~ and aluminou~ material containing a~out
60 per cent of ~ con dioxide and 10 to 20 per cent of alum-
inum oxide. A third embodiment of the pre~ent invention res-
ult~ ~n an improved filler-a~qreqate mixture havina a lo~
apparent density and ~pecific gravity, and al~o having imp-
roved pozzolanic propertie~ in both the filler and ag~regate
portions of the improved filler-aqqregate mixture. In the
_ g _
11~3021
third embodiment the third portion cru~hed, Pcreened and
clean~ed coal material~ are converted ineo artificial pozzol-
anic filler and aq~reqate impurity-free mixture~, by calcining
the clean~ed coal material~ utilizina their own fuel enerqy
Rource at a temperature in the ranqe of 800~. to 2000F. until
volatile or~anic impuritie~ in the coal material~ are driven
off to ef~ect the double clean~ing of the pozzolanic mixture,
and thereafter crushing and arinding the double clean~ed cal-
cined material to a requi~ite finene~.
The clean~ed coal material ~ rd portion may ~e calcined
utilizina it~ o~n fuel heat ~ource to effect the second clean-
~inq of the coal material and con~ersion of the material into
an improved filler and aqqreqate mixture havinq pozzolanic
properties therethrouah in a kiln, open pit, or other ~uita~le
~ean~.
It ha~ been found that the temperature of calcination i~
a very important factor in the treatment of the clean~ed coal
material with the optimum te~perature of calcination thereof
depending upon the ~hemical compo~ition of the clean~ed coal
material which may vary from one coal mining site to another.
The exact temperature of calcination ~hould be determined
for material fro~ ea~h particular ~ite, although it has been
found that the calcination temperature~ dependinq upon the
chemical compoRition of the clean~ed coal materials may vary
within a wide ranqe, i~e.g 800 and 2000 deqree~ Fahrenheit. It
should be noted, however, that the temperature of calcination
~h~uld be at lea~t 50F. below the meltinq point of the mat-
erial utilized.
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11~3021
The doublv clean~ed calcined material may be of two dif-
feren~ qrou~, with ~he fir~t qroup beinq predominantly ~ilic-
eou~ and containinq not lefi~ than 70 per cent of ~ilicon diox-
ide and the ~econd qroup con~i~ting of ~iliceou~ and alu~inou~
material containing about 60 per cent of ~ilicon dioxide and
10 to 20 per cent of aluminum oxide.
To be ~uitable for the pre~en~ purpose, the calcined mat-
erial must be oru~hed, pulverized and air ~creened to provide
fine particulate pozzolanic material and larger sized pozzol-
ani~ material, and it ha~ been found that the deqree of fine-
nes~ of the fine parti~ulate pozzolanic material i8 a deter-
mininq ~actor. ~ine qrindina can be done in a ball mill or
by other ~uitable means and a finene~s of the material shall
be attained that ~hen ~ieved on a 325 mesh ~reen, the fract-
ion retained on the ~ieve ~h~ll not exceed 12 per cent of the
sieved material. The lar~er ~ized pozzolanic material is
crushed and ~creen~d to pxoduce ~izing~ therefrom in which
th~ maximu~ sizina diameter is 3/8 of an inch and the minimum
diameter is that which i~ retained on a 325 mesh Rcreen. The~e
proce~ed material~ in themselve~ ~ill poss~ little or no
cementitious value but in the pre~ence of moi~ture will che~-
ically react ~ith calcium hydroxide at ordinary temperatures
to form ~om~ound~ po~ses~inq cementitious properties. The cal-
cium hydroxide may be provided by the addition of a requisite
amount of Portland cement or hydrated lime to ~uit a particular
requirement. In certain application~ an alkali or Yalt~ of an
alkali may be added to enhance the pozzolanic activity of
a pozzolan-cement or lime mixture.
1:133021
BRIEF DE~CRIPTION OF THE DRAWINGS
Fiqure 1 iR a ~low diaqram ~howina the variou~ facet~ for
producin~ improved ~ubstitute ra~ cement-~akin~ materials for
u~e a~ cement-makinq kiln mixture~, ~herein the improv~d raw
materials have been cleanaed of uater ~oluble and extraneou~
adherinq matter ther~in and contain the requi~ite chemical
~nqredient~ needed for cement m~kinq as ~ell as a ~ufficient
amount of fuel heat ener~y to effect their o~n calcination
according to the fir~t embodiment of the pre~nt invention,
and
Figure 2 i~ a flo~ diagram showing the various facet~ for
producing an improv~d portland cement, and increasing the
cement producing capacity of exi~ting cement producing plant~
w~thout the building of new cement producing facilitieR, thu~
reducinq pre~ent fuel enerqy con~umption and future fuel ener~y
conRumption dramat~cally accordina to the ~econd embodiment
of the pre~ent invention,
and
Fiqure 3 i~ a flow diagram ~howin~ the variou~ facet~ for
produaina an improved filler and aggreqate ma~erial having
pozzalanic propertie~ therethrouah, and alRo havin~ a low
apparent density and ~pecific aravity, ~uitable for u~e as
a high volume filler-aq~reqate replac~ment additive mixture
in cement and lime a~plication~ accordinq to the ~hird embod-
iment of the present invention.
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11330Zl
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
In practicinq the pre~ent invention and with reference to
Figure 1, any type of low qrade coal or waste coal materials
may be utilized. ~uch coal material~ may have llttle or no
commercial value for their B-T-U- content, but are e~pecially
useful to the pre~ent invention- Such coal material typically
~ontain~ as much a~ 80X by weiqht of non-combustible material,
includinq moiYture, dirt and ash. Coal material~hi~ has been
found acceptable in practicinq the pre~ent invention in~lude~
coal, bone coal, coal shale, clavey coal, red doq, near coal,
oxid~zed coal, leonardite, burned and unburned waste coals,
bro~n coal, bituminous coal, ~ubbituminous coal, li~nite coal
and ~astes thereof. The coal wastes may result from the minin~
and procefisina of anv type of coal material whatsoever. The
more valuable coal material~ (such as anthracite coal) are
lePs desirable due to their lower content of non-carbon mat-
erialF.
The coal material i~ separated into firRt, ~econd and third
portion~ ~ho~e internal and external surface area~ are to be
expanded and lea~hed. The coal material i~ cru~hed and ~ized,
the siZing re~ulting in coal material havinq a maximum particle
diameter o~ approximately 3/8 of an inch (with no minimum diam-
eter).
The follo~inq example~ are illustrative of the invention
but are not intended to be limitin~ in any manner.
EXAMPLE 1
In producina improved raw material for u~e as substitute
material~ in cement kiln mixture~, calcination te~ were made
to determine the ~uitability of ~elected waste coal materials.
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11330:~1
It WaR found that the requicite chemical inaredient~ of coal
material~ utilized a~ cement-makina raw materials may be of
two different qroups, with the fir~t qroup beina predominantly
~iliceouc and containina not le~s than 70 per cent of ~ilicon
dioxide and the ~econd aroup consistin~ of siliceoUs and alum-
inou~ material containina about 60 per cent of ~ilicon dioxide
and 10 to 20 per cent of aluminum oxide. The followinq calcin-
ation te~t~ made on a typical coal waste material taken from
a coal wa~te dump at Lethbridae, Alberta ~hows the æuitability
of ~uch a material for utilization in cement-making kiln mixe~.
Te~ting Pure
Te~tsStandards Sample
1. Finesæ on #325 Max. 12.X 9~90
2. Pozzolanic activity Min. 600 p~i 1405 p~i
Con~lusion~Very qood #2, accepted for further tests
3. Lo~ on iqnition 2.35
4. Slli~on dioxide63.02
5. Aluminum oxide 22.34
6. Ferric oxide 5.88
20 7. Calcium oxide 2.72
8. Magnesiu~ oxide 2.50
9. Sodium oxide .50
lQ. Pota~ium oxide .06
11. Re~t 2.98
Concl u~ ionsAccepted f or furthe~ test inq
The first portion of the coal materials are expo~ed to
water for from one to ten hours. Thi~ may be accomplished by
spreadinq the coal materials over a lar~e area and either
sprinklinq or floodinq with water or by immer~inq the coal
30 materials in a water bath while travellina on a conveyor belt.
-- 14 --
1133021
Ry ~o wettinq the coal materialR, the coal material absorbs
about 5X of the water and expand~ it~ internal and external
Purface area appreciably. After the initial wetting, the coal
material~ are dried bV application of artificial heat or by
expofiure to fiunlight. It ha~ been found that by subjecting the
coal material~ to one wettin~ and dr~inq cy~le per day for a
period of five day~ may re~ult in a one hundredfold expansion
of internal and external ~urface area by creating numerous
~mall fracture~ throughout the coal ~aterial~. The coal mater-
ials are then ~ompletely saturated with water in order toleach water soluble and adherinq extraneous materials there-
from. This ~aturation may be for a~ little a~ one hour if
~ufficient water movement through the coal materials can be
effe~ted. If a ~ufficiently low-grade coal material i8 U8ed,
it is po~ible to remove up to 30X of the weight of the coal
material~ a~ water ~oluble and other removable debris in thi~
leachinq procefi~.
If it i~ de~ired to ~roduce a cleaner coal material to
further enhance it~ B.T.U. heat value, after leaching with
~ater, any one of a number of different acid~ or ba6e~ may
be u~ed, de~ending upon the type of material~ it i~ desired
to remove. For example, by ~ubjectinq the coal material~ to
a ~olution of either hydrochloric acid or ~odium hydroxide,
a wide range of chemical compound~ may be removed from the
coal material which would otherwise remain after leachin~ with
water. By leachina with either an acid or a ba~e may remove
variou~ chemical compsund~ which would otherwi~e remain, it
i~ a relatively expen~ive and time con~uminq operation which
would in mo~t ca~e~ be un-nece~sary-
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1133021
The improved ra~ cement-makina material re~ultina from
the above clean~ina of the coal material~ are mixture~ of
cement chemical inqredientR and an external fuel energy source.
The improved raw material~ are added to a cement-making mix
a~ a ~ubstitute for the clay or ~hale raw material~ normally
u~ed therewith. The material~ may be added to the mix prior
to the addition of the mix to the kiln or ~ub~equent thereto.
The percentaae addition of the clean~ed coal materials to the
cement-making mixture may vary from one type of cement to an-
other and i~ best calculated by the cement quality controlen~ineer for the particular cement plant. When added to a
cement-makin~ kiln mixture a~ part of the mix formulation the
cleanRed coal material~ contain a suffici~nt a~ount of fuel
heat enerqy to eff~ct their own calcination and contribute
to the calcination of other portion~ of the mixture, a~ comp-
ared to the other raw materials in the mixture which require
an ~xternal fuel heat energy ~ource to effect tbeir calcin-
ation. Therefore, in the fir~t embodiment of the pre~ent inv~
tion, an impro~ed ra~ material i~ provided for u~e in the man-
ufacture of portland cement which utilize~ it~ own energy~ourc~, re~ultlng ther~by in a more durable cement and a con-
~iderable saving in fuel energy con~umption and manufacturing
co~ts.
EXAMPLE 2
The method of the ~econd embodiment of the pre~ent inven-
tion re~ults in a doubly clean~ed calcined coal material ~hich
i~ an effective pre-calcined replacement additive for portion6
of the cement-makin~ mixture,~ervinq to enhance the cement prod-
ucinq capacity of exi~tina cement manufacturing plant~ without
the building of additional cement producing facilitie~, and
drdmatically reducinq the fuel heat eneray con~umption of ~uch
fue~ inten~ive manufacturing plant~. A clean~ed coal material
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11~3021
æecond portion similar to that utilized and proce~ed in Ex-
ample 1 i~ placed in a conventional oven and soft-burned at a
temperature of bet~een 350F. and 850F. ~ith limited access
to air for from 1 to ten hour~. The burning proce~s should be
carefully controlled BO a~ to prevent excessive ~elf-combustion
of the coal ~aterials. Durin~ the burnin~ proces~ the orqanic
impuritie~ in the coal material~ are driven off thereby effect-
ing a ~econd or double clean~in~ of the reæultant calcined
Coal material product. The calcined materials remaining after
thi8 double cleansinq and calcining processing have a very
low apparent density and a specific gravity of leRs than 2Ø
~ t uill be under~tood that the invention ~ay be embodied
in other ~pecific forms ~ithout departinq from the spirit
or central characteri~tics thereof~ The present examples and
embodiments~ therefore, are to be considered in all respects
as illu~trative and not re~trictive, and the invention iY not
to be limited to the detail~ given herein but may be modified
~ithin the scope of the appendQd claims-
The imProved calcined cement-makinq ~aterial at this staqe
ha~ many o~ the latent properties of an arti~icial pozzolanic
material, and on addition to the cement-making ~ixture will
contri~ute the~e propertie~ to the cement to enhance the cem-
entitious proper-tieg of the portland cement. The calcin~d mat-
erial i~ first crushed to a ~uitable ~izina for use in the
cement-makin~ mixture and may be added to the mixture prior
to, durin~ or after the di~charqe from the cement kiln. Since
the improved calcined material~ are already calcined it may be
de~irable to add the heated material to the uncalcin~d cement-
makin~ ~jxture immediately after their calcination ~o that the
heat value of the improved calcined material may contribute
its heat content to the uncalcin~d mixture. Alternatively,
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11330Z~
the im~roved calcined material may be added to the cementclinker after it~ di~charqe from the cement kiln and inter-
ground with the klinker and requi~ite activating agents to
make an ~mproved cement therefrom.
The amount of the improved calcined material addition to
the cement-makinq mixture~ prior to, during and ~ub~equent to
such addition will vary according to the type oP cement beina
manufactured, enerqy con~ideration~ and manaqement practice,
and i~ be~t determined by the cement-plant quality control
enaineer at the plant ~ite.
EXAMPLE 3
The method of the third embodiment of the pre~ent inven-
tion re~ult~ in an improved pozzolanic filler-aggregate mixt-
ure having pozzolani~ properties therethrough which i8 an eff-
ective cement replacement additive to provide long term durab-
ility under normal and aqqre~ive condition~ of u~e in lime
and cement, cementinq application~. A coal material third
portion similar to that utilized in Example 1 iB proces~ed a~
de~cribed in Exam~le 1, except that, the clean~ed coal mater-
ial~ are calcined at a hiqher temperature than that describedin Example 2 to make of them a more active pozzolanic material,
and ~ubje~ted to a fine qrindina procedure in part to ~erve
a~ a cement replacement additve. The third portion of the
cleansed coal material i~ placed in a conventional oven and
burned at a temperature of between 800F. to 2000F. under
controlled conditionY of burnin~, to make of them active pozz-
olans. It ~hould be noted, ho~ever, that the temperature of
~alcination ~hould be at least 50 deqree~ Fahrenheit belo~
the melting point of the material us~d. The exact temperature
of burninq should be determined for material from each partic-
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1~33021
ular site, althouqh it has been found that the calcination
temperaturefi dependina upon the ~hemical composition of the
coal material may vary within a wide range, i.e., 800F. and
2000F.
The calcined material may be of two different groups, with
th~ fir~t qroup beinq predominantly ~iliceouR and containing
not le~s than 70 per cent of æilicon dio~ide and the ~econd
group consistina of siliceous and aluminous ~aterial containing
about 60 per cent of silicon dioxide and 10 to 20 per cent of
aluminum oxide,
~ he calcined material ha~ in the proces~ of its calcination
r~ceived a ~econd or double clean~ing a~ de~cribed in Example
2, except that, it ha~ been burn~d at a higher t~mperature
a~ described above. After this calcination the materials are
divided ~nto two portion~, the fir~t portion being ground to
a finene~s wherein a fine particulate pozzolanic fillOE addit-
ive havinq a maximum diameter pas~ing through a 325 me~h ~creen
leavina not more than 12 per cent retained on the ~ceen i~
produced, and lara~r sized æecond portion calcined material
havln~ a maxi~um fiizing of 3/8 of an inch and predeterained
gradations thereof down to that æize retained on a 325 meRh
rQen are producQd.
The pozzolanic filler-agqregate materials resultlng from
the above processe~ conæistently develop higher tensi~e ~tren-
gths than portland cement alone as can be seen from the foll-
owing~ usinq Type 1 c~ment alone, 1 year strength 520 p~i, 5
year ~trength 460 p8i~ ~ith 30~ pozzolan added 1 year strength
~0 pæi, 5 year strength 550 p8i. Type 11 cement alone, 1 year
~rength 500 ~i, 5 year ~treng~h 520 p~i, with 30% pozzolan
-- 19 --
11;~30Z~
added 1 year ~trenath 620 p~i~ 5 vear ~trenqth 610 psi. Type 1
cement alone, 1 year ~trenqth 520 D~i, 5 vear strength 460 pci,
with 25X pozzolan added 1 ~ear strenath 680 p~i, 5 year 6tren-
ath 640 p~i. The above te~t~ ~ere made with cement and pozzolan
replacement by ab~olute volume. Pozzolanic materials may be
u~ed to replace up to 50 per cent of the cement volume in a
concrete mix without appreciable reduction of material strength.
Therefore, becau~e a cubi~ yard of pozzolan, wsigh~ only app-
roximately 63 per cent of the weioht of cement, if c~ment
and pozzolan are ~old at the ~ame price per ton, the u~er can
make a ~ubstantial ~aving in both cost of ~.aterial purchased
and freiqhtinq cost~ to a particular job site. Similarly,
while it i8 known to add chemicalg ~uch as alkali~ to pozzolan~
during proces~ing, I have found experimentally that both
coar~e and fine pozzolanic materialR of the present invention
may be activated by the addition of an alkali or the 6alts
of an alkali when used in 80il stabilization applications, to
achieve ~trength value~ double thofie normally attained, and
that the~e addition~ of alkalis to the ~oil-pozzolan mixture
were provided after calcination. Thus when both the pozzolan
fine particulate and the larger ~ized pozzolanic material~ of
the pre~ent invention are utilized in concreting application~
a further saving may be achieved by the reduced cost~ of
proces~ing the variou~ pozzolanic gradations.
It ~hould be further under~tood that the de~irable prop-
ertie~ to be aained by the u~e of the inherent pozzolanic
propertie~ of the clean~ed coal material~ after calcination
may be advantaqeou~ly practic~d in all three of the above
embodiment~ and i~ hereby made part of the pre~ent invention.
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1133021
IMPR~VED CEMENT-MAKING MIXTURE
When the oriainal coal material i~ procesged by an expand-
ina and leachina procedure to achieve a cleansed condition,
with the clean~ed coal materia~ havina fine particulate and
larqer ~ized material, the coal material~ may be utilized in
either one or ~ore of three methods. In the fir~t embodiment
of the present invention, both the fine particulate and the
larger fiized coal materials are utilized, being added to a
raw material cement-makinq mixture at the ~ite of a typical
cement-plant kiln. The coal material additive~ are added to
the mixture of raw cement-makin~ material~ according to a requ-
i~ite formulation for portland cement. Such a formulation, i~
de~ianed by the cement plant chemist to suit the de~ired type
of cement requir~d and the available raw material~, ~hich may
~ary from one part of a deposit to another and one district
to another. With due allowance beina made for the combustible
fuel ener~y content of the coal material~ (which u~ually
amount to bet~een 5000 and 8000 B.T.U. per lb of dry matter),
the amount of coal material added may amount to a~ much as
60 per cent of the combined cement-makinq mixture. In the
commerci~l production of portland cem~nt, the cement i~ manuf-
actured by two method~, the "~et process~ and the ~dry proce~s".
In the wet proce~, the raw cement-makinq materials (includinq
the clean~d coal materia~) are ~round and mixed with water
and fed to the kiln~ a~ a moi~t ~lurry, in the dry proce~, the
raw materlal~ (includinq the cleansed coal materials~ are gro-
und and mixed, and fed into the kiln~ in a dry state. In the
conventional cement kiln~ lined with refractory materials, a
blast of flame at the lower end heats the wet or dry r~w mater-
ials to approximately 2700F. (148Z.22~). The blast of flame is
- 21 -
1~33021
fueled by oil, qa~ or pulverized coal having a ~.T.U. value
in aXCe~R of 10,500. ( per pound of dry ~atter). As the raw
materials pas~ throuqh the kiln, they unite and form a new
sub~tance with it~ own chemical and phy~ical characteristic~.
which ~ake~ clinker about the size of marbleæ. This red hot
clinker i~ di~charged from the lower end of the kiln and i~
cooled- After coolin~, it can be ~tockpiled or i~mediately
around with added ~yp~um until it i~ so fine that 90X will
pa~ through a me~h with 32,400 me~he~/inch (6,452 cm).
~ecause the re~ultinq cement has u~ed considerably le~
fuel energy in it~ manufacture than by u~ing conventional
ra~ material mixture~, the addition of the clean~ed fine
particulate and larqer ~ized coal materials of the pre~ent
inv~ntion ha~ brouqht about a dramatic saving in energy
con~umption and provided a more contro~lable and predictable
cementing product. The chemical analy~is of a waste coal
material, ~hich has been calcined by~p~ ~ neous combustion
utilizina it~ own carbon and volatile content to effect ~UCh
calcination, i~ ~hown above in Example 1.
IMPROVED CEMENT PR~DU~TION CAPACITY
The ~econd embodiment of the pre~ent invention embodies
a novel method for doublin~ the cement producing capacity of
old and new cement producin~ plant~. After the wa~te coal
material~ of the ~irst and second portion~ have been expanded
and leached, and cru~hed to fine particulate wa~te coal mat-
erial and larger ~i~ed waste coal material (~ith a maximum
diameter of 3/8 of an inch~, the wa~te coal material~ may be
pre-calcined by the application of heat in a kiln, open pit,
or other suitable means. It has been found that the temper-
ature of calcination i~ a very important factor in the treat-
- 22 -
il33021
ment of the coal material with the optimum temperature of
caloination thereof dependina upon the chemical composition
of the coal material, which may vary from one mining site to
another. The exa~t temperature of cal~ination æhould be det-
ermined for material from each particular ~ite, although it
ha~ been found that the calcination temperature depending on
the chemical composition of the coal material may vary witbin
a wide ran~e from 35~0F. to 8S0Fahrenheit. It fihould be
noted, however, that the temperature of calcination æhould be
at lea~t 50 deoree~ below the meltina point of the material~
u~ed. The calcined material may be of two different ~roups,
with the fir~t qroup beinq predominantly æiliceou~ and contain-
inq not le~s than 70 per cent of ~ilicon dioxide and the
æecond aroup conæi~tina of æiliceoufi and aluminoufi material
containinq about 60 par cent of silicon dioxide and 10 to 20
per cent of aluminum oxide. The fipecific qravity of the cal-
ined material 6hown in the table in Example 1 wa~ 2.47, while
the fipecific gravity of Canada Normal Cement i8 3.14 and the
æp~cific qravit~ of Inland Portland Cement iR 3.11. In the
recalcination of the ~alcined material when added to a cement-
~akinq mixture the 108~ on iqnition i~ 1.19, while the lo~æ on
iqnition of ra~ materials normally u~sd in cement-makinq mixeæ,
dependin~ on the chemical composition may amount to as much a~
50X of the mixture. It will be ~een therefore that the addition
of the ~alcined material~ of the invention to cement making
mixture~ may increa~e the bulk volume output of a ce~ent prod-
ucing plant by aæ much a~ 100 per cen~ without the building
of additional cement producin~ facilitiefi~ ~hich would re~ult
in a dramatic sa~ina in fuel enerqy con~umption. hdditionally,
after the initial firfit clean~ino of the raw ooal materialæ
by an expandinq and leachin~ procedure, a further or double
clean~in~ i~ effected in it~ calcination drivinq off any re-
ainina orqani~ impuritie~ therein.
- Z3 _
1~330Zl
IMPR~VE~ P0~7,0LANIC FILLER-AGGREGATE MlX'rURES
The third em~odiment of the pre~ent invention embodie~
a novel method of ~reparina artifi~ially improved filler-
aaqreqate cementinq material~ havinq pozzolanic properties,
whether they be fine particulate or larqer ~ized aqareqate
materials. After the coal materials of the third portion have
been expanded and leached to effect a firRt cleansing, calcined
to develop it~ latent pozzolanic properties thereby driving
off orqanic impuritie~ therein to effect a ~e~ond or double
cleansina, and cru~hed and qround to fine particulate pozzol-
anic material havina a maximum particle diameter pas~in~ throu~h
a 325 me~h ~creen leavinq no more than 12X retain~d thereon,
and larqer ~zed particle ~izinq~ ranqinq downward6 from a
maximum sizing diameter of 3/8 of an inch down to that size
retained on a 325 me~h ~creen, both the fine particulate and
the larg~r sized pozzolanic materialR are utilized a~ cem~nt
and lime repla~ement additive~ on a volume replacement ~a~i~
în con~retinq application~. The double cleansinq of the coal
material~ prior to and subsequent to their conver~ion to`~eing
effec~ive filler-aqgeqate pozzolanic materials has re~ulted in
pozzolanic material~ having a low apparent den~ity and ~pecific
gravity, thi~ indicates a very high poro~ity in the materials
after calcination. A first advantage to be qained by the u6e
of the metho~ and material~ of the pre~ent invention ~ay be
~een from the follo~inq~ when the filler-aqqregate pozzolanic
materials are ~eparated into a firxt portion fine particulate
pozzolanic material and second portion larger ~ize pozzolanic
aq~re~te material, the fir~t portion fine particulate pozz-
olanic material may be U8ed to replace up to 50 per cent of
the cement volume in a concrete mix without appreoiable red-
uction of material ~trenqth. A cubic yard of the pozzolanic
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1133021
material of the present invention, however, weighæ only approx-
imately 63~. a~ much as compared with the weight of cement, and
a~ æuch replacement iR made on an absolute volume basi~, if
both the cement and pozzolan were to be sold at the same price
per ton, the u~er ~an make a ~ubctantial ~aving in cost of mat-
erial purchased and freiahting to a particular jo~ site~ A sec-
ond advanta~e to be qained by the use of the method and mater-
ials of the pre~ent invention is the provision of a second por-
tion highly-porous aqareqate material having active pozzolanic
propertie~ therethrough. Thus in cementing-application~, the
liquified cementing-aqent, and in a converse reaction the re~-
ultant hydrated lime or calcium hydroxide formed ln the hydrat-
ion of the portland ~ement is able to penetrate the porous
structure of the pozzolanic filler and agaregate materials to
react with the active pozzolanic sites therethrough, to make
therefrom a more ~olid, durable and chemically-resi~tant cem-
ented material. A third advantage to be gained by the use of
the method and material~ o~ the pre~ent invention i8 in perf-
ormance wherein, ten~ile strenath is materially higher at later
age~, compre~ive ~trengths which i~ less at early ages but
equal or greater at later ages, heat of hydration and temper-
ature rise i~ reduced, permeability is much le~#, sulphate res-
istance i~ increased, alkali-aggregate expanSion is reduced,
and workability i8 improved. A fourth advantage to be gained
~y the use of the method and material~ of the present invention
iR that no external source of fuel energy wa~ utilized or need-
ed in the preparatîon of the present pozzolanic filler-aggreg-
ate material~, thereby effecting the conservation of lOOX of
the normal external fuel energy requirements u~ed to prepare
~uch pozzolan material~- A higher temperature of calcination
i~ u~ed for pozzolan preparation and ranqe~ from 800~F. to
2000F. for different materials~ It should be noted, however,
_ Z5 -
1133021
that the temperature of calcination should be ~t least 50 deq-
rees below the meltinq point of the materialæ calcined. The
calcined material~ may be of two groups, with the first group
beinq predominantly ~iliceous and containinq not le88 than 70
per cent of ~ilicon dioxide and the second group consisting of
siliceous and aluminou~ material containing about 60 per cent
of ~ilicon dioxide and 10 to 20 per cent of aluminum oxide.
In practicing the present invention external fuel energy
conservation (external meaning, fuels additional to those con-
tained in the coal material) amounting to as much as 50X i6effected in the first embodiment, 50X in the second embodiment
and up to lOOX in the third embodiment by utilizing the inter-
nal fuel energy content of the clean~ed coal material which
has been found capable of providing ample heat energy at a suf-
ficiently high range of temperature~ to effect the conversion
of the cleansed coal mater~al~ into highly active pozzolan mat-
erials. The total utilization of the coal resource i8 no~ comp-
leted by the sale of the marketable coal, and not entirely by
the utilization of the waste coal material as described herein,
~0 but i6 completed when the heated ga~es generated by the cal-
cination of the waste coal material are recycled to recover
and utilize the surplu~ heat energy and organic coal impurity
content~ In a first instance the surplus heat energy is util-
ized to aid in the calcination of the non-coal portion of the
cement-making mixture of the first embodiment of the invention,
and also of the second embodiment, and again to serve as an
aid in the calcination of the non-coal porti~n of the pozzolan-
cement mixture of the third embodiment. It is well known that
most of the chemical~ ~ecovered from gaseæ and oils are avail-
able from coal materials, gases and oils being used now becauseof their ease of handling. Since these same organic chemicals
can be delivered by the method of the present invention in gas-
eous form and in a heated state,large potential markets abound.
- ~6 ~
