scispace - formally typeset

Journal ArticleDOI

The Development of the Rotary Kiln and Its Application to Various Chemical and Metallurgical Processes

01 Sep 1914-Journal of Industrial and Engineering Chemistry (American Chemical Society)-Vol. 6, Iss: 9, pp 754-760

About: This article is published in Journal of Industrial and Engineering Chemistry.The article was published on 1914-09-01 and is currently open access. It has received 5 citation(s) till now. The article focuses on the topic(s): Rotary kiln.
Topics: Rotary kiln (67%)

Content maybe subject to copyright    Report

7
54
THE JOCRLVAL
OF
INDUSTRIAL ,4,VD E-VGINEERING CHEMISTRY
Vol.
6,
NO.
9
The method is simple and easy to manipulate and
0.1024
the results obtained were very satisfactory. It was
Grains
Hglz
also found to be useful for the assay
of
mercuric iodide
1.01
and oleate of mercury.
n
97
Grams HgIz
0,1004
Powdered mercuric iodide-2 assays (0.1 gram sample).
.
,
.
.
,
.
.
Tablet triturates,
1/30
grain-6 assays (sample, 30 tablets).
, ,
.
.
0.97
ANALYTICAL DEPARTYEKT,
PaRKE,
DAVIS
&
CO.
0.99
0.98
1
.oo
DETROIT,
MICHIGAN
1
4
LABORATORY
AND
PLANT
1
THE DEVELOPMENT
OF
THE ROTARY KILN AND ITS
METALLURGICAL PROCESSES1
By
RICHARD
K MEADE
BLACK ASH REVOLVERS
and the molten charge poured through the openings
APPLICATION TO VARIOUS CHEMICAL AND
into cars placed below.
REVOLVING METALLURGICAL FURKACES
The counterpart of this furnace
is
found in the
metallurgical industry in the Bruckner ore roaster,
largely used at one time in this country for calcining
chemical engineer, invented a revolving black
ash
and desulfurizing copper
ores.
The Bruckner
roaster
furnace but the furnace as he built it was not a success.
It remained for Elliott and Russell some five or six
years later to design a furnace which would operate
successfully and this was employed in the works of the
Jarrow Chemical Company, South Shields, Eng.,
where the practical difficulties encountered in its
operation were overcome by
J.
C.
Stephenson. The
apparatus became quite popular after this and was
generally introduced into alkali works both in England
and elsewhere.
The black ash furnace or “revolver” (Figs.
I
and
2)
consisted of a horizontal cylinder
of
wrought iron about
30
ft.
long by
IO
ft.
in diameter lined with fire brick and
As
as
184’
w’
Pattinson,
an
FIG.
2-sODA-ASH
REVOLVER,
EMPTYISC
THE
CH.4RGE
does not materially differ from the soda revolver
except that the evaporator flue is omitted and often
the fire box is a car running along
a
track at right
angles to the center line
of
the furnaces. In this way,
the car can be connected with any furnace and allowed
to remain there until the sulfur ignites, when it may be
FIG.
~-SODA-ASR
REVOLVER
provided with two bearing rings or tires of steel which
rested upon four small flanged wheels, or rollers.
The cylinder was revolved by means of
a
girth gear
meshing with a pinion, which latter was driven by
means of a small steam engine. The cylinder was
provided with openings at either end, communicating
with
a
furnace and a lye evaporator respectively. The
gases from the furnace passed through the cylinder
and melted the charge, the cylinder being revolved
meanwhile. The waste gases passed over into the lye
evaporator and the heat was utilized there. The
furnace was ‘not continuous but was operated by
charaina the materials
(a
mixture
of
salt cake,
II
FIG.
3-sIEMENS
REVOLVING
STEEL
FURNACE
Na2S04, limestone and coal) into the cylinder through
man-holes in the side of the former, from hoppers
placed above the cylinder. These openings were then
closed by suitable covers and when the charge was
finished the covers were removed, the furnace tilted
of
Chemical Engineers, Troy,
N.
Y.,
June 17-20, 1914.
wheeled to the next cJ71inder and a current
Of
air
allowed to Pass through the first cylinder to burn
off
the Sulfur.
In
1869,
Siemens, the celebrated English metal-
lurgist, applied a somewhat similar furnace (Fig.
3)
1
Presented at the 6th Semi-annual Meeting
of
the American Institute

Sept.,
~914
THE
JOrRSdL
OF
IiVDl-STRIAL
to the manufacture of steel direct from thf. ore and
Danks. of Cincinnati, Ohio. about this time invented
a rotary puddling furnace
m
1
ich worked upon the same
principle. Both the Siemens and the Danks furnace
were extensively used.
Crampton, another Englishman. in
I8;z.
took out
a
patent upon
a
rotary puddling furnace (Fig.
4).
He
proposed to heat his furnace. however, with powdered
coal. Crampton’s first furnace
was
used at Woolw-ich
Ll.I*
1
f
8
.
t
1
1
I*,
\
.-
r
FIo.
4-cRAMPTOX’S ROTARY
PUDDLIKG
FVRKACE
Arsenal, in
1873,
and also at other English iron works.
His furnace differed from those of Siemens and Danks
in that the cylinder was open at one end only, the jet
of fuel and air being blown in below while the gases
passed out above.
Crampton evidently understood the value of pul-
verized coal.
It
is of interest to note that this form of
fuel. after nearly twenty years of successful use in the
cement industry,
is
just beginning to be used to any
extent for puddling iron, and yet Crampton suggested
that it be
so
used over forty years ago. His furnace
was designed not only to save the labor
of
fettling and
rabbling the iron but also that of stoking the coal
on the grate.
THE ROTARY
CELIEKT
KILK
X
few
years after this, Crampton conceived the idea
of using a rotary furnace heated by pulverized coal for
burning cement. but, although he took out a patent
in
IS;;
on
his process,
I
can find no mention
of
his
ever ha\-ing put his invention into practical use.
In
ISS~,
an English engineer, Nr. Frederick Ran-
some.
received a patent upon a continuous rotary
furnace process for burning Portland cement. Ran-
some’s furnace differs from those which have been
mentioned above in that it consisted simply of a
straight cylinder. supported upon rollers and revolved
by gears, tilted slightly at an angle to the ho5zontal.
The effect of this tilting was that when material
was
fed into the upper end the revolutions
of
the cylinder
caused the material to move through the furnace.
-4s
the lower end
was
left entirely open the action
of the furnace
was
continuous, the material to be
calcined passing in at the upper end and the burned
material
out
at the lower
in
a steady strear. This
is the present day “rotary kiln” (see Figs.
6
and
7).
Ransome’s idea was faulty in that he expected to
eliminate the necessity of grinding the burned clinker
by his process rather than to effect any economy of
labor or fuel in the hurning process itself. His idea
-1
SD
ESGIAVEERILVG CHEMISTRY
755
was that by calcining the ram material in the form of
a
fine powder in such a furnace the clinker
so
obtained
would be fine also and hence would not need to be
ground. He entirely overlooked the fact that semi-
fusion must take place in order to form Portland
cement and that
i’n
this condition the material m-odd
be sure to stick together and form small nodules.
Instead of making a clinker easier to grind the rotary
kiln made a clinker much harder to grind than that
burned by the upright kiln. Ransome’s process was
given quite a prolonged trial at a cement works at
Grays. Essex, England, using gaseous fuel, but did not
prove c
o
m
m
er ci all
y
s
u cc e ssf ul
.
In
the same year, H. Mathey, of Xew York, took
out
a
patent upon
a
revolving furnace‘(Fig.
j),
some-
what similar to that of Ransome except that, instead
I
1
FIG.
S-MATHEY’S
REVOLVING
LIME
.4ND
CEMENT
KILN
of inclining his furnace, he obtained the same effect
by having the center line of the kiln horizontal but
the kiln itself was made slightly cone shape, the
material being fed in at the smaller end. He pro-
posed to heat his kiln by
?
grate fire and to employ
it for burning lime and hydraulic cement.
In this country,
a
small cement plant in Oregon
attempted to use Ransome’s kiln, in
1887,
but the
attempt here too proved a failure. About the same
time the Atlas PortJand Cement Company began to
experiment with Ransome’s kiln, first at East King-
ston, New York, on wet materials and later with success
upon the cement rock
of
the Lehigh District in
Pennsylvania. In Ransome’s original patent, he pro-
posed to heat the kiln by producer gas but its de-
velopment in this country was made possible by the
use
of
crude oil.
At
first these kilns were only
40
ft.
long, but
it
was soon found more economical to
lengthen them
to
60
feet, and now the usual length is
between
IOD
and
I
jo
it.
with diameters ranging from
;
to
9
feet.
The rotary kiln came quite generally into use in
this country following the results obtained by the
-4th Portland Cement Company. About
1896.
powdered coal in place
of
oil came into use and from
that time on all new plants for the manufacture of
Portland cement installed rotary kilns, employing
pulverized coal as a fuel, except in localities where oil
or natural gas are cheaper. Practically all Portland
cement made in this country and much of that in
England and Germany is now burned in rotary kilns.

7
56
THE JOURNAL
OF
I;VDC:STRIAL AND ENGINEERING CHEMISTRY
Vol.
6,
NO.
9
It is not the purpose of the present paper to treat
of the employment of the rotary kiln in cement burn-
ing, as the literature obtainable
on
the subject is
voluminous, but instead to call attention to its em-
ployment in other industries and
to
suggest new uses
to which it may be put.
DESCRIPTION
OF
THE
ROTARY
KILS
The rotary kiln (Fig.
6)
in its usual form consists
of
a cylinder, from
6
to
9
feet in diameter by from
60
to
150
feet long, made of steel sheets from to
inch in thickness, lined with fire brick and in-
clined at a pitch of from
3/8
to
3,
4
inch
to
the foot.
The steel sheets are held together with single strap
butt joints, as these joints resist expansion strains
due to heating better than lap joints. This cylinder
is supported
on
two
or
more tires made
of
rolled steel,
and having a face of from
6
to
12
inches and a thick-
ness of at least 4 inches. They run each on heavy
friction rollers made of cast steel, which are often
mounted in pairs
on
a rocker. The kiln is driven
by a girth gear situated usually near its middle or
upper end, and a train of gears, actuated either by a
line shaft or a motor. The upper end of the kiln
projects into a brick flue which
is
surmounted by
a
steel stack. The flue is provided with a door at the
bottom to take out the dust which accumulates there.
The lower end of the kiln is closed by
a
hood into
which the kiln projects. Sometimes this hood is made
stationary with movable fire-brick doors, but oftener
it is mounted
on
a movable carriage. The front wall
of the hood is provided with
two
holes, one for the
entrance and support of the burning apparatus, and
the other for observing the operation
of
the kiln and
for inserting bars to break up the rings formed and
entering the stack. This latter plan has the effect
of a damper, crowding the heat more to the front of
the kiln.
It
probably lessens the output somewhat,
since the choking cuts down the amount of coal that
can be burned.
The short
60
foot kilns usually bear
upon
two
or
three tires and longer kilns often on four or more
tires. The kilns are always provided with two or more
horizontal thrust roller bearings to keep the kiln
on
the
vertical roller bearings.
The material to be burned is fed into the kiln
through a horizontal water-jacketed screw-conveyor,
or
more generally spouted directly hto the kiln through
an
inclined pipe of cast iron. Wet materials are often
pumped directly into the kiln. The ram- material
feeding device is attached directly to the driving gear
of
the kiln
so
that when the kiln stops the feed also
stops. The material
to
be burned is stored
in
large
steel bins above the feeding device
so
that a constant
and regular supply may be always at hand.
The kiln is heated by a jet of burning fuel, usually
powdered coal where the ash of this is not objection-
able. Where the ash of the fuel is objectionable
producer gas is usually employed. Where oil
or
natural gas are cheaper they are always used as they
are also the most convenient fuel.
SODULIZIXG
ORES,
CINDER, ETC.
About
1900,
various metallurgists were experi-
menting with the rotary kiln for nodulizing flue-dust,
fine iron ores, etc. Edison conducted experiments,
for example,
on
the nodulizing of the fine concentrates
obtained from his magnetic separators and several
iron and steel concerns experimented with the use
of
the kiln to nodulize flue-dust and fine iron ores.
Within a few years plants were established for the
latrer purpose. The Pennsy1vsni:t
Stee:
Company
were
among the early users
of
nodu!izing
ki!ns.
em-
ploying one on Cornwa!l concentrares. From
stJou~
the yc:ir
1904
on.
rhe
parenr office has issced nizny
parcn-.s
on
various processes
ior
nodulizing
ores.
The
rorary
ki!n has furnished a simple ii:eans
of
uti:izing thc
soft
clayey ores, such as
that
or‘
the
II~yari
field in Cuba. Practica:!y all
of
the schemes
tried for placing this ore in satisfactory condition for
:he
blasr
iurnacc were unsrlti5f;.crory unci: :he roynry
kiln
!vas
tricc!.
The
plant in Cuba nolv
consists
of
twelve
kilns
IOO
fee: long ‘eleven
Gi
these lxing
IO
feci
and
one 9 (err in diameter). and hc.s
:i
cr,paci:y
of
]
FIG.
6-ROTARY
KILN
repair the lining. The lower part of the hood is partly
open and through this the clinker falls. Air for com-
bustion also enters here. Fig.
6
represents a com-
pleted kiln.
The usual diameter of a
60
foot rotary kiln unlined
is from
6
to
7
feet, of a
IOO
foot rotary from
7
to
8
feet and a
125
foot rotary
8
to
81/2
feet. Nost of them
are made the same diameter throughout, though some
of them are made, say
6
feet
6
inches in diameter
for the first
30
feet and then taper through
IO
feet
to
a
diameter of
j
feet
6
inches for the remaining
20
feet; others taper for the last
IO
or
Ij
feet before
from
Ijoo
to
2000
tons
of
nodules per
24
hours.
Chemical manufacturers also began about
1904
nodulizing pyrites cinder or “blue billy
selling’ the
nodules
to
the blast furnaces. This was possible
because the process not only nodulized the cinder,
but also desulfurized it. This practice has now be-
come quite general and nearly all large sulfuric acid
manufacturers whose locations permit of
a
ready sale
of the product to the blast furnaces
now
nodulize their
cinder. When copper bearing pyrites ore is roasted
for the sulfuric acid and then leached for the copper,
the iron oxide residue
is
now nodulized and sold to
the blast furnaces, the wet residue being conveyed
direct from the leaching tanks to the kiln.

Sept.. 1914
THE
JOl-R*Y.!L
OF
I.ZTD17STRIAL
ASD
ENGIiL‘EERIiJTG CHEJLISTRY
757
During thc past year, a great deal of interest has
been aroused in the possibility of treating fine copper
ores and smelter flue-dust in the rotary kiln and one
of niy associates, Nr.
J.
H. Payne. has succeeded in
solving this problem. rotary kiln installed and
designed according
to
his specifications has now been
working successfully on such material at the plant
of the
U.
S.
Metals Refining Co., Chrome,
h*.
J.. for
over a year. The fine ore question is a very serious
one to the copper smelter because of the fine condition
of the ore resulting from concentration.
The New Jersey Zinc Co.. also, have employed
a
rotary kiln for nodulizing fine franklinite ore.
From
ore containing
17.1
per cent zinc, nodules con-
taining
20.4
per cent zinc were obtained with little or
no
loss
of
metal.
The process of nodulizing does not differ very
materially from other rotary kiln processes. The
main point to be watched is the regulation of the
temperature and the principal difficulties encountered
are the sticking
of
the charge to the walls
of
the kiln.
In
1585,
a patent was granted to Henry Mathey
of
Kew York, on a process of making lime which con-
sisted “in first crushing the stone to a suitable degree
of fineness. then burning the crushed or pulverized
stone in a revolving cylinder, whereby the particles
of stone are subjected to a constant and uniform
heat.’’ In the description
of
his process, Mathey
proposed to crush the limestone to pass
a
KO.
4
or 6
mesh screen and to burn it in the rotary furnace which
he invented and which has been described previously.
Siemens also mentions the use of his rotary furnace
for burning lime.
I
believe some experiments on
burning lime in a rotary kiln were also made shortly
after this
at
one of the cement plants in the Lehigh
district and also
b17
the California Portland Cement
co.
In 190j or 1906.
the Sew York Lime Co. started
to burn lime at Satural Bridge.
N.
Y..
using a
IOO
it.
X
6
ft. rotary kiln fired by prodccer gas, and
shortly after this rotary ’lime kiln plants were built
by both the Union Carbide Co. and the Aluminum
Ore
Co.
There are
now
in operation quite a number of
rotary kiln lime plants most of which, however, are
supplying lime for chemical and metallurgical purposes
for reasons given be1.0~.
-4n application
of
the rotary kiln to burning lime,
of peculiar interest to the chemical industry, is the
employment
of
the rotary kiln for burning lime from
the waste carbonate of lime or “lime sludge” obtained
from the manufacture
of
caustic soda by the action of
lime on soda ash. Large quantities of this waste are
produced by the paper-pulp manufacturers and also by
caustic soda works. Lime-sludge is also produced
by beet sugar manufacturers. The rotary kiln is now
employed for burning waste lime from both industries.
The rotary kiln is especially suited to burning these
sludges as they can be introduced into the kiln in the
form
of
a thin mud or “slurry.”
For burning lime, producer gas is usually employed
for heating the kiln but, when great purity and absence
BURSISG LIME
of
color are not required, pulverized coal can be used
to advantage.
The limestone to be burned is usually
crushed to pieces of one-half inch and under. before
being introduced into the kiln.
The objection to the
rotary kiln for lime burning is principally due to this
latter fact. The lime produced
is
in the form
of
dust
and small pieces. whereas for building purposes most
users iTish lump lime. This preference
is
due entirely
to ignorance. Fine lime is usually the result of air
slaking and, as air slaked lime is partly carbonated,
it is natural that the builder should demand lime in
lumps. On being supplied with rotary kiln lime, he
supposes it is air slaked lime and refuses it. Such
lime. however, is particularly suited
to
metallurgical,
chemical and agricultural uses, and to hydrated lime
manufacture, for all of which pur’!poses crushing
of
the lime is necessary.
The advantages of the rotary kiln are its low labor
cost of operating. the uniformity with which it burns if
properly handled and its high fuel efficiency. The
labor item of lime burning can be cut in half by opera-
ting a rotary kiln and a fuel efficiency of six tons of
For this
reason where lime is desired for chemical uses, for
hydrate manufacture, for wood pulp plants, for
fertilizer and in short, where lump lime is not neces-
sary, the rotary kiln will make lime cheaper than any
other form of kiln. The first cost of a rotary plant is,
however,
jo
per cent greater than that of an ordinary
grate-fired vertical kiln plant of the same capacity but
it is
2j
per cent cheaper than a producer gas plant of
like output.
One great advantage
of
the rotary kiln is the fact
that small stone can be burned in it. It is also suited
to burning stones which break up into smaller pieces
and crumble on heating. Such stone cannot be
burned in upright kilns because of the stopping
up
of the draft by the spalls.
-4
rotary kiln lime plant usually consists of a pre-
liminary gyratory or jaw crusher for breaking down
the big stone. This is followed by some form of
break down mill or crusher to reduce the stone to pieces
of inch in diameter and under. These secondary
crushers are usually of the swing hammer type. The
stone goes from the crusher to a bin and from this is
fed automatically and evenly into the kiln. From
the kiln the lime drops into a rotary cooler where it is
cooled.
It
is then elevated into
a
bin from which it
is
drawn for shipment as needed. At several lime
plants boilers are installed at the ends of the kiln
making use of the waste gases from these to generate
steam.
,lime for one ton of fuel has been obtained.
ROASTIXG OF BAUXITE, CHEMICALS, ETC.
Rotary kilns are now employed for drying and
dehydrating many ores and chemicals. In 1902,
a
rotary kiln was installed for the dehydrating
of
bauxite,
and this kiln has now come quite generally into use
for
this purpose. Producer gas is generally employed
for
heating such kilns, although oil or natural gas would
be the
most
desirable fuel where either could be em-
ployed without too great expense.
A
very high grade of ferric oxide pigment
is
now

7
58
THE
JOURIVAL
OF
INDL-STRIAL
made in the rotary kiln by heating the residues ob-
tained from spent pickling solutions. In this case, the
salt has merely to be dehydrated, the sulfur trioxide
driven
off
and the ferrous oxide converted to the higher
oxide.
.
One large chemical company has
a
rotary kiln plant
for dehydrating salts containing chemically combined
water. The plant consists of four rotary kilns, each
120
ft.
long and
7
ft.
in diameter. Producer gas is
used to heat the kilns and the exit gases from the
kiln are passed through
a
dust collecting and washing
apparatus where they are scrubbed to recover valuable
dust which they carry from the kiln.
The dust problem must always be considered in
rotary kiln installations and where the dust represents
a
loss
of valuable.materia1 or is likely to constitute
a
nuisance to the community arrangements should be
made to catch this dust. With small installations,
a
settling chamber and water sprays will prove satis-
factory but with large installations the problem is
not
so
simple.
The rotary kiln, fired directly by a powdered coal,
oil
or gas flame, is one of the most economical methods
of
drying and dehydrating materials known.
It
is
extensively used for drying blast furnace slag which
has
been granulated by water in the cement plants of
the Universal Portland Cement Co. and would offer an
excellent method of drying washed phosphate rock.
ore, etc., where large quantities of very wet material
are to be dried.
MAKING BICHROMATES
Mr.
J.
H. Payne, by employing a highly oxidizing
atmosphere in the rotary kiln has been able to produce
sodium chromate using this form of furnace in place
of
the reverberatory furnace now generally used for
this purpose, and
a
patent has been granted him
on
this process.
BURNING PYRITES
Ducco, an Italian chemical engineer, in 1906
sug-
gested the use of the rotary kiln for burning pyrites
for the manufacture of sulfuric acid, the pyrites being
fed in
at
one end and the air for combustion entering
at
the other. His first experiments on such
a
furnace
were made in the works of Rifredi, near Florence,
where the practicability of the scheme
was
demon-
strated. Various other acid plants in Italy also use
the rotary kiln for this purpose.
As
employed by
Ducco, the internal surface
of
the kiln
was
provided
with spiral grooves to facilitate the descending move-
ment of the ore without the production of much dust.
In this country, the Pyrite Engineering,
Co.,
Capth-
age,
N.
Y.,
are exploiting
a
system of roasting pyrites
in
a
rotary kiln upon which they hold patents. They
have installed such
a
kiln at the plant of the Hinckley
Fiber
Co.,
Hinckley,
N.
Y.
This plant, at last ac-
counts, was working successfully, burning an ore which
sometimes ran as low as
20
per cent sulfur without
employing any auxiliary heat. The pyrites is being
roasted just
as
it comes from the ground, after being
crushed to
"4
inch and down, using both lump and
fines together. The lower end of the kiln is closed,
a
series of trap doors which work automatically allow
AJD
ENGISEERING CHEMISTRY
Yol. 6,
No.
9
the cinder to fall from the kiln without the admission
of too much air. When the kiln is first started, the
pyrites ore is kindled by means of
a
jet of burning
sulfur.
In
view of the fact that' the rotary kiln is much
more simple than the ordinary mechanical rabble
furnace, it is remarkable that more acid and pulp
manufacturer? have not given them
a
trial.
,4
novel use
of
the rotary kiln is in the production
of sulfur trioxide. This process is in use at
Hochst,
at Hruschau and at Hamburg. Burnt pyrites, which
has been soaked in ferrous sulfate solution, is passed
into the upper end of
a
rotary kiln, the hot gases
from the sulfur burners being admitted
at
the lower.
The kiln (Fig.
7)
is provided with shelves which pick
the material up
as
the kiln revolves and cascade
it
in
FIG
']-ROTARY
TUBE
FURNACE
FOR
MANUFACTURE
OF
SULFURIC ACID
a
spray of fine material through the current of gas
passing through the cylinder.
In the uppe.r and colder
part of the tube, the sulfur dioxide gas is absorbed
by the burnt pyrites.
As
this works its way down
through the cylinder to the lower end, the heat liberates
all the sulfur dioxide in the form of vapors of sulfur
trioxide and sulfuric acid.
The gases are freed from
dust and absorbed
as
usual. The burnt pyrite falls
into a chamber at the lower end of the kiln and is re-
employed by soaking in ferrous sulfate solution ob-
tained from the treatment of pyrites containing
copper.
MANUFACTURE
OF
SULFIDES
By designing the kiln
so
as to cut down the amount
of air entering the firing end, it is possible to procure
a
reducing atmosphere in the kiln
so
that
it
can be used
for the reduction of sulfates to
sulfides.
In
this case,
the problem is
a
particularly easy one because' of the
low temperatures necessary in this work. Calcium
and barium sulfate can both be reduced to sulfides
with little trouble using
a
grate fire to heat the kiln.
Both are now made commercially in rotary kilns.
Indeed, all of the more modern plants for the manu-
facture of barium sulfide are equipped with rotary
kilns, and
a
large quantity of this compound is now
produced and employed in the manufacture of litho-
phone, blanc fixe, barium salts and in various chemical
processes.
In manufacturing barium or calcium sulfide, the
barytes or gypsum, as the case may be, is crushed and
mixed with from
zj
to
30
per cent of coarsely ground
coal. The mixture is then passed through a tube mill
or some other type of pulverizer where sufficient water

Citations
More filters

Journal ArticleDOI
Abstract: Rotary kilns are widely used in several branches of the chemical industry. In order to control the temperature of the solid and the gas flowing through the kiln, it is important to understand the heat exchange phenomena that occur. The design and construction of a novel experimental device to study heat exchange in rotary kilns is described. The device, which comprises a rotary kiln equipped with an external electrical heating system, enables the study of the influence of various parameters such as the solid flow rate, the kiln inclination angle, the rotational speed, or the presence of lifters on heat exchange and in particular on the heat exchange coefficient between the solid and the wall. Preliminary experimental results concerning the influence of the solid flow rate and the rotational speed on the solid-to-wall heat exchange coefficient are presented.

23 citations


Journal ArticleDOI
Marie Debacq1, Marie Debacq2, Stéphane Vitu3, D. Ablitzer2  +2 moreInstitutions (3)
Abstract: The transverse flow of cohesive powders in rotary kilns equipped with lifters was studied experimentally and theoretically. A laboratory device was built up in which the flow of uranyl difluoride (UO2F2), uranium sesquioxide (U3O8) and uranium dioxide (UO2) powders was filmed, recorded and analyzed using partly manual image analysis techniques. Experiments were performed both at room temperature and at high temperature. A constitutive law describing the powder discharge was derived, involving a relationship between the volume fraction of powder contained in a lifter and the angular position of this lifter. This law based on geometrical calculations is successfully compared with the experimental results of unloading.

20 citations


Cites background from "The Development of the Rotary Kiln ..."

  • ...For over a century [1], rotary kilns have been widely used in the inorganic chemistry industry....

    [...]


Journal ArticleDOI
Marie Debacq1, Marie Debacq2, Phahath Thammavong3, Stéphane Vitu3  +3 moreInstitutions (3)
Abstract: The axial and transverse solid distribution of a cohesive powder in flighted rotary kilns was calculated from an original method based on the lifter discharge law previously determined, geometrical calculations and supplementary measurements (in particular the fall velocity of the powder at high temperature). At a given axial position, the quantity of powder falling through the gas, the total quantity of flighted powder as well as the quantity remaining in the bulk are thus calculated; the axial bed depth profile is obtained from the Saeman-Kramers-Afacan model.

12 citations


Additional excerpts

  • ...For over a century (Meade, 1914), rotary kilns have been widely used in the inorganic chemical industry....

    [...]


Journal ArticleDOI
Mortaza Gholizadeh1, Chao Li2, Shu Zhang3, Yi Wang4  +3 moreInstitutions (5)
Abstract: Pyrolysis is a promising process to convert municipal waste into fuels in solid, liquid or gaseous forms or value-added chemicals. The composition of pyrolysis products is affected by many factors, among which the configuration of the pyrolysis reactor is one of the essential parameters, as it influences the heat transfer, mass transfer, residence time of the reaction intermediates, interaction of the volatiles, etc. Up to now, there are varied types of pyrolysis reactors including the rotary-kiln, fixed-bed, batch and semi-batch, fluidized-bed, tubular, plasma and microwave that have been used in the pyrolysis of municipal waste. Each type of reactor has its own configuration and affects the pyrolysis process of municipal waste in distinct ways. There is a necessity for revisiting the progress of the investigation of the characteristics of the pyrolysis of municipal waste in different types of reactors, especially in terms of the kinetics of pyrolysis and the distribution of products. In addition, the techno-economic aspects of the pyrolysis of municipal waste in varied types of reactors are discussed, aiming to assess the potential for large-scale or commercial applications.

9 citations


Fathi Habashi1Institutions (1)
01 Jan 2010
Abstract: The rotary kiln was invented in the middle of the nineteenth century as a continuous reactor to solve the problem of the tedious and high man power batch processes in the chemical industry. It was then applied at the beginning of the twentieth century in the metallurgical industry and became later an essential reactor in both industries.

Network Information
Related Papers (5)
Performance
Metrics
No. of citations received by the Paper in previous years
YearCitations
20201
20132
20111
20101