1. business and industrial
2. energy
3. oil

H. V. WELCH.
PROCESS AND APPARATUS FOR RECOVERING SOLUBLE CONSTITUENTS FROM FURNACE FUMES.
H. V. WELCH.
PROCESS AND APPARATUS FOR- RECOVERING SOLUBLE CONSTITUENTS FROM FUHNACE FUMES.
APPLICATION FILED AuG.1|,19H. RENEwEo MAY 2. 192|.
1,382,057,
`
PmnœaJunezL 1921.
2 SHEETS-SHEET 2.
¿Tg5
66
UNITED STATES yPA'TENT OFFICE.
HARRY V. WELCH, OF LOS ANGELES, CALIFORNIA., ASSIGNOR TO INTERNATIONAL
PRECIPITATION COMPANY, OF LOS ANGELES, CAIIFORNIA, A CORPORATION OF
CALIFORNIA.
PROCESS AND APPARATUS FOR RECOVERING SOLUBLE CONSTITUENTS FROM FUR
NACE-FUMES.
Specification of Letters Patent.
1,382,037.
Patented J une 21, 1921.
Application ?led August 11, 1917, Serial No. 185,779. Renewed May 2, 1921. Serial No. 466,218.
To all whom. 'it may concern .'
desidera'tum, and since this Was to be ac
Be it known that I, .llamar V. WELcH, a complished with as little interference as
citizen of the United States, residing at Los )ossible with operating conditions, it has
Angeles, in the county of LosiAngeles and ee-n usually the practice to remove these in
State of California, have invented a new and the dry state. Thus, the operation of each
useful Process and Apparatus for lx’ecover section of the treater plant was intermittent
ing Soluble Constituents from Furnace in character, due to the necessity of remov
10
Fiimes, of which the following is a specifi
cation.
This invention relates particularly to the
recoveryT of potassium compound from waste
furnace gases, but is also applicable, in a
lng at regular intervals of time, the dust
collected upon the treater pipes or plates.
age of potassiferous constituent. In prac
20
25
65
gases passing through treater. To secure
maximum efìiciency, commercially, it has be
come common practice to decrease the ve
locity through the treater, to minimum con
slstent with economical construction, and
70
tice, it has been found that this potassiferous to provide by rapping and hammering de
constituent, under proper furnace conditions, vices, upon all parts of the treater subject
is very largely volatilized. and as a fume,
ed to high potential, frequent andvigorous
can be obtained as a very concentrated prod
action, to completely loosen and remove the 75
uct in the solids emitted from furnace gas
accumulated solids.
f
exits. As examples of su'ch conditions, I
It has been proposed to supply water to
may mention the gaseous discharges from ce the inside surfaces of the treater llues, in
ment kilns, where the solids caught in gas order to continually carry away deposited
. )assino'
the outlet
h throiwh
t)
30
60
It has been found that the gradual accu
mulation of dust and fume upon the col
lecting Walls, tends to promote unfavorable
general way, to recovery of other water so electrical conditions, and these result in in
luble materials contained in fume or dust complete removal of the solids from the
in hot gases.
In the industrial arts, there are numerous
instances where the feed furnaces and com
bustion chambers contains a certain percent
55
l
)iie î mav
con
-
material and maintain smooth electrode sur 80
tain from 5 to 40% potassium compound, faces. This overcomes some of the diílicul
while the original feed to kiln contains usu ties above noted, and also provides for con
ally under 1% potassium compound. Other tinual solution of solubles in the fume, con
industrial plants. showing large potassifer currently with the collection of the fume.
ous fume or dust discharges in waste fur The present invention provides for carry
35
nace gases, which may here be mentioned, ing out such a mode of operation in the most
are blast furnaces, sugar mills burning economical and effective manner.
pressed sugar cane stock under boilers,
An important object of the invention is
plants incinerating kelp. tobacco stems, etc. to provide for utilizing the water or liquid
My invention is applicable for the recovery used for carrying olf theI deposit, in a cyclic
40
taining potassium compound has been col
lected by electrical precipitation in treaters
the use of water.
.
Another object of the invention is to uti
wherein the gas is subjected to the action of lize the waste heat of the furnace gases in
an electrical field` and the types of treaters heating the water, to the most suitable tem
45
95
which have been used, comprise collecting perature for solution of the desired solubles,
electrodes formed as pipes or plates, dis
charge electrodes formed Yas wires-for ex
50
90
of potassium compound in any of such cases. manner, so as to obtain more effective re
In cement plants, the fume or dust con covery of the solubles and. to economize in
and for evaporation of the solution to oon
centrate the same, for recovery of the solu
ample, and means for maintaining said elec bles therefrom.
In this connection, my invention also pro
trodes' at high potential difference, so as to
cause precipitation of the material mainly vides for limiting the amount of heat With
on the collecting electrodes. Since the re drawn from the gases by the liquid, so as, on
moval of the solids was formerly the main the one hand, to prevent undue evaporation
100
1,382,037
of the liquid such as would result in in portion of each lower header chamber 8
sufficient flushing of the collecting electrode forms a sump or reservoir for receiving the
surfaces, and -on the other hand. to prevent collected material.
undue cooling of the gases, particularly in
The upper header 7 may be closed at the
cases where natural draft is used.
top thereof by reinforced concrete top mem 70
A further object of thc invention is to ber 12, which may be provided with circular
utilize reagents present in the furnace gases, openings to receive the insulating supports
for controlling the solution of the contents for the discharge electrodes, which are
of the fume. AFor example, in the case of mounted in such manner
10
to extend verti
cement kiln gases, my invention provides cally and axially in the respective flues 6. 75
for utilizing carbon dioxid present therein, Each of said insulating supports may com-'
to reduce the solubility of the calcareous prise a slab or disk 13 and a bushing 14,
constituent of the fume or dust.
15
20
mounted centrally vin said disk, said disk and
The accompanying drawings illustrate an bushing being, for example, of serpentine or
apparatus suitable for carrying out my in other suitable insulating material, and said
vention, and referring thereto,
bushing having a central bore for passage of
Figure l is a partly sectional elevation of the conductor 16 leading to the discharge
such apparatus.
electrode.
'
Fig. 2 is a section on line 2-2 in Fig. 1.
Each discharge electrode is preferably of
Fig. 3 is a section on line 3--3 in Fig. 2.
the form shown, comprising an upper plate
80
85
Fig. 4 is a flow sheet of a modification of or s ider 18, fromwhich hang any desired
the apparatus.
'
num er of electrode members formed, for ex
Fig. 5 is a vertical section of a modified ample, as wires 19, connected at their lower
form of electrical precipitator, embodying ends by a member 20, said electrode wires
25 my invention.
~
being preferably mounted so as to converge
Fig. 6 is a section on line 6-6 in Fig. 5.
toward their lower ends, and so that each
Fig. 7 is a perspective of another form of electrode wire will extend parallel to the ad
discharge electrode.
90
jacent surface bushing of the electrode Íiue
Fig. 8 is a plan view of distributing means 6. By sufficiently weighting the lower end
30 for the liquid and
`
Fig. 9 is a vertical section thereof.
The apparatus shown in the drawings com
prises an electrical precipitator or treater
indicated at 1, adapted to receive the gases
35 to be treated from a furnace flue 2, and pro
vided with means for supplying Water‘or
40
45
50
of the plurality of spaced apart electrode
95
wires a stable or non-vibrating structure is
obtained, the convergence of the electrode
wires preventing swaying or pendulum
movement thereof so that .any support or re
taining means for the lower ends of the elec 100
trodes, is not necessary, the electrodes being
other liquid for dissolving the solubles from supported wholly from -their upper ends.
the precipitated material, 'a filtering means The upper member 18 on which these elec
indicated at 3 for removing the solid matter trode wires are hung is connected to a rigid
from the resulting solution, means such as rod 16 extending through the insulating
evaporating or crystallizing tanks 4 and 4L’ bushing 14: aforesaid, and connected at its
for'separating the potassium salt or other upper end to high tensionvcurrent supply
desired product from the solution, and suit wire 25, which is mounted on insulators 26,
able pipe and pump means'for conducting and is connected by a wire 27 to any suitable
the liquid in a closed cycle through the de source of high tension current, preferably
scribed apparatus.
unidirectional-for example, in the manner
The electrical precipitator shown in the set forth in the patent to F. G. Cottrell, No.
drawing is of a type particularly adapted for 895,729-dated August 11, 1908. The con
105
110
use with cement kiln fume or other fumes crete structure of the treater may be provided
which have no injurious corrosive eHect on with one or more vertical partition walls 115
cement or concrete. Said precipitator com« 29 so as to separate the upper and lower
prises a structure built up of concrete, prefer headers in such manner as to form, in effect,
ably reinforced and monolithic, and having a plurality of treaters adapted to receive the
thevarious passages or fines for gases formed gases in series. The gases may be caused to
therein, said passages or iiues including ver pass either upwardly or downwardly 120
tical fiues 6, opening at their upper ends into through the flues 6. In case down~iiow of the
' header chambers 7, and at their lower ends gases is preferred, as would generally be the
' into lower header chambers 8, sald header case, the flue 2, leading from the furnace, is
chambers 7 and 8 being formed in the con connected to the inlet opening 9 for one ofthe
60 crete structure, and being provided with lat headers 7, and the outlet opening 10 for the '125
eral openings 9 and 10, constituting respec corresponding lower header 8 is connected by
tively, inlets and outlets for the gases. The a flue 30 to the inlet opening 9 for the upper
vertical lines 6 are preferably tapered from header 7, for the next succeeding set of flues.
their upper toward their lower ends„for the In this case, only two sets of fines are shown,
65 purposes hereinafter set forth. The bottom the outlet ll() of the lower header 8 of the
130
55
1,382,037 _
second set of flues being connected directly
by outlet fiue 31 to stack 32. If desired, how
ever, one or more additional sets of flues may
. The hot gases coming, for example, from
a cement kiln or kilns, and carrying dust
and fume containing potassium compound
be provided, connected in similar manner to as a constituent, are conducted through flue
that above described, and if necessary, suit 2 to the upper header 7 of the first set of 70
able blowing or forced draft means may be treater fiues and passed downwardly through
provided for forcing the gases through the said treater flues into- the lower header 8
fines, in case natural draft is not sufficient for and then up through the connecting fiue 30
that purpose.
Suitable means are provided for supplying
water to the several treater flues 6. For this
purpose, supply pipes 34 and 35, for the re
spective first and second sets of fiues, are con
nected to outlet pipes or nozzles 36, discharg
15 ing water into the upper portions of the re
10
and down through the treater fines of the
second set, in which they are discharged 75
through fiue 31 to the outlet 32. In passing
down through the flues 6, the gases are sub
jected tothe action of an electrical field
produced between the discharge electrodes
19 and the inside surfaces of the fiues 6, said
80
spective flues, preferably in a tangential surfaces being kept wet or flushed by cur
direction, said flues being preferably pro rents or streams of water flowing thereover
vided with shelves or troughs 38 at their up
from the nozzles 36 and the body or sheet
per portions against which the water is di
of water flowing in this manner on the in
side surfaces of the flues 6, being connected
formly and effectively distributed onto the to ground through the body of the treater
surfaces of the flues. The water running structure and the pipes which supply the
20 rected so as to cause the water to be more uni
85
down the surfaces of the flues 6 collects in water, and the discharge electrodes 19 being connected to the high tension electric sup
the respective sumps at the lower portions of
25 the headers 8, and is withdrawn or pumped
off in the manner hereinafter described, to
gether with the collected material.
From the lower header 8, for the first set
of treater fines, an outlet pipe 40 leads to
30
ply conductor 27, whereby high tension cur
rent, either direct or alternating, is supplied
thereto, for maintaining a sufficiently high
potential difference between said discharge
electrodes, and the flues 6 constitutinoP the
pump 41, which forces the liquid through collecting electrodes.
a pipe 42, either directly to the filter 3 or,
if desired, to a heater 44, provided with a
steam coil 45, or other means, for 'heating
the liquid so as to increase the solubility of
The effect ofD the
40
45
suspended material, and to continuously de a continuously flowing stream of water on
liver the filtrate through an outlet pipe 47. the inside of each treater fiue, accumulation
Said outlet pipe discharges into a suitable of any solid material on the walls of such
evaporating or crystallizing means, such as fiue is prevented, and a substantially smooth
tanks 4 and 4', which are adapted for treat surface free from projections tending- to
ment of the liquid by evaporation, or by develop discharge from the collecting elec
50
55
rate the desired salts'therefrom. Suitable
means, such as pump 50, is provided for
drawing off the residual liquor from a sump
58 receiving such liquor from the last tank
100
rectional current produced, for example, in
tinuously operating rotary filter, adapted to the manner set forth in the patent of F. Gr.
continuously receive the liquid containing Cottrell above referred to. By maintaining
cooling, or both, in such manner as to sepa
95
electrical field produced as above described
is to cause precipitation of suspended mat
ter, including dust or -fumes in the gases,
on the body or sheet of liquid flowing down
35 certain constituents thereof, if desired, said the walls orf-the fiues, this precipitating ac
heater 44 being connected in such case, by tion being especially effective when the elec
- a pipe 46, to the filter 3. Said filter may be trodes are charged by a substantially unidi
of any suitable type--for example, a con
90
105
110
trodes, is maintained irrespective of ¿the na-V
ture of the material being precipitated.
This is of especial advantage in precipitat
ing dust or fume, such as cement kiln fume, 115
containing a comparatively high proportion
4', and for forcing it through pipe 35 to the of potassium compound, which would other
water supply nozzle 36 of the flues of the wise tend to form a poorly conducting de
second set. Outlet pipe 54, leads from the posit, interfering seriously with precipita
lower portion of the lower header 8 for this tion. By thus maintaining the collecting
120
second set of treater fiues to a cooler 60, electrodes in condition of maximum effec
from which a' pump 55 forces the liquid tiveness, I am enabled to largely increase
through pipe 34 to the water supply7 nozzle the velocity of the precipitating action and
60
for the first set of treater flues. A by-pass correspondingly increase the rate of flow
59 having a valve 59’ may be provided for of gas through the aparatus, with the result 125
the cooler 60. Filter 3 may be provided that the dust precipitating capacity of a
plant of given size is largely increased. I
prefer to take advantage of this efficiency of
My process may be carried out in the precipitation in making thel treater fines
larger than is usually the case, said fiues, for
above described apparatus, as follows:
with supply pipe 56 for wash water, the wash
ings passing through pipe 57 to sump 58.
65
180
`
1,382,037
,
example, being two or three feet in diameter, ble form, any of the potassium compound 65
as against one foot or less in usual practice. which has not been dissolved in passing
With such a construction, and with the form through the treater fines. The solution then
of discharge electrodes above described, the flows through pipe 46 to. filter 3, wherein
the suspended material is removed, the clear
trode and the surface of the collecting elec-l filtrate running through pipe 47 to the crys
trode may, according to my invention, be tallizing tanks 4, wherein the solution is
increased to say twelve inches, the operating treated by cooling, evaporation or otherwise,
g-ap or distance between the discharge elec
70
voltage being correspondingly raised so as in order to separate out the desired potas
to maintain the strength of field as near as sium salt.
practicable to the break-down potential dif
ference-that is to say, the ‘highest potential
difference which it is possible to maintain
in the apparatus without arcing or sparking
15 between the electrodes to any undesirable
extent. The use of such comparatively large
treater fines is of advantage, not only in
reducing the cost of installation for a given
cross-sectional area and gas flow capacity,
20
25
but also in maintaining within desirable
limits, the amount of surface of liquid eX
posed to the hot gases passing through the
treater, and thereby avoiding undue con
sumption of water and undue lowering of
temperature of the gases. The amount of
surface exposed by the treater fiues of the
gases should, however, be suíiicient to attain
the main object of this process in heating
The residual liquid is then
pumped by pump 50 through pipe 35 to
nozzles 36 in the upper part of the second
set of treater flues, thus completing a cycle
of operation. Or if desired, all of the fil
tered solution may be evaporated to dryness
for recovery of the solids therefrom, and
only the wash water returned to the leaching
stage of the process.
As shown in Fig. 4, I may provide for de
canting ofl' a part of the liquid coming from
the precipitator, before filtering, the pre
cipitator, indicated at 61, being provided,
75
80
85
for example,with a receiving tank 62 at the
bottom of the lower header thereof, said
tank having an overflow chamber 63 at its
upper part, for clear liquor, and having a
draw-oil’ pipe 64 at its bottom for sediment,
said pipe 64 leading to the pump 41 which
90
the water by the heat of the gases, and is connected to the heater 44 as above de
30
35
thereby reducing the temperature of the scribed. In this case, it is possible to bring
gas to a point at which all of the potassium the solution to saturation under the condi
content or other desired volatile soluble will tions of operation so that more or less potas
be condensed in the form of Jfume and pre~v sium salt or other salt desired may be sepa
cipitated, such heating of the water flowing rated in the tank 62, by reason of the cool~
through the treater flues being also suíii
ing of the liquid therein. The main leach~
cient to maintain‘the water in a portion at ing cycle is throu h the precipitator 61,
least of the treater Íiues at a comparatively then from the over ow chamber 63 through
100
high temperature-say, approximately 1000 pipe 66 to sump 58, and thence through
C., such high temperature being best adapt pump 50and pipe 45 back to the upper part
4,0 ed for solution of potassium compound pres
of the precipitator. The sediment settling
ent in the precipitated material. The mate
in the bottom part of tank 62 is drawn ofi` to
rial collected in the treater fines of the sec~ gether with more or less liquid, and includ
ond set and washed down in the lower header ing any salt that may have settled out,
45
105
8 thereof, is pumped along with the water through pipe 64 to pump 41, and in passing
through pipe 54, pump 55 and pipe 34, to through the heater 44 the salt that may have
the upper part of the treater flues of the settled out is redissolved by the action of
ñrst set, and the water and material con heat, aided, if necessary, by agitation. Suit
tained therein, in passing down the~ said able mechanical means may be provided for
treater flues of the first set, receives a fur
50
forcibly withdrawing the pulp from the
ther amount of precipitated material, which bottom of tank 62, in case it is too thick to
is precipitated directly' on the surface of the How readily. In place of the decantation
water and carried down therewith into the
lower header 8 for said first set, and this op
eration may be repeated in as many treater
55 flue sets as may be necessary to bring the
used. The precipitator indicated in Fig. 4
may be made 1n one or more sections,
through which the gas and the washing liq
concentration of potassium compound in uid are passed in series in counter current
60
115
tank shown, any suitable thickener ma. be
the solution to the point desired. The ma îtrealps, as described in connection with
terial consisting` of a solution of potassium 4`1g. .
V
compound and other salts, together with ' The thickened pulp drawn from the lower
suspended material, is pumped from the last part of the decantation chamber, or ob~
lower header through pipe 40, pump 41 and tained from the material collecting at the
pipe 42 to the heater 44, wherein it may be bottom of the precipitator, by use of a suit
subjected to heat at a suiiicient temperature able thickener, may be passed to a suitable
and for a sufficient time to convert into solu digester or reaction chamber for treatment,
120
1,882,037
for the purpose of increasing the solubility the body of the treater being, for example,
65
of potassium compound therein, the pulp be
of concrete molded to form vertical up
ing subjected in such chamber, to the action wardly tapering walls 70 so as to form flues
of steam or hot water, preferably ata tem 7l which are downwardly tapering, and the
perature above 100o C., or being subjected discharge electrodes being hung in these
to the action of an acid or other agent for filles and consisting of wires strung in down 70
increasing the solubility of said compound. wardly tape1~inggroups as above explained,
Also, the residue, after filtering out potas or of vertical plates 72 placed transversely A
sium compound solution, maybe treated in in the flues, and having downwardly con
verging edges which are parallel to the walls
from such treatment may be dried and sold of flues 7l, said plates being mounted on
for its potassium compound content, or it insulated supports 73 in any suitable man~
may be filtered to recover the dissolved po ner, and provided with spacing means 74,
tassium salt, and the residue may, if desired, or as shown in Fig. 7, the discharge elec
be returned to the feed of the cement kiln, trodes may consist of two- rows of wires 75
10 similar manner. In either case, the material
15
for example.
In some cases, in the production of Port
extending in two downwardly convergent
planes, said wires being hung from insulated
75
80
land cement with a view to recovery of po supports 76 at their upper ends and con
tassium salt as a by-product, it is found de nected to suitable tensioning and spacing
20 sirable to use sodium chlorid in the raw mix, means 77 at their lower ends.
for assisting volatilization of potassium
The construction of the treater or pre 85
compound in the heat treatment in the kiln, cipitator of concrete is of advantage on ac
and also, in some cases, for increasing the count of cheapness of construction. and on
25
solubility of the potassium compound in the account of durability, especially in cases
material precipitated from the kiln gases. where the'gases being treated are liable to
In such cases, the potassium will be present corrode metallic structures. The liquid sup
largely in the form of chlorid and theproc plied to the treater distributes more uni
90
ess may be so carried out that the liquid, at formly over the concrete surface than over
30
moderate temperature-»say 75° C., is cir a smooth surface, and thus is less liable to
culated through the precipitator until it is run in ridges. The inclination of the walls
saturated with potassium chlorid, and it may of the flues also aids in the distribution of
then be filtered and the filtrate cooled to
`the liquid.
95
.
cause separation of potassium chlorid. Or,
35
Instead of the apparatus shown -in the
the liquid may be filtered before it is satu drawing, any other suitable apparatus may
rated with potassium chlorid and the filtrate be used for carrying out my process herein
then evaporated to saturation of such salt, described. For example, the electrical pre 100
and cooled to separate potassium chlorid. cipitator shown in application of H. A..
In either case, the residual solid material re
Burns, Ser. No. 832,892, filed April 18, 1914,
fume into the body of circulating liquid, and
the various filtering and pumping and other
sulting from filtration, may be returned to may be used for the precipitation of the
40
the raw mix, so as to restore to the cycle,
any sodium chlorid, and any potassium com
105
pound present therein; and the residual liq devices used in carrying out the process may
uor from which potassium chlorid has been
crystallized out, may be returned to the raw
45 mix feed or to the fuel feed for the kiln, so
as. to restore a further residual portion of
be of any suitable type. and may be made of
any suitable material-_for example, in case
the substances being treated are of a corro
sive nature,.the said apparatus, including
sodium chlorid and of potassium compound, the electrical precipitator, may be made of,
to the cycle. By these operations, the quan' or lined With a comparatively non-corredi
tity of sodium needed for carrying out the ble material such as metal, tile, etc.
The liquid may be circulated through the
mum recovery of potassium compound is precipitator as a whole, without removal of
any of the suspended or dissolved constit
eventually obtained.
The process above described is applicable, uents thereof, or it may be treated for sep
110
50 process is reduced to a minimum, and maxi
115
in some of its features to the recovery of aration of any part of such solid constitu
55
other water solubles from furnace gases
i for example, it may be applied to the recov
ery of zinc salts or zinc from zinc furnaces,
the Zinc being removed from the resulting
solution by electrolysis. for example, and
60
ents before returning to the precipitator.
In any case, each `circulation of the liquid
through the precipitator causes’ it to take up
an additional portion of the desired soluble.
Removal of such soluble from the liquid
may be effected by treatment of the whole
120
the barren solution returned to the leaching
stage of the cycle, as set forth in an applica body of liquid at each circulation, or by 125
treatment of only a portion of such body,
tion filed by me of even date herewith.
The electrical precipitator may be made such portion being drawn off continuously
of the plate type, as shown in Figs. 5 and 6, or intermittently and the remainder of the
resaca?
liquid body being returned to the circula the distributers 79 for the different units or
tion, together with sufficient fresh liquid to sections of units, and the distributers 79 sup,
make up for the loss by such withdrawal. ply the liquid uniformly throughout each
rl`he portion so Withdrawn may consist of unit or section. Similar distributing means
part or all of the'pulp remaining as a resi maybe provided for }_>recipitators such as
due on filtration or decantation, or part or shown in Figs. 1 to 3.
all of the filtrate or clear liquor. 'l‘he treat
ln carrying out the process in any of the
ment for recovery of the soluble from the apparatus above described, it may, in some
portion so Withdrawn may be by evapora~ cases, be necessary to cool the liquid during
tion or cooling or both evaporation and cool its circulation, to prevent undue loss of
ing, so as to separate the desired salt by liquid by evaporation, owing to absorption
crystallization, or it may be by evaporation of heat from the gases in the precipitator.
of the solution to dryness, so as to recover
15
20
all the entire solid contents thereof. Thus,
if desired, a part of the circulating body of
liquid may be drawn off, continuously or
intermittently, and may be evaporated to
dryness for recovery of all the fume con
Such cooling may be effected, for example in
in the sump 58 in the form shown in Fig. 4.
tank for removal of solid suspended ma
terial, which may be removed from said
85
pound in the sludge, as above set forth, so as 90
to increase the amount of potassium com
pound that can be taken up from the gases
with a given amount of Water, and the re
sulting sludge, with its accumulated load
of potassium compound, both dissolved and
recovery of the dissolved material by evapo undissolved, can then be passed to the heater
ration or cooling, and crystallization or by 44, shown in Fig. l, to heat the same sufli
.evaporation to dryness. Or, in some cases, ciently to bring all the potassium compound
the fume contents may be of suiiicient value,
80
Said cooler 60 may also serve as a settling
tents precipitated into the portion of liquid cooler in any suitable manner, the compara
tively clear liquor being pumped to the suc
circulating through 'the precipitator and ceeding- leaching stage. The cooler 60,
fresh liquid being supplied to said body to shown in Fig. 1, may also be used to effect
make up for that lost in such evaporation. the cooling action required forproducing an
The circulating body of liquid may be sub accumulation of precipitated potassium com
85 as a Whole, to enable them to be recovered
75
a cooler such as indicated at 6() in Fig. l, or
so drawn off, the main body of liquid re
jected to filtration or decantation either be
fore or after such Withdrawal of the portion
to be treated for removal of its solid con
tents, and in either case, the portion so With
drawn may be subjected to filtration, if nec
30 essary, to remove suspended material before
25
70
into dissolved condition.
95
"
The additional liquor required to make
100
Without any filtration, the portion of the up for losses in. leaching and in filtration
I liquid Withdrawn from the circulation being ~may be supplied at any stage of the process;
evaporated to dryness, more or less com but is preferably supplied as Wash Water for
pletely, so that the final product contains the the filtering operation.
40 insoluble as Well as the soluble part of the
1n addition to causing precipitation of the 105
fume.
~
fume into the liquid, the electrical field de
In order to insure uniform distribution of veloped in the precipitator has several other
the liquid over the surfaces of the electrodes, advantageous functions; one of which is the
I prefer to provide distributing means 79, production of electrical convection or Wind
45 comprising, for example, a tank 80 mounted age, which brings the fume particles into 11o
to rotate on a spindle 8l and driven by more effective contact With the liquid, and
pulley 82 or other means, so as to cause a
nozzle or outlet means 83 connected to said
50
55
,60
another is the lowering of the surface ten~
sion of the liquid, enabling the particles to
tank to travel over, and dischargeoliquid more readily enter the liquid and to be sub
into, anannular series of receptaclesSël’, jected to chemical or other action thereof.
communicating- with ducts 84 leading re~ In this connection, it may be stated _that the
spectively to pockets 85 at the upper ends of fume particles are in some cases of almost
the electrode Walls 70, each pocket 85 having molecular ?ineness, and are not in general
a lip 86 over which the liquid supplied able to penetrate the surface of a liquid of
thereto may overfiow on to the surface of strong surface tension such as water, and on
the electrode.- In general, a large number the other hand, the fineness of these particles
of precipitator units will be provided, and a makes them especially suitable for action
distributor 87 will be arranged to supply the thereon when they have been'forced into the
liquid in uniform charges successively to the liquid; so that the process is of especial ad
respective precipitator units; said distrib vantage as applied to such fumes.
uter 87 being similar in construction to the
lnasmuch as the gas is cooled more or less
distributer 79 above described, and „le dis in its passage through the electrical precipi
tributing ducts 90 thereof leading to the re tator, and in general, the conductivity of the
spective distributers 79, so that the liquid is gas varies inversely with the temperature;
uniformly distributed by distributer 87 to While the dielectric strength of the gas in
115
120
125
1,382,037
creases as the gas becomes cooler, it may, in -solubles'„troni` dustor fume iirhotl `furnace
some cases, he desirable to vary they spacing qgases, comprising a plurality of electrical
of the discharge electrode’from the receiving -‘precipitators y provided Y withv discharge and..>
electrode. Thus, in vcasethe` gas flows down collecting electrodes,¿said -precipitators ,be
10
wardly through the precipitator, as in the
apparatus shown in the drawing, the oppos
ing electrodes may be more Widely spaced at
their upper ends, whereas, if the apparatus
is arranged for upward flow of the gas, the
electrodes may be spaced more widely at
their lower ends, the discharge electrode be
ing ci'iiiiiected inseries so asfto maintain 1.a
gas streaml therethrough, means for supply
ing liquid to the collecting electrodes in each
of said precipitators, means for cooling such
liquid after it has passed over the collecting
electrodes of any precipitator, means Jf'or
conducting the vliquid from said cooling
ing, in that case, arranged to converge more means to the liquid supplying means for the
rapidly toward their lower ends than the re next preceding precipitator in the gas
stream so as to maintain an absorbing liquid
ceiving electrodes.
cycle in an opposite direction to said gas 80
What
I
claim
is:
15
1. Apparatus for recovering water solu stream, means for removing suspended ma
bles from dust or fume in hot furnace gases terial from said liquid after it has passed
20
25
comprising an electrical precipitator pro through the last precipitator of the liquid
vided wìth discharge and collecting elec cycle,fmeans for removing soluble material
trodes, means for supplying liquid to said from the resulting liquid, and means for
5. The _process of obtaining potassium
means for removing soluble material from
the resulting liquid, and means for return compound from the suspended matter of ce
ing the residual liquid to the liquid supply ment kiln l'lue gases, which consists in treat
ing said material with water in such man
ing means for said collecting electrodes.
2. An 4apparatus for recovering water ner as to produce a saturated solution, then
solubles from dustor fume in hot furnace heating the resulting sludge to cause solu
30
40
95
ing electrodes, means for removing suspend ment kiln flue gases, which consists in
100
sulting liquid, and means for returningthe sludge and solution contained therein to
residual liquid to said liquid supplying cause separation'of a compound containing
105
ed material from said liquid after it has bringing such gases while still hot into con
,passed through said heating means, means tact with water to produce a sludge con
for removing soluble material from the re taining a hot saturated solution, cooling the
means for said collecting electrodes.
3. An apparatus for recovering Water solu
potassium, returning the remaining solution
to act on the said material, and subjecting
bles from dust or fume in hot furnace gases, the sludge containing insoluble material to
comprising a vplurality of electrical precipi the action of heat to dissolve potassium com
45
90
gases, comprising an electrical precipitator tion of insoluble potassium compound there
provided with discharge and collecting elec in, and separating the resulting solution
trodes, means for supplying liquid to said from the remaining insolubles.
6. The process of obtaining potassium
collecting electrodes, means for heating said
compound
from suspended material lof ce
liquid after it has passed over said collect
35
85
collecting electrodes, means for removing returning the residual liquid tothe liquid
suspended material from said liquid after supplying means for the first precipitator of
it has passed over said collecting electrodes, the liquid cycle.
tators provided with discharge and collect pound therefrom, and separating the result
ing electrodes, said precipitators being con ing solution from the insolubles.
7. The process of obtaining potassium
nected so as to provide for succesisve pas
110
sage of said hot gases therethrough, means compound from suspended material of ce
for supplying liquid to the collecting elec ment kiln flue gases, which consists in cir
50 trodes in each of said precipitators, means culating leaching liquid in contact with said 115
for conducting the liquid which has passed gases and suspended material, so as to pro
over the collecting electrodes of any precipi duce a solution of potassium compound and
tator to the liquid supplying means for the a sludge containing potassium compound,
next preceding precipitator in the gas said solution being used as such leaching
liquid-then subjecting said sludge to heat
cycle in an opposite direction to the gas to- dissolve potassium compound therefrom,
55
stream so as to maintain an absorbing liquid
120
60
stream, means for removing suspended ma and separating the resulting solution from
.
terial from said liquid after it has passed the insolubles therein.
8. The process of recovering potassium
through the last precipitator of the liquid
cycle, means for removing soluble material compound from fume in hot furnace gases
from the resulting liquid, and means for which consists in electrically precipitating
returning the residual liquid to the liquid the fume into a flowing liquid, consisting of
supplying means for the íirst precipitator a solution of potassium compound having
125
suspended material therein, passing the
4. An apparatus fer .removing water gases into a second precipitator and electri
of the liquid cycle.
65
130
cally precipitatin
residual fumes into a to recover the potassium compounds there
flowing liquid, co lectiiig the resulting liq- from.
_
.
uor and suspended material and using it as
ln testimony whereof I have hereunto set 10
the lìrst mentioned flowing liquid, collecting my hand, at Los Angeles, California, this
5 the liquor containing suspended material 3rd day of August, 1917.
from the first precipitation, and treating it
to separate insoluble material therefrom and
'
HARRY V. WEL-CH.