Note: Descriptions are shown in the official language in which they were submitted.
iO72179
This invention relates to the manufacture of
battery plates especially those of tubular type and i8
concerned in particular with the filling of the tubes
of such plates, novel apparatus for carrying out the
5. method and novel active material paste composition.
Tubular plates can have a variety of different
types of tube material and tube configurations and can
have tubes ~oined together or formed as separate tubes
which are separately located on the spines.
; 10. One example of such separate tube arrangements
utilizes woven fabric tubes having a thin outer plastic
sheath provided with perforations about 1-2 mm across
spaced apart by about 1 to 2 mms. me plastic sheath
is about 0.1 to 0.2 mms thick.
15. The invention, though not limited to such
arrangements, however is described with particular
reference to tube arrangements in which the tubes are
a single preformed assembly since this facilitates
assembly of the tubes onto the spines of the plate.
20. A conventional method for making tubular plates
involves impregnating fabric tubes with a resin to
render them stiff though still permeable, locating the
tubes on an array of lead alloy spines, one spine to
each tube, and filling the space between the interior
25. f the tubes and the spines with active material e.g.
lead oxide powder from a hopper and shaking the assembly
to compact the power in the tube. This method has
considerable problems including waste of lead oxide
powder, inconsistency of filling weight, and unevenness
30. of filling, the active material tending to become
2.
KDNK/NH ~ '
107Z179
over consolidated at what is the bottom of the tubes
during filllng but i8 the top of the tubes ln use.
One proposal, in G.B. Patent No. 947796, for
reducing these problems was to extrude an active material
5. paste containing a water soluble thickening agent into
the tubes under high pressure. However, this method
resulted in plates which had unpredictably variable
electrical performance. mere was also a tendency for
the paste to break down and lose its fluidity under
10. pressure and also to go solid inside the machinery if
there were any intervals or delay in the production
sequence.
Another proposal, in G.B. Patent No. 1386056, is
to inject a metered volume, corresponding to the internal
15. volume of the tubular plate, of an acidic automotive
battery paste into the tubes within a very short space
of time e.g. less than 1.5 seconds~ me paste has a
certain amount of additional water added to it. This is -
alleged to form a suspension, but in fact this mixture is
20. a thic~ paste which is not self levelling. The pastes
which are disclosed contain 3 parts grey lead oxide, 1
part red lead oxide, 2.96 parts by weight of oxides to
each part by weight of acid and water and 0.06 parts by
weight of 1.4 specific gravity sulphuric acid for each
2~. part by weight of oxide, i.e. 12.6"' of the grey lead
oxide was sulphated. The specification describes the
pastes as having dynamic viscosities in the range 3000
to 4000 centipoises. No indication is given of what
method of measurement of viscosity or measuring
30. apparatus is to be used.
3.
KDNK/NH
-` 107Z~79
We have measured the visco~ity of the above paste
described in British Patent No. 1386056 on a rotating
vane viscometer as described below using the measurement
technique described below.
We find that this paste has a rotating vane
viscometer torque value (as defined herein) of 0.~75 lbs
ft. The paste is not self levelling; that is when a mass
is deposited as a lump on a flat surface it does not
assume a flat level surface within a period of 24 hours,
10. though small amounts of liquids separate out from the
solids during this period.
mis process has the disadvantage of requiring -
accurate metering of the volume of paste to be injected
and the paste is so viscous that it has to~be forced
15. into the tubes under high pressure.
-This need to use high pressure results in variation
in den$ity of the paste along the length of the tubes.
the paste tendlng to become over consolidated at the inlets
to the tubes which are the bottoms of the tubes in use.
20. In addition it introduces difficulties in getting the
- paste to travel the full length of a tube, especially in
a deep plate. This severely limits the size of plate
! which can be filled. This introduces further problems in
production of batteries from the paste and in use of the
25. batteries.
We have discovered that these problems can severally ~
and collectively be reduced by using a radi~àlly different -
active material composition, apparatus and method in
which a pourable liquid slurry of low viscosity is fed
30. into the tubes under gravity of low pressure and then,
;
4.
107Z179
when the tubes are full, preferably consolidated by
allowing the back pressure to build up.
By controlling the valve to which the back
pressure is allowed to rise, the degree of consolidation
can be varied as desired and an even consolidation achieved.
A slurry of very low viscosity is fed into the tubes under
gravity or very low pressure conditions.
According to the present invention, a method of
filling envelopet plates, e.g. tubular plates, for batteries,
e.g. lead acid batteries, which comprises introducing an
active material composition into the porous envelope of an
enveloped plate e.g. the tubes, when the envelope is assem-
bled on the current conducting element of the plate, e.g.
the spines, is characterised in that the active material
composition is introduced into the envelope as an aqueous -
slurry, which has a rotating vane viscometer torque value
Cas defined herein see page 29 lines 6 to 11) in the range
0.006 to 0.06 lbs ft. at 20C; the material of the envelope
desirably being selected to filter out active material
whilst allowing passage of liquid and the introduction of
the slurry into the envelope is continued until the envelope ~
is filled with active material, the said aqueous slurry --
being introduced into the envelope at a pressure of less
than 15 psi and desirably less than 5 psi until the en-
velope is filled with the composition, liquids issuing thro-
ugh the walls of the envelope, the pressure then being allow-
ed to rise to a value about 15 psi or 5 psi but not in excess
of 100 psi and the pressure thereafter being released. The
-- 5 --
1072~79
composition preferably has a rotating vane viscometer torque value (as
defined herein) in the range 0.010 to 0.050 or 0.06 and preferably O.OlS to
0.04 lbs ft at 20C.
In accordance with the invention there is provided a method
of filling enveloped plates for batteries which comprises introducing an
active material composition into the porous envelope of an enveloped plate
when the envelope is assembled on the current conducting element of the
plate, characterised in that the active material composition is introduced
into the envelope as an aqueous slurry which has a rotating vane viscometer
torque value in the range 0.006 to 0.06 lbs ft at 20~C, the said aqueous
slurry being introduced into the envelope at a pressure of less than 15 p.s.i.
until the envelope is filled with the composition liquids issuing through
the walls of the envelope, the pressure then being allowed to rise to a
value above 15 p.s.i. but not in excess of 100 p.s.i. and the pressure
thereafter being released.
For ease of description the process will be described
essentially with reference to tubular plates.
The ratio of volume of slurry which is fed into the tubes,
to the total internal free volume of the tubes in the plate is preferably
not more than 3:1 e.g. less than 2:1.
The internal free volume of the tubes is that volume within
the internal diameter of the tubes which is not occupied by the current
conducting elements.
The aqueous slurry comprises a blend of water and particulate
active material. The slurry may be non acidified or may have had acid
added to at least partially sulphate the oxide.
The weight ratio which should be used depends on the particular
active material which is being used, the permeability of the tubes which
are being filled and whether the composition contains acid or not and, if
it does ~ontain acid, the ratio of acid to active material, i.e. the
degree of sulphation.
-6-
1072179
With the non-woven fabric described below we prefer to use
non acidified slurries having a solids to liquids ratio of 2.5:1 to 3.5 1
and with partially acidified slurries a solids to liquids ratio of 1.7:1
to 2.5:1, the acid having the effect of considerably increasing the
viscosity of the slurry. -
-6a-
-
. ,
` :` `: ` ,:
1072179
.
The slurry can contain conventional ~illers and
additives for the active material such as hydrophobic
or hydlophilic silica, so long as the composition continues
~` to have a viscosity as defined above. In one arrangement,
5. the tubes are allowed to fill substantially under gravity
by being pumped into the tubes under zero back pressure,
the pumping is continued and the back pressure allowed
- to build up to a value not in excess of 70 psi. Thus
the pressure may be in the range 5 to 50, e.g. 10 to 30
10. psi. The time over which the pressure build-up is allowed --
to occur is not critical. Usually the pressure is merely
allowed to build up to a set value at which point the
! press~re is released.
- ~urprisingly and in contrast to the prior proposals
15. where the whole filling operation is carried out under
high pressure, which results in the active material being
- stratified, the paste being more dense nearer the inlet
: - ~which will be the bottom of the tubes in use), this
arrangement enables the density of the active material
20. in the tube to be increased evenly throughout the tube.
As mentioned abové the ratio of active material to
liquids which should be used depends on a variety of
$actors including the nature of the material from which
the tubes are made.
A balance must be struck between the need for
the material to have a high water permeability to provide
good conductivity in use in the battery and the need for
the material to retain the active material so as to enable
filling to be carried out rapidly and
` 1072179
the active material to be retained in the tubes over long
periods of use and under conditions of shock and
vibration. One suitable material is made $rom a non-
woven batt of polyester fibres which is 0.5 to 0.7 mm
5. thick and weighs 120 to 160 grams per sq. cm, has an air
permeability (as hereinafter defined, see page 18 line
29 to page 19 line 1) of 8.0 litres/sq. cm/minute and a
water permeability (as hereinafter defined see page 18
line 29 to page 19 line 11) of 1.5 litres/sq. cm/minute.
10. This material is preferably not perforated, its
porosity being derived from the natural gaps between the
-fibres from which it is made.
More broadly, it is preferred to use a material
having a nitrogen permeability in the range 0.5 to 12,
15. e.g. 1 to 10 or preferably 3 to 9 litres/sq. cm/minute.
Desirably, it should also have a water permeability of
at least 0.01 litres/sq cm/minute e.g. 0.1 or 0.5 to
1, 2 or 5 litres per minute or more.
As indicated below, it is preferred to use a
20. slurry composition in which the active material particles
have an average particle size in the range 5 to 20 microns.
However, material with average particle sizes in the
range 1 to 30 or 50 to 100 microns can equally well be used.
Referring again to lead acid systems the lead
oxide preferably has substantially all of its particles
having particle sizes less than 100 microns, e.g. less
than 1% by weight are above 200 microns in diameter. In
addition, less than 1% is below 0.001 micron in diameter.
Typically, at least 50~ e.g. 95C/o by weight, is less than
30. 10 microns and 5% is less than 1 micron. The oxide may
8.
-- ~
' . ~
~07 Z179
,`: .. . .
- . ;
comprise grey lead oxide or red lead oxide Gr a blend
of grey lead oxide and red lead oxide and preferably
a blend of grey lead oxide of average particle size 20
microns and red lead oxide of average particle size
5. 5 to 10 microns. The ratio of grey to red lead may be
in the range 95:5 to 5:95 thou~h 90:10 to 50:50, e.g.
33:67 is preferred. . ~ - -
Preferably, the tubes are clamped at the top -
and bottom so that liquids can escape out from the ~rhole
10. area of the tubes. ~ ;
Desirably, a supply of the slurry composition
is continuously mixed during thè filling and a minor
- proportion of the slurry supply is introduced from this
- continuously mixed supply ~nto each tubular plate.
15. The supply of siurry composition is preferably
delivered by à pump l~hich gives smooth delivery and
maintains the slurry in suspension- a~d the slurry, in
the i~tervals bet~ Pn introduc~ion into a -tub~ar plate,
; - i8 recirculated from the outlet of the pu~.p back to its
20. inlet, e.g. via a recircula~ing ~be corr.ected ~o the
pump outlet, and an agitat~d stora~e t&~c,-Yrom -Yrh~ch a
~- supply tube extends to the pump inlet.
,
In a first form of the method, the s urry is introduced
~rom a pump into one tubular plate then when that pl~te
25. is filled is continuously recirculat~d from the outlet of
the pump to the pump i~let and is then introduced in~o
another tubular plate.
--~ The invention may be put into practice in various
ways and one specific embodiment and certain modifications
~3. will be described by way of example with refèrence to the
,
' 107:~179
the accompanying drawings, ln which:-
Figure l is a diagrammatic side elevation ofapparatus in accordance with the invention;
Figure 2 is an enlarged diagrammatic perspective
5.~ view of the filling box show~ in Figure l;
- Figure 3 is a diagrammatic view OI part of the
lower clamp shown in Figure 2 in the open position, - -
sho~ing only some of the tubes of the plate;
Figure 4 is a cross-sectional plan view on
1~. the line IV-IV of Figure 3;
Figure 5 is a part cross-sectional view of part
of the upper clamp in the open position, as in Figure 3,
- Figuxe 6 is a general front elevational view of
the rotating vane viscometer used to measure the viscosities
15.- of the slurries used in the invention;
Figure 7 is a detailed front elevational view of
the paddle assembly of the viscorneter of Figure 6;
~ Figure 8 is a plar view of the container for use
with the viscometer of Fi~lre 6 fcr contain~ng the sample
20~ whose viscosity is to be measured, and
- Figure 9 is a plan view produced from an opiical
photomicrograph of the non woven fa~ric, I~, described
below and used in the examples.
The-apparatus consists of a slurl~y tank lO in which
25. the slurry to be filled into the plate tubes is stored.
The tank is fitted with a paddle ll located at the bottom
of the ta~ and driven by a belt and pulley drive 12 from a
variable speed motor 13. A vertical feed tube 15 extends
up from jus~ above ~he paddle ll to the inlet to a supply
.
.
.
0 7 ~ 3
pump 16 whioh is also driven by a belt and pulley
drive 17 from a variable speed motor 18. m e out-
let of the pump 16 is connected ~erti.cally down~rards
- by a supply pipe 19 to a plate filling station 20.
5. The supply pipe proceeds via a pressure gauge 22
a two-way val~e 23 Rnd a fishtail mani~old 24. m e
. val~e 23 ei.ther permits the slurry to f10W verti-
- cally downwards to the station 20 or can be posi-
tioned to direct the slurry to the tank 10 via a
10. recirculat-ing tube 25 which extends down to just
above the paddle 11. The tubes 15 and 26 are
preferably of the same cross-sectional area.
e mass of the supply of slurry is preferably
maintained at about 150 kg, e.g. 100 to 200 kg, and
- 15. the mass of slurry introduced into each tubular
plate, the individual filling weight, is o~ the
order of 400 to 1,000 gm. ~ More broadly, the weight ~ -
- ratio`of the active material, e.g. 75 kg, in the
- - continuously mixed slurry supply to the indi~idual
20. filling weight is in the range 1300:1 to 25:1 pre~erably
1000:~ to 200:1 more particularly 160:1 to 100:1.
; - - me station 20 comprises a frame 29 rigidly
8ecured in relation to the manifold 24 and carry~
- ing top and bottom clamps 30 and 31. :
25. me clamps 30 and 31 are toothed and conform --
- . to the outside surface profile of the bottom and
top o~ the tubular plate since the plate lS in-
serted in the clamps with its open bottom end facing
the manifcld 24. The manifold has an outlet nozzle
30. assembly consisting of 1/4 inch lo~g copper or other
-
~ -
KDNK/JE~ - 1,1 -
- " ~ . 107Z179
rigid ~èed tubes with external diameters`correspond-
ing to the internal diameters-of the plate tubes
and spaced apart ~n a straight line, the centres of
the feed tu~es being on the centres of the plate
5. tubes. -
mus the open ends of the plate tubes fit
snugly over ~he feed tubes and are clamped thereto
by the top clamp 30 tthich may be provided with
- resilient sealing liner.
10. m e lower'clamp 31 holds the plate in position
and presses the tubes against a thickened end
section on the spines. me faces of the plate are
completely freè.
- m e spines ~re of conventior~l lead alloy com-
15. position and of conventional st~ucture being located
on a top bar at centres correspo~di.-~ to the cer.tres
of the tubes with which they will be used. m ey are
desirably provided with short axial fins ~Jhich are
~sed to centre the spines in the tubes and to prevent
20. the spines Deing distorted during har.cllir~ prior to
: filling.
The`station 20 will now be described in more ~ -
detall with reference to Figures 2 to ~.
As mentioned above, the station 20 c~mprises
25. a frame 29 rigidly secured in relation to the mani- -
fold 24. m is frame is in ~o parts 32 and 33 h mged
to each other along the left hand eage, ~nd it is
the part 33 which is rigidly a~tached t~ The mani- - -
fold 24. m e top and bottom clamps are e~ch in
~_~3D. two parts 30A and 30B ar.d 3a~-and 31~ A and 31A
. - -
.
2_
"~` ` 1072179
are carried by the movable part 32 of the frame
29 and 30B and 31B are carried by the fixed part 33
of the frame 29.
The fixed part 33 also carries top and bottom
; 5. locking levers 36 and 37 which are arranged to
engage top and bottom handles 38 and 39 on the movable
frame part 32, and lock the filling station closed.
The fixed part 33 of the frame 29 also carriesa bottom support bar 42 which has an aperture 43 through
10. which the lug 44 of a plate 45 can pass and which
assists in registering the plate in the filling station.
The top and bottom clamps 30 and 31 have toothed
profiles which conform to the external sheathed
dimensions of the plate and the two portions of each
15. clamp when closed define a row of cylindrical holes 48
connected by gaps 49 twice the thickness of the fabric
47 of the sheath so as to prevent the sheath being cut
by the clamps.
The bQttom clamp 31 presses the fabric 47 of
20. the sheath against the broadened shoulders 51 of the
spines 52 of the plate to ensure a tight seal. (See
Figures 3 and 4).
Figure 5 shows the clamping arrangement at the
manifold 24. A manifold plate 54 has a row of feed
25. tubes 55 passing down through it and having narrowed
ends 56 which extend through apertures in a rubber
gasket 58. It is resilient being compressible by
finger pressure to only about half its uncompressed
thickness, which is about 1/8 inch thick. me
30. arrangement shown in Figure 5 shows the sheath 50 in
KDNK/NH
` 10~2179
position over the ends 56 of the feed tubes. However,
the arrangement is in fact such that the gasket 58 has
to be compressed by about 1/16th inch by the sheath 50
being forced up into it in order to get the top bar of
5. the plate onto the bottom bar 42 of the frame. (This
- compression has not been shown on the drawing). The
clamp 30 presses the fabric 47 of the sheath around
the ends 56 of the feed tubes 55 to achieve a good top
seal.
10. The pump 16 is one which gives smooth delivery
and is of the well known type, such as that marketed
under the trade name MONOPUMP, which comprises a rotor
in the form of a single start helix fitting in a
cylinder in the form of a double start helix of twice
15. the pitch of the rotor, in which the rotor turns about
its own axis in one direction whilst its axis orbits
about the axis of the cylinder in the opposite
direction at the same speed. This form of pump gives
a positive displacement with uniform flow, and
20. prevents the separation of liquids and solids in the
composition.
In another arrangement (not shown) the filling
station 20 is formed as a twin manifold arrangement -
each manifold being fed from the pump 16. The two way
25. valve 23 is replaced by a three way valve and each line
from the valve 23 to a manifold contains a pressure
responsive valve 70.
This valve 70 is preferably a pressure release
valve which can be set to any desired pressure e.g.
30. 15 psi and when this pressure is reached wi~l hold
14.
KDNK/~H
1072179
the pressure at 15 psi until actuated, e.g. manually.
The procedure would then be for a plate to be
inserted in one manifold and the valve 23 switched
either from recirculation or from the other manifold.
5. The plate would fill e.g. in 5 seconds and then the
pressure would rise to 15 psi and be held there for
5 seconds. During this time the operator would have
removed the filled plate from the other manifold and
inserted a new plate. He could then switch the valve
1O. 23 either to recirculate momentarily or immediately
to fill the new plate.
In an alternative arrangement the pressure
release valves 70 is arranged to switch the pump
supply to recirculation and release the pressure on
15. the plate as æoon as the preset pressure is reached.
In operation, the filling process is as
follows.
The composition is made up to the desired
composition in the tank 10 by use of the paddle 11.
20. A tubular plate 50 is assembled, the fabric tubes 47
being located on the metal spines 52, and it is
positioned against the clamps 30B and 31B, at the
station 20 with its open bottom ends pushed up against
the gasket 58 and over ends 56 of the feed tubes 55 of
Z5. the manifold 24. The part 32 of the frame is then
swung closed against the part 33 and the clamps 30
and 31 thus closed and the locking arms 36 and 37
secured over the handles 38 and 39. The paddle 11 is
kept in operation and the valve 23 is turned to the
30. recirculating position connecting the pump 16 to the
KDMK/MH 15.
``` 107Z179
tube 28 and the pump 16 is switched on. Recirculation
is carried out until the flow is steady. The pressure
indicator 22 indicates zero pressure whilst
recirculation is occurring.
5. The valve 23 is then switched to connect the
pump 16 to the manifold 24. The slurry passes down
into the station 20, the active material filling the
interior of the tubes. The valve 23 is maintained in
this position until the tubes have filled with active
10. material at which point the pressure indicator
indicates a relatively sudden increase in presæure.
At this point liquid exudes in globules from over the
whole surface of the tubular plate essentially
simultaneously. As the pressure rises to the cut off
15, pressure further small amounts of liquids exude from
the plates. - -
The first liquids tend to be clear; later
liquids tend to also contain active material. When
the pressure reaches the desired shut off value
20. the valve 23 is then switched to recirculate the
composition to the tank 10 via the pipe 26.
The clamps 30 and 31 are then opened and the
filled plate removed and the further processing
operations such as bottom bar insertion, pickling,
25. drying and electrolytic formation carried out on the
plate.
16.
KDNK/NH
` 107Z~79
m e excess slurry in the manifold 24 falls down
. into the tank 10.
In continuous operation, the pressure rise indi-
cated by the indicator 22 could be used to control
`5. the filling cycle, e.g. to activate the valve 23,
and open the clamps 30 and 31 to disengage it from
- the manifold 24 and re-engage a new plate in the
clamped position. Limit switches could be provided,
which would be activated by the new plate en~aging 1~. the manifold 24 to divert the val~-e 23 back ~o the
filling pOSition.
Examples
Examples will now be given of specific plate
- production techniques.
15. The plates were positive plates having 15 tubes
eachl~.5 inches long. m e tubes were made of non
woven polyethylene terephthalate fibre. This is
made as follows:-
O A thin web (1.5 metres wide) of ~ibres having
20. an average length of 4~ inches is produced by card-
ing, and a fleece is produced by layering approxi-
mately ten webs to form a continuous len~th of r.on-
woven fa~ric (also 1.~ metres wide)!
The fibres extend generally longitudinally in
25. the web, which is pleated in a zig-zag fashion as
it is taken off from a conveyor travelling in $he
direction of the length of the web onto a conveyor
travelling at right angles thereto. Thus the fibres
extend substantially transversely to the length of
30. the fleece, but due to the travel of the secor.d
KDNK/JR - 17 -
-
` ` ~07Z179
.
conveyor the ~ibres in adjacent layers are opposit~ly
inclined at a small angle to the transverse di.rection.
This material is then impreOnated with 50% by
weight of polyacrylic binder. It has a thickness of
5- 0.5 to 0.7 mm and ~eighs 120 to 160 grams/sq cm.
This material is then converted into an array of tubes
by passing two layers of it through a multiple sewing
machine to secure`the layers together along parallel
lines (for example, spaced about 2 to the inch) to form
10: pockets or tubes in the conventional manner.
This material is then dipped in a phenolic resin
and dried. The material picks up 30% of phenolic resin
based on the dry weight of the non-wover. material. hfter
cutting to length circular section mandrels 0.287 inches
15. in diameter are then inserted between the rows of stitches
to form the pocke's. It nas an æir permeability of 8.0
litres/minute/sq cm and a water permeability of 1.5 1itres/
minute/sq cm area. Its structure is sno~rn in Figure 9
of the accompanying drawings.
20. Aæ can be see~ in ~iOure 9 this no~-woven fabric
is made up of randomly en-tang1ed individual fibres. The
fibres have a diameter of about 25 micrcrs or more broadly
20 to 50 microns. The gaps between individual fibres are
in general less than 250 microns and mostly less 'han 100
25- microns and moreover the materia1 in having a thickness
of 0.5 to 0.7 mms has a three dimensional structure
permitting the overlap of many indiviàual fibres in any
one path from face to-face of the sheet.
Air permeability was measured as follows:-
3- A sample 2.8 cm in diameter t6.16 sq cm effective
cross-sectional area) ~JaS clamped in position aIld the
time for 50 1 of dry nitrogen ~o flow through the sa~ple
at 20C under pressure difference of 0.6 inches (1.5 cms)
18
107Z179
. ~ water gauge was recorded.
The material is too permeable for mercury porosi- -
metry or air flow through an alcohol saturated sample
`to be accurate measurement techniques.
5; Water permeability was measured on the same sample
by measuring the time taken for a column of water ini,tially
42 cm high and l litre in volume to flow under gravity
through the sample.
' - m e dot~nstream end of the colvmn below the sample
10. was blocked off, the water introduced above the sample and
then the do~mstream end below the sample opened to atmosphere.
This material is referr~d to as the non woven fabric N.W.
- - in Table 1 below. '
Another fabric was also used. It was a spun woven
15. fabric referred to as SW in Table 1 below and having an
air permeability of 6.0 litres/sq cm/minute. It has 17
wef,t threads per cm and 22 wa~p threads per cm. The warp
threads being abovt 250 microns in diameter and the weft
- threads being about 375 microns in di2meter. Microscopic
20. examination indicates that the ga?s between adjacent,warp
threads and adjacent wef~ ~hreads are about 250 microns
~- by 250 microns maximum but these gaps are bridged by
' numerous loose fibres extending out from the threads.
'- The compo~itions used ai~e indicated in Tables 1A
25. and 1B below.
The slurry was made from mixtures of grey lead
oxide ~average particle size 20 microns) and red lead
oxide (average particle size 5 to lO microns) mixed in
various weight ratios with mains water.
.
1~7Z179' - -
The solid particles in the slurry were such that
less than 1% by weight were above 200 microns, and less
than 1% were below O.OOl microns, 957~ by weight were
less than 50 microns. These particle sizes were determined
5. by sieving.
- The tank lO contained 150 kg of slurr~, the paddle
ll, 30 inches by l~5 inches, was rota-ced at 30 to 70 rpm, -
to maintain solids in suspension. The pump 16 was run a-c
~ ~arious volume throughputs as indicated in Table 1A.
10. During recirculation the pressure indicator 22 showed zero
pressure. Using the same stirring and pvmpin~ conditions,
the valve 2~ was switched to the fil1 pos tion, and ~he time
for which the indicator 22 showed zero pressure recorded
and the total time up to 1~hen the valve 23 was again switched
- 15. to recirculation and the maxim~m pressure reached recorded.
These are given in Table 1A. The i.~ternal volume of the
tubes was 170 cc.
It is preferred to add acid to at least partially
sulphate the oxide; l gram of oxide reauires 0.4 mls of
20. 1.4 sp gr sulphuric acid to achieve 'his. The mixing
of the slurry continues in the storage tank durirg the
acid addition and once this is completed the filling -
cycle can be con-cinued. Cer-cain cf -che Exa~ples in Tables
- 1A and 1B are of partially acidified compositions. 1-
~25. Example 12 was carried out using tubes havi7lg a total i
internal
- free volume of 105 cc.
.
,
.
1~7~179
` .
21
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.
107Z179
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~` ` 107Z179
Notes on table 1A and 1B
1) Acid/solid ratios. It has been assumed that all the
- acid i8 absorbed by and reacted with the excess oxide at
the stage when it is first added and thus the acid/oxide
5. ratio remains constant until more acid is added i.e. a
proportion of the acid is removed with each sample of
paste which is removed.
2) Solid/liquids ratios.
A) These are calculated including the whole of any acid
10. added as liquid.
B) The weights of solids removed in the samples of the
filtrates have been ignored since the weights of these
` samples were relatively small and there was no way of
easily determining the ratio of solids to liquids in the
15. filtrates.
C) The ratios have been calculated ignoring the amount
of liquids removed in the paste in the tubes. mese ratios
therefore slightly underestimate the solids content of the
slurries. ,; 20. 3) Gre ~ ed ratios. These have been assumed to remain
constant except when extra grey or red oxide is added.
4) Wet paste in plate. The weight x of the fabric tube
the lead spines and a bottom bar was measured. The values
~uoted are the wet filled plate after bottom-baring minus x.
25. 5) % Settlement of the sample. This is the height A of
the solids in the container divided by the height B of the
liquids from the bottom of the container expressed as a
percentage after the sample had been thoroughly shaken for
~ minute and then allowed to settle in a vertical position
30. for 24 hours.
- 24 -
`. ^ ` 1072179 ---
`'''` ' ' , ' ':
,' me container is a round bottomed test tube of
1.5 cms int~rnal diameter and at least 9 cms of
~lurry are placed in the test tube.
6) ~ e of the sus~ension. This is the time
' 5. taken for the solids level of the sample in the
container described under 5) above to sink to half-
. way between B and A.
e test is c,arried out by placing a rubber
band with its bottom edge,at the half~ay level i.e.
- 1~0. (B ~ ~)/ 2 cms from the bottom of the test tube,
shaking the tube vigorously for at least ~ minute
, or until all the solids are displaced from the
- bottom of the test tube and th~n righting the test
tube and l~easuring the time ~rom tnat inst~nt to the
15. instaLnt ~hen light is first visible under the rubber
band.
7) ~ m is is merely a setting. me
volume of slurry pumped through th2 manifold as
~easured at v~rying sett'ings by collecting the
20. slurry as it ~ out of the manifold. Two measure-
ments were m.ade for each pump setting. m e volume
' of slurry was measured.
A graph t~as then plotted lor the 0, 20, 30-and
40 pump set~ings of volume aga~nst time in seconds
25. tusing a stop watch). A reaso~able straight line
plot was obtained.
8) Time to start of ~ressure build u~. This is
the time between the inlet valve being opened and
the pressure gauge actually starting to move rather
_ 30. than ~erely flicker.
- KD~/JR ' 25
1072179
.. . .
9) Theoretical ~olume pumned to start of ~ressure
build-up. This is the time under the eighth column ~rom
the left of table 1A multiplied by the ~olume reading under
the seventh column from the left of table 1A and is
5; purely theoretical.
r 10) Stratificatioll. (Table 3) This is determined by
pickling the plates in 1.40 speci4ic gravity for 6 hours
- - ~ followed by drying at 180F for 12 hours.
,~ The top bar and the bottom bar were then cut off
10. the plate and the remainder cut into four equal horizontal
strips labelled A B C and D with A at the bottom bar end
- of the plate. m ese were then weighed. The horizontal
- strips were then cut into four sections o~ three tubes
~each leaving out every fourth tube and labelled 1 to 4
15. with 1 at the lug sidè of the plate. The four sections one
'from each of the horizontal strips was then weighed and
the value given under l in Table 3 i3 this value. The
-~ - ~other vertical sections 2, 3 and 4 were weighed in the
same way.
20. 11) Pencil_porosity. This is d termined by the well
known technique of mercury in~rusion porosimetry and
is done on the same samples as Tab1e 3. Details of this
- technique are given in British Pa~ent Specification
No. 1331257 (EPS 61). - -
25. m e rotating vane viscometer values for certain of
the slurries used in the above examples are given below
in Table 2.
The viscometer used is illustrated in Fi~ures
6, 7 and 8.
.
- . . .
`
,
`` . - 107Z179
The apparatus consists of a frame 110 carrying
an electric motor 111 driving a paddle assembly 120
via a gear box 112 and a torque transducer 119. The
speed in the gear box 112 is sensed by a tachogenerator
5. 113 the output of which is fed to a digital volt- -
meter 113A. The voltage signal produced by the torque
transducer is fed .,o a chart recorder 114. The recorder
has a variable chart speed and a variable scale.
A sample. container 130 is claml~ly supporied on
. 10. an adjustable tàble 115 which car. be raised and lowered
. onguides 116 by a pneumatic cylinder 11?.
The sample container 130 has a detachable lid
131 located above the paddle assembly 120. The lid
can be secured to the container by an external bayonet
15. lock (not shown).
The paddle assembly 120 is removably attached to
the outpu,, shaft li8 of the gear box 112, and consists
o~ a central rod 121 having a lower boss 122 ~hich
in use nests in a hole 132 in the bottom of the container
20. 130. ~he rod 121 has a diameter D5 o~ ''.3 cms -and ~:
carries 3 pairs of paddles 123, 124 and 125. The paddles
123 and 125 are in the same p].al?e and are at right angles
to ~he paddles 12l~. A 1 t;he bl~1es of the paddles are
vertical and thus paralle7. to ihe ax~s of the rod 121.
25. The paddles are carried on arms 12~, 127 an~ 128. The
distance D6 from ihe centre of the arm 1'-'6 '~ the boss
122 is 6.5 cms, the distarlce D7 from t~e cen$re of -the arm
127 to the boss 122 ~s 3.9 cms and the distance from the
- centre of the a.m 12~3 to the boss 122 is 1.~ cms. The
30. width of each paddle D3 is 1.2 cms and its h~ght D2 is
1.2 cms and its thickness 0.1 cm. ~e distance D4 from
.. .. .
2?
... . , . . ' .. - - - , -
. . .
! 107;~179
... . .
.
,~- the inside edge of each paddle to the surface of the
,s~ rod 121 is 1.5 cms.
~- ' The distance D1 between the outside edges of the
~ paddles in a pair of paddles is 6.8 cms.
?~ 5 The-internal height of the container 130 is
~` 8.2 cms and its internal diameter is 8.8 cms. There
.~ are four internal'baffles 135 located at the ends of
diameters at right angles to each other. The thickness
D10, of each baffle 135 is 0.30 cms and its im~ard extent
' 10. D9 is 0.5 cms. The s,eparation D11 of the baffles on a
., diameter is 7.65 cms. Each baffle extends the full heigh-t
,' of the co~tainer.
~'' ' The container and baffles are made of smooth
. .
'` stainless steel.
' 15. The apparatus is used as follows:
.~ .
'The container is filled t,o a depth of 8.2 cms
with the maierial under test and raised into position,
clam~ed to the table 115 and the lid 131 secured.
The chart recorder 114 is started a~d the motor 111 is
20. then started wlth the gearing set for a low shear rate e.g.
6 rpm. The start up toraue and steady state torque are
' detected by the torque ~ransducer 119 and the motor and recorder
- run until'~a steady torque value has been rec,orded for at
least 2 minu~es. This is the steady s~ate ~orque value.
'~25. The torque value at the steady s~aie is qucted and if
an initial peak was present this fact is noted. The sample
is then removed, shaken with the bulk of the material being
_ ' measured and the container refilled. The measurement
is then repeated at a hlgher shear rate e.g. 18 rpm. The
, 28
~0~2179
cycle is repeated for as many shear rates as desired.
The background torque value namely with the
container 1~0 empty was found to be 0.004 lbs ft at all
the shear rates quoted in Table 2. The same value was
5. obtained ~rhen the container was filled ~Jith water.
The rotating vane viscometer torque value a~
defined herein is ~he value of the steady state torque
value of the sample measured in the above described manner
~ on the above described machine at a shear rate of 6 10. revolutions of the paddles per minute at ambient
temperature o~ 20C.
,
': ' ' ~ ' ~ ', . ` '
.
' ' ' ' ` . ' ' ' .
.
.
-- .
,. . - - . -
.
.
''
.. ..
. _ . . .
" '.
.. . .
.
.
, ~ 107Z179
~ .
. TA~LE 2
. .
. ~ Gre % ' Ro~.atinr vane viscomet;er
: ~ ~ ~ Solitls ,S~].~ha- ~rlear ~o~qu~ ~pl~Jenc~
. ~ o~ide ~iU~s tion rate of peak
- __ . _., . . __ . ,_. ~ ~
~ 2 66:34 2.57:1none 6 0.017 No
~ - __,n_ ~ ____
.. 18 0.014
. ._ . _ . . __ .
.~ 30 0.014 _
, ~ ,_ _ .. _ _
42 0.014
_ . ,_
~ 4 75:25 2.38:1 4.0 6 0.066 ~es
., _ . . -,...................... .--
.- . 24 0.066 ~o-
. , ,. _ ,,,. ,, . . _
42 0.066 No
:~, . _ ._ _ .
~-. 5 75:25 2.39:1 4~ 6 0.035 Yes
,, .,_ _ _
. 18 0~032 NO
' ___
. 30 0.027 No
:~: . ,. __ , .
.~ 42 0.028 No
. _ , ,_ _ ..
- 10 75:25. 3:1 _ . 6 0O014 Yes
~- . : ._ _ ... .,_
. 18 0.011 Yes,- ~ _ .. _ _
0.012 Yes
._ ,, , ,
42 0.013
, .. . _ __ . __ .,. ,.
Compar- 3:1 2.90:1 12.6 6 3.47 Yes
ison Example .
. 1 o~ G.B. . .
:1~80865 1
` . 12 ~ -100:0 0.90:1 17 11 0.010 No -
.
Stratification results ~or the plates made
in Examples 3, 5, 8 and 12 are given in-
Table 3 below.
.
Porosity results for the plates made in
Examples ~, 5 and 8 are given in Table 4 below.
;`` `~ 107Z179
,
. 1~ o
~ . U~
; 0 0 U~ 0
a~ ~ 0
___ N N N
0 0
N t~J N
1~ N N N
cr~ 0
N t'~ I N
,. 0 ~
~ 0 0 ~ ~O
.~- . ~ N ~I J
~; ._
~ C N ~ I 0
`.' +
S' U~
:: 0 N C~
51 N N N
~., _
0 0 0
O
~O ~ N N N
:-' 5.. E~ . ~t) CJ~ O
. ~ ~) O ~ ~ U~
, cq, ~ N N
N N N
:' .
~ ~ O O ~
''I U~ 0
.'~ . -
, ~q ~ ~ ,
.' 1~ .. .- .. -
rl :~ N ~ ~ O
¦-,, N N O
~ ~ . -
;~ U~
~ ~ 1~ N O
a~ ~ .. .. = ..
.~ ~ h ~O 1~ 0
,` . _ . .
ald~lex~ ~ u~ 0 N
-._ 31
- - .~ :
: - - - -
