Residue recovery process and apparatus

The recovery of materials from viscous bodies of petroleum residue and asphalt deposits which contain substantial quantities of the deposits by the use of an induced thermal gradient in a region of such a viscous body in which there is located a screw-like pump. This is effected by a process and apparatus that utilizes a thermal gradient about a archimedian screw-type pump in the pit or pond where its inlet is proximate of the surface of the pit or pond. The thermal gradient about the pump concentrates less viscous components at the vicinity of the inlet and a positive pressure is applied to assure a flow of residue towards the inlet allowing the lower viscosity materials to be captured and pumped from the pit or pond to a shore facility.

BRIEF DESCRIPTION OF THE INVENTION 
The process for the removal of petroleum residues of relatively high 
viscosity from pits and ponds by floating an Archimedean screw-type pump 
in the pit or pond such that its inlet is proximate of the surface of the 
pit or pond, providing a thermal gradient about the pump such that less 
viscous components of the petroleum residues become more highly 
concentrated in the vicinity of the inlet to the pump, utilizing a 
positive pressure on a surface layer of the residues in the pit or pond 
such that a flow of petroleum residue is created toward the inlet to the 
pump and a petroleum residue composition of a lower viscosity than that of 
the remainder of the pit or pond is displaced to the inlet of the pump and 
the displaced residue is pumped from the pit or pond to a shore facility. 
BACKGROUND TO THE INVENTION 
Throughout the world there are deposits of petroleum residues that are 
created artificially or naturally. For example, Bahrain pitch derives from 
the black oil residues of the Caltex Petroleum Corporation refinery [now 
operated by the affiliated Bahrain Petroleum Company B.S.C. (closed)] 
located in Sitrah, Bahrain (the largest island of the Bahrain group of 
islands), generated in the 1938-1942 time period. The residue, apparently 
with brackish quench water, was deposited in this time period in seven (7) 
pits creating seven (7) pitch ponds having a total area of about 70,000 
square meters. The only changes to this resting body of pitch over the 
years since 1942 are those gently wrought by natural forces, such as the 
dusting over by desert sands, evaporation from the searing Asia Minor 
(Middle East) heat and deposition of rain water and migrated sea water. 
The black oil residues deposited in the pits were compositionally 
relatively consistent because they were made primarily over a short period 
of time while the refinery was being limited to the manufacture of 
aviation fuel and other "light" cracked hydrocarbon feedstocks. 
Variability in the pitch was inputted when, during that period, untreated 
crude oil was fed through the refinery and then deposited into the pits. 
Thus, "Bahrain pitch", as that term is employed herein and in the claims, 
means the pitch collected and located in the aforementioned seven (7) 
ponds, as it was generated in the W.W.II timeframe and modified by natural 
forces in subsequent years to the year 1987. Its unique past establishes 
the pitch to be an unique material. 
Essentially all of the other black oil residues deposits about the world 
are "newly" created relative to the creation of the Bahrain pitch ponds. 
Hardly any of them are more than 30 years old and most of them were formed 
from residues of a highly diverse nature reflecting the advances in 
petroleum technology in the years between the formation of Bahrain pitch 
and this more recent period. Consequently, they possess compositions 
materially different from Bahrain pitch. The differences in chemical 
composition of Bahrain pitch from other black oil residue deposits can be 
seen from the differences in physical properties of Bahrain pitch and the 
other black oil residue deposits. One factor that stands out about Bahrain 
pitch is its high viscosity. In this regard, Bahrain pitch's viscosity 
fits somewhere between conventional residue deposits and the naturally 
occurring bitumens used primarily for making asphalt. This high viscosity 
is a reflection of the pitch's unusually high paraffinic and crystalline 
wax contents and its high asphaltenes content. Most of the world's black 
oil residues contain individually no more than about 10 weight % of these 
materials whereas Bahrain pitch contains more than about 20 weight % of 
them. In addition to this high wax and asphaltenes content, Bahrain pitch 
has an inordinately high crystallized carbon content. 
The special black oil residues used in forming the Bahrain pitch coupled 
with the environmental considerations extant during the history of the 
ponds caused to be generated a unique composition of matter. The quiescent 
state of its existence allowed the Bahrain pitch to undergo a 
transformation not unlike that which occurred in naturally-occurring 
asphaltic bitumens that one finds in countries such as Venezuela and 
Trinidad. Of course, the limited age of the Bahrain pitch ponds precludes 
the pitch from reaching the ripe physical state of these other natural 
bodies. Even so, aromatic molecules within the pitch benefited from the 
extended quiescent condition to become aligned into large anisotropic 
bodies which contribute to the pitch's high viscosity. Though such 
transformation is interesting chemistry, it however transformed Bahrain 
pitch from a material which theoretically could have been readily 
exploited for its fuel value. To date, very little of the Bahrain pitch 
ponds has been mined for any purpose whatsoever and none of that has been 
for an effective commercial gain. 
Unrefined Bahrain pitch has a high viscosity in the range of greater than 
40,000 centistokes, as determined at 150.degree. F. (65.6.degree. C.), 
greater than 6,000 centistokes, as determined at 125.degree. F. 
(79.degree. C.) and 2-5,000 centistokes, as determined at 200.degree. F. 
(93.degree. C.) Its A.P.I. at 60.degree. F. (15.5.degree. C.) is less than 
0, calculated to be typically -6 to -10 A.P.I. 
Unrefined Bahrain pitch comprises as major constituents, 
2 to 10 weight percent of total sediments including siliceous particulate 
matter and carbon particulate matter (generally viewed as crystallized 
colloidal carbon), 
8 to 12 weight percent of paraffinic and microcrystalline waxes, and 
20 to 25 weight percent of asphaltenes. 
The following table sets forth a summary of the composition and known 
properties of the Bahrain pitch: 
TABLE 1 
______________________________________ 
Typical Specifications from Bahrain Pitch Ponds 
Neat Pitch 
5%.sup.* 
10%.sup.** 
15%.sup.*** 
______________________________________ 
Viscosities @ 38.degree. C. 
Centistokes &gt;20,000 11,000 1,500 900 
Redwood (sec.s) 
95,000 52,250 7,125 4,275 
Saybolt (sec.s) 
85,000 46,750 6,375 3,825 
Ash Content, w/w max. 
0.1 0.1 0.1 0.1 
BS & W, % w/w max. 
1 1 1 1 
Sulphur Content, % w/w 
4.9 4.7 4.4 4.2 
Flash Point .degree.C. 
129 61 61 61 
Pour Point .degree.C. 
42. 29.3 27.1 15.0 
.degree.F. 107.6 86. 81. 59. 
Asphaltenes, % w/w 
24 23 22 20 
______________________________________ 
.sup.* Diluted by that weight % by diesel or light cycle gas oil. 
.sup.** Diluted by that weight % by diesel or light cycle gas oil. 
.sup.*** Diluted by that weight % by diesel or light cycle gas oil. 
It has been known for some time that the practical limit for cutting 
unrefined Bahrain pitch with light cycle gas oil or diesel oil is 15-18% 
w/w. Above this figure precipitation of asphaltenes from solution was 
recognized as occurring. 
The Bahrain pitch as found in the ponds has a significant particulates 
sediment content ranging in the area of 2 to 10 weight %, give or take a 
percent, based on the weight of the pitch. Of this sediment content, the 
inorganic oxide content of the sediment ranges in the area of 0.25 to 5% 
by weight of the pitch. The inorganic oxide content should be reduced in 
refining the pitch to the first stage, to between 0.05 to 0.1% by weight 
of the pitch, and preferably a lesser amount. The remainder of the 
sediment content of the pitch is particulate carbon matter, such as 
crystallized colloidal carbon. 
According to Nelson, Petroleum Refinery Engineering, Fourth Edition, 
McGraw-Hill Book Company, New York, N.Y., London, at pages 71-72, 
"At gravities below 10 API, water and sediment do not settle out of the 
oil and such oils cannot be displaced from tanks by water." 
The properties reflected above with respect to the black oil residues of 
Bahrain and the residues deposited from refineries elsewhere are more 
tractable than the naturally-occurring asphaltic bitumens that one finds 
in countries such as Venezuela (Orinoco basin) and Trinidad. However, in 
all instances, these highly viscous residues and asphalt containing 
materials possess substantial viscosities and are of a generally 
intractable nature. 
The most common method employed for the removal of these viscous materials 
from their landfill deposits has been by shovel, typically mechanically 
but sometimes by hand. Some efforts have been made to use archimedean 
screw-type pumps to more continuously remove them from the landfill 
deposits. None of these procedures have proven totally adequate for an 
effectively commercial process for recovering such residues and asphaltic 
materials from the deposits. The exceptionally high viscosities of these 
materials makes these procedures slow and irregular, thereby materially 
increasing the cost of the recovery efforts. 
There is need in the industrial recovery of petroleum residue and asphalt 
deposits for a more efficient and effective method for removing the 
deposits for subsequent treatment. This invention relates to a process and 
an apparatus sequence that materially enhances ones ability to effect such 
recovery. 
THE INVENTION 
This invention stems from the recognition that the petroleum residue 
deposits as well as asphalt deposits, the world over, possess at least a 
small amount of less viscous components which if more concentrated in the 
deposits would aid at selected temperatures in significantly reducing the 
viscosity of the deposits such that their recovery can be made materially 
easier to carry out. As indicated above, it is well known that the 
viscosities of such deposits can be materially reduced by blending a 
solvent in the deposits. However, such solvents have a materially greater 
money value than the deposits. As a result, their use greatly increases 
the cost of the recovered deposit materials and since the deposits possess 
relatively low commercial value, the use of solvents becomes economically 
prohibitive. This invention utilizes inherently-present solvents in the 
residues and asphalts to aid in the reduction of the viscosity of the 
deposit materials whereby to enhance their recovery for further 
processing. 
The invention relates to the recovery of materials from viscous bodies of 
petroleum residue and asphalt deposits which contain substantial 
quantities of the deposits. The invention is concerned with the recovery 
of viscous petroleum residue and asphalt deposits from pits or ponds of 
substantial size from which recovery of the deposits are normally 
difficult to effect. Though the invention is directed primarily to the 
recovery of petroleum residue and asphalt deposits having gravities below 
10 A.P.I. that are located in fairly large and/or deep pits and ponds, it 
is also applicable to the recovery of other petroleum materials having a 
higher A.P.I. gravity that are difficult to recovery such as petroleum 
residues containing high paraffinic or microcrystalline wax contents. 
This invention relates to a process which comprises a combination of 
features which include 
i. providing a thermal gradient in the region of the surface of a viscous 
body of petroleum residue or asphalt deposit, 
ii. locating an archimedean screw-type pump in said region such that the 
inlet of the pump is proximate of the surface of the deposit and the 
outlet of the pump is openly connected to transport means for passing the 
deposit from the pump to a shore receiving system used for the recovery of 
the deposit, 
iii. passing a skimmer in a reciprocating motion relative to the pump such 
that deposit is pushed by the skimmer toward the pump within said region 
and then withdrawn from the pump in a direction away from the pump, and 
iv. transporting deposit into the inlet of the pump, through the outlet of 
the pump and to said shore receiving system. 
Preferably, the process of the invention relates to the removal of 
petroleum residues of relatively high viscosity from pits and ponds by 
floating an archimedean screw-type pump in the pit or pond such that its 
inlet is proximate of the surface of the pit or pond, providing a thermal 
gradient about the pump such that less viscous components of the petroleum 
residues become more highly concentrated in the vicinity of the inlet to 
the pump, utilizing a positive pressure on a surface layer of the residues 
in the pit or pond such that a flow of petroleum residue is created toward 
the inlet to the pump and a petroleum residue composition of a lower 
viscosity than that of the remainder of the pit or pond is displaced to 
the inlet of the pump and the displaced residue is pumped from the pit or 
pond to a shore facility. 
The invention relates to an apparatus for the removal of petroleum residues 
of relatively high viscosity from pits and ponds which comprises a 
floating archimedean screw-type pump in the pit or pond such that its 
inlet is proximate of the surface of the pit or pond, means for providing 
a thermal gradient about the pump such that less viscous components of the 
petroleum residues become more highly concentrated in the vicinity of the 
inlet to the pump, means for applying a positive pressure on a surface 
layer of the residues in the pit or pond such that a flow of petroleum 
residue is created toward the inlet to the pump and a petroleum residue 
composition of a lower viscosity than that of the remainder of the pit or 
pond is displaced to the inlet of the pump such that the displaced residue 
is pumped from the pit or pond to a shore facility.

DETAILED DESCRIPTION OF THE INVENTION 
All petroleum residues and asphalts contain a molecular distribution that 
varies significantly. As a general rule, the lower the molecular weight of 
a component in the petroleum residue or asphaltic compositions, the less 
viscous will be the component. The less viscous components may not be 
significantly lower boiling than the less volatile components of the 
petroleum residue or asphaltic compositions, but when concentrated, they 
are clearly less viscous and more flowable at lower temperatures. 
It has been discovered that thermal treatment of petroleum residues and 
asphalts causes the less viscous components of those compositions to rise 
and sufficiently separate from the more viscous components of the 
compositions such that there is caused a gradient reduction in viscosity 
in the compositions. This invention takes advantage of that phenomena and 
lowers the viscosity of the compositions in a manner that facilitates 
their removal from pits and ponds. 
The invention utilizes localized introduction of heat to a large body of 
deposited petroleum residues or asphalt such that the temperature in a 
predominant portion of the body is unaffected by such localized 
introduction of heat. However, the invention utilizes localized heating to 
alter the composition of the residue or asphalt in the proximity of the 
heating and to cause less viscous residue or asphalt composition to 
migrate into the localized heated region. This sequence causes the process 
to be continuous in the sense that the solvation of the deposit, which is 
subject to removal through an archimedean screw-like pump, is effected by 
a extracting a higher concentration of the less viscous components from 
other portions of the body being treated. 
The invention incorporates localized heating of a relatively large body of 
viscous petroleum residues or asphalt deposit so as to cause seepage of 
less viscous components of the deposit to the area of the localized 
heating such that the concentration of the less viscous components in such 
area is increased and the flow characteristics of the deposit in the area 
of localized heating is improved, i.e., the deposit exhibits a less 
viscous nature. 
The drawings illustrate one particular mode for practicing the invention. 
Other modes are contemplated and the invention is not intended to be 
limited to that depicted in the drawings. 
With respect to FIGS. 1 and 2, there is shown pond or pit area 1 contained 
by land mass 2. Pond or pit 1 may contain a viscous body of petroleum 
residues deposit or an asphalt deposit (natural or synthetic). Located 
offshore in area 1 is archimedean screw-like pump 3 suspended in the 
viscous body by floatation devices 5. Surrounding an area about pump 3 
within area 1 is thermal transfer line or lines 29, supplied with heat 
from an offshore system (not shown). As shown in FIGS. 1 and 2, line 29 
comprises a loop arrangement about pump 3 to insure the localization of 
heat in the vicinity of pump 3. The arrows in line 29 characterize the 
flow within the line. 
Line 29 may be an electrically or fluid heated pipe or a system that 
effects heating of the deposit residing about it by contact heating. 
Illustrative of the following is a porous piping in which heated steam fed 
from land is caused to bubble from orifices in the piping into the 
surrounding deposit and by contact heating, raises the temperature of the 
deposit. This induces a thermal gradient about line 29 and also about pump 
3. 
It has been determined that if one were to rely solely on the induced 
temperature gradient in the localized regions of a pit or pond to effect 
removal of the deposit, there would be insufficient flow into the pump to 
efficiently support the pumping action. In order to induce sufficient of 
the very viscous deposit to the induction end of the pump, inlet 6, it is 
desirable to introduce a positive pressure on a thermally treated portion 
of the deposit so that a mass thereof is transported to the inlet of the 
pump. This can be easily accomplished by positioning a blade or skimmer 7 
in the localized heated region of the pit or pond 1 surrounding pump 3 and 
using travel guide cables 13 and 15, to which blade or skimmer 7 is 
affixed, in this case, through frame 17, to move the blade or skimmer 7 
forward toward pump 3 while it cuts into the viscous body and forces 
deposit into the inlet 6 of pump 3. As shown in FIG. 2, blade or skimmer 7 
is capable of pivoting in frame 17 such that on withdrawal from pump 3, 
after having forced a load of the deposit into the pump inlet 6, the blade 
or skimmer 7 is pushed out into hatched line position 9 on the surface of 
the viscous body. As a result, blade or skimmer 7 rides during withdrawal 
on the surface of the viscous body without introduction of significant 
resistance to movement. Frame 17 is affixed to flotation devices 11 which 
serve to keep frame 17 and blade or skimmer 7 in the desired positions 
relative to the viscous body of deposit materials. 
The movement of blade or skimmer 7 is controlled by matched pulley systems 
21 and 33. Their top and side views are depicted in FIGS. 1 and 2. Each 
pulley system is driven by its own motor, 25 and 31. The pulley systems 
are located on support surfaces 23 and 32 and each system, 21 or 33, 
rotates on a common axle for each pair of pulley wheels that are mounted 
in support walls 22 and 30 respectively. Of course, support walls are 
provided on opposite sides of the pair of pulley wheels. 
As shown in FIGS. 1 and 2, the outlet of pump 3 is connected to withdrawal 
pipe 19 and the driving force for carrying the deposit is the pump 3 
driven by motor 8. Motor 8 may be electrical or gasoline controlled. The 
removed deposit is collected in storage tank 27. In certain circumstances 
it may be desirable to heat withdrawal pipe 19 to facilitate the removal 
of the deposit via the pump and the withdrawal pipe. For example, should 
the viscosity of the deposit in pipe 19 increase when the pipe is outside 
of the heated region about pump 3, and the viscosity is too great for pump 
3 to handle, then by raising the temperature of pipe 19, the viscosity of 
the deposit in pipe 19 can be sufficiently lowered to facilitate the 
removal operation. Such heating of pipe 19 can be effected by electrically 
heating the pipe by providing an electrical wrapping around pipe 19 at 
least in those sections of pipe 19 where sufficient "freezing" of deposit 
occurs that removal of the deposit is deleteriously inhibited. 
FIG. 3 provides a more detailed characterization of the operation of blade 
or skimmer 7 as it cuts through viscous body 1 pushing deposit toward pump 
3. As shown, blade or skimmer 7 cuts into the body 1 and forces a portion 
of the material forward to the pump. Frame 17 comprises a pivot axle 37 
that extends the length of the frame. The axle 37 is a rod with threaded 
ends that allow the bolting of the axle to frame 17. Axle 37 extends 
through sleeve 36 which coexists at the other side of frame 17. Extending 
through sleeves 36 are cables 13 and 15, see FIGS. 1 and 2 above. Cables 
13 and 15 are held in fixed positions by sleeves 36 so that as the cables 
move, so moves frame 17. Frame 17 securely holds blade or skimmer 7 by 
sliding axle 37 through a tubular end in blade or skimmer 7 so that blade 
or skimmer 7 can pivot or rotate on axle 37. Blade or skimmer 7 is held in 
the position shown in FIG. 3 by backwall 35 which forms part of frame 17. 
Backwall 35 acts as a stop for blade or skimmer 7 so that its rotation is 
a counterclockwise direction is arrested so that it is maintained in the 
vertical position shown in FIGS. 2 and 3. However, frame 17 is suitably 
constructed that blade or skimmer 7 can freely rotate in a clockwise 
direction when the blade or skimmer 7 is withdrawn from pump 7. Needless 
to say that whether blade or skimmer 7 rotates clockwise or 
counterclockwise when withdrawn from pump 3 is dependent on the positional 
relationship taken for these instruments. 
In FIGS. 1 and 2, blade or skimmer 7 is positioned so that when it is 
pushed toward pump 3, blade or skimmer 7 is pushed in a counterclockwise 
direction. If blade or skimmer 7 were located on the other side of pump 3, 
then, of course, it would be pushed in a clockwise direction. 
A desirable method for heating the region of pond or pit 1 around pump 3 is 
depicted in FIG. 4. As a replacement for line 29 as shown in FIGS. 1 and 
2, one may employ tubular coil 38 according to the arrangement of FIG. 4. 
As shown in FIG. 4, coil 38 possesses a tubular inlet 39 and a tubular 
outlet 41. Located on each tubular leg of coil 38 are sparging holes 43, 
each of which openly connect with the interior of each of the tubular 
legs. The relationship of pump 3 containing inlet 6 and blade or skimmer 7 
to tubular coil 38 is established by showing a phantom representation of 
pump 3 and blade or skimmer 7 in FIG. 4. The operation of coil 38 is 
simple. A heated fluid, preferably steam, is supplied through the tubular 
inlet 39 and issues through sparging holes 43 as it circulates through 
coil 38. Enough heated fluid is supplied to coil 38 that a portion remains 
to pass through outlet 41. Uniformity of the sparge streams that issue 
through and from sparging holes 43 can be controlled by correlating the 
diameters of the holes to the steam pressure in the various portions of 
coil 38. 
The operation of the process of the invention is further demonstrated in 
the schematic representation depicted in FIG. 5. As shown in FIG. 5, there 
is located line 29 in a region below and around pump 3 containing inlet 6, 
whose entry port is positioned at about the surface of viscous body 1. In 
this embodiment, line 29 can be a variety of heating means but in this 
case, it is represented by coil 38 of FIG. 4. As steam issues from 
sparging holes 43 into the viscous body located about pump 3, steam 
represented by the wiggly lines courses upward and heats the region around 
pump 3. This causes a temperature gradient to be created from line 29 to 
the surface of body 1. This temperature gradient is illustrated by zones 
A, B and C, each illustrated as differently shaded rectangular zones. The 
deeper shaded zone A is located closest to line 29, therefore that zone is 
at a higher temperature than zones B and C. Logically, zone B is hotter 
than zone C. Because of this temperature differential, less viscous 
materials are concentrated to the greatest extent, on a relative basis, in 
the hottest zone, in this case zone A. Because line 29 is a loop that 
allows deposit to pass through it, less viscous components in the 
deposited material located below line 29 are caused to migrate upward to 
replace less viscous materials removed to a higher level in the viscous 
body. This also takes place outside the loop of line 29. Thus, heating of 
the body in a region causes striations of less viscous material to be 
eluted from sections of the viscous body into other sections of the 
viscous body. As a consequence of heating one section of the viscous body, 
less viscous materials are extracted upwardly in a larger region of the 
body extending outside of the heated region, all effected without having 
to heat the larger region. 
As pointed out above, petroleum residues vary from site to site. In some 
cases, the residues are waxy and in some cases they are viscoelastic. In 
other cases, the residues contain sufficient byproduct chemicals that they 
have a sufficient low enough viscosity to allow reasonable flow under the 
recovery conditions described above. Therefore, there are situations where 
sparged steam might not adequately raise the temperature of the body 1 at 
the region about the pump to insure adequate deposit removal. In such a 
case, an alternative to the use of sparge ring is a closed loop heating 
coil which circumscribes the heating region about the pump. The coil would 
be heated by a suitably heated fluid brought to a temperature greater than 
100.degree. C. Suitable heated fluids comprise steam or commercially 
available heat transfer fluids. 
However, in those cases where the residues are so waxy or visco-elastic 
that they tend to plug the inlet of the archimedean screw-like pump 3, 
there are simple alterations to the pump that can be made that will insure 
the easy introduction of the residue deposits to the blade of the pump 
without holdup at the hopper inlet 6 of the pump. One such alteration is 
shown in FIG. 6. 
FIG. 6 shows an alteration of pump 3 which includes the use of a sparger 
ring 45 at the entrance of hopper inlet 6. Sparger ring 45 comprises a 
series of nozzles circumscribing the entrance of hopper 6. As a flow aid 
to deposit fed to the hopper entrance, as shown in FIG. 8, hot water or 
well-known chemical flow aid mixtures can be sprayed, shown as spray 
streams 47, from all or many of the nozzles into the interior of hopper 
inlet 6. This procedure facilitates the feeding to the blades of the pump 
when the deposit being fed is almost intractible and helps to reduce the 
drag coefficient on the hopper walls and product delivery pipe 19, see 
FIGS. 1 and 2. 
FIG. 7 illustrates an improvement in the hopper inlet design which provides 
maximum adaptibility to flow and feed considerations. In this figure, the 
hopper inlet 49 is a modification of the hopper inlet 6 design of FIG. 6. 
As shown in FIG. 9, hopper inlet 49 comprises housing 48 and contains 
sparger ring 45 and spray streams 47 discussed previously. In addition, 
hopper housing 48 is circumscribed by four (4) hydraulically or 
pneumatically controlled pistons 51, three of which are shown in FIG. 9. 
The pistons 51 are affixed to hopper housing 48 by piston brackets 55 and 
to fixed collar 52 by brackets 53. Collar 52 is fixedly linked to the 
outer shell of pump 3. Each of the pistons 51 contain fluid tubings 54, 
for supplying fluid, air or liquid, to actuate or control the individual 
pistons. By virtue of separate controls over the operation of the pistons 
51, hopper housing 48 can be raised or lowered uniformly or raised or 
lowered nonuniformly, i.e., eccentrically, at an one or more piston 51 
sites. There is provided in hopper 49, internal sleeve 56 which is fixed 
to the shell of pump 3. The lower end of housing 48 is another sleeve that 
mates with sleeve 56 so that housing 48 can be slid up or down sleeve 56. 
By making sleeve 56 of a material that is flexible, such as rubber, 
pistons 51 can also operate to bend the hopper inlet in any direction, 
such as toward or away from the direction of deposit flow actuated by 
blade or skimmer 7. 
The arrangement of FIGS. 7 and 9 works as follows. There are occasions when 
the surface of the pit or pond will vary during the recovery operation, 
mainly owing to the response of the viscous body 1 to either too little or 
too much delivery of deposit by the action of blade or skimmer 7. There 
will be times when the hopper inlet should be lowered or raised or turned 
into or away from the direction of deposit flow. All of these conditions 
can be readily accomodated by the novel hopper design for the pump, as 
depicted in FIGS. 7 and 9.