Note: Descriptions are shown in the official language in which they were submitted.
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Process for the Recovery of Petroleum I=Iydrocarbons and heavy metals from
Solid and Aqueous
Media
Background to the Invention
The present invention relates to removal and recovery of heavy metals and
petroleum hydrocarbons
which mav be present in the contarninated soil, clays, and sand and aqueous
media and a method for
remediating the soil and aqueous media with one or more organic chernicals
where at least one water
soluble dialkldithiocarbamate is admixed with one water soluble dioctyl sodium
sulfosuc:cinate so as
recover the petroleum hydrocarbons and heavy metals contained in the
contaminated soil and aqueous
media.
The invention also relates to the field of petraleum hydrocarbons recovery
from contaminated soils and
aqueous media. 'vIore specifically the invention relates to improving a
petroleum. hydrocarbon recovery
system and method for not only rernoving hydrocarbons from contaminated soils
and aqaeous media but
from other media including subte:ranean oil deposits, sludge deposits on
machines and 'oore hole
equipment including pumping equipment and piping, in addition treating
petroleum sludge deposits on
the bottom of crude oil tanks.
Contaminated solids( soils) and aqueous media including groundwater contain
high levels of toxic
organic and inortanic compounds and therefore need to be treated. Soils
containinb hazardous organic
pollutants and/or heavy metals pose a serious environmental threat and over
time if left untreated leads to
huge groundwater contamination particularly if the toxic contaminates make
their way into groundwater
aquifers. These aquifers will carry these toxic contaminltes into the
groundwater which in turn will
eventually impact the ecological balance of the environment and will end up in
the food chain.
In most cases, the contamination occurred as a result of ccrtain industrial
activities which took place and
as sucli were left in the ground by these industrial activities. Due to the
potential environmental problems
associated with not treating the contaminated soils and aqueous media are well
documented and have led
to novernment agencies establishing guidelines or limits in terms of the
levels of bv which these
conlpounds can remain in the soil. In Ontario, tlte Waste Management Branch of
the Province has issued
"Guidelines for the decommissioning and clean up sites in Ontario
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Typically, metal contaminates include metals which occur naturall,v in the
environment such as arsenie as
well as metals which are not normally present in the solids or aqueous media(
i.e. man ntade metals)
such lead, zinc, mereury, cadmium, copper, nickel, chromium, and cobalt, as
well as other metals such as
silver, ai-senic and vanadium. Soils which contain excessive amounts of these
heavy metals are restricted
in their land use must be treated so as to remove and encapsulate these
excessive amounts of heavy
metals.
The invention relates to the removal and recovery of these heavy metals. The
removal of these metals
involves contacting the soils with an aqueous solution containing one or more
surfaetants which when
admixed with the soil create slurry. The chemical reaction associated with the
contacting of the surfactant
with the contaminated soils creates separation between the heavy metals and
the soil particles and the
"washed soils are conveyed to separate staging area and the heavy metals are
"drawn of7 and filtered out
using a number of methods including but not limited to a centrifuge. The
treated soil is usually land6lled
or used as subsoil for other industrial uses.
Description of Prior Art
In US. PAT# 5,772,776 a method is proposed that a soluble
dialkyldithiocarbomate can effectively
recover Pb and other heavy metals by admixing at least one water soluble
dialkyldithiocarbomate with
initial soil slurry so as to obtain product aqueous soil slurry comprising one
or more water insoluble
metal-dialkyklithio-carbamate complexes whiehcan be physically separated from
the soil slurry. This
invention intends to incorporate a similar compound in its polishing phase as
described later in this
invention.
US.PAT 6797195 discloses a process for recovering metals from waste streams
for separating the
tecovering precious metals from industrial waste streams, adjusting the pH of
an industri.al waste stream
and containing the precious and non-precious metals to be recovered; adding a
metal coinplexing agent to
promote the aggregation of the said metal ions; adding a flocculating agent to
the increase the said metal
ions and form a solution thereof. Dewatering said solution to form a
supernatant, dewatering and drying
said sludge to form an ionic metal concentrate to selectively remove and
recover the desired metal
therefore.
US. PAT #5,882,429 discloses a process for the fixation of metals and removal
of hydrocarbons from
contaminated soils whereby liquid phase agglomeration techniques, in
combination \vith solvent
extraction were used to remediate organic contarninated soils. The combined
process aPows concurrent
removal of the organics and fixation of the heavy metals. The removal of
hydrocarbons is well
understood in the art, however the process fails to address the problem of
separating the hydrocarbons
from the liquid while at the same removing the heavy metals from the
contaminated soils. Fixation of the
heavy metals may not meet the guidelines in the Province of Ontario as the
metals still remain in the soil
albeit in an encapsulated state.
A more effective method would be to completely remove the heavy metals from
the contaminated media
as such would eliminate any future leaching that may occur in the soils.
Further, fine te:ctured fines such
as clays and sledges containing fines, separation of the hydrocarbons and
heavy metals has proven to be a
difficult technical problem particularly in the case of mature fine tailings
created by the {Clark hot water
extraction process" used in the extraction of bitumen from the oil sands in
Alberta. In addition, processes
for removing metals and hydrocarbons from contaminated soils and aqueous media
have: long been
associated with the high costs and storage problems. Long term liability of
the waste management still
exists in the environment. Although many technologies exist including ion
exchange or,.-lectrolyte
recovery of metals from waste streams, the problem is its is difficult to
apply the technology in
continuous process method such as water filtration systems. None of the known
prior art technologies
separate and recover both hydrocarbons and a variety of heavy metals in one
eontinuous "washing"
process.
US.PAT #5264135 discloses a process for the stabilization of inetals in
wastewater sluclge whereby
certain metal complexing agents are added to the sludge and the coniplexing
agents are :>elected from a
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group consisting of ditnethyldithiocarabamate, diethylcarbamate,
trithiocarbamate. The wastewater is
treated in a clarifier with either caustic (NaOH) or lime (Ca (OH)<sub>2</sub>).
Once mixed in the clarifier, the
heavy metals will precipitate out of the solution and drop to the bottom of
the clarifier. The precipitate is
then periodically drawn off from the bottom to form sludge. This sludge is
then transporl:ed to a
dewaterine press and at this stage the above compounds are added in sufficient
amounts as to stabilize the
heavy rnetals. The removal of the heavy metals from the sludge is difficult
and requires a very
sophisticated complexing agent.
The dewatered sludge is then tested using the requirements of the TCLP test.
The maxirr um acceptable
levels for certain metals, as defined in the Federal Register (Toxicity
Characteristic Fina:l Rule, March, 29
1990) are illustrated in the following table
TCLP Maximum Limits
for Organics Parts per
Million m)
Arsenic 5
Barium 100
Cadmium I
Chromium 5
Lead 5
Vlercu 0.2
Selenium I
Silver ~
The amount of complexing agent according to this invention which is added to
the sludge is in the range
of 5 to 50,000 ppm. There are number of problems with this process which in
part make it economically
unfeasible in terms of being cost- effective and if more stringent TCLP tests
are introduced in the future,
the tests in fact, may be able to leach out the metals thereby impacting the
feasibility of using this
invention in the fie1d.
In addition, the process relies on a settling process which is undesirable for
large quantities of solid
hazardous or toxic wastes and in most cases cannot be regenerated.
U.S. Pat. No. 5,008,017 (Kiel, et al.) discloses a process for recovering
metals form a waste stream where
the dewatered sludge is heated to 900 F to recover silver. However this would
be unfeasible in a process
type removable method as the energy costs would exceed the revenue stream that
could be generated
from such a process.
None of the above are technologies actually separates the hydrocarbons and the
heavy metals from the
waste stream without additional separation steps. It is therefore a need for a
method to efficiently remove
and recover heavy -metais- and-petroleum hydrocarbons from contamiuated solid
and aqr.eous waste
streams in one completely integrated process system.
U.S. Pat. No_ 6,099,206 (Pennell) discloses a process for remediating
contaminated aqu: fers by
modifying the density of the non-aqueous phase liquids (NAPL) including
petroleum-bE.sed products
such as gasoline. The process also addresses the problem with remediating
denser non-aqueous phase
liquids (DNAI'L's). Pennell's approach to recovering or removing hydrocarbons
is to "flush a surfactant-
based solution down into the subsurface containing the above contaminates
through an injection well.
The process modifies the density of the DNAPL by flushing the aquifer with a
suitable alcohol; and
displacing the NAPL by flushing the aquifer with a suitable surfactant. The
surfactant <<sed to lower the
interfacial tension between the DNAPL's and the solid ( subsurface soil) was
(4% Aerosol MA/OT 4%
Aersol AYIOT) The combination of 4% Aerosol MA/OT ( sodium diamvl
sulfosuccin,tte) and 4%
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Aerosol AY/OT ( sodium dioctylsulfosuccinate ) worked the most efficientlv in
terms of removing the
DNAPL.
The present invention is an improvement over this invention and the prior art
with resQect to the
removal of hydrocarbons in two instances; firstly, it utilizes only a 0,5 %
surfactant to water process
solution ( 99.5% water to 0.5% surfactant) to displace the hydrocarbons making
it extremely cost-
effective over the prior invention, and secondly, injecting process solutions
into subsurface media is
difficult to monitor in terms of its effectiveness. In other words, the
volunie of DNAPL`s actually that
were displaced during the process is never fully calculated.
The improvements in the method to extract petroleum-based contaminates found
in the current
invention, as shown in Figure 1.0 , is firstly, the process can be monitored
and tailored at every stage to
ensure complete removal of the contaminates. The primary reason for this is a
improvernent over other
methods, is the fact that the process is carried out above ground in a closed-
loop mecl:anical separation
system. The known art as described in the above invention is cost-
prohibitive. The cost of chenuca]s to
remove contaminates from solids and aqueous media is an extremely important
factor in determining
what recovery method is employed in the field.
Detailed Description of the Invention
The present invention relates to the removal of petroleum hydrocarbons and
heavy meta.ls from
contaminated soil, and aqueous solutions. The term "soil" is used in a generic
sense to refer to the various
materials which can be found in the earth and which can be subject to
contamination.
Common contaminates include, crude oils, that is mineral oils, petroleum,
solvents or acid treated mineral
oils, and oils derived from coal such as cresol and heavy metals such lead,
mercury,
titanium.zinc,lead,arsenie etc . Also included are refined hydrocarbons such
as gasoline's, diesel,
kerosene's: and commercial oil-containing compositions such as motor oils,
lubricants aad hydraulic
fluids.
An important material contained in the invention is the unique use of "Gemini
surfactarts. Additional
surfactants, preferably in the amounts within the ranges 0.01- 15% can be used
and can be characterized
as non-ionic, anionic, cationic, or amphoeric. Non-ionic surfactants include
nonylpenol, sorbitan
monooleate, glycerol monooleate poly (ethylene oxide). non ionic surfactants
used in the invention may
include the following, sodium exylene suflonate, dioctyl sodi.um
sulfosuccinate, di-2-ethylhexyl sodium
sulfosuccinate ( Manufacturers Chemicals). These surfactants influence the
properties of surfaces and
interfaces such as the interfaces between hydrocarbons and water. In
scientific terms, th~,.se surfactants
are considered shoet-chained fatty acids and form monolayers at the interfaces
and show surface activity.
In other words, these molecules are capable of associating to form micelles.
The uniqueness of the
surfactants employed by this invention is the fact that these molecules have
two hydrophilic (chiefly
ionic) groups and two tails and are linked by a unique spacer group. Sodium
dioetylsull'osuccinate is
commercially available from chemical manufactures , the sodium
dioctylsulfosuccinate used in this
invention is supplied by Manufacturers Chemical LLP, Cleveland Tennessee under
th,s Trade Name
DOSS.
Another embodiment of the invention relates to the field of petroleum
hydrocarbon production recovery
and handling and a method of fluidizing, separating, and recovering highly
viscous residual petroleum
product such as sludge, process equipment and or inorganic solids and may
relate to subterranean oil
deposits whereby the invention may make the oil flow more easily thereby
improving the method of
extracting the said oil from the below surface reservoir. More particular as
in the case of sludge in the
aforementioned paragraph or what is referred as "slop oil", the invention may
extract ctude oil
commonly included as a percentage of the suspended solids contaminates
particularly such as inorganic
sand and clay particles contained in certain waste streams and solids which
are contained in the residual
media in the bottom of oil storage tanks, bulk crude oil tankers and but not
limited the aforementioned
and may include media such as oil sand tailings referred in the industry as
Mature Fine Tailings. In
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addition to the foregoing, the invention may remove certain waxes which are
contained in the crude and
which form deposits, such deposits consist of linear paraffin hydrocarbons and
naphtenic hydrocarbons, and such hydrocarbons can exist in either liquid state
or solid state. Solid state
paraffins caused flow rate reduction in pipelines and oil pumping operations.
Currently toxic solvents are
used in some cases to remove the above waxes.
In the current invention, the final removal of heavy metals from waste streams
of the he.avy metal
recovery operation will be flowed through a fixed bed tower containing a
chelating resin manufactured
by AICO Chemical, Chattanooga Tennessee and more specifically this resin which
will capture zinc,
mercury, selenium, arsenic, copper, lead, and silver from mature fine tailings
including but not limited to
mine tailing, offshore drilling mud tailings. Fig 1.0 illustrates the process
whereby the extracted heavy
metals will be solidified for use in other industrial processes.
Description of the Drawing Figure
Fig.1.0 is schematic diagram of surfactant- enhanced petroleum hydrocarbon and
heavy metals recovery
and extraction system apparatus. The apparatus consists generally of a sample
of contaminated soi11. A
conveyor to transport the soil to screener 2. At screener/crusher where the
soil is crushedl to appropriate
size 3. A screw conveyor containing a power shaft where the soil is
transported to the pugmill/mixer 4.
The process solution containing the surfactants may be injected at this stage
and is an option to be
cons.idered for those who will practice the art. A pugmill/mixer where the
soil mixed with the process
solution 5. A reagent tank which pumps the process solution to the
pugmill/mixer 6. A screw conveyor
which transport the mixed slurry to centrifuge 7. A centrifuge which separates
the solids from the liquids
( optional ) S. The solids are drawn off the bottom and transported to a clean
soil staginl; area 9. The
remaining liquids containing the contaminates
( i.e. petroleum hydrocarbons and heavy metals are transported to
liquid/clarifier 10. The liquids are
separated whereby more process solution is injected. At this stage the
petroleum hydrocarbons are
decantered off into a holding tank. 11. The remaining wastewater stream is
pumped through fluidired
bed containing the aforementioned resin( AICO Chemicals) 12. The metals are
solidified and dried in
closed vessel 19. A flocculant maybe added during the clarification phase to
settle any clays or fines still
remaining in the wa.stewater 24. The flocculant is pumped to the liquid
separator 21.After the heavy
metals are removed the wastewater is pumped into a holding tank 17. The
recvcled water is then pumped
back into the pugmilUmixer. The recycled water contains 90-97% of the
surfactants useci in the extraction
of the petroleum hydrocarbons 16.
Further Notes
The above schematic can be fabricated as one completely integrated system and
is intended to be a
mobile process plant.
Examples
In a preferred working embodiment of the invention, sodium
dioctylsulfosuccinate is provided with 99
grams water at a concentration of from about 0.05% to about 10.0% by volume,
and preferably about 1%
to achieve final solution. The 100 grams of process solution was then added to
200 granis of
contaminated soil. The contents were agitated at a high shear for 2 minutes.
The solutioil was allowed to
stand for 5 minutes thereby creating two phases. The upper phase contained the
solubilized heavy metals
and the lower phase contained solids and other metals. The soil was
solubilized heavy metals and the lower phase contained solids and other
metals. The soil was spiked with
a variety of heavy metals as illustrated in Table 2
The upper stage (i.e. the wastewater stream) was treated with additional
complexing agents.
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Table 2.0 Represents soil being spike with heavy metals
Base Dirt # 2 Solid
Lab Report 199517 Result MDL t'tqetJi D Th
MeraLs Scaa
Alutninum (Al) 9870 2000 6010 6
Antimuny (Sb) < 1.5 1.5 6010 6
Arsenic (As) <2 2 6010 6
Bariurn (Ba) 103 0.1 6010 6
Berypium (Be) 1.59 0.1 6010 6
Cadmium (Ctl) 2.41 0.15 6010 6
Calcium (Ca) 199300 500 6010 6
Chromium (Cr) 2.96 0.25 6010 6
Cobalt (Co) 6.78 1 6010 6
Copper (Cu) 32.6 0.2 6010 6
Iron (Fe) 29340 250 6010 6
Lead (Pb) < 1.5 1.5 0010 6
Magneslum (Mg) 20840 1000 5010 6
Manganese (Mn) 607 100 6010 6
Niclte: (Ni) 3_17 0.5 6010 6
Selenium (Se) <2.5 2.5 6010 6
Silver (Ag) <0.5 0.5 6010 6
Zinc (Zn) 227 0.1 6010 6
Mercury (Hg) < 0.1 0.1 7471
The next table illustrates the remaining heavv metals in the soil after it was
treated with the process
solution as described above
Table 3.0 Illustrating Treated Soils and Remaining Heavy Metals
Base Solid
Lab 199525 Result MDL MetltQa' Dcue
Metals Scan
Alumirrtrm (Al) 4238 mc}mg 2000 6010 61121r07
Antlmony (Sb) < 1.5 mg/Kg 1.5 6010 6'21/07
Arsenic (As) <2 mg/Kg 2 6010 6,21i07
Barium (Ba) 68.3 mg/Kg 0.1 6010 6,12 1107
Beryllirart (Be) 1.1 mg/Kg 0.1 6010 6121:07
Cadmium (Ccg 1.28 mg/Kg 0.15 60'0 W21.107
Calcium (Ca) 91100 mglKg 500 6010 6!21707
Chromium (Cr) 2.03 mg/Kg 0.25 6010 6/21:07
Cobalt(Co) 4.49 mg/Kg 1 6010 6l21l07
Copper (Cu1 21.9 mgJKg 0.2 6010 642 V07
tron 16400 mg/Kg 250 6010 6/21107
Lead < 1.5 mg/Kg 1.5 6010 6121/07
Magnesium (Mg) < 1 mglKg 1 6010 6/21/07
Manganese (Mn) 256.3 mgrKg 100 6010 5/21/07
Nidcel (Ni) 2.1 mglKg 0.5 6010 6121/07
Selenium (Se) <2.5 mgACg 2.5 6010 612907
Silver (Ag) <0.5 mg'Kg 0.5 6010 6121/07
Zinc <0.1 rng'Kg 0.1 6010 6i21107
Mercury (Hg) < 0,1 mg(Kg 0.1 7471
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Table 4.0 Represerlts the Treated llecante.red Wast.evc'ater ( i.e. 1%
Diso(liumsulfosuccinate (DOSS))
Ec:oSzfe Envit'onmenral
Decant Water Mansurf Liauid
Lcrb Reporr 199523 Result IVIDL Method Dp:e TErne Anal
hletals 5can
Aluminum (Al) 2.3.7 ^~gfKg 2 6010 6/21107 13:25 IFH
Antimany(&b) 7.56 mglKg 1.5 6010 612110"7 13: :5 IF~i
Arsenic (AS) <2 mg!Kg 2 6010 6/21-711 13:25 IFH
Barium (Ba) 2.: mgrK.g 0.1 6310 6!2110",' 1.125 1FH
Beryllium (Be) <0.1 mgrKg 0.1 6010 W216i, 13:25 FH
Cadmium (Cd) 0.363 nig(Kg 0.15 6010 GP2 1!07 1325 FH
Calcium (Ca) 1106 mg!Kg S00 601ci 6121!07 14:47 tFH
Chromlum (Cr) <0.25 mg'Kg 0.25 6010 6J2!10? 13:25 FH
Coball (Co) <1 mg/Kg 1 6010 W21r07 13:25 IFH
Copper iCu) 0.216 mgrKg 0.2 6010 6/21/Q7 13:--, ti F'ri
Iron (Foi 65 1 myVKg 0.25 9)10 (il21h)7 -13:25 IFH
Lead (P5) < 1.5 rng'Kg 1.5 6010 621hTI 13.35 1FH
Magnesium (Mg) 60.7 mglKg 1 6010 6/?Ih37 13:25 IFH
tvlanganese (Mn) 7.8 mgXg 0.1 6010 6211-J? 13:25 'IFH
Nickel (Ni) <0.5 mghCg 0.5 601C 621I07 13:25 IFH
Seienium (Se) Q5 mg/Kg 2,5 601C6I31!D7 13:25 !FH
Silver (Ag) <0.5 mg/Kg 0.5 6010 6G'.V07 13:25 FH
Zinc (Zn) 53 mglKg 0.1 6010 6/21U07 13:25 FH
m;,rKg
Metal removat H'as accornplished in 2 minutes whercby the contents were
agitated for ' 2 minutes at high
shear and the water was decantered off and collected in a 250171I gIass
measuring flask. The extraction
and recovery of the heavy metals procedure was accotnplished in two-step
process_ Further, more
efficient extraction procedures are continued to be investigated. The common
practice in the art of
extraction technology is to employ a centrifuge. The heavy metals remaining in
the " treated wastewater
stream can be polished using a resin filtration system.
Heavy metal leaching potential af the treated solids was determined by the
U.S. -EPA toxicity test
method 1320A and Toxicity Characteristics Leaching Process Procedure i47ethod
1311.
Long term stability was tested using the agency's multiple extraction
procedure tnethod 1320
