CA2226180A1 - Pre-treatment of hydrocarbons for preventing spills - Google Patents

Abstract

There is provided a process for reversibly solidifying hydrocarbons for transportation or storage to prevent spillage of the hydrocarbon. The process involves mixing the hydrocarbons with a sufficient quantity of a hydrocarbon wax, such as paraffin, whereupon cooling the resulting mixture leads to solidification into a buoyant, united mass. The minimum amount of hydrocarbon wax required to solidify the oil will depend on the type of crude oil, the type of wax being used and the temperature that the solidified mass is being maintained at during shipping. In the case of crude oil shipment by ocean tanker the crude may be pre-treated with the hydrocarbon wax in the storage compartments and the mixture transported in solid form. The solidified, united mixture effectively prevents spillage of the crude in the event of the hull being ruptured and is not displaced by sea water. The buoyant solidified mixture prevents the ship from sinking in the event of a hole being formed in the hull of the ship. Waste hydrocarbons such as contaminated PCBs are solidified using the hydrocarbon wax at much higher levels of the wax to ensure complete encapsulation of the oil. In the case of transportation of crude oil, the wax may be recovered from the crude oil by heating the mixture to liquefy it and the components separated by fractional distillation.

Description

PRE-TREATMENT OF HYDROCARBONS FOR PREVENTING SPILLS

FIELD OF THE INVENTION
The present invention relates to methods of reversibly solidifying liquid hydrocarbons for transportation or storage to prevent spillage of the hydrocarbon .

BACKGROUND OF THE INVENTION
It is well know that the transportation and storage of hydrocarbons can be a hazardous affair. Crude oil is often transported via tanker vessel or tanker truck and, on occasion, vehicles carrying oil have met some calamity which resulted in the spillage of the cargo oil. It is estimated that between 30to 40 oil tankers a year accidentally release significant amounts of crude oil into the environment. At sea, the spilled oil tends to form floating oil slicks which kill fish and fowl alike. When on land, the spilled oil has a tendency to seep into the soil and contaminate ground water. In either case, the liquid oil is difficult and expensive to remove from the site of the accident.
Various methods, both physical and chemical, have been used to contain oil spills and to facilitate oil removal from the surface of water. A
physical containment method commonly used is to encircle an oil slick with a floating boom and then scoop up the oil. Drawbacks to this method are that oil slicks tend to spread rapidly so that the slicks must be scooped up in sections and this requires considerable manpower and equipment. Obvious difficulties encountered due to high winds and rough seas will be apparent to those skilled in the art. This method is also impracticable for skills occurring far from shore.
Various chemical schemes to clean up large surface area oil spills have been proposed. Sohnius (United States Patent No. 3,607,741) discloses recovery of oil from water using cellulosic material pre-treated to render it hydrophobic to provide it with an affinity for oil. In one embodiment the cellulosic material is contained in a mesh netting to be placed on the surface of the oil. In another embodiment the cellulosic material is contained on the surface of a cylinder which rolls under wind power across an oil slick confined SUE~STI~UTE SH~ET

by a boom and entrains oil this way. Disadvantages of this method are the need for iarge numbers of booms and cylinders for cleaning up large slicks. The recovery of oil from the cellulosic material would be both time consuming and expensive.
Alquist (United States Patent No. 3,785,972) teaches cleaning up oil slicks by spraying a way onto the surface of the oil slick in order to increase the liquefaction temperature of the oil above the temperature of the water thereby forming a solid mass which can be scooped up. Wax/hydrocarbon mixtures are also sprayed onto the oil slick and then ignited to burn off the lighter hydrocarbons in the crude thereby forming a hardened, asphalt-like material which is then scooped up. Bartha (United States Patent No.5,112,495) discloses spraying molten hydrocarbon wax onto the surface of an oil slick whereupon cooling the wax coated slick forms a solid mass which may then be physically scooped up.
Weinberg (United States Patent No. 3,756,948) is directed to a method and means for absorbing crude oil for recovery and transportation using polystyrene crumbs. This patent is directed to a method of physically absorbing oil which is quite different from gelling or solidifying the oil. Weinberg affects recovery of the oil from the polystyrene by dissolution of the polystyrene by either chemical solvents or heat.
Drawbacks to these various schemes are that the application of the containment agent to the spilled oil can be costly and time consuming, and spills often occur in remote locations difficult to reach in a short time. Largeamounts of wax must be transported to the spill site, heated to the liquid form and then sprayed over the entire surface of the oil slick thus requiring specialized ships and equipment. Further, to transport the large volume of solidmixture from the spill site will require large tanker ships specially adapted with the handling and loading facilities needed to scoop up and store the solid mass.In orderto minimize the chance of an oil spill, emphasis has been placed in the building of safer and stronger transportation vessels. The development of the double hulled oil tanker is an example of one such vessel.
These vessels, while decreasing the chance of an oil spill by decreasing the ~B~ 3TE S~T

likelihood that the compartment or container holding the oil will be ruptured, tend to be very expensive. Furthermore, no vessel is completely safe from disaster and it is possible that a sufficiently violent calamity may result in the rupture of event the strongest vessel.
The economic costs associated with bulk shipping of crude oil has increased steadily with the higherfrequency of marine disasters in recent years.The insurance costs alone associated with underwriting oceanic transport of crude oil are in the tens of millions of dollars at least. It is therefore desirable to provide a method of pre-treating hydrocarbons prior to shipping which will significantly reduce the chances of oil slicks forming in the event of a mishap.In a related matter, the storage of waste oil and hazardous hydrocarbon compounds such as PCBs (polychlorinated biphenyls), is also problematic. Usually the hydrocarbon is placed in a steel drum or barrel and then stored in a waste storage facility or buried underground. The drums used to store the hydrocarbon sometimes develop defects as a result of corrosion or as a result of an impact. These defects may result in the release of the hazardous compound causing soil and ground water contamination. The leaked hydrocarbon is difficult to clean up, often requiring the soil to be dug up and removed. Efforts have been made to strengthen the storage drums in order to lessen the probability of a leak. These superior drums tend to be expensive.
Another approach in the storage of waste oil and hazardous hydrocarbon compounds is to render the material solid. In the solid state, the consequences of a leak are less serious. The spilled hydrocarbon is easier to collect if it is in a solid state, and the solidified hydrocarbon is less likely to leach into the soil or contaminate the ground water. To solidify the hydrocarbon, a solidifying agent is added in sufficient concentration to render the mixture asolid or semi-solid mass. The solidifying agents normally used to be expensive, and the solidifying process is often difficult or expensive to reverse.
Weitzen (U.S. Patent No. 4,341,078) discloses the solidification of PCBs by the addition of a slurry of cryogenically comminuted polymer particles suspended in a cryogenic liquid such as liquid nitrogen. It can be appreciated that the solidifying agent used in Weitzen is expensive and requires 5~B~T~TE

specialized equipment to handle. The solid resulting from the Weitzen method is difficult to liquefy, requiring ionizing radiation or conditions of high shear.
Derby (U.S. Patent No. 3,881,295) discloses the solidification of PCBs by the addition of swellable polymer particles. The polymer particles imbibe the PCBs and swell to form a thick gel. Derby does not disclose a method of reversing the solidification of the PCB mixture. The reversibility of the solidification step is desirable to ease the disposal of the hazardous material by incineration.
Conner (United States Patent No. 4,518,507) is directed to a method of chemically solidifying and encapsulating hazardous waste by solidifying the waste and encapsulating it in a membrane such as polyethylene.

SUMMARY OF THE INVENTION
The present invention provides a method of pre-treating hydrocarbons fortransportation or storage. The method comprises the steps of mixing the hydrocarbon with a hydrocarbon wax in a contained volume to form a mixture while maintaining the mixture above a solidification temperature rangein which the mixture will solidify. The hydrocarbon wax is present in an amount effective to substantially solidify the mixture when the temperature of the mixture drops below the solidification temperature range to thereby substantially solidify the mixture forming a hardened mass. The solidified mixture liquefies upon heating to a temperature above the solidification temperature range.
In another aspect of the invention there is provided a method of pre-treating hydrocarbons for transportation in a vessel. The method comprises the steps of mixing the hydrocarbon with a hydrocarbon wax to form a mixture and storing the mixture in a contained volume in the vessel while maintaining the mixture above a solidification temperature range in which the mixture will solidify. The hydrocarbon wax is present in an amount effective to substantiallysolidify the mixture when the temperature of the mixture drops below the solidification temperature range to thereby substantially solidify the mixture and heating the mixture to a temperature above the solidification temperature range liquefies the mixture. Transporting the solidified mass in the vessel to a destination and recovering the hydrocarbon wax from the oil.

Sl~ ~T~U~E SH~

The present invention also provides method of encapsulati~g a hydrocarbon liquid for storage comprising the steps of mixing the hydrocarbon liquid with paraffin wax and forming a mixture. The paraffin wax is present in an amount effective to solidify the mixture when the temperature of the mixture drops below a solidification temperature range, the solidified mixture forming a substantially solidified mass.

BRIEF DESCRIPTION OF THE DRAWINGS
The process of the present invention will now be described, by example only, reference being had to the drawings, in which:
Figure 1 is a plot of % solidification versus % paraffin wax for various oil/paraffin mixtures and oil/paraffin/water mixtures at 25~C;
Figure 2 is a plot of % solidification versus % parafffin wax for various oil/paraffin mixtures and oil/paraffin/water mixtures at 20~C;
Figure 3 is a plot of % solidification versus % paraffin wax for various oil/paraffin mixtures and oil/parafffin/water mixtures at 15~C;
Figure 4 is a plot of % solidification versus % parafffin wax for various oil/parafffin mixtures and oil/paraffin/water mixtures at 10~C;
Figure 5 is a plot of % solidification versus % parafffin wax for various oil/paraffin mixtures and oil/paraffin/water mixtures at 4~C;
Figure 6 is a plot of % solidification versus % paraffin wax for various oil/paraffin mixtures and oil/paraffin/water mixtures at 0~C;
Figure 7 is a plot showing the effect of temperature on the solidification of an oil/paraffin wax mixture and oil/paraffin wax/water mixtures with 9% paraffin wax;
Figure 8 is a plot of % solidification versus time in a mixture of crude oil and 9% paraffin wax at 20~C;
Figure 9 is a plot of viscosity versus % paraffin wax for different ~ mixtures of crude oii/paraffin wax at 20~C;
Figure 10 are plots of % solidification versus % paraffin wax for gasoline and diesel fuei;
Figure 11 is a perspective view of an encapsulated solidified ~BSTIT~TE ~I~E~T

mixture of hydrocarbon/hydrocarbon wax in accordance with the present invention;
Figure 1 2(a) shows the results of an infrared anaiysis of an encapsulated mixture such as that shown in Figure 11, and Figure 12(b) is an infrared analysis of PCB contaminated oils.

DETAILED DESCRIPTION OF THE INVENTION
A) Pre-treatment of Hydrocarbons for Shipping In accordance with the present invention, to reversibly solidify hydrocarbons such as crude oil for transportation the oil is first mixed with a solidifying agent. The solidifying agent is preferably a hydrocarbon wax. In oneembodiment of the process the wax is melted and mixed with the oil. Some agitation of the oil and wax may be necessary to achieve a homogeneous mixture. The mixing may occur in the transportation vessel itself, or prior to the oil entering the vessel, in which case the solution should be held at a temperature above the solidification temperature.
In this specification, the word mixture is used in the broadest sense to mean a substance containing two or more ingredients (Webster's New World Dictionary, second college edition), namely the hydrocarbon being solidified and the hydrocarbon wax used as the solidifying agent. The nature of the resulting mixture between the hydrocarbon and wax is unclear since several types of mixture are possible including a homogeneous solution in which all the wax is dissolved, a saturated solution containing the precipitatedwax, an extended gel, a colloidal suspension, or combinations thereof.
Therefore it will be understood that the word mixture is meant to cover all possibilities. Similarly, the word solidify is defined as "to become solid, firm, hard or united" so that solidification is used to describe the firm, united mixture formed when an effective amount of the hydrocarbon wax is added to the hydrocarbon. The solidified mixture referred to herein formed by mixing the effective amount of hydrocarbon wax with the liquid hydrocarbon is characterized by the mixture exhibiting a significant increase in viscosity overthe liquid hydrocarbon to prevent free flow of the mixture.

S ~ ~;TI~ S~ ~ ~

After the mixture of oil and solidifying agent are loaded into the vessel, the mixture may be cooled to a temperature below the solidification temperature of the mixture if it is desired to ship the crude oil in a solidified form. This may not require any elaborate cooling mechanisms as the solidification temperature may be close to ambient depending on the amount of hydrocarbon wax and nature of the crude oil to be more fully discussed below. If the vessel is seafaring, preferably the wax and amount thereof is chosen so the temperature of the water surrounding the vessel is sufficient to cool the mixture to the point where it solidifies. The solidified oil/wax mixture may then be safely transported. Alternatively, the mixture could remain liquefied during transport but the mixture is chosen so that if a hull breach occurs the contact of the water to the mixture results in the mixture solidifying thereby preventing egress of the mixture.
The type of wax used may affect the required wax concentration necessary to achieve the desired solidification temperature range. On the assumption that the hydrocarbon wax will exhibit some degree of solubility in the oil, the oil acts as a solute to lower the melting point of the wax so that it is expected that the higher the melting point of the wax, the lower the wax concentration required to reach a specific solidification temperature range in cases where solution formation is an important mechanism.
In one embodiment of the invention the hydrocarbon wax is paraffin wax which is both inexpensive and for all practical purposes biologically and chemically inert. The concentration of wax used in the solution generally varies between 1.0% and 15% by volume. The concentration of wax is adjusted depending on the type of crude oil being shipped and the desired solidification temperature of the solution. Viscous crude oil generally requires a lower concentration of paraffin wax as compared to light crude oil. If a higher solidification temperature is required, the concentration of the paraffin is increased. Beyond 15% paraffin by volume there is not a large increase in the solidification temperature, regardless of the grade of crude oil used. On a gallon basis, the inventor has found that effective solidification of the crude is obtained when the concentration of parafffin wax in the mixture is between about 2 SUÇ~S~UTE SH~ET

ounces to about 8 ounces per gallon depending on the type of crude oil.
Depending on the type of crude oil and the quality of the paramn wax, the solution may not have a specific solidification temperature. The solidification temperature may be a range within which the mixture undergoes the liquid to solid phase transition. Above the range, all of the mixture would be in the liquid phase, while below the range, all of the mixture would be in the solid phase. During the mixing step, the temperatures of both the paraffin wax and the oil should be above the solidiflcation temperature range for the mixture.
Paraffin wax has a melting point of approximately 55~C which will be above the solidification temperature of the mixture; therefore, it is possible to mix the paraffin with the oil if the oil is only slightly above the solidification temperature.
If the oil temperature is too low, then the paraffin may rapidly solidify upon contacting the oil and insufficient mixing of oil and paraffin occurs. Insufficient mixing of oil and wax may result in pockets of liquid oil in the transportation 1 5 vessel.
The data displayed in Figures 1 to 10 were obtained from a series of experiments to study the reversible solidification of crude oil and other hydrocarbons using paraffin wax. The crude oil chosen for these studies is known as Pennsilvania light sweet crude oil. The experiments were conducted to determine the concentrations of moiten or liquefied paraffin wax required forthe solidification of the crude oil at various temperatures.
The crude oil was mixed with various concentrations of molten or liquefled paraffin wax and left in a water bath at 60~C for 3-5 minutes in orderto completely melt the paraffin and achieve a homogeneous mixture. The mixture was then brought to the desired temperature in a water bath and incubated for 48 hours for the results experiments summarized in Figures 1-6.
The % solidiflcation was determined by measuring the soiidification point of themixture by monitoring the change in slope of the cooling curve versus time. In order to see the solidification behaviour of oil with liquefied paraffin in the presence of water, the homogeneous mixture was suspended into water which was pre-heated to the desired temperature.
The data shown in Figures 1-6 shows that paraffin wax solidifies SU~3S~lT~3TE SHE~

CA 02226l80 l997-l2-30 oil and the concentration of paraffin required for solidification is dependent upon the temperature of the oil. Further, when these experiments are carried out in the presence of water, the % paraffin wax required for the solidification of oilis substantially decreased which is demonstrated by the shift in curves towards the left in Figures 1-6.
The results plotted in Figures 1-6 indicates that solidification of oil with paraffin is a temperature dependent phenomena whereby a higher concentration of paraffin is required to cause the solidification of the mixture at higher temperatures. Solidification of oil by paraffin is optimal at 4~C whereaswhen water is mixed into the solidification process, the optimal temperature is as high as 20~C, see Figure 7 and Table 1. In other words, the solidification ofoil with paraffin in the presence of water is more favourable than in the absence of water.
Solidification of oil in paraffin is a time dependent phenomena and is also dependent upon the concentration of paraffin at a given temperature.
Figure 8 shows a time course of solidification of oil in 9% paraffin at 20~C
where the optimum solidification occurs between 30-40 hours whereas no solidification of oil was observed in the absence of paraffin.
Viscosity is a measure of the resistance to flow that a fluid produces under shear stress. In order to characterize the solidification processusing paraffin wax, the viscosity of different crude oil/paraffin wax mixtures was measured. Homogeneous mixtures of oil with various concentrations of paraffin were prepared as before and the viscosity of these mixtures was determined at 20~C using an Ostwald viscometer. Figure 9 shows that the viscosity of oil increases with the increase in concentration of paraffin. As the concentration of paraffin wax reaches beyond 7%, the viscosity rapidly increases and at around 1 5% the oil is no longer fluid. These results are in agreement with the previous finding of solidification behaviour illustrated in Figures 1 to 6.
To investigate the solidification of petroleum hydrocarbons other than crude oil with paraffin wax, gasoline and diesel fuel were selected. Both of these hydrocarbons were mixed with various concentrations of molten or liquefied paraffin to prepare homogeneous mixtures and solidification behaviour SU B Tll~UTE SH EET

was determined at 20~C. Figure 10 shows that paraffin wax in appropriate concentrations solidifies both gasoline and diesel fuel. The optimum concentration of paraffin wax required to solidify gasoline and diesel fuel is about 15% and 20% respectively.
The rate of solidification depends on the rate of cooling and the initial temperature of the mixture. It will be appreciated that large volumes of the mixture would require longer cooling periods in order to fully solidify. It is anticipated that in the example of a seafaring tanker vessel, the temperature of the surrounding sea water would be suffficiently low to cool the mixture intoa solid mass within a short period of time. Even if the cargo is not fully solidified, it is expected that the mixture will form a solidified "skin" where the mixture contacts the cold walls of the hull of the vessel, the skin surrounding an inner mass of liquid mixture. The solidified skin should hinder the flow of mixture out of the cargo hold in the event of a rupture. Any liquid which does leak through such a rupture will be in direct contact with sea water. In most latitudes travelled by ocean going oil tankers, the sea water would be suffficiently cold to solidify the escaped mixture.
The solidified mixture also has the benefit of rendering the tanker vessel safer to its crew. The firm, buoyant solidified mixture in the cargo holdof the ship will not be displaced by water in the event of a rupture so that thevessel remains buoyant even if its hull has been punctured below the water line.
The mixture may be heated in order to facilitate its removal from the cargo hold of a vessel. Once liquefied, the mixture is pumped from the ship and may be placed in a holding tank or piped directly to the refinery. The paraffin wax may be recovered from the hydrocarbon using recovery techniques such as fractional distillation known to those skilled in the art. The paraffin wax recovered from the mixture may be reused again and again as the solidifying agent for shipping oil. The recycling of parafffin may decrease the overall costof this method of oil transportation by decreasing the need to purchase additional paraffin.
The volume of oil shipped per tanker will be decreased depending S~3STITUTE SHEET

on the concentration of the wax in the solution. If the solution comprises 4%
wax by volume, then the tanker will be transporting 4% less oil per trip as a result. Allowances must be made for the volume of liquefied wax which is added to the tanker. If the liquefied wax is being pumped into the tanker along with the oil7 then the rate the oil is pumped into the tanker may be adjusted tocompensate. The higher the concentration of paraffin, the more rapidly the solidification process proceeds upon addition of the paraffin and the harder theresulting solidified mass.
The paraffin wax may be introduced into crude oil in a molten or liquefied form and mixed therewith as discussed above. Alternatively, it will beappreciated that the paraffin could be introduced into the crude oil in a solid or powder form as long as the crude oil is at a suitable temperature to melt or liquefy the paraffin. The particular method of introducing and mixing the parafffin wax with the hydrocarbon may depend on the processing conditions at the points where the transport vehicles are loaded.
It will be appreciated by those skilled in the art that other waxes may be used in addition to parafffin. For example, suitable solidifying agents include the broader low temperature melting paraffinic waxes; carnauba wax;
saturated fatty acids such as for example palmitic acid (m.p. 63~C) and stearic acid (m.p. 70~C); and ozocerite which is a naturally occurring rrlineral wax comprising a mixture of solid hydrocarbons. The preferred concentration of the particular wax is determined in part by the solubility of the wax in the particular grade of crude, the melting point of the wax and the temperature at which the mixture is being maintained during shipment.
In addition to crude oil, it will be immediately clear to those skilled in the art that other hydrocarbon liquids may be solidified in the same way using the hydrocarbon waxes as disclosed herein based on the studies summarized in Figure 10.
In another embodiment of the invention, the solidifying agent is not mixed with the oil until just prior to a calamity. The solidifying agent is kept in a liquid state in separate compartments and when the ship carrying the oil appears to be in danger of a rupture, the solidifying agent is rapidly mixed with ~;UB~iTITUT~ S~ET

the oil to form a mixture. Upon exposure to the cold ocean water, rapid solidification occurs to produce a buoyant mass thereby preventing excessive loss of crude oil. By adding the solidifier to the crude oil only when a calamity is imminent, the costs associated with recovering the solidifier in cases where a calamity does not occur is reduced.
The method pre-treating crude oil or other hydrocarbons according to the present invention is extremely advantageous over prior art methods of spill cleanup because it eliminates the need to ship containment booms and other cleanup equipment to the spill site. The hydrocarbon wax/crude oil mixture can be readily separated since the wax is natural component of crude so existing refining facilities can be used to effect separation and the hydrocarbon wax can be re-used. Similarly, solidifying the crude oil using molten hydrocarbon wax is highly advantageous over other gelling agents employing chemical reactions for the reasons given above.
B) Treatment of Contaminated Oils To encapsulate waste oil or hazardous hydrocarbons such as PCBs for storage, the hydrocarbon is first mixed with a melted hydrocarbon wax to form a mixture. The temperature of the wax and hydrocarbon is maintained at a temperature above the solidification temperature. While the mixture is in a containment vessel such as a drum it is then cooled to a temperature below the solidification temperature. The resulting solidified solid may be stored for an indefinite period of time.
Paraffin wax or other waxes having similar melting points may be used. The concentration of wax in the mixture is dependent on several variables including the type of hydrocarbon to be encapsulated. The higher the percent by weight wax present, the higher the solidification temperature of the solidified mixture.
The temperature of the hydrocarbon is maintained during the mixing stage at a temperature above the solidification temperature range. The concentrated solution may then be added to the hydrocarbon. Agitation may be required to fully mix the concentrated wax solution with the hydrocarbon.
Leachate studies were conducted to assess the efficacy of the T~T~ S ~ E ~

encapsulation method in which waste oil (PCB's) were encapsulated by paraffin wax. Table I summarizes the results for several samples B to H with sample A
being paraffin wax. The procedures followed are discussed herebelow.
Leachate Test Procedure Total PCB's: The sample (9.938 g) was extracted with 100 mL of dichloromethane using soxlet extraction procedure. Dichloromethane was exchanged with 245 m L of iso-octane. The extract was further diluted 1000 fold and analyzed using gas chromatography equipped with electron capture detector (GC/ECD), Hewlett Packard GC/ECD 5890 Series ll. The column was a DB 5 30 meters (5% Phenyl).
The leachate procedure was from Regulation 347, Revised Regulation of Ontario,1990 as amended to O. Reg.183,240,501,555/92 under Environmental Protection Act. (General-Waste Management) November 1982, pages 113-118.
Water PCB's: Water sample was extracted using dichloromethane and concentrated in iso-octane. The sample was then analyzed using GC/ECD.
Calibration factors (cf) convert the measured area for a compound into the amount present. Calibration factors are calculated during a calibrationrun using the formula:
cf component (X) = amount Standard (X)/area Standard (X) The stored calibration factors are then used in subsequent analysis runs to calculate the final results using the formula:
amount n sample (X) = area (X) in sample * cf of component (X) Typical Calculation (Sample: H):
The sample (0.500 9) of paraffin wax+PCB's-Oil is extracted for total PCB'swith 210 mL Hexane:Acetone (1:1) mixture by sonication for 12 minutes. The extract is analyzed using GC/ECD.
Standard 2.00 ng/uL
- Area of standard 2000321 Area of sample (H) 1120202 cf component (X) 9.9982X10-7 Amount in diluted sample 1.12 ng/L or 1.12 ug/uL

SU 13STITUTE St~ EET

Dilution factor 10 m L
Total PCB's in 0.50 g of sample = 1.120 x 10 - 11.20 ug Total PCB's in sample = 11.20 ug/0.50 g = 22.4 ppm TABLE I

Sample Description Total PCB's (ppm) A Paraffin Wax < 0.1 B PCB oil 32450 C 50% Solution of paraffin wax+PCB oil 13625 D 25% Solution of paraffin wax+PCB oil 7112.5 E 10% Solution of paraffin wax+PCB oil 2875.0 F 05% Solution of paraffin wax+PCB oil 1422.8 G 01% Solution of paraffin wax+PCB oil 271.5H 0.1% Solution of paraffin wax+PCB oil 22.4 Blank <0.1 The solidification temperature of the mixture is dependent on the type of hydrocarbon being encapsulated, the quality and purity of the paraffin wax, and the concentration of the paraffin wax. As in the case with oil encapsulation, the solidification temperature may not be specific and may range over a few degrees centigrade. The type of wax and the purity of the hydrocarbon all contribute to the magnitude of this range.
As with the case of crude oil solidification, the rate of solidification is dependent on the initial temperature of the mixture and the rate of cooling.
The solidification rate is not critical in this case because the mixture shall generally remain in the storage container for some time before the container is shipped.
In the event that the containment vessel is ruptured, the escape of hazardous hydrocarbon is curtailed by the solidity of the mixture. If the SU BS~T~3~E SH E~T

containers are buried or resting on the ground, the iikelihood of the hazardous hydrocarbon leaching into the soil is likewise lessened.
In one non-limiting example to solidify waste PCBs, paraffin wax is heated to between 54 to 60~C and the PCBs held at room temperature or higher. Two cups (16 oz.) of liquid natural paraffin wax are added to a container containing 14 cups (112 oz.) of PCB waste oil and the resulting homogeneous mixture is solidified to form about a gallon of solidified PCB.
In a scaled up example,6.5 to about 7 gallons of liquefied paraffin between 54 to 60~C is added to a standard drum containing about 48 gallons of waste PCB oii and the resulting mixture is stirred to form a homogeneous mass which upon cooling solidifies. Up to 50% by volume of paraffin may be used to provide substantially complete entrainment of the waste oil depending on the application.
Referring to Figure 11, there is shown generally at 10 an encapsulated mixture 11 of PCB and hydrocarbon wax according to the process disclosed herein. A neutralized layer 12 comprising paraffin encapsulates the solidified mixture 10 and an outer sealer layer 14 comprising portland cement forms a rigid, supporting outer protective layer. The infrared analysis shown inFigure 12(a) is for structure 10 of Figure 11, which was initially encapsulated in a container; the structure removed and sectioned and the analysis carried in each of the layers 12 and 14. Wavelength scan 20 was taken of an interior section of neutralizer layer 12 and scan 22 was taken of an interior section of sealer layer 14. Superimposed on Figure 12(a) is Figure 12(b) which includes a scan 24 of a PCB contaminated oil sample with the characteristic PCB peaks marked. Comparison of Figure 12(a) with Figure 12(b) shows that there were no PCBs detectable using this technique within layers 12 and 14. These results support the efficacy of the solidification process for sealing waste PCBs using paraffin as disclosed herein.
In the event that the hazardous hydrocarbon is to be disposed of permanently via incineration or the like, the solution may be liquefied by simply heating it to a temperature above the solidification temperature. The liquefied solution may then be introduced into an incinerator as is. Alternatively, if it is ~U~3S~T~E ~ T

desired to reiocate the oii into other containers the mixture is liquefied and transferred.
While the method of pre-treating hydrocarbons prior to shipping has been described with specific studies using paraffin wax, it will be appreciated by those skilled in the art that numerous variations of the process may be readily made without departing from the scope of the invention disclosed herein. For example, as mentioned7 other hydrocarbon based waxes may be used to the same effect as paraffin wax and the optimum % by volume of the wax to the hydrocarbon will be determined by the type of hydrocarbon being solidified, to the type of wax being used and those skilled in the art will be able to readily determine the optimum values in a routine way.

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Claims (13)

THEREFORE WHAT IS CLAIMED IS:

1. A method of pre-treating hydrocarbons for transportation or storage, the method comprising the steps of:
mixing the hydrocarbon with a hydrocarbon wax in a contained volume to form a mixture while maintaining the mixture above a solidification temperature range in which the mixture will solidify, the hydrocarbon wax being present in an amount effective to substantially solidify the mixture when the temperature of the mixture drops below the solidification temperature range to thereby substantially solidify the mixture, the solidified mixture liquefying upon heating to a temperature above the solidification temperature range.

2. The method according to claim 1 wherein the hydrocarbon is crude oil and the temperature of the crude oil is maintained above the solidification temperature range of the mixture while the hydrocarbon wax is being added.

3. The method according to claim 2 wherein the hydrocarbon wax has a melting point greater than about 50°C.

4. The method according to claim 3 wherein the hydrocarbon wax is paraffin wax.

5. The method according to claim 4 wherein the mixture is removed from the contained volume by heating the solidified mixture to a liquid and then pumping the liquid from the contained volume.

6. The method according to claim 5 wherein the paraffin wax is recovered from the crude oil by fractional distillation of the mixture.

7. The method according to claim 1 wherein the hydrocarbon is crude oil and the hydrocarbon wax is selected from the group consisting of paraffinic waxes, carnauba wax, palmitic acid and ozocerite.

8. The method according to claim 4 wherein the concentration of the paraffin wax in the mixture is between about 2 to about 8 oz. per gallon of crude oil.

9. The method according to claim 4 wherein the concentration of paraffin wax in the mixture is between about 1% to about 30% by volume.

10. A method of encapsulating a hydrocarbon liquid for storage comprising the steps of mixing the hydrocarbon liquid with paraffin wax and forming a mixture, the paraffin wax being effective to solidify the mixture when the temperature ofthe mixture drops below a solidification temperature range, the solidified mixture forming a substantially solidified mass.

11. The method according to claim 11 wherein the hydrocarbon liquid is a solution of polychlorinated biphenyls and the concentration of paraffin wax is about 50% by volume.

12. In a method of pre-treating hydrocarbons for transportation in a vessel, comprising the steps of:
a) mixing the hydrocarbon with a hydrocarbon wax to form a mixture and storing said mixture in a contained volume in the vessel while maintaining the mixture above a solidification temperature range in which the mixture will solidify, the hydrocarbon wax being present in an amount effective to substantially solidify the mixture when the temperature of the mixture drops below the solidification temperature range to thereby substantially solidify themixture, the solidified mixture liquefying upon heating to a temperature above the solidification temperature range;
b) transporting the mixture in the vessel to a destination; and c) recovering the hydrocarbon wax from the mixture.

13. The method according to claim 12 wherein the hydrocarbon wax is parafffin wax present in the mixture between about 1% to about 30% by volume.