Bitumenous contaminants

Small concentrations of volatile components in a liquid mixture may accumulate in the vapor space of a container over time and appreciably reduce the flash point relative to the reported closed-cup value. This may be the result of degassing, chemical reaction or other mechanism. An example is bitumen [162]. Similarly, if a tank truck is not cleaned between deliveries of gasoline and a high flash point liquid such as kerosene or diesel oil, the mixture might generate a flammable atmosphere both in the tmck tank and the receiving tank. Contamination at the thousand ppm level may create hazards (5-1.4.3 and 5-2.5.4). Solids containing upward of about 0.2 wt% flammable solvent need to be evaluated for flammable vapor formation in containers (6-1.3.2). 

Residual products (No. 6 fuel oil, bunker C oil) these products have little (usually, no) ability to evaporate. When spilled, persistent surface and intertidal area contamination is likely with long-term contamination of the sediment. The products are very viscous to semisolid and often become less viscous when warmed. They weather (oxidize) slowly and may form tar balls that can sink in waterways (depending on product density and water density). They are highly adhesive to soil. Heavy oil, a viscous petroleum, and bitumen from tar sand deposits also come into this category of contaminant. 

Off-gas from the coke burner ( -Gas) contains nitrogen, sulphur dioxide (SO2), hydrogen sulphide (H2S), carbon monoxide (CO), carbon dioxide (CO2), water vapour and other trace contaminants. The -Gas is directed to the CO Boiler for incineration where sulphur compounds are converted to SO2. The Boiler flue gas is passed through electrostatic precipitators for particulate control and then emission to atmosphere. The CO Boiler also serves as the Sulphur Plant tail gas incinerator. Maximum sulphur emissions are 146 tonnes/day or 10.6% of sulphur contained in bitumen feed to the cokers. 

This difficulty in translating what appears to be a simple technique in a beaker to a viable continuous process contributed to the failure of many subsequent pilot plants. It was not until 1967 that the first commercial plant was put on stream, using giant bucket wheel excavators to mine the sand, the hot water process to separate the oil, centrifuging of the froth to remove solid and water contaminants, delayed coking of the bitumen to produce a sour distillate product, followed by hydrofining to produce a "synthetic crude oil. 

In the process (Figure 8-10), the preheated feedstock (which may be whole crude, atmospheric residuum, vacuum residuum, or bitumen) is injected into a stream of fluidized, hot catalyst (trade name ArtCat). Complete mixing of the feedstock with the catalyst is achieved in the contactor, which is operated within a pressure-temperature envelope to ensure selective vaporization. The vapor and the contactor effluent are quickly and efficiently separated from each other and entrained hydrocarbons are stripped from the contaminant (containing spent... 

Toluene appeared to be the best compromise from the standpoints of volatility, ease of handling, toxicity, and halogen contamination. In all subsequent work, bitumen was extracted with refluxing toluene. Typically, three successive extractions with 100 mL toluene each were used for 10 g... 

Polymer encapsulation is an ex situ S/S technique involving the application of thermoplastic resins such as bitumen, polyethylene and other polyelfins, paraffins, waxes, and sulfur-based cements, as opposed to cements and pozzolans. Polymer encapsulation has been used primarily to immobilize low-level radioactive wastes and those waste types that are difficult to immobilize in cement, such as Cl- and SO4-based salts. Bitumen (asphalt) is the least expensive and (hence) used most often. Thermoplastic encapsulation heats and mixes the contaminated soil with the resin at 130 to 230°C in an extrusion machine. Organic pollutants and water boil off during the extrusion and are collected for treatment or disposal. The final product, a stiff yet plastic resin, is then discharged into a drum or other container and land-filled (U.S. EPA, 1997). 

The common asbestos containing materials that may be found in contaminated land and brown field sites are therefore pieces of cement boarding, insulation boarding, fibrous insulation or occasionally free fibre depending upon the previous usage of the site, bitumen felt, vinyl floor tiles and gasket materials. These materials may have been mixed in with demolition rubble and soil, crushed as hardcore and utilised on site, or simply buried to raise the level of the land prior to redevelopment. 

Solid radioactive wastes are produced from many systems and purification circuits of the reactor station, see Figure 20.7. Many contaminated items can be decontaminated by proper treatment, saving both money and waste storage space. Low level waste can also sometimes be "declassified" and disposed of as normal, inactive, waste or scrap. Combustible solids may be reduced in volume through incineration. Several techniques are used for fixation of wastes in such a way that they can be safely stored with a minimum of surveillance. These techniques all have in common an enclosure of the activity in an insoluble material (normally concrete or bitumen) and in blocks of sizes and activities small enough to be handled with a fork lift. 

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