Waste disposal

Compositions: coating or plastic – Coating or plastic compositions – Inorganic settable ingredient containing

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Details

106802, 106900, 502 60, 502 62, 502100, 502150, 501155, C04B 700, C04B 1802, B09B 300

Patent

active

051435500

DESCRIPTION:

BRIEF SUMMARY
The present invention is concerned with a method of waste disposal, and by-products thereof.
Heavy oil from storage tank bottoms and from other hydrocarbon processing operations often contains a high proportion of solid sediment, and poses a particularly severe waste disposal problem. This is particularly so with sedimentation residue from a hydrocracker or the like, which generally contains a very substantial proportion of catalyst. The waste material cannot be used for landfill because of the likelihood of leaching of toxic materials therefrom. Conventionally, such material (referred to herein as hydrocarbon sludge) has been disposed of by physically removing it from the tank, and then incinerating it.
A recently suggested process involves thoroughly mixing the hydrocarbon sludge with a hydrophobically treated calcareous additive (such as lime), and then compacting the resulting powdery mixture. While this process is believed to work reasonably satisfactorily, the cost of the hydrophobically treated lime is by no means negligible, and makes a significant contribution to the overall cost of the process.
Silica-alumina based catalyst fines (for example, from catalytic cracking plants) are themselves waste materials which are difficult to dispose of, because such materials tend to become airborne.
I have now devised a method which enables such catalyst fines and hydrocarbon sludge to be disposed of concurrently, which method also produces a product which is useful in its own right.
According to a first aspect of the invention, therefore, there is provided a method of disposal of hydrocarbon sludge, which comprises mixing said sludge with spent silica-alumina catalyst particulate fines, of particle size not exceeding 50 micrometers, so as to form friable aggregates of the particulate fines in which the individual particles are bound together by said sludge.
The hydrocarbon sludge and particulate fines are generally mixed together in an amount of 1.25 to 1.75 parts by weight of the particulate fines per part by weight of the hydrocarbon sludge. This ratio may be varied depending on the quantity of solid material in the hydrocarbon sludge; typically the sludge contains liquid hydrocarbon oil in an amount of 5 to 50% by weight (such as about 30% by weight). It is sometimes advantageous to pretreat the hydrocarbon sludge to remove some of the solids content prior to mixing with the silica-alumina catalyst fines.
The hydrocarbon sludge itself is generally derived from petroleum crude oil; the composition of the oil present in the sludge may resemble crude oil or derived hydrocarbon products having a boiling range at least as high as kerosene/diesel fuels.
The hydrocarbon sludge is preferably the sedimentation residue from a hydrocracker or the like; the heavier sedimented fraction of this material generally contains a substantial proportion of entrained solid catalyst from the hydrocracker, as outlined above.
The silica-alumina fines generally contain a preponderance of silica (such as about 70 to 90% by weight of silica). Such fines, which can be extracted from flues used in catalytic cracking towers, generally have a particle size of up to 5 micrometers.
The catalyst fines provide a large surface area suitable for adsorbing and binding the oil phase (which is generally bonded to the surface of the particles by physical forces such as Van der Waals forces). The resulting mixture is hydrophobic and granular, in which the majority of the individual particles are encapsulated, and bonded together, by the oil phase. The mixture is generally suitable for road making; alternatively it can be disposed of safely (having essentially no fines which would be likely to cause airborne contamination) in landfill or the like, and being resistant to leaching by water.
The present invention further comprises a granular formulation which coprises silica-alumina particles bonded together by means of hydrocarbon sludge.
The method of mixing of the particulate fines and the hydrocarbon sludge is not critical; the ingredients may be

REFERENCES:
patent: 4028130 (1977-06-01), Webster
patent: 4385121 (1983-05-01), Knowlton
patent: 5032548 (1991-07-01), Lowe

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