Patent GB-734132-A (GB)
Title: Processes for separating solid substances from mixtures thereof with oil
IPC: C10G73/06
Filed: 1952-11-28
Abstract: Solid substances are separated from a mixture thereof with oil by bringing the solid substances into contact with (a) an aqueous auxiliary liquid which has a higher dielectric constant than the oil phase and is substantially or totally immiscible with the oil phase and (b) a surface-active substance containing or consisting of an organic phosphorus compound, the contacting being effected in such a manner that an oil-in-water emulsion is temporarily p  formed, so that the angle #q between the direction of the interfacial tension g of the two liquid phases and the surface of the solid substance, under equilibrium conditions at a point where the three phases meet, as measured over the oil phase, is at least 90 degrees, whereby the oil phase separates from the solid substance or the solid substance enters the aqueous auxiliary liquid phase.  The process is applicable to the removal of solid hydrocarbons from oils (for example the separation of naphthalene from tar oil) and the removal of complex compounds of hydrocarbons with urea or thiourea (for example the crystalline complexes of urea and straight-chain hydrocarbons or of thiourea and branched-chain hydrocarbons or naphthenes) from the oil reaction medium in which they are formed.  Suitable surface-active substances (b) are alkali metal salts of dialkyl phosphates, such as those of di-3,5,5-trimethylhexyl phosphate and di-n-octyl phosphate. The mixture of solid substance and oil to be treated may be mixed with a solvent which, at the working temperature dissolves the oil but not, to any substantial extent, the solid substance.  If the solid substances are initially in solution in the oil, such solution, with or without admixture with a solvent as described above, may be cooled so that an oil or oil-solvent phase containing a solid phase is created.  In conjunction with the surface-active substance (b) there may be employed a demulsifier which prevents the formation of stable emulsions without adversely affecting the activity of the surface-active substance.  The pH of the auxiliary aqueous liquid phase (a) may be adjusted, preferably to a value higher than 7, for example by the addition of caustic alkali solution.  Specification 733,067 is referred to.ALSO:Solid substances are separated from a mixture thereof with oil by bringing the solid substance into contact with (a) an aqueous auxiliary liquid which has a higher dielectric constant than the oil phase and is substantially or totally immiscible with the oil phase and (b) a surface-active substance containing or consisting of an organic phosphorus compound, the contacting being effected in such a manner that an oil-in-water emulsion is temporarily formed, so that the angle #q between the direction of the interfacial tension g  of the two liquid phases and the surface of the solid substance, under equilibrium conditions at a point where the three phases meet, as measured over the oil phase, is at least 90 degrees, whereby the oil phase separates from the solid substance or the solid substance enters the aqueous auxiliary liquid phase.  The process is applicable to the removal of solid hydrocarbons from oils (for example the dewaxing of oil containing paraffin wax and the separation of naphthalene from tar oil) and the removal of complex compounds of hydrocarbons with urea or thiourea (for example the crystalline complexes of urea and straight-chain hydrocarbons or of thiourea and branched chain hydrocarbons or naphthenes) from the oil reaction medium in which they are formed. Suitable surface-active substances (b) are alkali metal salts of dialkyl phosphates, such as those of di-3,5,5-trimethylhexyl phosphate and di-n-octyl phosphate.  The mixture of solid substance and oil to be treated may be mixed with a solvent which, at the working temperature dissolves the oil but not, to any substantial extent, the solid substance.  If the solid substances are initially in solution in the oil, such solution, with or without admixture with a solvent as described above, may be cooled so that an oil or oil-solvent phase containing a solid phase is created.  In conjunction with the surface-active substance (b) there may be employed a demulsifier which prevents the formation of stable emulsions without adversely affecting the activity of the surface-active substance.  The pH of the auxiliary aqueous liquid phase (a) may be adjusted, preferably to a value higher than 7, for example by the addition of caustic alkali solution.  In the examples, mineral oil distillate containing solid paraffin wax, and in some cases also dichloroethane or a mixture of benzene and methyl ethyl ketone as solvent, is dewaxed according to the process of the invention by stirring with an aqueous solution of sodium di-3,5,5-trimethylhexyl phosphate or sodium di-n-octyl phosphate until the temporary oil-in-water emulsion is formed and then allowing to settle until the paraffin wax goes into the aqueous phase.  In some cases the aqueous solution to be used is made alkaline with caustic soda, or contains added ethylene glycol or a demulsifier such as sodium sulphate and/or Triton X770 (a polyethene-oxide substituted alkaryl sulphonate; the word "Triton" is a Registered Trade Mark). The treatment of the wax-containing aqueous phase to obtain paraffin waxes of varying oil content is described.  For comparison purposes, the use of sodium heptadecyl-9-sulphate instead of surface-active substance (b) is described.  Specification 733,067 is referred to.