Patent GB-849760-A (GB)
Title: Extraction by the double solvent method
IPC: C10G21/02
Filed: 1958-05-13
Abstract: <PICT:0849760/IV(b)/1> The separation of a homogeneous mixture of two liquid components (M) with two solvents (S1 and S2) is carried out in two vertically disposed extraction zones Z1 and Z2, the denser solvent, S1 being introduced to the top of Z1 and the lighter solvent S2 to the bottom of Z2.  The bottom product of Z1 and the top product of Z2 are mixed with the mixture M to give a non-homogeneous mixture which is decanted by gravity and separated into a light phase and a heavy phase.  The light phase is fed to the bottom of Z1 and the heavy phase to the top of Z2, the flows thereof being controlled in response to the pressure and variations in the separation level in the decanting stage respectively.  One component of M plus S2 is recovered from the top of Z1 and the other component plus S1 from the bottom of Z2.  In the Figure Z1 and Z2 are indicated by reference numerals 1 and 2 respectively, S1 is supplied via line 9, S2 via line 14 and M via line 16.  The bottom product of Z1 from line 20, the top product of Z2 from line 21 and M from line 16 are mixed in mixer 15 and decanted in separator 23 from which the light phase is fed to Z1 via line 31 and the heavy phase to Z2 via line 27. The process is applicable to the separation of mixtures of acetone with acetic acid, using chloroform and water as solvents, and of ortho and para chloronitrobenzenes, using heptane and methane as solvents.  It may also be used to separate the constituents of mineral oils, e.g. into paraffin and non-paraffin hydrocarbons, (see Group III).ALSO:<PICT:0849760/III/1> The separation of a homogeneous mixture of two liquid components (M) with two solvents (S1 and S2) is carried out in two vertically disposed extraction zones (Z1 and Z2), the denser solvent S1 being introduced to the top of Z1 and the lighter solvent S2 to the bottom of Z2.  The bottom product of Z1 and the top product of Z2 are mixed with M to give a non-homogeneous mixture which is separated in a decanting stage into a light and a heavy stage. The light phase is fed to the bottom of Z1, its flow being controlled in response to its pressure while the heavy phase is fed to the top of Z2, its flow being controlled in response to variations in the separation level in the decanting stage. One component of M plus S2 is recovered from the top of Z1 and the other component plus S1 from the bottom of Z2.  In the drawing Z1 and Z2 are indicated by references 1 and 2 respectively, S1 is supplied via line 9, S2 via line 14 and M via line 16.  The bottom product of Z1 from line 20, the top product of Z2 from line 21 and M are mixed in mixer 15 and decanted in separator 23 whence the light phase is fed to Z1 via line 31 and the heavy phase to Z2 via line 27.  The process may be used to separate the constituents of mineral oils, e.g. into paraffins and non-paraffins as in the preparation of a paraffinic lubricating oil.  Non-paraffin solvents mentioned are phenol, cresols, furfural, sulphurous acid, nitrobenzol and aniline.  The process is described with reference to the treatment of crude mineral oil with liquid propane and a phenol-cresol mixture.  The process may also be applied to the separation of mixtures of other organic compounds (see Group IV(b)).