Patent GB-750045-A (GB)
Title: Improvements in or relating to the treatment of a mixture of saturated, mono-unsaturated and poly-unsaturated fatty acid compounds
IPC: C11B7/00
Filed: 1954-03-03
Abstract: <PICT:0750045/IV(a)/1> A mixture of saturated, mono-unsaturated and poly-unsaturated fatty acids or their esters is separated by selective crystallization from solution in an organic solvent by first effecting a primary separation at a relatively low temperature at which the saturated and mono-unsaturated fractions crystallize to the exclusion of the poly-unsaturated fractions which remain in solution, and then effecting a secondary separation of the recovered solid phase crystals in the presence of the solvent at an increased temperature at which the saturated fraction tends to crystallize while the mono-unsaturated fraction remains in solution.  Fatty ester or fatty acid mixtures treated preferably comprise 5 to 25 per cent saturated fraction, 10 to 65 per cent mono-unsaturated fraction, and 10 to 65 per cent poly-unsaturated fraction.  Mixtures of lower saturated fraction content may be used if the concentration of this fraction is increased during the primary separation by addition from any extraneous source or by re-cycling from the secondary filter cake.  The starting material may comprise fatty acids having down to 8 carbon atoms, mixtures of mono- and di-glycerides and ordinary esters of fatty acids. The solvents exemplified comprise ketones, ketone-aromatic mixes such as acetone-benzol, nitroparaffins such as nitroethane, acetonitrile, chlorethylenes and non-polar solvents such as low boiling hydrocarbons, e.g. butane or mixtures of such solvents. The separation temperatures vary with the materials and solvents used.  In a suitable plant, a fatty acid ester mixture is fed through a pipe 10 to a mixer 11 with solvent from a pipe 12 and heated in the mixer.  The solution is chilled in a coil 15 to the primary separation temperature and then passed to a filter 16 to separate the liquid phase as filtrate which is discharged through pipe 17 and the solid phase as filter cake which is discharged into pipe 20.  The latter is passed to a secondary mixer 21 with further solvent from pipe 22 and the temperature adjusted to the secondary separation temperature.  The slurry is then passed to the secondary filter 28, the filtrate being withdrawn through pipe 32 and the solid filter cake being discharged into pipe 31.  The solvent is stripped from each fraction at 34, 39 and 43 respectively to discharge the poly-unsaturated fraction through 35, the mono-unsaturated fraction through 40 and the saturated fraction through 44.  The solvent from each is returned to a solvent header 38.ALSO:<PICT:0750045/III/1> A mixture of saturated, mono-unsaturated and poly-unsaturated fatty acids or their esters is separated by selective crystallization from solution in an organic solvent by first effecting a primary separation at a relatively low temperature at which the saturated and mono-unsaturated fractions crystallize to the exclusion of the poly-unsaturated fractions, which remain in solution, and then effecting a secondary separation of the recovered solid phase crystals in the presence of the solvent at an increased temperature at which the saturated fraction tends to crystallize while the mono-unsaturated fraction remains in solution.  Fatty mixtures treated preferably comprise 5 to 25 per cent saturated fraction, 10 to 65 per cent mono-unsaturated fraction, and 10 to 65 per cent poly-unsaturated fraction. Mixtures of lower saturated fraction content may be used if the concentration of this fraction is increased during the primary separation by addition from any extraneous source or by re-cycling from the secondary filter cake. The starting material may comprise mixtures of fatty acids, of their glycerides, of their mono-, di- and triglycerides, or of other esters of the fatty acids.  Such mixtures may be derived from soya bean oil, cottonseed oil, fish oils, peanut oil, tung oil, &c.  The solvents exemplified comprise ketones, ketone-aromatic mixes such as acetone-benzol, nitroparaffins such as nitroethane, aceto-nitrile, chlorethylenes and non-polar solvents such as low boiling hydrocarbons, e.g. butane or mixtures of such solvents.  The separation temperatures vary with the materials and solvents used; for soya bean fatty acids with acetone the temperatures are usually -30 to -50 DEG F. and 5 to 30 DEG F. respectively.  In a suitable plant, a fatty acid mixture is fed through a pipe 10 to a mixer 11 with solvent from a pipe 12 and heated in the mixer.  The solution is chilled in a coil 15 to the primary separation temperature and then passed to a filter 16 to separate the liquid phase as filtrate, which is discharged through pipe 17, and the solid phase as filter cake, which is discharged into pipe 20.  The cake is passed to a secondary mixer 21 with further solvent from pipe 22 and the temperature is adjusted to the secondary separation temperature.  The slurry is then passed to the secondary filter 28, the filtrate being withdrawn through pipe 32 and the solid filter cake being discharged into pipe 31.  The solvent is stripped from each fraction at 34, 39 and 43 respectively to discharge the poly-unsaturated fraction through 35, the mono-unsaturated fraction through 40 and the saturated fraction through 44.  The solvent from each is returned to a solvent header 38.