Process for scrubbing a crude mixture which is obtained in the nitration of toluene after separating off the nitrating acid and comprises dinitrotoluene, nitric acid, nitrogen oxides and sulfuric acid, which comprises two scrubbing steps (WS-I) and (WS-II), wherein i) in a first scrubbing step (WS-I), the crude mixture is extracted with a scrubbing acid I comprising nitric acid, nitrogen oxides and sulfuric acid in a scrub comprising at least one extraction stage, where the scrubbing acid discharged from the first extraction stage (WS-I-1) of the first scrubbing step (WS-I) has a total acid content of from 10 to 40% by weight and a content of from 80 to 350 ppm of hydrocyanic acid, giving a prescrubbed crude mixture, ii) in a second scrubbing step (WS-II), the prescrubbed crude mixture comprising dinitrotoluene is extracted with a scrubbing acid II in a scrub comprising at least one, preferably at least 2, extraction stage(s), where the scrubbing acid discharged from the first extraction stage (WS-II-1) of the second scrubbing step (WS-II) has a pH of less than or equal to 4, giving a dinitrotoluene-comprising mixture which is essentially free of nitric acid, sulfuric acid, nitrogen oxides and hydrocyanic acid and has a content of not more than 300 ppm of nitric acid and nitrogen oxides, not more than 3 ppm of sulfate and not more than 50 ppm of hydrocyanic acid.

A technique for purifying solid materials containing contaminants, such as petroleum coke, may involve introducing the contaminated solid material into an extractor vessel along with an organic solvent. The contaminated solid material and organic solvent may be conveyed in a countercurrent direction during which the contaminant is extracted at least partially out of the solid material and into the solvent. After extraction, the resulting extracted solid material can be processed in a desolventizing unit and the recovered solvent sent back to the extractor. Further, the solvent containing extracted contaminant can be processed in a solvent recovery unit, further recovering solvent that can be sent back to the extractor.

Disclosed herein are methods for recovering diphosphonite-containing compounds from mixtures comprising organic mononitriles and organic dinitriles, using multistage countercurrent liquid-liquid extraction. Recovery is enhanced with one or more method steps. In a first step, a portion of the heavy phase from the settling section of the first stage is recycled to the settling section of the first stage. In a second step, a portion of the light phase from the settling section of the first stage is recycled to the mixing section of the first stage. In a third step, the first stage takes place in a mixer-settler, a Lewis base is introduced into the settling section of the first stage, and a complex of Lewis acid and Lewis base is formed in this settling section. In a fourth step, a polyamine is added to the first stage.

The present invention provides an annular centrifugal contactor, having a housing adapted to receive a plurality of flowing liquids; a rotor on the interior of the housing; an annular mixing zone, wherein the annular mixing zone has a plurality of fluid retention reservoirs with ingress apertures near the bottom of the annular mixing zone and egress apertures located above the ingress apertures of the annular mixing zone; and an adjustable vane plate stem, wherein the stem can be raised to restrict the flow of a liquid into the rotor or lowered to increase the flow of the liquid into the rotor.

Liquid-liquid extraction column (1) comprising injection points for feedstock (2), for washing (3) and for backwashing (4), two withdrawal points (5, 6), trays (P.sub.i) located along the column and defining 2 to 30 zones each comprising at least two trays, the n zones comprising: at least one extraction zone Z.sub.i comprising the zones from Z.sub.1 to Z.sub.x, x being greater than or equal to 1, and at least one backwash zone comprising the zones from Z.sub.x+1 to Z.sub.n, n being greater than x; in which the trays of one and the same zone exhibit one and the same height H of inter-tray space (10); in which, when x>1, the height H of the zones Z.sub.i increases when i increases; and, when x=1, the height H of the at least one backwash zone is less than the height H of zone Z.sub.1.

The present invention relates to an extraction column 1 having a vertically aligned column body 2 which is cylindrical at least in sections and forms a column cavity 3 having a horizontal maximum extent, with provision in the column body 2 of at least one first feed 4 for an extractant, at least one second feed 5 for the fluid to be extracted and at least one outlet 6 for the extract mixture and at least one outlet for the raffinate. In the inventive extraction column 1, a vertically aligned divider 7 arranged within the column cavity 3 subdivides the column cavity 3 into a plurality of vertically aligned and horizontally divided regions, the horizontal maximum extent of each region being less than the horizontal maximum extent of the column cavity 3. The invention further relates to a process for extracting a constituent from a fluid by means of such an extraction column 1.

The present invention relates to an extraction apparatus for extracting at least one constituent in a substance. The extraction apparatus comprises an extractor, an extraction separator and an extraction condenser. The extractor is used to mix the substance and an extraction fluid, wherein the extraction fluid is a subcritical fluid. The extraction separator is connected to the extractor for receiving and heating the extraction fluid to gasify the extraction fluid and to separate the constituent and the gasified extraction fluid. The extraction condenser is connected to the extraction separator and the extractor for receiving and liquefying the gasified extraction fluid from the extraction separator and sending the liquefied extraction fluid to the extractor.

The present invention relates to a process for obtaining food grade hexane, comprising: fractionating a hydrocarbon feed having a boiling point in the range of 50 C. to 140 C. to obtain a hydrocarbon fraction having boiling point in the range of 63 C. to 69 C. and having 3%-15% (wt/wt) of aromatic compounds content; extracting the hydrocarbon fraction by counter current solvent extraction using sulfolane as a solvent to obtain a first raffinate phase; extracting the first raffinate phase by co-current solvent extraction using sulfolane as a solvent to obtain a second raffinate phase; and washing the second raffinate phase with water to obtain a food grade hexane containing less than 100 ppm of aromatic compounds.

A bearing assembly can be used in liquid service applications where the bearing assembly is intermittently or continuously exposed to liquid, such as below the liquid level of a solid-liquid extractor. In some examples, the bearing assembly includes an annular sleeve and an annular bearing. The annular sleeve is designed to be installed over the end of a rotatable shaft and positioned inside of a housing through which the rotatable shaft at least partially protrudes. The annular sleeve has an outer surface and length parallel to the rotational axis of the rotatable shaft. The outer surface of the annular sleeve may taper radially inwardly along at least a portion of the length of the sleeve. As a result, the bearing assembly and rotatable shaft positioned therein may pivot within housing about the taper of the annular sleeve.

The present invention relates to a counter-current extraction process involving a plurality of mixing and separation stages for fractionating a phospholipid-containing feed material into two or more fractions enriched in one or more phospholipids, comprising (a) contacting the phospholipid-containing starting material under agitation with an extractant comprising an aliphatic alcohol selected from C1 to C3 alcohols; (b) separating the obtained emulsion into a phospholipid-enriched extract from a residual raffinate.