METHOD OF EXTRACTING OIL-FREE PARAFFINS BY CRYSTALLISATION USING SELECTIVE SOLVENTS Russian patent published in 2014 - IPC C10G73/06 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved method of extracting oil-free paraffins by crystallisation using selective solvents, which involves mixing the material with a solvent, cooling the obtained mixture and crystallisation thereof. Before mixing the solvent and the material, the solvent is filtered in a precoat filter through a layer of a neutralising agent - calcium hydroxide, wherein the washed layer is formed by repeatedly passing through the filter a suspension of dry solvent and calcium hydroxide taken in a ratio which enables to form such a layer with sufficient activity of the neutralising agent. The washed layer is replaced if the difference in pH of an aqueous extract of the solvent at the input and at the output of the neutraliser-filter is less than 0.3.

EFFECT: method reduces corrosive and erosive wear of equipment, reduces content of mechanical impurities in the product, prolongs the service life of a hydrofining catalyst.

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