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Peabody Process Systems, Inc.

Srini Vasan

A process is described for the treatment of waste liquor containing a mixture of alkali metal or ammonium thiocyanate and polysulfides to convert the latter to the corresponding sulfates. The waste liquor is admixed with concentrated sulfuric acid under turbulent mixing conditions and in an inert atmosphere. The treated liquor is purged of gaseous by-products using an inert gas (e.g. carbon dioxide) and the purged liquor is treated to recover sulfate therefrom.

Treatment of thiocyanate containing waste liquor

A process for steam stripping sulfur dioxide from a buffered aqueous solution in which it is absorbed in a flue gas desulfurization process is carried out at pressure greater than atmospheric. The process of pressure stripping of sulfur dioxide surprisingly results in increased steam economy as compared to stripping at atmospheric pressure and yields sulfur dioxide vapor which can be directly condensed to a liquid product with ordinary cooling water, eliminating the need for drying, refrigeration or compression operations. The high temperatures corresponding to high steam pressures enable economical use of stripping vessel overheads for preheating operations also. Stripping at pressures of 50 to 65 psig results in steam requirements which are only one-third to one-half of that at atmospheric pressure stripping. At the high pressures lower gas flow rates permit the use of more compact stripping equipment.

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New Canaan, CT, United States of America

Srini Vasan