Freeport-mcmoran Corporation

Freeport-mcmoran Sulphur LLC

Robin W Strickland

Jay Charles Smith

Thomas H McCord

A sulfur purification process is provided. Ash-containing molten sulfur is fed to a centrifuge and subjected to centrifugation under controlled conditions at G forces at least about 4,000 times that of gravity. The centrifugation generates a purified sulfur product and a high-solids sulfur waste stream. A solid bowl disc centrifuge provided with conical discs is used to effect the centrifugal separation of solids from liquids at G forces of at least about 4,000. The centrifuge and related piping system are equipped with heating means so as to maintain the temperature of the sulfur above about 250&deg; F. If large volumes of sulfur are to be treated, e.g., 40 or more long tons per hour, a pretreatment step, where the molten sulfur is first subjected to centrifugation at G forces at least about 4,000 times that of gravity in one or more nozzle bowl centrifuges, is added in order to obtain satisfactory results. In another aspect of the sulfur purification process, the nozzle bowl centrifuge underflow waste stream is further processed in a cyclone-thickener arrangement to obtain a high-solids sulfur waste stream and a moderate-solids sulfur stream which is then mixed with the low-solids sulfur product stream from the nozzle bowl centrifuge(s), or recycled to the feed of the nozzle bowl centrifuge(s).

Purification of sulfur by means of centrifugation

A process and apparatus for removing SO.sub.2 from low-volume gas streams containing high concentrations of SO.sub.2 includes a tank scrubber containing an aqueous SO.sub.2 absorbent and an impeller. The tank scrubber has an unpartitioned vessel. The impeller includes a vertical rotating shaft having an upper and lower impeller. The lower impeller serves to agitate the SO.sub.2 absorbent. The upper impeller includes a shroud thereby directing the absorbent and gas outwardly toward the wall of the scrubber. The gas is injected into the absorbent at a point below the shrouded impeller. The shroud prevents gas bypass and thereby promotes gas-liquid mixing and, consequently, markedly improves SO.sub.2 removal efficiency.

Method and apparatus for removing sulfur dioxide from gas streams

A process and apparatus for removing SO.sub.2 from low-volume gas streams containing high concentrations of SO.sub.2 includes a tank scrubber containing an aqueous SO.sub.2 absorbent and an impeller. The impeller includes a vertical rotating shaft having an upper and lower impeller. The lower impeller serves to agitate the SO.sub.2 absorbent. The upper impeller includes a shroud thereby directing the absorbent and gas outwardly toward the wall of the scrubber. The gas is injected into the absorbent at a point below the shrouded impeller. The shroud prevents gas bypass and thereby promotes gas-liquid mixing and, consequently, markedly improves SO.sub.2 removal efficiency.

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New Orleans, LA, United States of America

Robin W Strickland