Methods of and apparatus for recovering a constituent of a process effluent

A method of recovering germanium from the gaseous effluent of a lightguide fiber preform manufacturing process which involves the reaction of silicon and germanium compositions with oxygen in the substantial absence of a source of hydrogen, said method including the steps of:

• treating the process effluent with an aqueous medium to dissolve and react gaseous germanium entities from the effluent in the aqueous medium, and to provide a recirculating mixture which comprises particulates and a solvent solution comprising the aqueous medium and the reacted gaseous germanium entities;
• flowing the mixture into a first filter which provides a filtrate that is substantially free of particulates larger than a first size and a residue;
• flowing the residue from the first filter to a second filter which is effective to provide a filtate which is free of particulates larger than a second size that is smaller than the first size and a residue;
• recirculating the residue from the second filter through the second filter;
• contacting subsequent process effluent from the preform manufacturing process with the filtrates from the first and second filters;
• and
• withdrawing portions of the residue from the second filter when the germanium concentration of the mixture is at least a predetermined level.

An apparatus for recovering a material from a process effluent such that a constituent of the material has at least a predetermined concentration, said apparatus comprising:

• treating means for contacting the effluent with a liquid medium to provide a recirculating mixture which includes the liquid medium and particulates with at least the particulates including the constituent to be recovered;
• first filter means connected to said treating means for removing from the mixture particulates above a first size to provide a filtrate which is substantially free of particulates larger than the first size and a residue;
• second filter means connected to said first filter means for removing from the residue from said first filter means particulates above a second size that is smaller than the first size to provide a filtrate which is free of particulates larger than the second size and a residue which is recirculated through said second filter means;
• means for directing the filtrates from said first and second filter means to said treating means to contact process effluent which is flowed into said treating means;
• and
• means rendered effective when the concentration of the constituent to be recovered is at a predetermined level for withdrawing a portion of the residue from said second filter means.

An apparatus for recovering germanium from the gaseous effluent of a lightguide fiber preform manufacturing process which involves the reaction of silicon and germanium compositions with oxygen in the substantial absence of a source of hydrogen, said apparatus including:

• scrubbing means for subjecting the effluent to an aqueous medium to dissolve gaseous germanium entities from the effluent in the aqueous medium, and to provide a recirculating mixture comprising particulates and a solvent solution comprising the dissolved, reacted gaseous germanium entities;
• first filter means connected to said scrubbing means for removing particulates larger than a first size from the recirculating mixture to provide a filtrate which is substantially free of particulates larger than the first size and a residue;
• second filter means connected to said first filter means for removing particulates larger than a second size that is smaller than the first size from the residue from said first filter means to provide a filtrate which is free of particulates larger than the second size and a residue;
• recirculating means for causing the residue from said second filter means to be reflowed therethrough;
• means for moving the filtrates to said scrubbing means to contact subsequent process effluent;
• and
• means rendered effective when the concentration of the germanium is at a predetermined level for withdrawing a portion of the residue from said second filter means.