Abstract: A process is provided for the manufacture of titanium dioxide pigment wherein excess ilmenite ore is reacted with dilute sulfuric acid having a concentration of between about 25% and about 60% by weight and in preferably at least two stages wherein the first stage is maintained at a temperature up to about 140.degree. C. and the second stage is conducted at a lower temperature (than the first stage) which is below about 100.degree. C. to provide a salt solution of titanium and iron. Thereafter, the titanium is hydrolyzed to provide titanium dioxide hydrate accompanied by recycling the spent acid from the hydrolysis for reaction with the ilmenite ore charged to the process. The titanium hydrate is calcined to provide titanium dioxide pigment.

Abstract: A process is provided for the manufacture of titanium dioxide pigment wherein excess ilmenite ore is reacted with dilute sulfuric acid having a concentration of between about 25% and about 60% by weight in the presence of an iron reductant, and in preferably at least two stages wherein the first stage is maintained at a temperature up to about 140.degree. C. and the second stage is conducted at a lower temperature (than the first stage) which is below about 100.degree. C. to provide a salt solution of titanium and iron. Thereafter, the titanium is hydrolyzed to provide titanium dioxide hydrate accompanied by recycling the spent acid from the hydrolysis for reaction with the ilmenite ore charged to the process. The titanium hydrate is calcined to provide titanium dioxide pigment.

Abstract: A hollow fiber separatory device is provided wherein a polyurethane prepolymer is cross-linked or cured with an ester of a polyhydric alcohol which contains two or three hydroxyl groups, e.g., propylene glycol monoricinoleate, and an aliphatic acid of at least 12 carbon atoms and one or more epoxy and/or hydroxy groups per molecule.