Athens Corporation

Ipec Clean, Inc.

Christopher S Blatt

John Andrew Adams

Gerald A Krulik

David W Persichini

Susan M Jordan

Robert T Shinagawa

Dieter Dornisch

A method for the removal and purification of substantially all of the fluoride ions contained in a solution containing greater than 10 parts per million (ppm) fluoride ion, a mixture of other anions, silicon in the form of a fluorosilicic acid, silicic acid, silicates, or silicon tetrafluoride, and optionally also containing complex metal fluorides, to produce an ultrapure hydrofluoric acid, comprising the steps of (a) adjusting the pH of the solution to an alkaline pH to hydrolyze the fluorosilicic acid and any complex metal fluorides; (b) removing the fluoride ions and other anions from the solution by passing the solution through an ion exchange resin, where the ion exchange resin is adapted to adsorb substantially all of the fluoride passed over the ion exchange resin; (c) displacing the fluoride ions and other anions bound to the ion exchange resin, thereby forming a mixture of anions in an effluent emanating from resin; (d) optionally concentrating the effluent at a high pH and then lowering the pH; and (e) distilling the mixture of anions in the effluent from a sulfuric acid solution to generate ultrapure hydrofluoric acid. An apparatus useful for practicing the method is also disclosed.

Separation and purification of fluoride from industrial wastes

A method for the on-site reprocessing of isopropyl alcohol used in semiconductor manufacturing, to generate an ultradry and ultrapure isopropyl alcohol. This ultradry and ultrapure isopropyl alcohol is produced through a pervaporation step, followed by double distillation. In the first distillation step, an autonomous azeotropic self-stripping distillation column is used to produce an ultradry and partially purified isopropyl alcohol. In the next step, the isopropyl alcohol is distilled in an overhead product distillation column, to produce an ultrapure and ultradry isopropyl alcohol. Alternatively, if the feed isopropyl alcohol contains less than 2000 ppm water, the pervaporation step may be omitted. The resulting isopropyl alcohol has between a high of 100 parts per million (ppm) and a low of 0.1 ppm of water in the isopropyl alcohol. It also has zero particles per milliliter of a size larger than 2.0 microns, zero to 2 particles per milliliter of a size of 0.5 micron to 2.0 microns, zero to 30 particles per milliliter of a size between 0.1 microns and 0.5 microns, an unspecified number of particles per milliliter below 0.1 microns, 1 part per trillion (ppt) to 1 part per billion (ppb) of any specific trace impurity such as metals, anions, and cations, and 10 ppt to 10 ppm of any other specific trace organic substances.

Dehydration and purification of isopropyl alcohol to an ultradry and

A high efficiency batch sulfuric acid reprocessor system that is capable of producing high purity acid through distillation. Methods of use are also provided. The distillation is monitored and controlled in accordance with temperatures of the system, in particular, the temperature of the column and the temperature of the vapor in a condensing chamber. A stream splitter enables the invention to selectively collect high purity product as well as remove waste or recycle condensate as reflux.

High efficiency chemical processing

Growing community of inventors

La Costa, CA, United States of America

Christopher S Blatt