Student Paper: Evaluating the Options: Recycling Hydrofluoric Acid

Student Paper: Evaluating the Options: Recycling Hydrofluoric Acid
Jennifer Kavanagh; University of Minnesota Duluth

A substance commonly used in the semiconductor industry because of its unique abilities to etch silica is hydrofluoric acid (HF). Hydrofluoric acid, by volume, is one of the largest Resource Conservation and Recovery Act (RCRA) regulated hazardous waste streams generated by the semiconductor industry. To find out if a method exists today to reduce the amount of HF waste being disposed, a survey was conducted of the semiconductor industry to see what options currently exist for recycling HF. The goals of the survey were to uncover the current techniques used by the semiconductor industry to recycle HF, determine the most cost effective method for recycling HF, and also to learn the advantages and disadvantages of recycling HF. According to the results of the survey, the most common method of recycling HF for the semiconductor industry involves the precipitation and flocculation of calcium fluoride (CaF2). The CaF2 filter cake can be sold to another industry to be used in that industry s process. This method along with the crystallization method and the ion exchange method are discussed.