Modular Process Design: Chemical and Thermal Recycling of Acids

In order to recycle spent acids from different applications, a design approach based on different process modules gives operators the flexibility needed to handle different contaminants Spent or waste acids (SA) containing sulfuric or nitric acid are a byproduct of various processes involving nitration or sulfonation reactions or of processes, in which these acids are used for leaching or as a catalyst. These reactions and processes are used in the industrial production of polymers, drugs, pigments, other specialty chemicals, explosives, battery chemicals or metallurgical products. The SA from such industries is diluted by reaction water and contaminated with organic and inorganic compounds. Stricter environmental regulations and rising raw-material prices in recent years have led to considerable cost and organizational effort for the procurement of fresh acid and the disposal of SA. An effective acid-recycling system can contribute to a more cost-efficient, independent and environmentally friendly production process. A challenge for recycling systems, however, is the wide variety of production processes and the resulting SA with partly unknown contaminants. Chemical and thermal recycling of SA consists of various steps and the…