Benefits of process intensification for Caro's acid production

Process intensification is a method of achieving inherently safer designs by reducing the inventory of hazardous material. Fortuitously, intensification also reduces capital cost because if less material is present, then vessels pipes, structures and foundations become smaller and cheaper. Traditionally, Caro's acid has been produced by reacting concentrated sulphuric acid with hydrogen peroxide at sub-ambient temperatures to avoid product decomposition. The equipment was bulky and relatively costly - typically a refrigerated 30 litre reactor vessel operating with a residence time of 30 minutes was needed to produce 300 kg per day of product. The high capital and operating costs of such equipment greatly limited the in situ generation of Caro's acid for use as an oxidant for potential applications. However, by applying the principle of intensification Interox have developed a continuous adiabatic reactor with an output three times greater than the previous unit, using a reactor volume of only 20 ml (equivalent to a size reduction of 1500:1), a residence time of less than a second and capable of operating without cooling. A unit has successfully completed field trials extracting uranium in Australia and detoxifying a cyanide effluent in Europe. On the basis of this work, a compact, portable, stand-alone Caro's acid generator has been built which is designed to run automatically without constant supervision at user sites around the world. The development of the unit has demonstrated that a simpler and safer design can be achieved by process intensification with significant savings in both capital and operating costs.