Hydrogen peroxide and caustic soda: Dancing with a dragon at the pulp mill

When hydrogen peroxide is mixed with caustic soda as part of the pulping or paper-making process, potentially dangerous amounts of heat and oxygen can develop. As a result, catastrophic events have occurred at several mills in Europe and North America in recent decades. Enter the dragon.

Peter Hart, manager of new technology at MWV Corp., in Atlanta, GA, worked with FPL research chemical engineer Carl Houtman and analytical chemist Kolby Hirth to develop safety considerations for installing new or retrofit bleaching systems that include dilution of hydrogen peroxide from a common 50% concentration to a safer level. Peroxide at 10% concentration cannot generate the explosive mixture with sodium hydroxide. As a means of comparison, peroxide solutions typically found in a home medicine cabinet are closer to 3% concentration.

Trucks or railcars often deliver hydrogen peroxide to pulp mills, where it is routinely stored at a 50% concentration. By diluting peroxide, safer bleaching systems can be maintained. Peroxide is commonly used as part of a bleaching sequence in kraft mills to brighten and to provide brightness stabilization.