Investigation of Particle Size Increase of Micronized Copper Azole Preservative and the Effectiveness of Mixing Systems for Storage Tanks

Abstract

Sedimentation in the holding tanks of the wood preservative micronized copper azole (MCA) is a key concern to the wood preservation industry. MCA is in suspension unlike other traditional preservative treating solutions. This project evaluates the effects of the current wood treating conditions on the size of micronized copper particles, the chemical composition of particles over 1 µm, and the potential of implementing a recirculation system for minimizing sedimentation in full scale operations. Experimental results demonstrated elevated temperatures led to an increase in size of MCA, while other parameters exhibited negligible effects. Analysis of particles over 1 µm showed malachite and copper oxides were among the particles identified. Computational Fluid Dynamics (CFD) simulation showed several fluid recirculating retrofits, namely improved inlet configuration could minimize settling, and such modifications would be a simple and inexpensive option for the wood preservation industry, Stella-Jones Inc.