In many industrial processes solids must be purged of gases between processing units. For example, often solids containing air must be purged of oxygen before entering oxygen-sensitive processes. Solids purging can be effectively accomplished in multi-stage purge columns in which the purging gas, e.g., nitrogen, flows counter to the solids as the solids flow by gravity down the purge column. Experiments were conducted in 2.75" & 6" diameter, 7 stage purge columns. Several stage dividers were tested; however, stage dividers, consisting of funnels with dispersing washers beneath the funnel discharge, was the most effective geometry tested for purging. Interstage backmixing rates were determined by judiciuos purging of test solids with oxygen and by using oxygen sensors to measure oxygen concentrations within individual stages. From this data interstage backmixing rates were determined. Predictive correlations are presented for interstage backmixing rates as are design methods for predicting column purging performance.