Length and density grading (LDG) technology is used to maximize the recovery of reusable catalyst.

Length grading is used to selectively remove short catalyst particles that cannot be removed with conventional screening. Length grading is particularly valuable for units that are sensitive to pressure drop.

Density grading separates catalyst particles of similar size based on individual particle density. We have effectively separated articles with density differences as small as 10%. One common application of density grading is the separation of heel-contaminated reforming catalyst when the catalyst must be dumped for reactor maintenance. (See the September 18, 1995 Issue of the Oil & Gas Journal for more details.)