Factors affecting the pyrophorisity of spent bleaching clay

Artificial cakes of bleaching clay/vegetable oil have been studied for their pyrophoric character using both Differential Scanning Calorimetry and a constant‐temperature, fixed‐interval, spontaneous heating (CaTFISH) test developed in this laboratory. It was determined that this is a two‐step process involving a first‐stage low‐temperature spontaneous heating reaaction followed by a second‐stage high‐temperature spontaneous heating reaction. The latter is characterized by charring and, in some cases, flaming combustion. A study of relevant variables has established that clay type, filter cake age, oil retention, moisture, and the presence of antioxidant significantly affect the spontaneous heating characteristics of clay/oil masses. Oil type was not found to be a significant variable in these studies.