Influence of stearate dry coating on ibuprofen powder: What about the combustibility?

Dust explosion is one common type of process safety incident within the pharmaceutical industry. During powder processing, surface modification is widely used to increase dust flowability by alleviating inter-particle cohesion. However, it is currently unclear whether the addition of guest particles affects the combustibility of pharmaceutical powders. To investigate the explosion hazard of stearate-coated ibuprofen powder, this paper studied the ignition sensitivity and explosion severity of pure and coated ibuprofen by determining a series of explosion parameters in accordance with ASTM standards. The results indicated that the addition of stearate significantly reduced the minimum ignition energy of the mixture. Other parameters including the minimum ignition temperature, the minimum explosible concentration, the maximum explosion pressure, and the maximum rate of pressure rise were found to have less correlation with the improvement in dust flowability. Powder characterization through methods such as the Hausner ratio, scanning electron microscope, thermo-gravimetric analysis, and X-ray diffraction were employed to investigate chemical phase changes between coated mixtures and pure pharmaceuticals. The effects of improved dust flowability and dust dispersibility on the combustibility of ibuprofen dust were discussed to improve explosion-proof awareness in the pharmaceutical industry.