How can the incombustible content of rock dust be determined after application?

The incombustible content of rock dust can be accurately determined through the analysis of samples using a volumeter or proximate analysis. This method allows for precise measurement of the various components of the dust, including the proportions of incombustible materials versus combustible materials.

Proximate analysis specifically assesses the moisture, volatile matter, ash, and fixed carbon in a sample. In the context of rock dust, the incombustible content is primarily associated with the ash content, providing valuable insight into its effectiveness in controlling hazards like coal dust explosions.

Using a volumeter can also help in quantifying how much rock dust is required to achieve a certain level of fire suppression, as it measures the physical and chemical properties of the dust. This approach is more systematic and scientific compared to visual inspections or simple weight measures, which may not provide a complete picture of the material's combustibility.