Study on the inhibition mechanism of green suppressants zinc borate and zinc silicate for oil shale based on flame propagation experiment and thermodynamic analysis

The Green materials zinc borate (ZB) and zinc silicate (ZS) were adopted as suppressants. Hartmann tube was used to study the flame inhibition effect of oil shale explosion. It showed that the flame front length became shorter and the propagation velocity and acceleration gradually decreased by increasing suppressants. When 30 wt% ZB was added, the complete inhibition of oil shale explosion flame could be achieved, while the flame inhibition effect of ZS was relatively weak. Flynn-Wall-Ozawa and Starink methods were used to study the activation energy of oil shale, which showed that the activation energy increased significantly after adding the suppressant. By characterization tests, the microstructure changes of oil shale before and after the explosion were analyzed, and the mechanism of the explosion inhibition difference between two suppressants was revealed. ZS played a physical inhibiting role by absorbing heat, reducing temperature and diluting the concentration of combustible gases. While ZB not only had the physical inhibition role of absorbing heat and diluting the concentration of gases, but also had a covering physical inhibition role. Simultaneously, ZB also had the chemical effect. It played a highly effective physical and chemical synergistic inhibition role in the deflagration of oil shale.