Introduction
Water gel, sometimes known as slurry explosive, is a relatively new explosive that has supplanted conventional explosives. Slurries are made up of one or more solid ingredients in a semi-solid or gel state. In essence, these are made by mixing a natural polymer like guar gum with a water solution of an inorganic oxidiser, such as ammonium nitrate (which can also be combined with sodium or calcium nitrate). Slurry is created in the gel by the diffusion of gasoline and oil.
Composition and Properties
A typical slurry explosive formulation includes:
- Ammonium Nitrate: This is the primary oxidizer used in slurry explosives, often in combination with water and various surfactants.
- Water: Serves as the medium for the slurry, affecting the viscosity and stability of the explosive.
- Fuels: Common fuels include fuel oil, aluminum powder, or other carbonaceous materials that enhance the explosive’s energy output.
- Additives: These may include gelling agents, sensitizers, and stabilizers to improve performance and safety. For instance, guar gum or polyacrylamide can be used to modify viscosity and stability
Mechanism of Action
Slurry explosives detonate through a shock wave initiated by a detonator. The energy released during detonation is influenced by factors such as the particle size of the ammonium nitrate, the degree of mixing with fuels, and the confinement conditions during use. The detonation velocity can vary significantly based on these parameters, typically ranging from 1400 to 6000 m/s.
Safety measures
- Should be kept away from flame & excessive heat
- Should be handled and stored with care.
- Do not subject product to heavy impact or friction
- During charging ensure that cartridges are charged in a continuous column in the bore hole
Advantages
- Cost efficient, easy to use and safe
- They provide high degree of safety from Mechanical Impact friction
- They have exceptional bore hole coupling as they have high loading density in a bore hole thus enabling them to transfer maximum energy
- Better water resistance than ANFO
Applications
Slurry explosives are predominantly used in:
- Mining: For blasting rock in surface and underground operations.
- Construction: In large-scale earth-moving projects where controlled demolition is required.
Due to their water content, slurry explosives are less sensitive to accidental detonation compared to traditional dynamite, making them safer for handling and storage.
Trends and Developments
In recent years, there has been an increasing focus on the characterization and identification of slurry explosives due to their potential misuse in criminal activities. Advances in analytical techniques are being developed to differentiate between various types of slurry explosives based on their chemical composition and physical properties.
Conclusion
Overall, slurry explosives represent a significant advancement in explosive technology, providing effective solutions for industrial applications while also posing challenges for safety and regulation.
Bibliography
https://www.sciencedirect.com/science/article/abs/pii/S0003267098005339
https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/ammonium-nitrate
https://link.springer.com/chapter/10.1007/978-94-017-0639-1_9
