Blasting Through the Ages: Explosive advancement through the ages

Hundreds of men began rowing, moving closer to their enemy and readying to launch their new weapon: Greek fire.

Every row brought them closer to opening the hatch and firing the burning liquid toward the enemy ship. Finally, they got within range and opened a series of long, bronze tubes that held back tons of Greek fire and sent the flaming liquid to cover the opposing boat.

In the year 678 A.D., a new age of history began: that of controlled explosives.

Burning liquids had been used in warfare since before 400 B.C. Today, we believe this to be petroleum products that were dumped into the water and lit to either destroy ships or prevent their movement.

Still, Greek fire, which was developed in 678, is credited as one of the first high explosives utilized by man. With the success and power of explosives, humanity began to extensively study explosives that could be used in warfare and in daily life. The advancement originally began with Greek Fire, leading to the development of land- and water-based deployment strategies, along with mines and grenades.

Around 900 A.D., reports of gunpowder in China for medicinal use began developing. By the 13th century, the explosive spread throughout Europe and Asia for use in warfare.

The actual development, formulations and history are heavily debated today. Black powder is a deflagrating explosive, meaning it burns rapidly but does not detonate and it does not produce a shockwave. It is likely that Greek fire was also a deflagrating explosive, although the formulations are not known today.

Detonating explosives

The first detonating explosive was not developed until 1608, more than 2,000 years after the first reports of incendiary weapons in naval battles.

The name of this explosive was lost to history, but it was reported to be extremely powerful and likely did truly detonate based on observational reporting.
In 1659, the first ammonium nitrate compound was produced. This is the major ingredient in commercial explosives today.

Fulminating Silver, which has been used throughout the years and is still around today in some ballistics and initiation systems, was invented in 1786. At the time, though, these explosives were not heavily utilized and considered too sensitive to be used in a practical manner.

Then, one of the greatest inventions in commercial explosives arrived from an unusual place. Ascanio Sobrero, an Italian chemist, was looking to develop a new medicine as a cure to angina. The new medicine would have to dilate blood vessels to help reduce blood pressure.

As Sobrero experimented with various compounds, he invented nitroglycerin, which testing showed to be extremely effective in the treatment of angina. He began to produce it in large quantities, and one morning, upon walking into his laboratory, found the entire place destroyed from within.

Sobrero had no idea what happened. He began to make more nitroglycerin after rebuilding, but a bottle sitting on a shelf randomly detonated one day, causing damage and frightening Sobrero. He was a religious man, claiming this nitroglycerin was the devil’s work, and that the devil could cause it to detonate at any time. He spent the rest of his life cautioning others from making the new medicine.

One of Sobrero’s students did not listen, and instead of ensuring it was not produced decided to take the nitroglycerin back to his father’s construction company to experiment with it in blasting. To accomplish this, liquid nitroglycerin was put into glass bottles and lowered into a borehole, then fired using black powder.

The approach was extremely effective, and Immanuel Nobel, who was Alfred Nobel’s father, began using nitroglycerin regularly. Eventually, Alfred lost his brother and a chemist to a large plant explosion, and he began experimenting with developing a safer version of nitroglycerin.

One day, after spilling nitroglycerin on his floor, he used some diatomaceous earth to soak it up. He eventually tested this product and found that it was safe and could reliably be fired. Alfred went on to file the first safe, high explosive for the commercial explosive industry: dynamite.

Modern explosives

Dynamite was one of the greatest inventions for the explosive industry and led to rapid advances in commercial blasting.

After nearly a century, dynamite was replaced by explosives that were even safer and cheaper – ammonium nitrate-based explosives. This first started in the 1950s, with the experimentation of Melvin Cook, who wanted to add water to explosives to create a pumpable explosive product.

Originally, Cook was laughed at and labeled a theoretician by the industry because, typically, water desensitized explosives. Cook then took water and mixed in finely crushed TNT and a gumming agent to harden the product.

Upon testing, the product not only fired but it was extremely powerful and pumpable. This was the first water-gel explosive created. Following its invention, Cook went on to found the Ireco Powder Co.

Water gels later transformed, adding in first ammonium nitrates and then substituting TNT with a liquid explosive: momomethylamine nitrate. In the 1970s, research began to remove the high explosive from water gels and, eventually, emulsions were made. These have taken over the slurry explosives market.

Around a similar time, Bob Akre was working for Cleveland-Cliffs Collieries in Indiana when he decided to experiment with developing a new type of explosive.

Akre had seen major disasters such as the Texas City ship explosion that was caused by ammonium nitrate. He knew ammonium nitrate was used in other explosive products such as some dynamites, and he wanted to see if he could develop an explosive from ammonium nitrate fertilizer.

Akre decided he would experiment right outside his office, and he brought over a cement mixer. He tried to mix ammonium nitrate fertilizer prills with different substances and take them to his coal pit, load the new mixtures into 9-in.-diameter holes, and fire the holes as part of his normal blast.

Akre had numerous rapid successes, but the practicality of the new products became the major challenge. For example, in one test he combined ammonium nitrate with molasses. The product shot great, but after the blast he couldn’t figure out how to deal with the massive bee swarm that came to the pit and surrounded his mixer.
Later, Akre started adding fine coal, which was a waste product at the time. This worked extremely well in the blast.

Eventually, other mines started to request that Akre sell the new products to them. Problems quickly arose with segregation of the ammonium nitrate and coal fines. This led to the addition of waxes and/or oil as the fuel for the product now called ANFO, which is the top-used product in the world.

Conclusion

Today, great advancements have been made in commercial explosives. Emulsions are using better emulsifiers that increase shelf-life and decrease crystallization and energy loss. New ammonium nitrate prills were invented called technical grade ammonium nitrate that increase the energy of ANFO products and their ability to hold oil.

Additionally, experimentation was done to allow for better sensitization, better control and more energetic products. Also, new manufacturing methods produce less waste and reduce production costs.

While we can look back through history and see advancements made in the technology of commercial explosives, the future is also full of exciting new products. Today, for example, green energetic materials and nanoexplosives are being experimented with to develop more powerful, cleaner explosives for mines.

The future is open in the story of explosives, and it will be up to engineers of today and tomorrow to pick up the torch and carry it to write the next chapter.

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The Blasting Through the Ages series is an initiative by Pit & Quarry and Academy Blasting to tell the story of the blasting world. The series will include four articles spanning four issues of the magazine, including:
Part 1. A Brief History of Drilling
Part 2. Explosive Advancement Through the Ages
Part 3. The Evolution of Initiation Systems
Part 4. Blasting: The Story of Breaking Rock