Underground drilling rigs are an example of percussion drilling. The first mechanized impact drill was invented in 1844. It used compressed air to apply an impact load to hit the drill bit. Photo: AcademyBlasting.com

The Bblasting Through the Ages series is an initiative of Pit & Quarry and Academy Blast to tell the story of the blasting world. Throughout the ages, great blasters and engineers have completely changed the scientific and artistic blasting techniques used today. This series will introduce in detail the historical methods of drilling, loading and blasting, and lead readers through history and understand the major developments of each era. The series starts with a brief drilling history.

A small gold mine in Hungary began an experiment in 1627 that changed the mining industry forever.

February 8th that year was a cool and refreshing morning in the Hungarian countryside, and the miners went down to the ground one after another. But this day is different.

Caspar Weindl led the group that the Hungarian Mining Tribunal was observing and came up with a new idea that could be tested.

The crew of Oberbiberstollen in Schemnitz will try to break rocks and gold with black powder instead of fire and vinegar. It first uses a striker with a large hammer to press horizontal holes into the drift surface, and then fills each hole with a small amount of black powder. Then, put a reed full of black powder into the hole, and insert a cork at the end to keep everything tight.

Wendell lit the reed, and the crew ran to find cover. The air hit their chests violently, and the ground seemed to tremble for a long time. The man prayed that the crew could escape from the mine.

After the dust settled, everyone looked at the destructive power of the explosion. They found rocks—not large rocks that take days or weeks to break, but finely broken rocks that can be brought to the surface for a second break.

On February 8, 1627, the mining industry ushered in a new era: the era of blasting.

Modern handmade steel shows how the miners originally placed the holes. Photo: Ryan Sibley

The story of drilling began in these early mines in Hungary and Germany, when blasting technology had not yet spread to other parts of the world.

Miners in Hungary and Germany took large rams (chisels) and punched holes with large hammers about 2 inches in diameter and 40 inches in length. Then fill these holes with about 16 grams of black powder and detonate them.

This is not the age of blasting optimization. The focus is to complete the work and spread the technology to other mines. Drilling a hole requires the work of five people-one holding and turning the batting stick, three people taking turns to hit the batting stick with sledgehammers, and one person resting. The entire crew rotates to ensure that they remain active and not too tired.

Although innovations such as clay compaction (packing) and powder factors have been developed, the next major change in the blasting environment comes from improved drilling capabilities.

The first new drilling technology appeared in 1683, when Henning Huthmann proposed a new drilling system using gravity drilling. This kind of drill bit can only be used for vertical holes (such as shafts and open-pit mines), and the drill bit steel will be driven into the rock to start.

Then, the two "strong men" would pick up the heavy object fixed on the rope frame, lift it up and put it on the striker. According to reports, a 1.5-inch deep drill only requires 10 strikes—it's easy to see how slow and laborious the production is at this time.

This is called drop drill, a type of drill that relies on dropping heavy objects on the steel back while slightly rotating the steel to move the drill bit forward. This is a similar mechanism to the drilling used today—percussion drilling—but it is labor intensive and usually requires a person to pick up the weight and release it.

The drill bits at that time were crown bits and roller cone bits, which were slow and inefficient when breaking rocks. No air or water was used to flush the holes to remove cuttings, all drilling relied on violent blows.

In 1749, the Hungarian miners introduced the wedge bit, and ten years later the German introduced the chisel bit. These help to improve efficiency, but still do not solve the problem of drill cuttings.

Further research found that both the number of impacts and the weight falling on the back of the rig helped increase the drilling speed. The "ideal" weight of the lifting drill system is being tested worldwide.

In 1840, a new method of drilling technology appeared: rotary drilling. This system relies on a person turning the drill steel by hand, which slowly drills a hole in the rock. The system was initially only used for coal and very fragile materials because the pressure and rotation speed were not fast enough to penetrate hard rock well.

Prior to this, the only machine drill was the drop drill for vertical holes. Therefore, the system enables miners to drill underground easily and quickly.

In 1844, Brunton invented the first mechanized impact drill, which used compressed air to impose an impact load to hit the drill bit. This was later developed by Nasmyth, and the mining community can now use a simple method to drill horizontal holes with compressed air: percussion drills. Schumann, Cave, Couch and Burleigh and others quickly advanced this technology and developed the elbow drill we know today.

As open-pit mines required larger boreholes than the 1.25- to 2.25-inch diameter boreholes used underground, rotary drilling began to develop. Initially, the target for the hole diameter became 4 inches, then 6 inches, and they continued to grow.

At the same time, with the invention of explosives, it became imperative to drill deeper holes. When using black gunpowder, the charge must be very short to work properly, and no long drilling is required. With the invention of explosives, everything has changed, and drilling technology must keep up.

The drop-drilling system is very suitable for vertical drilling in shafts, but it cannot meet the mine’s demand for larger diameter drilling. The drop drill was not very portable, and the rotary drill started to take over.

These drill bits can be larger in diameter and portable, and are initially operated by a gear system to allow a person to fully drill out of the explosion. In the end, through the inventions of Armstrong, Keystone and Downey, they turned to mechanized drilling. These drill bits led the development of modern large-diameter rotary drill bits available today.

Although it is possible to write a book to tell the history of drilling and the various types of drills invented, this brief analysis tells the story from the first drilling to the blasting in the rock to the beginning of today's modern drilling system. Therefore, let us first briefly introduce the drilling rig systems used in today's mining and construction industries.

There are three main categories of exercises. The first and most common system is the top hammer drill. This is an impact system, which operates by hitting the top of the drill steel with impact force. The rapid impact and rapid rotation of the steel allow rapid drilling. This system is similar to the ancient hollow drill system that uses the same basic mechanism to operate. The typical bit size for top hammer drills is 2 inches to 4 inches, and the maximum practical depth is approximately 60 feet.

The second system is a down-the-hole (DTH) hammer drill, which uses an impact drilling method, but the impact action is directly above the drill bit. This allows deeper holes to be drilled, which can extend beyond 300 feet. These also did not reduce the penetration depth.

These drill bits can also be used for larger diameter holes, with typical drill bit sizes ranging from 3.5 inches to 10 inches. This is a major advancement in impact technology, allowing deeper and more precise drilling on a larger diameter than the top hammer. For this reason, down-the-hole drilling rigs have occupied most of the market for medium-hard rock mining rigs.

The third system currently on the market is a rotary drilling rig, which operates similarly to rotary systems in the late 1800s and early 1900s. They use large and heavy downward pressure to keep the drill in contact with the rock, and slowly claw away from the rock mass to place large-diameter boreholes. These rigs have minimal drilling deviations because they use large steel threaded together to drill the rock.

In large-diameter hard rock, they usually use tri-cone bits, which can increase the drilling speed by ten times to drag the bit, up to 17.5 inches in diameter. These drilling rigs are the main force in the large-scale open-pit mining industry.

Without understanding what will happen in the drilling world, any drilling story is incomplete.

Today, progress has not only been made in drilling equipment, but also in the accompanying software used. Modern drilling rigs are moving towards self-sufficiency, without the need for an operator in the cab. These drills can be automatically positioned and drilled to the precise depth designed-this is not easy for the operator.

Today's drills automatically record key parameters such as penetration rate to develop automatic drilling logging records to help understand the rock. This technology is likely to be advanced to fully autonomous drilling teams on site, which will not only develop information about penetration rates, but also automatically sample rocks to provide such things as compressive strength, tensile strength, and Young's modulus. And other characteristics.

This can help the blaster optimize hole loading for better results, but engineers can also use it to depict different grades of rock and ore. In the future, these rigs may even include sampling systems to automatically report the grade of the rock/ore being drilled.

Although drilling can be processed into larger diameters, one question needs to be asked: do we really need larger diameter holes? A 17-inch diameter borehole requires a table height of at least 125 feet to effectively break the rock. The lowest cost and best performance of blasting with a 17-inch diameter hole requires a table height of 165 feet.

Few mines in the world today can really see the benefits of larger diameters. The operating scale of most mines is much smaller than this maximum.

Although larger diameters are possible, it is not beneficial. In addition, as more and more mines go underground and use smaller diameter boreholes, this may not be a viable market.

The next upgrade in the exercise will be efficiency. At present, the market is rapidly improving the efficiency of the drill bit itself.

Combine this with more powerful equipment to reduce overall drilling costs, and you will see future competition for drilling equipment around cost of ownership, reliability and efficiency.

In the future, drilling may shift to electric power and be powered by large batteries, but at the current rate of advancement in battery technology, it may take 15 to 30 years before it can be widely implemented in the industry.

Finally, these questions should be asked: Is there a better drilling method? In the foreseeable future, will we continue to use percussion and rotary drilling technology? To understand this, one must explore the past again.

Systems such as jet perforation use thermal crushing to break the rock in hard rock, which is very expensive to use and was quickly replaced when tungsten carbide drill bits entered the market. Due to high power consumption and energy density requirements, laser drilling systems are inefficient and are unlikely to become the main drilling method on the market.

The use of explosives for drilling has also been successful, but this has problems in efficiency and application. Although many other drilling technologies have been studied, the reliability, ease of use and practicality of percussion or rotary drilling are hard to match.

Perhaps in the distant future, we will see the development of other technologies (such as thermal fracture) to change the face of drilling. For now, this seems to have some way to go.

After nearly 400 years of drilling, history has witnessed a significant increase in the practice and trading of drilling holes in the rock, making way for large-scale fragmentation.

This history can never be recorded in a few pages, but it is clear that the industry has undergone earth-shaking changes since the first explosion in 1627.

The story of drilling begins with those hardworking people who dig holes in the rock. Today, the machine can move and drill on its own, without the need for a person to sit on it.

Over the next 20 years, the industry will experience tremendous progress, redefining what drilling looks like. Over the next 400 years, it has shaped great new innovations, when future miners will look back and be surprised by today's "old school" drilling methods.

Part 2. Explosive progress through the ages (launched next month)

Part 3. Evolution of the startup system (launched in August)

Part 4. Blasting: The Story of Broken Stones (launched in September)

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