Another option we have is to use an emulsion blend blasting product. This product, commonly referred to as “emulsion”, is essentially an ammonium nitrate solution mechanically mixed with other raw materials by a computer controlled system onboard a delivery vehicle that has been driven to the job site. The specially designed delivery truck has a number of holding tanks for these various materials. When the blast is ready to be loaded, the computer controlled system pumps these materials at specific ratios out through a hose and down into the borehole. In this system, the blasting agent is not sensitive until it is pumped into the hole and given time to react and settle in. This process is called “gassing”. This is why the emulsion product McCallum Powder regularly uses is referred to as a non-sensitized, gassing emulsion blasting agent.
There are several benefits to this emulsion product that make it a very useful tool for our daily blasting operations. One important aspect of this emulsion loading process is the stability of the product. Since it is stored in separate tanks on the delivery vehicle, the product is not mixed and therefore not sensitive to detonation prior to it being pumped into the borehole. This allows McCallum Powder to very safely store and haul the product throughout the Pacific Northwest. There are other types of emulsion that can be used which are pre-mixed and very effective. These “sensitized emulsion” products do not offer the flexibility of mixing the product on the job site but do have a lot of the same benefits once the emulsion is loaded.
Another benefit of McCallum Powder’s emulsion is it is 100% waterproof. Having a density over 1.00 g/cc means the product is denser than water. This means when the product is pumped into the water-logged borehole, it will not float but sink to the bottom. With all the product sinking to the bottom, it displaces the water in the borehole, leaving us with a solid, consistent borehole load of explosives without any water pockets. This advantage in the often wet conditions of the Pacific Northwest is invaluable. This way we can plan and execute drilling and blasting operations without having to worry about a variable we will never be able to control: the weather.
The emulsion is delivered via a special custom-designed truck and ejected through a long hose, so we are able to park the truck near the blast pattern and only move the hose from hole to hole, instead of having to pack hundreds of ANFO bags all over the shot. This is both an advantage and a disadvantage of emulsion where we are able to pull the hose along the blast, however the access to the blast pattern needs to be passable for McCallum Powder’s delivery vehicle. Whereas if ANFO was used, any vehicle, such as a skid loader, could be used to deliver the blasting products.
Considering the emulsion can have a density over 1.00 g/cc, often closer to 1.20 g/cc, this means the emulsion is about 45% heaver than ANFO’s density of around 0.82 g/cc. These 0.38 g/cc may not seem like much to those unfamiliar to blasting, but it can make a world of difference with all things considered. With the 45% denser product, a borehole loaded with ANFO that would have held 100 lbs. of explosive product, the exact same borehole loaded with emulsion could hold 145 lbs. of explosives. If you have not read our blog post on Powder Factor, go back and read it to understand the significance of this difference.
Historically, emulsion has been significantly more expensive than ANFO for many reasons. This has caused many people to shy away from trying emulsion as an alternative to ANFO. ANFO has been so successful, reliable, and consistent for so many decades, it is hard to convince some people to try a more expensive product when the product they are currently using is working just fine. However, even though emulsion is a more expensive product, we are able to maximize every borehole, blasting cap, booster, labor hour, and all other fixed costs much more efficiently than ever before, all thanks to emulsion. Not to mention the waterproof advantage, the stability of storage and hauling, as well as the speed of using a hose instead of packing out hundreds of bags.
Initially, we only used emulsion as a product to address the issue of wet boreholes in order to avoid issues with ANFO and dewatering. With the evolution of the emulsion products offered today as well as our increased understanding and appreciation for the product and its cost/benefit ratios to our operation, we now use emulsion on almost every production blast we are able to get access to with one of our fleet of emulsion delivery trucks.
By being able to achieve the same or better Powder Factor with less drilling, less holes, less caps, and less boosters, any drilling and blasting project whether it is wet or dry could benefit from the use of emulsion if applied with knowledgeable, professional and experienced drillers and blasters.