Dynamite

Most dynamites are nitroglycerin-based products. A few manufacturers of dynamite have products in which they substituted non-headache producing high explosives such as nitro-starch for the nitroglycerin. Dynamites are the most sensitive of all the generic classes of explosives. Because of their sensitivity, they offer an extra margin of dependability in the blasthole since gaps in loading within the explosive column and many other environmental factors that cause other explosives to misfire do not occur as often with dynamite.

There are two major sub-classifications within the dynamite family: granular dynamite and gelatin dynamite (Figure 18). Granular dynamite is a compound that uses a single high explosive base such as nitroglycerin. Gelatin dynamite is a mixture of nitroglycerin and nitrocellulose that produces a rubbery waterproof compound.

Straight dynamite consists of nitroglycerin, sodium nitrate, carbonaceous fuels, sulfur, and antacids. The term “straight” means that the dynamite contains no AN. Straight dynamite is the most sensitive commercial high explosive in use today. It should not be used for most construction applications since its sensitivity to shock can result in sympathetic detonation from adjacent holes, firing on an earlier than planned delay. On the other hand, straight dynamite is an extremely valuable product for dirt ditching (excavation of a ditch in dirt using an explosive compound). The sympathetic detonation previously discussed is an attribute in dirt ditching because it eliminates the need for a detonator in each and every hole.

High density extra dynamite is the most widely used product. It is similar to straight dynamite except that some of the nitroglycerin and sodium nitrate is replaced with AN. The ammonia or extra dynamite is less sensitive to shock and friction than the straight dynamite. It has found broad use in all applications, quarries, underground mines, and construction.

Low density extra dynamites are similar in composition to the high-density products, except that more nitroglycerin and sodium nitrate is replaced with AN. Since the cartridge contains a large proportion of AN, its’ bulk or volume strength is relatively low. This product is useful in soft rock or where a deliberate attempt is made to limit the energy placed into the blasthole.

Straight gelatins are blasting gels with additional sodium nitrate, carbonaceous fuel, and sometimes sulfur. In strength, it is the gelatinous equivalent of straight dynamite. A straight blasting gelatin is the most powerful nitroglycerin-based explosive. A straight gel, because of its composition, is also the most waterproof dynamite.

Ammonia gelatin is sometimes called special or extra gelatin. It is a mixture of straight gelatin with additional AN added to replace some of the nitroglycerin and sodium nitrate. Ammonia gels are suitable for wet conditions and are primarily used as bottom loads in small diameter blastholes. Ammonia gelatins do not have the water resistance of a straight gel. Ammonia gels are often used as primers for blasting agents.

Semi gelatin dynamite is similar to ammonia dynamite except it normally contains additional AN. This product has moderate water resistance and is a low-cost water- resistant product commonly used by the construction industry.