Lessons on safely storing ammonium nitrate-based explosives

Relatively inexpensive, widely available, and easy to use, ammonium nitrate is a critical component to any mining operation – but can be lethal if mismanaged.

Ammonium nitrate-based explosives come in many forms, from ammonium nitrate fuel oil (ANFO) to emulsion and slurry explosives. No matter the form, they remain highly volatile, making storage and transportation exceptionally difficult and labour-intensive.

A grim reminder of the potential dangers of transporting highly sensitive explosives is the 2022 Apiate incident in Ghana, where a large quantity of explosives ignited when a motorcycle collided with a truck. The explosion destroyed hundreds of houses, killed 13 people, and injured about 180 more. Storage is not exempt from risk. In 2020, around 2,750 tonnes of ammonium nitrate ignited and led to an explosion that wounded some 7,000 and displaced around 300,000 people.

While these examples represent the worst-case scenario, any uncontrolled, accidental ignition of ammonium nitrate-based explosives, including those at or near the mine’s operational site, could result in death, injury, destruction of property, severe public backlash, heavy government fines, and project closures.

Guarding against transport-related ignition risks

Every tonne of ammonium nitrate that leaves a supplier’s gate should be treated as a reaction waiting for the wrong conditions to happen. Ignition events usually stem from one of three failures: mechanical shock, heat build-up, or contamination. This means that every kilometre of road must be planned for, and every square metre of storage must be engineered to keep triggers apart.

Moreover, it’s essential that all participants in the transportation process are closely aligned. When the haulage contractor, magazine operator, and the blasting crew share a unified protocol, gaps disappear, and the chances of a chain reaction fall sharply.

Regulations underpin that standard. South Africa’s Explosives Regulations require access-controlled danger zones, lightning protection on all magazines, and strict limits on combustible material inside storage buildings. Additionally, standards such as the national South African National Standards (SANS) 10229 code govern classification and packaging for road transport, linking authorised carriers to designated routes, as well as obliging operators to avoid congested areas wherever feasible and to park only inside secure, fenced compounds when rest stops are unavoidable.

Across the border, Zambia and Namibia mirror those rules, creating a de facto regional baseline that mines cannot ignore. Executives who treat compliance as just paperwork risk being blindsided by a permit suspension the moment a consignment strays from its declared route or arrives at an uncertified storage facility. Ultimately, staying ‘compliant by design’ saves far more than it costs.

Vehicles transporting bulk emulsion or prilled ammonium nitrate in South Africa are further required to have specific safety features, including spark-arrester exhausts, sealed wiring looms, and on-board fire suppression units. These requirements are also outlined in several national regulations.

Drivers must be trained to keep the load within eyesight and in easy reach – unless the vehicle is inside a locked compound. Similarly, they must avoid tools, oils or batteries that could generate sparks in the cargo bay. Occupational Safety and Health Standards’ (OSHA) long-standing 1910.109 standard cites unattended vehicles and mixed cargoes as two of the most common precursors to transport fires.

MEA’s practice is to audit every fleet vehicle quarterly, and fit geo-fenced GPS tags that alert a 24-hour control room if a driver stops outside an authorised zone or deviates from the planned corridor.

Enhanced safety to safely store explosive materials

Once delivered, more stable, permanent storage solutions become critical. Warehouses must be non-combustible, naturally ventilated or fitted with remotely actuated mechanical ventilation in case of fire, and laid out so that stacks stop far enough below roof beams to prevent radiant heat from accumulating above the pile.

Flooring must consist of sealed concrete that’s always kept clean, as contaminants such as wood chips or spilt fuel can act like tinder under an oxidiser. Every stack should sit on timber pallets sheathed in fire-retardant plastic to keep moisture out and to allow forklift airflow underneath.

Automatic sprinklers are compulsory once bagged ammonium nitrate stocks exceed roughly 2,500 tonnes. Below that threshold, mines and storage solutions providers still need to have hydrants, hose reels, and Class A/B extinguishers placed along loading docks and inside each magazine bay.

Even with these layers, people remain the final safeguard. All warehouse staff should rehearse evacuation and cordon drills quarterly, with distances recalculated for the actual tonnage on hand. Supervisors must log inward inspections, checking seal integrity, stack height, humidity, and temperature at the start of every shift. Those logs feed into a cloud dashboard where anomalies trigger automated alerts.

As is evident from the complexities of storing and transporting ammonium nitrate explosives outlined above, expert input from explosives management and logistics providers such as Mining and Energy Acuity (MEA) is paramount from a safety and compliance perspective.

As leading explosives specialists in Africa, MEA has built its reputation on weaving the necessary controls into a tightly integrated chain, from port receipt to final priming on the site. This is why our clients move thousands of tonnes of ammonium nitrate across the subcontinent each month without a single ignition loss. In explosives management, predictability is profit, and predictability begins with vigilance long before the first stick goes down the hole.