The blog post contains a summary of the article by Timo Halme from FORCIT Explosives, which was presented and published at EFEE (European Federation of Explosives Engineers) in 2025.
The full article can be downloaded from the link provided below the summary.
HYDROGEN PEROXIDE (HP) AND HYDROGEN PEROXIDE EMULSION (HPE)
HP is a powerful oxidizer widely used in the process industry. Contamination of HP typically leads to rapid exothermic decomposition, producing large volumes of oxygen gas and vaporized water, which can cause pressure build-up or even explosion.
Explosive compositions based on HP can be formulated in several ways. This paper focuses on water-in-oil fuel mixture (HPE), as the continuous fuel phase offers protection against contamination of HP droplets.
COMPARISON OF HPE AND ANE (AMMONIUM NITRATE EMULSION)
HP is much more reactive when compared to AN. However, technically speaking usability and performance of HPE is comparable to common ANE products with some exceptions. HPE viscosity and pumpability can be adjusted so that standard ANE loading technology can be converted for HPE.
For example, oxygen balanced Kemiitti HPE made of 50-60 % HP solution energy is comparable to FORCIT’s Kemiitti 810. Kemiitti HPE performance has been tested in development blasts. Fragmentation and advance were at least as good as ANE products. VOD for Kemiitti HPE was 4400–5300 m/s in Ø51 mm horizontal holes.
Technical differences between HPE and ANE products come mainly when considering lower densities. Ungassed density of HPE is between 1,15–1,20 g/cc and gassed density between 0,8–1,0 g/cc depending on HP concentration. Gassed density is typically lower than water density. In water-filled boreholes, gassed HPE may detach and float due to its lower density than water. In addition, vertical hole depth might be limited due to pressure build-up on hole bottom. High pressure might lead to high density causing low initiation sensitivity on the bottom. Theoretically maximum vertical column for HPE is 20 meters but more tests and VOD measurements are required for confirmation.
OCCUPATIONAL HEALTH
According to ECHA (European Chemicals Agency) long term (8h) exposure limit in air is 1ppm and short term (15min) exposure limit is 2ppm. HP concentrations have been measured with HP-sensor while handling HP or HPE. The readings were repeatedly over 2 ppm.
As mentioned before, HP and HPE are highly reactive compounds. The reaction evolves and spreads very fast through the whole mass of HPE. When the first signs of vapor cloud and bubbling appear the reactivity spreads through whole mass in minutes. Reasons probably are sharp temperature rise, strong convection and chemically aggressive radicals released from decomposing HP.
The high concentration of HP in vapor is caused by increased vapor pressure of HP in boiling HPE but also strong convection of oxygen gas and vaporized water that carries HP as aerosol.
HP/HPE EXPOSURE SYMPTOMS, RISKS AND MITIGATION
Initial symptoms of HP vapor exposure include itching and burning feeling on skin, airways and eyes, followed by dizziness. Repeated long-term exposure can cause permanent lung damage, which may be intensified by fine particulate matter in mining environments. Additionally, decomposition of HP can release singlet oxygen, a reactive species capable of damaging DNA and exhibiting carcinogenic effects.
Contamination is an everyday risk in loading with bulk products. While HPE spreads similarly to ANE, its consequences are more severe. Mildest symptoms are itching and stinging/burning pain on skin and potentially infection later. HPE entering the eyes can cause permanent damage.
Contaminated working clothes and other combustible materials can ignite spontaneously. FORCIT has had two cases where organic material used to clean HP/HPE stains have ignited spontaneously.
Current mitigation measures at FORCIT include strict PPE requirements: motorized full-face mask with suitable gas filter, chemical-resistant coveralls, long-sleeved chemical-resistant gloves, and rubber boots. Careful handling and limiting volumes are also essential.
BLAST FUMES
Forcit has arranged three campaigns of blast fume measurements for Kemiitti HPE product. Results show no NOx exists in blast fumes, but CO levels were comparable to levels obtained from ANE products. Also some ppm of HP was detected. Development goal for the future is to optimize HPE formulation so that CO production is minimal.
SAFETY
HPE contains over 90 wt-% HP solution, giving it similar reactivity potential as HP, despite the protective water-in-oil structure. Compatibility with other explosive components requires risk assessment and test data due to high reactivity of HPE. Runaway reaction may lead to premature detonation. Known hazardous reactions include those with acetone and hexamine, which can form initial explosives.
CLASSIFICATION AND WASTE HANDLING
HPE cannot use ANE’s UN3375 classification because it applies only to emulsion matrices where AN acts as an oxidizer. The unique features of HP must be considered in the risk profile. The largest difference and challenge compared to ANE, is the spontaneous decomposition of HP creating oxygen gas bubbles in HPE (i.e. HPE becomes spontaneously sensitized with time). This spontaneous decomposition can be slowed down but not stopped. Sooner or later HPE transforms spontaneously into class 1 material.
In framework of ADR a classification as a self-reactive substance may be possible but also in that case spontaneous decomposition may practically lead to class 1.
Waste handling is challenging due to high reactivity of HPE. A waste bucket containing HPE can start reacting violently at any minute. Therefore all HPE waste must be avoided, and any generated waste must be rendered safe immediately, starting with demulsification. Further research is required to develop safe disposal methods.
ENVIRONMENTAL IMPACT
HP is often marketed as a green chemical because it decomposes into oxygen and water. However, when used in bulk explosives, release scenarios must be reassessed. Studies indicate that 5-20 % of bulk explosives may remain unreacted in muck after blasting, posing risks such as HP contamination in water and oxidation of chromium (III) to toxic chromium (VI).
Recently, HP manufacturers have introduced a new hazard category to the HP classification. Within couple months all HP solutions containing more than 25% HP will be classified hazardous to environment – very toxic to aquatic life. We are analyzing the effect of this to use as a raw material for bulk explosives.