US EPA

1690926 

Journal Article 

ANFO is not always ANFO 

Nygaard, EC; Voges, K; ISEE; ISEE 

2001 

PROCEEDINGS OF THE TWENTY-SEVENTH ANNUAL CONFERENCE ON EXPLOSIVES AND BLASTING TECHNIQUE, VOL II 

97-105 

WOS:000174089300008 

ANFO is the most used industrial blasting agent in the world, and is often used as a reference for comparison of other explosives. It is known to work very well under dry conditions in large borehole diameters, whilst in small borehole diameters increasing amounts of toxic fumes (CO, NO and NO2) can be formed. In underground blasting, problems can also occur with reduced visibility caused by unreacted ammonium nitrate and overall composition of the detonation fumes. ANFO is made by mixing Ammonium Nitrate Porous Prills (AN-PP) and fuel oil. We have measured velocity of detonation (VOD), toxic fumes and visibility after blasting of ANFO in 54x2 mm steel tubes, and the differences are remarkable: By using an AN-PP grade developed for underground blasting and small diameters, the following can be obtained:. VOD increased from 1500 to 3500 m/s. The amount of CO was reduced by more than 30%. The amount of NO and NO2 was be reduced by more than 50% and 80%, respectively. The visibility was be improved by more than 90%. Although the improvements were smaller when blasting in rock, the positive results were confirmed. The results show that it is important to choose the correct AN-PP grade for the different applications. A good AN-PP for open pit blasting is not necessarily a good product to use for ANFO in underground blasting, and vice versa. It is also pointless to use ANFO as a reference blasting agent for VOD and toxic fumes without referring to the AN-PP characteristics and the test conditions. To extend the use of ANFO more focus should be on further development of various types of ANFO based products like Water resistant ANFO Aluminised ANFO Reduced ANFO (ANFO light) The ultimate goal should be an overall improvement of ANFO as a concept rather than just a product.