What is the dominant factor determining the selection of ANFO versus emulsion explosives in a dry versus wet blasting environment?

The dominant factor determining the selection of ANFO (Ammonium Nitrate Fuel Oil) versus emulsion explosives in dry versus wet blasting environments is water resistance. ANFO is a mixture of ammonium nitrate fertilizer and fuel oil. Ammonium nitrate is highly soluble in water, which means it readily dissolves. If ANFO gets wet, the ammonium nitrate will dissolve, rendering the explosive ineffective and potentially causing misfires. Therefore, ANFO is primarily suitable for dry blasting environments where there is no water present in the boreholes. Emulsion explosives, on the other hand, are specifically designed to be water-resistant. They consist of tiny droplets of water containing ammonium nitrate surrounded by a continuous oil phase. This water-in-oil emulsion prevents the ammonium nitrate from dissolving when exposed to water. Emulsions can also contain other ingredients to enhance their performance and water resistance. Because of their water resistance, emulsion explosives are the preferred choice for wet blasting environments where boreholes are water-filled or damp. In these conditions, ANFO would fail to detonate reliably, while emulsion explosives will perform effectively. The choice between ANFO and emulsion is therefore dictated primarily by the presence or absence of water in the blast holes.