For this reason, we will center this discussion primarily on ANFO, noting that similar principles would apply to emulsions with proper percentages.
Ammonium Nitrate and Fuel Oil (ANFO) typically has around 6 percent oil with an optimal balance of 5.7 percent oil to 94.3 percent ammonium nitrate.
Two methods exist then for adding used oil to the ANFO. The first method would be to use the entire amount of oil as a used oil.
The major risks associated with used oil in ANFO is in blasting safety and environmental concerns.
The stone industry shifted to bulk products, dewatering the holes with pumps and increasing the percentage of ANFO in the hole.
ANFO absorbs three times its weight in water from the surrounding rock.
This oftentimes restricts them from taking full advantage of the drilling benefits of heavy ANFO, but they are getting good results.
"For some conditions, we are sensitizing down to the specific gravities that resembles ANFO densities." The specific gravity of ANFO is 0.85 and the specific gravity of straight emulsion is 1.30.
A typical blend will have over 50 percent of its total mixture be emulsion by weight with the remainder composing of ammonium nitrate or ANFO.
Currently, from studies conducted by NIOSH it is known that any form of blend or heavy ANFO will produce greater amounts of fumes than straight emulsion or straight ANFO, it is believed this may stem from detonation parameters.
In order to improve this situation, ensure that if a blend is being used for water resistance, ANFO is fueled properly and being mixed with the emulsion.
Furthermore, in some places in the world these blends are being sold mixing hard fertilizer prill AN with emulsion, yet selling the hard prill AN for the price of an ANFO. This dramatically increases the cost of the product, for example let's assume that ANFO sells for $0.30 per pound and hard-prill sells for $0.18 per pound.