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SEP 2017

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26 • ROCK products • September 2017 www.rockproducts.com also mandates a maximum of 50 percent by volume of used oil in an ANFO product and when used oil exceeds 30 per- cent, absorption tests must be performed prior to blending. Other requirements are also listed in the generic petition, which must then be submitted to MSHA for approval for each individual mine. Tested Component Limit Arsenic 5 ppm maximum Cadmium 2 ppm maximum Chromium 10 ppm maximum Lead 100 ppm maximum Total Halogens 1,000 ppm maximum Flash Point 100° minimum The Mixing Process After the oil has been drained from equipment, it must first be placed into a tank that will store all used oil on-site. Oils of varying grades can be mixed, as long as under 10 percent total volume of 90W oil is used. Oil must then be tested on a re-occurring basis to ensure proper quality is met. One important note, if testing off-site it is best practice to not use the oil until after tests return as failed tests may result in consequences to the mine. After the storage and testing stage, the oil may be drawn from the tank to a truck for mixing into explosives. While the oil is in the tank, it is considered by MSHA as a "used oil" and upon filtering through a 60 mesh and 100 mesh (in series) filter system the oil is then treated as "recycled oil". This oil can now be diluted and mixed with diesel oil and must be used within 24 hours of being drawn into a bulk vehicle. After blending this oil mixture can be used from a bulk truck and is mixed with blasting grade ammonium nitrate prills. With proper oxygen balance and a good truck this USANFO will perform almost identically to regular ANFO. One word of caution, different state Environmental Protec- tion Agencies require different testing and modelling of fumes generated from blasting. Suppose that this oil had a lead con- tent of 40 ppm (40 percent of limit to hazardous waste), with the proper MSHA paperwork and generic petition it could be used in ANFO with up to a 50 percent of the oil mixture. This would then reduce the lead content to 20 ppm for what would be mixed into the ANFO. During the detonation, this oil would be exposed anywhere from 3,000 F to 7,000 F and a chemical reaction would take place that could create some lead components, such as lead oxides, which is a solid at normal state and has a boiling point of about 2,700 F. This means that at a point in the detonation, the lead oxide would be gas and turn to a liquid, then solid normally within milliseconds or less. However, some state EPAs will require "gas modeling" to incorporate this and updating of permits, even though these gasses will not leave the property. The EPA has not responded to requests for more information or federal guidelines on this matter. In this case, best practice is to check with the local EPA office to detail exactly what will be required to allow this. The authors have seen projects in the past that would have saved large amount of money ruined because of such stringent EPA testing and modeling require- ments, especially in terms of air pollution. Conclusion Used oil in ammonium nitrate explosives (ANFOs and Emul- sions) can provide an environmental friendly remedy for disposing of used oils and cut costs at most operations that use heavy equipment. While specific regulations exist to stop this process, exemptions from MSHA can be obtained follow- ing generic petitions and proper testing standards. These testing standards, filtering processes, and maximum blend limitations ensure that used oil does not pose signifi- cant risks to blasting safety or the environment. State EPAs can have significant say in the use of used oil in these explo- sives products and must be contacted in any feasibility study to determine exact regulations of each mine. With proper management of oil and explosives, mines can effi- ciently reduce costs and see increases in their social license to operate by removing normally waste oils from site. Dr. Calvin Konya is the president of Precision Blasting Services, and Anthony Konya is a project engineer for the company. They can be reached at 440-823-2263, or Anthony@idc-pbs.com. Most mines will fuel their ANFO with diesel oil, which is either purchased and provided by the mine or brought in by the explosive supplier. References 30 CFR Part 56.6309. (n.d.). 40 CFR 279.11. (n.d.). ASTM. (n.d.). Closed-Cup D3941-90. ASTM. (n.d.). Open-Cup D1310-86. Mine Safety and Health Administration. (1994). MSHA Generic Petition (revised 9-1-94). Ruhe, T., & Bajpayee, T. (1996). Low Temperature Limits for Mixing Recycled Oil, Diesel Fuel, and Ammonium Nitrate to Make ANFO-Type Blasting Agents. Proceedings of the Twenty-Second Annual Conference on Explosive and Blasting Technique, 232-243. Ruhe, T., & Bajpayee, T. (n.d.). Thermal Stability of ANFO made with Recycled Oil. USED OIL AND EXPLOSIVES

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