Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, TN 375, 1991 Feb; :1-2
Objective: Develop a safe, efficient filter for removing diesel particulate matter (soot) from the exhaust of underground mining machines equipped with water scrubbers. Approach: The Bureau' of Mines and the Donaldson Company, Inc., jointly developed a low-cost, disposable, pleated-media filter (PMF) system. The system is intended for use on Part 36 permissible equipment or other machines equipped with water scrubbers. The PMF is installed downstream of the water scrubber to take advantage of the cool exhaust produced by the water bath. This demonstration system was tested on three Jeffrey 4114 Ramcars and a Wagner LST-5 scoop at Utah Fuel Company's Skyline mine near Scofield, Utah. Figure 1 illustrates a clean filter element being inserted into the canister on the Ramcar. How It Works: The PMF system consists of a water trap, an optional over-pressure relief valve, filter canister, and PMF. Under normal operations exhaust from a vehicle equipped with a water scrubber is heavily laden with water, especially on immediate startup of the engine. The water trap is designed to remove most of the water droplets from the exhaust before they enter the PMF, thus improving PMF performance. The over-pressure valve is designed to limit the exhaust backpressure by venting off some exhaust gas before the filter. It is attached to the water trap upstream of the PMF. Figure 2 illustrates and shows a break out sectional view of the location of the PMF on the Ramcar. After the exhaust exits the water trap, it passes through the PMF. The Donaldson Company manufactures the PMF, which is quite similar to intake air filters used on over-the-road diesel engines. It is a cone-shaped, 24-in-long filter with 270 two-inch pleats, and is constructed of a paper-like material. The PMF is designed to have a filtration efficiency of 99 pct for a standard road dust. However, diesel soot is much smaller in size than road dust so the filtration efficiency of the PMF for soot is slightly lower. Test Results: A week-long field study was conducted to evaluate the performance of the PMF system. The field study evaluated the effects of the PMF on air quality in an underground coal mine using diesel haulage on a continuous miner section. The exhaust systems of four diesel machines, including three Jeffrey 4114 Ramcars and one Wagner LST-5 scoop, were equipped with the PMF exhaust control system for four of the five days of testing. The reduction of soot was measured using size-selective aerosol sampling by inertial impaction followed by gravimetric analysis. These measurements determined the concentration of the submicron aerosol fraction which is almost entirely composed of soot. Samples were collected during normal production shifts in the ventilation intake and the haulageway, in the machine operator compartment, and in the return air. Analysis of measurements indicate that diesel-generated aerosol was reduced on the average by 95 pct +/- 4 pct. The filters tested had a useful service life of about 12 hours and cost about $50 each. Filter life may be extended by ensuring proper engine maintenance, avoiding unnecessary engine idling, and ensuring the water scrubber functions properly.
Minneapolis, MN: U.S. Department of the Interior, Bureau of Mines, TN 375