SIMULATED LEACHING OF TIRE MONOFILL COVERING MATERIAL

Covering materials at the tire monofills in southern Stark County, Ohio comes from available mine spoil on site. Rock types found in these materials are sandstone, black shale, shale, underclay, coal and weathered coal. Natural leaching was simulated with simulated precipitation and pulverized rock samples in a Soxhlet extractor at 101±2°C for 24 ± 1 hours. The extracted liquid was then evaporated down to incipient dryness and then analyzed for up to 42 elements using an inductively coupled plasma-mass spectrometry method. Calcareous matrix was seen to disappear after the extraction process. The matrix could be a source for Ca, Mg, but also a source for Ba, Sr, Mn, and Fe. Pyrite dissolution could essentially release all the chalcophilic elements as impurities and held in solid solution. Fusinite particles in coal contain secondary carbonates and framboidal pyrite. During the extraction process, large amounts of trace elements could be extracted from fractured coaly particles in weathered coal. It is interesting to note that large amounts of As can be leached from weathered coal. Dissolution of quartz, muscovite, plagioclase, and clays could also release small amount of trace elements. Pyrite and the associated macarsite can be counted as the major source for elevated levels of Cu, Mo, Pb, and Zn and carbonate minerals for Mn, and Sr in tire monofill leachate. Elevated temperature found in these monofills can further accelerate the leaching process. It is, therefore, imperative that the amounts and the characteristics of these minerals in covering material be carefully studied and regulated.