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<br /> <br /> <br />1-/~l~ <br />NVaai~m At1a~ <br />International <br />. ue~,o.~ Ca.o.. <br />CORE LABOFtATOR1ES <br />HIIMIDITY CELL TESTING <br />Analytical tests used to predict the formation of ac <br />drainage fall into two categories. Static tests measu <br />of acid-producing material and acid-consuming materi <br />the sample. Kinetic testing attempts to simulate th <br />producing and acid-consuming processes which occur is <br />environment. Humidity cell testing is a kinetic tes <br />obtained from static tests are relatively simple to <br />may not be representative of the naturally occurring <br />reactions. Kinetic tests, including humidity cell t <br />more realistic model of the reactions occurring in t: <br />environment but analytical results are often more di <br />interpret. <br />SAMPLE PREPARATION <br />mine <br />a the amount <br />present in <br />acid- <br />the natural <br />Results <br />terpret but <br />inq, are a <br />natural <br />cult to <br />Samples are air-dried at room temperature for 24 hour$ or until a <br />stable weight is obtained. Air-dried samples are the~h crushed to <br />minus l0 mesh (2 mm) using a disk pulverizer and thor ughly <br />blended. Air-dried, crushed samgles are stored in pl stic bags <br />until analysis. <br />TEBT APPARATIIB <br />Humidity test cells are plastic containers with tight fitting <br />lids. Each cell is 2.75 inches high and 7 inches squ re. An <br />air inlet feeds into the center of the top lid and a d ain fitting <br />is located in the bottom corner of each cell (see Fi re 1). A <br />series of twelve individual humidity cells is connect d to a <br />regulated source of compressed air using equal lengths of 0.5 inch <br />diameter Tygon tubing. Humidified air is generated u inq a 6.5 <br />gallon glass carboy which is half-filled with deionize~d water. <br />This carboy is equipped with Tygon tubing connected to two <br />dispersion air-stones. Compressed air can be fed directly to the <br />humidity cells (dry air cycle) or pumped through the rboy first <br />and then routed to the humidity cells (humidified air cycle). <br />Humidity cells are placed on wire racks during testingj. Sample <br />leachates are collected using glass beakers located beneath the <br />drain fitting of each cell (see Figure 1). <br />.r... _,.. ,-. i <br />