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<br /> <br /> <br />~~~.~ <br />W~st~rn AtW <br />Ineernatianel <br />INTRODUCTION <br />CORE LAB~RA~CRIE5 <br />HUMIDITY CELL TESTING <br />Analytical tests used to predict the formation of acid mine <br />drainage fall into two categories. Static tests meas re the amount <br />of acid-producing material and acid-consuming materi 1 present in <br />the sample. Kinetic testing attempts to simulate the acid- <br />producing and acid-consuming processes which occur i~h the natural <br />environment. Humidity cell testing is a kinetic tes Results <br />obtained from static tests are relatively simple to nterpret but <br />may not be representative of the naturally occurring chemical <br />reactions. Kinetic tests, including humidity cell t sting, are a <br />more realistic model of the reactions occurring in t e natural <br />environment but analytical results are often more di ficult to <br />interpret. <br />SAMPLE PREPARATION <br />Samples are air-dried at room temperature for 24 houtls or until a <br />stable weight is obtained. Air-dried samples are then crushed to <br />minus 10 mesh (2 mm) using a disk pulverizer and thoroughly <br />blended. Air-dried, crushed samples are stored in pliastic bags <br />until analysis. <br />TEST APPARATUS <br />Humidity test cells are plastic containers with tightfitting <br />lids. Each cell is 2.75 inches high and 7 inches square. An <br />air inlet feeds into the center of the top lid and a drain fitting <br />is located in the bottom corner of each cell (see Figy~re 1). A <br />series of twelve individual humidity cells is connected to a <br />regulated source of compressed air using equal lengths of 0.5 inch <br />diameter Tyqon tubing. Humidified air is generated u ing a 6.5 <br />gallon glass carboy which is half-filled with deioniz d water. <br />This carboy is equipped with Tygon tubing connected t~ two <br />dispersion air-stones. Compressed air can be fed directly to the <br />humidity cells (dry air cycle) or pumped through the c3arboy first <br />and then routed to the humidity cells (humidified air cycle). <br />Humidity cells are placed on wire racks during testing. Sample <br />leachates are collected using glass beakers located beneath the <br />drain fitting of each cell (see Figure 1). <br />Ttr, anNYS~f oproon•n Mnrvwara+cmwntrem Tarpon err. <br />ni+rpnnnn+aop~ngnf natlfW r+p+fM+M M+I Irba~r <br />m Tr YaOUrnvM. Woos opvcm+ a Wom+Oy"w rortrvrW <br />r/n+C10+rM <br />n. <br />.. <br />qn <br />