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7.4 Crush (may hand break) plus 5 cm material to just pass a 5 cm (2 inch) screen and recombine with <br /> the screened minus 5 cm material. <br /> 7.5 Thoroughly blend the recombined 100% minus 5 cm mine rock sample, and using the feed moisture <br /> content (7.1 above), calculate the dry weight of the sample to insure a minimum of 5 kg (dry weight) is <br /> available for the MWMP extraction (column percolation)test. <br /> 7.6 Load the 100% minus 5 cm mine rock sample into the extraction device(column) in a manner to <br /> minimize particle segregation and compaction. <br /> 8. Extraction Procedure <br /> 8.1 Adjust the extraction fluid application rate (2) such that the number of millilitres of water applied to the <br /> column in a 24 hour period will be equal to the number of dry grams of mine rock sample in the column. <br /> 8.2 Measure and record the initial pH of the extraction fluid. <br /> 8.3 Begin metering the extraction fluid onto the top of the mine rock contained in the column at the <br /> predetermined rate. <br /> 8.4 When a volume equal to the mass of dry solids in the column has been delivered through the column <br /> (assume 1 ml/g), cease application of the extraction fluid (3). Note: The mine rock charge will retain water <br /> so extraction fluid application must continue until the target effluent volume(1:1 solids to effluent ratio) <br /> has been collected This will require application time beyond 24 hours, but not to exceed 48 hours. <br /> 8.5 Thoroughly mix the effluent immediately. Then procure sufficient quantity for the required analyses <br /> (usually Profile I or Profile 11). <br /> 8.6 Measure and record the pH of the extract. <br /> 8.7 Filter(4)the sample through a 0.45 pm inert membrane to obtain extract for dissolved constituent <br /> analyses. <br /> 8.8 Preserve (5)the extract sample appropriately for the required analyses. <br /> 8.9 Allow the mine rock solids, after extraction, to drain until the surface of the sample no longer"glistens" <br /> and at least two minutes elapse between drops of effluent from the column <br /> 8.10 Remove the mine rock residue(solids)from the column and take a representative portion for <br /> residual moisture(6)determination <br /> 8.11 Blend and split the moist mine rock residue to obtain samples for additional analysis if necessary. <br /> 8.12 If it is evident at Step 8.3 that the particle size of the sample(finely divided solids such as clayey <br /> soils, sludges, mill tailings, etc.) is not allowing reasonable percolation of the extraction fluid to occur, <br /> aborting the extraction procedure and submitting the sample to an alternate extraction procedure may be <br /> advised. <br /> 9. Reporting (record and report the following to NDEP) <br /> 9.1 pH of extraction fluid (influent). <br />