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82~27i9d 17:22 E ]B2 S76 8917 NcCle]land Lab 07 <br />• A51'M D-3987.85 <br />'I'bis test method was not designed for, but can he ustd fnr, tttetals [nobility evaluation. <br />Also, the test was not designed for regulatory put'prtses. <br />I)iftcrcnws in protocol include; feed sire waS not specified, minimum 70g solids charge, <br />Ito acid or pH adjustment employed, 29 RPM using hurizcmtal or EOE rolling for 18 <br />!tours. A 0.45µm filter w:ts specified to product extract for analysis. A suite of analysts <br />was not specified. <br />NDEP-M WMT <br />"1'he Nevada Department of Environmental Protection (NDEP) meteoric water mobility <br />test procedure differs substantially from the other four procedures, and iu my opinion <br />more readily simulates potential for metals mobility from hard ruck mine waste and <br />process waste by meteoric water. NDEP will allow a bottle roll extraction procedure, <br />but prefers the column percolation MWMT procedure, The wlumn percolation <br />procedure is described Iterc. <br />NDEP specifies a minimum solids charge weight of Skg at tt feed size no coarser than <br />SOmm (2"). Usually, 50 Ihs is used fnr the column procedure. <br />'17te mint waste samplt (usually a composite) is prepared by initial screening at 2"..Plus <br />2" material is stage cnlshed to just pass a 2" screerL and is recombined with screened <br />• minus 2" material. Although not mandated, plus and minus 2" weight distributloas are <br />calculated. The 100°!0 - 2" waste n>ck feed is blended and split to obtain at least Skg fur <br />the MWM'C, end 2kg for scrcclvng at 21N1 mesh. The 2(X1 mesh screening is required to <br />detcrntne the fines content nt the waste rock. The charge is wet screened at 2W mesh. <br />Size fractions aro dried, weighed, and plus and minus 200 mesh weight distribution are <br />calculated. <br />'the column MWMT' is conducted on the •2" waste rock to detcrnune the mobility of <br />select constituents by synthetic meteoric water (lixiviant), lixiviant p11 after contact with <br />[he solids, and the residual moisNre content of the final solids. The fi' l.D. YVC wlutrm <br />is thoroughly washed, rinsed with dilute acid solution, and rinsed with deionized water to <br />provide a clean envirottmentfur conducting the MWMT. I,ixivianlis prepared by <br />adjusting the pH of deionized water ('type II water) to pli 5.5 with reagent grade <br />concentrated nitric acid. The quantity of lixiviant applied is equivalent t,7 the weight of <br />ttte respective moist solids (1:1 ratio), Lixiviant is applied using metering pumps in a <br />manner to insure 24 hour total application. Efflueltt is collected in a sealed container <br />and the volume is measured by weighing. The efFltlent is thoroughly mixed and at least 2 <br />liters is taken for analysis. '1'hc 2 liter sample is filtered through a 0.7µm filter to <br />product an extract, lixu'act sautples arc taken anJ art appropriate]y preserved for <br />metals, analyte, and if appropriate, WAD cyanide analysis. Samples for metals analysis <br />are preserved by adjusting the pl1 to 2.0 with nitric acid. A sample is preserved for <br />nitrate analysis by adding H2SOd to pH 3.11, An unprescrved sample is used for analyte <br />. !`1cC:LliL1.AN1) 1.AI3URAT(.>It11iR, INl'. <br />