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| − | ===Table 5-1: Methods for Geochemical Characterization===
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| | | | |
| − | <table border="1" cellspacing="0" cellpadding="3" width="1304">
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| − | <tr>
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| − | <td width="137" bgcolor="#dddddd"><p><strong>Test Type</strong></p></td>
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| − | <td width="241" bgcolor="#dddddd"><p><strong>Test Methods and Description</strong></p></td>
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| − | <td width="252" bgcolor="#dddddd"><p><strong>Use in Water Quality Prediction</strong></p></td>
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| − | <td width="313" bgcolor="#dddddd"><p><strong>Advantages</strong></p></td>
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| − | <td width="319" bgcolor="#dddddd"><p><strong>Limitations</strong></p></td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="3"><strong>Grain Size</strong></td>
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| − | <td width="241" valign="top">Sieve</td>
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| − | <td width="252" rowspan="3" valign="top">Predict reactivity on basis of available surface area</td>
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| − | <td width="313" valign="top">Relatively rapid, less expensive</td>
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| − | <td width="319" valign="top">Little information on fine fraction<br />
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| − | No information on "reactive" fraction</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top">Hydrometer</td>
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| − | <td width="313" valign="top">Information on fine fraction</td>
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| − | <td width="319" valign="top">More time consuming, more expensive<br />
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| − | No information on "reactive" fraction</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top">BET method</td>
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| − | <td width="313" valign="top">Sophisticated technique<br />
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| − | Information on "reactive" fraction through measurement of total and specific surface area</td>
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| − | <td width="319" valign="top">Time consuming and expensive<br />
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| − | Requires specialized equipment and personnel</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="3"><strong>Chemical Composition</strong></td>
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| − | <td width="241" valign="top">Digestion using various acids for analysis by multiple quantitative techniques (ICP-AES, ICP-MS, AAS, NAA) </td>
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| − | <td width="252" rowspan="3" valign="top">Determines total potential load of constituents to environment.</td>
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| − | <td width="313" rowspan="3" valign="top">Comparison against site-specific baseline values and reference geologic materials<br />
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| − | Surrogate for and confirmation of ABA parameters (e.g., Ca, S)<br />
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| − | Surrogate for and confirmation of mineralogical composition<br />
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| − | Evaluation of sample set representativeness</td>
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| − | <td width="319" rowspan="3" valign="top">Instrument-specific interferences<br />
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| − | Volatilization<br />
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| − | Elevated detection limits due to dilution </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top">Preparation of bead/powder sample for semi-quantitative analysis by XRF</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top">Portable equipment (XRF)</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137"><strong>Paste pH/Paste Conductivity</strong></td>
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| − | <td width="241" valign="top">Mixture of solution and solid in desired ratio (typically 1:1 to 5:1) followed by pH/electrical conductivity measurement</td>
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| − | <td width="252" valign="top">Determines potential short-term effect of surficial/soluble salts on water quality</td>
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| − | <td width="313" valign="top">Quick, inexpensive, easy to perform in field and laboratory<br />
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| − | Can be useful screening test for operational mine waste classification and management</td>
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| − | <td width="319" valign="top">Lack of ability to predict long-term conditions <br />
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| − | Measures stored acidity </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="12"><strong>Acid Base Accounting (ABA)</strong></td>
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| − | <td width="241" valign="top"><strong><em>Sobek Method</em></strong><br />
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| − | AP commonly from total sulphur<br />
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| − | NP by boiling, HCl to pH 0.8-2.5</td>
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| − | <td width="252" valign="top"><strong>All Methods:</strong><br />
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| − | Establish overall acid generating and acid neutralizing capability of a material through independent determination<br />
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| − | Identification of the need for and samples that require kinetic testing </td>
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| − | <td width="313" valign="top"><strong>All Methods:</strong><br />
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| − | Most techniques well established<br />
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| − | Generally relatively fast and inexpensive<br />
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| − | Provide operational screening criteria for mine waste classification and management </td>
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| − | <td width="319" valign="top"><strong>All Methods:</strong><br />
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| − | Provide no information on relative rates of acid generation and neutralization<br />
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| − | Assume NP and AG sulfur or minerals are completely available for reaction<br />
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| − | Can over- or under-estimate AG or NP depending on method used <br />
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| − | NPR cannot be calculated in the absence of sulphur and sulphide<br />
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| − | Acid addition dependent on a subjective fizz test which can affect accuracy</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Modified Sobek</em></strong><br />
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| − | AP from sulphide sulphur<br />
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| − | NP at ambient temperature for 24 hours near boiling, HCl to pH 2.0-2.5</td>
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| − | <td width="252" valign="top"> </td>
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| − | <td width="313" valign="top">Prevent over-estimation of NP or AP relative to Sobek method</td>
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| − | <td width="319"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Lapakko</em></strong><br />
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| − | NP at ambient temperature up to 1 week, H2SO4 to pH 6.0</td>
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| − | <td width="252"> </td>
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| − | <td width="313"> </td>
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| − | <td width="319"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>BC Research Inc. (BCRI) Initial</em></strong><br />
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| − | NP at ambient temperature for 16-24 hours, H2SO4 to pH 3.5</td>
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| − | <td width="252"> </td>
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| − | <td width="313"> </td>
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| − | <td width="319"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Sobek Siderite Correction</em></strong><br />
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| − | as Sobek, but with H2O2</td>
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| − | <td width="252" valign="top">Accounts for complete oxidation of soluble metals during titration</td>
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| − | <td width="313">ASTM draft method uses sulphuric acid Requires no fizz test<br />
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| − | Uses pH to determine acid addition requirements<br />
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| − | Negative values indicate stored acid</td>
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| − | <td width="319"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Net Carbonate Value (NCV),%CO2</em></strong><br />
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| − | NCV = ANP + AGP, where<br />
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| − | AGP = -1.37[(total sulphur) - (residual sulphur after pyrolysis)]<br />
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| − | ANP = 3.67[(total carbon) - (carb on after HCl digestion)] (=see TIC) </td>
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| − | <td width="252" valign="top">Used principally by Newmont Negative ANP and positive AGP must be corrected to zero <br />
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| − | Negative NCV indicates acid generation potential<br />
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| − | Confirm NCV classification using BC Research Confirmation on zone composites</td>
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| − | <td width="313" valign="top">Standardized as ASTM E-1915 <br />
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| − | Waste rock composites characterized with metallurgical suite for ores <br />
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| − | Several options for sulphide confirmation depending on mineralogy <br />
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| − | Classification system limits uncertainty</td>
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| − | <td width="319" valign="top">Requires carbon-sulphur sophisticated combustion-infrared instrumentation similar to Sobek <br />
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| − | Results require conversion for comparison against data from other ABA tests in order to differentiate methods<br />
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| − | Metal carbonates overestimate ANP<br />
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| − | Does not account for silicate buffering or stored acidity</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Acid Buffering Characteristic Cu</em></strong><strong><em>rve</em></strong> <strong><em>(ABCC)</em></strong><br />
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| − | Titration of sample with acid while continuously monitoring pH </td>
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| − | <td width="252" valign="top">Provides an indication of the portion of the NP that is readily available for neutralization<br />
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| − | Used principally in Australia<br />
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| − | Similar in nature to the BCRI Initial test</td>
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| − | <td width="313" valign="top">Can be used to identify minerals responsible for neutralization by comparing against ABCCs for reference minerals<br />
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| − | Well suited for measuring actual NP vs. total NP<br />
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| − | Represents a less conservative method of measuring NP</td>
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| − | <td width="319" valign="top">Limited operational value<br />
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| − | Limited basis for comparison against results from more "traditional" ABA tests</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Total Inorganic Carbon (TIC)</em></strong><br />
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| − | TIC = (total carbon) - (carbon after HCl digestion)</td>
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| − | <td width="252"> </td>
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| − | <td width="313" valign="top">Measures NP associated with carbonates only</td>
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| − | <td width="319" valign="top">Only provides carbonate fraction of NP<br />
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| − | Can only be used in concert with total NP results<br />
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| − | Will include carbonates that do not contribute NP (e.g., siderite)</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241"><strong><em>Sulphur Analysis<br />
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| − | </em></strong>(total S, pyritic S, sulphide S, organic S, sulphate S, residual S)<br />
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| − | Analysis requires selective digestion of ground sample with acid and measurement of sulphur by infrared or titration after combustion<br />
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| − | Removal of non-sulphide and/or targeted sulphide minerals to determine sulphur species</td>
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| − | <td width="252" valign="top">Potential of samples to generate acid<br />
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| − | Used as part of ABA testing</td>
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| − | <td width="313" valign="top">Distinguishes between sulphur forms and allows identification of "reactive" sulphur species</td>
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| − | <td width="319" valign="top">Does not confirm the identity of the sulphur-bearing mineral(s)<br />
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| − | Can overestimate or underestimate reactive sulphur content</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Chromium Reducible Sulphur</em></strong><br />
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| − | Targets acid-volatile sulphur, elemental sulphur and pyrite sulphur through HCl digestion </td>
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| − | <td width="252" rowspan="3" valign="top">Used principally in Australia</td>
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| − | <td width="313" valign="top">Considered a very reliable method for measuring low-level sulphur concentrations<br />
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| − | Only measures sulphide minerals</td>
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| − | <td width="319" rowspan="3" valign="top">Limited basis for direct comparison against results from more "traditional" ABA tests</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Total Actual Acidity (TAA)</em></strong><br />
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| − | Titration of KCl extract to pH 5.5 with NaOH</td>
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| − | <td width="313" valign="top">Can define actual acidity in low-pH samples that have oxidized </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241"><strong><em>Total Potential Acidity (TPA)</em></strong><br />
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| − | Heating of KCl extract with H2O2 and titration to pH 5.5 with NaOH</td>
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| − | <td width="313"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="4"><strong>Net Acid Generating (NAG)</strong></td>
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| − | <td width="241" valign="top"><strong><em>Single addition NAG</em></strong><br />
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| − | Reaction with H2O2 and titration to pH 4.5 with NaOH</td>
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| − | <td width="252" rowspan="4" valign="top"><strong>All Methods:</strong><br />
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| − | Establishes overall acid generating capability of a material through simultaneous reaction of acid generating and acid neutralizing components<br />
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| − | Identification of the need for and samples that require kinetic testing<br />
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| − | Used principally by Australasian companies </td>
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| − | <td width="313" valign="top"><strong>All Methods:</strong><br />
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| − | Evaluates net acid-base balance<br />
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| − | Can also be used to determine NP<br />
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| − | Generally relatively fast and inexpensive<br />
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| − | Provides operational screening criteria for mine waste classification and management <br />
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| − | Can eliminate false positive BC Research Confirmation results for unreactive materials </td>
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| − | <td width="319" rowspan="4" valign="top"><strong>All Methods:</strong><br />
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| − | Does not distinguish between AP and NP<br />
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| − | Screening method only<br />
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| − | Potential interferences in presence of organic carbon and copper<br />
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| − | May underestimate AP potential in high-sulphide material due to incomplete oxidation<br />
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| − | Sensitive to quality of H2O2 </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Sequential NAG</em></strong><br />
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| − | Multi-stage repeat of single-addition NAG tests until NAG pH is greater than 4.5</td>
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| − | <td width="313" valign="top">Overcomes incomplete oxidation<br />
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| − | Can be used to approximate lag time to acid generation</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Modified NAG</em></strong><br />
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| − | As single addition NAG, but accounts for potential effect from organic matter<br />
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| − | Extended boiling and assay of the NAG solution for S, Ca, Mg and TOC </td>
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| − | <td width="313" valign="top">Accounts for potential effect from organic matter</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Kinetic NAG</em></strong><br />
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| − | As single addition NAG but with monitoring of temperature, pH and EC during reaction with H2O2</td>
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| − | <td width="313" valign="top">Provides an indication of reaction kinetics and lag time</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="6"><strong>Mineralogical Composition</strong></td>
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| − | <td width="241" valign="top"><strong><em>Visual/Optical Microscopy</em></strong><br />
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| − | Hand lens, binocular microscope</td>
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| − | <td width="252" rowspan="6" valign="top"><strong>All Methods:</strong><br />
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| − | Identify primary and secondary minerals that could affect acid generation potential and contact water quality<br />
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| − | With increasing sophistication of techniques, also information on texture, mineral composition and morphology to evaluate mineral reactivity and availability for weathering reactions that can affect acid generation and leaching potential </td>
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| − | <td width="313" valign="top"><strong>All Methods:</strong><br />
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| − | Provide information on acid generating potential and NP, availability of minerals for weathering<br />
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| − | Corroborate lithologic information<br />
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| − | Essential for understanding of geochemical controls on contact water quality and as inputs to geochemical model simulations </td>
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| − | <td width="319" valign="top">Qualitative</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>X-ray diffraction (XRD)</em></strong><br />
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| − | Qualitative or semi-quantitative (Rietveld) analysis</td>
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| − | <td width="313" valign="top"> </td>
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| − | <td width="319" valign="top">Semi-quantitative at best <br clear="all" />
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| − | High detection limit ~1% <br clear="all" />
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| − | Capable of identifying crystalline minerals only</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Petrographic analysis</em></strong><br />
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| − | Reflection or transmission petrographic microscope</td>
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| − | <td width="313" valign="top"> </td>
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| − | <td width="319" rowspan="3" valign="top">Requires sophisticated instrumentation and specialized personnel for interpretation</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>SEM/EDS</em></strong><br />
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| − | Electron beam scan for mineral identification</td>
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| − | <td width="313" valign="top">Surpasses combustion-infrared methods in quantifying trace sulfide mineral concentrations </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Electron microprobe</em></strong><br />
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| − | Like SEM but optimized for chemical analysis </td>
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| − | <td width="313" valign="top"> </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Portable equipment (PIMA)</em></strong><br />
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| − | Infrared analyzer</td>
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| − | <td width="313" valign="top">Portable<br />
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| − | Particularly suited for hydrated minerals</td>
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| − | <td width="319" valign="top">Not capable of identifying all minerals</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="137" rowspan="17"><strong>Short-Term Leach Tests</strong></td>
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| − | <td width="241" valign="top"><strong><em>SPLP (Synthetic Precipitation Leaching Procedure)</em></strong><br />
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| − | US EPA Method 1312<br />
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| − | 20:1 solution to solid<br />
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| − | Deionized water or dilute sulphuric/nitric acid to pH 4.2 or 5.0<br />
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| − | < 9.5 mm <br />
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| − | 18 ± 2 hours<br />
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| − | Variant: <strong><em>Standard Test Method for Shake Extraction of Mining Waste by the Synthetic Precipitation Leaching Procedure</em></strong><br />
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| − | ASTM D 6234</td>
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| − | <td width="252" valign="top"><strong>All Methods:</strong><br />
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| − | Measures readily soluble constituents of mine and process wastes</td>
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| − | <td width="313" valign="top"><strong>All Methods:</strong><br />
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| − | Provides indication of leaching of salts<br />
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| − | Identifies readily dissolvable constituents</td>
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| − | <td width="319" valign="top"><strong>All Methods:</strong><br />
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| − | Provides no information on transient processes and long-term conditions<br />
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| − | only simulates short-term interaction<br />
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| − | high liquid to solid ratio may underestimate leachability<br />
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| − | grain size reduction may increase reactivity</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>TCLP (Toxicity Characteristic Le</em></strong><strong><em>aching Procedure)</em></strong><br />
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| − | US EPA Method 1311<br />
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| − | 20:1 solution to solid ratio<br />
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| − | acetic acid/acetate buffer<br />
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| − | < 9.5 mm <br />
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| − | 18 ± 2 hours </td>
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| − | <td width="252" valign="top">Used to determine if waste is hazardous under RCRA<br />
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| − | Intended to simulate municipal landfill containing organic wastes</td>
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| − | <td width="313" valign="top">Applicable standards available</td>
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| − | <td width="319" valign="top">Use of acetic acid/acetate buffers not appropriate for mining applications, Short list of metals evaluated </td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Meteoric Water Mobility Procedure (MWMP)</em></strong><br />
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| − | 1:1 solution to solid ratio<br />
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| − | reagent-grade water<br />
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| − | < 2 inch<br />
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| − | < 48 hours</td>
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| − | <td width="252" valign="top">Same as for SPLP<br />
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| − | Primarily used in Nevada</td>
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| − | <td width="313" valign="top">Quasi-dynamic test<br />
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| − | More realistic than SPLP due to higher solid to solution ratio, longer duration and coarser material<br />
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| − | Applicable standards available</td>
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| − | <td width="319" valign="top">Weaker lixiviant than acidified SPLP</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>California Waste Extraction Test (WET)</em></strong><br />
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| − | 10:1 solution to solid ratio<br />
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| − | dilute sodium citrate solution<br />
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| − | < 2 mm <br />
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| − | 48 hours </td>
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| − | <td width="252" valign="top">Intended to simulate municipal landfill containing organic wastes <br />
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| − | Primarily used in California</td>
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| − | <td width="313" valign="top">Lower liquid to solid ratio and longer test duration than SPLP and TCLP<br />
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| − | Applicable standards available</td>
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| − | <td width="319" valign="top">Use of sodium citrate not appropriate for mining applications</td>
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| − | </tr>
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| − | <tr>
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| − | <td width="241" valign="top"><strong><em>Modified Test for Shake Extraction of Solid Waste with Water</em></strong><br />
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| − | 4:1 solution to solid ratio<br />
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| − | reagent-grade water adjusted to pH 5.5 with carbonic acid<br />
| |
| − | 18 hours </td>
| |
| − | <td width="252" valign="top">Same as for SPLP</td>
| |
| − | <td width="313" valign="top">Lower liquid to solid ratio than SPLP</td>
| |
| − | <td width="319" valign="top"> </td>
| |
| − | </tr>
| |
| − | <tr>
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| − | <td width="241" valign="top"><strong><em>British Columbia Special Waste Extraction Procedure (BC SWEP)</em></strong><br />
| |
| − | 20:1 solution to solid ratio<br />
| |
| − | acetic acid<br />
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| − | < 9.5 mm <br />
| |
| − | 24 hours<br />
| |
| − | <strong><em>Modification for mining </em></strong><strong><em>wastes</em></strong> <br />
| |
| − | 3:1 solution to solid ratio<br />
| |
| − | dilute hydrochloric acid </td>
| |
| − | <td width="252" valign="top">Similar to TCLP for normal procedure<br />
| |
| − | Similar to SPLP and ASTM for modified procedure</td>
| |
| − | <td width="313" valign="top">Modified: lower solution to solid ratio than SPLP and ASTM</td>
| |
| − | <td width="319" valign="top">Intended to simulate municipal landfill containing organic wastes <br />
| |
| − | Same as for SPLP</td>
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| − | </tr>
| |
| − | <tr>
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| − | <td width="241" valign="top"><strong><em>NAG Test with Leachate Analysis</em></strong><br />
| |
| − | 100:1 solution to solid ratio<br />
| |
| − | 15% H2O2 solution<br />
| |
| − | < 75 um <br />
| |
| − | Until boiling or effervescing ceases</td>
| |
| − | <td width="252" valign="top">Can be used to determine "terminal" water quality after complete oxidation of reactive sulphides</td>
| |
| − | <td width="313" valign="top">"Short-cut" to terminal conditions</td>
| |
| − | <td width="319" valign="top">Leachate contains all reaction products from sulphide oxidation<br />
| |
| − | High solution to solid ratio<br />
| |
| − | Significant grain size reduction</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Characterization of Waste - Leaching - Compliance Test for Leaching of Granular Materials and Sludge</em></strong><br />
| |
| − | EN 12457 1<br />
| |
| − | One stage test<br />
| |
| − | 2:1 solution to solid ratio<br />
| |
| − | < 4 mm <br />
| |
| − | EN 12457-2<br />
| |
| − | One stage test<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | < 4 mm <br />
| |
| − | EN 12457-3<br />
| |
| − | Two stage test<br />
| |
| − | 2:1 and 8:1 solution to solid ratios<br />
| |
| − | < 4 mm <br />
| |
| − | EN 12457-4<br />
| |
| − | One stage test<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | < 10 mm <br />
| |
| − | <strong>All Methods:</strong><br />
| |
| − | distilled/demineralized/deionized water<br />
| |
| − | 24 hours</td>
| |
| − | <td width="252" valign="top"><strong>All European Union (EU) Methods:</strong><br />
| |
| − | Basic characterization: obtain information on leaching behavior and characteristics<br />
| |
| − | Compliance: determine whether waste complies with specific reference values </td>
| |
| − | <td width="313" valign="top"><strong>All European Union (EU) Methods:</strong><br />
| |
| − | Test protocol is adjusted based on information needs and site-specific conditions<br />
| |
| − | Applicable standards available (expressed as loadings) </td>
| |
| − | <td width="319" valign="top">Same as for SPLP</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Characterization of Waste - Leaching </em></strong><strong><em>Behavior</em></strong><strong><em> Tests - Up-flow Percolation Test</em></strong><br />
| |
| − | CEN/TS 14405<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | < 10 mm <br />
| |
| − | demineralized water<br />
| |
| − | duration as needed </td>
| |
| − | <td width="252" valign="top">Used to determine leachability of a waste under hydraulically dynamic conditions (EU)</td>
| |
| − | <td width="313" valign="top">Test can be used to establish the distinction between various release mechanisms (e.g., first flush vs. steady state leaching)</td>
| |
| − | <td width="319" valign="top">Same as for MWMP<br />
| |
| − | Test developed for landfills</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Characterization of Waste - Leaching </em></strong><strong><em>Behavior</em></strong><strong><em> Tests - Influence of pH on Leaching with Initial Acid/Base</em></strong> Addition<br />
| |
| − | CEN/TS 14429<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | at least 8 individual solutions of different pH using nitric acid or sodium hydroxide covering the range pH 4-12<br />
| |
| − | 95% < 1 mm<br />
| |
| − | 48 hours</td>
| |
| − | <td width="252" valign="top">Used to determine influence of pH on waste leachability and buffering capacity (EU)</td>
| |
| − | <td width="313" valign="top">Leachate analyzed for inorganic constituents (as opposed to prCEN/TS 15364)<br />
| |
| − | pH is allowed to fluctuate after initial addition of acid or base<br />
| |
| − | Allows evaluation of buffering capacity</td>
| |
| − | <td width="319" valign="top">Same as for SPLP<br />
| |
| − | Test developed for landfills</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Characterization of Waste - Leaching </em></strong><strong><em>Behavior</em></strong><strong><em> Tests - Influence of pH on Leaching with Continuous pH-Control</em></strong><br />
| |
| − | EN 14997<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | at least 8 individual solutions of different pH using nitric acid or sodium hydroxide covering the range pH 4-12<br />
| |
| − | 95% < 1 mm<br />
| |
| − | 48 hours</td>
| |
| − | <td width="252" valign="top">Used to determine influence of pH on waste leachability (EU)</td>
| |
| − | <td width="313" valign="top">Leachate analyzed for inorganic constituents (as opposed to prCEN/TS 15364)<br clear="all" />
| |
| − | pH is maintained at constant value after initial addition of acid or base<br clear="all" />
| |
| − | Allows evaluation of leachability under constant pH</td>
| |
| − | <td width="319" valign="top">Same as for SPLP<br clear="all" />
| |
| − | Test developed for landfills</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Characterization of Waste - Leaching </em></strong><strong><em>Behavior</em></strong><strong><em> Tests - Acid and Base </em></strong><strong><em>Neutralization</em></strong><strong><em> Capacity Test</em></strong><br />
| |
| − | CEN/TS 15364<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | at least 8 individual solutions of different pH using nitric acid or sodium hydroxide covering the range pH 4-12<br />
| |
| − | 95% < 1 mm<br />
| |
| − | 48 hours </td>
| |
| − | <td width="252" valign="top">Used to determine final pH of a waste as well as assess consequences of external influences (carbonation, oxidation) on the final pH (EU)</td>
| |
| − | <td width="313" valign="top"> </td>
| |
| − | <td width="319" valign="top">Same as for SPLP<br />
| |
| − | Test developed for landfills<br />
| |
| − | Leachate only analyzed for pH</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Lixiviação de Resíduos</em></strong><br />
| |
| − | NBR 10005<br />
| |
| − | 16:1 solution to solid ratio<br />
| |
| − | acetic acid<br />
| |
| − | < 9.5 mm <br />
| |
| − | 24 hours</td>
| |
| − | <td width="252" valign="top">Used to determine if mine waste is hazardous under solid waste regulations (Brazil)<br />
| |
| − | Intended to simulate municipal landfill containing organic wastes</td>
| |
| − | <td width="313" valign="top">Applicable standards available</td>
| |
| − | <td width="319" valign="top">Use of acetic acid not appropriate for mining applications</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Solubilização de Resíduos</em></strong><br />
| |
| − | NBR 10006<br />
| |
| − | 4:1 solution to solid ratio<br />
| |
| − | deionized water<br />
| |
| − | grain size not specified<br />
| |
| − | 7 d<strong>ays</strong></td>
| |
| − | <td width="252" valign="top">Used to evaluate potential for impacts to groundwater by comparison against groundwater quality standards (Brazil)</td>
| |
| − | <td width="313" valign="top">Applicable standards available<br />
| |
| − | Lower solution to solid ratio and longer duration than SPLP</td>
| |
| − | <td width="319" valign="top">Same as for SPLP</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Test Method Standard for Leaching Toxicity of Solid Wastes - Roll Over Leaching Procedure</em></strong><br />
| |
| − | GB5086.1-1997<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | deionized/distilled water<br />
| |
| − | < 5 mm <br />
| |
| − | 18 hours </td>
| |
| − | <td width="252" valign="top">Used to determine if mine waste is hazardous under solid waste regulations by comparison against Integrated Wastewater Discharge Standards (China)</td>
| |
| − | <td width="313" valign="top">Applicable standards available</td>
| |
| − | <td width="319" valign="top">Same as for SPLP</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Test Method Standard for Leaching Toxicity of Solid Wastes - Horizontal Vibration Extraction Proc</em></strong><strong><em>edure</em></strong><br />
| |
| − | GB5086.2-1997<br />
| |
| − | 10:1 solution to solid ratio<br />
| |
| − | deionized/distilled water<br />
| |
| − | < 3 mm <br />
| |
| − | 24 hours </td>
| |
| − | <td width="252" valign="top">Used to determine if mine waste is hazardous under solid waste regulations by comparison against Integrated Wastewater Discharge Standards (China)</td>
| |
| − | <td width="313" valign="top">Applicable standards available</td>
| |
| − | <td width="319" valign="top">Same as for SPLP</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Sequential Extraction<br />
| |
| − | </em></strong>Variety of methods using different extractants to evaluate leachability from targeted fractions of mine waste<br />
| |
| − | Methods may vary depending on analyte of interest and target fraction of interest</td>
| |
| − | <td width="252" valign="top">To evaluate associations between constituents of interests and different fractions of the solid<br />
| |
| − | Allows for determination of the labile portion of the solid phase</td>
| |
| − | <td width="313" valign="top">Understanding associations of constituents with different fractions of the solid assists in understanding geochemical conditions under which they may be released to the environment</td>
| |
| − | <td width="319" valign="top">Involved procedure<br />
| |
| − | Many reagents<br />
| |
| − | Most reagents not uniquely selective to targeted fraction<br />
| |
| − | Use of some reagents precludes analysis of certain constituents<br />
| |
| − | No applicable standards</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="137" rowspan="2"><strong>Long-Term Leach Tests</strong></td>
| |
| − | <td width="241" valign="top"><strong><em>Humidity Cell Test (HCT)</em></strong><br />
| |
| − | ASTM D5744-96<br />
| |
| − | 0.5:1 or 1:1 solution to solid ratio<br />
| |
| − | deionized water<br />
| |
| − | different dimensions for < 6.3 mm and <150 μm<br />
| |
| − | weekly cycle of 3-day alternating dry air and wet air followed by leach<br />
| |
| − | generally 20-week minimum but can run longer<br />
| |
| − | weekly analysis of diagnostic ARD parameters (e.g., pH, SC, Fe, SO4, Eh, Ca, Mg, alkalinity)<br />
| |
| − | generally less-frequent analysis for comprehensive metals and major ions </td>
| |
| − | <td width="252" valign="top">To determine long-term weathering rates (sulphide oxidation, dissolution of neutralizing minerals, trace metal release) under oxygenated conditions<br />
| |
| − | To evaluate lag time to acid generation<br />
| |
| − | To provide reaction rates for geochemical modeling</td>
| |
| − | <td width="313" valign="top">Standardized test<br />
| |
| − | Provides kinetic and steady-state leaching information and is recommended test for determination of weathering rates of primary minerals</td>
| |
| − | <td width="319" valign="top">Not suitable for evaluation of saturated materials<br />
| |
| − | Grain size reduction may increase reactivity</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Column Test</em></strong><br />
| |
| − | variable solution to solid ratio<br />
| |
| − | generally deionized water, groundwater or natural precipitation<br />
| |
| − | generally < 25 mm<br />
| |
| − | variable dimension, but generally larger than HCT<br />
| |
| − | leaching cycles can vary and include maintaining water over sample, alternate flooding and draining, and recirculating leachate </td>
| |
| − | <td width="252" valign="top">As above, but can simulate leaching in variably saturated or oxygen-deficient conditions<br />
| |
| − | To simulate environmental performance of amended mine wastes and/or cover designs</td>
| |
| − | <td width="313" valign="top">Frequently closer to field conditions than HCT<br />
| |
| − | Can simulate different degrees of saturation<br />
| |
| − | Can simulate remedial alternatives<br />
| |
| − | Simulates combined weathering of primary and secondary minerals</td>
| |
| − | <td width="319" valign="top">Not standardized<br />
| |
| − | Potential for channeling through preferential flowpaths<br />
| |
| − | Grain size reduction may increase reactivity<br />
| |
| − | Without entire load of weathering products from primary minerals, reaction rates for primary minerals and extent of secondary precipitation cannot be measured</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="137" rowspan="3"><strong>Field Tests</strong></td>
| |
| − | <td width="241" valign="top"><strong><em>Wall Washing</em></strong><br />
| |
| − | 1L rinse of 1 × 1 m surface area<br />
| |
| − | distilled water</td>
| |
| − | <td width="252" rowspan="3" valign="top"><strong>All Methods:</strong><br />
| |
| − | To estimate long-term potential of mine materials to generate acid and leach metals using on-site materials </td>
| |
| − | <td width="313" valign="top">Rapid<br />
| |
| − | Measures leachate quality from in situ material<br />
| |
| − | Can be repeated to obtain temporal component</td>
| |
| − | <td width="319" valign="top">May be difficult to establish accurate mass balance due to loss of solution</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>US Geological Survey Field Leach Test (FLT)</em></strong><br />
| |
| − | 20:1 solution to solid ratio<br />
| |
| − | deionized water<br />
| |
| − | < 2 mm <br />
| |
| − | 5 minutes </td>
| |
| − | <td width="313" valign="top">Can be performed in the field<br />
| |
| − | Rapid and inexpensive method to characterize chemical reactivity and water-soluble fraction<br />
| |
| − | Field screening method that can be used as surrogate for SPLP due to similarity in approach and results</td>
| |
| − | <td width="319" valign="top">Same as for SPLP</td>
| |
| − | </tr>
| |
| − | <tr>
| |
| − | <td width="241" valign="top"><strong><em>Field Cells/Test Pads/Mine Facilities</em></strong><br />
| |
| − | Monitoring of increasingly larger volumes of mine wastes<br />
| |
| − | Ambient precipitation or irrigation<br />
| |
| − | Degree of grain size reduction required decreases with increasing size of test<br />
| |
| − | Test duration months to years </td>
| |
| − | <td width="313" valign="top">Test are conducted under actual field conditions<br />
| |
| − | Can collect samples after transient events<br />
| |
| − | Larger sample size results in enhanced test charge representativeness<br />
| |
| − | With increasing test size, effects from grain size reduction, sample heterogeneity and preferential pathways reduced<br />
| |
| − | With increasing test size, empirical results increasingly directly applicable to mine facility</td>
| |
| − | <td width="319" valign="top">Comprehensive characterization of test sample may not be feasible<br />
| |
| − | Complete understanding of water balance may not be feasible<br />
| |
| − | Complexity of tested system may limit interpretive and predictive value of observations</td>
| |
| − | </tr>
| |
| − | </table>
| |
