ASTM D8187-18

Standard Guide for Interpretation of Standard Humidity Cell Test Results

SIGNIFICANCE AND USE
4.1 Use of HCT Data and Testing Objectives—The laboratory weathering test method (D5744) generates data that can be used to:  
4.1.1 Determine whether a solid material will produce an acidic, alkaline, or neutral effluent;  
4.1.2 Identify solutes in the effluent that represent dissolved weathering products formed during a specified period of time, and inform the user of their potential to produce environmental impacts at a mining or metallurgical processing site under proposed operating conditions;  
4.1.3 Determine the mass of solute release; and  
4.1.4 Determine the rate at which solutes are released (from the solids into the effluent) under the closely controlled conditions of the test for comparison to other materials.  
4.1.5 These approaches are based on the existence of detailed mineralogical work and static tests that provide a basis for interpreting HCT results.  
4.1.6 Detailed mineralogical work might lead a reviewer to suspect either acid neutralization potential (ANP) or acid generation potential (AGP) minerals have questionable availability, which would be a significant factor in interpreting HCT results and decisions concerning test duration.  
4.2 Interpretation of data generated by the laboratory weathering procedure can be used to address the following objectives:  
4.2.1 Determine the variation of drainage quality as a function of compositional variations (for example, iron sulfide and calcium plus magnesium carbonate contents) within individual mine rock lithologies;  
4.2.2 Determine the amount of acid that can be neutralized by the sample while maintaining a drainage pH of ≥6.0 under the conditions of the test;  
4.2.3 Estimate mine rock weathering rates to aid in predicting the environmental behavior of mine rock; and  
4.2.4 Determine mine rock weathering rates to aid in experimental design of site-specific kinetic tests.  
4.3 Interpretation Approaches—Guides A, B, and C are intended as examples of what to consider in developin...
SCOPE
1.1 This kinetic test guide covers interpretation and cooperative management of a standard laboratory weathering procedure, Test Method D5744. The guide suggests strategies for analysis and interpretation of data produced by Test Method D5744 on mining waste rock, metallurgical processing wastes, and ores.  
1.1.1 Cooperative management of the testing involves agreement of stakeholders in defining the objectives of the testing, analytical requirements, planning the initial estimate of duration of the testing, and discussion of the results at decision points to determine if the testing period needs to be extended and the disposition of the residues.  
1.2 The humidity cell test (HCT) enhances reaction product transport in the aqueous leach of a solid material sample of specified mass. Standard conditions allow comparison of the relative reactivity of materials during interpretation of results.  
1.3 The HCT measures rates of weathering product mass release. Soluble weathering products are mobilized by a fixed-volume aqueous leach that is performed and collected weekly. Leachate samples are analyzed for pH, alkalinity/acidity, specific conductance, sulfates, and other selected analytes which may be regulated in the environmental drainage at a particular mining or metallurgical processing site.  
1.4 This guide covers the interpretation of standard humidity cell tests conducted to obtain results for the following objectives:    
Guide and Objective  
Sections  
A – Confirmation of Static Testing Results  
5 – 6  
B – Evaluation of Reactivity and Leachate Quality
for Segregating Mine, Processing Waste, or
Ore  
7 – 8  
C – Evaluation of Quality of Neutralization
Potential Available to React with Produced
Acid  
9 – 10  
1.5 This guide is intended to facilitate use of Test Method D5744 to meet kinetic testing regulatory requirements for metallurgical processing products, mining waste ...

General Information

• Status: Published
• Publication Date: 31-Mar-2018
• ICS: 13.030.10 - Solid wastes
• ICS: 19.040 - Environmental testing
• Technical Committee: D34 - Waste Management
• Drafting Committee: D34.01.04 - Waste Leaching Techniques

Relations

• Refers: ASTM D5681-23 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2023
• Refers: ASTM E1915-20 - Standard Test Methods for Analysis of Metal Bearing Ores and Related Materials for Carbon, Sulfur, and Acid-Base Characteristics
• Effective Date: 01-Jul-2020
• Refers: ASTM D5681-18 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2018
• Refers: ASTM D5681-17 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Sep-2017
• Refers: ASTM D5681-16a - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Nov-2016
• Refers: ASTM D5681-16 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Feb-2016
• Refers: ASTM D5744-13 - Standard Test Method for Laboratory Weathering of Solid Materials Using a Humidity Cell
• Effective Date: 01-Sep-2013
• Refers: ASTM D5744-13e1 - Standard Test Method for Laboratory Weathering of Solid Materials Using a Humidity Cell
• Effective Date: 01-Sep-2013
• Refers: ASTM D5681-13 - Standard Terminology for Waste and Waste Management
• Effective Date: 01-Feb-2013
• Refers: ASTM E2242-12a - Standard Test Method for Column Percolation Extraction of Mine Rock by the Meteoric Water Mobility Procedure
• Effective Date: 01-Dec-2012
• Refers: ASTM E2242-12 - Standard Test Method for Column Percolation Extraction of Mine Rock by the Meteoric Water Mobility Procedure
• Effective Date: 01-Jun-2012
• Refers: ASTM E2242-12e1 - Standard Test Method for Column Percolation Extraction of Mine Rock by the Meteoric Water Mobility Procedure
• Effective Date: 01-Jun-2012
• Refers: ASTM D5744-12 - Standard Test Method for Laboratory Weathering of Solid Materials Using a Humidity Cell
• Effective Date: 15-Feb-2012
• Refers: ASTM E1915-11 - Standard Test Methods for Analysis of Metal Bearing Ores and Related Materials for Carbon, Sulfur, and Acid-Base Characteristics
• Effective Date: 01-Nov-2011
• Refers: ASTM E1915-09 - Standard Test Methods for Analysis of Metal Bearing Ores and Related Materials for Carbon, Sulfur, and Acid-Base Characteristics
• Effective Date: 01-Dec-2009

Overview

ASTM D8187-18: Standard Guide for Interpretation of Standard Humidity Cell Test Results provides guidance for analyzing and interpreting data from Standard Humidity Cell Tests (HCT) performed using ASTM D5744. The guide helps stakeholders manage and interpret laboratory weathering procedures to predict drainage quality and environmental impacts of mining waste rock, metallurgical processing wastes, and ores. By standardizing the interpretation of kinetic test results, ASTM D8187-18 supports stakeholders in making informed decisions related to mine waste management, environmental permitting, and regulatory compliance.

Key Topics

• Purpose of HCT: The humidity cell test is a laboratory procedure designed to simulate the weathering of solid materials (such as mine rock or processing waste) under controlled conditions and to measure the release rates of weathering products. The test results inform predictions related to acid generation or neutralization, solute mobility, and potential environmental impact.
• Stakeholder Management: The standard emphasizes cooperative management involving agreement among stakeholders (mining companies, regulators, consultants) to define test objectives, analytical parameters, estimate testing durations, and hold decision points throughout the testing process.
• Interpretation Approaches:
  • Confirmation of Static Testing Results: Verifies outcomes of static tests using laboratory weathering data.
  • Evaluation of Reactivity and Leachate Quality: Assesses material classification, reactivity, and resultant drainage quality to inform ore and waste segregation.
  • Assessment of Neutralization Potential: Measures the acid neutralization capacity of materials and supports decision making for waste management planning.
• Data Analysis: Weekly leachate is analyzed for parameters such as pH, alkalinity/acidity, specific conductance, sulfates, and regulated analytes (e.g., metals), forming the basis for environmental impact assessments.
• Decision Criteria: The guide offers strategies for establishing test durations, end points, and decision points (when to continue or modify testing), tailored to the mineralogical and site-specific characteristics of the materials tested.

Applications

• Mine Site Characterization: Supports the classification of mine rock and wastes based on their potential to generate acid, release metals, or neutralize acid, using comparative kinetic test results.
• Environmental Permitting and Compliance: Helps mining operators and regulators assess compliance with environmental regulations regarding drainage quality, metal leaching, and site water management.
• Design of Waste Management Plans: Data from humidity cell tests interpreted using ASTM D8187-18 inform the segregation of ore, mine waste, and processing residues, aiding in the design of disposal and stockpiling strategies.
• Predictive Modeling: Provides input data for models that predict the long-term environmental behavior of waste materials under field conditions, supporting risk assessment and management.
• Performance Monitoring: Long-term monitoring strategies for permitted facilities can be developed by integrating humidity cell performance databases with actual facility drainage data.

Related Standards

• ASTM D5744: Test Method for Laboratory Weathering of Solid Materials Using a Humidity Cell (primary procedure for HCT referenced by D8187-18).
• ASTM D5681: Terminology for Waste and Waste Management.
• ASTM D6234: Test Method for Shake Extraction of Mining Waste by the Synthetic Precipitation Leaching Procedure.
• ASTM E1915: Analysis of Metal Bearing Ores and Related Materials for Carbon, Sulfur, and Acid-Base Characteristics.
• ASTM E2242: Test Method for Column Percolation Extraction of Mine Rock by the Meteoric Water Mobility Procedure.

Practical Value

By providing a systematic and flexible framework for interpreting humidity cell test results, ASTM D8187-18 ensures consistent decision-making and documentation, enhances environmental stewardship, and facilitates regulatory approval processes for mining and metallurgical projects. Consistent application of this standard supports sustainable resource development by helping identify potential environmental risks before they materialize, ensuring proactive management, and optimizing the long-term performance of waste containment strategies.

Keywords: humidity cell test, mine waste, environmental testing, kinetic test, acid generation potential, leachate quality, ASTM D8187-18, ASTM D5744, mining waste management, regulatory compliance.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D8187 − 18
Standard Guide for
Interpretation of Standard Humidity Cell Test Results
This standard is issued under the fixed designation D8187; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.5 This guide is intended to facilitate use of Test Method
D5744 to meet kinetic testing regulatory requirements for
1.1 This kinetic test guide covers interpretation and coop-
metallurgical processing products, mining waste rock, and ores
erative management of a standard laboratory weathering
sized to pass a 6.3-mm (0.25-in.) Tyler screen.
procedure, Test Method D5744. The guide suggests strategies
1.5.1 Interpretation of standard humidity cell test results has
foranalysisandinterpretationofdataproducedbyTestMethod
been found to be useful for segregation of ore and waste and
D5744 on mining waste rock, metallurgical processing wastes,
design of proper stockpiling and disposal facilities.
and ores.
1.1.1 Cooperative management of the testing involves 1.6 Interlaboratory testing of the standard D5744 humidity
agreement of stakeholders in defining the objectives of the cell has been confined to mine waste rock. Application of this
testing, analytical requirements, planning the initial estimate of guide to metallurgical processing waste (for example, mill
duration of the testing, and discussion of the results at decision process tailings) is not supported by interlaboratory test data.
points to determine if the testing period needs to be extended Method B of Test Method D5744, however, has been found
and the disposition of the residues.
useful for testing of metallurgical products, and this guide is
also useful for interpretation of those results (1).
1.2 The humidity cell test (HCT) enhances reaction product
transport in the aqueous leach of a solid material sample of
1.7 Thisguideisintendedtodescribevariousproceduresfor
specified mass. Standard conditions allow comparison of the interpreting the results from standard laboratory weathering of
relative reactivity of materials during interpretation of results.
solid materials in accordance with Test Method D5744. It does
not describe all types of sampling and analytical requirements
1.3 The HCT measures rates of weathering product mass
that may be associated with its application, nor all procedures
release. Soluble weathering products are mobilized by a
for interpretation of results.
fixed-volume aqueous leach that is performed and collected
weekly. Leachate samples are analyzed for pH, alkalinity/ 1.8 The values stated in SI units are to be regarded as
acidity, specific conductance, sulfates, and other selected
standard. No other units of measurement are included in this
analyteswhichmayberegulatedintheenvironmentaldrainage guide.
at a particular mining or metallurgical processing site.
1.8.1 Exception—The values given in parentheses are for
information only.
1.4 This guide covers the interpretation of standard humid-
ity cell tests conducted to obtain results for the following 1.9 This standard does not purport to address all of the
objectives: safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
Guide and Objective Sections
A – Confirmation of Static Testing Results 5 – 6
priate safety, health, and environmental practices and deter-
B – Evaluation of Reactivity and Leachate Quality
mine the applicability of regulatory limitations prior to use.
for Segregating Mine, Processing Waste, or 7 – 8
1.10 This international standard was developed in accor-
Ore
C – Evaluation of Quality of Neutralization
dance with internationally recognized principles on standard-
Potential Available to React with Produced 9 – 10
ization established in the Decision on Principles for the
Acid
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
This guide is under the jurisdiction of ASTM Committee D34 on Waste
Management and is the direct responsibility of Subcommittee D34.01.04 on Waste
Leaching Techniques.
Current edition approved April 1, 2018. Published May 2018. Originally The boldface numbers in parentheses refer to a list of references at the end of
approved in 2018. DOI: 10.1520/D8187-18. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8187 − 18
2. Referenced Documents 4. Significance and Use
4.1 Use of HCT Data and Testing Objectives—The labora-
2.1 ASTM Standards:
toryweatheringtestmethod(D5744)generatesdatathatcanbe
D5681 Terminology for Waste and Waste Management
used to:
D5744 Test Method for Laboratory Weathering of Solid
4.1.1 Determine whether a solid material will produce an
Materials Using a Humidity Cell
acidic, alkaline, or neutral effluent;
D6234 Test Method for Shake Extraction of Mining Waste
4.1.2 Identify solutes in the effluent that represent dissolved
by the Synthetic Precipitation Leaching Procedure
weathering products formed during a specified period of time,
E1915 Test Methods forAnalysis of Metal Bearing Ores and
and inform the user of their potential to produce environmental
Related Materials for Carbon, Sulfur, and Acid-Base
impacts at a mining or metallurgical processing site under
Characteristics
proposed operating conditions;
E2242 Test Method for Column Percolation Extraction of
4.1.3 Determine the mass of solute release; and
Mine Rock by the Meteoric Water Mobility Procedure
4.1.4 Determine the rate at which solutes are released (from
the solids into the effluent) under the closely controlled
3. Terminology
conditions of the test for comparison to other materials.
3.1 Definitions—For definitions of terms used in this guide,
4.1.5 These approaches are based on the existence of
see Terminology D5681.
detailed mineralogical work and static tests that provide a basis
for interpreting HCT results.
3.2 Definitions of Terms Specific to This Standard:
4.1.6 Detailed mineralogical work might lead a reviewer to
3.2.1 acid concentration present (ACP), n—in static acid-
suspect either acid neutralization potential (ANP) or acid
base classification, an estimate of mineral acidity determined
generation potential (AGP) minerals have questionable
by titration of a sample slurry with water.
availability, which would be a significant factor in interpreting
3.2.2 acid generation potential (AGP), n—in static acid-
HCT results and decisions concerning test duration.
base classification, an estimate of sulfidic mineral content
4.2 Interpretationofdatageneratedbythelaboratoryweath-
determined from mineralogy or the sulfide sulfur content.
ering procedure can be used to address the following objec-
tives:
3.2.3 acid neutralization potential (ANP), n—in acid-base
4.2.1 Determine the variation of drainage quality as a
classification, an estimate of basic mineral content determined
function of compositional variations (for example, iron sulfide
from mineralogy, the carbonate carbon content, or acid neu-
and calcium plus magnesium carbonate contents) within indi-
tralization potential acidity titration result. The preferred esti-
vidual mine rock lithologies;
mate for use is based on the capacity of the mineral to maintain
4.2.2 Determine the amount of acid that can be neutralized
circumneutral pH as it dissolves.
by the sample while maintaining a drainage pH of ≥6.0 under
3.2.4 adaptive management plan (AMP), n—in environmen-
the conditions of the test;
tal kinetic testing, a structured, iterative process of robust
4.2.3 Estimate mine rock weathering rates to aid in predict-
decision making in the face of uncertainty, with an aim to
ing the environmental behavior of mine rock; and
reduce uncertainty over time via system monitoring.
4.2.4 Determine mine rock weathering rates to aid in
3.2.5 decision point, n—in management of a humidity cell experimental design of site-specific kinetic tests.
test operation, a point in time during the operation of a
4.3 Interpretation Approaches—Guides A, B, and C are
humidity cell that is selected, during the planning stage, for the
intended as examples of what to consider in developing an
stakeholders to meet and make decisions on whether to
approach for determining how reasonable objectives for hu-
continue or modify the operation of the test.
midity cells might be structured, and some possible criteria for
cooperative management of HCTs involving stakeholders.
3.2.6 humidity cell performance database, n—a compilation
4.3.1 It is also possible to use an approach to establish a
of: (1) tested rock sample, mining waste, ore, or metallurgical
decision point, rather than an end point, to the humidity cell
tailings characterization; (2) completed sample collection rep-
test during the planning stage. Guides A, B, and C are
resenting the geological classifications and acid-base charac-
examples of techniques and associated criteria comprising
teristics; and (3) humidity cell field weathering test reports, for
some approaches to help interpret data generated by humidity
use in planning and interpretation of HCTs.
cell tests. Decision points can be established during the
3.2.7 mining waste, n—overburden or waste rock excavated
planning stage to allow stakeholders an opportunity to review
and disposed of during mining operations.
the results and decide if additional weathering cycles are
needed to meet the objectives of the testing.
3.3 Symbols—Variableslistedinthisguidearedefinedinthe
4.3.2 Continuation of the HCT beyond the decision point
individual sections in which they are discussed.
may or may not provide important information regarding the
acceleration or deceleration of oxidation and metal leaching in
the material being tested.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.3.3 More detailed leachate information from a longer
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
HCT may be critical information for designing waste manage-
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. ment or water treatment facilities as accounted for in anAMP,
D8187 − 18
but an agreed-upon endpoint of test objectives would allow for 4.8 Performance monitoring of permitted facilities can be a
a decision that advances mine planning and permitting. critical element in the development of a humidity cell perfor-
mance database, as well as support for the evolving HCT
4.3.4 The laboratory weathering procedure provides condi-
weathering cycle duration criteria and approach proposed here.
tions conducive to oxidation of solid material constituents and
enhances the transport of weathering reaction products con-
4.9 A humidity cell performance database could be devel-
tained in the resulting weekly effluent.This is accomplished by
oped in a standard format to allow comparison of laboratory
controlling the exposure of the solid material sample to such
weathering results with drainage from field waste facility
environmentalparametersasreactionenvironmenttemperature
performance, based on publicly available information.
and application rate of water and oxygen.
4.9.1 A model approach with possible objectives and crite-
4.3.5 Because efficient removal of reaction products is vital
ria are presented below as examples to help interpret HCT
to track mineral dissolution rates during the procedure, labo-
results.
ratoryleachvolumesarelargeperunitmassofrocktopromote
4.10 Variations in specific approach requirements and crite-
the rinsing of weathering reaction products from the mine rock
ria (% sulfur, sulfide sulfur, carbonate, pH, sulfate release, etc.)
sample.Interpretationoflaboratorykinetictestsbycomparison
will depend on the site-specific objectives, deposit mineralogy,
with field tests has shown that more reaction products from
and characterization, including various static test results and
mineral dissolution are consistently released per unit weight
management plans agreed upon by stakeholders.
and unit time in laboratory weathering tests (2). For example,
4.10.1 Regardlessofthesite-specificstakeholderobjectives,
sulfate release rates observed in laboratory tests of metal mine
instability in metal release rates should strongly suggest
rock have been reported to be three to eight times those for
continuation of weathering cycle testing.
small-scale field test piles of Duluth complex rock (3), and
4.10.2 Regardless of the decision process followed, the
from two to 20 times those for small-scale field test piles of
ultimate responsibility for the permitting decision lies with the
Archean greenstone rock (4). A greater increase is anticipated
permitting agency(s), and the ultimate environmental liability
when laboratory rates are compared with field rates measured
and operating responsibility lies with the mining company.
from operational waste rock piles.
4.11 These approaches are suggested as a model to be used
4.4 In some cases, it may be useful to establish criteria for
by the involved stakeholders for their determination of when it
a decision to end the weathering cycles for a particular cell
is appropriate to schedule and extend HCT weathering cycles
based on HCT results but still continue to maintain the HCT
and how to treat the residues.
test weathering cycles for a longer duration.
–2
4.12 The specific parameters (sulfur, CaCO,SO release
3 4
4.4.1 In other cases, it might be useful to have duplicate
rates, metal release rates, etc.) involved will likely vary
HCTs and use one as a basis for a decision point and
depending on site-specific factors, which could include the
subsequent destructive evaluation of reaction products.
lithology, petrology and mineralogy, climate, regulatory
4.4.1.1 The duplicate cell could be maintained to confirm
approach,environmentalriskfortheunits,andoredeposittype
the basis for the decision and be used to update the AMP and
being evaluated.
financial guarantee, if necessary.
4.13 The criteria selected for management of the duration of
4.4.2 This approach supports a decision concerning mine
HCTs should rely on a combination of parameters, as any
waste management and planning, including an AMP.
criteria based on a single parameter value like % sulfur will not
4.4.3 This approach does not necessarily resolve the need
be reliable (5).
for accurate prediction of long-term metal leaching and drain-
4.14 Thevaluesintheapproachespresentedarechosenonly
age quality, but is recommended as a tool for making decisions
as examples, and actual cell management criteria are intended
on how to conduct testing with the objective of determining
to be reviewed and agreed upon by the stakeholders, on a
how ore and waste will be handled and monitored, and the
site-specific basis.
potential level of risk involved in related decisions for specific
sites and materials.
4.15 The specific parameters and values selected might vary
considerably depending on site-specific factors, which might
4.5 Continuing HCT weathering cycles for an extended
include environmental risk. It is up to the stakeholders to
period of time may also provide a higher level of certainty.
modifyandusethisapproachtodevelopobjectiveswhichmeet
4.6 Depending on the site-specific resources at risk and
the specific requirements at their site and to use their modifi-
behavior of waste materials, an extended HCT weathering
cations to reach a consensus on test duration.
cycle duration may be an important consideration for stake-
4.16 The following decision criteria (sulfide sulfur quanti-
holder groups to use in evaluating HCTs.
tative limit, sulfate release rates, pH, and steady state duration)
4.7 As a mine typically involves very large quantities of
must be developed on a site/project-specific basis based on
waste rock, which will be leached by at least some amount of considerations including site-specific lithology, mineralogy,
incident precipitation for extended times, ongoing monitoring
trace metal characteristics, and potential environmental risks.
of waste facility performance, including any produced effluent The values given in the following guides are merely example
or leachate, is almost always required as a condition of permit criteria; it is up to the stakeholders to manage their own
approval. criteria.
D8187 − 18
GUIDE A
CONFIRMATION OF STATIC TESTING RESULTS
5. Summary of Guide
TABLE 2 Summary of NCC Classifications and Final HCT pH
5.1 Stakeholdersagreeonpreliminaryscopeanddurationof
Ranges for the Genesis Project
HCTtests based on lithology, mineralogy, static testing results,
Lowest HCT Highest HCT Number of
ore, mine, and processing requirements. Materials are classi-
NCC Classification
Final pH Final pH Composites
fiedandtestedbyTestMethodD5744andresultsinterpretedto
Acidic 2.24 2.33 2
comparewithTestMethodsE1915statictestingclassifications.
Slightly Acidic 2.62 2.81 2
Inert-Neutral 4.45 7.94 7
Slightly Basic 3.79 7.46 3
6. Procedure
Basic 6.66 7.61 4
Highly Basic 7.11 7.98 2
6.1 Classify the HCT test materials according to their
acid-base classification in accordance with Test Methods
E1915, as shown in Table 1.
6.1.1 Results from materials tested by Test Method D5744
and interpreted may be used to assess the suitability of static
cant acid generation potential) should be adequate to confirm
testing classifications and the relative ranges of drainage
the classification for ore and waste control during mining and
quality parameters to be associated with the static testing
metallurgical operations.
classifications for the materials tested on a site-specific basis.
6.4.2 A decision point should be planned at 20 weeks to
6.1.2 An example of the classification of materials and
determine whether or not the static test results have been
humidity cell final pH results for the Genesis Project (6) is
confirmed.
shown in Table 2.
6.4.3 It is important to note that even for highly acidic (high
6.2 Confirmation of static test results using humidity cells
potential for acid generation) or highly basic (high net neutral-
should be initiated early in the mine and process development
izing potential) samples, a longer test duration may provide
cycle to identify whether certain waste materials will require
important information regarding the acceleration or decelera-
further study when the plan of operations for the facilities is
tion of oxidation and metal release behavior that may be
better defined.
critical information for designing waste management or water
6.3 The tests should include weathered solid material analy-
treatment facilities.
ses according to Test Method D5744, or mass balance
6.5 Screening effluents for water treatment requirements
calculations, as appropriate.
shouldincludecomparisonsofeffluentsbetweenHCTs(weath-
6.4 End Member Classifications—Highly acidic (ABA val-
ering of sample) and Test Method E2242 or D6234, represent-
ues of ≤ –10 net calcium carbonate [NCC]), or highly basic
ing the best case (water leach of sample mobile salts), and the
lithologies (NCC values ≥ +10), as determined by Test Meth-
residual solutions from the University of British Columbia
ods E1915.
Research Confirmation Test (7) to represent the worst case
6.4.1 If the objective of the humidity cell te
...