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Wednesday March 26, 2003
1:30 pm to 5:00 pm
This Workshop was held in conjunction with the Heap Leach Closure Workshop.
1:30 – 2:15 pm
STEERING COMMITTEE OF ADTI-MMS | Presentation |
Virginia T. McLemore1 and the Steering Committee of the Acid Drainage Technology Initiative—Metals Mining Sector (ADTI—MMS)
1New Mexico Bureau of Geology and Mineral Resources (NMBGMR), New Mexico Institute of Mining and Technology, Socorro, NM, 87801, ginger@gis.nmt.edu
The Acid Drainage Technology Initiative (ADTI) was created in 1995 by the National Land Reclamation Center, National Mining Association, Office of Surface Mining, Environmental Protection Agency, Bureau of Land Management, U. S. Geological Survey, and Interstate Mining Compact Commission. ADTI’s mandated task is to identify, evaluate, and develop cost-effective and practical acid mine drainage (AMD) technologies and to address other drainage-quality issues related to mining. The intent of ADTI subsequently has evolved to identify, evaluate, develop, disseminate information, and promote understanding about cost effective, environmentally sound scientific methods and technologies to manage MIW and related processing materials. In 1999, ADTI was expanded through the addition of the metal mining sector (MMS) group. ADTI now addresses MIW drainage quality issues related to metal mining and related metallurgical operations, including pit lakes (ADTI-MMS) as well as MIW from coal mines (ADTI-CMS, coal mining sector), for future and active mines as well as for historic mines and mining districts.
The first project undertaken by MMS is the development of a handbook on best practices and technologies concerning the sampling, monitoring, prediction, mitigation, and modeling of drainage from metal mines and related metallurgical materials based upon current scientific and engineering practices. The MMS handbook on MIW is a technical document. This handbook is not intended to be a substitute for regulatory requirements; instead it is intended to provide tools for solving technical problems. This handbook addresses all types of mine-drainage control and treatment methods, including generalized design and performance criteria. Historic examples and case studies are included. Design details associated with successful mining operations and case histories of several mine failures are provided and research needs and cost effectiveness of various options are identified and evaluated. The handbook will enable a user to select technologically effective and economical sampling and monitoring, prediction, modeling, mitigation, and mine closure methods suited for particular geological and environmental situations.
In the first chapter (Introduction), the basic information about physical and chemical characteristics of mining, climate, and environment are provided. The remaining five chapters include sampling and monitoring (chapter 2), prediction (chapter 3), mitigation (chapter 4), modeling of MIW (chapter 5), and pit lakes (chapter 6).
Other projects undertaken by MMS include:
• RAMS Database work
• RAMS Engineering Handbook
• the MMS group presented a training course; Bureau of Land Management (BLM) Course 3000- 47 Acid Rock Drainage, Prediction and Treatment
• Coordination and support for corporate research.(Molycorp)
• INAP Coordination.
• Incorporation as a formal Non-Profit Corporation.
The ADTI-MMS website (http://www.unr.edu/mines/adti)
2:15 – 2:45 pm
SAMPLING AND MONITORING COMMITTEE OF ADTI-MMS | Presentation |
Virginia T. McLemore1, Carol C. Russell2, and the Sampling and Monitoring Committee of the Acid Drainage Technology Initiative—Metals Mining Sector (ADTI—MMS)
1New Mexico Bureau of Geology and Mineral Resources (NMBGMR), New Mexico Institute of Mining and Technology, Socorro, NM, 87801, ginger@gis.nmt.edu
2U. S. Environmental Protection Agency, 999 18th Street, Denver, Colorado 80202, russell.carol@epa.gov
The Metals Mining Sector of the Acid Drainage Technology Initiative (ADTI-MMS) addresses mining impacted waters (MIW) drainage-quality issues related to metal mining and related metallurgical operations, for future and active mines as well as for historical mines and mining districts. One of the first projects of ADTI-MMS is to develop a handbook describing the best documented science and methodologies for sampling, monitoring, prediction, mitigation, and modeling of drainage from metal mines and related metallurgical materials based upon current scientific and engineering practices. The sampling and monitoring committee is charged with preparing the sampling and monitoring chapter. This chapter reviews basic philosophical and scientific features of sampling and monitoring. While focusing mostly on sampling of ground and surface water, soils, and rocks, other media including air and biological organisms also are considered in this chapter. The purpose of this chapter is to describe the philosophy of sampling and monitoring, discuss some of the most commonly used sampling and monitoring techniques, provide cost-effectiveness information about various techniques, offer guidance about which techniques are most suitable, and critique the strengths and shortcomings of various approaches or techniques. Workshops are planned to disseminate the information in this chapter.
2:45 – 3:15 pm
ADTI MODELING COMMITTEE – STATUS REPORT | Presentation |
Edward M. Trujillo, Chair ADTI-MMS Modeling Committee
Mining companies, consultants, and federal and state land-managing agencies are challenged with making environmentally-sound decisions on how to best manage millions of tons of mine waste from abandoned, existing, and future metal-mining activities without adversely impacting existing surface and groundwater quality. Mine-waste management decisions are largely based on the predicted quality of drainage from the mine waste. While suites of laboratory-predictive tests and their results are commonly used by industry and reviewed by mining companies and land-managing agencies to help forecast mine-waste drainage quality, no consensus exists regarding how well these tests predict future drainage quality in the field. Because of the complexity of the problem and the uncertainty of predictive-test accuracy, mining companies and land-managing agencies are concerned that the prospect of having contaminated drainage develop 25 to 50 years in the future from mine-waste is a real possibility. To avoid such a scenario, mining companies, consultants and federal and state agencies need a single resource outlining the current state-of-the-art in predictive models, an understanding of their application and interpretation, and an organized compilation of the source and cost of these models. These aspects are essential for making scientifically based decisions on mine waste management and are the focus of the ADTI modeling committee.
The specific objectives for the ADTI-MMS modeling committee are to conduct a literature survey of existing predictive models for acid rock drainage systems, compile the results of the survey and write two workbooks or guidance manuals on modeling – one on geochemical modeling and another on geochemical modeling coupled with transport or flow. This talk will give an overview of modeling and the status of the ADTI-MMS modeling committee.
3:15 – 3:30 Break
3:30 – 4:00 pm
MINE ROCK PILE EROSION AND STABILITY EVALUATIONS AT MOLYCORP'S QUESTA MINE, NEW MEXICO
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Dennis L. Turner Sr. Programs Consultant (602) 771-4501
ADEQ, 1110 W. Washington St., MC5415B-3, Phoenix, AZ 85007
Molycorp began mining molybdenum and producing concentrate at Questa in 1919, first by mining the high-grade lode veins, followed by an open pit operation beginning in 1965 and then by underground methods beginning in 1983, which continues today at about 2700 TPD. The open pit operations ceased in 1981, leaving 9 mine waste rock piles, some of which are 1600 ft high. Mine rock piles from the open pit operation were created as valley fills followed by end dumping. Over time, since surface mining ceased, concern has grown about the long-term weathering effects of the mine rock piles and resultant drainage and slope stability issues. Molycorp has requested research proposals from four university-based research teams to investigate the potential effect of physical and chemical weathering within the span of 100 years and over geologic time (much greater than 100 years). The project's goal is to develop a model that assesses the risk of failure of the rock piles, based on their physical, chemical, mineralogical and weathering characteristics.
4:00 – 4:30
PROGRESS OF BLM-FUNDED ACID MINE DRAINAGE RESEARCH
W. W. White III1 , Kim A. Lapakko2 , and Edward M. Trujillo3
The environmentally sound management of abandoned, existing, and future metal mine wastes on public lands has been identified as the most difficult and costly reclamation problem facing federal and state land-managing agencies. Drainage-quality prediction is essential to environmentally sound mine-waste management. The U.S. Bureau of Land Management (BLM), in association with the Minnesota Department of Natural Resources Division of Lands and Minerals (MN DNR) and University of Utah Chemical and Fuels Engineering Department (University), continued sponsorship of research on predictive modeling of contaminated drainage from metal-mine waste after the U.S. Bureau of Mines closed.
A well-defined kinetic test protocol was developed and approved as an ASTM method with funding from the USBM and the BLM. BLM-sponsored research showed that the ASTM humidity-cell protocol produced highly reproducible drainage quality, within and among laboratories, on four waste-rock lithologies (MN DNR). A simplified humidity-cell method produced results similar to those from the ASTM protocol with comparable intralaboratory replication. Mine-waste characterization and accelerated-weathering (humidity cell tests ranging from 20 to 278 weeks) were conducted on 63 samples from eight different mine-waste lithologies (MN DNR). For three lithologies with at least moderate amounts of calcium and magnesium carbonates, 24 to 60 percent of the neutralizing carbonates were available in samples with neutralization potentials of 21 to 42 g CaCO3 (kg rock)-1. Acid production thresholds were identified based on the sulfur content of two mine-waste lithologies with very low calcium and magnesium carbonate contents. Drainage pH values less than 4.5 were produced by Duluth Complex samples with S > 0.41% and field test piles yielded drainage pH values similar to laboratory values for samples of similar sulfur content. Drainage pH values less than 4.5 were also produced by Archean greenstone samples with S > 0.2%. Field rates of chemical release from Duluth Complex and Archean greenstone rocks typically ranged from 10 to 45 percent of those for laboratory samples of similar sulfur content.
The University’s laboratory model demonstrated reasonable agreement between modeled output and actual pH, sulfate, and calcium concentrations from weekly humidity-cell drainage produced from accelerated weathering of five different waste-rock lithologies. The field model linked governing geochemical reactions to transport phenomena in porous media and produced concentration profiles for multiple species in a simulated symmetrical test pile.
Results from the BLM-sponsored research are published in 5 peer-reviewed journal papers, 2 M.S. theses, and 19 contract reports.
1 Physical Scientist, U.S. Bureau of Land Management, Salt Lake Field Office
2 Principal Engineer, Minnesota Dept. of Natural Resources, Lands and Minerals Division
3 Associate Professor, University of Utah, Chemical and Fuels Engineering Dept.
4:30 – 5:00
Pit Lake Committee Report. |Presentation |
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Contact Information
Dr.Dirk Van Zyl, Director
Mining Life-Cycle Center, MS 173
University of Nevada,
Reno, NV 89557
Ph: (775) 784-7039
dvanzyl@mines.unr.edu
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