Cyanide Management in Mining - 4: Toxicity and Environmental Properties of Cyanide

Areas of Study: Environment and Community

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The Cyanide Management in Mining courses attempt to provide the user with the background for development of a cyanide management plan that meets the unique requirements of each operating mine. This course, the fourth in a series of six, discusses the sources and toxicology of cyanide; its toxicity to aquatic organisms, birds and mammals; the toxicity of related compounds and mine waste; and environmental exposure and monitoring

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  • Audience Level:
  • Professional
  • Enrollment:
  • Required
  • Duration:
  • 12 hours

Course Summary


The cyanidation process for the extraction of gold and silver from ore has been employed since 1898 when it was first used in New Zealand and Africa and soon after in the United States. It is a very efficient process capable of extracting gold in amounts of less than one percent of an ounce from a ton of rock with over 90% efficiency.

Because of the environmental risks, a cyanide management plan is of critical importance to a mining operation. The lack of such a plan, in some cases, has contributed to adverse environmental incidents involving cyanide. The United Nations Environment Programme (UNEP) is developing an international code for the management of cyanide. Implementation and adherence to this code, augmented by experienced scientific and engineering judgment, will help reduce both the number and severity of environmental incidents involving cyanide.

The "Cyanide Management in Mining" courses attempt to provide the user with the necessary background for development of a cyanide management plan that meets the unique requirements of each operating mine. The full complement of courses in the series includes:

  • Chemistry of Free and Complexed Cyanide
  • Analysis of Cyanides
  • Geochemical Properties and Environmental Fate of Cyanide
  • Toxicity and Environmental Properties of Cyanide
  • Water Management and Discharge Strategies
  • Treatment Technologies for Cyanide and Related Compounds
"Toxicity and Environmental Properties of Cyanide" is the fourth in the series of six courses. This course covers the sources and toxicology of cyanide; its toxicity to aquatic organisms, birds and mammals; the toxicity of related compounds and mine waste; and environmental exposure and monitoring.

This course comprises 13 viewing sessions, each of 30 - 60 minutes duration, plus supporting figures, tables and references, and three interactive reviews that confirm achievement of the learning objectives.

Learning Outcomes

  • Discuss the sources and toxicology of cyanide.
  • Discuss the toxicity of cyanide and related compounds and mine waste to aquatic organisms, birds and mammals.
  • Discuss environmental exposure, exposure limits and monitoring of cyanide.
  • Apply the knowledge gained to development of a cyanide management plan.

Recommended Background

  • A degree or diploma in environmental engineering or mineral processing.
  • Experience of gold or silver extraction with cyanide.

Dr. Terry Mudder

For twenty years until 2014, Dr. Terry I. Mudder was co-owner (with his wife, Dr. Karen Hagelstein) of Times Limited, a consulting firm located in Sheridan, Wyoming (USA). He was previously employed as Chief Environmental Engineer and Research Chemist at the Homestake Mine, and later a partner and corporate consultant with SRK Consulting. Dr. Mudder holds B.S. and M.S. degrees in Chemistry, and a Ph.D. in Environmental Science and Engineering. He has more than three decades of experience in investigation of various aspects of cyanide wastes. He served as an adjunct professor, guest lecturer, and thesis advisor at universities worldwide. He has worked on scores of mining projects, authored nearly one hundred publications, and been involved with numerous short courses, many with EduMine, on acid mine drainage, rehabilitation, and cyanide. As a leading expert on cyanide in mining in the world, he has co-authored many manuals, pamphlets, and books, including the CDs entitled The Chemistry and Treatment of Cyanidation Wastewaters, The Cyanide Monograph, and The Cyanide Compendium.

Dr. Mudder has been instrumental in developing and applying novel chemical, physical, and biological treatment processes for which he has received international awards and patents. He has been a member of many national and international scientific organizations and associated professional committees, as well as a manuscript reviewer. He has been the Technical Advisor for Mining Environmental Management for nearly a decade, for which he has written numerous editorial and opinion articles. He co-created the cyanide information website, CyanideMine. In February 2014 Dr. Mudder was inducted into the International Mining magazine's Hall of Fame and was recognized with an award in Environmental Management and Stewardship.

Dr. Mudder co-sponsored the Dr. Adrian Smith Award given to outstanding individuals for lifetime achievement in environmental stewardship in mining. He has served as technical advisor to aboriginal groups, various industries, international governments, and NGO's including the World Bank, the International Finance Corporation, and the United Nations Environmental Program (UNEP).

Mike Botz M.S., P.E.

Mr. Mike Botz is president and owner of the consultancy Elbow Creek Engineering, Inc. and is a registered professional chemical engineer. Mr. Botz holds a BS degree in Chemical Engineering from Montana State University and an MS degree in Chemical Engineering from Purdue University. As a Senior Process Engineer, Mr. Botz has over ten years of experience related to the evaluation, testing, design, cost estimating, construction, commissioning and troubleshooting of industrial water treatment plants. In addition, Mr. Botz is also highly experienced with industrial gas cleaning systems for removing chemical contaminants and particulate matter. Projects completed by Mr. Botz have spanned North America, Latin America, Europe, Australia, Africa and Asia and have ranged in scope from conceptual evaluations through pilot testing, full-scale facility construction and plant commissioning. In addition to industrial project work, Mr. Botz has provided course instruction to academic, government and industry groups, and has presented research findings at numerous industry professional societies. Mr. Botz is active in the Society for Mining, Metallurgy and Exploration (SME), the American Water Works Association (AWWA) and the American Institute of Chemical Engineers (AIChE) through presenting papers and chairing technical sessions. Mr. Botz has authored and co-authored numerous publications in regard to the management and treatment of industrial waters and gases. Mr. Botz was also co-author of the books The Cyanide Monograph and the Chemistry and Treatment of Cyanidation Wastes, both published through Mining Journal Books Limited in London.

Dr. Karen A. Hagelstein

Karen Hagelstein has twenty-five years of consulting experience in industrial hygiene, environmental science and engineering, has about ten years of college teaching experience, and is currently a partner of TIMES LIMITED, a woman-owned firm since 1992. She received her B.S. in biology from the University of South Dakota, a M.S. in physiology and biophysics, and a Ph.D. in civil and environmental engineering from University of Iowa, Iowa City in 1982. Dr. Hagelstein's projects have included human health assessments and air quality monitoring at numerous schools, office buildings, homes, hazardous waste sites, print shops, power plants, hospital, airport, welding shops, recycling facility, and manufacturing plants for guitars, recreational equipment, and particle-boards. Expert witness reports and testimonies have been provided concerning occupational health regulations, air dispersion modeling applications, the health impacts of sewage-contaminated homes, and the toxicological implications of thermo-fogging agents, fire/combustion products, organic wastes, heavy metals, and welding exposures.

Several projects and publications have focused on the environmental significance of cyanide and its derivatives. The ecological and toxicological properties of cyanide with respect to terrestrial, aquatic, and wildfowl exposures was assimilated, published, and presented for a mining conference in Perth, Western Australia. Dr. Hagelstein provided information to a New Zealand mining company and a government-mandated Turkish contingency regarding community relations and environmental implications of cyanide use at a gold mine. Standard operating procedures and occupational health guidelines for the onsite storage, handling, and transport of cyanide were produced for an article in the Mining Journal Publication and for a booklet of the International Council on Metals and the Environment (ICME). In 2000, she participated in a multi-stakeholder conference in Paris, France to develop a code for the environmental management of cyanide in the mining industry that was sponsored by the United Nations Environmental Programme (UNEP).