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Cyanide 

 
Author: Dr. Terry Mudder

Summary

This review surveys online resources relevant to the use of cyanide in mining. It gives general information on cyanide and the Cyanide Management Code, and discusses cyanide analysis, treatment, and health and safety. A number of suppliers and links to EduMine courses on cyanide are also given.

INTRODUCTION

InfoMine information about cyanide is available on this site, in the EduMine courses by Dr. Terry Mudder, in publications in our library, and through the links in LinksMine. By using the Google search box at the top of this page you can find TechnoMine cyanide-related information via any combination of keywords relevant to your interests and needs.

No one article could ever provide a complete and comprehensive encyclopedia on so large a topic. What follows here is an introduction with enough technical content to inform and assist the intelligent person on any mine faced with the issue: CYANIDE.


WHAT IS CYANIDE?

The term "cyanide" refers to a chemical compound containing one atom of carbon and one atom of nitrogen. The technical definition of cyanide is: A triple-bonded molecule with a negative one charge consisting of one atom of carbon in the +2 oxidation state and one atom of nitrogen in the -3 oxidation state.

Cyanide is a unique chemical compound used to manufacture hundreds of everyday goods, and chances are that today you will use many products that included cyanide in its manufacture. These products may include vitamins (B12), jewelry, adhesives, computer electronics, fire retardants, airplane brakes, cosmetics, dyes, nylon, nailpolish remover, paints, pharmaceuticals, Plexiglas, rocket propellant, and table salt. The manufacturing of these productstakes place every day around the world with little knowledge from the general public that cyanide is a critical ingredient in their manufacture. Indeed, without cyanide it would not be possible to manufacture such widely used items as nylon and many vitamins and other medications.

Cyanide is a relatively toxic compound but has been safely used for well over a hundred years around the world. Many people have a natural fear of cyanide that arises from a general understanding of its toxicity but a less thorough understanding of its actual properties and usefulness in our everyday lives. As with any chemical, cyanide must be properly and safely handled to avoid harm to people or the environment. The benefit people derive from cyanide and its many products far outweighs the risk posed to people and the environment.

The human body has a natural ability to detoxify small quantities of cyanide, and there is normally a small amount of cyanide and its breakdown products in the body as a result of everyday activities. These activities may include the metabolism of vitamin B12, eating of foods naturally containing cyanide (for example, almonds, lima beans, coffee and table salt), exposure to automobile exhaust and smoking cigarettes. In some form, we are exposed to low levels of natural and manmade cyanide every day without risk to our health or the environment.


CYANIDE CODE

Do not touch cyanide at your mine unless you have read the International Cyanide Management Code. You can download the code at http://www.cyanidecode.org/ The following extract is from an excellent report on the code at a site I recommend you consult:

After adopting an international cyanide management code two years ago, six of the world's largest gold producers, along with three manufacturers of sodium cyanide, announced Monday that they will commit to the code. Trouble is the mechanism for actual enforcement and auditing of the voluntary code has yet to be implemented.

Nevertheless, AngloGold Ashanti, Barrick, Kinross, Newmont, Placer Dome, and Rio Tinto declared in a press release issued Monday that they will commit to the code. Cyanide producers DuPont--which originally proposed a cyanide management code for gold mining nearly 15 years ago, CyPlus (formerly Degussa) and Cyanco have also committed to the code. Glamis Gold, Gold Fields, Minas Luismin of Mexico, WMC of Australia, and Eldorado Gold also served on the industry advisory group which formulated the code, but have not yet become signatories.

The idea of an international cyanide code was a good one when it was proposed several years ago. A lot of hard work by quite a few folks went into the effort, which was sponsored by the United National Environment Programme and the International Council on Metals & the Environment. The steering committee boasted a membership from the governments of Peru, Canada, Ontario, and the European Commission, NGOs including the World Wide Fund for Nature of Australia, academia, cyanide producers, labor, regulators, the International Finance Corporation, mining associations, such as the South African Chamber of Mines and the Australian Gold Council, and the gold mining industry. The steering committee was chaired by former Homestake environmental executive Harold Barnes. Code manager is Norman Greenwald, an Arizona-based environmental consultant.

Here are the Principles of Practice set out in the code:

  1. Production: Encourage responsible cyanide manufacturing by purchasing from manufacturers who operate in a safe and environmentally protective manner.
  2. Transportation: Protect communities and the environment during cyanide transport.
  3. Handling and Storage: Protect workers and the environment during cyanide handling and storage.
  4. Operations: Manage cyanide process solutions and waste streams to protect human health and the environment.
  5. Decommissioning: Protect communities and the environment from cyanide through development and implementation of decommissioning plans for cyanide facilities.
  6. Worker Safety: Protect workers' health and safety from exposure to cyanide
  7. Emergency Response: Protect communities and the environment through the development of emergency response strategies and capabilities.
  8. Training: Train workers and emergency response personnel to manage cyanide in a safe and environmentally protective manner.

The code provides Standards of Practice for each of these principles. For example regarding transport, the standards of practice are:

    • Establish clear lines of responsibility for safety, security, and release, training and emergency response in written agreements with producers, distributors and transporters.
    • Require that cyanide transporters implement appropriate emergency response plans and capabilities, and employ adequate measures for cyanide management.

An accompanying document, Implementation Guidance for the International Cyanide Management Code, sets out details of how to implement the principles and standards. They are long and detailed and I urge you to consult the original document for the specifics.

SUPPLIERS

The Infomine supplier's pages link you to cyanide suppliers. For quick reference see the Nevada company that makes and sells cyanide; the MSDS for cyanide is readily available on this site.

DENVER MINERAL ENGINEERS, INC., offers a complete range of mining process equipment for cyanide gold recovery and water treatment:

CyPlus claims to be the world's largest supplier of cyanide to the mining and other industries. They provide information on all aspects of cyanide from manufacture, through use, to disposal.

In Western Australia go to the Mineral Process Control site for supplies of chemicals for cyanide processing.


COURSES

EduMine has eight courses on cyanide. The following seven are by the experts, namely Dr. Terry Mudder, Mike Botz, Dr. Karen Hagelstein:

These course contain far more information than we post here. Take a look at them. Please also see the links to the right hand side of this text for a complete list of courses, technical publications, and other InfoMine resources related to cyanide.


CYANIDE ANALYSIS

The term "cyanide" generally refers to one of three classifications of cyanide, which are: (1) total cyanide; (2) weak acid dissociable (WAD) cyanide; and (3) free cyanide, as shown in the following figure. Each of these forms of cyanide has specific analytical methodologies for its measurement, and it is important that the relationship between these forms be understood when analyzing cyanide-containing solutions. As indicated in this figure, for a given solution the total cyanide level is always greater than or equal to the WAD cyanide level, and likewise, the WAD cyanide level is always greater than or equal to the free cyanide concentration.

General Classification of Cyanide Compounds
General Classification of Cyanide Compounds

The approach to assessing the quality of water samples in many situations is to analyze for WAD cyanide since this includes the toxicologically and environmentally important forms of cyanide, including free cyanide and moderately and weakly complexed metal-cyanides. Total cyanide includes free cyanide, WAD cyanide plus the relatively non-toxic iron-cyanide complexes. Complete characterization of a cyanide solution generally includes analyses for pH, total cyanide, WAD cyanide, thiocyanate, cyanate, ammonia, nitrate and base metals such as copper, iron, nickel and zinc. Click to learn more about the cyanide related compounds thiocyanate, cyanate, ammonia and nitrate

A companion document to the draft International Cyanide Management Code deals with the collection and analysis of cyanide samples and is a useful reference. Download Now (PDF 44 kB)

Online cyanide analyzers are also being used to continuously monitor cyanide levels in processing plants. Click on the following links for related information.

There are several step-by-step laboratory procedures for analyzing cyanide, and below are links to some of the more common methods.

Method Description
USEPA OIA-1677 Available Cyanide by Flow Injection with Ligand Exchange
Click here to download brochure describing OI Analytical equipment.
USEPA 9010C Total and Amenable Cyanide: Distillation
USEPA 9012A Total and Amenable Cyanide
(Automated Colorimetric With Off-Line Distillation)
USEPA 9012B Total and Amenable Cyanide
(Automated Colorimetric With Off-Line Distillation)
USEPA 9013 Cyanide Extraction Procedure for Solids and Oils
USEPA 9014 Titrimetric and Manual Spectrophotometric
Determinative Methods for Cyanide
USEPA 9213 Potentiometric Determination of Cyanide in Aqueous Samples
and Distillates with Ion-Selective Electrode
USEPA 335.1 Cyanides, Amenable to Chlorination
USEPA 335.2 Cyanide, Total (Titrimetric and Spectrophotometric)
USEPA 335.3 Cyanide, Total (Colorimetric and Automated UV)
USEPA 335.4 Determination of Total Cyanide by Semi-Automated Colorimetry
ASTM D2036-06 Standard Test Methods for Cyanides in Water
ASTM D4282-02 Standard Test Method for Determination of Free Cyanide
in Water and Wastewater by Microdiffusion
ASTM D4374-06 Standard Test Methods for Cyanides in Water -- Automated Methods for
Total Cyanide, Acid dissociable Cyanide, and Thiocyanate
ASTM D6696-05e1 Standard Guide for Understanding Cyanide Species
ASTM D6888-04 Standard Test Method for Available Cyanide with Ligand Displacement and
Flow Injection Analysis (FIA) Utilizing Gas Diffusion Separation and Amperometric Detection
ASTM D7237-06 Standard Test Method for Aquatic Free Cyanide with Flow Injection
Analysis (FIA) Utilizing Gas Diffusion Separation and Amperometric Detection
ASTM D7284-08 Standard Test Method for Total Cyanide in Water by Micro Distillation followed by
Flow Injection Analysis with Gas Diffusion Separation and Amperometric Detection
ASTM D7365-09 Standard Practice for Sampling, Preservation and Mitigating
Interferences in Water Samples for Analysis of Cyanide
ASTM D7511-09 Standard Test Method for Total Cyanide by Segmented Flow
Injection Analysis, In-Line Ultraviolet Digestion and Amperometric Detection
Standard Methods
4500-CN
Methods for Total Cyanide, Cyanides Amenable to Chlorination,
WAD Cyanide, Cyanogen Chloride, Cyanates and Thiocyanate
ISO 6703-1:1984 Determination of Total Cyanide
ISO 6703-2:1984 Determination of Easily Liberatable Cyanide
ISO 6703-3:1984 Determination of Cyanogen Chloride
ISO 27368:2008 Analysis of Cyanide in Blood
USGS I-1300 Cyanide, Colorimetric, Pyridine-Pyrazolone
USGS I-2302 Cyanide, Colorimetric, Barbituric Acid,
Automated-Segmented Flow
Picric Acid I Direct Spectrophotometric Method Using Picric Acid Reagent
Picric Acid II Picric Acid Method for Determining Weak Acid Dissociable (WAD) Cyanide

Please also take a look at this paper: Proceedings of the International Cyanide Detection Testing Workshop

Here are similar references to cyanide analytical procedures: National Environmental Methods Index (NEMI)

Here is a presentation by Skalar Analytical B.V.: Automated Total Cyanide Analysis: EPA Method Keleda-01 Implemented with the Skalar Flow Analyzer



CYANIDE TREATMENT

A variety of processes are available to treat and recover cyanide.Following are links to information about the more commonly used cyanide treatment methods in the mining industry.

Overview of Cyanide Treatment Methods Download recently published technical papers that discuss the most widely used methods to treat and recover cyanide in the mining industry. Download Now (153 kB)

Cyanide Recovery Practice at Cerro Vanguardia: Cyanide recovery from industrial solutions has been practiced worldwide for several decades. Click here to access a recent publication describing the cyanide recovery plant operating in Argentina, or contact the Cyantists for more information.

Hydrogen Peroxide Cyanide Destruction Process Solvay Interox manufactures hydrogen peroxide and has several downloadable documents that describe hydrogen peroxide and its use in cyanide destruction processes. This is one of the oldest and most well known cyanide treatment processes.

Hydrogen Peroxide and Caro's Acid Powerful Oxidants for Cyanide Destruction A brief review of the use of peroxygens to destroy free CN-, WAD (weakly acid dissociable) CN- and tightly complexed cyanides will be followed by a case history on the use of Caro's acid (peroxymonosulfuric acid) to treat cyanide in a tailings slurry at a large North American Gold mine.

Thermal Hydrolysis Cyanide Destruction Process Cyanide Destruct Systems, Inc. provides thermal hydrolysis systems for treatment of low-volume cyanide solutions, primarily in the plating industry. The process is effective at removing iron-cyanides to low levels. Connect to Cyanide Destruct Systems, Inc.

Sulphur Dioxide and Air Cyanide Destruction Process INCO Ltd. provides technology for the sulphur dioxide and air cyanide destruction process. A great alternative to consider for both slurries and solution to destroy cyanide in wastes. Click here to download a USEPA publication discussing the INCO process. Connect to INCO Ltd.; Connect to CyPlus - More than Cyanide

USEPA Cyanide Treatment Report In 1994, the USEPA published a general report on treating solutions at heap leach operations. Download Now (211 kB)

CYANIDE HEALTH AND SAFETY

In any work setting that involves the handling of cyanide, safety is of utmost concern. Cyanide toxicity to humans, birds, fish and other wildlife has been studied for many years and is well understood. This information, coupled with a properly developed and administered cyanide management plan, allows operations to safely handle cyanide without undue risk to workers or the environment. The following are sources of technical information dealing with the toxicity and environmental behavior of cyanide.

HUMAN HEALTH

Toxicological Profile for Cyanide In 1997, the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) developed a comprehensive toxicological profile for cyanide. The profile includes health effects, production and use, potential for exposure, toxicity and regulations along with an extensive reference list. This profile was updated in 2004, and both the 1997 and 2004 versions are available below. A short summary of the profile is provided in an ATSDR ToxFAQs file for cyanide.

Hydrogen Cyanide and Cyanides: Human Health Aspects The World Health Organization published in 2004 a review of human health aspects associated with cyanide. Download Now (678 kB)

Material Safety Data Sheet (MSDS) for Sodium Cyanide (NaCN) Download Now (100 kB)

USEPA Fact Sheet on Cyanide The USEPA has a consumer fact sheet describing cyanide and its regulation in drinking water. Details

Centers for Disease Control and Prevention The U.S. Centers for Disease Control (CDC) has a compilation of publications dealing with the human health and safety aspects of cyanide. Details

National Institute of Occupational Safety & Health (NIOSH) The National Institute of Occupational Safety & Health (NIOSH) publishes general safety & health information for a large number of chemicals including hydrogen cyanide.

Health Guideline for Hydrogen Cyanide Occupational Safety and Health Administration (OSHA) guideline summarizing pertinent information about hydrogen cyanide exposure for workers and employers. Details

Cyanide in Drinking Water The California Environmental Protection Agency has published a document describing the public health goal for cyanide in drinking water, which is a concentration of less than 0.15 mg/L. Download Now (53 kB)

Cyanide Air Emissions The U.S. Environmental Protection Agency (USEPA) has published a document discussing air emissions of cyanide compounds. Download Now (451 kB)

Occupational Exposure to Cyanide The U.S. National Institute for Occupational Safety and Health (NIOSH) has published a report with recommended criteria for occupational exposure to several cyanide compounds, including hydrogen cyanide, sodium cyanide, potassium cyanide and calcium cyanide. Download Now (6.5 MB)

Public Health Assessment of Cyanide Air Emissions The USEPA was recently petitioned to complete a study of cyanide in the air at a U.S. gold mine. The USEPA concluded in 2000 that cyanide levels at the mine and in nearby residential areas are not at levels of health concern. Details


CYANIDE POISONING AND RESPONSE

Publication on Cyanide Poisoning from WorkSafe Australia Download Now (59 KB)

US Army article on Cyanide Poisoning - Cyanide, long considered a toxic, deadly substance, has been used as a poison for thousands of years. It was not highly successful as a chemical warfare agent in World War I, possibly because of the way it was delivered. Download Now (101 KB)

Cyanide Antidotes Details

Use of Air Dispersion Modeling to Estimate the Time Potentially Available for Emergency Response Action Needed to Protect Public Safety From Chemical Releases. The Release Incorporating Terrain Effects (RITE) Emergency Response Software model was used to determine the amount of time potentially available for emergency response personnel to notify the public and convey instructions on the proper actions that should be taken in the event of a chemical release.Download Now (550 KB)

Preliminary Data Search Report for Locating and Estimating Air Toxic Emissions from Sources of Cyanide Compounds. Download Now (388 KB)


ENVIRONMENTAL BEHAVIOR

Cyanide Hazards to Fish, Wildlife, and Invertebrates: A Synoptic Review U.S. Fish & Wildlife Service report by Ronald Eisler, December 1991. Download Now (715 KB)

The Cyanide Cycle The Cyanide Cycle is a graphical representation of the various chemical, physical and biological reactions associated with cyanide compounds in the natural environment. Download Now (164 kB)

Preventing and Responding to Cyanide Spills: Dr. Terry Mudder recently prepared a document discussing the prevention and response to cyanide spills. Download Now (99 KB)


CYANIDE REGULATIONS, STANDARDS, AND GUIDELINES

Reducing Impacts of Tailings Storage Facilities on Avian Wildlife in the Northern Territory of Australia The objectives of these guidelines include enabling best practice management to reduce native bird mortalities at mining operations, assisting mine planners and operators to understand the issue of bird visitations and mortalities on tailings storage facilities, and helping planners incorporate features into new operations that will minimise bird mortalities. Download Now (296 KB)

Environmental, Health and Safety Guidelines for Mining Technical reference documents with general and industry-specific examples of Good International Industry Practice. Download Now

Water Quality Standards Criteria Summaries: A Compilation of State/Federal Criteria. This document contains excerpts from the individual Federal-State water quality standards establishing pollutant specific criteria for interstate surface waters. Download Now (3.8 MB)


ASSESSING RISKS

Cyanide Poisoning Statistics According to the American Association of Poison Control Centers (AAPCC), during 2004 there were 163 cases of cyanide poisonings in the US, 8 of which resulted in death and none of which occurred in the mining or metal plating industries (most were intentional suicides). By way of comparison, in that same year 24 deaths were attributed to marijuana use, 8 to pesticides exposure, 74 to carbon monoxide poisoning, 2 to the use of mouthwash, and 2 to exposure to air fresheners. Download Now (521 KB)


CYANIDE ATTENUATION AND AIR QUALITY MODELING

Significant Dust Dispersion Models for Mining Operations: This report discusses the health effects of dust, regulations pertaining to dust, and dust propagation models for underground and surface mines. Download Now (303 KB)

Preliminary Data Search Report for Locating and Estimating Air Toxic Emissions from Sources of Cyanide Compounds: This report deals with emissions from production and uses of cyanide compounds, and source test procedures. Download Now (371 KB)

Use of Air Dispersion Modeling to Estimate the Time Potentially Available for Emergency Response Action Needed to Protect Public Safety From Chemical Releases: This Master's thesis examines emergency response procedures, the RITE emergency response software model, the distance of plume travel, and the time for plume travel. Download Now (536 KB)

Cyanide Volatilisation from Gold Leaching Operations and Tailing Storage Facilities: The purpose of this Master's project was to develop a prediction model for cyanide volatilisation from plant operations and tailings storage facilities in South Africa. Download Now (1.7 MB)


CYANIDE FACTSHEETS, NEWSLETTERS, AND BRIEFS

Summary Fact Sheet on CyanideDownload Now (140 KB)

Cyanide Fact SheetDownload Now (50 KB)

Field Manual of Wildlife Diseases: Birds - Chapter 46: Cyanide: Cyanide poisoning of birds is caused by exposure to cyanide in two forms: inorganic salts and hydrogen cyanide gas. Download Now (827 KB)

Fact Sheet - Cyanide and Its Use by the Minerals Industry: Information on cyanide uses in the minerals industry, regulatory responses, technology reducing cyanide risks, and continous improvement. Download Now (76 KB)

Living with Cyanide (The Geochemical News): Sources of cyanide contamination; analysis and speciation of cyanide; toxicity; cleaning up tailings solutions and remediating contaminated sites; examples of cyanide pollution cases. Download Now (748 KB)

NICNAS Existing Chemicals Information Sheet - Sodium Cyanide: The National Industrial Chemicals Notification and Assessment Scheme (NICNAS) has assessed the environmental risks of sodium cyanide and made recommendations for minimising the environmental risks from its transport and use in mining. Download Now (105 KB)


MORE SITES ON CYANIDE

Cyanide Management Handbook (PDF). Part of the Leading Practice Sustainable Development in Mining series, from the Australian Department of Resources Energy and Tourism

Cyanide Management - Best Practice Environmental Management in Mining (PDF). This booklet is one of the Sustainable Minerals series of publications, aimed at assisting the minerals industry apply the principles of best environmental practice to minimise the impacts of cyanide use. Published by Environment Australia.

Sodium Cyanide Paste (PDF). The native forests of the Waitakere Ranges have suffered enormously from possums. Operation ForestSave - a campaign that ran in 1998 - greatly reduced possum numbers and helped the forest recover and flourish.

Cyanide is Widely Used to Manufacture Common Consumer Goods Hydrogen cyanide is the basic form from which most major cyanide compounds are derived. It has been produced worldwide for many years using basic chemicals such as ammonia and natural gas. About three million tonnes of hydrogen cyanide is produced annually worldwide, of which about 6% is converted into sodium cyanide and used in the metals industries (mining and metal plating). The remaining 94% of the hydrogen cyanide is used in the production of a wide range of industrial and consumer items.

Cigarette Smoke Contains Hydrogen Cyanide If you smoke, you are exposing yourself to elevated levels of hydrogen cyanide gas.

Inert Cyanide Compounds Are Present in Table Salt (16 kB) Inert iron cyanide compounds have been used for many years as anti-caking agents in road and table salts.

Foods With Trace Levels of Cyanide May Fight Cancer A professional nutritionist offers over 300 tasty recipes rich in the cyanide containing substances that many scientists believe is nature's control for cancer. Cyanide, in minute quantities and in proper food forms, instead of being poisonous, actually may be essential to health.

Iron Cyanide Being Used in Health and Beauty Products News about the safety of popular health & beauty brands.

Many Plants and Animals Produce Cyanide Naturally Cyanide is naturally produced by many plants and insects as a natural defense mechanism. One example is the Elderberry bush that grows throughout the Western US.

Cyanide Naturally Present in Major Food Source Cassava is a major food source for millions of people in developing countries that naturally contains cyanide. Cassava requires careful harvesting and preparation techniques to avoid possible health effects associated with cyanide ingestion. More About Cassava

How is Gold Produced? Simplified diagram prepared by The Gold Institute describing how gold is produced using cyanide.

The International Cyanide Management Institute Authors of the International Cyanide Management Code For The Manufacture, Transport and Use of Cyanide In The Production of Gold, aka the Cyanide Code.

International Finance Corporation Guidelines Technical reference document with general and industry-specific examples of Good International Industry Practice (GIIP). From the World Bank Group.

The Environmental Literacy Council An article from an independent non-profit organization on the use of cyanide gold mining

Extractive Industries Transparency Initiative The EITI sets a global standard for companies to publish what they pay and for governments to disclose what they receive.

The Initiative for Responsible Mining Assurance A multi-sector effort, launched in Vancouver, Canada, on June 7-9 2006, to develop and establish a voluntary system to independently verify compliance with environmental, human rights and social standards for mining operations. The report from the Vancouver meeting is available on their site.

Council for Responsible Jewellery Practices An international non-profit organisation representing over 80 member companies across the gold and diamond supply chain.

UNEP Environment and Mining Documents on mining and sustainable developments from United Nations and other organisations

Mineral Information Institute A not-for-profit organization based in Colorado dedicated to educating youth about the science of minerals and other natural resources, and about their importance in our every day lives.


OTHER NEWS ITEMS ON CYANIDE

Colorado Supreme Court rejects county's ban on mining using cyanide (Jan. 2009)

Colombian Divers Recover Cyanide Can Sunk in River (Sept. 2008)

Suicide Confirmed in Cyanide Case (Aug. 2008)

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