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:
- Production: Encourage responsible cyanide manufacturing by purchasing from manufacturers who operate in a safe and environmentally protective manner.
- Transportation: Protect communities and the environment during cyanide transport.
- Handling and Storage: Protect workers and the environment during cyanide handling and storage.
- Operations: Manage cyanide process solutions and waste streams to protect human health and the environment.
- Decommissioning: Protect communities and the environment from cyanide through development and implementation of decommissioning plans for cyanide facilities.
- Worker Safety: Protect workers' health and safety from exposure to cyanide
- Emergency Response: Protect communities and the environment through the development of emergency response strategies and capabilities.
- 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
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 (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.
- Process Analytical Systems (553 kB)
- Mintek Cyanoprobe (144 kB)
- Cyantific Instruments P/L (72 kB)
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 9010B |
Total and Amenable Cyanide: Distillation |
| 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 |
D2036-06 Standard Test Methods for Cyanides in Water |
| ASTM D4282-02 |
D4282-02 Standard Test Method for Determination of Free Cyanide
in Water and Wastewater by Microdiffusion |
| ASTM D4374-06 |
D4374-06 Standard Test Methods for Cyanides in Water
-- Automated Methods for Total Cyanide,
Acid dissociable Cyanide, and Thiocyanate |
| ASTM D6696-05e1 |
D6696-01 Standard Guide for Understanding Cyanide Species |
| ASTM D6888-03 |
D6888-03 Standard Test Method for Available Cyanide
with Ligand Displacement and Flow Injection Analysis (FIA)
Utilizing Gas Diffusion Separation and Amperometric Detection |
Standard Methods
4500-CN |
Methods for Total Cyanide, Cyanides Amenable to Chlorination,
WAD Cyanide, Cyanogen Chloride, Cyanates and Thiocyanate
|
| ISO 6703-1,2 |
Determination of Total and Easily Liberatable Cyanide |
| ISO/CD 27368 |
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 |
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 Downloadrecently published technical papers that discuss the most widely used methods to treat and recover cyanide in the mining industry. Download Now (153 kB)
Treatment and Recovery of Cyanide The 2001 2nd Edition of the book Chemistry and Treatment of Cyanidation Wastes published by Mining Journal Books Ltd is now available in softcover and electronically. This book includes detailed theoretical, design and operational information about the commonly used cyanide treatment processes in the mining and metal finishing industries, plus dozens of references to other technical publications. Contact the Cyantists for ordering information.
Cyanide Recovery Cyanide recovery from industrial solutions has been practiced worldwide for several decades. Click here to download 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. Cyplus Corporation (Degussa) also manufactures hydrogen peroxide and is experienced in assisting operations with implementing cyanide treatment systems. Connect to Solvay Interox; Connect to CyPlus Corporation Degussa Publication (1.3 MB)
Caro's Acid Cyanide Destruction Process Caro's acid, or peroxymonosulphuric acid, is a very strong oxidant and a suitable candidate for treating relatively low levels of cyanide in slurry tailings. Download a publication by FMC Corporation for details about this process or click here for an FMC Corporation publication discussing the properties of Caro's Acid.
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 ReportIn 1994, the USEPA published a general report on treating solutions at heap leach operations. Download Now (217 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 Publication on Cyanide Toxicology Download Now (101 kB)
Cyanide Antidotes Details
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)
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)
MORE SITES ON CYANIDE
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.
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