Cyanide and Arsenic in Gold Mining. Possible Environmental effects of The Rise and Shine (RAS) Bendigo Gold Mining Project
Photo: Fulvio Ciccolo
"For the first time in the history of the world, every human being is now subjected to contact with dangerous chemicals from the moment of conception until death." Rachel Carson.
Introduction
The Bendigo-Ophir Gold Project, located in the Dunstan Mountains of Central Otago, New Zealand, is one of the most significant gold discoveries in the region in decades. Led by Santana Minerals Limited, this project, is divided into several sub-projects, with the Rise and Shine (RAS) section holding the most promise. The RAS section alone is expected to produce significant economic returns to the country, generating an estimated NZ$2 billion in net profit over a 10-year period. Santana estimates close to NZ$1 billion in royalties to the central government.
The company has chosen to utilize cyanide, a very common method for gold extraction. In addition, the type of rock seen in Central Otago also releases large quantities of arsenic. Both cyanide and arsenic raise significant concerns about the risk of potential negative impacts on our environment, waterways, and plant, animal, and human health.
What is Cyanide?
Cyanide is a highly toxic chemical compound with the formula CN−, commonly used in various industrial processes, including gold mining. In mining, cyanide is employed to leach gold from ore, a process that, while effective, has sparked significant environmental and health debates due to its potential for contamination and toxicity.
Extraction of Gold Using Cyanide
The Santana Minerals gold mining project, specifically the Rise and Shine (RAS) mining project in Bendigo, will employ cyanide leaching, a method where gold is extracted by dissolving the ore in a cyanide solution. The process begins with soil being dug up, crushed, and milled before being introduced to cyanide tanks where the gold is separated. Although safeguards like detoxifying cyanide tailings from 200 ppm to 20 ppm (parts per million) are in place, the process still poses substantial risks. The crushed and milled material is treated with cyanide, and the resulting tailings are processed to reduce toxicity. However, the environmental challenges and the risk of accidental spills remain a significant concern.
The Cyanide Code
The Cyanide Code is a voluntary program that promotes the safe management of cyanide in gold mining, aiming to protect human health and the environment. Santana Minerals has not yet signed up to the Cyanide Code, raising concerns about the company's commitment to these safety and environmental standards. According to second-hand sources, the company may consider joining only if recommended by their consultants.
Arsenic in Rocks and Soil
What is Arsenic?
Arsenic is a naturally occurring element found in rocks, soil, water, and air. It is a metalloid, meaning it has properties of both metals and non-metals. While arsenic can exist in both organic and inorganic forms, the inorganic type is more toxic and is often associated with environmental pollution.
Arsenic in Rocks
Rocks naturally contain arsenic, typically in small amounts (1-5 ppm). Some rocks, especially igneous and sedimentary types, have higher concentrations. Common arsenic-bearing minerals include arsenopyrite, realgar, and orpiment. When these rocks break down into soil, arsenic levels can range from 0.1 to 40 ppm, with the Otago Schist containing slightly higher levels (5-20 ppm). Water interacting with these rocks can absorb arsenic and carry it into streams and estuaries.
Arsenic in Groundwater
Arsenic can also be found in groundwater as it flows through bedrock, such as schist, over long periods. This process can lead to the accumulation of high arsenic levels in the water. In gold-bearing areas, the interaction between arsenic-rich rocks and groundwater can result in concentrations exceeding 50 ppb. This is particularly concerning in regions like Otago Schist, where natural groundwater arsenic levels are already elevated.
Arsenic in Gold Mining
During the extraction process, arsenic can be released from the rocks and become concentrated in tailings, the waste material left after the gold is extracted. Historically, arsenic was often washed away into rivers and the sea, but modern mining practices involve storing arsenic-bearing tailings in dams to prevent environmental contamination.
Environmental and Health Implications
Risk of Contamination
The real danger occurs if a tailings dam, which holds arsenic-bearing waste from mining, leaks or collapses. This risk is heightened by increasingly common heavy rainfall, as seen in recent seasons across Central Otago, New Zealand, or during earthquakes. Such a disaster could release both cyanide and arsenic into the environment, contaminating water sources and soil. The presence of both arsenic and cyanide is particularly hazardous, posing significant risks to environmental and public health.
Impact on Water
Water sources near the mining site, including the creeks that feed into Bendigo Creek and Lake Dunstan, are at risk of contamination from cyanide, arsenic, and other chemicals used and released in the mining process. During rain events, these creeks, which typically run dry, could carry contaminants into larger water bodies, potentially affecting local aquifers and the broader ecosystem. The water used in the mining process will be pumped from the Bendigo Bore over a 12km pipeline, adding another layer of complexity and potential environmental impact.
Impact on Soil
The soil in the Rise and Shine area, characterized by its low permeability due to underlying schist rock, is also at risk of contamination. Cyanide, arsenic, and other chemicals used in the extraction process could seep into the soil, potentially impacting local agriculture, including nearby organic vineyards. The natural seepage on surrounding land will be interrupted and diverted, which could further disrupt the local soil ecosystem.
Possible Health Effects of Exposure to Cyanide in Human Health
Cyanide is extremely toxic, and exposure can lead to a range of serious health effects. Acute exposure to cyanide, even in small amounts, can cause immediate symptoms such as headache, nausea, dizziness, and difficulty breathing. In severe cases, it can lead to respiratory failure, seizures, and cardiac arrest, potentially resulting in death within minutes if not treated promptly. Chronic exposure, although less immediate, is also dangerous. It can result in neurological damage, impairing cognitive function and motor skills, and may also lead to chronic fatigue, thyroid dysfunction, and cardiovascular problems. Cyanide’s interference with cellular respiration means that long-term exposure can cause gradual organ damage, particularly affecting the brain and heart.
Possible Health Effects of Exposure to Arsenic in Human Health
Arsenic exposure, particularly through contaminated water or food, is a major public health concern due to its cumulative and long-term effects. Chronic exposure to arsenic is associated with an increased risk of developing several types of cancer, including skin, bladder, lung, and liver cancers. It can also cause significant skin conditions, such as hyperkeratosis and pigment changes, which are often precursors to skin cancer. Beyond its carcinogenic effects, arsenic can lead to cardiovascular diseases, including hypertension and ischemic heart disease, due to its ability to damage blood vessels and interfere with normal heart function.
Arsenic exposure can also have profound effects on the nervous system, leading to symptoms such as numbness, tingling, and pain in the extremities—a condition known as peripheral neuropathy. Additionally, there is evidence that chronic arsenic exposure can impair cognitive development in children and contribute to reproductive issues, including miscarriages and birth defects.
Short-term Development Can Lead to Long-term Setbacks
The Rise and Shine, RAS, Bendigo mining project represents a significant economic opportunity for the region, but it also brings considerable environmental and health risks, particularly related to cyanide use and arsenic release in gold mining. Public engagement and oversight will be crucial in ensuring that the benefits of this project do not come at an unsustainable cost. Sometimes, short-term development can lead to long-term setbacks.
Local residents and stakeholders are encouraged to stay informed and involved in the development of the Santana Minerals gold mining project. The balance between economic benefits and environmental health is delicate, and public oversight is essential in holding the project accountable. Let's stay informed about the impacts of cyanide and arsenic in gold mining to have a better understanding of the Ophir Bendigo mining project.
