While authorities attempt to stop illegal gold mining nationwide, its use as a source of funding of criminal groups, and the destruction of multiple water sources, especially in departments such as Córdoba, Chocó and Antioquia, the academia is redoubling its efforts to recover the quality of the water affected by these metal mining processes.
Such is the case of the method for the treatment of cyanide-polluted wastewater, which resulted from research conducted by professors of EAFIT´s Environmental Processes Research Group (Gipab by its acronym in Spanish), and the Research Group in Intensified Reactive Processes with Separation and Advanced Materials (Prisma by its acronym in Spanish), from Universidad Nacional of Manizales.
"It is a treatment system implemented to transform cyanide using advanced oxidation processes. Reactivity allows them to quickly interact with different compounds and to transform them into simpler and environmentally friendlier substances", says Édison Hernán Gil, Gipab leader.
As explained by Professor Gil, oxidation aims at chemically transforming cyanide into less harmful substances such as cyanate, ammonium, nitrogen and carbon dioxide. Some of the advantages of this process are that, unlike other treatment systems, this does not generate sludge and there is no contaminant transfer from one phase to another in the process.
"There is dissolved cyanide that remains in the wastewater after gold extraction through leaching processes which does not react and is subsequently dumped into sources of surface water, despite being a toxic and potentially lethal substance to the environment and to human health. These processes generate water effluents with free cyanide, hydrocyanic acid and complexes formed through the association of cyanide with various metals. Both hydrocyanic acid and free cyanide are regarded as highly toxic and potentially lethal", explains the researcher.
Danger of death
According to the information reported by the Ministry of Health and Social Protection, cyanide is a highly reactive and toxic substance used in gold processing, chemical laboratories, paints, adhesives, solvents, enamels, herbicides and industries such as jewelry and plastics. It may enter the body by inhalation or through the skin, the conjunctiva of the eyes, and the intestinal tract.
The Guías para el Manejo de Urgencias Toxicológicas (Guidelines for Toxicological Emergency Management) edited by this Ministry, report that the intake of 200 milligrams of this chemical could cause death. The poisoning symptoms “include headache, nausea, a smell of bitter almonds, dyspnea, confusion, syncope, seizures, coma, respiratory depression and heart failure. In case of survival, the patient may have chronic neurological sequelae.”
Consequently, Professor Gil highlights the benefits of using this method on both the environment and human health, which, despite not yet having the support of any industrial sector, could be applied to mining and electroplating procedures without interfering in production processes or increasing the cost of metal extraction or deposition.
It is with good reason that, and as stated by Professor Izabela Dobrosz-Gomez from Prisma to the Universidad Nacional newspaper, the mining industry wants to find processes to facilitate the reduction or removal of cyanide in the wastewater of its processes, in part bound by Law 1658 of 2013 that banned the use of mercury in gold mining, which will be implemented in a phased manner: in seven years for the industrial sector, and in two years for the mining sector.
In this way, the research and teaching efforts driven by the Colombian academic sector are preparing the ground for a second chance for the country’s bodies of water, although "it is necessary for the Colombian environmental legislation to be more stringent and demanding, and that compliance be ensured" for the massive implementation of these solutions, adds Édison Gil.
For more information:
Alejandro Gómez Valencia
Journalist - EAFIT Information and Press Area
Phone: 2619500 ext. 9931
E-mail: jgomez97@eafit.edu.co