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 Editorials | Environmental | January 2008 
Science Can Show the Way to Cleaner Mining
 Diego Cevallos - Tierramérica
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Mexico City - In 2010 the Mexican mining company Peñoles could be using a unique, more environmentally-friendly method for extracting gold and silver from ore - but convincing the company to consider the new approach was not easy.
The method, created by researchers at the public Metropolitan Autonomous University (UAM) here, involves an electrochemical reactor that would make unnecessary several steps in the conventional process of industrial mining. Furthermore, it is cheaper and does not generate waste.
Current methods use the poisonous cyanide and costly processes of heating up the ore to separate out the precious metals from the other minerals in the ore.
The reactor uses thyourea, a molecular compound similar to the urea obtained from the decomposition of plants or of hydrocarbons.
Thyourea, the oxidation of which is controlled with electricity, enters into action upon contact with the sandy or rocky material, and precipitates out the gold or silver. And the compound can be reused almost infinitely.
The reactor has been operating since mid-2007 in a cubicle of no more than 16 square metres at the UAM, and it is hoped that by 2010 similar reactors will be working at the Peñoles mine processing plants in the north-eastern state of Coahuila at four or five times the size of the prototype.
Peñoles, the world’s leading producer of refined silver and owner in Mexico of the deposit holding the world's largest reserves of the metal, in the central state of Zacatecas, sponsored and financed part of the UAM project.
The company, with monthly operations of more than 300 million dollars and exports around the world, contributed around one million dollars to bring the invention to the experimental stage and to channel it into industrial use.
But that contribution required an intense effort to convince the company's executives. The Peñoles mine in Coahuila created lead contamination affecting hundreds of nearby residents from the 1970s to 1990s.
"The industry executives don’t trust us, the researchers. The first thing they told me in Peñoles (12 years ago) was that the timeframe in which universities work is not their timeframe," Ignacio González, electrochemical researcher at UAM (Iztapalapa unit) and one of the reactor's inventors, told Tierramérica.
"We have to recognise that the scientists at Mexican universities are not accustomed to responding to the real needs of the companies, so it was very difficult to motivate Peñoles," he added.
José Luis Nava, the UAM researcher who led the process of taking the invention to the industrial scale, maintains that the reactor "promises a great deal for the future of the global mining industry."
The communities near the sites where the electrochemical reactor functions will not suffer contamination of any type, Nava told Tierramérica.
Once the reactor is in place, there will be significant economic benefits for Peñoles, according to González, though the company would not indicate the extent.
The patent for the invention in Mexico and Europe belongs to the UAM, but in other countries it is shared with Peñoles, which will see part of the royalties. It is hoped that other mining companies will want to implement this new, cleaner technology.
"There is nothing in the world like our reactor, and now that it will be moving to the industrial phase there will be a great deal of interest in the leading mining countries," which include Australia, Canada, United States and South Africa, González said.
Peñoles operates mines in several Mexican states and has investments in several Latin American countries. It is also the world leader in production of metallic bismuth and sodium sulphate, and Latin American leader in processing refined gold, silver and zinc.
The company's operations in Torreón, a principal city of Coahuila state, caused a scandal in the 1990s when it was found that Peñoles was releasing huge quantities of lead into the environment.
Twenty thousand people were contaminated by the lead. The authorities intervened, and the company accepted its responsibility, adopting lead mitigation measures and paying for part of the medical attention needed by the people affected.
Local doctors had been denouncing the contamination near the processing plant since the late 1970s, but at first Peñoles had tried to play down the importance.
In Mexico there are very few cases in which companies that are competitive on the international market enter into partnerships with researchers to seek solutions to industrial problems.
There are more than 2,000 centres of higher education in Mexico, of which 30 are public, like the UAM. The public universities carry out 80 percent of the country’s scientific activity.
The UAM electrochemical reactor is one of the few effective contributions of the universities to Mexico's industrial sector. In this country, the government earmarks less than 0.5 percent of the national budget to scientific and technological development.
Diego Cevallos is an IPS correspondent. Originally published by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme and the United Nations Environment Programme. |
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