The promising results obtained by the research team of the Metallurgical Engineering Department led them to apply for a patent for a “Method for extraction of copper in solution from concentrates, with retention of iron in solids.”
The group made up of Dr. Patricio Navarro, Dr. Cristian Vargas and Daniel Espinoza, developed a pre-treatment of copper concentrates, under certain conditions of temperature and addition of reagents, so that following a 30 minute dissolving process, after just three to four days, 70% of the copper is dissolved - a very high percentage compared to the current rates.
There are certain copper ores (sulfide ores), which are very difficult to treat by hydrometallurgical processes, because the treatment processes are extremely slow. After a very long time, the copper dissolution reached by the industry is extremely low, around 20%. This problem was the starting point for the study that culminated in this innovative methodology.
“Another strength of our proposal is that in traditional leaching processes, the copper is dissolved, along with a large amount of iron that is present. On the other hand, using this method, we dissolve 70% of the copper, but we do not dissolve more than 1% of the iron, so we are recovering a lot of copper in very short times, while separating the copper from the iron. What is important about this innovation is that we are dissolving minerals that are difficult to treat, separating copper from iron and, as a third positive point, minimizing the use of water. There are three relevant aspects of this patent”, Dr. Navarro pointed out.
Robust response to an unsolved problem
There are two types of copper ores: sulfides and oxides. Oxides are treated by a very successful method, but there is a problem: oxidized copper reserves are strongly decreasing and will continue to do so, which will mean that a large part of the existing facilities will fall into disuse or the amount of copper production, by this means, will go down.
On the other hand, copper sulfides are treated by another process: smelting. However, the amount of concentrate smelted in Chile is no more than 25%; the rest is sold abroad as copper concentrate. “ The material we are selling has little processing; it is almost pure raw material. The current scenario shows a decrease in copper ores, resulting in a large number of industrial facilities with lower production and, of this production, it is sold because the smelters cannot smelt any more. Why not develop processes so that part of this concentrate can be treated using our technology and thus produce more elaborated copper and reduce the sale of material with less elaboration?”, added Dr. Navarro.
The mining industry will be strengthened by the patented methodology. “We are bringing innovation to the industry and the patent will invigorate the sector. At the national level, the treatment of concentrates by means of hydrometallurgical processes is being strongly studied, but what boosts our development is that we are recovering a lot of copper in very short times. This sets us apart," added the academic.
For Daniel Espinoza, it was an honor to participate with two such outstanding academics and to have achieved such an innovative patent. “This will have an impact on a treatment that is done at a national level and which addresses a problem that has not been able to be solved. The goal is to raise it to an industrial scale and bridge an important gap in copper recovery with a new methodology that also minimizes water. We specialize in hydrometallurgy and electrometallurgy and the patent is a starting point to reach processes upstream and downstream of our method. I am very grateful to the students who participated, who carried out the experiments, who projected, who gave feedback, who gave many ideas that made this work evolve”, he said.
Dr. Cristian Vargas, who is also the dean of the Faculty of Engineering, emphasized that the patent has an impact on the contingency of sulfide ore treatment. “It is the beginning of a series of developments and transfers to the industry of a new technology of great value for the current extractive metallurgy of sulfides. I am very happy to contribute to the needs of the country and the mining industry. In terms of developments for the sector, the Faculty continues to lead in different areas thanks to different projects carried out in each academic unit, achieving the development of processes that have allowed us to advance in the transfer of different innovations," he emphasized.
These three years of work, which included several graduate students, were arduous but very motivating for those involved, who emphasize that the methodology will continue to be optimized and improvements will probably be made on what has already been obtained. The next stage is that of scaling up, in order to access larger quantities of material during piloting.
This patent contributes to the Department's leadership at a time when innovation in mining needs to be energized quickly.