Saturday, January 28

Researchers from Extremadura and Salamanca encapsulate “highly toxic” antimony residues


Antimonite fragment.

They have managed to convert a polluting material that is harmful to health, present in mines in the region that are not exploited, into filling or an alternative addition to construction materials.

PS

A team of researchers from the universities of Salamanca, Extremadura and Lorraine (France) have succeeded in encapsulating antimony residues in cement. In this way they have managed to convert a “highly toxic” product into a material suitable for filling mines or as an alternative aggregate in construction materials.

The work has been published in the journal ‘Journal of Cleaner Production’ and in it the authors show the potential of cementing to manage mining waste that contains antimony, “a toxic element that is considered a priority pollutant by the European Union, due to the significant environmental and health problems that it can cause.

In a multitude of products

Antimony is a chemical element that is used in the manufacture of a multitude of products, from mobile phones to glass, so its production, far from decreasing, “will increase in the coming decades,” they have detailed.

However, they have remarked that there is “a growing concern” about its wide distribution in the environment, since “antimony can reach high concentrations in the areas where it is exploited, especially if there has been poor management of the mining waste generated ».

Pollution

“Stibnite is the most important mineral and the main commercial source of antimony. But stibnite oxidizes very easily and can lead to the release of antimony which, above certain concentrations, can contaminate soil and water, cause toxic effects on plants, accumulate in them and be transferred through the trophic chain, threatening human health and ecosystems”, they have detailed through the press release issued by Irnasa.

At present, as they have explained, the main producer of antimony worldwide is China, where in mining areas the human intake of antimony is approximately 50 percent higher than the maximum tolerable intake. This intake comes from various routes such as water, vegetables, cereals or meat.

mines in extremadura

As detailed by the Irnasa-CSIC researcher Esther Álvarez Ayuso, in Spain, the main antimony mines are in Extremadura, but they are no longer exploited. «Its exploitation took place between the 40s and the 80s of the last century. However, the waste generated has not been properly managed and remains deposited in the environment,” she specified.

Given this problem, the team of researchers is developing methods to “prevent or minimize” the dispersion of this toxic element, one of which is encapsulation using cement, which, although it is not a new technique, “has hardly been explored for the treatment of residues with the presence of antimony”.

«We think that this method could have great potential for the treatment of this type of waste. It is an inexpensive technique and has already been applied successfully for the treatment of other elements that present a similar geochemical behavior. In addition, it allows different management options for the materials that are generated after the cementation process”, explained Álvarez Ayuso.

In this way, the team subjected the waste in the laboratory to different cementation processes, using Portland cement and calcium hydroxide as a binder, in different proportions, and has determined the “optimal” conditions.

Not allowed in landfills

«Under the conditions that we have selected in this work, we have managed to convert these wastes, which were characterized as toxic and not even admissible in hazardous waste landfills due to their high antimony leaching, into non-toxic waste and admissible in controlled landfills» , has underlined the Irnasa-CSIC researcher.

Being able to deposit this product in landfills is an option for the management of this waste, but not the only one, since “another of the strengths of the work” is that it verifies that the resulting material can be used to fill mines, since “It meets the required compressive strength values”, they have pointed out from Irnasa.

Likewise, according to the press release, they have observed that some of the mining waste studied has “great potential” to be used as substitutes for natural aggregates in construction materials.

“What we would be achieving is the treatment of waste, avoiding environmental contamination and in turn reusing it, preserving natural resources, which is very interesting from the point of view of the circular economy”, Álvarez Ayuso concluded in this regard. , who adds that the idea of ​​the team is to continue advancing in this approach through “future projects”.


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