Reducing mine water use in arid areas through the use of a byproduct road dust suppressant

Abstract

Water scarcity is a critical global-scale social risk. Several factors are affecting the availability of fresh water, like global population growth and the increase of industrial activities. Particularly in the mining industry, water is a critical resource for mineral production and road maintenance. Haul roads in surface mining operations are traditionally treated with large amounts of water to reduce dust emissions caused by large trucks that generate up to 97% of mine dust that reduces safety and mining productivity. An alternative to reduce dust in mining roads is the use of Magnesium Chloride Hexahydrate (6H2O·MgCl2), which is a byproduct of the local lithium. So far, there is no scientific evidence that combines laboratory and field research to assess the effectiveness of an industrial byproduct used as a dust control for mining haul roads. This paper reports a quantitative analysis of the effectiveness of 6H2O·MgCl2 in reducing operational water based on a laboratory and field study. Laboratory results show an important water retention effect in 6H2O·MgCl2 treated soils compared to untreated soils. In addition, results showed that soils exposed to higher air relative humidity increases the water absorption from the air, confirming the hygroscopic property of 6H2O·MgCl2. Field results collected for a year in a copper mine located in an arid area of Chile showed that water consumption in haul roads treated with water only is on average 153 times higher than water consumption in roads treated with 6H2O·MgCl2 brine. In other words, 6H2O·MgCl2 brine treatment allows approximately 99% of water saving. The dust monitoring system using a laser device demonstrated that, on average, dust emissions are 3.4 times higher in roads treated with water only than in roads treated with 6H2O·MgCl2 brine. Overall, the study concludes that using 6H2O·MgCl2 brine effectively reduces water consumption used for dust suppression in haul roads, demonstrating that the use of 6H2O·MgCl2 byproduct is a very promising material for addressing water management issues in the mining industry.