MINING CHEMICALS up to full NaSH replacement, at relatively low dosages. It says the product operates effectively across a wide pH range under both air and nitrogen conditions, without H₂S or other toxic gas formation. Typical dosage requirements are significantly lower than NaSH, generally in the range of 0.3-3 kg per tonne of the Cu-Mo bulk concentrate, contributing to reduced treatment costs and simplified reagent handling.
Operational experience, Syensqo says, shows that successful NaSH replacement is best approached in phases, starting in highimpact areas such as the rougher stage, where reagent consumption is highest, and where maximising molybdenite recovery and Cu depression are critical.“ This allows operators to capture early gains in safety and performance while maintaining circuit stability, before progressing toward other areas such as cleaners.”
In recent plant trials in a large Latin American Cu-Mo operation, AERO ® NR- 7361 replaced about 50 % of NaSH as a depressant in the rougher delivering an approximately 7 percentage point increase in molybdenum recovery, along with higher rougher Mo concentrate grades and improved flotation response.
Meanwhile, significant NaSH reduction with AERO ® NR-7361 led to the elimination of H₂S-related alarms, which contributed to safer working conditions and more stable uninterrupted plant operations. Reduced NaSH consumption also translated into tangible economic benefits, including estimated reagent cost savings of around $ 300,000 per year with additional upside linked to improved metal recovery.
At another operation, AERO ® NR-7361 replaced the incumbent copper depressant at a lower dosage, reducing total depressant consumption by approximately 60 % while maintaining both molybdenum grade and recovery.
Syensqo’ s NaSH replacement solutions have been successfully commercialised at a number of other mining operations. At one site, AERO ® 7260 HFP, a Syensqo polymeric NaSH replacement depressant, is used as a partial substitute for NaSH. Its application enhances copper depression as well as efficient penalty element depression, enabling the operation to meet stringent molybdenum concentrate quality and sales specifications, with a Mo grade exceeding 50 %.
In response to challenges at a site where high levels of insolubles in its bulk copper-molybdenum concentrate negatively impacted Cu-Mo separation, a tailored solution, AERO ® NR-7370, was developed. This product enabled the elimination of two depressant reagents in the molybdenum circuit and reduced NaSH consumption by 50 %. AERO ® NR-7370 is the result of
continuous improvement efforts, building on the performance of AERO ® NR-7361. As shown in plant trial data, the use of AERO ® NR-7370 in the primary rougher circuit delivers between 1 to 3 % higher molybdenum recovery compared to both NaSH and AERO ® NR-7361.
Syensqo:“ These results highlight that NaSH replacement is not simply a reagent substitution exercise, but an opportunity to optimise overall circuit performance. Successful implementation requires a holistic view of the flotation process, including control of pH, frother selection, dosage optimisation, mass pull control, and consideration of downstream impacts such as thickener performance. Adapting operating conditions, such as reagent schemes and conditioning strategies, is key to achieving consistent results.”
Lower dosages with Syensqo’ s AERO ® NR Series and reduced hazardous emissions simplify handling and transportation, while supporting broader sustainability objectives.
As orebodies become more complex and regulatory expectations evolve, the need for safer, more adaptable flotation chemistries will only increase. Innovations such as Syensqo’ s AERO ® NR Series it argues demonstrate that it is possible to move beyond traditional inorganic depressants, achieving a balance between metallurgical performance, operational