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Hostaflot NP107 Improves Mineral Collection at Lower pH Reduces Lime Consumption

The Bottom Line

The use of Clariant’s Hostaflot NP107 collector to lower pH for copper and molybdenum recovery leads to…

  • 60% reduction of lime consumption in rougher flotation
  • Mineral recovery and concentrate grade unaffected by lower pH
  • Less lime storage requirements and truck traffic
  • Customer savings of approximately $1 million dollars annually


Sulfide ore producers often use lime to increase pulp pH in an effort to optimize mineral recovery. One copper and molybdenum mine in Chile employs lime at a dosage rate of more than 1 kg/ton of ore to increase the pulp alkaline levels from an average pH 7 to pH 11.

Mine operators looked to Clariant for a solution to reduce pulp alkaline levels while maintaining recovery rates achieved at the higher pH. They also wanted to reduce processing costs associated with lime, which averaged from $0.15 to $0.20 per ton of ore.

With a customer-established target alkaline reduction from pH 11 to pH 9.5, Clariant engineers tested many different collector formulations to reduce required rougher flotation pH levels, prevent losses of copper and molybdenum, and maintain metal concentrate grade. The dosage rate of collector also had to lower overall processing costs.

Secondary benefits desired by the customer were to improve safety by lowering truck traffic delivering lime to the mine. Additionally, a reduction of lime consumption would increase the storage capacity for lime without expanding the facilities, critical to this operation remotely located in the mountains where truck traffic is restricted at times during the winter.


Increased global consumption of minerals has mining companies searching for ways to improve operating efficiencies in order to supply this growing demand. Global competition from other suppliers also forces mines to discover new approaches for reducing long term operating costs, so they can remain competitive.

To achieve the desired copper and molybdenum recovery rates, the beneficiation process for a large mining operation in Chile required a pulp pH of 11 at the rougher flotation using its standard collector. This consumed more than 1 kg of lime per ton of ore to raise the pH from a natural average of 7, which added approximately $0.20 per ton of ore to the processing costs.

Clariant worked with the mine to develop a new collector that would offer similar recovery concentration levels of copper and molybdenum at a lower pH. Clariant engineers focused on reducing required pH levels at the rougher flotation stage to optimize lime saving and lower mineral processing costs.


Using Clariant’s lab facilities, Clariant engineers tested ore samples provided by the mine. Multiple trials of different formulations were evaluated to determine the reagent that delivered the desired recovery rates at the targeted pH, given the mine’s feed material.

After careful analysis, Clariant engineers determined that Hostaflot NP107 proved to be the best performing reagent for feed material. In the lab, it exhibited the ability to deliver the desired mineral recovery rates at targeted alkaline levels of pH 9.5.

Mine employees conducted their own lab tests using Hostaflot NP107, and the reagent delivered results consistent with Clariant’s analysis. Approved for industrial trial, Hostaflot NP107 was tested in the plant for three months, operating at pH 9.5.

Dosage rate between the collector the mine previously used and Hostaflot NP107 remained unchanged. However, Hostaflot NP107 achieved the same mineral recovery and concentrate grade results at pH 9.5 vs. a pH 11, resulting in a significant lime savings.


With successful trials and field implementation, Clariant’s Hostaflot NP107 is now the standard collector used by the Chilean copper and molybdenum mine. This Clariant collector…

  • Reduces lime consumption in rougher flotation by 60%
  • Provides a global process lime savings of 30%
  • Maintains metallurgical results and quality of concentrate previously achieved at higher pH
  • Lowers truck transit at the mine to improve safety
  • Increases lime storage capacity without expanding facilities
  • Delivers a potential increase in molybdenum (and gold) recovery
  • Decreases some molybdenum oxide dissolution which reduces it being discharged into the environment
  • Saves the customer, on average, $1 million annually in processing costs


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