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Selective Hostaflot F Collector Improves Copper Concentrate Quality

The Bottom Line

The use of Clariant’s selective Hostaflot F to float copper and molybdenum in high impurity feed…

  • Significantly improves copper concentration grade over standard collectors
  • Improves recovery of molybdenum
  • Increases pure copper production efficiency
  • Produces a cleaner burning concentrate for the smelting process
  • Saves the customer $30 million annually when producing copper


A large Chilean copper and molybdenum mine and smelting operation began extracting ore from a section of the mine high in pyrite. With iron-to-copper ratios above 2:1 in the ore, the copper concentrate grade dropped from 29-30% to 24-27% when using the standard xanthate collector, reducing production in the smelter and increasing gasses emitted by the smelting process.

Representatives from the mine approached Clariant and other reagent suppliers to develop a selective collector to replace its standard collector when processing ore that is high in pyrite. The customer established a target copper concentrate grade of 30% for material sent to the smelting furnaces. If possible, the collector was also required to improve collection of molybdenum.

By developing a selective collector to improve flotation of copper and molybdenum, Clariant enabled the customer to achieve its objectives of: a) maintaining fine-grade copper concentrate; b) reducing gas emissions generated by the smelters; c) lowering costs to produce pure copper.


Impurity levels present in mineral deposits often fluctuate significantly from one section of a mine to another. As impurity levels rise, the concentrate grade quality by the flotation process drops as standard collectors struggle to effectively separate the minerals from the gangue.

One large copper and molybdenum operation in Chile experienced poor performance of its standard collector while mining deposits with high levels of pyrite. AS the iron-to copper ratio rose above 2:1, copper grade dropped to as low as 24%, not achieving the targeted 30% levels required by the customer’s smelting furnaces.

When processing copper concentrate below 30%, production of fine-grade copper suffered. The furnaces were required to process more concentrate to produce the same amount of pure copper. High concentrate impurity levels also resulted in increased gas emissions, which the customer could not fully capture.

Clariant worked with the mine to develop a highly selective collector, designed specifically to address the high pyrite impurity. Clariant engineers focused on reagents that floated the copper and molybdenum in a selective way and made the pyrite impurity less likely to float.


From high-impurity ore samples provided by the mine, Clariant engineers conducted in-house lab experiments developed to improve mineral collection. Multiple formulations of the specialized Hostaflot collector were put through trials to customize the right collector for the mine’s feed.

In-depth analysis showed that Hostaflot F increased copper concentrate grade and performed the best of all reagents tested. In the lab, copper concentration increased to levels that achieved the customer’s target.

Hostaflot F went through a series of lab trials performed by the mine’s technicians. The customer’s lab results correlated with Clariant’s findings, and the collector was qualified for full-scale field trials.

At the flotation cells, collector dosage rates were adjusted to get the correct amount that floated copper/molybdenum and suppressed pyrite flotation without overflows and material loss. Clariant and mine engineers determined that 25 to 30 grams/ton of ore processed was the correct dosage for this application. A dosage of 8 to 10 grams/ton of the standard xanthate collector was also employed to avoid higher selectivity and potential drop of copper recovery.

Total collector cost increased by only $2 million annually while saving the customer $30 million in smelting costs, representing a 15-time return on investment.


In applications where the iron-to-copper ratio exceeds a 2:1, Clariant’s highly selective Hostaflot F collector:

  • Increases copper concentrate level to above 30%
  • Improves collection of molybdenum
  • Decreases pyrite’s ability to float
  • Produces a concentrate that burns cleaner in smelting furnaces
  • Allows smelters to maintain pure copper production levels, while processing less concentrate food material
  • Helps to reduce smelting equipment wear
  • Saves the customer $30 million annually in smelting costs


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