Case Study Boliden Tara Mine: Pionera F-250 Substitutes Sodium Cyanide as Pyrite Depressant

A plant trial at Boliden Tara was scheduled where Pionera F-250 was added to the mill in the grinding circuit in place of cyanide in a randomised trial extending over seven months.

Data were only collected when the mill was operating at minimum normal defined load, and data from both online analysers and composite samples were available for analysis. 

From plant experience, the iron/lead ratio in the lead flotation feed is used as a proxy for process control. A significant fraction of the ore, roughly classified as having an iron/lead ratio below 3, is well-behaved. At iron/lead ratios above 3, the plant often faces challenges when producing an acceptable lead concentrate.

Initial laboratory flotation experiments and a full-scale plant trial revealed that Pionera F-250 biopolymer could replace cyanide as a pyrite depressant at the Tara mine in Ireland. The use of Pionera F-250 gives flotation recoveries similar to the use of cyanide as a pyrite depressant.

For the mine, the replacement of cyanide as a pyrite depressant represents a significant change. It has been a long-term goal to reduce cyanide consumption, and the results from the herein described plant trial are the first step.

Key takeaways:

• Plant operation data confirmed preliminary flotation tests indicating that Pionera F-250 is a valid replacement for sodium cyanide.
• Pionera F-250, a non-toxic, sustainable, and environmentally friendly reagent, provided the same performance as cyanide.

Plant trial data of lead grade in final concentrate with Pionera F-250 and Cyanide as Pyrite depressants.