Tackling the pumping of foaming slurries

By Jay Chapman, Global Practice Lead Pipelines, Ausenco

Pumping a very foamy slurry in an iron ore processing plant froth flotation circuit can compromise operations by reducing pumping capacity and efficiency, increasing pump maintenance, and causing messy clean-up situations when sumps and tanks overflow. Introducing frothing agents and blowing air through the slurry enables the separation of silica from iron ore, but once that job is complete, the froth is not desirable. Foamy slurries generally contain a large amount of solid particles and air bubbles caused by froth densification. Air bubbles increase vibration, wear, noise, heat and cavitation in the pumps, and reduce pump performance.

Quartz, the main waste mineral present in iron ore bodies, is typically reverse floated. In this process, an ether-amine is used as a collector and as a frothing agent.

Slurry pH is key to proper flotation, but following the flotation process the pH needs to be dropped from 10.5 to 7.5 in order to reduce the additional foam pumping complexity. In our analysis of the foam formation problem, four compounds are evaluated to neutralize the floated tailings slurry:

  • Carbon dioxide
  • Acetic acid
  • Hydrochloric acid
  • Industrial acid

Reducing slurry foam before it arrives at the centrifugal pump suction nozzle is the main goal of our solution. After neutralization, some foam persists, but with significantly reduced stability.

Our solution also focuses on further reducing foam after neutralization. After acid dosing, high pressure water is sprayed on the treated slurry as a complementary treatment to further take advantage of bubble instability.

Ask us about the successful solutions we provide for tailings pipelines and in-plant slurry pumping, and how they might apply to your projects.

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