PNS (Poly Naphthalene Sulfonate)

  • In froth flotation, PNS (Poly Naphthalene Sulfonate) acts as an anionic surfactant commonly used as a collector in froth flotation. PNS has a hydrophobic (water-repelling) tail and a hydrophilic (water-attracting) head, which makes it an effective collector of hydrophobic minerals such as sulfides.

    PNS is added to the flotation cell’s slurry of ore and water. The PNS molecules attach themselves to the surface of the mineral particles, creating a hydrophobic surface. This makes the mineral particles more likely to attach to air bubbles and rise to the surface of the flotation cell, where they form a froth layer that can be skimmed off to produce a concentrate.

    PNS is effective in the flotation of various sulfide minerals, including zinc, copper, molybdenum, chalcopyrite, and galena. PNS can improve the recovery and grade of these minerals, resulting in a higher concentrate yield.

    PNS is a beneficial reagent in froth flotation, which can be explained as follows:

    • Adsorption: PNS molecules can adsorb onto the surfaces of mineral particles, particularly sulfide minerals such as chalcopyrite, sphalerite, and molybdenite. This adsorption is due to the hydrophobic nature of the PNS molecule and the presence of sulfonic acid groups that can form hydrogen bonds with the mineral surface.
    • Frothing: PNS can also act as a frothing agent in froth flotation, helping to create a stable froth that can carry the mineral particles to the surface. This is because PNS molecules can lower the surface tension of the water in the flotation cell, allowing gas bubbles to form and stabilize.
    • Selectivity: PNS can improve the selectivity of mineral separation by preferentially adsorbing onto the surfaces of certain minerals. This can be particularly beneficial in complex ores containing multiple minerals with similar properties.
    • Higher concentrate yield: PNS can improve concentrate yield in zinc, copper, molybdenum, and other ores by increasing the recovery of valuable minerals. This is due to the increased adsorption of the PNS molecules onto the mineral surfaces, which can increase the probability of the froth collecting the mineral particles.
    • Cost-effectiveness: PNS is a relatively inexpensive reagent easily incorporated into froth flotation processes. This can lead to cost savings in the production of minerals, particularly in large-scale mining operations.

    References:

    • Zhang, H., Guo, X., Wang, H., Chen, H., & Li, H. (2019). The role of poly naphthalene sulfonate on copper sulfide flotation. Minerals Engineering, 143, 105898
    • Liu, Y., Hu, Y., Huang, Q., & Liu, W. (2019). Influence of poly naphthalene sulfonate on the flotation separation of molybdenum and copper sulfides. Minerals Engineering, 135, 24-30.
    • Liu, J., Sun, W., Hu, Y., & Cui, W. (2018). Flotation of copper oxide minerals using ethylene diamine tetra-acetic acid as an activator. Minerals Engineering, 117, 20-24.
    • Yang, Q., Li, Y., Han, J., Wen, L., Liu, Q., & Li, W. (2021). Selective flotation of copper and lead sulfide minerals in mixed sulfide ore using poly-naphthalene sulfonate. Minerals Engineering, 172, 107112.
    • Wang, L., & Forssberg, K. S. E. (1995). Effect of polymeric dispersants on sulfide ore flotation. Colloids and Surfaces A: Physicochemical and Engineering Aspects, 96, 121-129.

    PNS can also be utilized to handle mine tailings, which are the waste materials left over after the extraction of minerals from the ore. A challenge in managing mine tailings is their transportation and deposition in tailing ponds or other storage facilities. Tailings can be very dense and difficult to pump and place in a controlled manner, leading to issues such as blockages, overflow, and environmental damage.

    PNS can be used as a dispersant in handling mine tailings, which can help break up the dense particles and improve the flowability of the slurry. This can make it easier to pump the tailings over long distances and deposit them in a controlled manner, reducing the risk of blockages and overflow.

    Water Reduction improvements in the handling of mine tailings, through the use of PNS, can also have environmental benefits. By improving the flowability of the slurry, less water may be required in the transportation and deposition process, reducing the amount of freshwater needed and the potential for water pollution.