RECLAMATION OF POTASH MINE SLIME TAILINGS USING CROSS-LINKED POLYACRYLAMIDE HYDROGEL
Cameron, Kathleen D
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Potash mine slime (PMS) tailings, a silty clay marine sediment by-product of potash mining, can have electrical conductivities> 200 mS em" and sodium adsorption ratios> 60.makingthe tailings extremely saline-sodic in nature and difficult to reclaim. The fine texture of the slime combined with the high Na content make the tailings vulnerable to dispersion, erosion and compaction. Compaction, water logging and excessive Na and dissolved salts are barriers to successful vegetation establishment and growth within the potash mine slime tailings. Although a number of reclamation techniques have been researched, none to date have proven sufficiently successful to utilize on a large scale. Addition of synthetic polymer, cross-linked polyacrylamide hydrogel, was tested for its effectiveness in improving chemical conditions in potash slime tailings. A greenhouse study indicated that addition of polymer, specifically incorporation of cross-linked polyacrylamide hydrogel at the 0.2% wt./wt. rate, was effective in decreasing salinity and sodicity and allowing vegetation to be established in potash mine slime tailings. The results also indicated that successful establishment would require a large quantity of good quality leach water and adequate drainage to remove the salts, to effectively reduce both salinity and sodicity. Bench top studies revealed that exposure to freeze-thaw cycles and incorporation of polymer in non hydrated form were most beneficial in promoting leaching of salts. Cross-linked polyacrylamide hydrogel was incorporated at 0.1%,0.2% and 0.3% by weight in a raised bed in a potash slime tailings holding pond near Vanscoy, SK. All treatments, including an unamended control, were irrigated with seven inches of water over a period of about seventy-five days. Samples, taken over a two year period indicated a significant decrease in both salinity and sodicity with polymer treatments being slightly more effective than the control. However, arise in the water table over the study period reduced the ability to detect significant treatment effects on leaching and salt removal in the field.