Research and implementation of novel sludge depressants for potash ore processing

The processing of potash ores is often hindered by the presence of impurities such as clay, carbonate, and sulfate minerals, which actively sorb alkylamines used as cationic collectors, leading to increased reagent consumption and decreased flotation performance. To address this issue, preliminary desliming of the ore is typically combined with the use of organic depressants to reduce the sorption of alkylamines on sludge particles. Urea-formaldehyde resins (UFR) have demonstrated high efficacy as sludge depressants in potash ore processing. These resins bind to silicate-carbonate sludge and anhydrite, significantly reducing the sorption of alkylamines and thereby enhancing the selectivity of sylvite flotation. One such reagent, KS-MF, produced by Metadynea LLC, was found to be particularly effective due to its formulation, which includes 1–1.5 % free formaldehyde by weight and polymer-modifying additives that further boost its performance. As an alternative, Oligomer K-6 reagent, with a reduced free formaldehyde content, was developed. Further advancements led to the synthesis of a depressant containing less than 0.5 % free formaldehyde by weight. This depressant was modified with ethylenediamine, a light amine, making the depressant synthesis process both safer and more effective. Experimental studies have confirmed that urea-formaldehyde resins with amino alcohol-modifying additives, containing less than 0.5 % free formaldehyde by weight, provide similar benefits in terms of reducing alkylamine sorption and enhancing flotation selectivity. Comparative industrial trials conducted at PJSC Uralkali processing plants have demonstrated that the use of these novel depressants allows for high process performance, even when processing ores with elevated levels of insoluble residue. In conclusion, the introduction of these efficient and more environmentally friendly sludge depressant reagents offers several key benefits: reduced collector consumption, enhanced selectivity in sylvite flotation, and the ability to maintain stable processing indicators across a wide range of water-insoluble residue levels.