The Design and Use of a Laboratory-Scale Deslime Thickener

Selective flocculation and dispersion (SFD) is a process used to separate finely liberated (<25µm) hematite from gangue minerals. SFD, conducted in a deslime thickener, requires a specific water chemistry, a selective flocculant and a dispersant to be effective. This research focused on finding the most effective dispersant for the hematite concentration process using a laboratory scale continuous deslime thickener. The dispersants studied were sodium silicate, sodium henicosapolyphosphate (21-member polyphosphate), 2000 molecular weight (MW) polyacrylic acid (PAA), 4000 MW PAA and 7000 MW PAA. It was found that sodium henicosapolyphosphate at 0.05 pounds of dispersant per ton of ore yielded the best grade/recovery curve for iron. The 4000 MW polyacrylic acid at 0.25 pounds of PAA per ton of ore had an iron grade/recovery curve nearly that of sodium henicosapolyphosphate but yielded a lower phosphorus concentration in the product (down to 0.022% P).