Rheological regulation of high-solids iron concentrate slurry by anionic polyacrylamide and its compatibility with reverse flotation

Efficient transportation of high-solids iron concentrate slurry is often constrained by strong interparticle networks, whereas polymeric rheology modifiers may interfere with reverse flotation. This study evaluated an anionic polyacrylamide (APAM) for rheological regulation and flotation compatibility by integrating rheological measurements, batch flotation, adsorption analysis, zeta-potential measurements, FTIR spectroscopy, and induction-time measurements. At 50 g·t −1 APAM, the apparent viscosity at 200 s −1 decreased by 24.87 %, while increasing the dosage to 60 g·t −1 provided only limited additional reduction. Over the dosage range of 0–60 g·t −1 , the Fe grade decreased from 66.5 % to 66.0 % and Fe recovery from 82.0 % to 81.0 %. APAM preferentially adsorbed on hematite, with a maximum adsorption capacity of 0.750 mg·m −2 , compared with 0.275 mg·m −2 on quartz. The accompanying increase in negative hematite surface charge was consistent with weakened particle interactions in the slurry. In contrast, limited APAM adsorption on quartz reduced the maximum collector adsorption capacity by no more than 3.0 %. In the presence of collector, the induction time increased only slightly from 111.7 to 145.3 ms at APAM dosages up to 50 g·t −1 , but reached 216.7 ms at 60 g·t −1 . These results demonstrate that APAM establishes a rheology-flotation compatibility window by preferentially regulating iron-bearing particle networks while causing only limited perturbation of the quartz-collector interface. Under the investigated conditions, 50 g·t −1 APAM provides a favorable balance between rheological improvement and reverse flotation compatibility.