Modeling and Optimisation of Multigravity Separator for Recovery of Iron Values from Sub Grade Iron Ore Using Three Level Three Factor Box Behnken Design

摘要

In this study, a three level, three factor Box- Behnken factorial design combined with Response Surface Methodology (RSM) for modeling of process parameters of Multi Gravity Separator (MGS) for recovery Iron values from sub grade iron ore, Deposit No. 5, Bailadila complex has been developed. The three significant operational parameters of MGS, Drum rotational speed, Drum inclination and wash water Flow rate were considered in the experimental work and all other parameters like feed percent solids, shake frequency and shake amplitude were maintained constant. The ‘as received’ sub grade iron ore sample is admixture of lump and fines and chemically assayed 40.80% Fe, 40.90% SiOsub2/sub, 0.24% Alsub2/subOsub3/sub and 0.22% Loss on Ignition (LOI). Experiments were conducted with representative sample ground to -100 mesh (0.152mm) as per the design matrix. The obtained results were evaluated with the Box-Behnken factorial design, RSM and also Quadratic programming (QP). Second order response functions were developed for grade (%Fe) and recovery (% yield) of the concentrate fraction. Taking advantage of quadratic programming (QP), it was observed that maximum grade of 64.00% Fe achieved at a drum inclination of 3 degrees, wash water flow rate of 6 Liters Per Minute (LPM) and at a drum rotational speed of 175 Revolutions Per Minute (RPM). Similarly a maximum concentrate recovery (Yield) of 67.87% by weight could be achieved at 5 degrees drum inclination, 2 LPM wash water flow rate and at a drum rotational speed of 225 RPM. Predicted values of responses obtained using model equations were in good agreement with the experimental values. The influence of the process variables of multi gravity separator on concentrate grade and recovery were discussed.