# Optimization of Multi-gravity Separator (MGS) Parameters for Specularite Ore Beneficiation: Evaluating Box–Behnken and Central Composite Designs

## TL;DR

This study compares two statistical methods to optimize a machine that separates iron-rich ore, finding effective settings to improve iron quality and recovery.

## Contribution

The first comparative assessment of Box–Behnken and Central Composite Designs for optimizing specularite ore beneficiation using a multi-gravity separator.

## Key findings

- Optimized MGS parameters achieved 63.97% Fe grade and 72.05% recovery.
- Central Composite Design showed better predictive performance than Box–Behnken Design.
- Optimal conditions included 143 rpm drum speed, 6.2 L/min wash water, and 4.5° drum slope.

## Abstract

This study investigates the optimization of multigravity
separator
(MGS) parameters for the beneficiation of specularite ore, using both
Box–Behnken design (BBD) and central composite design (CCD)
as response surface methodologies. The effects of the drum speed,
wash water amount, and drum slope on the grade and recovery of specularite
were evaluated. Results indicated that increased wash water and drum
slope generally enhanced the Fe grade, while higher drum speeds had
adverse effects. Conversely, recovery was maximized with lower wash
water amounts, lower drum slopes, and higher drum speeds. The comparison
between BBD and CCD designs revealed that both methods provided similar
optimal grade and recovery values, though with different parameter
settings. CCD demonstrated superior predictive performance with higher F-values and closer agreement between adjusted and predicted R
2. Multiresponse desirability optimization identified
optimum conditions of approximately a 143 rpm drum speed, a 6.2 L/min
wash water, and a 4.5° drum slope for CCD, achieving a composite
desirability of 0.891. Confirmation tests closely matched predicted
values with <1% deviation, validating model accuracy. The optimized
conditions yielded a specularite concentrate assaying 63.97% Fe with
72.05% recovery. The findings demonstrate that MGS, when appropriately
optimized, can effectively upgrade specularite ores to meet the quality
requirements of micaceous iron oxide (MIO) pigment production. This
work provides the first comparative assessment of BBD and CCD for
MGS-based specularite beneficiation and establishes a validated optimization
framework that integrates mineralogical, statistical, and operational
insights.