Optimization of Operating Parameters on Dry Grinding of Calcite in a Stirred Media Mill Using the Box-Behnken Design

Abstract

The optimization of the operating parameters of a stirred media mill in the dry grinding of calcite was investigated. A three-level Box-Behnken design was used for the purpose of examining the impact of four independent factors, the stirrer speed (SS), grinding time (GT), media filling ratio (MFR), and solid mass fraction (SMF), on the product particle size (d50). For the purpose of establishing an empirical correlation between operating parameters and responses, a series of experiments were carried out. Variance analysis showed a reasonably good value for d50 (R2 = 0.965). According to the software solutions, the optimum conditions for minimizing the d50 size were found to be 573 rpm stirrer speed, 11.18 min grinding time, 63% media filling ratio, and 11.52% solid mass fraction, with 3.78 µm for the d50 size. To verify the improvement of grinding, verification tests were performed using the above-mentioned optimum conditions and the average d50 size and standard deviation were found to be 3.83 µm and 0.025, respectively. The average d50 value obtained was smaller than those obtained in the 27 tests. Furthermore, when the optimum result obtained from the experiments was compared with the result obtained using the software, a 22% energy saving was achieved. The impacts of grinding on the structural characteristics of calcite particles were characterized by XRD analysis. XRD measurements indicated that no change was observed in the peak areas of ground calcite specimens compared to the untreated calcite specimen.

Environmentally Friendly Green Synthesis of Fine Particles by Dry Mechanical Processes Toward SDGs: A Review

“…For the achievement of SDGs, the improvement of energy consumption in the dry grinding processes is significantly important. Many researches relating to the analysis of energy consumption discuss the energy efficiency using the specific grinding energy and/or electric power consumption (Altun et al, 2015;Altun et al, 2019;Blanc et al, 2020;Katircioglu-Bayel et al, 2020;Ngamnikom and Songsermpong, 2011;Ogonowski et al, 2018;Tamura et al, 2017;2020). In particular, Prziwara, Kwade and co-workers (Prziwara et al, 2018a;2018b;2018c;2020a) have actively studied in detail the effects of grinding aids on the grinding efficiency in dry fine grinding processes.…”

Mechanochemical Treatment of Historical Tungsten Tailings: Leaching While Grinding for Tungsten Extraction Using NaOH

“…It was observed that the stirrer speed (D), temperature (A), and digestion time (B) had positive effects, meaning an increase in these main factors would increase the W recovery. The stirrer speed had the largest contribution of 58.5% because it relates to the particle size reduction, increases the surface area, and enhances the reactivity of scheelite [10,23]. It also enhances mass transfer in the highly viscous NaOH digestion solution and continuously removes the Ca(OH) 2 solid product layers that form on scheelite mineral particles as the accelerated rate-determining chemical reaction (Equation 1 Despite temperature and digestion time individually having a positive effect on W recovery, their interactions (AB) showed a negative effect, and this contribution was larger than that of the individual factors.…”

“…Reducing both the stirrer speed and the digestion time to have a high leaching temperature had a more negative effect on W recovery because the mechanical activation of scheelite was reduced. With the coarser tailings used in this study, particle size reduction, which is essential for increased scheelite reactivity [10,23], is less enhanced.…”

“…The tailings used in this study were also much coarser (>75 µm) than the scheelite concentrates used in other scheelite leaching studies; hence, when selecting factors to optimize the LWG process, factors that improve both scheelite leaching kinetics and grinding in a stirred media mill were considered [12,23]. The effects of leaching temperature, NaOH solution concentration, mineral particle size, liquid/solid ratio, and stirring speed are significant to both the digestion of scheelite by NaOH and the leaching rate [5,10,24].…”

“…The effects of leaching temperature, NaOH solution concentration, mineral particle size, liquid/solid ratio, and stirring speed are significant to both the digestion of scheelite by NaOH and the leaching rate [5,10,24]. These effects have been investigated in various studies using different statistical and graphical techniques [23,25], and in this study, this approach was also taken.…”