Grinding Kinetics of Slag and Effect of Final Particle Size on the Compressive Strength of Alkali Activated Materials

Abstract

This study aims to model grinding of a Polish ferronickel slag and evaluate the particle size distributions (PSDs) of the products obtained after different grinding times. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs). Other parameters affecting alkali activation, i.e., temperature, curing, and ageing time were also examined. Among the different mathematical models used to simulate the particle size distribution, Rosin-Rammler (RR) was found to be the most suitable. When piecewise regression analysis was applied to experimental data it was found that the particle size distribution of the slag products exhibits multifractal character. In addition, grinding of slag exhibits non-first-order behavior and the reduction rate of each size is time dependent. The grinding rate and consequently the grinding efficiency increases when the particle size increases, but drops sharply near zero after prolonged grinding periods. Regarding alkali activation, it is deduced that among the parameters studied, particle size (and the respective specific surface area) of the raw slag product and curing temperature have the most noticeable impact on the compressive strength of the produced AAMs.

Grinding Behavior and Potential Beneficiation Options of Bauxite Ores

“…As can be seen in Table 3, which shows the calculated parameters K and M by fitting the Alyavdin equation to experimental data, the grinding rate constant K decreases from 0.206 to 0.043 when f c increases from 5% to 15%. It is also seen that M values range between 0.780 and 1.084, confirming the non-first-order grinding behavior of the ore [37,41,54]. Figure 4b) shows the presence of anatase that occurs in the form of individual microscale particles (<2 μm) widely dispersed within the diasporic core (center of the clast) as well as in the form of intergrown particles within the internal rings of hematite (inner-outer dashed line area) in the diasporic clast [11].…”

“…As can be seen in Table 3, which shows the calculated parameters K and M by fitting the Alyavdin equation to experimental data, the grinding rate constant K decreases from 0.206 to 0.043 when fc increases from 5% to 15%. It is also seen that M values range between 0.780 and 1.084, confirming the non-first-order grinding behavior of the ore [37,41,54].…”

“…These models consider that grinding follows a first-order law as reported in previous studies [37,38]. However, deviations from first-order kinetics have been observed for several mineral phases indicating that the breakage rate varies with grinding time [39][40][41]. For non-first-order kinetics, the following Equation (1) proposed by Alyavdin can be used to describe the grinding process [42,43],…”

New EAF Slag Characterization Methodology for Strategic Metal Recovery

“…Petrakis et al [10] evaluated the particle size distribution (PSD) of crushed Ferro-nickel slag at different residence time. Then, selected products were alkali activated in order to investigate the effect of particle size on the compressive strength of the produced alkali activated materials (AAMs).…”

Synthesis of Geopolymers from Mechanically Activated Coal Fly Ash and Improvement of Their Mechanical Properties

“…Also, many mechanical activation methods may affect the size reduction of coal fly ash particles. It has been reported that the reduction of particle size improved the rate of geopolymerization reactions [21,22]. It has also been reported that the strength of the geopolymer was improved by applying the high activity of the nanoparticles [23,24].…”