Structure and pozzolanic activity of calcined coal gangue during the process of mechanical activation

Abstract

On the basis of analyzing coal gangue's chemical and mineral compositions, the structure change of coal gangue during the mechanical activation was investigated by XRD, FTIR, NMR, and the mechanical strength of the cement doped coal gangue with various specific surface area was tested. The experimental results indicate that, the lattice structure of metakaolin in coal gangue samples calcined at 700 ℃ disorganizes gradually and becomes disordered, and the lattice structure of α-quartz is distorted slightly. The pozzolanic activity of the coal gangue increases obviously with its structural disorganization.

Investigation on the activation of coal gangue by a new compound method

“…Compared with Fig. 1, we can find that the there was no trace of chlorite (Mg 5 AlSi 3 AlO 10 (OH) 8 ) and kaolinite (Al 2 Si 2 O 5 (OH) 4 ) both in activated coal gangue C and T, which had been decomposed to active SiO 2 and Al 2 O 3 [13]. The obvious differences between these are as follows: in activated coal gangue T, the crystal structures of feldspar (KAlSi 3 O 8 ) and muscovite (KAl 3 Si 3 O 10 (OH) 2 ) still existed in TMTA technology, but the peaks decreased apparently in gangue C. On the other hand, the crystallinity of quartz in gangue C was also decreased.…”

“…Mechanical activation is a physical process, taking place in mechanical activators (especially ball mill), aimed at improving the material's activity by only decreasing the particle size without the need for the application of chemical reagents. Guo et al [8] conducted a study on structure and pozzolanic activity of calcined coal gangue during the process of mechanical activation, and they found that with the decreasing grain size, the pozzolanic activity increases and is attributed to the disorganization of 6-coordinated aluminum and Q 3 silica. Thermal activation is a universal method, which has been widely studied by many researchers in China.…”

Effects of Fine Gangue on Strength, Resistivity, and Microscopic Properties of Cemented Coal Gangue Backfill for Coal Mining

“…Gangue is one of the most important components of CGB for coal mining; this is because crushed gangue exhibits a pozzolanic activity and a certain degree of strength [8][9][10]. However, considering the slurry transportation restriction and the compressive properties of the CGB, the maximum particle size of coal gangue is normally 15 mm at maximum.…”

Using Chinese Coal Gangue as an Ecological Aggregate and Its Modification: A Review

“…Equations (1)- (3) show the kaolinite calcined chemical reaction. Coal gangue has a low-temperature activation zone between 500 • C and 800 • C [39,[57][58][59][60], and it has the highest activity when the calcination temperature is 700-750 • C. As the continuous temperature increased, mullite appeared at 1000 • C, and it has no hydration and does not affect gangue activation.…”