Page 224 - AJWEP-22-5

Liu, et al.

18 experimental trials to prepare slurries. The density, (fly ash-to-coal gangue mass ratio) were all below 0.01
viscosity, and water bleeding rate of the slurries were (Table 4), indicating extremely significant differences.
measured, and the results are summarized in Table 3. This finding demonstrates that all three factors had
Statistical analysis of the orthogonal experimental data statistically significant effects on slurry density.
was performed using SPSS software. However, factor C exhibited a relatively higher p-value,
The p-value reflects the degree of influence of each indicating a less pronounced impact on slurry density
factor on the response variables: p<0.01 indicates an compared to factors A and B, which demonstrated
extremely significant difference, a p-value between 0.01 equivalent levels of significance. The order of influence
and 0.05 denotes a significant difference, and p>0.05 of the three factors on slurry density is as follows:
suggests no significant difference. 9-11 Fly ash-to-coal gangue mass ratio > solid volume
The analysis conducted in this study included concentration > coal gangue particle size. 13
significance testing and marginal means analysis. The marginal means of each factor were utilized
Significance testing was used to evaluate the isolated to examine their individual effects on slurry density.
effect of individual factors on the parameters by The variations in marginal means for each factor are
calculating marginal means. Marginal means represent illustrated in Figure 4. Solid volume concentration
the average values of dependent variables after plays a critical role in increasing slurry density (Figure
eliminating the influence of other factors, thereby 4A). As the volume concentration increased, the slurry
14
isolating the contribution of a single factor. In became more compact, resulting in higher density.
12
conventional analyses, changes in dependent variables A near-linear inverse relationship was observed between
typically result from the combined influence of multiple coal gangue particle size and slurry density (Figure 4B).
factors. The density decreased from approximately 1.37 g/cm
3
The p-values for factors A (solid volume 3
concentration), B (coal gangue particle size), and C to 1.25 g/cm as particle size decreased, due to finer
particles generating larger interstitial volumes within
the slurry. These voids are filled with water, thereby
Table 3. Orthogonal experimental results reducing the volumetric proportion of coal gangue and,
Sample A a B b C c Slurry Viscosity Water consequently, lowering the overall density. 15-18
density (mPa·s) bleeding The fly ash-to-coal gangue mass ratio exhibited
(g/cm ) rate (%) a quasi-linear positive correlation with density
3
1 1 1 1 1.21 4.25 0.34 (Figure 4C). Higher proportions of coal gangue
2 1 1 2 1.34 5.10 0.40 increased slurry density due to the inherently greater
3 1 2 3 1.45 5.30 0.38 density of coal gangue powder compared to fly ash. At
4 1 2 4 1.17 6.10 0.37 a constant slurry volume, a higher coal gangue content
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5 1 3 5 1.12 4.20 0.34 proportionally elevated the overall density. Higher solid
6 1 3 1 1.22 5.10 0.32 concentrations (60–70%) reduce water consumption by
20–30% compared to 50% slurries, thereby lowering
7 2 1 2 1.60 12.50 0.26 pumping costs and minimizing the risk of groundwater
8 2 1 3 1.52 9.50 0.32 contamination from bleed water. Retained injectability
9 2 2 4 1.34 5.60 0.38
10 2 2 5 1.17 5.10 0.34 Table 4. Significance analysis of influencing
11 2 3 1 1.25 5.70 0.35 factors on slurry density
12 2 3 2 1.29 5.30 0.31 Factor Sum of DOF Average F‑value p‑value
13 3 1 3 1.35 10.40 0.32 squared variance
14 3 1 4 1.30 11.50 0.31 deviations
15 3 2 5 1.40 9.10 0.26 A 0.051 3 0.030 32.481 0.000
16 3 2 1 1.50 10.20 0.24 B 0.042 2 0.025 24.972 0.001
17 3 3 2 1.38 7.40 0.31 C 0.043 6 0.010 12.339 0.002
18 3 3 3 1.37 8.10 0.32 Deviation 0.016 7 0.002
Notes: Solid volume concentration in the slurry; coal gangue Sum 30.036 18
b
a
particle size; and fly ash-to-coal gangue in the mixed slurry. Abbreviation: DOF: Degrees of freedom.
c
Volume 22 Issue 5 (2025) 218 doi: 10.36922/AJWEP025210162