Eluviation and Leaching of Elements from Broken Fly-Ash-Based Porous Geopolymer
Abstract
:1. Introduction
2. Engineering Background
2.1. Overview of Coal Face
2.2. Overview of Face End Backfilling
2.3. Environment of Backfilling Body Eluviation
3. Materials and Methods
3.1. Materials
3.2. Fly-Ash-Based Porous Geopolymer Preparation
3.3. Testing Apparatus
3.4. Experimental Content and Procedures
- (1)
- Simplification of eluviation process
- (2)
- Simplification of leaching process
- (3)
- Simplification of mine water
3.4.1. Dynamic Eluviation Test
3.4.2. Static Leaching Test
3.4.3. Leaching Orthogonal Experiment
4. Results and Discussion
4.1. Analysis of Dynamic Eluviation Test Results
4.2. Analysis of Static Leaching Test Results
4.3. Analysis of Orthogonal Experimental Results
5. Conclusions
- (1)
- The amount of Cu and Zn in the leachate was low, and the concentration of Cu and Zn in the leachate decreased and then increased slightly with the increase in eluviation time, but their concentration increased and than decreased with the increase in grain size.
- (2)
- The concentration of Pb in the leachate was greater, and it decreased gradually with the increase in leaching time. However, it gradually decreased with the increase in grain size.
- (3)
- Under acidic environments, the leaching of Cu and Zn became easier, especially Cu, which increased by several orders of magnitude in strongly acidic environments compared to weakly acidic environments. Under neutral and alkaline environments, the amount of Cu and Zn in the lixivium was lower. However, the amount of Zn in the leachate increased slightly in the strongly alkaline environment (pH > 10) compared to the weakly alkaline environment.
- (4)
- The leaching of Pb was basically not affected by pH and did not show an obvious geometric increase or decrease in either a strongly acidic or a strongly alkaline environment, but its leaching amount was slightly larger under weakly acidic (weakly alkaline) conditions, which could reach 0.02 mg/L.
- (5)
- The reduction in solid–liquid ratio promoted the leaching of heavy metals from fly-ash-based geopolymer.
- (6)
- The order of the factors affecting the leaching of heavy metals from fly-ash-based geopolymer was grain size > pH > solid–liquid ratio.
Author Contributions
Funding
Institutional Review Board Statement
Informed Consent Statement
Data Availability Statement
Acknowledgments
Conflicts of Interest
References
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Component | SiO2 | Al2O3 | Fe2O3 | CaO | K2O | Na2O | MgO | TiO | Others |
---|---|---|---|---|---|---|---|---|---|
Ratio | 58.3% | 24.6% | 5.4% | 4.6% | 2.0% | 2.0% | 1.5% | 1.1% | 0.5% |
Groups | Grain Size (Mesh) | Eluviation Time (h) |
---|---|---|
1 | 20–35/35–60/>60 | 3 |
2 | 20–35 | 1/3/7 |
Groups | Solid-to-Liquid Ratio | Grain Size (Mesh) | Lixivium pH | Leaching Time (Days) |
---|---|---|---|---|
1 | 1:10 | 20–35/35–60/>60 | 7 | 3 |
2 | 1:10 | 20–35 | 2/4/7/10/12 | 3 |
3 | 1:10/1:20/1:30 | 20–35 | 7 | 3 |
4 | 1:10 | 20–35 | 7 | 2/4/6 |
Groups | pH | Grain Size (Mesh) | Solid-to-Liquid Ratio |
---|---|---|---|
1 | 7.00 | 35–60 | 1:30 |
2 | 7.00 | >60 | 1:20 |
3 | 4.00 | >60 | 1:30 |
4 | 10.00 | >60 | 1:10 |
5 | 4.00 | 35–60 | 1:10 |
6 | 7.00 | 20–35 | 1:10 |
7 | 10.00 | 35–60 | 1:20 |
8 | 10.00 | 20–35 | 1:30 |
9 | 4.00 | 20–35 | 1:20 |
Name of Heavy Metal | Analysis Parameters | Influencing Factors | ||
---|---|---|---|---|
pH (A) | Solid-to-Liquid Ratio (B) | Mesh Number (C) | ||
Pb | K1 | 0.0336 | 0.0267 | 0.0117 |
K2 | 0.0255 | 0.0318 | 0.0285 | |
K3 | 0.0222 | 0.0228 | 0.0411 | |
0.0112 | 0.0089 | 0.0039 | ||
0.0085 | 0.0106 | 0.0095 | ||
0.0074 | 0.0076 | 0.0137 | ||
Optimum level | A1 | B2 | C3 | |
Rj | 0.0038 | 0.003 | 0.0098 | |
Primary and secondary order | C > A > B | |||
Cu | K1 | 0.0498 | 0.0165 | 0.0048 |
K2 | 0.0090 | 0.0081 | 0.0108 | |
K3 | 0.0096 | 0.0435 | 0.0528 | |
0.0166 | 0.0055 | 0.0016 | ||
0.0030 | 0.0027 | 0.0036 | ||
0.0032 | 0.0145 | 0.0176 | ||
Optimum level | A1 | B3 | C3 | |
Rj | 0.0133 | 0.0118 | 0.0160 | |
Primary and secondary order | C > A > B | |||
Zn | K1 | 0.0075 | 0.0114 | 0.0090 |
K2 | 0.0078 | 0.0084 | 0.0069 | |
K3 | 0.0123 | 0.0081 | 0.0120 | |
0.0025 | 0.0038 | 0.0030 | ||
0.0026 | 0.0028 | 0.0023 | ||
0.0041 | 0.0027 | 0.0040 | ||
Optimum level | A3 | B1 | C3 | |
Rj | 0.0016 | 0.0011 | 0.0017 | |
Primary and secondary order | C > A > B |
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Shi, P.; Zhang, Y.; Sun, Q.; Ta, X. Eluviation and Leaching of Elements from Broken Fly-Ash-Based Porous Geopolymer. Materials 2021, 14, 6884. https://doi.org/10.3390/ma14226884
Shi P, Zhang Y, Sun Q, Ta X. Eluviation and Leaching of Elements from Broken Fly-Ash-Based Porous Geopolymer. Materials. 2021; 14(22):6884. https://doi.org/10.3390/ma14226884
Chicago/Turabian StyleShi, Peng, Yuan Zhang, Qingfu Sun, and Xupeng Ta. 2021. "Eluviation and Leaching of Elements from Broken Fly-Ash-Based Porous Geopolymer" Materials 14, no. 22: 6884. https://doi.org/10.3390/ma14226884