Improving Fly Ash Brightness with Carbon and Iron Oxide Removal
Abstract
:1. Introduction
2. Materials and Methods
2.1. Pretreatment of Fly Ash
2.2. High Temperature Carbon Removal
2.3. Iron-Containing Oxides Removal by Acid Leaching
2.3.1. Process Method
2.3.2. Box–Behnken Design and Response Surface Methodology
2.4. Characterizations of Samples
2.4.1. Testing of Chemical Composition
2.4.2. Testing of Phase and Crystal
2.4.3. Testing of Powder Brightness
3. Results and Discussion
3.1. Analysis of Phase Composition of Original Fly Ash
3.2. Analysis of Chemical Composition of Original Fly Ash
3.3. Screening Analysis of the Original Fly Ash
3.4. Analysis of High Temperature Carbon Removal
3.5. Analysis of Iron-Containing Oxides by Acid Treatment
3.5.1. Box–Behnken Design and Response Surface Methodology
3.5.2. Analysis of Variance of Response Surface Regression Model
3.5.3. Optimal Process Conditions
4. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Factor | Variable Levels | ||
---|---|---|---|
−1 | 0 | 1 | |
A HCl concentration/% | 5% | 10% | 15% |
B Leaching time/h | 0.5 | 1 | 2 |
C Reaction temperature/°C | 50 | 70 | 90 |
SiO2 | Al2O3 | CO3 | CaO | Fe2O3 | TiO2 | K2O | Na2O | SO3 | MgO | P2O5 | CeO2 | SrO | ZrO2 | Cl | MnO | ZnO |
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
46.32% | 31.60% | 8.54% | 4.74% | 4.47% | 1.29% | 0.63% | 0.60% | 0.48% | 0.42% | 0.37% | 0.20% | 0.15% | 0.06% | 0.05% | 0.03% | 0.02% |
400 Mesh | 500 Mesh | 600 Mesh | 700 Mesh | |
---|---|---|---|---|
Mass Percentage/% | 15% | 7% | 50% | 28% |
Brightness/%ISO | 9.02 | 13.46 | 18.01 | 19.61 |
Run | Coded Variable Level | Brightness (%ISO) | |||
---|---|---|---|---|---|
HCl Concentration (/%) | Time (/h) | Temperature (/°C) | Predicted | Experimental | |
1 | 1 | −1 | 0 | 43.79 | 43.52 |
2 | 0 | 0 | 0 | 43.37 | 43.55 |
3 | 0 | 0 | 0 | 43.37 | 42.33 |
4 | 1 | 1 | 0 | 41.69 | 41.26 |
5 | 0 | 1 | 1 | 41.01 | 41.11 |
6 | 0 | −1 | 1 | 41.73 | 41.65 |
7 | −1 | 0 | 1 | 40.97 | 40.62 |
8 | 0 | 0 | 0 | 43.37 | 43.55 |
9 | 0 | −1 | −1 | 40.59 | 40.50 |
10 | 0 | 0 | 0 | 43.37 | 43.76 |
11 | −1 | −1 | 0 | 41.45 | 41.90 |
12 | 1 | 0 | 1 | 42.39 | 42.73 |
13 | 0 | 0 | 0 | 43.37 | 43.67 |
14 | −1 | 0 | −1 | 39.73 | 39.40 |
15 | 0 | 1 | −1 | 39.31 | 39.40 |
16 | −1 | 1 | 0 | 41.55 | 41.82 |
17 | 1 | 0 | −1 | 40.79 | 41.15 |
Variable | Statistical Analysis | ||||
---|---|---|---|---|---|
Sum of Square | Df | Mean Square | f-Value | p-Value | |
Model | 30.86 | 9 | 3.43 | 9.88 | 0.0032a |
A | 3.03 | 1 | 3.03 | 8.72 | 0.0213 |
B | 1.98 | 1 | 1.98 | 5.70 | 0.0483 |
C | 4.00 | 1 | 4.00 | 11.53 | 0.0115 |
AB | 1.19 | 1 | 1.19 | 3.42 | 0.1068 |
AC | 0.032 | 1 | 0.032 | 0.093 | 0.7689 |
BC | 0.078 | 1 | 0.078 | 0.23 | 0.6491 |
A2 | 0.92 | 1 | 0.92 | 2.66 | 0.1468 |
B2 | 2.55 | 1 | 2.55 | 7.35 | 0.0301 |
C2 | 15.66 | 1 | 15.66 | 45.11 | 0.0003 |
Cor Total | 33.29 | 16 |
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Song, H.; Fan, H.; Gao, H.-t.; Liu, J.-a.; Mou, H. Improving Fly Ash Brightness with Carbon and Iron Oxide Removal. Recycling 2020, 5, 5. https://doi.org/10.3390/recycling5010005
Song H, Fan H, Gao H-t, Liu J-a, Mou H. Improving Fly Ash Brightness with Carbon and Iron Oxide Removal. Recycling. 2020; 5(1):5. https://doi.org/10.3390/recycling5010005
Chicago/Turabian StyleSong, Helong, Huiming Fan, Hang-tian Gao, Jian-an Liu, and Hongyan Mou. 2020. "Improving Fly Ash Brightness with Carbon and Iron Oxide Removal" Recycling 5, no. 1: 5. https://doi.org/10.3390/recycling5010005