摘要
为探究磨细铁尾矿粉在无熟料体系中的固结性能,以硅铝型铁尾矿为主体材料,掺配钙、硫、硅校正材料,在磨细比表面积约为1 000
中国现存有207亿t金属尾
硅铝型铁尾矿中富含SiO2和Al2O3,但水化生成水化硅酸钙(C‑S‑H)及钙矾石(AFt)所需的Ca(OH)2和CaSO4不足.鉴于此,本文以硅铝型铁尾矿为主要组分,借助机械力活化方法来增加铁尾矿表面晶格缺陷浓度,同时选用富含Ca(OH)2、CaSO4和非晶态SiO2的工业副产品为校正材料,配制出铁尾矿粉无熟料固结材料,并研究影响该固结体强度的因素及水化机理.
铁尾矿源于密云维克铁尾矿,主要矿物成分为石英、长石及云母等矿物.钙、硫、硅3种校正材料均选用工业副产品.原材料的化学组成(质量分数,文中涉及的组成、水固比等除特别注明外均为质量分数或质量比)见
Material | SiO2 | Al2O3 | Fe2O3 | CaO | MgO | K2O | Na2O | SO3 | IL | Total |
---|---|---|---|---|---|---|---|---|---|---|
Iron tailing | 61.07 | 9.15 | 13.38 | 2.90 | 2.78 | 2.14 | 2.29 | 1.25 | — | 94.96 |
Calcium correction material | 2.18 | 1.16 | 0.72 | 66.92 | 1.43 | 0.02 | 0.24 | 0.48 | 26.23 | 99.38 |
Sulfur correction material | 2.16 | 1.14 | 0.64 | 33.69 | 0.57 | 0.66 | 0.72 | 41.42 | 18.67 | 99.67 |
Siliceous correction material | 38.84 | 8.33 | 0.37 | 36.73 | 12.48 | 0.27 | 0.18 | 0.92 | 1.37 | 99.49 |

图1 铁尾矿的XRD图谱
Fig.1 XRD pattern of iron tailing
以磨细石英砂试件为参照组,铁尾矿粉无熟料固结试件的抗压强度试验方案及结果见
Code | w(iron tailing power) /% | w(quartz sand)/% | w(correction material)/% | Specific surface area/( | Median particle size(D50)/μm | Compressive strength/MPa | |||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Calcium | Sulfur | Siliceous | 3 d | 7 d | 14 d | 28 d | |||||||
QL2000 | 0 | 80 | 20 | 0 | 0 | 978 | 9.670 | 1.06 | 1.38 | 1.87 | 2.05 | ||
QG2005 | 0 | 75 | 20 | 5 | 0 | 993 | 9.731 | 1.27 | 1.61 | 2.16 | 2.37 | ||
QS2515 | 0 | 60 | 20 | 5 | 15 | 965 | 6.734 | 8.13 | 19.06 | 25.38 | 28.74 | ||
FL2000 | 80 | 0 | 20 | 0 | 0 | 984 | 9.669 | 3.48 | 4.68 | 5.97 | 6.85 | ||
FG2005 | 75 | 0 | 20 | 5 | 0 | 1 016 | 8.584 | 11.46 | 15.27 | 16.43 | 16.75 | ||
FS2515 | 60 | 0 | 20 | 5 | 15 | 985 | 10.026 | 26.97 | 37.55 | 46.52 | 52.08 |
由文献[
使用FEI Quanta 250扫描电镜(SEM)观察试样的微观结构.使用TTRⅢ X‑射线衍射仪(XRD)测试试样的水化产物,仪器参数为:管电流120 mA、管电压40 kV、扫描角度5°~65°,扫描速率6 (°)/min.使用Discovery差示扫描同步热分析仪(DSC‑TG),N2作为保护气体,将磨细的净浆粉末以10 ℃/min的速率从室温加热至1 100 ℃,得到DSC‑TG曲线.
将破型后的净浆试件立即用无水乙醇终止水化,按试验需求制成SEM测试用块状试样,以及XRD、DSC‑TG测试用75 μm(200目)粉体试样.需要说明的是,由于试件FL2000的3 d抗压强度偏低,浆体结构疏松,导致其在SEM测试时抽真空时间过长,因此本文所有微观早龄期试样均选用养护龄期为7 d的 FL2000试件,其他试验的早龄期测试选用养护龄期为3 d的试件.
由

图2 铁尾矿粉无熟料固结材料硬化浆体的微观形貌
Fig.2 Micro morphology of hardened paste of iron tailing powder non‑clinker consolidation materials

图3 铁尾矿粉无熟料固结材料水化前后的XRD图谱
Fig.3 XRD patterns of iron tailing powder non‑clinker consolidation materials before and after hydration
由

图4 铁尾矿粉无熟料固结材料硬化浆体中的AFt含量
Fig.4 Ettringite content in hardened paste of iron tailing powder non‑clinker consolidation materials

图5 铁尾矿粉无熟料固结材料硬化浆体的DSC曲线和TG曲线
Fig.5 DSC curves and TG curves of hardened pastes of iron tailing powder non‑clinker consolidation materials
通过
Code | Age/d | Initial temperature/℃ | Final temperature/℃ | Mass loss ratio/% | w(AFt)/% | HAFt/% | w(C‑S‑H)/% |
---|---|---|---|---|---|---|---|
FL2000 | 7 | 105.7 | 150.0 | 0.84 | 0 | 0 | 6.26 |
28 | 104.9 | 151.5 | 1.26 | 0 | 0 | 9.37 | |
FG2005 | 3 | 60.0 | 149.9 | 4.59 | 6.21 | 2.85 | 12.97 |
28 | 60.9 | 149.3 | 5.57 | 7.79 | 3.58 | 14.87 | |
FS2515 | 3 | 59.4 | 161.5 | 4.68 | 4.56 | 2.09 | 19.23 |
28 | 59.8 | 160.8 | 5.31 | 3.82 | 1.75 | 26.45 |
石英和长石均属于架状硅酸盐结构,在细磨化过程中比层状结构的矿物更容易形成表面断
普通硅酸盐水泥净浆中的C‑S‑H含量在35%~45%之
(1)全部采用工业废料,通过合理有效的钙、硫、硅校正配料,并采用机械力粉磨,使粉体材料的比表面积达到1 000
(2)铁尾矿粉表面晶格畸变提供了能够有效参与水化反应的非晶态SiO2和Al2O3,生成的主要水化产物为C‑S‑H和AFt. 在水化过程中,仅铁尾矿粉表面非晶质层提供的有效非晶态SiO2、Al2O3才能与外掺的钙、硫校正材料发生水化反应,水化速率快,矿物中的晶态成分不参与水化.
(3)采用化学分析方法测定硬化浆体中的AFt含量,结合DSC曲线和TG曲线,近似计算出C‑S‑H的含量. 通过掺入15%的硅质校正材料,显著提高了硬化浆体中C‑S‑H的含量,将硬化浆体中的晶胶比调控为1/7~1/5,可有效确保固结体强度的持续稳定发展.
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