Enhancement of leaching of Ca from steelmaking slag by ultrasonic for CO2 mineral sequestration
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摘要: 炼钢渣是一种含有大量硅酸钙的碱性废物，可用于钢铁企业捕获CO2并合成高附加值的CaCO3。在此研究了在乙酸溶液中超声对炼钢渣中Ca的浸出率和选择性提取率的影响。试验结果表明，超声功率、液固比和乙酸溶液的初始浓度与Ca的浸出率呈正相关，但炼钢渣的粒度和温度与Ca的浸出率呈负相关。温度和乙酸溶液的初始浓度与Ca的选择性提取率呈负相关。此外，超声功率和固液比对Ca的选择性提取率影响不大，但增加超声功率和固液比会增加非钙杂质元素的浸出率。在0.5 mol/L乙酸水溶液中提取0.96 μm以下炼钢渣中的钙，反应40 min后Ca的选择性提取率高达96.7%。在浸出过程中，超声可以有效打破和去除炼钢渣颗粒表面残留的二氧化硅形成的多孔钝化层，提高Ca的浸出率。Abstract: Steelmaking slags containing large amounts of Ca silicate is a potentially alkaline waste that can be used to capture CO2 to synthesize high-quality CaCO3. Here, effect of ultrasonic on leaching efficiency and selective leaching rate of Ca in steelmaking slags was studied in acetic acid solution. Experimental results shown that ultrasound could help to strengthen leaching of Ca in acetic acid solution. Ultrasonic power, liquid-solid ratio, and initial acetic acid solution concentration were positively correlated with Ca extraction, but particle size of steelmaking slags and temperature were negatively correlated with Ca extraction. Meanwhile, temperature and initial concentration of acetic acid solation had a negative correlation to selective extraction yield of Ca, which were beneficial for the diffusion of impurity elements. Also, ultrasonic power and solid to liquid ratio were insignificant effect to selective extraction yield of Ca, but increase of ultrasonic power and solid to liquid ratio were also helpful to the diffusion of impurity elements. It was worth noting that decreasing grain size of steelmaking slags would raise selective leaching efficiency of Ca and the maximum selective leaching rate upped to 96.7%. During leaching process, ultrasonic could effectively break and remove the porous passivation layer formed by residual silica on surface of steelmaking slags particles, and improved leaching rate of Ca.
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Key words:
- steelmaking slags /
- CO2 mineral carbonation /
- ultrasonic /
- Ca /
- leaching rate /
- selective leaching rate
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图 2 不同因素对钢渣中钙浸出的影响
Figure 2. Effect of different factors on calcium leaching in steel slag
图 3 不同因素对钢渣中钙浸出的影响
Figure 3. Effect of different factors on calcium leaching in steel slag
图 4 不同因素对钢渣乙酸水溶液中钙、铁、镁选择性浸出率的影响
(a)超声波功率；(b)钢渣粒度；(c)固液比；(d)反应温度；(e)乙酸水溶液初始浓度
Figure 4. Effect of different factors on selective leaching rate of calcium, iron and magnesium in acetic acid aqueous solution of steel slag
图 5 不同条件浸出渣的SEM形貌
初始乙酸浓度=0.5 mol/L,温度=40 ℃, 时间=40 min（a）原料（粒度=180 ~ 380 μm）；（b）机械搅拌（粒度=180 ~ 380 μm）；（c）超声（超声功率=100 W, 粒度=180 ~ 380 μm）；（d）超声（超声功率=200 W, 粒度=180 ~ 380 μm）；（e）超声（超声功率=200 W, 粒度=0 ~ 96 μm）；（f）超声（超声功率=200 W, 粒度=96 ~ 180 μm）
Figure 5. SEM morphology of leaching residue under different conditions
表 1 炼钢渣的XRF分析化学成分a
Table 1. Chemical composition of the steelmaking slags by XRF-analysisa
编号 粒度/μm w/% O Ca Fe Si Mg Mn Ti C P V 试样1 180 ~ 380 39.18 28.89 14.33 3.87 3.32 3.18 2.07 1.94 1.12 1.01 试样2 96 ~ 180 37.20 28.76 15.57 3.98 3.78 3.72 1.91 1.70 1.29 1.03 试样3 0 ~ 96 37.57 28.64 15.45 3.93 3.74 3.67 1.92 1.71 1.28 1.00 a只显示含量高于1%的元素。 
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