洁净煤技术

2020, v.26;No.125(01) 194-206

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准东煤灰提取氧化铝和白炭黑技术研究
Study on the technology of extracting Al_2O_3 and SiO_2 from Zhundong coal ash

王敏;王辉;杨海瑞;刘汉辉;孙健伟;
WANG Min;WANG Hui;YANG Hairui;LIU Hanhui;SUN Jianwei;College of Energy Science and Engineering,Harbin Institute of Technology;Department of Energy and Power Engineering,Tsinghua University;

摘要(Abstract):

为实现准东煤灰的绿色化综合利用,笔者研究设计了从准东煤灰中制取氧化铝和白炭黑的工艺流程,确定了最佳工艺条件,并通过SPSS双变量分析比较不同影响因素对提取率影响程度。试验采用准东煤——将军庙原煤,破碎并用马弗炉模拟煤粉炉静态燃烧方式制取灰样。准东煤灰的成分分析和元素分析表明:SiO_2占48.84%,Al_2O_3占31.26%。参照标准制备灰样,对灰样进行SEM分析,发现粘黏性严重,因此试验前先进行机械研磨。采用煤灰与硫酸铵焙烧法制备氧化铝,工艺分为焙烧过程和酸浸过程。因滤液中含有大量杂质铁、钙等元素,采用pH调节法除杂并对除杂效果进行检验,检验结果为除杂率接近100%。从提铝渣中制备白炭黑分为碱浸过程和多次碳分过程。在提铝工艺焙烧过程中,通过提铝率变化曲线及节能角度确定了各因素的最佳试验条件为:焙烧温度600℃,焙烧时间60 min,焙烧配料比1∶6;在提铝工艺酸浸过程中,得到最佳试验条件为:酸浸温度60℃、酸浸时间20 min、H_2SO_4浓度0.2 mol/L、酸浸液固比50。从提铝渣制备白炭黑研究中,通过SEM观察到提铝渣疏松多孔,有利于进一步的提硅试验。通过XRD对提铝渣分析,得出提铝渣中含有大量硅、钙元素;用K值法(RIR法)求得提铝渣中Si含量及经提铝后的Si损失率为7.64%。得出碱浸过程最佳试验条件为:碱浸温度60℃、碱浸时间30 min、碱浸NaOH浓度3 mol/L、碱浸液固比70,此时Si提取率为99%。采用多次碳分法进行提硅能够满足不同硅含量纯度要求,得到最佳碱浸工艺条件为碳分pH=9.5、CO2通气速率24 m L/min、碳分NaOH浓度0.2 mol/L、碳分液固比80。通过双变量相关性分析,得到各因素对提铝率、SiO_2提取率及H_2SiO_3沉淀率影响程度大小分别为:焙烧温度>焙烧时间>焙烧配料比,酸浸时间>酸浸温度>H_2SO_4浓度>酸浸液固比,碱浸液固比>碱浸温度>NaOH浓度>碱浸时间,碳分pH>碳分液固比>碳分NaOH浓度>CO_2通气速率。通过经济性及可行性分析,说明提出的工艺能有效实现准东煤灰的绿色化综合利用。从提铝后的滤液中重新提取(NH_4)_2SO_4,实现生产原料的再利用;碳分过程后的Na_2CO_3溶液可通过加入石灰苛化的方式实现NaOH可循环利用于提取工艺生产;本工艺除生产氧化铝和白炭黑外,还能获得Na_2SO_4等附加产品。
In order to realize the green utilization of Zhundong coal ash,the process of preparing Al_2O_3 and SiO_2 from Zhundong coal ash was designed. The optimal process conditions was determined,and the degree of different factors on the extraction rate were carrieed out by SPSS bivariate analysis. Zhundong coal—Jiangjunmiao was used as raw coal,and ash samples was prepared using a muffle furnace to simulate the static combustion of a pulverized coal furnace after crushing.. Through the composition analysis and elemental analysis of the coal ash,it is found that SiO_2 accountes for 48.84%,and Al_2O_3 accounted for 31.26%. The coal ash sample was prepared according to the standard,and the sample was analyzed by SEM. The stickiness is serious,so mechanical grinding is performed before experiment.The Al_2O_3 was prepared from coal ash by ammonium sulfate roasting method which was divided into roasting process and acid leaching process.Because the filtrate contained a large amount of impurities such as iron and calcium,impurities were removed by using the pH adjustment method and the effect of removing impurities was checked. The impurity removal rate is almost 100%. Alkali leaching process and multiple CO_2 separation process were used to prepare SiO_2 from the aluminum slag. In the calcination process of aluminum extraction,the optimum experimental conditions of various factors were determined by the change curve. The results show that the calcination temperature is 600 ℃,the calcination time is 60 min,and the roasting ratio is 1 ∶ 6. In the acid leaching process of aluminum extraction process,the best experimental conditions are temperature 60 ℃,time 20 min,H_2SO_4 0.2 mol/L,and liquid-solid ratio 50. The slag was analyzed by SEM and XRD. It is found that aluminum extraction slag contains a large amount of silicon and calcium elements,and the Si loss after aluminum extracting is 7.64% by the RIR method.The optimum experimental conditions for the alkali leaching process are temperature 60℃,time 30 min,NaOH_3 mol/L,liquid-solid ratio 70,and the SiO_2 extraction rate is 99%. Multiple CO_2 separation method can meet the requirements of different SiO_2 content purity. The optimum alkali leaching conditions are p H = 9. 5,CO_2 aeration rate 24 m L/min,NaOH 0.2 mol/L,and liquid-solid ratio 80. Through the bivariate correlation analysis,the effects of various factors on the Al_2O_3 extraction rate,SiO_2 extraction rate and H_2SiO_3 precipitation rate are obtained which are roasting temperature > roasting time > roasting ratio,acid leaching time>acid leaching temperature>H_2SO_4 concentration>acid leaching liquid-solid ratio,alkali immersion liquid-solid ratio>alkali leaching temperature>NaOH concentration> alkali leaching time,pH> liquid-solid ratio> Na OH concentration>CO_2 aeration rate.Through the economy and feasibility analysis,the research can effectively realize the green utilization of Zhundong coal ash.( NH_4)_2SO_4 is re-extracted from the filtrate after aluminum extraction to realize the reuse of production raw materials. The Na_2CO_3 solution after the CO_2 separation process can be causticized by adding lime to realize the recycling of Na OH in the extraction process. In addition to the production of Al_2O_3 and SiO_2,additional products such as Na_2SO_4 can also be obtained.

关键词(KeyWords): 准东煤灰;氧化铝;白炭黑;双变量相关性;可行性分析
Zhundong coal ash;Al2O3;SiO2;bivariate correlation;feasibility analysis

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基金项目(Foundation): 国家重点研发计划资助项目(2016YFB0600203)

作者(Author): 王敏;王辉;杨海瑞;刘汉辉;孙健伟;
WANG Min;WANG Hui;YANG Hairui;LIU Hanhui;SUN Jianwei;College of Energy Science and Engineering,Harbin Institute of Technology;Department of Energy and Power Engineering,Tsinghua University;

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