基于矿化反应过程三阶段划分的粉煤灰高效矿化方法研究

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中文摘要：粉煤灰由于含有钙镁等碱土金属氧化物导致其浆液呈碱性,直接充填井下采空区易污染地下水源.利用陕北矿区府谷电厂粉煤灰开展组分测试、浆液pH值特性测试及固碳降碱试验,基于浆液pH值与OH-浓度理论关系对粉煤灰固碳降碱反应过程进行阶段划分并提出两级耦合的粉煤灰高效矿化方法.研究结果表明:①粉煤灰含CaO、MgO、K2O等碱土金属氧化物,溶于水浆液呈高碱特性,浆液pH值随浆液浓度增大而增大,当粉煤灰浆液质量分数≥30%时,浆液pH值不受质量分数影响且粉煤灰碱土金属氧化物与水反应生成OH-速率较快,溶于水 20 min,OH-浓度饱和;②粉煤灰与CO2 发生矿化反应生成方解石型CaCO3,每 1kg粉煤灰可矿化封存 29.57 g CO2;③粉煤灰与CO2 发生矿化粉煤灰固碳降碱过程中pH变化曲线呈"倒S"型,按降pH速率分为慢速(Ⅰ)、快速(Ⅱ)、慢速(Ⅲ)3个阶段,3个阶段的pH值分界点分别为 11.39、7～8且第I阶段无法消除;④降pH与降碱不是同一概念,降碱指的是降浆液中OH-浓度,降pH第I阶段对应快速降碱阶段,降pH第Ⅱ、Ⅲ阶段对应深度降碱阶段;⑤决定粉煤灰固碳量的主要为降pH第Ⅰ阶段,而非pH下降速率较大的第Ⅱ阶段,第I阶段CO2 利用率约为 30.78%,第Ⅱ、Ⅲ阶段CO2 总利用率约为 9.04%;⑥基于粉煤灰固碳降碱过程阶段划分及反应装置降碱速率、容积的差异性,提出两级耦合的粉煤灰高效矿化方法.研究结果对分析粉煤灰固碳降碱机理,提高粉煤灰固碳降碱效率,促进粉煤灰处置工业化应用具有重要意义.

外文标题：Study on efficient mineralization method of fly ash based on three-stage division in reaction process

外文摘要：Due to alkaline earth metal oxide such as calcium and magnesium being existed in the fly ash,its slurry is alkaline.It's easy to pollute the underground water when the slurry was filled in the goaf.Thus,some experiments such as composition test,slurry pH charac-teristic test,carbon and alkali reduction test were carried out by using fly ash selected from Fugu Power Plant in northern Shaanxi Mining area.Based on the theoretical relationship between slurry pH value and OH-concentration,the reaction process of carbon and alkali reduc-tion of fly ash was divided into stages and a two-stage coupling method for high efficiency mineralization was proposed.The results showed that the slurry of fly ash had high alkali for the reason that the alkali metal oxides such as CaO,MgO,K2O,etc being existed and the pH value increased with the slurry concentration.While the pH value was not affected by the concentration when the slurry concentration was more than 30%.At the same time,the OH-concentration was saturated after fly ash being dissolved in water for 20 minutes due to the fast reaction of alkali earth metal oxides with water.And the reaction product is calcium carbonate of calcite type as well as 20 grams of carbon dioxide being mineralized per kilogram of fly ash.In the process of carbon fixation and alkali reduction,pH reduction curve reflec-ted as reverse S type and the pH reduction rate was divided into three stages,referring to slow,fast and slow.The changing points of three stages were that pH values being 11.39 and 7-8 as while as the first stage cannot be eliminated.Simultaneously,the pH value and alkali re-duction were not the same concept for alkali reduction referring to the decrease of OH-concentration in the slurry.So the first stage corres-ponded to the rapid alkali reduction and the second and third stage corresponded to the deep alkali reduction.The carbon fixation amount was mainly determined by the first stage,not the second stage of rapid pH value decrease for the reason thar the CO2 utilization rate of the first stage was about 30.78%,while the total CO2 utilization rate of the second and third stages was about 9.04%.Based on the stage divi-sion of reaction as while as the difference of alkali reduction rate and reaction device volume,a two-stage coupling method of high effi-ciency mineralization was proposed.The research results have great significance for analyzing the mechanism of carbon fixation and al-kali reduction of fly ash,improving the efficiency and promoting the industrial application of fly ash disposal.

外文关键词：

high-alkali fly ashcarbon fixation and alkali reductionstage divisionhigh efficiency mineralizationtwo-stage couplingmineralization reaction

作者：

于秋鸽、尹希文、樊振丽、甘志超、浮耀坤

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作者单位：

中煤科工开采研究院有限公司,北京 100013

天地科技股份有限公司开采设计事业部,北京 100013

关键词：

高碱粉煤灰固碳降碱阶段划分高效矿化两级耦合矿化反应

基金：

国家重点研发计划资助项目陕西省厅市联动重点资助项目天地科技开采设计事业部科技创新基金资助项目

项目编号：

2022YFB41021002022GD-TSLD-40KJ-2021-KCQN-03

出版年：

2024

DOI：

10.12438/cst.2024-0151

煤炭科学技术

煤炭科学研究总院

煤炭科学技术

CSTPCD北大核心

影响因子：2.095

ISSN：0253-2336

年,卷(期)：2024.52(6)