Engineering Research Centre for CO2 Emission Reduction and Resource Utilisation,Ministry of Education,Institute of Resources and EnvironmentalEngineering,Shanxi University
Huairou Laboratory Shanxi Research Institute

将电石渣循环利用于建筑材料、环境治理和化工产品等领域,可实现工业废渣利用和二氧化碳减排。在双碳背景下,对电石渣固碳量及其循环利用途径的碳减排潜力分析尤为重要。详细统计了代表产区电石渣粒径分布和化学组成,依据各电石渣中氧化钙含量计算理论固碳量,系统分析电石渣各类循环利用途径的碳减排效果及其在生命周期评价中具体实施步骤,介绍了生命周期评价在电石渣领域的应用案例。计算发现电石渣理论固碳量与氧化钙质量分数呈正相关。新疆和河北地区电石渣中氧化钙质量分数均约90%,山东地区电石渣氧化钙质量分数低,约61%,来自山东和新疆等6个产地电石渣的理论固碳量在0.48~0.72t/t(以电石渣计)。电石渣循环利用领域,电石渣不论是替代石灰石原料生产水泥、砌砖、氯化钙和碳酸钙等建筑和化工产品,或针对其呈碱性特点用于烟气脱硫和工业废水处理,依各自产业规模差异均能不同程度减少二氧化碳排放,达到碳减排目的。其中,电石渣在建筑材料领域应用成熟,生产规模大,故碳减排总量大,代表企业平均每年减少万吨级二氧化碳排放。用生命周期评价计算电石渣循环利用碳排放量4个案例分析显示,电石渣制取1t水泥熟料排放CO2669kg;电石渣在NH4Cl与(NH4)2SO4浸取体系中制1t轻质碳酸钙的CO2排放量相当,分别为308.21和300.7kg,电石渣制1t胶结制品碳排放量最低,约151.11kg。推测由于电石渣生产水泥干燥预处理需消耗大量能源,导致其CO2排放量高;用电石渣制备碳酸钙与胶结制品相比,前者需投加NH4Cl或(NH4)2SO4等化学试剂,增加原辅材料带来的间接排放使前者碳排放量更大。电石渣-胶结制品CO2净排放量为-301.47kg/t(以胶结制品计),电石渣在NH4Cl和(NH4)2SO4浸取体系中制1t轻质碳酸钙的CO2净排放量分别为-157.5和-139.3kg。可见电石渣循环利用于胶结制品领域的碳减排效果最好。可从电石渣的干燥处理工序和原辅材料添加工序等优化入手,研究电石渣-水泥/碳酸钙领域碳减排,制定有针对性的碳减排方案。

Recycling of calcium carbide slag in areas such as building materials, environmental treatment and chemical products canrealize the utilization of industrial waste slag and carbon dioxide emission reduction. Under the dual-carbon background, it is particularlyimportant to analyse the carbon reduction potential of calcium carbide slag in terms of carbon sequestration and its recycling pathway. Theparticle size distribution and chemical composition of calcium carbide slag in the representative production areas were counted in detail,the theoretical carbon sequestration was calculated based on the calcium oxide content in each slag, the carbon emission reduction effect ofvarious recycling pathways of calcium carbide slag was analysed systematically as well as the specific implementation steps in the life-cycleassessment (LCA), and the application cases of LCA in the field of calcium carbide slag were introduced. The calculation results showthat the theoretical carbon sequestration of calcium oxide is positively correlated with the content of calcium oxide of calcium carbide slag.The calcium oxide mass fraction of calcium oxide in calcium carbide slag from Xinjiang and Hebei are both about 90%, and the calciumoxide mass fraction of calcium carbide slag from Shandong is lower, about 61%, and the theoretical carbon sequestration of calcium carbide slag from six origins, including Shandong and Xinjiang, floats in the range of 0.48 to 0.72 t/ t(electrochemical slag). In the fieldof calcium carbide slag recycling, calcium carbide slag, whether it is a substitute for limestone raw materials for the production of cement,bricklaying, calcium chloride and calcium carbonate and other construction and chemical products, or its alkaline characteristics forflue gas desulphurisation and industrial wastewater treatment, according to the respective differences in the scale of the industry can be different degrees of reduction of carbon dioxide emissions, to achieve the purpose of carbon emission reduction. Among them, calcium carbide slag in the field of building materials application is mature, the production scale is large, so the total amount of carbon emissions reduction is larger, on behalf of the enterprise can reduce carbon dioxide emissions by 10 000 t per year on average. Four case analysesusing life cycle assessment to calculate carbon emissions from recycling of calcium carbide slag show that 1 t of cement clinker madefrom calcium carbide slag emits 669 kg of CO2. The CO2 emissions of 1 t of light calcium carbonate made from calcium carbide slag inNH4Cl and ( NH4) 2SO4 leaching systems are comparable, 308.21 and 300.7 kg, respectively, and the CO2 emissions of 1 t of cementedproducts made from calcium carbide slag are the lowest, about 151. 7 kg, and the CO2 emissions of 1 t of cemented products madefrom calcium carbide slag are the lowest, about 151.7 kg. The lowest carbon emission is about 151.11 kg. It is assumed that the dryingpre-treatment process of cement produced by calcium carbide slag consumes a lot of energy, which leads to the high CO2 emission. Compared with cemented products, calcium carbonate prepared by calcium carbide slag needs to be added with chemical reagents, such asNH4Cl or (NH4) 2SO4, and the indirect emission brought by the increase in the raw and auxiliary materials makes the former′s carbon emission greater. The net CO2 emission of calcium carbide slag - cemented products is -301.47 kg/ t (cemented products), and the netCO2 emission of calcium carbide slag in NH4Cl and (NH4) 2SO4 leaching system to make 1 t light calcium carbonate is -157.5 and -139.3 kg, respectively. It can be seen that calcium carbideslag recycling in the field of cemented products is the best carbon emission reduction. It is suggested that the carbon emission reduction of calcium carbide slag can be studied from this aspect. If the study of carbon emission reduction in the field of calcium carbonate slag cement/ calcium carbonate is carried out, it can start from the optimisation of the drying and treatment process of calcium carbonate slag and the addition of raw and auxiliary materials to formulate targeted carbon emissionreduction plans.

国家重点研发计划资助项目(2022YFB4102102);山西省重点研发计划资助项目(202102090301010);黄河实验室资助项目(YRL-202108);山西大学交叉学科建设资助项目

廖雪妍,成怀刚,钱阿妞,等.电石渣循环利用碳减排潜力及其生命周期评价研究进展[J].洁净煤技术,2024,30(4):157-170.

LIAO Xueyan,CHENG Huaigang,QIAN Aniu,et al.Carbon emission reduction potential and life cycle assessment of calcium carbon slag utilisation[J].Clean Coal Technology,2024,30(4):157-170.