为了揭示不同钙基吸收剂对生物质热解气化制氢特性的影响机理,以玉米秸秆为原料在一个两段式热解气化装置上研究了添加不同钙基吸收剂对其制氢特性的影响,结果表明:煅烧石灰石、煅烧碳酸钙和煅烧白云石等3种吸收剂的添加均可有效吸收玉...为了揭示不同钙基吸收剂对生物质热解气化制氢特性的影响机理,以玉米秸秆为原料在一个两段式热解气化装置上研究了添加不同钙基吸收剂对其制氢特性的影响,结果表明:煅烧石灰石、煅烧碳酸钙和煅烧白云石等3种吸收剂的添加均可有效吸收玉米秸秆热解气化过程中生成的CO_2,促进水气变换(WGS)反应的平衡向右移动,从而生成更多H_2;同时,吸收剂的主要组分CaO还可催化玉米秸秆热解挥发分的裂解与气化反应以及WGS反应,从而显著提高产气中H_2的体积分数与产率。另外,煅烧白云石中的含镁组分还显示出对气化过程以及CO_2吸收具有进一步的催化作用,使得其在玉米秸秆热解气化过程中可获得更高的H_2体积分数(71.8%)和产率[224.5 m L/(g db biomass)]。展开更多
Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of indus...Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of industrial CO<sub>2</sub> emissions. On average 0.8 to 0.9 ton of CO<sub>2</sub> is emitted to produce one ton of OPC. In this paper, partial substitution of clinker (30% - 35%) by the calcined clay-limestone mixture was investigated in order to produce an eco-cement (LC3). Analyzes by XRF, XRD and ATG/ATD have characterized different components, determined the calcination temperature and selected the right clay which can act as effective Supplementary Cementitious Material (SCM). Mechanical tests on mortar carried out over a period of 90 days. The WBCSD/WRI “Greenhouse Gas Protocol” methodology then allowed the calculation of CO<sub>2</sub> emissions into the atmosphere. Three types of clay are available in the Songololo Region. The kaolinite is the principal clay mineral and its content varies from 27% to 34%. The sum of kaolinite and amorphous phase which enable clay to react with cementitious material ranges from 57% to 60%. The SiO<sub>2</sub> content ranges from 33% to 76%, the Alumina content from 12% to 20% so that the ratio Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> is on the higher side (0.17 - 0.53). The calcination window is between 750°C and 850°C and the best clay which can act as SCM identified. The clinker’s substitution reduced CO<sub>2</sub> emissions from 0.824 ton of CO<sub>2</sub> for one ton of OPC to 0.640 ton of CO<sub>2</sub> for one ton of LC3, means 22% less emissions. The compressive strengths developed by LC3 vary from 8.91 to 57.6 MPa (Day 1 to Day 90), exceed those of references 32.5 cement and are close to 42.5 cement. In view of the results, LC3 cement can be considered for industrial trials.展开更多
A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without P...A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.展开更多
The Cretaceous shallow marine Gboko limestone, Yandev, Nigeria is a component of the sedimentary fill of the 800 km NE-SW trending Benue Trough, Nigeria. The limestone is made up of thin bedded to massive limestone be...The Cretaceous shallow marine Gboko limestone, Yandev, Nigeria is a component of the sedimentary fill of the 800 km NE-SW trending Benue Trough, Nigeria. The limestone is made up of thin bedded to massive limestone beds interspersed with laminated grey shale having foraminifera as the dominant fossil. The limestone has both mud supported and grain supported texture, and micrites constitute about 75% of the limestone. Bulk chemical composition analysis of the limestone reveals average CaCO3 of 92.41% and a range of 77.50% - 99.00%. Mineralogical impurities include quartz, dolomite, pyrrhotite, fluorapatite etc. Trace elements concentration analysis was carried out using Energy Dispersive X-ray (EDXRF) spectrophotometry and showed the following trace elements: Mn (841.3 ppm), Sr (444.6 ppm), Fe (470 ppm), Zn (114.6 ppm) and Pb (116.4 ppm). Calcining the limestone in a laboratory muffle furnace at 1050°C for 90 minutes produced a compact, soft burnt porous and reactive lime that does not crumble into fines. The lime so produced neither meets the requirements of the Steel Making Shop (SMS) of the Ajaokuta Steel Plant nor could it be used in the growing sugar refining industry in Nigeria. It can however be used in the food and the food by-products industry, environmental, agricultural and petroleum industries etc. The raw stone remains a major source of raw materials for cement manufacture for the ever expanding building industry.展开更多
文摘为了揭示不同钙基吸收剂对生物质热解气化制氢特性的影响机理,以玉米秸秆为原料在一个两段式热解气化装置上研究了添加不同钙基吸收剂对其制氢特性的影响,结果表明:煅烧石灰石、煅烧碳酸钙和煅烧白云石等3种吸收剂的添加均可有效吸收玉米秸秆热解气化过程中生成的CO_2,促进水气变换(WGS)反应的平衡向右移动,从而生成更多H_2;同时,吸收剂的主要组分CaO还可催化玉米秸秆热解挥发分的裂解与气化反应以及WGS反应,从而显著提高产气中H_2的体积分数与产率。另外,煅烧白云石中的含镁组分还显示出对气化过程以及CO_2吸收具有进一步的催化作用,使得其在玉米秸秆热解气化过程中可获得更高的H_2体积分数(71.8%)和产率[224.5 m L/(g db biomass)]。
文摘Ordinary Portland Cement (OPC) is by mass the largest manufactured product on Earth, responsible for approximately 6% - 8% of global anthropogenic carbon dioxide emissions (CO<sub>2</sub>) and 35% of industrial CO<sub>2</sub> emissions. On average 0.8 to 0.9 ton of CO<sub>2</sub> is emitted to produce one ton of OPC. In this paper, partial substitution of clinker (30% - 35%) by the calcined clay-limestone mixture was investigated in order to produce an eco-cement (LC3). Analyzes by XRF, XRD and ATG/ATD have characterized different components, determined the calcination temperature and selected the right clay which can act as effective Supplementary Cementitious Material (SCM). Mechanical tests on mortar carried out over a period of 90 days. The WBCSD/WRI “Greenhouse Gas Protocol” methodology then allowed the calculation of CO<sub>2</sub> emissions into the atmosphere. Three types of clay are available in the Songololo Region. The kaolinite is the principal clay mineral and its content varies from 27% to 34%. The sum of kaolinite and amorphous phase which enable clay to react with cementitious material ranges from 57% to 60%. The SiO<sub>2</sub> content ranges from 33% to 76%, the Alumina content from 12% to 20% so that the ratio Al<sub>2</sub>O<sub>3</sub>/SiO<sub>2</sub> is on the higher side (0.17 - 0.53). The calcination window is between 750°C and 850°C and the best clay which can act as SCM identified. The clinker’s substitution reduced CO<sub>2</sub> emissions from 0.824 ton of CO<sub>2</sub> for one ton of OPC to 0.640 ton of CO<sub>2</sub> for one ton of LC3, means 22% less emissions. The compressive strengths developed by LC3 vary from 8.91 to 57.6 MPa (Day 1 to Day 90), exceed those of references 32.5 cement and are close to 42.5 cement. In view of the results, LC3 cement can be considered for industrial trials.
文摘A new type of cement was prepared with ground limestone powder, blastfumace slag, steel slag and gypsum without calcination. The fraction of ground limestone powder in the cement was as high as 40 wt%-60 wt% without Portland clinker. All of its physical properties can meet the requirements of masonry cement standards. The impact of limestone content on physical properties of the cement and determined its impact on law was investigated. The steel slag can excit the aquation activity of this cement effectively, and the influence of its quantity on the strength of the materials was studied, which shows that the optimum quantity of mixing is 10%. By way of changing the different content of the lime stone by quartzy sample, the law of the compression strength and the PH value was determined, confirming that the lime stone can promote the early aquation of the slag and improve the early strength. The main hydration product of this cement is calcium aluminate hydrate, ettringite and calcium silicate hydrate, as indicated by XRD and SEM analysis.
文摘The Cretaceous shallow marine Gboko limestone, Yandev, Nigeria is a component of the sedimentary fill of the 800 km NE-SW trending Benue Trough, Nigeria. The limestone is made up of thin bedded to massive limestone beds interspersed with laminated grey shale having foraminifera as the dominant fossil. The limestone has both mud supported and grain supported texture, and micrites constitute about 75% of the limestone. Bulk chemical composition analysis of the limestone reveals average CaCO3 of 92.41% and a range of 77.50% - 99.00%. Mineralogical impurities include quartz, dolomite, pyrrhotite, fluorapatite etc. Trace elements concentration analysis was carried out using Energy Dispersive X-ray (EDXRF) spectrophotometry and showed the following trace elements: Mn (841.3 ppm), Sr (444.6 ppm), Fe (470 ppm), Zn (114.6 ppm) and Pb (116.4 ppm). Calcining the limestone in a laboratory muffle furnace at 1050°C for 90 minutes produced a compact, soft burnt porous and reactive lime that does not crumble into fines. The lime so produced neither meets the requirements of the Steel Making Shop (SMS) of the Ajaokuta Steel Plant nor could it be used in the growing sugar refining industry in Nigeria. It can however be used in the food and the food by-products industry, environmental, agricultural and petroleum industries etc. The raw stone remains a major source of raw materials for cement manufacture for the ever expanding building industry.
