云南某低品位黏土型锂矿石含锂0.147%,为探究低能耗、环保的开发利用工艺,采用新型焙烧助剂ASH开展了低温焙烧—无酸浸出的提锂工艺研究,并结合XRD、SEM-EDS等分析手段阐述了反应机理。试验结果表明,在试样与ASH质量比为1∶0.3、焙烧温...云南某低品位黏土型锂矿石含锂0.147%,为探究低能耗、环保的开发利用工艺,采用新型焙烧助剂ASH开展了低温焙烧—无酸浸出的提锂工艺研究,并结合XRD、SEM-EDS等分析手段阐述了反应机理。试验结果表明,在试样与ASH质量比为1∶0.3、焙烧温度为400℃、焙烧时间为1.0 h,去离子水浸出时间为2 h、浸出温度为70℃、液固比为5 m L/g条件下,锂浸出率为83.81%。机理分析显示,焙烧—浸出前后,样品中主要矿物相未发生变化,但衍射峰强度降低;经焙烧—浸出后,浸渣表面均匀分布着裂纹和空隙,Al、Si、Fe、Ti含量均有所降低。说明ASH与矿物发生反应,破坏了矿物的表面结构,生成了可溶性盐Li-ASH。与传统焙烧—浸出工艺相比,本研究所采用的提锂工艺焙烧温度低、浸出时无酸,降低了生产能耗、简化了工艺流程,对同类型低品位黏土型锂矿的绿色高效开发利用具有重要借鉴意义。展开更多
This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeabil...This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.展开更多
Secondary lignocellulosic biomass has proved to be useful as an energy source through its oxidation by means of combustion processes.In accordance with the above,in this paper,we wanted to study the ash from urban pru...Secondary lignocellulosic biomass has proved to be useful as an energy source through its oxidation by means of combustion processes.In accordance with the above,in this paper,we wanted to study the ash from urban pruning residues that are generated in cities in the Neotropics.Species such as Licania tomentosa,Azadirachta indica,Ficus benjamina,Terminalia catappa,Leucaena leucocephala,Prosopis juliflora and Pithecellobium dulce were selected because they have been previously studied and showed potential for thermal energy generation.These materials were calcined in an oxidizing atmosphere and characterized by X-ray diffraction and fluorescence,scanning electron microscopy with microchemistry,BET surface area,thermal gravimetric analysis,and differential scanning calorimetry.The pH and apparent density were also established.The results show high basicity materials(average pH 10),a behavior associated with the presence of chemical elements such as calcium,potassium,magnesium,chlorine,phosphorus,and sulfur.Structurally,these materials have a very significant amorphous fraction(between 49%and 74.5%),the dominant crystalline phases are calcite,arcanite,sylvite,and hydroxyapatite.These ashes have low surface area and do not exceed 13 m^(2)/g.Two characteristic morphological aspects were observed in these ashes:a morphology of rounded grains where silicon content is highlighted,and lamellar morphologies where the presence of chlorine is highlighted.Thermally,these ashes show four significant mass loss events(400℃,430℃,680℃,and 920℃),causing mass losses that vary between 25%and 40%.Through this study,it was possible to establish that,from a chemical point of view,these ashes are less dangerous in comparison with those of a mineral coal that was used as a reference.However,they require additional treatments for their disposal due to their high basicity.Because of their composition,these ashes have the potential to be used in the ceramic and cement industries,and in the manufacture of fertilizers.展开更多
This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeabil...This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.展开更多
文摘云南某低品位黏土型锂矿石含锂0.147%,为探究低能耗、环保的开发利用工艺,采用新型焙烧助剂ASH开展了低温焙烧—无酸浸出的提锂工艺研究,并结合XRD、SEM-EDS等分析手段阐述了反应机理。试验结果表明,在试样与ASH质量比为1∶0.3、焙烧温度为400℃、焙烧时间为1.0 h,去离子水浸出时间为2 h、浸出温度为70℃、液固比为5 m L/g条件下,锂浸出率为83.81%。机理分析显示,焙烧—浸出前后,样品中主要矿物相未发生变化,但衍射峰强度降低;经焙烧—浸出后,浸渣表面均匀分布着裂纹和空隙,Al、Si、Fe、Ti含量均有所降低。说明ASH与矿物发生反应,破坏了矿物的表面结构,生成了可溶性盐Li-ASH。与传统焙烧—浸出工艺相比,本研究所采用的提锂工艺焙烧温度低、浸出时无酸,降低了生产能耗、简化了工艺流程,对同类型低品位黏土型锂矿的绿色高效开发利用具有重要借鉴意义。
文摘This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.
基金Ministry of Science,Technology and Innovation of Colombia through the“Fondo Francisco Joséde Caldas”National Financing Fund for Science,Technology and Innovation for the financing provided for the development of the project (Project 120885272102,Call 852 of 2019).
文摘Secondary lignocellulosic biomass has proved to be useful as an energy source through its oxidation by means of combustion processes.In accordance with the above,in this paper,we wanted to study the ash from urban pruning residues that are generated in cities in the Neotropics.Species such as Licania tomentosa,Azadirachta indica,Ficus benjamina,Terminalia catappa,Leucaena leucocephala,Prosopis juliflora and Pithecellobium dulce were selected because they have been previously studied and showed potential for thermal energy generation.These materials were calcined in an oxidizing atmosphere and characterized by X-ray diffraction and fluorescence,scanning electron microscopy with microchemistry,BET surface area,thermal gravimetric analysis,and differential scanning calorimetry.The pH and apparent density were also established.The results show high basicity materials(average pH 10),a behavior associated with the presence of chemical elements such as calcium,potassium,magnesium,chlorine,phosphorus,and sulfur.Structurally,these materials have a very significant amorphous fraction(between 49%and 74.5%),the dominant crystalline phases are calcite,arcanite,sylvite,and hydroxyapatite.These ashes have low surface area and do not exceed 13 m^(2)/g.Two characteristic morphological aspects were observed in these ashes:a morphology of rounded grains where silicon content is highlighted,and lamellar morphologies where the presence of chlorine is highlighted.Thermally,these ashes show four significant mass loss events(400℃,430℃,680℃,and 920℃),causing mass losses that vary between 25%and 40%.Through this study,it was possible to establish that,from a chemical point of view,these ashes are less dangerous in comparison with those of a mineral coal that was used as a reference.However,they require additional treatments for their disposal due to their high basicity.Because of their composition,these ashes have the potential to be used in the ceramic and cement industries,and in the manufacture of fertilizers.
文摘This paper emphasized the use of rice husk ash (RHA) and sugarcane bagasse ash (SBA) in improving concrete properties, and also their combined effects on workability, compressive strength, flexural strength, permeability and water absorption capacity. Thus, in this study, the water-to-cement ratio was kept constant (0.45), the binder materials content for conventional mix was kept constant at (350 kg/m<sup>3</sup>) and the partial replacement of cement with RHASBA used was 5%, 10%, 15%, 20%, 25%, and 30% by weight of cement. The maximum compressive strength was noted at a 5% replacement level of cement with RHASBA. The Results showed that the optimum replacement of cement with RHASBA in concrete was 5%, which was found to increase the compressive strength by 15%, flexural strength by 3.4%, lowered permeability by 50%, lowered sorptivity by 11.34% as compared with control concrete at 90 days of curing time. The micro-structural test results further established that RHA and SBA have a high content of SiO<sub>2</sub> which enables them to be more reactive in concrete and also revealed that the presence of RHASBA depletes Ca(OH)<sub>2</sub> crystals, converting it into CaH<sub>2</sub>O<sub>4</sub>Si (C-S-H gel) leading to the strengthening of bond within the concrete matrix.
