Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement,fly ash(FA),and kaolin to produce geopolymers,to make full use of CMTs,the properties of geopolymers manufactured under diffe...Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement,fly ash(FA),and kaolin to produce geopolymers,to make full use of CMTs,the properties of geopolymers manufactured under different material mass ratios and curing methods(standard curing,water bath curing,and 60℃curing)are evaluated with significantly increased dosage of CMTs.Porosity and unconfined compressive strength tests,X-ray diffraction,field emission scanning electron microscopy,and energy dispersive spectroscopy are used to determine the physical and mechanical properties,microstructure,and mineral composition of geopolymers.Finally,costs and CO 2 emissions of specimens with different material mass ratios during the preparation processes are compared.The results show that during the geopolymerization of low-calcium materials,various geopolymer gels,including calcium silicate,calcium silicoaluminate,and mainly sodium silicoaluminate gels,coexist.The solid waste,cost,and carbon dioxide emission reductions can reach 100%,166.3 yuan/t,and 73.3 kg/t,respectively.Under a curing condition of 60℃,the sample with a CMTs mass fraction of 70%and an FA mass fraction of 30%meets the requirements of porosity,compressive strength.The resource utilization of CMT and FA is realized in a more economical way.展开更多
Three different preparation methods including steam physical activation, catalytic carbonation and KOH chemical activation methods were used to prepare municipal solid waste- based carbon materials. The methylene blue...Three different preparation methods including steam physical activation, catalytic carbonation and KOH chemical activation methods were used to prepare municipal solid waste- based carbon materials. The methylene blue （MB） adsorption value was applied to evaluate the adsorption capabilities of the prepared carbon materials. The effects of preparation methods on adsorption capability and yield of products were investigated. The yield of carbon materials with the catalytic carbonation method is the highest, and the KOH activation method is the second level. Considering the adsorption performance, the KOH activation method is much more favorable. Among the different components of municipal solid waste-based carbon materials, the adsorption properties of the single component of paperboard, the double components of tire and paperboard, the triple components of tire, paperboard and polyvinyl chloride （PVC）, and the multi-component mixtures are better than those of other single-, double-, triple- and multi-component mixtures, respectively.展开更多
Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally store...Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally stored on surface areas. The volume and chemical characteristics of these materials generate serious problem for required storage spaces and mainly environmental degradation. Paste backfill(PBF) is one of ingenious solutions to minimize the quantity of tailings to store. PBF is basically defined as a combination of mine processing tailings, binder, and water mixing. The purpose of this paper is to present backfilling components characterization and formula verification for a waste valorization solution through paste backfilling technology in Imiter operation. Obtained results and realized analysis demonstrate PBF conformity and adequacy with assigned underground functions. However the studied recipe can be more ameliorated to obtain an optimal mixture ensuring the required mechanical strength.展开更多
The design and building of new alternative fuel plants is an increasing necessity to replace old technology and non-renewable fossil fuels. To optimize the performance of these plants and to obtain an economically fea...The design and building of new alternative fuel plants is an increasing necessity to replace old technology and non-renewable fossil fuels. To optimize the performance of these plants and to obtain an economically feasible production of these types of fuels, it is necessary to have a total control of each variable involved in the process of production and how these factors affect the yield of fuel production. In this paper it is proposed a model of a digester to generate gas using a Vensim software designed to generate simulations in dynamic state. This simulation was developed using differential equations to model the behavior at each stage of the process and auxiliary conditions to complement the mathematical description of the model. The main factors in the biogas production are the retention time and the methanogen mortality ratio. For retention time lower than 10 h the process loses effectiveness due to bacterial growth is not completed efficiently, but a high retention time involves a bigger reactor and the yield of production decreases considerably for retention time higher than 40 h. The best yields were obtained for a mortality ratio in methanogen and acidogenic bacteria lower than 0.2 and a retention time of 30 h with a final production of 3.33 L by each kilogram of biomass.展开更多
To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas(GHG)emissions is required for Tianjin's waste management system. Firstly, six objective functions, name...To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas(GHG)emissions is required for Tianjin's waste management system. Firstly, six objective functions, namely, cost minimization, GHG minimization, eco-efficiency minimization, cost maximization, GHG maximization and eco-efficiency maximization, are built and subjected to the same constraints with each objective function corresponding to one scenario. Secondly, GHG emissions and costs are derived from the waste flow of each scenario. Thirdly, the range of GHG emissions and costs of other potential scenarios are obtained and plotted through adjusting waste flow with infinitely possible step sizes according to the correlation among the above six scenarios. And the optimal scenario is determined based on this range. The results suggest the following conclusions. 1) The scenarios located on the border between scenario cost minimization and GHG minimization create an optimum curve, and scenario GHG minimization has the smallest eco-efficiency on the curve; 2) Simple pursuit of eco-efficiency minimization using fractional programming may be unreasonable; 3) Balancing GHG emissions from incineration and landfills benefits Tianjin's waste management system as it reduces GHG emissions and costs.展开更多
基金The National Natural Science Foundation of China(No.41877240)Scientific Research Foundation of Graduate School of Southeast University(No.YBPY1930).
文摘Considering that copper mine tailings(CMTs)are commonly mixed with ordinary Portland cement,fly ash(FA),and kaolin to produce geopolymers,to make full use of CMTs,the properties of geopolymers manufactured under different material mass ratios and curing methods(standard curing,water bath curing,and 60℃curing)are evaluated with significantly increased dosage of CMTs.Porosity and unconfined compressive strength tests,X-ray diffraction,field emission scanning electron microscopy,and energy dispersive spectroscopy are used to determine the physical and mechanical properties,microstructure,and mineral composition of geopolymers.Finally,costs and CO 2 emissions of specimens with different material mass ratios during the preparation processes are compared.The results show that during the geopolymerization of low-calcium materials,various geopolymer gels,including calcium silicate,calcium silicoaluminate,and mainly sodium silicoaluminate gels,coexist.The solid waste,cost,and carbon dioxide emission reductions can reach 100%,166.3 yuan/t,and 73.3 kg/t,respectively.Under a curing condition of 60℃,the sample with a CMTs mass fraction of 70%and an FA mass fraction of 30%meets the requirements of porosity,compressive strength.The resource utilization of CMT and FA is realized in a more economical way.
基金The National Natural Science Foundation of China(No.51576048)the Environmental Protection Subject Foundation of Jiangsu Province(No.2015013)+3 种基金the Industry,Education and Research Prospective Project of Jiangsu Province(No.BY2015060-04)the Fok Ying Tong Education Foundation(No.142026)the Fundamental Research Funds for the Central UniversitiesProgram for New Century Excellent Talents in University(No.NCET-12-0118)
文摘Three different preparation methods including steam physical activation, catalytic carbonation and KOH chemical activation methods were used to prepare municipal solid waste- based carbon materials. The methylene blue （MB） adsorption value was applied to evaluate the adsorption capabilities of the prepared carbon materials. The effects of preparation methods on adsorption capability and yield of products were investigated. The yield of carbon materials with the catalytic carbonation method is the highest, and the KOH activation method is the second level. Considering the adsorption performance, the KOH activation method is much more favorable. Among the different components of municipal solid waste-based carbon materials, the adsorption properties of the single component of paperboard, the double components of tire and paperboard, the triple components of tire, paperboard and polyvinyl chloride （PVC）, and the multi-component mixtures are better than those of other single-, double-, triple- and multi-component mixtures, respectively.
文摘Mine waste and process tailings storage is one of important challenge for which mining operations are increasingly confronted. Treatment discharges of plants and main part of waste rock development are generally stored on surface areas. The volume and chemical characteristics of these materials generate serious problem for required storage spaces and mainly environmental degradation. Paste backfill(PBF) is one of ingenious solutions to minimize the quantity of tailings to store. PBF is basically defined as a combination of mine processing tailings, binder, and water mixing. The purpose of this paper is to present backfilling components characterization and formula verification for a waste valorization solution through paste backfilling technology in Imiter operation. Obtained results and realized analysis demonstrate PBF conformity and adequacy with assigned underground functions. However the studied recipe can be more ameliorated to obtain an optimal mixture ensuring the required mechanical strength.
文摘The design and building of new alternative fuel plants is an increasing necessity to replace old technology and non-renewable fossil fuels. To optimize the performance of these plants and to obtain an economically feasible production of these types of fuels, it is necessary to have a total control of each variable involved in the process of production and how these factors affect the yield of fuel production. In this paper it is proposed a model of a digester to generate gas using a Vensim software designed to generate simulations in dynamic state. This simulation was developed using differential equations to model the behavior at each stage of the process and auxiliary conditions to complement the mathematical description of the model. The main factors in the biogas production are the retention time and the methanogen mortality ratio. For retention time lower than 10 h the process loses effectiveness due to bacterial growth is not completed efficiently, but a high retention time involves a bigger reactor and the yield of production decreases considerably for retention time higher than 40 h. The best yields were obtained for a mortality ratio in methanogen and acidogenic bacteria lower than 0.2 and a retention time of 30 h with a final production of 3.33 L by each kilogram of biomass.
基金Project(51406133) supported by the National Natural Science Foundation of ChinaProject supported by the Scientific Research Foundation for the Returned Overseas,ChinaProject supported by Independent Innovation Fund of Tianjin University,China
文摘To reduce carbon intensity, an improved management method balancing the reduction in costs and greenhouse gas(GHG)emissions is required for Tianjin's waste management system. Firstly, six objective functions, namely, cost minimization, GHG minimization, eco-efficiency minimization, cost maximization, GHG maximization and eco-efficiency maximization, are built and subjected to the same constraints with each objective function corresponding to one scenario. Secondly, GHG emissions and costs are derived from the waste flow of each scenario. Thirdly, the range of GHG emissions and costs of other potential scenarios are obtained and plotted through adjusting waste flow with infinitely possible step sizes according to the correlation among the above six scenarios. And the optimal scenario is determined based on this range. The results suggest the following conclusions. 1) The scenarios located on the border between scenario cost minimization and GHG minimization create an optimum curve, and scenario GHG minimization has the smallest eco-efficiency on the curve; 2) Simple pursuit of eco-efficiency minimization using fractional programming may be unreasonable; 3) Balancing GHG emissions from incineration and landfills benefits Tianjin's waste management system as it reduces GHG emissions and costs.
