Scrapped tires from vehicles are produced in large quantities. Despite numerous existing uses of scrapped tires, alarge quantity ends up at the landfill sites, which contributes to environmental degradation. The devel...Scrapped tires from vehicles are produced in large quantities. Despite numerous existing uses of scrapped tires, alarge quantity ends up at the landfill sites, which contributes to environmental degradation. The development ofmore applications of scrapped tire usage can reduce the disposal of tires at landfill sites. This research proposes anovel use of scrapped tires by using the strips taken from scrapped tires in replacement of steel bars as reinforcement. Manhole covers were produced using scrapped tires by completely replacing the steel with scrapped tires.Four different samples of manhole covers were prepared and tested. The highest bearing capacity of 25.5 kN wasrecorded with a sample of 100 mm thickness made with cementitious composite, which is 2.25 times higher thanthe bearing capacity of a conventional reinforced-concrete manhole cover. The use of manhole covers made withscrapped tires can effectively address the theft issue of manhole covers. The lifecycle cost analysis shows that themanhole cover made with scrapped tires is 3.4 times more cost-effective in comparison with the conventionalmanhole cover. This research shows a new avenue of the potential use of scrapped tires as reinforcement in structures, which can improve sustainable construction practices.展开更多
Magnesium(Mg)alloys are widely used lightweight structural materials for automobiles and help reduce carbon emissions.However,their use increases the production of Mg alloy scrap,which is recycled at a much lower rate...Magnesium(Mg)alloys are widely used lightweight structural materials for automobiles and help reduce carbon emissions.However,their use increases the production of Mg alloy scrap,which is recycled at a much lower rate than aluminum,and its greater complexity poses challenges to existing recycling processes.Although vacuum distillation can be used to recycle Mg alloy scrap,this requires optimizing and maximizing metal recirculation,but there has been no thermodynamic analysis of this process.In this study,the feasibility and controllability of separating inclusions and 23 metal impurities were evaluated,and their distribution and removal limits were quantified.Thermodynamic analyses and experimental results showed that inclusions and impurity metals of separation coefficient lgβ_(i)≤-5,including Cu,Fe,Co,and Ni below 0.001 ppm,could be removed from the matrix.All Zn entered the recycled Mg,while impurities with-1<lgβ_(i)<-5 such as Li,Ca,and Mn severely affected the purity of the recycled Mg during the later stage of distillation.Therefore,an optimization strategy for vacuum distillation recycling:lower temperatures and higher system pressures for Zn separation in the early stage,and the early termination of the recovery process in the later stage or a continuous supply of raw melt can also prevent contamination during recycling.The alloying elements Al and Zn in Mg alloy scrap can be further recovered and purified by vacuum distillation when economically feasible,to maximize the recycling of metal resources.展开更多
Title:Seismic fragility of unreinforced masonry buildings with bonded scrap tire rubber isolators under far-field and near-field earthquakes Authors:WANG Mingyang;GAO Wenjun;LU Xilin;SHI Weixing A bstract:To improve t...Title:Seismic fragility of unreinforced masonry buildings with bonded scrap tire rubber isolators under far-field and near-field earthquakes Authors:WANG Mingyang;GAO Wenjun;LU Xilin;SHI Weixing A bstract:To improve the seismic performance of unreinforced masonry(URM)buildings in the Himalayan regions,including Western China,India,Nepal,and Pakistan,a low-cost bonded scrap tire rubber isolator(BSTRI)is proposed,and a series of vertical compression and horizontal shear tests are conducted.Incremental dynamic analyses are conducted for five types of BSTRI-supported URM buildings subjected to 22 far-field and 28 near-field earthquake ground motions.The resulting fragility curves and probability of damage curves are presented and utilized to evaluate the damage states of these buildings.The results show that in the base-isolated(BI)URM buildings under seismic ground motion at a peak ground acceleration(PGA)of 1.102 g,the probability of exceeding the collapse prevention threshold is less than 25%under far-field earthquake ground motions and 31%under near-field earthquake ground motions.Furthermore,the maximum average vulnerability index for the BI-URM buildings,which are designed to withstand rare earthquakes with 9°(PGA=0.632 g),is 40.87%for far-field earthquake ground motions and 41.83%for near-field earthquake ground motions.Therefore,the adoption of BSTRIs can significantly reduce the collapse probability of URM buildings.展开更多
Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespre...Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespread use in aerospace and defense industries.However,with the growing volume of end-of-life components and inherently low production yields,the efficient recycling of rare earth-containing magnesium alloys has become increasingly critical.This study explores the separation and enrichment behavior of magnesium and neodymium during the vacuum recycling of rare earth magnesium alloys,utilizing gas-liquid phase theory and phase diagram computational methods.Both theoretical analyses and experimental results indicate that the separation process in the Mg-Nd system—whether by vacuum distillation or gasification—follows a consistent phase transformation sequence:Mg_(41)Nd_(5)→Mg_(3)Nd→MgNd→Nd.Two distinct neodymium-rich morphologies were observed:a loose porous structure and a dense,compact form.Notably,vacuum gasification of ZM6 rare earth magnesium alloy resulted in a neodymium concentration of 82.91 wt.%in the solid residue.The process demonstrated high direct recovery efficiency,rapid separation kinetics,and zero secondary waste generation—establishing it as a green and highly efficient recycling approach for magnesium alloy scrap.These findings provide fundamental theoretical and practical support for the recycling of Nd-containing magnesium alloys and contribute to the sustainable utilization of secondary rare earth resources.展开更多
Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare eart...Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare earth(RE)elements(especially Dy)are unevenly distributed globally.Therefore,an environmental-friendly recycling method for RE elements with a highly precise separation of Dy and Nd from end-of-life magnets is required to realize a carbon-neutral society.As an alternative to traditional hydrometallurgical RE separation techniques with a high environmental load,we designed a novel,highly efficient,and precise process for the separation and recycling of RE elements from magnet scrap.As a result,over 90%of the RE elements were efficiently extracted from the magnets using MgCl_(2)and evaporation loss was selectively suppressed by adding CaF_(2).The extracted RE elements were electrolytically separated based on the formation potential differences of the RE alloys.Nd and Dy metals with purities greater than 90%were estimated to be recovered at rates of 96%and 91%,respectively.Almost all the RE in the scraps could be separated and recycled as RE metals,and the byproducts were easily removed.Thus,this process is expected to be used on an industrial scale to realize a carbon-neutral society.展开更多
Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this stud...Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this study,the effects of paint layers on metal surfaces during LIBS classification were investigated.LIBS spectra were collected from metal surfaces painted with black and white paints by ablation with a nanosecond pulsed laser(wavelength=1064 nm,pulse width=7 ns).For the black-painted samples,the LIBS spectra showed a broad background emission,emission lines unrelated to the target metals,large shot-to-shot variation,and a relatively low signal intensity of the target metal,causing poor classification accuracy even at high shot numbers.Cleaning the black paint layer by ablating over a wide area prior to LIBS analysis resulted in high classification accuracy with fewer shot numbers.A method to determine the number of cleaning shots necessary to obtain high classification accuracy and high throughput is proposed on the basis of the change in LIBS signal intensity during cleaning shots.For the white-painted samples,the paint peeled off the metal surface after the first shot,and strong LIBS signals were measured after the following shot,which were attributed to the nanoparticles generated by the ablation of the paint,allowing an accurate classification after only two shots.The results demonstrate that different approaches must be employed depending on the paint color to achieve high classification accuracy with fewer shot numbers.展开更多
The NdFeB scrap,as a representative solid waste of rare earths,possesses significant recyclable value.This study focused on NdFeB waste and investigated the environmental impacts of pyro-and hydro-metallurgical proces...The NdFeB scrap,as a representative solid waste of rare earths,possesses significant recyclable value.This study focused on NdFeB waste and investigated the environmental impacts of pyro-and hydro-metallurgical process(PH-M process)and its improved version,the pyro-and hydro-metallurgical improvement process(PH-Mi process).The results demonstrate that,although the PH-Mi process consumes higher amounts of energy,electricity,and chemicals compared to the PH-M process,it is more environmentally friendly and economically efficient(i.e.,net profit increased by 34.12%).To quantify and compare the environmental performance of the two scenarios,life cycle assessment methodology was applied.It is concluded that the PH-Mi process is superior to the PH-M process for eutrophication potential(EP)and the total environmental impacts.In comparison with PH-Mi process,PH-M process exhibits a certain advantage in terms of carbon footprint due to increased consumption of electricity and chemicals after the technological upgrade.展开更多
Highly efficient removal of impurity Bi element from scrap brass can facilitate the recycling process of brass.The effects of melting temperature,holding time and Mg-Ca alloy content on the removal effect of impurity ...Highly efficient removal of impurity Bi element from scrap brass can facilitate the recycling process of brass.The effects of melting temperature,holding time and Mg-Ca alloy content on the removal effect of impurity Bi element were investigated by compound-separation method.The mechanism of the compound-separation method was revealed for removing the Bi element from a thermodynamic point of view.The results showed that the Bi content was decreased from 1.95 wt.%to 0.178 wt.%at the optimum process parameters of melting temperature of 980°C,holding time of 20 min,and Mg-Ca alloy content of 6 wt.%,achieving a removal rate of 90.9%.A small amount of Ca-Bi compound remained in the brass matrix after refining.NaF flux can effectively wet and adsorb Ca-Bi compounds due to its low viscosity and the function of lowering the surface tension,which facilitate the agglomeration and flotation of Ca-Bi compounds to the melt surface,thereby ensuring the sufficient removal of Bi element.展开更多
Recycling-oriented alloy design is a crucial part of material sustainability,as it reduces the need for raw material extraction and minimises environmental impact.This requires that scraps be reused or repurposed effe...Recycling-oriented alloy design is a crucial part of material sustainability,as it reduces the need for raw material extraction and minimises environmental impact.This requires that scraps be reused or repurposed effectively,even when the scraps are co-mingled and have higher costs for further sorting and separation.In this work,we explore an alloy design concept by creating a compositionally flexible domain that can recycle multiple alloy grades and yet maintain relatively consistent properties across chemical variations.This is demonstrated through the Fe-Cr-Ni-Mn system to identify compositionally flexible austenitic stainless steels(CF-ASS)and accommodate the recycling of mixed austenitic stainless steel scraps.Alloys within the nominal composition spaces exhibit relatively consistent mechanical properties and corrosion resistance despite significant variations in different alloy compositions.We illustrate how we can utilise the compositionally flexible austenitic stainless steels to recycle mixed 200 and 300-series stainless steel and ferronickel scraps,demonstrating its practical viability.While this demonstration focuses on the stainless steel system,the underlying principles can be extended to other systems related to mixed scrap recycling.展开更多
To improve the seismic performance of unrein-forced masonry(URM)buildings in the Himalayan re-gions,including Western China,India,Nepal,and Paki-stan,a low-cost bonded scrap tire rubber isolator(BSTRI)is proposed,and ...To improve the seismic performance of unrein-forced masonry(URM)buildings in the Himalayan re-gions,including Western China,India,Nepal,and Paki-stan,a low-cost bonded scrap tire rubber isolator(BSTRI)is proposed,and a series of vertical compression and horizontal shear tests are conducted.Incremental dynamic analyses are conducted for five types of BSTRI-supported URM buildings subjected to 22 far-field and 28 near-field earthquake ground motions.The resulting fragility curves and probability of damage curves are presented and utilized to evaluate the damage states of these buildings.The results show that in the base-isolated(BI)URM buildings under seismic ground motion at a peak ground acceleration(PGA)of 1.102g,the probability of exceeding the collapse prevention threshold is less than 25%under far-field earthquake ground motions and 31%under near-field earthquake ground motions.Furthermore,the maximum average vulnerability index for the BI-URM buildings,which are designed to withstand rare earthquakes with 9°(PGA=0.632g),is 40.87%for far-field earthquake ground motions and 41.83%for near-field earthquake ground motions.Therefore,the adoption of BSTRIs can significantly reduce the collapse probability of URM buildings.展开更多
A new technological process involving the introduction of an induction furnace(IF)powered by green electricity was proposed for reducing the CO_(2) emission in the conventional blast furnace–basic oxygen furnace(BF–...A new technological process involving the introduction of an induction furnace(IF)powered by green electricity was proposed for reducing the CO_(2) emission in the conventional blast furnace–basic oxygen furnace(BF–BOF)steelmaking route.The proposed BF–IF–BOF process gains benefits from preheating and smelting scraps utilizing green electricity and further remarkably cuts down the CO_(2) emission in BOF steelmaking.The CO_(2) emissions of conventional and new processes have been comparatively analyzed according to the actual data from a commercial steel plant in China,taking into account the upstream CO_(2) emission,direct CO_(2) emission,and credit CO_(2) emission.The analysis revealed that the CO_(2) emission factor of internal scraps from the steel plant was different from that of purchased scraps from the society but equalled to that of crude steel.The CO_(2) injected into the BOF as a coolant could be defined as the upstream CO_(2) emission source,and there is a net reduction of 1 t CO_(2) emission for each ton of CO_(2) utilized in the BOF.Compared to the BF–BOF process with a scrap ratio of 19.23%,the CO_(2) emission reduction per ton of steel in the new process is 0.278,0.517,0.753,0.987,1.219,1.448,and 1.683 t,respectively,as the scrap ratio increases to 30%,40%,50%,60%,70%,80%,and 90%,and increasing the scrap ratio has a more significant impact on the emission reduction than CO_(2) injecting.A minimum CO_(2) emission model for the BF–IF–BOF process was established,and the minimum CO_(2) emission per ton crude steel was calculated to be 0.677,0.581,0.487,0.393,0.300,0.209,and 0.110 t,for the BF–IF–BOF process with the scrap ratios of 30%,40%,50%,60%,70%,80%,and 90%,respectively.展开更多
Unmanaged wood waste,particularly in countries like Nepal,presents serious environmental concerns due to open burning and improper disposal,leading to carbon emissions,air pollution and land degradation.This study int...Unmanaged wood waste,particularly in countries like Nepal,presents serious environmental concerns due to open burning and improper disposal,leading to carbon emissions,air pollution and land degradation.This study introduces an environmentally sustainable strategy to upcycle Toona ciliata wood scrap—an abundant and underutilized lignocellulosic biomass—into high performance carbon electrodes for green energy storage applications.Activated carbon(TCWAC)was synthesized via single-step pyrolytic carbonization followed by phosphoric acid activation,yielding a material with high specific surface area,hierarchical porosity,and excellent electrical conductivity.Electrochemical measurements using a three-electrode configuration in 6 M KOH revealed optimized potential windows of -1.0 to -0.2 V(TCWAC),-1.2 to 0 V(TCWAC-Mn),and -1.15 to -0.4 V(TCWAC-Fe).TCWAC exhibited a specific capacitance of 156.3 Fg^(-1)at 1 Ag^(-1),with an energy density of 3.5 Whkg^(-1),and 80.2% capacity retention after 1000 charge-discharge cycles.Composites with MnO_(2)and Fe_(2)O_(3)were also evaluated.TWAC-Mn delivered 489.4 Fg^(-1),25.1 Whkg^(-1),and 99.1% retention,whereas,TWAC-Fe achieved 321.3 Fg^(-1),6.3 Whkg^(-1),and 90.3% retention.The superior performance of MnO_(2)is attributed to its multiple oxidation states,facilitating reversible faradaic redox and enhanced pseudocapacitance.This work offers the first direct,systematic comparison of MnO_(2)and Fe_(2)O_(3)composites on a common biomass-carbon matrix under identical synthesis and testing conditions.The finding provides mechanistic insight into charge storage behaviour and demonstrate a scalable route for converting biomass waste into sustainable electrode materials,contributing to cleaner energy solutions and improved biomass valorization.展开更多
A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching...A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching time on chemical composition,particle size and magnetic properties was investigated.Due to the low reduction potential of rare earth element(REE),the Nd-rich phase was preferentially leached.The use of an acid concentration of 0.5 mol/L,a solid to liquid ratio of 1/10 and a leaching time of 30 min was sufficient to leach the Nd-rich phase.Atomic resolution transmission electron microscopy was employed to examine the surface structure and chemistry of the leached Nd_(2)Fe_(14)B powder.It is revealed that the leaching process affects not only the Nd-rich phase but also the matrix grains,resulting in the formation of a predominant oxygen-rich amorphous reaction layer,25 nm thick.However,the oxygen content is reduced from 3500 to 2500 ppm and the magnetic saturation is increased by 8%.This method is a promising addition to the HPMS process,as the powder can be mixed with fresh,unoxidized grain boundary phase to produce recycled magnets with high remanence.展开更多
This paper establishes a model for the production cost of iron and steel enterprise.The variation rule of the production cost versus the iron/steel ratio for two cases, namely,fixed steel production and a fixed amount...This paper establishes a model for the production cost of iron and steel enterprise.The variation rule of the production cost versus the iron/steel ratio for two cases, namely,fixed steel production and a fixed amount of molten iron,is analyzed,and the concept of a steel scrap threshold price is proposed.According to the analysis results,when the steel scrap unit price exceeds the steel scrap threshold price, an increase in the iron/steel ratio can reduce the production cost,and vice versa.When the gap between the steel scrap unit price and the steel scrap threshold price is relatively large, the impact of the iron/steel ratio on the production cost is more prominent.According to the calculation example,when steel production is fixed （284 358 t/month）and the steel scrap unit price is 263.2 yuan/t more than the steel scrap threshold price,an increase of 0.01 in the iron/steel ratio causes a monthly production cost reduction of approximately 750 000 yuan （2.63 yuan/t）.When the amount of molten iron is fixed （270 425 t/month）and the steel scrap unit price is 140.7 yuan/t more than the threshold price,an increase of 0.01 in the iron/steel ratio causes a monthly production cost reduction of approximately 430 000 yuan （1.5 yuan/t）.The results indicate that iron and steel enterprise should adjust the production strategy in time when the scrap price fluctuates, and then the production cost will be reduced.展开更多
The collected tungsten carbide/cobalt scrapped waste typically contains approximately 90% tungsten carbide and 10% cobalt.A nitric method is used to extract tungsten and cobalt from tungsten-containing waste.The waste...The collected tungsten carbide/cobalt scrapped waste typically contains approximately 90% tungsten carbide and 10% cobalt.A nitric method is used to extract tungsten and cobalt from tungsten-containing waste.The waste is first dissolved in nitric acid,which then makes cobalt soluble and becomes cobalt nitrate solution.The waste also oxidizes tungsten carbide to insoluble tungstenic acid precipitate.If tungsten carbide scraps are obtained from leftover of LCD glass cutting,after applying the same process as above,the remaining glass also needs to be separated from the tungstenic acid.XRF analysis shows that 93.8% of cobalt and 97.72% of tungsten can be obtained separately by this wet chemical method.By ICP analysis,no more tungsten ion remains after 2 h reaction in the cobalt recovery when 12 N of nitric acid is used for oxidation.The recovery materials obtained for tungsten are tungsten oxide and for cobalt a mixture of Co3O4 and CoO.展开更多
The degradation of five naphthalene derivatives in the simulated wastewater was investigated using the iron-carbon micro-electrolysis method.The optimal initial pH of solution and adsorption of iron-carbon and removal...The degradation of five naphthalene derivatives in the simulated wastewater was investigated using the iron-carbon micro-electrolysis method.The optimal initial pH of solution and adsorption of iron-carbon and removal efficiency of the total organic carbon(TOC)were investigated.The results show that the removal efficiency of the naphthalene derivatives can reach 48.9%?92.6% and the removal efficiency of TOC is 42.8%?78.0% for the simulated wastewater with 200 mg/L naphthalene derivatives at optimal pH of 2.0?2.5 after 120 min treatment.The degradation of five naphthalene derivatives with the micro-electrolysis shows the apparent first-order kinetics and the order of removal efficiency of the naphthalene derivatives is sodium 2-naphthalenesulfonate,2-naphthol,2,7-dihydroxynaphthalene,1-naphthamine,1-naphthol-8-sulfonic acid in turn.It is illustrated that the substituents of the naphthalene ring can affect the removal efficiency of naphthalene due to their electron-withdrawing or electron-donating ability.展开更多
Molten salt is an excellent medium for chemical reaction,energy transfer,and storage.Molten salt innovative technologies should be developed to recover metals from secondary resources and reserve metals from primary n...Molten salt is an excellent medium for chemical reaction,energy transfer,and storage.Molten salt innovative technologies should be developed to recover metals from secondary resources and reserve metals from primary natural sources.Among these technologies,molten salt electrolysis is an economic and environment-friendly method to extract metals from waste materials.From the perspective of molten salt characteristics,the application of molten salts in chemistry,electrochemistry,energy,and thermal storage should be comprehensively elaborated.This review discusses further directions for the research and development of molten salt electrolysis and their use for metal recovery from various metal wastes,such as magnet scrap,nuclear waste,and cemented carbide scrap.Attention is placed on the development of various electrolysis methods for different metal containing wastes,overcoming some problems in electrolytes,electrodes,and electrolytic cells.Special focus is given to future development directions for current associated processing obstacles.展开更多
Copper consumption increased very quickly in China in recent years,which could not be met by inland copper industry.In order to achieve a sustainable development of copper industry,an analysis of copper recycling in C...Copper consumption increased very quickly in China in recent years,which could not be met by inland copper industry.In order to achieve a sustainable development of copper industry,an analysis of copper recycling in China was necessary.For the life cycle of copper products a copper-flow diagram with time factor was worked out and the contemporary copper recycling in China was analyzed,from which the following data were obtained.The average life cycle of copper products was 30 years.From 1998 to 2002,the use ratio of copper scraps in copper production,the use ratio of copper scraps in copper manufacture,the materials self-support ratio in copper production,and the materials self-support ratio in copper manufacture were 26.50%,15.49%,48.05% and 59.41%,respectively.The materials self-support ratios in copper production and manufacture declined year by year in recent years on the whole,and the latter dropped more quickly.The average index of copper ore and copper scrap from 1998 to 2002 were 0.8475 t/t and 0.0736 t/t,respectively;and copper resource efficiency was 1.1855 t/t.Some efforts should be paid to reduce copper ores consumption and promote copper scraps regeneration.Copper scraps were mostly imported from foreign countries because of shortage in recent years in China.Here the reasons related to copper scraps deficiency were also demonstrated.But we can forecast:when copper production was in a slow rise or in a steady state in China,the deficiency of copper scraps may be mitigated;when copper production was in a steady state for a very long time,copper scraps may become relatively abundant.According to the status of copper industry in China,the raw materials of copper production and manufacture have to depend on oversea markets heavily in recent years,and at the same time,the copper scraps using proportion and efficiency in copper industry should be improved.展开更多
Scrap tires were pyrolyzed in a continuously stirred batch reactor in the presence and absence of catalysts. The maximum yield of derived oil was up to 55.65 wt%at the optimum temperature, 500 °C. The catalytic p...Scrap tires were pyrolyzed in a continuously stirred batch reactor in the presence and absence of catalysts. The maximum yield of derived oil was up to 55.65 wt%at the optimum temperature, 500 °C. The catalytic pyrolysis was performed using 1.0 wt%（on a scrap tire weight basis） of catalysts based on ZSM‐5, USY,β, SAPO‐11, and ZSM‐22. The oil products were characterized using simula‐tion distillation, elemental analysis, and gas chromatography‐mass spectrometry. The results show that using a catalyst can increase the conversion of scrap tires to gas and decrease char by‐products;the yield of derived oil remains unchanged or a little lower. The oils derived from catalytic pyrolysis had H/C ratios of 1.55–1.65 and contained approximately 70–75 wt%light oil, 0.3–0.58 wt%S and 0.78–1.0 wt%N. Catalysts with high acid strengths and appropriate pore sizes, such as ZSM‐5, USY,β, and SAPO‐11, increased the amount of single‐ring aromatics in the light‐middle‐fraction oil to 45 wt%. The derived oil can therefore be used as a petrochemical feedstock for producing high‐value‐added chemical products or fuel oil.展开更多
文摘Scrapped tires from vehicles are produced in large quantities. Despite numerous existing uses of scrapped tires, alarge quantity ends up at the landfill sites, which contributes to environmental degradation. The development ofmore applications of scrapped tire usage can reduce the disposal of tires at landfill sites. This research proposes anovel use of scrapped tires by using the strips taken from scrapped tires in replacement of steel bars as reinforcement. Manhole covers were produced using scrapped tires by completely replacing the steel with scrapped tires.Four different samples of manhole covers were prepared and tested. The highest bearing capacity of 25.5 kN wasrecorded with a sample of 100 mm thickness made with cementitious composite, which is 2.25 times higher thanthe bearing capacity of a conventional reinforced-concrete manhole cover. The use of manhole covers made withscrapped tires can effectively address the theft issue of manhole covers. The lifecycle cost analysis shows that themanhole cover made with scrapped tires is 3.4 times more cost-effective in comparison with the conventionalmanhole cover. This research shows a new avenue of the potential use of scrapped tires as reinforcement in structures, which can improve sustainable construction practices.
文摘Magnesium(Mg)alloys are widely used lightweight structural materials for automobiles and help reduce carbon emissions.However,their use increases the production of Mg alloy scrap,which is recycled at a much lower rate than aluminum,and its greater complexity poses challenges to existing recycling processes.Although vacuum distillation can be used to recycle Mg alloy scrap,this requires optimizing and maximizing metal recirculation,but there has been no thermodynamic analysis of this process.In this study,the feasibility and controllability of separating inclusions and 23 metal impurities were evaluated,and their distribution and removal limits were quantified.Thermodynamic analyses and experimental results showed that inclusions and impurity metals of separation coefficient lgβ_(i)≤-5,including Cu,Fe,Co,and Ni below 0.001 ppm,could be removed from the matrix.All Zn entered the recycled Mg,while impurities with-1<lgβ_(i)<-5 such as Li,Ca,and Mn severely affected the purity of the recycled Mg during the later stage of distillation.Therefore,an optimization strategy for vacuum distillation recycling:lower temperatures and higher system pressures for Zn separation in the early stage,and the early termination of the recovery process in the later stage or a continuous supply of raw melt can also prevent contamination during recycling.The alloying elements Al and Zn in Mg alloy scrap can be further recovered and purified by vacuum distillation when economically feasible,to maximize the recycling of metal resources.
文摘Title:Seismic fragility of unreinforced masonry buildings with bonded scrap tire rubber isolators under far-field and near-field earthquakes Authors:WANG Mingyang;GAO Wenjun;LU Xilin;SHI Weixing A bstract:To improve the seismic performance of unreinforced masonry(URM)buildings in the Himalayan regions,including Western China,India,Nepal,and Pakistan,a low-cost bonded scrap tire rubber isolator(BSTRI)is proposed,and a series of vertical compression and horizontal shear tests are conducted.Incremental dynamic analyses are conducted for five types of BSTRI-supported URM buildings subjected to 22 far-field and 28 near-field earthquake ground motions.The resulting fragility curves and probability of damage curves are presented and utilized to evaluate the damage states of these buildings.The results show that in the base-isolated(BI)URM buildings under seismic ground motion at a peak ground acceleration(PGA)of 1.102 g,the probability of exceeding the collapse prevention threshold is less than 25%under far-field earthquake ground motions and 31%under near-field earthquake ground motions.Furthermore,the maximum average vulnerability index for the BI-URM buildings,which are designed to withstand rare earthquakes with 9°(PGA=0.632 g),is 40.87%for far-field earthquake ground motions and 41.83%for near-field earthquake ground motions.Therefore,the adoption of BSTRIs can significantly reduce the collapse probability of URM buildings.
基金supported by the National Natural Science Foundation of China(No.92475108)Yunnan Province Nonferrous Metal Vacuum Metallurgy Top Team(No.202305AS350012).
文摘Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespread use in aerospace and defense industries.However,with the growing volume of end-of-life components and inherently low production yields,the efficient recycling of rare earth-containing magnesium alloys has become increasingly critical.This study explores the separation and enrichment behavior of magnesium and neodymium during the vacuum recycling of rare earth magnesium alloys,utilizing gas-liquid phase theory and phase diagram computational methods.Both theoretical analyses and experimental results indicate that the separation process in the Mg-Nd system—whether by vacuum distillation or gasification—follows a consistent phase transformation sequence:Mg_(41)Nd_(5)→Mg_(3)Nd→MgNd→Nd.Two distinct neodymium-rich morphologies were observed:a loose porous structure and a dense,compact form.Notably,vacuum gasification of ZM6 rare earth magnesium alloy resulted in a neodymium concentration of 82.91 wt.%in the solid residue.The process demonstrated high direct recovery efficiency,rapid separation kinetics,and zero secondary waste generation—establishing it as a green and highly efficient recycling approach for magnesium alloy scrap.These findings provide fundamental theoretical and practical support for the recycling of Nd-containing magnesium alloys and contribute to the sustainable utilization of secondary rare earth resources.
基金supported by a Grant-in-Aid from the Japan Society for the Promotion of Science(JSPS)Fellows(19J20301).
文摘Owing to the worldwide trend towards carbon neutrality,the number of Dy-containing heat-resistant Nd magnets used for wind power generation and electric vehicles is expected to increase exponentially.However,rare earth(RE)elements(especially Dy)are unevenly distributed globally.Therefore,an environmental-friendly recycling method for RE elements with a highly precise separation of Dy and Nd from end-of-life magnets is required to realize a carbon-neutral society.As an alternative to traditional hydrometallurgical RE separation techniques with a high environmental load,we designed a novel,highly efficient,and precise process for the separation and recycling of RE elements from magnet scrap.As a result,over 90%of the RE elements were efficiently extracted from the magnets using MgCl_(2)and evaporation loss was selectively suppressed by adding CaF_(2).The extracted RE elements were electrolytically separated based on the formation potential differences of the RE alloys.Nd and Dy metals with purities greater than 90%were estimated to be recovered at rates of 96%and 91%,respectively.Almost all the RE in the scraps could be separated and recycled as RE metals,and the byproducts were easily removed.Thus,this process is expected to be used on an industrial scale to realize a carbon-neutral society.
基金supported by the R&D Center for Valuable Recycling (Global-Top R&D Program)of the Ministry of Environment (No.2016002250003)。
文摘Scrap metals are typically covered with surface contaminants,such as paint,dust,and rust,which can significantly affect the emission spectrum during laser-induced breakdown spectroscopy(LIBS)based sorting.In this study,the effects of paint layers on metal surfaces during LIBS classification were investigated.LIBS spectra were collected from metal surfaces painted with black and white paints by ablation with a nanosecond pulsed laser(wavelength=1064 nm,pulse width=7 ns).For the black-painted samples,the LIBS spectra showed a broad background emission,emission lines unrelated to the target metals,large shot-to-shot variation,and a relatively low signal intensity of the target metal,causing poor classification accuracy even at high shot numbers.Cleaning the black paint layer by ablating over a wide area prior to LIBS analysis resulted in high classification accuracy with fewer shot numbers.A method to determine the number of cleaning shots necessary to obtain high classification accuracy and high throughput is proposed on the basis of the change in LIBS signal intensity during cleaning shots.For the white-painted samples,the paint peeled off the metal surface after the first shot,and strong LIBS signals were measured after the following shot,which were attributed to the nanoparticles generated by the ablation of the paint,allowing an accurate classification after only two shots.The results demonstrate that different approaches must be employed depending on the paint color to achieve high classification accuracy with fewer shot numbers.
基金supported by the National Key R&D Program of China(No.2020YFC1909005).
文摘The NdFeB scrap,as a representative solid waste of rare earths,possesses significant recyclable value.This study focused on NdFeB waste and investigated the environmental impacts of pyro-and hydro-metallurgical process(PH-M process)and its improved version,the pyro-and hydro-metallurgical improvement process(PH-Mi process).The results demonstrate that,although the PH-Mi process consumes higher amounts of energy,electricity,and chemicals compared to the PH-M process,it is more environmentally friendly and economically efficient(i.e.,net profit increased by 34.12%).To quantify and compare the environmental performance of the two scenarios,life cycle assessment methodology was applied.It is concluded that the PH-Mi process is superior to the PH-M process for eutrophication potential(EP)and the total environmental impacts.In comparison with PH-Mi process,PH-M process exhibits a certain advantage in terms of carbon footprint due to increased consumption of electricity and chemicals after the technological upgrade.
基金the financial supplies supported by the National Natural Science Foundation of China(Nos.U2202255,52371038)the Science and Technology Innovation Program of Hunan Province,China(No.2023RC1019)。
文摘Highly efficient removal of impurity Bi element from scrap brass can facilitate the recycling process of brass.The effects of melting temperature,holding time and Mg-Ca alloy content on the removal effect of impurity Bi element were investigated by compound-separation method.The mechanism of the compound-separation method was revealed for removing the Bi element from a thermodynamic point of view.The results showed that the Bi content was decreased from 1.95 wt.%to 0.178 wt.%at the optimum process parameters of melting temperature of 980°C,holding time of 20 min,and Mg-Ca alloy content of 6 wt.%,achieving a removal rate of 90.9%.A small amount of Ca-Bi compound remained in the brass matrix after refining.NaF flux can effectively wet and adsorb Ca-Bi compounds due to its low viscosity and the function of lowering the surface tension,which facilitate the agglomeration and flotation of Ca-Bi compounds to the melt surface,thereby ensuring the sufficient removal of Bi element.
基金financially supported by the National Key Research and Development Program(No.2023YFB3712403)the National Natural Science Foundation of China(Nos.52201112,52071066,U22A20106,and U22A20173).
文摘Recycling-oriented alloy design is a crucial part of material sustainability,as it reduces the need for raw material extraction and minimises environmental impact.This requires that scraps be reused or repurposed effectively,even when the scraps are co-mingled and have higher costs for further sorting and separation.In this work,we explore an alloy design concept by creating a compositionally flexible domain that can recycle multiple alloy grades and yet maintain relatively consistent properties across chemical variations.This is demonstrated through the Fe-Cr-Ni-Mn system to identify compositionally flexible austenitic stainless steels(CF-ASS)and accommodate the recycling of mixed austenitic stainless steel scraps.Alloys within the nominal composition spaces exhibit relatively consistent mechanical properties and corrosion resistance despite significant variations in different alloy compositions.We illustrate how we can utilise the compositionally flexible austenitic stainless steels to recycle mixed 200 and 300-series stainless steel and ferronickel scraps,demonstrating its practical viability.While this demonstration focuses on the stainless steel system,the underlying principles can be extended to other systems related to mixed scrap recycling.
基金The National Natural Science Foundation of China(No.52208195)the Independent Subject of State Key Laboratory of Disaster Reduction in Civil Engineering of Tongji University(No.SLDRCE19-A-10).
文摘To improve the seismic performance of unrein-forced masonry(URM)buildings in the Himalayan re-gions,including Western China,India,Nepal,and Paki-stan,a low-cost bonded scrap tire rubber isolator(BSTRI)is proposed,and a series of vertical compression and horizontal shear tests are conducted.Incremental dynamic analyses are conducted for five types of BSTRI-supported URM buildings subjected to 22 far-field and 28 near-field earthquake ground motions.The resulting fragility curves and probability of damage curves are presented and utilized to evaluate the damage states of these buildings.The results show that in the base-isolated(BI)URM buildings under seismic ground motion at a peak ground acceleration(PGA)of 1.102g,the probability of exceeding the collapse prevention threshold is less than 25%under far-field earthquake ground motions and 31%under near-field earthquake ground motions.Furthermore,the maximum average vulnerability index for the BI-URM buildings,which are designed to withstand rare earthquakes with 9°(PGA=0.632g),is 40.87%for far-field earthquake ground motions and 41.83%for near-field earthquake ground motions.Therefore,the adoption of BSTRIs can significantly reduce the collapse probability of URM buildings.
基金supported by the National High-end Foreign Expert Introduction Program Project(No.G2023105012L).
文摘A new technological process involving the introduction of an induction furnace(IF)powered by green electricity was proposed for reducing the CO_(2) emission in the conventional blast furnace–basic oxygen furnace(BF–BOF)steelmaking route.The proposed BF–IF–BOF process gains benefits from preheating and smelting scraps utilizing green electricity and further remarkably cuts down the CO_(2) emission in BOF steelmaking.The CO_(2) emissions of conventional and new processes have been comparatively analyzed according to the actual data from a commercial steel plant in China,taking into account the upstream CO_(2) emission,direct CO_(2) emission,and credit CO_(2) emission.The analysis revealed that the CO_(2) emission factor of internal scraps from the steel plant was different from that of purchased scraps from the society but equalled to that of crude steel.The CO_(2) injected into the BOF as a coolant could be defined as the upstream CO_(2) emission source,and there is a net reduction of 1 t CO_(2) emission for each ton of CO_(2) utilized in the BOF.Compared to the BF–BOF process with a scrap ratio of 19.23%,the CO_(2) emission reduction per ton of steel in the new process is 0.278,0.517,0.753,0.987,1.219,1.448,and 1.683 t,respectively,as the scrap ratio increases to 30%,40%,50%,60%,70%,80%,and 90%,and increasing the scrap ratio has a more significant impact on the emission reduction than CO_(2) injecting.A minimum CO_(2) emission model for the BF–IF–BOF process was established,and the minimum CO_(2) emission per ton crude steel was calculated to be 0.677,0.581,0.487,0.393,0.300,0.209,and 0.110 t,for the BF–IF–BOF process with the scrap ratios of 30%,40%,50%,60%,70%,80%,and 90%,respectively.
文摘Unmanaged wood waste,particularly in countries like Nepal,presents serious environmental concerns due to open burning and improper disposal,leading to carbon emissions,air pollution and land degradation.This study introduces an environmentally sustainable strategy to upcycle Toona ciliata wood scrap—an abundant and underutilized lignocellulosic biomass—into high performance carbon electrodes for green energy storage applications.Activated carbon(TCWAC)was synthesized via single-step pyrolytic carbonization followed by phosphoric acid activation,yielding a material with high specific surface area,hierarchical porosity,and excellent electrical conductivity.Electrochemical measurements using a three-electrode configuration in 6 M KOH revealed optimized potential windows of -1.0 to -0.2 V(TCWAC),-1.2 to 0 V(TCWAC-Mn),and -1.15 to -0.4 V(TCWAC-Fe).TCWAC exhibited a specific capacitance of 156.3 Fg^(-1)at 1 Ag^(-1),with an energy density of 3.5 Whkg^(-1),and 80.2% capacity retention after 1000 charge-discharge cycles.Composites with MnO_(2)and Fe_(2)O_(3)were also evaluated.TWAC-Mn delivered 489.4 Fg^(-1),25.1 Whkg^(-1),and 99.1% retention,whereas,TWAC-Fe achieved 321.3 Fg^(-1),6.3 Whkg^(-1),and 90.3% retention.The superior performance of MnO_(2)is attributed to its multiple oxidation states,facilitating reversible faradaic redox and enhanced pseudocapacitance.This work offers the first direct,systematic comparison of MnO_(2)and Fe_(2)O_(3)composites on a common biomass-carbon matrix under identical synthesis and testing conditions.The finding provides mechanistic insight into charge storage behaviour and demonstrate a scalable route for converting biomass waste into sustainable electrode materials,contributing to cleaner energy solutions and improved biomass valorization.
基金Project supported by the German Federal Ministry of Education and Research as part of the program"FH-Kooperativ"the European Commission under the Horizon Europe Research and Innovation Program(101058598)。
文摘A single-phase Nd_(2)Fe_(14)B powder was prepared from end-of-life(EOL)wind turbine magnets by a combination of hydrogen processing of magnetic scrap(HPMS)and selective leaching with citric acid.The impact of leaching time on chemical composition,particle size and magnetic properties was investigated.Due to the low reduction potential of rare earth element(REE),the Nd-rich phase was preferentially leached.The use of an acid concentration of 0.5 mol/L,a solid to liquid ratio of 1/10 and a leaching time of 30 min was sufficient to leach the Nd-rich phase.Atomic resolution transmission electron microscopy was employed to examine the surface structure and chemistry of the leached Nd_(2)Fe_(14)B powder.It is revealed that the leaching process affects not only the Nd-rich phase but also the matrix grains,resulting in the formation of a predominant oxygen-rich amorphous reaction layer,25 nm thick.However,the oxygen content is reduced from 3500 to 2500 ppm and the magnetic saturation is increased by 8%.This method is a promising addition to the HPMS process,as the powder can be mixed with fresh,unoxidized grain boundary phase to produce recycled magnets with high remanence.
基金The National Key Technology R&D Program during the 12th Five-Year Plan Period(No.2012BAF10B05)
文摘This paper establishes a model for the production cost of iron and steel enterprise.The variation rule of the production cost versus the iron/steel ratio for two cases, namely,fixed steel production and a fixed amount of molten iron,is analyzed,and the concept of a steel scrap threshold price is proposed.According to the analysis results,when the steel scrap unit price exceeds the steel scrap threshold price, an increase in the iron/steel ratio can reduce the production cost,and vice versa.When the gap between the steel scrap unit price and the steel scrap threshold price is relatively large, the impact of the iron/steel ratio on the production cost is more prominent.According to the calculation example,when steel production is fixed （284 358 t/month）and the steel scrap unit price is 263.2 yuan/t more than the steel scrap threshold price,an increase of 0.01 in the iron/steel ratio causes a monthly production cost reduction of approximately 750 000 yuan （2.63 yuan/t）.When the amount of molten iron is fixed （270 425 t/month）and the steel scrap unit price is 140.7 yuan/t more than the threshold price,an increase of 0.01 in the iron/steel ratio causes a monthly production cost reduction of approximately 430 000 yuan （1.5 yuan/t）.The results indicate that iron and steel enterprise should adjust the production strategy in time when the scrap price fluctuates, and then the production cost will be reduced.
基金Supported by the project of National Science Council in Taiwan(No.:NSC-95-2622-E-159)
文摘The collected tungsten carbide/cobalt scrapped waste typically contains approximately 90% tungsten carbide and 10% cobalt.A nitric method is used to extract tungsten and cobalt from tungsten-containing waste.The waste is first dissolved in nitric acid,which then makes cobalt soluble and becomes cobalt nitrate solution.The waste also oxidizes tungsten carbide to insoluble tungstenic acid precipitate.If tungsten carbide scraps are obtained from leftover of LCD glass cutting,after applying the same process as above,the remaining glass also needs to be separated from the tungstenic acid.XRF analysis shows that 93.8% of cobalt and 97.72% of tungsten can be obtained separately by this wet chemical method.By ICP analysis,no more tungsten ion remains after 2 h reaction in the cobalt recovery when 12 N of nitric acid is used for oxidation.The recovery materials obtained for tungsten are tungsten oxide and for cobalt a mixture of Co3O4 and CoO.
基金Project(05KJD6010110) supported by the Natural Science Foundation of the Education Commission of Jiangsu Province,ChinaProject(2005005) supported by the Science and Technology Foundation of the Environmental Protection Bureau of Jiangsu Province,China
文摘The degradation of five naphthalene derivatives in the simulated wastewater was investigated using the iron-carbon micro-electrolysis method.The optimal initial pH of solution and adsorption of iron-carbon and removal efficiency of the total organic carbon(TOC)were investigated.The results show that the removal efficiency of the naphthalene derivatives can reach 48.9%?92.6% and the removal efficiency of TOC is 42.8%?78.0% for the simulated wastewater with 200 mg/L naphthalene derivatives at optimal pH of 2.0?2.5 after 120 min treatment.The degradation of five naphthalene derivatives with the micro-electrolysis shows the apparent first-order kinetics and the order of removal efficiency of the naphthalene derivatives is sodium 2-naphthalenesulfonate,2-naphthol,2,7-dihydroxynaphthalene,1-naphthamine,1-naphthol-8-sulfonic acid in turn.It is illustrated that the substituents of the naphthalene ring can affect the removal efficiency of naphthalene due to their electron-withdrawing or electron-donating ability.
基金the National Natural Science Foundation of China(No.51621003)the Beijing Natural Science Foundation(No.2204073).
文摘Molten salt is an excellent medium for chemical reaction,energy transfer,and storage.Molten salt innovative technologies should be developed to recover metals from secondary resources and reserve metals from primary natural sources.Among these technologies,molten salt electrolysis is an economic and environment-friendly method to extract metals from waste materials.From the perspective of molten salt characteristics,the application of molten salts in chemistry,electrochemistry,energy,and thermal storage should be comprehensively elaborated.This review discusses further directions for the research and development of molten salt electrolysis and their use for metal recovery from various metal wastes,such as magnet scrap,nuclear waste,and cemented carbide scrap.Attention is placed on the development of various electrolysis methods for different metal containing wastes,overcoming some problems in electrolytes,electrodes,and electrolytic cells.Special focus is given to future development directions for current associated processing obstacles.
基金Supported by Key Technologies R&D Programme(No.2003BA614A-02)
文摘Copper consumption increased very quickly in China in recent years,which could not be met by inland copper industry.In order to achieve a sustainable development of copper industry,an analysis of copper recycling in China was necessary.For the life cycle of copper products a copper-flow diagram with time factor was worked out and the contemporary copper recycling in China was analyzed,from which the following data were obtained.The average life cycle of copper products was 30 years.From 1998 to 2002,the use ratio of copper scraps in copper production,the use ratio of copper scraps in copper manufacture,the materials self-support ratio in copper production,and the materials self-support ratio in copper manufacture were 26.50%,15.49%,48.05% and 59.41%,respectively.The materials self-support ratios in copper production and manufacture declined year by year in recent years on the whole,and the latter dropped more quickly.The average index of copper ore and copper scrap from 1998 to 2002 were 0.8475 t/t and 0.0736 t/t,respectively;and copper resource efficiency was 1.1855 t/t.Some efforts should be paid to reduce copper ores consumption and promote copper scraps regeneration.Copper scraps were mostly imported from foreign countries because of shortage in recent years in China.Here the reasons related to copper scraps deficiency were also demonstrated.But we can forecast:when copper production was in a slow rise or in a steady state in China,the deficiency of copper scraps may be mitigated;when copper production was in a steady state for a very long time,copper scraps may become relatively abundant.According to the status of copper industry in China,the raw materials of copper production and manufacture have to depend on oversea markets heavily in recent years,and at the same time,the copper scraps using proportion and efficiency in copper industry should be improved.
基金supported by the Basic Research Program of VCC Technology(ycsy2014ky-A-14)~~
文摘Scrap tires were pyrolyzed in a continuously stirred batch reactor in the presence and absence of catalysts. The maximum yield of derived oil was up to 55.65 wt%at the optimum temperature, 500 °C. The catalytic pyrolysis was performed using 1.0 wt%（on a scrap tire weight basis） of catalysts based on ZSM‐5, USY,β, SAPO‐11, and ZSM‐22. The oil products were characterized using simula‐tion distillation, elemental analysis, and gas chromatography‐mass spectrometry. The results show that using a catalyst can increase the conversion of scrap tires to gas and decrease char by‐products;the yield of derived oil remains unchanged or a little lower. The oils derived from catalytic pyrolysis had H/C ratios of 1.55–1.65 and contained approximately 70–75 wt%light oil, 0.3–0.58 wt%S and 0.78–1.0 wt%N. Catalysts with high acid strengths and appropriate pore sizes, such as ZSM‐5, USY,β, and SAPO‐11, increased the amount of single‐ring aromatics in the light‐middle‐fraction oil to 45 wt%. The derived oil can therefore be used as a petrochemical feedstock for producing high‐value‐added chemical products or fuel oil.
