Materials Science Forum Vol. 847

Abstract: Foam glass was widely used as a green energy saving material with good performances of light, thermal insulation and sound absorption. Using waste glass as raw material for foam glass production, can not only turn waste into treasure and reduce resource consumption, but also protect the environment. In this article, the foam glass which produced in Jiaxing, China was studied based on the method of life cycle assessment (LCA), and the resources, the energy consumption and the emission of pollutants at the same time were evaluated. The results show that the characterization value of GWP is the largest. The foaming stage is the main contributor which accounts for 79.7%. Similarly, the foaming stage is the major contributor to AP, POCP, EP and HTP .The characterization value of ADP is the smallest. The foaming stage and annealing stage is the main contributor to ADP which account for 43.0%, 49.7% respectively. It has been found that the foaming stage makes the most contribution to the environmental impact. AP, GWP, POCP and EP of the foaming stage are extremely prominent compared to other stages. The authors used the methods of equal weight coefficient and AHP to weight the single indicator. The results show that the environment impact caused by the foaming stage is the largest, then grinding stage and cutting stage follow behind. The environment impact caused by the transportation stage is the smallest.

Abstract: Magnesium is a promising lightweight and green metallic engineering material, but the environmental impact of primary magnesium production stage, especially greenhouse gas (GHG) emissions cannot be ignored. In this study, the life cycle energy consumption and GHG emissions caused by the production of primary magnesium in the years of 2003-2013 in China were calculated; the factor decomposition was conducted to analyze the GHG emissions of magnesium production process by using logarithmic mean Divisia index method (LMDI), including energy GHG emission factors, energy structure, energy consumption per ton of primary magnesium, production, emissions per unit of dolomite and ferrosilicon, and dolomite and ferrosilicon consumptions per ton of primary magnesium. The results showed that GHG emissions of primary magnesium production increased 260.29*10⁴ t CO_2eq in total from 2003 to 2013. The variety magnesium production contributed the biggest part of GHG emissions, accounting for 418.17%. The energy structure took second place on the contribution of GHG emissions, accounting for-161.49%. The nest part was energy consumption per ton of primary magnesium, accounting for-138.97%. While, the contribution of energy GHG emission factors, emissions per unit of dolomite and ferrosilicon, and dolomite and ferrosilicon consumptions per ton of primary magnesium was relatively small, which were 0.88%, 0.00% -2.72% -4.73% and-11.13%, respectively. Thus, it is the key methods to reduce GHG emissions by optimizing the energy structure and decreasing the energy consumption.

Abstract: Amorphous alloy strips has been widely used in the field of distribution transformers due to its good soft magnetic properties. The resources, energy consumption of the amorphous alloy strips production with the rapid solidification technique and the environmental impacts were calculated based on the life cycle assessment method. The results showed that the largest contribution to the non-renewable resource consumption was ferroboron production process, accounting for 98% of abiotic resource depletion (ADP). And the strip production process had the largest contribution to the global warming potential (GWP), acidification potential (AP), photochemical oxidation potential (POCP), human toxicity potential (HTP),eutrophication potential (EP). Ferroboron production process contributed the biggest environmental impact when producing 1 ton amorphous strip, accounting for 70% of the total environmental impact. Under the new technology for energy-saving and emission-reduction, when the utilization rate of boric acid increased in ferroboron production process, all the environmental impact decreased.

Abstract: In recent years, users replace their mobile phone more and more frequently, therefore, the number of waste mobile phones has been increasing year by year. In 2014, the number was more than 1 billion units. Indium, that has unique optical transparency and electrical conduction properties, is a necessary element in the screen of mobile phone. The potential yield of indium recycled from waste mobile phone is considerable. Recycling indium from waste mobile phones can alleviate the constraints of indium resources while gaining great economic benefit. However, there is no relevant research work to evaluate the potential yield of indium in the waste cell phone. This paper explores the main factors that constraint the efficiency of recycling by predicting potential yield of indium recycled from waste mobile phone, and puts forward the corresponding policy recommendations. The results are based on the Logistic model and Stock-base model and a survey. The results show that the potential yield of indium recycled from waste mobile phone from 2015 to 2035 will increase from 8.7 tonnes to 10.2 tonnes in China. However, the recovery rate of waste mobile phone is very low, the actual available amount is far lower than the potential yield of indium. The main factors that constrain the efficiency of recycling are: (1) it is difficult to guarantee information security; (2) the existing recycling system is not perfect; (3) the technology of recycling indium needs to be improved.

Abstract: China is now confronted with the tasks of both promoting the economic growth and protecting the environment. Environmental protection has been adopted as the basic national policy to achieve sustainable development. The progress and innovations in the field of material science and engineering are expected to make great contributions since they can help to increase efficiency and reduce pollution. In this paper, the environment situation in China was reviewed to highlight some certain fields that need the efforts from material scientists. And some new technologies were also discussed as the potential methods to deal with these problems. In summary, this paper can be served as a clue for the material researchers who want to contribute to Chinese environmental protection.

Abstract: The aim of this paper is to explore material flow analysis, study the resource consumption and environmental impact of the production preparation process of typical rare earth materials. The results showed that in the beneficiation processes, producing one ton of rare earth concentrates (Rare Earth Oxide, REO50%) will also produces 27 tons of iron ore and 21 tons of tailings. The recovery of rare earths is only 16.8%. In roasting processes, roasting one ton (REO50%) of rare earth concentrates will emits 150 ~ 200Kg sulfuric acid mist, 500 ~ 600Kg sulfur dioxide, 30 ~ 40Kg fluoride, 30 ~ 50Kg smoke and1t (containing thorium) radioactive slag, and 1.2 tons of concentrated sulfuric acid should be used. The lower recoveries and large-scale of concentrated sulfuric acid used in roasting processes in rare earth industry are the main reasons lead to high pollution and high emissions.

Abstract: In this study, the CML model for resource depletion was updated based on the current status of the mineral resources and the characteristics of relevant statistics in China; and the characterization factors of resource depletion were determined for the majority of natural minerals which are most used in materials industry. Besides, case studies on iron and steel production (BF-BOF and EAF process) were carried out to demonstrate the valid of the modified and localized resource depletion model. The results show that in terms of category, the development of Chinese steel industry is mainly based on the depletion of the natural iron ore and fluorite. The results also show that for BF-BOF process, abiotic resource depletion potential (ADP) in 2012 is 5.26 times of that in 2004; and for the EAF process, ADP in 2012 is 23.6 times of that in 2004. Therefore, the information of ADP needs to be updated at intervals of time.

Abstract: Plastic pipe is a kind of new pipeline material and its output has been increasing in recent years. It is still mainly used for water supply and drainage of buildings and municipal utility industry as well as for safe drinking in rural areas, about half of all plastic pipelines are used for buildings, and the proportion of these pipelines used in other fields is also increasing. Plastic pipeline system's influence on the environment within its life cycle is the focus of researches in recent years. Based on life cycle assessment (LCA), this paper assesses the common water supply and drainage pipelines (PPR, PE and PVC-U) for buildings for resource and energy consumption, non-renewable resource consumption (ADP) of pollution gas emission, greenhouse effect (GWP), acidification effect (AP) and eutrophication (EP) and inhalable inorganics (RI) generated in the process of life cycle from raw material exploitation to produce production and other environmental influence closely related to the national energy conservation and emission reduction policy. The result shows that the influence indexes of non-renewable resource consumption for functional unit of PPR pipe, PE pipe and PVC-U pipe are 2.22×10^-5 Kg antimony eq./ kg, 1.51×10^-5 Kg antimony eq./ kg, 6.82×10^-6 Kg antimony eq./ kg; those of acidification effect are 1.92×10^-2kg SO₂ eq./ kg, 1.96×10^-2g SO₂ eq./ kg, 3.90×10^-2kg SO₂ eq./ kg; those of eutrophication are 2.39×10^-3kg PO4^3-eq./ kg, 2.36×10^-3kg PO4^3-eq./ kg, 3.40×10^-3kg PO4^3-eq./ kg; those of inhalable inorganics are 6.46×10^-3 kg PM2.5 eq./ kg, 6.30×10^-3 kg PM2.5 eq./ kg, 1.91×10^-2 kg PM2.5 eq./ kg; those of greenhouse effect are 3.72kg CO₂ eq./ kg, 3.60kg CO₂ eq./ kg, 7.93kg CO₂ eq./ kg. This result shows that the environmental influence of PPR, PE and PVC-U pipes mainly depends on the raw materials required for producing pipes, so the key of plastic pipeline greening is to reduce the consumption of virgin resin. This investigation creates a database about plastic pipeline's influence on environment within its full life cycle for the purpose of laying a foundation for calculating intrinsic energy in a building, promoting selection of green building material, facilitating the realization of green building objective, and improving the knowledge of developer, constructor and user to potential influence of the pipeline system within its life cycle.

Abstract: The energy consumption due to heat loss from exterior windows plays an important part in that of the whole building. Therefore, the environmental impact of exterior windows couldn’t be neglected. In this study, the energy consumption and environmental impact were quantified and analyzed based on life cycle assessment methodology. The results showed that both energy consumption and environmental impact of aluminum alloy windows and wood-plastic (WPC) windows mainly occurred at the production stage of aluminum alloy profile and flat glass respectively. At the stage of aluminum alloy profile production, the energy consumption and environment impact were 73.06% and 86% of whole life cycle, and for WPC windows they were 32.95% and 48% at the stage of flat glass production. In addition, the energy consumption and comprehensive environmental impact of aluminum alloy windows during the whole life cycle were 1.26 and 4.59 times more than that of WPC windows.

Abstract: In order to determine the optimal parameters of the external insulation system and guide the energy saving and greenhouse gas emission reduction of building, a typical student dormitory building in Beijing was chosen as research object. The life cycle thinking and dynamic simulation method were used in the present investigation. The relationship between the expandable polystyrene (EPS) external insulation system design parameters and building energy consumption and greenhouse gas emission in each phase of materials production phase, operation phase and the whole life cycle was studied, systematically . The results show that the consumption of clay brick, concrete and cement mortar account for 98.1% of the total materials consumption, where concrete contributes most to both energy consumption (36.6%) and greenhouse gas emission (35.9%). Regarding the contribution to energy consumption and greenhouse gas emission for building life cycle, materials production phase accounts for 5.6%-18.8% and building operation phase takes up 80.6%-93.4%. With the increase of EPS insulation thickness, the energy consumption and greenhouse gas emission increase linearly in materials production phase, decrease in building operation phase, and have an optimization value in the building life cycle to reach the minimum when the heat transfer coefficient (K) is 0.3W / (m² • K) equivalent to the EPS insulation thickness is 130mm. Building heating load reduces with the increases of insulation thickness, but the envelope thermal insulation performance has no significant influence on cooling load.