Materials Science Forum Vol. 814

Abstract: Urban population has been increased rapidly and caused such urban problems as shortage of housing and traffic jam, and the continuously expanding buildings have resulted in strong impact on global resource consumption and environmental pollution. Green building materials are the basic guarantee to the quality and service life of buildings, the material carrier to realize various functions of buildings and also the foundation and support to develop green buildings. Based on the coherence and relevance of assessment on full life cycle of buildings and building materials, the influence of exterior window selection on carbon emission of buildings was analyzed in aspects of the initial stage (production, consumption and transport of building materials) of carbon emission of buildings, i.e. the intrinsic energy per unit product, operation, demolition and treatment. The comprehensive assessment was also established, and the selection of green building materials was investigated for exterior windows based on the reduction of energy consumption during full life cycle of buildings by combining such indicators as the usability, durability, fireproofness, environmental protection and functionality of exterior windows. It solved the puzzles of architects on selection of building materials and the puzzles of building material manufacturers on demand of green buildings. The selection of green building materials on green buildings was promoted and the realization of the goal of "green buildings" also assisted.

Abstract: The energy saving of temporary buildings used heat-reflective coatings in cold region has been paid growing attention. Surface temperature and energy consumption were calculated by the temporary office building and factory building in Beijing. The buildings are color steel plate structure in this paper. The roofs and exterior walls of buildings were painted with heat-reflective coatings. The general solar reflectivity of roofs and exterior walls were about 26% and 22%; after the application of heat-reflective coatings the reflectivity increased to about 84% and 72%. Results demonstrated that the roofs have the best cooling effect, with the average surface cooling reaching 23.32°C in summer. The estimated energy savings of roof was about 9.95Wh/m² per day and the energy consumption reducing rate was up to 67.7% in summer. Considering the energy consumption increased in winter, heat-reflective coatings were only strongly advised to paint on roofs in cold region.

Abstract: Mateial selection technology for green building is an important support of green building development. Aiming at the realization of green building energy conservation, the green building material selection evaluation model was proposed integrating double elements - energy contained in a unit product of building material and energy saveing brought to the building operation in the service process of building material. Taking three categories of thermal insulation materials - polyphenyl board, rock wool board and polyurethane rigid foam board as examples, the relative relationship was calculated and analyzed between energy contained in a unit product of three categories of thermal insulation materials and energy saving in building operation brought by them respectively, and finally a conclusion draws from that: based on building energy conservation, polyphenyl board is a suitable product to realize green building material selection.

Abstract: With the development of science and technology and industry level, solid wastes are fully utilized. Among which gangue is the solid waste generated in the process of coal mining, its comprehensive utilization rate is more than 60%. Environmental pollution in the process of coal mining is one of the typical environmental problems confronted in China. In this paper, the life cycle inventory (LCI) of gangue was acquired by the method of life cycle assessment and further environmental impact assessment was achieved as well. The results showed that environmental impacts based on allocation of calorific value were greater than that of economic value, and it’s about 3.68 times the impacts assigned by economic value. Therefore allocation of economic value was better.

Abstract: Substance flow analysis (SFA) of cobalt in China was carried out to analyze cobalt flows and stocks by using static SFA. Cobalt can be widely used in industry due to its high-melting point, high-strength, and well magnetism. In this static model, the relationship among inflows, outflows and stocks throughout the whole cobalt life-cycle in China were identified. According to the static model, the amount was calculated in the form of cobalt metal, in 2012, 29784t of cobalt was produced, and 30700t of cobalt was imported, 9400t exported and domestic consumption was 31700t, 9000t stocks of cobalt was consumed and 3000t old scrap was recycled in China. The ore index and recovery scrap resource of cobalt industry were 0.318 t/t and 0.136 t/t respectively.

Abstract: Using the sludge of sewage treatment plant to calcine cement clinker is a new method and is confirmed on the international to utilize city sludge recycling and harmlessly. In this work the test of the raw material burnability, cement clinker mineral composition and petrographic analysis were used to study microscopic characteristics of clinker, to analysis of the effect of sludge performance of cement clinker calcination. It was found that when sludge were as a raw material for calcining cement clinker, best city sludge content was around 15% ~ 20%. With an improvement of lime saturation coefficient, the burnability of raw material declined. The mineral composition of sludge clinker was the same as that of the conventional Portland clinker, while mineral structure and morphology of the sludge clinker were better.

Abstract: Spherical calcium carbonate (CaCO₃) is a potential component in many industrial fields such as high-grade papermaking, high-grade painting, environment, and pesticide. This paper describes a novel approach to synthesize spherical calcium carbonate (CaCO₃) particles via passing CO₂ bubbles into phosphogypsum salt leaching solution (CaSO₄) in the presence of ammonia (NH₃) at different temperatures. The influence of the initial solution pH and concentration of calcium ions on the polymorph and morphology of CaCO₃ was studied. The physical characteristics of the precipitate were evaluated using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results showed that compared with different calcium sources the phase and morphology of CaCO₃ synthesized by phosphogysum leaching solution had some regularity. The grain size of spherical CaCO₃ became bigger, surface became smoother, and particle dispersion became better with the increase of calcium ion concentration. The content of vaterite increased and particle grain size changed a little with the increase of pH. The research results had important environmental significance for phosphogysum resource utilization and CO₂ fixation.

Abstract: With the rapid development of industry in China, China has become the largest producer of refined copper as well as the largest consumer of copper in the world. In order to provide the support for decreasing the environmental impact of the copper pyrometallurgy of China, the life cycle assessment methodology was carried out in this study to identify and analyze the typical processes’ environmental load of refined copper production from ‘cradle-to-gate’ perspective. The results showed that the most serious environmental impact of copper pyrometallurgy was abiotic depletion potential and human toxicity. The abiotic depletion potential mainly comes from the copper ore mining, for this reason, increasing the use of renewable copper is an effective means to alleviate environmental load of our country copper pyrometallurgy industry. Meanwhile, reducing the direct and indirect discharge of poisonous and harmful elements (e.g. heavy metals) from the copper ore mining stage and the copper smelting process could decrease the human health damage efficiently.

Abstract: When steel slag, a by-product of steel making in impurity catching process, is added, the forming process of cement clinker and the major reactions in that process are changed. Since there are dramatic differences between the chemical components and mineral compositions of steel slag and that of natural cement raw materials, the empirical equation for the calculating forming heats of cement clinker made of limestone and clay is no longer applied for those made of steel slag. In this paper, the empirical equation for forming heat calculation of steel slag added cement clinker was promoted, and testified by acid dissolution experiments. Results showed that the change of raw materials had great influence on the forming heat of cement clinker. When the traditional raw materials were replaced with steel slag, the forming heat of cement clinker reduced. Calculating the forming heat by our revised empirical equation can help reduce errors and bring great convenience for the calculation and evaluation of heat efficiency. This research provides theoretical underpinning for the study and calculation of forming heat of steel slag added cement clinker.

Abstract: A porous SiC ceramic reinforced copper-matrix composite was fabricated by spontaneous infiltration of molten Cu-24at%Si alloy into the reinforcement. The influence of process parameters on the infiltration behavior and microstructure of the as-prepared SiC/Cu composite investigations showed that infiltration temperature had an important influence on the infiltration behavior, and higher infiltration temperature which decreased the viscosity of molten Cu-24Si was beneficial to the penetration. Besides, the degree of infiltration increased with the increase of dwelling time at 1600°C. SiC particles were bonded together by sintering additives to form the porous reinforcement, which can be maintained after spontaneous infiltration. The interfacial bond between SiC and Cu-24Si alloy was tight, and no obvious interfacial reaction layer was observed in the as-prepared composite.