Bo Xue Sun

Exergy-Based Model of the Depletion of Mineral Resources

The primary problem of eco-materials is how to judge whether a material is environmentally friendly or not, and the method of life cycle assessment is usually used to evaluate it. The depletion of mineral resources is a very important indicator of LCA, but its characterization is still filled with dispute. At present, the most commonly used method is CML, which is put forward by Leiden University, and its core idea is that using the ratio of exploitation amount and reserves of mineral resources as the degree of scarcity. Although being accepted by most of the scholars at work on LCA, CML doesn’t grasp the essence of the depletion of mineral resources. Recently, a new assessment method, injecting new ideas to the conventional life cycle assessment, combines exergy with LCA is arising, which can be used to solve some specific problems of LCA especially the depletion of mineral resources. In this paper, two results of elements’ exergy calculated by Rivero and Szargut respectively are compared, and the exergy of some natural minerals, which can be used in LCA and other minerals-related research, is calculated based on the data of Chinese mineral resources.

Analysis on the CO2 Emission of Calcium Carbide Sludge as Secondary Raw Material in Cement Clinker Production

With the development of economy, China has become one of the largest cement producers in the world. However, cement industry is a main contributor of global carbon emissions. Substituting calcium carbide sludge for limestone is an effective method for CO2 emission reduction in cement industry and has developed rapidly in recent years in China. The purpose of this study is to determine the life cycle CO2 emission of cement clinker produced with calcium carbide sludge as secondary raw material. The results show that compared with general cement clinker, the life cycle CO2 emission intensity of cement clinker produced with calcium carbide sludge will be decreased by 39.1% when substitution rate is 80%. And the CO2 emission results from the procedure of cement clinker production accounts for 85.7% of the total emission, in this stage, the CO2 emission declined by 42.2%.

Life Cycle Assessment of Heavy-Duty Truck for Highway Transport in China

The detailed life cycle assessment of heavy-duty truck for highway transport in China is conducted by Centre of National Material Life Cycle Assessment (CNMLCA). The input of energy and output of pollutants emissions are documented as the life cycle inventory (LCI). The life cycle impact assessment (LCIA) results calculated with the CML method show that the hotspot of environmental impacts from transport in China. The environmental benefits from implementations of European emissions standards in China for transport are also analyzed. The analysis shows that the acidification potential (AP) makes the most huge contribution to total environmental impact, up to 33.7%. As the second hotsopt, global warming potential (GWP) takes up 26.83% of total environmental impact. Photochemical oxidant formation potential (POCP) takes up 23.42% of total environmental impact, which is more or less the same comparing with the result of GWP. Eutrophication potential (EP) takes up 15.05% of total environmental impact. The last but not the least environmental impact category - human toxicity potential (HTP), only takes up 0.95% of total environmental impact. If the heavy metal and dioxin emissions are also considered, maybe the results will be changed and the HTP will take more in the whole environmental impact. It can be concluded that if we pay more attention on SO2 emissions especially NOx emissions reduction, the acidification and photochemical smog would be relieved a lot and the total environmental impact can be decreased a lot. More punishment on overload may be a good choice to reduce environmental load of heavy truck of highway transport in China.

Materials Flow Analysis of Metallic Titanium in China

The materials flow quantity, direction, structure and characteristics of metallic titanium resources in China were illustrated by the Stocks and Flows (STAF) model with time series. The indices such as the metallic titanium resource efficiency, the import-export, the consumption and the social stocks were calculated. From the point of view of the overall resources flow, China titanium industry has entered a stable growth period from the development and expanding period during the recent decade. The resources self-support rate of metallic titanium production and manufacturing increased from 44% and 60% to 66% and 78%, respectively. The titanium ore grade is the main factor affecting the utilization efficiency of titanium element. Considering the titanium utilization rate were increased by 1%, the ore consumption of titanium sponge production would be reduced by 57.8kg/t. The production and consumption ratio of metallic titanium products was increased by 57%, which showed the trend from short supply to self-sufficiency and gaining the net exports of Chinese metallic titanium products. However it appears to the trend of surplus production capacity presently, and the high quality products still rely on import. The recycling of metallic titanium wastes is mainly from the manufacturing process, of which the recovery rate is still lower in the use stage. It is expected that China will face the peak of metallic titanium scraps in 2033 by calculating the amount of social stocks of metallic titanium resources.

Environment Impact Analysis of Four Different Cement Production Strategies

With development of the economic, China has been the largest cement production country in the world. But the big production of cement also causes serious ecological environmental problems. In this study, a cradle-to-gate life cycle assessment was carried out for four typical cement factories in China. The results indicated that new suspension preheater (NSP) process and power plant were mainly to blame for most emissions and environmental performances, and GWP is the most prominent category in the accumulative environmental performance of cement production. Any of the strategies for cleaner production of cement considered in this study, including larger production scale, cogeneration and using calcium carbide slag as secondary material, has effect in improving the environmental performance, but the final single result show that the utilization of calcium carbide slag is the best method, and it could reduce the environmental impact obviously.

Substance Flow Analysis of Rare Earth Lanthanum in China

Substance flow analysis (SFA) is an established method to analyze the structure and characterization of resource flows or substance flows. Lanthanum (La) is an important type of light rare earth element, which is widely used in the fields of glass, luminescence, catalyst, agriculture, etc. This paper conducts a static SFA for lanthanum in China in 2002 and 2011, including different life cycle stages, e.g., exploitation, concentration, smelting, manufacture, use and disposal. Mining utilization efficiency, smelting ratio, export rate, ratio of scrap to raw material in 2002 and 2011 were comparatively analyzed. The results indicated that the utilization efficiency of La in the production stage of rare earth concentrates increased in 2011 relative to the value in 2002 by 80%, and the utilization efficiency of La in the manufacturing stage increased by 74%. The results also showed that although the mining utilization rate was increased, the resource efficiency was still low and how to increase the resource efficiency is a significant issue for Chinese rare earth industry. On the based of the results, some advices were also proposed, which will provide useful reference information for the green development of Chinese rare earth industry.

Exergy-Based Resource Intensity Analysis of Primary Nickel Production in China

The resource intensity of primary nickel production in China was analyzed by the indicator of exergy, which can provide a unified picture about the overall processes involved in the life cycle of nickel. The results show that primary nickel’s CExD value is 235GJex/t, and the largest contributor to the CExD is electricity (46%), followed by fuels (31%), mineral (16%), and land resource (7%); the considerable proportion natural mineral and land resource account for in the result is due to the high exergy value of sulphide minerals and the low grade of natural nickel ore. The results also show that the calculation of this study is sensitive to the choice of allocation basis (mass and market value); however, market value is not recommended in this study since that nickel’s price varies greatly over time.

A Life Cycle Inventory Case Study for Marble Mining in China

The goal of this paper is to conduct a life cycle inventory (LCI) case study for marble mining in China. The scope focuses on the whole life of marble mining. The functional unit is “per cubic meter of marble block”. The LCI data, including the input of energy and natural resources and the output of pollutant emissions, were collected on-site. The LCI results show that if the waste quarries could be recovered after the exploration, the environmental damages from the marble decorative materials would be much less. The environmental impacts of fresh water consumptions are also discussed. Some suggestions and recommendations on how to improve the environmental performance, at the same time the marble materials can be produced to support the increasing sales, are made. In the future, the land use and the mine recovery should be discussed.

Calculating Chinese Human Toxicity Potential Factors of Heavy Metals in Water for Material Industry

With the development of materials industry, the problem of water pollution is increasingly serious, and therefore it is important to establish an appropriate characterization model of heavy metals in water in China. This paper provides the human toxicity potential factors of several heavy metals, including Hg, Cd, Cr, Pb and As. The result showed that Chinas HTP factors are partial greater than Europe factors, caused by the different industrial situation and the ratio of total human intake to total emissions.

Analysis on Life Cycle CO2 Emission of Aerated Concrete Production in China

Aerated concrete is a new type of wall material with beneficial features like light weight, heat insulation, fire prevention and low energy consumption. As a key milestone in wall materials innovation and energy-saving of building system, it has been proven to be an ideal wall material which can replace traditional clay brick through years of application and practice. This study calculated the CO2 emissions in all the stages of life cycle of aerated concrete production. Compared with clay brick, the life cycle CO2 intensity of aerated concrete block will be decreased by 67.4% with the same insulation effect. Study on the environmental loads of aerated concrete industry will provide theoretical base for the carry out of energy-saving and emission reduction, the formulation of clean production and the development of recycling economy.