Search

High-volume fly ash (FA) cement presented a slow setting and lower early compressive strength, restricting the utilization in cemented paste backfill (CPB). The present work investigated the feasibility of using metakaolin with various particle sizes and content to modify the properties of FA cement. Reaction kinetics, rheological properties, setting time, compressive strength, hydration products, and the CPB samples' microstructure were thoroughly studied. The results showed that 5 wt% of super-fine metakaolin (SMK) could strongly promote the binder hydration, leading to the formation of a more compact matrix with higher early compressive strength. The 3 d-compressive strength of the CPB samples was increased by around 216% after replaced by 5 wt% of SMK. Besides, the binder doped with 5 wt% SMK showed better environmental and cost performance.

To improve the properties of cemented ultra-fine tailings backfill (CUTB), the authors intend to outline the framework of the effect of steel slag (SS) on the properties of CUTB. Therefore, flowability, unconfined compressive strength (UCS), hydration products, and pore structure were used to investigate the properties of CUTB samples. The results showed that the incorporation of SS increased the flow spread by increasing the water film thickness (WFT). Unconfined compressive strength (UCS) was observed to be enhanced when the content of SS did not exceed 20 wt%. Hydration phase evolution tested by X-ray diffraction, thermogravimetry, and thermodynamic modeling indicated the additional formation of hydrotalcite-like phases (Ht). This contributed to a denser microstructure. Besides, lower total porosity and critical pore diameter (dcr) obtained by mercury intrusion porosimeter tests were observed in samples with SS addition, which could favor the strength development. On the other hand, toxicity characteristic leaching procedure (TCLP) results indicated that the CUTB exhibited good environmental performance.

Accurate road information is crucial for the effective planning and management of open-pit mines. However, the parameters related to the roads in open-pit mines change constantly, and their shapes are often complicated. These factors indicate the difficulties in updating road information in open-pit mines. This study reports a method for updating the road information in open-pit mines using the trajectories of trucks. The method employs an algorithm for compressing trajectory data, an algorithm for extracting new roads, and an algorithm for old-road classification. Data from the Fushun open-pit mine is used to validate this method, and our experiments show that it can identify more than 90% of new roads and the majority of disappearing roads. In addition, we analyze several factors affecting the results obtained using this approach and provide a detailed description of the limitations of this method. Overall, our findings indicate that this is a promising approach to road-information retrieval.

Within the framework of the U(3) chiral perturbation theory, we revisit the masses, decay constants, and the mixing parameters of the light pseudoscalar mesons π, K, η, and η′. The low energy constants up to next-to-next-to-leading order are determined by including the light-quark mass dependences of the various quantities from different lattice QCD simulations and relevant phenomenological inputs. Then we study the finite-temperature behaviors of the masses of the light pseudoscalar mesons. The thermal behaviors of the η−η′ mixing angles in singlet-octet and quark-flavor bases are also explored. While the masses of the π, K, and η are increased when increasing the temperatures, the mass of the η′ turns out to be slightly decreased in the low-temperature region.

This paper presents the detailed results and analyses on the ecological footprints and bio-capacities of the individual cities and the province as a whole for the year 2001, providing a clear picture of sustainability for the province. Results show that the ecological footprints of most cities in Liaoning exceeded their respective bio-capacities, incurring high ecological deficits. The ecological deficit of the province as a whole was 1.31 ha/cap. Those cities with resources extraction and/or primary material-making as their major industries constitute the “ecologically black band”, whose ecological deficits ranged from 2.45 to 5.23 ha/cap, the highest of all cities in the province. Fossil energy consumption was the major source of footprint amounting to 1.63 ha/cap at the provincial level, taking up 67.3% of the total. For cropland, modest ecological surpluses occurred in Jinzhou, Tieling, Huludao, and Panjin while modest ecological deficits in Dalian, Benxi, Fushun, and Dandong, resulting in an overall surplus for the province. Liaoning had a certain level of surplus in fishing ground (water area), mainly distributed in the coastal cities of Dalian, Panjin, Huludao, Yingkou, Jinzhou, and Dandong. Most cities had a small ecological deficit in pasture and all had a small ecological surplus in forest. The eco-efficiency, expressed as GDP value per hectare of footprint, exhibits high variations among the cities, with the highest (Shenyang) more than 10 times the lowest (Fuxin). Cities with manufacture, high-tech, and better developed service industries had high eco-efficiency, while those with resources extraction, primary material-making, and less developed service industries had low eco-efficiency. Based on the components and geographical distribution of ecological footprint, strategic policy implications are outlined for Liaoning’s development toward a sustainable future.

Based on ecological footprint and material flow analysis indicators, a model has been developed to reflect the aggregate environmental pressure and the carrying capacity of a regional economy. The model was applied to calculate the environmental pressure and carrying capacity of Shenyang in the period of 1991–2005. Results show that, of the total ecological footprint of Shenyang, 66%–80% came from carbon footprint and 20%–34% from direct footprint. The carbon footprint increased rapidly after 2000 at an average annual rate of 15.2%, higher than the GDP growth rate (13.76%) in the same period. Therefore, the principal issue of Shenyang's environmental pressure is carbon emission. The direct ecological overload increased steadily at an average annual rate of 6.3%, while the carbon overload increased rapidly after 1998 at an average annual rate of 20.8%, reached 15 million global hectares in 2005. This indicates that there exists a huge gap between the carbon absorption capacity and carbon emission in Shenyang and it is rapidly enlarging.