Partially Replacing Fly Ash with Limestone Powder in the Paste - Influence and Characterization
Paste filling is an important research direction of coalmine "green mining" which can dispose coalmines solid waste and achieve environmental protection. The mechanical properties such as compressive strength, workability, ulti- mate tension value, shear strength and splitting strength of paste, in which the fly ash was partially replaced by limestone powder, was studied. Adiabatic temperature rise, setting time, shear strength, permeability, frost resistance and dry shrinkage of different substitution rate were investigated and the results were compared with traditional paste. The test re- sults showed that the influence of limestone powder on workability, permeability and frost resistance performance of paste was slight, the setting time of paste were shortened, adiabatic temperature rise and mechanics performance of paste were decreased, dry shrinkage value was increased with limestone powder content increasing.
Solutions to the problem of waste deposition at a coal-fired power plant.
This paper deals with the impact on the environment of the combined operation of a power plant and a coal mine located in Velenje, Slovenia. The consequences of intensive deep underground mining are the sinking of the surface and the filling up of the emerging hollows with water. As far as the various consequences of coal combustion are concerned, only the harmful effects of the surface deposition of ash and slag are discussed, with the poisoning of the lake and the river water being considered the most harmful. The integrated system of waste treatment at the power plant is presented. The idea of the system is to use the waste materials such as ash, slag, gypsum, contaminated water, etc. as the building materials or to apply them in the process of improving the ash dump and the environment. The system needs to be closed as much as possible, so that the waste cannot influence the surroundings of the dump. The physical and chemical properties of the waste materials from the power plant, the results of ecological measurements and the impact of the ecological damage are presented. In addition, we present: a description of the applied methods; the activities and the technical measures; the obtained results and the difficulties; and the problems that need to be overcome in order to normalise the ecological conditions.
The Prevalence of Dietary Supplement Use among College Students: A Nationwide Survey in Japan
To clarify the prevalence of dietary supplement use among college students, we conducted Internet-based nationwide questionnaire surveys with 157,595 Japanese college students aged between 18 to 24 years old who were registrants of Macromill Inc. (Tokyo, Japan). Among the 9066 respondents (response rate 5.8%), 16.8% were currently using dietary supplements. The prevalence of dietary supplement use did not differ significantly between males (17.1%) and females (16.7%). However, it increased according to their grade (13.1% to 20.5%), and it was higher in medical and pharmaceutical college students (22.0%) compared to others (16.7%). The main purpose of dietary supplement use was for the health benefits in both males and females. Other reasons were to build muscle in males, and as a beauty supplement and for weight loss in females. According to the purpose of dietary supplement use, the most commonly-used dietary supplements were vitamin/mineral supplements in both males and females, then protein and weight loss supplements in males and females, respectively. Although most students obtained information about dietary supplements via the Internet, they typically purchased the supplements from drug stores. Of the students surveyed, 7.5% who were currently using or used to use dietary supplements experienced adverse effects, with no significant difference between genders (8.8% in male, 7.0% in female). In conclusion, the prevalence of dietary supplement use increased with grade among college students in Japan. Some of them experienced adverse effects. Education may be important to prevent adverse effects resulting from supplement use in college.