Advanced Materials Research Vol. 878

Abstract: Removal of phenols from waters and wastewaters is an important issue in order to protect public health and environment. In an effort to develop an effective adsorbent for removal of phenol from aqueous solutions, fly ash cenospheres (FACs), the solid wastes generated from a coal-firing power plant, were modified with an amino-terminated organosilicon (γ-aminopropyltriethoxysilane, KH550). Surface properties of the KH550-modified FACs (M-FACs) were characterized by the X-ray diffraction (XRD), the scanning electron microscopy (SEM) and X-ray photoelectron spectra (XPS). The characterized results showed that KH550 was successfully grated on the surface of FACs. The effects of various experimental parameters such as solution pH, adsorbent dose, and temperature upon the phenol adsorption onto M-FACs were evaluated. The results showed solution pH had a major impact on the phenol adsorption onto M-FACs, the optimum phenol removal was observed around pH 7-9. The kinetic studies indicated that the adsorption process was best described by the pseudo-second-order kinetics, suggesting that the mainly phenol adsorption process was predominantly controlled by chemical process. M-FACs presented more than double adsorptive capacity as compared with FACs. The adsorption capacity of the regenerated adsorbents could still be maintained at 83% by the fourth adsorption-desorption cycle.

Abstract: In this paper, the mineral processing experimental study on the flotation tailings which are stored in the tailings pond of a copper-molybdenum mine is conducted, with a large content of slimes and kaolinite in the tailings and the fine particle sizes and poor locked particles of most of valuable minerals disseminated in the gangue minerals taken into consideration. Based on the mineralogical characteristics of the ore, a combined process is adopted in order to recover copper, molybdenum, sulfur and iron minerals from the ore, this process contains a series of steps in a particular sequence, which are pre-desliming of the ore, bulk flotation of copper and molybdenum of the coarse fraction, separation of Cu-Mo, separating sulfur from bulk flotation tailings and low-intensity magnetic separation of iron from sulfur flotation tailings. The results of the closed circuit test show that it can be obtained copper concentrate with a Cu grade of 20.61% and a recovery rate of 28.52%, molybdenum concentrate with a Mo grade of 36.00% (containing 20% C) and a recovery rate of 43.35%, sulfur concentrate with a S grade of 35.66% and a recovery rate of 42.58%, and iron concentrate with a Fe grade of 68.40% and a recovery rate of 6.85% (75% of phase recovery of magnetite).

Abstract: Steelmaking slag mineral carbonation is a possible technology for the reduction of carbon dioxide (CO₂) emissions to the atmosphere, which has been studied both in aqueous and dilute alkali medium. A set of variables, the stirring speed, reaction time, alkali to slag ratio and reaction temperature, were systematically investigated. The results indicated that reaction time, alkali to slag ratio and reaction temperature were the major factors for CO₂ mineral sequestration. Under the optimal conditions with the alkali to slag ratio of 4 % at 80 °C, 16.64 g CO₂ can be sequestrated in per 100g steel slag and both calcite and aragonite were generated. This work would be of significance to understand the reaction mechanism deeply and provide valuable information for further study in this field.

Abstract: Iron recovery from a lead slag in Henan province was carried out with the technique of coal-based direct reduction followed by magnetic separation. Scanning electron microscopy (SEM) was used to investigate the transformation of iron-containing minerals and the particle size of metallic iron generated by coal reduction. The results showed that technique is feasible for iron recovery from the lead slag. Under the conditions of weight ratio of slag: coal: CaO as 50:15:5, the roasted temperature of 1250 °C for 45 min, and then two stage of grinding and twice magnetic separation, the metallic iron powder was obtained with the iron grade of 92.85% and iron recovery of 92.85%. The iron-containing minerals in the forms of hercynite, fayalite and maghemite were mianly transformed into metallic iron and the particle size of metallic iron was more than 50μm. Therefore, the metallic iron in roasted product can be dissociated by coarse grinding and further was separated by magnetic separation to recover the metallic iron.

Abstract: The objective of paper is to optimize the variables of the sintering process with the six sigma philosophy. The impact of sintering temperature, Ca ratio, Na ratio and reaction time on the alumina reaching rate were primarily studied. In the research, a novel method was adopted to efficiently recover alumina and silica from high-alumina fly ash, and the response surface methodology of six sigma approach was also implemented to analysis the results obtained by the experiments. There is great significance to optimize sintering process for the industrialization of the novel method. Amount of energy consumption will be reduced in the production.

Abstract: The activated carbons (ACs) were prepared by furfural residues with the activation of water vapor. The optimum condition of preparation was investigated by orthogonal experiment. The influences of carbonization temperature and time, activation temperature and time, quantity of steam on the adsorption behavior of the ACs were investigated. The experimental response varied between: 24.7-38.7% for the total yield, 29-162mg/g for the adsorption of methylene blue (AMB), 495.2-904.7 mg/g for the adsorption of iodine (AI), 113.9-524m²/g for the surface areas calculates by Brunauer-Emmett-Teller (S_BET). The optimal activated carbon is obtained when using 600°C as carbonization temperature, 900°C as activation temperature and 25min as carbonization and activation time. The results indicated that under optimum conditions the methylene blue of AC was 163mg/g, the iodine of AC was 904.7mg/g, the surface areas (S_BET) of AC was 524m²/g, and the Yield of AC was 30.6%.

Abstract: Container houses have exhibited huge advantages in such aspects as building efficiency, environmental protection and sustainability. This article begins with the present situation of the transformation and application of the waste containers. Then it discusses the characteristics of the containers and provides certain references for the future transformation design of the containers through a case study of the waste containers transformation design flow.

Abstract: Heavy metals are one of the important factors that need to be considering for the disposal of sludge incineration ash. Vitrification by melting has been identified as a potentially effective tool that can solidify the heavy metals into the glass matrix structure. In this paper, the characteristics of heavy metals in sludge incineration ash (SIA) were studied by using Community Bureau of Reference (BCR) sequential extraction procedure. Fractions extracted by the BCR sequential procedure were acid soluble/exchangeable, reducible, oxidizable and residual fraction, respectively. The total contents of Cu were the highest, followed by then Zn, Cr and Ni, and the content of Pb was the least. The effects of basicity (CaO/SiO₂) on the solidification efficiency of heavy metals and the leaching toxicity of obtained molten slag were investigated. The molten slags demonstrated strong capacity on the stabilization/ solidification of heavy metals. With the basicity value increasing from 0.4 to 0.8, the solidification efficiency of Cu, Zn, Pb and Ni decreased first and then increased, while that of Cr decreased straightly. The heavy metal leaching test results of the molten slags were far lower than the limits required by the regulatory standard of EPA, confirming the possibility of engineering and construction applications.

Abstract: With the enlarging of industrial desulfurization, the amount of FGD gypsum is increasing rapidly. The preparation of alpha-calcium sulfate hemihydrate (α-HH) is one of the biggest concerns for FGD gypsum reclamation. The influence of mixed chlorate solution of Mg-Ca-Na concentrations (5-30 wt%) and FGD gypsum concentrations (5-30 wt%) by hydrothermal salt solution method at atmospheric were investigated at temperatures (75-99^°C) within a reaction time of 4h and a pH value of neutral. The results showed that 20 wt%, 20 wt% and 97^°C was respectively optimal parameter of salt media concentration, FGD gypsum concentration and temperature. Products obtained from the dehydration process of optional experimental conditions with mixed crystal modifier were characterized based on relevant standards in this study. The results showed that α-HH had integrity crystal structure, 2h flexural strength and oven dry compressive strength were 5.34MPa and 30.21MPa, which had meet the industry standards of α30 grade.

Abstract: It is suggested that industrial solid waste has a wide variety of types. It has complex composition and huge amount, which is proved to be one of the main sources of environment contamination. The damage degree to the environment of industrial solid waste is as dangerous as water pollution and atmospheric pollution. Based on the severe circumstance of industrial solid waste in a worldwide range, this article aimed to describes the definition, classification and the status of disposal, comprehensive utilization and discharge of industrial solid waste in China. And from the view of engineering, puts forward some countermeasures for industrial solid waste disposal - one-stop harmless disposal technology.