Applied Mechanics and Materials Vols. 675-677

Abstract: The feasibility of pulp and paper mill wastewater sludge as substrates for biogas production was evaluated in labrotory scale. Also the influence of pre-acidification, feeding modes and sludge concentration on anaerobic digestion system were studied.

Abstract: The internal structure and the working principle of gravity oil-water separator used for self-circulation well-flushing equipment were introduced. Based on CFD, the flow field was calculated and analyzed with different quantities of horizontal deflectors and inclined deflectors in the separator. According to velocity vector diagrams and oil drop trajectory diagrams with different number of horizontal deflectors and inclined deflectors, the influence rules on separation efficiency were analyzed. The results show that the separation efficiency is improved gradually with the amount of horizontal deflectors increased, and the optimal value of separation efficiency is 3 inclined deflectors.

Abstract: Utilization of the waste toner in wasted print cartridge was beneficial to the environmental protection and resource recycling. Fe₃O₄ has been obtained from the waste toner via magnetic separation and heat-treatment in present study. XRD measurement revealed the recuperated sample has ferriferrous oxide structure without other crystalline impurity. The electrochemical performances of recuperated Fe₃O₄, as the electrode active material for supercapacitor, was conducted by cyclic voltammetry and charge-discharge process. The results showed that the specific capacitance of Fe₃O₄ achieved 76.5 F/g under 50 mA/g current density, which possessed typical capacitive behaviors and good cycling stabilities. Based on the preferable electrochemical performances, Fe₃O₄ recovered from waste toner may be a potential alternative as electrode material for supercapacitor.

Abstract: A novel and improved waste pyrolysis test system is developed by process design, pyrolysis host type design and the corresponding counterpart type design. It contains the design of waste pyrolysis pretreatment device, the sealing feeding device, the pyrolysis slag cooling device, the high temperature pyrolysis gas dust removal device and the pyrolysis gas desulfurization dust removal device. This study proposes a good testing model and a production validation on waste combustion under the oxygen-free and high-temperature condition. Thus it offers an effective technical support and guidance on improving the utilization of waste calorific value and preventing the generation of dioxin.

Abstract: Recycling of metallic fractions from waste printed circuit boards (PCBs) using gravity separation and hydrometallurgy was investigated. The obtained research fruits were listed as follows: (1) When being pulverized to finer than 0.4mm, waste PCBs could be generally dissociated from plastics. (2) Shaking table was shown to be suitable for processing pulverized PCBs. Pulverized PCBs containing 6.97% copper was enriched to 33.55% in a single operation and the copper recovery was 90.3% in the best size range of separation. (3) Pressure oxidation leaching was shown to be effective for separating copper from aluminum and tin. The leaching extraction of aluminum and tin were 86.6% and 96.3%, copper extraction was 1% or less under the optimal conditions.

Abstract: In this work, the traditional two-stage hydrometallurgy leaching process and the neutralization-flocculation leaching process were used for treating the dust, produced in steelmaking process. The results of the comparison of two processes show that traditional techniques could produce the accumulation of silicone gel generated by cycles which hampers the followed filtration process seriously. These situations make it unable to meet the production requirements. By contrast, the filtration process was fast after the acidic leaching when considering the neutralization-flocculation process. Furthermore, leaching solution processing performed better while adding iron and charcoal for improving the effect of the treatment processes. The results showed that zinc leaching rate was above 93%, and desilication rate was above 99%. Meanwhile, filtration rate of the iron-silicon residue was as fast as 4.7 m³ .m^-2 .h^-1.

Abstract: Chicken feather have many excellent properties, unfortunately, the dark color affects its wide applications. In this study, the three stage bleaching process was used to bleach the dark chicken feather. The effects of the key chemicals on bleaching properties were discussed, and the change of the fine hair whiteness and strength before and after bleaching were investigated. It provides a sound theoretical basis for people understanding and studying the bleaching properties of chicken feather.

Abstract: The aim of this paper is to investigate FGD gypsum quality from coal-fired power plants and its comprehensive utilization. FGD gypsum comprehensive utilization technologies mainly include employed in the wallboard manufacture, as cement retarders, as a construction material for roads and as a soil ameliorant. In China, FGD gypsum is mainly utilized to produce wallboard and as cement retarders. FGD gypsum comprehensive utilization technical route was proposed based on FGD gypsum produce, storage, transport and comprehensive utilization. In order to ensure FGD gypsum quality so that it can be well utilized, the following requirements should be satisfied: for FGD gypsum, moisture content (wet basis) should be no more than 10%; CaSO₄·2H₂O content should be no less than 90%; CaSO₄·1/2H₂O content should be no more than 0.5%; pH should be controlled between 5 and 9; Cl^- content (dry basis) should be no more than 200 mg/kg.

Abstract: Pharmaceutical wastewater was treated by coupling of micro-electrolysis-catalytic oxidation, using porous multicomponent alloys as packing. Influence of initial pH of wastewater, micro electrolysis time, packing ration, H₂O₂ dosage and catalytic oxidation time on removal rate of COD in wastewater was studied. The optimal process condition for treatment of pharmaceutical wastewater by coupling of micro-electrolysis-catalytic oxidation is as follows: initial pH 2.5, micro electrolysis time 90 min, packing ration 1:1, and dosage of H₂O₂ 2 ‰, catalytic oxidation time 120min and oxygen aeration. Under the optimal process condition, the average removal of COD is 52.5%, and the average mass concentration of COD is 276 mg/L.

Abstract: Synthesis of pure-form zeolite 13X was investigated using the alkali fusion-hydrothermal method to dissolve Si and Al sources from fly ash, and with the addition of Si source, to prepare initial gel. Experimental results demonstrated, the regular morphology and homogeneous composition are in good agreement with standard zeolite 13X by characterization of XRD, SEM and IR. The properties of adsorption and CEC values were evaluated by BET and UV-spectrophotometry, respectively. All properties are much better than commercial zeolite 13X. Our results further revealed that like coal fly ash after alkali fusion pretreatment can be used for zeolite synthesis. Thus, It demonstrates a promising feedstock for the green synthesis of zeolites directly without experiencing intermediate chemicals.