Powder Technology and Application III

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Authors: Zi Qiao Jin, Xian Jun Lu, Shu Gang Hu
Abstract: In order to stimulate the potential cementitious property of granulated blast furnace slag (GBFS), the ground GBFS sample (Wei Fang Iron and Steel Corporation, China) was activated by lime and gypsum under different dosages. The results showed that lime is an effective activator for the slag, and the optimum dosage of lime is about 10% (w/w) of the slag. At the optimum dosage of lime, the 28 days compressive strength of the lime-slag paste is higher than that of 32.5 ordinary Portland cement (OPC). But, the early age strength (3 and 7 days compressive strength) of the lime-slag paste is lower than that of the OPC. Addition of gypsum can effectively improve the early age strength of the lime-slag paste. At the ratio of gypsum:lime:slag of 8.2:9.2:82.6 (w/w), both the early and long-term compressive strengths of the gypsum-lime-slag paste are higher than that of the OPC. According to XRD, TG-DTA and SEM detections of the hydration products of the lime-slag paste, the gypsum-lime-slag paste and the OPC paste, it reveals that the hydration process of the GBFS-based cementitious material is different from the ordinary Portland cement and the presence of ettringite (AFt) contributes to the early age strength of the pastes. The major hydration product of the OPC paste (<7 days) were measured as ettringite (AFt), but the AFt phase was not detected in the hydration product of the lime-slag paste and the major hydration product of the lime-slag paste was determined as amorphous CSH gel. However, AFt was detected in the hydration products of the gypsum-lime-slag paste in the early stages of hydration, and the formation of AFt is favorable for the early strength improvement of the material.
Authors: Shao Jian Ma, Jin Lin Yang, Gui Fang Wang, Wei Mo, Xiu Juan Su
Abstract: Alkaline leaching is an important way for treating low grade metal oxide ore, which has some advantages such as low corrosion and low pollution compared to acidic leaching. In order to recover the zinc from a low grade complex zinc oxide ore in which the grade of Zn and Fe are 13 wt.% and 40.2 wt.%, respectively, and 52.8% of Zn is contained in siderite, 34.63% in limonite and 11.55% in smithsonite, this paper presents a preliminary investigation of this type of ore by alkaline leaching method. In this study, ammonia-ammonium chloride and ammonia-ammonium carbonate were used as the leaching reagents. The effects of alkaline concentration, leaching time, leaching temperature and liquid to solid ratio (L/S) were studied, respectively. The results show that 43.15% of initial Zn content was extracted adopting ammonia-ammonium chloride as the leaching reagent in 4.5M at 30°C for 3h with a liquid to solid ratio of 4:1, while 43.07% of Zn recovery was achieved employing ammonia-ammonium carbonate as the leaching reagent at 5M, 30°C and 4:1(L/S). The low leaching rate of Zn is probably attributed to that the zinc contained in siderite was not extracted completely because Zn and Fe exist as isomorphism in siderite.
Authors: Yue Xin Han, Li Xia Li, X. Liu, Ning Bo Song, Yu Bin Wang
Abstract: With the purpose that the desulphurized and skimming slag tailings powder from Ansteel replaces part of cement, water requirement of normal consistency, soundness, setting time and strength of cement with desulphurized and skimmed slag tailings was researched respectively in this paper. Results demonstrated that both of the compressive strength and the rupture strength of cement mortar of 3 and 28 concrete age decreased gradually with the amount of tailings increase, and what resulted in strenghth decreased was also investigated, It was shown that suitable amount of tailings to be blended was limited to 30 wt.%.
Authors: Yu Qin Liu, Xian Jun Lu, Jun Qiu
Abstract: The structure and thermal property of organomontmorillonite (OM) were studied by X-ray diffraction (XRD), differential thermal analysis (DTA), and thermalgravimetric analysis (TGA).Based on the thermal property of OM, a new method for quantitative characterization of the alkyl-ammonium adsorbed in the layers was established, and the influence of adsorption amount on the viscosity of OM gel was examined. Changes in the basal spacing of OMs and Na-montmorillonite (Na-mont) indicated that alky-ammonium ions intercalated into the montmorillonite layers. TGA results showed that OM and Na-mont had different thermal property, Na-mont held more free water in the layers. The intercalated alkyl-ammonium in OMs decomposed at the temperature of 230~480°C. Effective dosage (DOSeffective) has significant influence on the viscosity of OM gel. Under the optimal DOSeffective(1.1~1.3CEC), the alkyl-ammonium cations can fully cover the exchangeable site in the layers, then the “card-house” structure formed. Structure of the alkyl-ammonium cations determines the intercalation efficiency, the longer the carbon chain, the higher the intercalation efficiency. The intercalation efficiency has no evident correlativity with the viscosity; however, structure of the alkyl-ammonium cations determines their arrangement in the layers.
Authors: Lei Liu, Yue Xin Han, Zhi Tao Yuan, Li Xia Li, Qi Tan
Abstract: As an ultra-fine crushing equipment, High-pressure Grinding Roller (HPGR) has unique advantages in crushing refractory ores, owing to its high efficiency and low energy consumption. Low-grade hematite ores from Anshan were crushed by a laboratory CLF-25-10 HPGR with different applied load, roll speed and feed moisture. The different operating factors on the fine crushed products characteristics were investigated and the suitable operating parameters were obtained. The results showed that the product became finer and specific grinding energy increased with applied load increasing, while the capacity did not vary obviously. The capacity was proportional to the roll speed, while product finess and specific grinding energy didn’t change significantly. The moisture of feed was beneficial to coarse particles crushing and went against fine particles crushing. Specific grinding energy increased and capacity increased and then decreased with the increase of feed moisture. It was obtained that applied load of 5.2N/mm2, roll speed of 0.18m/s and feed moisture of 5% were suitable to crushing effect. At these conditions, the percent of -0.074mm production was 21.84%, P80 of product was 2.55mm, specific grinding energy was 1.081Kwh/t and capacity was 1.521t/h.
Authors: Qian Qian Hou, Pei Xin Zhang, Ming Fang Zhang, Zheng Wu Lu, Xiang Zhong Ren
Abstract: Compared with traditional lighting, LED has many unparalleled advantages, and is considered to be the most promising green light which may be able to substitute incandescent and fluorescent lamps. The requirement of LED's luminous efficiency grows with its increasingly application in the lighting field. This paper summarizes the development of gaining approaches of Power-type WLED and their respective advantages and disadvantages; analyses several effective programs which can improve luminous efficiency, including changing substrate materials as to enhance the heat-release performance as well as the impact of chip structure design, the packaging materials and technology or other factors; proposes a new LED packaging material- inorganic fluorescent glass, which is expected to simplify the packaging process greatly, at last, there is an expectation of High-power WLED in future application.
Authors: Ye Han, Ming Gu, Wei Wei Zhang, Shu Yu Yao
Abstract: The Fe2O3-CaO-SiO2 glass ceramics were prepared by the method of quenching and controlled crystallisation. Differential thermal analysis, X-ray diffractometry and vibrating sample magnetometer were used to study the crystallisation and magnetic properties of Fe2O3-CaO-SiO2 glass ceramics. It was concluded that the main crystalline phases of glass ceramics during the process were Hematite, Iron Silico Oxide and Hedenbergite. The saturation magnetisation values (Ms) of glass ceramics varied between 108 emu•g-1 and 147 emu•g-1. The crystallisation of Hedenbergite lead to the high Hc value (~2000Oe).
Authors: Peng Wei Jiang, Zhi Jun Ma, Yue Xin Han
Abstract: Humic acid has been extensively used in the fields like industry, agriculture, medicine, environment protection, etc. As a kind of potential organic resources that being developed and utilized, humic acid is drawing more and more attention from the world. China is abundant in coal resource; the lignite of China contains a lot of humic acid. Extraction humic acid from lignite creates favorable conditions for the development of coal industry and agriculture industry, has broad utilization prospect. By combining the method of nitric acid preoxidation and the method of alkali solution and acid eduction, the humic acid was extracted from the lignite. The orthogonal experimental method and FTIR were integrated in this study. The influences of nitrate concentrations, acid-coal proportion, oxidized temperature, oxidation time, extraction liquid concentration, liquid-solid ratio, extraction temperature and extraction time etc. on the process of extracting humic acid were examined. The results indicate the optimal processing condition can achieved when using sodium pyrophosphate and sodium hydroxide solution as the extraction agents, the rate of humic acid production can reach to 39.25%. And the total content of humic acid production can reach to 46.14%.
Authors: Na Li, Zhi Jun Ma, Yi Min Zhu
Abstract: Due to lignite is a kind of coal with low degree of coalification, low heat value, high moisture content, and prone to weathering and spontaneous combustion, it is not easy for long distance transport. The briquette technology is an effective way to resolve this question. In this study, the lignite from Huolinhe Coalmine was taken as the raw material. By drying it and adding agglomerant into it and letting it go through the physiochemical process, a lignite briquette with improved heat value and some strength was produced, which solved the problems like heat value reduction and the environmental pollution caused by weathering during the lignite transport process, and increased the economic and social benefit of lignite utilization. This study used the agglomerant cold-press molding technique to prepare the briquette, the obtained briquette went through the tests of ash content, heat value, compressive strength, surface behavior etc., and the test results then were analyzed. Meanwhile, this article discussed the acting force types of the particles inside briquette and influencing factors of lignite molding from the point of agglomerating mechanism. The optimal agglomerant type and blending ratio of the agglomerant was determined, which will provide basic consideration for the industrial production of the briquette.

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