Authors: Xiao Duo Ou, Jian Wei Yang, Xian Tai Yin, You Fang Liao

Abstract: Four PVC pipes with the length of 1500 millimeters and inner diameter of 160 millimeters were used to make a consolidation device with a drainage system at the bottom, in order to make a study on the relationship between surface sedimentation and water discharge with time at different heights (the heights were adopted as 150 millimeters, 250 millimeters, 300 millimeters, 350 millimeters respectively) of red mud tailings of Pingguo Aluminum. A test was conducted on the mud discharge of the first layer and second layer respectively. It is shown that when the red mud is discharged at the first layer and the second layer, the sedimentation of which increases with the increase of height. The sedimentation curves of the first layer with 300mm, 350mm heights and the second layer emissions have two turning points. The red mud sedimentation rate of the height of 300mm is faster than the other three and the gap of the water discharge between heights of 250 millimeters and 300 millimeters is about 100 gram. The water discharge of the second layer is smaller than the first layer, of which the gap is about 250 gram; the decreasing rates of the red mud void ratio of the first layer and the second layer are the same, but the decreasing speed of void ratio of the first layer emissions is much faster, and the final void ratio tends to be between 1.22 ~ 1.26; The density curve experiences two processes of increase and two processes of decrease after the mud of first layer and second layer are discharged respectively, then tends to be stable and the stable value is between 2.01 and 2.06 g/cm^{3}.

3102

Authors: Feng Nian Wei, Lu Yang Guo, Zhi Chao Liu, Xu Shen, Hong Tao Liu

Abstract: The effects of three kinds of red mud from alumina plant on limestone’s sulfation kinetics were investigated by thermogravimetric analysis method. Red mud can effectively improve the desulfurization performance of limestone in the whole temperature range. Red mud has little effect on the rate constant of the surface reaction (k), but it can significantly improve the effective diffusivity of reactant in the product layer (Ds). The enhancement of sulfation is more pronounced once the product layer has been formed and consequently the promoting effect becomes greater once the sulfation reaction becomes diffusion controlled.

2339

Authors: Peng Wei, Xiao Dong Ni, Ti Kang Li

Abstract: In order to investigate the mechanism of mud membrane formation during slurry shield tunneling, mesoscopic particle flow method was carried out to examine the way of mud membrane forming in sandy soil stratum at granular level with combinations of the traits of (particle) discrete element model. This study showed that the type of mud membrane formed transit from mud cake to permeable mud cake zone with the increase of the diameter rate of strata soil and bentonite clay until an inability to form mud membrane in the same strata of the soil. Numerical simulation results and related laboratory test are in good accordance, it bear out that researching the It has been demonstrated that it is comparatively reasonable and effective to carry out research on the mechanism of mud membrane formation at a meso-scale level.

362

Authors: Xu Liang, Wei Yu

Abstract: Red mud used in cement stabilized macadam, can be used as cementing materials and auxiliary cementation of cement, and be regard as fine aggregate, which has dual role. Aiming at optimum content of red mud which used in the cement stabilized macadam road base, the grey system theory was used and a new grey situation decision model was established. In this model, variation coefficient was used to decide index weighting. Based on the model for optimum mixture ratio of cement and red mud stabilized graded crushed stone, the calculation of the conclusion is consistent with the actual engineering, which shows that grey situation decision-making is the effective method of optimum content of red mud optimization.

968

Authors: Yue Shen, Ling Tan Zhang, Shi Li Cui, Yi Nao Su, Li Min Sheng, Lin Li

Abstract: Based on the mathematical analysis of band transmission signal coherent detection theory and mud pressure DPSK signal modulation process, by establishing the coherent detection mathematical model of mud pressure DPSK signal, this paper studies the practicability of broadband mud pressure DPSK signal coherent detection. By analyzing the noise impact on input signal parameter of demodulation system, based on probabilistic statistics theory and coherent demodulation mathematical model, the bit error rate and antinoise ability of mud pressure DPSK signal is studied. Theoretical analysis and numerical simulation indicate that, by adding arc cosine and derivation segment to basic demodulation process, the coherent demodulation effect of mud pressure DPSK signal is satisfied, but the demodulation process is more complex than conventional communication system. Theoretical analysis shows that mud pressure DPSK signal has the same theatrical bit error rate as conventional communication binary phase shift keying (2PSK) signal, but due to the difference of signal demodulation means, the reconstruction of rotary valve control pulse will be affected seriously by the derivate of vertical component of the noise within frequency band, causing that the antinoise ability of mud pressure DPSK signal demodulation system is far lower than 2PSK signal system, and numerical calculation shows that the actual bit error rate is far higher than latter; so under the condition of large carrier frequency, to obtain relative small actual bit error rate and relative larger information transmission rate, the mud pressure DPSK signal input signal-to-noise ratio should be raised as far as possible.

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