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Copyright of Uranium Mining & Metallurgy is the property of Uranium Mining & Metallurgy Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Railway Construction Technology is the property of Railway Construction Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The process of removing water from sewage sludge is particularly important due to its high content in the raw sludge. This translates into problems with the transport and storage of sediments. Additionally, high water content reduces the calorific value of the sludge. The methods for selecting the appropriate parameters for sewage sludge conditioning and filtration, based on the experimental data presented in this work, may allow for the optimization of sludge dewatering lines in small and large sewage treatment plants. The optimization of the dewatering process has a significant impact on the environmental and economic benefits, which consequently results in a decrease in the power costs of the devices used, flocculants, and sludge processing, and, above all, it contributes to the reduction in the negative impact on the environment. The use of mineral substances in the preparation of sewage sludge improves the effects of its dewatering in the pressure filtration process, as expressed in the obtained values of the final hydration and process efficiency. The use of polyelectrolytes alone significantly improves the effects of sewage sludge dewatering. In this work, the polyelectrolytes were supported by the addition of cement or zeolite. The conditioning of sewage sludge in combined methods using C-494 polyelectrolyte and minerals made it possible to reduce the compressibility coefficient to the range of 0.24–0.47 and, at the same time, to achieve the best results of sludge dewatering in the filtration process. The lowest hydration of 74.9% was achieved when polyelectrolyte and cement were added to the sludge, and this hydration was 6.5 percentage points lower compared to that of the non-filtered sludge. [ABSTRACT FROM AUTHOR]

A pressure filtration–flocculation–solidification combined treatment possesses great potential for the reutilization of the waste mud slurry generated from diverse construction projects as filling material due to its versatility and high efficiency. However, very limited existing studies have focused on the factors affecting pressure filtration's efficiency. In this paper, a calculation model for compression filtration is established based on laboratory pressure filtration model tests and one-dimensional large-strain consolidation theory. The influence of various parameters on pressure filtration's efficiency is analyzed, and favorable values for these parameters are recommended. The results show that an increased initial mud cake thickness significantly increases the dewatering time and reduces the treatment's efficiency. A lower dewatering time and higher efficiency can be achieved by increasing the filtration pressure, but the efficiency improvements become limited after reaching the critical pressure threshold. For the mud slurry used in this study, the optimal values for the initial mud slurry bag thickness, filtration pressure, and dewatering time are 240 mm, 1.0 MPa, and 30 min, respectively, yielding a final mud cake water content of 58.7% after filtration. [ABSTRACT FROM AUTHOR]

The influence of different weighting agent on the performance of synthetic drilling fluid system (SBM) were studied in this work. Based on the MODRILL drilling fluid system of China Oilfield Services Co., LTD., the variation of SBM performance with 2.04 g/cm³ were investigated with different weighting agent of 4.3 g/cm³ Barite, 4.4 g/cm³ Barite and 4.8 g/cm³ Trimanganese tetra oxide with the ratio of 10∶0∶0、0∶10∶0、5∶0∶5、6∶0∶4、7∶0∶3、8∶0∶2、5∶5∶0. The results showed that the rheological property, emulsion-breaking voltage and high temperature and pressure filtration are affected by the different weighting agent. The apparent viscosity and the plastic viscosity would be decreased and the yield point and 6 rpm reading would be increased with the increasing trimanganese tetra oxide. The emulsion-breaking voltage would be decreased with the increasing trimanganese tetra oxide. The high temperature and high pressure filtration would be substantially increased when adding the increasing trimanganese tetra oxide. The above conclusions were verified in the filed test by studying the effect of weighting agent on the performance of synthetic drilling fluids. [ABSTRACT FROM AUTHOR]

• Optimal oil sands tailings filtration depended on flocculant and coagulant dosing sequence. • Flocculant-coagulant sequence (F-C) generated much better filtration results than C-F. • Surface charges of tailing flocs potentially impacted floc strength and filtration efficiency. Rapid and cost-effective dewatering of wet tailings is crucial for clean and sustainable production in mineral processing. In the process of dewatering oil sands mature fine tailings (MFT) through coagulation-flocculation followed by pressure filtration, we observed that the dosing sequence of coagulants and flocculants had a significant influence on dewatering efficiency. Employing two anionic commercial flocculants (SNF3338 or Kemira PAM) together with an inorganic or a natural coagulant (aluminum sulfate, or chitosan), it was found that the sequence of flocculants followed by coagulants (F-C) gave higher net water release during filtration and lower moisture content in filter cakes than those in reverse sequence (C-F). The capillary suction time measurement showed a faster water release rate from the MFT treated with the F-C sequence. Zeta potential measurements indicated that flocs formed by treatment with the F-C sequence had lower negative potential or more positive potentials, likely contributing to the stronger floc strength and improved inter-floc porosity that favored pressure filtration. The findings in this Technical Note could help optimize the chemical treatment regime and reduce chemical consumption in the filtration of fine wet tailings. [ABSTRACT FROM AUTHOR]

• Synthesise composite coagulants for simultaneous removal of Cs+ and Sr2+ ions. • Operating agitated tubular reactor (ATR) in scope of process intensification. • ATR provided maximum removal efficiency of > 96% Cs+ and > 99.9 % Sr2+. • Physical characterisation and pressure filtration analysis also performed. • Smaller specific cake resistances measured for composite flocs than BaSO 4. Composite coagulants were synthesised in both a batch system and an agitated tubular reactor (ATR) using natural clinoptilolite with barite (BaSO 4) co-precipitation for the intensified simultaneous removal of Cs+ and Sr2+ ions. Ideal plug-flow characterisation of ATR was initially assessed under 3 and 5 Hz oscillations, showing pseudo plug-flow behaviour at the higher rate. Composite flocs were characterised by SEM and size analysis, while dewaterability was also studied by sedimentation and pressure filtration. Aggregate sizes were smaller, but denser and more monodisperse from the ATR than in batch. Composite flocs also gave measured specific cake resistances > 10 × smaller than pure BaSO 4. The higher metal removal performance was achieved using the ATR for Cs+ (95.7%) and Sr2+ (99.9%) at 5 Hz oscillation. A further enhancement for Cs+ removal was achieved by introducing Ba2+ ions into ATR after Na 2 SO 4 addition, achieving > 96% Cs+ and > 99.9% Sr2+ removal. Overall, this study highlights that composite flocs outperform pure BaSO 4 in Cs+ and Sr2+ ion removal while achieving greater dewaterability and filterability. Additionally, we show the ATR effectively intensified the co-precipitation process, potentially reducing plant size and cost, making it a suitable process for modular nuclear cleanup and post-management operations. [Display omitted] [ABSTRACT FROM AUTHOR]

A pressure filtration–flocculation–solidification combined treatment possesses great potential for the reutilization of the waste mud slurry generated from diverse construction projects as filling material due to its versatility and high efficiency. However, very limited existing studies have focused on the factors affecting pressure filtration’s efficiency. In this paper, a calculation model for compression filtration is established based on laboratory pressure filtration model tests and one-dimensional large-strain consolidation theory. The influence of various parameters on pressure filtration’s efficiency is analyzed, and favorable values for these parameters are recommended. The results show that an increased initial mud cake thickness significantly increases the dewatering time and reduces the treatment’s efficiency. A lower dewatering time and higher efficiency can be achieved by increasing the filtration pressure, but the efficiency improvements become limited after reaching the critical pressure threshold. For the mud slurry used in this study, the optimal values for the initial mud slurry bag thickness, filtration pressure, and dewatering time are 240 mm, 1.0 MPa, and 30 min, respectively, yielding a final mud cake water content of 58.7% after filtration.

• The luminescent ZnO-doped Y 2 O 3 ceramics was prepared by infiltration of Y 2 O 3 with Zn2+ ions and pressureless sintering. • The presence of ZnO grains embedded into the Y 2 O 3 matrix was proved using EBSD technique. • The whole visible spectral range of PL emission was achieved in the ZnO-doped Y 2 O 3 ceramics. • Effect of Zn2+ dopant concentration and sintering temperature on luminescence. • Warm white light emission with maximum centered around 570–590 nm depending on ZnO. Y 2 O 3 ceramics containing up to 4 at.%Zn2+ were prepared by infiltrating a zinc acetate water solution into a pre-sintered matrix of Y 2 O 3. After pressureless sintering for 2 h at 1400 °C, ZnO grains dispersed in an Y 2 O 3 matrix were identified. The photoluminescence (PL) spectra of the Y 2 O 3 :ZnO ceramics exhibit a very broad emission band over the entire visible spectral range with an intensity maximum at about 570−590 nm. The intensity of the PL emission increases with an increasing concentration of additive Zn2+, reaching a maximum between 3 and 4 at.%. The annealing temperature also affects the emission intensity. The Y 2 O 3 -ZnO ceramic emits yellowish (warm) white light with the CIE 1931 colour coordinates (0.39,0.43) and a correlated colour temperature in the range of 4000−4600 K. The luminescence decay kinetics at RT exhibit multi-exponential behaviour with faster (∼180 ns) and slower (1.3 μ s and 8.0 μ s) decay components and the average lifetime spanning into the range of 5.3–6.5 μ s. [ABSTRACT FROM AUTHOR]

Coal refuse slurry impoundments have potential environmental concerns associated with water contamination and impoundment stability. Pressure filtration can be used as an alternative method of handling such coal waste streams as it offers an opportunity to stack the dewatered refuse solids for subsequent disposal, reducing or eliminating the need for the impoundment. A response surface methodology approach was used to evaluate the effects of pH, filtration time, and air-blow time on pressure filtration, whose response was measured in terms of final cake moisture. Cake moistures as low as 19.2% were obtained in this study. Experimental results showed a decrease in cake moisture by 13% with an increase in filtration time from 40 minutes to 50 minutes. One third reduction in cake moisture was achieved for a test with 10 minutes of air-blow after 30 minutes of filtration time compared to a test with 40 minutes of filtration time. The effect of pH was significant on both the residual moisture content and the amount of solids deposited in the cake, with acidic pH increasing the filtration performance. A linear fit was developed to relate the amount of solids deposited in the cake as a function of pH and filtration time. A regression model for the response surface with respect to the predictor variables had an R2 value of about 0.99 with almost all the main effects, their square terms, and the interaction effects statistically significant. [ABSTRACT FROM AUTHOR]

A new method is proposed for efficiently predicting filter cake resistance as a function of crystal size distribution. The method is useful for the preliminary design of processes where an economic tradeoff is encountered between a crystallization step and a filtration step. In that case it is necessary to estimate the filter cake resistance repeatedly as a function of crystal size distribution for the process design and optimization. The method is faster than CFD-DEM and more precise than the random packing assumption. The proposed method is validated using published experimental data. To demonstrate the proposed method, an integrated crystallization-filtration process of ammonium alum is simulated and analyzed. The results show that by increasing the residence time of ammonium alum crystals in the crystallizer from 15 min to 60 min, the crystal cake resistance can be reduced by 42% and the filter area can be reduced by 23%. [Display omitted] • A method to estimate crystal filterability based on a specified CSD is proposed. • The method is faster than CFD-DEM and more rigorous than random packing assumption. • Simulation results are validated using published experimental data. • The method can be integrated with any crystallizer model. • Tradeoffs between crystallizer and filter design are analyzed through a case study. [ABSTRACT FROM AUTHOR]

• Demonstrates a novel technique for purifying the cefluosil. • Investigates the optimal nucleation temperature is 1145 °C. • Identifies optimal separation conditions, i.e., T = 1150℃， P = 0.35MPa, t = 4, resulting in the η ce = 88.56%. • Develops the Cake Filtration Models, which expressed as Δ P = α · σ · u · η A 2 · V + u · η · R m A , and t = η · σ · α 2 · ρ 2 · A 2 · Δ P · W 2 + η · R m ρ · A · Δ P · W. • Provides meaningful insights into the separation and purification of rare earth elements. Bayan Obo blast furnace slag (i.e., rare earth slag) is rich in rare earth elements. However, current methods for the separation and extraction of rare earth elements often suffer from lengthy production processes, high energy consumption, and significant environmental pollution, making large-scale applications difficult. Therefore, the separation, purification, and comprehensive utilization of rare earth elements from rare earth slag have become urgent priorities. In this study, gas pressure filtration technology was employed to purify and separate cerium fluorosilicate crystals from a quaternary system of CaO-SiO 2 -CaF 2 -Ce 2 O 3 rare earth slag. The pressure filtration mechanism was investigated, and both constant rate filtration and constant pressure filtration cake models were established. Additionally, the nucleation behavior of the cefluosil crystals was studied, and the optimal nucleation temperature under theoretical conditions was estimated to be 1145 °C. Furthermore, the effects of different separation conditions on the separation efficiency were examined, and it was concluded that successful separation of the cefluosil crystals was achieved under the optimal separation conditions (i.e., filtration temperature of 1150 °C, filtration pressure of 0.35 MPa, and filtration times of 4). After the pressure filtration separation, the recovery rate of Ce, a rare earth element, in the upper crucible reached 88.83%. This study confirms the effectiveness of pressure filtration for solid-liquid separation of rare earth slag and provides new insights for the separation and purification of high-value rare earth elements in rare earth slag. [ABSTRACT FROM AUTHOR]

• A new method to convert waste shield slurry into high-strength material was proposed. • Better pumpability and dewatering of slurry pre-treated by GBFS-FSB were obtained. • Multi-stage pressure filtration can improve the strength of the cakes. • The mechanisms of dewatering and strength growth were discussed. • Dense structure and low water content limited the strength improvement. A huge amount of waste slurry generated in the shield tunnelling construction process needs to be utilized or disposed properly. A geopolymeric flocculation-filtration-solidification method (G-FFS) was proposed in this paper. The properties and the dewatering efficiency of the waste slurry conditioned by the cementitious agents and the geopolymeric agents were investigated through filtration under multi-stage pressures. The strength of the filter cake and its microstructures were then investigated. Subsequently, the mechanisms of dewatering and solidification of the waste slurry and the advantages of the G-FFS method in terms of environmental friendliness were discussed. The results show that, with the G-FFS method, the waste slurry with a high water content could be dewatered rapidly and transformed into high-strength building materials (2.47–10.31 MPa). The conditioned slurry also demonstrated a low kinematic viscosity and a low capillary suction time, indicating a better pumpability and dewatering ability. The addition of the sodium dodecyl sulfate (SDS) could improve the dewatering performance further. The hydration of the geopolymeric agent and the high-pressure filtration enhanced the strength of the cake. The densified micro-structure of the filter cake and limited water content led to the difficulty of hydration and, thus, limited the increase of the strength. Compared to the traditional method of utilizing the waste slurry through a cementitious agent, the G-FFS method demonstrates its advantages in efficiency, cost-effectiveness, and environmental friendliness. [ABSTRACT FROM AUTHOR]