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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]

Achieving synergy between load-carrying capability and excellent damage tolerance is one of the most concerned issues in the ultra-high temperature ceramic field. Herein, ZrB 2 -SiC-C f composite with homogenous architecture was constructed by a novel pressure filtration and slurry infiltration accompanied by low-temperature hot pressing. The composite exhibited a typical non-brittle fracture feature owing to crack deflection, crack bifurcation and fiber pull-out mechanisms, resulting in a reliable specific flexural strength of 75 MPa/(g/cm3) and superior work of fracture of 672 J/m2. [ABSTRACT FROM AUTHOR]

A spatially resolved one dimensional pressure filtration model was developed for a slurry of edible fat crystals. The model focuses on the expression step in which a cake is compressed to force the liquid through a filter cloth. The model describes the local oil flow in the shrinking cake modeled as a porous nonlinear elastic medium existing of two phases, viz. porous aggregates and interaggregate liquid. Conservation equations lead to a set of two differential equations (vs. time and vs. a material coordinate ω) for two void ratios, which are solved numerically by exploiting a finite‐difference scheme. A simulation with this model results in a spatially resolved cake composition and in the outflow velocity, both as a function of time, as well as the final solid fat contents of the cake. Simulation results for various filtration conditions are compared with experimental data collected in a pilot‐plant scale filter press. [ABSTRACT FROM AUTHOR]

Pressure filtration testing was carried out to dewater coal refuse slurry obtained from the thickener underflow stream of an operating coal preparation facility in Pennsylvania. Pressure filtration offers an opportunity to dewater refuse solids so that they can be stacked for long-term storage, while increasing the quantity of water available for recycling. Lab-, pilot- and bench-scale pressure filters were tested. Results from the lab-scale plate filter indicated a steep decrease in cake moisture for the first 120 seconds of the filtration cycle, beyond which further decrease in cake moisture was achieved only by initiation of air-blow. Similar trends were observed with the pilot-scale plate filter, with a 1.5% cake moisture reduction for every minute of air-blow after the initial sharp decrease. Cake moistures of about 30% were achieved for both units, though cake thickness can influence cake moisture. Filtrate flux values were also similar for the lab- and pilot-scale plate filters, indicating a linear scale-up with respect to the filter area. Analysis of the filtrate flux for various thicknesses in the lab-scale plate filter indicated that filtrate flux, for a given filter area, increased with increase in cake thickness. Upon normalization of filtrate flux based on cake thickness, the thinnest cake was shown to have the highest filtrate flux per unit thickness. Bench-scale pressure filtration results gave similar trends on filtrate flux and cake moisture, indicating that testing at this level can be used as a screening tool prior to scale-up testing. [ABSTRACT FROM AUTHOR]

The present investigation aimed to understand dewatering amenability of the tailing slurry generated during the beneficiation of chromite ore. The tailing includes mainly ultrafine particles with a concentration of Cr+6 which causes environmental and storage issues. Several dewatering techniques were investigated, including settling by using two different thickeners (high rate thickening and paste thickening), pressure filtration, as well as classification by using hydrocyclone. This paper explains the results obtained in various stages of the dewatering process. Further, different dewatering circuits were examined for the effective dewatering of the tailing slurry, and the optimum solutions were discussed. It is also concluded that up to 97% of the water can be recovered and recycled from such tailing slurry by adopting an efficient dewatering circuit. [ABSTRACT FROM AUTHOR]

Purpose: This work details experimental observations on the effect of liquid flow percolating through packed beds of crystals to elucidate how the filtration pressure severely alters the size distribution and crystal shape. Pressure filtration is widely used in the pharmaceutical industry, and frequently results in undesired size distribution changes that hinder further processing. Methods: The percolation methodology presented fixes fluid flow through a bed of crystals, resulting in a pressure over the bed. X-ray computed tomography (XCT) provided detailed observations of the bed structure. Detailed 2D particle size data was obtained using automated microscopy and was analysed using an in-house developed tool. Results: Crystal breakage is observed when the applied pressure exceeds a critical pressure: 0.5–1 bar for ibuprofen, 1–2 bar for β-L glutamic acid (LGA) and 2–2.5 bar for para amino benzoic acid (PABA). X-ray computed tomography showed significant changes in bed density under the applied pressure. Size analysis and microscope observations showed two modes of breakage: (i) snapping of long crystals and (ii) shattering of crystals. Conclusion: LGA and PABA have a similar breakage strength (50 MPa), ibuprofen is significantly weaker (9 MPa). Available breakage strength data may be correlated to the volumetric Gibbs free energy. Data from 12 and 35 mm bed diameters compares well to literature data in a 80 mm filter; the smaller, easy to operate percolation unit is a versatile tool to assess crystal breakage in filtration operations. [ABSTRACT FROM AUTHOR]

The effects of processing parameters on fatigue lives of graphene oxide papers (GOP) and reduced GOP (RGOP) are investigated. The fabrication method could be either vacuum filtration or pressure filtration, and the important processing parameters include graphene weight fraction in suspension, sonication time for suspension and pressure value for pressure filtration. Fatigue performance of the papers are studied by strain‐controlled fatigue test. Under vacuum filtration method, fatigue lives of both GOP and RGOP decrease with increasing graphene weight fraction. The longest fatigue life is 403 284 cycles for the GOP under highest power sonication time and lowest graphene weight fraction. Fatigue lives of most GOP increase with increasing sonication time up to medium level. Under pressure filtration method, all GOP have shorter fatigue lives than those by vacuum filtration. Scanning electron microscopy is employed to carefully analyse the failed papers in order to clarify the fatigue failure mechanism. [ABSTRACT FROM AUTHOR]

In order to enhance the effects of concentration and dewatering, sludge is prepared (treated) before. The aim of conditioning sludge before dewatering is to reduce, not only its resistance but also its compressibility. The article presents the analysis of the impact of combined methods of conditioning (ultrasonic field, inorganic coagulant, cationic polyelectrolyte) on the changes in final hydration of sewage sludge in the process of pressure filtration. The study involved sewage sludge after the process of methane fermentation and stabilization in open digesters. The aim of the work was to show that by using the energy of ultrasound and chemical substances, it is possible to change the properties of sewage sludge through changing the dimensions and the capacity of particle packing, thus improving the effectiveness of dewatering. Digested sludge is hard to dewater, which is proved by its capillary suction time (CST), amounting to 1,859 s. The lowest CST value (29.3 s) and final hydration (65%) were obtained for sludge sonicated for 60 s (amplitude 30.5 µm) prepared with PIX 113 (coagulant) in the dose of 1.0 mg/gd.o.m. (d.o.m. - dry organic mass) and Zetag 8180 (polyelectrolyte) in the dose of 7.0 mg/gd.o.m. The application of an ultrasonic wave and chemicals to modify sewage sludge caused the reduction in the value of final hydration and thus led to better results of sludge dewatering in the process of pressure filtration. In addition, the combined use of ultrasound, PIX 113 and Zetag 8180 reduced the content of suspended solids, phosphorus and ammonium nitrogen in sludge liquids. [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]

The paper presents the impact of different methods of sewage sludge conditioning on the improvement of sludge dewatering during pressure filtration processes. The following conditioning methods were tested for sludge preparation: sonication, addition of organic and inorganic chemicals (Zetag 8180, PIX 113 and the combined action of both substances). The research covered: physical and chemical analysis of sewage sludge, measurement of capillary suction time as an indicator of sludge dewaterability, some technical parameters of sludge pressure filtration process and the analysis of filtrate to assess the degree of contamination. The results of the research showed that the final water content of the prepared sludge decreased, while the specific filtration resistance increased. Among the tested methods the best results of sludge dewatering effects were obtained for sonicated sludge and its preparation with inorganic coagulant PIX 113. The combined effect of sonication with the addition of chemicals Zetag 8180 and PIX113 to sludge allowed for the reduction of organic substances, ammonium nitrogen and phosphates in filtrate after sludge dewatering.

Pressure filtration is a key process in ceramic forming; however, the influences of density difference in different parts of a pressure‐filtrated wet cake on subsequent drying and sintering have not yet been explored. In the present work, alumina slurries dispersed by copolymers of isobutylene and maleic anhydride (PIBM) and ammonium salt of polyacrylic acid (PAANH4) were pressure filtrated to examine the impacts of density difference in the as‐prepared wet cakes. In comparison to the wet cake produced from PAANH4, the wet cake with PIBM had much higher bulk density and smaller density difference between its upper and bottom parts (height of ~23 mm). Furthermore, in order to reveal the differences between these two wet cakes, the nature of agglomerates in their slurries was investigated. The slurry with PIBM contained agglomerates with a wider size distribution, bigger average size, and higher sphericity, producing a wet cake with a higher particle packing density and more homogeneous packing structure after pressure filtration. Hence, almost no deformation occurred in a large wet cake (280 mm × 130 mm × 20 mm) with PIBM, whereas that with PAANH4 experienced a severe deformation after sintering. [ABSTRACT FROM AUTHOR]

• Flocks are stable against decomposition at varying energy inputs. • Flock diameter rises with increasing solid concentration. • Replacement of classical centrifugation for flock separation by filtration. • Raised mass flow by increasing concentration while maintained classification result. • Cornerstone towards the development of a scalable processing of nanoparticles. Nanoparticles like quantum confined ZnS semiconductor nanocrystals, exhibit unique structure-property relationships. Narrow particle size distributions (PSDs) become one of the most important factors to tailor product performance. Size selective precipitation has already been proven to be an effective post processing strategy for ZnS nanoparticles. It is based on the titration of a poor liquid into a stable dispersion, which leads to the preferred flocculation of larger particles. Afterwards, these flocks must be separated from the continuous phase. While on lab scale the formed flocks can be easily separated by centrifugation from the fine fraction, for larger scale production using continuous processes, new concepts are urgently needed. Herein we developed a filtration process for flock removal that allows the handling of larger quantities. For process design, we first investigated the flock properties in order to know how stable the generated flocks are and how the flock properties can be controlled. Then, we replaced the classical flock separation by centrifugation through separation by surface filtration under the constraint that the underlying separation efficiency was not affected. By the future use of properly controlled, alternating filtration modules, our work opens the door for establishing an urgently needed, scalable post-processing for sub-10 nm nanoparticles. [ABSTRACT FROM AUTHOR]

Pressure filtration provides an opportunity for dewatering coal refuse sufficiently to reduce or possibly eliminate the need for a slurry impoundment. In this study, pressure filtration was performed in a lab-scale unit to evaluate the dewatering nature of coal refuse slurry, which was obtained from a coal preparation facility. Evaluation of the process was performed using a fractional factorial design with cake moisture as the response and pressure, pH, and solids concentration as the variables of interest. Results indicated a decrease in cake moisture with increase in solids concentration and pressure, and an increase in cake moisture with pH. With pH playing a significant role in dewatering coal refuse slurry, zeta potential measurements were performed at different pH values to confirm the likeliness of agglomeration at lower pH. Filtrate flux values from the current test matrix were compared with the flux values of a bench-scale pressure filter, and a logarithmic relationship between the filtrate fluxes of the two units was developed. Results also indicated that for lower values of filtrate flux, the flux per discharge port remained constant during the scale-up from bench-scale to lab-scale units. [ABSTRACT FROM AUTHOR]

Water removal in colloidal processing is a tough and crucial problem because deformation and cracking of the wet body easily happen during the drying process. Inspired by conventional pressure filtration (PF), we combined spontaneous coagulation casting (SCC) with PF to partially remove water from the gelled sample before drying for the purpose of lessening the risk of cracking and shortening the drying period. The effect of pressure, holding time, and solid loading on the particle packing ratio of wet samples, the drying process, and the bulk density and homogeneity of green and sintered bodies was surveyed systemically. The PF process of 0.4 MPa for 2 h was optimized based on dewatering ratio from ceramic slurries. The particle packing ratio of the pressure-filtrated samples increased with the solid loading of ceramic slurries, and 61 vol% was obtained for the slurry with 56 vol% solid loading. The drying time of the pressure-filtrated samples was shortened by as much as 42%–53% compared with that of the gelled samples, and the linear shrinkage for the pressure-filtrated samples during drying was only approximately 0.5%, much smaller than that of the gelled samples (2.4%–4.6%). Furthermore, the bulk density of the pressure-filtrated green bodies was more than 2% higher than that of the gelled green bodies, and more homogeneous green bodies were obtained by PF than by SCC. The alumina ceramic with 98.8% relative density and a homogenous density distribution was obtained after being sintered at 1550 °C for 2 h. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A novel process for integration of bioethanol and biodiesel production is proposed. • The retained fatty acid soap reduced lignin redeposition and cellulase absorption. • Pressure filtration is a superior method for minimized water use. • A high glucose yield of 94.95% and the ethanol yield of 73.10% were achieved. Abstract Utilization of sustainable energy is limited by energy requirement for the manufacturing of renewable fuels. Moso bamboo was pretreated with industrially derived crude glycerol obtained from different sources at 150/160 °C for 3 h. This bamboo, pretreated with base biodiesel glycerol with pressure filtration removal method, showed a high glucose yield of 94.95% and an ethanol yield of 73.10% of the theoretical. Major glycerol content was removed by pressure filtration, leaving a small amount of fatty acid soap in the pretreated sample, which formed an emulsion that reduced lignin redisposition onto the biomass surface and effectively blocked lignin absorption of cellulase, allowing greater enzymatic hydrolysis and fermentation system function. The surface was more hydrophilic and a higher lignin removal was achieved: 39.24% with base biodiesel glycerol pretreatment compared to 26.08% with sodium hydroxide glycerol pretreatment. This study provides a useful and cost-effective process, BBGP, for high-yield ethanol production. [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]

Sludge dewatering is a key element in sludge’s processing and management. Solid-phase separation, sludge volume reduction and the separation of a high-quality supernatant are the main tasks of the dewatering devices. The effectiveness of this task, in turn, results from the selection of the dewatering method and conditioning of the sludge before dewatering. The aim of the research was to determine the influence of conditioning substances (polyelectrolyte, fly ash and zeolite) on the efficiency of dewatering at variable filtration pressure. The use of polyelectrolyte in sludge conditioning was a solution that increased the efficiency of the filtration process. On the contrary, the use of structure-forming substances (fly ash and zeolite) slows the process but reduces the hydration of the filter cake. The same trends were obtained in dual conditioning combining dosing of polyelectrolyte and ash or zeolite. It was also shown that the dewatering efficiency of conditioned sludge with these two different substances (ash and zeolite) was the same. The use of zeolite in independent or dual conditioning was important for the quality of the supernatant.

Graphical abstract Based on the different melting points of metals or alloys, alloys of Pb-Sn and Cu were selectively and gradually recovered from granulated printed circuit boards (PCBs) by pressure infiltration separation. Highlights • Cost-effective and environmental recovery are difficult via traditional methods. • Pressure separation provides highly efficient recovery of metals from PCBs. • Higher pressure and temperature improved Cu recovery. • The process achieves closed-loop, clean recycling of e-waste with high efficiency. Abstract In recent years, recovery of metals from electronic waste (e-waste) within China has become increasingly important due to potential supply risk of strategic raw material and environmental concerns. Printed circuit boards (PCBs) contain lots of valuable metals together with plenty of hazardous materials, which are considered both an attractive secondary resource and an environmental contaminant. Pressure filtration is an effective and environmentally friendly method for separating and recycling comminuted PCBs. Present work is focused on the recovery of metals from PCBs by low-pressure filtration separation. A two-stage separation process was adopted to selectively recover Pb-Sn and Cu alloys at different temperatures. The results showed that the temperature and pressure had great influence on the recovery of metals in the separation process. After the two-stage separation process, the total recoveries of Pb, Sn, Cu and Zn were 79.96%, 89.91%, 88.80% and 68.57% respectively, when the temperature is 1350 °C and the pressure is 0.30 MPa. This is a high-efficiency, short-flow, clean-production, and environmental-friendliness that can improve the recovery of metals and realize the reuse of waste resources. [ABSTRACT FROM AUTHOR]

This study deals with the modeling and analysis of the pressure filtration process using statistical and machine learning techniques. The effects of externally controllable process-influencing factors such as pressure, pH, temperature, solids concentration, filtration time, air-blow time, and cake thickness on filtration performance, measured in terms of cake moisture, were modeled. A 9-factor regression model based on an exhaustive search algorithm and a 7-6-1 artificial neural network (ANN) model based on a resilient backpropagation algorithm were developed and gave R2 values of 0.84 and 0.94, respectively. Relative importance of input variables was analyzed using novel methods such as added-variable plots based on the regression model and Olden's method based on the ANN model. Results from both methods established a negative correlation for pressure, solids concentration, filtration time, temperature, and air-blow time and a positive correlation for cake thickness and pH. Analysis from regression and ANN models indicated pH to be the most significant process-influencing factor. Even though both models served as good interpretable models, the ANN model outperformed the regression model in terms of predictive capability, with an R2 value of 0.965 compared with the regression model's 0.750 for the test dataset. [ABSTRACT FROM AUTHOR]

Pressure filtration of coal refuse slurry has the potential to provide a concentrated solids stream that can be stacked, thereby offering multiple environmental benefits. However, potential leachates from the solids stream can impact the environment. In that context, this study performed preliminary investigations of the application of zeolite-based additives to adsorb metals leaching from coal refuse slurry at low pH. Additives were added to the coal refuse slurry, which was filtered using bench- and lab-scale pressure filtration units. Results indicated that the overall filtrate flux and cake moisture characteristics were not significantly affected by the addition of additives up to 20% (by weight of solids). It was shown that adsorption as high as 80% was achieved by using the additives to capture iron. It was concluded that the finer additive with less silicon content was more effective in capturing iron. The results showed that the thickener feed stream leached out less iron than the thickener underflow stream. The adsorption process was not significantly affected by slight variations in initial iron concentration in the solution. The use of lower pH water on the filter cakes treated with the additive showed minimal release of iron and manganese into the aqueous phase. [ABSTRACT FROM AUTHOR]

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High density and homogeneous green body is important for fabricating transparent ceramics. Inspired by the improved samples’ homogeneity in slip casting, we introduced low pressure filtration to gel casting to further increase the relative density and homogeneity of the green body and to shorten the drying time. The effect of pressure filtration on drying characteristics, bulk density and porosity of the pre-sintered bodies, and the microstructure and optical transmittance of the resultant ceramics were intensively investigated. The results showed that pressure filtration can reduce the drying time by 27.3%, improve the density of the pre-sintered bodies and reduce the residual pores of the sintered ceramics. The in-line transmittance of the translucent alumina prepared by the pressure filtration assisted gel casting was 32.7% at 600 nm with a thickness of 1 mm, which is about 6% higher than that without pressure filtration. In principle, this process can be applied to fabricate any other high-performance ceramic. [ABSTRACT FROM AUTHOR]

The effects of pressure and cake thickness were studied using a split-plot design for pressure filtration of a fine refuse slurry obtained from a bituminous coal preparation facility. Pressure filtration offers the potential to significantly reduce the moisture content of the fine refuse stream with the addition of little to no flocculants, thereby minimizing the volume of refuse stored in impoundments and providing a recycle water stream for use within the plant. Experimental results showed that the final cake moisture decreased with increase in pressure and decrease in cake thickness. In addition, specific cake resistances calculated for the various tests indicated an increasing trend with increasing pressure and decreasing cake thickness. With increase in cake thickness, an increase in cake moisture and the weight of solids deposited in the cake was observed. An ANOVA analysis indicated that both cake thickness and pressure significantly affected the cake moisture, while only cake thickness statistically influenced the weight of solids in the cake. A regression model was developed with an R2 value of about 0.99 to relate cake thickness, the single largest statistically significant factor, with the weight of solids in the cake. Filter capacities were calculated in terms of the solids deposited per unit time based on a product specification of 25 percent cake moisture, and it was observed that the thinnest cake had the highest filter capacity. [ABSTRACT FROM AUTHOR]

Sewage sludge dewatering processes can be very costly and difficult to solve at the wastewater treatment plants all over the world. Sludge includes substances that do not dehydrate easily, and without initial proper preparation, the effects of its dehydration and the degree of separation are very low. The degree of dehydration of sewage sludge is significant, because it is associated with energy consumption and costs of drying the sludge. The aim of the research was to determine the influence of combined activity of PIX 113 coagulant (non-sonicated and sonicated) and Zetag 8160 polyelectrolyte on pressure filtration parameters of digested sewage sludge. A technique based on the preparation of coagulant PIX 113 with ultrasound waves was used in an unconventional way. The combination of physical and chemical sludge conditioning was intended to improve the sludge dewatering process. The sludge for tests was collected after the digestion process. The use of the non-sonicated and sonicated PIX 113 in combination with the polyelectrolyte Zetag 8160 resulted in a decrease of capillary suction time (CST) value in relation to CST of the untreated sludge. Applied dosages of chemical reagents, such as PIX 113 and Zetag 8160, have improved the values of final hydration of sludge in the process of pressure filtration. The lowest final hydration of sludge was obtained when sludge was prepared with sonicated PIX 113 and Zetag 8160. Thus, the use of ultrasonic wave for the modification of the PIX 113 coagulant improved results of sludge dewatering process during pressure filtration. [ABSTRACT FROM AUTHOR]

In guiding dewatering of oil sands tailings we measured dewaterability of as-mined kaolin when sand was added as a process aid to both the dispersed and flocculated kaolin slurries. In batch tests, gravitational settling, inverse permeability R , and compressive yield stress P y were measured as functions of solids volume fractions Φ, as sand increased in the mixtures. We measured P y(Φ) for flocculated kaolin with an equal sand fraction, a flocculated diluted kaolin, flocculated diluted mature fine tailings (MFT), gel-point kaolin and MFT. Results indicated that an optimal quantity of sand in mixtures with kaolin increased the consolidated volume fraction of solids at equivalent compressive yield stress, reduced hindered settling function values, and enhanced gravitational settling rate. P y(Φ) vs Φ plots for gel-point volume fractions of kaolin and MFT showed MFT to be more compressible, but needed a much longer time to dewater. Two flocculants had similar P y(Φ) vs Φ responses when tested with either kaolin or MFT. Flocculated kaolin and MFT exhibited rapid settling, but flocculated was less compressible than unflocculated. P y(Φ) vs Φ plots for both kaolin and MFT that were flocculated after dilution produced a crossover at P y = 121 kPa and Φ = 0.41. The P y(Φ) vs Φ data from all tests followed power law. [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]

Pressure filtration offers the opportunity to produce solids (filter cake) that can be stacked or mixed with the coarse refuse, and water (filtrate) that can be recirculated in the plant. In this study, the bench-scale pressure filtration testing was performed to dewater coal refuse slurry, which was obtained from the thickener underflow stream of a coal preparation plant, and was being discharged into a slurry impoundment. A flexible fractional factorial design was developed to determine the effects of pressure, pH, and solids concentration on the performance of filtration, which was measured in terms of filtrate flux. The results indicated that the pH had a maximum effect on the filtrate flux followed by the pressure and solids concentration. Additionally, a linear regression model and an Artificial Neural Network (ANN) model were developed to predict the filtrate flux based on the test variables. Both models were able to fit the data well, with R 2 values of 0.986 and 0.991 for the linear regression model and the ANN model respectively. It was also found that the test dataset had a mean squared error of 0.2 for the ANN model, while it was 3.99 for the regression model. [ABSTRACT FROM AUTHOR]

Bench-scale pressure filtration testing was performed to evaluate the dewatering characteristics of two coal refuse slurries, which were collected from thickener underflow streams of two coal preparation plants. Pressure filtration provides an opportunity to produce drier solids (filter cake) that can be stacked or mixed with the coarse refuse and improved water (filtrate) recovery that can be reused in the plant. This paper examines the effects of some of the major influencing variables such as pressure, slurry pH, feed solids concentration, fines fraction of solids in the slurry, filtration time, and temperature on dewatering thickener underflow slurry. Experimental results indicated that the overall filtrate flux increased with increase in pressure and temperature while it decreased with increase in fines fraction, pH, filtration time, and solids concentration. A total of 82 experimental results were used to develop a feed forward back-propagating artificial neural network (ANN) model. The model had R2values over 0.9 for both the training and the testing datasets, indicating the goodness of fit. Sensitivity analysis performed using the ANN model indicated that filtration time and pH were the most significant variables influencing filtrate flux. [ABSTRACT FROM AUTHOR]

During the dewatering process of iron ore concentrates, the formation of shrinkage cracks severely interferes with the filtration process and causes high cake moisture. Until now, effective countermeasures and mechanism study about shrinkage cracks are still insufficient. In the previous researches, capillary forces have been considered to be the driving potential for the shrinkage cracks, which were related with liquid surface tension and particle contact angle. Thus, surface tension and contact angle were both changed in this paper by using a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB). Moreover, the zeta potential, adsorbance and infrared spectra were respectively measured before and after CTAB coating to analyze the change of interfacial properties and the influence on the extent of shrinkage cracks. The results indicate that the tendency of filter cakes to form shrinkage cracks can be weakened with the decrease of capillary forces. [ABSTRACT FROM AUTHOR]

Pretreatment and enzymatic hydrolysis play a critical role in the economic production of sugars and fuels from lignocellulosic biomass. In this study, we evaluated diverse pilot-scale pretreatments and different post-pretreatment strategies for the production of fermentable sugars from sugarcane bagasse. For the pretreatment of bagasse at pilot-scale level, steam explosion without catalyst and combination of sulfuric and oxalic acids at low and high loadings were used. Subsequently, to enhance the efficiency of enzymatic hydrolysis of the pretreated bagasse, three different post-pretreatment process schemes were investigated. In the first scheme (Scheme 1), enzymatic hydrolysis was conducted on the whole pretreated slurry, without treatments such as washing or solid-liquid separation. In the second scheme (Scheme 2), the pretreated slurry was first pressure filtered to yield a solid and liquid phase. Following filtration, the separated liquid phase was remixed with the solid wet cake to generate slurry, which was then subsequently used for enzymatic hydrolysis. In the third scheme (Scheme 3), the pretreated slurry was washed with more water and filtered to obtain a solid and liquid phase, in which only the former was subjected to enzymatic hydrolysis. A 10 % higher enzymatic conversion was obtained in Scheme 2 than Scheme 1, while Scheme 3 resulted in only a 5-7 % increase due to additional washing unit operation and solid-liquid separation. Dynamic light scattering experiments conducted on post-pretreated bagasse indicate decrease of particle size due to solid-liquid separation involving pressure filtration provided increased the yield of C6 sugars. It is anticipated that different process modification methods used in this study before the enzymatic hydrolysis step can make the overall cellulosic ethanol process effective and possibly cost effective. [ABSTRACT FROM AUTHOR]

The aim of this paper was to study cake filterability and compressibility as a function of the particle shape and particle size distribution (PSD). Different shapes and PSD of calcium carbonate and uranium oxalate particles covering the classical types encountered in industry (sphere, cube, needle and platelet) were obtained by precipitation. The size and shape factor distributions were measured using an image analysis system on SEM pictures. The cake filtration properties were measured in ideal monitored operating conditions, because of a miniaturised filtration cell set-up. The impact of the PSD and the shape were quantitatively assessed. These two solid features have an impact on cake resistance and compressibility, but not in the same way. The PSD has the strongest effect on cake resistance and compressibility. The particle shape is a decisive parameter for cake compressibility when the shape is far from the sphere. Both parameters need to be considered when working on the development of a filtration operation. Here, a practical model built following the Darcy law coupled with a new correlation for compressibility factor assessment is proposed. It gave satisfactory estimates of cake filterability and compressibility for the four shapes studied. [ABSTRACT FROM AUTHOR]

Rheological properties of aqueous suspensions (48 vol%) of zircon-alumina mixtures containing different amounts of polyelectrolyte as dispersant were studied. Slip casting in a plaster mold and pressure filtration at 8 MPa experiments were performed to correlate the rheological properties of the suspensions with the relative density of green casts. Flow curves fitted satisfactorily to the Casson model. The Casson viscosity values remained nearly constant whereas Casson yield stress parameter decreased to a minimum and then increased with increasing the amount of dispersant added. The influence of particle size distribution (PSD) of the powder mixtures on Casson yield stress parameter and on the minimum viscosity was also examined. Green densities increased as yield stress Casson parameter decreased. The mixture of alumina and zircon as fine and coarse powders produced bimodal PSD which maximized the green density of the compacts. Some weakly flocculated suspensions having low apparent viscosity and small yield stress produced casts with relatively high densification. This is attributed to a slight higher viscosity at low shear rates of these suspensions in which settling of particles and /or segregation of components can not occur.

The article presents the results of research on the impact of inorganic coagulants and polyelectrolytes and their common action on non-prepared and sonicated digested sludge. Sonication of sludge samples was carried out under static conditions for 60, 120, and 180 s. An ultrasonic wave off = 20 kHz and two different amplitudes ofA = 15.25 and 30.5 μm were used in tests. The coagulant PIX123 and the polyelectrolyte Zetag 8160 were used for conditioning. On the basis of CST test, doses of chemical reagents were chosen for conditioning. The results indicated the effect of the PIX123 and Zetag 8160 application on non-sonicated and sonicated sludge. The lowest CST values were achieved, while the combination of coagulant in a fixed dose of 1.0 mg/g and polyelectrolyte was used. This effect was observed for non-sonicated sludge as well as for sonicated sludge. The higher dose of chemical reagent used for non-sonicated sludge, the lower the final hydration was achieved. For non-sonicated sludge, better results were obtained when the Zetag 8160 was used. For sonicated sludge, better results were achieved when PIX123 was used. The effect of the final hydration reduction for sonicated sludge and prepared with Zetag 8160 was not satisfactory. The application of the coagulant and the polyelectrolyte combination does not allow achieving lower final hydration of sludge in comparison with only PIX 123. However, it was possible to achieve higher suspension and COD reduction. [ABSTRACT FROM PUBLISHER]

Cake filtration is an important unit operation in the processing of minerals and pigments. The filtration characteristics are strongly dependent on the upstream processing of the ore, such as grinding parameters. This study aims at empirical investigation of the influence of key stirred media milling variables on the pressure filtration characteristics of calcium carbonate. Various regression models are presented and evaluated with respect to their statistical significance. The results show that all the grinding variables have a statistically significant influence on the average specific cake resistance, but the predictability of the models is not very good unless combined and polynomial terms are considered. [ABSTRACT FROM AUTHOR]

Chemical and process industries utilize stirred media mills for efficient fine grinding of solids. Stirred media mills, also referred to as stirred ball or stirred bead mills, generally have a good ability to produce fine particles with a relatively narrow particle size distribution. Wet grinding with vertical stirred ball mills is typically carried out for slurries containing particles smaller than 200 μm, such as industrial minerals and pigments. Filtration is an important unit operation, which is performed in order to reduce the water content of the slurry after grinding and concentration, and prior to drying and transportation. Pressure filters are used to obtain the maximum dryness of the product. A number of properties of solids affect the filtration performance. The particle size and shape, the width of particle size distribution, and the net surface charge of the particles are among the factors having a significant influence on the filtration characteristics. In this study, the dependency of the pressure filtration properties of wet ground calcium carbonate (GCC) slurries on the grinding result obtained by a stirred media mill is investigated. After grinding, subsequent filtration experiments were carried out with a laboratory-scale pressure filter. Average specific cake resistances, porosities of the filter cakes, and cake compressibility parameters were determined from the filtration data. The results showed clear correlations between the particle size data and the related filtration properties. Interesting observations were also made regarding the average porosity of the filter cakes and the uncertainty of the experiments. [ABSTRACT FROM AUTHOR]