Slurry Concentration Research Articles

Techno-economic feasibility and comparison of coal water slurry concentration on a coal to methanol plant with consideration of carbon capture and storage

ABSTRACT In this study, the effect of slurry concentration and carbon dioxide capture and storage (CCS) equipment on the techno-economic feasibility of a coal-to-methanol (CTM) process with coal water slurry (CWS) gasification are investigated, while the effective means to improve the economic benefit of methanol factory are proposed. The sensitive factors including production scale, coal price, and carbon tax are investigated, especially the CWS concentration is compared at 63% and 68% scenarios. A CTM plant with 180 × 104 t/a production scale shows that the saving cost could reach 29.20 × 106 US$ and the CO2 emission could be reduced by 0.65 × 106 t/a every year as the CWS concentration increases. The investment in CCS equipment would increase the production cost (PC) per methanol raising by 7–8%, while the CCS introduction would effectively alleviate the PC increment caused by the carbon tax. Note that as the carbon tax exceeded 9.42 US$/t, the benefit for CCS on the reduction of PC would be more significant. The outcomes of this study have suggested that increasing the CWS concentration is an effective method to reduce the PC and improve the economic benefit. The CCS technology could effectively reduce CO2 emissions and mitigate the raising of PC caused by carbon tax. The findings have manifested a well feasibility for environment benefit improvement by solid content increasing and CCS introduction in response to energy and environmental challenges for the cleaner production and sustainable development.

Numerical study of the flow and heat transfer characteristics of microencapsulated phase change slurry

ABSTRACT Microencapsulated phase change material (MPC) slurry is created by combining phase change material with a carrier fluid that has superior heat transfer properties compared to ordinary water. MPC slurry is conventionally investigated as heat storage and working fluid in a variety of applications to reduce power consumption. This study numerically investigates the impact of several critical parameters on the heat transfer coefficient (HTC) of MPC slurry in a circular pipe, using Eulerian–Eulerian model. The right triangle curve, one of equivalent specific heat model (ESHM), was applied to evaluate the influence of different critical variable values specified as T in = 305 K, q wall = −125~−200 kW/m2, α v = 0~15%, Re = 6290~13838, and D = 10~25 mm. The results show that increasing the velocity develops local HTC and reduce the rate of heat transformation. Phase change processing takes roughly twice as long at 1.1 m/s as at 0.5 m/s. Additionally, the results demonstrate that a high concentration of MPC slurry is advantageous for energy storage, as the temperature of MPC slurry is maintained over a considerable distance in cooling conditions. At a velocity of 0.8 m/s, the outlet bulk temperature of MPC slurry at various concentrations is 2–6 K higher than that of water. Furthermore, the evaluation reveals that the HTC was largely determined by pipe size, which was the primary factor. The findings of this study are useful for optimizing energy systems that require thermal energy management.

Investigation of Erosion Effect on Surface of Basalt Fibre Reinforced Polymer Composites

In the present study the erosion behavior of basalt fibre reinforced composite was studied. Slurry pot erosion test were conducted on the composite samples with 30%, 40% 50% and 60% reinforcement. Slurry concentration, speed and contact angle were considered as the parameters. The sand particles from the range of 212, 425 and 600µm were suspended in the water. The results revels that the slurry erosion was found to be increased with slurry concentration and the turning speed. The impact angle with 900 has the major influence on the erosion. The highest mass loss due to erosion is found in the sample with 30% reinforcement and the minimal mass loss due to erosion is found in the sample with 60% reinforcement.

Effect of peat moss as a feed additive on odorous compound concentration and odor contribution in stored pig slurry

Effect of peat moss as a feed additive on odorous compound concentration and odor contribution in stored pig slurry

ANN SUPPORTED STUDY ON THE PERFORMANCE AND SLURRY EROSION RESISTANCE OF THERMAL SPRAYED WC20CR3C27NI COATINGS

The thermal spray coatings are commonly employed in slurry pump components and hydrodynamic turbine blades, where wear progression is an intricate phenomenon. In this research work, the performance analysis of HVOF and APS sprayed WC20Cr3C27Ni coatings for slurry erosion wear is carried out by using artificial neural networks (ANN). The influence of time, particle size, impact angle, speed, and slurry concentration on wear performance of coatings and turbine steel substrate are evaluated. Under the experimental settings, slurry erosion wear rates and mass loss for both coatings and substrate were determined. When ASTM A743 steel was coated with thermal sprayed WC20Cr3C27Ni coatings, the slurry erosion wear resistance of the steel was enhanced by 2 and 3.5 times for APS and HVOF coatings, respectively. The design of ANN made it possible to examine the interactions between the seven input variables. A robust model was formed by the two outputs that followed. This model enables the prediction of slurry erosion wear rate and mass loss of WC20Cr3C27Ni coatings and substrate.

Effect of excitation parameters on the motion characteristics of the tailings slurry during vibration dewatering

Fine flotation tailings slurry (FFTS) are potential mines rich in a large number of useful minerals, and the large-scale stockpiling of tailings slurry have caused serious resource waste and environmental pollution. High efficiency dewatering is urgent demand of the FFTS disposal and utilization. In this work, the influence of excitation parameters on the FFTS motion characteristics and dewatering performance was explored during the continuous dewatering by the vibration screen. The results showed that the slurry concentration along the screen surface showed a trend of increasing in steps, and a typical three-region differential dewatering phenomenon appeared. The increase of vibration intensity was conducive to speeding up the motion velocity of the FFTS and avoiding the accumulation of the tailings particles on the screen surface. And the layer thickness on the screen was reduced, which was beneficial to shorten the percolation distance of the liquid. There was a competitive coordination mechanism between percolation distance and dewatering time on the dewatering performance. When the velocity was less than 0.07 m/s, the moisture was reduced by the reduction of the layer thickness, and the dewatering time was not the main factor. When the velocity exceeded 0.07 m/s, the influence of the layer thickness on the dewatering was weakened, the material could not obtain sufficient dewatering time. The dewatering results showed that with the optimal conditions of f = 16 Hz, A = 5 mm and α = 45°, the product moisture reached 19.37 % and the discharge speed was 4.69 t/m2·h. A case study indicated that dewatering for 6000 t FFTS could be completed by 3 vibration screens working 7.67 h per day, and the volume of FFTS was reduced from 2125 m3 to 831.25 m3. The work might provide theoretical and technical support for efficient dewatering of FFTS with environmental benefits.

Analysing the role of a bio-surfactant extracted from Colocasia esculenta (L.) Schott on the stabilization of high concentrated iron ore slurry for transportation

ABSTRACT. The transportation of minerals/ores in form of slurry through pipelines is an alternative, effective and also eco-friendly mode of transportation. Surfactants extracted from the plant sources are gaining high interest for the formulation and stabilization of high concentrated solid-water slurries. In this work, the role of a novel bio-surfactant extracted from Colocasia esculenta (L.) Schott on the stabilisation of iron ore slurry (IOS) was studied and reported first time. The collected iron ore powder (IOP) and dried IOS samples were analysed with the help of XRF, XRD, SEM and EDS analysis. The results confirmed that the surfactant molecules (present in aqueous Colocasia esculenta (L.) Schott) coated well on iron surface and forms an effective barrier between the iron ore (IO) particles. The studied rheological parameters for the slurry indicated non-Newtonian flow behaviour.
 KEY WORDS: Iron ore slurry, Colocasia esculenta (L.) Schott, XRD, SEM, rheological measurements
 Bull. Chem. Soc. Ethiop. 2023, 37(6), 1459-1470. DOI: https://dx.doi.org/10.4314/bcse.v37i6.13

Temporal characterization of biogas slurry: a pre-requisite for sustainable nutrigation in crop production

Biogas slurry serves as a useful organic fertilizer due to its substantial nutrient content, and its characterization enables the evaluation of nutrient content and its efficient utilization. This study focuses on the variations in the nutrient content of biogas slurry from different dairy farm systems located near the ICAR-Indian Agricultural Research Institute (IARI) (New Delhi), Daryapur Kalan (New Delhi), and Madanpur (Uttar Pradesh) during the pre-monsoon, monsoon, and post-monsoon seasons. The study reveals significant variations in macronutrient levels, particularly nitrogen (N), which showed variations exceeding 3% and a wider range of almost 6% during the pre-monsoon and post-monsoon periods. Spatial differences between dairy farms also contributed to the variance, with more than 10% differences observed between IARI and Daryapur Kalan and between IARI and Madanpur. Phosphorus (P) remained stable across seasons with spatial variation, while potassium (K) exhibited a reverse trend. Correlation analysis highlighted strong positive associations between N content and phosphorus (0.959), organic carbon (0.954), pH (0.813), and electrical conductivity (0.806). The findings suggest the use of biogas slurry has a potential to reduce the synthetic fertilizer consumption of N, P, and K by approximately 8.78%, 11.01%, and 14.33%, respectively and using them for further for nutrigation.

Thermodynamic and environmental analysis of self-thermal antibiotic residues supercritical water gasification system for hydrogen and power production

Efficient treatment of antibiotic residue, containing a range of persistent organic compounds, is essential to ensure the protection of both the environment and human health. Supercritical water gasification technology could achieve the clean and efficient energy conversion of antibiotic residues. In this paper, a self-thermal supercritical water gasification system for antibiotic residues is developed to convert antibiotic residues to high-purity H2 and electrical power. The system analysis results demonstrate that increasing the antibiotic residue slurry concentration, elevating the gasification reactor temperature, and optimizing the ratio of water-to-dry antibiotic residues effectively enhance system efficiency and H2 yield within specific ranges. The H2 yield and net electrical power at optimal operating conditions are 634.52 kg/h and 2.3 MW with 10 t/h dry antibiotic residue feeding. Meanwhile, the energy efficiency, exergy efficiency, and cold gas efficiency of the system are 61.32%, 63.05%, and 53.96%, respectively. The life cycle assessment analysis shows that the global warming potential of the system is 20.77 kg CO2-eq/kg H2 with the above operating conditions. Taking into account the emission reduction impact of the system on thermal power generation, the inclusion of CO2 capture and storage units can potentially lead to a negative global warming potential for the system.

Structural evolution of bed drainage channels under the shear effect of the whole process of tailings thickening

Cemented paste backfill (CPB) technology has the advantages of safety, environmental friendliness, economics, and efficiency. This method offers assurances for practical underground mining and tailings pond management. The bed drainage channel structure and coarse particles with diameters above 45 μm were reconstructed and quantitatively characterized in 3D by computed tomography (CT) for the whole tailings thickening process. The spherical pore diameter evolution trends, stick throat channel radius and throat channel length were analyzed with and without shear using the pore network model (PNM). The functional relationship between the average spherical pore diameter and bed pressure is given, and the boundary values between the bed’ primary and secondary drainage channels are clarified. The ratio of throat length to diameter (Tw) is proposed to measure the difficulty of throat channel structure on the water discharge in the bed. The effects of the volume and number of coarse particles with diameters above 45 μm on the bed porosity and pore connectivity were analyzed. The range of particle diameters that significantly affect the bed porosity and pore connectivity was clarified. The results show that the spherical pore diameter, throat channel radius, and throat channel length decrease with increasing bed pressure with and without shear. Moreover, the average spherical pore diameter in the bed has a power-law relationship with the bed pressure. The spherical pore diameter, throat channel radius, and throat channel length with shear were lower than without shear, and the slurry concentration was higher than without shear. The main drainage channels of the bed with and without shear consisted of large pore structures with diameters of not less than 433.3 μm and 329.8 μm, respectively. The throat channel structure parameter Tw increases with the increase of bed pressure. When Tw is higher than 8.7, the discharge of water in the bed is hindered, making it challenging to improve the slurry concentration. The porosity and pore connectivity of the bed decreases with increasing volume and number of coarse particles. Among them, coarse particles in the diameter 150–300 μm range significantly reduce the bed porosity and pore connectivity. This study guides the preparation of high-concentration paste filling slurry, which is helpful to improve the efficient mining capacity of mines and have fewer tailings ponds.

Numerical optimization of hydrothermal liquefaction process for the production of bio-oil and bio-char from Citrus maxima peel waste and product characterization.

This research study aims to potential utilization of Citrus maxima peel waste and optimize the hydrothermal liquefaction process for the production of bio-oil (BO) and bio-char (BC). The effect of several HTL processing variables on BO yield (%) and BC yield (%), including temperature, retention period, and slurry concentration, has been examined using central composite design (CCD) (a three-level three-factor design). The optimized values of HTL process variables were found to be 240°C (temperature), 52min (retention time), and 7% (slurry concentration) and the corresponding responses were 5.794% (BO yield) and 29.450% (BC yield). The values obtained from the RSM-CCD model as the predicted values agreed with the experimental values (5.93% and 30.14%). Further the BO and BC obtained under optimized conditions and CPP were analyzed to identify the variations by 1H-NMR, GC-MS, FT-IR, and CHNO-S.

Fluoride Concentration, Antibacterial Effect, and Cytotoxicity in Children's Toothpaste: In Vitro Study

Abstract Objectives The aim of this study is to evaluate the effect on cell viability, antibacterial activity against cariogenic bacteria, and total fluoride availability of commercially available children's toothpastes in Thailand. Materials and Methods Seven toothpaste slurries were prepared from seven commercial toothpastes for children. Total fluoride concentration was determined. The agar diffusion method was used to examine the antibacterial effect of toothpaste against Streptococcus mutans. The viability of L929 mouse fibroblasts exposed with different concentrations of each toothpaste slurry was tested by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide) assay. Statistical Analysis One way analysis of variance (ANOVA) and Tukey's honestly significant difference (HSD) tests were used for zone inhibition analysis. Cell viability data were analyzed using Student's t-test. Results Fluoride concentration in fluoride-containing toothpastes ranged from 521.36 to 1,377.83 ppm. Two toothpastes exhibited a similar level of fluoride concentration compared between the product labels. Other toothpastes showed a difference or slight difference in fluoride concentration between the companies' information and our data. The zone of inhibition ranged from 0 to 2.08 cm. A significantly higher zone of inhibition was observed in toothpastes with sodium lauryl sulfate. The concentration of toothpaste that reduced cell viability to less than 50% of the control was 0.8, 3.1, 6.3, 6.3, 25, and 100% for Fluocaril Deli Fruity, Oral-B Junior 6 + , Kodomo Kids, CUdent Stevia, SunStar GUM, and Kindee Organic, respectively. Conclusion The examined children's toothpastes can inhibit the growth of S. mutans, which did not correlate with fluoride concentration. The antibacterial effects could be the results of other ingredients, for example, sodium lauryl sulfate.

Investigation of flocculation behavior of tailings during settling-concentration: influence of true density, particle size, and mud layer height

The rapid concentration of tailings is a crucial initial step in the cemented paste backfill (CPB) process, as it ensures the stability of the backfilling slurry concentration and the continuity of the backfilling process. The structure of flocs plays a pivotal role in tailings concentration, directly contributing to such critical technical parameters as settling speed and bottom flow concentration. However, most of the current studies focus on flocculant addition rather than the tailings slurry itself. Also, there is a lack of uniform characterization of the flocculant structure in the flocculation and settling system. This study establishes a semi-quantitative assessment system for evaluating the fine structure of tailings flocs based on indicators such as the exposure state of coarse particles, floc size, and floc compactness (porosity). The findings reveal that, during the settling process, the higher true density of tailings (3.156 g/cm3) and intermediate particles (40 wt% of 38 μm–74 μm particles) attenuates the clamping effect of turbulence on settling, leading to a faster settling rate to 0.65 cm/s and 0.29 cm/s respectively. Moreover, in the thickening process, tailings located at the bottom of the mud layer expedite the precipitation of interstitial water within the floc structure through the combined influence of gravity and rake frame shear. Consequently, a denser floc structure forms, as evidenced by a higher concentration of bottom flow at a macroscopic level. This conclusion provides a theoretical basis for faster preparation of highly concentrated tailings slurry in CPB.

Experimental investigation on the supercritical water gasification of coal by integrating the hydrogen oxidation process into a supercritical water fluidized bed

The autothermal gasification process is crucial for the industrial application of supercritical water gasification (SCWG) in a supercritical water (SCW) fluidized bed. However, researchers often consider providing external heat to investigate the gasification process and seldom achieve autothermal gasification. Herein, the hydrogen oxidation process was integrated into an SCW fluidized bed to provide heat for the gasification process and to investigate gasification results under various experimental conditions. Using this method, a carbon gasification efficiency of 98.6% and a H2 yield of 68.03 mol/kg were obtained at an experimental temperature of 690 °C. After the gasification products were partially oxidized in the oxidation zone, a H2 yield of 13.6 mol/kg and a total carbon content of <10 ppm in the liquid products were obtained. Compared with the uniform electrical heating method, the heating method based on the hydrogen oxidation process in SCW has obvious advantages, can improve the coal slurry concentration and mass ratio of coal to SCW in the reactor, and maintain a milder temperature under near-complete gasification conditions. This work provides a basis for heat supply in the industrial application of SCWG technology.

Experimental Study on Dense Settlement of Full-Tail Mortar under Mechanical Vibration

There are some problems in the application of slurry preparation technology, such as wide fluctuation range of underflow concentration, long settling time and low efficiency of solid–liquid separation. This is an important basis for researching the thick settling law of tailings slurry under the action of mechanical vibration and its influencing factors to solve these problems. To this end, a small vibration thickening testing machine and vibrating rod were designed and developed. Physical simulation experiments were conducted to analyze the settling characteristics of tailings slurry under different vibration duration, start time, vibration frequency, and vibration inertia single factors. The results show that: (1) Mechanical vibration can effectively accelerate the settling speed of tailings particles, but the relationship between them is a non-positive correlation, and mechanical vibration time control with in 5 mins is the best. With the delay of starting the vibration time, the final mass concentration first increases and then decreases. (2) As the vibration frequency increases, the final mass concentration of tailings settlement first increases and then decreases. When the eccentric vibrator speed is 6000 r/min, the best slurry settlement effect is achieved. (3) When the vibration inertia of the eccentric oscillator is 0.158 g·cm2 and the final mass concentration reaches 70.1%, the settling time only takes 210 min. (4) The lower the slurry concentration, the faster the settling speed. As the initial concentration increases, the final thickening time is also gradually prolonged. The research results provide some insights for the rapid thickening technology of rake-free paste thickeners.

Evaluation and mechanism of ultrasound-assisted electrochemical desulfurization using citric acid as the electrolyte solution

ABSTRACT Achieving the clean utilization of coal is the priority of the coal industries. This paper proposed an efficient electrochemical technology for coal desulfurization before combustion. It was explored that citric acid can chemically provide enough acidic conditions for desulfurization reactions, and the ultrasonic-enhanced treatment physically helps to remove sulfur from coal due to its cavitation effect and mechanical effect. So the experiments of ultrasound-assisted electrochemical desulfurization using citric acid as the electrolyte solution were conducted. They combined physical and chemical methods to effectively remove sulfur from coal. The optimal operating parameters of the desulfurization effect were achieved by qualitative and quantitative analysis of coal samples(coal slurry concentration of 66 g/L, electrolysis time of 8 h, electrolyte concentration of 1.5 mol/L, electrolysis voltage of 4 V, electrolysis temperature of 30°C, ultrasonic strengthening time of 1 h and ultrasonic intensity of 320 W.). The total sulfur removal efficiency reached 45.09%. The electrolytic desulfurization experiments removed samples’ sulfur contents, ash contents, and water. The crystal structures of gypsum, white iron ore, zinc sulfide, and the molybdenite mineral composition were also destroyed for purification. Gaussian simulations showed that C-S bonds and S-S bonds contained in non-thiophene organic sulfur are easier to remove, and S-S bonds are more likely to break than C-S bonds. This study realized the promotion of desulfurization with the ultrasonic wave and citric acid solution. It provides a new idea of synergistic desulfurization and is beneficial to reduce atmospheric sulfur pollution.

Reducing transport resistance in highly concentrated fine-grained slurry pipelines by vibration-induced fluidization

Reducing the resistance in slurry pipeline systems is a major concern in dredging projects because of its high energy consumption, which can reach up to 80% of the total energy consumed. In this study, a resistance reduction method (a vibratory resistance reducer) for highly concentrated fine-grained slurry pipeline transport based on vibration-induced fluidization was introduced. Further, the major factors influencing the resistance reduction were quantitatively explored through slurry pipeline transport tests. The experimental results show that the proposed method significantly reduces resistance in the slurry pipeline. The resistance loss reduction rate increases with the vibration frequency and an optimal vibration frequency exists for the resistance reduction. Moreover, vibration-induced fluidization results in a higher resistance reduction for a smaller transport capacity of the pipeline. For silt and fine sand, coarser slurry particles have smaller optimal vibration frequency, and higher resistance reduction rate of slurry pipeline transport under a certain vibration frequency. Finally, using the experimental data, an empirical formula for estimating the resistance loss reduction rate of slurry pipeline transport using a vibratory resistance reducer was proposed.

Numerical Study of Resistance Loss and Erosive Wear during Pipe Transport of Paste Slurry

Cemented paste backfill (CPB) as a solid waste treatment technology that prepares tailings as aggregate into a highly concentrated slurry to be transported to the underground mining area, is now widely used in mines. However, the pipeline resistance loss and erosion wear during CPB slurry transportation considering the coupling effect of inlet velocities, viscosities, and particle sizes have not yet been well evaluated and analyzed. Hence, the CFD-based three-dimensional network simulation of CPB slurry flow in an L-shaped pipe at different combinations of the three parameters was developed using COMSOL Multiphysics software. The results showed that the pipe resistance loss was most affected by the inlet velocity and viscosity, with the minimum pipe resistance loss occurring at an inlet velocity of 1.5 m/s, a viscosity of 2.0 Pa·s, and a particle size of 150 μm. In particular, pipe erosion wear was severest at the bend and was positively correlated with inlet velocity and particle size, and negatively correlated with slurry viscosity, with maximum pipe erosion wear occurring at an inlet velocity of 3.5 m/s, a viscosity of 3.0 Pa·s, and a particle size of 2000 μm. The findings would be important for the design of the CPB pipeline transportation, which will improve the safety and economic level of a mine.

Experimental investigation of hydrodynamical polishing of hard steel alloys using SiC abrasive and modelling with ANN

In this research, the impact of hardness of material, tool angular speed, abrasive particle size, and slurry concentration on surface roughness during the hydrodynamic polishing process is examined. Experimentation is carried out on EN18 and EN31 steels using a drilling machine with a soft tool of polyurethane rubber and slurry (mixture of servo spin oil 12 and SiC) for machining. Taguchi's L18 orthogonal array is designed to find out the optimum process parameters. The results of the experimental investigation and parametric analysis demonstrate that the process variables have a substantial impact on the surface quality, with the abrasive particle size having a greater impact than tool speed, tool hardness, and slurry concentration. The results reveal that the chemical erosion process efficiently eliminates surface layer and the HDP procedure reduces surface roughness. The minimum surface roughness (Ra) is only 0.21 µm. Also, there are few inclusions and flaws on the machined surface. In comparison to material hardness and angular speed, abrasive particle size has a greater impact on surface roughness. Also, artificial neural network a computational technique, is used for better prediction values with a higher coefficient of determination (R2) value.

Response surface methodology (RSM) based analysis on slurry erosion behavior of laser textured and PTFE sprayed VC+TiC coating deposited via HVOF

This research article focuses on investigating the slurry erosion behavior of vanadium carbide (VC) + titanium carbide (TiC) coating deposited via high-velocity oxy-fuel (HVOF) spraying. The study also focuses on examining the potential effects of laser texturing and polytetrafluoroethylene (PTFE) spraying on enhancing the resistance of the deposited coating against slurry erosion. Moreover, the study employs response surface methodology (RSM) to precisely model and optimize erosion behavior across various slurry conditions, while considering key process parameters such as velocity of jet, angle of impact, and concentration of slurry. By utilizing a central composite face-centered design (CCFD) matrix, an empirical correlation between these parameters and resulting mass loss is established. The failure mechanism was also examined using SEM images.