Slurry Water Content Research Articles

Influence of Galvanic Interaction between the Iron Grinding Medium and Chalcopyrite on Collectorless Flotation Behavior of Chalcopyrite: Experimental and Density Functional Theory Study.

The eco-friendly flotation process for chalcopyrite is economically significant and promotes sustainable development in mining. Collectorless flotation is a green and clean method for chalcopyrite utilization, but galvanic interactions during the grinding process can affect the surface structure, chemical composition, and electrochemical properties, impacting collectorless flotation recovery. This article uses a self-made device and flotation experiments to study galvanic interactions and their effects on surface oxidation and collectorless flotation behavior under different grinding conditions (including mineral particle size, slurry water content, pressure, and galvanic interaction time). The impact of galvanic interaction on the surface chemical composition and electrochemical properties of chalcopyrite is studied using high-performance liquid chromatography (HPLC), X-ray photoelectron spectroscopy (XPS), and electrochemical tests. Additionally, the effect of the galvanic interaction on the surface structure is analyzed with density functional theory. XPS and HPLC results show that iron grinding media contact with chalcopyrite, reducing elemental sulfur content of the chalcopyrite surface, improving hydrophilicity, and decreasing chalcopyrite collectorless flotation recovery. Grinding conditions, such as mineral particle size, slurry water content, and galvanic interaction time, significantly impact collectorless flotation and can be regulated to optimize results.

Small-Strain Characteristics of Reconstituted Soils: The Effect of Slurry Water Content and Fabric Anisotropy

Abstract Determination of small-strain properties of soils is essential for many geotechnical applications. Reconstituted specimens have conveniently been used to characterize small-strain properties of cohesive soils in the laboratory. In this study, the influence of slurry water content (ws) and fabric anisotropy on the small-strain properties of reconstituted kaolinite and illite specimens was investigated. Bender elements were employed, within triaxial testing equipment, to obtain vertically propagated, horizontally polarized, shear wave velocity measurements and corresponding shear moduli during the consolidation stage of undrained triaxial compression tests. The soils were initially prepared at water content values of one and one-half (1.5×) and three (3×) times the respective liquid limit for each soil type. The shear wave velocity and shear modulus data were normalized to the void index by following a procedure that was similar to procedures that have previously been used to normalize compression and undrained shear strength data. Unique “intrinsic” relationships for shear wave velocity or shear modulus, independent of soil fabric, were not observed during this study. Inherent fabric anisotropy was also assessed by comparing the aforementioned triaxial shear wave velocity data to measurements of horizontally propagated, vertically polarized, shear wave velocity that were obtained by utilizing bender elements within a consolidation device. The amount of fabric anisotropy was dissimilar and the characteristics of the cross-anisotropic fabric were not observed for the specimens. The amount of inherent fabric anisotropy (Vs,HV/Vs,VH) ranged from 0.63 to 0.97 for the kaolinite and illite specimens with ws values of 1.5× the liquid limit and ranged from 1.13 to 1.21 for kaolinite specimens with ws values of 3× the liquid limit. During the shearing stage, inconsistent and unreliable relationships were obtained for the shear wave velocity-vertical effective stress behavior and shear modulus-axial strain behavior. As discussed herein, the ws level should be considered when reconstituting soil specimens for small-strain stiffness determination.

Effect of fly ash addition on slurry dewatering by electro-osmosis combined with mechanical pressure

In this study, fly ash was used as an additive to increase the dewatering efficiency of an excavated soil slurry treated by electro-osmosis combined with mechanical pressure and thus effectively obtain a low-moisture treated slurry with wider applicability; the properties of the treated slurry were also studied. The results showed that, at a fly ash dosage of 5%, the drainage volume was 350 mL, which presented significantly better dewaterability properties than the unconditioned slurry, the water content of the anode and cathode layer after treated was 20.5% and 19.1%, the compressibility coefficient was 0.170 MPa−1 and 0.152 MPa−1, and the shear strength was 81.2 kPa and 85.1 kPa, respectively. And we also studied the physical properties of the treated slurry at different locations, the physical properties were also affected by the fly ash dosage. It was concluded that fly ash used in adequate concentrations can reduce the slurry water content, and fly ash also can improve the mechanical properties of excavated soil slurry after the mechanical dewatering combined with electro-osmosis.

Numerical simulation of semi-dry flue gas desulfurization process in the powder-particle spouted bed

Computational fluid dynamics (CFD) combined with the two-fluid model (TFM) was used for simulation of water vaporization and semi-dry flue gas desulfurization process in a two dimensional powder-particle spouted bed (PPSB), on the basis of gas-solid two-phase flow, the mathematical and physical models of water vaporization process and flue gas desulfurization reaction process have been established through reasonable hypothesis and simplification of the system. The numerical method was used to simulate the desulfurization reaction process and the heat and mass transfer in the powder-particle spouted bed. Simulation results indicate that water vaporization rate was high in spout and annular regions. The main area where flue gas desulfurization reaction occurs was annular area, as a result, the maximum value of desulfurization product rate appears in the annulus. Under the same condition, the desulfurization efficiency of simulation value is 75.75% when the value of slurry water content equals 40 kg-H2O/kg-dry_sorbent, which is close to but greater than the experimental value (75.03%). The desulfurization efficiency of spouted bed increases first and then decreases with the increase of water content of desulfurization slurry, and the optimum slurry water content for desulfurization process in powder-particle spouted bed was obtained by numerical simulation, which was 40 kg-H2O/kg-dry_sorbent.

The structure of spray-dried detergent powders

The complex multiscale structure of spray dried detergent granules has been characterized using a complementary range of techniques including scanning electron microscopy (SEM), image analysis, wide angle and small angle X-ray scattering (WAXS, SAXS) and X-ray microtomography. A complex composite structure is revealed due to the multiphase nature of the starting slurry and its evolution during the drying process. Four simple model formulations based on linear alkylbenzene sulphonate (NaLAS) and sodium sulphate were used to probe the influence of initial slurry water content and binder, sodium silicate (SiO_2:nNa_2 O), on the structure. The structure revealed can be viewed as a continuous matrix consisting of NaLAS, sodium sulphate and binder in which large, dense, crystals of sodium sulphate are embedded. These large crystals were initially undissolved in the slurry and are consequently reduced in number in the product made from higher water content slurry. Air is also dispersed in this matrix at two length scales, large vacuoles, typically larger than 0.1x the particle diameter driven by ‘puffing’ i.e. water boiling, and micro-scale porosity which evolved during the crystallisation of the drying matrix. The matrix is formed from the dried slurry liquid phases and is a composite structure of binder, dried surfactant liquid crystalline phase and sub-micron scale crystallites of sodium sulphate. The liquid phase compositions change with the slurry water content, as well as the addition of binder; this changes both the sulphate polymorphs present and the spacing of the liquid crystalline lamellae, i.e. d-spacing, of the NaLAS phase. The composition and crystalline structure of the surface is also affected. The particle morphology can also be significantly affected with the high initial moisture content particle having a distinct agglomerated and blistered structure. The multiscale influence of formulation on particle structure, and consequently product properties and performance, highlights the challenge in predictive design of these important detergent products.

Numerical modeling of an E-Gas entrained flow gasifier to characterize a high-ash coal gasification

In this paper, a three-dimensional numerical simulation was carried out to characterize a high-ash coal gasification in a pressurized, oxygen-blown, two-stage E-Gas entrained flow gasifier. The Tabas coal was used as a high-ash feedstock, with 32wt% ash and was compared with the Illinois #6 low-ash coal, with 10wt% ash. The computational model was conducted in ANSYS FLUENT 14 based on the conservation equations described in the Eulerian–Lagrangian approach. Also, four heterogeneous combined with seven homogeneous reactions were solved via the finite rate and eddy-dissipation/finite rate model, respectively. Two different parametric analyses were conducted to characterize the gasification process in the E-Gas gasifier. These analyses cover the effects of the O2/Coal ratio and coal slurry water content on the gasifier performance characteristics such as the exit temperature, main species mole fractions, carbon conversion, high heating value, yield syngas fraction and cold gas efficiency. It was found that using the higher ash content coal decreases the cold gas efficiency about 5%, limits the gasifier economical operating range, and reduces the exit temperature, yield syngas and total higher heating value.

Simulation analysis of hybrid coal gasification according to various conditions in entrained-flow gasifier

Today, as more and more power is required globally, securing a sufficient supply of energy is very important. Coal is one of the energy resources that may be useful in solving the energy crisis. Currently, we have to reduce greenhouse gas emissions. Coal gasification is one of the methods that use coal and at the same time solve the climate problem. This technology produces synthesis gas, which is composed of hydrogen, methane, and carbon monoxide, from coal through procedures of drying, pyrolysis, and gasification. In this study, KIDECO coal (HCK raw coal) and hybrid coal (biomass/coal = 10 wt%) were mixed with water to make a coal slurry. Hybrid coal is a fuel combining coal and sugarcane derived from bioliquid. Transportation of the coal slurry, which is related to slurry viscosity, was considered as an aspect of energy efficiency. Viscosity experiments were performed on the KIDECO coal and hybrid coal by Korea Institute of Energy Research (HCK coal) using a viscometer at 40, 50, and 60 wt% of water content. Simulation analysis was performed by the Aspen Plus program. In this study, the entrained-flow gasifier is the proposed basic model for simulating gasification of HCK raw coal and HCK coal. The carbon conversion and the cold gas efficiency were also calculated to analyze the energy efficiency. Sensitivity analysis was performed according to various conditions such as slurry water content, oxygen ratio, operating temperature, and operating pressure to investigate the process characteristics after verifying the basic model.

Noisy-power dissipation and efficiency in NiO/Fe2O3 wet grinding by planetary ball mill

The relationship between the efficiency of NiO/Fe2O3 wet grinding and noisy-power dissipation was studied. The optimal grinding parameters were found as: a slurry water content of 64.10%–85.47%, ball number ratio of 360/20, revolution speed of 300.9 r/min, powder-filling ratio of 10.88%, ball-filling ratio of 20.53%–23.88%, and grinding time of approximately 6 h. The discrete element method (DEM) was employed to analyze relationship between the noisy-power dissipation and the grinding efficiency, and equations describing the relationship were derived. The mean particle size of the ground powder decreased with a decrease in the degree of noisy-power dissipation, while the grinding efficiency and the amount of specific impact power used decreased with an increase in the degree of noisy-power dissipation.

A chemometric investigation of the effect of the process parameters on the performance of mixed Si/C electrodes

Silicon composite anodes are attractive candidates to replace present day carbonaceous anodes. In particular, silicon possess the highest theoretical capacity in an appropriate potential window, it is abundant and environmentally friendly. The present work consists of a systematic investigation of the influence of parameters during composite electrode fabrication. The following factors have been considered: SBR content, CMC content, slurry water content, drying temperature, and pressing force. A full factorial 2 5 experimental design was applied, considering two response variables: achieved cycle number at fixed capacity cycling test ( y 1), and maximal observed coulombic efficiency ( y 2). All statistically significant factors and their interactions have been identified.

Concentration of pig slurry by evaporation: anaerobic digestion as the key process

Nutrient redistribution between areas with a structural pig slurry surplus and those with a shortage, is limited by the high cost of transportation and spreading, due to the high water content in slurry (more than 90%) and its relative low nutrient concentration. Water can be removed from slurry by evaporation, through the application of waste heat from a power plant or from other processes. Apart from obtaining a concentrate with an obviously higher nutrient concentration than the original slurry, another objective is to obtain clean water as condensate. The objective of this work was to study the batch vacuum evaporation of pig slurry liquid fraction, to evaluate the economic feasibility and to evaluate condensate quality as a function of both pH (4, 5 and 6) and pig slurry type (fresh slurry and anaerobically digested slurry). Results showed that condensate characteristics (ammonia nitrogen, VFA, COD) were strongly dependent on these variables. Previous anaerobic digestion presented clear advantages: it provided a fraction of the required energy and it removed organic matter, preventing its volatilisation in the evaporation process and providing higher quality condensates. These advantages make the combined treatment strategy economically more feasible than the evaporation process alone.

Flowable Slurry Containing Foundry Sands

This research was carried out to evaluate the use of foundry sands on properties of flowable slurry. Two different flowable slurry mixtures were proportioned for strength levels in the 0.34-0.69 MPa (50-100 psi) range, at 28 days, using two different sources of foundry sand and two different sources of ASTM Class F fly ash. Flowable slurry mixtures containing fly ash, without any foundry sand, were used as reference mixtures for this investigation. For each reference mixture, additional mixtures incorporating clean and used foundry sands as a replacement for fly ash were also proportioned. These flow able mixtures made with and without foundry sand were evaluated for bleeding, depth of nail penetration, settlement, shrinkage, condition of set, etc. In general, bleed water increased with an increase in the added mix water or foundry sand content of the mixtures tested. The settlement decreased with a decrease in the slurry water content. All the test specimens showed no sign of shrinkage cracks. The depth of nail penetration decreased with increasing age or decreasing water content. Compressive strengths of the test mixtures were found to vary between 0.28 and 0.62 MPa (40-90 psi) at 28 days. The overall results showed that excavatable tlowable slurry with desirable physical properties can be manufactured using foundry sand as a replacement for fly ash up to 85%.

Qualitative Analysis of Oil Sand Slurries Using On-Line NIR Spectroscopy

The development of a reliable on-line method to monitor process streams is important for improved process control in oil sand extraction plants. The suitability of diffuse reflectance near-infrared (NIR) spectroscopy for this purpose has been tested in a pilot plant environment. Spectra of a feed slurry flowing through a pipe were measured with the use of an on-line fiber-optic probe. Data were collected throughout a nine-hour period during which ore type and slurry water content were varied. The feasibility of monitoring feed stream conditions is demonstrated by principal component analysis of the measured spectra. Clustering of these spectra according to ore type and water content enables the detection of deviations from and transitions between steady-state conditions of the process. Estimates are given of characteristic times for the process to reach a steady state after a change in condition has been initiated. The use of artificial neural networks for classifying spectra on the basis of ore type is also illustrated.

The Role of Jute Geotextile/Slurry Interface Friction on the Bearing Capacity of Clay Slurry

Abstract The layered clay-sand scheme of land reclamation depends on the successful formation of sand seams sandwiched between hydraulically placed layers of marine clay slurry to provide shorter drainage paths for rapid clay consolidation during surcharge application. It is anticipated that a low-cost jute geotextile placed on a clay slurry surface without anchorage will expedite construction of sand seams by providing support for the thin sand layers and preventing penetration of sand into the clay slurry. In this application, the interface friction between the very soft clay slurry and the jute geotextile plays a major role in determining the support for the thin sand seam. This paper discusses measurement of the jute/slurry interface friction by incremental vertical penetration of a thin, end-weighted jute sheet under an incremental load to obtain the interface stress value under a quasistatic condition. The effects of sheet width and sheet type were investigated and found to be negligible on the measured interface friction for the clay slurry water content range tested. The results of the interface friction for the 500 g/m2 jute geotextile is then applied to a rectangular loaded area with a jute base on clay slurries of 150 to 300% water content. These water contents are the likely range of values to be encountered in field applications. The load test results indicate that the measured bearing capacity for the jute on clay slurry is about 5.5 to 6.5 times the interface friction, which is in close agreement with typical bearing-capacity factors used in a shallow foundation on clays.

Computer Control of Raw Material Blending for the Cement Industry

The principles of blending control are explained with particular reference to a control scheme currently being implemented by G.E.C. Computers & Automation Ltd. for Skanska Cement AB at their Limhamn cement works. The control principles can, however, be applied to other blending plants. The Limhamn blending process is briefly described in order to give an appreciation of the control problems involved. The computer, instrumentation and X-ray analysing systems are outlined. The iterative optimiser is explained. This calculates set points for the material flows which, when implemented, result in manufacture of slurry with correct chemical composition at minimum cost. On-line regulating techniques which control the blending machinery are described. The regulating programmes maintain material flows at their calculated set point values. They also control water addition in order to keep slurry water content constant. Distinct advantages are to be obtained by the separate implementation of the optimising calculations or the regulating control, but the two are complementary, and to obtain maximum benefits, a computer control scheme should include both.