Slurry Solids Concentration Research Articles

Laboratory Investigation of Beach Profiles in Tailings Disposal

Transient beach profiles in tailings disposal are investigated both experimentally and theoretically. The effects of feed solids concentration and total slurry discharge on beach profiles are examined using a plexiglass flume 4.87 m long, 0.31 m wide, and 0.46 m deep. The slurry feed solids concentrations examined are up to 14.1% by weight. It is found that the slope of the beach and the rising rate of the beach at the solids feeding point are much influenced by feed solids concentration. On the other hand, when the feed solids concentration is constant and the total slurry discharge is varied, the slope of the beach does not change significantly. A nonlinear mathematical model is developed to predict beach profiles. The resulting partial differential equation is solved numerically by a simple explicit scheme. Very good agreement between the experimental data and the theoretical prediction is observed. The experimental data are also correlated successfully with a power expression, which is often seen in mining engineering literature.

Measurement of surface tension in agricultural waste slurries

An experimental method to determine the equilibrium surface tension of cattle and pig slurry is described. The surface tension was determined by using a published modification of the “maximum bubble pressure method”: the pressure inside a spherical bubble in excess of its surrounding is measured just prior to its release into a slurry through a capillary; the surface tension is calculated using the well known relation, P = 2σ/ r where P is the maximum pressure, σ is the surface tension and r is the radius of curvature. The method was found to be valid only at slurry solids concentrations of less than 6% by weight, where measurement errors due to slurry viscosity and the influence of solids were insignificant. Slurry surface tension was found to be 0.06 to 0.07 N/m, only slightly lower than water. This method may be applied to other agricultural waste slurries, fermentation broths and domestic sewage.

ChemInform Abstract: Spray‐Drying Ceramic Powders

Spray-drying is a convenient process for producing a granulated, flowable powder of uniform bulk density. In this review the effect of feed slurry solids content, viscosity, binder type, and atomization technique on the granule character are discussed. Also, mechanisms of hollow granule formation and binder migration are reviewed.

WALL SAMPLING FROM HORIZONTAL SLURRY PIPELINES

An experimental study of the errors associated with wall sampling from a horizontal slurry pipeline has been conducted. Experiments were performed for water-sand slurries flowing in a one inch horizontal pipeline. The effects of particle size (0.08 mm to 0.4 mm), upstream slurry solids concentration (4% to 12%, by volume), upstream bulk velocity (1.8 m/s to 4.0 m/s), sampler diameter (4 mm to 25.4 mm), sampler location, and sampling velocity ratio (defined as the ratio of the sampling velocity to the upstream bulk velocity, 0 to 4.5) on the sample solids concentration and sample particle size distribution were examined. The experimental results show that the observed sample solids concentration and its particle size distribution are functions of the sampler location, sampler diameter and sampling velocity. For the case of sampling from the top or from the side of the pipe, the sampling efficiency (defined as the ratio of the sample solids concentration to the upstream solids concentration) was found to be...

Spray‐Drying Ceramic Powders

Spray‐drying is a convenient process for producing a granulated, flowable powder of uniform bulk density. In this review the effect of feed slurry solids content, viscosity, binder type, and atomization technique on the granule character are discussed. Also, mechanisms of hollow granule formation and binder migration are reviewed.

Heat-Transfer Characteristics in Upward Three-Phase Flows of Gas-Liquid-Solid Mixtures

Heat-transfer coefficients in gas-liquid-solid three-phase flows in a 50.8mm i. d. vertical tube were measured in relation to flow patterns such as bubble, slug and penetrant flows. The gas velocity, slurry flow velocity and solid concentration were changed. The heat-transfer coefficients in the bubble and slug flow regime decreased with an increase in slurry flow velocity at low slurry flow velocity, while increased in the penetrant flow regime. The solid concentration greatly influenced the heat-transfer coefficients in all flow regimes, and the maximum value existed at a certain solid concentration.

Gas holdup in a continuous coal-suspended bubble column with annular flow section.

The gas holdup characteristics of a continuous annular bubble column of coal were studied. Coalescence of bubbles occurred more readily in the slurry bubble column than in the air-water two-phase bubble column. The gas holdup eG decreased with increasing slurry flow rate and solid concentration. However, increase of eG with increasing solid concentration was found in a higher range of solid concentration. Considering such an effect related to solid concentration, an empirical correlation for the estimation of gas holdup was derived. The applicability of the previously reported correlations for the slurry bubble column was also studied.

An analysis of the high-frequency screening of fine slurries

High-frequency screen tests of a number of different fine slurries are analyzed to determine the effect of slurry feed rate and weight per cent solids on screen size selectivity values. Results of this analysis indicate that for the screen cloths tested, slurry feed rate has a negligible effect on size selectivity values but that increasing the feed solids concentration causes finer but less efficient particle size separation. The size selectivity data are analyzed to give values for the d 50 , the sharpness index and apparent bypass parameters of a screen size selectivity equation. Approximate empirical relationships between these parameters and screen aperture size and slurry feed solids concentration are given, and an example of the use of the size selectivity equation in grinding-circuit simulations is presented.

Specific Resistance Measurements: Methods and Procedures

A computer‐aided data acquisition system was used with three sludges, two chemical‐conditioning systems and nine support media to investigate the effect of slurry solids concentration on specific resistance, the effect of initial time and filtrate volume readings on filtration data, and factors affecting the precision and accuracy of specific resistance measurements. The results of the study show that: (1) The specific resistance of a flocculent slurry is a very strong function of suspended solids concentration at low concentrations and relatively independent of concentration at high values; (2) improper determinations of the onset of filtration or errors in filtrate volume measurements produce slurry filtration data that do not fit the standard model (nonsynchronous data); and (3) specific resistance values are not as accurate and translatable as they might be because of differences in methods used in different laboratories. Several suggestions for improving the translatability of specific resistance mea...

The kinetics of methyl bromide hydrate formation

The rate of formation of methyl bromide hydrate in a continuous stirred tank reactor has been measured under conditions in which the Δ T driving force, the degree of agitation, the salt concentration in the aqueous phase, the volume fraction of liquid methyl bromide present and the fraction of solids present in the slurry were all varied. As long as the agitation intensity is over 0.01 hp/gal and there is at least 3 volume % liquid methyl bromide present in the reactor, the hydrate formation rate appears to be controlled mainly by the kinetics of the interfacial reaction to form crystals. Under these conditions only 10% to 25% of the total driving force is used to boil the refrigerant while the remainder is consumed by the interfacial reaction. This is in contrast to the butane freezing process where nearly all the Δ T is consumed by boiling of the refrigerant. With a slurry solids concentration of 15% and a Δ T of 2.5°C specific reaction rates are over 60 lbs of water solidified per hour per ft 3 of slurry.