Amount Of Fine Material Research Articles

Determination of Abrasiveness in Copper-Gold Sulfide Ores: A Contribution to the Geometallurgical Model of the Sossego Deposit

The geological context of this study is established in the iron oxide-copper-gold (IOCG) deposit of Sossego (Canaã dos Carajás, Brazil), where hydrothermal alterations in shear zones concentrated the metals of interest and added new characteristics to the metavolcanic-sedimentary and granite rocks. The mineral transformation of rocks by hypersaline fluids enriched in metals and silica also modifies some metallurgical properties, such as abrasiveness. Special bench tests on rock drill cores are used in mapping the abrasiveness of rocks, with the Bond abrasion test being more commonly used in the mining industry, but it has a restrictive sampling protocol and mass requirement for geometallurgical studies. As a counterpoint, the test of the Laboratoire Central des Ponts et Chaussées/Central Laboratory of Bridges and Roads (LCPC) requires a smaller amount of fine material and a finer granulometric range. The study on the use of LCPC was implemented in 40 samples, using Bond Ai as a reference. The results showed a strong correlation between both methodologies (R2 = 95%), validating the use of LCPC to quantify abrasiveness in the Sossego mine. It was also possible to classify the most abrasive lithologies.

Development of a Novel Viscosity Modifier Agent for Cementitious Materials: Preliminary Study

AbstractConcrete compositions demand products in order to meet certain requirements and specific properties. For the production of self-compacting concrete, a certain amount of fine materials and/o...

Calcination thermokinetics of three Brazilian limestones

Abstract Limestone and lime producers inadvertently generate a considerable amount of fine material during their processing, consequently becoming a great environmental liability. As far as the industrial calcination process is concerned, there is still a need for an experimental survey on Arrhenius law parameters, as apparent frequency factor and activation energy, referring to Brazilian limestones. The knowledge of these thermokinetic parameters may contribute to energy saving during the industrial calcination process, as well as for allowing the use of limestone fines in other industrial applications. This study aimed to characterize three Brazilian limestones by focusing on their laboratory-scale calcination using both quasi-isothermal and non-isothermal methods to estimate their kinetic parameters. The non-isothermal method (by thermogravimetric analyses) allowed estimating the activation energy for each limestone through the high calcination rate ranges. However, the kinetic parameters estimated by the quasi-isothermal method turned out in lower values, indicating the need to control the reactor atmosphere.

Using Small-scale Blast Tests and Numerical Modelling to Trace the Origin of Fines Generated in Blasting

Waste fines from rock breakage often negatively influence economics and environment. The Austrian Science Fund (FWF) sponsors a project to investigate the cause of the fines by studying blast fragmentation throughout small-scale blast tests and numerical simulations. The tests include blast-loading confined granite and mortar cylinders by detonating cord with 6, 12, and 20 g/m of PETN. The blast-driven dynamic cracking at the end face of the cylinder opposite to the initiation point is filmed with a high-speed camera. The filming is followed up by an analysis of surface and internal crack systems and sieving of the blasted cylinders to quantify the amount of fine material created. The numerical simulations cover the blast fragmentation of a mortar cylinder. These simulations use Finite and Discrete Element Methods (FEM, DEM) with explicit time integration. The model cylinders are loaded by a pressure evolution acting on the borehole wall. Both methods produce realistic crack patterns, consisting of through-going radial cracks with crack intersections around a crushed zone at the borehole. Furthermore, the DEM models have also yielded realistic fragment size distributions (FSD). The paper covers the present progress of the ongoing project and related future work.

Determination of the Plasticity Index of Soils with Fine-Grained Soils Using Methylene Blue Test

The amount of fine material available in the soil is significant in Atterberg limits and methylene blue tests. In the context of Atterberg limits, increased amount of clay minerals contained in the soil increases liquid and plastic limit values; however, increasing sand content reduces the moisture content reducing the water retention capacity of the soil which in return reduces the plasticity index (PI) value. In the case of methylene blue test, which is used to specify the quality of the amount of fine material, existence of clay in the medium increases the pollution level of the sand and the amount of methylene solution (V1) used. In this study, soil classes were determined and pollution rates were identified with Atterberg limits, pycnometer, sieve analysis, hydrometer analysis and methylene blue tests conducted on 11 different natural soil samples collected from different regions. From the data obtained, first the relationship between PI and methylene blue (MB) was examined and was evaluated according to the results of the “single regression” method. Furthermore, the other coefficient of uniformity (Cu), coefficient of graduation (Cc), unit weight of soils (γs) parameters obtained from experimental studies were also subjected to “multiple regression analysis” in order to reveal their impact on the MB and this impact was confirmed taking both statistical analyses into account.

Effect of riverbed conditions on survival of planted eyed eggs in chum salmon Oncorhynchus keta

Wild stocks of chum salmon Oncorhynchus keta are supplemented by hatchery fry enhancement programs in northern Honshu, Japan. To maintain these programs, there is a need to reduce expenses and labor. Eyed egg planting is more cost effective than hatchery production of fry. Therefore, we evaluated the effect of environmental conditions on survival of chum salmon eyed eggs planted using Whitlock–Vibert boxes. We measured the percent cumulative weight of fine sediments, Fredle index (FI) as a measure of permeability, vertical hydraulic gradient, water depth (WD), and flow velocity at planting locations. Egg-to-fry survival averaged 92.7% (range: 57.2–100%) in 2013 (N = 19) and 71.5% (range: 6.4–100%) in 2014 (N = 23). Survival was significantly positively correlated with FI and flow velocity, negatively associated with percent cumulative weight of fine sediments and WD. Vertical hydraulic gradient had no effect on survival. Our results suggest that a higher FI (i.e., low amount of fine material and larger particle size), higher flow velocity, and shallower WD reduce the mortality of planted chum salmon eyed eggs. This is likely a result of increased permeability in the substrate and restriction of fine sediment intrusion into the incubation zone.

Stability of Solution Cavities in Urban Developments: A Case Study Towards Enhancing Geohazard Risk Assessment

Karst cavities in fissured soluble rock represent serious geotechnical hazard for civil construction and urban development. The process of cavity formation, expansion, and propagation is difficult to predict because it is driven by a combination of diverse causes, such as the dissolution rate of rock; flow of groundwater; amount of fine material within rock layers; presence of loose, uncontrolled fill over the rock; and the leakage of underground utilities. Several factors can affect cavity stability, including cavity geometry and dimensions, cavity depth, overburden surface-layer lithology, and surface-loading conditions. This paper presents a case study for karst cavities stability in the Abu Dhabi Municipality (ADM) of the United Arab Emirates as part of a comprehensive study initiated by the ADM to address the geotechnical, geologic, and hydrogeological hazards encountered in the municipality. The purpose of this study is to develop a methodology for assessing karst cavities stability in the ADM, and thereby, quantify their potential hazard for civil construction and urban development in the municipality. A numerical study is performed, using a finite difference model that is based on site-specific ground conditions encountered in a localized area. Results from this numerical investigation are presented in the form of stability charts for different lithologic and surface-loading conditions. These charts are used to develop a set of geographic information system cavity-collapse geohazard maps for the study area to factor solution cavity-collapse risk into an integrated geohazard map for the ADM. Based on available information and the case study presented herein, it is concluded that the collapse of solution cavities do not significantly contribute to the geotechnical hazard observed in the ADM.

Case study on sampling, processing and characterization of landfilled municipal solid waste in the view of landfill mining

Abstract Landfilling has been the major method for municipal solid waste (MSW) disposal during recent decades. Recently utilization of deposited materials, commonly referred to as landfill mining, has been increasingly considered due to increasing raw material costs and environmental reasons. When mining municipal solid waste (MSW) landfills, finding suitable treatment and utilization routes for different types of materials is essential because of the economic aspects and to minimize the re-landfilled fraction of the waste. This paper describes a case study to sample, characterize and process wastes of a potential landfill mining site. The study combines manual sorting with full-scale mechanical treatment to better assess the treatability of the landfilled wastes. The approach also aimed at complying with the challenges of the heterogenous nature of the landfilled MSW. An approximately 30 m high and 10-year-old Finnish landfill was sampled in connection with the drilling of three gas collections wells, producing samples from two layers of waste of slightly different ages (ca. 5–10 years). Manual sieving and sorting into seven waste fractions as well as full-scale mechanical processing was performed. Further characterization included the fuel properties of the calorific fractions and the leaching properties of the fine materials. Manual sorting of the materials yielded 40–45% (w/w) of the possible fuel fraction in the landfilled waste with a net calorific value of approximately 20 MJ/kg dry matter. The metal fractions recovered in the manual sorting amounted to 3–4% (w/w). The landfilled waste was also processable by full-scale mechanical processes, including shredding, magnetic separation, screens and a wind sieve, despite the moisture and impurities in the landfilled waste. Results from the mechanical process showed that approximately 30% (w/w) of the material could be recovered as solid recovered fuel with similar calorific values to the fuel fraction from the manual sorting. Approximately 1% (w/w) could be recovered as magnetic metals in the mechanical process. The yields of fuel and metal fractions are site-specific but could likely be improved by optimizing the mechanical process for landfill mining purposes, as is indicated by the results from the manual sorting of the materials. The amount of fine materials (

Development and validation of relationships between sunflower seed quality and easily measurable seed characteristics for grading purposes

Sunflower seed delivered by farmers is usually traded without taking seed quality into account, owing to the lack of a quick and inexpensive method for quality assessment at delivery points. Seed quality parameters (oil content, protein content, hullability and amount of fine material produced during dehulling) and easily measurable seed characteristics (moisture content, hectolitre mass, thousand seed mass and seed size) were determined in 209 samples from 19 cultivars produced at 11 localities during 1999/2000. Relationships between the seed quality parameters and easily measurable seed characteristics were determined by multiple regression analysis. Although the r2-values were poor, mean absolute errors of estimates were low compared to measured ranges and standard deviations, indicating that these relationships are suitable for quality estimation. During the 2000/2001 season 270 samples of 18 cultivars produced in 15 field trials were analysed and used to compare measured and estimated quality parameters to validate the established relationships. Estimations of all the quality parameters were poor, mainly owing to systematic error indicating that annual reparameterisation of the equations may reduce the error of estimates to acceptable levels. Implementation of such a seed classification system seems unattainable.

Distribution and Normalization of Heavy Metal Concentrations in Mangrove and Lagoonal Sediments from Mazatlán Harbor (SE Gulf of California)

Concentrations of heavy metals, carbonates, organic carbon and granulometry were examined in sediments from 60 sites within Mazatlán Harbor and adjacent areas. Regional distribution had a strong (for Al, Fe, Li and Ni) and weak (for Cd, Co, Cr, Pb, V and Zn) seaward concentration gradient decreasing from the upper lagoon. The highest concentrations for most metals occurred in fine-grained sediments from Infiernillo Estuary, the upper lagoon and the industrial zone. In contrast, lower levels were usually found in the sandy sediments of the navigation channel, port entrance and an area associated with sewage outfall. Analysis of transects in mangrove and lagoonal sediments indicated that the amount of fine material and organic carbon increases towards the margins where mangrove sediments exist. While metal variations were not clearly observed in most of the metals examined; only Ni, V, Pb and Cu showed a slight tendency to increase towards the margins. Sometimes lagoonal sediments had redox and texture characteristics comparable to those from mangrove substrate, thus competing because of a similar capture capacity of metals. Metal data were normalized against Al and Li using a combination of normalization techniques (95% prediction intervals, regional anomalies and enrichment factor). It was found that Al and Li were good normalizers for most of the examined metals and they are important constituents of one or more of the major fine-grained heavy metal carrier(s) and adequately reflect the granulometric variability in the sediments of the study area.

The effect of environment and cultivar on sunflower seed. I. Yield, hullability and physical seed characteristics

The quality of South African sunflower oil cake varies and often has an unacceptably low protein and high crude fibre content. Poor hullability of the seed is generally regarded as the primary cause thereof. This study examines the contribution of cultivar and environment to the variation in yield, physical seed traits and hullability. Seed of five cultivars produced at six environments was analysed: Grain yield and all the seed traits were affected by cultivar, environment and a relatively small cultivar × environment, interaction. Environmental effects caused the most variation for yield, hectolitre mass, hull content and the amount of fines produced, while the thousand seed weight and hullability were mainly affected by cultivar. The cultivar PAN 7392 had a high and stable hullability over environments indicating that breeding for such seed traits is possible. Correlation coefficients between hullability and the easily measurable seed traits were poor. Both the negative relationship between hectolitre mass and hullability and the positive relationship between the hectolitre mass and amount of fine material produced, indicate that seed with low hectolitre mass should be preferred for maximising the chance of obtaining seed of acceptable processing quality.

Coefficient of friction of binary granular mixtures in contact with a smooth wall: PART I: Direct shear box measurements of the effects of particle size ratio and particle surface roughness

The effects were investigated of the varying fine fractions, packing geometry and different surface roughness on the measured wall friction coefficients of binary granular mixtures. Shear cell tests carried out with mono-size beds of coarse particles ( d>1 mm) under different types of packing configurations were repeated after the addition of the maximum possible amount of fine material into the packing at different particle size ratios. Similar experiments were also performed with mixtures of particles of smooth and rough surfaces. The relationship between the wall friction coefficient and the compressive stress tends to be strongly affected by the surface roughness of the constituent particles. The wall friction coefficient of an assembly of smooth particles is altered significantly by the addition of rough particles of similar size but of lower coefficient of friction, while rough particles of finer size appear to have far less effect. In contrast, when the fines are smooth particles and the coarse particles are rough, then the assembly frictional behaviour is found to be dominated by the fines.

Interrelation of stratification and passage in the screening process

The customers of the aggregate producing industry want a reduction of misplaced material, which puts heavy demands upon the suppliers. Misplaced material consists of particles below the separation limit remaining in the coarse fraction and coarse particles in the fine fraction. To minimise these problems, it is necessary to have a fundamental understanding of the screening process. There are two simultaneous processes to consider during screening, stratification and passage of particles through the apertures in the screen surface. The purpose of this article is to provide a physical explanation showing how the rate of stratification and the rate of passage vary along the screen. The interrelation of the two processes is described in the flow model presented here. The rate of stratification varies with the proportion of fine material and the ratio of the sizes of the particles. The rate of passage depends on the probability that the particles will pass through the apertures and on the amount of fine material on the screen surface. When the whole screen surface is covered with fine material, the rate of passage reaches a maximum. The model has been implemented in a calculation program. The general outcome of the calculations is in accordance with experiments.

The influence of three methods of gravel cleaning on brown trout, Salmo trutta , egg survival

Siltation of spawning gravels in upland rivers appears to be an increasing hindrance to salmonids' spawning success. River managers seek an effective and non-labour intensive means of loosening gravel and reducing fine material, so improving spawning success; this study compared three practical gravel cleaning techniques, applied at realistic (rather than intensive) levels, by assessing survival to hatching of buried brown trout, Salmo trutta L., ova at five sites on four rivers with gravel substrate in southern England. Each site consisted of six reaches, of which three were cleaned by tractor rotovating, high pressure jet washing and pump washing; these were compared with adjacent, untreated reaches. Brown trout ova were buried in both fine mesh and coarse mesh boxes in each reach. Significant improvements (at P<0·05) in survival (number of live alevins) were found in three of the five pump washed reaches, two of the five tractor rotovated reaches and one pressure washed reach when the data were analysed by site. When data from all five sites were analysed together, all treated reaches showed a significant improvement (at P<0·05) in egg survival to hatching compared with control reaches for fine mesh egg boxes; for coarse mesh boxes only pump washed reaches showed such an improvement. We feel that pump-washing provides the most effective, inexpensive and suitably non labour-intensive means of improving gravel, although ultimately it may be better to reduce the silt load of rivers. Freeze core bed samples taken before and immediately after cleaning were analysed for silt content; pump washing and high pressure washing may have reduced the amount of fine material. Copyright © 1999 John Wiley & Sons, Ltd.

Influence of Total Aggregate Gradation on Freeze-Thaw Durability and Other Performance Measures of Paving Concrete

Transportation-related agencies are experimenting with increased control of aggregate gradation in their concrete pavement specifications. There is anecdotal evidence that shows that total aggregate gradation can be optimized to yield improved concrete performance during construction and service life. Strong scientific data are less numerous in supporting this idea because of the variability in aggregates that can occur and practical considerations in avoiding waste particle sizes. The influence of total aggregate gradation on the freeze-thaw durability of concrete test specimens that employed a variety of sedimentary and igneous aggregates common in Wisconsin is examined. Optimized gradations consisted of increased amounts of aggregate particles in the No. 4 to No. 16 sieve size range and decreased amounts of fines in the No. 50 to No. 200 sieve size range. A near-gap gradation was fabricated by removing some particles in the No. 4 to No. 16 sieve size range and increasing the amount of fine material in the No. 30 to No. 100 sieve size range. Several methodologies and practical considerations were considered in establishing the aggregate gradations. A control gradation utilized a 60-40 blend of coarse/fine aggregate with gradations determined by the naturally occurring particle sizes. The concrete specimens prepared in this study were subject to strength, shrinkage, permeability, and accelerated freeze-thaw testing. All concretes had well-controlled water-cement ratios and showed excellent freeze-thaw durability. The optimized gradation mixes did not show consistently improved performance compared with the control mixes. The near-gap mixes showed reduced strength, reduced freeze-thaw durability, and increased shrinkage.

Amelioration of a degraded hardsetting soil using an anionic polymeric conditioner

Changes in the physical properties of a degraded hardsetting soil (Alfisol) after treatment with an anionic polymer (PAM) at a range of application rate (0–0.01% by weight) and antecedent soil water content were investigated. Significant improvement in soil physical properties, namely increased water stable aggregation, reduction in tensile strength and bulk density was detected in the treated soil at the lowest application rate (0.001%) and the effects increased with increasing rate of application. At the same polymer application rate, the improvement was greater at lower antecedent soil water content. However, the soil water content had a much smaller effect on soil physical properties than the polymer application rate. While zero germination was observed in the control soil (no polymer), significant improvement in germination of cotton was detected at an application rate of 7 kg ha −1 (0.005% of polymer by weight to 1 cm depth). The reduction in tensile strength of the polymer amended soil was most significantly related to the decrease in the amount of fine material ( < 50 μm) produced on wetting. Therefore, the anionic polymer ameliorates hardsetting by promoting formation of water stable bondings within microaggregate size range (< 250 μm).

Alkali release by volcanic aggregates in concrete

Selective leaching techniques that dissolve hardened cement paste in concrete while leaving aggregate particles intact, reveal mass transfer from the aggregate to the hydrated phases during concrete hardening. Leaching techniques based on selective cement dissolution with alkaline EDTA-TEA were applied to experimental mortars. Results are presented for two solvents whose only difference lies in the choice of cation: MET, the Li +, NH 4 + version, and TET, the tetramethyl-ammonium (TMA)-version. TET, which features large cations providing limited exchange capability, attacks alumine-silicates the least while dissolving clinker and paste faster. In contrast to dacite and phonolite, which reduce the level of alkali, some basalts release large amounts of alkali into the pore solution of concrete, especially when the aggregate considerable amounts of fine material and the water-cement ratio ( w c ) is high. The alkali release during the first 6 months ranges from about 1%Na 2O equivalent for a rapidly cooled fresh basalt with poorly crystallised feldspars to about 0.1% for a well crystallised basalt. It follows that, despite the use of low-alkali cement, sufficient alkali can be released from some aggregates to initiate alkali-aggregate reaction.

ASSESSING THE VARIABILITY OF ATTERBERG INDICES WITHIN THE DALHOUSIE SOIL ASSOCIATION (BRANDON SERIES)

This study assessed the lateral and vertical variability of the Atterberg indices within one soil map delineation and inferred the variability of two additional delineations of the Dalhousie association (Brandon series). The data showed that Atterberg indices were highly variable with the liquid limit varying from 33 to 51% for samples from one transect line. This variation was composed of spatial variation in both lateral and vertical directions. Much of the variation in liquid limit was related to the amount of fine material (&lt; 0.05 mm) in this soil, generally considered to be very uniform. Analyses of liquid limits from fewer samples were used to infer variability of two additional delineations. When Atterberg indices for specific depths were used different engineering classifications resulted from that given from mean values for the pedon or map unit. Key words: Atterberg indices, variability, transect, sampling confidence

Suspended Sediment Transport on the Northern Oregon Continental Shelf

Time-series measurements of bottom currents on the northern Oregon continental shell reveal widely varying speeds with means near 10 cm per sec. Current direction is more constant but often is rotary. Frequency power spectra indicate that generation may be due to internal and surface tides. Measurements of turbidity along four transects and at two time-series stations indicate that suspended material concentrates principally at the seasonal thermocline, at the permanent pycnocline, and at the bottom. Thickness and intensity of the bottom layer vary with both current strength and the amount of fine material in the surface sediment, whereas the intensity of the midwater layer appears to be related to the distance from the sediment source. The midwater layer also increases in vertical extent away from the shore. Seaward transport at the upper two surfaces provides a mechanism by which terrigenous sediment and biogeneous material bypasses the outer continental shelf.