Use Of Rocks Research Articles

Engineering Evaluation of Laterite Derived from Sedimentary Rock for Use as Subgrade and Sub-Base Materials

Geotechnical assessment of lateritic soils obtained from along the Ojota and Shagamu ends of the Lagos–Ibadan expressway was conducted to evaluate their suitability for use as sub-grade and sub-base materials. Laboratory tests, including moisture content, specific gravity, particle size distribution, fabric/plasticity, compaction, and California Bearing Ratio (CBR), were performed on eight (8) soil samples following British Standards (BS) 1377 methods for soil testing. The lateritic soils were classified as clayey sand, silty clay, and silty to clayey sand. They exhibited moderate plasticity and semi-pervious characteristics, suggesting suitability for use as sub-grade materials. Samples 3, 5, 7, and 8 were identified as more suitable for road construction materials, while Samples 1, 2, 4, and 6 showed susceptibility to seasonal volume changes due to high clay content. These samples would require minor soil stabilization to mitigate the effects of their active clay contents. Adequate drainage systems were recommended to prevent water accumulation, soil volume changes, loss of load-bearing capacity, and potential material failure beneath road pavements. The geotechnical properties of the lateritic soils from the tropical area of Ojota–Shagamu differed significantly from those of other lateritic soils found in southwestern Nigeria.

Geophysical assessment of basement rocks for use as an unconventional reservoir in the Rabeh East oil field, southern Gulf of Suez Basin

Geophysical assessment of basement rocks for use as an unconventional reservoir in the Rabeh East oil field, southern Gulf of Suez Basin

Experimental study on the effect of thermal treatment on the mechanical properties of clay-rich rocks (mudstone)

Temperature is one of the most important environmental factors that affect rock engineering properties. The clay-rich rocks such as mudstone are abundant in the earth's crust and have a high affinity to water. So the behavior of these rocks differs from others after thermal treatment, which might force the water out of the clay. Therefore, we investigated the effect of thermal treatment on the mechanical properties of clay-rich rock, mudstone, under three temperatures; ambient temperature, 250, and 500 °C. Our results showed that thermal cracks begin to appear in the mudstone at a temperature between 500 and 600 °C. Several mechanical properties were measured in the lab; uniaxial compressive strength (UCS), elastic modulus (E), Poisson's ratio (ν), Brazilian tensile strength (BTS), fracture toughness of tensile (KIC), and shear (KIIC) cracks. Due to the drying of clay minerals through the dehydration and dihydroxylation processes, the following mechanical properties of mudstone significantly increased after treating the rock with a temperature of 500 °C; UCS, E, BTS, KIC, and KIIC have improved by 91%, 39%, 16%, 41%, and 94%, respectively, while ν decreased by 80%. This reduction of ν, due to increasing the thermal treatment temperature, caused the behavior of mudstone to transform gradually from ductile to brittle material which means that the failure of such rocks, at this temperature, might be a sudden one. This research presents new insights into the effect of temperatures below 500 °C on clay-rich rocks for use in different engineering fields.

Evolution of Alkali Release by an Illitic Rock for Use as Supplementary Cementitious Material

AbstractThe levels of CO2 emissions generated by the cement industry and the growth in demand for its products have led to a search for ways to reduce these emissions. The use of supplementary cementitious materials has become one of the solutions proposed for this problem. Illite, which is found all over the world, is a possible supplementary cementitious material. Before illite can be used, it must be milled and treated thermally in order to activate it, so that the alkalis (Na+ and K+) are free and available to react. Alkalis in cement participate in deleterious reactions (alkali-silica reaction) or have a beneficial effect (alkaline activation). The alkalis present in the rocks can play an active role in these phenomena, however. In addition, the material could be influenced by the alkaline environment produced by the cement. The current study was aimed at analyzing whether an alkali release occurs and if so, how it is affected when a milled and thermally treated illitic rock is in contact with water or an alkaline solution. The material was characterized by X-ray fluorescence, polarizing microscopy, and X-ray diffraction (XRD). The sample was treated thermally at 300, 600, and 900°C, and the thermal activation was evaluated through XRD, density, and Atterberg limits. The evolution of alkali release was studied by determining the sodium and potassium concentration of contact water obtained by mixing the samples with different pH solutions for various lengths of time. In addition, the calcium concentration was determined. The concentrations of sodium and potassium in the contact water were determined by flame photometry, and of calcium by EDTA (ethylenediaminetetraacetic acid) titration. The results showed that with increasing age, increasing solution pH, and higher treatment temperatures, alkali release occurred and increased, whereas Ca2+ concentration decreased.

Effect of gradation, compaction and water content on crushed waste rocks strength

We reduced the size of the abstract to 170 words, but we cannot go lower without loosing meaning. We hope it will be ok like this --> Open-pit mining operations generate large volumes of waste rocks. It can be both economically and environmentally attractive to valorise waste rocks in mining infrastructures such as haul roads. However current practice usually consists of using waste rock directly, without any preparation or selection, thus frequently resulting in punctures, dust generation and low durability. The aim of this study was therefore to determine optimal geotechnical properties of crushed waste rocks for use in surface course layer. Crushed waste rocks were characterised in the laboratory. Their strength was evaluated using California Bearing Ratio (CBR) tests. Several compaction energies were used, and he effect of maximum particle size, fines content, and dry density on the strength were assessed. Results showed that these parameters had a significant impact on the performance of the material. The strength was maximum for an optimum FC of around 10%, a high density and in the presence of coarser particles. Two regression models were also proposed to predict the CBR value of crushed waste rocks based on their physical properties.

The tensile strength of volcanic rocks: Experiments and models

The tensile strength of volcanic rock exerts control over several key volcanic processes, including fragmentation and magma chamber rupture. Despite its importance, there is a paucity of laboratory data for the tensile strength of volcanic rocks, leading to an incomplete understanding of the influence of microstructural parameters, such as pore size and shape (factors that vary widely for volcanic rocks), on their tensile strength. To circumvent problems associated with the variability of natural samples, we provide here a systematic study in which we use elastic damage mechanics code “Rock Failure Process Analysis” to perform numerical experiments to better understand the influence of porosity, pore diameter, pore aspect ratio, and pore orientation on the tensile strength of volcanic rocks. We find that porosity and pore diameter exert a first-order control on the tensile strength of volcanic rocks, and that pore aspect ratio and orientation also influence tensile strength. Tensile strength is reduced by up to a factor of two as porosity is increased from 0.05 to 0.35 or as pore diameter is increased from 1 to 2 mm. Small, but systematic, reductions in tensile strength are observed as the angle between the loading direction and the major axis of an elliptical pore is increased from 0 to 90°. The influence of pore aspect ratio (the ratio of the minor to major axis of an ellipse) depends on the pore angle: when the pore angle is 0°, a decrease in pore aspect ratio, from 1 (a circle) to 0.2, increases the tensile strength, whereas the same decrease in pore aspect ratio does not substantially change the tensile strength when the pore angle is 90°. These latter numerical experiments show that the tensile strength of volcanic rocks can be anisotropic. Our numerical data are in broad agreement with new and compiled experimental data for the tensile strength of volcanic rocks. One of the goals of this contribution is to provide better constrained constitutive models for the tensile strength of volcanic rocks for use in volcano modelling. To this end, we present a series of theoretical and semi-empirical constitutive models that can be used to determine the tensile strength of volcanic rocks, and highlight how tensile strength estimations can influence predictions of magma overpressures and assessments of the volume and radius of a magma chamber.

Resistance of a soapstone waste rock to freeze-thaw and wet-dry cycles: implications for use in a reclamation cover in the Canadian Arctic

Engineered covers are commonly used to control the potential environmental problems related to acid mine drainage and contaminated seepage from tailings and waste rock storage facilities. Cyclical environmental weathering processes, such as freeze-thaw and wet-dry cycles, can cause rock degradation. However, these processes are usually not explicitly considered when selecting coarse-grained geomaterials for use as cover materials, even though they could be responsible for a decrease in cover performance over time. This study assesses the durability of a non-potentially acid-generating soapstone waste rock unit with respect to freeze-thaw and wet-dry cycles. This waste rock is intended for use as a cover material for the reclamation of mine tailings and waste rock storage facilities at a site in the Canadian Arctic. An experimental approach was developed based on existing standard and non-standard laboratory methods. Degradation tests were conducted on rock cores, rock slabs, and < 50-mm granular materials. These tests examined changes in selected physical and mechanical properties before and after 20 and 80 freeze-thaw and wet-dry cycles. The high density, low water absorption index, and low apparent porosity of the fresh waste rocks suggested excellent rock durability, which was confirmed by the degradation tests that showed acceptable mass losses and negligible evolution of the material’s physical and mechanical properties over time. Considering the results of this study, the studied waste rock unit was identified as an excellent construction material for mine closure purposes. The experimental approach developed for this study could be included in cover design methodologies and applied widely in the selection of rocks for use in mine reclamation schemes in cold regions.

Uniaxial compression test of rocks: Review of strain measuring instruments

The importance of uniaxial compression test (UCT) of rocks will never be overemphasized as it plays a vital role in understanding the mechanical properties of rocks for use in civil, mining, and petroleum engineering. Strain response of rocks to external loading is small; it requires a precise instrument to capture the strain with reasonable accuracy. The conventional method is associated with system compliance error, limited precision, and bedding error. Several methods were devised to alleviate these errors. This study embodies the existing strain measuring instruments during UCT of rocks, their principles, features, accuracy, merits, and demerits are correctly scrutinized. The paper serves as a powerful tool that enables the selection of a suitable instrument accordingly. It is hoped that the study will encourage more exploration in the area.

Evaluation the suitability of Fat’ha gypsum rocks for use as thermal insulators in Sharqat District/Northern Iraq

This research aims to study the suitability of gypsum rocks in Sharqat district as thermal insulators. The Result showed that the gypsum rocks have negligible porosity (3.80-5.17) %. And the absorption ratio between (1.6-2.4) %. The density was (2.15-2.34 gm/cm3). While the specific gravity values were as (2.15- 2.34). The moisture content ranged between (0.40 - 0.94) %. The thermal test results showed that the average thermal conductivity value of gypsum rock was (0.65) W/mc̊. The laboratory tests indicate a suitability of gypsum rocks of the in Sharqat area as thermal insulators.

Dust Exposure, Fractional Exhaled Nitric Oxide and Respiratory Symptoms among Volcanic Rock Miners in Kilimanjaro, Tanzania

Volcanic rock for use as building material is mined extensively in the North Eastern Region of Tanzania. Dust emitted from the rock may contain harmful elements such as crystalline silica, arsenic (As), cobalt (Co), boron (B) and mercury (Hg) which might contribute to severity and onset of health symptoms.Objective:This study assessed respiratory symptoms and fractional exhaled nitric oxide as a marker for respiratory inflammation in relation to dust exposure among workers in different job sections in volcanic block mining.Materials and Methods:A cross- sectional study assessed a total of 135 workers in which 70 were exposed and 65 none exposed. The mining activities are mainly manual, and include cutting of blocks underground, transporting blocks to the shaping area, shaping blocks, loading blocks and aggregates (Murom) to vehicles and clearing or expanding the site. Respiratory health questionnaires were administered through face–to-face interviews. A total of 28 samples of “total” dust were collected around the breathing zone of the workers using SKC Sidekick pump (model 224–50) with a flow rate of 2.0 l/min. FENO assessed respiratory system inflammation using a portable electrochemistry-based sensor (NIOX MINO).Findings:The overall arithmetic mean concentration of personal total dust exposure among the workers was 4.37 mg/m3 (range 0.15-20.84). The prevalence of acute cough and red eyes were significantly higher among exposed than among non exposed (35% vs 10% and 45% vs 14%, respectively). The ANOVA Boniferroni test showed a significant difference in mean FENO between stone cutters and none exposed (P = 0.005).Conclusions:This study suggests the strong association between working as a stone cutting and shaping with respiratory inflammation. There is a need for respiratory mask type P2 use to protect workers from the exposure. There is also need for the follow up study involving cohorts of all workers happened to be in the mine.

Quantitative Identification of the Annealing Degree of Apatite Fission Tracks Using Terahertz Time Domain Spectroscopy (THz-TDS).

Apatite fission-track (AFT) analysis, a widely used low-temperature thermochronology method, can provide details of the hydrocarbon generation history of source rocks for use in hydrocarbon exploration. The AFT method is based on the annealing behavior of fission tracks generated by 238U fission in apatite particles during geological history. Due to the cumbersome experimental steps and high expense, it is imperative to find an efficient and inexpensive technique to determinate the annealing degree of AFT. In this study, on the basis of the ellipsoid configuration of tracks, the track volume fraction model (TVFM) is established and the fission-track volume index is proposed. Furthermore, terahertz time domain spectroscopy (THz-TDS) is used for the first time to identify the variation of the AFT annealing degree of Durango apatite particles heated at 20, 275, 300, 325, 450, and 500 ℃ for 10 h. The THz absorbance of the sample increases with the degree of annealing. In addition, the THz absorption index is exponentially related to annealing temperature and can be used to characterize the fission-track volume index. Terahertz time domain spectroscopy can be an ancillary technique for AFT thermochronological research. More work is urgently needed to extrapolate experimental data to geological conditions.

Experimental evaluation of thermo-mechanical performances of candidate rocks for use in high temperature thermal storage

Packed-bed of rocks using air as heat transfer fluid (HTF) are identified as a promising alternative and cost effective solution for thermal energy storage (TES) in concentrating solar power plants (CSP). Desert sands, igneous and other rocks are being intensively tested for heat storage at high temperature. This paper focuses on the study of several candidate rocks for heat storage. Thirteen samples are collected from diverse places in Morocco and thermally cycled between 20°C and 650°C. The chemical and thermo-physical properties influencing the lifetime of rocks are identified. Vickers hardness test has been used to evaluate the compressive strength of the samples and the effect of thermo-mechanical stress during thermal cycling. The obtained results show that quartz and calcite are the principal minerals controlling rock physical properties. Limestone, marble and granite have not withstood thermal cycling. Their hardness decreases after each cycle. Rhyolite and quartzitic sandstone show excellent ability during thermal cycling. When comparing their principal characteristics, rhyolite seems to be the most promising candidate for high temperature TES.

Determining the pozzolanic activity component of volcanic rock

To assess the quality of volcanic rock used as pozzolan in cement-based materials, two methods are introduced to estimate the pozzolanic activity component of volcanic rock based on X-ray diffraction data and chemical composition. Pozzolanic activity component is calculated by rock method as the product of rock composition (SiO2 + Al2O3) content and rock amorphous phase content determined by X-ray diffraction over the entire range. In the mineral method, pozzolanic activity component is calculated as the sum of the active component SiO2 content and the active component Al2O3 content, which are calculated by the chemical composition and amorphous phase proportion determined from X-ray diffraction data of quartz and feldspar, respectively. An excellent positive correlation was observed between the two pozzolanic activity component types. Both calculated pozzolanic activity components had separately positive correlations with the pozzolanic activity index measured as the ratio of mortar strengths. The results could be applied to judge the potential of volcanic rock for use as pozzolan.

Mechanical activation of natural acidic igneous rocks for use in cement

Mechanical activation of three natural acidic igneous rocks, including granite, pumice, and perlite, was studied using a planetary mill. Positive effects of milling were demonstrated with respect to the compressive strength of mortars with the partial substitution of cement by mechanically activated acidic powders. A set of mortar specimens was made with 0%, 10%, 20%, and 30% activated powder replacement.X-ray diffraction and mineralogy studies revealed that the initial granite consists of fully crystalline phases, while pumice and perlite contain not only amorphous but also crypto-crystalline phases. It was found that pumice and perlite rapidly lost their crystalline nature through milling, remaining in solely amorphous phases after 15min of milling, whereas granite maintained its crystalline nature even after 45min. Milling generates a larger specific surface area, much more remarkable for pumice than for granite and perlite, but due to reactive agglomeration, there was a limitation on the specific surface area of pumice. All three mechanically activated acidic powders had significant effects on strength development especially at the early ages of solidification. But in the long term their effects depended on material type and grinding condition. The greatest strength improvement was achieved by mechanically activating perlite for 30min, at 10% substitution in cement mix. Cement consumption can be reduced by up to 30% in weight using mechanically activated powders in cement mix while keeping the 28day compressive strength at a satisfactory level. In addition, ultrasonic pulsation of mechanically-activated perlite indicated that the specific surface area was mostly influential and available in the early stages of solidification, while structural changes appeared to be so at later stages of hardening.

USE OF SINGLE LAYER CONCRETE ARMOUR UNITS AS TOE REINFORCEMENT

Detailing and optimization of the toe reinforcement is presented as a case study from the construction of the 5.2km long main breakwater for the new Colombo South Harbour in 18m water depth. During the breakwater design the environmental constraints on supply of large rock armour were recognized, and CORE-LOC™ single layer concrete armour units were selected for the primary armour protection. During construction, supply of relatively small quantities of 8-12t rock for use in the toe reinforcement became an issue, and use of CORE-LOC™ units placed on the flat rock armour apron as an alternative to rock armour toe reinforcement was investigated and implemented. This use is unusual as there is no in-plane compression between units as found when they are placed on the slope. A site based prototype scale trial was conducted to evaluate placing method and criteria, and an "alternate opposing cannon† pattern placement, in rows going seaward from the primary armour, was successful. Packing density and unit spacing is the same as for the primary armour. Hydraulic stability of this alternative toe reinforcement was verified in 2D physical hydraulic model testing.

The Traveling Libby Legacy: Minnesota Community Exhibits Nonoccupational Health Impacts Consistent with Asbestos Damage

Vol. 120, No. 1 News | Science SelectionsOpen AccessThe Traveling Libby Legacy: Minnesota Community Exhibits Nonoccupational Health Impacts Consistent with Asbestos Damageis accompanied byRadiographic Evidence of Nonoccupational Asbestos Exposure from Processing Libby Vermiculite in Minneapolis, Minnesota Tanya Tillett Tanya Tillett Search for more papers by this author Published:1 January 2012https://doi.org/10.1289/ehp.120-a35aAboutSectionsPDF ToolsDownload CitationsTrack Citations ShareShare onFacebookTwitterLinked InReddit Adverse health effects of asbestos have been documented worldwide for the better part of the last half-century, with a large number of studies focused on occupational exposures received during the mining and processing of vermiculite ore. A new study reports on nonoccupational health effects resulting from community exposures to Libby vermiculite ore processed at the Western Minerals/W.R. Grace (WM/WRG) facility in Minneapolis, Minnesota [EHP 120(1):44–49; Alexander et al.].The WM/WRG plant is located in a residential neighborhood that includes a mix of single- and multifamily homes as well as schools and churches. During its years of operation from 1938 to 1989, residents were allowed to haul away waste rock for use in their yards, and children played on piles of waste rock outside the plant.Previous studies indicated an association between changes in lung function––a risk factor for asbestos-related disease—in children who reported playing on piles of waste rock in Libby, Montana, where this vermiculite ore was mined. In the current study, researchers analyzed radiographs of the lungs of 461 Minneapolis community members who were at risk for exposure to the WM/WRG vermiculite prior to 1980 (this date ensured an adequate latency period for any asbestos-related effects to manifest). The participants were part of the original Northeast Minneapolis Community Vermiculite Investigation cohort initiated by the Minnesota Department of Health and the U.S. Agency for Toxic Substances and Disease Registry.Archival photo of children playing on waste rock at the WM/WRG plant.Minnesota Department of HealthParticipants’ background asbestos exposures were estimated by coupling residential history with air dispersion and deposition models of the asbestos emitted from the plant when it was in operation. The researchers also asked participants about activity-based routes of exposure, such as having played as a child on the piles of waste rock outside the plant.Nearly half the participants reported engaging in at least one activity that brought them into contact with the waste material, and 39% reported having played on the waste rock piles. Radiographic evidence showed a 10.8% prevalence of pleural abnormalities consistent with pneumonoconiosis—evidence of asbestos-induced changes in the lungs—as determined by consensus of two radiologists certified to evaluate X rays for the effects of asbestos. Participants with pleural abnormalities were more likely to be male and were older, and those who reported frequently playing on waste rock piles had twice the prevalence of pleural abnormalities compared with those who reported never playing there. Pleural abnormalities also were more strongly associated with cumulative exposure estimated to have been acquired over many years than with higher intermittent peak exposures.Study limitations included small population size, imprecise estimations of activities leading to exposure, and analysis of only a single chest radiograph for each study subject. However, the results suggest that health effects associated with asbestos exposure may occur at lower levels than previously believed, pointing to the need for further research on the effects of long-term, low-level, and nonoccupational asbestos exposures.FiguresReferencesRelatedDetailsRelated articlesRadiographic Evidence of Nonoccupational Asbestos Exposure from Processing Libby Vermiculite in Minneapolis, Minnesota12 October 2011Environmental Health Perspectives Vol. 120, No. 1 January 2012Metrics About Article Metrics Publication History Originally published1 January 2012Published in print1 January 2012 Financial disclosuresPDF download License information EHP is an open-access journal published with support from the National Institute of Environmental Health Sciences, National Institutes of Health. All content is public domain unless otherwise noted. Note to readers with disabilities EHP strives to ensure that all journal content is accessible to all readers. However, some figures and Supplemental Material published in EHP articles may not conform to 508 standards due to the complexity of the information being presented. If you need assistance accessing journal content, please contact [email protected]. Our staff will work with you to assess and meet your accessibility needs within 3 working days.

New Insights into Ancient Maya Building Materials: Characterization of Mortar, Plaster, and Coquina Flagstones from Toniná

ABSTRACTThis work shows current research on lithic raw material used by the ancient Maya of Toniná. The core of the city of Toniná lies on a steep-sided hill of calcareous sandstones from the shallow marine deposits dated as Oligocene, in the Chiapas Highlands of Southern Mexico. Results of paleontological fieldwork in Toniná show several biostrome sediments mound-like with tabular bafflestones and large coquina flagstones, which are sheet-like rocks enriched with fossil mollusk shells, corals, encrusted organisms, and calcareous debris. The people of Toniná intentionally selected and carved these rocks for use as building blocks and bricks on floors, walls, and stairways. At least two coquina flagstones measuring about 1.90 m long were identified in an archeological context most likely associated with carved stelae. Also non-marine carbonate rocks such as a crudely banded travertine and spongy calcareous tufa from recent sediments of freshwater environments surrounding Toniná were used by the Maya as a raw material on walls, columns, reliefs and murals base.Results of the chemical, mineralogical and micromorphological analysis on plaster and bedding mortars from the walls of Toniná display a slightly interbedded lime of sparry calcite cemented in a highly porous groundmass with silt-to pebble-size of calcareous and siliciclastic rock-crushed aggregates, sand, and soil remains. Lime fabric reveals enclosing quartz grains, granular calcite crystals, and carbonaceous inclusions which may suggest that the lime has been made from a burnt grain-rich limestone with fibrous cement and porous microfabric. WDX analysis in lime lumps of plaster reveal an average amount of 1.37 wt% MgO associated with a limestone source ranging from regular to a magnesium-enriched limestone (1 to 2 wt %). XRF detect a strontium-rich level in the calcite matrix of plaster which is as high as that of fossil shells, tufa, and coquina. Finally, XRD shows that the mean amount of calcite in plaster is 95 wt% and lower amount (2-2.5w%) of siliciclastic minerals: quartz and albite. In contrast, calcite in mortar ranges less than 90.1 wt%. The concentrations of non-carbonate minerals, such as quartz and albite, are higher than those in plaster because mortar incorporates more siliciclastic rock remains, sand and clay.

A physical analogue material to simulate sturzstroms

A physical analogue material is presented as a synthetic rock for use in centrifuge experiments on sturzstroms. Sturzstroms are rock slides of very large volume, which display intense fragmentation of blocks of rock owing to inter-particle collisions. Although the stresses within the centrifugal experimental set`-up are significantly enhanced owing to acceleration forces, compared with 1g laboratory experiments, the original rock of a sturzstrom event is still too strong and does not display fragmentation in the centrifuge. An analogue material has been developed to exhibit similar mechanical properties as well as reduced strength. A literature review on the development of analogue materials is included together with the recipe of the newly developed synthetic soft rock, based on Quartz sand bonded with Portland cement. A comprehensive mechanical characterisation of this material is given.

Directable Weathering of Concave Rock Using Curvature Estimation

We address the problem of directable weathering of exposed concave rock for use in computer-generated animation or games. Previous weathering models that admit concave surfaces are computationally inefficient and difficult to control. In nature, the spheroidal and cavernous weathering rates depend on the surface curvature. Spheroidal weathering is fastest in areas with large positive mean curvature and cavernous weathering is fastest in areas with large negative mean curvature. We simulate both processes using an approximation of mean curvature on a voxel grid. Both weathering rates are also influenced by rock durability. The user controls rock durability by editing a durability graph before and during weathering simulation. Simulations of rockfall and colluvium deposition further improve realism. The profile of the final weathered rock matches the shape of the durability graph up to the effects of weathering and colluvium deposition. We demonstrate the top-down directability and visual plausibility of the resulting model through a series of screenshots and rendered images. The results include the weathering of a cube into a sphere and of a sheltered inside corner into a cavern as predicted by the underlying geomorphological models.

Quantitative characterisation of processed phlogopite ore from Silver City Dome District, Kansas, USA, by automated mineralogy

Historically, phlogopite and olivine have been mined in the Silver City Dome District in Kansas, USA, from lamproite ultra-potassic igneous rock for use as a supplement in cattle feed. Micro-Lite LLC is now evaluating processing techniques for recovery of phlogopite to be used for reinforcement in plastics, high temperature applications, and electrical insulators, which requires a higher grade phlogopite product. To determine the purity of the processed ore, QEMSCAN ® was utilised to identify and quantify phlogopite and impurities, including olivine, pyroxenes, feldspars, titanium phases (mainly titanite and perovskite), apatite, magnetite, chromite, and other phases. Samples were prepared and analysed in a manner to decrease or eliminate preferred orientation of phlogopite to provide accurate quantitative results. The results show that the flotation product has a higher concentration of phlogopite at 87% (by mass), compared to 78% in the hydrosizer product. The main impurity phase in both products is olivine (10% in the flotation product and 18% in the hydrosizer product). In the hydrosizer product, 15% of the sample consists of liberated phlogopite particles, while in the flotation product 58% of the sample occurs as pure, liberated phlogopite particles.