Quartz Input Research Articles

Simulation of flows of hazardous elements in copper smelting process based on Bayesian network

The large amount of hazardous waste produced and discharged in the process of copper smelting has brought serious environmental risks and disposal pressure. However, the migration and transformation behavior of hazardous elements in the copper smelting system is affected by multiple factors, and idealized chemical mechanism studies are difficult to reveal the complex patterns in large-scale production. This study has built a Bayesian network model based on the Expectation-Maximum algorithm and cluster tree propagation algorithm to reveal the key influencing factors and mechanisms of the distribution of hazardous elements in actual large-scale production. The results show that the main operating parameters affecting the flow direction of hazardous elements are blast volume, oxygen supply volume, input copper content, quartz input, etc. The variation patterns of elemental fluxes of arsenic and lead with input variables in all production processes of copper smelting system were obtained. The fluxes of these two hazardous elements alter similarly in most processes. The maximum variations of arsenic and lead content in material flows are up to 48% and 32%, respectively. This study can help to supplement and perfect the theoretical basis of the distribution pattern of hazardous elements and to realize automatic prediction of element flows under different operating conditions.

Trace-elemental and petrographic constraints on the severity of hydrographic restriction in the silled Midland Basin during the late Paleozoic ice age

AbstractEnrichment of redox-sensitive trace elements in ancient marine shales is conventionally believed to be controlled by marine benthic redox conditions, whereas the influence of hydrographic conditions on trace element enrichment pattern has been rarely considered. Here, we present newly obtained data sets from the Upper Pennsylvanian organic-rich Cline Shale in the Midland Basin, Texas, to illustrate the influence of hydrographic circulation on the trace-element enrichment pattern and the stratigraphic record of mudrocks. Various lithofacies, including siliceous mudrocks, argillaceous mudrocks, skeletal-bearing argillaceous mudrocks, calcareous mudrocks, and wackestone, are identified in the Cline Shale. Significant changes in the trace-element enrichment pattern, mineral composition, texture of framboidal pyrite, and other bulk geochemical parameters in different lithofacies are interpreted to have been caused by high-amplitude and high-frequency glacio-eustatic sea-level oscillations in the silled Midland Basin during the late Paleozoic ice age. Specifically, glacio-eustatic sea-level falls generally resulted in the severe isolation of the Midland Basin from the Panthalassic Ocean, highly restricted hydrographic circulation, long deep-water renewal time, euxinic bottom-water conditions, depleted seawater Mo (molybdenum) in the silled basin, and low sediment Mo/TOC (total organic carbon), coupled with significant extrabasinal detrital quartz input, forming siliceous mudrocks. Enhanced phosphorus cycling and excellent preservation conditions are considered to be responsible for the high TOC observed in siliceous mudrocks. In contrast, glacio-eustatic sea-level rises substantially enhanced water exchange between the basin and the Panthalassic Ocean, created overall suboxic to anoxic bottom-water conditions, resupplied seawater Mo, elevated sediment Mo/TOC, and increased platform carbonate production in the basin, forming calcareous mudrocks and wackestone.

Maastrichtian to early Paleocene sea level changes and climatic evolution on the southeastern Tethys margin

Abstract An integrative multi proxy approach based on lithology, microfacies, bulk rock composition, total organic carbon (TOC), and δ13Ccarb was used to estimate southeastern Tethys sea level fluctuations during the deposition of the Maastrichtian-Danian oil shales in Jordan. Clay mineral assemblages were used as proxies to determine climatic variation induced sediment supply during the Cretaceous/Paleogene boundary (K/Pg) interval. The results from two cores (OS-02, Jafr Basin, southeast Jordan; OS-28 Azraq-Hamza Basin, central-east Jordan) reveal four major intervals of distinctive bulk rock composition reflecting sea level changes. Interval I (earliest Maastrichtian) with a low sea level and the formation of dolomites and a high detrital quartz input predates the oil shales. Intervals II and III in core OS-02 and interval II in core OS-28 represent the highest relative sea level following the Early Maastrichtian sea level rise on the Arabian Platform. Intervals III (core OS-02) and II (core OS-28) coincide with the highest organic matter deposition. Interval IV (core OS-02) and intervals III and IV (core OS-28) relate to the sea level regression-transgression cycle in the latest Maastrichtian through Danian and are marked by a large drop in the TOC content. Increased terrestrial influx during sea level lows is evident from two peaks/intervals of major negative δ13Ccarb values in core OS-28. Based on clay mineralogy it can be differentiated between warm/humid, warm/cool seasonally alternating, and cool/arid climates. When bulk rock composition is used as a sea level proxy, clay mineral assemblages from both cores reveal the dominance of warm and humid climate or, alternatively, warm/cool seasonal alternations during high sea levels (II and III core OS-02; II and IV core OS-28), while periods of arid and cool climate correspond to lower sea levels. The sea level changes and climatic variations deduced from the Jordanian oil shale successions are in agreement with the long term variations from the Egyptian Western Desert sections (southeastern Tethys), and the Tunisian El-Kef section (southweastern Tethys). Moreover, the sea level changes identified relate to the regional changes on the Arabian platform during the Maastrichtian-Danian.

Investigating the use of sedimentary geochemical proxies for paleoenvironment interpretation of thermally mature organic-rich strata: Examples from the Devonian–Mississippian shales, Western Canadian Sedimentary Basin

Shales and mudrocks are enriched with diverse suites of major elements and trace metals that reflect their depositional environment, provenance and diagenesis. Here we present geochemical data for Devonian–Mississippian shaly strata (Western Canadian Sedimentary Basin) to assess the use of geochemical proxies for thermally mature deposits (> 1.5% vitrinite reflectance; VRo), and the ability to apply such proxies to elucidate the paleoceanographic conditions responsible for element distributions. Specifically, excess silica contents, C–S–Fe relationships, Ni/Co, V/Cr, Mo/Al and Re/Mo are utilized. Although regional in scope, the data presented here has broader implications for utilizing trace element geochemistry from geologic periods (Devonian–Mississippian) in which significant organic-rich sediment accumulation occurred, and subsequently underwent high levels of thermal diagenesis. Comparison of thermally mature lower Besa River, Golata, Muskwa and Fort Simpson shales (> 2% VRo for lower Besa River, and between 1.5% and 2% VRo for Golata, Muskwa and Fort Simpson), show that: 1) thermal maturation has had no effect upon the distribution of redox-sensitive elements (e.g., Ni, V, Mo, Tl, Cd and U); and 2) these elements are delivered to the sediment in association with the organic matter under anoxic (possibly euxinic) water-column conditions. Major element geochemistry (and optical microscopy) indicates organic-rich lower Besa River and Muskwa sediments are enriched in biogenic silica (proxied by excess SiO 2 concentrations), hence the use of Si as a proxy of detrital quartz input must be used with caution. Excess Si concentrations could be used as paleoproductivity proxies in reducing sediments where elements such as P and Ba are mobilized and not retained in the sediments. Golata sediments also have high excess Si contents, but the enrichment of Ti, Nb, Th, Ce, Hf and La (detrital-proxying elements) relative to average shale implies a detrital source of the quartz. Organic-rich, sulfur-rich upper Besa River shales were deposited in anoxic conditions (based upon C–S–Fe and Re/Mo relationships), akin to lower Besa River and Muskwa shales. However, upper Besa River shales show no enrichment of redox-proxying elements Mo, U and V, indicating benthic anoxia was not a ubiquitous requirement for element sequestration. Thermal maturation levels are similar to that of lower Besa River shales; hence element loss through diagenesis is not implied. A possible explanation is differing sedimentation rates which can affect the diffusion and concentration of elements into the sediment, and subsequent authigenic enrichment. This behavior makes Mo, U and V of limited use as paleoredox proxies under these sedimentary conditions.

Recent developments on ISPA-cameras for gamma ray imaging: gamma imaging with an electrostatic crossed focussed ISPA-tube

The Imaging Silicon Pixel Array (ISPA)-tube is a position-sensitive hybrid photon detector. Originally developed for high-energy physics purposes, it has also been used for biomedical applications. Two kinds of ISPA-tube prototypes have been tested successfully in the field of gamma ray imaging. The current developments aim at obtaining a detector dedicated to single-photon emission imaging. In this paper, we present the first use in a gamma camera of a new ISPA-tube prototype having an increased active input surface of 40mm diameter and a de-magnifying electron optics. The quartz input window of the tube is optically coupled to a 3.5cm2 YAlO3:Ce detector array with 0.6mm2 single elements.

An ISPA-camera for γ-rays in nuclear medicine

The ISPA (Imaging Silicon Pixel Array)-tube is a position-sensitive photon detector. Originally developed for HEP applications, it can also be envisaged for biomedical applications. By coupling it to scintillating crystals or crystal arrays (YAP) we built a γcamera and detected through a collimator the 122 keV γ-rays from a 57 Co source. This paper presents the results obtained with two different ISPA-tube prototypes: the first ISPA-tube, having a glass fibre optic input window, allows to achieve very high spatial resolutions; the second ISPA-tube prototype, with its non fibre optic quartz input window, leads to much better energy resolutions while preserving sub-millimetrie spatial resolutions.

Investigation of an aggrading paleosol developed into andesitic ring-plain deposits, Ruapehu volcano, New Zealand

Within a sequence of andesitic volcaniclastic deposits on the northeastern ring plain of Ruapehu volcano is a ca. 10 m-thick sequence of weathered andesitic tephras. Weathering and paleosol development is most evident in 3.6 m of fine ash in this sequence. The ages of these tephras are constrained between ca. 23–70 ka by dated rhyolite tephras erupted from central North Island volcanoes. Mineralogy of the fine ash deposits reveals their origin, and the processes involved in their soil development. The fine ash deposits are almost totally locally derived either as primary volcanic ash or fines reworked from the ring plain itself by aeolian processes. Aerosolic quartz input associated with regional loess deposition during the cool climatic episodes of mid-δ 18O stage 3 and δ 18O stage 4 is very low, having been diluted by rapid accumulation of andesitic tephras in these episodes. The observed weathering features and secondary minerals within the ash sequence were derived from a complex combination of factors including climate change, accretion rate, and post-depositional modification. Relatively strong weathering development in two parts of the ash sequence is correlated with two widespread soil development episodes during the Last Glacial observed throughout the southern North Island. The accretion rate of the soil surface at these times also affected the expression of climate-related weathering. Formation of allophane (with an A1:Si ratio of 2:1) and ferrihydrite occurred near the soil surface as the ash was accreting. The amount of allophane and ferrihydrite through the sequence appears to be inversely related to the accretion rate of the soil surface. Upon burial of the ash materials by a thick ( > 20 m) sequence of lahar and tephra deposits, halloysite was later formed in the buried ash. The leaching of silica from the thick overburden of volcaniclastics into the ash material as well as perched water is thought to have decreased the A1:Si ratio in the soil solution and thus promoted the formation of halloysite from weathering andesitic glass.

A fast spectroscopic diagnostic for the measurement of plasma impurity ion dynamics

A high-resolution spectrometer has been developed and used to measure simultaneously impurity ion temperatures and flow velocities in high temperature plasmas with 10 μs temporal resolution (limited by digitization rate). This device is actually a duo-spectrometer: measurements from two different chordal views of the plasma can be made simultaneously via two separate quartz input fiber optic bundles coupled to the entrance slits which are tilted to compensate for line curvature. The dispersed spectra on the exit plane of the duo-spectrometer are coupled via quartz fiber optics to two arrays of 16 photomultiplier tubes each. Measurements made by recording the Doppler broadened and shifted 227.091 nm emission from the C v impurity ions in the Madison Symmetric Torus (MST) reversed-field pinch (RFP) plasma have achieved precisions of <6 eV for temperatures of 150 eV and <0.7 km/s for flow velocities of 6 km/s. Representative results from the MST RFP indicate that the toroidal flow velocity drops and ion temperature increase during sawtooth events in MST.

Veiling glare measurements in the F4111 image intensifier

Veiling glare is a phenomenon present in most imaging devices and systems. It is a source of concern in proximity-focused image intensifiers where it causes a loss in image contrast, especially at low spatial frequencies. Veiling glare was measured in two different ITT F4111 18-mm image intensifiers, one with a fiber optic input window and fiber optic output window (FO/FO), and the other with a quartz input and fiber optic output window (Q/FO), by means of a half-field high-contrast excitation method. Near-field veiling glare, a measure of stray light close to a high-contrast edge, and far-field veiling glare, a measure of more widely distributed stray light, were measured as fractions of the illumination level. Near-field veiling glare of 0.4±0.1 and far-field veiling glare of 0.08±0.02 were measured for the FO/FO intensifier, and near-field veiling glare of 0.38±0.01 and far-field veiling glare of 0.03±0.002 were measured for the Q/FO intensifier. The characteristic length, which is a measure of the extent of veiling glare from the edge, was 0.69±0.04 mm (near-field) and 1.8±0.4 mm (far-field) for the FO/FO intensifier, and 1.19±0.03 mm (near-field) and 6±1 mm (far-field) for the Q/FO intensifier. A preliminary investigation suggests that the characteristic length for near-field glare increases with increasing wavelength.

Gradual carbonate-to-clastic transition and provenance of quartz along the NW Trento Plateau, Southern Alps, Italy

Over the drowned site of the NW Trento carbonate platform a gradual transition from Early Cretaceous pelagic carbonate to more siliciclastic sedimentation during the Early Tertiary is denoted by mineralogical and geochemical trends. Decreasing oxygen isotope ratios of quartz in the matrix (from +34.33% to +18.47% SMOW) suggest a mainly biogenic origin for the silica, with insignificant terrigenous quartz input during the Early Cretaceous and only minor introduction of terrestrial quartz during the Late Cretaceous and Early Tertiary. The insignificance of terrigenous input during the Late Cretaceous and Early Tertiary is consistent with existing depositional models that involve bypassing of the NW Trento Plateau margin, the bulk of the terrigenous deposition being funnelled into the adjacent Lombardian flysch basin (Bernoulli and Winkler, 1990) during the Eoalpine tectonic phase (Doglioni and Bosellini, 1987).

Paleoclimatic significance of quartz/illite variations in cores from the eastern equatorial north Atlantic

Detailed X-ray diffraction analysis of cores taken in the eastern equatorial Atlantic suggest that during approximately the last 600,000 yr a relatively constant background of clay mineral deposition has existed on which are superimposed large oscillations in quartz input (relative to illite). The quartz is transported from the Sahara Desert by the northeast trade winds and the quartz/illite oscillations appear to reflect past changes in the transporting effectiveness (intensity) of the trade winds. Comparison of the quartz/illite variations with paleotemperature variations for the northeast Atlantic suggests that major inputs of quartz correlate with cold periods and that warm periods correlate with low quartz input. The parallelism between the curves indicates a fundamental link between trade wind intensity and past climatic fluctuations, and further suggests that the changes of intensity are closely atuned to temperature fluctuations in the northern latitudes. The relationship between the quartz/illite variations and wind intensity is complicated by the fact that other climatically controlled factors may also affect quartz deposition in the equatorial Atlantic.