Separated Grain Research Articles

Investigation on the Correlation between Mechanical Strength, Grain Size, and Density of Fly Ash Microspheres in the Context of Refining Process.

Fly ash microspheres, also called cenospheres, have many valuable properties that allow them to be widely used. Some of its most important properties are its mechanical and thermal strength as well as its chemical stability. These features constitute an important commercial parameter. Refining processes aim to select the highest quality product from raw materials that meets the expectations of recipients. Generally, preparing a final product involves selecting the appropriate sequence and parameters of the grain separation process. However, the key to the optimal selection of these parameters is knowledge of the specificity of the processed raw material. Microspheres are materials that are created spontaneously, uncontrolled, and without the possibility of intentionally influencing their properties. Therefore, due to the potential directions of microsphere use, it is justified to study the relationship between density, grain size, and mechanical strength. Understanding these relationships in microspheres from various sources is particularly important at the stage of planning refining processes. This paper presents the results of research on microspheres from two different sources. The tested raw materials (microspheres) are subjected to densiometric and grain analysis. Also, mechanical strength was determined for the separated density fractions and grain classes. The test results did not show significant correlations between the tested features of the microspheres. In the case of both raw materials, the highest density was observed in the smallest grain classes, and the highest mechanical strength was determined for microspheres with grain sizes in the range of 75-100 µm. For this grain size range, the value of mechanical strength is 26 for raw Material 1 and 38 for raw Material 2. The shares of this grain fraction in the microsphere stream are 11.2% and 16%, respectively. An important difference that may significantly affect the efficiency of the refining process is the method of distribution of the primary falling parts, which affects the mechanical strength of the tested raw materials.

Influence of the Grid Inclination Angle on the Efficiency of Preliminary Separation of the Combed Heap

Introduction. A highly topical scientific and practical task is to justify the choice of the most advanced variant of the device for pre-separating the combed heap and to optimize its design. Aim of the Study. The study is aimed at testing the effect of the grid inclination angle on the effectiveness of pre-separating the combed heap. Materials and Methods. It is possible to minimize the separated grain flow into the threshing machine either by means of a feeder house grid bottom or by means of a horizontal separating device, located directly in front of the threshing drum. To select the optimal design of the separation device, there was planned and conducted a laboratory experiment. The study was carried out in two stages. In the first series of experiments, the elevator body was installed horizontally, and in the second series – at an angle of 45° to the horizon. The width of the grid bottom openings had four variations (6, 8, 10 and 12 mm), and the speed of the scraper conveyor was 3 m/s. A combed heap of the winter wheat variety Moskovskaya 56 was selected as the study object. The grain moisture was 12%. Results.According to the results of laboratory studies, it was found that with an increase in the width of the grid surface openings, the intensity of separating grain increases. The maximum device throughput (90%) corresponds to the horizontal position of the grid bottom of the experimental installation and the width of the openings b = 12 mm. Extrapolation of the separated grain decreasing graph indicates that to ensure complete separation of grain, the length of the separating grid should be at least L = 0.9 m. Discussion and Conclusion. The use of a horizontal separating grid allows increasing the device separation efficiency and reducing its metal content by 14–16%.

Brittle basement deformation during the Caledonian Orogeny observed by K‐Ar geochronology of illite‐bearing fault gouge in west‐central Sweden

AbstractThis study presents K‐Ar ages of illite‐bearing fault gouges in crystalline basement in central‐western Sweden. Samples were taken from two faults that localized brittle deformation marginal to and within mafic dikes that intruded Paleoproterozoic granitoids. K‐Ar ages from 10 separated grain fractions span from 823 to 392 Ma. Older ages obtained (823–477 Ma) were influenced by a mixture of illite and K‐feldspar; the latter likely formed during a hydrothermal event prior to faulting. The remaining ages (442.1 ± 9.7 to 391.7 ± 6.1 Ma) were obtained from fractions from both faults hosting only authigenic illite and show that illite crystallized during the Scandian phase of the Caledonian orogeny. These results indicate that previously presumed autochthonous Caledonian basement was involved in continental contraction and subsequent collapse of the Caledonian orogen, influencing both the mode and depth of penetration of deformation into Baltica.

Losses of combustible substance on the background of characteristics of fly ashes of the selected polish coal-fired power plants

ABSTRACT The subject of the article is the quantitative–qualitative characterization of unburned carbon in fly ash, occured in power plants in southern Poland, fired with hard coal. Significant differences were found in the chemical and mineralogical composition of ashes, divided in groups regarding the combustion technology, i.e. pulverized boilers and combustion boilers with the fluidized bed. In the grain analysis of the ash samples, an increase in yield of the separated grain classes along with the reduction of grain size was found. The tendency was confirmed that the content of unburned carbon increases along with the increase in grain size. In the analyses of the chemical composition of grains it was found that the thicker coal grains are significantly contaminated with mineral inclusions, which was not observed for the grains smaller than 20 μm in size.

Development of a technique to control and ensure the predefined porosity of a grain layer in the pneumo-separating channel at a grain heap cleaner

To operatively control the state of a layer of the separated grain heap, while cleaning it from impurities in a pneumo-separating channel, it has been suggested to use ultrasonic waves with a frequency of 40 kHz.We have established the relationship between supplying air and a material on the difference from the average values for the lengths of ultrasonic waves paths, acquired from ultrasonic range finders, which are installed at the beginning, in the middle, and at the end of a pneumo-separating channel.Based on this pattern, we have designed a means to control and ensure the predefined porosity of the grain layer in a pneumo-separating channel of the grain layer cleaner. The technique is based on the principle of continuous calculation of the difference between the average values for the lengths of ultrasonic waves paths, acquired from range finders, located inside a pneumo-separating channel. The obtained values are transmitted to the control unit in order to process them by comparing the obtained values with the specified ones. Should a deviation in the obtained values from those specified occur, one has to adjust the supply of a material and/or air to the pneumo-separating channel.The developed means of operative control over the state of a separated layer makes it possible, during cleaning, to maintain grains in a suspended condition at the assigned level of fluidization.This ensures the best conditions for the removal of waste impurities throughout the entire volume of a grain layer, the high quality of grain cleaning at high efficiency of the cleaner.

Study on the optimizing mechanisms of superior comprehensive properties of a hot spray formed Al-Zn-Mg-Cu alloy

In this study, the microstructure of a hot spray formed Al-Zn-Mg-Cu alloy was observed, and the effects of ageing treatment parameters on the precipitation, the mechanical properties and corrosion behavior of the alloy were investigated. The as-deposited Al-Zn-Mg-Cu alloy had a fine equiaxed grain structure with low level of segregation and porosity. After hot extrusion and solution treatment, most of the coarse phases were dissolved, providing a favorable condition for subsequent ageing strengthening. The alloy was subjected to three different ageing treatments: peak-aging, over-aging, and non-isothermal retrogression and re-ageing (NRRA). Results showed that the alloy in peak-ageing condition possessed much better mechanical properties, but poorer corrosion resistance than that in the over-ageing condition. After NRRA treatment, however, great comprehensive performance was achieved for the alloy. In NRRA condition, the optimum combination of the size and number of strengthening phases was responsible for the high mechanical properties, whilst the separated grain boundary precipitates (GBPs) and the higher Cu content of the GBPs contributed to the better corrosion resistance.

Optical and transport properties of new double perovskite oxide

The ceramic material (Pb1.5Ba0.5BiVO6) is prepared through usual solid state method. Its structural and transport properties are explored and a number of interesting results are found from the X-ray diffraction (XRD), scanning electron microscope (SEM), Energy dispersive X-ray spectroscopy (EDS), complex impedance spectroscopy (CIS). In Pb2BiVO6 the substation of ‘Ba’ at A-site also has a double perovskite structure but there is an enormous changes in its micro-structure and cell parameters. In the studied compound high emphasis has been focused on the structure, grain distribution, optical and transport properties. The room temperature XRD, SEM and FTIR study suggests that the compound is single phase new compound, uniform distribution of grains and well separated grain boundaries. SEM micrograph also suggests that the charge carriers could easily finds their path to increase the leakage current and material may to be lossy. The optical band gap of the studied compound has been calculated from UV–Vis spectroscopy analysis and the material can be useful for photovoltaic devices. The absence of any unwanted particles is shown from EDS analysis. CIS analysis of the compound suggest that the transport properties in the material are due to short range mobility as well as hopping type motion.

Effects of oxide isolation layer on magnetic properties of L10 FePt film grown on Si substrate

Magnetic force microscope (MFM) is a powerful tool to subtly detect the stray field distribution of magnetic film or particles on a sub-micrometer scale. Due to its huge uniaxial magnetocrystalline anisotropy (Ku~7107 erg cm-3) and high Currie temperature (TC~500℃), FePt alloy in an L10 phase is expected to be coated on the MFM tip to display high coercive force (Hc) and to improve the magnetic stability and MFM resolution. A grain size of~3 nm will be enough to overcome the super paramagnetism. However, the growing fresh FePt films must experience a high temperature annealing (exceeding 700℃) in order to transform their structures thoroughly from a soft A1 phase into the desired hard L10 phase. This brings the risk of diffusion between FePt coating layer and the underneath Si cantilever. Several admixtures have been attempted by other researchers to obtain granular films with FePt grains separated by oxides, with the purpose to prevent the diffusion from happening between FePt and Si. But apparently, it will be very difficult to fabricate a separated FePt grain exactly on the top of MFM tip. This is a critical factor to affect the MFM resolution. And discussion about the influence of the interface diffusion is avoided in most of published papers. Alternatively, some oxide isolation layers with higher melting temperature can be useful for separating the top FePt film from the bottom Si crystal. In this paper, MgO and SiO2 are selected as isolation layers, deposited by magnetron sputtering. Subsequently, the FePt films are deposited at 400℃ and annealed at different temperatures (500℃ to 800℃) for 2 h. The experimental results indicate that the diffusion between FePt and Si substrate always occurs in the absence of any isolation layer, leading to a reluctant maximum Hc of~5 kOe for 50 nm FePt film. However, the coercive force could remarkably exceed 10 kOe if an isolation layer is used. In the case of MgO, a maximum Hc of~12.4 kOe for 50 nm FePt could be stably measured. However, the annealing temperature must be lower than 600℃ to hold back the occurrence of brittle cracks in isolation layer. Because of the smaller lattice mismatch and expansion coefficient difference between SiO2 isolation layer and Si substrate, the highest annealing temperature could exceed 800℃ when replacing MgO with SiO2. The Hc of FePt film could be adjusted in a range from~5 kOe to~15 kOe by changing the annealing temperature. These findings greatly benefit the fabrication of FePt-based MFM tips with high Hc. And it is expected to be able to effectively enhance the resolution of MFM image.

Grain separation in a straw walker unit of a combine harvester: Process model

The key criteria for the assessment of combine harvester are its capacity, and the quality of obtained grain bulk. The simultaneous minimisation of grain losses and the operation time of combine harvester requires, inter alia, the optimal selection of the construction and operating parameters for the straw walker unit, whereas the phenomenon of grain separation and its determinants depending on these parameters are not yet well understood. Therefore, a mathematical model of the process was developed considering: the rheological properties of a straw layer; the phenomena associated with the dynamic strain of the layer, forced by the motion of straw walkers; and the phenomenon of grain separation from a straw-and-grain mixture. The study included natural and simulation experiments. The effects of the following parameters were analysed: the capacity of the straw walker unit; the phase shift angle of the cranks of the straw walker shafts; the angle of inclination of the straw walker sieve surface; the angular velocity; the initial grain content in the mixture. For each combination of parameters under study, the content of separated grain on selected sections of the lengths of walkers was determined. The simulation results indicate that the quality of separation should not be regarded as a simple consequence of the velocity of straw movement over the surface of walkers. The important factors affecting the quality of separation include the kinematic parameters of walkers, dependent not only on the angular velocity, but also on the phase shift angle and the throw of the crank.

Rock magnetic characterization of the mine tailings in Portman Bay (Murcia, Spain) and its contribution to the understanding of the bay infilling process

The Portman Bay located in the SE Spain has suffered great changes since the 1950s associated with the mining activity. The direct discharge into the sea of mining waste has caused the silting of the bay in a few decades. In this study the magnetic properties of recent sands from a set of 52 samples from the bay and 16 samples from an opencast mine are magnetically analyzed. In particular, we have measured magnetic susceptibility, hysteresis loops, IRM-acquisition, SIRM-IRM and back-field-coercivity spectra, thermomagnetic curves and FORC diagram and took SEM micropictures. Data are correlated with classical magnetite content estimations derived from X-ray diffraction (XRD) in three separated grain sized (coarse, medium and fine grains) and heavy metal derived from X Ray Fluorescence (XRF) in samples from a parallel study at the same sampling sites and the same sampling campaign. The results indicate high concentrations of magnetite (up to 28%) compared to magnetically hard minerals that have not been quantified. Higher concentrations of magnetite are recorded in the central part of the beach, as indicated by Ms, SIRM and Kinit. Coercivity, however, indicates smaller values in the center of the Bay, suggesting a larger size of the magnetic particles. The S-ratio or high coercivity fraction is higher in older samples. Correlation of the magnetic properties with magnetite grain size indicates a positive correlation between Ms and medium and fine grain size fractions, determined by X-ray diffraction. In addition, magnetic properties show a direct relationship between magnetite content and the heavy metals Pb, Cu and As. Our results indicate that the deposition of magnetite was fast and properties have not been modified in depth. However, spatial location in the Bay is significant when we examine distribution of grain sizes. Also, results suggest that magnetite acts as captor of heavy metals.

J0310304 ASME T92材厚肉継手から採取した大型クリープ試験片の破断時および途中止め時損傷評価

Large sized creep rupture and interruption tests were performed for specimens made from ASME T92 thick plate weld joint. For one specimen, creep test was continued till rupture. For another specimen, creep test was interrupted at 60% and 70% of estimated creep life time, 10,000 hours. Rupture time was almost comparable to that of published creep data acquired by standard size specimens. Type IV damage was observed for both, ruptured and interrupted specimens. SEM observations revealed that a number of micro-voids were nucleated at grain boundary of FGHAZ. On the same specimen, growth and cross-linking of micro-voids, heavily damaged and almost separated grain boundaries and grain-sized voids were also observed. These microstructural features were considered to show Type IV damage evolution. An importance was indicated to detect and consider early stage damage, i.e. micro-voids, grain boundary separation, to evaluate residual life of actual component from the earlier stage of usage.

Electrochemical properties of doped ceria electrolyte under reducing atmosphere: Bulk and grain boundary

The electrochemical behavior of a symmetrical cell, Pt/Ce0.8Sm0.2O1.9−δ/Pt, under reducing conditions and wide temperature range (250 – 600 °C) is detailed. In terms of the charge carriers transport through the electrolyte microstructure, AC impedance spectroscopy has been applied to address useful concerns about the transport properties over electrolytic and mixed conduction regimes. The impedance spectra at lower temperature and oxygen partial pressure show the electrochemical response of separated bulk and grain boundary contributions. The increase in the electronic conductivity from 250 to 400 °C shows that the electrochemical reduction Ce4+/Ce3+ is as kinetic as thermodynamically favorable in the experimental conditions. In a typical Nyquist plot of an impedance diagram, until temperatures as low as 400 °C, the high and low frequency arcs can be accessed and the influence of reducing atmosphere over both the components is presented. The apparent activation energy for the electronic process (ΔE) extracted from the total conductivity is 2.54 eV. Distinguished bulk (2.34 eV) and grain boundary (2.63 eV) activation energies point the latter as an energetic barrier in the redox reaction. The oxygen partial pressure dependence of individual capacitances suggests storage of electrical charge along grain boundaries which can potentially behave as a chemical capacitor.

Life Cycle Analysis of Corn Harvest Strategies for Bioethanol Production

Corn (Zea mays L.) and corn stover are currently considered the most abundant and readily accessible feedstock resources for renewable bioethanol. Whole‐plant corn harvest could increase bioethanol yield compared with a conventional separated grain and stover harvest. There is limited research, however, on the environmental effects of whole‐plant harvest strategies, including nonrenewable energy efficiency, greenhouse gas (GHG) emission intensity, and soil organic C (SOC) changes. In this study, harvest methods together with bioprocessing steps were combined through life cycle analysis (LCA) models, and SOC changes for corn farming with different harvest methods were simulated by a Daycent ecosystem model. The harvest data were from four agronomy farms (Branch, Ingham, Huron, and Menominee) of Michigan State University across south to north in Michigan. The LCA results showed that a whole‐plant harvest strategy could increase energy efficiency 3.4 to 4.3 times and reduce GHG emissions by 38 ± 2% relative to a traditional separate grain and stover harvest strategy. The analyses also indicated, however, that whole‐plant harvest could reduce SOC (66.9 ± 22.9 g CO2 equivalent m−2) annually during 50 yr of continuous corn farming at Branch, Ingham, and Huron, while the conventional harvest system could sequestrate CO2 into SOC at Ingham, Huron, and Menominee. The Daycent simulation also showed that a winter cover crop planted after whole‐plant immature corn harvest could compensate for part of the SOC loss associated with a whole‐corn‐plant harvest.

HEAVY MINERAL DIAGNOSIS OF RAS BAGHDADY BLACK BEACH SAND: ACCUMULATIONS AND SIGNIFICANCE

A total of 30 samples each weighs 5 kg were collected from digging boreholes at 2 m depth at constant intervals across three profiles from Ras Baghdady beach sands, Red Sea coast, Egypt. Sieving, heavy mineral separation using Wilfy Shaked table and heavy liquid, magnetic separation using Lift type separator, mineral picking, mineral identifications, XRD, EDX and BSE have been performed to reveal the different mineral groups and the economic potentials. The separated grain size sub-samples arranged in their p order of abundance are 0.25-0.125 mm (10-60%), 0.5-0.25 mm (<10 to 20%), and 0.125-0.063 mm (<5 to 10%). Moreover, less than 1% to 10% are randomly distributed between grain size fractions < 0.063 and 1-0.5 mm. The most promising fraction based on the microscopic investigations containing mineral varieties and groups is very fine sand size. 60 gm of pure heavy minerals produced from 600 gm very fine sand size (0.125-0.063 mm). The light minerals are mainly detrital quartz grains and feldspars with mica flakes while the heavy minerals submitted to magnetic separation. Four separated magnetic sub-fractions (magnetite, ilmenite I, ilmenite II and ilmenite III) and one non-magnetic sub-fraction are obtained. The separated heavy minerals from Ras Baghdady very fine sand size (0.125-0.063 mm) contain 90 % of green silicates and 10 % of other heavy minerals in which ilmenite reaches 52 %, magnetite up to 15 %, garnet up to 11 %, goethite up to 11 %, zircon up to 5 %, rutile up to 3 %, sphene up to 3 % and other recorded traces of combined minerals up to 2 %. Based on the stereoscopic vision, XRD, BSE and SEM investigations, most of the studied heavy mineral grains are angular to sub-angular and homogenous in composition with a few variations to reflect short distance transportation and low energy deposition as depicted from the magnetically separated ilmenite grade III. The relative abundance and lateral distribution of the economic heavy mineral assemblages in the studied area are mainly controlled by hydraulic effects and beach topography. The estimated reserve of the economic heavy minerals within Ras Baghdady beach very fine sand can be summed up as follows; ilmenite 23490 tons, magnetite 6710 tons, garnet 5070 tons, goethite 5140 tons, zircon 2170 tons, rutile 1220 tons, sphene 1490 tons and leucoxene 10 tons. In addition to first record of ruby and sapphire, rare metal and radioactive bearing minerals such as monazite in which rare earth elements range is 61.2%, ~ 6.70 % Th, and ~ 5.4 % U as well as high content of Nd (17. 3%) and Sm (4.37%) are also recorded. Furthermore, the semi-quantitative EDX analyses of the picked uranothorite grains show high content of Th (40.12 %), U (11.77 %), and Y (11.9 %) while xenotime contains high content of Y2O3 (25.53 %), Yb2O3 (4.97 %), Nd2O3 (4.19 %) and Ce2O3 (3.46 %) as well.

Grain separation loss monitoring system in combine harvester

Based on laboratory experimental results obtained with an axial threshing test-rig with tangential feeding, cumulative distribution functions of separated grain in axial and radial directions of threshing rotor were built. Based on the analysis of the relationship between grain separation loss and grain separation flux in an area under the concave, an indirect grain separation loss monitoring method is presented in this paper. Piezo-electric polyvinylidene fluoride (PVDF) film was selected as sensitive material to design a grain flux sensor. While grain and material-other-than-grain (MOG) separated in the monitoring area impact on piezo-electric PVDF films, different electric charges are generated. After signal progressing with a charge amplifier, frequency discrimination and wave shaping, the number of grain can be counted by a microcontroller (MCU) and the grain separation loss of combine harvester can be measured in real-time. Field test results indicated that the measurement errors of grain separation loss recorded by the monitoring system relative to the loss checked manually were less than 12%.

An international terminology for grazing lands and grazing animals

Preface 2 Members of the committee 3 Acknowledgements 3 An International Terminology for Grazing Lands and Grazing Animals 1. Grazing land terms 4 2. Vegetation: descriptive terms 6 3. Forage growth and harvest 8 4. Forage nutritive value and intake 9 5. Management of grazing lands 12 6. Land–forage–animal relationships 15 7. Stocking methods 16 References 18 Appendix I. References and additional information for selected terms 21

Ferric-iron-rich tourmaline from the Darasun gold deposit, Transbaikalia, Russia

We have studied tourmaline of the schorl – dravite – povondraite series in a sample from the Darasun porphyry-style gold deposit, Chita region, Transbaikalia, Russia. A combination of analytical procedures has been used to determine composition in terms of major elements (electron microprobe), Fe 2+ and Fe 3+ (Mossbauer spectroscopy), the probable position of Fe 3+ in the Fe-rich core of a separated grain (FTIR), the Li content (ICP–MS), and conditions of formation (fluid inclusions in coeval quartz). A significant amount of Fe 3+ has been directly determined by Mossbauer spectroscopy (83% of iron is Fe 3+ over the averaged sample). The evolution of chemical composition of the tourmalines studied here can be generalized in the following model. The first generation of low-Al and high-Fe “oxy-dravite” – povondraite (Al~3, Fe~4, Ca~0.2, □ apfu ) is followed by a second generation of higher-Al and lower-Fe “oxy-dravite” (Al~6, Fe~1.5, Ca~0.1, □~0.2 apfu ), and the third generation consists of dravite having the highest Al and the lowest Fe contents (Al > 6, Fe apfu ). Depletion of the second and third generations in Fe is caused by deposition of early sulfides. The evolution in chemical composition of the tourmalines studied here is different from that of redeposited tourmalinites in Western Carpathians, where tourmaline evolves from schorl–dravite to povondraite. The chemical composition of the Darasun tourmalines is different from Fe 3+ -rich tourmalines from evaporite formations in low K, and is similar in Mg content. At the same time, the major type of homovalent substitution (AlFe −1 ) in the tourmalines examined is similar to that in tourmalines from Sn- and Cu-porphyry deposits, and may be accepted as a prospecting guide for the porphyry-style deposits. This finding of povondraite is the third in the world and the first in hydrothermal gold deposit. The fluid inclusions in the associated quartz indicate that that first-stage tourmaline precipitated from boiling fluid at low pressure. Boiling favored the increasing oxygen activity, and resulted in the increase of Fe 3+ in that tourmaline.

Modeling and simulation of grain threshing and separation in axial threshing units: Part II. Application to tangential feeding

The threshing process – by which the grains are removed from the ears – begins effectively at the feeding zone of threshing unit. At the same time, grain separation occurs in the feeding zone of the threshing unit if the rotor cage has openings. This paper presents the application of mathematical model for grain threshing and separation (described in Part I) in an axial threshing unit with separation beginning in the tangential feeding zone. The model describes and quantifies the cumulative percentages of unthreshed grain, free grain, and separated grain over the entire length of the rotor. Grain threshing and separation losses are also quantified. The mathematical model was validated using reliable and comprehensive experimental data. Very good agreement was found between theoretical (predicted) and experimental data for separated grain as well as for threshing, and separation losses of grain over the entire range of testing conditions. Assuming that a set of minimum experimental data is provided for initialization of model parameters, the model can be further used for: • process simulation that means reduction of testing time and associated costs, • optimization of design and functional parameters of threshing unit, • development of control software and process controllers for combine harvesters. This is the only model ever published for this type of axial threshing units.

Bulk and grain boundary conductivity of Ca 0.97Ti 1−xFe xO 3−δ materials

Polycrystalline Ca 0.97Ti 1− x Fe x O 3− δ samples with x=0, 0.01, 0.035, 0.07 and 0.15 were prepared by a conventional ceramic route and characterised by impedance spectroscopy at different temperatures in air. Spectra obtained for samples with low iron contents ( x<0.05) clearly show two separated bulk and grain boundary contributions, which were used to determine the corresponding conductivities. Though the bulk conductivity of those samples increases slightly with additions of Fe, the true grain boundary conductivity was found nearly independent of the content of Fe, except for effects of microstructure, such as differences in grain size. The grain boundary layer thickness was also estimated. The impedance spectra obtained for samples with Fe contents of 7% or higher show a single contribution attributed to the bulk suggesting a very low grain boundary resistance, and thus revealing a major change in grain boundary behaviour relative to samples with small Fe contents.

Effect of frost on the quality of samples of Janz wheat

The effect of frost damage on wheat grain quality was examined in samples of an Australian Prime Hard wheat cultivar Janz. Wheat grain samples that were lightly frosted, severely frosted and unfrosted were obtained from the Riverina district of New South Wales. Each frosted sample was separated by sieving into 2 fractions by size using a commercial grader that was equipped with an aspirator. As the degree of frost damage in the samples increased, grain size decreased, flour extraction decreased, flour ash increased, flour colour deteriorated, dough strength decreased, baking quality decreased, α-amylase activity increased and falling number decreased. Quality assessment of the separated grain fractions showed that the large grains (&amp;gt;2 mm) in both lightly frosted and severely frosted crops were equal or better than the unfrosted sample in all tested quality parameters. The large grain fraction fully met the Australian Prime Hard receival standards and was of quality commensurate with the grade. Separation of grain by size was calculated to be commercially viable for up to 50% frost damage. A commercial flourmill purchased frosted feed grain, followed the sieving procedure, and produced large grain consistent with unfrosted wheat that was subsequently used for normal processing.