rss_2.0Materials and Geoenvironment FeedSciendo RSS Feed for Materials and Geoenvironment and Geoenvironment 's Cover of cooling mode in relation to casting and extrusion parameters on mechanical properties of AA6082<abstract><title style='display:none'>Abstract</title><p> In this study, conditional average estimator neural networks (CAE NNs) were used for an analysis of the common influences of the cooling mode in relation to the ram speed, extrusion ratio, casting speed and casting temperature on the yield strength and the elongation of an extruded profile made from aluminium alloy (AA)6082. The obtained results from the analysis revealed very complex relationships between these parameters. In order to maximise the values for the yield strength and the elongation, the values for the ram speed, extrusion ratio, casting speed and casting temperature should be optimised in relation to the mode of cooling.</p></abstract>ARTICLE2017-06-01T00:00:00.000+00:00Geochemistry of Fluvial Sediments from Geregu, Southwest Nigeria<abstract><title style='display:none'>Abstract</title><p> Geochemical analysis of fluvial sediments on the banks of River Ero using inductively coupled plasma mass spectrometry illustrates their maturity, provenance and tectonic setting. The analysed sediment samples show low SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios of 2.92-2.99 (units FL_A, FL_B and FL_E) and high SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> ratios of 4.064-4.852 (units FL_C, FL_D, FL_F and FL_G). Sediments were geochemically classified as shales (units FL_A, FL_B and FL_E) and greywackes (units FL_C, FL_D, FL_F and FL_G). Variability in sediment maturity (FL_F &gt; FL_G &gt;FL_C &gt;FL_D &gt;FL_A &gt; FL_B &gt; FL_E) parallels a decreasing order in the ratios of SiO<sub>2</sub>/Al<sub>2</sub>O<sub>3</sub> and K<sub>2</sub>O/Al<sub>2</sub>O<sub>3</sub>, as well as the proportion of quartz grains and matrix components. Evidence from Al<sub>2</sub>O<sub>3</sub>/TiO<sub>2</sub>, K<sub>2</sub>O, Rb, La/Co, Th/Co, Cr/ Th, Th/Cr, La/Th-Hf, Th-Hf-Co and rare earth element contents of sediment samples suggest felsic protoliths of upper continental crust in a passive margin tectonic setting. An insignificant contribution of mafic components from the source is, however, inferred based on the Ni and Cr contents of the sediment samples. Combined Eu anomalies &lt;0.85 and (Gd/Yb)<sub>n</sub> ratios &lt;2.0 (1.53- 1.82, average 1.65) suggest post-Archean protoliths.</p></abstract>ARTICLE2017-06-01T00:00:00.000+00:00The flexural stiffness and tension state of basalt filter<abstract><title style='display:none'>Abstract</title><p> In recent years, there is a growing demand in Uzbekistan for new, cheap and competitive products from local raw materials, the demand being directly connected with the expansion and development opportunities of the mining, metallurgical and processing industries. In such conditions, the need for providing a solution of the problems faced by these industries is a very urgent one and requires further comprehensive studies. One of these tasks includes assessment of the force parameters and bending stiffness of basalt fibre filters, aimed at further improving the efficiency of local basalt raw materials and aiding in the manufacture of new, long-lasting, reliable and high-quality products. In this case, we studied the interaction of basalt fibre filter with a gas or liquid medium, the deformed state of the fibres under the action force of the gas or liquid, and the filter recovery process after removal of the load, all of which occur during mechanical filtration. These tasks are of interest because during the mechanical filtration of a gas or liquid (hereinafter, mechanical filtration) from solids, all attention is paid to the quality of the filtering process. The filtering quality, as known, is determined by the degree of contamination in the liquid undergoing treatment, duration of separation of the pulp into solid and liquid phases during the decantation process of the mixture and the amount of gas/ liquid released into the atmosphere along with carbon monoxide and toxic impurities. At the same time, the state and behaviour of the filtering material remain as minor factors, the consideration of which can play a decisive role in the establishment of filter life and work capacity. Solutions to these problems are very urgent and allow one to create new technologies for the production of basalt filters based on force parameters and bending stiffness, wherein the purification occurs without the intervention of chemicals.</p></abstract>ARTICLE2017-06-01T00:00:00.000+00:00Diversity of Soil Microbial Communities from an Iron Mining Area (Oued Zem, Morocco)<abstract><title style='display:none'>Abstract</title><p> Microbial communities in the soil were collected from 20 samples of an iron mining area (Ait Ammar, Oued Zem, Morocco), and unaffected samples were analysed to identify the effects of metal concentrations on functional diversity (Biolog<sup>®</sup> EcoPlates), and structural diversity (polymerase chain reaction-denaturing gradient gel electrophoresis of 16S rDNA). Aliivibrio fischeri is mainly used for evaluating polluted soil. The functional diversity was assessed by using such indices as area under substrate utilisation curve, richness, Shannon- Weaver and evenness indices. The analysis of similarities and the non-metric multidimensional scaling analyses of DGGE profiles showed that metals in the soil do not have a significant influence on bacteria. Principal component analysis of Biolog data revealed the similarity in the metabolic profiles of mining samples. These results suggest that the direction and the distance from the iron mine tailings do not have significant effects on the metabolic and structural diversity of the soil bacterial population. The toxicity of metals in soils heavily contaminated with Fe and P did not affect the quantities of microbial populations and did not significantly change the microbial diversity of contaminated soils.</p></abstract>ARTICLE2017-06-01T00:00:00.000+00:00Structural drilling using the high-frequency (sonic) rotary method<abstract><title style='display:none'>Abstract</title><p>In Slovenia, there is widespread use of structural drilling along with classical core drilling. Recently, however, the need has arisen for a highly effective core drilling method with the aid of which high-quality core might be obtained. In order to achieve this aim, one among several Slovenian companies dealing with geological surveying has decided to implement structural drilling using a high-frequency drilling method. The following article presents the theoretical foundations for such a high-frequency method, as well as the manner of its implementation. In the final part of the article, a practical comparison between the conventional and the high-frequency core drilling methods is also provided.</p></abstract>ARTICLE2017-06-01T00:00:00.000+00:00Underwater noise in the Slovenian Sea<abstract> <title style='display:none'>Abstract</title> <p>Continuous underwater noise has been monitored in the Slovenian sea near the lighthouse foundation at Debeli Rtič since February 2015, according to the EU Marine Strategy Framework Directive (MSFD). Anthropogenic noise sources (e.g. seawater densities, dredging activities and cleaning of the seafloor) and meteorological noise sources (e.g. wind speed and precipitation) were analysed in relation to the measured underwater noise levels using several graphical and statistical methods. The results of this study showed that average equivalent continuous underwater noise levels were, by 11 dB (<italic>L</italic><sub><italic>eq</italic>,63 Hz</sub>) and 5 dB (<italic>L</italic><sub><italic>eq</italic>,125 Hz</sub>), higher in the intervals when dredging activities took place than in the intervals when these activities were absent. Variation in underwater noise levels was partly related to the variation of the ship densities, which could be explained by the relatively small acoustic propagation in the shallow seawater. Precipitation level did not indicate any significant association with the variations in continuous underwater noise levels, though some larger deviations in the wind speed were found to be associated with the larger fluctuations in continuous underwater noise levels.</p> </abstract>ARTICLE2021-04-29T00:00:00.000+00:00Site characterization for engineering purposes using geophysical and geotechnical techniques<abstract> <title style='display:none'>Abstract</title> <p>Geophysical and geotechnical techniques were applied to determine the suitability of the sub-surface structure of Akole community area, Abeokuta, Nigeria, for the construction of engineering structures (CES). Four vertical electrical soundings (VES) were carried out, and 10 samples from different points at 1 m depth were analysed to determine soil moisture content, specific gravity (SG), Atterberg limits and California bearing ratio (CBR). The geoelectric sections revealed a maximum of five layers with the typical sounding curves of AKH and HKH types. Sieve analysis and tests for compaction limit, Atterberg limits, SG, optimum moisture content and maximum dry density for compaction limit revealed that samples SP2, SP3, SP4, SP6, SP7, SP8, SP9 and SP10 are of low plasticity with SG values that fall within the permissible range, while SP1 and SP5 are of medium plasticity and their SG values fall below the range of standard specifications. CBR analysis showed that SP1 and SP5 have low load-bearing capacities. VES 1 and 2, linked with SP1 and SP5, are considered unstable and unsuitable to support the CES with shallow foundations; however, excavation of weak layers up to a depth of 5 m and reinforcement will enable the support.</p> </abstract>ARTICLE2021-05-08T00:00:00.000+00:00Estimation of Depth to Bouguer Anomaly Sources Using Euler Deconvolution Techniques<abstract> <title style='display:none'>Abstract</title> <p>The geophysical measurement of variations in gravitational field of the Earth for a particular location is carried out through a gravity survey method. These variations termed anomalies can help investigate the subsurface of interest. An investigation was carried out using the airborne satellite-based (EGM08) gravity dataset to reveal the geological information inherent in a location. Qualitative analysis of the gravity dataset by filtering techniques of two-dimensional fast Fourier transform (FFT2D) shows that the area is made up of basement and sedimentary Formations. Further enhancements on the residual anomaly after separation show the sedimentary intrusion into the study area and zones of possible rock minerals of high and low density contrasts. Quantitative interpretations of the study area by 3-D Euler deconvolution depth estimation technique described the depth and locations of gravity bodies that yielded the gravity field. The result of the depth to basement approach was found to be in the depth range of 930 m to 2,686 m (for Structural Index, SI = 0). The research location is a probable area for economic mineral deposits and hydrocarbon exploration.</p> </abstract>ARTICLE2021-05-03T00:00:00.000+00:00Geochemical Fingerprinting pf Oil-Impacted Soil and Water Samples In Some Selected Areas in the Niger Delta<abstract> <title style='display:none'>Abstract</title> <p>With over 50 years of oil exploration and exploitation in the Niger Delta, there has been an increasing rate of environmental degradation due to hydrocarbon pollution. This study is aimed at tracing the sources of the oil spills and the distribution of pollutants in selected communities in the Niger Delta using geo-chemical techniques. A total of sixteen samples made up of ten crude oil-impacted soil samples taken at a depth of 30 cm and six water samples (two from boreholes, two from burrow pits and two from surface water – one from a river and the other from rain harvest as control) were collected. The identification and quantification of aliphatic hydrocarbons (AHs) and polycyclic aromatic hydrocarbons (PAHs) in the samples were performed with an Agilent 7890B gas chromatography flame ionisation detector (GCFID). The AHs including pristane and phytane, together with seventeen priority PAHs, were identified. The values of AHs and PAHs in the water samples ranged from 0.13 mg/l to 5.78 mg/l and 0.09 mg/l to 1.109 mg/l, respectively, while that for the soil samples ranged from 22.52 mg/kg to 929.44 mg/kg and 10.544 mg/kg to 16.879 mg/kg, respectively.</p> </abstract>ARTICLE2021-05-08T00:00:00.000+00:00Monitoring after the conclusion of mining works<abstract> <title style='display:none'>Abstract</title> <p>After mining works are completed and the mine is permanently closed, the holder of the mining rights must carry out monitoring in accordance with the applicable legislation and for the purpose of controlling the extraction area. This includes monitoring of the changes that have occurred during the process of mining, both on the surface and below it. This article presents an example of a monitoring program after the mining works are completed. The extraction of raw mineral material in an underground mine results in various impacts on the surface and underground space. The areas or segments of monitoring are divided into two parts in this article: The underground part includes monitoring of the geomechanical, climatic, and hydrogeological changes, while monitoring on the surface requires special attention to be paid to the stability conditions of the surface above old mine works and hydrogeological conditions in the area above the extraction or impact area. A practical example of the monitoring program that needs to be made when a mine closes is given in the article. The program covers areas, presents the ways and methods of measurement, as well as reporting of the measurements. The analysis procedure of already existing measurements, which need to be analyzed and included in the preparation of the monitoring program, is also presented.</p> </abstract>ARTICLE2021-05-03T00:00:00.000+00:00Retrogression of Orthopyroxene-bearing Gneiss of Iboropa Akoko, Southwestern Nigeria<abstract> <title style='display:none'>Abstract</title> <p>In this article, we report the mineral chemistry and petrographic features of charnockitic exposure of Iboropa within Precambrian Basement Complex of Nigeria. The mineral assemblages are pyroxene, plagioclase, biotite, hornblende, alkali feldspars, microperthite, quartz and ilmenite, with apatite occurring as accessory mineral. Apatite occurs in abundance as euhedral crystals. Orthopyroxene observed is strongly pleochroic and has numerous microfractures, and it is hypersthene (En<sub>45</sub>Fs<sub>54</sub>Wo<sub>1</sub>) with low TiO<sub>2</sub> and MnO, having extremely low percentage of CaO. Hypersthene is mantled by a complex corona of amphibole, and the amphibole is hornblende with a chemical formula: (K,Na)(Ca,Fe)<sub>2</sub> (Fe,Mg,Al,Ti)<sub>5</sub>(Al,Si)<sub>8</sub>O<sub>22</sub>(OH)<sub>2</sub>. Plagioclase occurs as inclusions in both pyroxene and biotite. Biotite has high concentration of TiO<sub>2</sub> and extremely low CaO. The opaque mineral observed is ilmenite and it is concentrated around hypersthene and amphibole. Rare earth element (REE) displays negative Eu anomaly with enrichment of light REE over heavy REE. Amphiboles surrounding orthopyroxene are evidences of retrograde reactions and are formed at the expense of orthopyroxene reacting with plagioclase and quartz in the presence of fluid. The relationship between the mineral assemblages suggests the retrogression of the gneiss that might be as a result of rehydration process, and it is a transition from granulite facies to amphibolite facies during a retrogressive form of metamorphism.</p> </abstract>ARTICLE2020-07-27T00:00:00.000+00:00Engineering Site Investigation and Shallow Foundation Design in Ore Area of Ondo State, Nigeria<abstract><title style='display:none'>Abstract</title><p>The study integrates geophysical and geotechnical methods for subsoil evaluation and shallow foundation design. The study involved six vertical electrical sounding and geotechnical investigation involving cone penetration test and laboratory soil analysis. Three major geologic units were delineated; the topsoil, weathered layer and partly weathered/fractured/fresh bedrock. The overburden thickness is in between 15.2–32.9 m. Based on resistivity (16–890 ohm-m) and thickness (12.7–32 m) the weathered layer is competent to distribute structural load to underlying soil/rock. The groundwater level varies from 4.5 to 12.3 m. Therefore an average allowable bearing capacity of 200 kPa is recommended and would be appropriate for design of shallow foundation in the area, at a depth not less than 1.0 m with an expected settlement ranging from 9.03–48.20 mm. The ultimate bearing and allowable bearing capacity for depth levels of 1–3 m vary from 1403–2666 kPa and 468–889 kPa for strip footing while square footing varies in between 1956–3489 kPa and 652–1163 kPa respectively.</p></abstract>ARTICLE2020-06-29T00:00:00.000+00:00Environmental Impacts of Mixed Aggregates for use in Unbound Layers in Road Construction<abstract><title style='display:none'>Abstract</title><p>During carbon steel manufacturing, large amounts of electric arc furnace (EAF) slag are generated. EAF slag, if properly treated and processed into aggregate, is an alternative source of high-quality material, which can substitute the use of natural aggregates in most demanding applications in the construction sector, mostly for wearing asphalt courses. In this screening process of high-quality aggregates, a side material with grain size 0/32 mm is also produced, which can be used as an aggregate for unbound layers in road construction. In this study, the environmental impacts of slag aggregate (fraction 0/32 mm) were evaluated in mixed natural/slag aggregates. Different mixtures of natural/slag aggregates were prepared from aged (28 days) and fresh slag, and their environmental impacts were evaluated using leaching tests. It was shown that among the elements, chromium (Cr) was leached from some mixed aggregates in quantities that exceeded the criterion for inert waste. The data from the present investigation revealed that mixed aggregates, prepared from aged slag (fraction 0/32 mm) and natural stone in the ratio 10/90, are environmentally acceptable and can be safely used in unbound materials for road construction.</p></abstract>ARTICLE2020-05-18T00:00:00.000+00:00In Memoriam – Assoc. Prof. Dr Ranko Todorović (30 November 1942–11 December 2019) Deposition Temperature Dependence on the Crystallite Size of NiO Thin Films<abstract><title style='display:none'>Abstract</title><p>In this article, we have investigated a fitting proposal model for calculating the crystallite size of pure NiO thin films by varying the structural parameters, such as full width at half-maximum <italic>β</italic>, lattice parameter <italic>a</italic> and differences in <italic>a</italic> − <italic>a</italic><sub>0</sub>. The experimental data of NiO thin films were prepared at several deposition temperatures in the range of 380–460°C. All estimated values of crystallite sizes are proportional to the experimental data. Thus, the measurement of the crystallite size values by this proposed model is compatible with practical measurements qualitative.</p></abstract>ARTICLE2020-06-15T00:00:00.000+00:00Production and Investigation of New Cast Aluminium Alloy with Lithium Addition<abstract><title style='display:none'>Abstract</title><p>Lithium additions to Al offer the promise of substantially reducing the weight of alloys, since each 1 wt. % Li added to Al reduces density by 3 % and increases elastic modulus. In the present work, the effect of 1.46 wt. % Li addition to AlSi7Mg (containing 7.05 wt. % Si and 0.35 wt. % Mg) was studied. The alloy showed reduced density and higher hardness after natural ageing. Experimental work showed that micro-structural and mechanical properties changed with Li addition. It was observed that 0.80 wt. % Li addition resulted in formation of new phase AlLiSi which has a great effect to increase hardness of AlSi7Mg. According to Scanning Electron Microscope (SEM) and X-ray diffraction analysis it was confirmed that the addition of Li causes formation of different phases which are: α-Al, β-Si and AlLiSi.</p></abstract>ARTICLE2020-06-13T00:00:00.000+00:00Fractional Current Flow in the Subsurface Using Electrical Resistivity Method: A Laboratory Approach<abstract> <title style='display:none'>Abstract</title> <p>The authors describe electrical resistivity method using a laboratory experiment, which was conducted in order to calculate the percentage of current that penetrated each layer of soil arranged in a container using Schlumberger array. Four soil samples arranged in three different set-ups were used. The apparent resistivity obtained was interpreted using curve matching techniques and WinResist iteration yielding types A curve, H curve and A curve, respectively. The interpreted data gave the resistivity of each layer and its thicknesses. The thicknesses obtained from the interpretation were at variance with the actual thicknesses arranged in the container. A multiplier was obtained which serves as a constant in other to obtain the actual thickness. The effective penetration depth of current was determined through the calculated thickness of each layer and the known electrode spacing (AB). The percentage of current that penetrates the layers was found to depend on the electrode spacing as well as the thickness of that layer. Thus, a layer with relatively small thickness has a small percentage of current passing through it compared to a thicker layer.</p> </abstract>ARTICLE2021-03-30T00:00:00.000+00:00Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils in Geotechnology and Mining Applications<abstract> <title style='display:none'>Abstract</title> <p>In geotechnology and mining, tools and equipment interact with aggressive geological material, causing the wear of these components. For this reason, it is important to determine the rate of abrasivity of individual geological materials, depending on the type of interaction with the tool. Various abrasivity tests have been developed in laboratories. Some of them are general, while others are special. What they all have in common is that they attempt to determine the abrasivity of rocks or soils in relation to the wear of the test specimens. This article gives an overview of the laboratory test methods for assessing the abrasivity of geological materials, which are useful in the field of geotechnology and mining engineering. General and special abrasivity tests are presented in detail. The aim of the article is to present existing laboratory tests to assess the abrasivity of rocks and soils, based on which further investigations of wear can be considered as part of a comprehensive approach to this tribological problem. Understanding of the wear mechanisms is the basis for the development of wear-resistant tools and models for predicting the tool life.</p> </abstract>ARTICLE2020-10-17T00:00:00.000+00:00Characterisation of the Wear of the Roller Cone Drill Bit Caused by Improperly Chosen Drilling Regime<abstract> <title style='display:none'>Abstract</title> <p>The rapid drop in the penetration rate or failure of the drill bit during the drilling process delays the drilling process. In our investigation, the ‘<italic>in situ</italic>’ drilling parameters were monitored during the drilling process along with the roller cone drill bit, which is suitable for drilling in soft rock formations (IADC 136). The drill bit was thoroughly examined to determine its damage and wear occurred during drilling along with decreasing penetration rate. The modern and standardised investigation methods were used to analyse the rock materials and the micro- and macro-structure of the materials of the roller cone bit. The analyses were performed by means of optical and electron microscopes, simultaneous thermal analysis of the steel materials, analysis of the chemical composition of the materials of the drill bit and determination of the geomechanical parameters of the drilled rock. The resulting wear, localised fractures and cracks were quantitatively and qualitatively defined and the parameters were correlated to the drilling regime and the rock material. The results of our investigation of the material of the roller cone bit can serve as a good basis for the development of new steel alloys that can withstand higher temperatures and allow effective drilling without structural changes of the steel material.</p> </abstract>ARTICLE2021-03-23T00:00:00.000+00:00High-resolution Biostratigraphic Studies of Step-1 Well, Offshore, Western Niger Delta<abstract> <title style='display:none'>Abstract</title> <p>A high-resolution biostratigraphic study of the STEP-1 well, offshore Western Niger Delta Basin, Nigeria, was carried out using foraminifera, calcareous nannofossils and palynomorphs. The study was aimed at identifying the biostratigraphic zones, age deductions as well as palaeoenvironmental and palaeoclimatic reconstructions. From the studied well section of 609 m (1,829–2,438 m), 50 ditch cuttings were used for foraminifera and calcareous nannofossils, while 25 samples were used for palynological studies at 12 m and 24 m intervals, respectively. Standard laboratory preparation techniques were employed for the three microfossil groups. Due to the occurrence of some forms such as <italic>Globigerina praebulloides</italic>, <italic>Haplophragmoides spp, Bolivina scalprata miocenica, Valvulina flexilis and Cyclammina cf.</italic> minima, two planktonic and one benthonic foraminifera zones were identified as follows: Lower N18, Upper N17 zone (early Pliocene, late Pliocene) and <italic>Cyclammina minima</italic> zone (late Miocene), respectively. Two biozones were recognized for the nannofossils and include NN12 (<italic>Ceratolithus cristatus zone</italic>) and NN11 (<italic>Discoaster berggrenii</italic> zone). These zones were assigned to early Pliocene and late Miocene, respectively. Other forms include <italic>Discoaster pentaradiatus, Sphenolithus abies</italic> and <italic>Ceratolithus armatus. Echitricolporites spinosus</italic>/P800zone has been assigned for the Palynomorph assemblages and was dated late Miocene due to the quantitative occurrence of <italic>Cyperaceaepollis spp</italic>. Four identified major condensed sections include intervals at 1,926, 1,987, 2,097 and 2,316 m, which have been dated 5.0, 5.8, 6.3 and 7.0 Ma, respectively. Based on the benthonic foraminiferal species and Palynological Marine Index, a shallow marine environment is deduced for the studied interval which was interpreted to be deposited under both wet and dry palaeoclimatic conditions. The findings, no doubt could serve as a template for a sequence stratigraphic model, generally beyond the resolution of seismic stratigraphy.</p> </abstract>ARTICLE2021-04-06T00:00:00.000+00:00en-us-1