Copper tailings reprocessing

in English Copper is widely used in the modern world. An excellent conductor of electricity, it is used in the electrical industry, in the construction industry because of its good corrosion resistance, and in the manufacture of heat exchangers in heating and cooling systems owing to its excellent thermal conductivity. Copper production has increased throughout the twentieth century, and this trend has continued over the last twenty years. The demand for copper is expected to increase significantly by the year 2030. Owing to the high prices of this metal and the lack of deposits, part of the demand can be met by extraction from copper-bearing tailings. In the past, owing to the lower level of technological development and lower copper prices, materials comparable in copper content to the copper ores mined today have ended up in tailings. Since these are already processed materials, the costs of mining, crushing and milling are largely eliminated, making them promising raw materials. The article presents the technological possibilities of reprocessing and also estimates the amount of copper that could be obtained worldwide in this way.

Regression methods for evaluation of the underwater noise levels in the Slovenian Sea

Anthropogenic underwater noise pollution of seas and oceans caused by shipping can have negative effects on marine animals. The aim of this study was to evaluate quantitatively how much the underwater noise levels in the Slovenian Sea were influenced by anthropogenic pressures and meteorological parameters in the period from 2015 until 2018. For this purpose, correlation method and least squares multiple linear regression analysis were used. The results of this study show that the correlation of underwater noise levels with the dredging activity is significant but low, while correlation with the ship densities is insignificant, which could be due to reduced sound wave propagation in the shallow sea levels. Correlation of the underwater noise levels with the wind speed was significant but low to medium, which could be explained by the breaking waves generated by the wind that produced sound.

Site characterization for engineering purposes using geophysical and geotechnical techniques

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. Določitev primernosti tal za gradnjo inženirskih objektov na območju skupnosti Akole v Nigeriji je bila izvedena s pomočjo uporabe geofizikalnih in geotehničnih metod. Izvedene so bile štiri navpične sondažne geo-električne meritve. Za določitev vlažnosti, specifične teže, konsistenčnih mej in kalifornijskega indeksa nosilnosti (CBR) je bilo preiskanih deset vzorcev tal iz različnih lokacij globine 1 m. Geo-električni prerezi so pokazali maksimalno pet različnih plasti s tipičnimi sondažnimi krivuljami tipa AKH in MKH. Na vzorcih tal z oznakami SP2, SP3, SP4, SP6, SP7, SP8, SP9 in SP10 so bile opravljene sejalna analiza, določitev meje zgoščevanja, določitev konsistenčnih mej, specifična teža, optimalna vlažnost in maksimalna suha gostota za mejo zgoščevanja. Vzorci imajo nizko stopnjo plastičnosti in specifično težo, ki spada v dovoljeno območje. Vzorca tal z oznakami SP1 in SP5 imata srednjo stopnjo plastičnosti in spadata pod območje standardnih zahtev. Preiskava s testom CBR je pokazala, da imata vzorca tal SP1 in SP5 nizko nosilnost na obtežbo. Preiskavi VES 1 in 2 sta prav tako pokazali, da sta vzorca SP1 in SP5 nestabilna ter neprimerna za temeljenje pri gradnji inženirskih objektov s plitvim temeljenjem, čeprav bi z odstranitvijo plasti globine do 5 m in armiranjem dosegli primerno nosilnost za temeljenje.

Geochemical Fingerprinting pf Oil-Impacted Soil and Water Samples In Some Selected Areas in the Niger Delta

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. Z več kot petdesetimi leti raziskovanja in pridobivanja nafte na območju delte reke Niger narašča stopnja degradacije okolja zaradi onesnaževanja z ogljikovodiki. Namen raziskave je slediti virom razlitij nafte in porazdelitev onesnaževal v izbranih skupnostih v delti reke Niger z uporabo geokemičnih pristopov. Skupno je bilo odvzetih 16 vzorcev, od tega 10 vzorcev z nafto nasičenih zemljin iz globine 30 cm ter 6 vzorcev vode, od tega dva iz vrtin, dva iz jame ter dva iz površinske vode (en vzorec iz reke in en iz deževnice). Z detektorjem plamenskega ioniziranja s plinskim kromatografom Agilent 7890B (GC-FID) je bila izvedena identifikacija in kvantifikacija alifatskih ogljikovodikov (AH) in policikličnih aromatskih ogljikovodikov (PAH). Identificirani so bili AH z vključujočim pristanom (pristane) in fitanom (phytane) skupaj s 17 PAH. Vrednosti AH in PAH v vzorcih vode se gibajo med 0.13 mg/l do 5.78 mg/l in 0.09 mg/l do 1.109 mg/l. Vrednosti AH in PAH v vzorcih zemljine se gibajo med 22.52 mg/kg do 929.44 mg/kg in 10.544 mg/kg do 16.879 mg/kg.

Estimation of Depth to Bouguer Anomaly Sources Using Euler Deconvolution Techniques

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.

Monitoring after the conclusion of mining works

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.

Underwater noise in the Slovenian Sea

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 (L eq,63 Hz) and 5 dB (L eq,125 Hz), 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.

High-Resolution Biostratigraphic Studies of Step-1 Well, Offshore, Western Niger Delta

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 Globigerina praebulloides, Haplophragmoides spp, Bolivina scalprata miocenica, Valvulina flexilis and Cyclammina cf. minima, two planktonic and one benthonic foraminifera zones were identified as follows: Lower N18, Upper N17 zone (early Pliocene, late Pliocene) and Cyclammina minima zone (late Miocene), respectively. Two biozones were recognized for the nannofossils and include NN12 (Ceratolithus cristatus zone) and NN11 (Discoaster berggrenii zone). These zones were assigned to early Pliocene and late Miocene, respectively. Other forms include Discoaster pentaradiatus, Sphenolithus abies and Ceratolithus armatus. Echitricolporites spinosus/P800zone has been assigned for the Palynomorph assemblages and was dated late Miocene due to the quantitative occurrence of Cyperaceaepollis spp. 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.

Fractional Current Flow in the Subsurface Using Electrical Resistivity Method: A Laboratory Approach

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.

Characterisation of the Wear of the Roller Cone Drill Bit Caused by Improperly Chosen Drilling Regime

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 ‘in situ’ 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.