Sludge effluents and solid deposits generated from the conventional lime treatment processes on the Zambian Copperbelt have led to reports of copper (Cu) and cobalt (Co) contamination into the nearby water bodies. To better understand the behaviour of the metals; partitioning, adsorption and their specific binding forms were studied through sequential extraction, batch adsorption experiments and surface complexation modeling (SCM). Results of mineral composition analyses indicated that micas, kaolinite, quartz and feldspar are abundant with hydrous ferric oxide (HFO) precipitates that formed as a result of the weathering of biotite grains existing as grain surface coating. Sequential extractionrevealed that Cu and Co metals are partitioned in the order of: exchangeable (F1: 600-1500 mg/kg Cu; 100-200 mg/kg Co), acid-soluble (F2: 2200-5500 mg/kg Cu; 190-220 mg/kg Co) and reducible fraction (F3: 2200-5500 mg/kg Cu; 260-300 mg/kg Co). Metals in F1 are hosted by kaolinite, F2 by both kaolinite and HFO whereas in F3 by dominantly HFO. Equal Cu concentration between F2 and F3 is due to both the limited amount of HFO (i.e. 5-10 g/kg) and desorption of loosely adsorbed Cu and Co metals to HFO surfaces. Batch adsorption experiments revealed adsorption as the dominant metal retention mechanism. According to modeling predictions, HFO sites are the dominant metal adsorption sites. At HFO site; >(s)FeOCo+, Co showed adsorption decrease from 40% in single system to 25% in binary system between pH 7 - 7.5 due to metal competition for adsorption sites. The high Cu concentration (i.e. 0.5-1.1% Cu) displaced low Co (i.e. 0.03-0.07% Co) concentration from the adsorption sites present in sludge, thus rendering Co mobile into the environment. To keep the adsorbed metals stable from release, optimal pH of 7.5 is suggested during treatment with lime. At this optimal pH, metals are decreased to below the regulation standard values and with less generation of voluminous sludge. Adsorbed Cu and Co can be recoverable from sludge through acid treatment at pH <3 based on sequential extraction results. The resultant metal-free sludge material has potential of been used as aggregate in construction. (C) 2020 The Authors. Published by Elsevier B.V.

In 2013, the first discovery of gas pools in well LS 208 in intrusive rocks of the Songliao Basin (SB), NE China was made in the 2nd member of the Yingcheng Formation in the Yingtai rift depression, proving that intrusive rocks of the SB have the potential for gas exploration. However, the mechanisms behind the origin of reservoirs in intrusive rocks need to be identified for effective gas exploration. The gas pool in intrusive rocks can be characterized as a low-abundance, high-temperature, normal-pressure, methane-rich, and lithologic pool based on integrated coring, logging, seismic, and oil test methods. The intrusive rocks show primary and secondary porosities, such as shrinkage fractures (SF), spongy pores (SP), secondary sieve pores (SSP), and tectonic fractures (TF). The reservoir is of the fracture pore type with low porosity and permeability. A capillary pressure curve for mercury intrusion indicates small pore-throat size, negative skewness, medium-high displacement pressure, and middle-low mercury saturation. The development of fractures was found to be related to the quenching effects of emplacement and tectonic inversion during the middle-late Campanian. SP and SSP formed during two phases. The first phase occurred during emplacement of the intrusive rock in the late Albian, when the intrusions underwent alteration by organic acids. The second phase occurred between the early Cenomanian and middle Campanian, when the intrusions underwent alteration by carbonic acid. The SF formed prior to oil charging, the SSP + SP formed during oil charging, and the TF formed during the middle-late Campanian and promoted the distribution of gas pools throughout the reservoir. The intrusive rocks in the SB and the adjacent basins were emplaced in the mudstone and coal units, and have great potential for gas exploration. (C) 2017 Elsevier Ltd. All rights reserved.

This study attempts to augment geology and potential hydrocarbon play system database not only in the Maamba Coalfield basin of southern Zambia but in other similar continental non-marine Karoo rift basins in the region as well. Geological analyses were conducted through extensive outcrops and exposures and subsurface boreholes. Six (6) major lithofacies (diamictites, conglomerates, sandstones, siltstones, coal and mudstones) represents Lower Karoo Group sequence. Four (4) mudstone core samples were prepared for thin section petrography. In addition, six (6) samples of sandstones obtained from outcrops, exposures and cores were impregnated with blue epoxy before thin sectioning in order to facilitate easy recognition of porosity. Quantification of framework grain composition and porosity was achieved by point counting a total of 300 points per thin section. The identification of diagenetic constituents and pore types was made possible by the use of scanning electron microscopy (SEM). Rock-Eval pyrolysis analyses utilised 35 core samples of mudstones and coal.According to results of the analyses, three (3) deposition settings which include; alluvial, fluvial-lacustrine and lacustrine setting are envisaged.. Fluvial-lacustrine deposits are host to mudstones and coal source rocks and sandstone reservoir rocks. Mudstones and coal source rocks gave the total organic carbon (TOC) that is well above the recommended thresholds of 0.5 wt % and 2.5 wt % of gas and oil generation respectively. The hydrogen index (HI) values are mostly below 200 mg HC/g TOC, indicating fair quantities of type III kerogen. The thermal maturity readings measured by temperature T-max range from 440 to 485 degrees C in agreement with calculated vitrinite reflectance (ROcalc) range of 0.76-1.57% indicating mature to post mature stages. This maturation is attributed to the burial temperatures and near-surface heat flows by faults. Production Index (PI) values are less than 0.1 suggesting some hydrocarbon expulsion possibly gases and gas condensates. Sandstones are moderate to poor sorted sub-litharenites. Total porosity in sandstones range between 0 and 6.3%, averaging 2.5%, and is mainly secondary porosity resulting from dissolution of labile minerals and fracture. Deposition and diagenetic related controls influenced much of the reservoir quality in sandstones. Lacustrine mudstones are the potential seal rocks. The major Structural traps are faults (e.g. normal and reverse faults) and the stratigraphic traps are sandstones.In this study, our area of focus is in the north and central part of Maamba Coalfield Basin where coal mining and exploration activities are currently taking place. The southernmost part of the basin is under developed such that the hydrocarbon play system potential is still unknown. However, recent coal exploration drilling has revealed the presence of source rocks at depth overlain by extensive overburden seal rocks. Based on the play concept analysis, it is possible to find more encouraging results from this area. (C) 2016 Elsevier Ltd. All rights reserved.

In this work the pyrolysis and evaluation of the product yield from Tchikatanga-Makola (Congo-Brazzaville). The TGA and DTG were performed at different heating rates of (5, 10, 15, 30, 50 degrees C/min); the final temperature reached was 760 degrees C. Fischer Assay analysis of oil shale is 8.12 wt%. The optimal pyrolysis temperature was between 480 degrees C to 540 degrees C, which in an average was 520 degrees C. The results of this work revealed that increasing the pyrolysis temperature to 540 degrees C increases the oil yield. Although the ratio of gas/oil was lower, it was found that at heating rates of 2 and 5 degrees C/min the gas yield increased, and at heating rate of 30 degrees C/min, the oil yield was higher representing the optimal heating rate of pyrolysis. The gas analysis indicated that the gas pyrolysis contain H-2, CO, CO2, N-2, H2S and some C-1-C-4 hydrocarbon. As the temperature increased to 520 degrees C, the oil yield decreased while the gaseous emission still increased. The amount of gaseous hydrocarbon increases due to the secondary reactions such as cracking and aromatization of oil derived from oil shale during retorting, however, the content of CO did not change much. But CO2 decreases due to the decarboxylation of organic matter. The oil analysis shows that the shale oil is essentially composed of 60% aliphatic, 23% non-hydrocarbons, 11% aromatics and 6% asphatenes. The elementary analysis of the oil from pyrolysis is mainly composed of C, H, S, N, O and H/C ratio. Hydrogen and carbon contents in oil shales are higher and increase by increasing the heating rate. This possibly explains the presence of aromatic hydrocarbon products existing in shale oil.

Just like in sedimentary stratigraphy, the volcanostratigraphic boundary is an important factor for constructing volcanostratigraphic framework. The fundamental factor of volcanostratigraphic boundaries is to classify the types and define their characteristics. Based on field investigation and cross-wells section analysis of Mesozoic volcanostratigraphy in NE China, 5 types of volcanostratigraphic boundaries have been recognized, namely eruptive conformity boundary（ECB）, eruptive unconformity boundary（EUB）, eruptive interval unconformity boundary（EIUB）, tectonic unconformity boundary（TUB） and intrusive contacts boundary（ICB）. Except ICB, the unconformity boundaries can be divided into angular unconformity and paraconformity. The time spans and signs of these boundaries are analyzed by using age data of some volcanic fields that have been published. The time spans of ECB and EUB are from several minutes to years. In lava flows, cooling crust is distributed above and below ECB and EUB; in pyroclastic flows, airfalls and lahars, a fine layer below these boundaries has no discernable erosion at every part of the boundary. EUB may be curved or cross curved and jagged. The scale of ECB/EUB is dependent on the scale of lava flow or pyroclastic flows. The time span of EIUB is from decades to thousands of years. There is also weathered crust under EIUB and sedimentary rock beds overlie EIUB. In most instances, weathered crust and thin sedimentary beds are associated with each other laterally. The boundary is a smooth curved plane. The scale of EIUB is dependent on the scale of the volcano or volcano groups. The characteristics of TUB are similar to EIUB’s. The time interval of TUB is from tens of thousands to millions of years. The scale of TUB depends on the scale of the basin or volcanic field. Both the lab data and logging data of wells in the Songliao Basin reveal that the porosity is greatly related to the boundaries in the lava flows. There is a high-porosity belt below ECB, EUB or EIUB, and the porosity decreases when it is apart from the boundary. The high-porosity belt below ECB and EUB is mainly contributed by primary porosity, such as vesicles. The high-porosity belt below EIUB is mainly contributed by primary and secondary porosity, such as association of vesicles and spongy pores, so the area near the boundary in lava flows is a very important target for reservoirs.