Natural Deposits Research Articles

Fuzzy-logic indicators for riverbed de-clogging suggest ecological benefits of large wood

Rivers provide dynamic habitats with ecological niches, particularly in their mobile sand, gravel, and cobble riverbed patches that create an active hyporheic zone. Natural or artificial deposition of fine sediment may clog the porous matrix of the hyporheic zone, impairing exchange processes between the subsurface and surface water. Clogging reduces the permeability of the sediment matrix, thus degrading the ecological functionality of the hyporheic zone. Once clogged, the ecological functions may be recovered through active stream restoration, which requires considerate site assessment. To this end, clogging is typically assessed by expert opinion of substrate characteristics including grain size characteristics, porosity, hydraulic conductivity, and interstitial oxygen content. To overcome limitations of expert assessment, such as subjectivity expressed in noisy decision-making, this study introduces a novel fuzzy-logic method based on physically sound rules. The method provides quantitative indicators for clogging and declogging to evaluate the effectiveness of stream restoration. We applied the fuzzy-logic method to test whether the placement of large wood, a common restoration practice, can locally prevent or reduce clogging. Two measurement series from before and after a morphologically effective flood suggested that large wood placements perpendicular to the flow generate elevated amounts of declogging. The tested logs caused a greater amount of declogging within their region of influence than observed at a reference point. The effect was stronger for a log emergent at baseflow. The declogging assessment showed that the novel fuzzy-logic indicators can reasonably overcome subjective judgment by accounting for multi-variate quantitative changes rather than individual parameter trends.

Nonlinear site response analyses for sands: investigating the influence of fabric anisotropy

Nonlinear effective stress site response analyses (SRAs) are commonly used to estimate dynamic soil behaviour, seismic wave propagation through the soil medium, and resulting ground motions [1]. These analyses can be used to identify potential hazards (e.g., landslides, settlements, liquefaction) and to estimate dynamic loads on superstructures in areas that are prone to natural or induced earthquakes, which can help with disaster planning and risk mitigation efforts. In this study, the influence of fabric anisotropy, which is induced during the soil formation process, on the response of sand deposits has been assessed through one-dimensional site response and response spectrum analyses (RSAs). First, a novel anisotropic critical state theory (ACST) based semi-micromechanical constitutive model accounting for the effect of fabric anisotropy has been incorporated into a fully coupled dynamic code employing the u-p formulation. Then, the initial fabric anisotropy has quantitatively (both with respect to intensity and orientation ) been changed to imitate different anisotropic formations observed in natural deposits. The proposed numerical procedure shows that fabric effects stemming from the anisotropic nature of sands can significantly influence the dynamic behaviour of sand deposits, leading to significant variations in ground motions and therefore resulting in diverse spectral accelerations at the ground surface.
 The loading direction dependent behaviour of sands, which can be associated with their anisotropic nature originating from the arrangement of the soil inner microstructure, is generally described/idealized using a second order fabric tensor by ACST based models. Similarly, in this study, a contact normal based second order fabric tensor together with a plastic strain driven fabric evolution formulation has been employed to link the influence of the changing inner microstructure to the relevant constitutive formulations. Further details on the fabric formulations and their multilaminate specific extension can be found in ref. [2] and [3]. Although numerous experimental studies have been conducted to investigate the influence of fabric on the undrained response of sands and advanced constitutive models have been developed to account for it, the majority of research efforts involving anisotropy have concentrated on the element test level, while practical boundary value problem (BVP) simulations are usually omitted. In order to ameliorate that trend, the practical aspects of the fabric effects in BVPs will be investigated in the next section.
 To investigate the repercussions of incorporating fabric effects, two identical SRAs with different initial fabric configurations, i.e., initially isotropic and anisotropic, have been carried out and the resultant response spectrums are presented in Figure 1. These SRAs were performed for a one-dimensional column of 10 m height with a water table located at m depth, subjected to a seismic load taken from the 1987 Superstition Hills earthquake. The initial field stresses were determined assuming . Even though the different initial anisotropic configurations produce similar RSA trends over the range of the period , a significant difference in peak values is observed at sec. Whereas the initially isotropic sand returns a peak value of , its anisotropic counterpart yields (i.e., higher), in which and are the spectral and peak ground accelerations, respectively. Figure 1 illustrates two different types of structure, a one storey building and a four storey building, with approximate natural periods of and , respectively. Since most of the variation in the RSA is observed in the range , it is expected that structures residing in that period range will be affected most by the fabric anisotropy.

Justification of an acceptable modern energy-efficient method of obtaining sodium silicate for production in Kazakhstan

Sodium silicate is used in various industries. Sodium silicate is a basic component in the production of silicate adhesives and paints, silica gel, welding electrodes, corrugated packaging, and geopolymer concretes and cements. All this is currently not produced in the Republic of Kazakhstan. The article discusses the methods of production of sodium silicate and substantiates the possibility of organizing production in the Republic of Kazakhstan. The authors have studied all the available experience in the production of sodium silicate, both now and in the past. At this stage of the research, an analysis was made of the experience in the production of serial and pilot sodium silicate in the USSR in the past and in countries where development has not been suspended at the present time. All possible sources of raw materials of technogenic and natural origin were studied. Business trips and expeditions to natural deposits were carried out and samples of raw materials from various natural and man-made sources were delivered. Studies have been carried out to determine the available volumes of raw materials. Various technologies for melting sodium silicate have been studied, incl. by unconventional schemes, such as smelting in cyclone furnaces. For melting in electric furnaces, various schemes of energy-saving methods for melting sodium silicate were analyzed. Promising ones have been identified. The following types of sodium silicate production were analyzed in the study: traditional smelting (carbonate method), wet method, sodium chloride sublimation method, sulfate method, cullet smelting. The optimal variant has been chosen, which makes it possible to reduce the cost of electricity by several times when introducing a highly efficient innovative technology of electric melting into practice.

Evaluation of Asphalt Produced from Waste Tyre and Polyethylene Terephthalate-Based Bitumen with Paraffin Wax as Rejuvenator

During pavement construction and rehabilitation, large amounts of bitumen are often required. As such, the need for material diversification in pavement construction is essential to conserve the non-renewable natural resource deposits. This study assessed the use of Polyethylene Terephthalate (PET) waste and grounded tyre combined in varying proportions with aged bitumen modifier, and wax as a rejuvenator in the production of asphaltic concrete. A 10% polymer replacement level was maintained for all modified mix batches with three distinct proportions: 6%-PET:4%-GWT, 5%-PET:5%-GWT, and 4%PET:6%-GWT. The rejuvenator was added in percentages 1, 2, and 3 by the total mass of modified bitumen mix. Results showed that the penetration values of the modified bitumen mixes with wax fall between bitumen grades 20–60, indicating suitability in warmer climates. Ductility results indicate an increase in ductility upon modification compared to the control mix. The 6%PET/4%GWT samples obtained the highest ductility values (M2 = 23.5 cm, M5 = 12.5 cm, M8 = 22 cm, M11 = 24.25 cm). The highest softening point value (84.5°C) was obtained with M3 (5%PET/5%GWT/0%wax). The inclusion of wax as a rejuvenator led to massive increases in viscosity values compared to both the control mix and the mixes without wax. Flash and fire point results fell within the same range, implying that the modification and rejuvenation did not yield significant impact on the flash and fire point properties. Marshall stability results showed that no modified bitumen batch obtained stability up to the control mix. The highest flow value (5.9 mm) was obtained with the M12 (5%PET/5%GWT/3%wax) mix. This was about 47.45% higher than that of the control mix and 23.7% higher than that of the corresponding mix without wax. The study recommends material diversification as well as dosage variation as essential in the drive towards achieving optimum stability in asphaltic composites.

Specifics of Asbestos Utilization in the Second Half of the 4th Millenium Bc in the Eastern Fennoscandia (on the materials of lithic workshop Fofanovo XIII)

The authors analys the cultural phenomenon of asbestos ware in the forest zone of North-eastern Europe in the second half of the 4th millennium BC. The dynamic of this phenomenon is studied on the materials of the site Fofanovo XIII, which combines characteristics of metatuff adze and axe workshop, asbestos ware workshop, and interregional center for social communication. Typological and spatial analysis of the ware collections allows us to distinguish two periods of asbestos ware distribution in the late Neolithic-Eneolithic. During the first period (3500–3300 BC), asbestos ware (type Voinavolok) had high social status and was distributed far from the zone of natural deposits of this mineral. Distribution of asbestos ware at this stage fits the model of prestige economy. During the second period (3300–3100 BC), asbestos ware (type Orovnavolok) lost its interregional status. The distribution zone of the asbestos ware had decreased and took its place in linear economic connections. Statistical comparison of the metric parameters of pieces of asbestos collected on the site, as well as phase and chemical analysis show that changes in the social role of asbestos correlated with the downgrade of the mineral raw material quality, and increase of its variability. The authors suggest that this dynamic could be explained in the context of the change in the role of the social centers on the western shore of lake Onega, presented by site Fofanovo XIII.

The effect B impurity and Xe intrusion in the graphite moderator on void reactivity feedback of thermal MSR

Thermal Molten Salt Reactor (MSR) massively utilizes graphite as both moderator and reflector. The molten fuel circulates around the primary loop and directly contacts with the graphite. Gaseous fission products, such as neutron poison Xe-135, are normally separated out from the core. However, deposition of Xe-135 in graphite could take place through direct Xe-135 intrusion into graphite pores, or salt intrusion that eventually undergoes fission in the graphite and leaves the Xe-135 inside. Another possible way of strong neutron absorber deposition in the graphite is boron impurity. Beside reducing the core excess reactivity, the existence of strong neutron absorbers in graphite could alter the core reactivity feedbacks. Thus, this study is meant to analyse the effects of Xe-135 and natural boron deposition in the graphite to the core reactivity feedbacks. The evaluations were done by monte Carlo calculations on their effects on void coefficient, fuel, and moderator temperature reactivity feedbacks. The introduction of void into under-moderated thermal MSR core generally produces positive void reactivity feedback. The deposition of strong neutron absorbers in the graphite decreases the void reactivity coefficient, yet still positive. Despite of core excess reactivity loss, the existence of strong neutron absorber in the graphite is favourable in safety point of view.

Natural Analogue Studies in Support of Post-Closure Safety Assessment of Deep Geological Disposal

Natural analogues are systems that have evolved over geological timescales with features similar to one or several components of a deep geological repository (DGR). Natural analogues complement short-duration laboratory studies since they are existing reflections of many long-term processes that might affect the performance of a repository. Mathematical models are often used for the post-closure safety assessment of a DGR. Confidence in the models’ predictions is enhanced when the models successfully simulate the past evolution of a natural analogue. This paper summarizes the Canadian Nuclear Safety Commission’s (CNSC’s) recent research on natural analogues to inform on (1) glacial erosion, (2) engineered barrier system, and (3) uranium reactive transport in the context of DGRs for radioactive wastes. Glaciation and its erosion are prominent factors impacting the performance of future DGRs at high latitudes in the northern hemisphere. The authors have reviewed the field data from the Greenland Analogue Project, developed a conceptual and mathematical model for the simulation of the thermal conditions within the Greenland ice sheet, as well as the thermal-hydraulic conditions at its base and the ice sheet velocity, and eventually estimated the erosion rate at the site. The Cigar Lake Analogue demonstrates the long-term radionuclide containment capability of the illite clay zone enveloping the ore body, serving as an analogy to the engineered clay barriers. The CNSC and University of Ottawa analyzed 129I in the Cigar Lake core samples, and modeled and correlated the diffusion-dominated transport of radionuclides over the geological evolution of the Cigar Lake deposit. The results provide information on the mobility of fission products and significant radionuclides in conditions analogous to the source, engineered barriers, and near-field host rock of a DGR. The reactive transport and geochemistry of the Kiggavik-Andrew Lake uranium deposit mineralization and remobilization was another natural uranium deposit analogue studied by the CNSC. A reactive transport model was established according to the conceptualized geochemical processes and run under specified boundary and initial conditions to validate the geochemical processes. The geometry, timing, geochemistry, and fluid composition were used as model constraints.

Magnesium isotope fractionation during natural travertine deposition from Baishuitai, SW China

Travertine samples deposited in Earth's surface environments can be used as an effective archive for paleo-climatic reconstruction. As a common element in carbonates, magnesium (Mg) and its isotopic composition in travertine could provide useful information for evaluating paleo-environment changes. In this study, we investigate the Mg isotope systematics in both endogenic travertines (mainly calcite) and spring/stream waters at Baishuitai, Yunnan, SW China. Our results show a systematic increase in δ26Mg value from −1.37 to −1.26‰ for water samples downstream, but varied δ26Mg values between −4.12 and −3.95‰ (average −4.02‰) for solid carbonates, thus a corresponding fractionation Δ26Mgcalcite-water between −2.76 to −2.59‰ (mean value of −2.69‰). Therefore, the solid carbonates preferentially incorporate light Mg isotopes during travertine formation. More interestingly, the Mg distribution coefficient (KMg/Ca) between travertine and water exhibits two variation trends with the calcite deposition rate (Rp) along the canal, which can be explained by the change of calcite formation mechanism from direct nucleation to precipitation via amorphous calcium carbonate (ACC) intermediate. In the upper-stream, the direct nucleation of calcite results in the rapid incorporation of Mg ions into crystal lattice, while a relatively slow precipitation of calcite downstream would incorporate Mg via ACC formation pathway in a quasi-equilibrium pattern. This is consistent with the grain size distribution and crystal morphology observed under SEM. Our results show the important control of water Mg/Ca ratios on the calcite precipitation during travertine formation, and imply the potential and complexity of using Mg isotopes of travertine deposits to reconstruct paleo-environments.

Anthropogenic influence on groundwater geochemistry in Horn Creek Watershed near the Orphan Mine in Grand Canyon National Park, Arizona, USA

Breccia pipe deposits of the Grand Canyon region contain ore grade copper and uranium. Horn Creek is located near the Orphan Mine mineralized breccia pipe deposit, and groundwater emerging from the bedrock in the headwaters of Horn Creek has the highest uranium concentrations in the region. Uranium decreases an order of magnitude between the groundwater at the top of the watershed and the groundwater emerging from the alluvial material lower in the watershed. Horn Creek water has low sulfur and uranium isotopic ratios which may suggest interaction with sulfide and uranium minerals found in mineralized breccia pipe deposits. Per- and polyfluoroalkyl substances were found in low concentrations in groundwater from the bedrock and may be related to mining process materials or other anthropogenic activities. PHREEQC modelling suggests that water that is elevated in uranium emerging from the bedrock in the upper watershed may mix with other groundwater and atmospheric precipitation infiltrated into the alluvial material in the lower watershed. Tritium is elevated in Horn Creek groundwaters, suggesting a component of modern water, some of which may have interacted with Orphan Mine workings. Additional studies could build on this understanding of chemistry changes in the waters of Horn Creek to provide more direct evidence of the contribution of water moving through the Orphan Mine. Supplementary material: Chemical data for this paper are available at https://doi.org/10.5066/F7P55KJN , PHREEQC geochemical simulations are available at https://doi.org/10.5066/P9X17FKG and groundwater chemistry from south of Grand Canyon, AZ is available at https://doi.org/10.6084/m9.figshare.c.6747638 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits

Critical raw materials associated with the lateritic bauxite and red mud in West Kalimantan, Indonesia

The Western Indonesia Bauxite Province in Kalimantan is a lateritic bauxite region with a complex history and poorly known sustainable metal contents within the bauxite residue. Bauxite residue produced using the Bayer process contains, notably, scandium. We present new geochemical, mineralogical and geological data from the lateritic bauxite and red mud from the active mine and deposit, which allow us to investigate the behaviour of critical elements during weathering. The geochemical analysis and translated isocon results have shown that the content of scandium in red mud is higher than the average concentration of crustal rocks and is concentrated in the ferrite layer and bauxite residue. A positive correlation between the existence of iron oxyhydroxide mineral in the residual iron-rich layer and red muds with the rare earth elements (REEs) and scandium concentrations may be interpreted as a scavenging effect of mobile REEs. The weathering and leaching processes in bauxite allows the adsorption of the trivalent scandium cation (Sc 3+ ) on goethite and are followed by ionic substitution with other trivalent cations in crystals of hematite. The study illustrates the importance of understanding processes during weathering and laterization for geochemical processes and REE exploration in tropical areas. Supplementary material: Material A, (A) Mineralogical profile of the bauxite, ferrite, and tonalite in Tayan and Mempawah, (B) Ternary diagram of bauxite and their parent rocks, (C) Trace element ratios in bauxite; Material B, Spearman's correlation rank of bauxite and associated rocks from Tayan mine ( n = 35); Material C, (A) XRD patterns of representative samples from the Tayan mine and Mempawah deposit, West Kalimantan, (B) Typical normal (left) and continuum (right) removed reflectance spectral curves of samples are available at https://doi.org/10.6084/m9.figshare.c.6689139 Thematic collection: This article is part of the Geochemical processes related to mined, milled, or natural metal deposits collection available at: https://www.lyellcollection.org/topic/collections/geochemical-processes-related-to-mined-milled-or-natural-metal-deposits

The use of sugarcane bagasse ashes (sba) in the confection of concrete’s traces and precast, replacing and adding to cement

Concrete is one of the most used construction materials in the world, with cement being one of its main ingredients. The incorporation of Sugarcane Bagasse Ash (SBC) in the production of concrete can present solutions for the use of this agro-industrial by-product and minimize environmental impacts arising from the removal of limestone in the production of cement, in addition to contributing to the reduction of emission of carbon dioxide and preserve natural deposits for cement production. This study aimed to use sugarcane bagasse ash in the addition and partial replacement of cement in the production of concrete. The specimens (TBs) were manufactured following the NBRs 7223 and 5738, in which a ratio was adopted: (1:1.98:3.23:0.61) as primary proposal (T1), and the replacement (T2) and addition (T3) of 5% of Portland cement by mass was performed. The ruptures of the specimens were performed by the compressive strength test of concrete cylindrical specimens at 7, 14, 21 and 28 days of age, after rectification. The results obtained show that it is feasible to use SBA, since the water/cement ratio and the percentage of mass to be replaced or added are appropriate, because both in the addition and the replacement of 5% cement by SBA obtained a gain in strength of concrete.

Spatial distribution characteristics of microplastics in the seawater column and sediments of the artificial reef area and adjacent water in Haizhou Bay

Recently, scholars have been increasing concerned about microplastics (MPs). Unfortunately, information is lacking on the spatial distribution patterns of MPs in coastal seas; therefore, our understanding of the extent of offshore MP contamination remains incomplete. MP distribution in the seawater and surface sediments of an aquaculture area (AA), artificial reef area (AR), and comprehensive effect area (CEA) in Haizhou Bay were investigated in this study. The results showed that the mean abundances of MPs in the surface, middle and bottom seawater were 6.98 ± 3.01 n/m3, 9.12 ± 3.07 n/m3 and 10.20 ± 2.41 n/m3, respectively, and that the abundance in the sediment was 3.09 ± 1.16 n/g. The MP abundance in the bottom seawater was significantly higher than that in the surface seawater (P < 0.05). The correlation among MPs at different depths was not significant, but MPs in most habitats showed a significant correlation. We discovered a significant correlation between the abundance of MPs in the CEA seawater and AR sediments, but not between that in the CEA sediments and AR sediments. MPs can be transported from surface seawater to deeper layers by natural deposition processes. The horizontal transport of MPs due to the coastal gulf current and regular semidiurnal tides lead to the correlations observed in of MP abundance among the AA, CEA, and AR. Migration of MPs from the CEA to the AR was primarily caused by the southern eddies in Haizhou Bay, while migration of MPs from the sediment to the seawater could be due to upwelling in the AR. This was also the main reason there was a lack of a correlation between the sediment from the AR and the seawater from the CEA. This work provides a theoretical and empirical foundation for MP transport and source tracking.

Public Exposure to Natural Radioactivity Near Uranium Deposits in Manyoni Area, Central Tanzania

Assessment of public exposure to background radiation was performed in Manyoni, Tanzania to address public concerns following the discovery of uranium deposits in their neighborhoods. Results show that the highest concentrations of radionuclides are 112, 95 and 463 Bq.kg-1 for 226Ra, 232Th and 40K, respectively. The highest annual effective dose to the public is 2.91 mSv.y-1 with a mean value of 1.29 mSv.y-1. Authorities may use these results to address public concerns as well as the baseline information. Further investigations on public exposures in Manyoni are recommended.

Formation and stability of studtite in bicarbonate-containing waters

Studtite and meta-studtite are the only two uranyl peroxides found in nature. Sparsely soluble studtite has been found in natural uranium deposits, on the surface of spent nuclear fuel in contact with water and on core material from major nuclear accidents such as Chernobyl. The formation of studtite on the surface of nuclear fuel can have an impact on the release of radionuclides to the biosphere. In this work, we have experimentally studied the formation of studtite as function of HCO3- concentration and pH. The results show that studtite can form at pH ≤ 10 in solutions without added HCO3-. At pH ≤ 7, the precipitate was found to be mainly studtite, while at 8 ≤ pH ≤ 9.8, a mixture of studtite and meta-schoepite was found. Studtite formation from UO22+ and H2O2 was observed at [HCO3-] ≤ 2 mM and studtite was only found to dissolve at [HCO3-] > 2 mM.

Nitrogen-doped hollow carbon nanoparticles with optimized multiscale nanostructures via dolomite-assisted chemical vapor deposition for high-performance potassium-ion capacitor

Carbon-based materials are considered as promising anode candidates for potassium-ion storage with the key bottlenecks lying in the slow kinetics and huge volume expansion caused by the large size of K+. Herein, nitrogen-doped hollow carbon nanoparticles (NHCP) with optimized multiscale nanostructures are synthesized by a natural template-assisted chemical vapor deposition process. Benefiting from the stacking nanoparticles structure with hierarchical pores, high level of pyridinic-/pyrrolic-N, and enlarged interlayer spacing, the constructed NHCP anode delivers superior K+ storage properties in terms of high reversible capacity (412.7 mAh g−1 at 0.03 A g−1), favorable rate capability, and long cyclic stability. The detailed experimental and computational studies reveal the combined storage mechanism of K+ adsorption and insertion in the multiscale nanostructure of NHCP. To achieve high areal capacities, self-supported NHCP electrodes with high mass loadings (3.41 and 6.23 mg cm−2) were constructed by a vacuum-assisted infiltration process which exhibits greatly improved areal capacities as compared with the traditional slurry coating electrode. The assembled full-carbon potassium-ion capacitor based on NHCP anode exhibits high energy and power densities (168 Wh kg−1 and 9.4 kW kg−1) and a long cycling lifespan (83.9% capacity retention after 10000 cycles at 1.0 A g−1). This work provides a facile fabrication method for porous carbon electrodes with high mass loadings and capacities, which holds the potential for practical application.

Modeling soil accretion and carbon accumulation in deltaic rice fields

Rice cultivation is popular in low-lying areas such as deltas, but climate change threatens the viability of the crop. In recent decades, the resilience of deltas to sea level rise (SLR) has been influenced by the reduction of sediment load from rivers due to the construction of dams, disrupting natural deposition in deltaic plains. Sediment and organic matter accumulation in wetlands are key to vertical accretion in the face of SLR and soil organic carbon (SOC) sequestration. In this sense, deltaic rice fields can retain sediments as well as wetlands and promote SOC sequestration, which is effective in adapting to SLR. In the Ebro Delta, the sediments that reached the fields through irrigation channels were used to build up and form rice fields in the wetlands of the area. We hypothesize that this sedimentation has been key to vertical accretion and SOC sequestration in rice fields. These processes were simulated by developing a process-based cohort model inspired by accretion in marsh equilibrium models (MEM). The model was able to simulate the soil carbon profile of rice fields in the Ebro Delta, based on the soil-accretion concept and considering the spatial heterogeneity of the area. Its predictions of vertical accretion and carbon content were more accurate for mineral and clay-like soils than for organic and sandy soils. Topsoil decomposition rate and organic matter content were the parameters that most influenced predictions of total vertical accretion and final soil organic carbon stock. Simulations were carried out according to future climate change scenarios, considering restoration of river sediment flux, to evaluate effects on SOC sequestration and vertical accretion in rice fields. Results showed that only with significant river sediment restoration did rice fields show positive vertical accretion, which facilitates SOC sequestration.

Chinese mining industry: state of the art review

The territory of the present-day People’s Republic of China is rich in mineral and energy resources which stimulate the growth of the extractive industry in the country. China is currently the world leader in the production of 31 commodities (mineral products): molybdenum, tungsten, iron, aluminum, lead, zinc, gold, coal, gypsum, bentonite, and many others. This stimulates the development of the appropriate infrastructure and training of specialists in the mining industry, the development of international links for investment and the exchange of best production practices. The purpose of this work was to study the history of exploration and extraction of natural resources, establish a domestic strategy for the development of the mining and metallurgical sector, and review leading Chinese mining and metallurgical companies. The paper reviewed key domestic processes in China which would affect the domestic and global mining and metallurgical industry. An assessment of natural resource deposits throughout the whole territory of the country was carried out with their brief description, highlighting the prime prospects, and presenting commodity reserves. The paper presents the main challenges for the mining and metallurgical industry to be met in the 14th Five-Year Plan. The development of the industry up to 2025 implies the expansion of extractive capacities with an overall reduction in dependence on imports, enhancing exploration programs, and the reduction of harmful emissions from operating enterprises, etc. Special attention is paid to publicly traded mining and metallurgical companies in China. The leaders in each sector are presented, and their brief economic indicators are given.

Environmental assessment in concrete pole industries

PurposeCompanies that manufacture poles generate several negative environmental impacts, whose extent needs to be assessed to find ways to mitigate them. MethodsIn this research, Life Cycle Assessment (LCA) was used as a methodology to measure the potential environmental impacts throughout the poles' life cycle. Primary data (amount of cement, gravel, sand, steel rebars, energy, water) were collected from industries located in Teresina, Piauí, Brazil, and information from the Ecoinvent 3.7.1 database (transport, solid waste, liquid effluents, particulate matter) was used. Results and discussionThe literature addresses pole production from a different perspective, making this study relevant to disseminate the life cycle thinking in concrete pole production. However, the literature points to a correlation trend for ecotoxicity and human toxicity indicators, as well as the results found in this research. Waste disposal stands out as an important source of impact for these industries, confirming the necessity of efficient management of these materials at the end of their lifespan and during the production process. The scenario analysis showed that is possible to reduce the potential impacts of these industries. ConclusionThe reuse of waste within the industry itself is feasible (using a shredder for this purpose) and can contribute to decreasing the extraction of natural deposits in various production processes related to the poles' life cycle and reducing their accumulation in the environment. The use of inputs from closer suppliers is a strategy that contributes to mitigating the potential impact of gaseous emissions, reducing the impact that generates global warming and climate change. In addition, other papers show viable alternatives in different scenarios, based on complex laboratory studies. Nevertheless, his approach shows how impacts can be mitigated with the adoption of simple actions such as the reuse of effluents and residues from these industries. It is possible to redefine the production process through a scenario close to the ideal, bringing environmental sustainability to the sector.

The role of addition of calcium alginate microcapsules on permanent deformation of AC–WC natural asphalt Buton stone in Indonesia

This paper discusses natural asphalt deposits of Buton stone (asbuton) in Indonesia are very abundant, but the characteristics of asbuton are not yet suitable for road applications. So that the use of asbuton as a binder needs to be added with additives that can react independently to overcome the permanent deformation such as the addition of calcium alginate microcapsules to the asphalt mixture. The purpose of this study was to determine the effect of adding calcium alginate microcapsules to the permanent deformation of AC-WC with asbuton. The current problem is that road pavements are not able to heal themselves when cracks start to occur, so additional materials are needed that can stimulate self-healing to occur so that the cracks that have started to occur can be closed again even though it takes time so that the self-healing process can occur. The microcapsules are made with the main ingredients of water, sunflower oil, sodium alginate (C6H7O6Na) and calcium chloride solvent (CaCl2), which are encapsulated and embedded in the asphalt mixture as a material that can restore the structural function by a healing method self healing. The research method uses true experimentally. Specimen variations in the study were the addition of calcium alginate microcapsules of 0 %, 1 %, 1.5 %, 2 %. Wheel Tracking Testing was carried out with the AASHTO Standard: T 32-11 and CAL Testing with the Tex-245-F 2014 standard. The results showed that with the addition of calcium alginate microcapsules, there was no significant contribution; better than microcapsules, the mixture decreases in the number of passes so that the mixture is easy to change shape rutting. However, adding calcium alginate microcapsules can reduce the value of weight loss, causing the adhesion of the asphalt mixture to increase

A case study on marmatite- pyrite/pyrrhotite selective flotation with two-step pulp regulation

Zinc occupies a vital position in modern industrial production, and zinc metal is mainly extracted from marmatite or sphalerite. Marmatite or sphalerite is often associated with pyrite and pyrrhotite in natural polymetallic sulfide deposits. Therefore, how to well achieve the selective separation of marmatite or sphalerite from associated pyrite and pyrrhotite is an important issue, because it is directly related to the efficient and sustainable utilization of zinc-bearing sulfide mineral resources. In this paper, a systematic research taking the selective separation of marmatite from high-sulfur sulfide ores as its core, was conducted. The results confirmed that pulp redox potential (Eh) as well as dissolved oxygen (DO) dominated the selective separation of marmatite from associated pyrite and pyrrhotite, and the Zn recovery and Zn grade of zinc concentrates could be greatly improved by controlling Eh. As a result, an effective and feasible operating mechanism with two-step Eh regulation was first established. The findings are expected to help scholars understand the marmatite-pyrite/pyrrhotite (Zn-S) selective flotation better, favor the beneficiation of high-sulfur polymetallic sulfide ores in study or practice, and provide important inspirations for the theoretical research or practical utilization on other similar sulfide resources, especially those containing pyrrhotite.