Cleanup Operations Research Articles

Integrated Application of Innovative Technologies for Oil Spill Remediation in Gran Tarajal Harbor: A Scientific Approach

This study examines recovery efforts at Gran Tarajal Harbor following a significant oil spill, employing a combination of innovative technologies tailored to enhance oil spill remediation. Cleanup operations incorporated advanced absorbent sponges with high reusability, absorbent granulates for targeted hydrocarbon capture, bioremediation techniques using allochthonous microorganisms to accelerate natural degradation processes, and the integration of newly designed oil containment barriers coupled with sponges. These technologies were instrumental in effectively mitigating environmental damage, as evidenced by a reduction in hydrocarbon concentrations in sediments from nearly 60,000 mg/kg to under 1600 mg/kg within seven months. Notably, advanced absorbent sponges demonstrated superior capacity for repeated use, optimizing the cleanup process and contributing to the sustainability of the response efforts. The most important finding of this research is the demonstrated efficacy of integrated approach in not only reducing hydrocarbon contamination but also in promoting ecological recovery. Heavy metal analyses revealed that lead and copper concentrations were primarily associated with routine port activities, while mercury levels, attributed to the spill, decreased significantly over time. Tissue analysis of local organisms showed minimal contamination, and assessments of biological communities indicated signs of ecological recovery. This work highlights the necessity of introduce new disruptive technologies in contingency plans.

A dataset of drone-captured, segmented images for oil spill detection in port environments

The high incidence of oil spills in port areas poses a serious threat to the environment, prompting the need for efficient detection mechanisms. Utilizing automated drones for this purpose can significantly improve the speed and accuracy of oil spill detection. Such advancements not only expedite cleanup operations, reducing environmental harm but also enhance polluter accountability, potentially deterring future incidents. Currently, there’s a scarcity of datasets employing RGB images for oil spill detection in maritime settings. This paper presents a unique, annotated dataset aimed at addressing this gap, leveraging a neural network for analysis on both desktop and edge computing platforms. The dataset, captured via drone, comprises 1268 images categorized into oil, water, and other, with a convolutional neural network trained using an Unet model architecture achieving an F1 score of 0.71 for oil detection. This underscores the dataset’s practicality for real-world applications, offering crucial resources for environmental conservation in port environments.

Regional, local and current forecast of the impact hazard of coal seam sites based on seismic monitoring

Relevance. Insufficient validity of the quantitative criteria of the regional, local and current forecast of the impact hazard of the coal seams being developed, the absence of algorithms linking the use of geophysical and direct geomechanical methods in forecasting. Aim. To develop a comprehensive method of geodynamic forecasting, including determining the extent of an impact-prone area identified by the results of a regional forecast based on the registration data of the GITS seismic monitoring system, for conducting local and current forecasts of impact hazard by regulatory methods. Object. An array of rocks of the excavation column 4-1-5-7 of the Osinnikovskaya mine during mining operations in the zone of a group of tectonic disturbances and the intersection of advanced workings. Methods. Regional geomechanical forecast by the geophysical method of seismic activity registration (GITS system), local (current) forecast by natural electromagnetic radiation methods (Angel-M equipment) and the output of drilling fines. Results. The paper introduces the results of complex studies in the excavation column 4 1-5-7 of the Osinnikovskaya mine to establish a correlation between seismic activity and the parameters of the stress-strain state of the array. The authors have introduced the concept of integral indicators of the considered parameters IF and Ikσ. They take into account the area of the zone for the i-th range according to the complex parameter of seismic activity F and the coefficient of vertical stresses in the roof of the formation Kσ. It is established that the informative value of the integral indicators is almost twice as high as the informative value of the initial parameters. Experimental nomograms и are presented to determine the category "DANGEROUS/NON-DANGEROUS" for the regional forecast of impact hazard according to the GITS seismic monitoring system. The authors developed a general algorithm for predicting the impact hazard during clean-up operations. This algorithm uses an integrated approach that includes a regional forecast for recording seismic activity within the mine field and local forecasting methods, both geophysical and direct, to clarify the boundaries of seismic energy release zones and confirm the category of impact hazard. Thу paper introduces the example of determining the width of the zone of increased seismic energy release in the mine closest to the seismically active zone. The dynamics of the occurrence, development and decrease of the seismic energy release zone in the considered areas in the mine workings is shown. The authors give the examples of the implementation of a local forecast of impact hazard in previously established potentially dangerous areas by methods of recording natural electromagnetic radiation of rocks and by the output of drilling fines.

Predictive Modelling of Sea Debris around Maltese Coastal Waters

The accumulation of sea-surface debris around the coastal waters of Malta poses significant ecological and environmental challenges, negatively affecting marine ecosystems and human activities. This issue is exacerbated due to the lack of an effective system tailored to predict surface-debris movement specifically for the Islands of Malta. To address this gap, a pipeline that combines a machine learning-based prediction system with a physics-based model is proposed. This pipeline uses data on historical sea-surface current velocities to forecast future conditions and visualise debris movement. Central to this system are two machine learning models trained to predict surface velocities for the next 24 h for a specific area. These predictions are then utilised in a Lagrangian model to simulate and visualise the debris movement, providing insights into future dispersion patterns. A comparative evaluation of both models using real-world data is made to determine which one performs best in this application. This method offers a tailored approach to addressing sea-surface debris around Malta by accurately predicting sea-surface current velocities and visualising debris movement, improving cleanup operations and marine conservation strategies.

Formulation and Optimization of Effective Oil Spill Dispersants Composed of Surface-Active Ionic Liquids and Nonionic Surfactants.

The use of chemical dispersants to remove oil spills in aquatic environments raises serious concerns, including heightened toxicity and limited biodegradability, which diminish their effectiveness. This study aimed to develop an environmentally friendly formulation by combining two nonionic surfactants (Tween 80, Span 80) with two surface-active ionic liquids (SAILs): 1-butyl-3-methylimidazolium lauroyl sarcosinate [Bmim][Lausar] and choline myristate [Cho][Mys], to remediate crude oil spill. The performance of the formulation was evaluated by its emulsion stability, surface tension, interfacial tension (IFT), and effectiveness. The toxicity and biodegradability of the formulation were also assessed to ensure their safe application in aquatic environments. The formulation (F9) exhibited the most stable emulsion, maintaining stability even after 5 h with a critical micelle concentration (CMC) of 3.52 mM. The efficiency of the formulation in dispersing various crude oils (Arab, Ratawi, and Doba) ranged from 70.12 to 93.72%. Acute toxicity tests conducted on zebrafish demonstrated that the formulation, with an LC50 value of 450 mg L-1, exhibited practically nontoxicity after 96 h. The formulation showed rapid biodegradability, exceeding 60% within a 28-day testing period. This research presents a promising approach for synthesizing the green formulation which can contribute to mitigating the environmental impacts of oil spills and enhancing the efficiency of cleanup operations.

Determination of multi-residue pesticides in dairy products using single-step emulsification/demulsification clean-up strategy combined with low-pressure gas chromatography-tandem mass spectrometry

In this study, a simple, sensitive, and rapid method was developed for the simultaneous determination of 99 kinds of pesticides in fatty milk samples. This novel emulsification-demulsification clean-up approach, coupled with an automatic demulsification-dehydration cartridge, allowed rapid single-step clean-up operation and high throughput. It also achieved effective and selective removal of lipids. The analysis was performed using low-pressure gas chromatography-tandem mass spectrometry (LPGC–MS/MS). Based on the optimal conditions, the targeted pesticides showed good linearity in the range of 5–250 μg/kg, with recoveries of 70–120% at spiking levels of 5, 10, and 20 μg/kg in cow milk, goat milk, and almond milk, respectively. The limit of quantification for most pesticides was 5 μg/kg, and the RSDs were lower than 20%. Analysis of real dairy products obtained from local markets revealed a potential risk in plant-derived almond milk, but no significant risks were found for cow and goat milk.

Abandoned, lost, or otherwise discarded fishing gear in coastal fisheries: A case study in the Baltic Sea coastal waters of Latvia

Abandoned, lost, or otherwise discarded fishing gear (ALDFG) is considered a problem of global concern which can cause considerable negative environmental and socioeconomic consequences. Due to use of slowly degrading plastic materials in fishing gear construction, ALDFG can remain in marine environment for decades. Enclosed marine environments are particularly vulnerable for all types of pollution and anthropogenic effects, including pollution resulting from ALDFG. However, the extent of this problem is often not estimated. We estimated the level of ALDFG accumulated in a semi-enclosed coastal marine environment in the Gulf of Riga and along coastal areas of the Baltic Sea which are particularly susceptible to different types of marine pollution, including ALDFG. We based our results on a pragmatic approach of using existing ALDFG estimates. The results showed a potentially considerable amount of derelict fishing gear accumulated over the last decade, specifically gillnets and entangling nets and trap gear (2762 netting sheets (CI: 969–4976) and 1379 lost traps (CI: 473–2337)). Therefore, this study highlights the need for the fisheries management to implement adequate ALDFG monitoring mechanisms and subsequent clean-up operations to limit continuous pollution and ghost fishing.

Retrieval operations of derelict fishing gears give insight on the impact on marine life

Abandoned, lost and discarded fishing gear (ALDFG), significantly impacts marine ecosystems and biodiversity by incidental capture known as ghost fishing. Such impacts were quantified during the Norwegian Directorate of Fisheries' annual ALDFG cleanup operation in September 2023 by examining the characteristics of retrieved ALDFG and recording the taxonomically sorted catch abundance and biomass. A total of 307 specimens equaling 382 kg of biomass were caught in the recovered gillnets and king crab pots. Gillnets exhibited a 27.3 % greater catch abundance and 50.3 % higher biomass per ALDFG unit mass compared to king crab pots. Margalef, Menhinick, Simpson, Shannon, and Pielou diversity indices showed a more pronounced impact on species richness and biodiversity associated with recovered gillnets. This study introduces an approach to assess the impact of ghost fishing on ecosystems and biodiversity through ALDFG retrieval operations, instrumental in developing estimates of the total ghost fishing capture by ALDFG.

Fluid Contamination Transient Analysis

Successful in-situ fluid cleanup and sampling operations are commonly driven by a fast and reliable analysis of pressure, rate, and fluid contamination measurements. Techniques such as pressure transient analysis (PTA) provide important information to quantify reservoir complexity, while fluid contamination measurements are commonly overlooked for reservoir description purposes. We introduce a new interpretation technique to relate fluid contamination measurements with near-wellbore fluid-transport properties by identifying early- and late-time flow regimes in fluid contamination and its derivative function. The derivative methods used in PTA inspired the development of the new fluid contamination interpretation method. Contamination transient analysis (CTA) evaluates transient measurements acquired during cleanup of mud-filtrate invasion to infer important reservoir flow conditions. Center-point derivative methods are applied to the fluid pumpout volume and time evolution of fluid contamination to identify flow regimes in cases of water-based mud invading either water- or hydrocarbon-bearing formations. We document synthetic examples of the new interpretation method for seven reservoir cases, numerically simulated to obtain contamination data, namely, homogeneous isotropic reservoir, radial boundaries, vertical boundaries, thin-laminated formations, mud-filtrate invasion radius, petrophysical properties, and permeability anisotropy. Single-phase flow and multiphase flow cases are also compared in the analysis. Reservoir boundaries and features are identified in the flow regimes obtained from the combined interpretation of the fluid contamination derivative (FCD) and the log-log plot of the contamination transform. The seven reservoir cases assume fixed reservoir and operational parameters, such as reservoir geometry, rock properties, fluid properties, invasion radius, time of invasion, maximum pumpout rate, and maximum drawdown pressure, to allow for a controlled sensitivity analysis enabling the identification of cleanup trends. It is emphasized that real-time field conditions could trigger certain limitations of the transient techniques developed in this work, such as noisy downhole formation testing measurements, active mud-filtrate invasion, or tool failure. To validate the assumptions, observations, and results of the numerical simulations, a field case is examined to (a) highlight the value of CTA in real-time fluid sampling operations and (b) further investigate its limitations. An alternative validation of the method is performed by applying the derivative directly to the formation testing measurements during fluid cleanup, reducing the uncertainty in the contamination estimation and the interpretation of transient trends. The new approach of the FCD is an alternative to improve fluid cleanup efficiency and to detect the spatial complexity of the reservoir during real-time downhole fluid sampling. Using log-log plots of fluid contamination and the FCD method, we encounter characteristic slopes defining late-time flow regimes. The spherical flow regime gives rise to a slope of –2/3, which has been previously documented by homogeneous isotropic analytical models. Radial flow exhibits a steeper slope of –3 that can be detected when the vertical limits are attained. Boundary effects are evident when the late-time slope of the FCD is equal to –1/3. In addition to the detection of reservoir boundaries, the CTA techniques developed in this paper enable the identification of reservoir fluid type and shale laminations and provide a foundation for the quantification of invasion radius and permeability anisotropy. It is found that cleanup efficiency could be improved based on contamination transient analysis by identifying the flow regimes taking place in the reservoir during filtrate cleanup, hence improving the prediction of the time required to acquire non-contaminated fluid samples.

Beach Litter Variability According to the Number of Visitors in Cádiz Beaches, SW Spain

The amount and composition of litter was evaluated during May and June 2021 at two urban beaches, i.e., La Victoria and La Cortadura, in Cádiz, SW Spain. Surveys were carried out daily in the morning and in the evening during the weekends to quantify the daily accumulation of beach litter and relate it to the number of beach users, which was assessed at around 1:00 p.m. Litter amount was also related to cleanup operations that were very mechanically and manually carried out each day very early in the morning. A total of 8108 items were collected at the two investigated sectors during the study period and beach visitors were quantified in 22 surveys. Plastic was the most common material, representing 82% in La Victoria and 68% in La Cortadura. The most common items were cigarette butts and small, hard plastic fragments. Some litter items that were hazardous to beach visitors were identified, such as broken glass. The number of visitors was positively related to the amount of litter. Significant differences were seen in the litter abundance between the morning and evening assessments since the beaches were cleaned daily and bins were available to facilitate trash disposal. Cleaning operations remove many of the litter items but always leave small quantities of small items uncollected. Efforts to prevent litter on these beaches should focus on informing visitors properly in order to avoid littering and on improving cleanup operations.

Temporal evolution of roof collapse from tephra fallout during the 2021-Tajogaite eruption (La Palma, Spain)

Although dominantly effusive, the 2021 Tajogaite eruption from Cumbre Vieja volcano (La Palma, Spain) produced a wide tephra blanket over 85 days of activity. About one month after the eruption onset, clean-up operations were implemented to mitigate the impact of tephra load on primary buildings. Here, we present a post-event impact assessment of 764 primary buildings, which expands our empirical knowledge of building vulnerability to tephra fallout to include impacts from long-lasting eruptions. Field observations are analyzed in the perspective of existing fragility curves, high-resolution satellite imagery and a reconstruction of the spatio-temporal evolution of the tephra blanket to characterize the evolution of roof collapse due to static loads over time. Thanks to a chronological correlation between the temporal evolution of tephra sedimentation and the timing of clean-up operations, we quantified their effectiveness in mitigating roof collapse. If no clean-up measures had been taken 11% of the surveyed buildings would have exceeded a 75% probability of roof collapse, while only 10 roof collapses have been observed (1.3% of the analysed buildings). This work provides key insights for further development of emergency plans for the management of long-lasting eruptions characterised by the sustained emission of tephra over weeks to months.

The spatiotemporal evolution of compound impacts from lava flow and tephra fallout on buildings: lessons from the 2021 Tajogaite eruption (La Palma, Spain)

The simultaneous or sequential occurrence of several hazards—be they of natural or anthropogenic sources—can interact to produce unexpected compound hazards and impacts. Since success in responding to volcanic crises is often conditional on accurate identification of spatiotemporal patterns of hazard prior to an eruption, ignoring these interactions can lead to a misrepresentation or misinterpretation of the risk and, during emergencies, ineffective management priorities. The 2021 eruption of Tajogaite volcano on the island of La Palma, Canary Islands (Spain), was an 86 day-long hybrid explosive-effusive eruption that demonstrated the challenges of managing volcanic crises associated with the simultaneous emission of lava, tephra and volcanic gases. Here, we present the result of a small-scale impact assessment conducted during three-field deployments to investigate how tephra fallout and lava flow inundation interacted to cause compound physical impact on buildings. The study area was a neighbourhood of 30 buildings exposed to tephra fallout during the entire eruption and by a late-stage, short-lived lava flow. Observations highlight, on one hand, the influence of clean-up operations and rainfall on the impact of tephra fallout and, on the other hand, the importance of the dynamics of lava flow emplacement in controlling impact mechanisms. Overall, results provide an evidence-based insight into impact sequences when two primary hazards are produced simultaneously and demonstrate the importance of considering this aspect when implementing risk mitigation strategies for future long-lasting, hybrid explosive-effusive eruptions in urban environments.

Novel filter-press single-step cleanup approach facilitated rapid screening and accurate quantification of 112 veterinary drugs in aquatic products.

In this study, a novel filter-press cleanup column was developed as a single-step cleanup approach for the rapid screening and quantification of 112 veterinary drugs in fish samples. Fish muscle samples were extracted with acetonitrile and ethyl acetate, sequentially. After concentration and reconstitution, N-propylethylenediamine (PSA) sorbent, packed in filter-press column, allows rapid single-step cleanup operation, while UHPLC-Q-Orbitrap-HRMS provides high-precision mass information in multi-residue screening. Under optimum settings, the detection and quantification limits were validated at 0.5 and 2.0μg·kg-1, for all analytes, respectively. The ranges of recoveries were from 35.3 to 138.4%. Most of these target analytes (82%) could be measured with recoveries between 60 and 130%, and intra-day RSDs ranging from 1.9 to 26.1%. This method was further applied to evaluate the residual of veterinary drugs in fish samples from four cities in China, and results demonstrated its practicability for multi-residue monitoring veterinary residues for food safety administration.

Zinc oxide – mesoporous silica nanocomposite: preparation, characterisation and application in water treatment for lead, cadmium and chromium removal

ABSTRACT Applications of nanomaterials in water and wastewater treatment and in environmental clean-up operations depend on the adsorption capacity of the materials for contaminants such as potentially toxic elements (PTEs). However, on their own nanoparticles can lose effectiveness as contaminant sorbents because of flocculation and aggregation. Embedding nanoparticles within a silica matrix offers one potential solution to the problem; hence, in this study, zinc oxide nanoparticles (ZnO-NP) were embedded in a mesoporous silica (MCM-41) matrix to create a composite material with potential for contaminants removal from water. The composite material (ZnO-mSiO2) and original ZnO-NP were characterised via UV-Vis, FTIR, XRD, TGA/DTA, BET, and SEM techniques, and were then evaluated for their capacities to remove cadmium (Cd), chromium (Cr) and lead (Pb) from water samples across varying conditions (pH, initial contaminant concentration, contact time and adsorbent mass: solution volume ratios). Langmuir and Freundlich adsorption isotherms were fit to the data to describe the adsorption observed. The ZnO-mSiO2 composite material proved highly effective at removing the PTEs (particularly Pb) across a wide range of conditions, with optimum removal rates achieved at pH 7 and above and 90 minutes contact time.

Restoring areas after a radioactive fallout: A multidisciplinary study on decontamination

Land remediation is an important part of restoration measures after a radioactive fallout containing long-lived fission products such as 137Cs. In this multidisciplinary study, we focused on three main issues related to remediation of contaminated urban areas. First, we assessed how much decontamination contributes to reducing resident radiation exposure and how much this reduction depends on the timing of implemented measures. Second, we calculated direct and indirect costs of decontamination in an industrialized country such as Sweden. Finally, in a survey study, we considered reactions of Swedish citizens to being given the hypothetical option of moving to a site decontaminated after radioactive fallout and how this predicted response might influence the design of contingency plans.The main findings are that clean-up operations must be done within the first few years after a fallout to contribute significantly to reducing residual dose. If conducted within 1–2 years, large-scale decontamination can, on average, avert 20–200 manSv per km2 residential area and unit ground deposition of 137Cs (1 MBq). The estimated direct costs (in 2020 purchasing power) would amount to 100 million Euro per km2 decontaminated residential area (comparable to Japanese estimates after the Fukushima accident), generating 39,000 m3 of radioactive waste on average, mainly in the form of 137Cs-contaminated topsoil. In our survey study of 2291 Swedish respondents about their willingness to return to decontaminated homes, women, families with resident children, and high-income earners exhibited more skepticism about returning, even if authorities were to deem it safe. The demographic pattern in attitudes was similar to that found among evacuees in the Fukushima prefecture after 2011.We conclude that predefined ranges of measured 137Cs ground deposition can be used as guidance for rescue leaders in the early post-accident phase in long-term planning for affected areas. This planning should include timing and intensity of decontamination measures, duration of evacuation, and risk communication to citizens. Because some citizens expressed both high risk perception and risk aversion, however, timely and dialogic communication is unlikely to limit a shift after the incident to an older and more male-dominated population composition. There is a risk that those who can afford to do so will move away, whereas people whose wealth is locked in property (houses or businesses) will feel stuck. Perceptions of unfairness may fray the social fabric and complicate resettlement, which in some cases may mean inefficient outlay of decontamination costs. We believe that the issue of monetary compensation to affected residents requires priority in future work.

Petroleum spills and the communicative response from petroleum agencies and companies: Impact assessment from the Niger Delta Region of Nigeria

Petroleum spills in the Niger Delta Region of Nigeria (NDR) have had far-reaching consequences on the entire ecosystem, impacting the aquatic, atmospheric, and terrestrial environments, and significantly affecting the livelihoods of the indigenous population. The adverse effects of these spills often result in violent reactions from the affected communities, leading them to demand compensation from the responsible petroleum agencies or companies. In response to such incidents, the agencies and companies have undertaken efforts to mitigate the situation by actively engaging with the affected communities, seeking to appease and pacify them while conducting cleanup operations. This study explores the environmental impacts of petroleum spills in the NDR and assesses the effects on the host community. A specific focus is placed on examining the communicative responses from various agencies and companies within the petroleum sector. To achieve this goal, the investigation employs a perspective-based review and survey approach, allowing for a comprehensive analysis of the situation from multiple angles.

Understanding the relationship between safety culture and safety performance indicators in U.S. nuclear waste cleanup operations

The relationship between nuclear safety culture and safety performance remains uncertain due to the limited research directly comparing these two variables. This study aimed to help address that gap in knowledge by evaluating the relationships between safety culture traits and two types of performance measures – personal safety and operations indicators – for a U.S. nuclear waste cleanup contractor.Data for 29 performance indicators were correlated with data measuring workforce perceptions on safety culture traits defined by the Institute of Nuclear Power Operations (INPO). Correlation and regression analyses indicated statistically significant relationships between safety culture traits and multiple organizational key performance indicators related to safety, quality and cost savings. Higher scores on safety culture traits were more closely associated with key performance indicators related to the evaluation and resolution of safety concerns, the recognition and accurate categorization of self-revealing and self-identified issues, and emergency response actions. The results suggest that while management strategies to improve safety culture may be linked to key performance indicators that strengthen overall organizational performance, these same strategies may also indirectly degrade the work environment in other areas. These research findings can help managers and safety professionals establish key performance indicators and safety culture metrics that are meaningful indicators of safety performance and inform action plans that improve productivity, enhance workplace safety, and avoid unintended consequences.

A new simpler and reliable method for determining mineral oil in sewage sludge: Influence of biogenic compounds for the quantitative analysis of C10–C40 hydrocarbons

The characterization of organic contaminants in sewage sludge is a fundamental step to address the relevant most appropriate management practice. In this perspective, C10–C40 hydrocarbon content was considered in Italy a crucial parameter to be considered, in spite of its irrelevance in the literature. The very complex mixture of organic substances of both biogenic and anthropogenic origin the sludge is made up of makes sewage sludge a matrix of uniqueness nature, and the analytic determination of hydrocarbon content through conventional procedures may be subjected to overestimation. In this work, optimization of two conventional protocols for the determination of mineral oil (EN14039 and IRSA CNR gravimetric method) were run with attention to anthropogenic compounds potentially affecting the C10–C40 mineral hydrocarbons determination. Effects from the first manipulations of sewage sludge samples to extraction procedure and clean-up operations were investigated.A new simple procedure was set up and tested on 30 samples from different wastewater treatment plants (WWTPs). Through a simple extraction with hexane (12 mL per 2 g of dried sludge, acidified with HCl conc.) at room temperature for 2 h, followed by a clean-up on Florisil column (10 mL–2 g) a confident determination of C10–C40 were obtained with respect to conventional optimized procedures. Variability within the range 0.06–9.49% was calculated with respect to the average value determined using three different methods, with an average value of 2.48 ± 2.37%, demonstrating the robustness of the determination. Up to 3% of the total hydrocarbons were identified as naturally occurring, namely terpenes, squalenes and deoxygenized sterols, passed through the clean-up Florisil column. A significant incidence (up to 75%) of the final overall C10–C40 content was found to be related to the C10–C20 component, originally present in the commercial polyelectrolytes in emulsion, widely used for conditioning before mechanical dewatering.

Проблемы и перспективы внедрения многостадийной выемки руды при отработке запасов калийных месторождений

Introduction. Most of the potash deposits in the world are mined using room-and-pillar mining method with natural support, which is accompanied by high mineral losses, as well as a high mine accidents due to the destruction of supporting elements, waterproof strata continuity and breakthroughs of oversalt water and brines into the mined-out void. Methods. Generalisation, systematisation and analysis of theoretical and experimental research on increasing the extraction ratio of potash ore to establish the methods degree for increasing extraction of potash reserves, to identify unexplored and problematic issues, to determine directions and approaches. Results. Theoretical justification of the possibility and expediency of several-stage stoping for potash mining implementing the principle of re-extraction of reserves from pillars with the provision of necessary protection measures of aquifer in the form of backfill. Conclusion. The article presents the results of an analysis of the specifics of underground mining of potash deposits. The concept of several-stage stoping for potash mining is formulated. Generalized variants of several-stage stoping are presented. The main problems of several-stage stoping implementation at potash deposits are described: the problem of gap-filling in rooms; prediction of altered physical and mechanical properties of seams and host rocks; the influence of multiple excavation on water-resistant properties of waterproof strata in several-stage stoping; the role of time in geomechanical processes; rational composition and recipe of backfill preparation; organization of stowing and clean-up operations at the site; technical and economic expediency of several-stage stoping. Possible lines of approach are suggested. Resume. The use of several-stage stoping for potash mining will increase the extraction ratio, improve the reliability of the waterproof strata during mining by replacing potash seams with a continuous fill mass, utilize waste from potash ore processing, and extend the service life of potash mines. A competent scientific and methodological foundation on the implementation of such technology at potash deposits needs to be built for a deep evaluation of the mining and geomechanical processes in the operation areas and the technical and economic performance of several-stage stoping. Suggestions for practical applications and future research line. The variants of several-stage stoping presented in the article can be used to develop methods of potash mining considering specific mining and geological conditions. Application of the described and similar variants of several-stage stoping in practice will significantly increase the extraction ratio while maintaining a minimal impact on the seam. Future research line will focus on the underground deposit development plan and the geomechanical justification of the parameters of the several-stage stoping.

Utilization of EPRI ChemWorks tools for PWR shutdown chemistry evolution modeling

Shutdown chemistry evolution is performed in nuclear power plants at each refueling outage (RFO) to establish safe conditions to open system and minimize inventory of corrosion products in the reactor coolant system (RCS). After hydrogen peroxide is added to RCS during shutdown chemistry evolution, corrosion products are released and are removed by filters and ion exchange resins in the chemical volume control system (CVCS). Shutdown chemistry evolution including RCS clean-up time to remove released corrosion products impacts the critical path schedule during RFOs. The estimation of clean-up time prior to RFO can provide more reliable actions for RCS clean-up operations and transients to operators during shutdown chemistry. Electric Power Research Institute (EPRI) shutdown calculator (SDC) enables to provide clean-up time by Co-58 peak activity through operational data from nuclear power plants (NPPs).In this study, we have investigated the results of EPRI SDC by shutdown chemistry data of Co-58 activity using NPP data from previous cycles and modeled the estimated clean-up time by EPRI SDC using average Co-58 activity of the NPP. We selected two RFO data from the NPP to evaluate EPRI SDC results using the purification time to reach to 1.3 μCi/cc of Co-58 after hydrogen peroxide addition. Comparing two RFO data, the similar purification time between actual and computed data by EPRI SDC, 0.92 and 1.74 h respectively, was observed with the deviation of 3.7–7.2%. As the modeling the estimated clean-up time, we calculated average Co-58 peak concentration for normal cycles after cycle 10 and applied two-sigma (2σ, 95.4%) for predicted Co-58 peak concentration as upper and lower values compared to the average data. For the verification of modeling, shutdown chemistry data for RFO 17 was used. Predicted RCS clean-up time with lower and upper values was between 21.05 and 27.58 h, and clean-up time for RFO 17 was 24.75 h, within the predicted time band. Therefore, our calculated modeling band was validated. This approach can be identified that the advantage of the modeling for clean-up time with SDC is that the primary prediction of shutdown chemistry plans can be performed more reliably during shutdown chemistry. This research can contribute to improving the efficiency and safety of shutdown chemistry evolution in nuclear power plants.