Pit Development Research Articles

Characterization of physical mass transport through oil sands fluid fine tailings in an end pit lake: a multi-tracer study

Soft tailings pose substantial challenges for mine reclamation due to their high void ratios and low shear strengths, particularly for conventional terrestrial reclamation practices. Oil sands mine operators have proposed the development of end pit lakes to contain the soft tailings, called fluid fine tailings (FFT), generated when bitumen is removed from oil sands ore. End pit lakes would be constructed within mined-out pits with FFT placed below the lake water. However, the feasibility of isolating the underlying FFT has yet to be fully evaluated. Chemical constituents of interest may move from the FFT into the lake water via two key processes: (1) advective-diffusive mass transport with upward pore water flow caused by settling of the FFT; and (2) mixing created by wind events or unstable density profiles through the lake water and upper portion of the FFT. In 2013 and 2014, temperature and stable isotopes of water profiles were measured through the FFT and lake water in the first end pit lake developed by Syncrude Canada Ltd. Numerical modelling was undertaken to simulate these profiles to identify the key mechanisms controlling conservative mass transport in the FFT. Shallow mixing of the upper 1.1 m of FFT with lake water was required to explain the observed temperature and isotopic profiles. Following mixing, the re-establishment of both the temperature and isotope profiles required an upward advective flux of approximately 1.5 m/year, consistent with average FFT settling rates measured at the study site. These findings provide important insight on the ability to sequester soft tailings in an end pit lake, and offer a foundation for future research on the development of end pit lakes as an oil sands reclamation strategy.

Postharvest bitter pit detection and progression evaluation in ‘Honeycrisp’ apples using computed tomography images

Bitter pit is a physiological disorder that is defined as brown, corky and roundish lesions, which can develop in apples before and after harvest. This disorder greatly reduces the product utilization value of the fruit, and can result in several million dollar economic loss to the apple industry. Computed Tomography (CT) imaging is a non-destructive and rapid sensing technique that can be applied to packaged apples. In this study, healthy and bitter pit Honeycrisp apples were harvested from two field sites and stored for 63 days. CT images of the sampled apples were collected on 0, 7, 14, 21, 35 and 63days after harvest. Images were analyzed to estimate the total pit area in each of the individual apples and were related to pit incidence and progression in different stages of storage. Results showed pit development during the storage period in bitter pitted apples. The rate of progression differed in samples collected from different field sites. Further analysis for pit distribution along each of the bitter pit affected apples showed 54% of pits located at the calyx-end of apples in comparison with middle and stem-end. Classification of healthy and bitter pitted apples using logistic regression based method resulted in false negative of 7–21%.

Hydrology Simulation of Ukud River in Lati Coal Mine

Development of mine pit and overburden disposal has caused dynamic changes in the catchment area of Ukud River, one of the rivers that flow through Lati Mining Operation. The maximum discharge of the river reached 13m3/second and the catchment area occupied a total area of 1901.7 hectares. Since the mining operations started, the river discharge fluctuations have changed considerably. In addition, the catchment area that was dominated by overburden disposal area contained sulphide minerals that potentially degrade the water quality of Ukud River due to the formation of acid mine drainage. Hydrological studies are essential to investigate potential environmental impacts of the mining activities. This study was conducted to determine the characteristics of the hydrologic systems in the mining area using semi-distributed models that can be used to simulate the river flow within catchment area.

Heat Transfer and Mode Transition for Laser Ablation Subjected to Supersonic Airflow**Supported by the National Natural Science Foundation of China under Grant Nos 11332011 and 11472276, the Project of the Chinese Academy of Sciences, and the Defense Industrial Technology Development Program.

When laser ablation is subjected to supersonic flow, the influence mechanism of airflow on laser ablation behavior is still unclear. A coupled thermal-fluid-structure model is presented to investigate the influence of supersonic airflow on the development of a laser ablation pit. Results show that the aerodynamic convection cooling effect not only reduces the ablation velocity but also changes the symmetry morphology of the ablation pit due to the non-uniform convective heat transfer. Flow mode transition is also observed when the pit becomes deeper, and significant change in flow pattern and heat transfer behavior are found when the open mode is transformed into the closed mode.

Monitoring the Quarry Pit Development

Planning and maintaining intact pit slopes in a quarry/mine pit is an important aspect for a sustainable quarry development and operation. It is a main concern in ensuring the constructed pit slopes and benches are stable and safe during quarrying operation activities as well as after permanent closure of a quarry pit. An appraisal for slope instability and failures is conducted at the quarry pit of the Lafarge Rawang Sdn. Bhd. which is located in Rawang, Selangor. Determination of the failures level, integrity and governing geological parameters the contributed to the failures, stability and the hazards are done by field observation, geological mapping and geophysical surveys. The earth resistivity and seismic imaging surveys were conducted to image the subsurface condition such as extent and thickness of limestone bedrock and overburden, including suspicious features like the presence of underground seepage, sinkhole and soil/rock inferred strength indirectly. Occurrences of a few slope failures are considered minor, small scale and localized in nature. The rock slope failures mainly due to structural parameters of the in-situ rock which imposed a heavy jointing intersection and rock bedding plane that coincidently constructed parallel to pit slope face.

Dynamics of development the works of roof coal series of the open pit Gacko by the software Gemcom Gems: Module cut evaluation

This work presents a method of determining the dynamics of development the open pit Gacko in the zone roof coal series with the annual capacity 3∙106 t/year of run-of-mine coal using the module cut evaluation of the software package Gemcom Gems. Defining the dynamics was preceded by optimization of the open pit that is done in the software Whittle. By optimization, the optimum boundary of mining (final contour) was obtained which includes 66∙106 t of run-of-mine coal. The contour of the open, obtained in the process of optimization, was used as the final contour of dynamics of the open pit development. Dynamics was developed for the period from 2016 to 2036 (until the end of service life). In the first 5 years, a detailed dynamics was made for the annual period, and after the fifth year, the dynamics was made for a five-year period.

Effect of harvest date and 1-MCP (SmartFresh™) treatment on ‘Golden Delicious’ apple cold storage physiological disorders

It is recognized that 1-methylcyclopropene (1-MCP) is able to influence fruit ripening, reduce superficial scald and improve post-storage quality in apples. However, 1-MCP may also increase disorders as bitter pit and diffuse skin browning. The objective of this work was to investigate the effect of 1-MCP (625nLL−1) and 3 different maturity stages (early, middle and late harvest date) on the incidence and development of physiological disorders and ripening delay during storage at 0.5°C and subsequent shelf-life at room temperature≈22°C, in ‘Golden Delicious’ apples. Fruit were collected in 6 orchards at a weekly interval, and half were treated with 1-MCP after 3 d cold storage, and the other half left as control. Quality parameters were evaluated at harvest, after 1-MCP treatment and after 6 months storage as well as after 7 d shelf-life. 1-MCP treatment of ‘Golden Delicious’ was effective for slowing softening, reduce electrolyte leakage and color changes associated with ripening (lightness and hue parameters), did not affect soluble solids content and had no clear effect on fruit phenols and antioxidant activity. 1-MCP inhibited superficial scald and significantly reduced rot; however, this treatment enhanced the development of bitter pit in some orchards. Harvest date did not influence scald, bitter pit and firmness but decreased weight loss, total phenols, soluble solid content and antioxidant activity from 2nd to 3rd harvest. The application of 1-MCP, 3 d after cold storage, to ‘Golden Delicious’ apples, reduced ripening and superficial scald, did not induce diffuse skin browning, but increased bitter pit incidence.

Faecal sludge simulants to aid the development of desludging technologies

This paper presents a review of currently available data from the literature on the undrained shear strength, bulk density, stickiness and debris content of faecal sludge. Those data have been used to develop two different simulants that replicate the full range of shear strengths and densities reported for faecal sludge. Comprehensive specifications are also presented for the debris or solid waste found in latrines to more closely replicate the challenge of pumping faecal sludge. Finally, a design guide has been produced to capture these results and support quantitative performance testing of desludging pumps. The simulants have already been used as part of the Bill & Melinda Gates Foundation's Faecal Sludge Omni-Ingestor project and by Water for People's SaniHub in developing improved desludging pumps. The wider use of these simulants could accelerate the development of pit emptying technologies and help standardize the quantitative evaluation of their performance.

Mechanisms regulating apple cultivar susceptibility to bitter pit

Fruit susceptibility to Ca2+ deficiency disorders has been associated cellular localization of Ca2+ and Ca2+ interactions with other nutrients. This study aimed to better understand the mechanisms regulating bitter pit (BP) development by comparing nutrient content and cell wall Ca2+ binding capacity in ‘Fuji’ and ‘Granny Smith’ (GS) apples. After two months of storage at 0°C, ‘Fuji’ apples had no BP, while GS apples had 52.5% BP incidence. Non-pitted GS fruit had higher flesh and skin Ca2+ concentrations than pitted GS fruit, the latter having similar flesh and skin Ca2+ concentrations to ‘Fuji’ fruit. Although ‘Fuji’ apples had the highest cell wall Ca2+ concentration, most of the Ca2+ shifted from the water-insoluble pectin into the water-soluble pectin fraction during storage. In GS, there was a large increase in the Ca2+ concentration in water-insoluble pectin during storage and a small increase in Ca2+ content in the water-soluble pectin. Pitted GS fruit had higher malic acid content, as well as higher [(K++Mg2+)]/Ca2+ and N/Ca2+ ratios in flesh and skin tissues than non-pitted GS and ‘Fuji’ fruit. The results indicate that apple susceptibility to BP can be enhanced by increasing water-insoluble pectin Ca2+, as well as [(K++Mg2+)]/Ca2+ and N/Ca2+ ratios in the fruit.

DIAGNOSING BITTER PIT IN APPLE DURING STORAGE BY CHLOROPHYLL FLUORESCENCE AS A NON-DESTRUCTIVE TOOL

Bitter pit is an important physiological disorder of apple that can develop on the tree but is most prevalent during storage. Delaying fruit maturation after harvest through controlled atmosphere storage and application of 1-MCP SmartFreshTM) can delay the onset of symptoms; however, significant losses may occur in long-term stored apples. It is hard to detect internal bitter pit using external examination alone. Current predictive methods are based on destructive internal quality assessments and mineral analysis. A non-destructive method to detect and predict the propensity of fruit to develop bitter pit at harvest and during the early stages of storage would improve store management practices. High risk ‘Bramley’ orchards were identified from over 100 orchards surveyed across the south east of UK in 2010/11. A subsample of susceptible orchards with fruit that consistently developed bitter pit in storage as well as orchards where fruit remained free from problems were selected. Trials were conducted over two consecutive seasons (2012/13 and 2013/14) to evaluate changes of chlorophyll fluorescence in SmartFreshTM treated and untreated ‘Bramley’ apples during storage. The relationship between chlorophyll fluorescence profiles and bitter pit incidence were similar in the presence or absence of SmartFreshTM. In the early stages of storage, the chlorophyll fluorescence profiles were able to distinguish between SmartFreshTM treated and untreated samples and correlated well with fruit maturity, rate of ethylene production and onset of bitter pit; however, they were less discriminatory in determining the severity of bitter pit in long-term storage. The most discriminant chlorophyll fluorescence characteristics correlated to bitter pit were identified. Models have been developed to predict the likely incidence and development of bitter pit during storage, although they are not capable of estimating severity of the disorder.

تأثير معاملات الكالسيوم المختلفة في تطور النقرة المرة على ثمار التفاح صنف غولدن ديليشس = The Effect of Different Calcium Treatments on the Development of Bitter Bit of Golden Delicious Apple Fruits

تفاح | النقرة المرة | كربونات الكالسيوم | نترات الكالسيوم | كلوريد الكالسيوم | محتوى الأوراق من المعادن | Apple | Bitter Pit | Calcium Nitrate | Calcium Carbonate | Calcium Chloride | Leaf Mineral Content

Initiation and propagation of a single pit on stainless steel using a local probe technique.

Experiments about single pit initiation and propagation were performed on 316L stainless steel with the aim to determine the pitting corrosion behaviour for nuclear waste containers. The experimental setup permits to control the pit development at will and to create reproducible single pits in three dimensions. Radial and deep evolutions of a disc shaped pit were studied for propagation times of up to 10 hours. These evolutions were used to determine what limiting mechanism takes place during long-term pit propagation. Special attention has been paid to the chloride ion action on pitting. A minimum chloride concentration was found to be necessary in the bulk electrolyte to support pit propagation. The existence of a critical pit depth of 230 μm was also underlined.

Induction of symptoms pre-harvest using the ‘passive method’: An easy way to predict bitter pit

An effective method for predicting bitter pit incidence implemented before harvest could be a useful instrument for both the fruit industry and growers. Between 2009 and 2011, various methods for the prediction of bitter pit were evaluated at 60, 40, and 20 days before harvest (dbh) and at a commercial harvest in ‘Golden Smoothee’ apples. Four methodologies, two new ones (the development of natural bitter pit before harvest through the ‘passive method’ and bagging detached fruit before commercial ripening), and two of known efficacy under other conditions (infiltration with magnesium salts and maturity enhancement with ethephon dips) were assessed. To estimate the predictive accuracy of each method, bitter pit-like symptoms were related to the postharvest presence of bitter pit. The ‘passive method’ assesses bitter pit-like symptoms that appear naturally in fruit once they are picked from the tree, and left at room temperature during its evaluation. The ‘passive method’, as well as the infiltration with magnesium salts and ethephon dips, recognized bitter pit-like symptoms approximately 5–7 days after sampling (at 40dbh) and showed significant correlation with the incidence of bitter pit after three months of cold storage. The ‘passive’ and ‘ethephon’ methods were also validated over two additional seasons in 30 and 16 different orchards, respectively. The results of these validations supported the efficacy of using the ‘passive method’ as the main method for predicting bitter pit, without having to use either reactive products or specialized equipment.

Ultra-Fine Grained Degradable Magnesium for Biomedical Applications

Abstract Properties of commercially available purity magnesium and wrought ZM21 Mg alloy were investigated in view of their biodegradable applications. In particular, the opportunities offered by grain size refinement down to the ultra-fine scale achieved by equal channel angular pressing (ECAP) and warm extrusion were discussed and material properties were analyzed. Results show that the grain refinement will lead to a significant improvement in compression strength. The tension strength of the coarse grained alloy is always significantly higher than that measured in compression due to the sharp texture of the starting wrought alloy. ECAP also causes an attenuation of the above texture effects, promoting marked changes in plastic flow behavior. The corrosion behavior of the investigated materials are affected by a combination of microstructural effects such as chemistry, grain size and the extent of lattice distortion inherited from previous processing stages. ECAP leads to refinement of grain size and to increased lattice defect density which apparently produce counterbalancing effects on corrosion performance. The improved dispersion of second-phase particles brings positive effects on development of pitting.

Quantitative monitoring of pitting corrosion based on 3-D cellular automata and real-time ENA for RC structures

A quantitative 3-D cellular automata (CA) prediction algorithm based on real-time electrochemical noise analysis (ENA) has been established for the pitting corrosion monitoring of reinforced concrete (RC) structures. The energy distribution ratio of wavelet energy spectroscopy (WES) has been used to drive a 3-D CA model to qualitatively predict the development of the corrosion pit. The EN characteristics of Q235 carbon steel in simulated concrete pore solutions (SCPS) have been investigated. Finally, the feasibility of the 3-D CA model (driven by the real-time ENA) has been verified by 3-D Ultra-depth Video Microscope experiments.

Technological heredity – A decisive factor for tribological features of regenerated gears

The reparatory hardfacing of damaged contact surfaces is the most reliable method of renewing the tooth shape, dimensions and operating characteristics of failed gears. Proper selection of method suitable for reparatory hardfacing implies knowledge about the mechanisms of contact surfaces wear. The regeneration itself is a complex process made up of a greater number of technological operations, with a very important and strictly determined arrangement. The comparative tribological characteristics of the gears regenerated by hardfacing and newly made ones are considered at the occurrence of initial pits on the teeth surfaces i.e. at the occurrence of primary pitting on the gear tooth flanks. The speed of destructive pitting development in regenerated and newly made gears is also compared in this paper.

Effect of stage development of mining operations on maximization the net present value in long-term planning of open pits

Long-term planning in the mining industry has one main goal: maximizing the value that is realized by excavation and processing of mineral resources. When designing the open pits, determining the stages of development the mining operations, (eng. Pushback) is one of the important factors in the process of long-term production planning. Using the different scientific methods and mathematical algorithms underlying the operation of modern software for strategic planning of production, it is possible to control the business economy. This work presents the influence of the open pit development phase of the South Mining District Majdanpek on significant increase the net present value.

Type II hot corrosion: Behavior of CMSX‐4 and IN738LC as a function of corrosion environment

CMSX‐4 and IN738LC, industrial gas turbine (IGT) aerofoil alloys with low (6.5 wt%) and high (16 wt%) chromium contents respectively, were exposed to type II hot corrosion conditions (700 °C, SOX in air, alkali sulphate/chloride deposits) for up to 1000 h. By comparing detailed pre‐ and post‐exposure dimensional metrology from the samples, the fraction of each sample's surface undergoing the incubation stage (lower levels of sample damage due to the presence of a protective scale) or the propagation stage (higher levels of sample damage due to the direct attack of the base alloy) of type II hot corrosion damage was determined. Corrosion pit development under type II conditions may be described as an extreme event. As such, the transition from incubation to propagation may be modelled using Weibull statistics, which were found to give a good fit to the spread of incubation lifetimes in the exposed IN738LC samples. Much shorter incubation lifetimes were found for the lower chromium content alloy (CMSX‐4). Propagation rates for CMSX‐4 were found not to be constant over time. Instead, when exposed to the higher deposition fluxes, the propagation rates fell after long exposure times as the resultant deposit/corrosion product inhibited the transportation of reactive species. This improved, quantitative understanding of the transition from incubation to propagation damage under type II hot corrosion conditions will assist in the development of quantitative hot corrosion damage models, enhancing IGT component lifetime prediction.

Local scour and the laws of scour pit’s shape downstream of debris flow sabo dam

The erosion shape and the law of development of debris flow sabo dam downstream is a weak part in the study on debris flow erosion. The shape and development of scour pit have an important effect on the stability and safety of debris flow sabo dam, which determines the foundational depth of the dam and the design of protective measures downstream. Study on the scouring law of sabo dam downstream can evaluate the erosion range and reasonably arrange auxiliary protective engineering. Therefore, a series of flume experiments are carried out including different debris flow characteristics (density is varying from 1.5 t/m3 to 2.1 t/m3) and different gully longitudinal slopes. The result shows that the scour pit appears as an oval shape in a plane and deep in the middle while superficial at the ends in the longitudinal section, the position of the maximum depth point moves towards downstream with an increase of flume slope angle. The maximum depth of scour pit is mainly affected by the longitudinal slope of gully, density of debris flow, and the characteristics of gully composition (particle size and the viscosity of soil). The result also indicates that the viscosity of soil will weaken the erosion extent. The interior slopes of scour pit are different between the upstream and the downstream, and the downstream slope is smaller than the upper one. For the viscous and non-viscous sands with the same distribution of gradation, the interior slope of non-viscous sand is smaller than the viscous sand. According to the regression analysis on the experimental data, the quantitative relationship between the interior slope of scour pit, slope of repose under water and the longitudinal slope of gully is established and it can be used to calculate the interior slope of scour pit. The results can provide the basis for the parameter design of the debris flow control engineering foundation.

Changes in antioxidative metabolism accompanying pitting development in stored blueberry fruit

Blueberries (Vaccinium spp. ‘LanFeng’) are harvested and consumed at maturation and have a short storage life at room temperature. Changes in blueberry quality and physiological parameters differ under room or low temperature storage conditions. The storage life of blueberries can be extended at low temperature, but pitting can develop associated with refrigeration, especially during subsequent shelf-life. The objective of this research was to understand the antioxidative metabolism accompanying pitting development of stored blueberry fruit, involving reactive oxygen species and antioxidant systems. Physiological and metabolic disorders, including low firmness, increased cell membrane electrolyte leakage and malondialdehyde (MDA) content, and changes in enzyme activity, were observed in pitting blueberries. Blueberries were stored at 20°C and 0°C for 10 days and 60 days, respectively. Hydrogen peroxide and superoxide radical production rate increased more rapidly during shelf-life after cold storage than at room temperature. On the other hand, blueberries during shelf-life after cold storage, when pitting occurred, had lower activity of antioxidant-related enzymes, including superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX), than those stored at room temperature. The severity of pitting was paralleled by higher cell membrane electrolyte leakage and MDA content, and lower SOD, CAT, and APX activities.