Bed Separation Research Articles

Being Wrong

Does a triumphant marriage require love? In this philosophical short story, Donna wed her high school sweetheart, nurtured three splendid offspring, only to find herself gradually adrift in emotional detachment from her husband. With her spouse laboring in a distant city, their encounters dwindle, and when they do occur, separate beds are the norm. Amidst a supportive yet ardor-deficient matrimony, Donna crosses paths with Chris, a local carpenter. An unconventional connection sparks, ultimately propelling her into an affair. The eventual decision to divorce her husband for the sake of newfound love sees her embracing Chris, a man deemed less conventionally attractive and materially successful. This choice ignites fury within her children, who lay blame on Donna for the divorce.

Uploading into Eternity

Uploading into Eternity

A review of all aspects of dry coal cleaning methods and evaluation of widely used applications

Although there are many developments in the energy industry, coal still holds its vital place and seems to have a major role in future. That is why the direct utilisation of coal becomes impractical even impossible in those days. Thus, the aim of this review is for all aspects of dry coal cleaning methods be overviewed, analysed and evaluated, including the applicability to the industry in the face of wet methods. The density-based methods have potential than the other dry coal cleaning methods and have made great development within the coal preparation industry. The Ep values of air jigs or air tables are between 0.13 g/cm3 and 0.26 g/cm3, but fluidised bed separation method are between 0.03 g/cm3 and 0.07 g/cm3. It provides rivalry with wet methods and is a serious alternative for coal preparation. [Received: January 17, 2022; Accepted: July 20, 2022]

Design of a shelf pneumatic classifier for separating a polydisperse mixture of granulated superphosphate

The object of this study is a polydisperse mixture of granular superphosphate. It is emphasized that existing technologies of granulation and processing of granules lead to the formation of dusty fractions of small particles. The content of small fractions in the finished product should be minimal and, in connection with this problem, the task is to remove small particles from the mixture. The purpose of the current experimental study is to classify a polydisperse mixture of granular superphosphate in a pneumatic classifier. The device includes an inclined perforated shelf with an unloading space between its end and the wall of the apparatus. It has been experimentally revealed that the maximum efficiency of extraction into the entrainment of small particles is achieved with a width of the discharge space equal to 0.5 of the length of the cross-sectional side of the apparatus; the degree of perforation of the shelf is 5 %; the angle of inclination of the shelf is 25–30°; the speed of the gas flow in the free section of the apparatus is 3.7 m/s. It is shown that the degree of extraction into the entrainment of a small fraction less than 1 mm in size reaches 70–75 %, the content of the small fraction in the carry-over is 96–98 %, and the large fraction is less than 5 %. By processing experimental data, an empirical equation was built that makes it possible to determine the concentration of particles in the gas stream for individual fractions of the material. It is shown that due to the implementation of an active aerodynamic weighing mode, the shelf pneumatic classifier works at specific loads for air flow rate less than the typical designs of fluidized bed separators. It is noted that the effective operation of the shelf pneumatic classifier in the production of granular mineral fertilizers is ensured at a productivity of no more than 10–12 t/h. With greater productivity, there is a need to install several devices in the technological line

The spatial distribution characteristics of autogenous medium and its effect on low rank lignite beneficiation in differential-motion dry cascade beneficiation bed

In the mining process, a large amount of inorganic mineral impurities are produced, leading to the grade reduction of lignite. Promoting the efficient separation and utilization of low rank lignite is the key measure to stabilize energy structure. In this paper, differential-motion dry cascade separation bed was used for separation, ash reduction and upgrading for low rank lignite. The spatial distribution characteristics of 1.5–0 mm pulverized coal particles in the differential-motion dry cascade separation bed was emphatically investigated. The influence of selecting 1.5–0 mm pulverized coal particles as autogenous medium on the uniformity and stability of bed density was systematically analyzed. The interlayer distribution law of low rank lignite in differential-motion dry cascade separation bed was dissected. The results shows that the leading particle size fraction and the leading density fraction of autogenous medium particles are d = 0.25–0.125 mm, ρ = 1.8–2.0 g/cm3, respectively and the autogenous medium particles could be diffused uniformly and stably along XOY and XOZ cross section and could form autogenous medium fluidized bed with uniform and stable density. When the pulverized coal particle size d = 0.25–0.125 mm, the average bed density reaches the maximum value of 1.815 g/cm3 and the standard deviation of bed density reaches the minimum value of 0.029, at this time, the stability of bed space density reaches the optimum. When the leading density fraction of pulverized coal is 1.8–2.0 g/cm3, the distribution range of bed density is 1.81–1.82 g/cm3 and the fluctuation amplitude is 0.01 g/cm3, at this time, the density of autogenous medium bed is uniform and stable. The interlayer distribution law of low rank lignite in the separation bed was determined. The ash content of upper layer materials is distributed relatively uniform and the distribution range is 9.44–9.76 % with small fluctuation amplitude. The ash content distribution fluctuation of middle layer materials is large and the distribution range is 18.69–31.02 %. The ash content of lower layer materials is distributed relatively uniformly and the distribution range is 41.22–42.06 %. The low rank lignite was separated and upgraded. The ash content of clean coal is 9.58 % and the yield is 63.14 %. The ash content of gangue is 42.09 % and the yield is 36.86 %. The probable error is 0.11 g/cm3. The separated products are relatively pure and the efficient ash reduction and upgrading for low rank lignite are realized.

Superhydrophobic copper foam bed with extended permeation channels for water-in-oil emulsion separation with high efficiency and flux

Developing separation materials with high separation efficiency and permeation flux for water-in-oil emulsions is an urgent demand and still a huge challenge. In this study, through anodization, electrostatic assembly of carbon nanotubes (CNTs), and grafting of nonafluorohexyltriethoxysilane (NFH-silane), a superhydrophobic copper foam containing re-entrant nanostructures was fabricated. The permeation channels were controllably extended by stacking multiple copper foams to form a columnar bed separator, and the residence time of emulsified water droplets was prolonged. When 30 pieces of copper foams were accumulated and the thickness of the stack was extended to 45 mm, the separation efficiency reached 99.14 %, and the permeation flux reached 31,500 Lm−2h−1 for separating surfactant-stabilized water-in-toluene emulsion. Due to the re-entrant nanostructures, the superhydrophobicity of the fabricated copper foam could keep stable in alkali, salt, oil environments, and only slightly decreased in surfactant environment, and the separation efficiency and flux can be recovered to the original level after multiple separation by simple cleaning, showing excellent superwettability stability and separation reusability. All these fascinating performance makes the superhydrophobic copper foam a promising candidate for continuous separating water-in-oil emulsions.

Movement Laws of the Overlying Strata at the Working Face Ends and Their Effects on the Surface Deformation

Underground coal mining causes stress relief and strata/ground movement, threatening the safety of the surface structures. Investigating the movement laws of the strata above the working face ends is important because it determines the deformation level of the surface subsidence trough at the boundary, which is also the zone with the largest deformation degree. This paper presents a study on the movement laws of the overlying strata at the working face ends, and assesses their effects on the surface deformation using field monitoring as well as physical and numerical modelling. The results show that the surface deformation at the subsidence trough boundary is closely related to the movement and rotation of the broken blocks of the primary key stratum (PKS), which control the development of the bed separation and the degree of the surface deformation at the corresponding locations. The numerical modelling results suggest that, the larger the mining height, the greater the rotation angle of the broken blocks and the more severe the surface deformation above the ends of the working face. The results also highlight the role of the thickness of the topsoil. The implications of the results and the limitations of the research are also briefly discussed.

Effects of enhanced hygiene measures on severe diarrhea and anastomotic leak after colorectal cancer surgery: the experience of a tertiary referral hospital in China.

The 2019 novel coronavirus (COVID-19) global pandemic has greatly changed the mode of hospital admissions. This study summarized and analyzed the incidence of severe diarrhea and anastomotic leakage during different periods for colorectal cancer surgery. From January 2017 to September 2020, 2,619 colorectal operations were performed in Peking Union Medical College Hospital. In contrast with previous years, enhanced hand hygiene training, more frequent ventilation of the wards, and separate bed treatments for patients were implemented in 2020. Data on incidence of severe diarrhea and anastomotic leakage were retrieved and collected. The number of cases of severe diarrhea after colorectal surgery was 32 (4.60%), 24 (3.33%), 32 (3.83%), and 11 (2.99%) in 2017, 2018, 2019, and 2020 respectively, while the incidence of anastomotic leakage was 3.30% (23/696), 3.75% (27/720), 2.87% (24/835), and 2.17% (8/368), respectively. There was no significant difference in the incidence of postoperative severe diarrhea or anastomotic leakage across the various years. The number of colorectal surgeries in 2020 was significantly decreased due to the COVID-19 pandemic. Among the different years, no difference was observed regarding the incidence of postoperative flora disorder or anastomosis leakage. Enhanced hygiene measures during the COVID-19 epidemic partially contributed to the decrease of severe diarrhea and anastomotic leakage.

A Case Study on Ground Subsidence and Backfill Deformation Induced by Multi-Stage Filling Mining in a Steeply Inclined Ore Body

The backfill mining method transports treated tailings to the mined-out area, which not only improves the surrounding environment of the mine but also enables the mined-out area to continue mining and production under the support of the filling body. However, with the growth in the depth and scale of mining, ground subsidence, and backfill deformation are becoming increasingly serious problems. As an example, in the Jinchuan mine, a typical multi-stage filling mining mine in China, the deformation law of surface rock mass and backfill are studied through a method combining field monitoring and numerical simulation. The major findings are as follows: (a) A settlement funnel is formed on the ground, and its radius gradually expands with continuous mining and filling. The location of the settlement center moves toward the surface above the footwall of the ore body, and the maximum subsidence reaches 739 mm in 14.5 years. (b) Three-section mining significantly affects the surface deformation, and the single subsidence center on the upper wall develops into the double subsidence center with the mining and filling. When the three-section mining is finished, the maximum value of the surface subsidence reaches about 1.35 m and the mining area is still in a relatively stable state. (c) The whole filling body presents obvious subsidence, with the development of the multi-stage mining and filling. Bed separation phenomena are found between the filling layers, and the closer to the interior, the more obvious it becomes. The backfill’s subsidence characteristics are similar to the surface’s; that is, both the subsidence amount and speed are higher on the hanging wall than on the footwall. (d) The backfill mainly shrinks inward in the horizontal direction, and the deformation is mainly manifested as an internal uplift and an external subsidence in the vertical direction. The mass instability of the backfill is difficult because of the insufficient deformation space, and the influence of large-scale deformation on the mining and overlying strata needs to be considered, as well as the local deformation near the rock contact zone surrounding the backfill. The results provide technical support for filling mining in the Jinchuan mine and provide a reference for other projects with similar engineering conditions.

Development Law of Mining Fracture and Disaster Control Technology under Hard and Thick Magmatic Rock

Hard and thick magmatic rocks are widely distributed in many mining areas in China. Their fracture migration could cause mechanical effects such as the evolution of overburden structure, the sudden change of surface subsidence, and the transformation of accumulated elastic properties, inducing strong dynamic phenomena and even coupled geo dynamic disasters. In this study, by means of theoretical analysis and similar material simulation testing, the fracture of hard thick magmatic rock and the fracture development characteristics of stope are analyzed, and the following research results are obtained: (1) the mechanical model of an elastic foundation beam is established, and it is found that the bending moment in the middle of hard thick magmatic rock is greater than the bending moment at the end, and the magmatic rock first produces fractures in the middle, and then the initial fracture occurs. (2) The existence of hard thick magmatic rock blocks the development of fractures in the longitudinal direction. The bed separation and fracture undergo three processes of generation, development and closure. When the working face advances 160 m, 200 m and 270 m, the maximum bed separation shape on the strike section experiences triangle trapezoid crescent shape. (3) A ladder type fissure channel is formed above the working face side and the open cut hole side. When the working face is advanced 160 m, the ladder type fissure channel develops to the bottom of the hard thick rock layer, providing a ladder type channel for gas flow. After the hard thick rock layer is broken, a large number of elastic properties are released, which produces a strong impact force on the gas rich area of the bed separation, and also causes a sharp rise in the gas pressure of the bed separation at the bottom of the magmatic rock. A large amount of high-pressure gas in the bed separation space flows reversely to the working face along the ladder type gas channel, which can easily induce a gas outburst, coal and gas outburst or other disasters. (4) The correctness of the similar simulation experiment is verified by the field data. Technical measures for preventing gas outbursts in bed separation by surface drilling and pressure relief gas extraction are put forward. The research results have a certain guiding role for the prevention and control of dynamic disasters and the design of roadway support under the condition of a hard and thick key stratum overlying the working face.

A novel collaborative study of abnormal roof water inrush in coal seam mining based on strata separation and wing crack initiation

Separation water inrush poses a potential threat to safe mining on the working face, whose mechanism should be investigated in order to take better prevention and control measures. In this study, aiming at the problem of separation water inrush under hydrostatic pressure, the 21805 working face of the Yushujing coal mine was chosen as the research object to establish an in-house similar simulation experiment. The experiment could reveal the evolution law of bed separation space, the process of water accumulation in bed separation space, and the breaking characteristics of separation water inrush. Meanwhile, in order to theoretically interpret the evolution of water-conducting fractured zone (WCFZ), an analytical model for wing crack initiation from compression-shear fracture and tension-shear fracture that considers T-stress was derived. The analytical model comprehensively considers the effects of overlying strata load and aquifer water pressure, fracture geometry, and rock properties. The results show that the time of separation water inrush obtained by the similar simulation experiment is consistent with the field result, and the orientation of new cracks generated due to water injection also coincides with the analytical solution. In addition, it is found that the development of bed separation space is a long-term process, which can provide a theoretical basis for the prevention and control of separation water inrush.

Seasonal subglacial ponding deposits in a thick till sequence, Dösebacka drumlin, southwest Sweden

Current melting of glaciers has increased interest in understanding glacier hydrology and the interplay between subglacial meltwater, the glacier bed, and ice behavior. However, little is known about the sedimentology of subglacial meltwater deposits, and no sediment type or sequence has been identified as being unique to subglacial settings. Here, we analyze a repetitive, coarsening-upward, sorted-sediment sequence in a thick, diamicton section that we interpret to be seasonal, subglacial meltwater deposits. Over 20 m of diamicton that we interpret to be subglacial traction till is exposed in a rock-cored drumlin at Dösebacka, Sweden, and the till contains multiple interbeds, 25–75 cm thick, of sorted sediment, each consisting of a coarsening-upward sequence of laminated clay, graded laminae of silt, and sand with pebbles. Based on sediment logs, grain-size, thin-section analysis, structural analysis, and field sedimentology, we investigate the genesis of these interbeds and conclude the interbeds to represent subglacial pond deposits. The coarsening-upward sequence represents cessation of till deposition due to hydrostatic bed separation followed by (1) suspension settling of clay in a subglacial blister/pond with drop-grains from an ice roof, (2) suspension settling of pulses of silt and very fine sand in still water coupled with occasional turbidites, (3) traction sedimentation (and loading) of sand and gravel from flowing water, and (4) renewed till deposition following reattachment. The interbeds also reveal deformation that is oriented parallel to the ice-flow direction and which we attribute to deformation during ice-bed reattachment.This sediment sequence parallels in character the seasonal behavior of supraglacial meltwater development on Greenland and moulin drainage, and we argue that the interbeds represent pond deposits during seasonal meltwater drainage. Drainage formed a subglacial blister/pond when the ice reached floatation point, and clay and, later, silt were deposited. With time, drainage became better integrated, and sand and pebbles were deposited by flowing water until reattachment when till deposition resumed.Additionally, based on our interpretation and the attitude of the beds in the drumlin, which parallel the drumlin slope, we argue the drumlin to have been formed by accretion rather than erosion. The anomalous thickness of the till and the numerous interbeds also imply a relatively rapid sedimentation rate, indicating the drumlin formed quickly (10's of years). This stoss-side environment allowed for preservation of the unique interbeds.

The influence of the synergistic effect of airflow and vibration in compound dry separation bed on upgrading of 6–0 mm fine-grained low-grade high-sulfur lignite

Coal is the important support to guarantee the national energy security system. China is the largest coal producer and consumer country and the lignite reserves are abundant. In recent years, as the high-quality coal resources decrease and the difficulty in mining increases, low-grade lignite resource has been the important component of China’s energy production and supply. Promoting the clean and efficient utilization of low-grade lignite is an important approach to realize the goal of carbon peak and carbon neutrality. In this paper, compound dry separation bed was used for the desulfurization and ash reduction of fine-grained low-grade high-sulfur lignite. The synergistic effect of airflow and vibration on particle force characteristics was emphatically investigated and the leading action stage under different airflow and vibration conditions was determined. The spatial migration acceleration variation rule and spatial migration trajectory of particles in different areas under the synergistic effect of airflow and vibration were systematically analyzed. Meanwhile, the spatial distribution characteristics of sulfur content of fine-grained low-grade high-sulfur lignite on the compound dry separation bed and the segregation rule of particles on the different areas along the bed transverse direction were explored, and the spatial distribution layer of the materials on the bed area was determined. The experimental results demonstrate that under condition of Γ = 10.14, when the gas velocity U = 0.125 m/s, vibration plays a leading role in the particle migration on the bed surface; when the gas velocity U = 0.148 m/s, vibration plays a leading role and the airflow plays a surrounding role; when the gas velocity U = 0.229 m/s, the synergistic effect of airflow and vibration dominates in the particle migration. The motion trajectories of particles in each cross section are all oval shape. The variation of acceleration amplitude along OX-axis determines the transverse migration trajectory of particles; the variation of acceleration amplitude along OY-axis determines the peak force characteristics of particles; the variation of acceleration amplitude along OZ-axis determines the stratification law of particles. Meanwhile, it is determined that the top layer of area Ⅰ is the low density particle distribution layer; the top layer of area II is the medium–low density particle distribution layer; all of the top, middle and bottom layer in area III are the high density particle distribution layer. The separation and upgrading for fine-grained low-grade high-sulfur lignite were conducted and the results were as follows. The yield of clean coal is 66.56 % and its sulfur content is 0.97 %; the yield of gangue is 33.44 % and its sulfur content is 22.41 %; the probable error Ep is 0.105 g/cm3, which means that the efficient and clean desulfurization and ash reduction for fine-grained low-grade high-sulfur lignite have been realized.

Research on formation mechanism of the mining-induced horizontal fractures in rock strata separation in the Jurassic coalfield, Huang long, Shaanxi, China

To analyze the mining-induced mechanism of the horizontal fractures due to bed separation in Jurassic coalfield, China, the mineral composition identification test, triaxial compression tests, and overburden response were performed in this study. The mineral composition of rocks is composed of terrigenous sand (cuttings, quartz, and feldspar), terrigenous silt, clay, and a few interstitial materials in adjacent rock strata. The differences of mineral compositions are proved to be the essential factors through triaxial compression tests on rock samples, which found that the strength, Young’s modulus, Poisson’s ratio, and plasticity of adjacent have great differences in rock samples. For predicting the variation of the horizontal fractures, the overburden is supposed to be a thin cube plate. And the range of sizes is corresponding to the scope of the extracted coal seam. Then, based on the elasticity thin plate theory, w(x, y)=C0(1+cos(xπ/a)) (1+cos(yπ/a)) is proposed as the deflection function and the stress and deformation of rock strata are obtained by the variational method and minimum potential energy principle. Hence, a mathematical model suitable is proposed to analyze the variation of the horizontal fractures. The Yuanzigou coal mine is taken as an example, the theoretical results are verified by an exploration borehole video imager. In conclusion, the distribution characteristics of rock strata and the differences in these physical parameters are the essential factors causing horizontal fracture between adjacent rock strata. Besides, the relationship between horizontal fractures and roof water inrush was also discussed in this study.

“Struggle at night – He doesn’t let me sleep sometimes”: a qualitative analysis of sleeping habits and routines of Hispanic toddlers at risk for obesity

BackgroundHispanic children face disproportionately higher risks for early life obesity and resultant comorbidities such as Type 2 diabetes and fatty liver disease. Sleep habits are modifiable behaviors that impact early childhood obesity; Hispanic infants have been shown to have less nighttime sleep compared to their white counterparts. Pediatricians often coach families on parents’ nighttime responsive feeding and longer child sleep duration as protective factors against early life obesity, but must understand the family context and potential barriers. This study aimed to discover the sleeping habits and routines of Hispanic toddlers at risk for obesity through the perspective of their mothers.MethodsThis qualitative study used a phenomenological approach. 14 Hispanic mothers were recruited from a Federally Qualified Health Center in Central Texas for qualitative interviews regarding their experience raising a small child. Children aged 6 to 18 months with child weight-for-length ratio ≥ 85% for age were approached for study involvement and consented during well child visits. Interviews occurred over several months during 2018–2019; NVivo software was used for analysis of qualitative themes. Two reviewers coded and used constant comparative methods to identify common themes.ResultsMothers diverged from AAP recommended guidelines for infant and toddler feeding and sleep habits. Mothers shared their intentions and the real-life barriers to implementing recommended habits. Mothers discussed wanting to have their child sleep in a separate bed or room but not having the resources (i.e., financial, space) to do so. Additionally, mothers discussed knowing not to feed to soothe at night but couldn’t bring themselves to let their child cry if they knew feeding would soothe them. Co-sleeping, feeding to sleep, middle of the night feeding, and lack of structured sleep habits were common interview themes and potentially modifiable factors.ConclusionsPediatricians need to be sensitive to culture and the real-world needs of families to determine if best practices are “practical.” Themes from these parent interviews can inform tailored interventions for children at high risk of obesity. Interventions should promote responsive nighttime feeding and structured sleep, working with individual family logistics, to coach families towards optimal healthy environments and healthy child weight.

Evidence of Seasonal Uplift in the Argentière Glacier (Mont Blanc Area, France)

AbstractThe hydromechanical processes by which basal water controls sliding at the glacier bed are poorly known, despite glacier basal motion being responsible for a large part of ice flux in temperate alpine glaciers. Previous studies suggest that sliding strongly relates to the quantity of water being stored at the ice‐bedrock interface. However, this water storage is difficult to quantify accurately on the basis of surface‐motion observations, given that uplift can also be affected by changes in vertical‐strain rates and sliding velocity change. Here, we use a comprehensive data set of in situ measurements performed over 2 years on the Argentière Glacier in the French Alps to investigate the relationships between horizontal and vertical velocities, basal sliding, subglacial runoff and bed separation. We observe strikingly large uplifts varying spatially between 0.20 and 0.90 m over the winter/spring seasons between January and June and with a consistent spatial pattern from 1 year to another. We show, based on observations and three dimensional ice‐flow modeling, that these large uplifts cannot be explained solely by changes in strain rates or in sliding up an inclined bed. Our results reveal that more than 80% of the observed uplift is related to enhanced bed separation through cavitation, allowing us to estimate the volume occupied by water‐filled subglacial cavities. Our interpretation of uplift being mainly caused by increased cavitation is also consistent with an associated increase in the observed surface horizontal velocity. These findings provide important observational constraints for testing subglacial hydrological models.

Upgrading of low-grade high-sulfur lignite using differential dynamic field dry cascade cleaning apparatus

Coal is an important cornerstone to ensure national energy security under the new situation. China is rich in lignite reserves. In recent years, with the increasing consumption of high-quality coal resources, the development and utilization of low-grade lignite resources has become extremely urgent. Promoting the clean and efficient utilization of low-grade lignite resources is an important way to achieve the goal of carbon emission peak and carbon neutrality. In this paper, the low-grade high-sulfur lignite is desulfurized and ash-reduced by using the differential dynamic field dry cascade separation bed. The temporal and spatial migration and distribution law of material sulfur content in the cascade separation bed are mainly studied, and the dominant period of particle migration is determined. The effects of vibration intensity and airflow velocity on the density uniformity and stability of differential dynamic field cascade separation bed are systematically analyzed. At the same time, the cascade distribution characteristics of low-grade high-sulfur lignite in different transverse areas of the separation bed are explored, and the transverse separation functional area is determined. The experimental results show that when the separation time T = 0–6 s, the particle system is dominated by mixed migration; when T = 0–12 s, the particle system is dominated by mixed-regional layering migration; when T = 0–18 s, the particle system is dominated by stratified migration; when T = 0–24 s, the particle system is dominated by inspective stratification. It is determined that the area of 0–700 mm along the X axis is the transverse separation domain of the materials; the area of 700–1400 mm along the X axis is the transverse transition domain of the materials, and the area of 1400–2000 mm along the X axis is the transverse diffusion domain of the materials. When the operating parameters are in the range of A = 3.1 mm, f = 29 Hz, and v = 0.212–0.314 m/s, the uniformity and stability of the bed density are the best. The low-grade high-sulfur lignite was separated and upgraded by cascade separation bed and the separation result are shown as follows. The sulfur content of clean coal was 0.98%, the ash content was 8.96%; the yield was 67.32%. The sulfur content of gangue was 16.77%, the ash content was 69.59% and the yield was 32.68%. The probable error Ep is 0.1 g/cm3, which means that the high-efficiency desulfurization and ash reduction of low-grade and high-sulfur lignite are realized.

Strengthening catalytic synergy of two function-complementary ZSM-5 by optimizing their spatial organizations in fixed-bed reactor to boost methanol aromatization

The effect of proximity of two different SiO 2 /Al 2 O 3 ratio ZSM-5 catalysts with complementary acidic properties on their catalytic synergy over methanol stepwise aromatization was specifically studied based on a series of different packing modes. The results showed that the powder mixing mode with high proximity excessively enhanced the synergy by intensifying mass transfer between two catalysts. Although it presented a high aromatics selectivity of 57.2%, but the catalyst lifetime was only 10 h due to the intense reverse of polymethylbenzene. The granule mixing mode with larger particle size only slightly improved the catalyst lifetime. Packing two ZSM-5 catalysts in separated dual beds mode could prolong the lifetime to 157 h but the aromatics selectivity was reduced to 21.0%, indicating that low proximity is not favored the catalytic synergy. Interestingly, the suitable proximity of designed alternative sequence beds mode not only intensified intermediates transport to some extent but also relieved the negative influence of aromatic reversion. The moderate synergy remarkably increased the aromatics selectivity to 28.9% with a satisfactory lifetime of 117 h. This work preliminarily elucidates the effect of proximity determined by the spatial organization of double ZSM-5 catalysts on their catalytic synergy for methanol aromatization. Packing Zn/Z-60 and NZ-500 in alternating sequence beds (packing mode) in the tubular fixed bed observably prolonged catalytic lifetime with a satisfied aromatics selectivity. • The effect of proximity on catalytic synergy of double ZSM-5 for MTA was studied. • The catalyst proximity was precisely regulated based on eight packing modes. • Enhanced mass transfer for aromatization was achieved under high proximity. • Catalytic stability was increased by decreasing catalyst proximity. • Mild catalyst proximity over alternate beds enhanced catalytic synergy for MTA.

Ore preparation in deep-sea mining of cobalt-rich ferromanganese crusts

The article covers the specific features of deep-sea mining of ferromanganese nodules (FMN) and cobalt-rich ferromanganese crusts (CMC) found in exploration areas. Experimental studies have been carried out to establish the physical and mechanical properties of CMC samples. These implied sample exposure to a bidirectional axial load from spherical balls (indenters) and compilation of resulting rock strength data sheets for subsequent evaluation. The processes of impact- and cut-induced CMC failure have been experimentally studied with identification of the impact load and axial cutting force required for ore preparation when using the combined mining approach. The existing FMN and CMC recovery facilities have been analyzed and the fundamental design principles have been developed for deep-sea mining with ore preparation. The FMN and CMC mining concept presented and described in the article features a walkingtype mining machine equipped with operating members designed for ore preparation. The article considers various CMC mining solutions using clamshell grabs with a built-in impact tool for ore preparation. A combined mining approach is proposed, with ore preparation implemented in the form of controlled penetration into the CMC bed and subsequent intensification of the impact-induced bed separation process without damaging the substrate. Two layout options have been analyzed for the use of the impact tool and the mining sequence, with the impact tool built along the grab axis or into the jaws of the grab. The latter option is deemed more efficient as it enables penetration management in line with the impact impulses and allows capturing chipped CMC pieces when the jaws are being closed.

Research on Formation Mechanism and Evolution Pattern of Bed Separation Zone during Repeated Mining in Multiple Coal Seams

Mastering the formation mechanism and dynamic evolution pattern of bed separation zone during repeated mining is the key to the success or failure of separation grouting injection technology. Taking a mine in Ningdong as the engineering background, using the research methods of theoretical analysis, numerical simulated, and field measurement, four overburden structure models of single or multiple key strata with repeated mining and single or multiple key strata without repeated mining were constructed. The evolution pattern of bed separation zone was studied from four aspects: bed separation zone development mechanism, formation position, development form, and change of clearance. The results showed that when a single key stratum of repeated mining exists between coal seams, it is difficult to form a large separation area because there is no key stratum during the upper coal mining, and a separation area will be formed below the key stratum when mining the lower coal. When the key stratum exists above all coal seams, a large separation zone will be formed under the key stratum when the upper coal is mined. When mining the lower coal, when the coal seam spacing is less than 4 times of the mining height of the lower coal, the crack will penetrate the upper coal floor. If the key stratum is not completely broken, secondary separation may occur. When multiple key strata are all located above all coal seams, there will be bed separation zone under the high-level key stratum. When multiple key strata and coal seams are distributed at intervals, the separation below the high-level key stratum during upper coal mining and the separation below the low-level key stratum during lower coal mining are formed. Because the high-level key stratum bends and sinks after being affected by the mining of coal 1, the clearance of bed separation during mining coal 2 is slightly less than that during mining coal 1, which is contrary to the pattern that the greater the bed separation clearance increases with the increase of mining height.