Abstract: With the implementation of carbon peak and carbon neutrality vision, an amine collector has been extensively applied in reverse flotation of bauxite, iron, and phosphate ores for desiliconization. Previous research indicates that the molecular structure of flotation reagents has a significant influence on their collecting performance and flotation selectivity. Regarding the substituent effect of organics, a method wherein a suitable substituent is inserted into existing reagents has been used to develop new high-performance flotation reagents. To clarify the effect of methyl on collection ability and flotation selectivity of cationic collectors, flotation separation of quartz and hematite has been conducted. C12 alkyl cationic surfactants such as dodecyl amine, dodecyl methylamine, N,N—dimethyl dodecyl amine, and dodecyl trimethyl ammonium chloride were selected as collectors. The active mechanism of methyl on the flotation performance of cationic collectors was also determined by calculating the electrostatic potential of the collectors and the van der Waals volume of its polar group. The collection abilities of cationic collectors were investigated by single mineral flotation. The results indicate that flotation recoveries of quartz and hematite are decreased with the insertion of a methyl group into central atom of a cationic collector. Further, the effect of methyl on selectivity of cationic collectors was investigated by flotation separation of artificially mixed quartz and hematite. The results revealed that the separation efficiency of artificially mixed quartz/hematite is increased gradually due to the drastic reduction in hematite flotation recovery rate. A methyl group is an electron donating group. The calculation and diagramming of electrostatic potential for selected collectors reveal that the charge distribution density of the cationic collector is varied by the introduction of an electron donating group. Consequently, the charge number of central atom is increased, thereby weakening the positive electrostatic potential of the atom and making the electrostatic adsorption strength between collector and mineral surface lower. Therefore, the flotation recovery rate decreased. Meanwhile, the size of a polar group for cationic collectors is enlarged by introducing the methyl group, thus increasing the steric hindrance of reagents and mineral surface interaction and resulting in an increase in flotation selectivity. With an increase in the methyl group number, the flotation separation efficiency of artificially mixed quartz and hematite becomes increasingly high. In the future, obtaining and quantifying correlation parameters of substituents and then explicating the relationship between substituent parameters and flotation performance of cationic collectors would be beneficial to establish a new design method for cationic collectors.
Abstract: To address the problems of byproduct treatment and pollution in thionocarbamate preparation, four novel processes for preparing O-isopropyl-N-ethyl thionocarbamate (IPETC) were designed, which can coproduce 4-(tert-butyl)benzyl mercaptan (BBSH), sodium benzyl trithiocarbonate (BTTC), sodium O-benzylthioethyl xanthate (SBEX), and benzyl disulfide, respectively. All the products were confirmed via FTIR and mass spectrometry. The composite collector (IPETC and BBSH mass contents were 51% and 41%, respectively) was synthesized via one-pot reaction of sodium isopropyl xanthate, 4-tert-butylbenzylchloride, and ethylamine using tert-butyl alcohol as solvent. The yield of IPETC and BBSH was 95% in the process of coproducing IPETC and BBSH. Specifically, BTTC and IPETC were synthesized via a reaction of sodium isopropyl xanthate, benzyl chloride, ethylamine, carbon disulfide, and sodium hydroxide. The IPETC and BTTC yields were 94% and 95% with a purity of 91% and 82% in the process of coproducing IPETC and BTTC, respectively. Meanwhile, SBEX and IPETC were synthesized via reaction of sodium isopropyl xanthate, 2-chloroethanol, ethylamine, benzyl chloride, carbon disulfide, and sodium hydroxide. The IPETC and SBEX yields were 89% and 93% with a purity of 95% and 91% in the process of coproducing IPETC and SBEX, respectively. Benzyl disulfide and IPETC were synthesized via a reaction of sodium isopropyl xanthate, benzyl chloride, ethylamine, and hydrogen peroxide. The IPETC and benzyl disulfide yields were 93% and 95% with a purity of 92% and 94% in the processof coproducing IPETC and benzyl disulfide, respectively. The flotation response of copper-molybdenum ore independent with IPETC and BBSH collectors and with their mixture was assessed. The flotation results indicate that the composite collector displays a superior collecting capability for copper sulfide ore. Further, the combination of IPETC and BBSH could give rise to a synergistic effect, significantly enhancing the overall flotation performance. The flotation performance of SBEX and BTTC on chalcopyrite and pyrite was also investigated. The flotation results indicate that SBEX and BTTC exhibited better collecting performance than sodium isobutyl xanthate (SIBX), which can replace SIBX for the flotation separation of copper sulfide. FTIR spectra and X-ray photoelectron spectroscopy analyses were conducted. The results indicate that when all three sulfur atoms in BTTC bond to the mineral surface, the hydrophobicity increases when compared to xanthates, wherein oxygen does not bond to the surface. Further, the thioether structure can increase the hydrophobicity of SBEX on the chalcopyrite surface, and SBEX features a higher collecting recovery toward chalcopyrite than SIBX. The results indicate that BTTC and SBEX might bond with copper atoms on the chalcopyrite surface through their sulfur atoms to form BTTC-Cu and SBEX-Cu surface complexes.
Abstract: O—butyl—N—isobutyl thionocarbamate (NBIB) is a novel collector for copper sulfur flotation separation. The adsorption capacity of NBIB was measured using a UV–vis spectrophotometer. The effects of the adsorption temperature, pH value, stirring time, and collector concentration on the adsorption capacity of NBIB on chalcopyrite surfaces, as well as its adsorption thermodynamics and kinetics, were investigated. Results of a pure mineral flotation experiment indicate that NBIB has a high recovery rate for chalcopyrite, strong collection capacity, and little influence by pH. The adsorption capacity of NBIB on a chalcopyrite surface increases with an increase in the collector concentration at 288, 298, and 308 K and pH 6, 9, and 12, respectively. When the equilibrium concentration reaches 0.5×10?4 mol?L?1, the adsorption capacity has a small increase range. At the same pH value, the adsorption capacity increases with an increase in the adsorption temperature. It is speculated that NBIB adsorption on a chalcopyrite surface is an endothermic process. At pH 6 and 9, little difference exists in adsorption capacity, which slightly decreases when pH increases to 12. Meanwhile, the pulp pH value has little effect on the adsorption capacity, which is consistent with the flotation test results. The adsorption capacity data were linearly fitted by Langmuir and Freundlich isotherms, and the Langmuir equation has a better correlation coefficient of the fitting curve. The adsorption process of NBIB on the chalcopyrite surface is more consistent with the Langmuir adsorption model, and it is speculated that the adsorption process may be monolayer adsorption. The parameters of the Langmuir equation are considered based on a thermodynamic formula. The results indicate that the linear fitting results are good, ?G is negative, and ?H and ?S are positive. Therefore, the process of chalcopyrite adsorbing NBIB may be spontaneous, entropy-driven, and endothermic chemical adsorption. Meanwhile, the adsorption capacity of NBIB on the chalcopyrite surface increases with an increase in the adsorption time at temperatures from 288 K to 308 K. The increasing trend of adsorption capacity slows down after the adsorption time reaches 20 min. Moreover, the adsorption capacity increases with increasing temperature. Evidently, the adsorption is an endothermic process, which is consistent with the results of the thermodynamic analysis. The kinetic calculation shows that the correlation coefficients of the second-order reaction fitting curve are greater than those of first-order reaction, indicating that the second-order reaction rate equation has a better linear fitting result. The equilibrium adsorption capacity calculated by the second-order reaction rate equation is closer to the experimental equilibrium adsorption capacity. Therefore, it is speculated that the NBIB adsorption on the chalcopyrite surface conforms to the second-order adsorption kinetic model.
Abstract: Owing to the global consumption of high-grade ores, large amounts of low-grade and complex ores are being processed nowadays. The entrainment of gangue minerals in the ores, especially silicate gangue minerals, has become a nonignorable issue that can significantly influence mineral flotation performance. Amorphous silica has been reported to exist widely in various ore deposits, but how it affects mineral flotation remains poorly understood. This study investigated the rheological properties and entrainment behaviors of quartz/amorphous silica gangue in copper flotation through batch flotation tests, rheology measurements, cryo-SEM analysis, and particle settlement tests. Results indicate an exponential increase in the pulp viscosity as the amorphous silica content in the gangue increased. These also led to distinct recoveries of chalcopyrite and gangue minerals in flotation: the chalcopyrite recovery kept decreasing, whereas the entrainment recovery of gangue minerals increased initially and then decreased. The change in the entrained gangue recovery was found to be a consequence of the reduced water recovery and the increased degree of entrainment for the gangue. In a range wherein the viscosity growth was low, the increased degree of entrainment for the gangue prevailed over the decreased water recovery, ultimately leading to an increase in the gangue recovery. However, when the pulp viscosity drastically increased, the decreased water recovery was found to be dominant in changing the gangue recovery, and thus the gangue recovery decreased. Further, the effect of amorphous silica on the degree of entrainment for the gangue was investigated on a size-by-size basis. A great difference was found in the degree of entrainment for the gangue mineral particles of the same size fraction. However, fine gangue mineral particles experienced the greatest increase in their entrainment degree. Therefore, the degree of entrainment for the gangue was size-dependent and subject to the presence of amorphous silica. The results of cryo-SEM and settling tests indicate that quartz/amorphous silica particle aggregates were formed when amorphous silica particles were present in the flotation system, and these aggregates had a relatively low sedimentation rate. It was inferred that formed gangue aggregates increased the pulp viscosity, which reduced the water drainage in the froth and the sedimentation rate of gangue particles, subsequently increasing the mass of the gangue in a unit mass of water and, thus, the degree of entrainment.
Abstract: Mineral resources are essential to human life and social development and play an important role in national security and economic development. China has huge reserves of metal mineral resources, but the per capita possession is low. Especially, it is difficult for iron, copper, aluminum, and other metal mineral resources to be self-sufficient and heavily dependent on foreign countries. Because of the massive exploitation of metal mineral resources, shallow resources are becoming exhausted, and deep mining will become the main force for the supply of metal mineral resources in the future. “Going deep into the earth” corresponds to the current state of national resource strategy development. It is found that there is still a certain gap between China’s deep metal mining technology and mining depth compared with internationally developed mining countries. The mining depth of foreign mining countries is mostly over 3000 m, with three South African mines having a mining depth of over 4000 m, whereas the mining depth of Chinese mines is mostly below 2000 m, and most of the metal mines have not yet broken through the kilometer depth. Furthermore, the level of mining technology in established mining countries abroad is high, and the degree of mechanization and intelligence is high. Deep mining technology in China is insufficient to meet the need for deep mining. China still has a large gap compared with internationally developed countries; therefore, the related rock mass mechanics theory and mining technology are no longer suitable for deep metal mining. In this paper, we summarize the research status of four major theories and technologies for deep mining of metal mines, namely, deep rock mechanics, deep well building and lifting, green mining, and intelligent mining, and proposes future research emphases. Finally, based on the research status and existing problems of the key technologies and theories of deep metal mining at present, the paper puts forward three strategic ideas: deep-part construction of a super-large intelligent autonomous mine, in-situ fluidized mining, and rock mechanics. With the continuous increase of mining depth, it is urgent to study the related theory and technology of deep mining of metal mines so as to ensure the safe, efficient, economical, and environmentally friendly mining of deep metal mineral resources and ensure the resource security of our country.
Abstract: In this work, the early hydration reaction and mechanical evolution characteristics of graded fine tailing cemented backfill are studied. The hydration exothermicity and electrical resistance characteristics of backfill slurry with different lime sand ratios are tested, and the microscopic morphology characteristics of early hydration products are analyzed according to scanning electron microscopy (SEM). Finally, on the basis of uniaxial compression mechanical test results, the early hydration reaction process and the effect of the products on the strength evolution of the backfill are analyzed. The results showed that the exothermic process of slurry hydration underwent rapid reaction stage I, induction stage II, acceleration stage III, deceleration stage IV, and stabilization stage V. The volume resistivity underwent increasing stage I, decreasing stage II, and accelerated increasing stages III. The slurry lime sand ratio affects the hydration heat release and volume resistivity. The larger ratio is, the greater the hydration heat release rate and heat release, the more hydration products are generated, and the greater the volume resistivity. An increase in the lime sand ratio prolongs the induction time of the hydration reaction and increases the rate of the hydration reaction during the induction period. At the same time, it retards the growth of volume resistivity. The larger the lime sand ratio is, the stronger the retarding effect and the larger the retarding effect on the growth of slurry volume resistivity. The rate of the hydration reaction directly determines the formation speed of the backfill strength. When the main components of the filling material, C3S and C3A, are dissolved rapidly in water, much heat is released. The generated Ca(OH)2 reduces the volume resistivity of the slurry and accelerates the growth of the backfill strength; the AFt generated subsequently compacts the pores between particles, blocks the dissolution of ions, decreases the rate of heat release, and prevents the growth of backfill strength. The backfill strength increases rapidly from 0–3 d and slowly from 3–7 d. When the hydration reaction is basically completed after 14 d, the filling material is solidified overall, and its strength is basically stable. The change in backfill strength first increases and then gradually decreases until stabilizing. These research conclusions provide theoretical support and scientific guidance for mining to adopt graded fine tailings to fill the underground goaf and control the temperature of the deep stope.
Abstract: The key to obtaining high-strength backfill is the cementing material used for backfilling. Therefore, to prepare a new slag-based binder for cemented tailings backfill, hydrated lime, desulfurized gypsum, sodium sulfate, and sodium hydroxide were selected as slag activators. Firstly, the D-optimal mixture design method was used to develop the strength regression model, analyze the influence of hydrated lime, desulfurized gypsum, sodium sulfate, and sodium hydroxide on the strength, and determine the best ratio of slag activator. Secondly, after optimizing the slag content, the optimum proportion of the binder was obtained. Lastly, X-ray diffraction and scanning electron microscopy were used to study the internal mechanism of the hydration products of the slag-based binder, the microstructure of backfill, and strength formation. The results show that the D-optimal mixture design method is a good method of obtaining the formula of the mixture with a less experimental amount. The sensitivity order to slag is sodium hydroxide > hydrated lime > desulfurized gypsum > sodium sulfate, and there are different degrees of interaction, so the weighing accuracy should be considered when batching. At the optimum mass ratio of binder (slag 85.00%, slaked lime 8.03%, sodium sulfate 3.96%, desulfurized gypsum 1.85%, and sodium hydroxide 1.16%), the early strength (1–3 d) is 3.5 times higher than that of cement, and the late strength (7–28 d) is at least two times higher than that of cement. The increased strength of hardened backfill cemented is closely related to ettringite (AFt) and C–S–H, the two primary hydration products of the new slag-based binder. During the early stages of hydration, a large amount of AFt rapidly nucleated on the surface of the slag, the distance between the tailing particles provided plenty of space for ettringite growth, and its long prismatic structure continuously extended into the intergranular pores. The rapid formation of early strength of backfill is primarily because of the physical filling effect of ettringite. In the later stage, the strength of the backfill is primarily attributed to the wrapping and bonding effect of C–S–H, which further optimizes the compact structure of the backfill. The high-strength backfill can be obtained using the new slag-based cementitious material, which is of great significance for safe and efficient mining. The slag-based binder that contains 86.94% (mass fraction) of industrial solid waste helps solve the problem of desulfurized gypsum of coal-fired power plants and mine tailings. Additionally, the D-optimal mixture design proved to be an effective method for designing and optimizing the ratio of multicomponent materials, such as binders and activator components.
Abstract: The backfill mining method is widely used in mines because of its advantages of environmental protection, safety, and efficiency and includes filling slurry pipeline transportation as an important part. The rheological parameters of filling slurry are important indicators for evaluating the characteristics of filling slurry pipeline transport; these parameters are mainly determined by rheometers at present, while the rheological experimental conditions are usually unavailable at the mine site. Because of its simplicity and speed, mines mainly use a slump test to evaluate the flow properties of a filling slurry. In this paper, we used a mini-slump cone to conduct a slump experiment of filling slurry with different mass fractions and cement–tailings ratios (the two most common variable parameters in filling slurry ratios), established an analytical model between the spread of a mini-slump cone and yield stress, obtained a simplified calculation model according to the shape of the filling slurry after flowing, calculated the yield stress of the slurry based on the simplified model, and compared the theoretical value with the experimental value of the yield stress of the filling slurry under the condition of the same ratio tested by a rheometer. At the same time, the influence law of different mass fractions and cement–sand ratios on the expansion degree of the filling slurry was studied using a two-factor analysis of variance. The results show that the spread is mainly influenced by the mass fraction and unsubstantially affected by the cement–sand ratio. The yield stress of the filling slurry increases with the mass fraction. When the mass fraction is low, the error in the theoretical value relative to the experimental value has a large range, and the error in the theoretical value is within 25%, averaging 16.79%; as the mass fraction increases, this error gradually decreases below 15%, averaging 8.81%. Considering its effect, a correction factor based on the mass fraction was proposed, and the error in the theoretical yield stress value after the correction was reduced below 10%, averaging 3.54%. In this study, the mini-slump cone test not only reduces the experimental material and labor intensity compared with the traditional slump test but also effectively characterizes the yield stress of the slurry, which provides practical guidance for evaluating the flowability of mine filling slurry.
Abstract: With its continuous application and promotion, filling technology, such as an ultra-long distance and special pipeline arrangement, faces an increasing demand, and the demand for the fluidity of filling material is also rising. Aiming at the large risk of blocking pipes and tubes in filling technology, the serious wear of pipelines, etc., and using modified magnesium slag (MMS) and fly ash (FA) to prepare high liquidity under different ratios of a new type of paste filling material (UH-MFPB), this paper probes this material’s early strength, liquidity, and rheological properties, and establishes the relationship between liquidity and rheological parameters. First, MMS and FA samples were prepared at different ratios of certain concentrations and cured for 3, 7, 28, and 56 days to measure their uniaxial compressive strength. The uniaxial compressive strength of a UH-MFPB sample increases first and then decreases with increasing FA content, and gradually increases with curing age. When FA content is 20%, the compressive strength of the sample reaches the maximum. At 3, 7, 28, and 56 days, the intensity was 1.335, 2.161, 6.759, and 12.104 MPa, respectively. Then, the slump and spread of fresh UH-MFPB slurry were measured. They increased with FA content, with a slump of 25.6–29.2 cm and a spread of 61–93.1 cm, showing good fluidity. Then, the rheological properties of fresh UH-MFPB slurry were measured in accordance with the Herschel–Bulkley model, and the relationship between shear stress and plastic viscosity and the shear rate was discussed, as well as the effect of FA content on rheological parameters and mechanisms. The shear stress is found to increase with the shear rate, and the viscosity decreases exponentially and then slowly with increasing shear rate. Rheological parameters (yield stress, plastic viscosity, and thixotropy) decrease with increasing FA content, and the slurry undergoes shear thickening when FA content reaches 20%. The Cross viscosity model was used to fit the viscosity curve of fresh slurry. Finally, the correlation between the fluidity and rheological parameters of fresh UH-MFPB slurry was discussed, and the yield stress was found to correlate negatively with the slump, plastic viscosity, and expansion, which were quadratic polynomials. Considering all factors, when FA content is between 10% and 30%, UH-MFPB slurry has ultra-high fluidity and high strength, which can play a good role in filling slurry transport.
Abstract: With the development of energy extraction to offshore, deep sea, and polar fields, the service environment is becoming increasingly harsh. Hence, developing cryogenic steel with high strength, high toughness at low temperatures, and excellent welding properties has become an urgent requirement for economic development. With equipment and technology innovation, although the FH40-grade cryogenic steel base metal can be developed by grain refinement, the low-temperature impact toughness of its welded joints might be drastically reduced. Thus, the application of FH40-grade cryogenic steel has been severely restricted. To examine the evolution of the microstructure of welded joints of FH40-grade cryogenic steel and its effect on low-temperature impact toughness, the macrostructure, microstructure morphology, and composition at the welded joints were analyzed using a metallographic optical microscope and through scanning electron microscopy, electron backscatter diffraction (EBSD), and energy dispersive spectroscopy (EDS) analysis, respectively. The results indicate that the FH40 cryogenic steel base metal has excellent comprehensive mechanical properties with a yield strength of 420 MPa, tensile strength of 518 MPa, and Charpy impact energy of 162 J at ?60 ℃, while the low-temperature toughness of the joint fusion line and the heat-affected zone was drastically reduced to 16 J. Results of a microstructure analysis indicate that the base metal of cryogenic steel was a fine polygonal ferrite and pearlite structure and pearlite bands occurred at the core position. The microstructure of the heat-affected zone of welding was mainly acicular ferrite, but evident martensitic bands were observed in the core. The results of the Vickers hardness test revealed that the hardness of 229.7 HV0.05 for acicular ferrite and 313.7 HV0.05 for martensite, which were approximately 40 HV0.05 and 140 HV0.05 higher than the original polygonal ferrite, respectively. An EBSD analysis indicates that the kernel average misorientation of the martensitic band was high with high internal stresses, which was the main cause of the sharp decrease in the low-temperature toughness of the welded joint. The presence of severe bias of carbon and manganese elements was confirmed through the EDS analysis of the banding in the heat-affected zone. In the rolling process, many continuous pearlite-banded structures were formed due to the severe central segregation of the base metal. In the welding process, the local hardenability increases due to the high local composition, and the martensite of hard and brittle phases was formed in the rapid cooling process, causing the increase in the local stress and hardness. Thus, the mismatch between soft and hard phases and organization led to a sharp decrease in the low-temperature toughness of the welded joint.
Abstract: Not only is scrap steel an indispensable ferritic raw material for the modern steel industry, but it is also the only green raw material that can replace iron ore in large quantities. The quality of the scrap steel directly affects the quality of molten steel, which makes it necessary to sort and grade scrap steel before it enters the furnace. Most iron and steel enterprises determine the grade of scrap steel mainly by visual inspection and caliper-based measurements by quality management personnel. As a result, this process is prone to human errors and low efficiency. Therefore, given that the major challenges of scrap inspection include the many categories of scrap, complex actual detection scenarios, and challenges in manual system connection, a deep learning network model CSSNet was proposed for scrap classification and rating based on the Squeeze-Excitation (SE) attention mechanism, and images of the scrap unloading process were collected for model training and validation. First, a 1∶3 physical model of scrap steel quality inspection was built to simulate this process. High-resolution visual sensors were used to collect images of diverse types of scrap steel in the scene of trucks unloading scrap steel. Then, a cross-stage local network was used to extract the features of the collected scrap images, the spatial pyramid structure was used to solve the problem of feature loss, and the attention mechanism was used to focus on the correlation between channels and retain the channel with the most feature information. Finally, model training and validation were done using two datasets containing seven labels for classification. In the model prediction stage, the constructed scrap steel quality inspection model CSSNet was used to judge the scrap steel category and quality to verify the accuracy and detection efficiency of the model. Based on the self-made scrap steel validation dataset, its performance was compared with mainstream single-stage object detection packages such as YOLOv4, YOLOv5s, and the two-stage object detection model Faster R-CNN. The model was found to be able to effectively rate different grades of scrap steel, with the classification accuracy rate of all categories has reached 83.7% and an mAP value of 88.8%. The performance of the CSSNet model is better than the other three target detection models. CSSNet can not only fully meet the needs of the actual production applications in terms of accuracy, real-time performance, and identification and rating efficiency but also surpass the traditional manual scrap quality inspection method, address multiple issues in the evaluation of scrap steel quality, and realize automated scrap steel quality testing.
Abstract: High-salt, organic waste liquids are characterized as having high COD value, complex composition, strong acidity or alkalinity, high salinity, and poor biodegradability, resulting in them contributing to environmental pollution. High-temperature incineration technology to treat high-concentration organic waste liquid has obvious advantages of thorough treatment, reduced effluents, and near-universal applicability to the many types of complex organic substances. Additionally, it is an effective way to dispose of high-salt, liquid chemical waste. Due to the complex composition and the high salt content of high-salt organic liquid waste, the high-temperature slag causes serious erosion to the refractory material of the incinerator during use. Damaged incinerator refractory linings are significant safety hazards and can cause major economic losses. It is crucial to study and understand the corrosion resistance of refractory materials very well. This paper introduces the main types of refractory materials suitable for high-salt organic waste liquid incinerators, the main types of incinerators and their applications, and finally, describes the mechanism of erosion of the refractory materials in detail. Based on the characteristics of the incineration process of phenol and acetone coproduction organic liquid waste, a method was proposed for the in situ anticorrosion treatment of high-salt organic liquid waste using traditional corundum–mullite refractory materials. The slag enters the refractory material through pores on the interface and reacts strongly with the refractory material surface at 1000–1300 ℃ to produce a low-melting, liquid phase product. The thermal stress of the product is different from that of the original refractory material. If it falls off and is damaged, the service life of the refractory material is extremely short, and the replacement cycle is only 3 months. The addition of Cr2O3 powder to the waste liquid is eventually deposited at the interface of the refractory material after the liquid waste is incinerated and forms an antierosion, refractory, solid solution layer. The corrosion-resistant layer on the surface of the refractory brick rarely reacts with the molten slag to form a low melting point phase. The protective layer can effectively slow down the penetration and erosion of the refractory materials by the slag. The preliminary test run results show that adding 5% Cr2O3 to the liquid waste can prolong the service life of corundum–mullite refractory bricks to several days. This study demonstrated that the in situ strengthening method to improve the corrosion resistance of conventional refractory materials is economical and efficient and shows good prospects of popularization and application.
Abstract: In China, more and more buildings use assembled frame structures such as prefabricated autoclaved lightweight concrete wall panels used as the exterior wall. In structural design, these wall panels are usually considered non-structural components. However, in the event of an earthquake, the damage and collapse of these wall panels are likely to lead to casualties and economic losses. In addition to the damaged wall panels, the connection between the wall panels and the main structure is also an important factor affecting the seismic performance of the structure. The traditional connection between the wall panels and the frame can be easily damaged in an earthquake. The seismic performance of frame structures based on the new connections and the integrity of the lightweight, concrete-filled wall panels needs to be explored. To investigate the synergistic seismic performance of the wall panels and the steel frame structures, low cycle reciprocating load tests were carried out on the steel frames infilled with the lightweight concrete assembled wall panels. A new sliding joint was developed to connect the wall panels and the steel frames, and its performance was compared with the traditional hooking joints. The effect of lightweight concrete wall panels and their integrity on the seismic performance of the structures was investigated by analyzing the load-bearing capacity, hysteresis performance, stiffness, energy dissipation, and ductility of the specimens. The results show that extrusion cracking of the wall panel and buckling at the end of the frame columns are the ultimate damage modes of the filled wall panel steel frame structures. The synergy of the wall panels and the steel frame improves the load-bearing and deformation capacity of the structure as compared to a hollow frame. The structure with sliding joints is better in terms of load-bearing capacity, stiffness, and energy dissipation capacity. Enclosed by CFRP cloth, the enhanced integral wall panels can improve the ductility, stiffness, deformability, and energy dissipation capacity of the structure. It is suggested that the improved seismic performance of frame structures by the infilled wall panels should be considered in the design of prefabricated frame structures and that the wall panels and the frames should be connected by sliding joints. These experimental results can provide a reference for the seismic design of steel frame structures filled with lightweight concrete assembled wall panels.
Abstract: Based on a summary of the characteristics of the industrial Internet, combined with the overall status of the existing industrial Internet, this paper analyzes the problems of the traditional industrial automation closed five-tier architecture and concludes that the current industrial Internet remains in a stage of technological development and maturation, which restricts the promotion and standardization of China’s intelligent manufacturing level to some extent. In the future, the industrial Internet will break the original data hierarchy structure, break the data barrier, and realize the development of intelligent manufacturing toward intelligent, flattening, lightweight, and green. First, this paper proposes a new industrial network collaboration architecture on the cloud side that supports efficient data flow. The proposed architecture is a flat, platform-based structure that realizes cloud-side collaboration and the integration of control, computing power, and network. Second, on the basis of the overall architecture of the industrial network, two key technologies are proposed to adapt the new industrial network infrastructure. One is 5G–time-sensitive networking (TSN) collaborative transmission technology. TSN realizes the interconnection and integration of heterogeneous networks in the industrial field based on the data link layer, and 5G–TSN collaborative transmission has become an important evolution trend of the intelligent factory network. Three key technical contents are introduced: 5G–TSN heterogeneous network convergence architecture, network clock adaptation mechanism, and software defined network (SDN)-based integration management and resource scheduling. The other key technology is cloud PLC technology based on a deterministic network, and the virtualization and cloud control system is the basis for breaking the original closed industrial control system. On the one hand, cloud-based hardware resources can be used to achieve one-to-many control, saving a large amount of industrial control equipment deployment investment costs. More importantly, the centralized control system can achieve unified control and optimization of global resources. This paper introduces the virtualization 5G cloud chemical industry control technology with two parts: technical content and technical route. Third, this paper proposes a cloud-based allocation of control resources and a cloud–network integration collaboration scenario and designs the 5G cloud-based programmable logic controller (PLC) and EtherCAT fusion system and the EtherCAT and TSN fusion system for real-time motion control. Through the testing of the end-to-end delay and cross-network time synchronization accuracy of the actual system, the current end-to-end delay of network transmission is less than 5 ms, the cross-network time synchronization error is between 100–400 us, and the accuracy is less than 100 ns These performance indicators reach the current industry-leading level. The test platform verifies the scientificalness and rationality of the new industrial network architecture. Finally, the integration problems and potential solutions of efficiency, reliability, and security are discussed in the future industrial automation system integrating network, control, and computing.
Abstract: Pipeline transportation is the most economical means of transporting oil, natural gas, and other energy sources over a long distance. With the increasingly harsh service environment of pipeline transportation, the requirements of pipeline steel in terms of strength, hydrogen-induced fracture resistance, and corrosion resistance have increased. In areas such as plateaus or deep seas, excellent low-temperature toughness is important to ensure the safe transportation of pipeline steel. Drop weight tear testing is one of the most effective methods for measuring the low-temperature toughness of pipeline steel. The test involves large specimens with full wall thickness. Through the characterization of the ductile–brittle shear area and ligament width of the sample, the toughness and tear resistance of pipeline steel can be better reflected. However, the drop weight tear test is difficult, time-consuming, and laborious, and it consumes a large amount of experimental resources. In this work, a machine learning-based model for predicting the drop weight tear test-derived shear area was established according to production line datasets provided by steel mills and pipeline steel datasets collected from the literature. Different machine learning algorithms were tested using the two datasets. The best models were random forest models. Strategy I included only production line datasets, and the Pearson correlation coefficient (PCC), which is the performance index, predicted by the machine learning model was 0.64. Strategy II involved literature data and production line data, and the PCC predicted by the machine learning model was 0.92. The consideration of literature data effectively improved the prediction accuracy of the drop weight tear test shear area. Moreover, in strategy II, to avoid the overfitting of the machine learning model, a feature screening technique was adopted. Finally, a genetic programming-based symbolic regression approach was developed to establish a formula describing the relationship between the selected features and the target shear area data. The PCC of the precision of this formula was 0.83, which indicates that the formula can be used to estimate the drop weight tear test-derived parameters of pipeline steel. The machine learning technology provides a new method for optimizing and predicting the drop weight tear test-derived shear area of pipeline steel. Moreover, the combination of production line data and literature data remarkably improved the accuracy of the machine learning model, which also allows for the prediction of other material production line data via machine learning techniques.
Abstract: With the rapid arrival of the Internet of Everything era, massive data resources are generated on edge sides, causing problems such as large network load, high energy consumption, and privacy security in traditional distributed training based on cloud computing. Edge computing sinks computing power resources to the edge side, forming a collaborative computing system that integrates “cloud, edge, and end,” which can meet the basic needs of real-time operations, intelligence, security, and privacy protection. With the help of edge computing capabilities, edge intelligence effectively promotes the intelligent development of the edge side, which has become a popular topic. Through our research, we found that edge collaborative intelligence is currently in a stage of rapid development. At this stage, several deep learning models are combined with edge computing, and many edge collaborative intelligent processing solutions have exploded, such as distributed training in edge computing scenarios, federated learning, and distributed collaborative reasoning based on technologies such as model cutting and early exit. The combination of a shallow breadth learning system and virtualization technology allows for quick implementation of edge intelligence, which considerably improves service quality and user experience and makes services more intelligent. As a key link of edge intelligence, edge intelligence collaborative training aims to assist or implement the distributed training of machine learning models on the edge side. However, in an edge computing scenario, the distributed training of the model must coordinate several edge nodes, and many challenges remain. Therefore, by fully investigating the existing research foundation of edge intelligent collaborative training, we focus on the challenges and solutions of edge intelligent collaborative training in edge scenarios such as equipment heterogeneity, limited equipment resources, and unstable network environments. This paper introduces and summarizes the overall architecture and core modules of edge intelligent collaborative training. The overall architecture mainly focuses on the interaction framework between edge devices. In terms of whether there is a central server role, it can be divided into two categories: parameter server centralized architecture and fully decentralized parallel architecture. The core module of edge intelligent collaborative training mainly focuses on the problem of collaborative training of a large number of edge devices for neural network models to update parameters. In terms of the role of parallel computing in model training, it is divided into data parallelism and model parallelism. Finally, the many challenges and prospects of edge collaborative training are analyzed and summarized.
Abstract: The high-precision positioning technology of a rail-type patrol robot is an important research direction in the area of intelligent patrol inspection of belt conveyors. An excessively long mining belt conveyor and a complex working environment severely affect the positioning accuracy of patrol robots. This study aims to address the problems of poor adaptability to tracks and limited positioning accuracy of the positioning technology of rail-type patrol robots in the field of mining belt conveyor patrol inspection. Therefore, a high-precision positioning method based on a modified fusion of encoder and near field communication, abbreviated NFC, double sensors is proposed. This work analyzes the influence of track and track environment characteristics of the belt conveyor track patrol robot on the encoder coefficient. It also proposes a track segmentation principle based on the same characteristics of a track surface, providing a basis for the subsequent correction and fusion algorithm. A recursive positioning method of the absolute value encoder is constructed based on the data feedback characteristics carried by the robot. Through the historical positioning sensor data of robot operation, the encoder coefficients are modified according to sections and directions. Further, the encoder coefficient correction method based on recursive least squares is proposed to improve the adaptability of the encoder to the track. Hence, corresponding positioning methods are constructed according to the different positions of the robot’s track segments. At the end of the segment, the fusion positioning of the encoder and NFC data are realized based on the Kalman filtering algorithm to reduce the cumulative error of the encoder. In the segment, to improve the positioning accuracy of the encoder, the subsection and direction correction coefficient and real-time data of the encoder are used for recursive positioning. Therefore, combined with the positioning of each section of the track, the continuous high-precision positioning of the track-type patrol robot on the entire track can be realized. Moreover, an experimental platform is built for the proposed method to conduct physical testing. The modified fusion positioning method is compared with encoder positioning, RFID positioning, and fusion positioning based on encoder and NFC. The results of the correction experiment indicate that the modified fusion localization algorithm based on the encoder and NFC can effectively improve the adaptability of orbital inspection robot localization to the orbital environment. Meanwhile, the results of the modified fusion experiment indicate that the positioning method can improve the positioning accuracy of the orbital inspection robot. Therefore, the proposed positioning method can be applied to the application scenario of a long-distance mining belt conveyor patrol inspection.
Monthly, started in 1955 Supervising institution：Ministry of Education Sponsoring Institution：University of Science and Technology Beijing Editorial office：Editorial Department of Chinese Journal of Engineering Publisher：Science Press Chairperson：Ren-shu Yang Editor-in-Chief：Ai-xiang Wu ISSN 2095-9389CN 2095-9389
