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Sorption data of Cd-TZ for C2H2, C2H4, and CO2

In the contemporary electric arc furnace (EAF) steelmaking industry, increasing contents and temperature homogenization via fluid flow stirring is found to be an effective method of improving production quality and smelting efficiency. It is a trend for different factories with bowl-shaped furnaces to apply the bath fluidity enhancement technology. EAF has plenty of advantages in modern steelmaking industry, and the improvements on the EAF steelmaking process have come up with two major tasks, namely reduction in energy consumption and tap-to-tap time. The latter task requires an essential understanding of every phase in EAF steelmaking process. The flat bath phase with poor bath fluid flow was crucial to the product quality and metallurgical efficiency considering EAF’s bowl-shaped structure. The research of three stirring bath methods, oxygen jets injection, electromagnetic stirring, and bottom blowing, were introduced, and then the detailed parameters of each method with their influences on molten bath fluidity were presented.

BackgroundAtrial fibrillation (AF) is the most common sustained cardiac arrhythmia and engenders significant global health care burden. The underlying mechanisms of AF is remained to be revealed and current treatment options for AF have limitations. Besides, a detection system can help identify those at risk of developing AF and will enable personalized management.Materials and MethodsIn this study, we utilized the robust rank aggregation method to integrate six AF microarray datasets from the Gene Expression Omnibus database, and identified a set of differentially expressed genes between patients with AF and controls. Potential compounds were identified by mining the Connectivity Map database. Functional modules and closely-interacted clusters were identified using weighted gene co-expression network analysis and protein–protein interaction network, respectively. The overlapped hub genes were further filtered. Subsequent analyses were performed to analyze the function, biological features, and regulatory networks. Moreover, a reliable Machine Learning-based diagnostic model was constructed and visualized to clarify the diagnostic features of these genes.ResultsA total of 156 upregulated and 34 downregulated genes were identified, some of which had not been previously investigated. We showed that mitogen-activated protein kinase and epidermal growth factor receptor inhibitors were likely to mitigate AF based on Connectivity Map analysis. Four genes, including CXCL12, LTBP1, LOXL1, and IGFBP3, were identified as hub genes. CXCL12 was shown to play an important role in regulation of local inflammatory response and immune cell infiltration. Regulation of CXCL12 expression in AF was analyzed by constructing a transcription factor-miRNA-mRNA network. The Machine Learning-based diagnostic model generated in this study showed good efficacy and reliability.ConclusionKey genes involving in the pathogenesis of AF and potential therapeutic compounds for AF were identified. The biological features of CXCL12 in AF were investigated using integrative bioinformatics tools. The results suggested that CXCL12 might be a biomarker that could be used for distinguishing subsets of AF, and indicated that CXCL12 might be an important intermediate in the development of AF. A reliable Machine Learning-based diagnostic model was constructed. Our work improved understanding of the mechanisms of AF predisposition and progression, and identified potential therapeutic avenues for treatment of AF.

R31 filter aid containing macromolecular long-chain organic compounds with carboxyl, sulfonic, amide groups was used to improve the filtration of fine hematite concentrate in this study. The carboxyl, sulfonic and amide groups adsorbed on the surface of hematite concentrate particles. The macromolecular long-chain organic compounds flocculated fine hematite concentrate particles to increase the apparent particles size. The H+ ions ionized by carboxylic acid and sulfonic groups compressed hydration film of hematite concentrate particles. The hydrophobic groups in the organic matter decreased the surface wettability of fine hematite concentrate particles. Thinner hydration film and less wettability decreased the water adhesion on surface of hematite concentrate particles. The dehydration rate of filter cake increased from 1.82 × 10−3 ml∙cm2∙s−1 to 3.20 × 10−3 ml∙cm2∙s−1 with a 75.82% increase, when the mass concentration of R31 filter aid increased from 0 to 1800 g/t, and the filter cake moisture content decreased from 19.88% to 17.72%.

The effects of titanium slag on the roasting and metallurgical properties of fluorine-bearing iron concentrate pellets were experimentally investigated in this study. Results show that the compression strength of fluorine-bearing iron concentrate pellets improved up to 3700 Newton/Pellet and the suitable range of roasting temperatures expanded 150 °C with the addition of titanium slag. The results of the scanning electron microscope and energy dispersive spectrum showed that the main phases of fluorine-bearing iron concentrate pellet with titanium slag were hematite, rutile, Fe2TiO5 and silicates. Moreover, the metallurgical properties of roasted fluorine-bearing iron concentrate pellets were improved by adding titanium slag. The softening range of roasted fluorine-bearing concentrate pellets decreased from 106 °C to 59 °C. The reduction swelling index of the roasted fluorine-bearing iron concentrate pellets decreased from 22.76% to 14.26% with the addition of titanium slag.

The technology of coherent lime powder injection (C-LPI) was developed and applied in the electric arc furnace steelmaking, which can inject lime powder into the molten pool deeply and effectively....

The effects of corrosion temperature, oxygen flow rate and corrosion time on the transformation of metallic iron were systematically studied, and the effects of mineral phases of Fe-bearing products on Ti–Fe separation were investigated. The reaction mechanism of metallic iron in corrosion process was proposed. The results showed that corrosion temperature played a key role in determining the transformation of metallic iron in reduced ilmenite during corrosion process. Under suitable corrosion conditions, Fe-bearing mineral in reduced ilmenite could be converted to amorphous ferric hydroxide, lepidocrocite, hematite and magnetite, respectively, and lepidocrocite was the most easily separated Fe-bearing mineral from corrosion products owing to the significant density difference between lepidocrocite and Ti-rich materials. The Ti-rich material with 77.81 wt.% TiO2 and Fe-bearing product with 52.69 wt.% total Fe were obtained by gravity separation. The Ti recovery ratio and Fe recovery ratio were 91.16% and 86.27%, respectively.

The method of carbon powder mixed injection with a shrouding supersonic oxygen jet was proposed to increase the utilization efficiency of carbon powder and improve the foaming slag operation during the electric arc furnace (EAF) steelmaking process by delivering the carbon powder more deeply into the molten bath. In this study, the fluid flow characteristics of the carbon powder mixed injection with a shrouding supersonic oxygen jet were studied and analyzed using numerical simulations, which were first validated by a cold test experiment. Compared with the conventional carbon powder injection without a shrouding jet, the shrouding supersonic oxygen jet can protect the central gas-powder jet against the entrainment of the surrounding atmosphere, increase the velocity of carbon powder and make the carbon powder cluster together in a longer distance. Furthermore, the industrial application research was carried out in a 50-ton commercial Consteel EAF, and the relative metallurgical effects were also studied. Compared with EAF steelmaking using conventional carbon powder injection without a shrouding jet, the powder consumption, tap-to-tap time, FeO content in the final molten slag and phosphorus content of the final molten steel were reduced by 19.3 kWh/ton, 4 min/heat, 2.6 pct and 1.2 × 10−3 pct, respectively, after using the method of carbon powder mixed injection with a shrouding supersonic oxygen jet.

The effects of CaO content, MgO content and smelting temperature on the vanadium behavior during the smelting of vanadium titanomagnetite metallized pellets were investigated. The thermodynamics of reduction and distribution of vanadium was analyzed and the high-temperature smelting experiments were carried out. The thermodynamic calculations show that the distribution ratio of vanadium between the slag and the hot metal decreases with the increments of CaO and MgO content in the slag as well as the increase of the smelting temperature. The smelting experiments demonstrate that the vanadium content in iron and the recovery rate of vanadium in pig iron increase as the CaO content, MgO content and smelting temperature increase, whereas the vanadium distribution ratio between the slag and iron tends to decrease. Moreover, the recovery rate of vanadium in pig iron has a rising trend with increasing the optical basicity of the slag. The addition of MgO in the slag to increase the slag optical basicity can not only improve the vanadium reduction but also promote the formation of magnesium-containing anosovite, which is beneficial to following titanium extraction.

Slag basicity (mass ratio of CaO to SiO2) is an important index to ensure smooth operation and efficient separation between the metal and slag within the metallurgical industry. Effects of basicity of the high titanium slag on the recovery of iron and vanadium, the separation behaviors between iron and slag, as well as the slag foaming behavior during the smelting process with the operating temperature of 1550 °C have been experimentally investigated. The results show that the recovery ratios of iron and vanadium increase with higher slag basicity. The amount of dispersed metallic iron droplets in the slag decreases sharply when the basicity increases from 0.5 to 0.8, then decreases slowly when the basicity is from 0.8 to 1.1. Furthermore, the perovskite (CaTiO3) phase appears when the basicity is above 0.8. The foaming height is at a high level when the basicity is from 0.5 to 0.6, then it decreases when the basicity is increased from 0.6 to 0.7, whereas it slowly increases with higher slag basicity. Finally, the optimum basicity range of titanium slag for efficient smelting of vanadium titanomagnetite is proposed to be 0.8 to 1.1 by considering the combined effects on the recovery, foaming, and minimization on the retention of the metal droplets within the slag.

A novel method for recovering zinc from zinc ferrite by reduction roasting-ammonia leaching was studied in this paper. The reduction thermodynamic of zinc ferrite by CO was analyzed. The effects of roasting parameters on the phase transformation and conversion rate of zinc ferrite, and the leaching behavior of zinc from the reductive roasted samples by ammonia leaching, were experimentally investigated. The mineralogical phase compositions and chemical compositions of the samples were characterized by X-ray diffraction and chemical titration methods, respectively. The results showed that most of the zinc ferrite was transformed to zinc oxide and magnetite after weak reduction roasting. 86.43% of the zinc ferrite was transformed to zinc oxide under the optimum conditions: CO partial pressure of 25%, roasting temperature of 750°C, and roasting duration of 45 min. Finally, under the optimal leaching conditions, 78.12% of zinc was leached into the solution from the roasted zinc ferrite while all iron-bearing materials were kept in the leaching residue. The leaching conditions are listed as follows: leaching duration of 90 min, ammonia solution with 6 mol/L concentration, leaching temperature of 50°C, solid-to-liquid ratio of 40 g/L, and stirring speed of 200 r/min.

The deposit-forming problem is one of the main bottlenecks restricting the yield and production benefit of iron ore pellets produced by coal-fired rotary kilns. In order to implement measures to ensure the efficient production of pellets by coal-fired rotary kilns, the mechanism and influencing factors on the deposit formation were reviewed. The pellet powder and coal ash come together to form the material base of the deposit. Meanwhile, the local reducing atmosphere caused by the continued combustion of residual carbon increases the FeO content, resulting in the formation of low-melting-point silicates. Moreover, alkali metal elements in coal ash can also promote liquid phase formation to cause serious deposit aggregation problems. During high-temperature roasting, the liquid phase corrodes the surface of the refractory brick to form the initial deposit, whereafter, it binds the pellet powder and coal ash from the material layer, which causes the deposit to accumulate continuously. The deposit formation of coal-fired rotary kilns is the result of interaction between many factors, which includes the quality of the green pellets, the composition of coal ash, the combustion efficiency of pulverized coal, roasting temperature, FeO content and alkali metal input. Finally, it is recommended that some measures to mitigate deposit formation can be adopted, such as increasing the compression strength of preheated pellets, choosing high-quality raw materials with low alkali metals, improving the combustion of pulverized coal.

In order to improve the control on sulphur content at the endpoint of Kanbara Reactor (KR) desulphurization process, the case-based reasoning (CBR) method based on mechanistic model correction is u...

The tribological properties and thermal-stress behaviors of C/C-SiC composites during braking were investigated aiming to simulate braking tests of high-speed trains. The temperature and structural fields of C/C-SiC composites during braking were fully coupled and simulated with ANSYS software. The results of tribological tests indicated that the C/C-SiC composites showed excellent static friction coefficient (0.68) and dynamic friction coefficient (average value of 0.36). The highest temperature on friction surface was 445 °C. The simulated temperature field showed that the highest temperature which appeared on the friction surface during braking was about 463 °C. Analysis regarding thermal-stress field showed that the highest thermal-stress on friction surface was 11.5 MPa. The temperature and thermal-stress distributions on friction surface during braking showed the same tendency.

The suitable titanium slag composition with high titanium content for electric furnace smelting of vanadium titanomagnetite was investigated through thermodynamics and related phase diagram analysis. According to the thermodynamic results, low-melting-point regions and MgTi2O5 primary phase area in the phase diagrams, the suggested titanium slag composition for the present vanadium titanomagnetite metallized pellets should consist of 50% TiO2, 8%–12% MgO and 13% Al2O3 (mass fraction) with a binary basicity of 0.8–1.2. Finally, the verified smelting experiments were conducted and successful separation of the molten iron from the titanium slag is obtained. The obtained vanadium-containing molten iron contains 0.681% V and 0.267% Ti, and the obtained titanium slag contains 52.21% TiO2 (mass fraction), in which MgTi2O5 is the primary phase. The titanium resource in the final titanium slag production could be used to produce TiO2 pigment by acid leaching methods.

Willemite is a common component of zinc and lead metallurgical slags that, in the absence of effective utilization methods, cause serious environmental problems. To solve this problem and increase zinc recovery, we proposed a novel extraction method of zinc from willemite by calcified roasting followed by leaching in NH4Cl–NH3·H2O solution. The thermodynamics and phase conversion of Zn2SiO4 to zinc oxide (ZnO) during calcified roasting with CaO were investigated. The mechanism of mineralogical phase conversion and the effects of the CaO-to-Zn2SiO4 mole ratio (n(CaO)/n(Zn2SiO4)), roasting temperature, and the roasting time on zinc-bearing phase conversion were experimentally investigated. The results show that Zn2SiO4 was first converted to Ca2ZnSi2O7 and then to ZnO. The critical step in extracting zinc from willemite is the conversion of Zn2SiO4 to ZnO. The zinc percent leached in the ammonia leaching system rapidly increased because of the gradual complete phase conversion from willemite to ZnO via the calcified roasting process.

Electric arc furnace (EAF) steel bottom-blowing can effectively improve the temperature and composition uniformity of the molten pool during smelting process. To explore the effect of molten-steel characteristics on bottom-blowing at various stages of smelting, we divided the smelting process of the EAF into four stages: the melting stage, the early decarburization stage, the intermediate smelting stage, and the ending smelting stage. The numerical simulation software ANSYS Fluent 18.2 was used to simulate the velocity field of molten steel under the condition of bottom-blowing stirring in different stages in EAF steelmaking process. The properties of bottom-blowing and the kinetic conditions of the steel-slag at this interface were investigated. Our results showed that at a bottom-blowing gas flow rate of 100 L/min, the average flow rates of the four stages were v1 = 0.0081 m/s, v2 = 0.0069 m/s, v3 = 0.0063 m/s, and v4 = 0.0053 m/s. The physical model verification confirmed the results, that is, the viscosity of molten steel decreased as the smelting progressed, and the flow velocity of the molten steel caused by the agitation of bottom-blowing also decreased, the effect of bottom-blowing decreased. Based on these results, a theoretical basis was provided for the development of the bottom-blowing process.

A novel direct-current electric arc furnace (DC-EAF) was designed and constructed in this study for experimentally investigating high-titanium slag smelting, with an emphasis on addressing the issues of incomplete separation of metal and slag as well as poor insulation effects. The mechanical components (crucible, electrode, furnace lining, etc.) were designed and developed, and an embedded crucible design was adopted to promote metal-slag separation. The lining and bottom thicknesses of the furnace were determined via calculation using the heat balance equations, which improved the thermal insulation. To monitor the DC-EAF electrical parameters, suitable software was developed. For evaluating the performance of the furnace, a series of tests were run to determine the optimal coke addition under the conditions of constant temperature (1607 °C) and melting time (90 min). The results demonstrated that for 12 kg of titanium-containing metallized pellets, 4% coke was the most effective for enrichment of TiO2 in the high-titanium slag, with the TiO2 content reaching 93.34%. Moreover, the DC-EAF met the design requirements pertaining to lining thickness and facilitated metal-slag separation, showing satisfactory performance during experiments.

Generally in the nickel converter slag, metals are mainly in the form of sulfides, which are difficult to separate from slag. Although metal oxides in the slag, such as NiO, CoO, and Cu2O, are easily reduced into metal using carbon, the presence of sulfur inhibits the reduction reaction. In this study, the addition of Fe2O3 to nickel converter slag produced desulfurized slag, which enhanced the carbothermal reduction process. Increasing the desulfurization rate promoted the conversion of sulfides into oxides in slag, which significantly increased the activity of NiO, Cu2O, and Fe2O3. However, the residual sulfur content had no significant effect on the activity of FeO and CoO, due to the high initial FeO content and cobalt existing mainly in the form of oxides. The optimum addition of Fe2O3 was 15.0 g per 100 g nickel slag, while the desulfurization ratio was 36.84% and the rates of nikel, cobalt and copper recovery were 95.33%, 77.73%, and 73.83%, respectively.

A hydraulic model with a similarity ratio of 1:4 was used to simulate the blowing parameters of 65t electric arc furnace (EAF). The molten bath stirring effects of different bottom blowing arrangements and flow rates under different combined blowing conditions were studied. On this basis, orthogonal experiments were designed to study the effects of bottom blowing rate, side blowing rate, and bottom blowing arrangement on the mixing time of molten bath. The results showed that the bottom blowing arrangement has little effect on the mixing time of molten pool. Under the condition of combined blowing, the degree of influencing factors on mixing time from big to small was the side blowing rate, bottom blowing rate, and bottom blowing arrangement. The industrial experiment showed that, compared with traditional process, the combined blowing process can increase the decarbonization rate and reduce the consumption of iron and steel materials.

As the three-level management system for material consumption in the EAF steelmaking plant cannot obtain statistics and carry calculation of material consumption for each furnace, the data from the system cannot provide guidance for actual smelting operation. In this paper, the field PLC process smelting data of the material consumption in “EAF-LF-CC” process were collected from Kepware as OPC Server and by VS2010 as development tool. Then, they were classified (in categories of scrap charging, auxiliary materials, gas consumption, injection information, power supply data, etc.) and stored into Microsoft SQL Server 2008 database to build a database of furnace material consumption. The database construction provides guidance for reducing the material consumption and optimizing smelting operation for each furnace.

The supersonic oxygen supply technology, including the coherent supersonic jet and the conventional supersonic jet, is now widely adopted in electric arc furnace steelmaking process to increase the bath stirring, reaction rates and energy efficiency. However, there has been limited study on the impact characteristics of the coherent supersonic jet and the conventional supersonic jet. Thus, integrating theoretical models and numerical simulations, an optimized theoretical model was developed to calculate the volume of the impact zone generated by coherent and conventional supersonic jets. The optimized theoretical model was validated by water model experiments. The results show that the jet impact zone volume with coherent supersonic jet is much larger than that with conventional supersonic jet at the same lance height. The kd value, a newly defined variable that is the product of the dimensionless quantity of velocity and free distance, reflects the velocity attenuation and the potential core length of the main supersonic jet, which is a key parameter of the optimized theoretical model. The optimized theoretical model can well predict the jet impact zone volumes of coherent and conventional supersonic jets with the error no more than 3.62 and 9.37%, respectively.

The melting behavior of titanium-bearing electric furnace slag is a key factor for effective smelting of vanadium titanomagnetite in electric furnaces. The melting behavior of synthetically produced CaO-SiO2-MgO-Al2O3-TiO2 slags with different TiO2 contents (48 wt.% to 54 wt.%), CaO/SiO2 mass ratios (0.8 to 1.4), and MgO contents (8 wt.% to 14 wt.%) was experimentally investigated in this study. The results demonstrate that the softening and melting temperatures decreased as the CaO/SiO2 ratio was increased but increased with increasing contents of TiO2 and MgO. The predicted slag phase composition showed that increasing the CaO/SiO2 mass ratio promoted CaTiO3 formation, whereas the proportion of MgTi2O5 phase increased with increasing MgO content. Appropriate slag compositions with binary basicity of 0.8 to 1.0, 10 wt.% to 12 wt.% MgO, and more than 48 wt.% TiO2 are suggested to obtain titanium-bearing electric furnace slag with low melting temperature and appropriate phase composition for titanium extraction.

The compressive strength of the roasted fluoride-containing iron ore pellets reached to 2463 N/P at roasting temperature 1080 °C for 10 min with appropriate preheating conditions. However, its compression strength drastically dropped no matter increasing or decreasing the roasting temperature and time. Unfortunately, the narrow suitable roasting temperature range seriously affects the normal pellets productions, while the low compressive strength of pellets limits their application in the blast furnace. In the present study, The SEM-EDS, TG-DSC techniques, and thermodynamic software were adopted to systematically investigate the roasting behaviors of fluoride-bearing iron concentrate pellet and the formation mechanism of liquid phases in the pellets during the roasting process. Furthermore, according to the EDS results and the phase diagram analysis, the low-melting-point phase Ca4Si2F2O7 was generated with the existence of fluorine and Na(K)AlSi3O8 was formed with the existence of alkali metal. These low-melting-point phases can react with the CaAl2Si2O8, CaSiO3, SiO2, and CaF2 to form the complex eutectics which had lower melting points. Briefly, the excessive amount of liquid phases in pellet generated from the fluorine and alkali metals primarily caused the poor roasting properties of the fluoride-containing pellet.

Serious deposits in the grate-kiln plant for iron ore pellet production can decline pellets quality and reduce production efficiency. The initial stage of deposit formation is crucial for adhesion and growth of deposit on refractories in the kiln. In this study, the simulated experiments of FeO formation indicated that the high FeO content decreased with increasing the roasting time. The effects of combustion efficiency of pulverized coal and Na2O amount on the adhesion on the refractory bricks were experimentally studied using an evaluated method. The results showed that the adhesion on the refractory bricks increased with decreasing the combustion efficiency of pulverized coal and increasing the Na2O content in the deposits. Finally, the mechanism of deposit formation mainly on the center-entrance area in the kiln was summarized as follows: the pulverized pellet powder and coal ash with unburnt carbon fell into the pores and cracks of the refractory bricks in the kiln. The unburnt carbon and alkali metal chemically reacted with the pellet powder and contributed to the formation of low-melting-point phases (fayalite, silicate), then the generated low melting point phases plus the chemical reactions between the deposits and refractory bricks caused the adhesion of deposits on the refractory bricks. The deposits grew and became thicker as the continuous effects of the above process.

Deposit in the grate-kiln process is a well-known problem for iron ore pellet production. In this study, the deposits in a coal-fired grate-kiln plant for hematite pellet production were characterized to reveal their formation mechanisms. Scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and X-ray powder diffraction (XRD) analysis demonstrated that the main phase of the deposits was hematite with minor proportions of magnesioferrite, hedenbergite, quartz and anorthite. Comparisons of key elemental ratios showed that the silicate phases in the deposits mainly originated from the coal ash and partly from the pellet powder. The primary form of deposits formed in the grate and feeding area in the kiln was the liquid solidification. The hematite particles could be reduced to FeO by unburnt carbon from the uncompleted coal combustion, and then the sufficient liquids for deposit formation were generated with the presence of FeO. The primary manner to form the deposits near the burner zone in the rotary kiln was the hematite crystallization and diffusion, while the liquid phases played a secondary role in the deposit formation. The generated FeO caused by unburnt coal residue not only contributed to the formation of liquid phases at low-temperature parts but also was beneficial to the combination of solid particles at high-temperature parts in the grate and kiln.

The suppression of titanium oxide reduction enables both successful separation of iron from slag and smooth production operations for the smelting of vanadium titanomagnetite. This study investigates the distribution behavior of titanium between the hot metal and enriched titanium slag during the electric furnace smelting of vanadium titanomagnetite metallized pellets. Activity calculations indicate that the TiO2 activity decreases with increasing amounts of CaO and MgO, whereas the TiO2 activity increases with smelting temperature. Additionally, high temperature experiments demonstrate that the titanium distribution ratio between the molten iron and titanium slag decreases with increasing CaO content in the slag. With the presence of high CaO content, increasing MgO content does not have a significant influence on the titanium distribution ratio. The titanium distribution ratio decreases with an increase in slag optical basicity but increases with an increment of the smelting temperature.

The behavior of silicon during smelting of vanadium titanomagnetite metallized pellets in an electric furnace has been investigated thermodynamically and experimentally. Thermodynamic calculations indicated that the activities of free oxygen ion and silicate increase with increasing CaO and MgO content in the titanium slag, whereas silica activity decreases as CaO and MgO increase. High-temperature experiments demonstrated that the Si content in the molten iron and distribution ratio of silicon between metal and slag decreased with suitable additions of CaO and MgO, but increased with smelting temperature. The Si content in the iron positively correlated with the Ti content in the iron but showed no obvious relationship with the V content in the iron. The Si and Ti contents increased with increasing smelting temperature. The Si content should be controlled below about 0.2 wt.% for effective and comprehensive smelting of vanadium titanomagnetite.

As an efficient oxygen supplying technology, coherent jets are widely applied in electric arc furnace (EAF) steelmaking processes to strengthen chemical energy input, speed up smelting rhythm, and promote the uniformity of molten bath temperature and compositions. Recently, the coherent jet with CO2 and O2 mixed injection (COMI) was proposed and demonstrated great application potentiality in reducing the dust production in EAF steelmaking. In the present study, based on the eddy dissipation concept model, a computational fluid dynamics model of coherent jets with COMI was built with the overall and detailed chemical kinetic mechanisms (GRI-Mech 3.0). Compared with one-step combustion reaction, GRI-Mech 3.0 consists of 325 elementary reactions with 53 components and can predict more accurate results. The numerical simulation results were validated by the combustion experiment data. The jet behavior and the fluid flow characteristics of coherent jets with COMI under 298 K and 1700 K (25 °C and 1427 °C) were studied and the results showed that for coherent jets with COMI, the chemical effect of CO2 significantly weakened the shrouding combustion reactions of CH4 and the relative importance of the chemical effect of CO2 increases with CO2 concentration increasing. The potential core length of coherent jet decreases with the volume fraction of CO2 increasing. Moreover, it also can be found that the potential core length of coherent jets was prolonged with higher ambient temperature.

With the increase of hot metal ratio in electric arc furnace (EAF) steelmaking process, physical sensible heat and chemical latent heat of gas increased significantly. As EAF raw material condition is similar to basic oxygen furnace (BOF), and the condition of BOF gas waste heat utilization technology is mature, waste heat utilization technology in EAF steelmaking will be getting more and more attention. Scrap preheating and steam production as mature technology is the main way of EAF gas waste heat utilization. Power generation converted high temperature steam to electricity will further improve the EAF gas utilization value. The previous ways are to recycle physical sensible heat of EAF gas. To use chemical latent heat of gas, the secondary combustion technology is usually adopted to make CO fully burn into CO2. Coal gas production can fully recycle the chemical latent heat of gas theoretically, which is higher efficiency than other ways. Coal gas production needs a stable steelmaking process to stabilize high temperature gas. And the way need to develop EAF sealing technology, oxygen removal technology and gas purification technology, to make gas content meet the requirements of coal gas production in EAF steelmaking process.

A novel process to prepare titanium dioxide from Ti-bearing electric furnace slag by NH4HF2-HF leaching and hydrolyzing process has been developed. In this present study, the effects of [NH4+]/[F] mXolar ratio, leaching temperature, [F] concentration, liquid/solid mass ratio, leaching time on the Ti extraction, and the phase transformations have been investigated to reveal the leaching mechanism of Ti-bearing electric furnace slag in NH4HF2-HF solution. In the NH4HF2-HF leaching process, the MgTi2O5 and Al2TiO5 are converted to TiF62− and Mg-Al-bearing precipitate. Ti extraction rate reached 98.84% under the optimal conditions. In addition, 98.25% iron ions can be removed in the presence of NaCl prior to hydrolysis process. The effects of pH and temperature on the selective hydrolysis of TiF62− during hydrolysis process were also studied. In the hydrolysis process, the TiF62− is converted to (NH4)2TiOF4. By calcination, high grade TiO2 powder with its purity of 99.88% was obtained, using which the products, well crystallized anatase and rutile, were obtained through roasting at 800 °C and 1000 °C, respectively.

In modern EAF steelmaking process, control of the nitrogen content of molten steel has become more and more important and bottom-blowing technique has been widely applied to promote the molten bath...

Fluorine-bearing iron ore is unique and complex. Serious preheating and roasting problems of fluorine-bearing iron concentrate pellets appear during the industrial production by the grate-kiln process. Besides, specularite has low hydrophilicity, undesirable particle size and shape, dense and smooth particle surface and poor assimilation performance. Thus, it has not yet been widely applied in production. This study applied the specularite to improve the preheating and roasting characteristics of the fluorine-bearing iron concentrate pellets. The experiment results indicated that the roasting properties of fluorine-bearing iron concentrate pellets were improved and the compression strength of roasted pellets increased with the addition of 10% specularite. The suitable roasting temperature range was expanded to more than 140 °C. Compared to other addition, the total iron of pellets was also increased. In addition, the improvement mechanism of adding specularite on the properties of fluorine-bearing iron concentrate pellets was discussed.

The effects of F− concentration, leaching temperature, and time on the Ti leaching from Ti-bearing electric furnace slag (TEFS) by [NH4+]-[F−] solution leaching process was investigated to reveal the leaching mechanism and kinetics of titanium. The results indicated that the Ti leaching rate obviously increased with the increase of leaching temperature and F− concentration. The kinetic equation of Ti leaching was obtained, and the activation energy was 52.30 kJ/mol. The fitting results of kinetic equations and calculated values of activation energy both indicated that the leaching rate of TEFS was controlled by surface chemical reaction. The semi-empirical kinetics equation was consistent with the real experimental results, with a correlation coefficient (R2) of 0.996. The Ti leaching rate reached 92.83% after leaching at 90 °C for 20 min with F− concentration of 14 mol/L and [NH4+]/[F−] ratio of 0.4. The leaching rates of Si, Fe, V, Mn, and Cr were 94.03%, 7.24%, 5.36%, 4.54%, and 1.73%, respectively. The Ca, Mg, and Al elements were converted to (NH4)3AlF6 and CaMg2Al2F12 in the residue, which can transform into stable oxides and fluorides after pyro-hydrolyzing and calcinating.

With the rapid development of Internet, it is increasingly convenient to obtain real-time traffic condition information, which has greatly stimulated the improvement of urban traffic guidance. Traffic conditions are generally divided into four grades in the existing network platform, which are expressed in different colours. The understanding of traffic condition is still at the level of abstract senses. Therefore, it is difficult to grasp the characteristics of urban traffic. To this end, a new idea is proposed in this paper, and the new idea is to study the urban traffic characteristics based on real-time traffic condition information extraction with image identification technology. With this method, we can not only quantify the abstract traffic condition information, but also solve the loss of traffic condition information. In addition, an instance is analysed in this paper, it shows that it can provide references for urban traffic organization management very well.

Supersonic oxygen-supplying technologies, including the coherent supersonic jet and the conventional supersonic jet, are now widely applied in electric arc furnace steelmaking processes to increase the bath stirring, reaction rates, and energy efficiency. However, there has been limited research on the impact characteristics of the two supersonic jets. In the present study, by integrating theoretical modeling and numerical simulations, a hybrid model was developed and modified to calculate the penetration depth and impact zone volume of the coherent and conventional supersonic jets. The computational fluid dynamics results were validated against water model experiments. The results show that the lance height has significant influence on the jet penetration depth and jet impact zone volume. The penetration depth decreases with increasing lance height, whereas the jet impact zone volume initially increases and then decreases with increasing lance height. In addition, the penetration depth and impact zone volume of the coherent supersonic jet are larger than those of the conventional supersonic jet at the same lance height, which illustrates the advantages of the coherent supersonic jet in delivering great amounts of oxygen to liquid melt with a better stirring effect compared to the conventional supersonic jet. A newly defined parameter, the k value, reflects the velocity attenuation and the potential core length of the main supersonic jet. Finally, a hybrid model and its modifications can well predict the penetration depth and impact zone volume of the coherent and conventional supersonic jets.

As the cost of hot metal is reduced for iron ore prices are falling in the international market, more and more electric arc furnace (EAF) steelmaking enterprises use partial hot metal instead of scrap as raw materials to reduce costs and the power consumption. In this paper, carbon emissions based on 1,000 kg molten steel by charging hot metal in EAF steelmaking is studied. Based on the analysis of material and energy balance calculation in EAF, the results show that 146.9, 142.2, 137.0, and 130.8 kg/t of carbon emissions are produced at a hot metal ratio of 0 %, 30 %, 50 %, and 70 %, while 143.4, 98.5, 65.81, and 31.5 kg/t of carbon emissions are produced at a hot metal ratio of 0 %, 30 %, 50 %, and 70 % by using gas waste heat utilization (coal gas production) for EAF steelmaking unit process. However, carbon emissions are increased by charging hot metal for the whole blast furnace–electric arc furnace (BF–EAF) steelmaking process. In the condition that the hot metal produced by BF is surplus, as carbon monoxide in gas increased by charging hot metal, the way of coal gas production can be used for waste heat utilization, which reduces carbon emissions in EAF steelmaking unit process.

Supersonic coherent jet plays a vital role in the steelmaking process; its impact force and stirring ability determine the smelting process. Many researchers have studied the characteristics of coherent jet under different shrouding fuels and oxygen flow conditions, but the preview results cannot reveal the relationship between the shrouding gas temperature, pressure, density, and the flow filed of coherent jet. In this paper, the field characteristics of coherent jet and conventional supersonic jet under different shrouding gas parameter conditions are studied by numerical simulation and experiment. The result shows that the temperature and pressure of the nozzle exit are affected by shrouding gas and it leads to the velocity and temperature fluctuations of the supersonic jet. The high temperature, high speed, and low density environment produced by shrouding gas protect the supersonic jet, and reduce the radial expansion and the axial velocity attenuation rate of the jet. The relationship between the supersonic region length of jet and the shrouding gas parameter is proposed. Compared with the conventional supersonic jet, the distributions of half-jet width and the position of vorticity magnitude are changed by shrouding gas. With the high temperature, high pressure, and low density of the shrouding gas, the turbulence intensity of the jet maintains a low level in a longer distance.

The vanadium-titanium magnetite concentrate from Panxi region of China was pretreated by high pressure roller grinding (HPRG) and then used in pelletization. Size distribution change of the vanadium-titanium magnetite concentrate after HPRG and the improvement of its green pellet strength were investigated. The results indicated that, besides the increase of fine particles, the vanadium-titanium magnetite concentrate after HPRG had a smaller size ratio of fine particle to coarse particle of 0.126, meaning a lower porosity, compared with the size ratio of raw material of 0.157. The concentrate particles were more closely packed when there was a smaller size ratio of fine particle to coarse particle. The particle packing in the green pellets was closer after HPRG, which strengthened the green pellets with an average drop number of 5.1 (drop height of 0.5 m) and average compressive strength of 13.1 N per pellet of 11 mm in diameter.

A SiC/ZrSiO4–SiO2 (SZS) coating was successfully fabricated on the carbon/carbon (C/C) composites by pack cementation, slurry painting and sintering to improve the anti-oxidation property and thermal shock resistance. The anti-oxidation properties under different oxygen partial pressures (OPP) and thermal shock resistance of the SZS coating were investigated. The results show that the SZS coated sample under low OPP, corresponding to the ambient air, during isothermal oxidation was 0.54% in mass gain after 111 h oxidation at 1500 °C and less than 0.03% in mass loss after 50 h oxidation in high OPP, corresponding to the air flow rate of 36 L/h. Additionally, the residual compressive strengths (RCS) of the SZS coated samples after oxidation for 50 h in high OPP and 80 h in low OPP remain about 70% and 72.5% of those of original C/C samples, respectively. Moreover, the mass loss of SZS coated samples subjected to the thermal cycle from 1500 °C in high OPP to boiling water for 30 times was merely 1.61%.

With constant progress gained from fine waterflooding, monitoring methods for reservoir performance have become more diverse, which results in an increasing amounts of data. To realize classified management of separate injectors, a macroscopic control system applied in separate layer water injection is proposed. By virtue of real-time surveillance function of digital separate layer waterflooding technology, the paper presented a macroscopic control system, to ensure effective management and utilization of large sets of available test data. This system consists of three major modules, which are data interpretation and utilization module, injector automatic monitoring module and block-reservoir dynamic adjustment and control module. In 2017, a pilot area that represents ultralow permeability reservoir was chosen to conduct field trial. Meanwhile, a functional test was carried out focusing on the proposed macroscopic control system. The results indicated that it realized digitization for automatic adjustment in single well and real-time monitoring of block reservoir in the whole process. It provides technical support for achieving macroscopic control in intelligent oilfield.

The tin-bearing middling obtained by flotation in Huanggang, Inner Mongolia, is with SnO2 content of 3–5 wt%, which was stacked and cannot be utilized, leading to the tin resource wasting and environmental pollution. In order to recover this tin resource, the tin volatilization behaviour in the tin-bearing middling during carbothermic reduction in rotary kiln process was studied in this paper. The results show that the volatilization rate can reach 87.4% and the SnO2 content in the residue decreased to 0.57 wt% under the conditions of Kiln tail: Kiln middle: Kiln head (coal addition ratio) with 1:2:7, the proportion of ball and coal was 20 kg: 20 kg and the pellets size was 5–10 mm at 1000 °C for 2 h. The research could provide a technical reference for the utilization of the tin-bearing middling.