Effect of Mn addition and refining process on Fe reduction of Mg−Mn alloys made from magnesium scrap

The Fe reduction,microstructure evolution and corrosion susceptibility of Mg−Mn alloys made from magnesium scrap refining with Mn addition were investigated.The results show that significant Fe content change occurs during near-solid-melt treatment(NSMT)process even in the absence of Mn,because of the high saturation of Fe in the melt.Furthermore,in the NSMT process,even a small amount of Mn addition can lead to a sharp deposition of Mn atoms.The NSMT process can increase the growth rate of the Fe-rich particles,and then accelerate their sinking movement.Nevertheless,the addition of Mn hinders the coarsening process of Fe-rich particles.Besides,the corrosion susceptibility of the alloys is mainly affected by the solubility of Fe,which can be significantly reduced by Mn addition.Moreover,the presence of more Fe-rich particles does not necessarily increase the corrosion susceptibility of the alloy.Consequently,in the refining process of Mg−Mn alloys made from magnesium scrap,on the basis of NSMT process and adding an appropriate Mn content(about 0.5 wt.%),the purity of the melt can be improved,thereby obtaining an alloy with excellent corrosion resistance.

Hybrid Neural Network Model for RH Vacuum Refining Process Control

A hybrid neural network model,in which RH process(theoretical)model is combined organically with neural network(NN)and case-base reasoning(CBR),was established.The CBR method was used to select the operation mode and the RH operational guide parameters for different steel grades according to the initial conditions of molten steel,and a three-layer BP neural network was adopted to deal with nonlinear factors for improving and compensating the limitations of technological model for RH process control and end-point prediction.It was verified that the hybrid neural network is effective for improving the precision and calculation efficiency of the model.

Effect of refining processes on inclusions and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy

The effect of different refining processes on inclusions and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy was investigated, including two-stage hexachloroethane (C2Cl6) refining process, two-stage rotating gas bubbling refining process and two-stage composite refining process. It was found that the two-stage composite refining process, which combined C2Cl6 and rotating gas bubbling, can significantly improve the melt purity and mechanical properties of cast Al-2Li-2Cu-0.2Zr alloy. Compared to the unrefined alloy, the volume fraction of gas porosity defects and slag inclusions decreased from 1.47% to 0.12%, and the yield strength, ultimate tensile strength and elongation of as-quenched alloy increased from 113 MPa,179 MPa and 3.9% to 142 MPa, 293 MPa and 18.1%, respectively. C2Cl6 was first utilized to degas and remove large size slag inclusions before lithium addition, and then the rotating gas bubbling was utilized to do the further degassing and remove the suspended fine inclusions after lithium addition. The two-stage composite refining process can take advantage of two methods and get the remarkable refining effect.

Thermal Analysis Simulation of Germanium Zone Refining Process Assuming a Constant Radio-Frequency Heating Source

Three-dimensional thermal a nalysis simulation of a horizontal zone refining system is conducted for germanimn semiconductor materials. The considered geometry includes a g＇ral）hite boat filled with germanium placed in a cylindrical quartz tube. A flow of Ar and H2 gas mixture is purged througll the tube. A narrow section of the, boat is assmned to be exposed to a constant heat rate produced b v an rf coil located outside the quartz tube. The results of this analysis provide essential information about various parameters such as the shape of tile molten zone, required power and temperature gradient in the system.

Multi-model coupling-based dynamic control system of ladle slag in argon blowing refining process

Since the current slagging of argon blowing refining process is relatively fixed,which cannot adapt to the fluctuation of converter smelting process,it poses the problems of poor metallurgical property of refining slag and a large amount of molten heel.An optimization system coupled with multiple models was proposed to dynamic control the ladle slagging in the argon blowing refining process.It can compile the optimal dynamic slagging scheme in real time under the guarantee of deoxidation performance and reasonable fluidity.The argon blowing refining slag composition range of CaO/Al_(2)O_(3)=1.3-1.7,CaO/SiO_(2)=6-12,w(MgO)=2%-6% was determined based on FeO activity and liquidus temperature by equilibrium thermodynamic calculation.In addition,it demonstrated better performance in the viscosity prediction task of the presented Visual Geometry Group 16-like one-dimensional convolutional neural network deep learning algorithm versus the Random Forest ensemble learning algorithm,as the adjusted coefficients of determination were 0.9712 and 0.9637,respectively.After the system was applied in operation,the argon blowing refining process was stable,and the steel yield was enhanced,which promoted the intelligent steelmaking level while achieving the cost reduction and efficiency improvement.

Influence of refining process and utilization of different slags on inclusions, titanium yield and total oxygen content of Ti-stabilized 321 stainless steel

Ti-stabilized 321 stainless steel was prepared using an electric arc furnace, argon oxygen decarburization (AOD) furnace, ladle furnace (LF), and continuous casting processes. In addition, the effect of refining process and utilization of different slags on the evolution of inclusions, titanium yield, and oxygen content was systematically investigated by experimental and thermodynamic analysis. The results reveal that the total oxygen content (TO) and inclusion density decreased during the refining process. The spherical CaO–SiO2–Al2O3–MgO inclusions existed in the 321 stainless steel after the AOD process. Moreover, prior to the Ti addition, the spherical CaO–Al2O3–MgO–SiO2 inclusions were observed during LF refining pro-cess. However, Ti addition resulted in multilayer CaO–Al2O3–MgO–TiOx inclusions. Two different samples were prepared by conventional CaO–Al2O3-based slag (Heat-1) and -TiO2-rich CaO–Al2O3-based slag (Heat-2). The statistical analysis revealed that the density of inclusions and the -TiOx content in CaO–Al2O3–MgO–TiOx inclusions found in Heat-2 sample are much lower than those in the Heat-1 sample. Furthermore, the TO content and Ti yield during the LF refining process were controlled by using -TiO2-rich calcium aluminate synthetic slag. These results were consistent with the ion–molecule coexist-ence theory and FactSage?7.2 software calculations. When -TiO2-rich CaO–Al2O3-based slag was used, the -TiO2 activity of the slag increased, and the equilibrium oxygen content significantly decreased from the AOD to LF processes. Therefore, the higher -TiO2 activity of slag and lower equilibrium oxygen content suppressed the undesirable reactions between Ti and O.

Refining the Production Process

WHILE much of Africa＇s oil production is exported in its crude form, Uganda is primed to build its own oil refinery. This ambition is set to be realized after the China National Offshore Oil Corp. （CNOOC） struck a $2-billion licensing deal to develop a vast petroleum field in Uganda. Signed in late September, it was the first oil production license to be issued in Uganda,

Preparation of V-Ti-Fe master alloys by metallothermic reduction method

V-Ti-Fe master alloys were prepared by metaUothermic reduction method, and the influences of the mass ratio of V205 to TiO2, Al and Al-Mg alloy addition amounts on the metal recovery rates and alloy compositions were investigated. The results show that appropriate technological parameters are： the mass ratio of V205 to TiO2 is 0.5：1, Al addition represents 95% of the theoretical value, and the Al-Mg alloy addition amount is one third that of the Al addition. The results from energy spectrum analysis show that V and Fe distribute uniformly in the prepared alloy, while the segregation for Ti, i.e. Ti-rich phase is detected. A spray refming process was carried out to reduce the impurity contents of Al and O in the prepared alloys. The Al content drops from 4.27% to 1.86%, and the O content drops from 2.10% to 0.91% after the refining process.

Study to Solve the Problem of Color Reversion in Refined Soybean Oil

This study carried out on the soybean oil samples taken from the processing lines during refining process (degumming, neutralization, bleaching and deodorization process) for crude soybean oil as well as on color reversed oil after deodorization step during storage for several hours to study the physical and chemical properties (color, refractive index (RI), free fatty acid (FFA), peroxide value (PV), p-Anisidine value (p-AV), total oxidative (TOTOX) value, oxidative stability (OS), saponification value (SV), iodine value (IV), unsaponifiable matter (unsap. %), soap content, minerals, waxes, total phenols content, K232 and k270 nm), the fatty acids composition, sterol compound, total tocopherols and their components (α, β, γ and δ tocopherol) and tocored compound for these oils and to find out the reason for the color reversion after a short period from storage for the deodorized soybean oil. Citric acid has been added (0.2%) to each color reversed and neutralized soybean oils, then procedure of bleaching and deodorization process on them, and studied its effect on the physical and chemical properties for them specially the color units (red and yellow), tocopherols contents and tocored compound. The results showed that refining process for soybean oil caused to a gradual decrease in values of AV, oxidative stability, IV, wax, % Unsapo., K232 and K270 nm, total polyphenols, minerals (P, Ca and Mg), total tocopherols and their compounds (α, β, γ and δ tocopherol) and also caused decrease in all sterol components, but they showed a few differences in percentages of fatty acids as result refining process. Color values (red and yellow unites) recorded gradually decreased during refining process, but these values were increased in deodorized soybean oil after storage (color reversed soybean oil). Reduction of α, β, γ and δ tocopherol contents was found to be linearly with the increase of red and yellow color units (color darking). The tocored is responsible for the color reversion phenomenon, where as maximum amount of tocored was in crude soybean oil 169.2 ppm, which gradually decreased during refining process 120.35, 99.82, 20.25, and 8.46 ppm, respectively, but it was found to be 46.5 ppm in color reversed soybean oil. Addition of citric acid (0.2%) related to the removal of tocored from soybean oil during the bleaching and deodorization process of soybean oil before and after color reversion in parallel with the significant decrease in the color values.

Changes in PAH and 3-MCPDE contents at the various stages of Camellia oleifera seed oil refining

Objectives:Polycyclic aromatic hydrocarbons(PAHs)and 3-monochloropropane-1,2-diol ester(3-MCPDE)were studied in camellia oil.It is important to study the changes in the content of PAHs and 3-MCPDE at different refining stages(from crude oil to the final refined oil product)to elucidate the influence of the refining procedures on their change.Materials and methods:The PAHs and 3-MCPDE in camellia oil from different refining stages(from crude oil to the product)of a plant were analyzed by gas chromatography–mass spectrometry and calculated by the internal standard method.Results:The overall PAH content was(79.64±2.43)μg/kg in crude camellia oil.After refining treatment,the PAH content decreased to(18.75±0.55)μg/kg.The 3-MCPDE content increased during the refining process from 0 mg/kg in the crude oil to 4.62 mg/kg in the refined oil product.Conclusions:This is the first study to simultaneously monitor changes in both PAH and 3-MCPDE contents during the production of camellia oil.These results confirmed the effectiveness of the refining method on PAH removal and the increase in 3-MCPDE at high temperature.It is suggested that novel processing methods or refining parameters need further optimization to decrease the overall concentrations of PAHs and 3-MCPDE in camellia oil.

Fast filtering false active subspaces for efficient high dimensional similarity processing

The query space of a similarity query is usually narrowed down by pruning inactive query subspaces which contain no query results and keeping active query subspaces which may contain objects corre- sponding to the request. However, some active query subspaces may contain no query results at all, those are called false active query subspaces. It is obvious that the performance of query processing degrades in the presence of false active query subspaces. Our experiments show that this problem becomes seriously when the data are high dimensional and the number of accesses to false active subspaces increases as the dimensionality increases. In order to solve this problem, this paper proposes a space mapping approach to reducing such unnecessary accesses. A given query space can be refined by filtering within its mapped space. To do so, a mapping strategy called maxgap is proposed to improve the efficiency of the refinement processing. Based on the mapping strategy, an index structure called MS-tree and algorithms of query processing are presented in this paper. Finally, the performance of MS-tree is compared with that of other competitors in terms of range queries on a real data set.

Extraction,separation and refining of microcrystalline cellulose from wheat straw using various pretreatments

This study focused on the manufacture of microcrystalline cellulose(MCC)from wheat straw using environmentally-friendly solvents.Raw cellulose was separated from wheat straw after thermal decomposition of lignin followed by dissolution of lignin using a recyclable ethanol/acetic acid/water solvent system.Then,pure cellulose was produced using a four-step refining process,including chelating,O_(3),H_(2)O_(2),and xylanase treatments.Finally,MCC was obtained through hydrolysis,drying,and mechanical treatments.The effects of acetic acid,O_(3),H_(2)O_(2),NaOH,pretreatment time,and temperature on the properties of wheat straw cellulose(including Kappa number,yield,α-cellulose content,crystallinity,KMnO4 value,degree of polymerization(DP),and brightness)were investigated.The results showed that the addition of acetic acid enhanced lignin removal and hemicellulose degradation,improving the purity of the raw cellulose.The optimized acetic acid dosage in the wheat straw thermal decomposition step was 2%(w/w).The optimized O_(3)dosage was 1.2%(w/w).The optimized conditions for H_(2)O_(2)treatment were found to be 3%(w/w)H_(2)O_(2)and 1.8%(w/w)NaOH at 70°C for 120 min.The KMnO4 value was 2.0,brightness was 84.1%ISO,the viscosity was 934 mL/g,and the DP was 626 for refined cellulose.Xylanase effectively improved theα-cellulose content of wheat straw cellulose.With an optimized xylanase dosage of 1.5 IU/g,theα-cellulose content was 94.7%,the brightness was 85.6%ISO,and the DP was 615 for wheat straw cellulose.

Organic composition of gasoline and its potential effects on air pollution in North China

When gasoline is burned to power an automotive engine, a portion of the fuel remains unburned or is partially burned and leaves the engine as hydrocarbon and oxygenated compounds. In addition, a small portion of the fuel can escape the vehicle through evaporation. Changes in alkanes, olefins and aromatics each affect emissions differently, which could complicate control strategies for air pollution. In this study, we collected 31 gasoline samples over five provinces and cities(Beijing, Tianjin, Hebei, Shandong, and Shaanxi) in North China between 2012 and 2013. The organic composition of the gasoline samples was analyzed using the gas chromatography-mass spectrometry(GC-MS) method, and the aniline compounds were analyzed by solvent extraction and the GC-MS method. The ratios of alkanes, aromatics, olefins and other organic compounds in gasoline were 40.6%, 38.1%, 12.9% and 8.4%, respectively. The aromatic and benzene exceedances were 15 and 8 based on the China's gasoline standards(III), and they accounted for 48.4% and 25.8% of all the gasoline samples, respectively. Strong carcinogen aniline compounds were detected in all 31 samples, and the content of aniline compounds in 3 samples exceeded 1%. The high proportion of aromatics and olefins in the gasoline increased the emissions of carbon monoxide(CO) and toxics, as well as the atmospheric photochemical reactivity of exhaust emissions, which could hasten the formation of secondary pollutants. Our results are helpful for redefining government strategies to control air pollution in North China and relevant for developing new refining technology throughout China.