Metallurgical performance evaluation of space-weathered Chang’e-5 lunar soil

Space metallurgy is an interdisciplinary field that combines planetary space science and metallurgical engineering.It involves systematic and theoretical engineering technology for utilizing planetary resources in situ.However,space metallurgy on the Moon is challenging because the lunar surface has experienced space weathering due to the lack of atmosphere and magnetic field,making the mi-crostructure of lunar soil differ from that of minerals on the Earth.In this study,scanning electron microscopy and transmission electron microscopy analyses were performed on Chang’e-5 powder lunar soil samples.The microstructural characteristics of the lunar soil may drastically change its metallurgical performance.The main special structure of lunar soil minerals include the nanophase iron formed by the impact of micrometeorites,the amorphous layer caused by solar wind injection,and radiation tracks modified by high-energy particle rays inside mineral crystals.The nanophase iron presents a wide distribution,which may have a great impact on the electromagnetic prop-erties of lunar soil.Hydrogen ions injected by solar wind may promote the hydrogen reduction process.The widely distributed amorph-ous layer and impact glass can promote the melting and diffusion process of lunar soil.Therefore,although high-energy events on the lun-ar surface transform the lunar soil,they also increase the chemical activity of the lunar soil.This is a property that earth samples and tradi-tional simulated lunar soil lack.The application of space metallurgy requires comprehensive consideration of the unique physical and chemical properties of lunar soil.

Effect of lump ore ratio on the metallurgical properties of blast furnace charge

We conducted a series of experimental studies on the metallurgical properties of N-lump and F-lump ores used in Baosteel’s blast furnace, including thermal cracking, low-temperature reduction pulverization, reducibility, and droplet properties.The results show that the thermal burst properties of N-lump ore are better than those of F-lump ore.The low-temperature reduction degradation index(RDI) pulverization of the charge is the best when the ratios of N-lump ore and F-lump ore account for 35% each.The reduction performance of the charge is improved when F-lump and N-lump ores are mixed with sinter.In the softening-melting performance experiment, when the proportion of N-lump ore is 40%,the characteristic area value(S) as the charge permeability index is the smallest.When F-lump ore is mixed with sinter, its droplet performance improves compared with that of single F-lump ore.The proportion of F-lump ore should not exceed 15%.

Boron removal in purifying metallurgical grade silicon by CaO-SiO_2 slag refining

Boron removal from metallurgical grade silicon （MG-Si） using a calcium silicate slag was studied. The results show that it is impossible basically to remove boron using a pure SiO2 refining. The oxidizing ability of CaO-SiO2 slag for boron removal was characterized by establishing the thermodynamic relationship between the distribution coefficient of boron （LB） and the activities of SiO2 and CaO. The experimental results show that the distribution coefficient and the removal efficiency of boron are greatly improved with the increase of CaO proportion in the slag. The maximal value of LB reaches 1.57 with a slag composition of 60%CaO-40%SiO2 （mass fraction）. The boron content in the refined silicon is reduced from 18×10^-6 to 1.8×10^-6 using slag refining at 1600 ℃ for 3 h with a CaO-SiO2/MG-Si ratio of 2.5, and the removal efficiency of boron reaches 90%.

Removal of boron from metallurgical grade silicon by electromagnetic induction slag melting

A new purification process was developed to remove impurities in metallurgical grade silicon （MG-Si） by electromagnetic induction slag melting （EISM）. Vacuum melting furnace was used to purify boron in different slag systems. The results show that the removal effect in SiO2-CaO-Al2O3 systems is better than that in other slag systems by EISM. The boron content in MG-Si is successfully reduced from 1.5× 10^-5 to 0.2× 10^-5 during EISM at 1 823 K for 2 h. Meanwhile, Al, Ca and Mg elements in MG-Si are also well removed and their removal efficiencies reach 85.0%, 50.2% and 66.7%, respectively, which indicates that EISM is very effective to remove boron and metal impurities in silicon.

Thermodynamic behavior and morphology of impurities in metallurgical grade silicon in process of O_2 blowing

Gas blowing is a valid method to remove the impurities from metallurgical grade silicon（MG-Si） melt.The thermodynamic behavior of impurities Fe,Al,Ca,Ti,Cu,C,B and P in MG-Si was studied in the process of O2 blowing.The removal efficiencies of impurities in MG-Si were investigated using O2 blowing in ladle.It is found that the removal efficiencies are higher than 90% for Ca and Al and nearly 50% for B and Ti.The morphology of inclusions was analyzed and the phases Al3Ni,NiSi2 and Al3Ni were confirmed in MG-Si by X-ray diffraction.It was found that SiB4 exists in Si？B binary system.The chemical composition of inclusions in MG-Si before and after refining was analyzed by SEM-EDS.It is found that the amount of white inclusion reduces for the removal of most Al and Ca in the forms of molten slag inclusion and the contents of Fe,Ni and Mn in inclusion increase for their inertia in silicon melt with O2 blowing.

Removal of phosphorus from metallurgical grade silicon by Ar-H_2O gas mixtures

The removal of phosphorus in metallurgical grade silicon （MG-Si） by water vapor carried with high purity argon was examined. The effect of the nozzle types, refining time, refining temperature, refining gas temperature and refining gas flow rate on the phosphorus removed was investigated by the self-designed gas blowing device. The optimal refining conditions are nozzle type of holes at bottom and side, refining time of 3 h, refining temperature of 1793 K, refining gas temperature of 373 K, refining gas flow rate of 2 L/min. Under these optimal conditions, the phosphorus content in MG-Si is reduced from 94×10^-6 initially to 11×10-6 （mass fraction）, which indicates that gas blowing refining is very effective to remove phosphorus in MG-Si.

Low-temperature purification process of metallurgical silicon

The removal of B and P consumes most of heat energy in Si metallurgical purification process for solar-grade Si. Metal-liquating purification of metallurgical grade silicon （MG-Si）, also called Si-recrystallization from metal liquid, was a potential energy-saving method for the removal of B and P efficiently, since Si could be melted at lower temperature by alloying with metal. The selection criteria of metal-liquating system was elaborated, and Al, Sn and In were selected out as the optimum metallic mediums. For Sn-Si system, the segregation coefficient of B decreased to 0.038 at 1 500 K, which was much less than 0.8 at the melting point of Si. The mass fraction of B was diminished from 15×10^-6 to 0.1×10^-6 as MG-Si was purified by twice, while that of most metallic elements could be decreased to 0.1×10^-6 by purifying just once. During the metal-liquating process, the formation of compounds between impurity elements and Si was also an important route of impurity removal. Finally, one low-temperature metallurgical process based on metal-liquating method was proposed.

Development and prospects of molten steel deoxidation in steelmaking process

In the long traditional process of steelmaking,excess oxygen is blown into the converter,and alloying elements are used for deoxidation.This inevitably results in excessive deoxidation of products remaining within the steel liquid,affecting the cleanliness of the steel.With the increasing requirements for steel performance,reducing the oxygen content in the steel liquid and ensuring its high cleanliness is necessary.After more than a hundred years of development,the total oxygen content in steel has been reduced from approximately 100×10^(-6)to approximately 10×10^(-6),and it can be controlled below 5×10^(-6)in some steel grades.A relatively stable and mature deoxidation technology has been formed,but further reducing the oxygen content in steel is no longer significant for improving steel quality.Our research team developed a deoxidation technology for bearing steel by optimizing the entire conventional process.The technology combines silicon–manganese predeoxidation,ladle furnace diffusion deoxidation,and vacuum final deoxidation.We successfully conducted industrial experiments and produced interstitial-free steel with natural decarbonization predeoxidation.Non-aluminum deoxidation was found to control the oxygen content in bearing steel to between 4×10^(-6) and 8×10^(-6),altering the type of inclusions,eliminating large particle Ds-type inclusions,improving the flowability of the steel liquid,and deriving a higher fatigue life.The natural decarbonization predeoxidation of interstitial-free steel reduced aluminum consumption and production costs and significantly improved the quality of cast billets.

Effect of thermal annealing on defects of upgraded metallurgical grade silicon

Effect of thermal annealing on the upgraded metallurgical grade（UMG）-Si was investigated under different conditions.The dislocation,grain boundaries and preferred growth orientation of Si ingot were characterized by optical microscopy,electron back scattering diffraction（EBSD） and X-ray diffractometry（XRD）,respectively.The arrange order of dislocation density of Si ingot is from the lowest in the middle to the lower in the bottom and low in the top before and after annealing.And it decreases gradually with increase of the annealing temperature.The number of small angle grain boundaries declines gradually until disappears whereas the proportion of coincidence site lattice（CSL） grain boundaries increases firstly and then decreases.The twin boundary Σ3 reaches the highest proportion of 28% after annealing at 1 200 ℃ for 3 h.Furthermore,the crystal grains in different positions gain the best preferred growth orientation,which can promote the following machining of Si ingot and the conversion efficiency of solar cells.

METALLURGICAL SYSTEMS ENGINEERING:PRESENT SITUATION AND FUTURE

The paper presents a discussion on the emergence and development of metallurgical systems engineering on the account of the history and development of modern metallurgy. The contents, characteristics, methodology and applications of metallurgical systems engineering are also addressed.

Effect of heavy metals on soil nematode communities in the vicinity of a metallurgical factory

The influence of Cu and Zn on soil nematode communities was examined along a pollution gradient with increasing distance from a metallurgical factory. Total and available heavy metal contents were used to study the effects of heavy metals on nematode abundance, trophic groups and ecological indices. The results demonstrated significant correlations between the number of total nematodes, bacterivores, plant-parasites and the total and available heavy metals. Bacterivores and plant-parasites were the dominant trophic groups. Significant differences in different sampling sites were found only in the number of bacterivores（P〈0.01）. The Shannon-Weaver diversity index（W）, trophic diversity index（TD）, evenness index（J＇） and dominance index（λ） were found to be sensitive to soil pH and C/N ratios. Significant correlations were found between the total nematodes （TNEM）, some genera （A crobeloides, Aphelenchoides, Cephalobus, Ditylenchus, Mesorhabditis, Tetylenchus and Tylenchus） and distance from the factory.

Hydrometallurgical purification of metallurgical grade silicon

The effects of the particle size of ground metallurgical grade silicon （MG-Si）, the sort of acids, and the type of stirring on the purified efficiency of MG-Si were investigated. It was found that a particle size less than 0.1 mm was most effective for acid leaching; the extraction yield of impurities was increased by 9% with HF leaching compared with HCl leaching and HNO3 leaching, and increased by 7% with ultrasonic stirring compared with mechanical stirring. The principle of hydrometallurgical purification of metallurgical grade silicon under ultrasonic fields was also discussed.

Kinetics of iron removal from metallurgical grade silicon with pressure leaching

In this paper, the kinetics of pressure leaching for purification of metallurgical grade silicon with hydrochloric acid was investigated. The effects of particle size, temperature, total pressure, and concentration of hydrochloric acid on the kinetics and mechanism of iron removal were studied. It was found that the reaction kinetic model followed the shrinking core model, and the apparent activation energy of the leaching reaction was 46.908 kJ/mol. And the apparent reaction order of iron removal with pressure leaching was 0.899. The kinetic equation was obtained and the mathematical model of iron removal from metallurgical grade silicon （MG-Si） was given as follows：The values calculated from the equation were consistent with the experimental results.

Reviews of Metallurgical Technology to Recovery Platinum Group Metals from Secondary Resource in China

China is extremely poor in mineral resources of Platinum Group Metals (PGMs), productive output of PGMs from mineral resource is 2.5 tons per year. At the same time, China is the biggest PGMs consumption country in the world, the mineral resource of PGMs is critical shortage, it shows the importance of recycling the secondary resource of PGMs. Sino-Platinum Metals Resource (Yimen) Co., Ltd. is the leader in recycling of PGMs from secondary resource, and has made outstanding contributions to China PGMs secondary resources recycling. This article elucidates the current situation of secondary resources recovery and development of metallurgical technology for PGMs.

Review on the study of metallurgical process engineering

After nearly one hundred years of research, metallurgy(metallurgical science and engineering) has gradually become a system with three levels of knowledge:(1) micro metallurgy at the atomic/molecular scale,(2) process metallurgy at the procedure/device, and(3) macrodynamic metallurgy at the full process/process group. Macro-dynamic metallurgy development must eliminate the concept of an "isolated system" and establish concepts of "flow," "process network," and "operating program" to study the "structure–function–efficiency" in the macrodynamic operation of metallurgical manufacturing processes. It means considering "flow" as the ontology and observing dynamic change by"flow" to solve the green and intelligent potential of metallurgical enterprises. Metallurgical process engineering is integrated metallurgy, toplevel designed metallurgy, macro-dynamic operated metallurgy, and engineering science level metallurgy. Metallurgical process engineering is a cross-level, comprehensive, and integrated study of the macro-dynamic operation of manufacturing processes. Metallurgical process engineering studies the physical nature and constitutive characteristics of the dynamic operation of steel manufacturing process, as well as the analysis-optimization of the set of procedure functions, coordination-optimization of the set of procedures' relations, and reconstruction-optimization of the set of procedures in the manufacturing process. The study establishes rules for the macro operation of the manufacturing process, as well as dynamic and precise objectives of engineering design and production operation.

Jet Behavior and Metallurgical Performance of Innovated Double-Parameter Oxygen Lance in BOF

A double-parameter oxygen lance used in a 300 t converter was designed to improve the metallurgical performance. A small-scale measurement of the jet behavior was done using a computer controlled scanning system. The experimental data on the velocity distribution at the jet centerline, the contour map of the jet velocity, the deviation of the jet centerline, and the velocity distribution of the axial section were compiled. According to the results of the small-scale measurement, the double-parameter lance was also employed for a BOF experiment. The metallurgy inde- xes show that the metallurgical performance was highly promoted by use of the double-parameter lance.

Cyclic metallurgical process for extracting V and Cr from vanadium slag: Part Ⅱ. Separation and recovery of Cr from vanadium precipitated solution

Cyclic metallurgical process for separation and recovery of Cr from vanadium precipitated solution by precipitation with PbCO_(3)and leaching with Na_(2)CO_(3)was investigated.The concentration of Cr residue in the solution decreases from 2.360 to 0.001 g/L by adding PbCO_(3)into vanadium precipitated solution according to Pb/Cr molar ratio of 2.5,adjusting the pH to 3.0 and stirring for 180 min at 30℃.Then,the precipitates were leached with hot Na_(2)CO_(3)solution to obtain leaching solution containing Na_(2)CrO_(4)and leaching residue containing PbCO_(3).The leaching efficiency of Cr reaches 96.43%by adding the precipitates into 0.5 mol/L Na_(2)CO_(3)solution with the mass ratio of liquid to solid(L/S)of 10:1 mL/g and stirring for 60 min under pH 9.5 at 70℃.After filtration,leaching residue is reused in Cr precipitation and leaching solution is used to circularly leach the Cr precipitates until Na_(2)CrO_(4)approaches the saturation.Finally,the product of Na_(2)CrO_(4)·4H_(2)O is obtained by evaporation and crystallization of leaching solution.

Effects of SiO_(2) on the preparation and metallurgical properties of acid oxidized pellets

The effects of SiO_(2) content on the preparation process and metallurgical properties of acid oxidized pellets, including compressive strength, reduction, and softening–melting behaviors, were systematically investigated.Mineralogical structures, elemental distribution, and pore size distribution were varied to analyze the mechanism of the effects.The results show that with an increase in SiO_(2) content from 3.51 wt%to 7.18 wt%, compressive strength decreases from 3150 N/pellet to 2100 N/pellet and reducibility decreases from 76.5% to 71.4%.The microstructure showed that pellets with high SiO_(2) content contained more magnetite in the mineralogical structures.Additionally, some liquid phases appeared, which hindered the continuous crystallization of hematite.Also, the softening–melting properties of the pellets clearly deteriorated as the SiO_(2) content increased.With increasing SiO_(2) content, the temperature range of the softening–melting zone decreased, and the maximum differential pressure and the comprehensive permeability index increased significantly.When acid oxidized pellets are used as the raw materials for blast furnace smelting, it should be combined with high basicity sinters to improve the softening–melting behaviors of the comprehensive charge.

Cyclic metallurgical process for extracting Ⅴ and Cr from vanadium slag: Part Ⅰ. Separation and recovery of Ⅴ from chromium-containing vanadate solution

The separation and recovery of V from chromium-containing vanadate solution were investigated by a cyclic metallurgical process including selective precipitation of vanadium,vanadium leaching and preparation of vanadium pentoxide.By adding Ca(OH)_(2) and ball milling,not only the V in the solution can be selectively precipitated,but also the leaching kinetics of the precipitate is significantly improved.The precipitation efficiency of V is 99.59%by adding Ca(OH)_(2) according to Ca/V molar ratio of 1.75:1 into chromium-containing vanadate solution and ball milling for 60 min at room temperature,while the content of Cr in the precipitate is 0.04%.The leaching rate of V reaches 99.35%by adding NaHCO_(3) into water according to NaHCO_(3)/V molar ratio of 2.74:1 to leach V from the precipitate with L/S ratio of 4:1 mL/g and stirring for 60 min at room temperature.The crystals of NH_(4)VO_(3) are obtained by adjusting the leaching solution pH to be 8.0 with CO2 and then adding NH_(4)HCO_(3) according to NH_(4)HCO_(3)/NaVO_(3) molar ratio of 1:1 and stirring for 8 h at room temperature.After filtration,the crystallized solution containing ammonia is reused to leach the precipitate of calcium vanadates,and the leaching efficiency of V is>99%after stirring for 1 h at room temperature.Finally,the product of V_(2)O_(5) with purity of 99.6%is obtained by calcining the crystals at 560℃ for 2 h.

Smart manufacturing of nonferrous metallurgical processes:Review and perspectives

The nonferrous metallurgical(NFM)industry is a cornerstone industry for a nation’s economy.With the development of artificial technologies and high requirements on environment protection,product quality,and production efficiency,the importance of applying smart manufacturing technologies to comprehensively percept production states and intelligently optimize process operations is becoming widely recognized by the industry.As a brief summary of the smart and optimal manufacturing of the NFM industry,this paper first reviews the research progress on some key facets of the operational optimization of NFM processes,including production and management,blending optimization,modeling,process monitoring,optimization,and control.Then,it illustrates the perspectives of smart and optimal manufacturing of the NFM industry.Finally,it discusses the major research directions and challenges of smart and optimal manufacturing for the NFM industry.This paper will lay a foundation for the realization of smart and optimal manufacturing in nonferrous metallurgy in the future.