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.

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.

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.

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.

Mathematical model of metallurgical thermal processes and application

There are lots of physical changes and chemical reactions in the processes of iron and steel making, these processes are quite complex in the aspect of heat transfer.The processes of iron and steel making can be approximately divided into three kinds.The first kinds are the processes of fusion metallurgy which involve enormous chemical reactions,such as blast furnace,converter,electric furnace and coke oven.The second kinds are the processes of heating and cooling which are mainly the physical changes,such as walking-beam reheating furnace,annular heating furnace and car-type furnace.The third kinds are the processes of heat treatment which mainly adjust metallurgical structure of metal,such as roller hearth heat treatment furnace, strip continuous heat treatment vertical/horizontal furnace and HPH bell-type annealing furnace.Every process can only be finished in particular thermal equipment.And all the physical and chemical processes mentioned above must obey first principles of engineering thermodynamics,heat & mass transfer,hydromechanics, combustion,metallurgy physical chemistry etc,and which can be summarized as principle of heat transfer,mass transfer,momentum transfer and chemistry reaction.In this paper,based on first principle of heat and mass transfer in iron and steel making processes,a series of mathematical models of thermal equipments and processes are presented.Such as the model of hot-blast stoves,coke oven,CDQ-boiler system,sintering, reheating furnace,soaking furnace,annular heating furnace,roller hearth heat treatment furnace,strip continuous heat treatment vertical/horizontal furnace,HPH bell-type annealing furnace,control cooling of medium plate,burner,heat exchanger and regenerative burner etc.The on-line application of the model is based on experimental certification of the mathematical model.And finally the computer optimization system of metallurgical thermal process is obtained.

Recent process developments in beneficiation and metallurgy of rare earths:A review

Rare earth elements(REEs)are irreplaceable materials supporting low-carbon technology and equip-ment,and their commercial demand and strategic position are becoming increasingly prominent.With the continuous depletion of rare earth(RE)resources,developing high-efficiency beneficiation and eco-friendly metallurgical processes has attracted widespread attention.This paper reviews the major minerals exploited for RE production and their deposits,as well as the beneficiation and metallurgical processes of RE minerals.Bastnaesite,monazite,mixed RE ores,and ion-adsorption clays are the main raw materials in the world to date.RE-bearing ores(except ion-adsorption minerals)are generally beneficiated by flotation,gravity and magnetic separation techniques.The mainstream metallurgical processes for bastnaesite,monazite and mixed RE concentrates are oxidation roasting-HCl leaching,caustic soda decomposition and high-temperature concentrated sulfuric acid roasting,respectively.Ion-adsorption clays are directly processed by in situ leaching-precipitation/solvent extraction.To achieve the sustainable development of RE resources,it is essential to further explore innovative techniques to achievecomprehensive utilization and cleaner production.

Effect of Fe/SiO2 and CaO/SiO2 mass ratios on metal recovery rate and metal content in slag in oxygen-enriched direct smelting of jamesonite concentrate

The oxygen-enriched direct smelting of jamesonite concentrate was carried out at 1250℃by changing the slag composition.The effects of Fe/SiO2 and Ca O/SiO2 mass ratios on the metal recovery rate as well as metal content in slag were investigated.Experimental results indicated that the metal(Pb+Sb)recovery rate was up to 88.30%,and metal(Pb+Sb)content in slag was below 1 wt.%under the condition of slag composition of 21-22 wt.%Fe,19-20 wt.%SiO2 and 17-18 wt.%Ca O with Fe/SiO2 mass ratio of 1.1:1 and Ca O/SiO2 mass ratio of 0.9:1.The microanalysis of the alloy and slag demonstrated that the main phases in the alloy contained metallic Pb,metallic Sb and a small amount of Cu2 Sb and Fe Sb2 intermetallic compounds.The slag was mainly composed of kirschsteinite and fayalite.Zinc in the raw material was mainly oxidized into the slag phase in the form of zinc oxide.

PLASMA SURFACE ALLOYING OF AGE-HIGH SPEED STEEL

It, ageing high speed steel (AHSS) with high cobalt, has a strong ability of age hardening. However, it has two disadvantages, One is short of toughness, the other is its high price because of its too much alloy content especially cobalt. All of these effect on its widespread using. Now there is a new method without the two flows to form this steel in the surface of ingot iron by use of double glow plasma surface alloying technique.In this paper, the following three parts are introduced: the metallurgical process of this surface ageing high speed steel (SAHSS), the micro structure of the alloying layer, the alloy distribution in the layer. By using the designed source pole, the special alloying process, the required surface alloying content, just like the AHSS—Co23W11Mo7 can be achieved in the surface layer. This new method has wide prospect in the fields of tools, moulds and other wear resisting fields.