Numerical investigation of sinusoidal pulsating gas intake to intensify the gas-slag momentum transfer in the top-blown smelting furnace

The variation characteristics of bubble morphology and the thermal-physical properties of bubble boundary in the top-blown smelting furnace were explored by means of the computational fluid dynamics method.The essential aspects of the fluid phase(e.g.,splashing volume,dead zone of copper slag,and gas penetration depth)were explored together with the effect of sinusoidal pulsating gas intake on the momentum-transfer performance between phases.The results illustrated that two relatively larger vortices and two smaller vortices appear in the bubble waist and below the lance,respectively.The expansion of larger ones as well as the shrinking of smaller ones combine to cause the contraction of the bubble waist.Compared to the results of the case with a fixed gas injection velocity(V_(g)=58 m/s),the splashing volume and dead zone volume of the slag under the V_(g)=58+10sin(2πt)condition are reduced by 24.9%and 23.5%,respectively,where t represents the instant time.Gas penetration depth and slag motion velocity of the latter are 1.03 and 1.31 times high-er than those of the former,respectively.

Clean production of Fe-based amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore and apatite

Separated preparation of prealloys and amorphous alloys results in severe solidification-remelting and beneficial element removal-readdition contradictions,which markedly increase energy consumption and emissions.This study offered a novel strategy for the direct production of FePC amorphous soft magnetic alloys via smelting reduction of high-phosphorus iron ore(HPIO)and apatite.First,the thermodynamic conditions and equilibrium states of the carbothermal reduction reactions in HPIO were calculated,and the element content in reduced alloys was theoretically determined.The phase and structural evolutions,as well as element migration and enrichment behaviors during the smelting reduction of HPIO and Ca_(3)(PO_(4))_(2),were then experimentally verified.The addition of Ca_(3)(PO_(4))_(2)in HPIO contributes to the enrichment of the P element in reduced alloys and the subsequent development of Fe_(3)P and Fe_(2)P phases.The content of P and C elements in the range of 1.52 wt% -14.63 wt% and 0.62 wt% -2.47 wt%,respectively,can be well tailored by adding 0-50 g Ca_(3)(PO_(4))_(2)and controlling the C/O mole ratio of 0.8-1.1,which is highly consistent with the calculated results.These FePC alloys were then successfully formed into amorphous ribbons and rods.The energy consumption of the proposed strategy was estimated to be 2.00×10^(8) kJ/t,which is reduced by 30% when compared with the conventional production process.These results are critical for the comprehensive utilization of mineral resources and pave the way for the clean production of Fe-based amorphous soft magnetic alloys.

The new green smelting process of CNREG commissioned

A demonstration project of the major scientific and technological project in Inner Mongolia Autonomous Region-"Industrialization Test of New Green Smelting Technology for Rare Earth Concentrate produced from Baiyun Obo ore"was commissioned on November 20th.This project adopts the"new green smelting process for rare earth concentrate"independently developed by China Northern Rare Earth Group(CNREG),and has achieved a new breakthrough in rare earth smelting technology.

Risk assessment of heavy metals in soils and vegetables around nonferrous metals mining and smelting sites,Baiyin,China

A field survey was conducted to investigate the metal and arsenic contamination in soils and vegetables on four villages （Shuichuan （SCH）, Beiwan （BWA）, Dongwan （DWA） and Wufe （WFE）） located along, Baiyin, China, and to evaluate the possible health risks to local population through foodchain. Results show that the most significantly contaminated soils occurred upstream at SCH where Cd, Cu and As concentrations exceeded maximum allowable concentrations for Chinese agricultural soil. Further downstream the degree of contamination semi-systematically decreased in concentrations of metal. Generally, the leafy vegetables were more heavily contaminated than non-leafy vegetables. Chinese cabbage is the most severely contaminated, the concentrations of Cd exceeded the maximum permit levels （0.05 mg/kg） by 4.5 times. Bio-accumulate factor also shows that an entry of Cd to food chain plants is the greatest potential. Furthermore, the estimated daily intake amounts of the considered toxic elements （Cd, Pb and Cu） from the vegetables grown at SCH and BWA and DWA have exceeded the recommended dietary allowance levels. Thus, the vegetables grown in three villages above, which affected by Baiyin mining and smelting have a health hazard for human consumption.

COMPUTER MODEL OF COPPER SMELTING PROCESS AND DISTRIBUTION BEHAVIORS OF ACCESSORY ELEMENTS

A computer model has been developed to simulate the distribution behaviors of Ni, Co. Sn. Ph,Zn, As, Sb, Bi, An and Ag in copper smelting process. The model assumes that the copper smelting furnaceis in thermodynamic equilibrium. As many as 21 elements (Cu. S, Fe. Ni, Co. Sn, As, Sb. Bi, Ph. Zn.An. Ag. O, N, C, H, Ca, Mg, Al, and St) and 73 compounds are considered. This model accounts forphysical entrainment in the melts. The predictions by the present computer model are compared with theknown commercial data from Guixi Smelter in China, Home Smelter in Canada and Naoshima Smelter inJapan. The agreements between the computer predictions and the commercial data are excellent, so that thepresent computer model can be used to monitor and optimize the actual industrial operations of copper smelting. It is applicable to simulation of almost all copper pyrometallurgical processes.

Numerical simulation analysis of Guixi copper flash smelting furnace

A numerical simulation analysis for reactions of chalcopyrite and pyriteparticles coupled with momentum, heat and mass transfer between the particle and gas in a flashsmelting furnace is presented. In the simulation, the equations governing the gas flow are solvednumerically by Eular method. The particle phase is introduced into the gas flow by theparti-cle-source-in-cell technique (PSIC). Predictions including the fluid flow field, temperaturefield, concentration field of gas phase and the tracks of particles have been obtained by thenumerical simulation. The visualized results show that the reaction of sulfide particles is almostcompleted in the upper zone of the shaft within 1.5 m far from the central jet distributor (CJD)type concentrate burner. The simulation results are in good agreement with data obtained from aseries of experiments and tests in the plant and the error is less than 2%.

Reductive smelting of spent lead–acid battery colloid sludge in a molten Na_2CO_3 salt

Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.

Effects of smelting parameters on the slag/metal separation behaviors of Hongge vanadium-bearing titanomagnetite metallized pellets obtained from the gas-based direct reduction process

Smelting separations of Hongge vanadium-bearing titanomagnetite metallized pellets（HVTMP）prepared by gas-based direct reduction were investigated,and the effects of smelting parameters on the slag/metal separation behaviors were analyzed.Relevant mechanisms were elucidated using X-ray diffraction analysis,FACTSAGE 7.0 calculations,and scanning electron microscopy observations.The results show that,when the smelting temperature,time,and C/O ratio are increased,the recoveries of V and Cr of HVTMP in pig iron are improved,the recovery of Fe initially increases and subsequently decreases,and the recovery of Ti O_2 in slag decreases.When the smelting Ca O/Si O_2 ratio is increased,the recoveries of Fe,V,and Cr in pig iron increase and the recovery of Ti O_2 in slag initially increases and subsequently decreases.The appropriate smelting separation parameters for HVTMP are as follows：smelting temperature of 1873 K;smelting time of 30–50 min;C/O ratio of 1.25;and Ca O/Si O_2 ratio of 0.50.With these optimized parameters（smelting time：30 min）,the recoveries of Fe,V,Cr,and Ti O_2 are 99.5%,91.24%,92.41%,and 94.86%,respectively.

Relationship between copper content of slag and matte in the SKS copper smelting process

In the newly developed oxygen-enriched bottom-blowing copper smelting process(also known as the SKS copper smelting process), Cu loss in slag is one of the most concerning issues. This paper presents our research results concerning the relationship between the Cu content of the matte and slag in the SKS process; the results are based on actual industrial production in the Dongying Fangyuan copper smelter. The results show that the matte grade strongly influences Cu losses in slag. The dissolved and entrained losses account for 10%–20% and 80%–90% of the total SKS industrial Cu losses in slag, respectively. With increasing matte grade, the dissolved and entrained Cu losses in the SKS slag both increase continuously. When the matte grade is greater than 68%, the content of Cu in the smelting slag increases much more dramatically. To obtain a high direct recovery of copper, the matte grade should be less than 75% in industrial SKS copper production.

Simulation of moving boundary of the reaction shaft in a flash smelting furnace

As to solve the online monitoring of the inner temperatur e and freezing profile of the reaction shaft of flash smelting furnace, simulation of the wall in the reaction shaft in a flash smelting furnace was made through numerical computation. The computational results are very near the data got in s ite. The error of the moving boundary is approximately 3%, and that of the tempe rature is less than 5%. It is proved that the simulation software is applicable for practice to monitor the temperature and moving boundary inside the hearth on line. Based on a large number of the data computed, the relation between the cha nge of the moving boundary and inner temperature is summarized, and the great in fluence of the cooling system on the forming and stability of the moving boundar y inside the hearth is emphasized, which provide the theoretical bases for optim izing the flash smelting operation.

Preparation of CuCr25 alloys through vacuum arc smelting and their properties

CuCr alloys are important contact materials, but all conventional preparing methods have disadvantages and mismatch the requirements for mass production and high properties. The CuCr25 alloys were prepared by means of arc smelting in vacuum, and their microstructures, physical properties as well as dielectric strength were investigated. The experimental results show that vacuum arc smelting is an ideal method to produce CuCr25 contact alloys with fine microstructure, low gas content, high density and dielectric strength. Meanwhile, with the high productivity and low cost, CuCr25 contact materials can be produced with mass production through vacuum arc smelting method.

Influence of operation parameters on flash smelting furnace based on CFD

The influence of three important operation parameters in Jinlong flashsmelting furnace, including the distributing blast speed, the oxygen enrichment rate of process airand the ratio of central oxygen to overall oxygen (O_c/O_o), has been investigated using a virtualsimulation system on copper flash smelting furnace. The core of this virtual simulation system is anumerical simulation of CFD (computational fluid dynamics), and this system incorporates couplingmomentum transport, heat transport, mass transport, reaction kinetics between gas and particles andchemical reactions between gas and gas. A set of numerical predicted data were obtained. The CFDsimulation shows that there is a sensitive zone of the distributing blast speed, and the dustcontent ascends when the speed exceeds 180 m centre dot s^(-1). Increasing the oxygen concentrationof processing air benefits the efficient production of the flash smelting furnace.

Heavy Metal Distribution in Soils near the Almalyk Mining and Smelting Industrial Area,Uzbekistan

The present study demonstrates distribution and chemical forms of heavy metals in soils of the AImalyk mining and smelting industrial area along five transects. The study area is located in Almalyk, Uzbekistan, where the intensification of industrial enterprises negatively impacts the environment. The distribution of 17 heavy metals （Cu, Zn, Pb, Sc, V, Cr, Co, Ni, Ga, Rb, Sr, Y, Zr, Nb, Ba, Th, and U） were studied in 21 sampling locations （21×3=63 soil samples） along five radial transects with a total length of 60 km downwind deposition gradient. Soil samples were collected from the upper layer （0-10 cm） at 4-6 km intervals. As a result of X-ray fluorescence spectrometry analyses by using X -ray fluorescence spectroscopy （XRF, Philips Analytical Ink, USA ）, a significant decrease in heavy metal （Cu, Zn, Pb） deposition was found going from the source in a downwind direction. Soil samples taken from the first location （near the pollution sources） showed higher concentrations of Cu, Zn and Pb, and lower concentrations with increasing distance from the source. Obtained data showed different impact of pollution sources to heavy metal deposition and distribution in soils. The Almalyk mining and smelting complex is the major source of Pb, Zn and Cu enrichment in soils. Distribution of other trace elements does not exceed background content and suggests lithogenic background. This allowed us to divide these elements into two groups： （1） technogenic （Cu, Zn and Pb）; and （2） lithogenic （Sc, V, Cr, Co, Ni, Ga, Rb, Sr, Y, Zr, Nb, Ba, Th and U） origins.

Coordinated control of carbon and oxygen for ultra-low-carbon interstitial-free steel in a smelting process

Low residual-free-oxygen before fmal de-oxidation was beneficial to improving the cleanness of ultra-low-carbon steel. For ultra-low-carbon steel production, the coordinated control of carbon and oxygen is a precondition for achieving low residual oxygen during the Ruhrstahl Heraeus （RH） decarburization process. In this work, we studied the coordinated control of carbon and oxygen for ultra-low-carbon steel during the basic oxygen furnace （BOF） endpoint and RH process using data statistics, multiple linear regressions, and thermodynamics computations. The results showed that the aluminum yield decreased linearly with increasing residual oxygen in liquid steel. When the mass ratio of free oxygen and carbon （[O]/[C]） in liquid steel before RH decarburization was maintained between 1.5 and 2.0 and the carbon range was from 0.030wt% to 0.040wt%, the residual oxygen after RH natural decarburization was low and easily controlled. To satisfy the requirement for RH decarburization, the carbon and free oxygen at the BOF endpoint should be controlled to be between 297 × 10^6 and 400 × 10^-6 and between 574 × 10^-6 and 775 × 10^-6, respectively, with a temperature of 1695 to 1715℃ and a furnace campaign of 1000 to 5000 heats.

Optimization of low-temperature alkaline smelting process of crushed metal enrichment originated from waste printed circuit boards

A novel low-temperature alkaline smelting process is proposed to convert and separate amphoteric metals in crushed metal enrichment originated from waste printed circuit boards. The central composite design was used to optimize the operating parameters,in which mass ratio of Na OH-to-CME, smelting temperature and smelting time were chosen as the variables, and the conversions of amphoteric metals tin, lead, aluminum and zinc were response parameters. Second-order polynomial models of high significance and3 D response surface plots were constructed to show the relationship between the responses and the variables. Optimum area of80%-85% Pb conversion and over 95% Sn conversion was obtained by the overlaid contours at mass ratio of Na OH-to-CME of4.5-5.0, smelting temperature of 653-723 K, smelting time of 90-120 min. The models were validated experimentally in the optimum area, and the results demonstrate that these models are reliable and accurate in predicting the smelting process.

Water model experiments of multiphase mixing in the top-blown smelting process of copper concentrate

We constructed a 1：10 cold water experimental model by geometrically scaling down an Isa smelting furnace. The mixing processes at different liquid heights, lance diameters, lance submersion depths, and gas flow rates were subsequently measured using the conductivity method. A new criterion was proposed to determine the mixing time. On this basis, the quasi-equations of the mixing time as a function of different parameters were established. The parameters of the top-blown smelting process were optimized using high-speed photography. An excessively high gas flow rate or excessively low liquid height would enhance the fluctuation and splashing of liquid in the bath, which is unfavorable for material mixing. Simultaneously increasing the lance diameter and the lance submersion depth would promote the mixing in the bath, thereby improving the smelting efficiency.

Solution behavior of ZnS and ZnO in eutectic Na_2CO_3-NaCl molten salt used for Sb smelting

The solution behavior, including solubility, reactivity and sedimentation, of ZnO and ZnS in a Na_2CO_3-NaCl molten salt used for Sb smelting was investigated in the temperature range of 700-1000 oC. The saturated amount of dissolved ZnO in the molten salt remained constant at 0.02% and was unaffected by temperature; additionally, ZnO did not react with the molten salt. In contrast, the saturated amount of dissolved ZnS in the eutectic molten salt increased with increasing temperature, and the content of ZnS was 0.53% at 1000 oC. In addition, ZnS reacted with Na_2CO_3 above 900 oC to give ZnO. The sedimentation rates of these three species in the molten salt followed the order of Sb>ZnS>ZnO. It was thus concluded that ZnO is an appropriate sulfur-fixing agent for low-temperature Sb smelting in a Na_2CO_3-NaCl molten medium, and that the optimal smelting temperature is below 900 oC.

Effect of diboron trioxide on the crushing strength and smelting mechanism of high-chromium vanadium–titanium magnetite pellets

The effect of diboron trioxide(B_2O_3) on the crushing strength and smelting mechanism of high-chromium vanadium–titanium magnetite pellets was investigated in this work. The main characterization methods were X-ray fluorescence, inductively coupled plasma–atomic emission spectroscopy, mercury injection porosimetry, X-ray diffraction, metallographic microscopy, and scanning electron microscopy–energy-dispersive X-ray spectroscopy. The results showed that the crushing strength increased greatly with increasing B_2O_3 content and that the increase in crushing strength was strongly correlated with a decrease in porosity, the formation of liquid phases, and the growth and recrystallization consolidation of hematite crystalline grains. The smelting properties were measured under simulated blast furnace conditions; the results showed that the smelting properties within a certain B_2O_3 content range were improved and optimized except in the softening stage. The valuable element B was easily transformed to the slag, and this phenomenon became increasingly evident with increasing B_2O_3 content. The formation of Ti(C,N) was mostly avoided, and the slag and melted iron were separated well during smelting with the addition of B_2O_3. The size increase of the melted iron was consistent with the gradual optimization of the dripping characteristics with increasing B_2O_3 content.

Numerical modeling of Jinlong CJD burner copper flash smelting furnace

Fluid flow, heat transfer and combustion in Jinlong CJD concentrate burnerflash smelting furnace have been investigated by numerical modeling and flow visualization. Themodeling is based on the Eulerian approach for the gas flow equations and the Lagrangian approachfor the particles. Interaction between the gas phase and particle phase, such as frictional forces,heat and mass transfer, are included by the addition of sources and sinks. The modeling resultsincluding the fluid flow field, temperature field, concentration field of gas phase and thetrajectories of particles have been obtained. The predicted results are in good agreement with thedata obtained from a series of experiments and tests in the Jinlong Copper Smelter and thetemperature error is less than 20 K.

Study on Foaming Behaviour of Molten Slag during Smelting Reduction with Iron Bath

The molten slag in smelting reduction with iron bath has peculiar behaviour for its high FeO concentration. Slag foaming is effected by the concentration and reduction rate of FeO, basicity of slag and temperature. Addition of granulated coke can greatly decrease slag foaming extent in the process of smelting reduction with iron bath. The anti-foaming capacity of granulated coke is the best when the ratio of coke used for coke layer to total coke used in smelting reduction is controlled at about 20%.