Detection of the assimilation characteristics of iron ores: Dynamic resistance measurements

Resistance in iron ore undergoes a sharp change of up to several orders of magnitude when the sintered solid phase changes to liquid phase.In view of the insufficiency of existing assimilation detection methods,a timing-of-assimilation reaction is proposed,which was judged by continuously detecting the changes in resistance at the reaction interface.Effects of pole position and additional amounts of iron ore on assimilation reaction timing were investigated.The results showed that the suitable depth of pole groove was about 2 mm,and there was no obvious impact when the distance of the poles changed from 4 to 6 mm,or the amount of iron ore changed from 0.4 to 0.6 g.The temperature of sudden change of resistance in the temperature-resistant image was considered to be the lowest assimilation temperature of iron ore.The accuracy of this resistance method was clarified by X-ray diffraction,optical microscope,and scanning electron microscope/energy dispersive spectrometer(SEM/EDS)analyses.

A pilot-scale study of selective desulfurization via urea addition in iron ore sintering

The iron ore sintering process is the main source of SO_2 emissions in the iron and steel industry. In our previous research, we proposed a novel technology for reducing SO_2 emissions in the flue gas in the iron ore sintering process by adding urea at a given distance from the sintering grate bar. In this paper, a pilot-scale experiment was carried out in a commercial sintering plant. The results showed that, compared to the SO_2 concentration in flue gas without urea addition, the SO_2 concentration decreased substantially from 694.2 to 108.0 mg/m^3 when 0.10wt% urea was added. NH_3 decomposed by urea reacted with SO_2 to produce（NH_4）_2SO_4, decreasing the SO_2 concentration in the flue gas.

A THEORETICAL DISCUSSION ON TYPES AND MEASUREMENT OF SUSTAINABLE DEVELOPMENT

Classifying the types and measurin g sustainable development are important contents of theoretical studie s on sustainable development.Scient ifically reflecting the characteristics of sustainable development an d favorably classify-ing the types of sustainable develop ment are the basis and objective of me asuring sustainable development.B y using the methods of coordinatively analyzin g man-land relationship and economi c analysis,especially by combining with constant elasticity of substitution(CES)production function,this paper advances average sustainable gross dom estic production(ASGDP),inquires into the mutually coordin ative and interdependent relationship between humane capital and natur al capital in the process of sustainabl e development.It also sets up an index system of measuring sustainable development and a type systemof sustainable deve lopment.then according to this index system,if firstly classifies the s ustainable develop-ment,moderate sustainable develop ment,and strong sustainable develo pment,and it also discuss them theoretical signifi-cance.Secondly,it probes into the minimum cost,structure optimizatio n and sustainable development.At la st,it dis-cuss the type classification of sustainable development on development sequence,and points out theoretically the amount of transitions among 8basic regional sustainable development types is 56.in the process of productive expan sion this transi-tion type embodies the input increase of humane capital is greatly larger than that of natural capital.On the c ontrary,econo-mized humane capital transition is a result of progressively decreasing marginal rate of technical substitu tion of humane capital to natural capital.

The natural history of oviposition on a ginkgophyte fruit from the Middle Jurassic of northeastern China

A distinctive pattern of oviposition lesions occurs on a ginkgoalean seed, Yimaia capituliformis,which likely was inflicted by a kalligrammatid lacewing with a long,sword-like,plant-piercing ovipositor.This newly recorded oviposition type,DT272, occurs in the 165 million-year-old Jiulongshan Formation,of Middle Jurassic age,in Northeastern China.DT272 consists from three to seven,approximately equally spaced lesions with surrounding callus tissue,the fabricator of which targeted fleshy outer and inner tissues ofa ginkgophyte fruit.This distinctive damage also is known from the fleshy attachment pad surfaces of basal bennettitalean bracts.Examination of the life history of this probable ginkgoalean-kalligrammatid oviposition interaction indicates that the spacing of the eggs in substrate tissues disfavored inter-larval contact,but little cart be said of defense and counterdefense strategies between the plant host and the newly hatched imrnatures.

Determination method of high-temperature characteristics of iron-ore sintering based on n(Fe2O3)/n(CaO)

The high-temperature characteristics of iron ores play important roles in optimizing ore proportion of sintering,which are tested by using iron-ore fines and analytical reagent CaO as raw materials.Two calculation methods of CaO addition amount based on binary basicity(basicity method)and n(Fe2O3)/n(CaO)(mole ratio method),respectively,were employed to evaluate the liquid phase fluidity(LPF)and the capability of calcium ferrite formation(CCFF)of iron ores.The results show that the rule of LPF of iron ores under the mole ratio method is different from that with basicity method.The LPF measured by basicity method has a linear positive correlation with the SiO2 content,and there is no linear relationship between LPF and Al2O3 content or mass loss on ignition,which are inconsistent with the results of the previous study.And the results of CCFF with low SiO2 content(<3 wt.%)or high SiO2 content(>7 wt.%)based on basicity method cannot reflect the true CCFF.The mole ratio method could successfully solve this problem by reducing the effect of CaO addition amount changes caused by SiO2 content of iron ores.

Preparation of Chromium-iron Metal Powder from Chromium Slag by Reduction Roasting and Magnetic Separation

Chromium slag（CS）has become one of the most hazardous solid waste containing chromium and iron.Based on its characteristics,the technology of reduction roasting and magnetic separation was employed to treat CS.The major impurity element of CS is magnesium and it exists in magnesium ferrite phase,which is hard to recover iron in the absence of additives.During reduction roasting,additives（Al2O3and CaF2）could destroy the structure of magnesium ferrite and improve the iron grade and recovery.The final product,i.e.chromium-iron powder,contains 72.54% Fe and 13.56% Cr,with the iron recovery of 80.34% and chromium recovery of 80.70%.

Effects of gangue compositions on reduction process of carbonbearing iron ore pellets

The influence of gangue compositions (mainly composed of SiO2,CaO,MgO and Al2O3)on the reduction kinetics of carbon-bearing iron ore pellets was estimated at 1373-1473 K in N2 atmosphere.The results showed that gangue content and each component distribution affected the pellets reduction process.The reduction rate was found to follow a linear correlation with quaternary basicity R4 [mass ratio of (CaO +MgO)to (SIO2 +Al2O3)]of the carbon-beating iron ore pellets;also,the content of SiO2 solid solution in iron oxide had a significant impact on the reduction rate.At the same reduction temperature,a higher R4 resulted in a lower SiO2 free content,weakening its inhibitory effect on the Boudouard reaction.The reduction temperature of Fe2SiO4 could be reduced by increasing the contents of CaO and MgO,improving the iron oxide reduction as well as the precipitation and growth of the iron grains.The g'angue content and .component distribution showed no effect on the rate-controlling step of the reduction;however,the apparent activation energy of reaction decreased with increasing quaternary basicity.When R4 increased from 0.15 to 0.67,the apparent activation energy decreased from 228.51 to 193.66 kJ/mol.

Visualization of collision and aggregation behavior of particles simulating movement of inclusions in molten steel

Inclusions with sizes less than 1 μm in molten steel are difficult to float up to the molten steel and slag interface owing to their slow terminal velocity. Thus, increasing the size of inclusion is essential for accelerating the removal of inclusions. Polystyrene particles simulating inclusions in molten steel were quantified by direct observation of the particle collision behavior in a turbulent flow in a water model. The box-counting fractal dimension of particles was calculated by processing the binary images of aggregated particles. The fractal dimension of the outer contours of the single plastic particles was smaller than that of the aggregated particles. The fractal dimension was varied from 1.14 to 1.35. When two or more monomer particles collide, the aggregates are separated more easily, as the temperature increases from 40 to 80 ℃. The aggregated particles were loose and easy to separate in the high-temperature aqueous solution. The effect of temperature on the surface tension of liquid and the interracial tension of solid and liquid is obvious. The particles are wetting in the water solution at a temperature more than 60 ℃. The relationship between the velocity of the particles and the fractal dimension of the solid particles with the equivalent diameter was discussed.