钼精矿处理流程中杂质钾的释放机理

通过动力学分析和SEM-EDS、MLA、ICP等分析技术研究钼精矿处理过程中钾释放的动力学特征和机理。结果表明,钼焙砂在水洗和氨浸过程中钾释放的最佳动力学模型均为一级动力学模型,且钾在钼精矿中主要以可溶性钾离子和4种含钾矿物的形式存在。在钼精矿的焙烧过程中,一部分云母分解生成正长石,而另一部分云母则与杂质金属元素结合后形成钡铁云母。此外,快速冷却可有效抑制钼焙砂中云母向正长石的分解转化。研究结果可为降低钼酸铵产品中的钾含量提供依据。

A Modified Model for Calculating Theoretical Flame Temperature in Blast Furnace and Its Application

The theoretical flame temperature （TFT） before tuyere, always highly concerned by blast furnace （BF） operators, is one of the most important parameters for evaluating the thermal state of hearth. However, some influ- encing parameters, for example, the SiO2 reduction by carbon, were always neglected or inaccurate when calculating the TFT. According to the definition of TFT, the temperature of coke into raceway and the reduction rate of SiO2 in ash of coke and pulverized coal were obtained by analyzing the samples before tuyere in blast furnace. Taking full ac- count of different factors, a modified model for calculating the TFT in blast furnace was established. The effects of the oxygen enrichment rate, the reduction rate of SiO2 in raceway, the ash content in coke and pulverized coal and the pulverized coal injection （PCI） rate on TFT were determined quantitatively. The modified model was applied to selecting the used coal for PCI in blast furnace. Considering the different SiO2 contents of mixed coal, the calculated TFT remained a stable level. This showed that the selected coal could be suitable for PCI in blast furnace.

Estimation of Energy Consumption in COREX Process Using a Modified Rist Operating Diagram

Fuel consumption in the COREX-3000 process run in Baosteel is currently higher than the design index. Therefore, mass and heat balance equations for the COREX process were established using the basic principles in- cluded in the Rist operating diagram for blast furnace （BF） as a reference. Thermodynamic calculations were then used to modify the Rist operating diagram so that it was suitable for the COREX process. The modified Rist operating dia- gram was then applied for the evaluation of metallization rate （MR） and fuel structure to reduce the energy consump- tion in the COREX process. The modified Rist operating diagram for the shaft furnace （SF） provided a nearly ideal value for the restriction point W when the metallization rate was increased, while the point P on the operating line for the melter gasifier （MG） moved upward due to reduction in the heat required in hearth. The feasibility of reduc- ing the energy consumption during the COREX process by changing the fuel structure was also demonstrated.

Effect of carbon solution-loss reaction on properties of coke in blast furnace

The pore structure of coke under CO2 atmosphere was investigated by the carbon solution-loss reaction experiment.The results show that the pore size distribution of coke gradually changes from dispersion to relative concentration with the increase in carbon loss rate,but it tends to be dispersed again in the late stage of the reaction,and the pore volume and specific surface area also increase first and then decrease with the increase in carbon loss rate.Scanning electron microscopy results show that the evolution of coke pores is from the formation of micropores to the expansion of micropores,and finally the micropore and mesopores collapse to form a large number of string holes.The chemical bonds and functional groups of different reacted cokes were analyzed by Fourier-transform infrared spectroscopy.Furthermore,the microstructure of reacted cokes was analyzed by optical microscopy,and then the ordering of the affinity of different microstructures with CO2 was given.The volume hypothesis which was the theory about energy size of comminution was adopted to analyze the degradation behavior of reacted cokes.The breakage energy of reacted cokes was calculated by volume hypothesis,and the power consumption coefficient CK of different reacted cokes was determined by drum experiment,and then the degradation behavior of reacted cokes under different power consumptions was predicted.

Analysis of energy consumption for lump coal degradation in melting gasifier

The volume hypothesis,a theory about the energy scale of comminution,was adopted to analyze the degradation behavior of lump coal under different heating time.The breakage energy of chars was determined by a compression test,and the results show that the ultimate strength of chars decreased at the early stage during the heating process,resulting in a decrease of the char breakage energy.At the late stage during the heating process,the char breakage energy increased with the increase of heating time.The power consumption coefficients CKof different chars were determined by a drum experiment,and then the char degradation behavior under different power consumptions was predicted.In addition,agasification experiment was conducted to determine the gasification activation energy（with CO_2）of lump coal heated for different time.The results show that the gasification activation energy increased greatly at the early stage during the heating process,which showed opposite change to the breakage energy of chars.Furthermore,the internal temperature and heat changes of the bonded coal briquette were calculated by using an unsteady heat conduction equation.The large difference between the surface and the center temperatures of coal and the large amount of heat absorption at the early stage during the heating process may have a negative effect on the breakage energy of chars.