Novelty on reduction of raw and pre-oxidised titaniferous magnetite ore with boiler grade coal

Pre-oxidation of fines of magnetite containing materials is usually carried out to get better yield of metals. Titaniferous magnetite ore (TMO) is one kind of low-grade iron ore (around 45–50% of total Fe) with a significant amount of TiO₂ (23.23%) and V₂O₅ (0.403%). TMO fines have been pre-oxidised at 973?K (700°C) for 9?h under air atmosphere. The effect of reduction of raw TMO fines as well as the pre-oxidised TMO fines using boiler grade coal in the form of cylindrical briquettes has been studied in the temperature range of 1273?K (1000°C) to 1473?K (1200°C) for periods of 10, 20, 30, 40 and 60?min to estimate the relative yield of iron. The influence of temperature and time on reduction experiments has also been investigated with XRD, FESEM analyses along with chemical analysis of the reduced samples. The most novel result is that the yield of Fe by direct reduction of raw TMO (92.42%) is even marginally better than that of reduction of pre-oxidised TMO (90.89%) at 1473?K (1200°C) for 60?min. Thus the single-step reduction of raw TMO is techno-economically more viable than the pre-oxidation followed by reduction technique.     

甘肃某含钛磁铁矿选矿试验研究

甘肃某含钛磁铁矿含钛6.58%,含铁21.46%,具有较大的回收价值.在工艺条件试验研究的基础上,采用"弱磁选铁-强磁预富集-钛浮选"的工艺流程回收有价金属,最终,实验室小型闭路试验可获得含铁61.75%,全铁回收率43.45%（磁性铁回收率达86.47%）的铁精矿和含钛50.10%,钛回收率60.23%的钛精矿,浮选作业回收率为85.94%,选别指标较好.      

Development of blast furnace quality pellet optimising blue dust,hard ore and friable ore ratio

Three types of ore fines such as hard ore (HO), blue dust (BD) and friable ore (FO), normally available from a mine show different physical and physicochemical properties. Each of the properties of any individual ore among three may not be suitable to use independently in pelletisation. However, uses of all these three are mandatory. Ores of some poor properties may show other properties excellent. Therefore, any specific poor property of any individual ore can be modified by adding (mixing) other ore which shows that particular property excellent. In order to utilise those three ore fines in pelletisation, mixing of above three ores have been done to get good pellet properties. In industry, the fluctuation in mixing ratio often creates problem in maintaining pellet quality and consistency in spite of maintaining identical basicity and MgO content. Therefore, the required mixing ratio and pellet chemistry has also been optimised in this study. BD, FO and HO has been found to be suitable in the mixing ratio of 70:25:5 with 1.4% MgO. However, with increase in FO beyond 50%, reduction degradation index (RDI) becomes very high (25%). RDI has been decreased to very low level by increasing MgO content from 1.4 to 2% which enables to use FO up to 70% for good quality pellet preparation.     

多金属硫化矿石综合回收铜金银试验研究

对安徽某矿多金属硫化矿石进行了选矿试验研究。试验采用优先浮选铜工艺流程,获得铜精矿品位20.39%,铜回收率83.41%;硫精矿焙烧制酸,硫酸烧渣经氰化炭浸工艺回收金,氰化渣作铁精矿出售。浮选、氰化炭浸金总回收率达89.66%。     

A study on precipitation kinetics of sigma phase in a hot-rolled super duplex stainless steel during isothermal aging based on the Johnson–Mehl–Avrami model

Isothermal aging treatment of 2507 super duplex stainless steel (SDSS2507) was conducted at 850°C after solution treatment at 1150°C. The characteristics of sigma (σ) precipitation kinetics in SDSS2507 were discussed and an improved JMA (Johnson–Mehl–Avrami) model had been developed. The results show that, the precipitation mechanism of σ phase in hot-rolled SDSS2507 was quite different to other ordinary DSSs. It can be found that σ phase precipitated via two mechanisms in this experiment. (1) The eutectoid decomposition δ?→?σ?+?γ₂. It dominated the precipitation kinetics of σ phase in aging 0–25?min, and at this time the volume fraction of σ phase increased rapidly. (2) After 25?min, the precipitation of σ phase absolutely relied on the transformation of γ?→?σ which is controlled by the diffusion of Mo and Ni in γ. In this period, the precipitation rate of σ phase was significantly decreased. In this case, the separate modeling on the basis of each transformation mechanism was adopted and then an improved JMA model was developed for the precipitation kinetics of σ phase in the whole aging process. As a result, a good agreement between the experimental data and this developed JMA model can be obtained.     

College adults are not good at self-regulation: A study on the relationship of self-regulation, note taking, and test taking.

Self-regulation supposedly plays a central role in memory and learning, especially for adults. Research using simple materials has found that adults are skilled self-regulators. Research using difficult materials has found the opposite. Using difficult materials, the authors attempted to improve college students' self-regulation by allowing extended study time before taking a test. The authors also examined whether background knowledge and note-taking strategies would be positively related to self-regulation. Results indicated that college students were not good at self-regulation, background knowledge and note taking were not related to self-regulation, and note taking and background knowledge were generally better predictors of test performance than self-regulation. Results imply that test performance is more related to note taking and background knowledge than to self-regulation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A comparative study on extraction of Fe(III) from chloride leach liquor using TBP, Cyanex 921 and Cyanex 923

A comparative study on extraction of Fe(III) from the HCl leach liquor of low grade iron ore tailings has been carried out using Tri-n-butyl phosphate (TBP), Cyanex 921 and Cyanex 923 in distilled kerosene. The percentage extraction of iron increased with increasing HCl and extractant concentrations. The extracted species in each case was found to be HFeCl₄·S. The extraction isotherms for the above extractants indicated quantitative extraction of Fe(III) in 3-stages at O:A ratio of 3:2 with TBP, and in 2-stages at O:A ratio of 1:1 with Cyanex 921 and Cyanex 923. The stripping studies of the loaded organic phases were carried out with 0.4 M HCl. The stripping isotherms indicated 2-stages at O:A ratio of 5:2 for TBP, and 3-stages at O:A ratio of 2:3 for Cyanex 921 and Cyanex 923. From the extraction studies, the extraction efficiency of the extractants for Fe(III) was in the order TBP < Cyanex 921 < Cyanex 923. Although Cyanex 923 was found to be the best extractant, the percentage stripping of Fe from the loaded Cyanex 923 was the least. The stripping of Cyanex 923 was 94.9%, but with TBP and Cyanex 921, it was 99.8% and > 99.9%, respectively.