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41.
由于微波加热具有加热速度快、反应灵敏、加热均匀、热效率高等优点,近几年在化学、化工和矿业方面的应用正逐渐开展。随着我国对铁矿石资源的需求越来越大,微博能在矿冶领域中潜在的重大作用越来越引起人们的高度重视。结合当前微波应用现状,阐述了微波焙烧在难选铁矿中的研究,重点介绍了微波在赤（褐）铁矿中研究现状,并指出微波在难选铁矿中的发展前景及研究趋势,同时对微波应用的前景进行展望。通过批量生产和技术提升大幅度降低工业用微波源的生产成本,从而降低微波高温设备的制造成本,微波高温设备将取代传统高温设备的市场,逐渐成为主流。 相似文献
42.
天台山碳酸锰矿石,从组分分析,为CaMg[CO_3]_2—CaMn[CO_3]_2类质同象矿石,矿石中碳酸盐矿物的含量较高,二元碱度大于1.3,系中磷低铁碳酸锰贫矿。文章在全面分析矿石组成特征的基础上,介绍了它的焙烧特性。经自燃式竖窑焙烧工业试验,焙烧矿石平均锰品位比入炉矿提高15.09％,Mn/Fe值上升6,P/Mn值降低0.022。工业试验成果通过鉴定,已被生产采用。 相似文献
43.
Grażyna Budryn Ewa Nebesny Joanna Oracz 《International Journal of Food Properties》2013,16(2):290-302
The aim of this study was to determine the effect of different roasting conditions, including temperature, humidity, and roasting air velocity on acrylamide contents in roasted Robusta coffee. In addition, acrylamide concentrations were correlated with the degradation of coffee bean polyphenols and its antioxidant activity. In the process of roasting in a quarter-technological scale apparatus used temperatures ranged from 190 to 216°C. Dry or moist air at a velocity of 0.5 or 1 m s?1 was used. Beans were roasted to achieve optimal sensory properties. The increase of roasting air velocity regardless of its temperature resulted in the intensification of acrylamide formation. The increase of humidity of roasting air caused a reduction of acrylamide formation, but only at the highest used roasting temperature. However, the modification of roasting conditions to achieve a drop in acrylamide concentration resulted in increased degradation of polyphenols and/or deterioration of antioxidant activity. The optimal roasting parameters were: Temperature 203°C, dry air, and low velocity of roasting air. Under these conditions, the roasted beans were characterized by relatively low level of acrylamide and moderate degradation of polyphenols. 相似文献
44.
Coffee beans of Coffea liberica (robusta) variety were roasted using convection and microwave heating. For roasting we used green coffee beans of 7.5% moisture content, and beans wetted to 10% moisture content and dried to 5% moisture content. The content of 5‐hydroxytryptamides of carboxylic acids C‐5‐HT (determined by TLC) as the index of substances irritating alimentary canal was investigated in the roasted beans, depending on the bean treatment before roasting and applied roasting method. Analytical results show that predrying of the coffee beans caused 15–30% loss of C‐5‐HT, depending on the applied drying conditions. The content of C‐5‐HT in the roasted beans depended on the roasting method and preliminary treatment of the beans prior to roasting. A higher C‐5‐HT loss occurred in the case of beans subjected to two‐stage processing, predrying and roasting. Convection roasting caused higher degradation of C‐5‐HT than microwave roasting. 相似文献
45.
As the sulfide ore deposits become less economically viable as a source of nickel, increasing attention is being paid to the nickeliferous laterite ores. However, in contrast to the sulfide ores, these oxide ores cannot be as easily concentrated by current technologies. Consequently, considerable research effort is being directed at developing new techniques for beneficiating the nickeliferous laterites. The pyrometallurgical production of a high-grade ferronickel alloy using a low cost carbonaceous reductant at relatively low temperatures is particularly attractive. In the current research, a thermodynamic model has been developed to aid in the understanding of the carbothermic reduction roasting process as a potential upgrading method for the nickeliferous limonitic laterite ores. The effects of process parameters such as temperature and reductant to ore ratio on the grade of the ferronickel alloy produced and the nickel recovery in the alloy have been studied. The thermodynamic predictions are shown to be in general agreement with the experimental results currently available in the literature. 相似文献
46.
Use of limonitic laterite as an iron source in conventional ironmaking is restricted due to its gangue composition and small particle size. Even direct reduction cannot effectively produce direct reduced iron (DRI) because NiO would be reduced together with iron oxide to form Fe–Ni. A small amount of Ni (about 2 wt.%) in DRI degrades the physical properties of final steel products. The current study investigated how oxidation roasting of limonitic laterite ores affected NiO reduction, with the goal of producing Ni-free DRI and Ni-bearing slag. Ni-bearing slag can be a good secondary Ni resource. Oxidation roasting made NiO inert under H2 reduction at 900 °C by forming Ni-olivine. Optimum roasting temperature was proposed by examining phase transformation of limonitic laterite ores during heating and by FactSage calculation of the equilibrium Ni fraction in Ni-bearing phases. Furthermore, the effect of Mg–silicate forming additives on the control of NiO reducibility was clarified to maximize the suppression of NiO reduction. Among various additives such as MgSiO3, Mg2SiO4 and Fe–Ni smelting slag, Ni-free olivine-typed flux was found to be the most effective form of Ni-olivine because Ni–Mg ion exchange between Ni-bearing phase and Ni-free olivine occurs more readily than other Ni-olivine formation schemes. Finally, the mechanism of Ni-olivine formation during roasting was studied using a diffusion couple test. Calculated diffusivity values of Ni in Mg2SiO4 indicated that the two major routes of Ni-olivine formation while roasting limonitic laterite ore are (1) Ni partitioning within Mg–Ni silicate before crystallization and (2) Ni diffusion from spinel to Ni free olivine after crystallization. 相似文献
47.
阐述了影响煤系硬质高岭土矿用于造纸涂料的主要因素和解决途径,并以四川普格高岭土矿加工利用研究为例,论述了该矿的矿石性质、加工工艺及其特点。通过研究最终获得了高档级涂布原料、中档级涂布原料和造纸填料三种产品,并进行了产品应用试验和技术经济分析。 相似文献
48.
49.
Weiwei Cheng Guoqin Liu Xuede Wang Xinqi Liu Bingge Liu 《Journal of the American Oil Chemists' Society》2015,92(11-12):1725-1733
The main aim of this research was to enhance the understanding of the formation mechanisms of benzo(a)pyrene (BaP) during roasting of sesame seeds (SS). BaP levels in hot‐ and cold‐pressed sesame seed oil (SSO) were evaluated to correlate oil technology and BaP formation. Extracted principal components from SS were roasted either singly or in mixtures at 230 °C for 30 min. BaP was measured by HPLC with fluorescence detection. The results showed that BaP levels in hot‐pressed SSO were significantly higher than those in cold‐pressed SSO (p < 0.05), BaP formation mostly occurred during SS roasting and increased with roasting temperature (between 80 and 280 °C) and time (from 10 to 50 min). Furthermore, the BaP level in the roasted hulled SS (3.64 μg/kg) was higher than it was in roasted whole SS (1.63 μg/kg). The maximum BaP level observed (5.03 μg/kg) was detected in a roasted mixture of SS protein and SSO. The addition of sesame protein to protein‐free SSO promoted the formation of BaP, which suggests that the pyrolysis products of protein and triacylglycerols are probably important precursors in BaP formation. 相似文献
50.
Bo Ling Xuanmin Yang Rui Li Shaojin Wang 《European Journal of Lipid Science and Technology》2016,118(9):1368-1379