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The kinetics of colour degradation,chlorophylls and xanthophylls loss in pistachio nuts during roasting process

Food Quality and Safety 2019年第4期3卷 251-263页

作者： Ali Dini Soudeh Khanamani Falahati-pour Khosro Behmaram Nasser Sedaghat Pistachio Safety Research Center Rafsanjan University of Medical SciencesRafsanjanIran Department of Food Science Engineering and TechnologyFaculty of AgriculturalFerdowsi University of Mashhad(FUM)MashhadIran

Objectives:Colour is amongst the parameter which is used for process control during *** and Methods:In this study,the effects of hot air roasting temperature(120,130,145,160,and 170°C)and hot air velocity(0.6,1.3,and 2 m/s)on colour change kinetics of pistachio nuts were investigated by employing image analysis and simultaneously chlorophylls and xanthophylls(lutein andβ-carotenoid)concentration were determined by spectrophotometric measurement ***:We found that roasting temperature and hot air velocity had significant effect on colour *** is a correlation between a-and b-value with chlorophylls and xanthophylls concentration,*** roasting temperature was found to be the main factor affecting colour *** variations in the pigments concentration and colour parameters of pistachio nuts were adequately simulated by quadratic and cubic *** changes in L-,b-values,and xanthophylls degradation were well-fitted to the first-order kinetic model while a-value and chlorophylls degradation followed the zero-order *** activation energy was determined at 113.9,116.7,and 117.2 kJ/mol with R2≥99.9 and 191,195,and 163.2 kJ/mol with R2≥99.5 and 73.7,71.3,and 81.6 kJ/mol with R2≥99.9 for L-,b-,and a-value in hot air velocity of 0.6,1.3,and 2 m/s,***:Activation energy of chlorophylls and xanthophylls degradation were in the range of the activation energy for the yellowness(b-value)and redness(a-value)reactions.

关键词： colour kinetics roasting process pistachio nuts imaging analysis

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Tin recovery from a low-grade tin middling with high Si content and low Fe content by reduction–sulfurization roasting with anthracite coal

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International Journal of Minerals,Metallurgy and Materials 2021年第2期28卷 210-220页

作者： Jing-cheng Wang Lei Li Yong Yu State Key Laboratory of Complex Non-ferrous Metal Resources Clean Utilization Kunming University of Science and TechnologyKunming 650093China Engineering Research Center of Metallurgical Energy Conservation and Emission Reduction of Ministry of Education Kunming University of Science and TechnologyKunming 650093China Faculty of Metallurgical and Energy Engineering Kunming University of Science and TechnologyKunming 650093China

A new method for separating and recovering tin from a low-grade tin middling with high Si content and low Fe content by roasting with anthracite coal was researched by studying the reaction mechanism and performing an industrial test,in which the Sn was sulfurized into SnS(g)and then collected using a dust *** Fe–Sn alloy may be formed at roasting temperatures above 950°C,and like the roasting temperature increases,the Sn content and Sn activity in this Fe–Sn alloy ***,more FeS can be formed at higher temperatures and then the formation of FeO–FeS with a low melting point is promoted,which results in more serious sintering of this low-grade tin *** from the thermodynamics and kinetics points of view,the volatilization of the Sn decreases at extremely high roasting *** results of the industrial test carried out in a coal-fired rotary kiln show that the Sn volatilization rate reaches 89.7%and the Sn is concentrated in the collected dust at a high level,indicating that the Sn can be effectively extracted and recovered from the low-grade tin middling with a high Si content and low Fe content through a reduction–sulfurization roasting process.

关键词： low-grade tin middling tin recovery roasting process Fe-Sn alloy resource recycling

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Pyrometallurgical Removal of Arsenic from Electrostatic Precipitators Dusts of Copper Smelting

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Journal of Minerals and Materials Characterization and Engineering 2021年第6期9卷 545-565页

作者： Hector Henao Ignacio Paredes Rodrigo Diaz Javier Ortiz Metallurgy Engineering Department Technical University Federico Santa María Av. Espa&#241 a 1680 Postal Code 2340000 Valparaíso Chile CODELCO Ministro Hales Division 48739 Antofagasta Chile

This work describes the experimental results of pyrometallurgical removing of arsenic from the dust collected in the electrostatic copper precipitators within the gas cleaning system of a Copper Flash Smelting Furnace. The generation of dust in the copper smelting worldwide ranges from 2 - 15 wt% per ton of a copper concentrate. In Chile, copper smelters produce approximately 110 kt/y of dust with a concentration of arsenic between 1 and 15 wt%. The dust is a complex of metals oxides and sulfurs with copper concentrations greater than 10 wt% and relatively high silver concentrations. Since its high arsenic concentration, it is difficult to recover valuable metals through hydrometallurgical processes or by direct recirculation of the dust in a smelting furnace. Thus, the development of pyrometallurgical processes aimed at reducing the concentration of arsenic in the dust (process of sulfidation-decomposition-oxidation, this work seeks to explore the roasting of mixtures of copper concentrate/dust, sulfur/dust, and pyrrhotite/dust. By the elemental chemical analysis of the mixture after and before the roasting process, the degree of arsenic volatilization was determined. The results indicated the effects of parameters such as roasting temperature, gas flow, gas composition, and the ratio of mixtures (concentrate/dust, sulfur/dust, or pyrrhotite/dust) on the volatilization of arsenic. According to the findings, th

关键词： Copper Smelter Dust Electrostatic Precipitators of Copper Removal of Arsenic Sulfidation roasting process

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Characterization and Pyrometallurgical Removal of Arsenic from Copper Concentrate roasting Dust

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Journal of Minerals and Materials Characterization and Engineering 2021年第6期9卷 609-620页

作者： Hector Henao Ignacio Paredes Rodrigo Diaz Javier Ortiz Metallurgy Engineering Department Technical University Federico Santa María Valparaíso Chile CODELCO Ministro Hales Division Antofagasta Chile

This paper describes the experimental results of removing arsenic from the dust collected in electrostatic precipitators of a fluidized bed roasting furnace (RP dust). The fluidized bed roasting process generates 600 kilotons of copper concentrate per year with 3 - 6 wt% of concentration of arsenic, producing a roasted product with a low content of arsenic below 0.3 wt%. The process generates 27 kilotons of RP dust per year with a concentration of arsenic of the order of 5 wt% and copper concentration of around 20 wt%. Subsequently, the dust collected in the electrostatic precipitators is treated by hydrometallurgical methods allowing the recovery of copper, and the disposition of arsenic as scorodite. This work proposes to use a pyrometallurgy process to the volatilization of arsenic from RP dust. The obtained material can be recirculated in copper smelting furnaces allowing the recovery of valuable metals. The set of experiments carried out in the roasting of the mixture of copper concentrate/RP dust and sulfur/RP dust used different ratios of mixtures, temperatures and roasting times. By different techniques, the characterization of the RP dust determined its size distribution, morphology, and chemical and mineralogical composition. RP dust is a composite material of small particles (roasting experiments indicated that for a 75/25 weight ratio of the mixture of the copper concentrate/PR dust under 700℃, 15 minutes of roasting time with injection of air, the volatilization of arsenic reached 96% by weight. The arsenic concentration after the roasting process is less than 0.3% by weight. For a 5/95 mixture of sulfur/RP dust, at 650℃, the volatilization of arsenic reached a promissory result of 67%. Even that this study was carried out for a particular operation, the results have the potential to be extended to dust produced in the roasting of concen

关键词： Copper Smelter Dust Electrostatic Precipitators of Copper Removal of Arsenic Sulfidation roasting process Fluidized Bed roasting

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