Reduction of molybdenite with carbon in the presence of lime

Padilla, R.; Ruiz, M.C.; Sohn, Hong Yong

doi:10.1007/s11663-997-0093-4

Cited by 41 publications

(28 citation statements)

References 15 publications

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“…[22] But no similarity was recorded between form Mo per Reaction [4] or its direct reduction-carburizathe C and CO reduction processes of either the sulfide MoS 2 tion to form Mo 2 C per Reaction [2], the product volume is (in the absence of CaO) or the molybdate, CaMoO 4 . Moreinadequate to cover the reactant MoS 2 surface (molar volume ratios of Mo/MoS 2 and Mo 2 C/2MoS 2 are 0.282 and 0.343, over, it is also relevant to observe that the kinetic results of (2) MoO 2 (s) ϩ 0.5O 2 (g) ϭ MoO 3 (s) ⌬GЊ 1200K ϭ Ϫ78.1 kJ mol Ϫ1 , p O 2 ϭ 2 ϫ 10 Ϫ7 atm well as those reported by Padilla et al [27] reported recently.…”

Section: Reactionssupporting

confidence: 72%

Kinetics of the direct synthesis of molycarbide by reduction-carburization of molybdenite in the presence of lime

Prasad

Mankhand

Rao³

et al. 2002

Metall Mater Trans B

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Kinetic studies were conducted on the carbon monoxide reduction of molybdenite in the presence of lime. Contrary to the expectation that the MoS 2 (s) ϩ CaO (s) ϩ CO (g) reaction will result in metal formation, molycarbide was found to form and no Mo was detected in the product. This is explained on the basis of thermochemical considerations, which indicate that the Mo 2 C formation is more feasible by eight orders of magnitude. The effects of quantity of lime in the charge, CO flow rate, temperature (1123 to 1298 K), and time of reduction have been studied. Kinetic analysis reveals that the results on the MoS 2 (s) conversion to Mo 2 C (s) fit into a modified parabolic rate law. Based on the thermochemical calculations and experimental findings, the probable reaction scheme has been identified. Molycarbide appears to form by a three-successive solid-gas reaction path consisting of (1) metal formation by the MoS 2 (s) ϩ CO (g) reaction followed by (2) in-situ carburization of Mo metal by CO (g), and finally (3) the scavenging of the COS (g) by lime, resulting in CaS (s). The latter two reactions drive the overall reaction forward. Further, out of these three consecutive reactions, progress of the overall MoS 2 ϩ CaO ϩ CO reaction seems to be governed by the intrinsic kinetics of the first one. Calcium molybdate, which forms as a transitory phase, plays a significant role by modifying the linear kinetics of the MoS 2 (s) ϩ CO (g) to one of parabolic nature.

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Section: Reactionssupporting

confidence: 72%

Kinetics of the direct synthesis of molycarbide by reduction-carburization of molybdenite in the presence of lime

Prasad

Mankhand

Rao³

et al. 2002

Metall Mater Trans B

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“…La reacción global, según lo estudiado por PADILLA et al [4], que gobierna la tostación con reducción carbotérmica en presencia de oxígeno se detalla en la ecuación 2. En ella se muestra un agente captador de azufre, siendo el CaO y el agente reductor como el C.…”

Section: Introductionunclassified

Uso de procesos pirometalúrgicas para la obtención de renio

2018

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RESUMENEl renio es un metal que presenta distintos métodos de obtención.El más utilizado es el que se lleva a cabo por la tostación de la molibdenita. En él se aplican métodos pirometalúrgicos tradicionales como es tostación oxidante, pero también existen métodos pirometalúrgicos innovadores como la tostación con reducción carbotérmica.En este trabajo se estudia el comportamiento que presenta el renio frente al uso de diferentes tostaciones, ellas son tostación oxidante y tostación con reducción carbotérmica. El objetivo es comparar ambos tratamientos discutiendo los valores de recuperación de renio.La tostación oxidante es un método que genera importantes emanaciones de SO 2 al medio ambiente, cuando se aplica a sulfuros metálicos. En cambio, la reducción carbotérmica es un proceso que utiliza el CaO como agente captador de azufre y elC como reductor, junto al sulfuro metálico, eliminando de esta manera la contaminación de la atmósfera que había sido producida por el SO 2 . Con tal fin, se estudió la relación molar de CaO óptima con respecto al Re y C, requerida para acelerar la velocidad de reducción y controlar la emisión de S a la atmosfera. De esta manera se determinan la dependencia del sulfuro metálico con los factores operacionales de temperatura de tostación, concentraciones molares y tiempos de tostación.Por otro lado, en la tostación oxidante se trabajó con las variables operativas de temperatura y tiempos de tostación para determinadas condiciones atmosféricas.En base a los resultados obtenidos de ambas tostaciones se determinaron las condiciones óptimas de las operaciones para la mayor recuperación de Re.Palabras clave: renio, tostación, reducción carbotérmica. ABSTRACTRhenium is a metal that has different obtainment methods. The most used comes from molybdenite roasting. Traditional pyrometallurgical methods like oxidizing roasting are applied, but there are also innovative pyrometallurgical methods as is roasting with carbothermic reduction. This paper presents the behavior of rhenium onto two different roasting processes: oxidizing roasting and toasting with carbothermic reduction. The purpose is to compare both treatments discussing rhenium recovery values.Oxidizing roasting generates several SO 2 emissions towards the environment when it is applied to metal sulphides. The carbothermal reduction is a process that uses CaO as sulfur capturer and C as a reductant agent, and eliminates the atmosphere pollution that would have been caused by SO 2 . Thus the

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“…Several studies have been reported in the past which were concerned with the use of various reducing agents, namely hydrogen, carbon monoxide and carbon for the reduction of metal sulfide, using mainly CaO and CaC03 for sulfur capture. These studies included the direct reduction of copper, zinc, nickel, lead, and molybdenum sulfides [3][4][5][6][7][8][9][10][11][12][13][14],…”

Section: Introductionmentioning

confidence: 99%

Antimony production by carbothermic reduction of stibnite in the presence of lime

Padilla

Chambi

Ruiz

2014

J min metall B Metall

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Experimental work on the carbothermic reduction ofSb,S3 in the presence o f lime was carried out in the temperature range o f 973 to 1123 K to produce antimony in an environmentally friendly manner. The results demonstrated the technical feasibility o f producing antimony by this method without producing SO, gas. Complete conversion o f Sb,S3 was obtained at 1023 K in about 1000 seconds and at 1123 K in less than 250 seconds using stibnite-carbon-lime mixtures with molar ratios Sbfi.:CaO:C = 1:3:3. It was found that the reduction proceeds through the formation o f an intermediate oxide SbO" which is subsequently reduced by CO(g) to yield antimony metal and CaS. The kinetics o f the SbJS3 reduction was analyzed by using the equation In(l-X) = -kt. The activation energy was 233 kJ mol'1 in the temperature range o f 973 to 1123 K. This value would correspond to an antimony catalyzed carbon oxidation by CO,.

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Reduction of molybdenite with carbon in the presence of lime

Cited by 41 publications

References 15 publications

Kinetics of the direct synthesis of molycarbide by reduction-carburization of molybdenite in the presence of lime

Kinetics of the direct synthesis of molycarbide by reduction-carburization of molybdenite in the presence of lime

Uso de procesos pirometalúrgicas para la obtención de renio

Antimony production by carbothermic reduction of stibnite in the presence of lime

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