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By Ana E. Bohé, Georgina De Micco, Gastón G. Fouga

"In this work the reaction between several manganese oxides and chlorine is investigated in the range of temperatures between 650 and 950ºC. The reaction path for the chlorination of MnO is established, which involves recrystallization of high valence manganese oxides (Mn3O4 and Mn2O3) followed by its chlorination. For this reason, to understand the reaction of MnO, the chlorination of Mn3O4 and Mn2O3 has also been studied. The starting temperature for the reaction of these oxides is determined by non isothermal thermogravimetric measurements. The effect of temperature is analyzed, under our experimental conditions the rate of reaction is mass transfer controlled. The activation energy for the volatilization of manganese chloride is obtained which is in good agreement with volatilization enthalpy of MnCl2.IntroductionMany oxide ores which have manganese in their composition undergo chlorination processes during the extraction of refractory metals such as Ti, Hf and Nb. Although several works related with chlorination of manganese oxides were reported, there is no information about the kinetics or mechanism of the manganese oxide chlorination reactions. Okahara et al. studied the chlorination of manganese oxides and established that they react easily above 250ºC. Furthermore, they observed that chlorination of high order oxides is more difficult when there is not a reducing agent [1]. Ivashentsev studied the chlorination of manganese oxides using Cl2(g), CO(g) + Cl2(g) and COCl2(g). He established that the reaction of MnO started at 130ºC with formation of MnCl2(s), he also observed recrystallization of manganese sexquioxide [2]. Finally, the chlorination of manganese nodules from the ocean was studied by Murthy and Reddy [3] with the aim of obtaining valuable metals such as Mn, Co, Ni and Cu. They studied the influence of several parameters like temperature, carbon percentage, particle size and chlorine flow rate in the extraction process."

Jan 1, 2008

By G. G. Barbante

Copper anode slimes are a valuable source of the precious metals, and selenium and tellurium. They are mineralogically complex and this has led to a great variety of process flowsheets for treating them. The traditional pyrometallurgical method utilises oxidation in a reverberatory furnace, but has numerous shortcomings. Recently deep-bath intensive smelting methods have been developed for use in the larger refineries. Despite these process advances, the thermodynamics of the reactions involved remains poorly understood. An initial description of the thermodynamics of slimes smelting is presented, but is severely limited by a lack of basic data. It is shown that slimes smelting is superficially similar to copper converting, but has many unique features. More basic thermodynamic data on selenium-based systems are needed before the process model presented can be further refined, and work in this direction has already commenced.

Jan 1, 1994

By Daniel A. Norrgran

Grinding ball fragments discharging from SAG mills and ball mills causes extreme wear to downstream processing equipment. These ball fragments, recirculating in a milling circuit, will cause excessive wear to sumps, pumps, hydrocyclones, and interconnecting piping. A magnetic separation system to remove grinding ball fragments from the mill discharge has been developed and successfully applied in the milling circuit. This magnetic separation system - termed Trammel Magnet - was first applied at the Escondida copper concentrator in Chile. The Trommel Magnet consists of an arc of permanent magnets mounted at the discharge end' of the tommel screen. The magnetic arc attracts the ball fragments and removes them from the process stream. This retrofitted magnetic separation system removed 126 metric tons of ball fragments from the circulating load of a. single ball mill in the initial 24 hour period. The mill has since stabilized and the magnetic separator is currently removing 7 metric tons per day of ball fragments. The retrofit of the Trommel Magnet has: 1. Extended the pumpp life and the hydrocyclone life approximately 300 percent. 2. Provided a 5 percent increase in the throughput of the mills by removing grinding ball fragments that contribute very little to the grinding process. Variations of the Trommel Magnet have also been developed for removing grinding ball fragments directly from the mill discharge without the use of a trommel screen. In each case, permanent magnets are used to collect the ball fragments from the mill discharge stream prior to reporting to the sump. These other systems have been designed and fabricated for in-plant test work.

Jan 1, 1999

By J. Lui

The 15m high Inco flash furnace uptake was designed as a reaction chamber with the objective of destroying the H2S contained in the furnace off-gas by combustion with oxygen at about 1300?C. Until recently, the oxygen required for this purpose was injected through afterburners located at the bottom of the uptake. An undesirable side effect of this practice was the formation of build up accretions on the inside walls of the uptake. This buildup had a negative impact on both the furnace on line time and the control of the flash smelting process. In late 200 I, the afterburners were relocated to the roof of the uptake. As a result, about 80% of the uptake accretion buildup disappeared with obvious beneficial effects for the operation of the furnace. This paper discusses key flash smelting aspects that affect the operation of the flash furnace uptake such as the dusting rate, the formation of H2S in the freeboard of the furnace, and the impact of using coke to supply some of the heat required by the process. The mechanism of buildup formation and its dependence on uptake afterburners location are also examined. Prof. Yazawa's sulfide smelting thermodynamic relationships proved instrumental in understanding the conditions that influence the formation and the elimination ofH2S and uptake buildup.

Jan 1, 2003

By Fuqiang Zheng, Yufeng Guo, Guanzhou Qiu, Tao Jiang, Xiaoming Qu

MxTi3-xO5 is the main titanium-bearing mineral in the titanium-bearing electric furnace slag (TEFS), which is produced by direct reduction-electric furnace smelting process with vanadium titanomagnetite concentrate in Panzhihua-Xichang region of China. In order to effectively utilize the titanium resource in TEFS, the thermomechanical analysis and conditions for the growing up of MxTi3-xO5 grain were investigated, which emphasized on the effects of CaF2 and cooling rate on the crystallization of MxTi3-xO5 in the melting process. The mineral phase and morphology of titanium-bearing slag were determined by XRD and electron microscope technique, respectively. The results indicated that the average grain size of MxTi3-xO5 grown up from 30 to 92 lm and the area fraction of MxTi3-xO5 reached about 66% from 61% under the conditions of 5 wt% CaF2 and cooling rate at 1 °C/min.

Mar 1, 2017

By S. Bagchi

The LaNi5-xMnx-hydrides have potential applications in cryocooling devices for non-mechanical method to compress hydrogen gas. Thermal aging behavior of LaNi5-xMnx-hydrides of compositions x=0.4 and x=1.5 has been investigated. The hydriding properties of the La1.02Ni4.6Mno.4 alloy do not change significantly after thermal aging at 453K for 260 hours. X-ray diffraction analyses of this aged alloy do not reveal the presence of any new phases but the Bragg peaks become broader. Line profile analyses show anisotropic microstrains with an average <e2>1/2 value of -5x103. Thermal aging of the other hydride, LaNi3.5Mn1.5 hydride, at 623K for 280 hours, showed significant disproportionation; the hydrogen capacity reduced significantly from an H/M value of 0.75 in the activated condition to -0.15 after aging. X-ray diffraction analyses showed disproportionated lanthanum dihydride, metallic Ni, and Mn phases. The Bragg peaks were very broad indicative of microstrains or small crystalline domains.

Jan 1, 1997

By S. C. Sharma, M. Krishna, N. Sanmukha

"The oxidation behavior of an aluminium composite with 0, 2, 4, and 6% by weight of hematite at 200 to 500 °C has been investigated. Within the experimental temperature ranges a parabolic weight gain was observed. The, weight gain as a function of oxidation time becomes linear after an initial period on oxidation formation, an oxide scale was found whose morphology depends on temperature, cooling rate and sub-scale formation at the interface between the matrix and reinforcement. The presence of hematite particulate reinforcement has very little effect on the oxidation behavior. The interface oxidization rate was found to be higher than that of other regions. The, oxidation products were either metallic oxides or ceramic oxides. The exposure time of specimens to oxidation was 1000 minutes at various temperatures. In the present work key principles of alloy oxidation were discussed. Also the paper emphasizes various reactions taking ' place and the activation energies involved in the oxidation reactions.IntroductionMetal matrix composites (MMCs) reinforced with ceramic particulate, whiskers, or fibers have received increasing attention due to their potentially high fracture toughness and strength 1-5. Particle reinforced Aluminium MMCs find potential application in several thermal environment, especially in the automobile engine parts, space applications, such as drive shafts, cylinders, pistons, and brake rotors6.With the exception of gold, no metal or alloy is stable at room temperature, they tend to form their respective oxides. Most of the metals in the solid or liquid state are morphologically unstable when exposed to air at higher temperatures. An investigation relating to the temperature profiles of the piston area in a diesel engine has shown that the temperature can reach as high as 500¬800 K in certain regions of the piston. As the piston and cylinder areas are exposed to high temperature environment, the MMCs should have sufficient stability on both mechanical and chemical strength (oxidation). Oxidation occurs at grain boundaries in alloys and at the interface of the particulate and matrix in MMCs, which usually enhances intergranular fracture, resulting in premature failure and severe brittleness 8-10. Therefore for high-temperature applications, it is essential to have a thorough understanding of the oxidation behavior of aluminium MMCs."

Jan 1, 2000

By Patrick R. Taylor

A kinetic study of the fluosilicic acid leaching of galena was performed under the presence of different oxidants. Fluosilicic acid concentration, agitation speed, concentration of solids and particle size, type and concentration of oxidant, and temperature were the variables studied. Hydrogen peroxide was found to be the most effective oxidant, its effectiveness being proportional to its concentration. As expected, an increase of leaching temperature increased the overall extraction and extraction rate. The same was found by decreasing the galena particle size. It is thought that leaching using hydrogen peroxide is controlled by fluid film mass transfer due to the calculated apparent activation energy. Reaction by-products such as sulfur and sulfur compounds retard the leaching rate. A mathematical model is proposed and compared to experimental results.

Jan 1, 2003

By Xiao Hong, Zhang Wenqiang, Gao Bing

The characteristics of top charging coke (coke 1) and stamp charging coke (coke2) were investigated. The weight loss ratios of two kinds of cokes with and without alkalis were measured after reacting with CO under the temperature of 2 900, 1000, 1100 and 1200 °C respectively. The microstructures of original cokes were observed by SEM. The experiment results show that, with no addition of alkali, the weight loss ratios of coke 1 and coke 2 were nearly the same under the temperature of 900 and 1000 °C. While the weight loss ratio of coke 2 was much larger than coke 1 under the temperature of 1200 °C. With alkali-rich, the weight loss ratio of the two cokes was almost the same at 1100–1200 °C.

Mar 1, 2017

By Jin Liu

To improve value metals recovery, a new operating concept for the Inco flash furnace was investigated, in which the flash furnace coke addition practice would aim at establishing a reducing barrier on the surface of the molten bath. The descending partially oxidized sulfide mineral particles would reach the supernatant coke layer prior to the formation of slag. The key for success depends on the effectiveness of the coke layer to produce a sulfur deficient matte while maintaining furnace production capacity. The mechanism and rate of carbon reduction of the phases formed in the flash flame, i.e. sulfide (matte) and oxysulfide was investigated by means of crucible graphite reduction test work. The objective of these tests was to measure the rate of solid graphite reduction of matte, oxysulfide, slag, and matte+slag mixture at different temperatures. These tests were expected to permit understanding and explaining the reduction mechanism of each material by comparing the respective reaction rates, product reaction gas compositions, reduced material assays, and other relevant parameters. Direct visual inspection of the test crucibles would provide additional information.

Jan 1, 2006

By R. C. Hubli

A chemical model has been developed to investigate the dissolution of sulphide minerals in brine solutions containing copper and iron chlorides. The model has been employed to study the dissolution .of synthetic NiS using different initial concentrations of Cu(II), Cu(I), Fe(III) and temperature. The speciation of copper with particular reference to the formation of hydroxy-chlorides as a function of total chloride and H+ has been computed. The model predictions are in agreement with experimental results. It has been found that addition of Fe(III) results in the maintenance of a high Cu(II)/Cu(I) ratio leading to enhanced rates of dissolution and suppresses the loss of Cu(II) due to the formation of hydroxyl-complexes.

Jan 1, 1997

By Guo Xian Jian

In this paper, the gas composition calculations on the FeS-H20 system at elevated temperature were performed. The results show that the gas constituents are H20, S02, H2S, Sj, H2, and O2 and the order of the compositions partial pressure is PH2o> PH2 >PSO2 >PSj >PH2S >PO2 when FeS is oxidized into Fe304 and FeO by steam in the temperature of 700°C -960°C, the Claus process occurs with the decrease of gas temperature in the off-gas and the S02 and H2S in the gas are transformed into Sj , the critical temperature for the transformation is 600°C, and conversion percent of Sj is 97% at 330°C,

Jan 1, 1996

By Philippe Henry

"Hydrometal provides an adequate technology to reintroduce otherwise lost metal units into the industrial cycle, thereby saving resources and energy, while keeping the environment cleaner. Two case studies at an integrated hydrometallurgical recycling facility (Hydrométal) in Belgium are discussed: (I) Residual low quality acid and caustic are used in the processing of zinc industry cements to produce copper, nickel, cobalt and zinc concentrates by several consecutive selective leach - precipitation processes.(II) Copper anode slimes are treated and their precious metal contents are recovered. Depending on the composition of the slimes, separate or combined concentrates of copper, bismuth, tellurium/selenium and silver/precious metals can be produced."

Jan 1, 2008

By Margarete Kalin

Mine abandonment is associated with the securing of access to underground workings, shafts, raises and adits. Waste rock piles and tailings are generally contoured and revegetated. When the waste materials contain pyritic material seepages can often emerge long after the physical reclamation work has been carried out. Their extent and origin has to be delineated to facilitate remedial measures. The depth to which the seepages extended can be determined with an electromagnetic (EM) survey. This paper reports on the experience gained using a winter and a summer EM survey correlated with measurements of specific conductivity at the sediment water interface. Lake sediments and ponds which represent a homogenous background material are good media, where specific conductivity and electromagnetic conductivity can be correlated. The origin of the seepage within the recontoured mine site requires detailed site knowledge, as many anomalies in heterogenous materials such as represented by a mine site are evident.

Jan 1, 1994

By Natasa Mitevska

The statistical analysis of the slag composition influence on copper losses to discard slag in the reverberatory furnaces No.1 and No.2 in the RTB BOR, Copper Smelter and Refinery (Yugoslavia) is presented in this paper. The model for the slag basicity calculation is determined, and connected to the copper distribution coefficients between the matte and slag phase. The influence of all components on the slag structure is also illustrated.

Jan 1, 2003

By Sung-Mo Jung

Experiments were carried out on a system with artificially prepared slags in a graphite crucible, in order to examine the possibility of recycling BOF slags produced in the steelmaking process. More than 80% of FeO and P2O5 was reduced within 20 minutes and the FeO reduction rate was greater than that of P2O5. P2O5 reduction began after more than 60% of FeO was reduced. Increasing slag basicity enhanced the reduction of FeO and P2O5. Temperature also improved slag reduction. The overall reduction rate was controlled by the chemical reaction at the slag/carbon interface. The reduction rates of FeO and P2O5 were second and first order with respect to their respective contents. Most of the reduced phosphorous is believed to vaporize in the form of P2 gas.

Jan 1, 2006

By James Vaughan

Ionic liquids are solvents of interest for applications such as electro- plating, winning and refining of metals. Of particular interest is the possibility of processing reactive metals such as aluminium, magnesium and titanium that cannot be deposited from aqueous solutions. Aluminium has been electro deposited from AlCl3 : ionic liquid mixtures at low temperatures relative to conventional Hall-Héroult smelting. Imidazolium ionic liquids are have been used in the past due to their relatively high ionic conductivity and cation stability. The less studied and less expensive phosphonium ionic liquids systems may provide a viable alternative to imidazolium ionic liquids for certain applications. New information regarding the physical properties and electrochemical behaviour of phosphonium ionic liquid systems is presented.

Jan 1, 2006

By E. V. Redin, B. A. Dubrovsky, E. V. Knyazev, A. I. Starikov

"Ti-V magnetite is one of the most abundant composite ore resources in the world. This ore cannot be fully processed via blast furnace technology because of high content of Ti02. According to the investigations carried out in the USA and Japan ITmk3 RHF (Rotary Hearth Furnace) technology is a breakthrough in Ironmaking. Reduction, melting and slag removal can be achieved in just 10 min. The main objective of the investigation is to establish optimum operation conditions for the production of iron nuggets from Ti-V magnetite ore via the ITmk3 by means of the lab scale testing. Samples of ore from the Maly Kuybas deposit (Southern Ural), carbon reductant and fluxes were chemically analyzed. Green pellets were processed via a lab chamber furnace to simulate RHF conditions. The nuggets and slag were chemically analyzed. This preliminary test work provides valuable information which may be used for large-scale testing in a commercially sized RHF.IntroductionThe ITmk3 process upon which this paper focuses was developed by Kobe Steel in its research facilities [l]. After pilot testing at Kobe Steel's Kakogava Works in 1999-2004 the pilot demonstration plant was built and operations were successfully carried out by Mesabi Nugget joint venture in 2002-2004. Steel Dynamics put into operation the commercial plant at the Mesabi Nugget site in Hoyt Lakes (Minnesota) in 2010. Results were consistent with nugget characteristics confirming ITmk3' s flexibility with respect to raw material inputs. At the same time, no research in the field of nugget from the Ti-V magnetite bearing ore with high content of Ti02 and Alz03 has been done. It is well known, if a lot of Ti02 and Alz03 enter the blast furnace, slag becomes viscous. The viscous slag is obstacle for stable operation of the blast furnace. Besides, high content of Alz03 raises the melting temperature of gangue minerals disturbing the coalescence of reduced iron to the nuggets."

Jan 1, 2013

By Shuichiro Okada

Various efforts to reduce energy consumption and smelting cost are made at Tamano Smelter. Production of anode copper has been increased by about 30 % and energy requirement has been decreased about 50 % respectively. Challenges toward more higher goal are being continued. Details about the following are described in this paper. 1 Waste heat recovery Steam recovery at up-take of FSFE Heat recovery from waste gas of anode furnaces 2 Application of tonnage oxygen 3 Application of pulverized carbonaceous fuels to the flash smelting furnace with furnace electrodes ( FSFE ) 4 Application of computer control system to copper smelting 5 Improvement of the fugitive gas collecting system 6 Improvement of the mechanical tuyere puncher for the converter furnace

Jan 1, 1983

By Supachai Surapunt

The distribution behavior of V A minor elements (As, Sb and Bi) in the smelting stage of the Mitsubishi process were evaluated thermodynamically based on thermodynamic data and operating data. The fractional distributions between the gas, slag and matte phases considered as the degree of vapor saturation of 1.0 are as follows: 53.8, 27.2 and 19% for As, 23.6, 56.6 and 19.8% for Sb, and 91.3, 1.1 and 7.6% for Bi, respectively. Arsenic is mostly distributed to the gas and slag phases. It is effectively eliminated by volatilizing and slagging. Antimony is mainly in the slag phase, which is suitably removed by slagging. Bismuth is easily vaporized to gas phase. The degree of vapor saturation has a large effeet on the distribution behaviors of the three elements between the three phases. The amount of a minor element in the charge has an effect on the distribution of As but no effect on the distributions of Sb and Bi. Increasing matte grade and temperature results in the change of distributions for As and Sb, significantly. The change in the distribution ratio between slag and matte phases also considerably affects the distributions of As and Sb. The distribution behavior of Bi is not significantly changed by the change in matte grade, temperature and distribution ratio.

Jan 1, 2003