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By John M. Gaines

Lead concentrates from the Viburnum Trend in Southeast Missouri are sintered, prior to smelting, to bind the particles together, homogenize the feed, and reduce the sulfur content. About 20% of the sinter at some plants is classified as bad sinter. A total of 130 samples of good and bad sinters were studied by reflected light microscopy, scanning electron microscopy-energy dispersive analysis, and electron microprobe analysis to characterize their differences in mineralogy and textures. Good sinters consist predominantly of hardysonite, franklinite, lead silicate matrix, and large crystals of calcium-magnesium-iron silicate, together with minor amounts of lead oxides, lead-zinc silicate, metallic lead, specular hematite, magnetite, lead-iron-bearing zincite, and zinc-lead-magnesium-bearing wustite in a tightly intergrown mesh of crystals and with an evenly distributed porosity of about 15-20%. Bad sinters contain larger amounts of lead silicate matrix, galena, metallic lead, and lead oxides, but smaller amounts of hardysonite, franklinite, and calcium-magnesium-iron silicate, lack intimate intergrowth of the phases, and have lower (0-5%) and unevenly distributed porosity.

Jan 1, 1992

By L. A. Mills

After three years of experience in operating the pilot plant for the Noranda Continuous Smelting Process, the decision was made, in March 1971, to build an 800 ton per day commercial plant at Noranda, Quebec. The de- sign and layout of the plant is discussed and the installed equipment described. Experience previously gained in the pilot plant is mentioned when it has been used in the choice of equipment or plant layout. The full- scale reactor was started up in March 1973 and the operational datacollected and the experience acquired during the first 30 months of operation are described. This includes operation to produce both high grade matte and copper. Areas discussed include refractory wear, fuel consumption and throughput of copper concentrates. Changes made to original equipment and methods of operation are discussed, together with the reasons. The ad- vantages of using solid fuels to handle inert materials and to maximize converting air flowrates and concentrate throughputs are described. Relative efficiencies of oil and natural gas are compared. The addition of oxygen from a 94 ton per day oxygen plant to the reactor converting air was started in August 1975 and the initial operating results are included.

Jan 1, 1976

By C. M. F. Vieira

Crushed fired brick waste, known as grog, screened at two different particle size, 840 (20 mesh) and 180 µm (80 mesh), was used in mixtures with clayey body to make typical red ceramics for bricks. The effect of the grog addition up to 20 wt.% on the properties of bricks fired at 700oC was evaluated. The results indicated that both the particle size and the amount of grog addition changed the fired properties of the clayey body. Additions above 5 wt.% of grog, with a coarser particle size, decreased the mechanical strength of both the dry body and the fired ceramic pieces. By contrast, grog with a finer particle size may be used up to 10% wt. without deteriorate the properties and corresponding microstructure of the clayey body.

Jan 1, 2009

By Francis Vanbellen

Umicore Precious Metals Refining operates an integrated precious metals smelting and refining plant in Hoboken, Belgium. Once a smelter and refiner of complex concentrates, the plant today?s feed consists exclusively of industrial and consumer recycled products, making it the world?s largest recycling facility for precious metals. Unlike the fairy tale of the Frog Prince, it took much more than a princess? kiss to successfully realize this makeover. A completely renewed plant has been built over the past decade. The most visible technological innovation was the commissioning of the Pb-Cu smelter. Its flexibility towards very different types of feed makes it perfectly suited as main entry to the Hoboken flow sheet. A new Cu-leaching & electro winning plant and precious metals refinery make up the Precious Metals Operations (PMO) whose targets are fast throughput and maximized yields for gold, silver and the platinum group metals. The Base Metals Operations (BMO), flexibly process the by-products from the PMO, valorizing ?impurities? like indium, tellurium, selenium and others. Off gas and waste water treatments ensure compliance with strict environmental standards. Precious metals recycling is an art that goes beyond mastering a unique flow sheet. Umicore Precious Metals Refining offers a complete recycling service, taking care of sampling and assaying, metals management and logistics. The quality of this integral service is recognized through the attribution of ISO certifications for our operational activities, sampling and the environmental care. And it?s an art that follows Michelangelo?s experience: ?Art is 5% of inspiration and 95% of transpiration.?

Jan 1, 2006

By E. Fockedey

he destruction of free cyanide on a Co3O4 doped carbon felt was studied. The experiments were done with an eiectrochemical filter press cell on dilute alkaline solutions containing 250 mg/l NaCN. No chloride ions were added to the solutions. The cobalt oxide protects the felt against corrosion and has a catalytic effect on the degradation of the cyanide. This kind of electrode allows working with current density as high as 1200 Aim without any visible degradation of the felt. The most interesting results were obtained with a current density of 400 Aim' at which the cyanide concentration can be lowered to 5 mg/l with a current efficiency of more than 70 % and a specific energy consumption of about 10 kWh/ kg CN.

Jan 1, 1998

By P. G. Mason

The Getchell property was mined for oxidized gold ore by underground and open pit methods from 1936 to 194.5, by which time known oxide ores were mined out. From 1945 until 1967 sulfide ores were mined and roasted to improve gold recovery with varying degrees of success. In J 983 FRM Minerals, Inc. purchased the property. Since then they have carried out extensive geological exploration to define the size and character of the orebody. The sulfide ore is refractory to direct cyanidation, thus considerable metallurgical testing has been necessary to develop a suitable, cost effective process for its treatment. Wright Engineercs Limited have designed and engineered a gold extraction plant, which incorporates pressure oxidation to liberate the gold and? is scheduled to be commissioned early in 1989.

Jan 1, 1989

By Hitoshi Iijima, Fumitaka Tsukihashi

"Fine powder of tantalum is used as materials of electric condenser. It is important to control the distribution of particle diameter of tantalum fine powders for the commercial use. In this study, fine powders of tantalum were produced by reducing tantalum chloride vapor with hydrogen gas at 1673 and 1773K. The tantalum chloride vapor was reduced with hydrogen and the produced fine particles of tantalum were collected to observe the distribution of particle diameter. The effects of reaction temperature, partial pressure of hydrogen gas and vaporization temperature of tantalum chloride on the distribution of particle diameter and reaction efficiency of reduction were determined. The mechanism of reduction reaction of tantalum was discussed.IntroductionThe ultra fine powder shows various different physical properties from that of bulk materials. Therefore, the application of ultra fine powder to various fields such as magnetic material, electric material, catalyst, etc is anticipated. The control of shape of powder, size distribution, property of agglomeration, purity is required for the practical use of ultra fine powder. Although the ultra fine powders of ceramics are produced by various methods, the ultra fine powder of metals are produced by the evaporation in gas atmosphere, plasma evaporation process, chemical vapor deposition process, and reduction and precipitation in liquid phase depending on the metal and productivity. The chemical vapor deposition process has features that pure metal powder can be obtained and the control of the distribution of powder size is easy. [1,2,3,4,5]"

Jan 1, 2000

By N. Tsuneyama

Sumitomo Metal Mining Company has been operating Waelz Kiln at the Shisaka Works for 12 years to recover zinc and lead from electric arc furnace (EAF) dust. To increase the capacity and cut down the operating cost, some improvements have been carried out resulting in the capacity of 60,000 t/ y of EAF dust as compared with 32,000 t/ y in 1977. The current capacity is equivalent to 20% or EAF dust generated in Japan. The number of workers has been decreased by the introduction of an automatic control system, and the productivity per worker is now twice as much as 10 years ago. This paper will describe the progress of the operation at the Shisaka Works after the previous? paper reported in "Zinc' 8 5? and summarize the status or EAF dust recycle in Japan.

Jan 1, 1990

By Katsuya Kase, Kaname Takeya, Keaji Ohmori, Yoshiyuki Asakawa

"The reduction-diffusion process (the R-D process) using Ca as a reducing agent has been practiced in industry in the production of the SmCos type, the Nd-Fe-B type and the 1b-Fe-Co type magnetic materials. The advantages of the R-D process are the generally high yield of rare earth metals and the single-stage conversion of a mixture of oxides and metal powders into a product of rare earth alloy powders. On the other hand, one of its disadvantages is the slightly high contents of oxygen and calcium. This disadvantage is remarkable in the Nd-Fe-B type. Singe-phase Nd2Fe14B alloy powders with low content of 0 and Ca, is obtained by choosing appropriate raw materials and performing the R-D process in a controlled way. These alloy powders are very suitable for the production of Nd-Fe-B sintered magnets and expected higher magnetic properties by adopting advanced magnet production method.IntroductionThe hard magnetic rare earth transition metal intermetallics, especially, have attained considerable technical importance. Examples are the alloys based on the intermetallics SmCo5[1], SmC017[2], NchFet4B[3], or the recently developed alloy SnuFe11Nx[4]. The reduction-diffusion process using Ca as a reducing agent has been well known as an economical method of producing rare earth based magnet materials[5]. The reduction-diffusion process has been practiced in industry in the production of the SmCos type, the Nd-Fe-B type and the 1b-Fe-Co type magnetic materials. The advantages of the reduction-diffusion process are the generally high yield of rare earth metals, the single-stage conversion of a mixture of oxides and metal powders into a product of rare earth alloy powders, the elimination of the crushing process of the alloy ingot, the inessentiality to special equipment, etc. On the other hand, one of its disadvantages is the slightly high content of oxygen and calcium. This disadvantage is remarkable in the Nd-Fe-B type. An outline of basic studies of the reduction-diffusion process was reviewed from the particular viewpoint of the production of magnet materials by Ogawa [6]."

Jan 1, 1998

By Onuralp Yucel, Ahmet Turan, Murat Alkan, Hasan Ozer

SHS (Self-propagating High-temperature Synthesis) is one of the important methods to synthesize B4C powders. The process contains the reaction of boron oxide powders (B2O3) with magnesium reducing agent and carbon black carburizer. SHS products are leached in HCl media to purify synthesized B4C powders in the following step. In the present study, effects of various functional additives (KClO3, KHSO4, MgSO4.7H2O, NaCl, MgO and Na2SO4) in the SHS stage were carried out. Various proportions of the additives were mixed with the initial SHS charge mixtures. Two different molar ratios were employed in the initial SHS mixtures as 1:3:0.8 B2O3:Mg:C and 1:2.5:0.8 B2O3:Mg:C. After the SHS step, HCl leaching process was applied to the SHS products. Filter cakes were dried and characterized by using X-Ray Diffraction Spectroscopy, BET and chemical analysis techniques.

Jan 1, 2015

By Mei-le He, Min Chen, Xiang Shen, Lei Xu, Lei Liu, Nan Wang, Xue-liang Yin

In the current study, Al2O3-MgO-CaO refractories were prepared at 1400-1600 by the addition of MnO micro-powders, and the effect of MnO addition on densification behavior of the refractory was discussed. The results showed that the doped MnO dissolved to MgAl2O4 phase, and promoted the growth of MgAl2O4 grains by the formation of MgAl2O4 solid solution. As a result, the dense microstructure was obtained, with the apparent porosity decreased from 19.2% to 5.4% and the bulk density increased from 2.78g/cm3 to 3.15g/cm3 after firing at 1600 for 2h by the addition of 4% MnO. In addition, a texture microstructure was observed, which is considered to be favorable to improve mechanical properties and the service life of Al2O3-MgO-CaO system refractories.

Jan 1, 2016

By Tiejun Chun, Jian Pan, Deqing Zhu, Zhiyong Ruan

"In this paper, the desulfuration of pyrite cinder pellets was carried out. Phase analysis shows that most sulfur of pyrite cinder exists in the form of elementary sulfur. Most sulfur was removed in preheating stage. 81.25% sulfur was removed and the average SO2 concentration of exhaust gas was 1365ppm when the pellets were preheated at 950oC for 9 min. The final product, assaying 62.42wt%Fe and 0.02wt%S content at 96.88% desulfuration was achieved under the conditions of preheating at 950? for 9 min and roasting at 1200? for 15 min, which can be used as the burden for blast furnace.IntroductionPyrite cinder, as a subsidiary product of sulfuric acid production by roasting of pyrite ores, was solid waste in sulfuric acid enterprises. According to the statistics, the annual production of pyrite cinder is about 15 million tons in China. Besides, there is lots of pyrite cinder deposited for many years [1-3]. The pyrite cinder consumed in the cement and other industries as auxiliary additives only accounts for less 30% of its total discharge and the left is stored in waste pond, occupying much land and polluting environment in China [4-5]. Moreover, pyrite cinder contains iron between 30-63% which can be utilized as a cheap raw material for ironmaking by sintering or pelletizing processes, which can not only prevent pollution but also provide cheap raw materials for ironmaking [6-7]. However, compared to traditional iron ore concentrate, pyrite cinder possesses higher sulfur content."

Jan 1, 2012

By Chonghe Li, Xionggang Lu, Wei Xiao, Xingli Zou, Weizhong Ding

The reduction degree and rate of the initial ilmenite concentrate and pre-oxidation samples by hydrogen were investigated by using thermogravimetric analysis system. H2-TPR was used to detected reduction properties of the pre-oxidation products which were oxidized at different temperatures. The phase transformations and micromorphology changes during pre-oxidation and hydrogen reduction were identified by XRD and SEM. The FeTiO3 was decomposed into TiO2 and Fe2O3 at the temperature below 900 oC. With the temperature rising, Fe2TiO5 was the only stable phase in high temperatures. The reduction of pre-oxidation ilmenite concentrate was faster than the natural sample, which was attributed to the micropores generated on the surface of ilmenite concentrate during oxidation. The main phases of the reduction product were metallic iron, ferrous pseuodbrookite.

Jan 1, 2014

By Mingchun Lu, Zhe Wang, Mingming Cao, Xiangdong Xing, Shan Ren, Jianliang Zhang, Zhengjian Liu

"The effect of reduction temperature on the vanadium titano-magnetite carbon composite pellets was investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM), and the discussion has put emphasis upon the enhanced reduction mechanism of additives containing CaF2 and NaF in this paper. The results showed that the reduction temperature of 1350°C was needed for the generation, mergence and growing up of metallic iron as well as monomer dissociation between metallic iron particles and slag phase in the vanadium titano-magnetite metallization pellets. The iron compound was completely reduced into metal iron, and Fe2Ti04 was mainly transformed into metal iron, (Fe,Mg)Ti205 and FeTi03 at 1350°C. The maximum metallization ratio was only 88.5% at 13500 for 30 min without any additive. However, with the addition of 3.0% CaF2 or NaF, the metallization degree of pellets could reach up to 94.8% and 92.5%, respectively.IntroductionVanadium titano-magnetite which is mainly distributed in the area of Panxi, Chengde and Maanshan in China is a kind of complex iron ore which contains various valuable metal elements such as iron, vanadium, titanium, etc. Among the above areas, Panzhihua (Sichuan Province in China) area possesses the largest deposits of vanadium titano-magnetite and the future reserves are more than 100x108t, and the reserves of Ti existing as Ti02 reach to 8.7x108t which occupy over 91% of the whole nation and ranked No.1 in the world[1]. Lots of researches on the comprehensive utilization of vanadium titano-magnetite have been conducted in the world. And many technological processes have been applied successfully in industrial production. Among these processes, the process of rotary kiln-electric furnace is employed to recover iron and vanadium in South-Africa, while the process of blast furnace-rotary furnace is widely used in Russia and China. Besides, many researchers have made efforts on employing new direct reduction process to realize the effective comprehensive utilization of vanadium titano-magnetite[2-4]. However, the direct reduction process is only researched in laboratory and it has not been used in industry."

Jan 1, 2013

By Maria K. Kojo

The interaction between various slags and a nickel concentrate containing pyrite, pentlandite, and violarite were investigated by submerging concentrate pellets in molten slags. The slags were contained in MgO-A12O3 spinel crucibles. The slag oxidizes the iron sulfides in the concentrate, resulting in a nickel matte. The amount of S02 gas formed during reaction was measured to determine the oxidation reactivity of the slags. The experimental variables included temperature, the ferric/ferrous ratio of slag, and other slag properties such as the FeO/SiO2 ratio and the MgO and NiO contents. The reactivity of the slag depended in a complex manner on its oxidizing power, viscosity, and interfacial tension. The slag composition for the greatest reactivity was determined to be Fe3+/Fe2+ = 0.3, Fe/SiO2 = 1.3, and % MgO = 2. This slag, however, caused substantial foaming. Increasing the MgO content to 10% or replacing it by 5% MgO + 8% NiO eliminated at a slight decrease in reactivity. The implications of the findings from this work in the bath smelting of nickel sulfide concentrates are discussed.

Jan 1, 1995

By John C. Carpenter

Solvent extraction is used to selectively recover copper from iron containing sulphate solutions. As chloride ions, which form series of complexes with transition metals, are now being used for leaching. Little is known of the effects of these ions, on solvent extraction behavior. It has been shown that commercial extractants of the L1X and Kelex series extract copper from chloride media: (1) at a lower pH than from sulphate solutions, (2) to similar loadings, and (3) except for L1X 63, without transferring chloride to the organic phase. A process for selective extraction of copper from chloride solutions should thus be compatible with standard stripping and electrowinning practice. Of several diluents, differing in aromaticity, kerosene gave enhanced extraction only with L1X reagents. A change in operating temperature had little effect on equilibrium metal distribution. All the extractants examined gave adequate separation of copper from iron. L1X 63 was found to extract chloro-complexes of copper and of iron and thus transfer chloride to the organic solution. Consequently this extractant and its mixtures are not preferred for use with chloride leaching systems.

Jan 1, 1976

By Naixiang Feng, Shaohu Tao, Zhihui Wang, Yuezhong Di

"A novel vacuum aluminothermic reduction lithium process was developed in present work which used lithium carbonate, alumina and calcium oxide as raw material. The process mainly contained three steps. The first step is that LiA102 clinker is prepared in ambient environment, then metal lithium is vacuum extracted from LiAl02 clinker with aluminum power as reducing agent, and the last step is that alumina is leached from the reduction residue with a mixture of sodium hydroxide and sodium carbonate. The results show that the lithium reduction ratio can be over 95% under the conditions of reduction temperature 1423K, reduction time 3h, and aluminum excess 20%. The main components of reduction residue are CaO· Al203 and 12Ca0·7Alz03. The alumina leaching rate of calcium aluminate in residue is over 80%. High-whiteness aluminum hydroxide can be obtained by carbonation precipitation of the reduction slag leaching solution.IntroductionWith a density about half of water, lithium is with the lowest density of all solids, mere 0.5 g/cm3 at 20 °C [l]. Lithium is widely used in aerospace, aviation, nuclear-generated power and electric battery industry. Nowadays, over 90 % of the world's primary lithium is produced by molten salt electrolysis [2-4]. But the development of molten salt electrolysis will be effected by some factors: cost, environment, and so on. Vacuum thermal reduction may be used extensively in future because of its low-energy consumption, high-purity and short-cycle."

Jan 1, 2013

By Shuqiang Guo, Dingsheng Tan, Weizhong Ding, Zunyu Hu

"The mixture of hydrochloric acid and magnesium chloride is a good lixiviant for leaching of laterite. The solution can enhance the leaching ability because of the proton activity deviated positively from ideal. Otherwise, the existence of magnesium chloride in the lixiviant affects the dissolution behavior of magnesia, which may be an advantage of the process with less hydrochloric acid consumption. An investigation of magnesia particle dissolved in strong hydrochloric acid solution has been conducted. Influences of concentration of the magnesium chloride and hydrochloric acid and temperature on magnesia dissolution were studied. The dissolution mechanism was also discussed in this paper.IntroductionThere has recently been much interest in the use of hydrochloric acid leaching processes for recovering metal from ores or secondary resources [l-41_ Compared with sulfuric acid, the use of hydrochloric acid as lixiviant offers significant advantages including faster leaching kinetics even at atmospheric conditions, higher leaching rate and greater solubility for most metal chlorides [5-61 .With the gradual decline of the nickel sulfide supply, the extraction of nickel from laterites has become increasingly attractive [7-s1. Nickel may be co=ercially recovered from laterites both by pyrometallurgical and hydrometallurgical processes. The drawbacks of pyrometallurgical processes include the requirement of high grade ores, substantial energy input and loss of cobalt bound within ores. The extraction of Ni from lower grade nickel laterites ores is suited by hydrometallurgical routes, which play an increasingly important role with depletion of higher grade deposits."

Jan 1, 2014

By K. V. Sreenivas Rao

Solidification experiments have been conducted to study the effect of interface heat flux and air gap formation on cooling rate of the casting during solidification of Al-4.5wt%Cu alloy. The thermal history of the casting and mold during solidification is recorded using thermocouples connected to computer interfaced data logger. The measured temperatures in the mold are used as input to the IHCP (inverse heat conduction problem) algorithm for simulating multiple heat flux components at the boundary. It is observed that the filling effects induce spatial variation in the thermal field in the mold and casting regions and greatly influence the cooling rate of the casting. The study demonstrates the use of IHCP and in-situ measured thermal profile in analyzing the cooling rate and microstructure.

Jan 1, 2008

By Daniel C. McLean

Extraction data for Cu, Zn and Fe were obtained from 4.5" and 10" columns using massive sulfide ore and natural acid mine water. The purpose was to determine if recycling of solution through the column would produce leach liquors of 4 g/l Cu and Zn at extraction rates of 1 g/l per pass at typical flow rates of 0.002 to 0.006 gpm/sq.ft. Test results exceeded expectations. Cu and Zn concentrations of 4 g/l were obtrained within 4 to 6 cycles. Concentrations greater than 6 g/l Cu and 8 g/l Zn were reached within 10 cycles. Concentrations of greater than 40 g/l of Fe and free sulfuric acid were obtained with no decrease in biological activity being observed. No reagents were used.

Jan 1, 1995