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By A. E. M. Warner

In co Limited has long and extensive experience in converting nickel-copper primary smelting mattes over a broad range of nickel/copper weight ratios and combined nickel-copper-cobalt contents. At the Copper Cliff Smelter, the composition of the converter product matte has to meet the requirements of the matte separation process; at the Thompson Smelter, converter matte of a different composition is cast into anodes for nickel electrorefining; and in Soroako, Indonesia, a very low copper product matte is granulated for the Japanese market. Recently, Inco has conducted pilot plant testing of three possible nickel-copper matte continuous converting routes, namely flash converting, oxygen top blowing-nitrogen bottom stirring, and tuyere blowing. This test work has generated substantial new information on nickel-copper matte converting chemistry. This overview paper reviews the metallurgy of nickel-copper matte converting, in particular the behaviour of cobalt and the operating conditions required to meet the iron and sulfur specifications of the product matte. The relevant thermodynamic information is used to discuss the industrial data.

Jan 1, 2003

By Wei Yu, Tiejun Chun, Jian Pan, Deqing Zhu

In this paper, the technology of producing fluxed pellets by using hydrated lime as binder instead of bentonite was carried out. Green balls with 0.8% bentonite and others with 2% hydrated lime were obtained under the same conditions of 1.5% coke, 1.45 basicity and balling at 8.5% moisture for 13 min in disc pelletizer. The properties of two types green balls were as follows: drop numbers of 4.8 to 5.0 times/0.5m, compressive strength of 19.7 to 24.2 N/pellet and thermal shock temperature of 280 to 385?, respectively. Comparing with bentonite as binder, the compressive strength of fired pellets with hydrated lime is elevated by 13.8% and climbs up to 3113 N/pellet under the following conditions: preheating at 1050? for 10 min and firing at 1300? for 15 min. The hydrated lime also improves the metallurgical performance of fired pellets. The reduction index was enhanced from 68.6% to 70.6%, RDI+3.15 increased from 90.1% to 98.8% and reduction swelling index dropped from 22.4% to 7.4%, respectively. Therefore, hydrated lime can not only replace bentonite as binder to enhance the firing behaviors of green balls, but also effectively improve the metallurgical performance of fluxed pellets which can be used as high quality feed for blast furnace.

Jan 1, 2011

By William Petruk

The concentrator of the Iron Ore Company of Canada consists of spiral circuits, a cone plant and a magnetics plant with regrind. The proportions of liberated and unliberated grains of iron oxides at each point throughout the concentrator were measured by image analysis, and recoveries were calculated for each particle type by the MATBAL materials balancing program. The results show that spirals and cones recover more than 92% of the liberated iron oxide grains in the size range of 848 to 150 um,, but the recovery drops off rapidly for finer grained particles. The tailings from the spirals and cones are reground and low intensity magnetic separators are used to recover liberated magnetite in the -37.5 um size range. The concentrator does not have a unit that efficiently recovers iron oxide grains in the size range of 150 to 37.5 um Consequently about 25% of the iron oxides in the ore are lost to tailings as liberated. grains in the size range of 150 to 37.5 um

Jan 1, 1989

By Kafui Nyavor

Acid mine drainage (AMD) is presently the biggest single environmental problem facing the mining industry. New and expanding metal mines in most parts of the world have to demonstrate their ability to contain this problem to obtain operating permits. Conventional methods of controlling acid mine drainage have primarily been limited to collecting the drainage and neutralizing with alkaline materials which do not provide a permanent solution to the AMD problem. Since acid mine drainage results from the oxidation of sulfides in the presence of oxygen, water and iron-oxidizing bacteria, controlling any of these three factors contributing to pyrite oxidation provides a potential at-source remedy for reducing or preventing acid mine drainage formation. Physical properties such as hydrophobicity also play an important role in the attachment of bacteria, adsorption of oxygen, water, and other ions that subsequently lead to the oxidation of pyrite. In this communication, the suppression of pyrite oxidation by treatment with fatty acid amines (FAA) was investigated. The FAA treated pyrite samples were tested at various conditions of temperature and pressure. At an elevated oxygen pressure of 500 psi and a temperature of 600 C, less than 0.2% oxidation was obtained for the FAA treated pyrite samples, while over 1.2% oxidation was obtained for the untreated samples in 10 hours of oxidation time. Accelerated column oxidation tests at ambient condition showed that FAA mated samples reduced pyrite oxidation by at least 75% in 81 days.

Jan 1, 1994

By Yasuhiro Konishi, Yoshiyuki Noda

"This paper describes a new processing of rare-earth oxide precursor, in which rare-earth carbonate powders are precipitated directly from emulsions of rare-earth loaded carboxylate solutions, using CO2 gas and water. This synthetic route of rare earth carbonate is a combined process of the stripping and precipitation stages in a conventional solvent extraction. Using this technique, lanthanum carbonate and yttrium carbonate were prepared at temperatures of 10 to 80°C and CO2 pressures of 0.1 to 3.0 MPa for 120 min. The rates of carbonate precipitation in a batch autoclave were sensitive to processing parameters such as CO2 pressure, temperature, and organic-phase composition. The particle size distributions of the carbonate powders were markedly dependent on temperature and C02 pressure.IntroductionSolvent extraction is the most appropriate commercial technology for separation and purification of rare earths. In typical commercial processes, the rare earths are stripped from loaded solvent extractants using aqueous solutions of mineral acid. After adjusting the pH of the aqueous strip solution, the rare earths are precipitated as insoluble powders of oxalates or carbonates, from which oxides can be produced by calcination. Such conventional processing can be simplified when the stripping and precipitation stages are combined by emulsifying rare-earth loaded solvent extractant with aqueous oxalic acid solution. It is likely that the single-stage precipitation stripping results in a marked decline in the consumed amounts of precipitating and neutralizing agents, thereby saving on both running and capital costs.Yoon and Doyle1) first demonstrated that oxalate powders of lanthanum and yttrium are directly precipitated from rare-earth loaded carboxylic acid solvent extractant when contacted with aqueous oxalic acid solution at ambient temperature and atmospheric pressure. Yttrium oxalate pow4ers were also prepared by precipitation stripping of di-(2 ethylhexyl) phosphoric acid. (D2EHPA) extractant using oxalic acid-hydrochloric acid solutions. 2) Moreover, neodymium oxalates were directly precipitated from organic solutions of tertiary aliphatic monocarboxylic acid and 2-ethylhexyl phosphonic acid mono-2- ethylhexyl ester using aqueous oxalic acid solutions, and powder characteristics of the resulting oxalates were compared with those of powders by the conventional solvent extraction routes. 3 • 4) Recently, attention has been directed towards the influence of processing parameters on the particle size distributions of yttrium oxalate precipitates. 5)"

Jan 1, 2000

By Zhiqian Zhang, Chao Wu, Chao Li, Hongxu Li, Chuanqi Jiao

"Many used electronic and optical products contain cerium of rare earth oxides, but it is difficult to recover such rare earth compounds by traditional metallurgy methods. The proposed supercritical water metallurgy is a novel way, perhaps it will be very helpful for rare element recycling, but the thermodynamic properties at such special systems is not clear. In the paper the H20-CeO-CeO2 and H2O-CeO2-Ce2O3 ternary system phase diagram were produced under the pressure of30MPa with different temperature of350°C, 375°C and 400°C. The stability existing area of possible cerium compounds and different ions like Ce2+,Ce3+,Ce4+,W,HO2-,0ff ,CeOH2+,CeO+ and CeO2· were determined.IntroductionCerium is an extensively used metal element playing an important role in the rare earth elements. CeO2 is an apparently simple binary oxide with cubic fluorite structure [l]. Ce0O gives rise to a range of important technological applications because of its oxygen storage capacity at moderate temperatures as below: CeO2=CeO2.x+ X/2O2 [2]. The oxygen storage phenomenon gives ceria important technological uses in different fields as automobile exhaust purification catalyst [3-4], fluorescent powder, ultraviolet absorption material [5], polishing powder, fuel cell materials [ 6], and gas sensors, etc. The excellent properties of CeO2 nano powder make its synthesis and preparation become one of the hot spots of world scientists study."

Jan 1, 2013

By Shujian Jia, Mingming Song, Gaoyang Song, Bo Song, Yuhou Yang

An innovative method is investigated to separate inclusion particles from liquid metal by super gravity. To make clear the characteristics of the inclusion separation, Al melt containing MgAl2O4 particles with diameters less than 150 μm has been treated under various super-gravity fields. The thickness of particle-accumulated layer formed at the bottom of the sample and the area fraction, number density and size of inclusions were measured. It is found that the thickness of the particle-accumulated layer decreases and the area fraction of particles at this location increases with the increase of super-gravity field. With the gravity coefficient G=500, time t=2 min, and temperature T=1023 K, it is hardly to find any solid particles in the upper and middle areas of the sample and the separation efficiency is up to 90%.

Jan 1, 2015

By Jana Dobrovska

Solidification and cooling of a continuously cast slab and simultaneous heating of a mould is a very complicated problem of transient heat and mass transfer. Nowadays, the solving of such a problem is impossible without numerical models of the temperature field not only of the slab itself, while it is being processed through the whole concasting machine (Caster), but of the mould as well. Two original numerical models have been developed and used in the investigation of a continuously cast steel slab. The first (one of two) 3D model of the temperature field of a concasting is capable of simulating the temperature field of a caster. Experimental research and data acquisition have to be conducted simultaneously with the numerical computation-not only to confront it with the actual numerical model, but also to make it more accurate throughout the process. After computation, it is possible to obtain the temperatures al each node of the network, and at each time of the process. The utilization of the numerical model of solidification and cooling of a concasting plays an indispensable role in practice. The potential change of technology-on the basis of computation-is constantly guided by the effort to optimize, i.e. to maximize the quality of the process. The user can therefore choose any appropriate longitudinal or cross-section of a slab and display or print the temperature field in a 3D or 20 graph whenever necessary. The second numerical model of dendritic segregation of elements assesses critical points of slabs from the viewpoint of their increased susceptibility to crack and fissure. In order to apply this model, it is necessary to analyze the heterogeneity of samples of the constituent elements (Mn, Si and others) and impurities (P, S and others) in characteristic places of the solidifying slab. The numerical model, based on measurement results obtained by an electron micro-probe, generates distribution curves showing the dendritic segregation of the analyzed element, together with the distribution coefficients of the elements between the liquid and solid states. The combination of both models enables the prediction of cracks and fissures in critical points of the continuously cast carbon-steel slab. Both models had been applied in the industrial investigation of a cast low-carbon-steel slab.

Jan 1, 2003

By E. Oshima

The only one reverberatory furnace smelting in Japan has been alive in Onahama Smelter, Onahama Smelting and Refining Company. The fuel for the reverberatory furnaces had been changed from bunker C-oil to mainly coal and partially waste tires to reduce the energy cost. The steam, recovered by the waste heat boilers of the reverberatory furnaces, has been utilized fully for the power generation to save the purchase power. Copper concentrate has been smelted also by injection through tuyeres in the P.S. converters since 1983. The amount of concentrate, treated in the converters, was increased by the construction of small oxygen plant in December, 1990. In the paper, the current practice and improvements in the reverberatory and converter operations are described.

Jan 1, 1993

Al2O3,-WC Composite powder for cutting tools was synthesized by self-propagating high-temperature synthesis using A1 powder as a reducing agent. WC, W2C and Al2O3 were concurrently formed in WO3Al-C system. It was found that the complete reaction was achieved with excessive addition of carbon and appropriate processing parameters such as degree of dilution, particle size of aluminum, compaction pressures of green pellets and carbon source. The final product which was leached by 50% HN03+HF diluted solution was consisted of Al2O3-55wt% WC having 2-3um of mean particle size.

Jan 1, 1999

By M. J. Collins

A hydrometallurgical process has been tested at the Sherritt Research Centre for separation of zinc, lead, copper and precious metal values from the zinc oxide fume leach residue stockpiled at the HBM&S operations in Flin Flon, Manitoba. Zinc is found primarily as zinc femte and sphalerite in the residue, lead as lead sulphate and jarosite, and copper as sulphide and jarositic compounds. Gypsum and siliceous gangue are significant diluents. The separation process includes hot acid, atmospheric and reducing (sulphur dioxide) leaching; zinc, copper and lead flotation; and atmospheric iron removal steps. Zinc is recovered to a high strength zinc sulphate solution and to a zinc sulphide concentrate suitable for feed to a roaster or to a zinc pressure leach plant; lead to a high grade lead sulphate concentrate suitable for feed to a lead smelter, and copper to a high grade copper sulphide concentrate suitable for feed to a copper smelter. Precious metals are divided between the zinc, lead and copper concentrates.

Jan 1, 1993

By G. G. Krishna Murthy

Several experiments were conducted to determine the rates of heat transfer coefficients of CaO-SiO2-A1203-FeO slags at temperatures in the range 1623-1823 K The experimental technique involved measuring heating rates of a solid specimen, sub¬merged in slag phase, using a temperature probe made of Pt\ 10%Rh-Pt. Effect of %FeO (3-10%), %FeS (0.1-0.68%), %P205 (0.2-3.0%), %MgO(5-6%), and %MnO (0.96-3.84%) present in the slag on overall heat transfer coefficient, U, of slags was investigated. Simple first order heat balance equation in combination with experimental plots rising temperature of solid specimen versus time were employed to determine the values of U. The values of U determined in the present investigation were present in the range of 70-260 cal/Ks.m2. The value of U increased with increasing the slag temperature. The values of U were not effected by increased amounts of sulfur in the slag phase. The increased concentrations of MgO, FeO, MnO, and P205 in the slag phase decreased the values of U. On the other hand, the increased amounts of Fe2O3 in the slag phase increased the value of U. Comparison of the results, obtained using the slag bath stirred by argon injection, with those determined without any stirring indicated that both radiative and conductive heat transfer mechanisms are important even at high temperatures.

Jan 1, 1993

By Rollie E. Dutton, David A. Stubbs

"A sensor has been developed and tested that is capable of emitting and receiving ultrasonic energy at temperatures exceeding 900°C and pressures above 150 MPa. The sensor works with standard ultrasonic pulser-receivers and has demonstrated the capability of measuring workpiece deformation during hot isostatic pressing (HIP). Details of the sensor design, performance, and coupling of the ultrasound to the workpiece are described. Ultrasonic data acquired by the sensor, in situ, during HIP runs and at elevated temperatures in air are presented.INTRODUCTIONHigh temperature structural components, such as structural castings for jet engines, nickel-base superalloy turbine blades, and ceramic and metal matrix composites made from powders are often densified by hot isostatic pressing (HIP). For powder consolidification, the HIP process involves sealing the powder (and reinforcing fibers for composites) within an evacuated ""Can"" made of a material that softens at high temperatures. A hydrostatic pressure is then applied by pressurizing the inside of the HIP vessel with argon gas (up to 140 MPa). The hydrostatic pressure densities the powder through the elimination of the porosity between the powder particles.This paper presents details of the development and preliminary testing of an ultrasonic displacement sensor that can be used to monitor materials processing, in situ, at temperatures and pressures significantly higher than current ultrasonic displacement sensors. The target processing environment for this sensor is that typically found in a hot isostatic pressure (HIP) vessel, i.e., temperatures exceeding 1000°C and pressures above 138 MP a."

Jan 1, 1997

By Youn-Bae Kang

In order to overcome weak points of steel for its engineering applications, in particular, for environmentally benign, energy-efficient, lightweight engineering systems, a number of new steels have been proposed, especially to improve strength-to-weight ratio (specific strength). Mass production of these steels, however, has encountered a serious roadblock particularly in the steel refining and casting processes. This is because their chemistries and cleanliness requirements are vastly different from those of the conventional steels, and thus an incremental improvement of the prevailing process technologies is found hard to meet the requirements. In this study, a new process is proposed, which employs inert gas bubbles in the shroud nozzle, liquid steel drops in the degassing chamber, and the siphon transport for continuous casting. The proposed process which integrates the final refining and cleaning steps prior to casting is expected to be a technologically disruptive innovation on the conventional counterpart. The effectiveness of the individual steps is discussed with experimental results.

By R. Y. Wan, S. L. Chryssoulis

"Gold associations were established in a·biooxidized, chlorinated CIL residue assaying 0.02 oz Ault and in a biooxidized thiosulfate leach residue assaying 0.01 oz Au/t. A detailed mineralogical study involved: assays of screened fractions; light microscopy; ion probe microanalysis to quantify 'invisible' gold in sulfide minerals; proton probe microanalysis to detect and quantify preg-robbed gold. In the CIL residue, most of the gold is preg-robbed (71 %). In the thiosulfate leach residue, gold occurs mainly as submicroscopic disseminations in microcrystalline quartz (chert). In both residues, the 'invisible' gold in pyrite accounts for a minor fraction of the gold assay. Quantitative determination of the gold occurrence in the two residue samples established conclusively that gold adsorption on carbonaceous matter in the thiosulfate leach is of minor importance.Acknowledgement: published with permission of Newmont Gold Company."

Jan 1, 1997

By Bowen Li, Matthew D. Andriese, Jiann-Yang Hwang, Zhiwei Peng

"Magnetic iron sulfide ore particles heat rapidly by microwave (MW) irradiation generating plasma during oxidation of surfaces. The high temperatures produced by the exothermic event decompose local portions of samples forming a differentiated flux of partially melted silicate (si-mt) with entrained metal-sulfide (sul-mt) droplets. The si-mt forms crystals of olivine (01) in Ca-rich pyroxene (Cpx) melt that resorbs a portion of iron sulfide (Po). The immiscible sul-mt droplets of (Fe,Ni,Cu)1-xS contain magnetic subsolidus Ni-pyrrhotite (Ni-Po) with Cr-bearing ferrospinel (Mag). Sub-micron sized flecks of Au are found on the surface of a sul-mt droplet with scanning electron microscope (SEM).IntroductionSulfide ore deposits supply the world's mineral resource in the production of non-ferrous metals. Particularly, Cu-Ni deposits are chemically enriched in metals from high sulfur saturation during magmatic formation that creates the proper geochemical environment for metals enrichment [1, 2]. The sulfur and oxygen fugacity control redox conditions of a differentiated silicate/sulfur magmatic melt with the concentration of iron playing a dominate role in the chemical partitioning of metals in sulfide liquid [3, 4]. The initial magnetic crystallization of (Fe,Ni)i-xS monosulfide solution (mss) from metal-sulfide liquid has an exclusive effect on the fractionation of mineral assemblages (zoning) [5].Phase equilibria of sulfide melt (sul-mt) components are related by a miscibility gap with mss forming Ni-rich pyrrhotite (Ni-Po) followed by the crystallization of (Fe,Cu)1-xS intermediate sulfide solution (iss) [6]. Precious metals form stable chacogenides and are retained in solution until the final liquid solidifies. The redistribution of metals now occurs by subsolidus cooling of mss and iss that exsolve low-temperature Fe-Cu-Ni bearing mineral assemblages [7]. The proper interpretation of ore genesis increases processing capabilities by isolating chemically enriched zones during extraction and should be used to aid in sustainable mine site development [8-11]."

Jan 1, 2013

By T. Innmi

The potential of the nickel matte anode was measured during the matte electrolysis in the commercial cell. The slime layer consists of elemental sulfur and was found to greatly influence the potential of anode. The measurements of porosity and permeability of the slime suggest that the voltage drop of the slime layer dominates the potential. Furthermore, the diffusion of the electrolyte through the slime layer is also one of the factors to determine the potential. In addition, the copper content of the nickel matte anode was found to affect the change in the anode potential during the electrolysis. The role of copper on the anodic dissolution of nickel matte is discussed in this work.

Jan 1, 1988

By Xuling Chen, Zhiyun Ji, Min Gan, Wenqi Li, Xiaohui Fan, Zhiyuan Yu

"Specularite and vanadium-titanomagnetite are difficult to granulate, and with the increase of their proportions, the permeability of sintering bed is deteriorated together with the combustion velocity of fuel for the shortage of air through the sintering bed, which can lower sintering speed and specific production capacity significantly. The biomass fuel has a higher combustion velocity than coke breeze, therefore the productivity of specularite and vanadium-titanomagnetite ore can be improved remarkably by replacing coke breeze partly with biomass fuel .The results showed that, when the proportion of biomass fuel replacing coke is 40%,the sintering speed and specific production capacity of 35% specularite were improved from 19.06mm/min, 1.33 t/(m2·h)to 21.45mm/min, 1.47 t/(m2·h),and that of 55% vanadium-titanomagnetite were improved from 17.23mm/min, 1.11 t/(m2·h)to 22.80mm/min, 1.44 t/(m2·h). As a conclusion, biomass fuel is effective to strengthen sintering of refractory iron ore.IntroductionThe iron and steel industry of our country has achieved significant development in the recent years. In 2010, the output of steel has reached to 0.627 billion tons. The increasing scale of iron and steel has led to rigorous domestic iron ore environment, and the reserves of hematite and magnetite that have superior sintering characteristics are on the decline with continually exploiting and utilizing [1]. Therefore, the RIO (refractory iron ores) SP (specularite) and VT (vanadium-titanomagnetite) have to be applied vastly. However, the quality of sinters can be deteriorated when utilizing RIO in high proportion due to their poor granulation and metallogenic performances [2, 3]. Generally, the ratio of SP is 3~5%,which should not exceed 10% in our country currently [4]. Though high rate of VT is adopted in PZH steel for a long time, the productivity is obviously low compared with normal sintering [5]."

Jan 1, 2012

By Etsuro Shibata

The saturated solubility of chromium oxide and the valence of chromium in the slag are important matters when considering how to effectively utilize chromium-containing slags. The experimental data of various types of slags cited in the literature were arranged according to the optical basicity in order to evaluate the effects of the oxygen potential and the slag composition. The saturated solubility of chromium oxide and the Cr2+/ Cr3+ ratio tend to decrease with the increase of the optical basicity of the slag at an oxygen potential below 10.5 atm. However, at an oxygen potential of 0.21 atm, the saturated solubility and the Cr6+/Cr3+ ratio tend to increase with an increase of the optical basicity. A practical approach was suggested to reduce chromium in the stainless steel slag and simultaneously recover it as a ferroalloy by the direct smelting reduction of chromium oxide in the molten slag using some reductant in a small furnace.

Jan 1, 2003

By Bin Xu, Qian Li, Yong-bin Yang, Tao Jiang, Jian-jun Hu

It could significantly increase the leaching rate of refractory gold concentrate containing sulfur and arsenic by roasting pretreatment with adding certain amount of sodium sulfate, and the mechanism of that was systematically researched with DSC, XRD and SEM in this paper. Results indicated that the mechanism of Na2SO4 on double refractory gold concentrate at roasting pretreatment can be summed up in the following three aspects：Firstly, Na2SO4 can react with SO2 and SO3 which is produced by the oxidation of sulfides and generate Na2S2O7(l), which plays buffer effect on sulfides exothermic oxidation, avoiding the secondary-encapsulated of gold. Secondly, the liquid phase of Na2S2O7 can cover mineral particles' surface that possesses a sintering effect, it leads to internal cracks of the particles. Finally, mineral particles will gather with sodium sulfate particles as the center that can improve the permeability of the layer.

Jan 1, 2015