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"Mineral flotation processes are often characterized by long dead times and slow process dynamics. The process dynamics change due to different ore types, feed grades and circulating loads. These are some of the factors that can make control of flotation processes difficult. Implementation of adaptive control algorithms at Brunswick Mining has made controlling these processes feasible. The role of adaptive controllers in plant optimization and the overall control philosophy is discussed.IntroductionBrunswick Mining is located just outside of Bathurst, New Brunswick, Canada. The concentrator processes approximately 10,250 tonnes per day of ore that assays at approximately 8.9 %Zn, 3.6 %Pb, 0.3 %Cu and 100 gram/tonne of Ag. The four products produced are zinc concentrate assaying 51 %Zn, lead concentrate assaying 36 %Pb, copper concentrate assaying 21 %Cu, and a bulk concentrate assaying 32 %Zn and 18 %Pb.The original flotation process control system, supplied by Outokompu Oy of Finland, was replaced in the summer of 1988 by a Provox system supplied by Fisher Controls Inc. The Provox system consists of two redundant integrated function controllers (IFC's), two operator console stations with two screens each and a Digital Equipment Co. microVax II computer running Fisher's Computer Highway Interface Package (CHIP).In January 1989 a boiler management package, which includes the boiler control hardware and another operator's console, will be added to the Provox system. In late spring of 1989, a Vax 3200 computer running G2 artificial intelligence software from Gensym Corporation will be installed. These devices are all connected using a redundant data highway that runs around the plant.The primary measurement devices in the flotation circuit are two Courier on-stream X-ray analyzers. The Courier systems each have 14 sample cells with two streams multiplexed into each cell. Each pass of the on-stream head takes approximately 6 minutes yielding a nominal sampling interval of 12 minutes. The Courier passes its assays to its respective IFC. The IFC handles the digital and analog I/O, DDC and cascade loop control, some low level calculations and sequencing. The CHIP microVax has 9MB of memory and 220MB of mass storage running under the VMS operating system. The CHIP microVax is a central database for the Provox system. It is used for data trending, metallurgical modelling and balancing, instrumentation database, long term storage, and on-line adaptive assay control."

Jan 1, 1989

By Qingyu Deng, Shiwei Ma, Guibao Qiu, Hua Wang

"The flow behavior of the blast furnace slag bearing titanium, like viscosity, play an importance role during the iron-making process with the vanadium-titanium magnetite, which is a very special minerals in Panzhihua, China. The dependency of the viscosity on the chemical composition like TiO2, Al2O3, MgO, binary basicity (CaO/SiO2), temperature, reaction time were studied. The experiments showed that the viscosity decreased with the increase of TiO2, MgO content and binary basicity, and it increased with the increase of Al2O3 content and temperature. The viscosity showed a slight decrease within 60mins’ reaction with graphite crucible, however, it increased rapidly afterwards with the formation of Ti(C, N).IntroductionThe ordinary iron ore has been an essential part of raw materials for vanadium-titanium magnetite smelting in Panzhihua to avoid a series of problems, such as slag thickening, adhesive bond of slag and hot metal, etc. The ratio of vanadium-titanium magnetite has been decreased gradually since 1970s, and has down to about 65% now. However, with the substantial appreciation of price of imported ordinary iron ore, Panzhihua Iron and Steel Group aims to increase the ratio of vanadium-titanium magnetite and decrease the dependence on ordinary iron ore in order to lower the cost of smelting process."

Jan 1, 2012

By S. Y. Tan

The thermal stability of fully silicided NiSi with arsenic doping on silicon was investigated. The aims of the work were to investigate the Ni silicide phase-related issues associated with arsenic dopant and thermal annealing on Ni-FUSI/HfO2/Si and Ni-FUSI/HfSiO/Si gate stacks. It was found that arsenic-incorporation demonstrated some improvement in both morphology and phase stability of nickel silicided films at high processing temperatures regardless underlying gate dielectrics. The correlations of Ni-Si phase transformation and arsenic doapnt with their electrical and physical changes were established by sheet resistance measurements, X-ray diffraction (XRD), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS) analysis. Furthermore, the modulation of the work function (WF) of Ni fully silicided gates by arsenic impurity is presented, comparing the effects of dopant (As) on the WF and silicide phases (NiSi and NiSi2). It confirmed that the work function of NiSi can be tuned by implanting arsenic dopant, but it ineffective for NiSi2 phase.

Jan 1, 2010

By Yunyan Wang

Diagrams of pc-pH for the complex ions concentration and pH value and -g- for activity coefficient and ionic strength ln±MnSOI4had been drew based on the thermodynamic principle of coordination chemistry and combined with Pitzer theory at 298.15K. The diagram of -g- indicated that -gincreased sharply from 0.0000 up to 1.2147 when I changed from 0.00 ln±MnSOIln4±MnSO4to 0.09; The increase of -gbecame slowly when I was more than 1.00 and less than 1.69; kept still when I ln±MnSOln4-g±MnSO4was more than 2.25 and less than 4.00. Diagrams of pc-pH illustrated that the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pc increased from 6.5 to 5.5 when I increased from 0.00 to 4.00; The pH of the minimum solubility of Mn(OH)2(s) increased with the increase of I, the pH increased from 11.80 to 12.76 when I increased from 0.00 to 2.89, the pH kept still when I (I was less than 4.0) increased. There is single function relationship between the minimum solubility of Mn(OH)2(s) and relevant pH in different I.

Jan 1, 2010

By W. Petruk

A study was performed to determine whether mineral textures affect are breakage during grinding, and to establish a correlation between are breakage and mineral liberation. A base metal are from the Brunswick No. 12 deposit in New Brunswick, Canada was ground for different periods of time in a laboratory ball mill, and both the unbroken are and the ground products were studied by image analysis. Similar size distributions were obtained for material from the 15-minute grind in a laboratory ball mill (K. 0 67 pm), for the grinding circuit discharge from a commercial mill (K. 0 = 59-72 pm), and for pyrite grains in unbroken are (K,. = 74 pm). This similarity indicates that the 1S-minute grind separated weakly adhering pyrite grains along grain boundaries, and represents the limit of easy breakage for the are. At this grind (15 minutes) large discrete are mineral grains and weakly adhering interstitial fillings aIrong pyrite were liberated. On the other hand, the 15-minute grind neither separated rooderately bonded pyrite grains nor released rooderate1y bonded interstitial minerals from pyritei a 45-minute grind (K.. 31 pm) in a laboratory ball mill was required. For Brunswick No. 12 are, a 45-minute grind in a laboratory ball mill (Keo = 31 pm) is equivalent to regrinding in a commercial mill (K ?? Fl:$ 30 pm). Grinding beyond 45 minutes in the laboratory ball mill broke the are by fracturing pyrite across grain boundaries and by Chipping grain edges. Such intense grinding (longer than 45 minutes) did not markedly increase sphalerite liberation. In contrast, the intense grinding increased galena liberation because a significant proportion of the galena occurs as minute inclusions in pyrite. These findings show that ore breakage and coincident liberation depend upon size distributions, intergrowths, and mode of occurrence of the minerals in an ore.

Jan 1, 1988

By Robert D. Pehlke

"Current continuous casting processes are going through a rapid evolution of advances and new developments. At the same time, intense efforts are being directed to the development of radical new technologies such as continuous casting of thin slabs and strip steel.Traditionally, the casting processes for steel have been anticipated by the development and implementation of processes in the non-ferrous industry. This trend is reviewed and what it may portend for steel is described.IntroductionThe continuous casting of steel has been a widely adopted process in the production of steel. The concepts for this processing go back into the early and mid 1800's; however, commerical development was delayed for a variety of reasons until the mid twentieth century.Beginning in the early 1960's, adoption of continuous casting was initiated and continues at this point in time to be accelerated. In Japan, more than 90% of the steel produced is continuously cast (1). More than 50% of the steel produced in the United States is continuously cast and this fraction continues to rise (2). Numerous examples can be cited of installations costing well over $200,000,000 which have provided a payoff in less than a year and a half. As this process has continued to be applied and its technology to increase, computer control systems have been installed. In particular, in the larger plants producing slabs, sophisticated computer systems involving the integration and networking of mini-computers, micro-computers, and mainframe including back-up systems at all levels are being utilized. Pehlke (3), and Harabuchi and Pehlke (4) have described the structure of these systems."

Jan 1, 1988

By T. T. Chen

Gold in the Twin Creeks ore is primarily associated with arsenian pyrite. During pressure oxidation, the sulphides are solubilized, but part of the dissolved iron reprecipitates as jarosite and as an iron sulphate-arsenate-phosphate phase. The pressure oxidation products are subjected to cyanide leaching. The cyanide leach residues consist of quartz, gypsum, bassanite, anhydrite, small amounts of jarosite, an iron-sulphate-arsenate-phosphate phase, as well as trace amounts of orthoclase, rutile, pyrite, hematite and monazite; all these particles are dispersed in a fine grained matrix of illite-muscovite. The autoclave leach residues contain a small amount of carbonaceous matter. Many gold grains are detected on the surfaces of the carbon particles, and these gold particles are not leached during cyanidation. The gold particles are typically 0.1-0.2/Lm in size and commonly are embedded in the carbon surface or are coated with a K-AI-Si-S-O phase on the surface of the carbon. The gold grains are consistently associated with elevated CI contents (50-300 ppm Cl). The poor gold cyanide leach recoveries, which initially occurred in the Twin Creek developmental circuit under certain operating conditions, are attributed to the presence of chloride in the feed. This results in the formation of soluble gold chlorocomplexes in the autolcave and the subsequent sequestering of the gold on the surfaces of the carbon particles.

Jan 1, 2000

By Edward Rosenberg

The synthesis and characterization of silica polyamine composites modified with a variety of sulfur containing ligands is described. The two most successful ligands in terms of sulfur in-corporation and mercury capture are ethylene sulfide and carbon disulfide. The ethylene sulfide forms either an amino mercaptane or a polysulfide upon reaction with amino groups on the composite. The carbon disulfide undoubtedly forms a dithiocarbamate functional group upon reaction of the amino group under basic conditions. Both materials posses excellent capture kinetics and capacities for mercury, Once captured, the mercury is extremely difficult to remove from the composite materials, even with concentrated acids, and they easily pass the TCLP test. The materials are compared with related thioether modified silica polyamine composites and appropriate potential applications are discussed.

Jan 1, 2003

By William A. Hockings

This report describes the results of laboratory studies on leaching of copper ores.tlf These studies are the first step of a program for the investigation of in situ leaching of tabular, metalliferous ore bodies.(2) The basic steps required in the development of an in situ process are: 1. Leachability - the ability to dissolve the metal values from the ore under in situ conditions must be demonstrated. 2. Ore Preparation - the ore must be prepared so that sufficient contact with the solution can be attained. 3. System Design - integrated in situ systems must be designed and studied for engineering feasibility. 4. Economic Feasibility - the economics of the system must be shown to be economically feasible and competitive. 5. Environmental Feasibility - the loss of reagents into the environment must be investigated. 6. Pilot Scale Testing - the feasibility of the system must be demonstrated on a sufficiently large scale. The studies described in this report were concerned only with the first step of the program, viz., leachability. Native and sulfide copper ores from the Michigan copper district were selected as model ores for these studies. Aqueous amnonia solutions were chosen as the solvents to be investigated. In this study carbonate (CO3, HCO3, H2CO3) was used exclusively as the anion. In keeping with custom it is referred to as carbon dioxide and concentrations are ex- pressed in terms of CO2. When leaching native copper the reaction is

Jan 1, 1976

By Herbert H. Kellogg

A model of the ISF is described. which reproduces with accuracy the "normal" operation of three industrial furnaces. The model, written in Fortran, is based on detailed heat and material balances, and the concept that the ascending gases reach equilibrium with zinc oxide and with the water-gas shift reaction. "Solution loss" of carbon in the lower shaft, and partial reoxidation of zinc vapor in the upper shaft are also essential features. For prediction of furnace behavior under altered operating conditions (blast rate, temperature, moisture content, oxygen enrichment, or injection of oil or coal through the tuyeres) the model modifies the heat loss, temperature of slag and bullion, amount of reoxidation in the upper shaft and the condenser efficiency to reflect the altered operating parameters. Model predictions for such operating conditions are in reasonable agreement with plant experience.

Jan 1, 1990

By N. Kanari

The kinetics of oxychlorination of MgO by C12+02 was studied in the temperature range of 850 °C - 1025 °C, using thermogravimetric analysis. The effects of C12/02 ratio, gas velocity, temperature and partial pressure of reactive gases on the reaction rate were investigated. The oxychlorination process was characterized by an apparent activation energy of about 214 kJ/mol. The reaction orders with respect to C12+02, C12 and 02 at 950 °C were about 0.65, 0.98, and -0.37, respectively. Some data about oxychlorination kinetics of MgO, Cr2O3, and MgCr2O4 contained in chromite were compared. Efficiency of using oxychlorination for the removal of iron oxides contained in magnesia was demonstrated.

Jan 1, 1999

By Musa Karakus

The sedimentary iron ores of Alsace-Lorraine, France have very high phosphorous contents that average 0.7% and are as much as 2.19% P. Ores from the Tucquegnieux and Joeuf mines have been studied by cathodoluminescence microscopy, X-ray diffraction, scanning electron microscopy, and electron microprobe analysis in order to fully characterize the mineralogy, size, shape, and distribution of the deleterious phosphate grains. The phosphorous occurs as collophane, a carbonate fluorapatite, in ten morphological forms, most abundantly as microcoprolites, but also as intraclasts, concentric layers, and cortices in ooids, phosphate replaced ooids and bioclasts, phosphatiC shells, fossil infillings and internal molds, fish teeth, phosphatiC laminae, and cements between the goethite ooids. About 95% of the phosphate grains are sufficiently large that relatively fine grinding fol'lowed by reverse flotation would be expected to be effective in significantly diminishing the phosphorous content of the concentrates.

Jan 1, 1989

By C. Beckermann

"A diffuse interface model is derived for the direct simulation of two-phase flows with surface tension, density differences between the phases, and phase change. The derivation starts from the balance equations for a sharp interface and uses a formal averaging procedure on an atomic scale to obtain diffuse interface versions of the equations. Two approaches are considered: (i) the two phases have different velocities inside the interface and separate conservation equations are solved for each phase, and (ii) the two phases have the same velocity inside the diffuse interfuce and mixture conservation equations are solved. Based on a superposition of microscopic (atomic-scale) and macroscopic interface morphologies, an expression for the interfacial momentum source term is introduced that models surface tension effects and accounts for immiscibility between the phases.IntroductionDiffuse interface methods have been a popular tool in the direct simulation of two-phase flows [I]. In diffuse interface approaches, the interface between the two phases is characterized by a rapid but smooth transition in the properties, such as density and viscosity. Usually, a phase function ? is introduced to represent this transition, and the evolution of ? in the domain is computed from a separate equation or recipe. A unique set of conservation equations (e.g., mass and momentum) is solved on the entire domain, irrespective of the phase present, by accounting for the transition in the properties and introducing terms that account for interfacial sources. The continuum surface force (CSF) model of Brackbill et al. [2], which accounts for surface tension, is an example of the latter. The volume-of-fluid (VOF), level set, and phase-field methods are all examples of diffuse interface approaches. The major advantage of diffuse interface methods is that explicit tracking of the interface and the application of traditional sharp interface conditions are avoided. A disadvantage can arise from the artificial smearing of what is in reality an interface of atomic-scale width; however, techniques have been developed to overcome this problem."

Jan 1, 2004

By Y. H. Liu

Several foaming aluminum samples of different density were prepared in a semi?industrial scale experimental system, Their properties such as the energy absorption characteristics, mechanical properties, heat conductivity and acoustical properties were measured. The results showed that the foaming aluminum with a density of 0.5 to 0.6 g/em3J has the best energy absorption and this makes it suitable as the ensuring bar of the automobiles and also as a cushion material for the engine. The foaming aluminum with a density of 0.25 to 0.4 g/em3 has the best acoustical properties and heat conductivity resistance, which is suitable for the door filling material, the ceiling and the partition or the car engine.

Jan 1, 2003

By Robert W. Bartlett, Keith A. Prisbrey

"Natural biooxidation of shallow, refractory ore heaps, relying on gaseous oxygen diffusion from the heap surface is attractive because of its simplicity and potential low cost, especially without using a lined pad, which is possible if percolation of leachate through the heap is avoided. In this case, the excess oxidation enthalpy must be removed by water evaporation from within the wet ore heap, and the rising water vapor flux within it will impede the downward oxygen flux. An analysis of this process shows that for typical values of pyrite grades and limited temperature increases in the ore heap, the oxidation rate and penetration into the heap is reduced to values between about 30 percent and 50 percent of those obtained when leachate percolation occurs and water evaporation is not a significant mechanism of heat removal.IntroductionHeap biooxidation of refractory gold ores, needed as a pretreatment step to liberate the gold for subsequent extraction by leaching, requires large amounts of oxygen for the normal amounts of sulfide minerals that are typically present, one to two percent pyrite and/or arsenopyrite.The importance and potential limitations of oxygen transport into commercial ore heaps, which are much larger than encountered with column tests of ore and with pilot heaps, has been recognized111 • Commercial ore heaps using radial stacking conveyors are typically about nine meters high and may be 100 meters or more in lateral dimension. Three oxygen transport mechanisms have been identified and analyzed: ( 1) natural convection, which arises from an increase in buoyancy caused by the temperature rise and gas composition changes associated with the exothermic oxidation of the sulfide minerals within the ore heap, (2) forced air ventilation, using low pressure fans and air distribution pipes within the heap, and (3) diffusion of oxygen in the gas-filled void spaces within the ore heap driven by the oxygen concentration gradient from the surface of the heap to the mineral oxidation loci within it."

Jan 1, 1997

By C. Koopman

During the production of phosphoric acid from phosphate ore and sulfuric acid, large amounts of calcium sulfate are formed, in which impurities from the feedstock are incorporated. To use the calcium sulfate in, for example, the building industry, a lower concentration of impurities is desired. Mercury, copper, lead, and cadmium were extracted from clear industrial recrystallization acid (0.8-3.9 mol/kg H3PO4, 0.2-0:5 mol/kg H2SO4) by supported solvent extraction with the extracting agent Cyanex 302 in kerosene in a transverse flow hollow fiber module. The permeability for the mercury ion was 1.4.10-6 m/s, whereas that for the copper ion was calculated to be 1.5.10 m/s. Cadmium, lead, and copper were extracted during the recrystallization of calcium sulfate hemihydrate to dihydrate, an existing step within the ,phosphoric acid production process, by solvent extraction with the same extracting agent. The concentrations of cadmium and zinc in the newly formed calcium sulfate were proven to be decreased. Unfortunately, concentrations of mercury and lead were too low for analysis.

Jan 1, 1999

By Hwasoo Park

Keywords: FC mold, Argon, Magnetic, Solidification Fluid flow plays a significant role for steel surface quality in continuous casting. Although water models are able to model fluid flow, the flow pattern is not of practical interest since the moving solidifying shell cannot be accounted. Computer modeling has become a popular and dependable tool to analyze the complex phenomena occurring in continuous casting. In this numerical simulation we coupled momentum and energy equations considering the solidification of steel along with turbulence ?-e model. The vertical bending mold is equipped with bifurcated nozzle with 15 degrees of port angle. FC mold is supplied with DC induced magnetic fields. Influence of argon and magnetic fields on molten steel flow and heat transfer is investigated by solving momentum equations adding source terms due to multiphase ? magneto hydrodynamics. The results show that magnetic fields reduce the jet velocity from port by lower magnetic core induced field but the influence on meniscus velocity is complex to describe. Magnetic fields increase surface temperature and homogenize its distribution on surface and inside a mold.

Jan 1, 2005

By Xiang Zhu

Xidagou is the largest waste water discharge channel of the Anshan Iron and Steel Complex (AISC) with average flow rate of 8000 cubic meters per hour, which is about 75% of the total effluent of the AISC. The waste water from Xidagou seriously polluted the Taizi River Basin. In order to meet the Chinese Class V Standard for Surface Water Discharge and the Standard for Recycled Industrial Water Reuse, with the aid of the World Bank, the AISC began the treatability studies in 1991. Based on the bench-scale test, the AISC carried out pilot-scale treatability studies on three different treatment processes and five different chemical coagulants for more than half a year in 1992. The study results show that the processes of primary sedimentation- chemical mixing and flocculation-secondary sedimentation-filtration can meet the requirement and that PFS and PAM are effective and economic chemical coagulants.

Jan 1, 1994

By C. Lupi

"The energy consumption of copper production by electrowinning, generally represents more than 1/4 of the total energy requirement in hydrometallurgical traditional process (roasting, leaching, purification and electrowinning). The considerable saving can be achieved just in this step that requires about 2.2 kWhlkg of the produced copper. To save energy the cell voltage, or more appropriately its anodic component, can be reduced: that is because the anodic voltage represents the main component of cell voltage and so it is largely responsible for the excessive energy consumption in copper sulphate electrowinning.In this work some ways are studied to lower the anodic voltage. First the cobalt ions were added to the sulphate solution in order to study the catalytic effect on oxygen discharge. Then lead alloys anodes (Pb-Ag, Pb-Sb-Ag and Pb-Ca) were used to promote a better oxygen evolution as a result of a different anodic surface. Their behaviour was compared with the PbSb traditional ones. Finally, as already pointed out by several authors for zinc electrowinning, ethylene glycol was employed as anodic depolariser in order to verify its effectiveness in the case of copper electrowinning. By combining all the above-mentioned ways, energy saving ranging from 20% to 27% is achieved.All the tests were carried out on a laboratory pilot-plant for long time to simulate the industrial conditions. The obtained copper deposits were observed by SEM to highlight their morphology."

Jan 1, 1997

By M. Hashimoto

The equilibrium distribution ratios of sulfur between molten copper and CaO-fluxes containing caF2 and caC12 were determined in the range of 1300° to 1400° C under carbon monoxide. The rate of approach to equilibrium is rapid and increases with increasing CaCll concentration. In CaO-CaFl-CaCl2 fluxes, the distribution ratio varies in a complex way with temperature and CaFl concentration. The results are compared with those obtained with the binary fluxes of CaO with BaFZ and MgFl ?

Jan 1, 1983