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By William Petruk

The primary requisite for a successful extractive metallurgy operation is to grind an ore fine enough to liberate the minerals so that they can be concentrated, or to expose mineral surfaces so that the minerals can be leached. The ease or difficulty of liberating or exposing the mineral grains is dependent upon the mineral textures such as grain size, crystallinity and bonding between mineral grains. In particular, mineral grains with straight grain boundaries and a weak bonding to other minerals are easily liberated and readily concentrated into high grade concentrates. In contrast mineral grains that have re-entrant boundaries and are strongly bonded to their neighbours are not easily liberated and will not produce high grade concentrates, even with regrinding. Similarly, inclusions that occur along fractures and grain boundaries can be readily exposed and leached. Whereas minute random inclusions in large grains will not be liberated or exposed unless they occur along planes of weakness.

Jan 1, 1995

By D. M. Hausen

It has been demonstrated that microscopic techniques can be applied in a practical manner to the study of spodumene liberation in the processing of pegmatitic ores at the Kings Mountain spodumene plant, Kings Mountain, North Carolina. Spodumene and associated non-opaque gangue minerals are identified and quantified by microscopic point-counting of polished thin sections of heads, concentrates, middlings and tails fractions. Specially prepared polished thin sections? provide uniform thickness of particles for measurement of diagnostic optical properties and the alternate use of incident and transmitted light in distinguishing the various gangue and ore minerals. Spodumene is commonly associated and interlocked with quartz, albite, microcline and muscovite. Concentrate grade depends on the degree of spodumene liberation, which in turn depends on the crystal size and textural association of interlocked minerals. The liberation of spodumene can be measured as a function of screen size by means of microscopic point-count data. Microscopic data also provide useful metallurgical information about the nature of diluent minerals in spodumene concentrates, and the form of lithia losses in the tails. Lithium assays correlate closely with microscopic spodumene analyses in various flotation products from Foote Mineral's Kings Mountain plant, and confirm the applicability of quantitative optical microscopy to the study of liberation and recovery of spodumene from pegmatitic ores. A better understanding of recovery-grade relationships was developed as a result of quantitative microscopy studies.

Jan 1, 1981

By Milton Blander

A review of concepts and theories for predicting thermodynamic solution properties of multi- component high temperature liquid solutions is reviewed. During the last 50 years the ability to predict :such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.

Jan 1, 1996

By C. Burton Clark

The important role of the petrographic microscope in the petrology of refractories is discussed, based on 45 years of industrial experience by the author. Highlights of his career are used to illustrate improvements in equipment and techniques during the period. Two specific investigations are described which emphasize the interrelated use of the petrographic microscope with other instruments such as the x-ray diffractometer and scanning electron microscope. Emphasis is placed on the use of phase equilibrium diagrams for guidance in predicting and interpreting reactions that occur under non-equilibrium conditions in the manufacture and use of refractories.

Jan 1, 1982

By J. B. W. Bailey

The Noranda Horne smelter in Quebec, Canada has change considerably during the last two decades to accommodate varying custom concentrate receipts, closure of the Horne mine, better working conditions, environmental programmes, new technology and increased energy and labour costs. This paper highlights the reasons for changing the smelter from two calcine charged and one wet charge reverberatory furnaces fired by coal to a smelter using. tonnage oxygen oil, natural gas and coal in a single wet charged reverberatory furnace and a Noranda Process continuous Reactor. The current operation 1 described, including three major topics; the use of oxygen/fuel burners on the charge banks of the reverberatory furnace which has increase the smelting rate from 680 to 1100 tonnes of concentrate per day; the oxygen enrichment of the Noranda Process converting air to achieve smelting rates of over 1800 tonnes of concentrate per day; the converting of the mixture of 73 percent copper matte produced from the Noranda Process and the 33 percent copper matte produced from the reverberatory furnace.

Jan 1, 1983

By D. Neuschiltz, M. Witthaut, R. Cremer

"Metastable (Ti,Al)N coatings with fee structure have been shown to exhibit superior performance as compared to TiN under conditions of wear at elevated temperatures due to their better oxidation resistance and hardness. The oxidation resistance of these coatings increases significantly with increasing Al-content. However, the deposition of (Ti,Al)N films with Ti/ Al ratios below about 30/70 leads to a hexagonal structure which is not suitable for tribological coatings. Only little is known about the location of the cubic to hexagonal phase transition and hence about the optimum composition of (Ti,Al)N hard coatings.To determine the position of this transition, Tii-xAlxN films with different Ti/Al ratios were deposited on high speed steel at substrate temperatures between 100 and 700 °C by means of reactive MSIP. The composition of the films was determined by electron probe microanalysis (EPMA) and X-ray photoelectron spectroscopy (XPS), the crystallographic structure by thin film X-ray diffraction (XRD).It could be shown that in case of deposition temperatures of 300-700 °C a two-phase region exists in the metastable TiN-AlN phase diagram, which expands with increasing temperature, wheras at 100 °C substrate temperature no two-phase region was observed. But in opposition to the phase diagram known from literature, which is based on thermodynamic estimations, the detected two-phase region is narrow for typical PVD temperatures, thus allowing the deposition of cubic single-phase Al-rich (Ti,Al)N hardcoatings for tribological applications. Based on these results, a new Ti1-xAlxN film with x = 0.62 has been developed, which showed an increase of oxidation resistance by a factor of 4."

Jan 1, 1998

By Yonggang Liu

Microstructure and precipitates in hot rolled low carbon steel sheet by CSP were investigated in this paper. It is pointed out the precipitates in low carbon steel sheet by CSP are different with that by traditional hot rolling. The bainites were found in CSP hot rolled steel sheet by TEM testing and these bainites could maintain in the sheets even after batch annealing. The selected area electron diffraction analyzing indicated that there were many CrB2BN and FeB4BN phases precipitated in hot rolled steel sheet and no AlN grains precipitated. The nitrides forming can limit AlN grains precipitating during the batch annealing processing, and this could do harm to the texture pipeline along orientation line forming with formed properties.

Jan 1, 2006

By Andreas Siegmund

Cast or rolled lead anodes employed in zinc electrowinning typically contain between 0.5?1.0% silver to decrease the overall corrosion rate. The production of cast lead-silver or lead-silver-calcium anodes often results in the formation of numerous holes, voids or laps in the anode surface that can initiate internal corrosion in localized areas. In rolled anodes the presence of internal porosity is significantly reduced, thus resulting in extended service life. The obtained grain structure of cast or rolled Pb-Ag anodes, however, requires a relatively long period of time to form a stable protective PbO2/MnO2 layer that can evolve oxygen without excessive lead contamination of the cathode. Therefore, these anodes are often mechanically, chemically or electrochemically conditioned prior to being placed in the electrowinning process. RSR Technologies has developed an improved anode for zinc electrowinning. The anode consists of a rolled Pb-Ag-Ca-alloy with controlled surface grain structure. The preferred calcium and silver content of the alloy is 0.05?0.08 % and 0.3?0.4%, respectively. Since May 2001, industrial-scale tests have been carried out at two zinc refineries in North America in industrial electrowinning cells. The controlled grain structure of these anodes allows forming an adherent protective oxide coating within a short period of several days when placed in an electrowinning cell without the necessity of being preconditioned. Anode sludge growth is evenly distributed. The anodes stay dimensionally stable and no short-circuits have been observed. Consequently, low corrosion rates and improved current efficiencies have been achieved.

Jan 1, 2003

By S Ivanaj

Oxidation of chalcopyrite from a copper concentrate in an electrochemical cell having separate-anodic and cathodic compartments was studied by potentiodynamic, potentiostatic and galvanostatic experiments. Oxidation of chalcopyrite particles was mainly realized by in-situ electrogenerated FeIII and Cull ions. The use of an ion exchange membrane, in this experimental set, avoids the reduction of the ferric and cupric ions. The effects of particle size, current feeder potential, current intensity and pulp density were studied to optimize the oxidation parameters. Selective complete oxidation of chalcopyrite was achieved. Oxidation of pyrite was negligible. Mom than 85 % of sulfur was obtained in its elemental form. This may allow selective extraction- of copper from the chalcopyrite concentrate without sulfur dioxide emissions.

Jan 1, 1995

By Jan Dabrovska

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 at 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 2D 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 (Mu, 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 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 Milton Blander

"A review of concepts and theories for predicting thermodynamic solution properties of multicomponent high temperature liquid solutions is reviewed. During the last 50 years the ability to predict such properties for molten salts, silicates and metals based on the generally known properties of the lower order (often binary) systems has been developed and shown to provide predictions which are quite useful in science and technology. There are many gaps in our understanding of these high temperature solutions, especially for metals, and considerably more work is needed.INTRODUCTIONA number of solution theories and concepts have been developed which reliably predict the properties of multicomponent solutions from those of the lower order systems (often only the binaries). Because there is available data for a large fraction of the important binaries, the capability for making predictions for many multicomponent systems used in metallurgical separation processes is broad and potentially very useful. At the very least, the theories greatly minimize the data necessary for predicting properties of complex multicomponent solutions of molten salts, silicates and metals. It is the purpose of this paper to discuss the concepts which are demonstrably useful. We will discuss simple forms of the theories to make the concepts clear but we will refer to the publications which contain the more complex equations needed to treat the large majority of systems.A simple framework for understanding what we need to know in order to make technologically useful predictions is based on well known thermodynamic principles. In technologies and sciences where molten salts, slags magmas or molten metals are used or studied, one must often calculate the extent of a chemical reaction (or separation) or of phase changes. To do this, one must first write an equilibrium constant, K, for the reaction in terms of the standard free energy change of the reaction, ?G°."

Jan 1, 1996

By Rodney Clary

Building on work completed in earlier papers, the current paper presents a techno-economic evaluation of two recently demonstrated technologies for treatment of arsenic containing refractory gold concentrates. Using defined project parameters and inputs, the authors compare capital and operating cost estimates for pressure oxidation (POx), and the Albion Process™. The paper incorporates data now publicly available from the Albion Process™ plant, which has operated at the GeoProMining Gold (GPM Gold) project in Armenia since 2014, as well as recent POx circuits.

By Cong Wang, Siyang Long, Pengcheng Zhang, Haibin Zuo

This paper introduced the research progress of microwave treatment on coal. The mechanics of microwave treatment mainly include thermal effects and non-thermal effects. Thermal effects, which lead to cracks and changes of pore structure, attribute to the selective heating of microwave. Non-thermal effects involve the removal of oxygen functional groups, improvement of coal rank and decomposition of minerals. Therefore, microwave treatment of coal has a lot of potential applications, mainly including drying, desulfurization, improvement of grindability, enhancement of coal-water slurry property and change the combustion and gasification properties.

Jan 1, 2016

By N. Y. Ma

Solid wastes produced in ironmaking and steelmaking off-gas cleaning systems often contain zinc. The zinc level in these solid wastes is generally too high to recycle the wastes for iron through blast furnaces, but too low to economically treat the wastes for zinc through zincrecovery facilities. The behavior, status, and distribution of zinc in the ironmaking and steelmaking off-gas cleaning systems have been analyzed from three aspects: thermodynamics of zinc condensation, oxidation and deposition, correlation of zinc concentration with particle size and density, and aerodynamics of dust particles in the off-gas cleaning systems. Theory and supporting data show that spontaneous separation of zinc from iron-bearing dust occurs in the ironmaking and steelmaking off-gas cleaning systems. Dry off-gas cleaning systems provide the most favorable conditions and environments for zinc to separate from the dust. If highefficiency dry separators were applied and appropriately arranged in the off-gas cleaning systems, zinc would be concentrated, and the majority of the solid wastes could be recycled for iron recovery through blast furnaces.

Jan 1, 2008

By Shenghui Guo, Ying Lei, Hao Niu, Huilong Luo, Jinhui Peng, Libo Zhang, Yu Li

"In this work, the combination of microwave drying (MWD) and heat pump drying (HPD) drying experiments were designed by response surface methodology (RSM) based on central composite design (CCD) using design expert software (Version 7.15), and the process parameters were optimized. The conditions given by software are: the MWD time is 4.6 or 4.4 min; the HPD time is 9.0 or 8.6 min; and the sample mass is 620 or 600 g. Under those conditions the moisture content is 1.0 10-2kg water/kg wet basis, and the effectiveness ratio is 0.70 kg water/kwh. The results of confirmatory experiments conducted under the optimized conditions show the combined drying have superiority of decrease of energy consumption and increase of handling capacity over the single MWD or HPD.1 IntroductionSilica sand is one of a silicate mineral with properties as hard, anti-friction and less reactive, commonly used as raw material for foundry and construction. The silica sand obtained from mineral dressing processes such as scrubbing, magnetic separation and flotation. Its moisture content is approximately 0.08~0.12 kg water/kg wet basis. The most common methods used for drying are solar drying and hot air drying. But these methods have some shortcomings: for example, the solar drying has longer process time due to low energy yield, [1] hot air drying has low-energy efficiency and a lengthy drying time. [2]Microwave is electromagnetic waves with frequency are 300MHz to 300GHz. The outstanding features of microwave heating are rapidity and selectivity. The water specific inductive capacity of 60~78 is much bigger than common materials, the moisture always quickly absorb electromagnetic wave and rapidly transfer to vapors. So, it can significant reduce the drying time. [3] Heat pumps (HPs) are devices for raising the temperature of low grade heat energy to a more useful level using a relatively small amount of high grade energy."

Jan 1, 2011

By V. Jiricny

There is a growing need to process galvanized steel scrap from automobiles, etc., in order to remove the zinc coating that otherwise causes problems in remelting of the scrap in electric arc furnaces. One approach that has moved to the pilot plant stage is that of Metal Recovery Technologies, Inc., of East Chicago (MRI). That company leaches the zinc fiom the scrap with a sodium hydroxide solution. The leached and washed scrap can then be returned to the steel industry. What is left is a sodium hydroxidelzincate solution which must be processed to recover the zinc and the NaOH. Presently, this is done by MRI using electrodeposition on planar electrodes at moderate current density and the resulting zinc is in the form of fine powder which is hard to process into, say, zinc for galvanizing. MRI has supported an investigation of a novel electrode, the spouted bed electrode (SBE), for zinc electrodeposition. In laboratory cells, zinc particles with low porosity have been grown up to 3mm in size. Microanalysis of the deposited zinc showed low level of impurities. DC energy consumption values were usually in the range of 2-2.5 kWg which is well below the energy consumption of the existing cells (and of present-day cells for electrowinning from acid sulfate electrolytes). These results were achieved at current densities (few thousand A/m2) that are much higher than possible with conventional electrodes. Discussion is provided of the scale-up of the cell to a commercial scale.

Jan 1, 1998

By Steve Naruk

Microscopic point-count analyses, although time-consuming, provide detailed mineralogical information which is not obtainable by any other means. Such information can be invaluable for evaluating mill circuit behavior. In comparing two months of operation of a Cu-Pb-Zn sulfide flotation circuit, chemical analyses show that higher copper recoveries and concentrate grades were obtained from lower grade ore, but they provide no explanation of how the improvements were obtained. Quantitative micro-scopic analyses, on the other hand, show the following: 1. There was no change in the identity of the Cu-bearing minerals. 2. Increased copper recovery was achieved primarily by increased recovery of chalcopyrite middling particles. 3. The increased recovery of chalcopyrite middling particles also increased the amount of gangue entrained as locked particles. 4. Increased rejection of free gangue particles, particularly those finer than 25 microns in size, resulted in a net decrease in gangue content.

Jan 1, 1981

By J. Murdoch Mackenzie

Two commercial nickel solvent extraction plants treating laterite leach solutions and using LIX®84-I have been operated in Australia. These circuits employ similar extraction chemistry but differ in their leaching and stripping operations. An alternative process involving elements of both can be conceived. The preparation of the feed solution to solvent extraction plays an important role in nickel extraction using LIX®84-I and the special features of manganese removal and cobalt oxidation in the preparation of the PLS are discussed. This paper compares these three circuit configurations with special reference to the extraction and reductive stripping of cobalt, the transfer of zinc and copper to the strip aqueous, ammonia transfer and sulfur transfer. The potential degradation of the organic and remediation using re-oximation is discussed. Keywords: Nickel, Solvent Extraction, Oxime

Jan 1, 2004

By L. A. Harris

The formation of coke during coal liquefaction can eventually result in catastrophic failure of the conversion system. Coking typically proceeds by the formation of liquid crystals (mesophase) and the subsequent separation of these crystals from the plastic phase formed during heating of coal. The anisotropy of the mesophase makes it readily detectable in the optical microscope under polarized light. This study examines the solids formed during coal liquefaction processing by optical and electron microscopy. Observations on the relationships between the coke morphology, minerals and inert macerals are presented.

Jan 1, 1982