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By R. A. Cockerell

This paper is concerned with the application of Advanced Process Control (APC) to copper smelting processes. A number of key issues relating to the application of APC, such as modelling for control, process dynamics and time delays, instrumentation and sampling, are discussed. A general methodology for the application of APC is then presented. Finally, three case studies are presented to demonstrate the benefits and efficacy of applying APC.

Jan 1, 1999

By Majid Sarkari, Hossein Atashi, Farhad Fazlollahi

"The aim of this research work was to prepare the efficient catalyst to purify pollutant output gases such as SO2 , NO2 and CO. This catalyst, lanthanum cobaltat (LaCo03) was prepared by the proper method in the analysis laboratory of Tabriz Oil .The first materials were chosen through calcination operation and temperatures of operation related to the Tamman temperature, therefore the basis for the first material of catalyst was nitrate and aqueous and since we had no availability to lanthanum nitrate, lanthanum oxide was used to prepare the nitrate one. Before all else, the first materials of catalyst were mixed together with the equal mole proportions and then, at the lower and upper temperatures of Tanunan temperature, calcination operation was carried out. To determine the molecular structure, the XRD analysis was utilized and specified that prepared lanthanum cobaltat was sixth aqueous and had the crystal structure type Triclinic.IntroductionLaCo03 has presented a vast interest because of its special electrical, magnetic and catalytic properties [1-4]. The catalyst LaCo03 can be prepared by means of several methods such as spray drying, freeze drying and also co-precipitation [5-12]. Some methods including hydrothermal, sol gel and citrate [13] This material usually has been synthesized by ceramic method and certainly the high temperature for the calcination operation. [14]. Lanthanum catalysts have been researched because of having such an active state [15]. One of the unique properties of this catalyst is the simultaneous conversion of pollutant elements. Nowadays CO oxidation has important applications in environment protection, such as indoor air cleaning and automotive exhaust treatment. LaCoO3 is one of the most important catalysts for CO oxidation."

Jan 1, 2013

By W. G. Davenport

Most pre-t 988 Outokumpu flash furnaces were built with blast heaters. Many continue to use them. Blast temperatures in these smelters· are typically 400 to 700 K (Table 2. 1) This chapter: (a) shows how hot blast is included in our calculations (b) evaluates the effects orhot blast onauthothermal65% Cu matte production.

Jan 1, 2001

By C. Gasparrini

Mineralogy may be applied to the selection of appropriate separation techniques, as well as to assist in the evaluation of problems causing loss of metals and other economically important elements during plant processing. Mineralogic studies may thus help develop techniques to optimize metal recoveries. The present paper describes how such factors as the minerals in which the elements of interest are concentrated, their chemistry, the chemistry of the associated minerals, grain size and textural associations with other minerals in the ore, may affect decisions on separation techniques for the recovery of economic elements. A number of case studies are described in which the mineralogical observation of ore samples has revealed the cause of problems experienced in the extraction of select precious and base metals, or has been decisive in the choice of appropriate techniques for recovery.

Jan 1, 1981

By K. Dzieciol

The paper presents a study about three image correlation methods ?common cross-correlation, mutual information and phase-correlation ? applied to characterize microstructures reconstructed with X-ray tomography. It is shown that phase correlation is not only the fastest, but also the most sensitive method for detection of similar microstructure features, cavities in the present case. A new image correlation indicator is proposed, which takes into account both the phase shift and the amplitude of similar features in compared images. Some preprocessing aspects related to the tomographic reconstruction and filtering out of characteristic noise are also discussed.

Jan 1, 2009

By Suguru Kohno, Yoshihiro Momose, Masakazu Honma, Tokirou Kamosawa

Copper metal surfaces have been examined by an extremely sensitive surface analysis technique called temperature programmed photoelectron emission (TPPE). The surfaces were ultrasonically cleaned and subsequently abraded by a screw in organic solvents and water. The TPPE apparatus is composed of a Geiger counter with Q gas (He+ iso-C4H10). The curve of photoelectron emission (PE) intensity vs. wavelength from 300 to 170 nm, termed PE spectrum, was repeatedly measured at different temperatures in the temperature- increase process from 25 to 350°C. The number of emitted electrons in a PE spectrum (PE total count) increased, reached a maximum at-250°C, and decreased with increasing temperature. With the surfaces cleaned alone in the liquids the maximum PE total count decreased in the order C3H70H > (CH3) 2CHOH > C2HpH > CHPH > H2O. With the mechanically abraded surfaces in the liquids the maximum PE total count changed as a function of the abrasion period and the maximum tended to appear at higher temperature with increasing abrasion period; the maximum value at 10-min abrasion decreased in the order H2O > CHpH > C2HPH > (CH3) 2CHOH > n-C3HpH. It was suggested that the TPPE behavior can be related to the acid-base interaction between the alcohols and the abraded metal surfaces and the presence of a contaminant over layer on the surface. From the XPS analysis of the 01 s spectra it was suggested that the chemical change of the adsorbed oxygen to oxide oxygen with temperature plays a substantial role in the appearance of the maximum PE total count.

Jan 1, 2000

By Krzyszof Borowiec

With the aim of determining the thermodynamic conditions for sulfation of impurity elements, in particular magnesium, in titaniferous slags the equilibrium gas composition for the sulfation reaction: MO + so2 + 1/2 02 = MS04 has been studied by an EMF technique with a solid zro2 + Cao electrolyte. Here M denotes the impurity elements: Mg, Ca and Mn, and the following _oxide systems have been studied: Ti02-MgO-Fe2 o 3 , Ti02-MnO-Mn2 o 3 , and Ti02 -CaO-Si02 , all in the . temperature range 700-1000ºc. Reproducible EMF values were obtained by adding small amounts of -Na2so4 to the oxide-sulfate mixture. From the observed results the Gibbs energy of formation of the phases Mg 2Ti04 , MgTi03 , MgTi 2o 5 , MnTi03 , CaTi03 , and CaTiSio5 , as well as the activity of MgTi05 in the solid solution with Fe2Ti05 have been calculated. The results show that, from a thermodynamic viewpoint, sulfation of these impurities in titaniferous stags i:s favorable- at around and below 800ºC.

Jan 1, 1985

By D. Silva-Galvan, R. D. Morales, S. Gonzáelez-López, A. Romero-Serrano, G. Plascencia-Barrera, F. Chavez-Alcala

This work is focussed on lead decopperising by two techniques: conventional top addition of sulfur and injection of sulfur powder. It is found that the first method proceeds under equilibrium conditions and the second one depends on kinetic considerations. Experiments were carried out using 15 kg lead baths at two temperatures, 340°C and 380°C. The carrying gas used for the injection trials was nitrogen at flow rates of 6.3 and 18.6 L min- 1• The results show that 'decopperising process is more efficient at temperatures close to the melting point of lead for the sulfur top addition process, whereas high temperatures produce better copper removal for the injection of sulfur powder. Besides, the sulfur injection with the higher nitrogen flow rate (18.6 L min-1) produced higher decopperising rates. Thermodynamic and kinetic models are used to simulate this lead refining process.

Jan 1, 2000

By Ladislav Bebar, Tomas Parizek, Radek Dvorak, Petr Stehlik

"More and more sweeping environmental regulations initiate research, development and introducing into operation up to date technologies for cleaning off-gas and flue gas generated in various branches of industry and municipal waste treatment. The following systems based on novel types of equipment are shown: thermal and catalytic treatment of waste gases polluted by VOC (Volatile organic compounds) and carbon monoxide (alternatively NOx), catalytic filtration for efficient destruction of PCDD/F (dioxins) and potentially NOx, wet cleaning of flue gases polluted by SO2, HCl and HF with a original type of homogenizer “O-element”, integrated equipment for cleaning waste gases polluted by solid particulates, SO2, HCl, HF and heavy metals (alternatively NOx or PCDD/F). The outstanding features of all equipment mentioned above are low investment and operating costs together with high removing efficiency of pollutants. These units can be used mainly in incineration plants, refineries and other chemical plants. The paper represents a review based on papers published in reputable international journals and a monograph under preparation as well as on experience from industrial applications.IntroductionIn the recent years, more and more emphasis is put on preserving clean environment. One of the most closely monitored objects of general public attention are exhaust gases, containing a number of undesirable compounds like NOx, CO, SO2, HCl, HF, fly ash a PCDD/F. These harmful species are created in chemical processes mainly in the industry, transport and energy sectors. There is therefore a strong impetus for abatement of these harmful pollutants. Sectors of industry are thus subject to emission regulations specific to various types of units. In the framework of increasing demand for a clean environment, the concerned legislation is becoming increasingly strict and requires removal of pollutants by modern methods that would ensure efficient abatement of emissions at reasonable investment and operating costs.Attention is focused chiefly on methods for decreasing harmful emissions from thermal waste treatment facilities processing industrial and municipal waste that may be subsequently applied in other sectors of industry. Units for the thermal treatment of waste not only provide means of its disposal, but may become also important sources of energy, provided that strict emissions limits are satisfied. Figure 1 compares emission limits given by the legislation for municipal waste incinerators and limits for a selection of energy sources with heat capacity up to 50 MW (see EU regulation 200/76/EC). The Figure implies that the values of emission limits for waste incineration are mostly comparable with emissions from the combustion of natural gas. Thanks to the continuing improvements of the methods for removal of harmful pollutants, the emissions from waste incinerators are typically deep below the limits."

Jan 1, 2008

By W. G. Davenport

Inco flash smelting blows industrial oxygen, dried Cu"Fe-S concentrate, Si02 flux and recycle materials horizontally into a hot (-1500 K) furnace. Once in the furnace, the oxygen reacts with the concentrate by Reactions 1.1, 1.2 and 1.3 to give: (a) liquid matte, 55 to 60 mass%Cu (b) liquid slag, 1 to 2 mass% Cu (c) off gas, 60 to 75 volume % S02. The matte is tapped into ladles and sent to converting, Fig. 1.3. The slag is tapped into ladles, and sent to a stockpile; with or without a Cu-from-slagremoval step. The off gas is water-quenched, cleaned of dust and sent to a sulfudc acid plant. The [nco flash furnace is also used to recover Cu from molten recycle converter slag. The slag is poured' into the furnace via a steel chute and water-cooled door, Fig. 3.1. In 2000 there are five Inco flash furnaces in operation: at Almalyk, Uzbekistan (Ushakov, et at. 1975); Hayden, Arizona (Marczeski and Aldrich 1986); Hudey. New Mexico (Belew and Partelpoeg, 1993); and Sudbury, Ontario (two furnaces, Carr etal, 1997, Humphris et ai, 1997; Molino et ai, 1997). The Almalyk, Hayden and Hurley furnaces smelt Cu-Fe-S concentrates. The Sudbury furnaces smelt Ni-Cu-Co~Fe-S concentrates'to produce -45% Ni+Cu+Co matte and -1% Ni+Cu+Co slag.

Jan 1, 2001

By Moenster J. A., M. J. Sankovitch

Doe Run's Buick Smelter was converted from a primary lead smelter to a secondary lead smelter in 1991. The recycling facility was designed to produce 60,000 tons of refined lead per year from 110,000 tons of spent starting-lighting-ignition (SLI) batteries and 10,000 tons of lead contained in drosses and scrap. Since commissioning, Buick's refined lead output has steadily increased to exceed 120,000 tons for 1999. The production gains have been the result of continuous process improvements, empowerment of the workforee, and development of additional scrap lead streams. The production gains were accomplished while setting industry standards for employee safety, reducing plant environmental emissions and employee blood leads, achieving ISO 9002 certification, and expanding product lines to meet customer requirements. This paper highlights Buick's major accomplishments through the 1990's.

Jan 1, 2000

By Leonard J. Friedman

Modern smelting systems using continuous, flash and/or oxygen smelting processes have a significant effect on the choice of sulfur dioxide control processes and system arrangements. Based on gases from an enriched air or oxygen smelting furnace and copper converters the paper reviews and analyzes alternate processes and system arrangements for recovery of sulfur dioxide. The work indicates the choice system to include a conventional sulfuric acid plant for converter gas and a liquid SO2 plant to handle the high strength smelting fur¬nace gas. The liquid SO2 plant would be used as a fly-wheel to damper the flow and SO2 concentration variations of the con-verter acid plant. Potential energy recovery alternates and product flexibility are also reviewed.

Jan 1, 1983

By C. K. Gupta

The paper reports on the experimental work and results obtained in processing a xenotime concentrate. The rare earth resource concentrate has been treated by three different methods namely, hydrothermal leaching, alkali roasting and alkali pugging or baking. The recovery in hydrothermal leaching with caustic soda at 150-160°C has been 89%. En comparison, processes involving alkali roastings with soda ash at 850°C and with caustic soda at 500°C, and alkali pugging or baking with caustic soda at 200°C have given recovery values close to 100%

Jan 1, 1992

By Cesar O. Gomez

A procedure has been developed for mounting at random particles of mineral samples to be characterized using image analysis. The procedure is based on the generation of a random distribution of sample particles in particles of a diluent material. and the embedding of this particle mixture in an epoxy resin without disturbing the initial distribution. Two materials with atomic number similar to that of the epoxy resin were successfully used as diluents: activated charcoal and graphite. The proportion of diluent material to be mixed with the sample to have a large number of mineral particles in the field of view while keeping the occurrence of touching particles at an acceptable level was determined empirically. The randomization achieved with the procedure developed in this work was tested using as samples known mixtures of silica and pyrite particles of the same sieve class. The agreement obtained between the mass ratio of minerals used in the preparation of a particular specimen and that resulting from image analysis demonstrates that the procedure developed is successful in producing a specimen where the embedded particles are randomly distributed.

Jan 1, 1988

By C. W. Vierrether

Mineralogical analysis contributes directly to the selection of applicable beneficiation techniques for a given site. Tentative remediation methods for use on the Sharon Steel tailings in Midvale, Salt lake County, UT, were determined in part by mineralogical characterization. A systematic characterization scheme was employed to identify mineral species, mineral associations, and grain size. This paper presents the mineral content and distribution data collected for site characterization. This data was used to determine areas that were representative of the total tailings at the Sharon Steel site. Although this was the main focus of characterization, other useful information was obtained. The approximate location of "old jig tails" was identified and insight on possible arsenic, mobility through the pile was also obtained from the mineralogical study.

Jan 1, 1991

By M. G. Basavaraj, S. Sarkar, G. S. Gupta, P. D. Patil

"Previous experimental study on raceway size hysteresis on two-dimensional cold model showed that the inter-particle and wall-particle friction had a very large effect on the raceway size. Existing literature correlations for raceway size ignore the frictional effects. It has also been shown in the present study that their applicability to the ironmaking blast furnace is questionable. To take into account the effect of friction on the raceway size a stress analysis has been done for the raceway region. Two-dimensional fluid flow equations under turbulent conditions have been developed and solved computationally in order to get the pressure forces. The frictional forces were obtained in terms of stresses. To predict the raceway size a force balance was done for the raceway zone considering the pressure force, the frictional force and the bed weight. The resulting equations from the force balance are able to describe the raceway hysteresis phenomena reasonably well along with the raceway size. A two dimensional experimental set up has been fabricated in order to validate the computer predictions. Predicted values agree well with the experimental values.IntroductionWhen a high velocity blast of air is introduced into a packed bed through a tuyere, a cavity is formed in front of the tuyere. This cavity, formed in the iron-making blast furnace, is called the raceway. Coke tumbles down and bums in this raceway, generating heat and reducing gases for the iron-making process. The raceway is responsible for producing most of the reducing gasses in the blast furnace. In addition, the size and shape of the raceway determines the movement of solids within the blast furnace, the distribution of gases and liquids (slag and metal), setting the location where the primary chemical reactions occur and the temperature profile in the lower part of the blast furnace.Due to the importance of the raceway, many investigators l - 6 have studied it and have predicted the raceway size using the empirical correlations based on experimental (hot & cold) and mathematical models. A number of correlations have been reported in the literature to predict the raceway size by various investigators3 - 6 which are different to each other. Each of the correlations shows a different dependence of raceway diameter (DR) on bed height, particle size, solid density, bed voidage and blast velocity. None of the correlations includes the effect of solid stresses on the raceway size and shape. The magnitude of these stresses will depend on the bulk solids properties (internal angle of friction, wall angle of friction) and the bed dimensions."

Jan 1, 2001

By R. L. Nyirenda

The use of ammoniacal ammonium carbonate (AAC) leaching for the treatment of carbon steelmaking EAF dust has been investigated on a laboratory scale. The experiments have been conducted on dust samples obtained from three European steelmaking companies. As received, the dusts were found to be toxic when tested according to current EPA toxicity testing procedures. Toxicity was on account of the leachability of one or more of the following elements: Ag, Hg, Pb, and Cd. Leaching experiments with concentrated AAC solution at 40 " C showed that zinc oxide present in the three dust samples, 60-80% of the total contained zinc, was rapidly solubilized. Data on the dissolution characteristics of Cd, Fe, Pb, Mg, and Mn are also presented. Toxicity tests conducted on residues of the leaching experiments found these to have leachates below past and current EPA toxicity threshold limits.

Jan 1, 1993

By Richard H. De Voto

The McDonald Gold Project and two satellite gold deposits near Lincoln, Montana, contain at least 9.9 million ounces of gold and 30 million ounces of silver. The McDonald gold deposit alone contains 7.2 million ounces of gold reserves that can be open-pit mined and processed by cyanide heap leaching at a projected cash operating cost of $190 per ounce. The deposit is predominantly oxidized with no chance of acid production, and can be mined, operated, and reclaimed with minimal permanent environmental disturbance other than the creation of an open pit filled with a fresh-water lake which would support trout. The Seven-Up Pete Joint Venture, the owner of the McDonald Gold Project, commenced permitting of an open-pit, heap-leach operation in November 1994. In 1998, Montana citizens passed an anti-cyanide, open-pit mining initiative, 1-137, which banned any new open-pit gold mine which uses cyanide processing, The Venture has conducted extensive studies, including metallurgical testing of the treatability of McDonald ores with alternative lixiviants, and has determined that all other mining and metallurgical treatment systems are vastly uneconomical in the recovery of gold and silver from the McDonald deposit. Therefore, the Venture's proposed open-pit mining and cyanide heap-leach processing is the only technology that can be applied economically to the McDonald deposit. Further, the analyses convincingly demonstrate that the proposed open-pit, cyanide heap leaching technology results in maximum resource conservation of this valuable and unique deposit and poses far less risk to human health and the environment than any of the alternative technologies.

Jan 1, 1998

By D. Papazoglou

This work was undertaken to investigate the thermodynamic and kinetic feasibility of using hot sulfur dioxide bearing gases from smelting processes to selectively sulfate the nickel in nickel laterite ores for subsequent extraction in water. The environmental benefits ofthis approach, as opposed to releasing the gas to the atmosphere, and the economic benefit of directly utilizing the S02 rather than converting it to sulfuric acid are strong drivers for such a process. A thermodynamic analysis indicated that selective sulfation of the nickel could be feasible under appropriate conditions and these were explored through a series of laboratory scale experiments. Laterite samples were reacted at temperatures between 500 and 800°C with an equilibrated mixture of sulfur dioxide, oxygen and nitrogen in a fixed bed reactor. Tests were conducted on saprolitic ore from Bulong, Western Australia, limonitic ore from New Caledonia and garnieritic ore from Indonesia. Nickel extractions were highest from the limonite and relatively low from the other ores. The maximum selective extraction of nickel from the limonite in a single stage sulfation was 73%. Sulfation of other elements present in the laterites was also examined. A two-stage process was also identified which involved sulfation using a strong sulfation potential followed by weaker sulfation potential to attempt to convert ferric sulfate formed in the first stage to ferric oxide. This increased the extraction for the limonite ore to around 84% Ni, 95% Co and 2% Fe. Direct sulfation of laterite could be feasible in locations where sulfide smelting or roasting operations are relatively close to laterite deposits.

Jan 1, 2003

By George P. Demopoulos

n this study we have sought to highlight the critical linkage between individual reaction kinetic parameters (usually determined in small bench scale experiments) and large continuous reactor performance by focusing on the industrially significant zinc pressure leach process. To this end a comprehensive mathematical model previously developed for the description of this process was employed. In this paper we have examined in particular how small variations in key kinetic parameters impact on the autoclave&apos;s performance, i.e. attainment of autogenous steady-state temperature, zinc conversion and solution chemistry. The reaction parameters studied were: (i) stoichiometry of the marmatite leaching reaction; (ii) the activation energy of the same reaction, E,; (iii) the rate constant of the ferrous to ferric oxidation reaction, k,; and (iv) the apparent equilibrium constant for ferric precipitation, K,. This parameter sensitivity analysis was done under no oxygen mass transfer control limitations. Model predictions were found to be more sensitive to the kinetic parameters under certain conditions than others. The most dramatic finding was the one related to the small amount of sulfate produced during marmatite leaching. In connection to this it was found that the small percentage (< 5 %) of sulfate produced enhances the autothermal operational stability of the autoclave. The need for accurate kinetic parameter determination under conditions similar to those encountered in industrial zinc pressure leaching was demonstrated.

Jan 1, 1999