Search Documents

By Robert G. Telewiak

During the past few years, the international nickel industry has taken some important steps to respond to conditions of global production overcapacity, relatively flat demand and low prices. These include the implementation of major cost reduction programs by most producers, closure of some high cost operations and the establishment of the Nickel Development Institute. Consumption in the western world increased by about 7 per cent in 1987 compared to 1986, supplies were less than demand, inventories were low, and late in the year prices increased dramatically. By year-end 1987, most producers were operating at, or close to, their effective capacities. Nickel demand is expected to increase to the year 2000 at an annual rate of about 1.7 per cent, led by increasing usage in the stainless steel sector. If this rate of growth is realized, then there will be need for the effective capacity of the nickel industry to be increased. Producers in Canada have put considerable effort in the past few years into reducing costs - with impressive results. Mining costs, in particular, have been reduced dramatically. While production is still less than the peak years of the yearly 1970's, it has increased substantially from levels of the early 1980's. Over the next few years, production is expected to increase slowly. A key determinant of the level of production in the 1990's could be the effect that regulations on sulphur dioxide emissions have on limiting production.

Jan 1, 1988

By B. C. Jena

In a chromite smelting process for the production of high-carbon ferrochromium, the slag composition profoundly affects operating conditions and the economic performance of the process. For a Canadian chromite concentrate, optimum slag composition and operating temperature were determined by process simulation with a computer model, which is based on parameters, such as the minimisation of slag volume, liquidus temperature, electrical energy consumption and chromium losses. Chromium recoveries are identified for slag compositions spanning wide concentration ranges within the quaternary system MgO-AI2O3- SiO2-CaO. The simulated data are compared with the experimental results.

Jan 1, 1994

By Carlos M. Fontes Vieira, Ruben J. Sanchez Rodriguez, Carlos E. Gomes Ribeiro

"In this study we attempted to model a response surface for the apparent dry density of ternary blends of calcitic marble particles. The crushed marble was divided into three granulometric ranges. Simplex network methodology was used to determine the mathematical relation between granulometric ranges and apparent dry density (ADD) of particle mixtures. A highly significant regression was obtained and the simplex network methodology proved to be able to predict high packing particle compositions.IntroductionProblems with packing and expected porosity of particles are common and widely recognized to be important in terms of both fundamental physics and engineering applications. For example, densification of a powder mass is important in the shaping of solids in ceramics, powder metallurgy or composite synthesis; chemical processes such as solid-liquid separation (sedimentation, thickening and filtration), raw material handling (stockpiling, blending, drying, storage and transportation) and pyrometallurgical processes (agglomeration, coke making, ore sintering, blast furnace iron making and new iron making processes) [1,2].Many factors can affect particle packing, but in practice, there are three main factors: (dimensionless) particle size distribution, particle shape and absolute particle size [2].Geometrical and practical methods were developed to predict properties in mixtures. Zou, Gan and Yu [2] present a paper treating a prediction of the porosity of multi-component mixtures of cohesive (fine) and non-cohesive (coarse) particles. Bahiense et al. [3,4] used a simplex network to determine a mathematical model for obtain the optimal compositions between aggregates to a greater packing of a ternary particles mixture. Despite these techniques for predicting particle packing, some studies in particulate composites production don't present clear criteria for choice of particle distribution [5,6]. As the best particle packaging depends on the size, distribution and shape of these particles, individual models can be constructed for specific combinations of these factors."

Jan 1, 2014

By J. W. Ahlrichs

In gold exploration and metallurgical testing, the role of the mineralogist is to assist in solving problems with regard to (a) sampling, (b) gold occurrences, and (c) petrologic classifications of host rocks. The presence of "coarse" gold as a sampling problem can be overcome by various methods, including "screen fire assays," screened analyses and special gravity techniques which may be used to determine distributions of "coarse" versus fine gold. Determinations of mineralogic associations of gold usually require special separation techniques, accompanied by fire-AA-mineralogic assays of the products. After accurate mineralogic analyses are obtained for various products, quantitative distributions of refractory gold associations can be calculated by the use of simultaneous equations. Petrologic classifications are required by the geologist for mapping and interpretation of the various rocks. After the petrology and mineralogic differences of the rock units are determined, x-ray diffraction analyses of analytical pulps can be used for lithologic logging of drill cores. XRD logging is an efficient method for correlating lithologic units and alteration trends throughout a gold prospect.

Jan 1, 1981

By Yotamu Hara, Animesh Jha

"High Curie temperature and large magnetic anisotropy make cobalt an important magnetic material for power engineering applications of magnets operating above ambient. It is also an essential constituent of modem lithium - cobalt oxide batteries, without which modem electronic gadgets will be functionless. Both these applications of cobalt save energy and reduce C02 emission. Ironically, however the production of cobalt from copper and nickel smelting in the world remains one of the least energy efficient process. The paper analyzes the energy balance, material and process chemistry of overall cobalt recovery and the waste generated, which entail the process limitations. We discuss a novel approach for the reduction of sulphide minerals with CaS04, permitting better separation of metals from slag and generating higher concentrations of S02. Such an approach may seem to be an alternative energy efficient option for processing and further purification of cobalt in metallic form. The results are discussed in the context of process thermodynamics and reaction kinetics for Coalloy production.IntroductionCopper sulphides bearing minerals are predominantly associated with iron and cobalt sulphides minerals. Carrollite (CuC02S4) is a mineral that has both copper and cobalt sulphides [1,2], which may also contain FeS, by substituting either Cu2+ or Co2+ ions in mineral lattice. On smelting copper - cobalt - iron sulphide concentrates, some parts of the cobalt often partition to matte at preferentially low oxygen potential by forming eventually an alloy phase with copper, however a significant fraction is often lost into an oxide slag rich in iron and silica. The slag heaps accumulated in the Copperbelt region in Zambia from last 60 years of mineral processing and metal extraction is reported to be 0.3 to 2.6 wt% of cobalt element, which is high [3]. Cobalt is also available in smaller concentrations in the copper smelting and converter slag, as reported in the investigations on the recycling of such slag materials using leaching with ammonium salt [4], iron chloride [5], and sulphuric acid [6], and solvent extraction [7].The recovery of cobalt from slag, irrespective of the techniques researched so far, does not seem energy efficient because the molten slag at 1300°C is quenched by losing thermal and chemical energy. The quenched slag is again reheated to above room temperature for leaching and above liquidus for carbothermic reduction of residual cobalt oxide. For example, in Mintek DC arc smelting [3], 80% of cobalt and 95% nickel are recovered by expending 600 kW per tonne. Assuming that the mineral carrollite is the starting phase, the univariant calculations for the Co-Ca-Si-S-0, Fe-Ca-Si-S-0, and Co-C-Si-S-0 systems are shown in Figure la, lb, and le, respectively at 1573 K."

Jan 1, 2012

By Tobias Dubberstein, Hans-Peter Heller

The viscosity of Fe-Cr-Mn-Ni TRIP/TWIP (Transformation Induced Plasticity, Twinning Induced Plasticity) steel with varied nickel content is investigated using a vibrating finger viscometer. The viscosity of the melt is calculated from the change in power input in the field coil by an immersed finger into the liquid steel to maintain a constant peak-to-peak amplitude of the sine wave of oscillator compared to the idle state. Nickel content in steel is varied from 3 wt% to 9 wt%. The dynamic viscosity (η) at 1600 °C for 3 wt% Ni is 3.73±0.14 mPas, for 6 wt% Ni 3.50±0.03 mPas, and for 9 wt% Ni 3.93±0.09 mPas. There is a kink from low to high nickel content in viscosity values of Fe-Cr-Mn-Ni alloys. This phenomenon can be explained by a change in coordination number in the melt, as reported for Fe-Ni binary system in literature. The availability of viscosity data delivers relevant input to model free fall atomization processes of FeCrMnNi alloys.

Jan 1, 2015

By G. A. Bala

As part of ongoing research to define mechanisms of microbial enhanced oil recovery (MEOR), this work describes the activity of Bacillus l1chen1formis JF-2 (ATCC 39307) Mosurfactant against crude oils with varying compositions. Surfactant based MEOR improves oil recovery by lowering the oil/brine interfactal tension (IFT) therefore permitting oil to be displaced or solub1lized into the aqueous phase.? MEOR is an Enhanced Oil Recovery (EOR) process which allows for the introduction of chemical and miscible fluids, in the form of microbial metabolic end-products, through the injection of microorganisms into the reservoir or stimulation of indigenous reservoir microbial populations. These microorganisms represent a replenishable in situ source of acid, gas, biopolymer, solvent, or surfactant products which can be. supported and manipulated by the addition of simple and inexpensive nutrients to enhance the recovery of oil. Microbially mediated surfactant production represents one mechanism of MEOR. Bacillus licheniformis JF-2. has been used in a mode 1 MEOR system based on Berea sandstone cores (permeabilly .85 to 400 md) to examine surfactant based MEOR of medium to heavy crude oils (API gravity 38.1° to 17.5°). Enhanced oil recovery was achieved with all oils tested using either cell free culture supernatants or microbial suspensions as injectants with no detrimental effect to the oil. Spatial distribution of cells following mf?crobtal flooding was analyzed with scanning electron microscopy. Data indkate complete distribution of cells with a predominance of organisms located distal to the point of injection. There appears to be no sign:if1cant recovery trend with respect to oil composition.. The biosurfactant produced by Bacillus lichen1form1s JF-2 lowers the interfacial tension of all oils tested equally well.

Jan 1, 1991

"An experimental study has been performed to investigate the dispersed phase holdup induced by a high-strength submerged gas injection in a bottom blown air-stirred one-seventh water model of CLU (Creusot-Loire Uddeholm) reactor using two different tuyere configurations. The air flow rates varied from 0.00599 m3/sec to 0.01312 m3/sec. In these series of experiments, water height and kerosene height were kept constant at 0.23m and 0.02m respectively. The dispersed phase holdup was determined at various gas flow rates, and tuyere orientations by using water and kerosene.The dispersed phase holdup increased with gas injection rate and decreased with vertical distance from the original interface. At constant gas flow rate, as the vertical distance increased in the centerline, off-center configuration of nozzles displayed higher values of the dispersed phase holdup than those of the center configuration. The variation of the dispersed phase holdup with the dimensionless axial distance and the gas injection rate was correlated by using the Modified Froude Number. The experimental values of the dispersed phase holdup were found to be in good agreement with the calculated values obtained from the correlation equations."

Jan 1, 1999

By Li Xi

This paper describes how a back-propagation neural network is built for predicting the properties of engineering materials from their other properties, compositions or processes. A predicted result of the impact toughness of a 12Cr-2Ni-1.5Mo stainless steel from its tempering temperature is presented. Furthermore, the combination of this neural network for prediction is able to supplement the unpredictability of the expert system outside its domain of expertise. An integrated system may perform more intelligently and solve more complex problems as well as human expert, in some case even better.

Jan 1, 1992

By Roberto Parada

In a long term program for the optimization of the Outokumpu Flash Smelting Furnace at Chagres Smelter many different subprograms are being developed. One of them is the design and application of a sampling method that can allow the direct diagnostic of the quality of the copper concentrates combustion. We present in this paper the evolution of the sampling devices used in a ten months of continuous sampling campaigns and an example for the sulfur elimination and magnetite formation in the flame from 60 cm to 100 cm under the burner. These type of information combined with the appropriate mathematical modeling of the combustion must propose some considerations to correct the classic criteria in the preparation of the charge for the smelting of copper concentrates based only on the mass and energy balance from the chemical and mineralogy composition of the concentrates.

Jan 1, 2006

By Robert W. Bartlett

"Bioheap pretreatment of sulfidic refractory gold ore prior to cyanide leaching is a promising new technology, especially for low-grade ores that cannot afford to be oxidized by pressure leaching or roasting. When an ore contains both refractory and non-refractory (oxidized) gold, an economic decision must be made whether, or not, to pretreat before cyanide leaching. This choice is more complex than the familiar ore/waste cut-off grade decision. Pretreatment usually increases recovery but delays receiving revenue. Based on choosing the processing route that maximizes the present value of the ore, an equation is developed that computes a ""critical cyanide leachable gold grade"" for determining whether pretreating will be profitable. If the ore's actual cyanide leachable grade, without pretreatment, is above this ""critical grade,"" it will not pay to pretreat. The waste/ore cut-off grade, pretreatment yield (leachable grade after pretreatment), total gold grade, pretreatment operating cost and the project's financial discount rate are parameters in the equation. Results of example calculations are provided. This equation can be used for mine development planning and, when bioheap pretreatment is an available option, for daily operating decisions on individual ore blocks.IntroductionOres that are refractory because of sulfide mineral encapsulation of microscopic gold are becoming important. These ores must be pretreated to oxidize the sulfides to liberate the gold prior to cyanide leaching. The conventional pretreatment process technologies are pressure leaching with oxygen and two-stage fluid bed roasting. However, low-grade refractory ores cannot afford the high operating costs of these processes. And, small mines with limited reserves cannot justify the high capital costs of these processes."

Jan 1, 1997

By W. L. Cornell

The processing of lead tailings for removal of the heavy metals produces concentrates upgraded in Co and Ni values. Reflected light microscopy, scanning electron microscopy, image analysis, and Vickers hardness measurements were used to identify mineral species, associations, degree of liberation, and distributions to the test products. Siegenite and bravoite were the most common species encountered, but violarite and enriched pyrite and marcasite phases were also identified. Liberation for the Co and Ni minerals contained in the tailings was 20 micrometers or less.

Jan 1, 1993

By Peter J. Koros

The current wave of interest in this topic is the result of increased use of titaniferous ores or ilmenite in blast furnace burdens for the purpose of repairing hearth damage. The titanium compounds that promote deposition of ?patching? materials in blast furnaces are the cause of downstream problems in the steelmaking shops. Steelmakers historically have objected to significant amounts of titanium in hot metal (>0.10 % Ti) for several reasons: 1) accretions caused by the TiC.TiN needles that float out of the iron as it cools in transit and in transfers make the accompanying slag sticky and crusty, causing problems in desulfurization and increasing time and Fe yield loss at the subsequent raking, 2) defensive measures have been taken in treatment, such as use of argon for carrier gas, but without technical rationale for this approach, 3) difficulty in removal of the ladle slag by the raker, with subsequent sulfur addition to the vessel charge, and 4) transfer into the BOF and/or formation of a very corrosive TiO2 containing acid slag during the early part of the BOF blow which, in addition to causing lining damage, results in loss of sulfur removal capability by the vessel slag. Based on a conceptual analysis of the metal-slag-atmosphere interactions during transfer ladle desulfurization treatment, a mechanism is postulated for the apparent effectiveness of the use of argon in reducing the deleterious effect of titanium and an alternate technique, possibly more effective, is proposed. As probably the use of argon causes increased exposure to atmospheric oxidation of the titanium carbonitrides contained in the ladle slag, the same benefit can be obtained by use of either oxygen or an air blast to oxidize the noxious reaction compounds. Validity of the concept has been demonstrated in a pilot plant setting. These issues, and related effects on testing the hot metal, are examined in detail with reference to the literature and plant and laboratory experience.

Jan 1, 2006

By Batric Pesic

Calcium silicate slag (Di-Cal) and magnesium oxide condensate (MgO) are the by-products of magnesium smelting operations, As these oxides have acid neutralizing and metal precipitating properties, it was decided to examine their reactions with (a) individual heavy metals and (b) with a mixture of metals in solution, The resulting solid reaction products were further tested with respect to the stability of the contained metals, The stability of the solid precipitates were examined as a function of the method of precipitation and as function of the solution pH With respect to the method of precipitation, the performance of Di-Cal and MgO was compared to the performance of lime, an industry standard for heavy metal precipitation, Four different pH solutions (4,0, 5,0, 7,0 and 1 LO) were used to study the effect of pH on the stability of the precipitates. It was found that Di-Cal, in most cases, produced the most stable precipitates and thus, outperformed lime, Metal precipitates prepared by the addition of MgO were the most soluble for each metal studied, except for Se,

Jan 1, 2001

By Saad Elias Kaskah

"The Box-Behnken Design (BBD) is used to model the sacrificial Cathodic Protection System (SCPS) to find the factors effectiveness behaviour. For protection potential assessment the BBD receives (resistivity of environment, sacrificial anode alloy, distance between anode and cathode and surface area for the structure to be protected) as input and gives the protection potential as output. By applying BBD with their analysis tools we get many results. The important results which are the factors individual effectiveness on the sacrificial cathodic protection (SCP) process are the resistivity which has the greatest effect on the potential protection (rank=l) followed by sacrificial anode alloy type (rank=2), surface area for structure protected required (rank=3) and distance between anode and cathode (rank=4). The interaction of sacrificial anode alloy and cathode area {X2X4 ) has significant effect on CP process with the limits which are used in this work while the other factors interaction (X1X2, X1X3, X1X4,X2X3, X3X4 ) has insignificant effect on the limits which used in this work.IntroductionFor carbon steel in seawater the normal corrosion potential E '°""_is in the range -550 to -600 mV vs. Ag/AgCI [1]. The most effective method to overcome the corrosion is cathodic protection {CP) which represents a control method in the steel wall corrosion. Cathodic protection has been used in several areas including marine and underground structures, storage tanks, and pipelines [2]. Sacrificial anodes system generates protective current which depends upon the inherent potential difference between the anodes and the structure to be protected. If the structure is made of iron or steel, any metal that is more active in the electromotive force series can theoretically be used as anode material [3]. There are many factors influencing on cathodic protection like resistivity (NaCl content), chemical composition of sacrificial anode alloy, distance between anode and cathode, surface area of cathode, temperature, humidity, velocity of solution, dust, impurities, bacteria and etc .. The present work studied four factors: NaCl content, resistivity), chemical composition of sacrificial anode alloy, distance between anode and cathode, surface area of cathode) with different three levels of values for each one. Then this work will find the optimum value from the factors levels that tacked to investigated there influencing on sacrificial cathodic protection system."

Jan 1, 2013

By L. L. Tavlarides, N. V. Deorkar

"Recovery/Recycling of metal ions from industrial process waste streams is a preferred alternative to disposal by conventional techniques. This paper presents methods for preparation of inorganic chemically active adsorbents to be used in fixed bed adsorbers. Methods for immobilization of chelating agents on the inorganic supports are discussed. The prepared adsorbents are characterized to determine coverage density of functional groups, effect of pH on metal ion removal efficiency, regeneration efficiency and uptake capacity. Results from the laboratory scale and bench scale experiments are presented here.IntroductionRemoval of heavy metal ions from processing wastes in various industries is an important problem. Waste streams in electroplating, electronic, catalyst preparation and hydrometallurgical industries contain metal ions such as copper, nickel, chromium, lead, tin, cadmium, silver, gold and platinum. One major concern for the non-ferrous metal industry is secondary recovery of precious metals and cyanide from cyanide leachate from smelter residue and hydrometallurgical waste streams.Recovery methods recently considered include evaporation, electrolyte metal recovery, reverse osmosis (1), adsorption, ion exchange (2,3), membrane separation (4,5) and Solvent extraction. These processes have met with various levels of limited success. The use of liquid ion exchange molecules to selectively extract metal ions for on-site treatment of these waste streams is currently receiving substantial interest (6,7). This interest seems from an awareness of the advances made in the development of commercial extractants for metal ion separation in hydrometallurgical industries (8). However, separation by solvent extraction processes is generally considered to be economical in the range of aqueous metal ion concentrations from 0.01 to 1.0 mol/lit (9). In order to exploit the selectivity of chelating agents, the idea of immobilizing chelating agent into a solid matrix has attracted growing attention in recent years. Many supports such as inorganic oxides, organic polymers, cellulose powder and polyurethane foam can be used for immobilization of chelating agents. Over the last decade, considerable efforts have been directed toward attachment/introduction of chelating agents into a polymer matrix (10,11). Inorganic supports as compared to polymer supports provide high mechanical strength, chemical and thermal stability, and high reaction rates due to open pore structure. On the contrary, organic resins shrink and swell, thus affecting mass transfer (12). Many of the disadvantages of polymer supports can be excluded by the use of inorganic supports. Innovative use of immobilization techniques can produce inorganic chemically active adsorbents with comparable capacity, stability and reaction rates. Consequently, the objective of our program is the development of inorganic chemically active adsorbents to be used in a fixed-bed unit operation as an alternative heavy metal ion recovery process. Methods of preparation of inorganic chemically active adsorbents, (ICAAs) characterization and applications are discussed in this paper. A brief summary of the results from laboratory scale studies and bench scale studies is presented."

Jan 1, 1996

By Yousef Mohassab, Manoranjan Misra, Monalisa Panda, Eman Wahbah

This work studies the removal of arsenic (V), arsenate, and arsenic (III), arsenite, from aqueous solution using calcined Quintinite-3T. The two adsorbents Quintinite-3T was prepared, calcined at different temperatures, and characterized by XRD, BET, and SEM. The surface area of the calcined Quintinite-3T was 193.4 m2/g. The particles size ranged from 12 to 56 nm for the uncalcined Quintinite-3T and from 24 to 42 nm for the calcined Quintinite-3T. Kinetic analysis, adsorption isotherm, and factors affecting the adsorption were investigated. Calcined Quintinite- 3T retained As(v) and did not release it back to water even after an entire month.

Jan 1, 2016

By C. H. Quan

Solvent extraction tests were carried out on a rare earth chloride solution derived from monazite processing to determine the effect of extractant and diluent on the distribution coefficients between organic and aqueous phases, and the separation factor between rare earths. The extractants were 20% by volume di-2-ethyl-hexyl phosphoric acid (DZEHPA) or 2-ethyl-hexyl phosphonic acid (Ionquest® 801). Four Shellsol diluents were tested ranging from nil to 100% aromatic content. D2EHPA gave the highest rare earth extraction for a given pH but was less selective than Ionquest. The geometric mean separation factor between adjacent rare earths varied from 2.41-2.56 for D2EHPA to 2.62-3.01 for Ionquest. The nil-aromatic diluents (Shellsol 2037 and 2358) gave better separation factors in Ionquest but, in D2EHPA, were slightly inferior to the 100% aromatic diluent Shellsol AB. Yttrium behaved as a pseudo-heavy rare earth with a distribution coefficient lying between Ho and Er, as expected from its ionic radius.

Jan 1, 1992

By Fu-Shen Zhang, Mengjun Chen, Jianxin Zhu

"A novel approach for foam glass preparation, namely vacuum-aided powder sintering technique, was preliminarily investigated in the present communication. The key point of which was to prepare foam glass at a negative pressure. Compared to normal powder sintering process, the new approach could benefit the foaming process by shorting the holding time, reducing the amount of foaming agent and especially decreasing relative density of the product. Optimum conditions were 750 °C, 1000 Pa, 5 min and 1 wt.% foaming agent, respectively.IntroductionFoam glass represents a highly valuable solution for thermal and acoustic insulation, since it possesses a generally higher mechanical, chemical and thermal stability than other foams'1'. The first industrial processing for foam glass production, the direct introduction of gases (""blowing"") into the special molten glass, can be dated back to the end of 1930s'2'. At present, almost all foam glasses is prepared by powder sintering technique instead of blowing,3 since it reduces the temperature by several hundred degrees. Moreover, as fine glass powders or similar powders can be used to substitute corresponding glasses by this technique, considerable attention has been focused on the production of foam glass by considering fully recycled glasses, coal fly ash, or other solid wastes as raw materials,4 especially CRT glasses'3' 5', on the point of environmental protection.In a previous report'6', when discussing the lead removal and recovery from CRT funnel glass by a pyrovacuum process, we found that foam glass could be prepared at a negative pressure. Therefore, in this communication, the similarities and differences between the powder sintering process for foam glass at normal and negative pressure was preliminarily discussed."

Jan 1, 2011

By Oscar Jaime Restrepo, Juan Camilo Restrepo, Jorge Ivan Tóbon

Portland cement is obtained by a conventional synthesis process from a mixture of limestone and clay at high temperature (1450 °C). This work reports the possibility to obtain cement silicates via alternative methods like Solution Combustion Synthesis (SCS), which optimize both time and temperature, and the consequences to energy efficiency and mitigation of CO2 emissions. The production of one ton of cement emits between 0.62 and 0.97 tons of CO2 into the atmosphere. In this process the CO2 emissions are between 21 and 59%. The combustion methods are chemical redox processes in which, at high temperature, a self-sustaining and fast wave is generated from using chemical precursors and organic fuels.

Jan 1, 2016