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By D. H. Magoon

The zinc smelter of Cominco Ltd. at Trail, B.C. Is the largest In the western world. A total of 550.000 tonnes of concentrate are proceed at the smelter annually. Approximately 80% of the zinc concentrate is roasted and the remainder Is treated by aqueous oxidation preaaure leaching. The zinc concentrate roasting and sulphur dioxide gas processing plants have undergone many changes over the years. This paper describes the processes and equipment currently used for concentrate roasting, S02 gas cooling and cleaning, mercury removal, sulphuric acid production liquid S02 production, and tall gas S02 scrubbing. The recent Installation of an advanced process control system for the operation of these Integrated processes Is also described.

Jan 1, 1990

By Thor Pedersen

Elkem's technologies for the processing of waste materials, dusts, sludges and other residues, are based on the use of their Multi-Purpose Furnace as the primary processing component. The Multi-Purpose Furnace? is an electric slag resistance reduction furnace equipped with a hot media, Modular Freeze Lining and Elkem's proprietary, air tight electrode seals. The oil cooled? freeze lining allows specific heat fluxes 2 to 3 times higher than furnaces lined with conventional refractory. Reduction activities taking place within the furnace are free from the reoxidation potential of infiltrated air as Elkem's electrode seals are positively gas tight. Small quantities of highly concentrated off gas of controlled composition are produced to suit the requirements of downstream processing. The high electrical thermal efficiency achieved by generating heat within the slag itself, combined with the ability to operate at high melting rates and intense power density, makes the Multi-Purpose Furnace 9 an unique implement for the design of furnace products. These characteristics are utilized in the processing example cited, "Elkem's EAF Dust Processing Technology", which combines two proven technologies in an economically feasible system for the recovery of contained metal values from K061 wastes at the same time producing a disposable slag product. The portion of the example dealing with the condensation of zinc was prepared with the assistance of Imperial Smelting Processes, Limited of Bristol, England with whom Elkem has a non- exclusive license.

Jan 1, 1990

By Zhanjun Wang, Yongqi Sun, Mei Zhang, Zuotai Zhang, Min Guo

The role of fluorine on the viscous and crystallization behavior of CaO-SiO2-MgO-Al2O3-FetO-P2O5-(CaF2) slags were explored using the rotating cylinder method, non-isothermal differential scanning calorimeter (DSC), X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. It was found that the viscosity slightly decreased with increasing CaF2 content. It was also found that CaF2 addition can promote the primary phase transformed from MgFe2O4 spinel to Ca3(PO4)F, which was beneficial to the enrichment of phosphorus. Additionally, the structure of the slags explained by X-ray photoelectron spectroscopy (XPS) and magic angular spinning nuclear magnetic resonance (MAS-NMR) were further analyzed, which was well in accordance with the above analysis.

Jan 1, 2016

By Hiroyuki Sano, Chikabumi Yamauchi, Mitsuru Tanahashi, Toshiharu Fujisawa, Shin-ya Iwahori

"Pyrometallurgical process using Cu2O-based slag was proposed as a recycling process for copper scrap. However, it is difficult to remove nickel from copper by oxidative refining. Therefore, it is necessary to reduce the concentration of nickel in copper before the oxidative refining. In the present work, the copper enrichment stage in this recycling process, where copper scrap melt is separated into the Fe-C-Cu melt and the molten copper, was taken up and the compositions of both melts were measured. Based on the above results, the distribution ratios of nickel between the Fe-C-Cu melt and the molten copper were calculated. Furthermore, the optimum condition of copper enrichment stage was discussed from the viewpoint of nickel removal and copper recovery. The possibility of recovering 4N-purity copper by using this recycling process was confirmed.IntroductionRecycling is well known as a method for saving resources and reducing environmental damage. More than 99% of copper is used in metallic form - as metal or copper alloys[l]. High-grade copper scrap is directly re-melted and reused, while low-grade copper scrap is transported to copper smelters to be pyrorefined and electrorefined. Nevertheless, a great amount of copper is being stockpiled in the cities and should be recycled in the near future. At that time, the current recycling process will face new problems due to the increases in the recycling rate to the smelters. This includes insufficient combustion heat to melt copper scrap and ·almost no benefit in electrorefining because the scrap does not contain gold and silver. Thus, an alternative pyrometallurgical method for copper scrap refining will be required."

Jan 1, 2000

By Yan Beygelzimer, Alexander Spuskanyuk, Victor Varyukhin

"A cellular model of the plastic deformation of polycrystalline aggregate is proposed and comprehensively described. Representative volume element (RVE) of a solid body, that is being deformed, is described as a population of interconnected units that, in turn, can consist of lower scale level units. Sliding along the various allowed sliding systems deforms simple units, which do not have an internal structure. For consideration of stress distribution within the limits of components, the approach of self-consistent field is used. Rotation of units and moment stresses connected with it are taken into account. Results of computer experiments are analyzed.1. IntroductionMicromechanical models of polycrystals are a link between the research of plastic deformation on micro and macro levels. Computer simulation of inelastic strain of polycrystals has found a great deal of interest as well. Despite the fact that this approach does not allow to obtain macroscopic constitutive relationships that are used in deformed solid body mechanics, it clarifies essential features of the phenomena in many aspects. First of all, it concerns effects stipulated by interdependence of micro-level and macro level of plastic deformation processes. Also, with the computing mechanics, instead of constitutive relationships, the adequate computer models can be used. Broad possibilities for computer simulation of various processes are opened by cellular automata approach. By means of numerical experiments, the cellular automata allows to study the macro behavior of the whole ensemble of cells depending on the local microscopic laws that define evolution of each cell and its interaction with the closest environment.We propose a mathematical model of a polycrystalline aggregate (the cellular model) based on a self-consistent scheme and on the interaction law similar to the one by Berveiller and Zaoui [1]. Our original solution is the self-similar structure of cellular automata that allows modeling of the fractal nature of real materials (Figure 1). The goals of this work are to present the major structures and relations of cellular model of polycrystal and to test this model for its adequacy as for describing known effects and dependencies. Identification of the model and its application for studying of concrete polycrystals are put aside for the future research."

Jan 1, 2001

By G. Barbery

The models for particle composition prediction that have been put forward are limited to simple textures and lead to an independance of grade with respect to particle size in broken ore. A presentation is made of a modification in texture description; binary textures, in which each subeonstituent has its own breakage characteristics are introduced. The calibration of the textural model can be made using heavy liquid separation results. The application to the case of coal is presented. Coal washability data present spe¬cial difficulty due to the distribution in the specific gravity of coal, which must be taken into account. Coal s.g. distribution is taken as a generalized exponential distribution. Model calibration is then possible and is shown to be in good agreement with experimental data.

Jan 1, 1987

By R Bartlett

Process engineering-science originally developed for percolation leaching of ore in heaps is extended to the decontamination of unsaturated soil, either in situ or after excavation and emplacement as a soil heap on an impervious pad. Phenomena considered include: soil matrix porosity and permeability; percolating solution retention, capillarity and flow; washing sweep efficiency; optimum solution application rates during leaching; soil agglomeration to improve soil permeability and soluble contaminant transport by diffusion in soil agglomerates. Practical aspects briefly discussed include leach pad construction, solution distribution and recovery from the soil, and solution containment.

Jan 1, 1994

By Gang Qi

The solubility of nitrogen in pure molybdenum was measured over the temperature range 2173 to 2473 K and up to one atmosphere (101 kPa) of nitrogen gas pressure. Both thermochemical and kinetic aspects of this phenomenon were considered in this study. The solution of nitrogen in molybdenum may be expressed by the reaction 1/2N2(g) = {N} (Mo,s), for which the standard Gibbs energy is given by the expression {A}G° = 78,500 + 27.36T Joules/g atom N. The formation of molybdenum nitrides, specifically Mo2N, was considered. Attention was also focused on the mechanism of nitrogen solution in molybdenum. Estimates of the diffusivity of nitrogen atoms in solid molybdenum were derived from the kinetic data.

Jan 1, 1991

By M. Olper, M. Maccagni

"The crude zinc oxides (CZO) produced in any thennal process dealing with EAF dust also contain lead, cadmium, and a considerable amount of halides (chlorides and fluorides). The high halide contents make these crude zinc oxides less and less attractive, both technically and economically, and a further refining procedure is nece'ssary to meet the zinc and zinc oxide market requirements.Hydrometallurgical techniques commercially used to dehalogenate the crude zinc oxides are not effective enough to upgrade the crude zinc oxides to the required specification for their direct use in the traditional sulphuric electrolysis by primary zinc producers.The EZINEX® PROCESS has solved the problem of the halides contained in the crude zinc oxides. This process is the only proven technology electrowinning zinc from a chloridebased electrolyte in a conventional cell house. This paper discusses the process economics taking the data from feasibility studies of different size commercial plants."

Jan 1, 2000

By Hong Ouyang

A unified computational model has been developed for the Bridgman growth processes of B-NiAI and CdTe crystals. To handle the geometrical and physical complexities, a two-level approach has been developed. At the gtobatlevel, conjugate heat transfer, phase change dynamics, and variable material properties along with the realistic geometries and thermal boundary conditions are accounted for inside the entire crystal growth system. Refined calculations are then made within the ampoule, with the boundary conditions supplied by the global simulations. This model can optimize the use of computational source, help understand solidification behaviors, and improve designs of crystal growth system.

Jan 1, 1996

By M. S. Moats

The treatment of oxidized residues of zinc with high iron content continues to present a technical challenge in both the steel and zinc industries. Two main problems are commonly identified and include high treatment costs and environmental concerns about contaminated, iron-bearing residuals. A new approach to this problem is described in which selective separation of the iron and zinc into salable products may be potentially feasible. The waste material is first leached to give a solution having an approximate concentration of 110 g/l Zn, 15 g/1 Fe and 40 g/1 H2SO4 and other impurities such as Pb, Cd, Cu and Sb. A suitable organic, such as D2EHPA, is used to load the majority of the iron. The aqueous phase is then acceptable for zinc electrowinning after standard solution purification. The novel step in the flow sheet is the efficient recovery of the ferric iron from the organic solvent using a solid metal to reduce the iron to the ferrous state. The Fe+2 is easily stripped into an aqueous phase in a relatively pure form, suitable for use in water treatment. Process parameters and possible flow sheet designs are described and discussed.

Jan 1, 1995

By R. H. Hanewald

INMETCO, a subsidiary of Inco Limited, is the only facility in North America that provides High Temperature Metals Recovery for nickel-, chromium-, and iron-bearing wastes. Since 1978, this process has prevented more than 775,000 tons of materials from becoming part of the nation's waste stream. The paper describes Inco's experience in metals recovery, traces the development and explains the operation of the High Temperature Metals Recovery Process, and examines the procedures and criteria used to determine whether spent catalysts meet process feed specifications. An overview of the current requirements for transporting spent catalysts is provided. The paper concludes with brief case histories of catalysts users employing High Temperature Recovery to manage spent catalyst.

Jan 1, 1995

By S. Abe

Various copper anodes to be electrorefined were subjected to a heat treatment comprising annealing at a temperature in the range of 700 °c to 1,000 °c followed by a slow cooling preferably on the order of about 150 °c, and using these heat treated anodes , a series of dissolution experiments were conducted under conventional electrorefining conditions. The results obtained have indicated that the above annealing/slow cooling process dramatically improves the dissolution activity regardless of the type of anodes. As an example, passivation times of l to 3 minutes in a standard test have been increased to more than 80 minutes by this innovated heat treatment. Other advantages sterning from the improved anodic activity include reduced electrical short circuiting which results in substantial labor effort in the tankhouse, reduced energy requirement, and reduced cost of processing anode slimes because the amount of anode slimes is reduced. In addition, this process gives rise to a dramatic change in the nature of anode slime layer formed in such a way that a comparable final cathode copper product can be achieved even from high-impurity copper starting material.

Jan 1, 1987

By Steven C. Torma

The present article reviews some of the technologies available for recycling high-energy yield explosives loaded projectiles. These activities lead to reduction of military ammunition stockpiles and their conversion into commercial and industrial applications. The recycling technologies involve dismantling and separation of ammunition components into recyclable metals, plastics, paper and explosive materials. The metal 1 ic components will be sent to smelters, where they will be converted to products that can be used in a variety of industries, such as construction, automotive, housing and so on. Plastics and paper will be recycled and reused. Explosives will be recycled to be used for industrial purposes in the mining industry. Propellants (ammonium nitrate and ammonium perchlorate) can be ground to small particle size and treated to be used in the agricultural industry as fertilizer. In addition, some of the excess explosive material recovered in the demilitarization process may be incinerated to produce energy for steam production for heating purposes, or for production of electricity. Furthermore, this article reviews the developments in the bioremediation of explosive contaminated soils and industrial effluents.

Jan 1, 1994

By D. M. Dabbs

A static dew point technique has been used to evaluate the solubility of arsenic in ?slag and its dependency on P02 at temperatures of 1458 and 1523K. The ferrous-ferric ion ratio of the slags ranged from 3.9 to 23.8. These values correspond to partial pressures of 02 ranging from 10-8 to 10-12 atm. The solubility of arsenic in slag was found to be independent of? P02? The data indicate that elemental arsenic exists in silicate ?slags. This result was further substantiated by mass .spectrometric analysis of doped slag specimens.

Jan 1, 1983

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 Chonghun Han, Tae-Hwa Choi, Young-Hwan Chu

"A statistical optimization method is proposed to maintain stable operation in a blast furnace with stave coolers. The objective of this study is to find the operating condition which maximizes productivity as well as minimizes the heat load on the stave coolers. In this method, we first analyzed historical data and calculated the heat flux of stave coolers and the burden distribution by mathematical models. In this approach, we determined the variables to optimize and manipulated variables to adjust these response variables. Next, we collected the necessary data for the data variables after preprocessing such as removal of noise and outlier. Finally, we constructed empirical models describing the patterns of response variables in terms of manipulated variables by partial least squares regression method, and then these models were used as objective functions for entire optimization problem. By using appropriate optimization algorithm, we determined the compromised optimum operating condition considering all response variables from the past operating conditions.IntroductionBlast furnace operation which is accompanied by complex physical and chemical phenomena is an essential process for steel industry. In this process, iron ore which is charged into the blast furnace from the top goes downward. It is reduced to iron by CO gas and is melted by the heat of combustion of coke and pulverized coal. The pig iron is tapped at the bottom in liquid phase after removing the slag, which floats on the pig iron.The cooling equipment of the blast furnace wall is changed from the plate type to the stave cooler recently. In order to cool the shell uniformly and eliminate shell spray cooling, Pohang No.2 blast furnace of POSCO (Pohang Iron & Steel Company) was equipped with 11 rows of stave coolers. These staves are only 350mm-thick including the 170 mm-deep refractory on the hot face."

Jan 1, 2001

By Patrick R. Taylor

A kinetic study of the fluosilicic acid leaching of galena was performed under the presence of different oxidants. Fluosilicic acid concentration, agitation speed, concentration of solids and particle size, type and concentration of oxidant, and temperature were the variables studied. Hydrogen peroxide was found to be the most effective oxidant, its effectiveness being proportional to its concentration. As expected, an increase of leaching temperature increased the overall extraction and extraction rate. The same was found by decreasing the galena particle size. It is thought that leaching using hydrogen peroxide is controlled by fluid film mass transfer due to the calculated apparent activation energy. Reaction by-products such as sulfur and sulfur compounds retard the leaching rate. A mathematical model is proposed and compared to experimental results.

Jan 1, 2003

By Joel K. Witt

San Manuel Oxide operations of BHP Copper, located in Southeastern Arizona, operates a leach-solvent extraction/electrowinning (SXEW) facility that produces high quality cathode copper from low-grade oxide ores. Permanent heap leaching and in-situ leaching methods accomplish the dissolution of copper from the oxide ores. Open pit mining and heap leach construction took place from 1985 to 1995. Run-of-mine oxide ore from the pit was hauled to the heap dumps and leached by the soaking cure and continuous irrigation method. Solution application to the heaps still continues and acid soluble copper recovery has reached 86%. This paper presents and discusses the current operating practices and innovations applied to the leach facilities to maximize copper recovery from the heap leached residue. Factors such as irrigation methods, solution chemistry, sideslope treatment, post curing, lixiviant acid strength, and "rice paddies" irrigation, will be discussed. Heap leach solution control and sampling methodologies will be also presented.

Jan 1, 1999

By J. L. Watson

The composite nature of titanomagnetites found on the west coast of the north island of New Zealand is an important parameter in the beneficiation of the black beach sands for export to Japan. To investigate this composite nature, borehole and plant samples from the Waipipi Ironsands Ltd property were subjected to a series of separations in heated Clerici solutions at densities varying from 3.2 to 4.6 g/cc. The resulting density fractons were analyzed magnetically and a set of distribution curves for composite grains proposed. In addition the experi¬mental data was plotted to produce titanomagnetite sand 'washability curves" which illustrate the possible problem areas in beneficiation that may arise due to composite titanomagnetite grains. From this data a set of guidelines are suggested for interpreting the curves in terms of ease of gravity concentration. The composite nature or liberation of titanomagnetite grains is shown to favor high and low grade composites with few intermediate compositions being isolated. The relationships between grain size, borehole depth and liberation are examined and related to beneficiation procedures for the black sand deposit.

Jan 1, 1982