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By Keith E. Forrester

This paper presents results of laboratory and field optimization of a proprietary processes developed by FESI for the stabilization of heavy metal bearing wastes. The specific waste studies presented within the paper include foundry ash, aluminum sweat furnace ash and a heavy metal contaminated soil. The FESI process chemistry and engineered processes were found to be the most cost efficient demonstrated and available method of stabilizing heavy metals and highly successful in passing regulatory limits.

Jan 1, 1994

By S. W. White

Plasma arc technology is increasingly being used to process a number of waste materials. In present research, plasma technology is being investigated to treat waste magnesium baghouse dust, which is a waste material from the Magnetherm process. This dust contains mostly MgO, but also contains NazO, CaO, and KzO. Plasma energy is to be used along with a reducing agent to produce pure gaseous magnesium while keeping the other materials in a slag. The magnesium will then be collected by rapid quenching. A non-transferred arc plasma torch is ideal for this reaction because of its high enthalpy and improved energy efficiency over conventional methods. Another advantage of plasma is that it allows for the pre-heating or pre-reacting of fine particles before contact with the melt. Thermodynamic calculations using the Gibb energy minimization method were used to determine the most stable compositions of the materials at various temperatures. Energy balances have also been calculated. These results conclude that we can recover approximately 98% of the magnesium with a proper quenching technique. The calculated results are compared with the experimental data, and good agreement between them was observed.

Jan 1, 1999

By Lisa E. Helberg

"Titanium tetrachloride is produced through the chlorination of a variety of titanium bearing ores, some occurring in nature, and others enriched in titanium content by a variety of ""beneficiation"" processes. The chlorination step can produce a variety of metal chloride impurities, such as iron chlorides and vanadium chlorides, which must be removed from the TiC14 before it can be used to produce pigmentary TiO2, titanium metal or for any other commercial use. The requisite manipulations involve both physical and chemical separations in a multi-step process. The history of various purification strategies will be discussed.TextThere are a wide range of titanium-based products available, all of which start with titanoferrous ore of some type. Two main routes are used to convert ores into products, known as the sulfate and chloride processes. The sulfate process uses sulfuric acid to digest the ore, separate the impurities, and then precipitate titanium dioxide from the resulting titanyl sulfate (TiOSO4) via metatitanic acid. This process can also supply TiOS04 for other applications."

Jan 1, 2011

By W. D. Cho

Fast dissolution of nonmetallic inclusions such as alumina particles in molten slags has been required in secondary steelmaking -ladle and tundish - to minimize the amount and the size of nonmetallic inclusions in steel products. In the present work, the dissolution behavior of alumina particles in molten CaO-A12O3 and CaO-A12O3-SiO2 slags at the temperatures between 1450 and 1550°C have been investigated in terms of kinetics and mechanism. Alumina particles were added directly into the slags and the variation of the particle size with time was determined using optical and electron microscopies. The conventional types of slag for ladle and tundish were included in the dissolution study. The effects of Al2O3, Siq, CaF2 and MgO contents on the dissolution rate of alumina particles have also been determined. The diffusion boundary layer between alumina particle and bulk slag phase has been observed and analyzed using SEM and EDS. Based on the analysis of kinetic data and the boundary layer, the dissolution mechanism has been discussed.

Jan 1, 2002

By C. Lupi

Electric arc furnace dust generated during the production of steels is regarded as hazardous waste because of the presence of leachable elements such as Cr, Pb, Cd .... Different processes are available according to the management policy chosen by the steelmaker: disposal. recycle and/or recovery. The feasibility of an hydrometallurgical Zn recovery process on fumes generated during the pyrometallurgical treatment of EAF dust has been investigated. The recovery of metallic iron, chromium and nickel as molten metal provides fumes very rich in zinc oxide ( 63.1% ) and poor in zinc ferrite. This secondary dust is still an hazardous waste and represents the raw material for the recovery of Zn and Pb. The waste material is first leached in 1.5 M sulphuric acid at 30°C to provide a Zn, Fe and Mn rich aqueous solution and a Pb and Ca sulphate rich sludge. The iron is eliminated by precipitation because is harmful to the following electrowinning process. The ftltered and purified leached solution is acidified in order to obtain good electrowinning conditions. A pure cathodic deposit of zinc is then produced in an electrolytic cell at laboratory scale.

Jan 1, 1996

By Jean-Christophe Gebelin, Mark Jolly, Samantha Jones

"The de-waxing process in investment casting is truly a black art which is carried out in a black hole - the autoclave. The process involves exposing wax, coated by a porous ceramic shell, to steam at a pressure of 10 bar and a temperature of about 180°C. The processes which then occur are truly multi-media and multi-physics. Steam condenses in the porous ceramic, wax melts and flows, the shells expand and sometimes crack. Why the shells crack is one of the most difficult questions asked in the industry.Modelling and validating the de-waxing process is not simple. The IRC at the University of Birmingham is attempting to model this process using Physica+ a code developed in the UK. This paper will present the latest results in this attempt to model one of the casting industries most intractable problems.IntroductionThe de-waxing process using an autoclave involves the following physical phenomena:· Flow of the steam in the autoclave;· Heat transfer from the steam to the wax, possibly through the shell;· Melting and flow of the wax.At the same time, other phenomena may occur, such as the flow of the steam through the shell, the condensation of the steam on the shell surface and on the wax pattern surface, the flow of wax the through the shell, etc ...This shows how complex the de-waxing process is from a physical point of view. The main defect that appears during this process is the cracking of the shell. Previous modelling work carried out by Snow [1] has shown that it is possible to predict the stress in the shell, making numerous assumptions. In this paper, the modelling to predict the state of stress in the shell that is currently in development at the University of Birmingham is presented together with the presentation ofthe physical phenomena to model and the assumptions used. The parameters that are needed in such models will also be discussed, and some experimental work undertaken at the moment presented."

Jan 1, 2001

By Sadi Medina

As it is characteristic from Custom Smelters, ENAMl Las Ventanas Smelter has to deal with different qualities and quantities of mining products from about 70 suppliers, that contain a variety of impurities that would be harmful for copper production. In order to increase the smelting capacity, an oxygen plant has been running since September of 1990. Moreover, to improve the environmental conditions, a new sulphuric acid plant started up to neutralize the metallurgycal off-gases from the Teniente Converter and partially from the Peirce-Smith converters. Based on the on-line operation among the reverberatory furnace and the Teniente Converter using oxygen enriched air to produce high grade matte, most of the volatilizing impurities, mainly arsenic, are collected as discarding compounds in the gas cleaning system of the acid plant. This paper describes the continuous performance of the Teniente Converter with acid plant, the results attained, the operation problems and how they were solved. The impurities distribution achieved in this process is also included.

Jan 1, 1993

By Gary A. Wickham

In the zinc industry, this past decade has seen both prosperity and depression. Significant changes have occurred throughout the world in mining, smelting, refining, and marketing. This paper will review many of the industrywide changes of recent years and the potential impact for 1990s. In addition to an historical review of supply and demand are discussion of technology considerations for zinc and zinc based products, effects of geographical shifting of markets, and projections for the 1990s.

Jan 1, 1990

By Edgar E. Vidal, Keith Smith, James A. Yurko

Beryllium, like many other reactive metals, is extracted from a halide (generally BeF2) using magnesiothermic reduction, also known as the Kroll process. The beryllium is produced in a molten state, which when solidified resemble "pebbles". Although beryllium is used in limited quantities compared to other metals (< 100 Mt/annual), it is a critical material for the nuclear, defense/aerospace, and large science markets because of its unique nuclear and mechanical properties. Beryllium processing has unique environmental, health, and safety concerns which must be handled appropriately in the 21st century from a worker and environmental safety perspective, and must be designed with this first in mind. In 2011, Materion began operations of its new Kroll plant – informally known as the “Pebbles Plant” - in Elmore, Ohio. The plant was majority funded by a U.S. Department of Defense Production Act (DPA) Title III grant, which is a unique government/industry partnership program to, "create assured, affordable, and commercially viable production capabilities and capacities for items essential for national defense." After a twelve year hiatus from primary beryllium production, Materion has reentered its extraction business and has relearned how to make pebbles. The purpose of this presentation is to give an overview on beryllium extraction and discuss some of the unique aspects of building and operating a safe beryllium facility during the production scale-up phase.

Jan 1, 2015

By G. Belardi

A study has been conducted to assess a new wet beneficiation treatment for the recovery of the sulphuric-acid-soluble titanium oxide contained in the waste from an Italian TiO2-pigment facility. The waste is produced during treatment of a Ti-enriched slag and contains as main components TiO2 (54%, of which 42% acid-soluble and 12% insoluble), SiO2 (27%) and A1203 (6%). Eighty percent of the material is finer than 50pm. The first step was to ascertain the possibilities offered by size classification, wet gravity separation, froth flotation and wet high-intensity magnetic separation to improve the grade and recovery of Ti02 and reduce the SiO2 content. The next step was to optimize the operating conditions of the various separations and assemble them into a complete flow- sheet. Beneficiation ensures potentially 70% recovery of the TiO2 with a concentrate grade of 80%.

Jan 1, 1998

By M. I. Novgorodova

Most of the gold in the earth&apos;s crust occurs as finely-dispersed gold and accounts for much of the gold lost in extraction processes and during exploration for gold. The Compositions, sizes, and morphology of fine gold particles (0.01 to 10 ~m in diameter) were studied with high resolution electron microscopy coupled with electron microprobe and microdiffraction devices, using colloidal carbon replicas. Correlations were made between fine gold, mineral associations and ore genesis. The results provide qualitative information on the proportions of finely dispersed, invisible and visible gold distribution in ores. Such knowledge is fundamental when planning an optimum technological recovery process.

Jan 1, 1991

By Evan O. Jones

Processes involving distillation under reduced pressure were developed at the Pacific Northwest Laboratory several years ago to recover spent acid solutions generated during the manufacture of nuclear fuel for the N-Reactor at the Hanford site. Following construction and testing of a pilot-plant, the technology was licensed to Viatec Recovery Systems, Inc. for commercialization. The technology developed included specialized distillation and rectification of volatile acids, removal of water and/or volatile acid from sulfuric acid, and precipitation of salts. A key feature of the Waste Acid Detoxification and Reclamation (WADR) technology is the development and use of advanced thermoplastic and fluoropolymer materials of construction in all critical process equipment. The technology was then expanded to include crystallization to recover metal salts for possible reuse. Economic and environmental advantages of the procedures include recovery of acids for reuse, simplification or elimination of the disposal of waste solutions, and possible recovery of metals. Industries expected to benefit from such applications include galvanizing, electroplating, sand leaching and any where metals are cleaned in acid solutions. Currently a modular system has been assembled for recovery of several different spent acid solutions.

Jan 1, 1995

By S. J. Gerdemann

The U.S. Bureau of Mines is studying the kinetics of wet oxidation of sphalerite concen- trate (ZnS) as a possible process for a gravity-pressurized reactor (GPR). At tempera- tures in excess of 200&apos; C, a sphalerite water slurry will react with 0, to form zinc sul- fate (ZnSO,). However, the pressure required to keep the water from boiling at these temperatures has kept this reaction from becoming a viable continuous process. The GPR can easily obtain the high pressures required for this reaction. The reaction rate is complicated by the solubility of 0, in water and the further oxidation of ZnSO, to insoluble zinc oxysulfate (Zn4(OH),S04.4H20). The effects of pressure, temperature, and particle size on the rate of reaction were investigated. Reaction rate was found to be limited by the amount of oxygen in solution. However, at 250" C and 1500 psia, over 90 pct of the zinc was solubilized in less than an hour. The conditions for maxi- mizing the Zn++ in solution, while minimizing oxysulfate formation, are discussed.

Jan 1, 1993

By Jian Pan, Zhen He, Deqing Zhu, Shouyan Yue

"The differences of raw material characteristic among six kind of iron concentrates and the influences on ballability were studied from the aspect of the size distribution, specific surface area and particles morphology. The results show that the specific surface area of iron concentrates has crucial influence on ballability, and the effective method of improving ballability for weak ballability iron concentrate has been found. It is of important guidance for Chinese steel mills to import and use iron concentrate from the whole world.IntroductionChina's steel industry has developed rapidly in recent years, crude steel production in 2011 is an unprecedented 683 million tons, which is almost half of the world crude steel production, and it is equivalent to the total sum production of the nations which rank at 2,3,4,5 and 6 in the world [1]. In order to match the development of steel industry, the blast furnaces are becoming larger and more modernization, therefore charging burden of higher quality is requested, and the reasonable blast furnace burden structure is more and more important, at the same time, for iron ore powder sintering process's continuous improvement and development, another method providing ""concentrate"" for blast fumace-pelletizing is also taken seriously. The grate-kiln method of pelletizing has achieved great development for its unique advantage, and in just a few years, there are over 60 rotary kiln production lines have built or being built in China, the sum of pellets has reached to more than 140 million [2, 3]. The rapidly growth of pelletizing yield demands diverse source of pellet, which include not only domestic magnetite concentrate, but also imported hematite which is high in iron and low in silicon. Usually the ratio of imported hematite concentrate increased gradually. The imported hematite concentrate has high grade and fine particle size (the content of -0.074 mm mostly higher than 90%), but the ballability of part of the concentrates is poor."

Jan 1, 2013

By A. D. Zunkel

The zinc in electric arc furnace dust (EAFD) arises from the fuming and oxidation of the zinc present, mainly as galvanizing, in automotive scrap. The dust is collected from the electric furnace offgases in bag filters and is classified by the EPA as a hazardous waste (K061). As more zinc is used in galvanized sheet on automobiles and more automobile scrap is recycled via the EAF, the more zinc will be available for recovery and recycling. EAFD will become a more prevalent and important source of zinc compared to the traditional zinc sulfide concentrates ifit can be cost effectively processed.

Jan 1, 1995

By Dan Mancuso

This case study is an example of how Encyle/Texas, Inc. (a subsidiary of ASARCO) responded to various socio-economic forces by converting an idle zinc hydrometallurgical refinery into a metals recycling facility. The facility accepts metal-laden process waste streams and produces various "synthetic ores" which are sold back to industry. Acceptance and reactions by industrial, political, economical and regulatory interests towards the project are also discussed.

Jan 1, 1992

By Chang Wei, Fan Zhang, Zhigan Deng, Minting Li, Cunxiong Li, Gang Fan, Xingbin Li

Marmatite is an important resource of zinc, which exist in forms of high iron and high indium. In order to recycle the valuable metal from these ores, the testwork of simultaneous leaching on neutral residue mixed with zinc concentrate of high iron and high indium has been conducted. The primary objectives are to leach the zinc and indium remaining in the neutral leach residue as ferrite using acid, and to reduce the ferric iron in solution to the ferrous by zinc concentrate, thereby extracting the zinc and indium in the zinc concentrate. The results indicated that in the following conditions, mass ratio of neutral residue to zinc concentrate of 1:0.25, particle size of 74-58 μm, initial sulfuric acid concentration of 150 g/L, liquid to solid ratio of 8 L/kg, temperature of 90°C, reaction time of 4h, the leaching efficiency of zinc and indium were over 95%, nearly 90% Fe was Ferrous in the leaching solution. This process effectively extracted zinc and indium and converted Fe3+ into Fe2+ in solution, and simplified the traditional process of reduction after leaching.

Jan 1, 2016

By Maria Leikola, Joseph Hamuyuni, Petteri Halli, Fiseha Tesfaye, Mari Lundström

In a race to save the planet of its rapidly depleting natural resources, the use of Secondary Raw Materials (SRMs) as replacements in several processes is currently intensively pursued. In fact, this is currently one of the European Union (EU)’s mandates. Valorization of SRMs is consistent with circular economy, where resource efficiency is maximized for the benefit of both businesses and the environment. In line with this mandate, this paper focuses on investigating process phenomena related to hydrometallurgical recycling of Electric Arc Furnace (EAF) dust. In the experimental study, selective dissolution of zinc and other metals is investigated to acquire a recyclable leach residue. Based on the experimental and theoretical investigations, zinc could be extracted from the EAF dust and a recyclable leach residue produced, having chemical composition suitable as a feed material into electric arc furnace.

Mar 1, 2018

By Philip L. LeHoux

"Kennecott Barneys Canyon Mining Co. is a gold heap leaching facility that has been in operation since 1989. In 1994, a flotation plant was commissioned to remove sulphide minerals from refractory sulphide ore. Tailings from the plant are mixed with oxide heap leach material in order to produce a geotechnically stable agglomerate from which the gold is leached and recovered in a conventional heap leach cyanidation process. The experience to arrive at an effective blending methodology is discussed.IntroductionAgglomeration is the practice of binding fine particles to coarser rock or other fines in order to avoid the deleterious effects of mobilizing the fines during the course of heap leaching(l-Chamberlin). Agglomeration has been considered a key component of successful operation at many heap leach sites. If the ore is of sedimentary origin and crushed, there is a high likelihood that the resulting product will contain a significant quantity of fines and a skewed gradation, that i~, a disproportionate amount of coarse and fine particles, with few in the intermediate size range. The exact methodology for determining whether the practice of agglomeration will have to be integrated into the operating scheme has been well discussed. These conditions are primarily geotechnical and geochemical. This paper will deal with the specific experiences of Kennecott Barneys Canyon Mining Company in modifying the agglomeration practices to suit evolving operational requirements."

Jan 1, 1997

By James J. Komadina, Robert R. Beebe

"Heap leaching of gold ores has enjoyed wide acceptance in the arid and semi-arid regions of the western U.S., Australia and South America. There are areas, however, where cold weather or excessive precipitation can limit the usefulness of heap leaching. Even in Nevada difficulties can be encountered which call for special operating procedures.The paper discusses the general climatological limitations and some of the techniques used to extend heap leaching into colder conditions. A case history of the Cripple Creek and Victor Gold Mining Company operation in Colorado examines 'valley-fill"" technology as an ideal cold-climate solution, where topographical conditions permit.AcknowledgementsThe authors gratefully acknowledge the management of Independence Mining Company for their permission to present this paper. The contributions of Golder Associates; Pikes Peak Mining Company Environmental Affairs Department staff, and the Colorado Department of Mines and Geology were all invaluable in successfully concluding this project.BackgroundWhen heap leaching of oxidized gold ores was introduced in the rnid-1970s it was aimed at large tonnages of low-grade material which could not, in general, be developed via conventional milling. Normally, the reasons for this were economic rather than technical: capital and operating costs for milling were simply too high. At first, grade was almost the only criterion, but deposits too small to justify milling were also potential targets for heap leaching.Renewed interest in gold was centered in the western United States and Australia, where exploration for milling-grade deposits had never really died. When heap leaching came along, it was in these areas that the first developments took place. Coincidentally, these same areas were favorable for heap leaching: climates were temperate for most of the year and competing land uses were limited. Even so, in the western United States in particular, winter temperatures were low enough to complicate operations. Precipitation was less a problem, although heavy snowfalls could periodically interfere as well."

Jan 1, 1997