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By John C. Taylor

With growing emphasis on energy conservation and increased concern over the presence of heavy metals in the environment, it is fortunate that most metals are readily recycled. In this respect, metals have a significant advantage over plastics and similar materials used as metal substitutes. For many years a secondary industry has processed scrap copper, nickel, lead and zinc to produce refined metal which has, to varying degrees, influenced the price and displaced the production of primary metal. This paper reviews some of the challenges the industry will face and the changes in process technology which will be required as pressure mounts to increase the amount of metal recycled. In the case of most base metals, this will have an impact on primary metal production; as the tonnage of metal recycled increases, the requirement for primary production, or new metal, will depend more and more on the growth in consumption.

Jan 1, 1993

By Sergio Sanchez-Segado, Yuan Zhang, Animesh Jha, Ahmad Fahmi Ruzaidi

Niobium and tantalum are considered critical materials because the increasing demand in the energy sector which is reliant on limited abundance of these two metals in minerals. Traditionally, niobium and tantalum mineralsare digested using hydrofluoric acid at moderate temperatures, producing oxy-fluorides which are separated by solvent extraction, involving the use ofhazardous chemicals. The increasing environmental pressures are forcing the industry to search for alternative low carbon processing methods. In this paper alkali roasting based separation and beneficiation, which is not well understood in the literature, is proposed, for which the kinetics and thermodynamic equilibria for the formation of sodium tantalate and niobate with sodium hydroxide are analyzedat the temperature range of 400ºC to 700ºC. The apparent activation energy of formation,changes from 31.0±0.8 to 22.3±1.2 kJ mol-1 and from 23.8±1.2 to110.2±12.8 kJ mol-1, for tantalate and niobate, respectively. The reaction mechanism is examined on the basis of the analysis of reaction products using X-ray powder diffraction (XRPD) and X-ray fluorescence (XRF).

Jan 1, 2015

By D. E. Karvelas

Argonne National Laboratory is conducting research to develop a cost-effective and environmentally acceptable process for the separation of high-value plastics from discarded household appliances. The process under development has separated individual high purity (greater than 99.5%) acrylonitrile-butadiene-styrene (ABS) and high-impact polystyrene (HIPS) from corruningled plastics generated by appliance-shredding and metal-recovery operations. The process consists of size-reduction steps for the commingled plastics, followed by a series of gravity- separation techniques to separate plastic materials of different densities. Individual plastics of similar densities, such as ABS and HIPS, are further separated by using a chemical solution. By controlling the surface tension, the density, and the temperature of the chemical solution, we are able to selectively float/separate plastics that have different surface energies. This separation technique has proven to be highly effective in recovering high-purity plastics materials from discarded household appliances. A conceptual design of a continuous process to recover high-value plastics from discarded appliances is also discussed. In addition to plastics separation research, Argonne National Laboratory is conducting research to develop cost-effective techniques for improving the mechanical properties of plastics recovered from appliances.

Jan 1, 1996

By Peter G. Mason

Over the last 15 years numerous Pressure Oxidation and Pressure Leach plants have been installed throughout the world. The technology is no longer regarded with awe and trepidation as plants designed to treat a wide range of feedstocks continue to be successfully brought on line. Important aspects of the design of such plants include feed preparation, slurry pumping, heating and heat recovery, pressure control and let-down, vessel design, safety and provision of associated services.

Jan 1, 1999

By James W. Reeves

DuPont was the titanium metal pioneer who put the greatest effort into both R&D and commercial sponge and powder metallurgy production. This was concentrated in the period 1945 through 1963. The commercial results were development of the chloride process for TiCl4 using ilmenite, development and improvement of the Kroll process, development of a modified Hunter process to make titanium powder and commercial development of a direct powder process. The powder metallurgical process failed because of the inability to meet powder chloride specifications. All this work remained a trade secret until published in NMAB -392 by Mahla in 1983. There were other processes explored by DuPont, both improved sponge and powder processes. Much of this work has been continued by others but none, as of yet, resulting in new improved titanium metal capacity.

Jan 1, 2001

By W. P. lmrie

The recent years have seen many copper smelting operations become uneconomic due to a combination of low metal prices, high energy and labor costs, environmental requirements and high investment costs for modernization or replacement. Since a copper commodity requirement remains, the industry will recover, but many operations will need to determine which processes can offer the best prospect for economic operation and readiness for reliable investment and implementation. Corporate investment decisions involve the judgment of many factors in addition to topical technical aspects. Consideration of plant management and operational aspects are thus included. Taking account of such proven processes as conventional, flash and continuous smelting, plus modified conventional and new unproven processes, this paper gives a systematic approach to aid optimum choice for a modernization or grassroots investment. Actual achievements in energy form alternates, conservation and cost effectiveness are highlighted, and areas of remaining potential for energy saving are discussed.

Jan 1, 1983

By C. Kathryn Sole

The close proximity of cobalt and nickel on the Periodic Table and their frequent occurrence together in nature means that their separation in primary hydrometallurgical flowsheets is not only often necessary, but requires the use of innovative chemistry to achieve high selectivity. Today, increasingly stringent demands for the high-purity cobalt and nickel salts required for battery applications in consumer electronics, electric vehicles, and solar applications are again challenging the state of the art. The evolution of cobalt–nickel separations is traced from the basic precipitation technologies employed in 1960s, through commissioning of the first cobalt solvent-extraction plant in South Africa in 1974, to the commercialisation of organophosphinic-acid extractants (which provided a step-change improvement in selectivity) and their eventual widespread use in the 1980s and ’90s. This was followed later by their sulphur analogue, which enabled different possibilities for laterite processing in the new millennium. Separations in chloride media, which take advantage of the different speciation chemistries, and nickel extraction by oximes in ammoniacal systems are also discussed. More recently, chelating and solvent-impregnated resins have added further dimensions to the possibilities for flowsheet design and enabled higher purity products to be attained from both primary and secondary sources. Selected case studies and flowsheets are described.

By G. H. Khoe

Neutralisation of acid uranium mill tailings with lime or other alkaline materials is usually practised to reduce the dissolved concentration of heavy metals and radio nuclides. Computer modelling of this process was carried out using the geochemical equilibrium code MINTEQA2. Computed dissolved metal and sulfate concentrations were compared with laboratory-based experimental data. It was found necessary to include the modelling of adsorption of trace metals (such as uranium and lead) by the precipitated ferric hydroxide in order to obtain acceptable concentrations in the neutralised liquors. There were limitations of the modelling exercise due to important aspects which were not addressed or properly accounted for such as chemical reaction kinetics and the effect of high ionic strength. These are discussed in the paper.

Jan 1, 1991

By L. J. Cabri

The level of mineral exploration activity for platinum in recent years, especially in North America, has ranged widely. Exploration programs have been based on a variety of ore deposit models and deposit types. These range from the classic magmatic model for sulfide/oxide deposits and their associated placers, through hydrothennal models for bonanza-type deposits, to low-grade mineralization potentially amenable to lower cost bulk mining methods. The platinum-group element (PGE) distribution in these different deposit types is not well-known however, and PGE determination is fraught with analytical difficulties. To properly assess a prospect or to achieve effective recovery by mineral processing, it is important to determine the mineralogical distribution of the PGE.

Jan 1, 1988

By Marco Olper

After two years of extensive research a new and innovative modification to the CX-EW process has been exploited. This process, called CX-EWS, avoids completely all the critical aspects of the previous process which affected the cost of the energy, of the chemicals and of The maintenance of the insoluble anodes. All these benefits reflect a saving of about 30% of The operating costs compared to the present traditional production and allow for a total operating costs of less than 6.5 cts/lb. lead (net of raw material cost). With this new technology it is allowed for the first time the treatment in the same plant facilities of both primary lead sulphide concentrate and spent batteries. The paper describes the technical and economical aspect of the new process with a feasibility study for 150,000 t/y spent battery facility throughput.

Jan 1, 1995

By Debbie Marshall

Nickel and cobalt in lateritic ores can be extracted by either a hydrometallurgical or a pyrometallurgical route. The high-iron limonitic fraction of a deposit is best processed' hydrometallurgically while the magnesium-rich transitional and saprolitic fractions are more suited for pyrometallurgical processing. During hydrometallurgical processing, it may be attractive, for economic reasons, to blend the limonitic component with transitional and saprolitic ores, which contain higher nickel levels. However, blending increases the concentration of magnesium in the feed, leading to increased acid demands. The decision on how much ore to process then becomes an economic one. Ore samples with different magnesium contents were prepared for the leach test program by blending limonitic and transitional ores. The ore samples were slurried in seawater and tested in the Falconbridge Hydrometallurgical Pilot Plant. As expected, acid consumption increased with increasing magnesium content of the ore. For target extractions of 95% nickel and 92% cobalt, the required residual free acid concentration increased from 30 g/L at 1.7% magnesium to 50 g/L at 2.7% magnesium. When the magnesium content was raised to 3.8% and 4.6% in subsequent pilot plant testing, the final free acid requirements did not increase beyond what was observed at 2.7% magnesium. Thus, the cut-off ore composition to maximize nickel units and minimize acid requirements is between 1.7- 2.7% magnesium. Keywords: high pressure acid leaching, laterites, magnesium

Jan 1, 2004

By F. W. H. Dean

A very sensitive sensor for the detection and measurement of hydrogen in solid steel is described. This technique is non-invasive and uses a collector to sweep the hydrogen emanating from a steel surface and feed to it sensor. This method is particularly sensitive, resolving fluxes to < 2 pI cm?2 S?I, with a linear measurement up to 1000 pI cm&apos;2 S?I, The collector is held on the steel substrate by magnets and it is shown that emanation of hydrogen from the steel is controlled by bulk diffusion of the hydrogen through the steel. The technique is demonstrated to have an excellent response time and reproducibility.

Jan 1, 2001

By N. L. Piret

Reprocessing of low zinc-bearing residuals with a zinc content of less than 10%, originating from the iron and steel industry, has been given more and more attention in the last few years, due to the potential landfill liability and the increasing cost of disposal by dumping. Whereas, recycling of hazardous electric arc furnace dust is already being performed commercially on a large scale in the U.S., Japan and Western Europe, almost no reprocessing takes place in the case of these low grade zinc-bearing materials. In blast furnaces and basic oxygen furnaces dusts and / or sludges are generated at a rate of 1 to 2 % of the respective production. The technologies for the retreatment of these types of materials, either commercially available or still being developed are briefly described hereafter. They involve internal recycling, upgrading by physical separation methods, separate hydrometallurgical processing and pyrometallurgical treatment. Their scope and limitations are critically assessed in terms of technological applicability, economic feasibility and environmental compatibility. Since, the possibtlity of achieving economic profitability is unlikely with this type of material, the main criteria for acceptability of the treatment process are: generation of a iron-rich material, suitable for treatment by the iron/steel industry, acceptance of the non--ferrous metal-bearing sub-product by zinc smelters, generation of non-hazardous waste materials.

Jan 1, 1992

By Robert M. Leary

The Kennecott Utah Copper smelter operates two Outokumpu flash furnaces: a smelting furnace for production of high-grade matte and a converting furnace for production of blister copper. Flash furnaces typically possess several characteristic features that must be considered in process control development such as long lag times associated with settler volume, non-linear input and output responses, large process gains, and unmeasured disturbances. Additionally, the Kennecott smelter possesses certain unique characteristics which must be considered such as single mine concentrate source, limited concentrate blending capacity, and feed preparation facilities that inevitably cause significant lags between furnace control parameters and manipulated set points. In order to improve furnace control and on-line time, a process control system was developed to address these issues. The feed forward control module provides predictive control and operates in response to furnace feed input changes. The feed back control module provides responsive control and is based on furnace output deviations. To provide regular feed back information to the control room supervisors, new sampling methods were developed which provide the operators with molten metal and bulk material samples at regular intervals to provide information for control. The control system was implemented on the Flash Converting Furnace in May 1999 and on the Flash Smelting Furnace in August 1999.

Jan 1, 2000

By Xiaojie Gao, Shufeng Yang, Jingshe Li, Chengsong Liu

In the blast furnace process, the dust entrained in the blast furnace gas enters into the down-comer, flows through the gravity dust separator (to eliminate coarse particles) and then is collected in a bag-house. The powder collected by the baghouse is called bag dust, while both fractions are called blast furnace dust whose main components are C and Fe. The dust also contains small amounts of nonferrous metals such as Zn and Pb, which have some value. Also, due to the small particle size and low density the dust is easily suspended in air and so can endanger human health. Therefore it is necessary to develop a process to both treat the dust to recover the metal values and to dispose of the residue – preferably by recycling to the blast furnace itself via the sinter strand. These objectives will result in good economic, environmental and social benefits [1].

Jan 1, 2014

By E. S. Geskin

"This paper is concerned with the construction of a formal technique for the selection of a metallurgical technology. Exergy consumption is used as the criterion of process efficiency. Different items of the exergy balance are considered and techniques for the reduction of exergy consumption are determined. The selected techniques of exergy saving enable us to identify processes which should be used at different stages of steelmaking. The combination of the selected processes enables us to suggest a technology for conversion of iron ore into steel products. The selection of this technology narrows the range of further search of metallurgical processes. The paper shows that qualitative thermodynamic analysis can be used as the first step in the design of metallurgical processes. IntroductionThe existing processes for making, shaping and treating of steel enable us to convert the available iron bearing ores into marketable steel products. However, the energy cost of metal production is much higher than thermodynamically required, while the metal properties are much lower than thermodynamically available. Increasing cost and declining availability of energy and raw meterials make the creation of new steelmaking technologies imperative. In recent years, the number of novel processes for the making, refining, and shaping of steel have been suggested and tested. Some found a practical application. However, the tested technologies make up a small portion of the physically available routes for the conversion of iron ore into a marketable product. It is also not evident that the optimal routes have been tested and that the selected technologies are the best among those tested.Although the development of new metallurgical technologies must be based on the experimental and practical information, the number of the alternative routes for the making, shaping and treating of steel, as well as the cost of examining each single route, make necessary the use of analytical techniques for the evaluation of the possible ways of process development."

Jan 1, 1988

By Patricio Barrios

In February 1996, ATLANTIC, COPPER completed the construction of a Project for Expansion and Environmental Improvements in its Smelter and Electrolytic Refinery located in Huelva. Following the expansion, the new operating concept is based on the simultaneous blowing of two converters, while increasing throughput in the Flash Furnace up to the level required to deliver matte to both converters. While the production level planned with the Project.(270,000 MTPY of copper from concentrates) was reached the following June, work since then has been carried out to optimize the new equipment .and to develop a new operating shedule. This paper describes operational experiences from the start up of the Expansion Project, difficulties encountered and operating improvements introduced, which have allow an increase of production levels up to 300,000 MTPY of copper.

Jan 1, 1998

By Jilai Xue, Jun Zhu, Liang Liu

"Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice with a heating process causing large energy consumption and high production costs. In this work, the floatation separation at room temperature were carried out using two types of skarn scheelite ores. The results showed that CaO and Na203 are better than NaOH as a regulator in pH value. In the rough floatation and first cleaning floatation, CaO (500g/t), Na203 (3000g/t) were used as a pH regulator, waterglass (4000g/t) was as a gangue depressant, oleic acid or sodium oleate were used as a collector. The degree of the obtained W03 concentrate was more than 65% (commercial product).IntroductionThe mainly gangue in scheelite are quartz, calcite, barite and some rare metal ores. There are three main types of scheelite for floatation: scheelite--quartz (silicate minerals) type, scheelite-calcite/ fluorite type, scheelite--calcite/fluorite/barite type. Generally speaking, scheelite--quartz type is separated easily, and others are difficult, on the contrary. The last two kinds of scheelite are always called scheelite--calcite/fluorite (barite) type, because there are similar floatation ability and floatation process between them. Scheelite, calcite and fluorite have same cation - Ca2+, it makes them have close floatation property [1]. Separation removal of fluorite and calcite from scheelite is a difficult technical operation in current industrial practice.The traditional separation method is a heating floatation process (Petrov's process) [2]. It can deal with many kinds of scheelite, and can be obtained stable quality ofW03 concentrate. On the other hand Petrov's process causes large energy consumption, high production costs and bad operational environments. Since 1980s, scheelite ambient temperature floatation has become the mainstream of study [3]. Nowadays more and more studies on scheelite floatation focus on complex reagent system [4, 5], rigid operating rules and at the same time development new regulator [1, 5]. Some research show there are new regulators can concentrate scheelite efficiently, but it may cause high costs, potential pollution and difficulty to spread. Oleic acid and sodium oleate used as collector have high adsorption capacity to scheelite, but same to calcite and fluorite[6]. So, it would not get ideal effect for separation of scheelite. In this work, the floatation separation at room temperature were carried out using two kinds of skarn scheelite ores. Calcium oxide and sodium carbonate was used as a pH value regulator, waterglass was used as a depressant and Oleic acid/sodium oleate was used as a collector. The result of experiment showed that the degree of the obtained W03 concentrate was more than 65% by one time ambient temperature roughing floatation, several times ambient temperature cleaning process."

Jan 1, 2014

By Francois Reizine

Infrared sensors will include scanning detectors and positioning sensors. The focus will be on 1, 2, and 4-color wavelength pyrometer systems which allow the accurate measurement of emissivity and, consequently, of the true temperature even in the presence of scale, slag, and fumes. Such sensors are being used in blast furnaces, BOF&apos;s, and galvanizing lines. Laser sensors will be presented using different principles of physics, mainly time-of-flight, pulsed infrared lasers for level measurement and dimensional measurement; triangulation lasers for width and thickness measurements; and laser Doppler velocimeters for velocity and length measurements, including mass flow, elongation, and tension control, cut-to-length applications. These sensors and systems are based on state-of-the-art technical developments to improve productivity and quality and reduce maintenance and downtime.

Jan 1, 2001

By Eduardo Juncal, Jorge Alberto Soares Tenorio, Jose Roberto de Oliveira, Denise Crocce Romano Espinosal

"Steel industry has been expanding every year, consequently there has been an increase in waste generation in this area. Thus, companies in this sector are finding it difficult to give a correct destination of waste. For example, only in a basic oxygen furnace (BOF) converter are generated about l8kg of dust per ton of steel. The aim of this work was the characterization of dust generated in the BOF converter. The characterization was performed by chemical analysis (titration for iron and its oxides and Inductively Coupled Plasma Atomic Emission Spectroscopy for other elements), scanning electron microscopy, size analysis using Mastersizer 2000 equipment and X-ray diffraction. It was observed that dust is composed mainly iron in form of magnetite, metallic iron and wustite with approximately 99% of the particle size below 100 µm.IntroductionToday, steel is a important metal for the world. It can be produced for two routes, blast furnace/ basic oxygen furnace (BOF) converter and electric arc furnace (EAF) [1].First route, the iron is produced from the reduction of iron ore and coke for fuel injection and! or natural gas for a production of pig iron in blast furnace. The pig iron is sent until BOF converter to perform the blowing of oxygen to obtain the steel. In the second route, the steel is produced using scraps or direct reduced iron (DR!) using electric arc.During steel production are generated a lot of wastes like slag, sludges, scraps and dust [2]. Only in the first six months of201O, world steel production totaled 706 million tons [3]. According to Watson and Wang [4], some 10 to 20 kg of dust is generated per tonne of liquid steel produced. Thus, the reuse of these wastes can be a great to companies, because it reduces the amount of raw material to be extracted and reducing disposal costs [5,6]."

Jan 1, 2012