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By Igor Wilkomirsky

Professor Ralph Harris was interested in minor elements behavior in nonferrous pyrometallurgical processes. His approach always considered fundamental aspects and technological considerations for the assessment of different challenges that today are becoming critical, particularly for Andean sulfides ores, where the content of Va elements (As, Sb and Bi) has challenged available technologies. This reviews the status of control and monitoring of As in copper smelters to give a general framework for this now-common problem. Some selected results of R & D programs at the University of Concepción are presented in the field of roasting, presenting a novel proposition for flue dust treatment as an alternative to the classical hydrometallurgical processes for these type of materials. This presentation seeks to open a broad but precise discussion about the needs of research in this area with further experimental and physicochemical modeling. The pioneering visions developed by Professor Harris with his students are now a source of inspiration and an unavoidable source of information.

Jan 1, 2013

By T. Johnson

Hydrometallurgical processes can be exceptionally corrosive. This is particularly true in acid leaching processes for copper, cobalt, nickel and rare earth elements. In the last five years, several large hydromet plants have been built in North America (Vale - Long Harbour, Baja Mining ? El Boleo and MolyCorp - Mountain Pass). Hundreds of storage tanks, extraction vessels and electrowinning cells along with miles of piping were designed and fabricated to withstand the aggressive environments inherent in these processes. One key element all three projects had in common was the extensive use of FRP in equipment design. As a material of construction, FRP provided equal if not improved durability relative to alternative corrosion resistant alloys at a considerably lower cost. This paper will highlight the extensive use of FRP in these three world scale projects and why it was chosen for each process.

Jan 1, 2013

By Mark Kennedy

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation?s cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2013

By Chen Xia

Iron separation from rare earth elements has always been an essential operation in almost all steps of rare earth element recovery and purification processes. As RE3+ and Fe3+ behave similarly in many operations the separation can sometime be either difficult or cost-inefficient. This article attempts to review the methods and options for removing the iron content within the process, with the focus on the existing or proposed precipitation and solvent extraction technologies. The precipitation of iron from REE solution as iron hydroxide, jarosite, goethite, hematite, or phosphate are briefly introduced. Methods for precipitating REE from solutions leaving iron impurities in the aqueous phase are discussed. Some proposed solvent extraction flow sheets for separating iron from REE are conceptually reviewed in this article.

Jan 1, 2013

Phase equilibria studies have been carried out on the "FeO"-Si02-MgO-A120rCr203 system in equilibrium with iron in the range of compositions and temperatures directly relevant to the nickel laterite deposits being investigated by Xstrata Nickel within the Araguaia belt in Para State, Brazil. Liquidus temperatures and primary phase fields have been measured as a function of composition using equilibration, quenching and electron probe X-ray microanalysis measurements. The results are presented in the form of pseudo-ternary sections. It was found that in the composition range investigated, olivine (Mg,Fe)2Si04 and pyroxene (Mg,Fe)Si03 are major primary phases. In addition, tridymite Si02 and spinel (Mg,Fe2+)O?(Al,Cr,Fe3+h03 are also present in the higher Si02 and lower Si02 regions respectively. The results of the phase equilibria studies were validated in a subsequent pilot smelting test.

Jan 1, 2009

By D. G. Tisdale

A pilot plant was installed and operated at the Xstrata Nickel Sudbury Smelter 10 demonstrate the CANSOLV SO2 Scrubbing System. A 350 m3/h slipstream (through a 10cm pipe) was drawn from two different industrial gas streams to test the performance and robustness of the scrubbing system. The system achieved high sulphur capture, typically above 99%, and proved tolerant 10 varying gas strength and dust content in the feed gas.

Jan 1, 2009

By M. J. King

Non-ferrous metals such as copper, nickel, lead, zinc, gold and platinum group metals are often found in sulphide mineral deposits. Various pyrometallurgical and hydrometallurgical processes are employed to extract the valuable metals from their minerals. These processes result in the production of sulphur bearing by-products or wastes. This paper provides a review of sulphur bearing by-products and the techniques used for their production. It focuses primarily on elemental sulphur, sulphuric acid and various fertilizer options. Liquid sulphur dioxide, oleum and gypsum by-products are also discussed.

Jan 1, 2009

The platinum group of metals (PGMs) possess a range of unique chemical and physical properties and arc increasingly finding important uses in a wide variety of environmentally-related technologies (eg. catalytic conveners, fuel cells, electronics). The typical ore grade for PGM mineralisation is similar 10 gold (gil) but the processing is more akin to base metals (at percent). The typical scheme for a PGM project is a mine, flotation concentrator, smelter and refinery. The environmental costs could therefore expected to be more significant than gold mining -in contrast to the uses for PGMs in many environmentally focussed technologies. The global production of PGMs is dominated by South Africa due to their large economic PGM resources in the Bushveld Complex, while other countries playa minor but important role. Concerns arc being raised about the long-term ability to supply PGMs to meet future technological needs, as well as allegations of significant environmental and social impacts such as water pollution, unfair village relocation and compensation issues. This paper presents a detailed review of the platinum-PGM industry and major environmental costs such as water, energy and greenhouse emissions. The relationships between production statistics and environmental or ?sustainability metrics' are then investigated with a view to understanding the current trends in PGM mining and potential future implications. The paper presents a unique case study for a group of metals which are uniquely concentrated in one major region of the earth and pose some intriguing and difficult sustainability issues for the future.

Jan 1, 2009

By A. D. Dalvi

With the current economic situation, the demand for nickel and other base metals has fallen significantly. More than 440 kt/yr world nickel capacity has been taken out of production within the last year, or more than 25% of the total [1]. This situation is similar to that at the end of 1970?s and it will take a number of years for the demand to recover to the levels before the economic downturn. In the meantime, the challenges facing the industry have increased due to diminishing ore grades, more inaccessible and complex deposits, mounting capital and operating costs and the various external pressures which include socio-economic, environmental, and energy challenges. All industries will be faced with paying the ?total ownership costs? in the future. This will only increase the burden on the industry. How to cope with this in what Thomas Friedman calls the ?Energy-Climate Era? [2] will be the most pressing challenge for the next generation of metallurgists and managers. It will force us to take a broader view of the problems and the solutions beyond mere technical. The metallurgists, engineers and project managers will have to look at the overall projects and their objectives in designing the solutions, requiring a top-down strategic approach.

Jan 1, 2009

The NorthMet deposit of PolyMet Mining contains a large reserve of copper-nickel-cobaltprecious metal mineralization. Historically it has been difficult to recover separate copper and nickel concentrates of a quality broadly acceptable to custom smelters using conventional mineral processing techniques. Recently, improved flotation methods have made it possible to produce separate and saleable concentrates which will be produced during initial startup of the NorthMet deposit and construction of the PLATSOL TM hydrometallurgical plant. After the initial transition period, it is planned that production of a bulk flotation concentrate will be followed by PLATSOL TM hydrometallurgical treatment to produce copper, nickel/cobalt and precious metal products. The PLATSOL TM process uses chloride-assisted total pressure oxidation treatment of a bulk concentrate to digest the base and precious metal content of the bulk concentrate into an autoclave solution. Following solid-liquid separation, the solution is then treated sequentially for precious metal recovery by reductive precipitation, copper solvent extraction and electro winning and finally, nickel and cobalt recovery by precipitation. During the pilot plant testing of the PLA TSOUM process for NorthMct bulk concentrate treatment, two variations on nickel and cobalt recovery were tested including mixed hydroxide precipitation with magnesia and separate nickel and cobalt hydroxide precipitation following solvent extraction separation with Cyanex 272. The results of the pilot plant testing of the nickel and cobalt recovery circuits for NorthMet arc presented.

Jan 1, 2009

By S. A. Shipilov

In this paper, the annual direct cost of corrosion in Canada is estimated to be approximately $41 billion. The figure does not include the indirect (user) costs of corrosion, sometimes referred to as social costs, which would essentially double the amount. Also, corrosion is shown to be a major contributor to environmental pollution, including when it results in the leakage of hazardous materials from pipelines, vessels and nuclear reactors. Industrial accidents caused by corrosion kill and injure hundreds of people annually. At present, corrosion is at the core of safety and risk analysis in several major industries such as energy generation, oil/gas production and transportation, chemical processing and petroleum refining. With the recent steam pipeline explosion during rush hour in New York killing one man, the collapse of the bridge in Minneapolis killing 13 people and another two years ago in Montreal when 5 people were killed, infrastructure corrosion is increasingly being acknowledged as a public safety concern.

Jan 1, 2009

By C. Walker

Since the 1950's, production of ferronickel from laterites has predominantly been achieved using the Rotary Kiln -Electric Furnace (RKEF) process. The productivities of kilns and furnaces have increased steadily over the years and metallurgical smelters can now rely on a smaller number of high-powered, reliable units to meet production objectives at much lower capital and operating costs per tonne of production. Modem RKEF plants are characterized by one or more process lines consisting of one large kiln feeding one large furnace. The current benchmark is one RKEF line with a high capacity kiln feeding an 80 MW furnace to process approximately 1.3 million tonnes per year of new laterite ore. It is proposed that a single RKEF line comprising one kiln producing 240 t/h of calcine feeding a 120 MW furnace could process 2 million tonnes per year of dry new ore which, for an ore grade of 2% nickel, is equivalent to 36,000 t/y of nickel per line. The plant could also be twinned to double the capacity to 72,000 t/y of nickel. This paper reviews recent developments in kiln and furnace technology, which enable substantial increase in productivity of an RKEF plant. The reduction in the capital and operating costs of a single-line, 2 million tonne of ore per year nickel laterite facility, and accompanying improvement in energy efficiency and environmental performance compared to existing operations, are also highlighted.

Jan 1, 2009

In view of the increasing environmental regulations that have been promulgated all over the world in the last 30 years, non-ferrous smelters and refineries have learnt and adapted to treat effectively metals'-containing process waste streams that need to be bled from the plant. However, anions such as sulfates, chlorides and fluorides-presently not a major problem ?are coming under increasing scrutiny and need to be addressed in the near future. The current paper reviews options for waste water treatment with reference to: a) types of waste streams processed b) process chemistry c) discharge options d) recovery and reuse of water and e) solids disposal. Methods to obtain zero liquid discharge ?a possible solution to eliminate discharge of above anions and residual heavy metals- are discussed with case studies. The long term goal of any non-ferrous smelter plant should be to have a zero liquid discharge philosophy-an approach that would become an epitome of water reuse and conservation.

Jan 1, 2009