Search Documents

By P. Hajiani

Rare earth elements (REEs) are critical materials in many leading-edge technology products. However, REE separation outside China has remained a challenge in addressing environmental concerns of current production. The author has worked on a technique employing the emphasised variability in the electrophoretic mobility (μi) of REE for the purpose of REE separation. In continuation of the results presented in IMPC 2016 [1], this contribution summarizes the progress achieved in 2016 and 2017. The major goal was to increase the REEs concentration by a factor of 1000 and to attenuate the consequent drawbacks, specifically joule heating effect. Amphiprotic hydroxylic solvent was selected to replace water, which has a major impact on the complexation mechanism and buffer requirement. Non-aqueous media result in a significant drop in the specific molar conductivity of the electrolyte, whilst μi reduces several times only. Moreover, a quasi-steady state electrophoretic separation in conjunction with temperature gradient focusing is adapted to improve scalability.

By Wayne Bell, Shivanand A. Borkar, Anish Upadhyaya, Matthew D. Andriese, Jiann-Yang Hwang, Zhiwei Peng

"A refractory ore body located in Michigan’s Upper Peninsula contains high concentrations of nickel and copper chiefly occurring in the minerals pyrrhotite, chalcopyrite, and pentlandite. Refractory ore bodies are difficult to treat by conventional mineral processing methods so microwave pre-treatment of the ore is employed to increase metallic-particle/host rock liberation by making use the differential thermal expansion properties of the mineral phases that absorb microwave energy. The Curie temperature measurement of metallic-bearing particles is in agreement with the known value for pyrrhotite occurring at 325°C. A nickel-rich iron sulfide mineral is found to be in occurrence and also appears to be magnetic under BSE imaging. It is shown the ore particles heat rapidly when exposed to microwave radiation for short durations of time mainly due to the high concentration of ferromagnetic mineral phases. Rapid heating causes thermal expansion of constituent mineral phases that produce cracks within ore particles. SEM imaging shows fracture occurring along grain boundaries and throughout host rock matrix. Ball milling experiments show an increased grindability of the ore resulting in a decrease in work index values.IntroductionCrushing and grinding operations consume 50-70% amount of energy used in mineral processing operations [1]. All these processes involve high energy impact of surfaces to develop compressive stresses that produce cracks to initiate breakage of particles. Microwave pre-treatment of certain types of ore might provide an energy savings to these type grinding processes by taking advantage of the tensional forces produced by selectively heating microwave absorbing type mineral phases. The heating of ore particles produces cracking by thermal expansion of the constituent mineral phases. Conventional heating has been investigated and shown to positively aid in grinding processes but determined energy inefficient to be used commercially."

Jan 1, 2011

By Paul O. Malan

"The Tusc gold deposit is located along the Carlin Trend approximately 13 kilometers north of Carlin, Nevada and 2.5 kilometers northwest of the Gold Quarry mine. Tusc is one of several structurally controlled oxide gold deposits located along the Good Hope fault within the Maggie Creek subdistrict. Mining commenced in 1994 with an oxide reserve of780,000 troy ounces of gold at an average grade of 1.34 g/t Au. The Good Hope fault forms the southwestern edge of the Schroeder Mountain uplift (also known as the Carlin Window) and juxtaposes carbonate rocks of the Siluro-Devonian Roberts Mountains Formation against siliceous mudstone, siltstone, and silty limestone of the Devonian Rodeo Creek unit. Submicroscopic gold mineralization is disseminated in the Good Hope fault system and in fractured hanging wall carbonate rocks. Wallrock alteration includes silicification, deca!cification, sericitization, and late alunite replacement and veins. All Tusc ore is transported 2.5 kilometers to Gold Quarry for processing. Leach-grade ore (0.2 - 1.7 g/t gold) is placed on the oxide leach pads, and mill-grade ore(> 1.7 g/t gold) is processed through the CIL oxide mill. IntroductionThe Tusc gold deposit is located in Eureka County, Nevada, U.S. A, approximately 13 kilometers north of the town of Carlin and 2.5 kilometers northwest of the Gold Quarry mine (Fig. 1 ). Tusc is one of several open-pit, oxide, gold deposits within the Maggie Creek subdistrict of the Carlin Trend. Tusc is a structurally controlled gold deposit located along the Good Hope fault. Submicroscopic gold mineralization is disseminated in the brecciated and silicified Good Hope fault zone and along intersecting northeast and northwest striking structures."

Jan 1, 1997

By Patrick R. Taylor

This investigation studied the inflight calcination kinetics of nuclear waste simulant using a thermal plasma reactor. A series of experiments were performed to determine the conversion of insoluble aluminum compounds to the soluble compounds and the decomposition of complex organic and nitrite compounds present in the simulant waste. Thermodynamic calculations based on free energy minimization were performed to establish a theoretical basis for this investigation. A kinetic model to describe the conversion of gibsite to sodium aluminate has been proposed. The products of the calcination were characterized using XRD, Gas Chromatography, and chemical analysis by ICP. The results of this investigation indicated 85% gibsite conversion to sodium aluminate, 90% of nitrate decomposition, 52% TOC decomposition and 90% conversion of chromium to soluble compounds. A process is identified for inflight calcination of wastes. Key words: Plasma, waste, simulant, calcination

Jan 1, 1996

By Fumito Tanaka

In the Mitsubishi Continuous Copper Smelting & Converting Process, the heat for the dissolution of scraps is effectively supplied from the melts strongly stirred by top injection. Various kinds of shape of scraps not only powder but also lump, sheet, cube and so on can be treated without any emission of dust and fugitive gas, and no additional furnaces for scrap processing is necessary. Therefore, this process is much suitable for recycling. The authors have investigated the melting rate of ice sphere into a water bath equipped with top blowing lances as a basic study for the dissolution of scrap. Hydrodynamic experiments were carried out, and mathematical models were applied to the results. The results show that the melting rate of ice sphere strongly depends on the standing waves at the bath surface.

Jan 1, 2001

By R J. Singh, E. Z. Chacko, Devilal, S. K. Jha, Rina Sahu, Sheshank Shekhar

"Breakouts are one of the biggest problems encountered during continuous casting of steel billets. Billets get cracked locally or break completely in two parts during solidification causing the liquid part of the partially solidified billet to empty inside the cooling chamber. Proper control of important parameters is necessary to avoid break outs during continuous casting. In the present work, the nature of the break outs at a billet caster at Tata Steel was studied. Data analysis was also done for certain casting parameters and the Sulphur tracer test was conducted to understand solidification in the mould. It was found that to reduce the occurrence of break outs, it was necessary to tune the operations based on the grade being cast and the design of the mould tube being used.IntroductionA break out during the continuous casting process is a rupture of the partially solidified shell inside the secondary cooling chamber, causing the contained liquid steel to spill out. In the mid 1970s while continuous casting technology was still in early stage of development, causes of breakouts was not well understood. Today, with technological development much has been understood about breakouts but, most of the understanding has been in the slab casting process wherein due to the higher level of instrumentation, a lot of information has been gained. In billet casting however, due to the geometry of the mould housing with the tube mould, multiplied by the complexity of the multiple strands, instrumentation has not been used and obtaining data for analysis has been difficult.Breakouts at billet casters are still the main hindrances to production. A break out results in a loss in production since the strand which has had a break out is now not available to produce and thus a six strand caster would be reduced to a five strand caster, increasing the time for casting the same tonnage. Additionally extra set up time is required as more often than not a mould change is required in order to have the strand casting again."

Jan 1, 2014

By K. Gao, R. Dry

"Carbon boil, which results in excessive spitting and even complete destruction of a metal drop, could significantly influence the efficiency of direct smelting processes. Carbon boil has been studied as a function of some key parameters such as melt sulfur content, oxygen partial pressure, and melt area/volume ratio. The time of carbon boil was determined using a CCO camera coupled with a time/date generator connected in parallel to a video recorder and a computer. The time of carbon boil was in the range ~5 - 15 seconds under the conditions in this study. A mechanism for carbon boil has been proposed.IntroductionThe occurrence of carbon boil in molten iron drops can result in excessive spitting and sometimes even complete destruction of a metal drop. In direct iron smelting processes, this could significantly influence the decarburisation of liquid metal and the post combustion and hence may influence the efficiency of smelting processes. The generation and consequent ejection of metal droplets into the gas phase occurs due to the intense turbulence in the bath which results from the injection of gases and coal. The aim of this investigation is to understand the fundamentals governing the carbon boil phenomenon under direct iron smelting conditions to assist control of process efficiency.Carbon boil phenomenon has been studied as a function of some key parameters such as melt sulfur content, oxygen partial pressure and melt area/volume ratio. The time for the occurrence of carbon boil has been determined in this study at 1440 °C using a novel approach which includes utilisation of a CCD camera coupled with a time/date generator connected in parallel to a video recorder and a computer. This arrangement permits the capture of the entire sequence of events leading up to carbon boil and therefore the determination of time of boil which is in the range -5 - 15 seconds under the conditions in this study."

Jan 1, 1996

By Jing Zhan, Gui Li, Wei-feng Li, Li-Hua Jiang, Chuan-fu Zhang, Jian-yang Hwang

Thermodynamics analysis for processing the charge with lead concentrate and lead sulfate-containing materials in bottom blowing smelting furnace was conducted. The results show that the technology of large-scale processing PbSO4- containing materials with PbS concentrate in bottom blowing furnace under the condition of using high-iron slag type, batch heat supplement, high temperature and rich oxygen is thermodynamically feasible. The exploration test and industrial experiment confirm the results. When S content in mixed ore is 16~17% with coke foam content of about 5%, the lead paste amount can be increased up to 40%.

Jan 1, 2015

By Leonid N. Shekhter, Corby G. Anderson, Esra Cankaya-Yalcin, Daniel G. Gribbin, Joseph D. Lessard, Larry F. McHugh

"A new process for smelting copper, Looping Sulfide Oxidation™ (LSO™) significantly and positively alters the smelting energy balance. This process uses copper oxide in conjunction with air for the desulfurization of copper and chalcopyrite concentrates. Copper oxide is regenerated in a flash type furnace and then ""looped"" back for the oxidation of the copper concentrate. Heat and material balances show that the Looping Sulfide Oxidation™ process requires significantly lower net energy than conventional technology. This process produces anode copper and higher S02 content off-gases for efficient formation of sulfuric acid. Additionally, the process yields slags with lower copper solubility as compared to the conventional technology.IntroductionBased on the positive results from LSO™ investigations [1], further lab investigations into co=on sulfides and metal oxides were performed. It was discovered that chalcopyrite (CuFeS2) is oxidized with copper (II) oxide. In this reaction over 98.5% of sulfur was removed as S02, while a significantly improved energy balance was observed. This paper intends to analyze both the conventional flash smelting process and the newly developed Looping Sulfide Oxidation™ process, comparing heat and material balance results. LSO™ yields improvements to the energy footprint for copper, opening the door to new copper processing opportunities."

Jan 1, 2013

By Lincoln McCrabb

Correct measurement and interpretation of viscosity data is critical for design of any thickening and pumping process that involves a non Newtonian slurry. The nickel laterite pressure acid leach (PAL) process relies on producing a slurry of maximum achievable solids concentration. Small variations of 1-2% solids concentration can alter economics significantly. For the Ravensthorpe Nickel Project, a rheology protocol has been developed which optimizes the solids concentration across a range of ore types. The vane yield stress technique has been utilized to accurately quantify the flow of thickened slurry in the lower shear range. A yield stress of 100Pa has been used as a benchmark to determine the optimum solids concentration achievable utilizing deep cone thickening. Statistical analysis of the data shows critical rheology distinctions between ore type, particle size, lithology and geochemistry. Linear and power law models have been applied to rheology flow curves to reconcile the material transport properties with the anticipated thickener underflow solids concentration. Keywords: Vane Yield Stress, Thickening, Rheograms

Jan 1, 2004

By J. C. Agarwal

Rare earth metal alloys are becoming increasingly important, particularly those of neodymium, because of their magnetic properties. This paper will present a generalized approach to the production economics of the metallic rare earth alloys. With appropriate regard for the chemistry of different rare earths and the large impact of economies of scale, it is possible to make fairly accurate estimates of the production costs of other rare earth alloys as well.

Jan 1, 1989

By E. N. Mounsey

Ausmelt Technology was selected by Bindura Nickel Corporation (BNC) as the basis for a new copper circuit to process nickel plant copper leach residue to blister, anode and finally cathode copper and recover PGM values at the Bindura Smelter Refinery (BSR). The process selected, based on Ausmelt Technology to smelt and convert the residue to matte and blister copper and produce a discard slag, is novel incorporating smelting, converting and slag reduction process steps in a single Ausmelt vessel. The process demands a high quality blister copper product with low levels of arsenic and nickel. This paper reviews the project and the initial operational results to the end of 1997 of the Ausmelt Top Submerged Lancing (TSL) smelter and discusses the implications for the wider TSL converter market.

Jan 1, 1998

By J. P. Downey, T. Salisbury, M. Berlin, E. Rosenberg, G. Pinson, R. Christianson, K. Gleason, W. Gleason, S. Davis

"The Center for Advanced Mineral and Metallurgical Processing is developing membrane production technology based on autocatalytic reduction of palladium from solution onto a unique, porous substrate. Surface membranes and catalytic structures are critically important to applications that range from hydrogen purification membranes to petroleum refining. Autocatalytic reduction processes represent a cost effective method of producing stable surface layered structures that have good working lives. These attributes are particularly important in the production of palladium alloy purification membranes used in hydrogen production. Although considerable research has investigated the interaction of hydrogen and palladium alloys, the mechanisms in play while the membranes form are not well understood. Preliminary research has identified three distinct deposition mechanisms and it appears that substantial control over the resulting membrane is possible.IntroductionPalladium-based membranes separate hydrogen from other gases because hydrogen is uniquely soluble in and readily passes through bulk palladium. As currently produced, palladium-based membranes are expensive and have short service lives. These circumstances are due in part to the lack of a complete understanding of palladium or palladium alloy deposition. The Center for Advanced Mineral and Metallurgical Processes (CAMP), in collaboration with the Metallurgical and Materials Engineering Department at Montana Tech and the Chemistry Department at the University of Montana, is engaged in the development of new methods and materials for hydrogen purification membrane production.In membrane production, the palladium requirement depends on substrate surface properties such as surface chemistry, porosity, and roughness. Thin, defect-free membranes have been successfully produced on substrates of porous glass, alumina, and stainless steel. However, the differences in the thermal expansion coefficients of palladium membranes and porous glass or alumina substrates cause problems at operating temperatures. The use of stainless steel substrates is advantageous because stainless steels have thermal expansion coefficients similar to that of palladium and they are stable at the required operating temperatures (Wicke, E., Brodowsky, H. and Ziichner, H. ). Stainless steel is also readily available and relatively inexpensive."

Jan 1, 2012

By J. Sofra

The quantity of copper produced by secondary material processing is increasing as metal producers look to cleaner and cheaper sources of copper. The need to smelt secondary copper more economically, to process a wide range of materials with large fluctuations in size and composition and to cope with the increasingly stringent environmental constraints have put considerable pressure on existing conventional secondary copper smelters. The Top Submerged Lance process, developed and commercialized by Ausmelt Ltd offers a low cost technology, which is particularly adapt at processing copper-bearing scrap and residues. The application of Ausmelt Technology to replace conventional secondary copper processing operations introduces potential for significant advantages in environmental performance, and improved process efficiencies through the use of cheaper hels and reductants, the high rate of metal recovery and the flexibility inherent in the technology to process various feed material types. The economical, process and environmental benefits of its application are highlighted for both the smelting and converting stages of copper production.

Jan 1, 1997

By P. Wieser, D. Feke

"Priming of filters with small pores is influenced by the surface tension of the liquid metal and may be complicated by freezing • Freezing followed by melting has been observed experimentally. This process has been modeled on the basis of one dimensional heat flow by radiation to the filter and by conduction in the metal. Also considered are super-heat of the metal and the initial filter temperature. The results of the model provide useful guidelines for the application of filters. IntroductionFiltration has been recognized as a valuable method of refining by removing suspended phases from liquid metals or alloys. Woven fiberglass type fabrics and wire screens were used initially in the aluminum industry. With the introduction of the ceramic filters that exhibit improved inertness and refractoryness, filtration has been introduced to higher melting alloys including cast irons, superalloys, stainless steels, as well as low and medium carbon low alloy steels. A considerable literature is delveloping rapidly on the progress in applications and the advances in understanding the mechanisms and effectiveness of filtration processes (1-8).With the use of filtration for different alloy systems for the production of cast to shape parts a bewildering variety of gating system modifications has been developed (Figure 1) to accommodate the installation of filters in the mold. The modifications have two principal purposes: 1) the runner expansion is intended to compensate for the resistance to flow due to the filter and that of the captured inclusions, and 2) the metal reservoir upstream of the filter, provides a temporary by-pass which permits metal to flow across the filter and heat it until priming can be accomplished. priming of.filters by low and medium carbon steel is readily accomplished but, compared to such alloys as cast iron or 19 Cr-9Ni stainless steel, requires greater precautions to avoid failure to prime by excessive freezing on or inside the filter pores. This problem is further examined below:"

Jan 1, 1986

By A. V. Kuznetsov, R. I. Kamkin, V. M. Paretskiy, A. Y. Mamaev, V. P. Bystrov, A. S. Vernigora

"Vanukov furnace technology is an efficient, proven pyrometallurgical injection technology, used extensively in Russia and Kazakhstan for a number of different applications. The technology was most widely adopted for processing copper sulfide concentrates for matte in smelters in Norilsk, Revda (Russia) and Balkhash (Kazakhstan). The following applications also were developed and tested at industrial scale: treatment of sulfide lead and lead-zinc concentrates, laterite nickel ore, production of cast iron, treatment of antimony gold-containing ores, and municipal solid waste. In this paper, current experience of Vanukov furnace application to these technologies is described with a number of general development trends and new areas of application.IntroductionAt the present time, the Vanukov process, developed at the Moscow State Institute of Steel and Alloys at the Department of metallurgy of non-ferrous, rare and noble metals with collaboration with other research organizations, is a highly efficient technological solution for processing different kinds of raw materials. The process was invented by Professor Andrey Vladimirovich Vanukov, whose research work began in 1949. From 1956 to 1975 test runs of the technology were carried out at the smelters in Norilsk and Balkhash. In 1976 a pilot Vanukov furnace was built in Ryazan. Furnace designs was modified to suit the various test programs. A major objective of each experiment was the determination of optimal working conditions for processing different types of raw materials such as copper, copper-nickel, copper-zinc, lead or pyrite concentrates, and materials containing secondary lead and zinc. After the death of Andrey Vladimirovich Vanukov in 1986, this technology and furnaces based on the technology were named after him: “Vanukov process” and “Vanukov furnace”. Today, the following furnaces based on Vanukov technology are either working or were tested at semi-industrial scale: three in Norilsk, two in Revda (Russia) and two in Balkhash (Kazakhstan) for treatment of copper sulfide concentrates for matte, one in Orsk (Russia) for processing laterite nickel ore, one in the Buruktal plant (Russia) for antimony gold-containing ores for antimony oxide sublimates and gold-containing metallic antimony, and one in China for processing sulfide lead and lead-zinc concentrates for production of black lead and zinc-containing sublimates."

Jan 1, 2011

By Sun-Hee Cheong

This study sought to produce L(+)-calcium lactate using precipitated calcium carbonate as a starter culture composite of lactic acid bacteria in lactic acid fermentation. Specifically, precipitated calcium carbonate was synthesized by reacting calcium hydroxide with sodium carbonate in the previous study by the authors. Synthetic precipitated calcium carbonate was then used as the calcium source of lactic acid bacteria during the fermentation process. In general, precipitated calcium carbonate has low absorption rate in the human body. On the other hand, calcium lactate has high absorption rate; it is commonly used in food and drug industries as calcium additives in various foods such as cookies, beverages, bread, sauces, powdered milk, and fruit juice. Calcium lactate has two racemates, e.g., L(+)-lactate and D(-)-lactate. In particular, L(+)-lactate is known to be more soluble than D(-)-lactate and generally produced from lactose by homo-fermentative lactic acid bacteria such as Lactococcus spp., Lactobacillus plantarum, Lactobacillus casei, Lactobacillus curvatus, and Pediococcus spp. Thus, the characteristics of the pertinent lactic acid bacteria and optimal condition such as temperature, pH, precipitated calcium carbonate addition rate, and content of fermentation for increasing formation yield and purity were investigated. The findings suggested the possibility of manufacturing L(+)-calcium lactate using precipitated calcium carbonate as a calcium source with high value-added instead of commercial calcium lactate.

Jan 1, 2006

By F. J. Tavera

Recently Jameson cell technology has gained acceptance in both mineral and non-mineral applications, mainly because of the high degree of contact between the involved phases in the downcomer, fact that leads to an efficient collection performance. The key for an acceptable performance of the downcomer operation depends on the stability of the jet zone, the mixing zone, and the plug flow zone. in this work the behaviour of the downcomer of a laboratory Jameson cell is reported, as a function of gas hold-up, superficial gas velocity, superficial liquid (or slurry) velocity, and length of the operating zones. The presence of carbon is evaluated in terms of its effect on the gas hold-up and bubble surface area flux. The influence of the downcomer operating conditions on the gas-liquid disengaging cell is presented. Keywords: Jameson cell, downcomer, gas hold-up, mixing, plug flow, conductivity.

Jan 1, 2003

By M. D. Light

An intelligent control system (ICS) is being developed for ferrous iron oxidation by Thiobacillus ferroxitdans. The ICS provides computerized data acquisition and' control of process variables (temperature, Eh, pH, dissolved oxygen arid carbon dioxide concentrations and dilution rate) to maintain the ferrous iron oxidation at the highest possible rate. The ICS uses fuzzy logic for analysis of data inputs and implementation of control strategies. T:his paper provides preliminary information on the development of the ICS and? its operation.

Jan 1, 1991

By Yoshihiko Maeda

"Although Japanese mining industry once had been a polluter of toxic heavy metals and gasses, it has been struggling for improvement of environment at mining and smelting facilities under the strict Japanese regulations. Through these efforts, the industry has developed various environmental technologies to be applied in other industries and society.Recycling of metal scraps, for example, has been conducted at smelting facilities. Treatment of hazardous waste, cleanup of contaminated soil and management of landfill are other examples of application of mining and smelting technologies and facilities. In accordance with the worldwide environmental concerns, the industry has become one of the leading industries to promote ""Sustainable Development"", and it is expected further contribution in reducing various environmental burdens to earth by utilizing its mining and smelting technologies and facilities. Some of the examples of these applications are presented in this paper.IntroductionDowa Mining Co., Ltd., established in 1984, is known as one of the ~op Japanese producer of nonferrous metals. Base on its special expertise in the mining and smelting of complex ores, it has expanded its business areas to downstream activities ranging from highly purified metals and alloys, electronics materials, chemicals and related various businesses. Dowa Mining now is becoming more active in the field of waste treatment and recycling.Dowa Mining had operated some mines until 1980th, located at the western part and northern part of Honshuu Island in Japan; the former is pyrite mine while the later is ""Black Ore"" mine,· a complex sulfide ore composed of high grade of copper,· silver, lead and zinc. However, due to the strong yen began in1985; Dowa Mining closed its mining operation in 1994, and has sifted to mining operations in Mexico."

Jan 1, 2000