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By C. Gaubert, G. Bourassa

"The construction or rebuild process in the anode baking furnaces has been modeled with the software Rockwell Arena, in order to minimize the process cost and risk. The case study was focused on the sectional rebuild (""on the fly"") that needs a high coordination of the material inventory, the on-site personnel and the construction/production schedule. Multiple entities and resources were allocated for the different part of the process (in-furnace process, prefabrication, materials transportation, etc.). Logic flow charts and VBA macros were used to simulate the space utilization (including cranes utilization) and interaction with production. MS-Excel output files can show user-friendly results."

Jan 1, 2006

By L. Bratek, K. Jaworek, M. Czaplicka

Methods for arsenic compound removal from aqueous solutions include processes such as: coagulation, adsorption, membrane techniques, electrochemical and biotechnology techniques. Advanced oxidation using both UV radiation and strong oxidizing agents such as ozone and hydrogen peroxide may also decompose these compounds. It is known that effluents from metallurgical processes contain inorganic arsenic compounds in addition to the organic compounds such as: dimethylarsinic acid and phenylarsonic acid. This paper presents the conditions that lead to the formation of deposits containing mainly arsenic, such as pH, the wavelength of the radiation and the type of oxidant, for this type of effluent.

Jan 1, 2014

By H. J. H. Pieterse

Agitation requirements in oxidation autoclaves can vary widely depending on the mineralogy of the feed material and the specific process selected. Before selecting an agitation system it is important that the client specify the desired throughput, mineralogy, chemistry, kinetics, compartments, overall retention time, and the desired oxygen utilization. In selecting the agitation system, the factors mentioned above as well as oxygen solubility, oxygen mass transfer coefficients, and specific power are evaluated. Much research effort has been directed toward open tank systems for fermentation and oxidation processes. However, for high pressure autoclave oxidation processes little information is available. In this review the author's experience in the autoclave industry and some of the available literature are utilized to compare the installed power per unit volume with some of the methods proposed for open tank oxidation. Equations that appear to give results close to that experienced in the industry have been identified. Further work is required in this area to develop a higher degree of confidence in the ability to predict the power required for any given case.

Jan 1, 2004

By P. H. Agson Gani, T. Sitorus, N. P. Widodo

"PT ANTAM UBPE Pongkor underground mine use blasting to develop its tunnels which will cause poisonous and dangerous gases trapped inside mine. To analyze this case, a study of mine ventilation, the dispersion of carbon monoxide (CO) gas concentration and diffusion coefficient is commenced. At the end, the re-entry time formula will be determined. Results indicate that this study is site specific and could only be applied in the place this study executed. The aim of this study is to be further developed by applying Principal Component Analysis (PCA) to find a universal re-entry formula. KEYWORDS Mine Ventilation, Re-Entry, Smoke Clearing, Diffusion Coefficient, Carbon Monoxide Gas, Gas Dispersion INTRODUCTION Pongkor underground mine is using cut and fill as its mining method. Thus, its development and production processes require blasting to develop its tunnel. This process caused poisonous and dangerous gases spread and trapped inside the mine, one of them is carbon monoxide (CO) gas. CO is formed in an unbalanced reaction of explosives detonation and could be the cause of headache, blackout and death to people who inhale CO at certain concentration (McPherson, 2011; Hartman, Mutmansky, Ramani, & Wang, 2012). Mine ventilation system is installed in the mine to resolve this problem. Mine ventilation play an important role to disperse CO gas by absorb the poisonous/dangerous gases and deliver clean air into mine. The important parameter is diffusion coefficient, because diffusion is affecting particulates or gasses spreading from its sources throughout the mine. Diffusion coefficient is the total diffusion in axial direction of turbulent flow mainly by convection of bulk motion, advection and eddy diffusion, while the effect of molecular diffusion is appreciably negligible (Widiatmojo et al, 2015). Taylor (1953, 1954) develops a theory about the dispersion by inducing a slow stream of solvent into a capillary tube. Taylor used Reynolds assumption of radial diffusivity to be analogous with the transfer of the matter in turbulent flow as well as the transfer of momentum and heat. Then, Taylor proposed the formula of diffusion coefficient, D (m2/s), against pipe diameter and turbulent shear velocity are as follow:"

Jan 1, 2019

By F. Siciliano, D. Bai, S. Yue, A. M. Elwazri

The influence of niobium addition and very low temperature (`cool') deformation on the microstructure and properties of low carbon microalloyed steels was investigated. In this work, the specimens were heated at 1200°C and held at this temperature for 20 minutes. Some specimens were aged at 400°C for times ranging from 10 minutes to 10 hours followed by air-cooling. Others were subjected to deformation at 400°C (`cool deformation') prior to aging. It was observed that the proportion of acicular ferrite was increased as the amount of Nb was increased. It was found that cool deformation increased both yield and tensile strengths significantly compared to that of the aged only specimens.

Jan 1, 2005

By Jayne Somers

Methane (CH4) is a potent greenhouse gas, accounting for 15 percent of all global greenhouse gas emissions in 2005. Since methane has a much shorter atmospheric lifetime than carbon dioxide (CO2), reducing methane emissions can achieve considerable climate benefits over the next 25 years. Coal seams often contain significant quantities of methane and CH4 released to the atmosphere from gassy mines during coal extraction is a major source of greenhouse gas emissions. Methane (CH4) emissions from coal mining activities constitute approximately 6% of total global human-related methane emissions. Coal mines around the world have recognized that methane is a clean energy resource that can be captured and used productively. Coal mine methane (CMM) is currently utilized for power generation, natural gas pipeline injection, vehicle fuel, industrial process feed stocks, on-site mine boilers, mine heating, and home heating distribution systems. Upgrading mine degasification systems can often improve gas quality and create favorable project economics. The United States has been a leader in coal mine methane (CMM) recovery and use since the 1990?s. There are now 15 projects at active underground mines in the U.S., as well as 26 abandoned mine methane projects. Recovery and use projects at active underground U.S. mines reduced methane emissions by approximately 49 Billion cubic feet in 2010. In an exciting new development, a ventilation air methane (VAM) mitigation project at the CONSOL McElroy mine in West Virginia was installed by Verdeo. Operational since September 2012, this is the first commercial-scale VAM project in the U.S. and the project will reduce methane emissions by an estimated 920 MMCF/yr. As part of the U.S. Greenhouse Gas Reporting Program, actual data on methane emissions from underground coal mines was collected for the first time in 2011 and reported to U.S. EPA in September 2012. The data collected will help inform stakeholders, particularly the underground coal mining industry, of CMM emission sources on public and private lands. The detailed data will also shed light on the specific sources of methane from active underground coal mines and highlight project opportunities for the U.S. coal industry. The paper will cover U.S. coal mine methane emissions, U.S. CMM utilization and destruction projects, Federal policies and State incentives for CMM capture and utilization. 2011 CMM data from the U.S. Greenhouse Gas Reporting Program Subpart FF will be analyzed and compared with previous U.S. Greenhouse Gas Inventory estimates. Other developments, including the voluntary carbon market, will be discussed.

Aug 1, 2013

By S. Mathieu, R. Mennillod-Blondin, P. Cousin, N. Valle, H. Bouzahzah, P. Marion

The gold deposit of the Lapa mine has a complex mineralogical gold state with coarse and fine native gold, aurostibite and submicroscopic gold within arsenopyrite. A specific mineralogical characterization of the refractory fraction was conducted combining various techniques such as optical microscopy, electron microscopy, electron microprobe and secondary ion mass spectrometry. In parallel, the mineral processing behaviour and the recovery of the refractory gold were studied by pressure oxidation and cyanide leaching. This paper presents the mineralogical methodology developed to characterize the refractory gold distribution within arsenopyrite. These results are presented and interpreted in order to plot gold recovery versus sulphide oxidation. The comparison of the metallurgical behaviour yields predicted from the mineralogical data and the one calculated from leaching tests shows a good agreement and allows mineralogical explanations of the gold metallurgical behaviour.

Jan 1, 2011

By T. Grammatikopoulos, SGS Canada Inc.

"The Nechalacho rare metal deposit, located in the Northwest Territories, Canada, is currently being taken through Feasibility Study by Avalon Rare Metals Inc. QEMSCAN analysis and supplementary electron microprobe analysis were utilized to identify and quantify the mineralogy of the deposit, and determine REE distribution among the minerals. QEMSCAN mineralogy was performed to provide textural information on the mineralization, determine the variability of the ore and identify REE domains, and the liberation and association of the REE minerals. The sample matrix consists predominantly of silicate minerals. The REE minerals include allanite, monazite, synchysite, columbite, fergusonite, and bastnaesite. Zircon is present in considerable amounts and is a REE carrier. Fergusonite and zircon account for most of the HREE, and monazite, allanite, synchysite and bastnaesite the LREE. QEMSCAN mineralogical data is extremely valuable in assessing the mineralogy of the ore. The data are implemented to define the mineralogy of the ore body, support metallurgical test work, and predict recoveries and grades.INTRODUCTIONThe term rare earth elements (REE) is used to describe the 15 lanthanide elements or metals and, more recently, the metals yttrium and scandium, which display similar physical and chemical properties.Economic and potentially economic REE deposits form two main groups, a more commonly occurring “light rare earth element” (LREE) group containing lanthanum, cerium, praseodymium, neodymium, and samarium and a less commonly occurring “heavy rare earth element” (HREE) group which, in addition to the LREE, contains elevated concentrations of the more valuable REE, europium, gadolinium, terbium, dysprosium, holmium, yttrium, erbium, thulium, ytterbium, lutetium and scandium. The first group is hosted primarily by carbonatites and the second by highly alkaline (Na + K > Al) silicate igneous rocks. The LREE are produced mainly from bastnaesite, monazite, etc., while HREE are produced almost exclusively from low-grade secondary ion adsorption clay deposits in which the REE are adsorbed onto the surfaces of kaolinite and halloysite, clay minerals produced by the weathering of granite and sediments. HREE are also found in fegusonite, zircon, xenotime, etc but are not produced presently from these minerals. China is responsible for 97% of the World’s production of the REE, mainly from the giant Bayan Obo, carbonatite-related deposit and from the clay deposits mentioned above.Quantitative automated mineralogy is increasingly being applied to ore deposits. It helps users to understand and improve mineralogical parameters for geological and metallurgical purposes. Data include textural characterization, to quantification and distribution of ore and gangue minerals, liberation and association of the REE minerals. The data can be used to define mineralogical domains and predict the metallurgical response of the ore (Gunning, de Souza, & Grammatikopoulos, 2009)."

Jan 1, 2012

By D. L. Cluff

Ventilation Air Methane (VAM) is a high volume low concentration methane source. The capture or use of methane from VAM is challenging, which results in the routine discharge of methane into the atmosphere. Mitigating VAM has the benefits of providing an energy source and reducing the atmospheric Greenhouse Gas (GHG) burden. The GHG radiative forcing effect of methane is 17?23 times as potent as carbon dioxide on a 100-year time horizon. Thus, any reduction in atmospheric methane would be beneficial. The calorific value of methane is 55.5 MJ/Kg; therefore, a 100 m3/s flow with VAM concentrations from 0.1?1% can provide 3.8?38 MW of exploitable power. Strategies to mitigate VAM such as: Thermal Flow Reverse Reactors (TFRR), Catalytic Flow Reverse Reactors (CFRR), Lean Burn and Catalytic Gas Turbines, Biothermica Vamox®, Megtec VOCSIDIZER©, and Vamcat? are briefly reviewed. The review of VAM mitigation technologies reveals disadvantages such as the need to maintain a minimum internal heat capable of oxidizing the methane. This requirement uses all of the available methane up to the point of reaction sustainability and up to half at the highest methane concentration in VAM. Some systems may introduce a pressure drop to the ventilation system, which would impinge on the existing ventilation system design. These impediments necessitate the development of a more amenable technology. In the proposed system, gas turbines (GT), coupled to a combustion chamber with an external fuel supply, assist the combustion of the VAM. The combustion-chamber coupled system provides electricity, while the heat contained in the GT exhaust gases increases the temperature of the VAM, encouraging the development of a flame inside a combustion chamber. The flow from the combustion chamber streams through a primary air/fluid heat exchanger capable of producing steam of a high enough quality to generate electricity using conventional steam turbines. The residual heat after primary extraction, directed through other equipment, provides additional heat based products such as industrial scale dry air, chilling by an absorption chiller or hot water. The overall design of the system is scalable for low to high VAM flows or variations in concentrations and is capable of providing the company or community with heating, chilling, hot water, electricity or motive force as needed by the particular site or community. The Multi-generation system uses heat from three sources to provide clean efficient energy while mitigating the atmospheric emissions of methane. These sources are heat from the GT, often considered waste heat, heat from fuel injected into the igniters and heat from the VAM. The opportunity to collect carbon credits may improve the economics. In order to design a system with this capacity, a detailed analysis of the combustion characteristics of three separate flows is required. VAM is the main airflow, having the highest volumetric effect, while the GT exhaust and the additional fuel added to the hot exhaust flow of the gas turbine are lower flows, but have a higher velocity and temperature. The aim of the modeling undertaken in this work is to establish the combustion dynamics, degree of pre-heating required and the geometry essential to the design of combustion based VAM mitigation multi-generation systems.

Aug 1, 2013

By Michel L. Bilodeau, Brian W. Mackenzie, Dallas W. Davis

"The paper formulates an evaluation procedure for examining the effects of location on the economics of developing mineral deposits. This methodology is applied to assess locational aspects of Nova Scotia's competitive position f or mine development relative to other Canadian regions and provinces. The appraisal concerns two representative mine development opportunities, a medium-size open-pit tungsten deposit, and a small underground gold deposit. The influence of regional economic conditions is initially assessed. Then, the consequences of taxation are isolated. Finally, the combined impact of regional and taxation conditions is examined. SettingThe economic potential of mining may be assessed in a number of ways. One approach, increasingly used for both corporate planning and government policy purposes, is to evaluate the competitive position of an actual or potential mineral producer in the international marketplace relative to other suppliers.Such examinations of competitive position vary from cost league comparisons of breakeven costs for operating mines, through the assessment of medium-term costs associated with developing new mine capacity, to long-term evaluations of the economics of mineral supply from the start of exploration. The complexity of the analysis increase s with the scope and timeframe of interest. Many factors are involved. One component of competitive position is the quality of the mineral resources available. Other key factors include existing technology, wage and salary rates, labour productivity, the cost of capital, infra structure requirements, distances from sources of materials supply an d to mineral markets, management attributes, organizational efficiency, government mineral policies (particularly taxation), and inflation and exchange rates. The paper fits within this competitive position framework.The variable economic conditions which exist within Canada have a direct bearing on the viability of mine development and, thereby, on mineral exploration potential. The paper examines locational aspects of Nova Scotia 's competitive position."

Jan 1, 1986

By Rajiv Kalra, Ji Jiangang

"This paper reviews the following aspects of the world’s largest manufactured Grinding Mill’s in terms of diameter and power, along with the world’s biggest shop assembly and trial run of the mills delivered to Sino Iron Magnetite Project in Australia.1. An overview of the basic flow sheet of the Sino Iron (Magnetite) Project located in Australia2. An overview of in-house designed CITIC Heavy Industries 12.2 m (40ft) F x 11 m(36ft) LG – 28MW AG mills including FEA and major components3. In-house manufacturing at CITIC-HIC work in Luoyang China of all major components for 6 off Ø12.2 m(40ft) AG mills and 6 off Ø7.9 m(26ft) x 13.6 m(44.6ft) LG – 2 x 7.8 MW Ball Mills4. Major aspects of design and preparation of the biggest shop trial run of Ø7.9 m(26ft) x 13.6 m(44.6ft) LG Ball Mill witnessed by international EPCM’s and clients in July 2009.5. Major aspects of one piece assembly of 1300 tonne rotating element of the Ø12.2 m(40ft) x 11 m(36ft) LG AG Mill and Ø7.9 m F (26) x 13.6 m(44.6ft) LG Ball Mill at the port of the export China and transport to Australian Port and then to site.6. An insight to unique installation methods used for Ø12.2 m(40ft) and Ø7.9 m(26ft) rotating element lifting on the mill foundation in one piece assemblies.7. CITIC Heavy Industries present capability for in house design and manufacture of Grinding Mills up to Ø13.7 m (45 ft) with 35 MW Gearless drives and Ø12.2 m(40ft) with 2 x 10 MW Geared Mill drives"

Jan 1, 2012

By A. Ghahremaninezhad, E. Jorjani, A. Riahi, Islamic Azad University, B. Nazari, H. Hani, Z. Manafi

The presence of a high iron concentration, 9.1 g/L, in the raffinate of the Sarcheshmeh copper heap bioleach process led to the formation of various types of jarosite, (K,Na,NH4,H3O)Fe3(SO4)2(OH)6, on the heap mineral surfaces. This study probes iron removal from the raffinate using a bio-oxidation process based on A. ferrooxidans bacteria in the presence and absence of jarosite seed. The jarosite seed was biologically synthesized using A. ferrooxidans bacteria. The effect of solution pH (1.5 to 2.5) and jarosite seed dosage (0 to 15 wt.%) on iron removal was examined. It was demonstrated that the concentration of iron ions present in the raffinate decreased from 9.1 g/L to 2.5 g/L with the addition of 10 wt.% jarosite seed at pH 2 and 130 rpm mixing rate at 32°C. Three different types of raffinate including (1) native raffinate containing 9.1, 3.4, 5.7 g/L of total, ferric and ferrous iron, respectively, (2) bio-oxidized raffinate in the absence of the jarosite seed containing 8.5 g/L total iron (mainly ferric with negligible ferrous), (3) bio-oxidized raffinate in the presence of jarosite seed containing 2.55 g/L total iron (mainly ferric with negligible ferrous) were used in mesophilic, moderate thermophilic and thermophilic bioleaching processes. The results of the flask tests showed that the highest copper bioleaching recoveries of 9.4, 49.4 and 90.8 % were achieved using raffinate (3) with mesophilic, moderate thermophilic and thermophilic bioleaching processes, respectively.

Jan 1, 2016

By Harry Siewert, Tom Milner, Jack Stickney

"LocationThe Gibraltar mine is located in central British Columbia (NTS 93B/9W), 362 km north of Vancouver. Access is provided by 20 km of paved road from McLeese Lake, which lies 45 km north of Williams Lake on Highway 97. Latitude and longitude of the mine are 52° 30' and 122° 16', respectively.The total area of the McLeese Lake site is approximately 1700 ha (4200 acres). This includes the orebodies, dumps, surface drainage collection system, plant site, roads and tailings ponds.Brief Description of OperationOre is mined by open pit methods and is concentrated using conventional crushing, grinding and flotation processes. Copper and molybdenum flotation occurs at an average rate of 40 000 tons per day. Tailing is discharged to an impoundment area and the water recycled as process water. Additional copper is extracted from the waste dumps using sulphuric acid as a leach solution followed by solvent extraction and electrowinning.HistoryExploration by Gibraltar began in 1964, continuing until late 1970, at which time it was announced that the property would go into production. Construction started in early 1971, with initial production in March 1972. Target capacity of 30 000 tons per day was achieved by the end of March and is currently at 40 000 tons per day.Ore reserves as of January 1, 1998 were 184 384 000 tons grading 0.31% Cu and 0.010% MoS2."

Jan 1, 2000

By P. E. Cavanagh

Introduction A comprehensive study of the economics of processes for smelting iron ores has been made by the Ontario Research Foundation on behalf of the Ontario Research Commission. This survey has included investigations of all processes in commercial use, and proposed processes which are still in the experimental stage. The two main objects of this work were to discover (l) whether any known processes would be particularly suited to present and future Canadian conditions, and (2) whether any new process would be of assistance in solving the present scrap shortage in Canada. The future prospects of the Canadian iron smelting industry have changed radically in the past ten years. For nearly twenty years before 1939 no iron ore was mined in Canada. The ore used was imported, mainly from the United States and Newfoundland. The economics of iron blast-furnace smelting always force the location of blast furnaces near the source of coal for making high-grade metallurgical coke, and near the market for iron and steel, rather than near the iron ore. Blast-furnace installations in Canada are confined to the north shores of the Great Lakes with ready access to United States coal and ore and the major Canadian markets, and to Nova Scotia near the coalfields of that Province. This distribution of primary smelting capacity naturally results in relatively high prices for iron and steel in the West, the North, and in Quebec.

Jan 1, 1948

By V. N. Mackiw, H. Veltman

"A process is described which permits the separate recovery of lead and zinc from complex low-grade sulphide concentrates such as are produced from the New Brunswick type of disseminated pyrite ores. This process calls for the preparation of a lead-zinc bulk concentrate from the original ore by flotation. The bulk concentrate is then oxidized under pressure in autoclaves in aqueous sulphuric acid solution, such as return electrolyte from zinc electrolysis. This yields a zinc sulphate solution and a residue containing lead sulphate, unaltered pyrite and elemental sulphur generated during the oxidation. After the oxidation, the leach slurry is briefly heated to above the melting point of elemental sulphur and then cooled. Thus, pellets containing pyrite and elemental sulphur are formed, and they are separated from the lead sulphate by screening and/or flotation. Laboratory tests have shown that about 95 per cent of the zinc and lead can be separately recovered from complex bulk concentrates. Process possibilities are discussed."

Jan 1, 1967

By A Falter

Gyroscopic surveying instruments, which apply the physical law of a gyroscope, are being used for deter-mining the azimuth of lines with a high degree of ac-curacy. In the past ten years, gyro-theodolites have been introduced widely for underground orientation in the mining industry of Russia, Germany and South Africa. Gyroscorpic methods eliminate awkward procedures of conventional shaft plumbing, and provide more safety, excellent control and the highest precision at any point under-ground without interference with hoisting operations. The advantages of gyroscopic orientation in geodetic surveys become obvious in primary and secondary triangulation, in the determination of co-ordinates of single triangulation points, using the method of trigonometric re-section and intersection, and when traversing over long distances or in areas with obstructed view. Other fields of application are found in geophysical surveys and in the orientation of technical objects; e.g. radar stations, relay stations and ballistic missiles.

Jan 1, 1964

By C. M. Clapperton, K. E. Darke, A. J. Boyce, C. M. Rice, S. D. Redwood

"Abstract - The Kori Kollo gold deposit is hosted by a c.15 Ma sericitized dacite stock in the La Joya district on the Bolivian Altiplano. The mineralization is of the Bolivian polymetallic vein (BPV) type, with a significant amount of the gold reserves contained in the oxide cap. Field and microscopic studies, K-Ar dating, ??34S values of pyrite, alunite and jarosite, and ??18O values of alunite and jarosite demonstrate that some of this gold is supergene. Two types of supergene gold are present: minute gold grains, 1 to 10 microns across, of high fineness and associated with jarosite and iron oxy-hydroxides; and ‘invisible’ gold, which is probably sorbed onto minerals such as jarosite and iron oxy-hydroxides.Pyrite ??34S values fall in the limited range -3.5 ± 0.6‰, consistent with a magmatic origin. Sulfate ??34S values are homogeneous and overlap closely with those of pyrite (-1.2 ± 2.1‰), which supports petrographic evidence that sulfates replaced pyrite. By contrast, sulfate ??18O values are inhomogeneous with a large range (alunite +2 to 26‰, jarosite -5 to +18‰). These data are interpreted as reflecting kinetically controlled reactions involving various proportions of atmospheric oxygen and local meteoric water. This is typical of supergene alteration and is due to the seasonally dry climate of the Altiplano.The oxide-zone mineralogy is dominated by sulfates and iron oxy-hydroxide minerals with some phosphates and halides, which indicates that the groundwaters were acidic, oxidizing and relatively saline. Under these conditions the most likely complexes responsible for gold mobilization are halides.Geological data and K-Ar ages indicate that oxidation of the BPV deposits began at least around 11 Ma and possibly up to 15 Ma ago, and that supergene alteration lasted until around 4 Ma. During this period, erosion was minimal. Although supergene processes have been active on the Bolivian Altiplano since the Middle Miocene, in contrast to Northern Chile, enrichment of gold has not occurred."

Jan 1, 1997

By Jie Deng, Wenliang Xiong, Binyan Chen

"With falling rare earth metal prices, low cost beneficiation of rare earth minerals is essential. The “Flotation-Agglomeration-Magnetic” (FAM) separation process is a newly developed technology by IMUMR to economically recover rare earth elements from different types of deposits. The theory of FAM process is to selectively agglomerate rare earth particles and separate from gangue minerals by bubble flotation process. The flotation product is further upgraded by magnetic separation. The FAM process has been successfully applied in industrial production on the Dalucao rare earth ore, Sichuan, China. The average REO grade of rare earth concentrate is 65% in the latest 12 month production run, with an average recovery of 55%.INTRODUCTIONRare earth elements (REEs) include fifteen lanthanide elements coupled with two chemically similar elements (yttrium and scandium). These elements are split into two sub-groups, La to Sm are classified as light rare earth elements (LREEs) and the remaining elements including yttrium are heavy rare earth elements (HREEs) (Kumari & Panda, 2015). The demand of rare earth elements surged in recent years due to their increasing usage in diverse industrial aspects including high strength magnets, phosphors, clean energy, polishing compounds and catalysts (Goley &Scott, 2014).More than 250 REE-bearing minerals have been discovered, but many minerals are with very low concentrations of REEs, varying from 10-300 ppm (Adam &Ping, 2013). The most common rare earth minerals mined are bastnaesite, monazite, xenotime and ion-adoption REE (Chelgani & Rudolph, 2015; Kanazawa & Kamitani, 2006). Before the 1960s, most rare earth resources were extracted from monazite in the beach placer, with the exploiting of Mountain Pass in the United States and Bayan Obo mine in China, bastnaesite became the chief mineral source of rare earth resources (Klinger, 2015). These minerals are commonly separated with gangue minerals by froth flotation, gravity concentration, magnetic separation, or any combination thereof based on their specific physical characteristics (Zhou & Wang, 2014; Adam & Richard, 2014; Yang & Satur, 2015; Xia & Brian, 2015a,b)."

Jan 1, 2016

By G. A. Gross

"Nearly 90 per cent of the iron ore produced in Canada is derived from iron-formation or bedded iron deposits. About 70 per cent of this consists of concentrates obtained from iron-formation; another 20 per cent was formed by natural enrichment processes.Four principal varieties of iron-formation are recognized -the Algoma, Superior, Clinton and Minette types. Differences in their geology, mineralogy, chemical com-position and environment of deposition are of special significance in their evaluation as ore.The properties of the ores, including grade, beneficiation qualities and minor element content in taconites, metataconites and naturally enriched ores, reflect characteristics of the primary stratigraphie units from which they are derived. A detailed description of the stratigraphie facies is essential for efficient utilization of these source beds."

Jan 1, 1966

By H. Arima

The Akita Zinc Company is the only refinery which produces hematite from the iron content in the zinc leach residue. The Akita Hematite Process consists of five stages, which are SO2 pressure leaching, the first neutralization stage, the de-arsenic process, the second neutralization stage and pressure hematite precipitation. In order to strengthen its cost competitiveness and stabilize its operation, the Akita Hematite Process has been modified continuously. Most recently, two process modifications were carried out. The first was an improved ability to maintain a lower arsenic concentration in the de-arsenic process, and the second was an increased throughput in the hematite precipitation autoclave. The details of these recent changes in the Akita Hematite Process are presented in this paper.

Jan 1, 2006