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By S. Banisi, E. Arghavani, Gh. Parsapour, S. Mousavi

Maximization of water recovery in thickeners is an essential step in the mineral processing industries. The Gol-E-Gohar iorn ore processing plant uses a center pier thickener with a diameter of 38 m and depth of 4 m. The feed rate is 50 t/h solids with a concentration of 5% (w/w), and it has been designed to provide an underflow containing 50% solids. The performance of the thickener was not as expected judged by the overflow stream containing 0.6% solids and water loss of 52 m3/h in the underflow. A criterion called the index of flocculation incorporating the perimeter-based fractal dimension of flocs, floc size, and settling velocities was proposed and used to determine the optimum flocculant dosage which was found to be 20 g/t. The fractal dimension of flocs in a pulp containing 5% solids was found to be between 1.16 (no flocculant) and 1.56 (40 g/t flocculant) which indicated highly branched and loosely bound structures for the flocs as flocculant dosage increased. At these conditions, the size of the flocs which was recorded by a digital microscope increased from 93 µm to 403 µm. A new feedwell with a special design with the aim of preventing flocs breakage and maximizing energy dissipation of pulp was constructed and installed. These modifications led to an increase in the thickener drivehead torque from 5% to 18% of the rated torque, indicating a higher bed depth. Finally, installation of a PID controller reduced the drivehead torque relative oscillation from 52.0% to 12.7%. These changes increased the solids concentration of the underflow from 49.0% to 56.9%, decreased the overflow solids concentration from 0.6 % to values smaller than 0.01% and resulted in a reduction of 27% in water loss in the thickener underflow.

Jan 1, 2014

By R. Drozd

"The Bui/moose Mine is in the northeast coal area of British Columbia, and less than $300 million was spent to bring this 2.3 million-tonnes-per-year metallurgical and thermal coal mine into production by November 1, 1983, one month ahead of schedule. The project is an unincorporated joint venture undertaking, with Teck-Bullmoose Coal Inc., a wholly-owned subsidiary of Teck Corporation, holding 51%, Lornex Mining Corporation holding 39%, and Nissho-lwai (Canada) Ltd. holding 10%. Bullmoose Operating Corporation will be the manager and operator of the project. This paper will broadly cover the history and exploration work on the property, the geology, open-pit mining plans and equipment, the preparation plant flowsheet from breaker station to clean coal silo, the 35 km highway truck haul, the railroad loadout system, manpower requirements, approvals and permits, and general financial arrangements. Introduction The Bullmoose Mine Project is located about 87 km by road south of Chetwynd, B.C. and consists of an open-pit coal mine, a plant facility in the Bullmoose Creek valley below the mine, and a separate rail loadout facility on the British Columbia Railway Branchline near the new town of Tumbler Ridge some 35 km by road to the east. The plant will be capable of producing a total of 2.3 million tonnes per year (mty) of washed metallurgical and thermal coal. Long-term metallurgical coal contracts for high-quality, medium-volatile, bituminous coal have been signed with nine Japanese buyers for 1.7 mty, and the balance of0.6 mty will be for thermal coal production. Plant construction began in the spring of 1982, and in May 1983, preproduction waste and overburden removal in the mine was started. The plant began tuning up in October and was fully operational by December 1983. Metallurgical coal began moving to the coast in unit trains during November, and first vessel loading at the Ridley Island port began in late December 1983."

Jan 1, 1985

By L. F. Zeiler

In the past, health concerns in coal mines have primarily centered on those elements which have been essentially inherent to the mining environment. These would include respirable coal mine dust, respirable crystalline silica, excessive noise levels, and diesel exhaust particulates. Commercially-available chemical products are prevalent on mine property. These potentially toxic materials are chemical formulations that can degrease, clean, and lubricate metal parts, separate coal from rock in float/sink operations, and aid in roof consolidation, among other uses. As the general public has become more aware of the hazards of chemical exposures, miners have likewise become more concerned about working with an ever-expanding variety of chemical products on the job. Often, product or chemical specific hazard communication training is inadequate or ineffective, and miners do not know exactly what the ingredients are in the products they handle, or the health hazards involved with their use or misuse. Currently, the Mine Safety and Health Administration (MSHA), by law, enforces 1972 Threshold Limit Values (TLV). MSHA is making preparations to adopt new personal exposure limits for enforcement. The values given throughout the article are 1994 TLV's and are not enforcement standards, but are used for discussion purposes. They reflect the current scientific thinking regarding personal exposure to these chemical agents. An overview of these products is presented, and the potential health hazards associated with their use are discussed. Controls needed to prevent overexposures, such as proper handling procedures and personal protective equipment, are covered. Methods used to collect and identify contaminants are presented.

Jan 1, 1995

By Peter Faust, Peter Hubbard, Kenichi Soga

The European Federation of Foundation Contractors (EFFC) and The Deep Foundations Institute (DFI) have set up a task group to compile a Guide for Working Platforms. The first edition of this Guide has been published in January 2020. The aim of the Guide is to provide reliable methods for design, testing and verification of working platforms for construction equipment, especially in the deep foundation industry where track loads can be excessive due to the nature of its operations. The Guide has identified areas where knowledge is limited. Actual track pressure and its distribution along the length of the tracks is still not well researched. Current recommendation provided in EN 16228-1 are believed to be overly simplified and may lead to conservative requirements for working platform thickness. This paper presents results of a series of field tests where the actual track pressure of a large drilling rig during operation was measured in real time together with the deformation of the working platform. Embedded, distributed fiber optic sensing (DFOS) at different depths throughout the platform allowed for a three-dimensional evaluation of the platform deformation throughout the entire operation. Results will help to develop more reliable recommendations for future safety requirements of working platforms for deep foundation equipment.

May 1, 2022

By Matthew N. Rubin

This report summarizes the work performed under USBM Contract No. H0155155, "Demonstrating the Noise Control of a Coal Preparation Plant." A Consolidation Coal Company coal preparation plant (the Georgetown Plant) was selected for demonstration of various noise control techniques and materials in a commercially operating plant. At the start of the project, the 1650 tons per hour (tph) plant was surveyed to document the existing sound levels and worker noise exposures. On the basis of the survey, individual noise sources were characterized and assigned priorities for treatment. Four categories of noise control treatments were installed in this plant: ? Resilient impact pads ? Curtains ? Chute liners ? Resilient screen decks. Currently (1977) available resilient impact pads and curtains were found to be suit-able for general use in coal preparation plants; in the Georgetown Plant, they provided significant noise reduction [6 to 10 dB(A)]. The overall performance of the chute liners which also provided useful noise reduction, was strongly dependent on the specific installation. Although the resilient screen decks have the potential for 7 to 9 dB(A) of coal/screen impact noise reduction, blinding and delamination (in composite decks) en-countered at the Georgetown Plant represented major design problems for these products. This program achieved noise reductions of up to 10 dB in various areas of the Georgetown Plant (within the restrictions imposed by the plant's operation) resulting in significant reduction in worker noise exposures.

Jan 1, 1977

By N. Greninger

The Bureau of Mines conducted a laboratory study of the measurement of the water and rock dust (RD) contents of synthetic mine-type coal dust (CD) mixtures using a commercial unit for measuring water content and several prototype radiometric units for measuring the RD content. The RD content ranged from 50 to 100 wt pct and the added water (AW) ranged from 0 to 15 wt pct. The total water (TW) content (intrinsic (IW) and AW) of a small dust sample could be readily measured automatically by essentially untrained personnel using a commercial unit. The RD content of a sample containing only IW could readily be measured by moderately trained personnel using several radiometric units. With gamma-ray devices, about 300 g of sample is needed. With the improved beta-ray device, about 25 g of sample is needed. With dry mine dust samples, the estimated RD error range for gamma-ray devices is 0.8 to 2.3 pct and 0.5 to 1.0 pct for beta-ray devices. However, the radiometric measurement of RD content was questionable if the dust mixture also contained AW or if it was uncertain whether the dust mixture contained AW.

Jan 1, 1988

By Michael E. Henderson

The U.S. Bureau of Mines (BOM) constructed the Hydraulic Transport Research Facility (HTRF) to investigate the hydraulic parameters relating to the transport of coarse coal. To achieve these goals in a timely and efficient manner, the Bureau contracted to Boeing Services International, Inc. (BSI) the responsibility of operating the HTRF and providing technical support. This data report is a summary of the testing and data results for the period from 16 September to 1 November 1983. The testing covered herein is for coarse 2-in by a (minus 50 mm) Pittsburgh Seam coal in a 12-in (3 00 mm) pipeline, at velocities ranging from 5 to 18 ft/s (1.5 to 5.5 m/s) and at concentrations ranging from 15 to 55 pct.

Jan 1, 1985

By John A. Rusnak

"This paper discusses the variation of coal strength based on the megascopic coal lithotypes for Central Appalachian high-volatile A coal beds. The composition of coal beds is complex and variable, depending on the depositional environment associated with original plant material, inflow of clastic material, and water level fluctuations in the original swamp/mire environment. Thus, different types of coal and sediment are formed within each coal bed. These differences in coal composition were first classified by Marie Stopes, a paleobotanist, in 1919. The classic coal megascopic lithotypes are vitrain, clarain, and durain, which correspond to bright, bright banded, and dull coal, respectively. Stopes also identified that the lithotype fusain, which is mineral charcoal, has no inherent strength and can act as a plane of discontinuity. In this study, two other coal-bed lithologies are also considered—bone and carbonaceous shale. This makes for a comprehensive suite of coal-bed stratigraphic components apart from rock partings. A total of 1,000 uniaxial compressive strength (UCS) and 440 indirect tensile strength (ITS) tests were conducted on cores from southern West Virginia that were specifically logged and described using the megascopic coal lithotype nomenclature. Statistical analysis is presented showing the results for each lithotype group with mechanical properties correlated to the lithotype. Previous studies have analyzed the mechanical breakage properties associated with coal lithotypes, which correlate well with these results. However, coal rank does appear to be a contributing factor, and this study is confined to only high-volatile A bituminous rank. Application of these results would be well suited to a rock mass classification system to address coal pillar rib stability. This would allow for rib support design and implementation to consider relative coal strength by visual observation of the seam stratigraphy through ongoing observations within a mine. Changes in seam composition can be readily identified, allowing the adjustment in rib support design. Another application would be for the determination of numerical modeling inputs based on detailed seam stratigraphy. However, these results, even with the standard strength reduction criteria, may not be applicable to currently accepted empirical coal pillar design procedures."

Jan 1, 2017

By Dave J. Porter

Si bien, los proyectos son el camino para que una organización minera cumpla con su estrategia, la gran mayoría de su historial de cumplimientos son un fracaso puesto que el impacto del proyecto no es tan rico en sus etapas y las organizaciones mineras no pueden cumplir con su visión y estrategía. En ese sentido, el presente texto señala la importancia de una adecuada gestión de proyectos para que la organización minera cumpla con su estrategia. Así, la madurez de la gestión de proyectos es un indicador de éxito continuo y requiere de visión, compromiso en las etapas iniciales, ya que sus ganancias son difíciles de cuantificar.

Apr 1, 2012

By Jan Van Greunen, Mark Vanderzee, David Haug, Geoffrey Hughes, Yiming Sun, Roozbeh Geraili Mikola

"The Sanitation Districts of Los Angeles County is planning to construct a new, approximately 7-mile-long (11.3 km) effluent outfall tunnel to be excavated by TBM and lined with precast concrete segments. Anticipated net operating pressures within the tunnel are expected to approach 3 bar. To counteract joint opening and exfiltration leakage, an approach has been investigated to post-tension the precast concrete tunnel lining with steel tendons. The tunnel alignment crosses several seismically active fault zones, at which installation of steel pipe is proposed as a secondary inner lining to mitigate potential offset displacements. This paper discusses the tunnel lining design approach and methods used to address these unique challenges.INTRODUCTION The Sanitation Districts of Los Angeles County (Sanitation Districts) is planning to construct a new 18-foot-diameter (5.5 m), approximately 7-mile-long (11.3 km) tunnel from the Joint Water Pollution Control Plant (JWPCP), located in the City of Carson, to the existing White Point outfall manifold structure at Royal Palms State Beach (RPSB) (Figure 1). The project is part of the Sanitation Districts’ Clearwater Program, which will improve overall system reliability through the repair and replacement of the existing aging infrastructure. The existing system includes two 6-mile-long (9.7 km) tunnels, 8- and 12-feet in diameter (2.4 and 3.7 m), and four ocean outfall pipes with a maximum capacity of approximately 675 million gal/day (MGD) (2.6 billion L/day). Addition of the new parallel tunnel will increase overall capacity to accommodate peak wet weather wastewater flows of up to 1,262 MGD (4.8 billion L/day) and will allow inspection and repair of the existing tunnels. The new outfall tunnel will be excavated using a pressurized face tunnel boring machine (TBM). Shafts at the north (JWPCP Shaft) and south (RPSB Shaft) ends of the proposed alignment will connect the tunnel to the existing wastewater treatment plant and existing ocean outfalls manifold and during construction act as launch and receiving shafts for the TBM. The tunnel will be excavated from north to south as a single heading."

Jan 1, 2016

Safety rules for installing and using electrical equipment in and about coal mines covered in this information circular supersede those previously included in Bureau of Mines Bulletin 514, issued in 1952. This revision brings these rules up to date and more nearly in line with present operating and safety practices in the industry. The rules are intended to supplement existing Federal and State regulations, and no provision shall be construed to oppose or supersede any provisions of the Federal Mine Safety Codes, the Federal Coal Mine Safety Act, or the mining laws of any State. The rules were designed to permit progress, such as application of new or improved materials and equipment or use of new practices where these materials, equipment, or practices retain or improve the level of safety established by these requirements. It is hoped that they will fill the need for a concise edition for mine electricians and electrical engineers, especially those who do not have ready access to more detailed rules or codes.

Jan 1, 1964

By Mark C. Russell, Charles T. Russell, Brooke Colburn, Parker Bailey, Desiree Bernhard, Kaito Durkee, Tristen Cutshall, Rob P. H. Urselmann

Hypersonic tunnel boring (HTB) uses directed, high velocity projectile impacts to remove rock. HTB is highly independent of rock strength and targets hard, abrasive rock and variable rock environments. This paper discusses history, theory and presents test (2×2 m and .75×.5 m tunnels) field trial results and technical and economic evaluation. The HTB tests are compared against the historic ‘project REAM’ and the concept against tunnel boring machines and drill & blast in design studies for full-scale 12 m and 4.5×5.5 m tunnels. The positive results indicate that under these conditions HTB can replace Drill & Blast and Tunnel Boring Machines.

Jun 13, 2021

By L. A. Morley

Volume III of the final report examines the indication versus interruption procedures used on motion-drive power equipment, with emphasis on surface excavators. The report begins with a review of the electromechanical acid conversion used with the Ward-Leonard control system. Protection criteria for the drive-system components are then discussed. Fault sources and fault calculations for both the ac supply source and dc power loop are introduced to assist in discussing indication and interruption procedures. The subject is then expanded to examine the dynamic process of the machine and determine the effects of fault current and position of the machine to allow for an orderly shutdown. With this analysis, possible indication an interruption procedures are given for the four-quadrant duty cycle of excavators. The report concludes by introducing other mining operations that utilize similar motion-drive systems and also static (solid-state) drives and recommends further research in these areas, as well as a more detailed examination of the dynamic fault analysis for excavators.

Jan 1, 1982

By David F. Gearhart, Khaled M. Mohamed

"Trusses are primarily used as passive roof supports in coal mines. They are constructed of three main parts: two grouted bolts installed at opposing forty-five degree angles into the roof so that they are anchored over the ribs and a cross member that ties the angled bolts together. There is also hardware used to assemble these components. The capacities of the angled bolts are typically 30 to 40 tons and the tensile capacity of the cross member is also 30 to 40 tons. Importantly, the direction of the immediate roof loading on the cross member is unlike the direction of the loading on the angled bolts. The load on the cross member is transverse to the longitudinal axis instead of along it, and therefore the cross member is loaded in the weakest direction.Previous tests conducted on truss systems applied loads such that the increasing tension in the two diagonal bolts increased the tension in the horizontal cross member, resulting in a stiff response. By contrast, if the load is applied directly to the cross member, which then transmits those forces to the diagonal bolts, it results in a much softer response.Based on this difference, laboratory tests to apply transverse loads and measure the vertical load capacity of three different types of cross members were conducted using the Mine Roof Simulator (MRS) located at the National Institute for Occupational Safety and Health (NIOSH) in Pittsburgh. The length of the samples was about 16 feet. Single-point load tests, with the load applied in the center of the specimen were conducted to verify the performance of the test arrangement and the finite element models. Double-point load tests, with a span of eight feet, were also conducted. This arrangement replicates the performance of the cross members with a distributed load. Both of these test arrangements were conducted on one-inch-diameter threaded steel bars and 0.7-inch-diameter cable and 0.6-inch-diameter cable cross members.For the single-point load configuration, the yield of the one-inch bar was nominally 22 kips of vertical load, achieved at 17 inches of deflection. For both sizes of the cable cross members, yield was not achieved even after 18 inches of deflection. Peak vertical loads were about 20 kips for the 0.7-inch cables and 15 kips for the 0.6- inch cables. For the double-point load configurations, the one-inch bar cross members yielded at 33 kips of vertical load and 10 inches of deflection. The 0.7-inch-diameter cable cross members broke strands at 30 kips of vertical load and 10 inches of closure, and the 0.6-inch-diameter cable cross members broke strands at 25 kips of vertical load and 10 inches of closure. Finite element models of each of the six different configurations were developed and show the variation of the vertical capacity of the cross members and the difference of the behavior of the bar versus the cables."

Jan 1, 2015

By Kristin K. Mueller, Lucie Coudert, Thi Yen Chau Nguyen, Lan Huong Tran, Jean‑François Blais, Guy Mercier

Fluorite (calcium fluoride—CaF2), also known as fluorspar, is an industrial mineral used in metallurgy, hydrofluoric acid production, and ceramics manufacturing. Based on the results from a previous study, a low-grade fluorspar by-product (20.0% CaF2) originating from the exploitation of a rare earth carbonatite deposit can be improved to 75.4% by combining magnetic separation and acid leaching. The present research aimed to develop and optimize a column flotation process to increase the purity of this fluorspar by-product by removing residual silicate minerals and meeting the requirements for ceramic manufacturing (> 85% CaF2). The optimal flotation conditions required for maximizing the recovery and improving the grade of a fluorspar by-product were identified using a conventional approach combined with a response surface methodology (Box-Behnken design). Optimal fluorspar flotation was achieved under the following conditions: 3.6 g/kg of sodium oleate as the collector, 2 g/kg of sodium silicate as the pH modifier and depressant, a conditioning time of 35 min, a flotation time of 7 min, and a solid-to-liquid ratio (S/L) of the pulp of 5%. Under these conditions, 86.8% fluorspar recovery was achieved, and the grade increased from 76.5% in the feed (metallurgical grade) to 88.6% (ceramic grade) in the final concentrate. The silicon content decreased from 5.66% in the feed to 1.12% in the fluorspar concentrate. Using magnetic separation before the flotation improves the final content of fluorspar in the concentrate with the final grade of 94.4%.

Sep 9, 2022

By Susan Rafalko, Mike Walker, John Sankey, Sherif Aziz, Alex Potter-Weight, Mary Nodine, Frederic Masse

"After several successful projects on the Garden State Parkway and New Jersey Turnpike for support of single-stage MSE (Mechanically Stabilized Earth) walls using rigid inclusions (Controlled Modulus Columns) as an alternate to two-stage MSE walls and surcharge, the Bass River Bridge Widening project presented additional challenges in terms of soil conditions and height of embankment that created opportunities for the design-build ground improvement contractor and its MSE wall-designing partner to enhance their design and construction methods. The specialist contractor decided, in association with the wall system supplier, to perform an independent large scale instrumented test area on the project to demonstrate the ability of the design techniques to model the behavior of the system, as well as the capacity of the rigid inclusions to provide the necessary bearing capacity and settlement control to allow the construction of the highway without any consolidation period. This paper presents a detailed description of the design of the ground improvement system and MSE wall system, as well as the results and conclusions of the monitoring data gathered on the large scale test program. The combination of rigid inclusion ground improvement technologies, such as the CMC system, together with an MSE wall system allows for the rapid and economical construction of high embankment without waiting for a surcharge and consolidation period or the necessity to use a two-stage wall system. In-depth understanding of the design techniques and advantages of this combination will be provided and should be beneficial for any geotechnical engineer or owner looking for innovative solutions to save both time and cost on their projects.1. IntroductionAs development continues on sites with poor ground conditions throughout the world, conventional MSE walls remain a flexible design solution; however, construction of MSE walls in combination with ground improvement is becoming more frequent where extreme differential and/or total settlement prevail due to soft ground conditions. Various techniques have been used in the past in such conditions (e.g. conventional surcharge, staged construction, or two-stage MSE walls), even though these design solutions have typically involved longer waiting times for settlement to occur. As a result, conventional MSE wall design has been combined with a variety of ground improvement techniques consisting of rigid inclusions for an economical and efficient solution with the potential to accelerate construction and limit long term settlement. For the particular subject of this paper, the specialist contractor (Menard) proposed to use CMCs (Controlled Modulus Columns) to support the highest part of the MSE wall. CMCs are grouted displacement rigid inclusions installed in a grid-like pattern using a displacement auger. Before the CMCs are installed, a working platform may first need to be placed to allow equipment to move around the site depending on the ground conditions. Following the CMC ground improvement, an LTP (Load Transfer Platform) is installed prior to the construction of the MSE wall."

Jan 1, 2015

By D. R. East

Recent experiences within certain sectors of the international mining industry suggest an underestimation of the environmental risk associated with the design of mine waste management facilities. These experiences show that the technical and managerial challenge of responsible mine waste management is not always fully appreciated. Unfortunately, the image of the mining industry's environmental performance is negatively impacted by a relatively few number of failures. This negative view overrides the many positive contributions made by the majority of mining companies. The fact that these failures continue to occur to this day in both developed and developing countries is indeed remarkable, and indicates a degree of risk-taking approaching unacceptable levels. The design requirements for tailing storage facilities are, in many cases, more demanding than those of conventional water dams, because seepage of fluids which contain dissolved metals may pose a greater threat than the mere loss of water.

Jan 1, 1999

By D. J. MacDonald

The Bureau of Mines has conducted bench-scale investigations leading to the design of an integrated process for producing reactor-grade zir-conium oxide (Zr02) from zircon sand, which avoids the air pollution, water pollution, fire hazard, and odor problems associated with the hexone-thiocyanate process. The integrated process consists of three steps: production of crude zirconyl sulfate solution, solvent extraction, and production of Zr02 from strip liquor. This report describes the solvent extraction step. Multistage, countercurrent liquid-liquid extraction with a tertiary amine in kerosine was used to separate zirconium from a dilute H2S04 solution containing hafnium and other impurities. Process steps de-scribed include extraction from an aqueous feed solution to form a hafnium-contaminated, zirconium-bearing organic-phase solution, scrubbing to separate zirconium from coextracted hafnium, stripping to transfer hafnium-free zirconium into an aqueous strip liquor, chloride-loading to produce a chloride-bearing organic solution, scrubbing with the chloride-loaded organic solution to remove traces of uranium impur-ity from the zirconium-bearing strip liquor, and regeneration to pre-pare the organic solution for reuse. These steps were performed simul-taneously in steady-state, bench-scale experiments. Zirconium recovery of up to 93 pct was achieved. Results of an economic evaluation are included.

Jan 1, 1984

By Yan-Jun Shen

The rock mass classification system, BQ (basic quality), is the only national system that is suitable to most kinds of rock engineering in China. It uses two main aspects of the rock mass, the intact uniaxial compressive strength (UCS) and the rock intactness index (KV), to obtain the rock mass BQ. The index KV could be measured by the acoustic wave method. However, because this method is an indirect approach to characterize the rock mass structure, misfits often occur between the test results and the actual rock mass characteristics. Therefore, a new parameter KGSI expressed by the geological strength index is proposed to replace the original KV, and a new method is presented to express the value of BQ as a function of the UCS and the KGSI. Then, the underground excavations at five hydropower stations were chosen as examples to study the relationship between the revised BQ and the each of the international systems (RMR, Q or RMi). In addition, the applicability of the RMR, Q, or RMi system is discussed for China?s rock characteristics and geological conditions, and suggestions are given for improving the revised BQ system.

Aug 1, 2013

By H. X. Li, A. Correa, M. M. Zhang, W. Xuan, M. Andrade

"With increasing demand for steel and depletion of high-grade iron ore deposits, more research efforts are being directed toward extending the life of existing ore reserves and developing technology to treat low-grade iron ore resources. Among all the reported technologies, biotechnologies in mineral processing – specifically bioleaching and microbially induced flotation – have emerged to be considered as low-cost, environmentally friendly potential alternatives to many of the current mineral processing techniques. This paper provides a comprehensive review of current research on the use of microorganisms for iron ore beneficiation and, further, discusses the applicability of bioleaching, bioflotation and bioflocculation for the beneficiation of low-grade iron ores.IntroductionIncreasing global demand for raw materials has led to diminishing resources of high-grade iron ore. As a result, the mining and utilization of low-grade hematite, limonite, specularite, siderite and goethite ores have attracted more and more attention. However, these types of iron ores are of complex paragenesis and fine disseminated grain size, and often contaminated by phosphorus in the form of solid solution. The distribution of phosphorus throughout the iron mineral crystals prevents the effective use of physical separation techniques, and these complex ores are at present largely untapped due to a lack of cost-effective and efficient processing methods. Chemical leaching and roasting-magnetic separation approaches have been mainly tested only on the laboratory scale and are all either cost prohibitive or ineffective when used on low-grade complex iron ores."

Jan 1, 2015