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By Russell L. Wood

The title of this session seems to have been picked especially for this paper. It is 1984, it is the morning after, and there is one monumental hangover among many if not most of the oil companies that have invested in mining in the past decade or so. How an oil company looks at mining depends on what time period you are talking about. A few years back around the time of investment this is what they were probably looking at: 1. A balance sheet of their own that was beginning to go wild, with many of their commodity prices having already seen increases of two, three, or four fold, and with no end in sight. 2. A need to invest their earnings someplace fast before the stockholders or the government got too interested. And that someplace should be in an industry where their own management skills could be applied. (Only a true cynic would suggest that this is a form of job security) 3. In mining there was an industry amazingly similiar to their own, one working with non-renewable natural resources, dealing with the same types of government agencies, and having the same type of critics and pressures from the general population. 4. An industry that was somewhat backward as compared with their own, and one where a generous ration of the capital and management skills so handsomely bestowed upon the oil industry could be used to great advantage.

Jan 1, 1984

By C. E. Capes

The spherical agglomeration process provides an attractive method for the cleaning and recovery of fine coals in the form of compact oil-bonded pellets. In treating a washery effluent containing 50% minus 20 micron material by this technique, the slurry was first mixed under vigorous agitation with oil to deash and dewater the fine coal. The flocculated coal pulp was then formed into larger agglomerates on a modified balling disc. The operation of a semi-pilot scale process is described and an analysis of some of the operating and system variables is given. A semi-theoretical expression to predict the final agglomerate size under various conditions is derived and compared with the experimental data. Coal producers are faced with a growing requirement to clean and recover fine mesh coals. Greater mechanization of the extractive and preparation processes has resulted in finer-sized products containing larger quantities of associated foreign matter and preparation plant effluents contain quantities of fine coals which are potentially valuable. These losses will probably increase with the expansion of production and will require the development of effective disposal and utilization processes under pressure of the lack of adequate disposal areas, the enforcement of air and stream pollution laws, and the economic need to obtain the maximum yield of salable product(1)

Jan 1, 1970

By G. P. Larson

We define a specialized mineral market as follows: Specialized Markets are markets where a low volume of a given mineral is used to convey a large benefit to a specific product. Sales of these value added minerals to small markets generally require a different marketing approach compared to bulk or commodity markets for traditional minerals. Specialized and commodity markets are differentiated by several characteristics as listed in Table 1.

Jan 1, 1990

By C. Perea, O. Restrepo, C. Ihle, H. Estay

In this study, research on the use of monosodium glutamate for copper leaching, with emphasis on the thermodynamics and oxidant characteristics, is presented. Copper dissolution was conducted following a hydrometallurgical route, using monosodium glutamate in alkaline solutions. The effect of oxidizing agents such as hydrogen peroxide (H2O2) and potassium permanganate (KMnO4), and the efficiency of copper leaching with glutamate compared with glycine have been studied. Results, obtained at room temperature, showed 92% recovery of copper using 0.03 M hydrogen peroxide, 0.5 M monosodium glutamate at a pH of 9.44.

Mar 2, 2022

By Joe Hachey, Jerry Dorn, Jeff Schutt, Derek Penrice

"Sound Transit’s East Link Project, a $3.7 billion (2015 $), 14-mile light rail extension, will connect downtown Seattle with the rapidly developing east side cities of Bellevue and Redmond. Among the most technically challenging aspects of the Project is the 2,435 foot long Downtown Bellevue Tunnel (DBT), which will be constructed through the central core of Bellevue underneath 110th Avenue NE using a combination of Sequential Excavation Methods (SEM) and cut and cover tunneling. The 1,980 foot long central SEM component of the DBT will be mined at shallow depth through challenging and complex geology, comprised of glacially overconsolidated soils, containing both regional and perched groundwater conditions and in close proximity to existing high rise buildings. The paper shares lessons learned from the planning decisions and risk based approach to the investigation, design and procurement processes which shaped the DBT configuration and enabled a successful transition to the project’s construction stage. INTRODUCTION The East Link Project is a voter-approved $3.7 billion (2015 $), 14-mile extension of the existing Sound Transit (ST) light rail transit (LRT) system from downtown Seattle, across Lake Washington via I-90, to the cities of Bellevue and Redmond on the east side of Lake Washington. With targeted completion in 2023, East Link will provide riders with an efficient and reliable connection between the largest population and employment centers on the east side and downtown Seattle. The project alignment is indicated in Figure 1 below.ST completed the Preliminary Engineering (PE) phase of the East Link project in late 2011. Subsequently the final design contract for the easternmost seven miles of the project was awarded to the H-J-H Team, a joint venture comprised of HNTB, Jacobs Engineering and Hatch Mott MacDonald in February 2012. H-J-H’s final design scope includes approximately 7 miles of double-track LRT between the east end of the I-90 East Channel Bridge and the Overlake Transit Center Station. While the project scope is extensive and diverse, the focus of this paper is the DBT. The DBT is located immediately north of the East Main Station, and travels approximately one half mile through downtown Bellevue under 110th Avenue NE between Main Street and NE 6th Street; terminating at the Downtown Bellevue Transit Center (BTC) Station. The location and extent of the DBT is indicated in Figure 2."

Jan 1, 2016

By E. A. Martell, K. S. Sweder

INTRODUCTION Lung cancer in uranium miners has been attributed to alpha irradiation of basal cells of the bronchial epithelium by radon daughters, primarily by 7.7 MeV alphas from polonium-214 (Altshuler et al., 1964). It also has been was observed that for a given cumulative radon progeny exposure, uranium miners who smoke cigarettes have an incidence of lung cancer about 10 times higher than nonsmoking miners (Lundin et al., 1969). It has been pointed out that the large excess of lung cancer deaths among smoking uranium miners is a multiplicative effect (Doll, 1971), which suggested possible synergistic interactions between airborne radon progeny and cigarette smoking. Experimental studies of the complex pattern of interactions between radon progeny, cigarette smoke particles, and the cigarette smoking process are in progress in our laboratory. Preliminary results, reported elsewhere (Martell, 1981), implicate alpha radiation from indoor radon progeny in the etiology of lung cancer in all cigarette smokers. Cigarette smoking produces high concentrations of smoke particles of low mobility and respirable size--particles between 0.5 and 4.0 µm in aerodynamic diameter (see below). The attached fraction of indoor radon progeny is highly dependent on the air concentration of small particles from cigarette smoking and from other combustion sources (Martell, 1981). The size distribution and other properties of radon progeny associated with cigarette smoke particles enhances their effectiveness in the induction of bronchial cancer in man. In this paper we discuss the properties of radon progeny associated with cigarette smoke, the fractionation of radon progeny and modification of their aerosol properties in burning cigarettes, the role of 218Po in these processes, the production of insoluble 214Pb and 212 Pb enriched particles in burning cigarettes, and the consequent differences in the patterns of polonium isotope alpha irradiation in the bronchial epithelium of smokers. EXPERIMENTAL PROCEDURES Experimental methods used in these studies involve the use of small experimental chambers of known radon and radon progeny concentrations in combination with aerosol collection and sizing techniques and sensitive radioactivity detection methods. The use of low-level [ß-] counting for radon progeny determination, providing a measure of 214 Pb plus 214Bi activity, makes it possible to carry out chamber experiments with small radon emanation sources and relatively low air concentrations of radon and radon progeny concentrations in the range from 100 to 1,000 pCi per liter. Thus, for example, in a typical experiment we use a 10 nanocurie 226Ra solution standard in a 10 liter chamber, providing an equilibrium concentration of 1,000 pCi of radon per liter. In small sealed chambers, radon progeny plate out rapidly on the chamber walls, with steady-state concentrations of airborne progeny less than 2 percent of equilibrium levels. This is experimentally convenient because, upon introduction of high concentrations of cigarette smoke particles or small particles from other sources, there is a systematic ingrowth of attached radon progeny, providing a tagged aerosol source of known age and radon progeny composition. In some chamber experiments a 226Ra solution standard of small volume, acidified to O.1N HNO3, was used as the radon emanation source. When used with a bubbler the holdup of radon in an 8 ml volume of 226Ra solution standard at 0.1N HN03 was only 2% of the total radon in the chamber at equilibrium. For experiments with 212Pb-tagged aerosols, we used a dry Ba(228Th) stearate emanation source prepared by the method of Hursh and Lovaas (1967). 226Ra and 222Rn determinations were made by radon gas counting. The 222Rn in a sealed air or water sample is transferred, using helium gas as a carrier, successively through a dry ice cooled trap at -80°C to remove water, through ascarite to remove C02, and through a small activated charcoal trap at -80°C to collect the 222Rn. Subsequently, by heating the charcoal to 400°C, the 222Rn is transferred next to an LN2-cooled capillary trap, and finally into an alphascintillation counting cell of the type described by Lucas (1957). As already stated, radon progeny activities were determined by low-level [ß-] counting, which provides a measure of 214Pb plus 214Bi. The radon progeny samples, collected on efficient Delbag polystyrene micro-fiber filters or on impactor foils, are placed in close, sandwich geometry between two thin-walled flow counters inside shielding anticoincidence counters and a 15 cm thickness of steel shielding. This configuration provides nearly 4II geometry and a low background of only 0.25 to 0.30 cpm. Aluminum absorber was added to provide a combined thickness of absorber and counter wall exceeding 7.0 mg/cm2 to eliminate the variable contribution of 7.7 MeV alphas from 214Po. 212 Pb determinations also were carried out by low-level [ß-] counting, in this case using a combined absorber and counter wall thickness of 9.0 mg/cm2 to eliminate contribution of 8.8 MeV alphas of 21 Po. In each experiment the [ß- ]activity data were corrected for decay to an appropriate common reference time for assessment of activity distributions.

Jan 1, 1981

By Keith S. Liddell

he selection of mill design parameters to suit the applica­tion requirements can result in quite different operating parame­ters for each generic type of application, even though the basic mechanical layout of the mills may remain similar. The selection of the type and size of grinding media is very important to efficient and cost-effective operation, and to ensuring that the milled product achieves the required properties. Accordingly, the grinding media selection is seen as an integral part of the mill design. Consideration of the requirement for classification is important in order to achieve the optimum mill and circuit performance. This can lead to the circuit feed not being classified for a steady feed with minimal slimes and a low size reduction ratio. Feed containing on-size particles would be deslimed by open circuit classification. Closed circuit classification is performed where the feed fluctuates. The rheological characteris­tics of the circuit feed slurry can have an influence on mill performance, and needs to be allowed for. A common misconception frequently encountered is the belief that "a mill is just a mill". This is not the case with stirred types of mills, since the operating parameters selected for the mill can have a large effect on the product characteristics. For example, horizontal shaft high speed stirred mills have a com­pletely different grinding action to vertical shaft low to medium speed stirred mills, which results in large differences between the surface area produced at a given product size (Liddell, 1986). Hence, it can be misleading to apply test results or design procedures obtained from one type of mill to other types for scale-up. The Metprotech stirred mill, as applied in the mining and minerals industries, is a low to medium speed vertical shaft mill. The basic design has been discussed previously (Liddell, 1989). Currently, the largest mills that have been manufactured have an installed power of 400 kW. The largest chamber volume at this power is 6000 litres, containing IO t of grinding media. It is intended that the installed power will increase up to lMW as applications requiring larger sizes arise.

Jan 1, 1995

By David A. Holmes

Zeolites are crystalline, hydrated aluminosilicates of the alkali and alkaline-earth metals. Their crystalline framework is based on a three dimensional network of SiO4 tetrahedra with all four oxygens shared by adjacent tetrahedra. The alkali and alkaline-earth cations are loosely bound within this framework structure and may be exchanged, to varying degrees, with other cations or molecular water. Most zeolites can be reversibly dehydrated. At present, close to 40 natural zeolite minerals have been identified and over 100 zeolites have been synthesized. Zeolites are a family of hydrous aluminosilicate minerals whose physical properties provide unique features for a wide variety of practical applications. Zeolites have been known for more than 200 years, but it was not until the middle of this century that their economic potential and widespread occurrence in sedimentary rocks were known. Since 1950, literally thousands of articles and patents have appeared in technical literature, and commercial pro¬duction of natural zeolites may now exceed 1 Mt worldwide an¬nually. In the past 40 years, the zeolite mineral group has changed from that of a museum curiosity to one of an established industrial mineral commodity. According to Breck (1974), zeolites are characterized by the following properties: 1) High degree of hydration, 2) Low density and large void volume when dehydrated, 3) Stability of the crystal structure of many zeolites when dehydrated, 4) Cation exchange properties, 5) Uniform molecular-sized channels in the dehydrated crys¬tals, 6) Ability to adsorb gases and vapors, 7) Catalytic properties. All zeolites are molecular sieves, but not all molecular sieves are zeolites. Activated carbon, activated clays, alumina powder, and silica gels are also molecular sieves. Molecular sieves are materials that can selectively adsorb molecules on the basis of their size, shape, or electrical charge (Clifton, 1987). Commercial application of zeolites is based on the following physical properties: molecular sieving, ion exchange, adsorption, and catalysis. Potential commercial utilization includes hundreds of possible applications. The principal uses at this time, however, are as fol¬lows: -Ammonium-ion removal in waste stream treatment, sewage treat¬ment, pet litter, and aquaculture, -Odor control, -Heavy metal ion removal from nuclear, mine and industrial wastes, -Agricultural use, such as soil conditioner and animal feed supplement. An estimated 800 kt to 1 Mt of natural zeolites were produced and consumed worldwide in 1991. Eight small operators reported collective production and consumption of an estimated 18 kt of natural zeolites in the United States during 1991, mostly for feed additives and for odor control, aquacultural, agricultural, catalytic, and ion exchange applications (Eyde, 1992).

Jan 1, 1994

By James A. Clum

The shift to lower grade iron ores, e.g., magnetic taconites, resulted in a shift towards agglomeration practices which could effectively deal with the fine particle sizes generated in the liberation and concentration processes. If the iron bearing particles are not extremely fine, e.g., -1/2 in + 100 mesh, sintering is an adequate means of agglomeration.(1) For the more dispersed ores which result in fine concentrates (more than 80%,-325 mesh), the fine particles must be agglomerated by mechanical means before final hardening, e.g., pelletizing.(1) In the pelletizing process, the essentially mechanical step of balling is extremely critical since the strength of the pre-fired pellet determines the firing conditions. The ability of the proper amount of moisture to hold together a ball of the very fine ore concentrate particles has long been recognized. It is a charac¬teristic of the reaction at the interface between the ionic solid of the ore concentrate and the polar water phase which overlays the solids. The strength in such moisture laden balls, the green strength, is a strong function of the water content (Figure 1) and thus deteriorates rapidly for either a small excess or a small deficiency of moisture. For purposes of commercial practice, the control of green ball handling properties by accurate control of ball moisture is too demanding. Moreover, as the ball is heated towards its hardening tempera¬ture, e.g., 1300'C, there is a substantial drying reaction which would lead to such a low dry strength of the ball that it would not support its own weight much less the weight of other balls in a firing furnace.

Jan 1, 1976

By James L. Withiam, P. C. Kelsall

The manuscript of this paper was not available for publication when the Proceedings went to press. Should the authors elect, they may distribute copies at the time of the Symposium.

Jan 1, 1986

By BHAMIDIPATI S. SASTRY, Pavan Kumar Kattamuri, ADITYA PANDEY

The thermal conductivity of rock surrounding the airway is one of the most important thermal properties for estimating strata heat transfer into the mine air and for designing the air-cooling strategies. Several laboratory methods are available for the determination of thermal conductivity; however, most of them are complex and cumbersome. The present study explains the working principle of Lee’s apparatus which is relatively simple, easy to fabricate and use, and provides consistent results. In the present study, thermal conductivities of sandstone cores obtained from an Indian coal mine are determined using Lee’s apparatus. An approach is discussed for determining the temperature gradient of sandstone specimens while cooling and used for calculating thermal conductivity. The thermal conductivity of different sandstone specimens attains values between 2.37 and 2.59 W m− 1 °C−1. For different sandstone cores obtained from the field, properties including specific gravity, specific heat capacity, thermal diffusivity, and porosity, along with thermal conductivity, are determined and highlighted in this study.

Jul 20, 2021

By J. A. Cremeens, D. D. Overton, J. C. Varnier

"Slope failures that occurred in 2008 and 2009 at the Pikeview Quarry in El Paso County, Colorado, USA were investigated using three-dimensional discrete element modeling methods. Large scale block sliding failures occurred along weak bedding planes that dip steeply into an excavation located at the toe of the slope. Several mining sequences at the toe of the slope were simulated to evaluate the effects of various degrees of extraction and backfill on slope stability. Slope stability back analysis was conducted using pre-failure and post-failure conditions to determine the joint shear strength properties. Laboratory testing was also conducted to determine intact rock properties. Three-dimensional discrete element analysis was uniquely applicable to this evaluation because it allowed representation of shear stress of the basal sliding surface and it afforded evaluation of several scenarios of extraction and backfill at the toe of the slope. INTRODUCTION The Pikeview Quarry is an aggregate quarry located approximately five miles northwest of Colorado Springs in El Paso County, Colorado, USA. The quarry has been operated by several owners since the early 1900s. The Pikeview Quarry has been a major source of construction aggregate for the Colorado Springs area for many years (MSHA 1986). In the 1950s, the site was mined by Peter Kiewit and Sons to provide limestone for the construction of the nearby Air Force Academy. A large scale slope failure occurred on December 2, 2008, which stopped mining activity at the Pikeview Quarry. A second, related slope failure occurred on September 13, 2009. The second slope failure was located immediately adjacent to the initial December 2008 failure. The objective of this publication is to discuss the three-dimensional slope stability evaluation. The causal relationships of slope instability are not within the scope of this publication. However, omitting the precursors to slope failure would limit understanding of the nature of the slope stability evaluation. The regional and local geology and the history of slope instability at the Pikeview Quarry aid in understanding these precursors. Two main failure mechanisms were hypothesized during the failure investigation to explain the triggering of the 2008 and 2009 large slope failures at the Pikeview Quarry. Both mechanisms are given equal credence in this publication. Quarry excavation was a key factor in the slope instability for both failure mechanisms. The objective of the three-dimensional model was to evaluate the effects of extraction and backfill at the toe of the slope with respect to slope stability. GEOLOGY Regional and local geology are both important factors in slope instability at the Pikeview Quarry. Geologic structure at the quarry is related to regional mountain building and basin development associated with the Laramide Orogeny and the Rocky Mountains. Lithologies at the Pikeview Quarry are also related to regional trends. Localized geologic features, primarily related to weathering and erosion, have also been major contributing factors to slope instability at the Pikeview Quarry."

Jan 1, 2017

By Jerry Luttman, Mark Dubay, Anvesha Dogra, Elizabeth Dwyre, Wei Hu

The I-75 Modernization Project (Segment 3) just north of Detroit, MI is being delivered as a Design-Build-Finance-Maintain (DBFM), which is a Public Private Partnership (P3). The project includes design and reconstruction of 5.5 miles of freeway, including a depressed section with a 20,630-ft long, 14.5-ft inside diameter, up to 100-ft deep stormwater tunnel, multiple drop shafts, and a pump station. The project also includes a maintenance term of 25-years. This is the first time MDOT has used a P3 delivery method for a major highway and tunnel project. This paper describes the development of the P3 documents, including performance-based tunnel and shaft technical requirements, and the approach to project risk management, financing, and insurance coverage.

Jun 23, 2024

By II Browne

After a decade of high copper prices, major mining companies are renewing their interest in purchasing operating properties and/or development of ore bodies. An existing operation carries with it a history that can present unique opportunities, while a greenfield operation allows for the establishment of a defined culture. Capital investments are distinctly different. A comparison of BHP Copper Robinson Operation, a greenfield property, and BHP Copper Tintaya Operation, a government owned Peruvian property, will provide insights into mining, concentrating and cultural differences between North and South American Operations.

Jan 1, 1997

By J. M. Mutmansky

This paper outlines patterns of methane emission in both longwall and room-and-pillar operations and the effects that these patterns have on the decision as to whether the methane is most economically handled by ventilation alone or by means of a methane drainage system in addition to ventilation. The costs of handling the methane in the ventilation system and the costs of implementing the methane drainage system will be discussed as well as the costs related to the production of coal. The important issue of production slowdowns and gas outs will also be discussed as well as the proper response of mine management to such a situation. Suggestions concerning the keeping of production records related to methane problems will be made as well as justification for more intensive economic analysis of coalbed methane extraction and utilization.

Jan 1, 1998

By J. M. Dean

With the continued downward pressure on coal selling prices, mine management must make its operations as efficient as possible. The problem is the same one throughout the mineral industries, streamlining operations to maintain competitive mining costs (Born, 1991). There has been a great deal of research into better using production manpower. But the story is different for operations support personnel. Traditionally, planning man-power requirements are done annually, with modifications to the operating plan occurring generally quarterly. On the other hand, the demands on manpower are often dynamic, being responsive to changing productivity levels ,mine conditions (including water influx, bad roof, poor floor)and unanticipated project requirements (responses to machine breakdowns or a new section setup requirement because of a drop in coal quality in another area). Such changes may impact the manpower structure significantly. At times they may cause serious labor relations problems concurrently. Realignments and the generation of instability in the workforce because of active job switching (bidding) are a result. Most responses by coal operators are reactive rather than proactive, a situation that could be mollified by more accurate and detailed planning of predictable manpower requirements. A manpower planning tool is needed that takes into consideration such things as changing productivity levels and conditions as manhour requirements for different work areas are planned, rather than blindly allocated through traditional staffing modes.

Jan 1, 1995

By V. K. Karra

An improvement in the present day screen sizing methods calls for knowledge on i) how material in the size range: 0.5 x 1.5 times the through-fall opening of the mesh on a deck, splits between the oversize and undersize streams of the deck, and ii) how near-mesh content of the feed affects the screening performance. In the throughput based sizing method given here, this is accomplished through the introduction of a generalized partition curve and a near-mesh factor. A newly developed efficiency factor is employed in addition to the traditional screen sizing factors.

Jan 1, 1979

The Longwall Strata Control and Maintenance System (LoSCoMS) is designed to monitor shield pressures in real-time from longwall faces and to provide on-line information related to underground strata behavior and longwall mining operation. The information includes shield pressure data with statistical analysis of setting, developing and final pressures, prediction of shield pressures for the following shift or day, etc. and maintenance data on the shields. The LoSCoMS has been installed and tested at Shoal Creek Mine operated by Drummond Company, Inc. The system is providing valuable information to mine operators for better understanding of underground behaviors. As a result, it has become an effective tool for minimizing ground control hazards and reducing out of seam material.

Jan 1, 1997

By C. A. Rowland

The rising costs for and the possibility for limited availability of electrical energy are emphasizing the continual conflict faced in the selection of comminution circuits used in preparing ores for concentration, namely; capital cost vs. operating cost. Frequently, the circuit with the lowest capital cost is not the most efficient in the use of electrical power and wear resistant materials. The simplest circuit in terms of flow, pieces of equipment and capital cost is the single stage autogenous or partial autogenous circuit used to grinding primary crusher discharge or run of mine ore to the desired product size. (Fig. 1) From this circuit, complexity increases to multi-stage crushing circuits preparing feed for multi-stage grinding circuits. Fig. 2 showing a three stage rod mill ball mill arrangement is an example of a complex grinding circuit. Stage concentration further complicates the flow. Multi-stage circuits being the most expensive to install, often give the greatest operating flexibility and offer the best possibilities for the most efficient use of available power and wear resistant materials. Within available grinding circuits, other comparisons such as high speed vs. low speed mills, grate discharge vs. overflow discharge, metal liners vs. rubber liners, high charge vs. low charge, etc. all add to the conflict

Jan 1, 1977

By Ö. Y. Gulsoy, L. Ergün, I. B. Celik

"In this study, the studies to develop a flowsheet for a low grade chromite ore are presented. The existing concentrator had to be suspended due to the decreasing metal prices. The study commenced with mineralogy and liberation profile of the chromite. The valuable mineral is chromite and the major gangue mineral is forsterite together with small amount of brucite and calcite. Heavy liquid tests were performed on different size fractions without any acceptable success. The concentration tests were performed using teetered bed separator (TBS) +shaking table, spiral concentrator+TBS+shaking table for different grind size. Based on the test results, 100% finer than 0.4mm was found to be optimum for grind size. Comparison of alternative circuits showed that the performance of both alternatives would be similar. A flowsheet was designed and operated for as 25 tph trial circuit in the existing plant. The results showed that the performance of the plant predicted was very close to the actual plant data. The paper describes the methodology used, presents the experimental data and actual performance figures.INTRODUCTION Turkey is one of the largest chromite producers in the world. Since 1850, chromite mining found industrial applications and geographically spread along six different regions in Turkey. Although the reserves in these locations are not as rich as the big producers, they are regarded as very valuable due to Cr/Fe ratio in terms of chromite utilization standards (1, 2). In this period, significant portion of high grade (=35% Cr2O3), directly marketable ore deposits have already been produced. According to General Directorate of Mineral Research and Exploration (Turkey) data; 83% of the known chromite deposits of Turkey which makes 242 341 000 tons in total, is consisting from the deposits those have a Cr2O3 grade lower than 10%. Only 5% of the known deposits (13 087 000 tons) has a grade of directly saleable (2, 3). Gravity concentration methods are well-known processes for chromite beneficiation and there are plenty of plants in the world and Turkey using these methods. As different equipment combinations can be used for the same enrichment method, different methods can also be used in combination for plant designs (4). Beneficiation of low grade and problematic chromite ores may lead to use these method and equipment combinations (5, 6). Ore liberation, the grades of Al2O3, SiO2, FeO and Cr2O3 in the obtained concentrate, Cr/Fe ratio, some physical and chemical properties between gangue and minerals (i.e. specific gravity, magnetic property, color, etc.) designate the selection and combination of these methods and equipment (7)."

Jan 1, 2017