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By Ingemar Marklund

INTRODUCTION Today at LKAB, the primary mining method used is sublevel caving, independent of ore-body size, shape, dip, and geographical location. The mining of small ore bodies with relatively flat dip involves a lot of develop¬ment work, a large initial investment, big dilution, and large ore losses. In 1975 serious investigations into other possible methods, especially for those small ore bodies which do not lie in direct contact with other ore bodies, began. Different methods were studied and a number of in¬teresting ideas came from Russian mines. An analysis was made of one of the proposed methods, sublevel benching, in which mining is carried out from raises, and which uses the throw from the blast to place the broken ore. However, there were reservations about working in big open rooms at great depth, and doubts about the possibility of getting acceptable drilling results in an acceptable environment from raised platforms. Testing was therefore delayed for a time. However the investigations continued and in the fall of 1976, it was decided to try vein mining in a small ore body (Indian) (see Figs. 1 and 2). MINING RESULTS The results are now available from the mining of Indian and are as follows: Ore plan area 1200 m2 Level height 50 m Ore volume 60 000 m3 Ore tonnage 270 000 t Iron content 62% Dip 0.69 rad (40°) Ore thickness 14 m Ore compressive strength 26 MPa Ore C-factor (fracture density) 0.21 Hanging wall compressive strength 28 MPa Hanging wall C-factor 0.27 About 40 000 m of the holes were drilled by ring drills with an average productivity of 85 m/shift; loading of a round (2 rows, 750 m of hole) was usually accomplished in one shift. The total ore recovery was about 270 000 t with an average iron content of 59%, and three to four shifts were required per round (4700 t) to load. The principal of "throwing" the rock during blast¬ing worked well, and no ore remains on the footwall. ROCK CONTROL Before mining commenced at Indian, it was dis¬covered that the rock strength in its vicinity was rela¬tively poor. Since the ore is flatly dipping, and mining was to take place with open rooms, the strength of the hanging wall was of great importance. A supplementary program of exploration drilling was done during the fall of 1976 in order to assess fracture spacing and rock strength from the drill cores. Results showed that the strength of the hanging wall was low because of the many fractures. A decision was made to try cable bolting of the hanging wall by extending some of the ordinary blast¬holes. Cables (20 mm diam) were grouted in these larger holes and the rest of the hole was then utilized for ordinary loading (see Fig. 2). About 100 bolts altogether were installed and, to date, only small falls have occurred and the hanging wall is holding. Its exposed area is 2100 m2 DEVELOPMENT WORK On the 350-m level, four crosscuts (two per mining room), one longitudinal drift, and two elongated drifts (one per raise) for the raise climber were developed as shown in Fig. 1. Of the 230 m of drift, 60 m were in ore and the rest in waste. For mining room A alone, a total of 115 m of drift were needed with 30 m in ore. The drift dimensions were about 4.5 X 5.5 m. In the drifting on the 300-m level, two connecting drifts were driven from one existing transport drift forward to the respective raises. The total development was 93 m, all in waste (Fig. 1). The two raises having a length of 80 m each were driven at an angle of 0.68 rad (39°) from the hori¬zontal. They were driven along the footwall contact with a separation of 30 m and had an area of 10 m2. LONG-HOLE DRILLING The drilling of long holes with the ring drilling unit began in the fall of 1977 in raise A. The equipment consisted of an Alimak raise climber, equipped with a lower platform from which the charging was done.

Jan 1, 1982

The ability to track miners and communicate with them while they work in underground coal mines is important during normal daily operation, and critical in emergency conditions. This was evident during recent incidents at underground coal mines worldwide. Communication with miners and the knowledge of their location is of great importance for rescue efforts and the preservation of life. Numerous technologies have been developed, adapted and deployed to meet tracking requirements of the Mine Improvement and New Emergency Response (MINER) Act of 2006. Evaluating the performance of these systems has proven to be dif?cult for mine operators, system manufacturers and regulatory agencies. The MINER Act requires operators to improve accident preparedness by developing an emergency response plan speci?c to each mine. With the recent implementation of the provisions of the MINER Act of 2006, all underground coal mines in the United States are subject to the mandates of legislation concerning communication and tracking system installation. As of June 2011, 203 new or revised tracking and/or communication systems had been approved by the U.S. Mine Safety and Health Administration (MSHA), with nearly 50 other systems or revisions in the approval process (MSHA, 2011). At that time, the available approved systems for underground coal mine use included these types: ? Leaky feeder communication systems. ? Fixed node-based communications and/or tracking systems. ? Wireless node-based communications and/or tracking systems. ? Medium frequency (MF) communication systems. ? Communication system peripherals. Other types of tracking systems have since been developed and some manufacturers are seeking approval for use in this application. Some of the new products include through-the-earth (TTE) systems and various radio frequency (RF) adaptations. New technologies that are currently being developed and deployed in other industrial applications should also be considered, including acoustical, optical, inertial and hybrid technologies. To date, no uniform method has been employed in the industry to effectively compare and evaluate the performance of installed systems. Neither industry operators nor regulatory agencies can accurately assess the capabilities of installed systems in the continuously changing mine environment. There is a need for a uniform evaluation method that provides the ability to assess how different systems and technologies perform in various mining applications, and whether they can satisfy the regulatory requirements.

By F. Aurelian

The Banat district in Romania was an important uranium mining area for the last 45 years until its closure in 1997. Uranium was present as finely dispersed pitchblende into solid bitumen lens and layers. Due to the mining activities, radioactive wastes have been disposed of in different places of the Banat area. These sites contain uranium, radium and radon and exhibit high contamination potential for environmental receptors (soil, air, waters, sediments and vegetation). Therefore the risk for human health through external and internal irradiation is considered high. The main pollution sources in this uranium mining area are mine and surface waters, waste and low grade ore heaps, dumps as well as release of radon. In this paper studies concerning recognition of pollution sources, delimitation of maps, uranium and radium solubilization and migration from dumps as well as environmental contamination of specific areas related to exploitation and exploration are presented. The risk assessment is based on the relationship ?source-pathway-target? in order to assess environmental risks and identify targets for rehabilitation. The sources causing significant contamination problems were identified by examining the pollutant linkage. The remediation plan for the Banat uranium mining complex involves mine flooding, treatment of water and leachates, as well as modification of heap slopes, application of covers and establishment of vegetation.

Jan 1, 2005

By Jacek Kolacz, Knut Lyng Sandvik

Fine grinding in an air swept and a grate discharge ball mill working in closed circuit with a forced vortex air classifier has been investigated in continuous laboratory scale. Minerals with different physical properties were ground down to 40, 20, and 10 micron top size. The shape of the product particle size distribution curve was investigated and specific surface (BET) was measured. During production of material with top size of 40 microns in an air swept mill, the capacity was up to 25% higher when compared to a grate discharge mill. This difference dropped to 180A during production of 10 micron top size material. A corresponding decrease in power consumption was observed. An important finding is that by regulation of the air flow rate through the mill, it is possible to achieve products with different specific surfaces and particle size distribution curve steepness. During production of the 10 pm material, the specific surface could be varied in the range 3 to 4.5 m2/g. Such powders could hardly be produced in a grate discharge mill because fine particles coated the grinding media and the lining. On the other hand the internal classification in the air swept mill kept the size distribution of the mill content relatively free of fines. This prevented a similar slowing-down of the air swept grinding process.

Jan 1, 1995

By J. B. Nanor, J. Lorengo, M. Misra, C. B. Bucknam

The dissolution of mercury during the gold cyanidation process is the cause of many environmental, health and processing problems. The removal of mercury-cyanide complexes from synthetic solutions and process water were investigated using sodium and potassium dimethyl dithiocarhamates and sodium sulfide as precipitating reagents. The results have shown that efficient mercury removal can he achieved by the formation of stable mercury compounds with the addition of potassium dimethyl dithioearhamate. The mercury dimethyl dithioearhamate precipitates are stable under plant operating conditions, and they do not have any deleterious effect on gold adsorption by activated carbon. Furthermore, it is possible to stabilize mercury in the heap during cyanidation by adding dimethyl dithioearhomate.

Jan 1, 1999

By R. Casagrande, L. R. Moore, J. Sessoms, P. Macy

"A South American nickel mine has been producing a nickel concentrate that also contains copper and iron (15 percent nickel, 5 percent copper, 28 percent iron) for the end use of stainless steel production. A critical specification for the quality of the steel is the iron to magnesium oxide ratio (Fe:MgO), with a ratio of below 3.5:1 having a substantial impact on the nickel value. This nickel concentrate producer historically mined the sulfur-rich mineral pyroxenite but had been forced to move to a magnesium oxide/silicate (MgO/SiO4)-rich mineral harzburgite, resulting in nickel recovery being reduced to around 50 percent to maintain the required Fe:MgO ratio. In this study, ore mineralogy, water chemistry and the chemistries associated with the flotation process were evaluated in an effort to increase nickel recovery while maintaining the Fe:MgO ratio according to specification. New chemistry was introduced with the specific goal of complexing with the MgO and retarding its interaction with the bubble flow in the flotation process.IntroductionGlobal nickel production in 2011 totalled to 1,770,000 tons, according to the Raw Materials Group (2013). From 1950 to 2005 there was an aggregate 4.4 percent increase in nickel production, with a market-value high of $1,000/ton nickel reached in 1998 (Mudd, 2010). Approximately 65 percent of nickel production is consumed by the stainless steel industry, with 12 percent of the remainder used in super alloys or nonferrous alloys. Nickel imparts corrosion resistance, temperature resistance and other benefits to its alloys (Table 1) (Oberg, 1996; Cáceres, 2003). The dominant types of nickel-bearing ores are classified as either laterites (limonite: nickel-iron oxide; and garnierite: nickel hydrosilicate) or magmatic sulfide deposits (pentlandite: iron-nickel sulfide) (U.S. Geological Survey, 2013a, 2013b). In 2012, about 40 percent of the nickel ore mined was sulfidic-type ores and about 60 percent was laterite. The processing of laterite ore is expected to continue to increase as the availability of sulfidic ores continues to decline."

Jan 1, 2015

By Bernardo Portillo, Alejandro Perez, Daniel Norrgran, Joseph Wernham

High gradient permanent magnetic separators (termed "Ferrous Wheel") are described as used to recover the iron bearing minerals from mill tailings at the Grupo Acerero del Norte's Hercules iron mines in Coahuila, Mexico. The pilot scale test work as well as the "in-plant" test work provided the basis for a 385 MTPH plant expansion to be commissioned late in 1995. Approximately 6 million metric tons of flotation tailings averaging 50 percent iron, mostly as hematite, are contained in two separate ponds. The tailings are relatively fine at 93 percent -200 mesh and 72 percent -500 mesh. After testing various recovery methods, a high gradient permanent magnetic separator was selected to produce a preconcentrate prior to flotation. The separator uses a flux converging matrix to generate high gradient magnetic fields and capture the hematite. The advantage of the Ferrous Wheel high gradient permanent magnetic separator is the use of permanent magnets as opposed to electro-magnets. Further the vertical rotating ring is much more conducive to matrix cleaning as opposed to the conventional horizontal ring separators. This feature also allows the use of a wide range of matrix materials to achieve the optimum metallurgical response

Jan 1, 1995

By M. J. Zdunczyk

The final 1995 figures on industrial sand and gravel have not yet been compiled by the US Geological Survey (USGS). There is usually about a nine-month lag time in receiving and compiling this information. However, USGS estimates that domestic production of industrial sand and gravel will increase about 4% to 28.2 Mt(31 million st). The average unit price is expected to increase as well. The top five producers during 1995 were Unimin, US Silica, Fairmount Minerals, Oglebay Norton and Morie Co. Glass manufacturing for containers, automobiles and buildings was mixed during 1995. Containers, the largest consumer of silica sand, remained steady, with regional increases. However, silica use in glass containers face increased competition from plastic and recycled glass (cullet). It was reported that the Pepsi Cola announced plans to replace glass containers with plastic during 1996.

Jan 1, 1996

By Kenneth R. Ware

I INTRODUCTION The Washington Metropolitan Area Transit Authorities (WMATA) rapid transit system (METRO), currently under construction, will have a total length of 98 miles. Forty-eight of these miles are underground and require either open cut excavations or tunnels. Despite stringent construction controls, it is inevitable that some ground settlement will occur adjacent to the deep open cut earth excavations and large diameter earth tunnels. It is therefore essential to underpin nearby important structures to prevent excessive differential settlements and Fig. 1 presents the METRO criteria for this underpinning. This paper describes the underpinning methods currently used on METRO and evaluates the effectiveness of each method. II DESCRIPTION OF SUBSURFACE STRATA The foundation materials in the Washington, D.C. area are extremely variable. Fig. 2 presents an idealized profile showing typical subsurface strata. The engineering properties of each stratum have been determined by extensive exploration and testing programs. Fill: Washington, D.C. fills consist of every variety of soil and rubble. They are not important to this study because no underpinning is founded on fill material. Terrace Deposits: Formed in outwash plains during the glacier period, these deposits are composed of random layers of either sand 1 The writings and opinions expressed herein are solely those of the author and do not necessarily reflect those of WMATA.

Jan 1, 1974

By Terry M. Tilley, Gregory P. Sherry

Purpose This is a unique project because the mining and tunneling industries have become highly mechanized and cannot normally accommodate a project where surface disturbance must be minimized or eliminated when there is less than 10 feet of ground cover. More traditional less mechanized methods must be employed and the skills and techniques for accomplishing the work have become all but non-existent. Therefore, this article highlights those areas of specialized skills and techniques. Methods The article will describe the design approach, the method(s) of ground support selected, the method(s) of excavation selected, the planning, scheduling and materials selection process. In addition, the article will describe the actual production characteristics and the results of the project. This approach will concentrate on productivities, adaptations to actual conditions and the quality of the end product. The design approach basically was to insure that the temporary support methods were adequate for the excavation and shoring stage of the project. The final concrete liner was designed using conventional structural design methods with the goal of constructing a tunnel that will last 100 years. The methods of support were spiling and variations of spiling in order to provide advance temporary ground support. In this project spiling is steel channel cantilevered and driven into the ground ahead of the working tunnel face which supports the ground allowing the face muck to be removed with overhead protection’. Conclusion This will be a discussion of the applicability of the methods. The actual performance of the excavation and shoring methods will also be evaluated. The final concrete liner completion results, the actual production rates and the conformance with budget and schedule will be addressed.

Jan 1, 2005

By Andrew H. Merritt

INTRODUCTION The prediction of the engineering behavior of a rock mass depends upon the systematic analyses of the results of an exploration program, and upon the recognition of the significant rock properties in the early stages of excavation. The variations in rock properties in different geologic terrains and the state of the geotechnical art preclude complete success in the former case, and we therefore must rely heavily on the experience gained in the latter phase. The geotechnical information obtained from these two phases is only of value to the design engineer when applied to the rock behavior during excavation and subsequent plant operation. Pertinent questions which must be answered include: how does the joint orientation and frequency effect tunnel support and overall cavern stability; how does the depth of surficial soil or weathering effect foundations or slope stability for portal cuts; are there permeable zones within the rock mass that could lead to leakage problems around penstocks and is the material in these zones soluble or likely to pipe in the long term; and does the proposed engineering structure fit the terrain, or will it inevitably lead to problems requiring extensive remedial treatment. During the early stages of construction there are two types of geotechnical information required; actual rock behavior with respect to the original design assumptions,

Jan 1, 1997

By Timothy C. Smith, S. Andrew Jacobs, Douglas E. Gonzales, Sandy J. Schexnailder, Carl Urban

At the Schwartzwalder Mine (Cotter Corporation, Golden, Colorado) ion exchange resins have been used in mine water treatment experiments. The experiments, initiated in October 1979 and currently in progress, demonstrate that mine water uranium values can be reduced to levels as low as 10 ppb. Duolite® A-101D, a strongly basic anion exchange resin, was tested in laboratory-scale columns (1 inch diameter) initially and then in pilot-scale columns (4 inch diameter), using both co-current and counter-current operational modes. Observations and conclusions resulting from these studies can be summarized as follows: (1) Duolite® A-101D appears to have successfully extracted uranium at influent levels of approximately 2.0 ppm over multiple loading and elution cycles, consistently producing effluent concentrations as low as 10 ppb uranium. (2) Based upon present test data, counter-current regeneration appears to be the key to successful operation. Upflow loading and downflow elution are the preferred modes for service and regeneration, respectively. (3) Filtration is a necessary pretreatment to remove fine clay and inorganic precipitates that will foul the resin, causing excessive pressure drop and poor loading and elution kinetics. (4) This waste treatment application is unique in that it offers the opportunity to recover some or all of the capital investment in the treatment facility

Jan 1, 1980

By J. K. Mohanty, D. Panda, P. K. Sahoo, R. K. Paramguru, K. C. Nathsarma

Ferromanganese slag, a product of the manganese industry, was characterized mineralogically. The slag, which contains high Mn values, was characterized using optical microscopy, XRD analysis and electron microscopy. No separate Mn-bearing oxide mineral phase was found. The slag is amorphous, and no crystalline phase was identified in the hulk sample by XRD, However, in. fine fractions, quartz was identified. Scanning electron microscopy (SEM) revealed the presence of Mn, Si, Al and Ca in the matrix without the development of a mineral phase. Leaching experiments using H2SO4 were carried out to determine if Mn could be extracted from the slag. At room temperature, almost 100% of the manganese could be dissolved at a solid-liquid ratio o f 1:10 by leaching with dilute sulfuric acid. The impurities could be precipitated by pH adjustment to produce a manganese sulfate solution suitable for the production of MnO2 or electrolytic Mn metal. Based on the laboratory-scale experiments, a suitable process is proposed to recover manganese values from the, ferromanganese slag.

Jan 1, 1999

By Vinton A. Garbesi

INTRODUCTION The placing of the monolithic concrete lining of the Bi-County water tunnel illustrates the state of the art in the materials, equipment, methods and productivity available to the industry for this type of construction. This paper describes the management and engineering rationale used by Clevecon, Inc., a subsidiary of S & M Constructors, Inc., Solon, Ohio, in developing the concrete mix designs, the design of the specialized equipment, and the methods used in the manufacture, transport, and placing of the lining. Also discussed are the changes to the reinforcing steel design instigated to facilitate its handling and placing, as well as to enhance the quality of the lining. The intent is to bring to the attention of designers the effects certain design aspects have on the construction of reinforced concrete tunnel linings, as well as indicate the areas where research and development effort should be expended to further reduce costs for this type of construction. GENERAL DESCRIPTION The Bi-County Water Tunnel West is a water transmission main owned by the Washington Suburban Sanitary Commission of Hyattsville, Maryland. The facility was designed by A. A. Mathews Division (formerly STRAAM Engineers, Inc.) CRS Group Engineers Inc., Rockville, Maryland. It is to be utilized as the central feeder of potable water for the northern suburbs of Washington, DC, extending some 4,597 meters from a riser shaft at its western terminus to the eastern interface, with a similar tunnel which extends eastward about 5,180 meters; the majority of its length being under Interstate Highway 1-495. The excavated and finished diameters are 3.8 and 3.05 meters respectively. The reinforced concrete

Jan 1, 1981

By G. H. Sedahmed, S. A. Nosier, M. H. Abdel-Aziz, A. A. Mubarak, M. A. El-Naggar, E. G. Abdel-Aziz

The performance of a rotating fixed bed reactor in recovering copper from industrial waste solutions by cementation is studied under various conditions. The rotating fixed bed is made of stacked woven steel screens to take advantage of two features of screens: the ability to present large area per unit volume and their ability to promote high turbulence. Variables studied are initial CuSO4 concentration, bed rotation speed, mesh number of the screens and bed thickness. The presence of baffles was found to increase the rate of cementation. The data were correlated by a dimensionless mass transfer correlation suitable for the design and operation of large scale cementation reactors.

By S. S. Cook, S. E. Paulson

The US Bureau of Mines is conducting core leaching experiments with sulfuric acid on oxide copper ores from the Cyprus Casa Grande and Asarco/Freeport Santa Cruz deposit in Arizona to further the understanding of the leaching process in supergene copper ores as it relates to in situ mining. Leach solutions from atacamite mineralization contained 5 to 30 g/L (0.05 to 0.28 oz/gal) copper and few extraneous ions. Leachant from chrysocolla ores, with grades similar to the atacamite, contained 2 to 9 g/L (0.02 to 0.08 oz/ gal) copper and abundant extraneous ions. Quartz and K-feldspar had no impact on leach solution composition at any acid concentration up to 40 g/L - (0.39 oz/gal) while illite and sericite had minimal impact. Biotite, calcium-rich clay, and limonite have a significant impact on solution chemistry when there is abundant free acid in solution. High acid concentra¬tions increase acid consumption in ores with abundant biotite and limonite gangue. High acid concentrations can be used in ores with quartz, K feldspar, and sericite gangues without increasing acid consumption per unit of copper removed.

Jan 1, 1990

By T. R. Ellis

Australia’s mineral valuation code continues to evolve, while mineral valuation standards are also being written for Canada and Southern Africa. The author is leading a task force for writing the extractive industries addition to the International Valuation Standards. Meanwhile, the International Accounting Standards Board is continuing the development of an extractive industries addition to its International Financial Reporting Standards, with an emphasis on valuation reporting. This paper analyzes the need, content and ownership for a U.S. minerals appraisal standard in the context of both these developing international standards and also existing U.S. regulations and appraisal standards. The author provides many questions for research and debate.

Jan 1, 2003

By Elif Emil-Kaya

Samarium (Sm), as one of the rare earth elements (REEs), has gained significant attention in the production of samarium- cobalt (SmCo) magnets due to their high corrosion and oxidation resistance, as well as their high-temperature stability. SmCo magnets find applications in various industries, including but not limited to national defense, aerospace, military and medical equipment. Sm and Co have been classified as critical metals due to their economic importance and supply risk. Recovering Sm from SmCo magnets is an effective method to ensure a stable supply. The present study investigates an integrated hydrometallurgical treatment and combustion process for the preparation of rare earth oxide (Sm2O3 ) powders from SmCo. Initially, SmCo powders are exposed to nitric acid, and the resulting slurry is selectively oxidized at 250 °C to obtain Sm(NO3)3 , Co2O3 and Fe2O3 . Subsequently, the selectively oxidized powders are leached with water to extract Sm. Sm2O3 powders are produced from the obtained leaching solution using an energy- and time-efficient solution combustion process. Finally, the optimal conditions for the production of Sm2O3 are identified, and the produced powder is characterized through X-ray diffraction (XRD) and field emission scanning electron microscopy (FESEM) analysis.

Nov 1, 2024

In 1990, US mine production of barite increased 54.1 %. Barite consumption, sold or used by grinding plants, increased by 27.6%. Imports were about the same as 1989. World mine production in¬creased 12.3%, according to the US Bureau of Mines. The value of domestically produced barite, fob mine, decreased 12.7%, according to the Bureau. The declared value, cif US port, of all imported crude barite during the year 1990 increased from $40.27/t ($36.54 per st) in 1989 to $40.61/t ($36.84 per st). Nevada continued to be the leading producer of barite with 82% of the total, followed by Georgia and Missouri. It is estimated that 750/c, of the domestically mined barite was used as a weighting agent in drilling fluids. The remaining 25% was used in barium chemicals, glass or as a filler. Most of the production from Missouri, Georgia and Tennessee was used in the non-oilfield sector. Of the total barite used by grinding plants and chemical manufacturers, it is estimated that 90% was used in drilling fluids and 10% in the non-oilfield sector. This includes barium chemicals and fillers in paper, plastics, and glass. Tonnage consumed in the drilling fluids market increased due to the higher average rig count during 1990. The average number of rotary rigs operating, (1010), was 16.2% more than the 1989 average of 869 in the US.

Jan 1, 1991

By Bruce W. Cavender, Brian L. Granger

The leaching characteristics of non-homogeneous ores have traditionally been difficult to assess in laboratory tests. A result of the large sample size necessary to ensure representativity, this difficulty is most acute for ores containing nuggets or other irregular occurrences of precious minerals. Consequently, small-scale leaching tests are often regarded as indicative rather than conclusive. The predictive nature of leaching tests can be improved by applying the experimental design concepts of blocking and randomization. In the case of column leaching, experimental 'blocks" are constructed with the same number of columns as there are separate test conditions. These blocks are treated identically throughout the test, with differences between columns within each block being the variables of interest. To maximize the uniformity of the blocks, randomization procedures are employed in the preparation of the sample and conduct of the test. The initial ore sample is screened and individual column charges composited from randomly selected increments from each size fraction. The leaching order, daily solution analyses, and processing of leach residues are similarly randomized. The observed differences in leaching performance between the columns in each block are compared to determine the over-all outcome of the test. A statistical analysis using t distributions gives a quantitative measure of the reproducibility of the outcome.

Jan 1, 1995