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Since it was first introduced, the Coal Mine Roof Rating (CMRR) has been widely accepted as a tool for geologic characterization and mine planning. This paper discusses the application of the CMRR to another practical ground control problem. Extended cuts (cuts greater than 6 m (20 ft) in length) are commonly used with remote control continuous miners. Extended cuts can greatly increase productivity, but they have been associated with a number of fatal roof fall accidents. When extended cuts are attempted in weak roof, the roof may collapse before it can be bolted, causing hazardous conditions. Until now, it has not been possible to predict where conditions may not be suitable for extended cuts. In this study, data on the CMRR and extended cut experience were collected at 36 mines in 7 states. It was found that when the CMRR was greater than 55, deep cuts were routine in nearly every case. When the CMRR was less than 37, extended cuts were almost never taken. Between 38 and 55, extended cuts were feasible sometimes but not others. The data also shows that extended cuts are less likely to be stable if either the entry span or the depth of cover increases.

Jan 1, 1998

By Georgy Cherkashov, Svetlana Babaeva, Tamara Stepanova, Firstova. Anna

Seafloor massive sulfides (SMS) study in the Russian Exploration Area at the northern equatorial Mid Atlantic Ridge began after signing the contract with International Seabed Authority in 2012. In order to evaluate the SMS resources in the course of exploration the major and rare metals with economic value should be determined. The evaluation is based on geochemistry and mineralogy and particularly on the type of rare metals occurrence in the SMS. As a case study research of the Semyenov cluster of SMS deposits have been conducted.

Sep 1, 2014

Heap leaching has become one of the prime technologies used for the recovery of precious metals from low-grade ores over the past ten years. The recovery process involves mining and stacking the ore on engineered leach pads, with or without crushing and/or agglomeration, followed by leaching with a low concentration sodium cyanide solution. The metal-bearing, pregnant solution is then processed by zinc precipitation or activated carbon absorption to extract the precious metals. The leaching process continues until all economic metal values are removed at which time the spent heap leach pads, the leached materials and excess process solutions require decommissioning. The management of these solutions may present a potential challenge for successful and environmentally sound decommissioning due to their composition, volume or continuity of generation from the spent ore even though active leaching has been terminated. The principal objectives of solution management in decommissioning spent heap leach pads are to meet all operative environmental regulations in a cost-effective manner and to leave the pads in a condition where they do not present a long-term liability either to the operator or to the environment. This involves the reduction in volume of the residual process solutions and/or treatment of these solutions to where they meet applicable water quality criteria. In the past, the environmental and economic aspects of decommissioning and solution management have been overlooked or under-estimated during the planning of mining operations. As a result, there is a potential for long-term liabilities and costs to be recognized only at the end of active leaching, a time at which operating revenues and cash-flow are minimal. Therefore, the decommissioning process requires addressing at the mine planning stage and agencies now require that a plan for solution management after the cessation of operations be submitted prior to initiation of mining. This paper discusses aspects of process solution management during decommissioning, both in terms of quantity and quality, and how potential issues may be recognized and planned for in the initial stages of heap leach design.

Jan 1, 1992

By John W. Tieman

Coal is a term applied to vegetable matter (trees, grasses, etc.) which was subjected to heat and pressure through geologic ages. This resulted in a change in both the physical and chemical properties. Because its chemical composition is variable, geologists classify coal as a heterogeneous mineral rather than a homogeneous mineral. Peat represents the initial, unconsolidated stage in the development of coal. This coalification continues with time and the application of temperature and pressure to lignite, subbituminous, bituminous, and anthracite toward the theoretical graphite end member.

Jan 1, 1981

By F. Habashi

It has been estimated that about 45 tonnes of mercury are emitted annually in the USA in the atmosphere as a result of burning coal in power-generating plants. A similar situation had existed in the metallurgical industry particularly in zinc production plants but this problem has been solved long ago by introducing scrubbing systems. Methods of mercury removal and recovery are discussed.

Jan 1, 2010

Worldwide minerals exploration slipped in 1992 from 1991 levels. Although industrial production figures showed the US economy emerging from recession in early 1992, it was not until February 1993 that the lagging indicator of unemployment dropped to 7%. Most other industrialized countries are still in recession. Preliminary data for 1992 showed industrial production dropping in Japan (5%), Germany (1.4%), the United Kingdom (0.5%) and France (1.4%). The slowdown in industrial production led to reduced mineral demand. This resulted in lean cash flows from mining operations, which squeezed exploration funding. Although mineral prices were steady during most of 1992, some mineral commodity prices began falling in late 1992 and early this year. Exploration 1991-1992 According to Metals Economics Group (MEG), planned 1992 exploration expenditures were down by about 5%. Geographically, the leading exploration target was the United States with 21 % of the expenditures, followed by Australia (19%), Canada (18%), Latin America (15%), South Africa (9%) and the western Pacific (7.5%). The remaining 10% was split between Europe and Africa. There were absolute increases in exploration expenditures in the United States and Latin America. Latin America showed the largest increase. The change in the Mexican mining law allowing foreign ownership of mines should result in the inflow of direct foreign investment in Mexico's mining industry.

Jan 1, 1993

By R. N. Chakravorty

Spontaneous combustion presents a very serious hazard to both safety and economics of mining operations. Notwithstanding considerable research that has been done over the years to present and control spontaneous combustion the risk still exists. Consequently, this problem poses a major challenge to mine safety researchers; new and improved techniques are constantly being developed to deal with this major hazard. This paper reviews the current practices to prevent and control spontaneous combustion in coal mine operations highlighting new developments in this area. Research and development work presently being carried out in Canada to' deal with this problem is also discussed which includes monitoring, inertization and application of biotechnology.

Jan 1, 1988

By M. Hakan Morcali, Onuralp Yücel, Haldun Gürcan, Serdar Aktas, Semih Özbey, Alper Keskin

"This work presents a method for the precipitation of cobalt sulfate by alcohols, specifically ethanol and methanol. The effect of the initial concentration of cobalt, the volumetric ratio of alcohol to cobalt sulfate solution, the addition of sulfuric acid and ammonia, and the effects of common ions on the precipitation percentage were investigated. The performances of ethanol and methanol were compared in terms of the precipitation percentage of cobalt sulfate, and explanations for different performances are offered. In the sulfate-based solution, the alcohol was shown to displace water ligands from the first coordination sphere of the cobalt(II) cations, which led to the precipitation of the cobalt ions as cobalt sulfate heptahydrate. SEM analysis revealed that the particle sizes of the powders produced by this method are smaller than those of commercially available cobalt sulfate. The scientific literature contains no data on the solubility of cobalt sulfate in ethanol. In this study, the solubility product constant (Ksp) for cobalt sulfate was experimentally calculated to be approximately 1.15 x 10-5.IntroductionCobalt sulfate, which is one of the most important compounds of cobalt, is used in the electroplating and electrochemical industries. The addition of cobalt sulfate to nickel-plating baths makes the treated metals brighter, harder, smoother and more ductile (Armstrong et al., 1988). It is also used as a desiccant for lithographic inks, varnishes, paints and linoleum, as well as in storage batteries, e.g., nickel-cadmium (Ni-Cd) and lithium-ion (Li-ion) rechargeable batteries (Kang et al., 2010). Cobalt sulfate is employed as a coloring agent in ceramics, enamels and glazes to prevent discoloration and as a copigment for the decoration of porcelain. In addition, cobalt sulfate has been used in animal feeds as a mineral supplement (Budavari et al., 1996; Kirk and Othmer, 1999).In the past, brewers used cobalt sulfate to prolong the life of beer foam (Kesteloot et al., 1968). Ranchers have dosed livestock with cobalt sulfate or used fertilizer enriched with this mineral to ensure that their animals obtained sufficient amounts of the trace mineral, which is essential to the production of vitamin B12. Cobalt sulfate has also been used in veterinary medication to prevent and treat cobalt deficiency in ruminants, which causes a reduction in feed intake and body weight, accompanied by emaciation, anemia and debility.Cobalt sulfate is a water-soluble bivalent cobalt salt. Cobalt sulfate heptahydrate dehydrates entirely at 420° C, and the dehydrated salt forms red monoclinic crystals."

Jan 1, 2015

By J. S. McAlpine, J. Matousek, W. Muir, P. Downey, K. Major

The Golden Bear refractory gold ore roasting operation is located at Huddy Lake, in northwestern British Columbia, about BO km northwest of Telegraph Creek (see Figure 1). The mine access road, used for supplies delivery, was developed by Golden Bear and consists of a radio controlled 155 km gravel road originating at Highway 114. Hine operations are based on a two week in, two week out rotating shift schedule with personnel transport by chartered aircraft from Vancouver, Whitehorse or the 3 Talthan conmunities. The site runway Is located adjacent to the tailings impoundment.

Jan 1, 1992

By J. H. Ahn, J. E. Gebhardt, W. K. Tolley

Color measurements were made for pure minerals, mineral mixtures and flolation froths loaded with different minerals. The research objective eras to correlate color with the composition of mineral streams. An industrially available system consisting of a fiber-optic-based illuminator and detector was used to measure color. The color values of binary mineral mixtures varied according to the type and proportion of minerals in the mixture. The measured color values of mineralized froths in the laboratory and in a commercial flotation circuit were dependent on the amount and type of minerals present.

Jan 1, 1994

By Ernest Y. Baafi

The usual tasks performed by a mine store include .removal, replenishment, ordering and deletion of items and updating of stocks. A personal computer Mine Store Inventory Database System MIDSYS for monitoring stocks in such a store is presented. The system consists of series of relational databases developed in dBASE III+ environment. The system has three main modules comprising of a store management module, a display module and an employee-store operation module. The third module is useful in tracing movement of store goods. The MIDSYS is menu .driven with help functions at all levels.

Jan 1, 1992

By Ernest Selig, John Dunnicliff, Delon Hampton

This paper provides a summary of a two-day conference held in New Orleans in March 1980, entitled "Tunnel Instrumentation: Benefits and Implementation." The conference addressed two major questions: First, what are the benefits of using instrumentation during tunnel construction? Second, what contractual relations should be established for conducting instrumentation programs during tunnel construction? Each session consisted of brief formal presentations and extensive panel discussions with participation from attendees. Attendees included owners, designers, contractors, and instrumentation specialists. This paper presents a consensus of views expressed during the conference.

Jan 1, 1981

By E. Berrezueta

Automatic digital phase imaging should yield unbiased and representative characterization of gold ores. However, this is not a simple task due to low gold grades, fine grain size, possible complex mineralogy, nugget effect, etc. A critical test was done by two methods, using the same sections of a gold-rich ore: with an optical (OM) and with an electron microscope (EM). In general, the two methods are consistent and useful for ore processing. There are some minor differences e.g. the detection of very fine gold grains is enhanced by EM.

Jan 1, 2001

By L. John Minnick

A revised and expanded edition of a previous paper** dealing with reactions of calcium and magnesium oxides and hydroxides with pulverized coal fly ash is presented. Lime-fly ash specimens were cured at constant temperature and subjected to X-ray diffractometry, differential thermal analysis, pozzolanic reactivity tests, and microscopical investigations. Bars of limefly ash were subjected to cycles of wetting and drying, and measurements of length change were recorded. A discussion of variations within and among types of lime and types of fly ash is presented. The nature of the pozzolanic reaction is reviewed, particularly as related to compounds which are used up and formed during the aging process. The relationship between the pozzolanic reaction and the resultant physical properties of the mixtures is examined.

Jan 1, 1968

By M. G. Papasotiriou

For our company, S&B Industrial Minerals S.A., restoration of areas which were mined and the effort for bringing up again a balance of nature is an important priority over the last 3 decades. The successful qualitative results of restoration works have delivered to nature over 1.700.000 m2 of surface after mining activity. Our fundamental method in order to achieve the best results for restoration of mined areas is the use of local plants (bush or tree type). Grass and herbs are installed by using the method of hydroseeding. Small trees and bushes are produced and they grow up at our fully owned Milos nursery and they are installed during winter when weather conditions are suitable. During the initial stages of restoration activities a great amount of surfaces, adequately shaped, are delivered by the mining department covered with top soil. These surfaces are suitable not only for the local nature community but also for a combination between natural and agricultural environment. The above fact was a great chance to create small horizontal agricultural cultivations as pilots inside the restored areas. At the beginning the agricultural items that could potentially be installed in these pilot areas were studied and examined analytically. The following agricultural items were finally qualified to be furthermore researched: 1) Vineyard (Vitis vinifera ) 2) Prickly pear (Opuntia ficus indica) 3) Jojoba (Simmonsia chinensis) 4) Olive tree (Olea europea)

Jan 1, 2007

By Fernando Muge

A complex pyrite orebody located in the South of Portugal (MO INHO) was exploited in the past by cut and fill methods until a certain level. It was decided to design a new plant for non ferrous metal extraction and the rate of production and exploitation method was modified accordingly. So, a sub level stoping (SLS) method was en visaged for the exploitation of the deepest part of the orebody (under 265 m level). For the planning of this SLS method, it was decided to perform a geostatistical study of the orebody, on the basis of the available information, which consists mainly of channel samples assayed for Cu, S, Zn and Pb.

Jan 1, 1979

By C. E. Capes

The continuous balling? operation whereby a moist particulate mass is tumbled in a horizontal revolving drum with recirculation of the undersize product can be extremely unstable. Product and recycle rates are subject to wide fluctuations. Although the problem seems to be well-recognized, there is little published information or quantitative data readily available, especially in relation to industrial-scale circuits. Probably the best available published results are in the Russian literature, an illustration of which is given in Figure 1. These data, taken from a study') of some of the factors which influence the stabilization of the pelletizing process, illustrate the wide variations in circulating load and circuit productivity which may be encountered over a period of operation. The problems of balling circuit stability may be traced to random seed or nuclei generation and uncontrolled agglomerate growth. The situation is analogous to that in crystallization processes where (4 considerable attention is given to nucleation control. Traditionally attempts have been made to optimize system and operating variables to stabilize the balling process. A supplemental approach which is taken here is to build on the considerable

Jan 1, 1975

By P. M. May, J. S. Solis, G. T. Hefter

Chemical speciation plays a critical role in many areas of gold processing. These include the formation of HCN in plant liquors, interference by copper in the extraction efficiency of gold, the recovery of adsorbed gold, and the behaviour of plant effluents in the environment. Thermodynamic modelling provides a cost-efficient method of rationalizing and even predicting of chemical behaviour. Unfortunately, because thermodynamic data for cyanide complexes are of poor quality and few are known under hydrometallurgical conditions. Such models are currently of limited use. This paper describes recent work on the thermodynamics of cyanide complexes of a range of metal ions. Data will be presented on the stabilities and enthal­pies (heats) and entropies of formation of a variety of metal ion species determined by potentiometry and calorimetry. Particular emphasis will be placed on the Cu(I)/CN- system.

Jan 1, 1995

By Hayati Karaman, Tevfik Güyagüler

In this paper fires due to spontaneous combustion in Middle Anatolian Lignite mine (OAL) which is the first fully mechanized underground lignite mine in Turkey, are studied. Since the installation of mechanization (1986), due to spontaneous heating, four panel fires namely, A01, A02, A03 and A04 have broken out. During these fires, the concentrations of carbon monoxide, methane and the velocity of air are measured continuously by the Micro Minos Environmental monitoring system. For each fire, the environment where fire has started is examined and the possible causes of the fire are investigated. Also the precautions taken to extinguish the fire at different stages are described and the importance of the early detection of mine fire are discussed together with the limitations of the monitoring system and the practical difficulties observed during the fire.

Jan 1, 1995

By Kewal K. Kohli, Richard E. Thill, Syd S. Peng

The results of unpublished investigations into surface subsidence from coal mining in the Northern Appalachian Coalfield are summarized. These investigations were carried out by various coal companies and the State of Pennsylvania in the sixties and seventies. Subsidence data were collected and analyzed from 10 room-and-pillar panels in 5 mines in the Pittsburgh coal seam. Results show that angle of draw ranges from 26° to 33° and subsidence factor from 0.42 to 0.72; surface heating generally occurs beyond the edges of the panel, the amount and extent of which vary; waviness occurs in the subsidence profile if a substantial number of pillar stumps are left in irregular patterns; interpanel effect is significant; time-dependent subsidence exists, but varies for different panels; and surface slope does not seem to affect the amount of subsidence.

Jan 1, 1982