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By Dong-Hyun Kim Kim, Tai-Ro Lee, Young-Hwa Seo

Overbreak occurred inevitably in a tunnel excavation, is the main factor for increasing cost and period in tunnel projects. Furthermore the damage to the remaining rock mass related to the overbreak can give rise to a serious safety problem in tunnels. As a rule of thumb, causes for the overbreak are inaccuracy in drilling, the wrong design of blasting and selection of explosives, and heterogeneity in rock mass. Specially, the geological features of the rock mass around the periphery of an excavation are very important factors, so a lot of research has been conducted to describe this phenomena. But the geological rockmass classification for the overbreak and the method for decreasing the overbreak have not been fully established. Besides, the technical improvement of the charge method is needed as explosives for the smooth blasting have not functioned efficiently. In this study, the working face around periphery of an excavation has been continuously sectionalized to 5~ 6 parts, and the new Blastability Index for the overbreak based on 6 factors of RMD(Rock Mass Description), UCS(Uniaxial Compressive Strength) JPS(Joint Plane Spacing), JPO(Joint Plane Orientation), JPA(Joint Plane Aperture) and FM(Filling Material) is proposed to classify sections of the working face. On the basis of this classification, the distance between contour holes and the charging density are determined to minimize the overbreak. For controlling the charging density and improving the function of explosives, the New Deck Charge(N.D.C) method utilizing the deck charge effect and detonation transmission in hole has been developed.

Jan 1, 2003

By Ferron A. Olson

Natural bornite (Cu5FeS4) leached in ferric chloride or in sulfuric or hydrochloric acid solutions with oxygen showed several differences. In ferric chloride 80 of the copper was leached in two stages. The first (30 copper removal) requiring one minute was controlled by mixed kinetics (liquid ferric ion diffusion and chemical surface reaction). The second was controlled by formation of a surface sulfur layer and then diffusion through the sulfur. With oxygen in sulfuric acid reaction was slow and only the first stage was studied. Copper removal had an induction period. The bornite structure disappeared at 12% copper removal (also found with ferric chloride) and covellite formed on the surface with a species inside the particles having an x-ray structure similar to CuFeS2 but with composition Cu3FeS4 (also with ferric chloride). Copper removal was controlled by iron dissolution. Surface iron vacancies filled with Cu+ to give CuS while interior copper dissolution produced Cu3FeS4. Preliminary results with oxygen and hydrochloric acid showed 80% copper removal and sulfur as end products (similar to ferric chloride).

Jan 1, 1982

By G Njowa

Mineral resource evaluation and estimation process is not an exact science; however it depends on the knowledge and experience of the competent person and his ability to apply his mind, make reasonable assumptions, interpretations and exercise sound judgment in the mineral resource estimation process. The mineral resource evaluation results in a mineral resource statement are disclosed to investors. The minerals industry is presently undergoing rapid changes in legislation governing the public reporting of mineral assets. It has gone through different phases of development with respect to the reporting of mineral resources and mineral reserves (mineral assets). In the past no reporting was done and currently mineral assets are reported as a supplementary section that briefly describes the mineral asset termed ?the mineral reserve and mineral resource statement?. The current industry trend appears to be going towards recognition and disclosure of the mineral assets on to the balance sheet. This paper explores the salient issues behind the mineral resources and mineral reserve statement of vein and reef deposits published in the public domain. It also highlights the potential misleading consequences of these issues and which filter through to the valuation of these particular mineral assets. The creation of reporting standards in the minerals industry has made significant inroads in standardizing and consolidating the interpretation and understanding of the different classification categories in the industry in an effort to promote common interpretation towards these salient issues.

Jan 1, 2008

An Application of Depressant BK510 in Separation of Molybdenite and Bismuth by Flotation

Sep 13, 2010

By Forrest T. Moyer

Frequency rates of injuries per million man-hours of exposure were improved during 1965 slightly to moderately over those of 1964 at metal mines, nonferrous reduction and refining plants, nonmetal mills, stone quarries and mills, sand and gravel operations, and slag operations. However, at metal mills and nonmetal mines the rates of occurrence of work injuries were less favorable. The severity rates of injuries during 1965 were better than in 1964 at metal mines and mills, stone quarries and mills, and slag operations. Conversely, severity rates were worse at nonferrous reduction and refining plants, nonmetal mines and mills, and sand and gravel operations.

Jan 1, 1966

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability o mine safety management personnel to apply analytical techniques to Injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objectives and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the application of the quantitative procedures to mine-specific accident/injury experience data is discussed in detail in the form of case studies. The accident data from three mines are analyzed, and recommendations for training are proposed for each of the mines on the basis of this analysis. The procedures to apply cost-benefit analyses are described along with the cost benefit ratios for the training program/policies for the mines.

Jan 1, 1993

By Terry R. Neumann

In 1989, the Bureau of Mines conducted a mineral resource investigation of the 52,350-acre Jersey Jack study area, located in the Clearwater Mountains of north-central Idaho. Twenty-eight mines and prospects were examined, and 483 rock, placer, and petrographic samples were collected during the field study. Two properties contain gold resources; mining company data show the Robinson Dike mine contains an estimated 940,000 tons of "drill proven and probable reserves" averaging 0.041 oz/ton gold, and the Bureau of Mines investigation showed the Blacksand placer mine contains an estimated 64,000 cubic yards of identified placer resources averaging $8.13 in gold per cubic yard. Sample analyses from other properties indicate that gold resources are likely to exist; however the low tonnage, narrow, fissure-vein type deposits would require mining by relatively high-cost underground methods and would be subeconomic at a gold price of $400/oz.

Jan 1, 1991

By H. Ewaschuk

"INTRODUCTIONRio Algom's involvement with the Enviro-Clear thickener began in May 1975, when tests on a laboratory waif were carried out by our Research and Development group. Commencing in June, further tests were carried out using a 3 foot diameter pilot unit. By December, a 30 foot full-scale thickener had been installed. In the near future, 3 more Enviro-Clear thickeners will be commissioned. With in the space of a year, almost $2.5 million had been committed to liquid/ solid separation facilities using the Enviro-Clear thickener. This paper briefly traces the extent and development of this commitment.BRIEF HISTORY OF QUIRKEQuirke Mine started operating in September 1956 at a rated capacity of 3,000 TOD. Because of market conditions, Quirke was shut down in December 1960. The facilities were re-opened at an increased capacity of 4,000 TPD in July 1968, by which time the demand for uranium had returned. Also, a second shaft was sunk, and by 1970, all of the ore treated in the concentrator was coming from the new Quirke II mine. The Quirke I stopes were allowed to fill with natural seepage. As well, acidic barren solution from the concentrator was pumped underground.With increasing demand for uranium, the capacity of Quirke will be further expanded to 7,000 TPD by 1978. Studies of how this expansion could best he carried out led to the consideration of a fairly new piece of equipment, the Enviro-Clear thickener, for certain operations in the concentrator. These operations are as follows:"

Jan 1, 1977

By Klaus Hasselwander

Fluctuating SO2 gas streams represent a difficult task for designers of SO2 removal systems (with respect to designing the plant), but in spite of the designers great efforts to solve the problems, the operation of such plants requires much care and attention. A fluctuating gas flow usually results from metallurgical smelting processes. Both gas composition and gas flow rate may vary. The first part of this paper outlines some existing technical solutions and presents the Pros and Cons of the different solutions. These solutions outline are: - Sulphuric acid plants operated with a preheater permanent in operation - Sulphuric acid plants with concentration increase of SO2 gas either using regenerative SO2 removal or cryogenic partial condensation of the SO2 - Sulphuric acid plants with additional burning of sulfur to increase SO2 content - Single-stage sulphuric acid plants followed by a tail gas system (which is) designed for periods of low SO2 input In the second part, this paper describes some existing technical solutions for removal of SO2 at low concentrations (i. e. less than 0.1 - 2 %-by volume), which could be used as tail gas treatment system for acid plants. While selecting an appropriate solution, special attention should be given to operating costs, which usually to a large extend depends on the type of absorption agent and the costs for disposal of the sulfur compound produced.

Jan 1, 2009

Active geothermal fields show many of the characteristics seen in hydrothermal ore deposits but there are important differences as well. There are, for example, many differences in geology and chemistry between individual geothermal fields, even some nearby, and these include variations in host rock types (volcanic, sedimentary, plutonic and metamorphic), structures controlling fluid flow (normal, lateral, and, rarely, reverse faulting occur) and hydrological setting (valleys to elevated terrain).

Jan 1, 1986

By E. R. Maize

This report is the third of a series on convergence of roof and floor in coal mines and subsidence of surface that accompanies it. The first paper5/ dealt with extraction in a mechanized mine (Montour 10) having relatively short rib lines that retreat rapidly. The second dealt with extraction in a mine (Crucible) in which coal was loaded. by hand and in which the rib lines wore long and slow-moving. The present report deals with a mine (Gibson) in which conditions approximated those in the Crucible mine, except that the distance between room centers was considerably less and the pillars were narrower in consequence. Moreover, the average cover was less and the studies were made under the steep hillside of a stream valley compared with a gently rolling surface over the portions of the second mine studied. Gibson mine lies in the east-central hart of Washington County, Pa. , approximately midway between the Montour 10 end Crucible mines on a north-south line. A cooperative agreement covering the work was made with the Hillman Coal & Coke Co. through W. L. Affelder, vice president. This paper describes the methods used in the investigation, gives excerpts from the data obtained, and offers such generalizations as appear to be justified.

Jan 1, 1940

By C. D. Haynes, S. C. Gambrell

The practice of roof bolting in WORLD-WIDE mining activities is very well-known, having been used extensively for over 50 years. The theory of roof bolting, however, is extremely complicated, and only recently have investigators attempted to explain the theory. Various means of stress analysis have been utilized in rock mechanics, most of which reduce rock to an isotropic, homogeneous medium that can be easily analyzed. One of the indirect research methods is the photo-elastic technique, the theory of which is widely known and needs no elaboration. This technique has been used extensively to examine the state of stress around underground openings of various shapes in certain types of strata, and under various loading configurations.'-" In-Situ Mine Roof Trusses The photoelastic technique was employed here to evaluate the state of stress above a mine opening where support is provided by the in-situ mine roof truss. This support configuration, shown in Fig. 1, has gained popularity in recent years, particularly in mines with bad roof conditions." To the authors' knowledge, no scientific determination has been made of the advantages roof trusses may offer over conventional bolting configurations comparable to roof trusses. Ordinary mine roofs usually sag or bulge downward soon after mining. Normally, after some movement the roof begins to stabilize, but the face of this bulging mine rock is usually in tension and will almost always fail unless supported. Because rock fails easily in tension, it is desirable to "preload" the roof, that is, to impress a compressive force on the mine roof to prevent bulging and subsequent tensile failure. Ordinary rock bolting installations, particularly if the bolting is perpendicular to the mine roof plane, do not produce a preloading effect. Although bolting installations squeeze the strata together and produce a beam effect desirable for support, they do not have the advantage of actual uplift. They pull down at the anchorage point with a force equal to the bolt tension which sometimes causes a separation in the plane of the anchorage detrimental to roof strength. In-situ mine roof trusses require the installation of steel tension rods in the roof of the mine much the same as conventional roof bolts, except that the rods are arranged to produce a stress pattern above the upper surface of the opening similar to that of a prestressed beam. The roof rock acts to transmit the compression force. The simplest form of truss consists of two steel rods anchored to the back of holes drilled at an angle of approximately 45 over the mine pillars. These rods are collared near the middle of the room, and the lower ends of the rods are connected by tie rods and turn-buckles. Used in this manner, a small-diameter steel rod can provide essentially the same support as a wide-flange steel beam. By tightening the turnbuckles, an uplift on the roof can be produced. Objective of the Investigation The objective of this investigation was to determine qualitatively the state of stress that exists above a mine roof after the installation of the in-situ mine roof truss vs. that of two angle roof bolts, hereafter referred to as "roof bolts," drilled and placed in the same configuration, that is, 45" above each pillar and connected together in the middle of the room by a bearing member such as a steel beam. Each state of stress was to be identified, insofar as possible, as compression or tension above the mine opening. Model Construction A photoelastic model of a mine opening was coil-structed from -in. thick PLM-4B birefringent plastic and was machined to specification shown in Fig. 2. The dimensions of the opening were chosen to simulate a width-to-depth ratio of 3 to 1. Two % -in. holes were drilled at 45" angles, as shown, to provide for the loading devices. After construction, the model was annealed at 240°F to remove stresses produced during machining.

Jan 1, 1971

By J. H. Potgieter

This paper describes an investigation to separate and selectively recover silver, gold and platinum from jewellery and laboratory wastes, and produce technical grade material suitable for training purposes. Nitric acid was employed to dissolve and separate silver and other impurities from gold and platinum, which were then dissolved in aqua regia and precipitated selectively. The current work quantified the effects of temperature, stirring rate, leaching agent concentration and solid: liquid ratio on the recovery of the various noble metals and in summary yielded the optimum treatment conditions in each case. It was found that increased leaching reagent concentration (in the case of Ag), temperatures and stirring rates enhanced the recovery kinetics and optimum yield of the three noble metals. An increased liquid to solid ratio also enhanced the recovery of the silver. Recovery yields 97.1%, 99.9%and 99.4% for silver, gold and platinum, respectively, were obtained. The recovered silver, gold and platinum had purities of, respectively, 98.3%, 99.1% and 99.0%. A cost saving of approximately R10 000 per kilogram of scrap refined could be achieved by the in-house treatment of the waste, not to mention the time-saving benefit.

Jan 1, 2004

By V. I. Kefeli

Public-private partnership efforts are working to create green landscapes from abandoned industrial sites. Fabricated soils, potentially an essential element of such landscapes, are designed to substitute for topsoil on the areas free from ground cover and plant community. The aluminosilicate matrix and humus form the soil micelle - the primary unit of any soil complex. Humus formation is a process based on carbon-nitrogen interaction. Sources of carbon can be materials rich in easily composted products like cellulose and polyphenols (plant leaves) or aged lignin polymers (saw dust from different woody plants). The pathways of carbon-nitrogen complexes are discussed. Properties of the fabricated soil components were examined by bio-tests and plant models.

Jan 1, 2002

Blasthole deviation is a frequent, well documented and undesirable occurrence in mining operations. It is caused by the drill string mechanics, operating variables and the interaction between the drill bit and the rock mass characteristics. It is composed of three distinct components: collaring or marking error, alignment error and trajectory deviation. This study has focussed on the dependence of trajectory or natural deviation on the geological features of the rock mass being drilled.

Jan 1, 1996

By Jochen Petersen, Thandazile Moyo

"The oxidative leaching of chalcopyrite in ammoniacal solutions has been evaluated using electro-analytical techniques. The anodic dissolution process has been established to be a seven-electron transfer process under nitrogen in ammonia–ammonium sulphate solutions and ammonia–ammonium carbonate solutions. The number of electrons transferred in the carbonate and sulphate salts suggests that the sulphur is oxidised to a thiosulphate intermediate and the copper and iron released as Cu+ and Fe2+. The Cu+ and Fe2+ is subsequently oxidised in solution in non-Faradaic reactions. The deportment of Fe2+ and S2O32- is affected by choice of the ammonium salt used in the leaching process. In the perchlorate salt, only five electrons are transferred, however observations made on the mineral surface after leaching do not support the formation of elemental sulphur. Scanning electron microscopy and energy-dispersive spectroscopy analysis of the mineral surface suggest presence of an iron–sulphur surface layer completely free of copper under the ammonia–ammonium sulphate conditions, an iron-rich surface layer under ammonia–ammonium perchlorate solutions and absence of surface layer build up under ammonia–ammonium carbonate solutions. INTRODUCTION Hydrometallurgical processes for copper extraction provide a viable route to recover the metal from mixed and low-grade ores, as well as overcome the environmental challenges faced by the traditional pyrometallurgical processes. Chalcopyrite is not only the most abundant of the copper sulphides, but also the most stable, making it recalcitrant to hydrometallurgical processes. Hence, hydrometallurgical processing of chalcopyrite continues to be an attractive area of research due to the vaguely understood surface chemistry of the mineral in different aqueous media. Different approaches to hydrometallurgical treatment of chalcopyrite can be carried out. These include thermal treatment prior to leaching, direct leaching and direct electrochemical leaching (Venkatachalam, 1991). Direct leaching of chalcopyrite can be carried out in various solution systems, as reviewed by Roman and Benner (1973) and Venkatachalam (1991). Ammoniacal solutions are attractive and effective lixiviants that form stable amine complexes with some base-metal cations while rejecting iron. Leaching of chalcopyrite in ammoniacal solutions in the presence of an oxidant is possible due to the stabilisation of copper(I) and copper (II) by ammonia at elevated pH levels. In oxygenated ammonia solutions, it has been suggested that chalcopyrite dissolves according to Equation 1 (Beckstead & Miller, 1977a):"

Jan 1, 2015

By William R. Vogel

The Bureau of Mines Information and Analysis organization collects worldwide data on virtually every commercially important nonfuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. This data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 3291, to place the collection of mineral statistics on an annual basis. The most recent authority for the Bureau of Mines Information and Analysis activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress), which strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral- material production or consumption.

Jan 1, 1989

The early development patterns of both Australia and New Zealand were substantially in parallel and both were heavily indebted to gold mining for, providing the stimulus to growth. However, since the mining boom, of 1895 - 1899, the mining sector in New Zealand has progressively declined, while in Australia it has assumed an increasing importance in the economy. The continued dominance of minerals in Australian trade, and the fact that eight out of the top ten companies in Australia are directly involved in mineral exploration and production, has strongly influenced government and public attitude's to the minerals sector. Although the legal framework of mining and exploration Acts and Regulations are similar it is in, the method of administration, particularly in regard to exploration and prospecting licences, that the gulf across, the Tasman is apparent. Despite the relative ease of application and granting of licences in Australia, in the more settled south eastern part of the continent we are finding more and more land is being zoned unavailable for exploration. In the remote areas, the Aboriginals now control nearly ten per cent of the land area of Australia, virtually with drawing that portion from exploration. The concept of 'Australianisation' has softened a hardening attitude against foreign investment in mining on the part of the bureaucracy. This anti-mining attitude is fortunately, not shared by the public, and we can but hope that the will of the Australian people can filter through to our masters in Canberra, and ease the rapid increase in the number of regulatory bodies which does so much to inhibit the normal conduct of business. The delays caused by interminable hearings and committee investigations all cost money. This cost can only rebound back on the end consumer, who after all is a voter.

Jan 1, 1982

By G. B. Bell

"INTRODUCTION On February 1, 1962, after five years of exploration and research, Jones & Laughlin Steel Corporation announced that they would develop the Adams Mine. Plant construction began immediately and in December of 1964 the first shipment of pellets arrived at J & L's blast furnaces in Pittsburgh. J & L continued to operate the property through its wholly owned subsidiary, Jones & Laughlin Mining Company, Ltd., until August of 1971 when it was sold to Dominion Foundries and Steel, Limited of Hamilton. Dofasco engaged Cliffs of Canada, a subsidiary of Cleveland Cliffs Iron Company, to manage the operation of the property.SUMMARY:The Adams Mine is a one million tons per year iron ore pellet operation located in the Boston Township Iron Range, approximately seven miles southeast of Kirkland Lake, Ontario. The property includes 5,300 acres in which eight areas suitable for open pit mining have been outlined. It was estimated that the reserves in these out lined areas are sufficient to produce 30 million tons of high grade iron ore pellets.The ore 'consists of fine grained magnetite with alternating layers of chert and is mined by conventional open pit methods. This extremely hard and abrasive ore averages about 20 percent magnetic iron, and has a ratio of concentration of 3. 9 /1. Presently, mining operations are confined to two pits with a third one being developed for operations to begin in 1973.The run-of-mine ore is crushed and ground and then concentrated by magnetic separation and flotation to a concentrate grade of 68 percent magnetic iron. The concentrate is agglomerated by a grate-kiln pelletizing process and shipped by rail to Dofasco's blast furnaces in Hamilton and to Jones & Laughlin's furnaces in Pittsburgh."

Jan 1, 1973

By Irvin Pritts

This report describes the design, fabrication, and testing of a prototype instrument which demonstrates the feasibility of determining respirable coal dust concentrations by light reflectance photometry. Coal dust is collected on a filter and the quantity collected is continuously monitored by reflectance-photometry. Light emission and detection is accomplished by reflective object sensors, which have both light source and detector in one chip. The use of a pulsed light source insures low drift characteristics of the measuring circuitry. The collection of the respirable coal dust on filters facilitates accurate calibration and also allows measurement verification, if desired, by well-accepted, gravimetric methods.

Jan 1, 1981