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By G. Deissman, S. Kistinger

For the last 15 years environmental Life-Cycle Assessments (LCA) have increasingly been used to evaluate the environmental performance of industrial processes and products and have been employed as a basis in decision making processes in the public and industrial sector. However, assessment methodologies for environmental protection measures and reclamation/remediation measures with respect to their consumption of natural resources are generally poorly developed. In this presentation a methodology for LCA of environmental protection measures and remedial actions, respectively is suggested, using the remediation/reclamation of mining sites as an example. Key aspect of this approach is the development of an evaluation method appropriate for environmental protection measures, which links the various impact indicators recognised in the impact assessments and allows their integrated assessment.

Jan 1, 2005

By Sebastián H. Troncoso

Open pit mine planning is normally based on the selection of an economic envelope that has been generated by the Lerchs & Grossman algorithm, which requires individual economic valuation of each block of a geological block model. The selected envelope, usually called Final Pit, is later discretized in pushbacks and benches, which correspond finally to the fractions that the production schedule will allocate in time. This planning methodology has been widely used by the mining industry in countless projects to exploit open-pit mines, however, in many of the deposits can be found some undesirable elements such as arsenic, phosphates, ash among others that tend to reduce the value of elements of economic interest, either by disrupting the processes of concentration or as deemed impurities that affect the quality of the final product. Thus, a fair amount of blending would be required to capture the real value of the ore body. The traditional approach under estimates a block value by penalizing the block value by the amount of contaminant even when at the mine a set of blocks is amine at a time. This paper proposes a methodology for computing cut off grades over time that would maximize net present value allowing blending that should fulfill a set of metallurgical constraints. Preliminary results show significant increases in value and reserves quantity, questioning the use of fixed cut-off grades in generating a production schedule when blending applies to fulfill a set of geometallurgical constraints. Finally, the model allows the authors to show the importance of having adequate planning tools that will lead to the ability to look at the potential economic value of a mineral deposit.

Oct 1, 2009

By F. Samimi Namin

During the process of developing surface or underground mines, some sites are considered for dumping of surface soils, while others are applied to reclaiming surface and waste disposal. For each kind of overburden, whether it be waste rock, low-grade material, or process tails, a separate storage site is considered so that it becomes possible to transport or recover the overburden separately. Decision-making must be completed by means of a selection process which takes into account the best methods of alternative sets in order to achieve these goals. This decision- making involves many parameters that are inter-related in that changes in some parameters affect the others. There are many methods of decision-making, however, Fuzzy Multi-attribute Decision-making (FMADM) and its functions are studied in this paper. The advantages of this method lies in its theoretical background, formulation, revising capability, unlimited alternatives, and consideration of the counteraction of the different parameters upon one another.

Jan 1, 2007

By Viviane Tavares

The technology advance of mobile devices makes consumers of these equipment do more constant exchanges, with this the obsolete devices discarding becomes an environmental problem, due its landfill accumulation. In order to minimize the environmental impacts caused by these equipment there?s the recycling necessity of polymers, ceramic and metallic materials. The main goal of this recycling is to study the printed circuit board of device mobile processing through ore treatment in order to recoup copper. Initially printed circuit boards were processed in a knives mill, in order to liberate the ferrous material, after that it was done the magnetic separation of the reduced residue. With the not magnetic fraction it was done the grain sized analysis and sulfuric acid and hydrogen peroxide leaching analysis. With the chemical analysis results proceeding from the leaching aliquot it was possible to observe that the leaching method with sulfuric acid and hydrogen peroxide presented greater copper recovery.

Jan 1, 2009

By Mario E. Rossi

The full economic evaluation of a mining project requires a block model that provides an estimate of the tons and grades of available resources. The model must be representative of the mineralization to be found at the time of mining for specified extraction periods and within acceptable error margins. In an operating mine, there may be a reasonable understanding and estimates of actual dilution and ore loss. This paper discusses the issue from the perspective of a project at a feasibility or preproduction level of development. Three types of dilution are discussed. Internal dilution (or change of support) is function of the spatial distribution of the mineralization and its relation to the operation?s selectivity. Geologic contact dilution is the unavoidable mixture at contacts or boundaries of material with different geologic characteristics, grades, or metallurgical performance. Operational planned and unplanned dilution should also be considered, sometimes incorporated by factoring the resource model, but more accurately by mimicking the grade control process. The resource estimation process always carries uncertainty, which is sometimes significant, and usually caused by several factors. These include quantity and quality of drill hole information; quantity and quality of geologic data; grade estimation methodology; dilution and mining recovery factors applied; etc. A key decision is to whether estimate as accurately as possible the in-situ geologic resource or to estimate the tons and grade of the material to be fed to the processing plant. The geologic modeling and grade estimation methods used are conditioned by this decision.

May 1, 2009

By P. V. Avotins, I. Djurkovic, D. R. Nagaraj, M. Grunjic, A. Day

"As part of a major reconstruction and expansion of the Majdanpek Copper Mine, an investigation and optimization of the flotation collector regime was undertaken. The flotation response of the major minerals to various reagents and the effect of pulp chemistry was studied from both a fundamental and practical point of view. These studies led to plant trials and the eventual adoption of a modified collector suite which improved both copper and gold recoveries.INTRODUCTIONThe Majdanpek Copper Mine processes 40,000 tons per day of ore containing about 0.43% cu. In addition to copper, the ore also contains recoverable quantities of molybdenite and gold. The mine has been in operation since 1961 and is the largest in Yugoslavia. It is currently undergoing major reconstruction and expansion. The flowsheet of the Majdanpek concentrator is shown on Figure 1.The ore body is variable in composition and changes in mill feed require proper control of operating variables to achieve the optimum metallurgical results. A detailed study including grindability, flotation response, and solid-liquid separation was carried out on several samples of the ore. Flotation response and the choice of reagent chemistry were found to be very important in achieving the highest recoveries of metal values. An automatic reagent control scheme insured that optimum dosages were used in the plant.The flotation collectors used at the present time include sodium isopropyl xanthate (SIPX), AERO 3302 Promoter and AERO 5415 Promoter. The addition of AERO 5415 to the reagent suite is a recent development and was based on the favorable results obtained in the extensive laboratory testing program conducted to establish the optimum reagent combination and dosages. Subsequent plant tests confirmed that AERO 5415 provided significant improvements in copper and gold recoveries. A description of the mineralogy of the Majdanpek ore and details of laboratory and plant metallurgical data are given in this paper. The chemistry of AERO 5415 Promoter and its interaction with minerals relevant to Majdanpek ore are also discussed."

Jan 1, 1992

By James L. Poole

The gold and silver markets from the late 1960's to the present are reviewed and the outlook for these metals in the 1980's is presented. Included in this discussion is a summary of the basic supply and demand balance for gold and silver since the mid-1960's. an explanation of the price formation for the metals, some of the relationships between the prices of these metals and selected economic parameters, and how these factors affect the outlook.

Jan 1, 1981

By K. V. Konigsmann

"Mattagami Lake Mines Ltd operate a zinc-copper mine with an annual output of about 200,000 tons of zinc and 30,000 tons of copper concentrates. Zinc concentrates arc shipped to a company owned smelter in Valleyfield (a distance of 690 miles), for Export to Quebec City and also to Josephtown, Pennsylvania (1,060 miles, Figure 1.)The protection of concentrates in open gondola rail shipments has been a matter of concern since operations commenced. Considerable financial losses did occur at times because of wind erosion. Operating difficulties were also encountered by customers because of excessive moisture accummulation in the concentrates. Test shipments made in 1969 established the magnitude of losses in open cars. The results and subsequent investigations at our mines and elsewhere confirmed that load protection is an economic necessity.Many types of covers were experimented with, more or less successfully. In 1972 we agreed on a joint program with Dupont of Canada Limited. A new type of cover was developed by early 1973. It has been in use since, undergoing several improvements as experience accumulates."

Jan 1, 1975

North American Coal is a subsidiary of NACCO Industries. Originally founded as Cleveland and Western Coal in 1913, North American Coal took its present name in1925. Today, North American Coal is one of the 10largest coal producers in America, mining about 32Mt/a (35 million stpy). The company mines primarily lignite for electric utilities. Its current operations are in North Dakota, Texas, Louisiana, and Mississippi. In addition, North American Coal’s Florida operation provides dragline mining services for quarries that produce more than 18Mt/a (20 million stpy) of limerock. With more than 1.8 Gt (2 billion st)of bituminous and lignite coal re-serves in the United States, North American Coal constantly seeks new technologies to keep its operations modern, productive and cost competitive.

Jan 1, 2004

By Gerrit V. R. Goodman

In This Chapter [Design and operation of machine-mounted scrubbers Dust control with scrubbers and blowing ventilation Dust control with scrubbers and exhaust ventilation Dust control with exhaust ventilation and no scrubber Dust control methods common to all continuous miner sections Dust control for roof bolters] This chapter explains how to control dust at continuous miner sections in coal mines where the main dust sources are continuous miners and roof bolters. In relation to dust, there are three categories of continuous miner faces depending on the type of ventilation and whether or not a machine-mounted dust scrubber is used. These are— 1. Mining machines with dust scrubbers used with blowing face ventilation 2. Mining machines with dust scrubbers used with exhaust face ventilation 3. Mining machines without scrubbers used with exhaust face ventilation The approach to dust control is somewhat different in all three of these. However, there are many dust control features (such as the need to provide adequate airflow) common to all continuous miner sections. For workers at roof bolter faces, there are two dust sources: 1. Dust from the continuous miner when it is upwind. 2. A malfunctioning dust collector on the bolter, which allows dust to escape DESIGN AND OPERATION OF MACHINE-MOUNTED SCRUBBERS [Almost all new continuous miners are equipped with scrubbers. When the dust is excessive, it is possible that the scrubber needs some maintenance.]

Jan 6, 2003

By Robert B. Hopler

The history of the first twenty years of the high explosives industry in the United States begins as an illustration of the free enterprise system at its best and ends with the industry virtually taken over by a single company: a company which strongly opposed the new explosive material at the beginning of the period. In the world of the late Twentieth Century we could almost compare this history to the opposition of the mainframe computer manufacturers to the introduction of the personal computer, and their later entry into, and attempted dominance of, that market. With computers in the twentieth century the attempt to dominate the market has not been particularly successful: with dynamite in the nineteenth century it was.

Jan 1, 1994

The excavation of ramps and tunnels often requires high-speed development with (or without) the use of high-energy mining equipment such as loaders, dump trucks, TBMs and roadheaders. This high-speed development creates a challenge in terms of providing a safe and productive working environment. For example, heat from continuously exposed surrounding rock, heat from broken rock, heat generated by mining equipment, potential in flows of hot ground water, pollution from associated diesel equipment and the distance of the advancing face from fresh through-ventilation all have to be taken into account when designing ventilation systems for high-speed ramp and tunnel developments. This paper discusses methods of achieving acceptable environments at the face and along the length of the tunnel. The methodology has been successfully implemented in the development of long (up to 20 km) TBM drives in the Lesotho Highlands Project and in mining projects in hot rock using drill and blast methods as well as mechanized methods using continuous miners and roadheaders. The determination of heat loads includes calculation of the heat flow within the surrounding rock, evaluation of the operating cycle of the equipment and the contribution to the overall heat load of the broken rock as it travels out of the tunnel. The determination of heat loads from surrounding rock in new tunnels required a modification of the algorithms generally used for established excavations. The paper also examines the use of, for example, mobile duct and fan systems to ensure that fresh air is delivered to the specific areas where workers are located.

Jan 1, 2000

By L. L. Chasko

A mine fire is one of the most challenging safety issues facing a mine operator and can occur at any location underground. The National Institute for Occupational Safety and Health (NIOSH) and the Twentymile Coal Mine, Colorado, conducted in-mine experiments to determine the capability of high-expansion foam for addressing underground fires. The tests were conducted in sloping entries with high-capacity diesel-powered foam generators. The following results were observed: a well-designed, maintained, and properly operated high-expansion foam generator can propagate a foam plug hundreds of feet in steep upward sloping (20 pct) multiple entries against a ventilation pressure; stoppings and partitions designed to contain the foam plug in upward sloping entries must be substantially constructed; and the predicted quantity of foam concentrate can be significantly less than the actual amount used due to foam losses, such as bubble breakage on dry surfaces. This paper describes the production of high-expansion firefighting foam and discusses the in-mine experimental tests and results. DISCLAIMER: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2009

By T. W. Beck

Drilling into coal mine roof strata to install roof bolts has the potential to release substantial quantities of respirable dust. Due to the proximity of drill holes to the breathing zone of roof bolting personnel, dusts escaping the holes and avoiding capture by the dust collection system pose a potential respiratory health risk. Controls are available to complement the typical dry vacuum collection system and minimize harmful exposures during the initial phase of drilling. This paper examines the use of a bit sleeve in combination with a dust hog-type bit to improve dust extraction during the critical initial phase of drilling. A twisted-body drill bit is also evaluated to determine the quantity of dust liberated by comparison to the dust hog-type bit. Based on these laboratory tests, the bit sleeve may reduce dust emissions by one-half during the initial phase of drilling before the drill bit is fully enclosed by the drill hole. Because collaring is responsible for the largest dust liberations, overall dust emissions can also be substantially reduced. The use of a twisted-body bit has minimal improvement on dust capture compared to the commonly used dust hog-type bit.

Feb 27, 2013

By Ren G. Dong, John Z. Wu, Daniel E. Welcome, Kristine Krajnak

Although the exact mechanisms underlying vibration white finger (VWF) are not clear, it has been speculated that VWF is associated with variations of the blood flow patterns due to the physical damage and/or degeneration in neural and vascular tissue caused by vibration loading [1]. Excessive dynamic deformation of the soft tissues in the fingertip under vibration loading is believed to induce multiple occupation-related hand/finger disorders. However, the in vivo distributions of the dynamic stress/strain of the tissues in the fingertip under vibration conditions have not been studied because they cannot be measured experimentally to date. The goal of this study is to analyze, theoretically, the location and frequency-dependent dynamic deformation of the soft tissue in the fingertip during vibration exposures. [ ] Methods The fingertip considered in the model is the distal phalanx, the portion from the distal end of the fingertip to the distal interphalangeal (DIP) joint articulation (Fig. 1). The external shape of the fingertip was determined using a smooth mathematical surface fitting to the observed fingertip shapes. The fingertip surface was then scaled to the dimensions of a typical male index finger: length 25 mm, width 20 mm, and height 18 mm. The fingertip was approximated to be symmetric, such that only a half of the fingertip was considered in the FE modeling. The fingertip was assumed to be composed of outer and inner skin layers, subcutaneous tissue, bone, and nail. The soft tissues (inner skin layer and subcutaneous tissues) were assumed to be nonlinearly elastic and viscoelastic, while the bone, nail, and outer skin layer were considered as linearly elastic. The simulations were conducted using a displacement-controlled protocol in two stages. First, the fingertip was statically pre-compressed. The contact plate was first displaced towards the finger to achieve a predetermined value of tissue deformation (i.e., 0.5, 1.0, 1.5, and 2.0 mm). Second, the steady-state dynamics responses of the fingertip were analyzed using a linear perturbation procedure. The fingertip was subjected to a continuous harmonic excitation (magnitude 0.5 mm) from the contact interface. The dynamic analysis was performed in a frequency domain ranging from 16 to 2000 Hz. The frequency-dependent distributions of the vibration magnitude and dynamic strain magnitudes in the soft tissues are investigated. Results Typical simulation results for the frequency-dependent distributions of the vibration magnitude in the soft tissues are shown in Fig. 2 (figures show the results with a pre-compression of 2.0 mm). The vibration magnitude at the contact surface is 0.5 mm (specified) for all frequencies, while the vibration magnitudes in the soft tissues are location- and frequency-dependent. It is clear that the fingertip has a major resonance around 125 Hz, at which the vibration magnitudes in the soft tissues are over four times greater than that of the contact plate (0.5 mm). It is interesting to observe that, at this resonant frequency (125 Hz), the soft tissues at the tip has the maximal vibration magnitude while the regions near the contact

Jan 6, 2006

Carlisle: An old friend and good friend, Alan Bateman, is the Silliman Professor of Geology Emeritus at Yale and editor of the Journal of Economic Geology. Now, Alan, let's start off by telling us something about how you became interested in copper. Bateman: Well, after I left Yale in 1913, I was appointed one of the field members of the Secondary Enrichment Investigation. We spent three years in the field studying all the copper deposits of North America, trying to find out how secondary copper enrichment took place. As part of this investigation, I went up to Kennecott, Alaska, in 1916. After the trip I was asked by the president of the company to become consulting geologist to them. I accepted his offer, and to this day I'm still consulting geologist to the Kennecott Copper Corp. Up at Kennecott, there were both Henry Krumb and my good friend Henry DeWitt Smith, who was general superintendent. He and I had been together at Yale, and I had ushered at his wedding. Interestingly enough, Henry took his bride to Alaska and I took mine there two months later. My assistant was Don McLaughlin, and I think that was his first experience in a mining camp. We published a paper on Kennecott together and cemented a friendship lasting to this day.

Jan 11, 1964

By Liming Yuan, John C. Edwards, Gene F. Friel, Robert A. Franks

Diesel fuel fire experiments were conducted in NIOSH’s Pittsburgh Research Laboratory’s (PRL) Safety Research Coal Mine (SRCM) to determine the critical air velocity for preventing smoke rollback. Such information is necessary for the preplanning and implementation of ventilation changes during mine fire fighting and rescue operations. The fire intensity varied from 50 kW to 300 kW depending upon the fuel tray area. Airflow in the 2 m high and 2.9 m wide coal mine entry was regulated during the course of each experiment; measured upwind from the fire as an average over the entry cross-section with an ultrasonic airflow sensor; and recorded dynamically with a mine monitoring system. The extent of smoke reversal was monitored with light obscuration monitors, ionization smoke sensors, and visual observations. Experimental results for the critical air velocity for smoke reversal as a function of fire intensity compared very well with model predictions based upon a computational fluid dynamics (CFD) fire dynamics simulator.

Jan 1, 2005

By Martin G. Castro, Renato G. Bautista, Morton Smutz

During the last 25 years, multistage mixer-settlers have been used extensively for liquid ion exchange work. The mixer-settler has the advantage of being a compact device in which a large number of stages can be assembled in a relatively small area. They are particularly advantageous for the separation of rare earths. Most of the adjacent rare earths have separation factors which are near one, which means that a large number of stages are needed to produce a good separation. When two elements (m, n) are extracted simultaneously, the separation factor (ßm, n) is defined as: [ ] where Ym, Yn are the molarities of the respective elements in the organic phase and Xm, Xn, are their molarities in the aqueous phase at equilibrium. The industrial consumption of rare earth oxides rose to over 6800 tons in 1968, an increase of 33% over 1967.1 The increased production and demand for rare earth and lanthanum chlorides for petroleum cracking catalysts was one of the principal factors in this increased consumption of rare earths. In 1968 approximately 59% of the rare earth oxides produced were used for gasoline cracking catalysts in the form of rare earth and lanthanum chlorides. There was also an increase in the sales of lanthanum oxides for use in optical lenses and in fiber optics. The future looks good for the rare earth industry. The rare earths can be expected to be used in many new products which are being developed. Until the late 1950's tributyl phosphate (TBP) was the principal solvent used in rare earth liquid ion exchange. In 1957 Peppard3 reported the use of di (2-ethyl-hexyl) phosphoric acid (D2EHPA) as a solvent for separating the rare earths. Rare earth separation factors of up to 2.5 were obtained in nitrate and chloride systems while the maximum separation factor using the

Jan 1, 1972

By Günther M. Volkmann

Continuous developments in tunneling require knowledge transfer between designers and suppliers to optimize the application of support systems. This collaboration allows the designer access to the latest research results, technical innovations, and support specific measurement techniques as well as the supplier?s experiences on recent projects. Project specific requirements determine the information that can be used to increase support system efficiency, advance rate, degree of safety, or decrease costs. This cooperative effort results in not only an unambiguous tender document, but also an optimized design with reduced risk that is coordinated with safe and high performance construction techniques. This paper will address the benefits of an early collaboration to both the design and the specifications in the tender document by using the A3 Hindhead project (UK) as an example.

Jan 1, 2008

By Irwan S. Halim

For tunnels in horizontally bedded rock, geologic factors affect the selection and design of the initial supports, including the rock propensity toward parting along bedding and the resulting high potential for rock slabbing during excavation. To evaluate this ground behavior, numerical analyses and results with Mohr-Coulomb, Hoek-Brown, and Ubiquitous Joint constitutive models were used, using the Upper Rouge CSO tunnel in Detroit, Michigan as an example. The different rock models and other geologic considerations are shown to impact the selection of the tunnel initial support and design. This paper emphasizes the appropriate selection of an analytical model based on the site specific geology to achieve an optimum initial support design.

Jan 1, 2008