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By T. R. Ellis

Minerals Appraisers/Valuers often find great difficulty or failure in attempting to employ the Sales Comparison Approach to the Market Value Appraisal of development and operating stage mineral properties. An important factor generally overlooked is a comparison of net operating income (NOI) margins on a per-unit-of-production basis between mineral properties, whether these be demonstrated or forecast margins. NOI margins can vary greatly between mines or quarries that are producing similar products. Ultimately, the expected NOI margin determines what a buyer is willing to pay for an income producing property. Common criticisms of the sales comparison approach by minerals appraisers are introduced. These are counterbalanced by raising some issues in the way the inputs for the Income Approach are usually derived by minerals appraisers, and by review of some conspicuous examples of the much too common misuse or abuse of the income approach in market value minerals appraisals. Example transaction analyses and sales comparison analyses are used to demonstrate the author?s methodology for adjusting units of resource in his transaction adjustment tables (see APPENDIX). The examples are used as the basis for discussion of ways to employ adjustments for operating economics and many other factors, while cautioning about the potential for double counting. The conclusions include a recommendation that minerals appraisers attempt to apply at least two of the three valuation approaches when appraising the market or fair value of development and operating stage mineral properties, the two being the sales comparison and income approaches.

Jan 1, 2011

By Quin Dennis

Process Optimization ?What is it really? It is NOT ?a larger fan to increase draft through a process ?a larger pump on a wet circuit ?a wider conveyor belt for solid materials ?a larger feed elevator into or out of a process These relieve individual constraints ??bottlenecks??and allow operation to the next constraint in the process ?It is also NOT about automating the operator ?which captures consistency but is not continuous optimization

Nov 1, 2011

By Ellsworth R. Spencer

An assessment of U.S. western hardrock miners? noise exposures was conducted as part of a multi-year National Institute for Occupational Safety and Health (NIOSH) survey of noise exposures in each sector of the mining industry. Noise from selected mining equipment and operator noise exposures were measured, analyzed and tabulated for dissemination to the participating sites and are being used to direct NIOSH research and interventions to address the greatest noise hazards. Eighty-two noise dosimeter measurements were obtained, along with time-motion studies as the miners operated hardrock mining machines. Of the operators, 96% had daily noise doses that exceeded the U.S. Mine Safety and Health Administration?s (MSHA) permissible exposure level. The average gold miner dosages while operating the following equipment were: haul trucks - 261%, load-haul-dumps (LHDs) - 235%, single boom drills - 221%, bolters - 214% and dual boom drills - 163%. The worst exposure level was a silver miner with a daily dose of 873%. Time-motion data showed that this miner?s exposure accumulated most rapidly while operating a jackleg drill. These results will be used to help prioritize noise control development by NIOSH and other partners.

Jan 3, 2010

By Yoichi Takeda

The CaO-FeO,-Cu20 slag has been practically applied to continuous converting of copper, and also has potential for refining of copper. Liquidus lines of the slag system and phase stability diagram for the liquid slag and the existing solid compounds under copper saturation are presented. Liquidus composition was determined by chemical analysis of slag sample saturated primary solid. The temperatures of invariant equilibria were investigated by thermal analyses. Oxygen potentials on the liquidus lines, the univariant and invariant equilibria were estimated from the relation slag composition and oxygen potential that relation was confirmed in separate experiments.

Jan 1, 2003

By Zhang Baoshan

In this paper, the forced features and dynamic behaviors of stone-column composite foundation are concisely related. The characteristics of Rayleigh wave method is summarised. This method is proposed in which, the stress ratio of the stone-column to the surrounding soil and the bear­ing capacity of the composite foundation are determined. Through the engineering cases, it is shown that, checking and evaluating the composite foundation in this method, is feasible, with high speed and low cost.

Jan 1, 1991

From Sept. 22-24, the Las Vegas Convention Center will be home to MinExpo 2008, the world?s largest mining equipment show that comes along once every four years. Sponsored by the National Mining Association (NMA), this year?s show is on pace to be the largest ever. Nearly 1,300 exhibitors have purchased nearly 55,700 hm2 (600,000 sq ft) of booth space. At the center of it all will be some of the most impressive mining equipment that the industry has to offer. And in the shadows of the massive haul trucks, drill rigs and bulldozers, attendees will be able to see the latest and greatest products including hand tools; the latest in automation and robotics; safety and communications equipment; longwall mining equipment; engines and parts; materials handling and processing equipment and services; pollution control equipment; reclamation equipment and services; computer applications; consulting and financial services and more. While many companies will be on hand to display the tried and true, there will also be plenty of new things to see. ?We anticipate that a whole range of new products will be introduced at the show,? the NMA said of the show that has been called the world?s richest deposit of mining technology, services and products. In addition to the show that will take place in Center Hall and North Hall of the Las Vegas Convention Center, MinExpo 2008 includes a conference program with 20 educational sessions that will tackle the most timely and pressing issues affecting the mining industry. Many of the industry?s top professionals will lead the discussions.

Jan 1, 2008

By Thomas Lardner

Excavation for The Bow, EnCana, in downtown Calgary, occurred between May 2007 and September 2008. A monitoring programme was used to determine the behaviour of the shoring wall, soil and bedrock during the excavation for the 21 metre (69 ft) deep excavation with a footprint of approximately 17,000 m2 (183,000 sq ft). Results from the inclinometer readings indicated that significant horizontal movement due to a weak rock layer and shear band effect. These modes of movement account for up to 100 mm (4.0 in) and 45 mm (1.8 in) of lateral deflection, respectively. Based upon the results of the monitoring programme, rock samples were collected from the weak mudstone bedrock, with great difficulty, to determine the strength and deformation parameters. Results from the uniaxial compression tests indicate a UCS around 830 kPa (120 psi) and elastic modulus between 80 and 180 MPa (11 and 26 ksi). Mohr-Columb parameters were determined to be c' = 340 kPa (49 psi) and f' = 24°. Residual strengths were determined to be c'r = 0 and f'r = 15°. Using the results of the laboratory tests and field investigation records, an initial finite element analysis was conducted. Results of the analysis show good correlation when compared with the observed monitoring deformation, indicating accurate portrayal of rock parameters. Additional analysis and investigation is required to determine the principal horizontal stresses in magnitude and direction.

Jan 1, 2010

By Albert L. Toenges

The production of coal from underground mines in Washington declined during the recent war owing to shortage of manpower, and coal was shipped to the Pacific Northwest from mines in the Rocky Mountain region. The movement of this coal into Washington required the use of railroad equipment that otherwise could have been used for transporting war materiel and personnel. Strip mining uses a minimum of manpower, and the development of coal areas in the Pacific Northwest that can be mined by the strip method should increase production in the area, thus releasing railroad equipment from the necessity of transporting coal long distances and also providing consumers with a lower-cost product. The development of a strip mine to supply the demand at low cost requires a large investment in heavy equipment. In order that the fixed charges due to large investment in plant and equipment may be kept at a minimum, large reserves of coal must be proved. A reconnaissance of an area near Toledo, Lewis County, Wash., indicated a large bed of lignite that could be mined by strip methods. The area is approximately midway between Portland, Oreg., and Tacoma, Wash. (refer to fig. 1), and the opening of a large mine in the area would supply fuel to these and other nearby centers.

Jan 1, 1947

By Paul Laframboise, Nigel MacDonald, Mike Hallewell, Robert Thorpe

"Galmoy Mine, owned by Arcon Mines Limited, has operated since 1997, and is one of three operating lead/zinc mines in Ireland. Changes in ore type starting in mid 2002 created challenges to metallurgical operations at Galmoy. This resulted in unacceptable lead and zinc flotation performance, which prompted initiation of a formal plant review and a subsequent stabilization programme. This involved a structured review of operational practices, development of a new Standard Operating Procedure (SOP) which in turn led to significant changes in process control equipment needs in conjunction with extension of zinc flotation cell residence time.This paper will describe the metallurgy of the Galmoy operation. Reasons for the poor metallurgy experienced in 2002 will be described, as well as the solutions identified to overcome these problems. By the second quarter of 2003, these solutions had been implemented and recoveries had risen to record levels.INTRODUCTIONGeneralGalmoy Concentrator is located in County Kilkenny (Refer to Figure 1 below) and was constructed during 1996 and commissioned in 1997.The concentrator at Galmoy had been designed initially to treat 650,000 tonnes per annum of primarily CW ore type. The main mineral of economic significance was sphalerite (Typically 10 to 11% Zn) with some minor galena (0.7%Pb) in a dolomite (Magnesium Carbonate) host rock.The only other competing sulphide mineral was pyrite (Circa 3 to 5% Fe in Mill Feed. This CW ore type predominated the first 6 years of production, but in August 2002, the ore mineralogy changed due to significantly higher levels of pyrite rich G ore body being blended in with CW ore."

Jan 1, 2005

The modern Golden Cross mine entered the production phase in January 1992. The project is designed to produce over 100 000 oz/yr of gold and over 300 000 oz/yr of silver during a mine life of eight years. An open pit and an underground mine are operated producing around 850 000 t/yr of ore, to feed a conventional carbon-in-leach processing plant. Golden Cross is owned in joint venture by Coeur Gold New Zealand Limited (80%) and Viking Mining Company Limited (20 %).   Since the start of production several major aspects of the design have altered. The underground mine began as a mechanised cut and fill operation. The cut and fill stoping progresses in 3.3 m flatback lifts with maximum stoping width of 6 m. Where the ore zone is wider than 6 m a post pillar cut and fill method is used. In 1993 a new bench mining plan was introduced between the 270 and 260 levels. Flatbacking continued in the footwall drives in anticipation of variability of the ore width and orientation. The development of levels below the main service 200 level has indicated a possibility of bulk mining the ore block rather than flatbacks. This could lower mining costs but also introduce higher dilution rates. Development is in the advanced stages for trialing this method.

Jan 1, 1994

By M. Kuchta, A. Newman

LKAB’s Kiruna Mine, located in northern Sweden, produces about 24 Mton of iron ore yearly using sublevel caving. For efficiency, the mine must deliver planned quantities of three ore products. We use mixed integer programming to schedule Kiruna’s operations, specifically, which production blocks should be mined, and when they should be mined to minimize deviations from planned production quantities while adhering to mining restrictions (e.g., sequencing). A new production block database and a well-formulated mixed integer programming model dramatically reduce the size of the original problem; in less than ten minutes we generate five-year schedules with time fidelity of months.

Jan 1, 2002

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Jan 1, 2009

By M Scoble

This paper will report on the application of data collected through the performance monitoring of large diameter surface rotary blasthole drii and electric mining shovels, in an integrated approach to blast optimizatiion.

Jan 1, 1992

ABSTRACTMechanised cut and fill stoping in the Racecourse orebodies between II and 9 levels was started in 1964.Five stopes are in progress over the two level interval, extracting the full strike length (600-2,000 ft) of each orebody without transverse pillars.Each stope is served by a central 10 ft by 12 ft service intake ventilation raise and an 8 ft by 8 ft return air raise at each end of the stope. Each stope is divided into two sections for drilling. firing. mucking, and fillingto maintain steady production. All equipment is kept in the stope for one level lift stoping. Gardner-Denver 2 boom jumbos are used for uphole drilling and Wagner ST 5 Scooptrams for loading and transport to ore passes located in the footwall of the orebody. A Wagner PTIO is used for materials handling and scaling of the stope backs.Mill tailings, after one stage of cycloning are used to fill the stope, one section at a time. About 80 per cent of the water is removed by decantation while the remainder percolates through hessian-covered pipes and boxes.The ore is passed to 11 level where it is hauled by the 3 ft 6 in. gauge train to the tipple at the shaft area. The ore is crushed underground before hoisting to the surface.A performance of about 100 ton/manshift is achieved by the drilling, blasting, and mucking crews in the stopes.

Jan 1, 1968

The process of pile driving disturbs the soil around the pile. The nature and magnitude of disturbance depends upon 1) the pile size, and 2) the nature of soil. Therefore, the prediction of a single pile behavior based on soil properties of undisturbed soil samples may not match its performance. Under lateral loads, the pile may loose contact with the soil near the ground surface especially in clays. The soil pile interactions are influenced the most by pile behavior in this zone. This situation further affects the tally of prediction and performance. Piles are used in groups. The zones of overlapping stress from one pile to the other both around the pile and below their tip particularly in soft soils, contribute to group effects. Empirical solutions have been developed for prediction of the pile group behavior. The group action is more involved under vibrations. Several cases of single piles and pile groups under static and dynamic loads from published records have been analysed. It has been shown that single pile test is the best source of information on the soil-pile-soil interaction effects.

Jan 1, 1989

By J. E. Crawshaw

"The few previous observations of the effect of turbulence on limits of inflammability have been made on a small scale in turbulence produced either by a fan or by movement of the mixture.By a suitable amount of turbulence from a fan the lower limit of methane was 5 per cent as compared with 5 per cent observed for quiescent mixtures in the same vessel.3 With a streaming movement of the gas mixture within the range of speed from 35 to 65 centimeters per second (69 to 128 feet a minute) the lower limit was approximately 5 percent,4 For a quiescent mixture of ethane the lower limit was 3.10 per cent ethane, but with fan running at a moderate speed a 3 per cent mixture exploded.5The object of the tests herein reported was (1) to determine the lower limit of natural gas in a mixture of natural gas and air Which would be ignited and propagate violently when the turbulence was produced by explosives fired from a cannon into the mixture; (2) to observe the behavior when the mixture contained less than this low limit; and (3) to determine how turbulence produced by a fan affects thin limit.Four series of tests were run, three of which were to determine the effect of different sources of ignition: Tests with (1) an electric igniter; (2) 3F black blasting powder stemmed with 2 pounds of dry fire clay stemming used to ignite the mixture, and (3) 40 per cent straight nitroglycerin dynamite unstemmed. The fourth was made to study the effect of turbulence produced by a two-speed electric fan, using an electric igniter as the source of ignition.In both series of tests with explosives, charges of 50 and 200 were used to determine the effect of increased quantity of explosives on the lower limit of natural gas."

Jul 1, 1930

Laboratory scale equipment was developed to recover zinc as oxide fume from granulated lead blast furnace slag. The cyclone furnace process is characterised by high treatment rates combined with continuous and independent operation.Results were sufficiently encouraging to warrant pilot plant scale trials being undertaken.INTRODUCTIONSince granulation of lead blast furnace slag started at Port Pirie in 1921 the stockpile of this material has increased to nearly 5 million tons which averages 17·5 per cent zinc by weight. Although a number of processes for recovering the zinc have been examined, economic considerations indicate that a slag fuming process is likely to be most suitable.In the conventional slag fuming process zinc is extracted by injecting pulverized coal and air into a molten slag bath. By maintaining a suitable air to coal ratio the oxidised zinc contained in the slag is reduced to metal. Volatilization of the zinc is followed by reoxidation in the gaseous phase with the addition of further air above the bath. The zinc oxide fume so produced is collected by normal gas cleaning methods.By examination of the thermodynamics of this process Bell, Turner, and Peters (1955) determined the zinc oxide activity of the slag over the duration of the fuming cycle.A combination of high temperature and high carbon monoxide/carbon dioxide ratio was found necessary for rapid zinc elimination.Since melting of the slag is an essential step in the slag fuming process, only two treatment methods appeared possible at Port Pirie until recently...

Jan 1, 1964

By J. G. Groppo

A series of performance studies have been conducted using counter-current column flotation to recover a marketable clean coal product from existing preparation plant fine waste streams. The test work was conducted at several preparation plant sites in Kentucky and Virginia and utilized a 0.15m (6 in.) I.D. column that was 5.79m (19 ft.) high. The refuse streams tested included both thickener feed and classifying cyclone overflow with a typical size distribution of 100 mesh X O. The percent solids of the column flotation feed varied from 1.5 to 15% while the ash content ranged from 30-60%. The concentrates produced contained 2-10% ash with BTU recoveries of nearly 90% using 0.12-1.25 kg/ton (0.25-2.5 lbs/ton) fuel oil and 0.12 kg/ton (0.25 lb/ton) MIBC. These results were consistent with or better than results obtained in preliminary laboratory scale column flotation evaluation. Test results from 7 different seams are discussed as well as scale-up relationships utilized to design a full scale installation presently in operation.

Jan 1, 1990

By Jay Rodgers

There has been a longstanding acceptance that burden plays a major role in the magnitude of ground vibration amplitudes generated from surface blasting. Much of the data that this belief is based upon is empirical in nature and may or may not represent an example of false inference. Recent published reports have rightly questioned the influence of burden and confinement on blast vibration amplitude, suggesting that the fracture condition of the rock mass is a better indicator. The increased investment in electronic detonators as a tool to control ground vibration amplitudes demands an understanding of vibration production detailed enough to make use of the vastly improved timing accuracy that they provide. A more accurate relationship may be found if we strip away the assumptions of the past and search for the underlying mechanism of vibration production in surface blasting. We must answer the question: What happens at or near the borehole when an explosive charge detonates that produces ground vibrations?

Jan 1, 2003

By Thomas C. Anderson

Tiedback walls are now recognized and accepted as a good solution for a variety of structural problems: ? Retaining Walls and Bridge Abutments in cut situations ? Landslide stabilization ? Repair/support of existing walls Acceptable techniques have been developed for anchoring in cohesive and granular soils and in any kind of rock. Methods have been developed for adequately protecting tieback tendons against corrosion and for testing every tieback to verify its long-term load-carrying capacity. However, the major problem that the industry faces today is how do we get constructable and economical tiedback walls contracted for and built with minimal claims. This paper will explore the issue of "constructability" through a look at specific problems from actual projects. From a research report from the Construction Industry Institute, Austin, Texas (1986), constructability is defined "as the optimum use of construction knowledge and experience in planning, design, procurement and field/operations to achieve overall project objectives." Maximum benefits occur when people with construction knowledge and experience become involved at the very beginning of the project." The design and installation of tiebacks has been developed primarily by specialty contractors; each contractor has evolved its own methods of performing the work, and consequently, many of the techniques are patented and proprietary. The real question is, how do we make effective use of this knowledge and experience during the design phase of the project?

Jan 1, 1991