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By Wayne R. Hopkins

Southern Arizona has one of the world's principal concentrations of copper ore bodies. Twenty miles south of Tucson, close to the Mexican border at Sahuarita in Pima County, is the Twin Buttes mine. In mid-1973, the Anaconda Company and American Metals Climax Incorporated (AMAX) established a 50-50 partnership to operate and expand the Twin Buttes property. Anamax Mining Company was established as the operating company for this joint venture. The production from the Twin Buttes mine is shared between the two partners who market independently. A major expansion of the Twin Buttes operation has included an accelerated stripping programrne for the pit, an expansion of the sulphide concentrator, the construction of an oxide leach plant and a 57 MW diesel generating power station. Part of this major expansion, the large tonnage oxide processing plant was brought on stream in 1975 and is now close to design capacity. The "mine to market gap" has been closed by producing high-purity copper cathodes at the mine site from oxide ore reserves. By using a hydrometallurgical process route, copper production is possible with negligible effects on the environment.

Jan 1, 1976

By S. Monette, D. B. Dreisinger, D. Vleeschhouwer, G. B. Harris, G. A. Kordosky

A new process for the recovery of pure (>99.95%) palladium and platinum is described. The process, which has been tested at the pilot scale, comprises (i) the simultaneous solvent extraction of palladium and platinum by a new Schering Berlin reagent, TN 1911, (ii) washing of the loaded extractant to remove co- extracted impurities, and (iii) differential stripping of first platinum at pH 3, and secondly palladium with strong hydrochloric acid, and (iv) precipitation of palladium and platinum salts, followed by reduction to metal. The process is, unusually, a non-ammonia one requiring only small amounts of ammonia at the end where final purification may be necessary for particularly complex feed solutions.

Jan 1, 1993

By M. C. Mound

A recent development using XRD techniques, a unique fixed detector, specifically permitting full mineralogical information simultaneously for the first time, specially designed sample preparation and presentation system and Rietveld codes provide a continuous real- time analysis on the true contained mineral polymorphic composition of powder streams such as ore materials, cement, ground clinker or any other mineral stream conducive to XRD analysis. There are several COSMA systems currently operating in the US, Canada, Italy and Australia, proving service and reliability of this concept. The mineralogical information generated continuously in real time is used for automated efficiency, product quality and reduces costs. Quantitative Phase Analysis information is transmitted to the plant DCS via Modbus over RS422 or ethernet. Some limited information is stored in the on-board computers for optional future use at the operator?s option.

Jan 1, 2010

By Kang-Hyun Lee, In-Mo Lee, Byung-Kyu Kim, Parkm Jinho, Seoung-Won Lee

"In this study, the TBM Resistivity Prediction (TRP) system is developed for predicting the location, thickness, permittivity ratio and electrical conductivity of anomalous zones ahead of tunnel face using the measured resistivity of the ground. The applicability of the developed system was verified by performing field tests at a construction site in which an EPB-shield TBM is used for tunnelling work. In the first field test, it was found that the rock around the tunnel face had the same resistivity and permittivity with the rock ahead of the tunnel face indicating no anomaly ahead of the tunnel face. In the second test, a stronger zone 5-m thick was predicted ahead of the tunnel face based on lower permittivity than that of the rock around the tunnel face. The ground condition assessed by the newly developed TRP system matched well with that either predicted from geophysical exploration or directly obtained from drilling boreholes or from daily observed muck conditions. INTRODUCTION During tunneling work, the emergence of unpredicted zones of relatively weaker or stronger ground can lead to delays in construction work or an increase of construction cost. Predicting anomalous zones ahead of tunnel face in advance can thus prevent time and economic loss. For these reasons, various methods to predict the ground condition ahead of the tunnel face have been studied and developed. Prediction methods using various kinds of equipment include tunnel seismic prediction, ground penetrating radar, electromagnetic surveys based on electronic antennas, and electrical resistivity surveys conducted by analyzing electric currents in the ground ahead of the tunnel face (Ryu et al. 2008). However, most of the prediction methods are only applicable to conventional tunneling job sites, which feature free access to the tunnel face. In mechanized tunneling projects, accessibility to the tunnel face is very limited because the tunnel face is occupied by the TBM."

Jan 1, 2016

By Richard W. Brummett

Problems in new strip mine development is a subject that could require several days to cover adequately. Coupled with the fertile imagination of television writers, we could probably expand it into a series rivaling Gunsmoke in longevity with just as many shootouts at sundown. It would-of course-be subject to a high Neilson Rating. To bring the subject into perspective, we will limit the comments to a general discussion covering western strip coal developments. Stimulated by increased demand for low sulfur coal, surface mineable western coal operations began a shift into high gear approximately four years ago. Then came last year's "energy crisis" that increased the pressure on coal development not only in the west, but nationwide. Several eastern power plants having dual oil and coal burning facilities were directed to discontinue using oil. Also, a number of new south and southwestern power plants scheduled to burn natural gas or of I commenced an ordered conversion to other fuels, namely, coal. The involved utilities with reserve positions accelerated their planning while others began the search for long-term commitments from coal producing companies. In addition, announcements were made for proposed mine mouth coal gasification projects in New Mexico, Wyoming, and North Dakota.

Jan 1, 1974

By D. K. Adjei, G. Ofori-Sarpong, R. K. Amankwah

"Mercury (Hg) is toxic and has long-term effect on the muscle tissues, the brain and the central nervous system functions due to its bioaccumulation and biotransformation effect. Hg pollution around the world is high and this has attracted much global concern such as the Minamata Convention on Mercury, held in 2013. For several years, mercury has been the chemical of choice for Artisanal and Small-Scale Mining (ASM) gold extraction, accounting for about one-third of the global mercury consumption. A greater percentage of this ends up in the environment through open burning of amalgam, spillage and indiscriminate disposal of waste. To break this wall of mercury pollution, it is very important for the mercury used to be recycled through the use of mercury retort units. This brings into the limelight, the Lantern Retort which tries to synergise the high conductivity of steel and the see-through effect of glass, thus, improving the amalgamation process. A research conducted on improving the original Lantern Retort arrived at an appropriate distillation length of 5.08 cm which was used in redesigning a more efficient retort. The improved Lantern Retort recovered about 98% of the mercury used. INTRODUCTION Artisanal and Small-scale mining (ASM) is an informal mining activities which employ quite simple tools such as pickaxes, sluice boxes, shovels, chisels, metal bars, mattocks and water pumps for mining and processing of gold ores. The artisanal and small-scale mining (ASM) sector has served as source of employment for many people in developing countries including Ghana (Aryee, 2001; Hilson and Potter, 2003; Amankwah and Anim-Sackey, 2004; Amankwah et al., 2010) and has provided a substantial amount of foreign exchange through its activities (Hilson, 2001; Styles et al., 2010). Hentschel et al. in 2003 estimated that about thirteen (13) million people are said to be engaged directly in the small-scale mining activities worldwide. However, an estimated 100 million people are said to depend on this sector for their livelihood mainly in developing countries. In China alone, a projected number between 3 and 15 million people are engaged in artisanal and small-scale mining activities (Hentschel et al., 2003), whilst in Ghana, it is estimated that more than 1,000,000 people are employed directly or indirectly in the artisanal and small-scale mining activities, with 10% being women (Amankwah and Anim-Sackey, 2004; Amankwah and Ofori-Sarpong, 2014). In Ghana, ASM gold production has grown from a low of 2.2% in 1989 to a high of 34% in 2014. This figure is estimated to increase with proper documentation. This indicates that the sector has made significant socioeconomic impact on many individuals and communities as a whole. Notwithstanding the above positive contributions, the sector has also contributed to negative impacts on human, aquatic life and the environment in general due to indiscriminate mercury emission. This ‘pollution wall’ needs to be broken, and several interventions have been put in place including the use of retort units like the lantern retort (Adjei et al., 2014; Amankwah and Ofori-Sarpong, 2014)."

Jan 1, 2017

By Scott G. Britton

Up to now, the hands-on approach to construction has been stressed. This chapter reviews the basic tools available for construction design and monitoring of a construction project. It is divided into three discussions, all under the general title of computer aids, since the trend for using these tools-is via the computer. In the context of our discussions, the focus for computer aids will be on the use of evaluation and analysis techniques for coal mine construction applications, including mainframe programs, CPM techniques, as well as mini and microcomputer applications. Although the presentation of material in this chapter may be detailed at times, by no means does it cover the entire field of computer applications for design or project scheduling and monitoring. It is only an attempt to illustrate the possibilities that are available to construction and mine engineers. Interested persons can pursue computer applications for coal mining by reviewing Computer Methods for the 80's. by Alfred Weiss, editor, published by SME-AIME.

Jan 1, 1983

By Harold Bloom

Dimethylglyoxime reacts with nickel in a buffered ammonical-citrate solution containing the detergent ?Aquet? and hyroxylamine-hydrochloride. The resulting nickelous dimethylglyoxime is extracted with xylene. Visual comparison with standards permits the estimation of from 50 to 10,000 ppm of nickel. Soil, rock, or sediment may be decomposed by digestion with (1-3) nitric acid, allowing about 70 determinations per man-day to be carried out. With minor modifications to the above procedure, sediment and soil may be semi-quantitatively analyzed for nickel at the sample site. The chemical equipment is easily portable and the analysis extremely rapid because the buffer, dime thylglyoxime and xylene are added simultaneously to the sample and no heating is required. The sensitivity varies with the "availability" of the nickel ions; under favorable conditions, one may obtain a positive test for as little as 10 micrograms in soils and sediments. This procedure is similar to one, for the field determination of heavy metals described elsewhere by the author.

Jan 1, 1958

By Thomas Schwind, Elmar Feigl, Gerald Skalla, Angelos Gakis

Cedarvale station was constructed as part of the Eglinton Crosstown Light Rail Line, under the operational Yonge-University Line Subway box of Toronto Transit Commission (TTC). The station was constructed as an open-cut, which necessitated the underpinning of the existing TTC box to minimize the impact on the Subway and allow its unhindered operation. Six mined galleries, 4 m wide by 2.75 m high, were excavated sequentially (SEM) immediately under the existing box, to provide the required space for the installation of the main underpinning beams. This novel solution was executed successfully providing quick access for the main excavation works to commence.

Dec 1, 2022

By R. Frenette, A. W. Mo, H. A. Hamza

Fine particles present major technical and economic problems to those who deal with solid/liquid separation processes. In the coal industry the problem is compounded by the large amounts of produced fines such as those present in Western Canadian coals. Flocculants in the form of high molecular weight water soluble polymers are commonly considered an effective solution for the enhancement of the separation process. These reagents are relatively expensive especially when considering a low-price commodity such as coal. Optimization of the use of these reagents is therefore an operational necessity. Six polymers were evaluated as to their effectiveness in flocculating a fine coal tailing. Results were compared with those for a reference flocculant, in-use at that time in the washery. It was shown that, in general, flocculants significantly improve the solid/liquid separation process. The ranking of the flocculants as to their effectiveness in settling and filtration indicated that the best flocculants for settling were not necessarily the most effective for filtration. Flocculants that showed the best filtration improvement were generally cationic and those best for settling were anionic.

Jan 1, 1988

By Fred T. Towne

There are a number of air classifiers manufactured throughout the United States and the rest of the world. The classifiers manufactured by Alpine, A. G. of Augsburg, Germany, are unique in their abilities. It is this uniqueness that I wish to delve into and in this respect we will limit this discussion primarily to the classifiers as manufactured by Alpine. It has been reported in the past that these classifiers were introduced into the. United States in the late 50's. Until the introduction of the Alpine Classifiers, air classification seldom produced a satisfactory fractionation of a product below 45 microns (325 mesh) or above approximately 22 mesh. It has been a common practice to classify fine materials which used water as a carrier medium The use of centrifuges are today producing thousands of tons of finely partitive powders in the very small particle size range. The use of centrifuges in connection with wet grinding mills has increased the rates of production of these mills considerably.

Jan 1, 1965

By Caren Caldwell, Leslie Thompson

1.1 Biological Process Description Pintail Systems, Inc. (PSI) has developed and in partnership with their clients in the mining industry has applied biological remediation processes for detoxification of spent ore and process solutions from heap leach operations. Contaminants that are treated to mine closure levels or drinking water standards include cyanides (weak acid dissociable and total cyanides), thiocyanate, nitrates and heavy metals. Biological processes are both site-specific and ore-specific processes. PSI specializes in isolating indigenous microorgan­isms from spent ore and process solutions and augments them in the laboratory for enhanced bio-detoxification in the field. Bioaugmentation in the lab is a key to successful heap bio-detox in the field. In PSI's bioaugmentation processes native microorganisms are isolated from the spent ore environment and are tested for contaminant remediation capacity. A majority of the indigenous microbes will be tolerant of the spent ore environment but will not contribute to contaminant metabolism. Indigenous enrichment or biostimulation of these non-working microbes by adding trace nutrients can competitively inhibit the working microbes. For this reason PSI focuses on the bioaugmentation process where non-working microbes are discarded and the working population is enhanced through stress, mutation and exogenous enrichment before it is re-introduced to the heap and process solutions.

Jan 1, 1997

By John O. Marsden

Process selection is the systematic development of the optun.m metal extraction route for a particular feed matenal and has two main objectives: (1) to optimize project economics, principally a function of gold recovery, throughput rate and processing costs, and to develop a process that satisfies all of the proct requirements including, for example, political and environmental considerations.

Jan 1, 1992

By D. D. Potter

ABSTRACT OF ORAL PRESENTATION Extraordinary conditions are often encountered when designing large blasts for in situ mining methods and spatial or innovation techniques are sometimes required. Some of the considerations in designing these large blasts will be discussed with emphasis on those factors that concern powder factor, rock movement and fragmentation. Sources of basic data will be described, along with some of the methods for obtaining these data.

Jan 1, 1977

By Edgardo I. Cifuentes, Andrew L. Mular, Andrew Burkert

Experimental designs are data acquisition plans which, if followed exactly, will quickly provide process engineers with information to assess statistically the individual and joint influence of factors on responses to permit of rapid decision making. Methodology employed to construct data acquisition plans is described in some detail. In production environments, factorial designs are appropriate for most purposes. Use of two level factorials to make decisions is described for a grinding circuit.

Jan 1, 1991

By Richard A. Bideaux

Using computer applications to solve mining problems began in the early 1960s, utilizing the large (for that day) centralized computing facilities at a few universities and major mining company headquarters. Many years passed before technology was adequate to allow any of those applications to be run at the mine sites to provide immediately available solutions. One of the first mining applications attempted was for ore reserve analysis and long- to medium-range mine planning. As these are among the most frequent and familiar minicomputer applications at the mine site, it is interesting to follow the evolution of computing and communications hardware which has finally allowed effective transfer of this technology.

Jan 11, 1981

By W. E. Benton

Diatomite or diatomaceous earth is a siliceous sedimentary rock principally made up of the skeletal remains of the diatom, a microscopic, single-cell aquatic plant related to algae. The unique structure, chemical stability and physical properties are the major attributes of diatomite not met by other forms of silica. The production of diatomite was down in 1982 vs. 1981, reflecting the worldwide recession. The principal markets for diatomite products continue to be basically filtration and fillers. The outlook is for small but steady growth into the 1990s.

Jan 1, 1983

By Rick Sarkisian, Greg Girardey, David Keech

The Conveyor Equipment Manufacturers Association (CEMA) specification B105.1 "Welded Steel Conveyor Pulleys" adequately defines pulley assembly standards for light material handling applications. However, most mining applications demand pulleys of higher reliability and load capacity than that offered by CEMA standard pulleys. Various sources have published specifications for "Engineered" conveyor pulleys. Typically, these specifications require T-section type pulleys applicable to operating belt tensions exceeding 439 N/mm (2,500 lb./in.). This paper examines the application of CEMA standard pulleys, T-section pulleys and also a mining duty pulley design. The mining duty pulley fills the void between CEMA standard pulleys and T-section pulleys and can eliminate the high cost and long lead times associated with T-section type pulleys.

Jan 1, 1998

By Gordon M. Pugh, David G. Rasmussen

INTRODUCTION Square-set timbering of stopes developed from stull support methods because veins too wide for stulling were being mined. In general, the void caused by the stoping of the ore is filled with a system of interlocking timbers. Timber framework supports the wall rock, the mining operations, and provides access. A timbered stoping method can be used in all widths of veins at any dip. The timbering can be normal and parallel to the planes of the walls or at angles to these planes. Irregularly shaped ore bodies can be worked by timbered methods. Pinching or swelling of the vein will not adversely affect the method. Timbered stoping is especially advanta¬geous where weak ground is encountered in the vein or the wall rock. The ground is unsupported only until timber sets are stood. These stopes can be filled with sand or waste when desirable. The customary method of developing a square-set timbered stope with haulage drifts above and below and timbered raises on each endline is shown in Fig. 1. The drifts are timbered the full stoping length. The raises have two compartments with the manway and timber slide in one compartment and the chute in the other. The drifts and the raises cannot be widely spaced as handling timbers is an important consideration. Stoping can begin immediately above the drift timber and continue in both directions and upward from the raise. Breasting down each blast round for only one timber set laterally is the common practice. The blasted ore falls to a lower floor where it is slushed or trammed to the chute. Drilling can proceed on the upper floor while broken ore is being removed from the stope. As shown in Fig. 2, square-set timbering may be used in cut-and-fill stopes to support the back and walls until fill is added. There are various ways of developing an ore block for timbered stoping. Fig. 3 depicts the situation for the main haulage in the vein with an intermediate drift separated from it by a sill pillar. The ore is slushed into the chute connecting the two drifts. The situation in Fig. 4 is identical to that in Fig. 3 except that no sill pillar is used. In Fig. 5, the haulage drift development is done in the footwall with crosscuts driven to intersect the ore body. The intermediate drift development is above the crosscuts with a minimal sill pillar. The main bottleneck in timbered stoping is in the timbering process. Drilling in the stope is generally held up while timbering is done. Two or three men are re¬quired to do the timbering and an additional one or two men are needed to transport and raise or lower the tim¬ber. Good organization is essential to timbering. Skill must be exercised in standing the timber to support the ground and still maintain good production. COSTS AND PRODUCTIVITIES Development and stoping costs are presented in Tables 1 through 7 for the situations in Figs. 3 and 5,

Jan 1, 1982

By Alfred Jr. Petrick

Modelling of cash flows and calculation of net present value of rate of return over the expected life of a mine/processing unit continues to be the accepted basis for mineral investment decision-making. The computer and spreadsheet programs have greatly improved ability to perform sensitivity and risk analysis, hence our ability to deal with key analytical problems. These problems of cash flow analysis result from the necessity of forecasting an uncertain and risky future. Cash flow models begin with the critical assumption of a "design basis", then integrate all of the variables relevant to the investment decision including forecasts of price, cost, taxation, financial conditions, and company strategy. Alternate "scenarios" portray possible future outcome of the investment decision. The potential for straying from reality is enormous. The computer has eliminated the time consuming hand calculations from the cash flow analysis, but the analyst still struggles with the risk of trying to predict "how the project will really turn out".

Jan 1, 1991