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By W. C. Hellyer

The Granduc ore body is located beneath glacial terrain on the borders of British Columbia and Alaska, some 600 miles from Vancouver and 30 miles from Tidewater at Stewart, B. C. The concentrator and attendant facilities are located in wilderness country at an elevation of 2500 feet. The average annual snowfall is 65 feet. Surface facilities and ore body are linked by a 10 mile railroad haulage tunnel. This copper property has been developed by Granduc Operating Company on behalf of Newmont Mining Corporation and American Smelting and Refining Co. First production started in November, 1970. In August, 1966, Granduc Operating Company awarded an engineering and construction management contract to McKee-Swan Wooster, a joint venture of A. G. McKee of Canada and Swan Wooster Engineering Company Limited, to design a concentrator to treat approximately 7000 tons of ore per day. The isolated location of the Granduc ore body indicated comparatively high freight rates on consumable items of concentrator supplies such as reagents, grinding media, etc. A firm flowsheet for the flotation of the Granduc ores having been developed by the Danbury laboratory of Newmont Exploration Limited, attention was devoted to means of reducing operating costs. One obvious method was to reduce or eliminate the costs of steel grinding media by employing some form of autogenous grinding. two pilot plant operations were carried out at the facilities of Lakefield Research of Canada Limited, in which autogenous grinding of Granduc ores was investigated. The results of these investigations led to the selection

Jan 1, 1972

By M. R. Paterson

Operational and economic factors tend to favor the application of continuous processes in preference to batch processes in the majority of mineral processing applications. In this paper, the requirement for a Continuous Elution Process is established and the development of a large-scale pilot plant is described. It is based on a Continuous Elution apparatus which has a number of special features. These are the subject of various patent applications. The apparatus is suitable for adaptation to the AARL, Zadra and other methods of elution. The performance of the Atmospheric Continuous Elution System (ACE) is concluded to have significant advantages over the batch process.

Jan 1, 1986

By Schebek, J. Warsen

"Data and information from sustainable development (SD) reports can be seen as a promising and easily accessible source for an Life Cycle Assessment (LCA), i.e. for generic Life Cycle Inventory (LCI) data in particular. The reliability and comparability of LCA results crucially depends on the quality of LCI data, that is defined by specific normative requirements. In parallel the GRI (Global Reporting Initiative) provides a set of guidance documents for enhancing the quality, rigor, and utility of SD reporting with specific reporting principles that address similar issues on a company level comparable to LCI data quality requirements on the process level. In order to assess the general suitability of the fundamental reporting principles for LCI data quality purposes selected reports from mining and minerals (M&M) sector are assessed within a detailed analysis."

Jan 1, 2005

By B. P. Boisen

INTRODUCTION Application Measurement of rock deformation is essential to stability and behavioral monitoring of underground openings. The difficulties of obtaining adequate sample distribution, density, and orientation can frequently be overcome by the use of single and multiple position borehole extensometers. In its simplest form, a borehole extensometer consists of an instrument head, usually anchored in the collar of a borehole, and a number of in-hole anchors, each of which is fixed in place at a known distance from the collar. As rock adjacent to the borehole deforms, the component parallel to the borehole direction causes a distance change between adjacent in-hole anchors, as well as a distance change between individual anchors and the instrument head. These changes are measured by means of a mechanical link (usually wire or rod) extending to the instrument head from each anchor. The resulting data can be used to compute the distribution, magnitude, rate, and acceleration of deformation in the material intersected by the extensometer's borehole. Wire Vs. Rod Extensometers Since the early 1960s myriad varieties of borehole extensometers have become available through the combination of various special features of two basic instruments, the wire and rod versions of borehole extensometers. Recent publications have recommended shallow depth limitations for wire extensometers, and favor rod extensometers for a broad range of borehole inclinations and depths. There are three main reasons for using a deep wire system: its cost effectiveness; the fact that tremendous depth means tremendous rod weight which will cause the rod to buckle or rub against the borehole or casing wall; and users' attitude and proper understanding of how to install and apply a wire-type extensometer. Here experience plays a big role. Over the years, many have learned the hard way that untensioned rod extensometers are simple and inherently inexpensive, but limited to vertical up holes where sensitivity is not influenced by friction between the rod elements and the borehole wall or protective conduit, the inertia of the rod elements, or the direction of the movement to be measured. In deep, horizontal, or inclined holes, and in instances where compressive as well as tensile strains or displacements are anticipated, tensioned rod or wire systems are preferred. System Components Borehole extensometers are made up of at least the following five principal components: the instrument head; the collar anchor assembly; the downhole system of anchors and rods or wires; the signal cable if the head is equipped for electronic readout; and the readout apparatus, whether mechanical or electronic. These components are shown in Fig. 1. Borehole Requirements Most extensometers are designed for installation in nominal 75 to 57-mm (3.0 to 2.25-in.) diam drill holes. Either a diamond drill or a percussion drill hole is satisfactory, provided the variation in drill-hole diameter is within the tolerance of the standard anchor design. The basic system may be modified for other hole diameters by changing the dimensions of the collar anchor and downhole anchor assemblies. Some instrument heads and collar anchor assemblies require enlarged borehole collars, though usually not over 150 mm (6 in.) for a depth of 1 m (3 ft). It is desirable, although not essential, that holes be free-draining. Holes must be clean and free of debris before installation. Depth/Orientation of Extensometer Boreholes Extensometers are designed to measure axial strain components in the instrumented drill hole. As the drill hole is axially deformed, the distances between individual downhole anchors and the instrument head change, as do the distances between adjacent anchors. The distance changes measured by a multiple position borehole extensometer, for example, are reduced to functions of time, hole depth, anchor position, or other parameters of significance in terms of the structure under investigation.

Jan 1, 1982

By R. D. Deister

The Buick concentrator represents state-of-the-art technology in automated digital process control operation utilizing a centralized computer. The process control strategies implemented at Buick are no longer new to the industry, but the successful application of these developments is still rather unique in North America. Productivity improvements, determined to be a direct result of the process control developments, are the primary topics of this paper. Emphasis is placed on metallurgical benefits including both lead and zinc recoveries; lead concentrate grade; and reductions realized in reagent consumptions, operating costs, and personnel. A detailed description of the concentrator, along with a history of the process control development and a more in-depth discussion of the control strategies implemented at Buick can be found in the references. (The Buick flowsheet is depicted in Fig. 1).

Jan 1, 1987

By E. Steel, V. S. Znamensky, A. Wylie

The asbestiform habit is most commonly developed in certain amphiboles and chrysotile, but other minerals also may crystallize with this unusual habit. The habit may be characterized by (1) a fibril structure, single or twinned crystals of very small widths (generally less than 0.5 pm), which have grown with a common fiber axis direction, but are disoriented in the other crystallographic directions; (2) anomalous optical properties, primarily parallel extinction; (3) unusual tensile strength; (4) high aspect ratio; and (51 flexibility. In addition, there is evidence to indicate that some amphibole asbestos may have unusual surface properties. ASBESTOS AND THE ASBESTIFORM HABIT Asbestos is defined as a group of highly fibrous silicate minerals that readily separate into long, thin, strong fibers of sufficient flexibility to be woven, are heat resistant and chemically inert, and possess a high electric insulation, and therefore are suitable for uses where in- combustible, nonconducting, or chemically resistant material is required (Gary, et al., 1974). The most common minerals that may occur with the asbestiform habit are chrysotile, grunerite (amosite], riebeckite (crocidolite), actinolite, anthophyllite, and tremolite; although the development of this habit among these minerals is rare. Other minerals, most notably other amphiboles, can occur in this habit, but no others have been mined commercially as asbestos. All asbestos is confined to metamorphic rocks, even though other habits of the amphiboles are common in igneous rocks. Slip fiber veins are the most common deposits (South African amosite, Canadian chrysotile, etc.), but mass fiber deposits also may occur such as California chrysotile or mountain leather. Field relations and experimental data support the hypothesis that metasomatism is the dominant process in the formation of asbestos fibers, amphibole as well as serpentine. The crystal habit of a mineral is the shape or form a crystal or aggregate of crystals take on during crystallization. The asbestiform habit has a number of characteristics that differentiate it from other habits. Chief among these is the fibril structure.Afibri1 is a single or twinned crystal with a very small width, generally less than 0.5 pm, and an extremely high aspect ratio; bundles of fibrils may have lengths reaching into the cm. Fibrils share a common crystal growth direction along the long axis of the fiber, but appear to be disoriented with respect to one another in the other crystallographic directions. The structure of the individual fibrils, and the organization of fibrils within a fiber may differ among the various types of asbestos. The fibril structure of asbestos is probably a factor in controlling a number of secondary properties that include high tensile strength, flexibility sufficient for weaving, and anomalous optical properties. The high tensile strength of asbestos is quite remarkable, exceeding that of the ordinary varieties by a thousand fold (Zoltai, 1978). In part, this may be attributed to the lack of defect on the fibril surfaces (Zoltai, 19781, but some contribution also must come from the existance of bundles and the nature of the ordering of and forces among the fibrils. The flexibility is not only enhanced by the fact that the fibrils may slip past one another, but by their small widths and extreme aspect ratios. However, structural defects parallel to the fiber axis also may contribute to this property. Among the common commercial asbestos types, the greatest flexibility is found in chrysotile and the least in grunerite asbestos (amosite), varying inversely with fibril thick- ness. In addition, at least for chrysotile, composition also may affect the flexibility of the fibers. Finally, most asbestos minerals are mono- clinic, but optically display parallel extinction (Heinrich, 1965, and Wylie, 1978). This also must be due, in part, to the ordering or lack of ordering of the fibrils. The fibril structure is probably a random

Jan 1, 1986

By Utku Gumus, Ertan Bostanci, Hanifi Copur, Ahmet Rüfai Bilgin, Ugur Altay

"Field observations on replacements of 12-inch constant cross-section double disc cutters in Tuzla Wastewater Tunnel excavated by an EPB TBM with 3.151 mm excavation diameter excavating hard rock are summarized. Cutter life is correlated to rock’s uniaxial compressive strength and Cerchar abrasivity index, and TBM operational parameters. Number of cutter replacements, average cutter replacement rates and types of cutter damages are summarized. The relationships between cutter life and rock properties and TBM operational parameters are analyzed by single variable regression method. Detailed analysis between chainages 1+200 and 1+982 km indicates that average cutter consumption rate is 35.7 m3/replacement (4.6 m/replacement). Cerchar abrasivity index and uniaxial compressive strength does not indicate any meaningful relationship with cutter life. Penetration per revolution and field specific energy might be used for predicting lives of constant cross-section double disc cutters. However, additional data is required to generalize the findings of this study. INTRODUCTION Cutter life / replacement and/or consumption rates in terms of cutter cost and replacement time loses is one of the most important parameters affecting excavation performance of mechanical excavators, especially of TBMs used very widely and equipped with usually disc cutters. Predicting cutter cost is a very important task in especially feasibility stage of tunneling projects. Basic parameters affecting cutter life can be classified into 3 general groups as geological and geotechnical, excavation machine (TBM) related, and operational parameters (Bilgin et al., 2013). The geological and geotechnical parameters are the most dominant ones among them. The machine related parameters should be arranged in accordance with the expected geological and geotechnical conditions for the best TBM excavation performance and minimum cost."

Jan 1, 2016

By Margreth Tadie, Chalwe Chibwe

Physicochemical properties of copper electrolytes are a strong fundamental consideration in electrodeposition processes during electro-purification and recovery of copper. Their influence extends to mass transfer as well as energy consumption during the electrodeposition process. In this study, the influence of electrolyte composition on electrolyte physicochemical properties was investigated to review the existing literature data. This review of data is considered necessary as more and more electrowinning models are being developed for process prediction and optimisation and a need of such data is required for accurate prediction of physicochemical properties. The major components of importance to the formation of smooth high-quality and high-purity copper cathodes at optimum current efficiency are considered the species in solution. These include Cu ions, Fe ions (major impurity), H2SO4, and a smoothing agent additive. A 5-factor, 2- and 3-level experimental design was employed to determine the effect of copper (35 and 45 g/l), sulphuric acid (160 and 180 g/l), iron (1, 3, and 6 g/l), polyacrylamide additive (2, 5, and 10 mg/ l), and temperature (45 and 55 °C) on electrolyte density, conductivity, and the diffusion coefficient in synthetic copper electrowinning electrolytes. The major species in a copper electrowinning electrolyte are found to be the most relevant for prediction of physicochemical properties. These results indicate that relatively simple empirical models are sufficient for modelling of the electrolyte domain in electrowinning, without the need for the generation of vast amounts of complex experimental data.

Feb 1, 2021

By Drupad B. Desai

Baltimore Region Rapid Transit System project final design began in 1973. The Section A of the planned Phase I is scheduled to go into revenue service in late 1982. The subway line structures include earth tunnels, rock tunnels and cut-and-cover structures. Final designs were performed by both the DMJM/KE staff and by outside subconsultants. This paper deals with Section A of the program. (Fig. 1.) The overall program cost for Section A is estimated to be $721 million. The cost for construction and owner furnished equipment is estimated to be $600 million, including contingency and escalation to time of construction. The remaining amounts are for right-of-way, design, construction management and agency (MTA) costs. The Section A line structures, including station lengths, are divided as shown in Table 1. [ ]

Jan 1, 1979

By R. H. Snow

Although industrial size reduction methods have an energy efficiency of only about 1 percent, methods of size reduction have not changed much for many years. One reason for slow progress has been the oversimple viewpoint that a single law should exist to relate size reduction to energy input. Modern simulation methods decompose the grinding process into a grinding rate function (selection function) and a breakage function. The breakage function is difficult to measure, and it usually requires tracers if it is determined from milling experiments. Prediction of breakage functions from basic principles is one objective of this paper. In this study we focus attention not on the gross energy input to the experiment, but on the spatial distribution of stress energy within the particle. We are led to this viewpoint by experimental observations of a few previous investigators (Bergstrom2, Rumpf3, Axelson4) and our own observations. Oka and Hiramatsu recently used their calculations of stress within particles for prediction of breakage, but again they tried to correlate the size of the fragments with the total stress energy, rather than the approach we propose. We assume that the stress energy is stored in the interior of the particle as the load is increased, until the particle breaks. We assume that each element of the particle breaks into fragments of a mean size that depends on the locally-stored stress energy. The size distribution of fragments is the computed from maps of the stress-

Jan 1, 1972

By R. L. Hills

America's industry uses about 44% of the total energy consumed by the nation directly as fuel burned in industrial plants or indirectly as fuel burned by utilities to provide electric power. In addition, industry requires raw materials or feed stocks derived from fuel sources or having fuel value. This represents about 11% of total U. S. energy consumption, bringing industry's portion to about 55%. Adding that portion of energy consumption required by the transportation sector to move raw materials, intermediates, and finished products, the total energy impact of industry approaches 213 of total U. S. consumption. It is obvious that American industry has the largest share in the task of balancing energy demand and supply. What are we going to do? -- We must increase the supply of energy and increase the beneficial results obtained from each unit expended. Both avenues, unfortunately, are limited in extent and speed. Increases in supply cannot occur without drastic and permanent increases in cost. These increases in cost are un- desirable and inflationary but do provide incentive for the rational businessman to expend the effort and money required to improve the effectiveness of energy in industry.

Jan 1, 1975

By P. van der Veen

There are two key reasons for this presentation: - Sustainability - Improving the economic, environmental and social impact of mining. As I will discuss in my presentation we see sustainability throughout the mine life cycle as critical for successful mine development - that is the mine makes a successful contribution to economic development and poverty alleviation for the host community and host country and at the same time the mine is a successful investment for the investor. - Knowledge Sharing ? The World Bank is not only a development bank, but also a ?knowledge bank?. One of our key functions is the dissemination of usable information and knowledge. We are here not only to share our experience but to learn from your experience as well ? two reasons that fit clearly with the mandate of the World Bank Group.

Jan 1, 2003

By James P. Rider

Significant advances in longwall mining technology and equipment have occurred over the last decade by the late 1990s, longwall mine output accounted for 40% of all underground output in the U.S. and today longwall mines account for approximately 50% of coal produced underground in the United states. A 51% increase in average shift production rates has occurred over the last 15 years. this increased longwall productivity has meant that far more dust is being produced and controlling respirable coal dust presents an ongoing challenge for coal mine operators the National Institute for Occupational safety and Health (NIOSH) conducted a series of benchmark surveys at longwall operations across the country to identify current operating practices and the types of controls being used. Gravimetric and instantaneous dust sampling was completed to quantify the dust levels generated by major sources on the longwall section and to identify different control technologies in use today substantial reductions in dust levels were realized at sampling locations on the face when compared with ongwall surveys conducted in the 1990s results from the underground dust surveys and current longwall dust control technology and operating practices will be discussed. Mining Engineering, 2011, Vol. 63, No. 9, pp. 74-80. Official publication of the society for mining, metallurgy and exploration, Inc.

Jan 1, 2011

By R. Addison

This is the story of the Carlton Mill. But first-a little geography. For those who do not know where the Carlton Mill is, or, perhaps, have only a vague idea, its location is indicated in Figure 1. The plant is situated on the road between the two old mining towns of Cripple Creek and Victor, 10 the west of Colorado Springs. From Denver, it's about 110 miles by road. The story of the Carlton Mill began with the discovery of gold at Cripple Creek in 1890. This discovery set off a major boom such that, by the turn of the century, there were 450 separate operating mines in the district. Gold production boomed early and declined rather rapidly as indicated by the graph in Figure 2. Significant factors affecting production are shown on the graph-the raising of the gold price in 1934 from $20.67 to $35.00 per ounce and the government executive order L-208 in 1942 requiring the closure of all gold mines.

Jan 1, 1983

By A. C. T. Bigg, A. F. Colombo, A. R. MacPherson

The step-by-step study of the Stronsay ores follows the testwork through the initial determination of Bond Rod and Ball mill work indices, the MacPherson Autogenous work indices and the production of a preliminary flowsheet. These results are then used to design a pilot plant program to test the effectiveness of fully autogenous primary and secondary grinding and to determine the feasibility of controlling feed rate by the use of variable speed mill drive and/or varying the mill load. A final flowsheet is recommended with mill sizes and power requirements.

Jan 1, 1992

By William C. Howe

This paper describes the technical status of the atmospheric pressure fluidized bed combustion (AFBC) process for utility steam generation. Major areas where AFBC development work is needed are discussed. Various approaches to solving these key issues are identified and the ongoing research and development programs addressing the key development areas are described. Other significant programs pertaining to the development of AFBC for utility steam generation are also discussed and needs for future work identified.

Jan 1, 1978

By D. Brandt

The Dos Pobres Mine is a copper oxide heap-leach operation located near Safford, AZ. Mine production is 163 kt/d (180,000 stpd) with a stripping ratio of 2:1. During the startup phase of the mine, the required fragmentation size was easy to achieve as the ore was highly weathered and fractured near the surface. As the mine depth increased, the proper fragmentation size became harder to achieve due to less weathering and different rock types. Because copper recovery increases as crusher product size decreases, achieving the appropriate product size at the crusher is the operating priority. The engineering department began a project to improve fragmentation through blasting and thus increase throughput in the crushing system. It soon became clear that input from other departments was going to be required to make this a safe and economical project. Therefore, the crush and convey and ore control departments worked together to evaluate all available data on blast patterns and explosive loads and tracked performance and results. Using image analysis, drill energy index and databases, improved fragmentation size has been achieved and results have been verified while controlling costs.

Jan 1, 2011

By Robert J. Gorney

This paper deals with the actual application of a direct digital control to simple as well as complex industrial process control loops, Fundamental descriptions of preliminary research and design are described briefly, as is the development of the present day controller and control computer. The results and effects of direct digital control in various types of single and cascaded loops as opposed to the use of conventional controls are discussed. Computer supervision of a process and control override are taken into account, in addition to methods of short and long term plant economic optimization.

Jan 1, 1965

By B. Stewart

Recent ore pass failures have underlined the need for improved designs, standards, structural monitoring methods, and better hang up prevention and removal techniques. Researchers at the Spokane Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) are investigating methods to improve safety during transport of ore in ore passes. Design criteria and hang-up prevention and remediation strategies involve studies of the effects of static and dynamic ore and waste rock loads on chutes, walls, gates, and support structures. Particle flow analysis methods were used to simulate the response of various ore pass designs to a wide range of ore loading conditions. A full-scale mock-up of actual ore pass and chute assemblies was duplicated and tested for load response. Data from a particle flow code and the mock-ups were com-pared. Loads on an active ore pass chute were measured.

Jan 1, 1998

By Tyler Acorn, Brandon Wilson, Jeff Boisvert

Scenario-level uncertainty is a representation of large-scale differences encountered when considering ultimate mining pits optimized over various subsets of stochastic realizations. Accounting for scenario-level uncertainty allows mine plans to be assessed against several probabilistic subsurface interpretations. Scenario-level uncertainty is found through clustering stochastic geostatistical realizations and optimizing final pits across the realizations in each cluster. Where these pits are geometrically different, plans for each scenario differ. Knowing these differences allows the value of each planning alternative to be assessed based on the value and relative probability of each scenario. These results also facilitate the use of formal decision-making frameworks for planning, leading to optimization that better represents the full statistical characterization of the deposit. An example utilizing this approach evaluates both infrastructure placement and drilling program requirements. In both cases, scenario-level uncertainty improves initial plans by limiting opportunity costs and identifying additional potential.