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By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of topdown managerial practices: reductions in production volume, employee layoffs, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefits are often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost-cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization's various constituencies with this direction, and motivate and inspire the organization. Cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2002

By R. V. Ramani, K. V. K. Prasad, M. Swaminathan

Engineering design involves, in addition to numerical calculations, considerable amount of expertise and judgement. The expertise and judgement is required to conceptualize and idealize the problem, select a suitable mathematical model for the problem and to interpret the model results in terms of stipulated design constraints. In recent years, knowledge based systems (KBS) have provided the capability to integrate the qualitative experiential and expert knowledge with the quantitative knowledge for improved analysis and design of systems. A possible KBS architecture for mine ventilation system design was discussed by Ramani and Prasad (1987). The expert system (ES) component of the KBS supports the analysis and interpretation phases of the ventilation design process with an algorithmic program used for the solution of alternate designs. The purpose of this paper is to discuss the data and knowledge needs for developing such a system and a formal means of their representation on the computer. A number of ES shells were evaluated to explore possible development and delivery environments for the system. A brief summary of this evaluation is also provided.

Jan 1, 1989

By B. A. Osei

Research to evaluate possible metrics for predicting dredgeability of compact aggregates, by hydraulically actuated clamshell dredges, shows work done by the pistons as a viable metric. Analysis of field data shows that there is a low, positive, correlation between cycle time (CT) and work done. If this correlation exists, then CT has to be considered an independent variable affecting work done during dredgeability assessment. Further research is required to elucidate the relationship between CT and work done during dredging. The objective of this paper is to test the hypothesis that work done during dredging increases with increasing CT. Kinematics and dynamics of the hydraulic clamshell were modeled and implemented in Simulink® in MATLAB. The model was validated using field data. The model was then used to test the research hypothesis. The results show that work done increases with increasing CT. This work confirms that work done during dredging increases with increasing CT. This result indicates that though an operator can increase the CT to deal with difficult digging, inputting unduly high CTs results in higher energy consumption during dredging.

Jan 1, 2011

By Sean E. Armstrong, Deepak Malhotra

The current trend in gold ore processing is the development of lower grade or highly refractory deposits. The perplexity of treating low grade oxidized ores has been adequately addressed by heap leach technology. However, refractory gold ores are very difficult to positively characterize the gold association within the mineral matrix. Gold accompanied with refractory sulfitlc or carbonaceous mineralization can often be sub­micron In size and occur interstitially. Mineralogical examination of these ores Is difficult, expensive, and occasionally Inconclusive. Hence, the metallurgist Is given little information for the selection of processing alternatives. The purpose of this paper Is to demonstrate the use of diagnostic leach procedures to assist the metallurgist' s decision-making process to solve some of these problems. By sequentially liberating and/or leaching gold associated with specific minerals, the amount of recoverable gold in each stage can be determined. Through careful interpretation of the results obtained by diagnostic leaching, the metallurgist can devise a flowsheet for treating the ore or solve a problem at an existing plant

Jan 1, 1992

By John T. Crawford

Open pit limit analysis techniques of various types have been utilized for many years to design ultimate pit surfaces. In the last 15 years there have been many advances in the development of sophisticated computer methods to aid this process. The extensive capability of the computer has led to multiple alternative approaches to problem solving. Computerized open pit limit analysis methods can be applied to a broad scope of long-range and intermediate-range mine planning and design questions. A single computer run develops a pit design from a set of data. A set of nonsequential runs is used to evaluate changes in pit slopes, property restraints, and mineral model variables. Ore reserve economic sensitivity and intermediate-range mining plans can be developed using sequential computer runs. Present value methods are incorporated by using iterative sequential techniques. Multiple ore processes, dump leaching credits, and the trade-off between open pit and underground mining can also be handled. Many of the applications described are representative of current practice. The remainder are suggested extensions.

Jan 1, 1979

By Sii Smith-Gruner

Blasthole drilling by todays standards is not a mature operation. In most mining appli¬cations, the blasthole drill rig is the least understood piece of machinery. Draglines, mining shovels, and haulage trucks may have more charisma, but the entire mining process starts with the drilling of blastholes to facilitate removal of the overburden and/or the primary material being mined. There are two (2) principal drilling methods them being rotary and percussion. In certain situations, percussion drilling is the most practical method, but for most applications, rotary drilling using the rotary tricone bit is the common and accepted drilling technique. While the drilling rig is on the surface and quite visible to everyone, it is really the object at the end of the drill pipe, the tricone bit, that is doing the work and drilling the hole. The rig supplies power to the bit and air to clean the hole. In addition, it must be capable of providing certain other functions and should be properly outfitted to adequately support the rotary tricone bit.

Jan 1, 1988

By Neville T. Moxen, Stuart K. Nicol, Malcolm D. Engel

Ion flotation is a process in which ions of interest are complexed with a suitable surfactant molecule. A dilute solution containing these complexes is then aerated, under which circumstance the surface-active complex concentrates at the air-water interface and is transferred to a froth. The present work describes some of the phenomenology of this process and experimental work leading up to the design and use of a pilot scale laboratory facility. Early experiments suggest that selective recovery of gold can be obtained in a manner at least equivalent to conventional CIP processing at low capital cost. Under favourable conditions, upgrade ratios of gold ions of the order of 180: l have been achieved from reclaimed residue dam water with as low an initial gold level as 0.2ppm. Successful development of countercurrent ion flotation for concentrating solids-free gold solutions may offer a lower cost alternative to existing gold ore processing technologies, or in more secondary applications such as concentrating dilute gold solutions or heap leach runoff. The technology may also have more generalised applications to other heavy metal processing.

Jan 1, 1990

By James L. Whitlock, Amy E. James

During the past twenty years, numerous advances have been made in the technologies used to pretreat sulfidic refractory gold ores. These advances have included improved equipment design, increased gold recoveries, and reduced operating and capital costs. More recently, treatment of refractory gold ores has primarily been accomplished by pressure oxidation (POX), roasting, chlorine oxidation, or biooxidation. In addition to improving the time-proven processes of pressure oxidation and roasting, new and innovative approaches to biooxidation pretreatment of both concentrates and whole ores have been developed. Selecting the appropriate biooxidation technology depends on the nature of the refractoriness in the ore, economic gold recovery, plant design operating parameters (such as desired tonnage), site climatic conditions, and operating and capital costs, as well as several other deciding factors. The objective of this paper is to outline the biooxidation processes and technologies currently available for the recovery of gold from refractory sulfidic ores, to discuss the critical factors that affect plant design and operation, and to provide the metallurgist with a practical guide to choosing the appropriate biooxidation technology for a particular ore or concentrate.

Jan 1, 1999

By Gary Johnson, Bill Mackenzie

The Paddy's Flat plant of Dominion Mining Limited was commissioned in March 1988 with a design throughput rate of 700,000 tpa. The plant now treats ore at an annualised rate of over 2,000,000 tpa. The only major capital improvement to the plant has been the addition of a pebble crushing circuit. Whilst significant changes in the average hardness of the ore being fed to the plant have obviously occurred, a number of processing innovations have been necessary to enable these throughputs to be maintained. The treatment of ore types with a wide variety of physical properties has been a feature of the operation of the Paddy's Flat plant. The leaching characteristics of the ores are relatively straight forward, and it has been possible to considerably enhance the rate of gold extraction from the ore. Reserves of soft surface ore have been increased which has created the opportunity to improve the profitability of the operation by increasing throughput to considerably above the design level, without having to increase the capital investment in the plant.

Jan 1, 1992

By V. I. Lakshmanan, Chris Dodson

Refractory gold ores or concentrates are pretreated in general by physical, chemical and biological oxidative pretreatment processes prior to cyanidation for the economic recovery of gold. The thermal treatment processes generally include fluid bed pro­cessing(!>, chemical with pressure<') or atmospheric (Caro's< ·'>, 3 Nitrox1')) pretreatment leaching and physical with ultrafine grinding!"). Roasting and aqueous pressure oxidation pretreat­ment methods have several commercial applications (Homestake, Barrick) and biological oxidation methods have recently found industrial applications in Africa. The roast pretreatment methods to treat refractory sulphide ores or concentrates transform iron sulphides generally to a porous iron oxide matrix assisting the lixiviant cyanide to effectively diffuse the calcine for cyanidation and hence with improved gold recovery. Jha and Kramer<') made an extensive review of roasting chemistty and practice to tt·eat refract01y gold ores. Industrially two stage pretreatment roasting is generally employed. During the first stage roasting is carried out under oxygen deficiency conditions to provide a low arsenic calcine, mainly magnetite and in the second stage magnetite is trans­formed to haematite under oxidizing conditions.

Jan 1, 1998

By A. Anderson, G. May, C. Kubank, S. Meik

The Kori Kollo operation is owned by Empresa Minera Inti Raymi S.A., a Bolivian mining company. Inti Raymi is an eighty-five percent owned subsidiary of Battle Mountain Gold Company (BMGC). The remainder of Inti Raymi is held by Zeland Mines S.A., a Bolivian mining company. The project is located near the village of La Joya, approximately 220 km south of La Paz, and 40 km north west of Oruro on the Bolivian altiplano. Inti Raymi started a heap leach operation in 1985. By 1988, following several expansions, 4,000 tonnes per day of oxide ore were being treated. At this time drilling was started to delineate the larger sulfide orebody. A feasibility study for the development of this deposit was completed in 1990, and following project approval, the engineering design was started later that year. During this period orders were placed for the major items of mechanical equipment. In July 1991, Minproc Engineers Inc. was awarded a firm price contract to design and construct the 14,000 tonne per day sulfide ore process facility.

Jan 1, 1993

By Jean-Michel Rendu

Electronic data processing&apos; is becoming a necessary part of all large mining operations. Accountants, geologists, mining engineers, samplers, and truck drivers are needed to operate a mine. So appear to be systems analysts, computer operators, and software engineers. Trucks, loaders, and drills must be used to extract useful material from the ground. So must be mainframe and microcomputers, plotters, digitizers, and computer terminals. The papers presented in this section describe experience gained in Europe, Australia, and North and South America. The mining and data processing environments and the size of the companies vary significantly, but the conclusions drawn are often strikingly similar. Common answers to often-asked questions can be summarized as follows: - Why invest in data processing? The main reason is that information systems can supply accurate and timely information for better decision-making. Other reasons are mentioned including, to speed-up the processing of large volumes of information, to perform operations which cannot be performed manually, or to reduce costs. But all of these reasons appear ancillary to that of supplying accurate and timely information.

Jan 1, 1989

By A. Kyriazopoulos

Quarrying is an important activity as it significantly contributes to the economy of a country. This activity presupposes the destruction of the natural vegetation, the removal of the surface soil and deposition of inactive materials. The lack of fertile soil in these disturbed areas is usually a problem for the plant cover establishment. The purpose of this study was to investigate the potential of the establishment of ten herbaceous plant species to inactive quarries with the use of limited amount of fertile soil. The research was conducted in the area of the quarries of the cement manufacture company ?TITAN?, Thessaloniki, Greece. On a terrace of one of the quarries, a 2 cm layer of fertile soil was placed. In early October 2007, the herbaceous species, Lolium rigidum, Festuca arundinacea, Bromus inermis, Agropyrum desertorum, Phalaris aquatica, Dactylis glomerata, Medicago sativa, Medicago lupulina, Sanguisorba minor and Phacelia tanacetifolia, were seeded separately. The first results indicated that among the tested species Dactylis glomerata, Festuca arundinacea and Phacelia tanacetifolia had the highest establishment capability.

Jan 1, 2008

By C. J. Pritchard

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyure¬thane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft - are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners&apos; safety.

Jan 1, 1990

By Thomas E. McNider

On July 20, 1990, a Spontaneous Combustion Control Plan was approved by MSHA for Jim Walter Resources, Inc. No. 5 Mine. The mine operated under the plan for twenty-nine shifts before MSHA revoked the plan. A total of fifty-five seals were constructed during the process of implementing the plan. The major difficulty in applying the control concept resulted from problems controlling leakage at the numerous seals. The number of seals was a direct consequence of attempting to merge the traditional bleeder system, used in all the Blue Creek Mines, with the bleederless system Jim Walter Resources proposed as a means of controlling the spontaneous combustion hazard. This paper discusses Jim Walter Resources experience with spontaneous combustion control and the new safety standard which applies to underground coal mines that demonstrate a history of spontaneous combustion and how this standard would apply to our No. 5 Mine. The new Ventilation Standards were published in the Federal Register on May 15, 1992, and scheduled to go into effect August 16, 1992.

Jan 1, 1993

In order to analyze and quantify distinct environmental properties in the vicinity of sites, the Site-Specific Natural Resources Information System (SARIS) has been developed based on a Geographic Information System (GIS). SARIS is one of the fundamental databases of a collaborative research program aiming at the resource orientated analysis of metallic raw material flows with aluminum and copper serving as exemplary case studies. The spatial database incorporates all present production sites of ore extraction, refining and smelting. Environmental data for each location were derived from global digital survey data covering land cover, soils, morphology, climate, topography and population density. The main application of this database is the characterization of environmental safeguard objects, which may be affected by the activity of concern. This site-specific environmental impact assessment is used to determine the relevance of environmental issues based on the distribution pattern of sites in a global framework. The derived results are used to suggest a tailored indicator approach to measure progress and performance of industrial developments relative to the predetermined site-specific conditions.

Jan 1, 2003

By Martin H. Col, Thomas W. Steele

The ability to make a good profit in the mining industry is becoming more and more difficult. Typically, grades are lower, sites are more remote, and environmental restrictions are getting tighter than ever before. While the price of the materials P.roduced, such as gold and silver, have stayed flat or declined, the external costs (goods and services) have increased. Increasingly difficult environmental restrictions have increased the lime and costs of develoJ?in9 new deposits, while often placing restrictions on a mme s production rate. Environmental costs for mine closure and site reclamation also make it very difficult to show a long-term profit while mining. Typically, the answer to this cost/price squeeze has been technological innovation. The whole concept of heap leaching low-grade gold ore is one innovation that provided some very goocf profits to the mining companies; but, today, those profits are being eroded by the continuing cost/ price squeeze. This paper will discuss material handling in a heap leach stacking operation and the alternatives of trucks, grasshopper conveY.or systems and mobile conveyor systems.

Jan 1, 1992

By Robert H. Merrill

The art of rock mechanics has been applied in various forms since early man first used caves for housing and fashioned rocks into weapons, tools, and utensils. The development of the science of rock mechanics has occurred in a slow but steady fashion due to the complexity of the materials, geometries, and loading conditions involved. It encompasses a great diversity of topics ranging from techniques for rock destruction to those required for rock strengthening or support, and as such enters daily into the life of the mining engineer. Although today rock mechanics can be confidently used in competent geologic structures, the degree of confidence diminishes as the structures become more complex and the number of geologic defects become more numerous. Even so, the principles still give a better estimate of the structural behavior of underground openings than ever before, and the persons responsible for design and control draw freely and often on the subject. For the most part, the civil engineer will spend more time and money on pre-design than the mining engi-

Jan 1, 1982

By D. S. Bird

Kennecott Utah Copper began a modernization program in 1986 that was aimed at expanding and updating mining and ore process facilities at the company’s Bingham Canyon copper mine and concentrator near Salt Lake City, UT. Major components of the project included installation of an in-pit crusher, a transfer conveying system and a new ore concentrator with a design capacity of 70 kt/d (77,000 stpd). The Copperton concentrator was commissioned in February 1988. The grinding circuit is one of its principal features. It consists of three identical lines, each with a 10.4-m- (34-ft-) diam x 4.6-m- (15-ft-) long semiautogenous grinding (SAG) mill and two 5.5-m- (18-ft-) diam x 8.6- (28-ft-) long ball mills. The SAG mills are driven by two 4.5-MW (each) (6000-hp) variable- speed dc motors through a clutch-pinion gear-ring gear assembly. The ball mills are driven by 4.1-MW (5500-hp) synchronous motors coupled through a typical clutch-pinion gear-ring gear system.

Jan 1, 1995

By James J. Snodgrass, David E. Siskind

The Bureau of Mines investigated the effects of vibrations from underground blasting in four rock types to define blast parameters that affect vibration amplitudes and to establish means of predicting expected vibration levels. Previous studies of surface blasting indicated that charge weight per delay period had a major influence on vibration amplitudes. Dividing the distance from the blast by the square root of the charge weight scaled the effect of various charge weights, however, and allowed vibration data for a particular site to be represented by a propagation equation of the form v = K(D/W ½ )-n (1) where v = particle velocity, D = distance from the blast, W = maximum charge weight per delay period, and K and n = empirically determined site constants. For square-root scaling, particle velocity and acceleration data from the underground sites appear to follow a similar propagation law. The subsurface data are in good agreement with those of the surface studies and provide a basis for engineering estimates of vibration amplitudes in many different rock types.

Jan 1, 1974