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By C. L. Lin

A PC image-based on-line coarse particle size analyzer has been developed to measure particle size distributions under plant situations where overlapped particles are being transported on a moving belt conveyor. Although previous testing had shown satisfactory performance of this image-based system for separated particle size measurements (the non-overlapped case), it was necessary to modify original algorithms in order to solve the overlap problem and make the system suitable for plant operations. On-site testing has been conducted at a large copper concentrator in the southwestern U.S. for further investigation of the overlap problem.

Jan 1, 1995

By Wayne D. Gould

The Cities Service Company's Pinto Valley mine and concentrator lie about 6 miles west of the town of Miami, Arizona at an elevation of approximately 4,000 feet above sea level. The concentrator started its first ballmill in July 74 and all six were available by November. Every effort was made to reduce capital costs, consequently, each unit process was studied critically to eliminate excess capital costs without loss of efficiency. Equipment selection was made on the basis of proven dependability and operating costs rather than on low bids. The result is a very workable plant with some important innovations. The concentrator is nominally 40,000 tons per day. The flowsheet is typical with 3 stage crushing, single stage closed circuit grinding, flotation, regrinding of rougher concentrate and cleaning of the rougher concentrate. The major equipment list is: 1 60 x 89 Traylor Primary Crusher 1 84" x 20' Stevens-Adamson Apron Feeder 3 7' x 16' Double Deck Tyler Screen 3 7' Nordberg Standard Crushers 6 8' x 20' Tyler Screens

Jan 1, 1975

By Jacob D. Baker

Sulphur dioxide is a versatile gas which has many uses throughout Pulp & Paper, Chemical, specialty Chemical, Mining and other industries. During recent years, S0 2 consumption and distribution patterns have resulted in renewed interests for liquid S0 2 and on site gaseous S02 manufacturing facilities. one relatively new use for S0 2 in the Mining Industry is its use for cyanide detoxification. Our purpose in this paper is to describe the process steps, economics and general technical features of so 2 gas generation using a Jet Type sulphur Burning System.

Jan 1, 1991

By W. S. Weldon

The use of spiral separators for the beneficiation of fine coal typically in the size range -2+0.1mm is now well established process technology. Developments during the mid 1980's resulted in the production of cost effective, efficient large diameter coal spiral separators. Recent developments and research have been geared to optimize metallurgical performance, materials handling and equipment geometry of large diameter coal spiral separators.

Jan 1, 1997

By Jim W. Rosteck, Anthony Del Vescovo

In December of 1992, the City of New York, Department of Environmental Protection, solicited bids for Contract 543B. The low bidder was a joint venture of Schiavone Construction Co., Inc. and the J. F. Shea Co., Inc. When completed, the project provides a 4.88 meter diameter water tunnel 8,840 meters long. This paper presents a case history of the equipment and construction methods utilized for this, the first portion of the New York City Water Tunnel constructed by use of a tunnel boring machine.

Jan 1, 1997

By K. V. S. Sastry

Pelletization, sintering, and pressure compaction are the most common methods used to agglomerate ore concentrates. Over the last 20 years agglomeration has grown enormously in popularity and has become a standard unit operation in the nonferrous, cement, fertilizer, and ceramic industries. However, it is in the processing of iron ores and the preparation of blast furnace feed that agglomeration is used most and its application has grown fastest (Ball, et al., 1973; and Sastry, 1977). This chapter deals with an account of the current practices and future trends in the application of computers relative to an overview of the process design and engineering considerations of the unit operation of agglomeration.

Jan 1, 1979

By K. Kuhnhenn, G. Prommersberger

General aspects In Germany, swelling rock is mostly found in the keuper formation. Keuper is a sedimentary rock formation of varying composition. It mostly consists of fine or medium layers of clay/silt/marl/dolomite stone with intercalations of gypsum or anhydrite in strips or nodes. After disintegration of the top layers and tectonical incidents, the gypsum level, i.e. the upper [ ]

Jan 1, 1989

By M. Sears, G. S. Esterhuizen, Z. Khademian

According to the 2010-2019 Mine Safety and Health Administration (MSHA) accident report database, 91% of reported ground control accidents in U.S. longwall mines were caused by roof instability. Gateroads are subject to significant changes in loading conditions from the development to the longwall abutment loading phases. When combined with thinly bedded shale roof, found in many U.S. longwall coal mines, the design of efficient roof support becomes challenging. In previous work, the Bonded Block Method (BBM) modeling of roof by UDEC was validated against field extensometer measurements in a longwall gateroad entry roof at a 180-m depth of cover. The BBM was shown as capable of capturing delamination and buckling of shale roof, one of the main roof instability mechanisms in longwall mines. This paper presents the recent findings on the roof-support interaction using BBM models of the same longwall entry. The effects of cable bolts, roof bolt density, and strap support on potential roof instability are studied. These types of studies are difficult and costly to conduct in an operating mine. Results show how the contribution of bolts, straps, and cable bolts can be quantified using the BBM models. The study demonstrates the potential for BBM numerical models to help understand the complex roof and support system interactions and to assist with optimizing gateroad support systems.

Feb 1, 2023

By R. R. Klimpel

The efficiencies of plant scale comminution processes are often evaluated by various indices that are calculated and/or measured somewhat independent of the performance of any associated downstream froth flotation processes. In order to compare some specific comminution factors such as energy utilization, media consumption, equipment utilization time, etc. comparisons of comminution efficiency independent of flotation behavior are appropriate. However, as more and more detailed plant level information is gathered on the joint and highly interactive nature of comminution and froth flotation, it is becoming increasingly obvious that knowing and using simple efficiency indices are not enough. What is needed are more performance related measures of the efficiencies of the combined size reduction -froth flotation system for effective plant level economic optimization to occur. The purpose of this paper is to present some examples of important interactions that influence the joint efficiencies of size reduction and froth flotation processes.

Jan 1, 1998

By Suprakash Gupta, Pawan Kumar Yadav, Deepak Kumar, Debasis Jana

Draglines are extensively used in Indian mines. A dragline has more than hundreds of components, and it is complex in design. This study involves the evaluation of the reliability of a draglines system using a Bayesian network (BN) model mapped from a fault tree. Based on the BN inference, the reliability estimation, the diagnosis, and the sensitivity analysis are performed. In this paper, the overall reliability of the dragline is estimated as well as the contribution of the subsystems or components in the overall reliability evaluation is presented. The results showed that the three subsystems of the dragline, namely, the dragging mechanism, electrical auxiliary subsystem, and swing mechanism, have the lowest reliability (82.17%, 87.98%, and 91.30%, respectively) after an hour of operation. The overall reliability at the first hour of machine operation is estimated to be 62.03%. The study may provide a reference for future work related to the dragline machine’s reliability design and maintenance.

Jan 14, 2023

By M. Shriwas, F. Calizaya

"Recirculation is prohibited in many coal mining countries because of the fear that the re-use of return air would allow the build-up of air contaminants at the workings. The incorrect design and location of a booster fan in any ventilation network can create unsafe condition due to recirculation. The current approach to investigating recirculation using simulation software requires manual effort which becomes tedious in a complex and a large network. An algorithm-based C++ program was designed to detect the recirculation in a booster fan ventilation networks. This program needed an input file prepared from output file generated by any ventilation simulator. This program created an output file for recirculation. This program demonstrated the strong capability to detect the recirculation in a sample network and a coal mine ventilation network. The outcomes of this program were documented in this paper. INTRODUCTION The proper design and location of booster fans eliminate the safety hazards associated with high main fan pressure. Conversely, the incorrect design of booster fans in any ventilation network can create unsafe conditions due to uncontrolled recirculation. The proper utilization of a booster fan derives benefits to reduce the main fan pressure, leakage, and consequently ventilation cost especially with high resistance network due to deep and extensive working area in a mine. However installation of booster fan may create uncontrolled recirculation, if it is not sized and located properly with respect to main fan. Recirculation is prohibited in many coal mining countries because of the fear that the reuse of return air would allow the build-up of air contaminants at the workings. Therefore, it is imperative to check the recirculation while designing and operating booster fan for a ventilation network. This paper deals with an algorithm based C++ program to detect the recirculation in a booster fan ventilation networks. This program was implemented to detect the recirculation in a sample network and a coal mine network. STATEMENT OF PROBLEM The currently available ventilation simulation programs do not give much information about recirculation for the generated solution (fan pressures). The current approach to investigating recirculation using simulation software requires manual effort, i.e., traversing from node to node in the output network by the simulator while keeping tracks of all the nodes that form recirculation paths. This is an easy task in a simple ventilation network, but it becomes tedious and sometimes very confusing in a complex and large network. Moreover, the presence of multiple recirculation paths makes the manual effort more complex and difficult, especially in separating multiple loops that are connected together. Thus, there is a need for a more efficient program that will detect and quantify the recirculation efficiently, for the generated fan pressures. A program is developed to detect the recirculation(s) in a network."

Jan 1, 2015

By Eric Sitorus, Septian Prahastudhi, Roy William, Wieda Azani

In July 2020, massive slope failure occurred in the southeast corner Grasberg open pit. This was the final episode in the breakthrough of Production Block 2 South (PB2S) of the Grasberg Block Cave to connect to the surface. This breakthrough had been rapidly evolving during the first half of 2020 and occurred as expected with no adverse impacts to safety or operations. To manage and safeguard the exposure to the workforce and operations, numerous hazards were identified and anticipated. The failure of the sill pillar between the open pit and PB2S cave was identified as the main area of interest and was closely watched during the failure process. This paper reviews the systematic approach developed to convert monitoring data into information around the collapse of the GBC PB2S cave sill pillar. The data that was interpreted consisted of micro-seismic, piezometric, ground-based radar and observational inspections. Geological structures on the boundary of the PB2S cave were clearly involved in the breakthrough process. As the cave propagation reached these structures and triggered instability, the resulting acceleration and breakdown were clearly shown by IBIS radar units associated with high movement in the slope. The focus of this paper is on the evolution of changes seen in the micro-seismic data and how it was used to understand the rapidly changing conditions of the sill pillar. The seismic parameters evaluated were event distribution, Es/Ep value, and the seismic moment tensor inversion. The changes of breakthrough indication seen in these parameters were substantiated by Shear Wave Splitting (SWS) analysis that showed a close correlation with the fractured zone above the PB2S cave as indicated by the increasing anisotropy.

Jan 1, 2022

By P. M. Hawley

In April 1975 Kaiser Steel Corporation and the United States' Department of Energy entered into a cost-sharing agreement for the demonstration of shield-type longwall supports on three consecutive longwall panels at Kaiser's York Canyon' Mine in New Mexico. Under this agreement the Department of Energy supplied 117 Hemscheidt 320 HSL caliper-type shield supports and hydraulic pumps for the duration of the demonstration. The purpose of the demonstration was to educate the U.S. coal mining industry as to the benefits in production, productivity, health and safety, and increased coal extraction afforded by shield-type longwall mining systems and to provide the industry with a working model. A detailed description of this demonstration is given in U.S. Department of Energy Publication No. DOE/ET/12530-T1, entitled "Demonstration of Shield-Type Longwall Supports at York Canyon Mine of Kaiser Steel Corporation," hereafter referred to as the York Canyon Report.

Jan 1, 1984

In the late 1980s and into the 1990s, the Mountain Pass Mine in California produced about 40 percent of the world?s rare earth elements. At the height of this production, the facility produced up to 54 L/s (850 gpm) of saltwater that was piped to offshore holding ponds where the water was evaporated. In 1998, following a series of waste water pipeline breaches, separations activities were suspended, reducing the Mountain Pass site to just the openpit mine and mill. The environmental concerns were addressed and the affected areas have since been remediated. However, in the years following the breaches, 97 percent of the world?s production of rare earth elements moved to China. By 2011, Molycorp, and the Mountain Pass Mine, had rebounded from the difficult times and were once again in a position to become a significant player in the rare earth industry.

Jan 1, 2011

By T. Mudder, K. Harvey

The objectives for closure of a hard rock mine include minimizing long term environmental liability, attaining regulatory compliance, and maintaining geotechnical stability, while closing as cost-effectively as possible. Proper planning for closure should come during the feasibility study, design and permitting phases, and during operations as updates. The lack of a proper or updated closure plan can result in severe environmental and economic consequences. Effective mine closure is the result of a combination of innovative concepts, long-term commitments, and multi-party cooperation. The purpose of this paper is to discuss concepts, commitments, and cooperation as they relate to an effective closure plan.

Jan 1, 1999

By Alex Harrison, K. Payne

Computer generated magnetic field reference signa- tures of steel cord belt splices are used to evaluate lay-up and fabrication irregularities of splices in operating conveyors. Used as a quality inspection tool, magnetic signature analysis is useful in auditing data collected by general non-destructive testing (NDT) consultants. The evaluation can detect irregularities that weaken a splice, as well as detecting signature changes that can be indicative of adhesion loss. The evaluation can be applied to any NDT data available from a variety of commercial sources, which means that independent review of critical splice data is possible.

Jan 1, 1996

By K. Hansson, A. Jedborn

Background In the mining industry, conversion of fine particles into a slurry is often part of the normal processing of the ore. Therefore, from a system's point of view, slurry transporta¬tion would be considered as a natural alternative, all the way from the working face to the final processing. In underground mines, there is sometimes a considerable inflow of ground water that has to be pumped out. When the mine dewatering installations are integrated with a hydraulic hoisting system, the cost of power needed to pump out the ground water can be excluded from the cost of hoisting, compared with other modes of transporting the solids to the surface. The chief advantage of hydraulic hoisting is that the hoisting capacity can be increased at comparatively low total cost without necessitating the sinking of new shafts. Alterna¬tive examples include deepening of the existing mechanical hoisting system, truck, or conveyor belts transport in ramps to the present level. These often become very expensive. The economic effectiveness of hydraulic hoisting and hydraulic design considerations have been discussed by Kostuik (1965) and Sellgren (1985, 1986) for both small shallow mines and large deep underground mines. Objective and scope The objective of this study was to demonstrate the feasi¬biliy of hydraulic hoisting in hypothetical examples of mine deepening. Underground grinding to a maximum particle size of about 700 um (about 25 mesh) is considered. The pumping of ground ore products with positive displacement plunger or membrane type of pumps at working pressures of up to 15 MPa (2200 psi) is a thoroughly tested technique (Venton, 1986). Hydraulic hoisting system A hydraulic hoisting system is described schematically in Fig. l . The ore is mined, handled, and crushed conventionally. It is then ground wet underground. The slurry is then tempo¬rarily stored in an agitated tank and pumped to an agitated receiving tank on the surface. The ore is then further processed in the concentrator. The capacity of a pipeline is very high. For example, an annual production of 500 Kt (550,000 st) of ore can be handled in a 100-mm-diam (4-in.-diam) pipeline. Systems layout - economic effectiveness Schematic mine layouts are presented that represent situ¬ations where hydraulic hoisting often is the most economical alternative. A situation where the ore is trucked to the level of the existing hoisting system is shown in Fig. 2 (following page). With hydraulic hoisting, only a shaft for ventilation, pipe¬line, and personnel are needed. In a first phase (Fig. 2), a hydraulic hoisting installation with crushing and grinding units, storage facilities, and pumps has been located at a level of about 400 to 600 m (1310 to 1970 ft) below the surface. With further development of the mine, the hydraulic hoisting

Jan 1, 1989

By K. H. Al-Rawahy

Appreciation and awareness of the unique nature of mineral investment and ultimate development of a mine are crucial in promoting sustainable development. Special characteristics of mineral development include high capital intensive, long pre-production period, high risk, and the unavoidable ?economic? depletion. This paper examines ways to integrate these unique attributes of the mineral industry into the educational process, so that a properly advised and knowledgeable culture in terms of a sustainable mineral industry can be developed. Specific approaches are investigated in order to achieve this objective. These include a stochastic evaluation of a mineral investment proposal, adding a premium to the cost of capital that is used for valuation process, and internalizing incidental costs to the private cost function, thereby realizing the true (vs. apparent) marginal social cost of the proposed development. Undoubtedly, a total evaluation of any mineral project that accounts for both tangible and intangible parameters will contribute to sustainable development objectives. By incorporating the practical application of apparent theoretical topics such as risk, probability, and externality, and their relevance and impact on mineral lifecycle (prospecting, exploration, development, exploitation, use, and ultimate disposal) into the educational process, it is hoped that a generation of technocrats and decision makers that are familiar with and concerned about sustainable development will emerge.

Jan 1, 2007

By T. J. Smolik

The Golden Sunlight Mine started full-scale operations in February 1983, with a conventional open-pit mine supplying 4464 tonnes (5000 tons) per day of milling ore. After crushing and grinding, the ore is leached with cyanide solution in large agitation tanks. Soluble gold values are removed from the sand portion of the leached ore with five stages of countercurrent washing cyclones. After thickening of the cyclone-wash overflow slurry, the gold is recovered in activated carbon with a six-stage carbon-in-pulp circuit and a five-stage upflow carbon column circuit. Pressure stripping, carbon reactivation, electro-winning and refining complete the gold recovery process.

Jan 1, 1984

By John Durkin, Steven Wirch, Fred N. Kissell, Steven Ruggieri

The Bureau of Mines has developed two expert systems to give advice on coal mine dust control, one for continuous miner sections, and another for longwalls. Prototype versions have been evaluated by coal operators and MSHA. Both systems query the user as to the nature and extent of the dust control problem. Typical questions asked deal with matters such as cutting sequence, current dust standards and characteristics of current dust control techniques. Advice given by the system generally does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to practically implement what is suggested. Both were written using expert system development software called Insight 2+. The advantages of Insight 2+ for the user are: low cost, IBM-PC compatibility, and the fact that little prior experience with computers is required. For the developer, Insight offers an easy to use production rule language and goal driven structure as well as a wide variety of capabilities.

Jan 1, 1987