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By Richard M. Winar

In September of 1988, the United States Environmental Protection Agency (US EPA) published final regulations that effect owners and operators of underground storage tanks (USTs). These regulation include stringent technical requirements for owners and operators of USTs containing petroleum and certain hazardous substances. The technical requirements effect both new (those installed after December 1988) and existing USTs and include notification; performance and operating standards; release detection, reporting, investigation; release response and corrective action; and closure requirements for out-of-service USTs. The USEPA also published final regulations regarding financial responsibility requirements for owners or operators of petroleum USTs in October of 1988. These regulations require owners or operators of petroleum USTs to demonstrate financial responsibility for the costs of corrective action and compensating third parties for bodily injury or property damage caused by releases from petroleum USTs. Like thousands of other industries, the mining industry must become thoroughly familiar with these new regulations in order to properly manage their UST systems, ensure compliance, and understand other ramifications imposed by these regulations.

Jan 1, 1990

By P. Nelson, R. O’Connell, J. Rostami

Tunnel boring machine (TBM) system utilization is a critical factor for predicting machine performance. The process of estimating machine performance, including rate of penetration (ROP) and machine utilization (U) must incorporate an understanding of site geology, TBM specifications and site management. The study herein presents a preliminary analysis of the different activity time and downtime components from hard rock TBMs at two project sites to evaluate their impact on machine utilization. A comparison of crew experience, first between shifts and then between projects is included to analyze its effect on utilization and downtime. This work presents the sensitivity of the utilization factor to selected activities in the projects and the impact of geology and site set-up/logistics on machine performance.

Jun 13, 2021

By J. P. McDonald

Exposure to particulates containing metals and metal fumes (PCMMF) is a potential concern in ore refining and smelting. Some metals of primary interest are arsenic, cadmium, copper and lead, which have been linked to various adverse health effects. The current National Institute for Occupational Safety and Health (NIOSH) sampling method for metals in particulates requires the use of a filter, precision airflow pump and laboratory analysis. A major concern with this method is the one-to-two weeks? wait before laboratory results are available for use in determining if additional controls are needed to assure adequate exposure protection for workers. Particulates containing these metals were sampled during sixteen sampling events at a copper smelter using the traditional NIOSH methods. Monitoring of particulates was simultaneously conducted using a TSI 8520 Dust-Trak real-time aerosol monitor with a 10-µm-cutpoint sampling inlet. NIOSH analytical methods related to particulates and metals (methods 0500, 0600 and 7300) were used to determine particulate mass and individual mass contributions of metals on sample filters. Linear regressions with y-intercepts forced to zero were developed to determine the relationship between the PM10 measurements recorded by the DustTrak and laboratory-reported total particulate mass, PM10 and respirable arsenic, cadmium, copper and lead concentrations. These linear regressions yielded correction factors that can be applied to DustTrak readings to obtain total particulate mass, PM10 and respirable concentration estimates for each of the four metals. The R2 (coefficient of determination) values from the linear regressions ranged from 0.65 for total lead to 0.91 for total copper. These results suggest that the DustTrak may produce real-time data useful in providing estimates for airborne concentrations of arsenic, cadmium, copper and lead in copper smelter particulates.

Jan 1, 2011

By D. W. Alexander

In 1993, CONSOL began investigating new methods of permanently filling coal mine shafts, which after ventilation is stopped, may contain a potentially hazardous atmosphere. Fill materials such as fly ash/cement can be pumped, are non-combustible and non-incendiary but tend to flow into the mine entries. A non-flowable mixture has been developed that minimizes the volume of fill used. The paper presents our recent shaft filling experience including fly ash material properties, mix designs, field problems, placement success, and gas testing techniques.

Jan 1, 1996

By L. Thompsen

High pressure grinding has been introduced into many grinding applications. The high pressure grinding roll offers capacity increases of existing plants and savings in operating costs. Also metallurgical advantages could be achieved. The first high pressure grinding roll in a copper mine was commissioned in Arizona in July 1995. This paper provides information about the operating experience gathered during the first months of operation. The current flowsheet will be described as well as further options for plant arrangements.

Jan 1, 1996

By P. James

"INTRODUCTION High sulfate (SO4-2) levels often occur in MIW (mining influenced water) either as the result of oxidation of sulfide minerals exposed by mining activity or by deliberate addition – commonly by sulfuric acid (H2SO4) use in hydrometallurgical leaching activities. Increasing regulation of sulfate discharge is creating new pressure to treat or mitigate sulfate release to prevent its entry into the environment. Current treatments include precipitating as gypsum during lime treatment, filtration separation using membranes such as reverse osmosis and nanofiltration technology, and biological elimination via methods like constructed bioreactors. Blue Planet Strategies (BPS) focuses on improved resource utilization targeting electrolytic treatment and waste conversion into resources and has now demonstrated that its proprietary DEMET™ (Dynamic Electrolytic Metal Effluent Treatment) platform can also remove sulfate from target streams as a byproduct of its usual primary treatment focus points of metal species elimination and/or pH adjustment.[1-6] This powerful new capability can mitigate sulfate contamination and recover the sulfate in a useful and potentially saleable form as a byproduct of improved primary treatments focused on enhancing production or treating waste. This provides a new treatment opportunity and value proposition for lowering overall sulfate consumption/addition or creating new revenue to defray conventional treatment costs. The DEMET Alternative DEMET utilizes a patented electrolytic technology platform employing proprietary dynamic high surface area electrodes in innovative configurations to achieve a variety of novel selective chemistries. DEMET‘s unique elements can yield higher processing rates at practical efficiencies, lower energy consumption, plus improved processing stability and lower maintenance requirements due to enhanced resistance to cell fouling and shorting; while also thwarting cross stream (catholyte vs. anolyte) contamination. Consequently, DEMET can provide a superior, extremely versatile, and cost-effective electrolytic treatment option where a multitude of FEED and PRODUCT stream combinations might be employed in comparison to traditional tankhouse electrolytic cells. Secondary reactions (Figure 1A) which could also occur at the cathode (plating/electrowinning, precipitation/scale formation, etc.) are controlled through process tailoring and operation parameter selection. Additionally, DEMET‘s innovative dynamic system mitigates potential fouling and electrode occlusion or shorting challenges which could occur when process particulars demand some of these secondary side reactions occur."

Jan 1, 2015

By M. W. Smith

Pennsylvania has 2500 miles of streams that do not meet water quality standards due to acid mine discharge (AMD), making AMD the greatest cause of water pollution in the state. The problem is mainly caused by abandoned coal mines. Pennsylvania is using a watershed-based approach to abating AMD which includes remining as a key component of a comprehensive restoration strategy. The Tangascootack Creek Watershed was targeted for AMD restoration through remining. Geologic mapping and overburden data were analyzed using Earth Vision software to identify areas of coal reserves which could be remined to improve water quality. Incentives are offered to encourage mining in these designated areas.

Jan 1, 1999

By O. D. Staman

The risk assessment project examines the likelihood of inorganic contaminants from copper dump-leaching operations to contaminate domestic water supplies. The project examines contaminant transport by modeling contaminant movement from the base of a leach pile through the unsaturated zone and into the saturated zone. The modeling effort is unique in that it models infiltration, contaminant transport in the unsaturated and saturated zone combined with geochemical modeling of the unsaturated zone. The project incorporates probability theory to reflect the uncertainty of hydrogeologic parameters.

Jan 1, 1994

By K. M. Mohamed, I. B. Tulu

"Failures of coal ribs are major hazards in underground coal mines. For the period of 2010 to 2014, rib falls were the leading cause of groundfall fatalities and accounted for 35% of all groundfall-related fatalities. Currently, the National Institute for Occupational Safety and Health (NIOSH) is conducting a research project to develop an engineering-based design methodology for rib control in coal mines to reduce rib fall accidents and fatalities in underground coal mines. Numerical models can be used as part of the design methodology provided the models are appropriately calibrated and verified. The paper presents a coal rib model to simulate the mechanism of the coal deformation and fracturing that can lead to stress-driven rib falls. The proposed coal rib model was calibrated against published data from an instrumented rib site at the West Cliff mine in Australia. Fracturing of the coal rib was defined by critical values of shear strain of the coal material and rib displacement. A critical plastic shear strain of 2.8% and a sudden increase of rib displacement of 30 to 45 mm were sufficient to develop a fracture plane in the rib model. Accordingly, a discontinuous rib deformation was achieved and it compared favorably against field monitoring data. INTRODUCTION Coal ribs are the vertical walls of coal formed when entries are developed in a coal bed. Failures of coal ribs are a major hazard in underground coal mines. Furthermore, failing ribs can contribute indirectly to roof and floor instability by increasing opening widths across intersections and entryways. Over the last 18 years, there has been a continual occurrence of injuries and fatalities in underground coal mines due to rib falls. For the period of 2010 to 2014, rib falls (excluding longwall face and bursts) were the leading cause of ground fall fatalities and accounted for 35% of all groundfall-related fatalities [1]. Despite the threat of rib falls, the amount of rib falls and rib support research conducted in the U.S. is limited compared with what has been done in pillar and roof support design. Currently, the National Institute for Occupational Safety and Health (NIOSH) is conducting a research project to develop an engineering-based design methodology for rib control in coal mines to minimize the number of rib fall accidents and fatalities in underground coal mines."

Jan 1, 2016

By B. W. Cavender

Innovative mining and metallurgical operating techniques or processes can be identified and developed by systematically analyzing change as it occurs within the mine, plant, technology, or industry. Sources of change to be monitored for innovative opportunities include unexpected successes or failures, incongruities between perceived and actual events, process needs, changes in perceptions, and the development of new knowledge. Innovation can be effectively organized, practiced, and managed. The perception of change as an opportunity rather than a threat is mandatory, as is the systematic measurement of innovative performance. Innovation is enhanced by specifically-designed policies regarding organizational structure and staffing, daily management practices, and compensation and incentives.

Jan 1, 1994

By Amy McBrayer, Andrea Brickey

Limited research has been conducted related to the development of mathematical optimization models for production scheduling at large surface coal mines using the area, i.e., strip, mining method. Increased economic and technical challenges have led to a new interest in production schedule optimization models for these type of mining operations like those currently applied to model underground and open pit mines. While area mines share similar characteristics to both open pit and underground metal operations, neither an open pit nor underground production scheduling model adequately depicts an area mine mathematically. We present an integer programming model with blending constraints and discuss the challenges and opportunities related to the implementation for area mines as well as future research in area mine production scheduling.

Jun 25, 2023

By M. V. K. Reddy

A differential flotation process for recovery of molybdenite from chalcopyrite concentrates produced at Rakha Copper Concentrator, Bihar, India has been developed. The flowsheet is simple, and relatively inexpensive and yields a concentrate assaying not less than 45% Mo at a recovery of minimum 65%, starting from chalcopyrite concentrate assaying 0.4% Mo. The consumption of the main depressant used, sodium sulphide is not more than 25 kg/t of copper concentrate processed without steaming; and with steaming the consumption was brought dorm to less than 12 kg/t of concentrate. Further reduction is possible by optimization of steaming parameters. Based on laboratory experimental results, further tests were conducted on concentrator site and process design parameters were established for design of commercial plant.

Jan 1, 1982

By Dirk van Zyl

Pad construction costs can impact the overall economics of heap leach projects. Pad construction costs for single-and double-lined pads, using various designs, are listed for a typical small and large project. Double-lined pads are now more often required by regulatory agencies. Unless such designs reduce the risk of site specific contamination significantly, the extra costs cannot be justified from an economical viewpoint. Specific attention is given to the short project life (typically five years) of heap leach projects. A few numerical examples are presented to demonstrate the overall economic impacts of these costs on economic parameters.

Jan 1, 1990

By D. Berberick

On January 5, 2012, the Mine Safety and Health Administration ordered the closure of the Silver Shaft, the primary underground access to Hecla?s Lucky Friday Mine, for removal of built up backfill material that accumulated over time on the shaft walls and furnishings. Lucky Friday and Cementation USA personnel worked quickly to identify the most effective means to get the mine back into production. The team developed a fast-track procurement and refurbishment plan utilizing shaft sinking winches, headframe modifications, a partial shaft sinking Galloway, and modified cages to not only complete clean-off of buildup, but also replace pipe brackets, shaft steel, and power and communications cables as needed in the 1,860 m (6,100 ft) deep shaft within 14 months.

Feb 23, 2014

By J. J. Gusek

The Riley Pass strip mine is an abandoned uranium-bearing lignite deposit in Harding County, South Dakota, covering about 150 acres of highwalls, pit floor and mine spoils exhibiting elevated levels of radioactivity. Six reclamation design alternatives were developed, ranging from doing nothing to reclaiming to approximate original con-tour. The alternatives were evaluated for expense, site stabilization, and mitigation of public safety hazards. A comparative economic evaluation on three of the alternatives was completed for the Forest Service in selecting an alternative and substantiating federal funding requests. This evaluation included economic impacts associated with physical and radiologic health hazards, affects on recreational users, socioeconomic impacts and environmental improvement.

Jan 1, 1995

By I. Sanchez

The development of the recent generation of large mining projects in South America has been challenging in many ways, but especially in the management of water in all its aspects. As a result, a number of projects have experienced difficulties and in some cases significant delays due to a lack of a clear and approved definition of the supply, use and discharge of water from mining and processing sites. The development of the recent generation of large mining projects in South America has been challenging in many ways, but especially in the management of water in all its aspects. As a result, a number of projects have experienced difficulties and in some cases significant delays due to a lack of a clear and approved definition of the supply, use and discharge of water from mining and processing sites.

Feb 23, 2014

By P. Gelfi, J. Vanderbeek, J. Enriquez

"The Cerro Verde copper-molybdenum mining complex is located near Arequipa, Peru. A 108,000 t/d copper concentrator (C1 concentrator) commenced operation in late 2006 and was debottlenecked to a 120,000 t/d capacity in 2011. A feasibility study, initiated in May 2010, assessed the potential for expanding the processing rate of the large Cerro Verde sulfide reserve via the installation of a second, stand-alone, concentrator (C2 concentrator) capable of processing a nominal 240,000 t/d ore. The feasibility study was successful and the project advanced through engineering, permitting and construction. Ramp up to nameplate capacity was ahead of schedule. The overall project was completed on schedule and within budget. The details of the project and supporting components are described. The design philosophy and design basis of the concentrator facilities are discussed as are factors that influenced the concentrator layout. Risk mitigation features included in the design are reviewed. The factors that drove the successful and rapid ramp up to nameplate capacity are discussed. Operational experiences in the first year of plant operation and project lessons learned are described. INTRODUCTION/BACKGROUND Sociedad Minera Cerro Verde S.A.A. (SMCV) operates a copper mine near Arequipa in southern Peru. Small scale operations operated intermittently until 1970 when the deposit reverted to the ownership of Minero Perú S.A (Peruvian government). Minero Perú S.A. commenced mining and processing of oxide reserves in 1972 and placed an SX-EW plant into production in 1976. The ownership of the property has changed hands several times over the years. Minero Perú sold Cerro Verde to Cyprus Climax Metals in 1994. Cyprus was acquired by Phelps Dodge in 1999. Freeport-McMoRan (FCX) acquired Phelps Dodge in 2007. Several studies were undertaken during the 1990’s that tried to establish the economic justification to process the large primary sulfide resource that underlies the surface oxide deposit. None of these studies produced an economic conclusion until a feasibility study was completed by Phelps Dodge and SMCV in 2004. This study provided the economic justification for the construction of a 108,000 t/d concentrator during 2005 and 2006. The key to the success of this study was identifying a water source that was sufficient to support processing economies of scale. Concentrator operations commenced in late 2006. The original design production rate of 108,000 t/d was achieved on a 30 day moving average basis on the 266th day after ore was first introduced. During 2009, studies and evaluations were performed that had the objective of addressing observed concentrator bottlenecks to allow a production rate of 120,000 t/d to be achieved. The 120,000 t/d figure represents the sustainable production limits associated with the installed primary crusher and tailing thickeners which would have been prohibitively expensive to upgrade. Debottlenecking activities were implemented during 2010 allowing sustained production rates of 120,000 t/d to be achieved."

Jan 1, 2017

By Byron C. Hardinge, E. R. Palowitch, Albert W. Deurbrouck, David J. Akers, Edward R. Torak

During 1983, 42.2% of the 686.0 (624.3 Mt) million tons of coal reported, 289.6 (263.5 Mt) million tons were mechanically cleaned, of which 107 (97.4 Mt) million tons were cleaned by dense media (magnetite and sand) processes.' The percentage of bituminous coal and lignite cleaned mechanically by dense medium processes increased from 7 to 38% between 1938 and 1983. The Electric Power Research Institute estimates that 150 million tons (137 Mt) of coal were cleaned by heavy-media processes in 1986, and that this number may increase to 265 million tons (241 Mt) by 1990.2 Dense medium separations include those coal preparation processes that clean raw coal by immersing it in a fluid having a density intermediate between clean coal and reject. As there is a general correlation between ash content and specific gravity, it is possible to achieve the required degree of removal of ash-forming impurities from a raw coal by regulating the specific gravity of the separating fluid. Dense medium processes generally offer the following advantages over other coal cleaning processes: • Ability to make sharp separations at any specific gravity within the range normally required even in the presence of high percentages of raw coal whose specific gravity is near the specific gravity of separation. • Ability to maintain a separating gravity that can be controlled within + 0.005 sp gr units. • Ability to handle a wide range of coal sizes. • Ability to change specific gravity of separation to meet varying market requirements. • Ability to handle fluctuations in feed, in terms of both quantity and quality. Unfortunately, dense medium processes can have the following disadvantages: • Relatively high capital costs caused primarily by the need for equipment to collect and recycle the medium. Relatively high operating costs caused primarily by operation of medium recycle equipment and loss of medium.

Jan 1, 1991

By R. L. Miller

"Miners worldwide use a tremendous amount of energy in producing finished minerals for the end user market. In accomplishing this goal, they incur energy costs that can range from 20% to 30% of the total cost of production, so there is fertile ground for cost savings. To unlock this huge value in cost reduction, energy analysis is the key and is broken into several segments: 1. Fuel analysis for power generation 2. Energy supply & demand 3. Opportunity cost for lack of power 4. Backup power 5. Power contracts 6. Energy efficiency 7. Renewable energy 8. Continuous energy management FUEL ANALYSIS FOR POWER GENERATION What is the first thing we evaluate when looking at power supply alternatives for the mining industry’s large power requirements? Is it 1) site, 2) engineering, procurement, and construction companies, 3) independent power producers, 4) turbine vendors, 5) grid connections, or 6) fuel supply, logistics, and infrastructure? In evaluations of power supply alternatives for mining companies with special emphasis in developing countries, there is one over-riding conclusion: reliable fuel supply drives the energy generation economic engine. Evaluating several different fuels including liquefied natural gas (LNG), natural gas, diesel, heavy fuel oil, and liquefied petroleum gases (LPG) among others, the best project outcomes are those where fuel supply, pricing, logistics, and infrastructure are given an extensive amount of time during the analysis stage. In an assessment of the twenty-year costs of generating power from multiple fuels, each fuel’s costs were placed into three separate net present value (NPV) buckets of: 1) capital, 2) operating and maintenance, and 3) fuel. Within a range of 65% to 85% for all fuels, fuel cost was the largest component of the NPV of the life cycle power generation costs. So if 65% to 85% of your life cycle power generation cost is one item, shouldn’t miners spend a corresponding amount of time in the analysis stage fully understanding this key determinant for a successful power project? In developing countries where power generation infrastructure may not exist or does not exist at the same level as is found in North America and Europe, fuel analysis becomes even more important. One of the key questions for fuel importation in developing countries is the draft at existing ports to allow larger vessels to dock at the jetty. Can larger ocean-going tankers dock at the port for off-loading, or is the port’s draft too shallow, thus forcing a Single Point Mooring (SPM) system or Conventional Buoy Mooring (CBM) system to be constructed at substantial capital expense? Once fuel can be imported, sufficient onshore storage capacity should exist, or must be built to off-load the entire fuel cargo from the larger ships. Additionally, the throughput capacity of the pipeline from SPM/CBM must allow a rapid unloading of the fuel from ship to shore to eliminate steep demurrage costs for the project."

Jan 1, 2017

By Vas P. Kenyen

Introduction Autogenous, semi-autogenous, and conventional grinding circuits are used to process ores. Current emphasis, though, is towards the use of the first two systems. The reason is the generally lower initial investment required for an autogenous or semi-autogenous circuit as compared to a conventional comminution circuit. However, the effect of operating costs that will significantly affect overall comminution economics is not considered in this evaluation. About 70% of the energy in a mineral processing plant is used in the comminution circuit. Until the 1974 oil embargo, energy was relatively inexpensive. Since that time, the cost of energy has escalated 40-fold. As a result, energy cost now forms a significant portion of operating costs in comminution. According to a survey conducted by General Electric Co. (Powers, 1982), the price of electricity will continue to rise 15% to 20% per year, in spite of the current oil glut. Both autogenous and semi-autogenous grinding circuits consume more energy than the conventional comminution circuit. Higher consumption ranging from 16% to 35% has been reported in the literature (Bassarear, 1982; Gjerdrum. 1979; Betts, 1982; and Christie, 1979). Consequently, even a small increase in energy costs is likely to have a significant impact on operating costs. Therefore, the economic decision of selecting an optimal comminution circuit is important. More than ever before, it is now critical to include in the evaluation of communition circuits not only the capital costs, but also the operating costs; in particular, the expected energy cost over the life of the operation. Failure to do this may lead to a less than optimal comminution circuit. Design A comminution system should be designed only after bench-scale or pilot plant testing of a representative sample. Conventional crushing and grinding circuits can be designed on the basis of the Bond Work Index (Rowland and Kjos, 1980). Over the years, sizing of full-scale rod and ball mills from Bond Work Index data has become well established. Autogenous and semi-autogenous mills cannot be sized based on bench-scale tests. Pilot plant tests are necessary to determine the amenability of the ore, critical size buildup, and power requirements. For this study, conventional and semi-autogenous grinding circuits were designed for ore throughput of 12, 24, 36, 48, 72, and 90 kt/d (13,200, 26,400, 39,600, 52,000, 79,200, and 99,000 stpd). Rod and ball mills were scaled up on the basis of the Bond Work Index. A two-stage semi-autogenous grinding circuit was designed on the basis of pilot plant test results. In designing a grinding system, emphasis was placed on operating flexibility. The largest commercially available equipment was

Jan 10, 1984