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By Z. T. Bieniawski, E. H. Skinner, R. A. Cummings, F. S. Kendorski

INTRODUCTION Caving Mine Drift Support Design The support of production drifts remains a high-cost item facing the developer or operator of an underground caving mine. Support costs are incurred well in advance of ore production, and there is a strong need to minimize these pre-production commitments of capital. Due to the extensive rock loads that normally develop during the caving process, the support used in caving mines is typically quite heavy and therefore costly. The process of designing this support increasingly makes use of basic tunneling principles, but is hindered by the still-incomplete state of knowledge of rock behavior in caving mines, and high variability of geological conditions in caving orebodies. Caving mines differ from tunnels in that the deformations and rock loads induced are transient and dynamic in occurrence, and are normally large in magnitude, often well in excess of rock mass strength. As opposed to tunnels, caving mine layouts are more intricate, and the methods and effects of construction ordinarily are not as closely monitored. Safety factors in mining tend to be lower and rock masses tend to he weaker. These aspects prevent strict application of tunnel design technology to caving mine drift support, with the result that mine drift supports are commonly designed chiefly on the basis of experience at other mines. Mining procedures at caving mines are evolved in response to site-specific requirements, to the extent that there are really as many caving methods as there are caving mines.

Jan 1, 1983

By F. B. Kuhnow

When performing blasting operations in open pit settings, energy is released and transmitted through the geology. Some negative effects can have significant impacts on mining operations and adversely affect mine production. This technical paper presents recommendations for blast design to prevent damage due to ground motion from blasting on adjacent concrete structures of underground operations. The paper includes a case study describing a problem regarding an open pit mine expansion and asks whether production blasting will damage concrete shaft structures due to blast stress waves and blastinduced ground motion. Based on the results, a set of criteria is provided to implement in current and future mining operations that involve blasting near underground concrete structures. A set of techniques on how to improve vibration levels for safe operations is also presented. Knowledge of particle velocity and wave propagation for site-specific circumstances to determine a safe level of vibration is recommended. Emphasis is placed on making use of electronic detonators and early delay detonators to achieve successful levels of vibration. A dynamic analysis is necessary to determine if vibration from blasting can damage the concrete shaft structure. When reinforced concrete structures are subject to blast loading, both concrete and steel are subject to very high strain rates. As opposed to static loads, when subject to high strain rate loads these materials increase their strength significantly. In fact, they increase by more than 50% for reinforcing steel, by more than 100% for concrete in compression, and by more than 600% for concrete in tension. This finding is of significant importance in mining operations because it allows an increase in flexural capacity of individual members as a result of high strain rates. Therefore, an elevated ground vibration (PPV) or particle velocity is permissible when blasting takes place near concrete structures.

Jan 1, 2014

By Hasan Nizamoğlu, Z. Abidin Sarı, Aslıhan Demiraslan, M. Deniz Turan, Tolga Depci

In this study, recovery of copper from solid material (obtained by leaching of chalcopyrite with oxalic acid in the presence of hydrogen peroxide) with a copper oxalate structure was carried out selectively using HCl. The chemical composition of the solid was as 29.3%, 9.7%, and 13.3% for Cu, Fe, and S, respectively. Selective recovery of copper by degrading the copper oxalate structure with a low-solubility product (Ksp = 4.43 × 10−10) was performed by conventional leaching in the presence of HCl. The optimum leaching conditions were determined as 5 M of HCl concentration, 318 K of leaching temperature, 120 min of leaching time, 25 ml/g of liquid–solid ratio and 400 rpm of stirring speed. Under these conditions, approximately 77% of copper and 3% of iron were taken into the solution. According to the characterization of the leach residue that was obtained, the oxalate structure was degraded. Moreover, the results of XRD analysis showed that the sulfur (S) and cubanite (CuFe2S3) phases were mostly observed in leaching residues, and this was supported by the SEM-EDX data. Based on the results, it may be stated that selective copper extraction can be obtained from a chalcopyrite concentrate by a two-step leaching method using a conventional hydrometallurgical technique.

By Lawrence A. Engel

The idea of using apron feeders for in directly feeding crushers is not a new one, it has been used for many years. To the best of our knowledge, the first apron feeder was used for bulk material handling in 1893. Since that time many design innovations have been introduced, with perhaps the most effective one being, the application of crawler tractor components in the feeder construction. This design was first introduced to the mining industry in 1954 by, national iron company. These feeders were used in the handling of run-of-mine iron ore on the Minnesota iron range, at the rate of 1,000 ltph. The material was fed over a grizzly to a jaw type of crusher. The crusher output was also handled by an apron feeder. Today, the apron feeder is being used in hard rock surface mine operations feeding crushers at rates of 5,500 ltph and over.

Jan 1, 1983

By Glen Church, Don W. Deere, Christoph M. Goss

The Standley Lake Dam Rehabilitation Project in Colorado included the complete replacement of the outlet works. This required two 1.8m (6 ft) diameter microtunneled wet lake taps, 380m and 186m (1246 ft and 636 ft) long, a permanent valve shaft 12.2m(40 ft) wide and 32m (105 ft) deep, and a 3.5m (11.5 ft) diameter (962 foot long) outlet tunnel driven with a roadheader. The tunnels were driven in low-strength, expansive, and slickensided claystone. The paper addresses the site investigation, shaft construction, roadheader performance, shotcrete placement, tunnel convergence, long distance microtunneling, and wet lake taps.

Jan 1, 2005

The 2003 SME Annual Meeting and Exhibit will take place Feb. 24-26 in Cincinnati, OH. The meeting will feature a host of special symposia and programming geared toward the industrial minerals and aggregate industry sectors. This programming focus is particularly relevant for this annual meeting, as it will be hosted in the center of America’s transportation hub and industrial mineral center. Cincinnati, located on the Ohio River, is key to the movement of America’s supplies and construction material needs.

Jan 1, 2003

By Carl G. Bock

INTRODUCTION The Washington Metropolitan Area Transit Authority (WMATA) has let a contract for the excavation of three rock stations, spaced about 3550' (1082m) apart, beneath Connecticut Avenue in Washington, D.C. Two previous rock stations have been completed, one of which had a crown pilot tunnel excavated to explore geologic conditions that would be encountered during the station excavation. This pilot tunnel was primarily for inspection by bidders and design was based on core hole information. The other rock station had no pilot tunnel and was also designed on the basis of core hole information. The three rock station areas, which are the subject of this paper, have been explored by crown pilot tunnels and an as-built report, with geologic maps and sections, has been prepared, for use by the design engineer as the basis of design for support of the structures. The geotechnical report describes the geologic structure in detail and relates it to excavation and support of the three crown pilot tunnels and the running tunnels which will be enlarged to create the 58'W x 44'H x 700'(+)L (17.6m x 13.3m x 212m +) stations. The information was complete enough to permit the design engineer to visualize the geologic structure and compute loads for the various types of rock conditions. It was therefore possible to determine the size and spacing of the steel sets for the several different conditions of rock structure encountered in the pilot tunnels.

Jan 1, 1976

By Robert A. Bauer, Paul B. DuMontelle

In 1985, participants of the multi-year Illinois Mine Subsidence Research Program conducted surveys of subsidence effects on crop production from current high-extraction mining methods, selected a site to characterize the profile, strain, fracture development in overburden materials and changes in aquifers produced by subsidence from high-extraction mining, characterized floor materia1 s in three mines, and established bibliographic reference and data base files. The Illinois State Geological Survey, University of Illinois at Urbana-Champaign, Southern Illinois University at Carbondale, Illinois Department of Mines and Minerals and Twin Cities Research Center of the U. S. Bureau of Mines are coordinating State and Federally funded research.

Jan 1, 1986

By V. McLemore, N. Dunbar, K. Donahue

There are three principle lines of evidence that indicate the clay minerals found in the Goathill North (GHN) rock pile at the Molycorp mine are predominantly a product of hydrothermal alteration, not weathering. The unweathered drill core and samples from GHN have similar types and abundances of clay-mineral groups based on XRD analysis. Chemical analyses from the electron microprobe reveal similar chemical compositions for the hydrothermal alteration clays in drill-core samples and clays found in the rock pile. Textural evidence gathered from petrographic and microprobe examination also suggests a hydrothermal origin for clay minerals.

Jan 1, 2007

By J. Kretschmann, O. Drusche, S. Krause

Mining companies are caught between the growing international relevance of ESG (Environmental, Social and Governance) investments and the need to secure their “social license to operate” by considering the needs of their stakeholders. In the search for sustainable business models, the concept of the circular economy (CE) is gaining momentum among practitioners and scholars, as it enables the creation of shared value and thus strengthens the trust of investors and stakeholder relationships. However, there is a lack of a sectorspecific CE framework providing guidance to decision-makers in evaluating promising activities. A gap, which this contribution aims to address.

Mar 2, 2022

By J. T. Hollow

The Fort Knox Mine is located in Alaska?s interior, where the average ambient air temperatures range from -24°C (-11°F) in January to 16°C (61°F) in July. The mill processes a free-milling gold ore utilizing both a gravity recovery circuit and conventional cyanide leach/carbon-in-pulp circuits. Mathematical models have been developed to accurately predict the impact of leach circuit slurry temperature on gold leaching, carbon adsorption and cyanide destruction kinetics. Additionally, an energy-balance approach has been used to model the seasonal variations in slurry temperatures throughout the Fort Knox mill. The energy-balance model, combined with the kinetics models previously developed to predict plant performance, was used to justify a tailing thickener installation at the Fort Knox Mine. This paper describes the development of the energy-balance model and its prediction of plant performance assuming a tailings wash thickener to reduce heat loss from the mill. Also presented is an analysis of the post-project plant performance that validates the model and shows that the mine produced an additional 596 kg (19,155 oz) of gold while reducing mill reagent costs by $6,302,000 during the first 38 months of operation.

Jan 1, 2007

By P. C. Fletcher, E. Kaya

The Bond grindability testing procedure has been standardized to measure the same grindability values, i.e. Bond work index (BWi), for the same ore when tests are performed in different laboratories or by different operators. This is accomplished by the standardization of mill dimensions, tumbling speed, grinding ball charge weight and distribution, sample ore charge weight in the mill and operating practice. The results of this investigation reveal that the Bond work index grindability values may differ substantially with different standard Bond ball mills. This paper will review the results.

Jan 1, 2002

By S. Borner Schweizer

An overview over SAM’s approach to assess corporate sustainability performance illustrates how sustainability challenges are linked to trends, assessment criteria and finally company performance. This process is exemplified with some general and industry specific criteria. Lastly, results of the Dow Jones Sustainability Assessment 2004 show a considerable gap between leading and average companies. Best practice examples demonstrate how lagging companies could improve their sustainability performance.

Jan 1, 2005

By E. Yigit

Hydrometallurgical production of zinc from concentrates is generally carried out by H2SO4 leaching. For the smooth operation of this process, some harmful components must be removed from the leach solution before the electrolysis stage; MgO is one of these compounds. Zinc concentrate samples from the Mount Isa mines were used in leaching tests. Leaching tests with an aqueous solution of H2SO4 and SO2 gas were carried out at various temperatures, pH levels and leaching durations. While duration and the pH value of the solution were effective parameters in H2SO4 leaching, temperature and pH were more effective in SO2 leaching for the removal of MgCO3 and CaCO3. Removal of MgCO3 and CaCO3 was generally achieved at low pH values. The results show that SO2 gas can be a good alternative to sulfuric acid in the leaching of MgCO3 and CaCO3

Jan 1, 2010

By D. Loring, J. Almgren

Climax Molybdenum Company’s Henderson Mine is a large panel caving molybdenum mine located about 43 miles west of Denver, Colorado. Three Joy M120-72-880 fans are installed in parallel on the No. 1 exhaust shaft. Throughout the mine’s history, ventilation changes such as the completion of the No. 5 exhaust shaft have decreased the utilization of these fans. To optimize fan performance they have been run with the full complement of 16 blades, down to as few as four blades. Since the completion of ventilation upgrades associated with the Henderson 2000 project, one surface fan has been operated under normal conditions with 10 or 12 blades. With the completion of a new network model of the Henderson ventilation system, a tool was built to develop fan curves for possible future fan configurations and predict future fan performance. This paper describes the tool and its use at Henderson.

Jan 1, 2007

By Harry R. Price, Bharat Doshi, Awni Qaqish, Abdul-Ghani Mekkaoui, Thaddeus Znoy, Ramesh Shukla

In 1992, a detailed inspection of the Southfield Sewer revealed a reach of approximately 0.8 kilometers in length, located directly below the freeway lanes, which was severely distressed. Failure of this section of the sewer would result in the closing of the busiest roadway in the state as well as the potential backup of sewage into homes and spilling into nearby surface waters. As such, repair of the distressed section required development of a procedure that would not jeopardize the conveyance of flow through the existing sewer nor impede travel on the overlying freeway. Based on these constraints, the DWSD and NTH team developed a repair concept that entailed the mining of a new, 3.05-meter (10-foot) diameter bypass away from the traffic lanes. The new bypass section was connected to the existing sewer, up stream and down stream of the distressed area, using a “top down” construction approach, that required only minimal freeway closures during weekend periods. This paper, prepared jointly by the Owner, Consultant and Contractor will describe existing conditions, design considerations and construction methods.

Jan 1, 2001

By D. J. Kunz

Myanmar Ivanhoe Copper Company Ltd. (MICCL) has been operating the Sabetaung- Kyisintaung (S&K) Project producing LME Grade A Copper Cathode using the Heap Leach-SX-EW Process since 1998. The mineralization is mainly Chalcocite and the mine has a life of 20 years at the designed annual production of 25,000 tonnes of cathode copper. Design capacity was achieved within two of months of start-up. The mine is among the world’s lowest cost, Heap Leach-SX-EW operations. Information regarding plant design and operation are presented along with the challenges lying ahead and the latest developments. Daniel Kunz is President and Chief Operating Officer of Ivanhoe Mines, and a director of MICCL. He has more than 20 years’ experience in mining, construction and engineering. Prior to joining Ivanhoe Mines in 1996, Mr. Kunz was Vice President and Controller of Morrison Knudsen Corporation, a major international mining and construction company. He was also President and Chief Executive Officer of MK Gold Company, a public mining company listed on NASDAQ.

Jan 1, 2001

By K. A. Lapakko, D. A. Antonson

Fourteen samples of pyrite-bearing Archean greenstone rock (d < 6.35 mm, 0.04% < St < 1.22%) were characterized (particle size, chemistry, mineralogy) and subjected to laboratory dissolution testing. The only sulfide and carbonate minerals identified were pyrite and siderite, respectively. Quartz, chlorite and sericite typically comprised 90 to 98 percent of the mineral content. For the first 60 weeks, seven samples with sulfur contents less than or equal to 0.16% produced drainage pH values exceeding 6.0. Over this period, six of the seven samples with sulfur contents greater than or equal to 0.20% produced drainage pH below 6.0, with minimum values ranging from 3.2 to 4.7. The seventh sample (0.72% S) had a siderite content of 18%. Small amounts of magnesium and, to a lesser degree, calcium carbonates present in the siderite apparently dissolved to neutralize acid and maintain drainage pH above 6.0. Sulfate release rates generally increased as sulfur content increased, and the rates of pyrite oxidation estimated for individual samples were roughly half to five times that reported in the literature for the abiotic oxidation of pyrite by oxygen. Observed neutralization potentials ranged from 0.2 to 2.0 g CaCO3/g rock.

Jan 1, 2002

By C. Sun

The Leeville underground mine has been in operation since 2006 and currently produces 3,500 tons of ore per day with an average gold grade of 0.34 opt. The mine has a large horizontal extent of 2,500 feet by 500 feet and a vertical extent of 20 to 200 feet. Based on the characteristics of the ore bodies, a long-hole stope and cut-and-fill mining methods are used at the deposits which are divided into several mining zones. Cemented rock fill (CRF) is used as the backfill in the open stope. CRF design includes the aggregate design, the ratio of cement and fly ash design, and strengths for the long-hole stope and cut-and-fill. In the aggregate design, the particle size distribution is one of the most influential aggregate characteristics in determining how it will perform as a basic backfill material. Gradation helps determine durability, porosity, cement and water requirements, strength, and shrinkage. To cut the backfill cost, fly ash usually is added into the binder to replace some part of cement. However, adding fly ash can affect the strength of the backfill. The reasonable percentage of fly ash is also important for making a good and low cost backfill. Based on the different mining method, the different backfill with different strength is designed. A systematic quality control procedure for aggregate and backfill is followed. After four yeas application, CRF system in Leeville achieved very good results.

Jan 1, 2011

By B. Slaker, M. M. Sears, G. Rashed

Ground falls represent a significant hazard at underground mines in the stone, sand and gravel (SSG) sector in the United States. Researchers from the U.S. National Institute for Occupational Safety and Health (NIOSH) are conducting detailed investigations into the complex loading conditions at underground stone mines operating in challenging conditions. This paper presents the application of numerical modeling to analyze pillar and roof stability at a dipping underground limestone mine.