Search Documents

By A. Pratt, G. Deschênes

This paper quantifies the detrimental effects of pyrite and stibnite on gold leaching kinetics. Means to reduce the effect of these minerals by addition of lead nitrate and oxygen are presented. A significant retarding effect was observed when the pyrite concentration was 20%. A pretreatment with lead nitrate reduced the extent of gold surface coating by Ag, Fe and S. Stibnite, at a concentration as low as 20 ppm, significantly affected the gold leaching kinetics through forming a passivating film of Sb(V) oxide possibly Sb2O5. The most practical way to alleviate the effect of stibnite is to leach the materials at a moderate pH with addition of lead nitrate. A low temperature reduced the efficiency of lead nitrate to counteract the effect of stibnite. The increase of dissolved oxygen is not favourable to alleviate the coating of stibnite on gold.

Jan 1, 2004

By Sergio Flores, Nate Long, William Hodder, Phil Rhodes, Tim McQueary

The Surface Water Supply Project Segment B3 is a 4 miles section of tunnel that will run East- West in Houston TX, from Hopper St to I-45. The tunnel will be mined by using a 128" Dia refurbished 1987 Lovat Tunnel Boring Machine capable of operating in Open or EPB mode. The tunnel will be temporarily supported with ribs and lagging and a 96" Dia pipe will be grouted into place. All four miles of this project are within Petroleum Pipeline Easements. The project includes seven shafts, 2000' of tunnel in potentially petroleum contaminated ground, crossing the Hardy Toll d, I-45, the nion Pacic ailroad ight of Way and multiple oil and gas pipeline crossings. This paper summarizes the planning and drive performed to date.

Jun 23, 2024

Sandvik built its first stone crusher in 1896 and has since grown to become a world leader in mining equipment. ?We are the best in the world, and we can now be even better at making our cone and jaw crushers in different models,? Olle Lundberg, production engineer at the Sandvik Mining factory in Svedala, Sweden told freelance journalist U. Samuelsson, of mekpoint.com. As a specialty manufacturing business under the umbrella of the Sandvik Group, Sandvik Mining is a leading global supplier of equipment, tools, services and technical solutions for the mining industry. Its expertise covers the areas of rock drilling, cutting and crushing, as well as loading, hauling and the handling of materials. Lundberg, along with five colleagues, will write CNC programs for the lathes and machining centers that manufacture Sandvik?s specially constructed casting. In 1999, Sandvik chose ESPRIT computer-aided-manufacturing (CAM) software by DP Technology to program its array of machine tools, and has worked with ESPRIT reseller Holotech, based in Örebro, since 2003.

Jan 1, 2014

By K. Zabrusky

Epithermal vein systems are often modeled as simple, discrete high grade structures within low grade host rock. However, geologic setting and structural preparation influence how such vein systems form. In structurally complex areas, veins may follow several structural trends and occur on a variety of scales. Geologic and grade modeling within such complex structural regimes can be difficult as individual veins cannot be delineated from host rock based on grade alone. Structurally complex areas require a different approach than traditional discrete vein modeling. Presented herein is a study of a structurally complex area that hosts vein mineralization to be mined underground. All veins could not be modeled discretely, so an alternate approach was needed. Major structures were modeled using surface and underground mapping and were then used to create a structural trend for the area. This trend was used to guide 3D grade shell construction. The grade shells replaced 3D vein solids for grade estimation in order to mitigate the influence of high grade samples. Structurally guided grade shell construction offers a more effective modeling method than discrete vein modeling in deposits that are structurally complex.

Feb 23, 2014

By M. Laliberte

Gold mine effluents are often characterized by a high concentration of copper, ammonia and cyanide derivatives (mostly cyanates and thiocyanates). While non-acutely toxic to birds, this water can be acutely toxic to fishes and invertebrates. In many jurisdictions, the effluent requires further treatment in order to pass a mandatory requirement to be non-lethal to species like the rainbow trout (Oncorhynchus mykiss) or Daphnia magna. Using actual mine water, it has been demonstrated that aerated moving bed biofilm reactors will biodegrade the ammonia, cyanides, cyanates and thiocyanates, thereby removing the toxicity associated with these components. By removing copper by precipitation the water can be made to pass acute toxicity tests. Tests have demonstrated that the process is stable between 4 and 25 C, with no significant changes in the treated water composition. Once the biomass is acclimatized, the process is resistant to upsets and requires very little inputs except for phosphorus and air. Furthermore, it has been demonstrated that an anoxic reactor can be added downstream of the aerated reactors to remove nitrates if required.

Feb 23, 2014

By C. E. Jordan

The Bureau of Mines investigated a simultaneous elutriation and flotation technique for separating polyethylene terephthalate (PET) from polyvinylchloride (PVC). The Tuscaloosa Research Center, through a cooperative agreement with a recycling company, devised an elutriation-flotation method for beneficiating the mixed heavy plastics portion of municipal solid wastes which is composed of polystyrene (PS), PET, and PVC. A sodium carbonate brine was used to remove the lighter PS from the heavier PET and PVC. Over 98 pct of the PS was recovered in a high purity PS concentrate containing 99.7 pct PS, The remaining PET and PVC mixture was washed to remove the brine salts that would be harmful to the flotation process. The clean PET and PVC mixture was conditioned in a solution of 45 g/t gelatine and floated in a short (l-m) column flotation cell in an upward flow of water. In a single flotation step, over 75 pct of the PET was recovered in a high purity product containing 99.8 pct PET. The bubbles attached to the PET lowered the effective density of the PET-bubble agglomerate and allowed successful separation of these agglomerates from the PVC plastic pieces. This method separated two-thirds of the mixed plastics fraction into high purity PS and PET products suitable for recycling and left only one-third of the plastics in the mixed plastics product.

Jan 1, 1992

By M. W. Harmer

Laboratory test work, pilot plant testing and plant experience with wet, fine mesh screens is discussed. High frequency, low amplitude, fine mesh, wet screens were installed on the 6th cleaner concentrate stream. These screens produce a 60% oversize recovery split of the molybdenite concentrate that is of leached equivalent quality. The undersize stream is leached with 'hot ferric chloride to remove Pb and Cu contaminates before roasting or shipment to sulfide customers. This plant modification is a good example of using existing technology in an unconventional flow sheet to yield significant cost savings.

Jan 1, 1990

By K. L. Hanning

Grinding and classification circuits at Climax Molybdenum Co. are described. Since the installation of a direct digital control computer in 1974, a number of control strategies were developed and evaluated. This paper deals in particular with the practical experience and results obtained in direct digital control of a wet grinding circuit consisting of a ball mill, constant speed sump pump, and hydrocyclones. For this circuit throughput is maximized, while maintaining a desired product size. Product size is inferred from measurement of operating variables.

Jan 1, 1977

By H. Maleki

Interwest Mining Company has been collecting geologic data within the last decade in preparation for underground mining of extensive coal reserves in its Bridger Coal property in southwestern Wyoming. During a preliminary data collection program in 2000, Interwest Mining completed geologic investigations, including surface mapping, drilling, aerial photography, rock testing, and limited groundwater investigations. Core from 12 exploration boreholes in the area of interest was tested to determine the mechanical properties of the coal seam and the immediate roof and floor for evaluation of the feasibility of underground mining. Geologic investigations identified the presence of one 7-to-17-ft-thick coal seam throughout the reserve under 1400 ft of cover. During a geotechnical feasibility study in 2002, the authors reviewed available data while completing comparative analyses identifying critical deficiencies in these data. The study projected moderate-to-difficult mining conditions, considering the weak nature of near-seam strata and depth of cover, and thus recommended limiting the longwall reserves to an overburden depth of less than 900 ft. These shallow remaining reserves were located at depths within regional mining experience to justify longwall mining methods. Based on a critical examination of available data, Bridger proceeded with more detailed data collection to improve understanding of the depositional and structural setting of the reserve, hydrogeologic conditions, overburden strength, and premining stress conditions. Additional data was collected during 2003 and 2004 field programs. Since 2003, Bridger has had the opportunity to observe ground behavior in a series of up to 1200-1600-ft- long rectangular openings created during highwall mining. These narrow unsupported openings remained stable in the short term in large areas but the overburden subsided locally in the long-term depending on geologic and panel layout designs. These localized subsidence events allowed an examination of in-situ coal strength based on back analyses of stress. The unextracted highwall areas near Ramp 17 provided an ideal location to access the underground reserves using a 6-entry set of mains. The existing north-south oriented longwall layout for the Bridger Coal was selected by Bridger to maximize resource recovery from the D41 reserves while considering operational and geotechnical constraints. At 45-degrees deviation from preexisting joints and mild horizontal stress field, this orientation was considered beneficial for overall stability while using both sets of joints for facilitating the caving process. The present layout utilizes pillars on 80- to 90- by 200-ft centers, 17-ft entry spans and 750-ft wide longwall panels (Figure 1). Gate pillars are on wide spacings and are intended to act as abutment-abutment pillars to limit strata deformation over the gateroads during longwall mining.

Jan 1, 2008

By M. Canty

An innovative biological treatment system designed to detoxify cyanide and nitrate and immobilize metals from cyanide leach operations is described. A pilot-plant demonstration was conducted to detoxify cyanide and immobilize several metals from a process stream at the McCoy/Cove Mine. Testing was performed under the EPA's Mine Waste Technology and Superfund Innovative Technology Evaluation Demonstration Programs. This technology was successful in detoxifying cyanide and effective in removing metals. The pH was consistently neutralized and nitrates were successfully removed. Results show that biological treatment can offer an innovative, cost-effective alternative for the treatment of mining wastewaters.

Jan 1, 1999

By S. Phillipson

The Mine Safety and Health Administration’s Roof Control Division (RCD) evaluated the use of Shuttle Radar Topography Mission (SRTM) data to identify fracture traces on Earth’s surface. Results were compared to the analysis method employed by RCD for 30 years, which relies on LANDSAT-TM Band 4. SRTM elevation models are expected to provide a direct representation of bedrock surface, while LANDSAT-TM Band 4 represents reflected near-infrared radiation as an indication of moisture content and is only a proxy for possible structures. Three areas in southwestern Pennsylvania were chosen for ground-truthing lineaments derived from both methods, following a series of desktop comparisons in six areas of the contiguous U.S. Field studies that identified numerous instances in which SRTM lineaments corresponded with joints at the projected location, and were oriented within 10° of joint strike, indicating that those SRTM lineaments represented the structural grain of the area. In some cases, lineaments were associated with individual joint zones. Photo-lineaments derived from the existing LANDSAT-TM methodology appear to offer a higher coincidence with expected trends of joints on a regional scale when performing the desktop comparisons, while field observations indicated that SRTM-derived lineaments had a higher association with individual geologic structures in the case study field area. It appears that both methods can identify the structural grain of an area, and that both tend to identify linear segments of valleys where erosion has preferentially occurred along joint zones or other structures.

Jul 1, 2023

By F. Qiming

By means of flotation experiments, potential-pH diagram, electrochemical testing and X -ray photoelectronic spectrum (XPS), the main factors (the thermodynamics and the property of surface products) influencing the separation of sulfide minerals (such as galena and chalcopyrite) in the collectorless flotation are studied. The actual conditions (Eh, pH) of separation are not conformable to the results of thermodynamic calculation. The kinetic behavior of oxidation of sulfide minerals and the property of oxidation products are the decisive factors of the separation of sulfide minerals in the collectorless notation.

Jan 1, 1992

By Joseph Fernandez, Luminita Calin

INTRODUCTION The Tunnel and Reservoir Plan (TARP), commonly known as the Deep Tunnel Project, is the daring and unique concept developed by the Metropolitan Water Reclamation District of Greater Chicago (MWRDGC) as a two-phase solution to the problem of waterway pollution and basement flooding due to sewer system backups created by the combined sewer over-flows (CSOs). Phase I, primarily for pollution control, includes the tunnels, shafts, connecting sewers and structures. These Phase I facilities intercept, during wet weather events, the CSOs within the MWRDGC TARP service area. The tunnels and shafts provide temporary storage of the CSOs for subsequent treatment at Water Reclamation Plants (WRP) before discharging into waterways. Ultimately, upon completion of Phase II, the tunnels, located from 45 m(150 ft) to 100 m (330 ft) below ground, will convey the CSOs to reservoirs for storage until WRP capacity is available. Phase II, which includes the reservoirs, pumping facilities, additional tunnels and shafts, has been planned to serve a dual purpose. The reservoirs provide storage of excess flows during wet weather events, those beyond the WRP capacity. Following the wet weather events, the stored flows can be conveyed, at controlled rates, to the WRPs for full treatment. These excess flows previously would have resulted in both overflows into the waterways and eventually backups in the local sewer systems. The storage capacity of the reservoirs also will promote the full utilization of the conveyance capacity of the tunnels and shafts, which in turn results in optimizing the conveyance capacity of the existing sewer systems. Therefore pollution control is further enhanced by allowing for capture of a greater volume of CSOs and greatly minimizing backups in the local sewer systems. The TARP project consists of four systems: O’Hare, Mainstream, Des Plaines, and Calumet, covering a total area of 971 km2 (375 mi2) and serving the City of Chicago and 51neighboring communities as shown in Figure1. With only two contracts left before completion of the Phase I tunnels, the 12.7km (7.9mi) Torrence Avenue leg, to be awarded in 1997, and the 12.4km (7.7mi) Little Calumet leg unfunded as of yet, both part of the Calumet System, the pollution control phase of the project is now 86% complete (Table 1).

Jan 1, 1997

By S. J. Page

The personal dust monitor (PDM) is a combined tapered element oscillating microbalance (TEOM) respirable dust monitor and cap lamp, configured to have dimensions and weight similar to those of a lead-acid miner’s cap lamp battery. The Higgins-Dewell (HD) cyclone design operated at 2.2 L min-1 airflow has previously been reported to have low bias relative to the International Organization for Standardization (ISO) convention. Previous reports have described the PDM as meeting the NIOSH Accuracy Criterion. In order to avoid certain analysis anomalies encountered during these evaluations, a different method of establishing the PDM relative standard deviation was employed. Re-analysis of laboratory data for both the early prototype and precommercial PDMs indicates that the PDM still meets the NIOSH accuracy criterion, and that the precommercial PDMs are more accurate than previously reported.

Jan 1, 2011

By D. Donison

The practice of blasthole mining is typically applied in competent ground conditions, primarily because of the open stope dimensions. At Magma Copper -Superior Mine, a field pilot project was completed examining a variation of blasthole mining in poor ground conditions. The results were very encouraging not only from a technical viewpoint, but also productivity viewpoints. This paper describes the pilot project and the resulting implications.

Jan 1, 1994

By V. P. Keran

Design of the Bajo de la Alumbrera Project started in June 1995 and concentrate production commenced early in the Third Quarter of 1997. The project is situated in North-Western Argentina and is being developed by Minera Alumbrera Limited which is owned by MIM Holdings Limited of Australia (50%), North Limited of Australia (25%) and Rio Algom Limited of Canada (25%). This paper outlines the key features that were incorporated in the design from both process and plant layout perspectives. It explains the background of flowsheet and equipment selection for the plant. A feature of the flowsheet is that it incorporates gravity gold circuits in both primary and regrind circuits for recovery of gold to dore as well as in the copper concentrate product.

Jan 1, 1998

By Robin P. Gardner

The mechanistic or phenomenological approach to ball milling involving the, concepts of particulate selection and breakage functions with particle population balance models has been well established over the past decade (c.f., the review articles by Austin (1) Herbst and Mika, (2) and Snow (3)). Initial efforts to apply this approach concentrated on batch milling, but since most milling in industrial practice is continuous, much recent research has been directed to extending this approach to continuous milling. The primary difference between batch and continuous milling processes is the relative importance of material mixing and transport in the mill in the latter case. Much analytical (4-8) and some experimental (9-15) work on the effect of mill mixing and transport on milling has been recently reported. Much of the analytical work has naturally centered around extension of the well-developed concepts that have been applied to chemical reactors, (16-18) Fortunately, it has been found(1) that most milling processes are analogous to first-order chemical reactions so that the combined effects of material transport and reaction (breakage) can be handled by the relatively simple segregated flow concepts. (8)

Jan 1, 1973

By A. Röttger, W. Theisen, J. Küpferle, M. Alber

"Wear of TBM tools significantly affects tunneling advance rates. Wear-prediction models are based (amongst others) on the abrasivity of the present geology, which is determined via laboratory tests. To evaluate the results from such tests in context, this work considers the tribological system TBM tool from a materials technology perspective. In so doing, the microstructures of different application-oriented materials are presented and discussed in terms of their wear behavior and wear resistance. The significant influence of tool materials on the abrasivity of the geology and thus wear prediction models has already be identified. LCPC, Cerchar and nano-scratch experiments have been performed as confirmation. Material-dependent wear mechanisms and their correlation in terms of tunneling have shown that it is mandatory to consider the complete tribological system to estimate the wear of TBM tools. 1 INTRODUCTION Mechanized tunneling is vital to ensure necessary infrastructure development in megacities like Tokyo (Bay Tunnel), Istanbul (Eurasia Tunnel) and Mexico City (Tunnel Emisor Oriente). The use of Tunnel Boring Machines (TBMs) has been established for many years. In contrast to other methods such as boring and blasting or excavation using dredgers, tunneling with TBMs allows simultaneous excavation and removal of both the mineral and tunnel lining by tubbing segments or shotcrete. This makes tunneling more efficient, allowing for faster development of the tunnel in both hard rock and soil [1]. When budgeting such tunneling projects, precise planning and coordination in terms of tunneling technique choice (e.g. EPB or Slurry-shield), the relevant geology, and the associated penetration rates and tool wear are required. In particular, wear to TBM tools has a significant impact on tunneling progress. Due to wear, tools become dulled or lose their functionality because of brittle material behavior, thus reducing penetration rates and therefore tunneling efficiency [1]. As a result, additional tool changes are necessary, leading to higher overall costs due to down times and maintenance costs. Therefore, there is strong interest in a reliable and precise wear prediction model for TBMs. As already mentioned, the geology and associated wear of the tunneling tools define the maintenance times."

Jan 1, 2016

By Z. Scopa, E. Tarshizi, R. Setterlind, L. Frost, R. Livernois

"THE MINES OF THE FUTURE The mines of the future present a host of challenges, which may appear exciting or daunting depending on one’s perspective. Whether some sectors of the public recognize it or not, the demand for raw resources is not going away any time soon. In fact, it is rising as global population grows, urbanizes and attempts to steadily increase quality of life. Yes, at the same time that much of the highly developed world is calling for greener goods, reduced consumption, and cleaner production, in other areas there are cries for clean water and sanitation, consistent energy supply, access to health care and education, personal security, and support for basic human rights. The balancing act for sustainable development of our global society is indeed precarious, and the mining community is necessarily a key player. Fortunately, many industry members have accepted this role and the responsibility to provide leadership and a solid foundation for progress. Looking ahead, we need new generations of leaders, many of whom will be mine engineers, which are ready to tackle all sorts of complex problems. There are tremendous needs just for technological innovations. Increasingly tough deposits will require that we continue to expand scale toward “super” pits and “deep” underground mining fully develop unconventional recovery techniques like in-situ leaching and gasification or deep-sea extraction, and seriously consider off-earth endeavors. Such work will take entirely autonomous equipment; novel separations, processing and recycling methods; and systems that can withstand extreme physical conditions – just to name a few. It will also take a level of systems integration never-before seen in our field, complete with big data issues, sophisticated analytics and modeling efforts, and cyber-security challenges. Moreover, increasingly complex environmental problems will require creative solutions. Addressing issues like pollution control across multiple media, emerging contaminants, optimal management of wastes, selective mining, and shared use of resources between mine operations and surrounding communities and ecosystems are among top priorities. Really, a complete paradigm shift must occur, such that our focus is on overall improvement of environmental conditions, rather than minimization of impacts. A similar shift will be required in the social realm. How can we make miners safer and healthier on-site and off? How can we contribute to communities such that they are better off, now and long-term, for having a mine next door? How can we help transform artisanal mining practices to also contribute to sustainable development? How can our work be a factor in increasing economic and political stability? How can we improve the public understanding of raw resources and the need for mining enterprises?"

Jan 1, 2017

By J. D. McKay

Flotation columns have been readily accepted for use in most sulfide flotation plants; however, recently columns are being used in many other areas. Recent improvements in design methodologies have overcome many operating problems and led to improvements in metallurgy. In addition, physical improvements in column design have simplified their operation while leading to better control. The Turbo-Air External Bubble Generator has provided a method for bubble size control and variation in air holdup and carrying capacity. These have enabled commercial operations to improve grades and recoveries by optimizing performance.

Jan 1, 1990