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By M. Bennett, L. Twidwell

Montana Tech has embarked on a coordinated series of studies to delineate the characteristics of the Berkeley Pitlake containing over 36 billion gallons of acidic, metal-contaminated water formed after the cessation of open-pit copper mining in Butte, Montana, USA. The objectives of the overall series of studies are to summarize presently available information and to generate new and needed information to formulate a conceptual environmental model for the pitlake and to provide characterization data for the development of advanced treatment technologies. In this presentation, the chemistry of the Berkeley Pitlake water is partially reviewed. It is known that the pitlake consists of two distinct layers of water referred to as surface and deep water. Samples of deep water were collected and placed in a 12-ft high and 6-inch diameter column and exposed to different wavelengths of UV radiation as well as atmospheric conditions. Measurements of pH, redox potential (EH), dissolved O2, turbidity, conductivity, temperature, and elemental composition show that the water reacts differently and indicates that the diurnal effects of sunlight likely play a major non-biological role in its chemistry. Resulting technology could be useful for developing an alternative to treating acid-rock drainage.

Jan 1, 2007

By F. Calizaya

This paper describes the basic requirements for the utilization of belt air to ventilate working sections at remote locations in relation to the main fans. It highlights the risks involved, potential problems, and the provisions that must be followed by mine operators for the safe use of belt air. The paper also presents a brief review of the current regulations, conveyor belting tests, atmospheric monitoring system requirements, and the experience gained by mine operators to utilize the belt entries to ventilate remote working sections or areas where mechanized equipment is being installed or removed. The paper concludes with a set of recommendations with respect to the utilization of belt air and the composition of belt material in under-ground coal mines.

Jan 1, 2008

By D. L. Murr, J. R. Jensen

Testing was conducted on a Minnesota Iron Ore concentrate with Cook Clay as a binder using compressive sheer mixing to enhance the performance of the agglomeration mechanism. The testing was conducted on a bench scale at the Midland Research Center the summer of 2004. Results of the test program will be presented that shows the impact of compressive sheer mixing had on the strength achieve in a green ball.

Jan 1, 2006

By Robert E. McIvor

The Functional Performance Equation for Ball Milling” was first presented in 1988. It now has been used successfully in more than a dozen mineral processing plants. This powerful, yet simple tool provides a new level of understanding of closed circuit grinding. It shows how grinding circuit efficiency is in reality comprised of two distinct efficiencies. It demonstrates how circuit production rate is related, collectively, to these two efficiencies, mill energy input, and the grindability of the ore. It links circuit performance to design and operating variables that can be manipulated, and creates an effective strategy for making plant improvements. This paper covers the derivation and industrial validation of this equation. As part of an engineering and management system that also incorporates suitable metrics and process control, other operators can now use this tool to make improvements and to manage the performance of their grinding operations with clarity and confidence.

Jan 1, 2005

By Doug Harding

The Niagara Tunnel Project (NTP) is a 10.4-km- (6.5- mile-) long, 14.4-m (47.5-ft) bored tunnel that will run under the city of Niagara Falls from the Upper Niagara River to the Sir Adam Beck power station. The completed project will enhance the capacity of the Sir Adam Beck power station by adding 500 m3 /sec (17,657 cu ft/sec) of water through the tunnel. The project uses the world?s largest hard-rock tunnel boring machine (TBM) at 14.4 m (47.5 ft) in diameter to excavate the tunnel. Features of the project include the use of a high performance (HP) main beam TBM, state-of-the-art ground support and tunnel logistics systems. A continuous conveyor is used for muck transport from the TBM to the disposal area In June 2004, the Ontario government announced that Ontario Power Generation (OPG) had been given approval to proceed with the third tunnel under the city of Niagara Falls ? the first two tunnels were constructed in the 1950s using drill-and-blast techniques. The third tunnel, appropriately named the Niagara Tunnel Project (NTP), consists of a 10.4-km- (6.5-mile-) long TBM-bored, concrete-lined tunnel with a finished diameter of 12.5 m (41.1 ft). In August 2005, OPG the selected of Strabag of Austria, one of the largest construction companies in Europe, as the contractor to build the NTP at a price of C$600 million. In September 2005, Strabag selected The Robbins Co. of Solon, OH to design, manufacture and deliver a new 14.4- m- (47.5-ft-) diameter high performance, state-of-the-art main beam hard rock TBM to be used in the excavation of the tunnel. To meet the aggressive construction schedule as requested by OPG/Strabag, the TBM needed to be sup-plied as ready-to-bore within a 12-month period after the contract was awarded to Robbins.

Jan 1, 2008

By Mark R. Svinkin

Construction vibrations may adversely affect surrounding buildings and their effects range from human discomfort and disturbance of sensitive devices to visible structural damage. There is no unique conclusion regarding the effect of construction vibrations at every site. Measurement is usually made to monitor vibrations and control them with the vibration thresholds for disturbance of sensitive objects as well as damage to structures. To prevent potential litigation and mitigate the vibration effects on sensitive devices, people and structures, it is necessary to manage and minimize vibration problems before the beginning of construction activities or installation of vibrating machine foundations, and during construction. Pre-construction damage survey and engineering vibration investigations, including the prediction of anticipating vibrations, have to be made at most construction sites in advance of construction activities. Vibration monitoring and control have to be provided during construction. The instrumentation feedback of vibration prediction, monitoring and control provide the basis for choice of measures to prevent or mitigate vibration problems and settlement damage hazards.

Jan 1, 2002

By Jacques Nantel

Mechanization has been at the core of productivity improvements since the industrial revolution. During the past 20 years, mining has derived spectacular progress from mechanization. In the future, however, mechanization alone will not be enough. In the next few decades, automation will bring about new generations of highly productive and safe machines, with low operating costs. Increased use of new and better technology is generally accepted as the prime factor capable of closing the productivity gap. The productivity gap is the difference between inflation and metal prices. The three S-curves in Fig. I represent the evolution of technology in general, and mining in particular. TI represents incremental changes. the dominant sort of technology changes in the mining industry: - Better drills, electric hydraulic drills vs. pneumatic drills, the drilling rate is twice as fast. - Better steel and bits, to accommodate the higher performance drills. - Improved chemical explosives. - Bigger trucks in open pits.

Jan 1, 1993

By Mikko Ruonala, Pertti Lamberg, Olli Hyvärinen

The smelting of copper sulphide concentrate is the dominant route in copper production (Figure 1). Heap leaching of oxidized copper ores with weak sulphuric acid together with copper solvent extraction and electrowinning has gained popularity during recent decades, and it accounts for close to 20 % of primary copper production. Heap leaching offers advantages such as lower costs and consequently the construction of a production plant at a mine site is made possible. Limited resources of oxidized copper ores, the long leaching time of chalcopyrite and inability to recover gold inhibit this growth. The HydroCopperTM process developed by Outokumpu Technology at the laboratories of Outokumpu Research, Pori, Finland, is a new chloride leaching technology /1,2/, which offers an alternative to smelting and heap leaching (Figure 1). In the HydroCopperTM process sulphidic concentrates with various mineralogy and grade can be treated at the mine site to produce high-quality copper. Instead of copper cathodes the HydroCopperTM end products are copper wire rod, copper bars or copper billets. One of the advantages of HydroCopperTM technology is that gold can also be recovered in the process simultaneously /3/. To confirm the functioning of the new process and to dimension equipment Outokumpu Technology built the HydroCopperTM demonstration plant in Pori, Finland /4/. It has a capacity of 1 metric ton of copper per day. After testing with Pyhäsalmi copper concentrate in 2003, the first commercial demonstration run with Erdenet copper concentrate took place in 2004.

Jan 1, 2005

By P. A. Olubambi1

Representative samples of the hydrothermal vein deposits of the bulk complex sulphide ore deposit, 10 km south of Ishiagu, in Ebonyin State, South Eastern part of Nigeria were collected from two small scale mining companies. The samples were mixed and successively crushed in a jaw crusher and cone crusher, and ground in a rod mill. Characterization was carried out with SEM, EDX, XRD, XRF and ICP-OES. Mineralogical analysis revealed the presence of sphalerite, galena, siderite, pyrite, quartz and chalcopyrite. X-ray Diffractometry showed that sphalerite mineral in the ore occurs as sphalerite ferrous with varied percentage of Zn and Fe within the various sizes while chalcopyrite occurs as a chalcopyrite group mineral with chemical formula Cu2MnSnS4. Results of the elemental analysis showed variations in elemental composition within the different sizes.

Jan 1, 2006

By M. M. Gilkey

This report describes the effects of water shortage on Arizona's mineral industries. The information presented was obtained in interviews with company representatives. Operations covered included all State metal mines using substantial quantities of water and all concentrators and smelters. Also included in the survey were 8 operations in the nonmetallic group; 22 in the plating, metal-fabricating, and metal-forming categories; 1 public-utility power company; and 6 water companies. The extent of the water shortage in Arizona is reflected in mineral- industry water-use practices, in the high cost and low quality of water used at many operations, and in the stringency of State control of well drilling and pumping. Many mineral-industry operations are among those users most seriously affected by the uneven water supply.

Jan 1, 1963

By M. M. Gilkey

This report describes the effects of water shortage on Arizona's mineral industries. The information presented was obtained in interviews with company representatives. Operations covered included all State metal mines using substantial quantities of water and all concentrators and smelters. Also included in the survey were 8 operations in the nonmetallic group; 22 in the plating, metal-fabricating, and metal-forming categories; 1 public-utility power company; and 6 water companies. The extent of the water shortage in Arizona is reflected in mineral- industry water-use practices, in the high cost and low quality of water used at many operations, and in the stringency of State control of well drilling and pumping. Many mineral-industry operations are among those users most seriously affected by the uneven water supply.

Jan 1, 1963

By C V. B Cunningham

The assessment of blasting results under production conditions is extremely difficult. As a result, it can take months or years to establish objective and valid estimates of explosive performance in achieving rockbreaking goals. This fundamental problem often results in decisions related to the manufacture, marketing, purchase and use of explosives being largely swayed by calculated energies from detonation codes. However, these codes are by no means standardised. Different energies are given by different codes because these employ varying combinations of fundamental science and empiricism. After a basic review of code operation, important guidelines to dependability are given with reference to ICI’S state-of-the-art codes IDEX and CPEX. Distinctions are drawn between Ideal, Non-Ideal and Blasting Codes. Concepts of explosive energy are discussed in brief.

Jan 1, 1991

By Wolfgang G. Brunner

A 3800 m long temporary water-retaining dike has been constructed under extreme conditions in the harsh northern climate to enable two of the kimberiite pipes at the Diavik Diamond Project reserve to be mined using open pits. The Diavik Diamond Project is located on East Island at Lac de Gras in Canada's Northwest Territories, approximately 200 kilometres south of the Arctic Circle. The dike which has been constructed in up to 25 m deep water from crushed granite quarried from the site projects into Lac de Gras encircles the first two of the kimberiite pipes to be mined. An 800 mm wide diaphragm cut­off wall constructed of bentonite, cement and crushed rock, totalling 33,000 m2, and a two-phase jet grouted curtain wail at its base, totalling 8,400 m2, have been installed through the dike and underlying till foundation into bedrock. The cut-off is designed to minimise water seepage from Lac de Gras through the dike. In order to ensure that the dike had adequate internal stability and diaphragm wall construction could proceed safely, the crushed rock fill material dumped into the lake was first compacted by TR 75 deep vibrators. In 2000, Bauer Maschinen GmbH of Schrobenhausen, Germany were awarded the contract for the supply of all specialist foundation equipment required on site and for providing technical support to the Canadian main contractor Lac-de-Gras-Construction throughout the construction of the cut-off walls during 2001 and 2002. Installation of the cut-off walls was completed in July 2002, three weeks ahead of schedule, and dewatering of the inner dike areas commenced just 5 days later and has continued throughout August and September. After completion of extensive testing of the diamond recovery plant, the mine is scheduled to go into full open pit production in February 2003.

Jan 1, 2003

By Michel G. Grenier

Compliance with Diesel Particulate Matter (DPM) exposure regulation is currently performed using timeweighted average (TWA) sampling on underground mine workers. These samples are collected in the span of an entire shift and the resulting concentrations are compared to a legislated exposure limit. While this is very useful to determine the exposure level of an individual to DPM, it fails to clearly identify causes of exposure and highlight opportunities that could help reduce the exposure of workers in the course of the work shift. Real-time DPM monitoring measures the worker?s exposure as a function of time and helps identify circumstances where corrective actions can be taken or design changes can be made by the individual or the employer to reduce the overall exposure of the worker and peers. This work focused on obtaining DPM concentrations using a real-time polycyclic aromatic hydrocarbon (PAH) monitor. The aim was to demonstrate that this instrument, while not a direct DPM analyzer, was able to provide a concentration profile that could easily be linearly correlated to standard TWA elemental carbon measurements. In addition, several instances of improvements that could be implemented to reduce the exposure of underground employees were demonstrated.

May 1, 2010

By G. Abramov

The 20th Century saw the modern mining industry enriched by one outstanding method of extracting of mineral resources called Borehole Mining (BHM). Mean while, despite its successful track record in wide ranging locales, few specialists are yet aware of this technology. The intent of this article is to introduce borehole mining to a wider spectrum of drilling and mining professionals. The BHM method is based on in-situ water jet cutting of rock mass. On Fig. 1 the schematic of the method is presented. The borehole mining tool 1 is lowered into the borehole 2 and high pressure water 3 is pumped down. At the bottom part of the tool, one portion of that water comes out through the hydromonitor nozzle 4 in a shape of water jet 5 and cuts the material 6 creating slurry 7. The other portion of high pressure water then comes to the hydroelevator 8 (jet pump, eductor) which produces a vacuum. When the slurry reaches this vacuum zone, the eductor sucks the slurry and pumps it up to the surface, where rock parts are separated from water in a tank 9 or a pond and clarified water is pumped down again closing the re-circulating BHM water supply system. The borehole mining tool is suspended on a drill rig tower 10 which allows the tool to rotate and move vertically along the borehole axis. While extracting rock mass, underground caverns (stopes) 11 are created. If necessary, compressed air 12 can be injected to the raising slurry flow to create an airlift effect. Also, a secondary agent 13 (such as oil, foam, etc.) can be added to the stope through the gap between the tool and the casing. As seen from the illustration, BHM is the remote mining method of extracting of mineral resources through boreholes by high pressure water jets.

Jan 1, 2001

By O. Naiker, T. Riley

Keywords: Pyrometallurgy, furnace, Xstrata, ferrochromium, Premus Technology The presentation will give a basic overview of Xstrata Alloys. Included will be a brief history of the Alloys division as well as of each plant within the division. The Xstrata chrome plants utilise a wide variety of production processes, including Xstrata's Premus process, the Outokumpu process, and the conventional process. Xstrata?s Lion Project is underway, with commissioning expected in the third quarter of 2006. The new smelter will utilize Xstrata?s patented Premus process, and the competitiveness of the Premus process is discussed.

Jan 1, 2006

By Jurgen te Kook

State-of-the-art for subsidence calculation are stochastical models. Although these models were successfully used all over the world they have their limitations due to the fact that they are not based on mechanical laws. For example the models did not take the rock mass structure and the rock mass characteristics into account. Therefore in a research program the skills of geomechanical numerical models for subsidence calculation were investigated. A case study shows that numerical models which are in principle based on the elastic theory are suitable for subsidence prediction. Due to the principles of these models the results are not sufficient in the case of multiple seam extraction. More extended geomechanical numerical models like FLAC and UDEC were investigated in further steps of the research work. Up to now large area geomechanical models require unrealistic long calculation times if the level of detail is similar to that of small scale calculations. Due to this it was necessary to implement a simplified description of the rock mass structure and characteristics. Different case studies show that this approach is successfull for subsidence calculation by numerical geomechanical models even for multiple seam extraction.

Jan 1, 2008

By Jim Wickens, Andy Cole, John Pekrul

"The roaster facility at Barrick Goldstrike Mine treats double-refractory sulfidic/carbonaceous gold ore. Prior to oxidation in the roasters, the ore is ground in two parallel dry grinding circuits utilizing 19’ Ø x 75’ double rotator mills. The design plant throughput was 12,000 dstpd. However, process improvements have significantly increased throughput rates by 25-50%. The current daily throughput record is 20,078 dstpd. Grinding circuit improvements contributing to this success include feed size reduction, ball size optimization, automatic ball charging optimization, and operating strategy changes. In addition to the changes already made, this paper discusses future optimization initiatives including on-stream particle size analysis and “real-time” ore hardness determination techniques.INTRODUCTIONBarrick Goldstrike Mines is located 29 miles Northeast of Carlin, Nevada, USA. Through 2001, the property has produced over 23 million ounces of gold making it one of the premier gold operations in the world.Prior to Barrick’s ownership, the property began producing gold from a small heap leach operation in 1975. The small-scale heap leach production continued through 1986, and in January 1987, Barrick acquired the property. Increased exploration activity by Barrick significantly increased gold reserves. In August 1988, a 4,500 dstpd mill facility was commissioned to treat high grade oxide ore. Also, heap leach operations had significantly expanded. In 1990, the mill was expanded to 6,000 dstpd, and the first autoclave was commissioned to treat refractory sulfide ore. By the end of 1996, the mill and pressure oxidation facility had expanded to 16,000 dstpd and heap leaching had ceased as oxide reserves were exhausted. In 2000, a roaster facility was commissioned to treat double-refractory sulfidic/carbonaceous ore."

Jan 1, 2003

By Carl Lubbe, Ron Frye, Wayne Curtis, Julie Pecori, Dan Leach

Blasting conducted in the USA using the new Electronic Initiation System developed by Altech has shown that an accurate delay system will benefit the customer. Results from test work clearly showed that improved fragmentation was effected and blast vibration was at least similar to that currently found at the test venue with improvements possible.

Jan 1, 1997

By A. Korchevisky

Environmental self-monitoring is one of the advanced approaches for industrial sustainability programs. Organization for Economy Cooperation and Development (OECD) defines self-monitoring as ?the system of organizational and technical measures put in place and financed by [the] regulated subject? in order to ensure their compliance with regulatory requirements?1. Self-monitoring is beneficial for industrial operators, communities, and governments. Industrial companies use self-monitoring as a central element of their compliance management that allows them to fulfill their duties, obligations, and to avoid citations. When industries control their emissions and ensure workers are not exposed above the regulated limits, communities are better. It is impossible for an EPA, OSHA, or MSHA inspectors to be close to every emission source or workplace full-time. It is much more effective for industries to self-monitor, under due supervision. Occupational conditions are a very important part of industry and health and safety self-monitoring should be highly prioritized. In this paper we will research the regulatory basis and best practice of occupational self-monitoring. We will show that not only is self-monitoring a vital element of an occupational health & safety management system, but that you need a management system for affective monitoring.

Jan 1, 2012