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By S. B. Bealko

In response to recent mining disasters and new mine rescue team legislation, NIOSH researchers conducted meetings across the United States with mine emergency response experts to investigate current needs and issues. Some of the issues include emergency response preparedness, mine rescue contests, real-life training capabilities, and training facilities. Many new teams are being formed that must be trained for mine rescue team competitions as well as be ready to respond to a variety of mine emergencies including a fire or explosion, a massive roof collapse, mine inundations, or vertical shaft rescue situations. Therefore, it is important that these teams are adequately prepared and trained. This paper presents a summary of domestic and international coal mine rescue training facilities and identifies those that provide unique, real-life, and/or state-of-the-art training. Research findings from this report will be used in further NIOSH investigations to improve coal mine rescue training. DISCLAIMER: The findings and conclusions in this report are those of the author(s) and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Jan 1, 2009

The ability to optimise a concentrator from mill feed to final products requires a simulator which integrates comminution, classification and separation modelling. In order to model this range of processes, such a simulator must handle a variety of information about the ore. The AMIRA P9 project has developed a whole-of-concentrator simulation capability which brings together a texture-based model of mineral liberation, quantitative X-ray micro-tomography analysis to measure the inputs required by this model, and a multi-component simulator software framework. In the context of this approach, the term ?multi-component? implies the ability of the simulation to handle many particle properties simultaneously; for example size, composition, density, floatability etc. The simulation software framework provides the means to manage the flow of data around a circuit flowsheet, allowing each process model to access the information relevant to that particular model. A case study based on plant data from a gold-bearing pyrite concentrator is used to demonstrate the capabilities of the multi-component approach in simulating circuits which contain comminution and separation processes.

Feb 27, 2013

By F. Calizaya

The PT Freeport Indonesia‘s Deep Ore Zone(DOZ) copper deposit is located in the province of Irian-Jaya, Indonesia. Currently, a block cave mine is being developed around this deposit. Production is scheduled to start in year 2000 and to ramp up to25,000 tpd by year 2003. The air quantity requirement for this mine is equal to 780 m3/s. To supply this quantity, the mine will require five centrifugal fans (one 450 and four 750 kW fans). This study summarizes the technical aspects related to the installation and commissioning of one of these fans. The fan was installed on the surface in a parallel arrangement with two others. It has a design capacity of 240 m3/s of air at 2.2 kPa of static pressure. The study presents the installation details from the underground shaft excavation and portal development through fan testing and commissioning. It also presents the results of a monitoring system that was installed to determine the fan duties.

Jan 1, 2000

By Kenneth G. Colman

Even though wet processes were used in coal preparation plants prior to 1941, dewatering coal was not a problem then because the finer sizes were uneconomical to recover and were considered waste. However, during the war years the scarcity of raw materials necessitated the utilization of every pound of natural resources and coal plants began seeking an economical mans of recovering fine coal. Early efforts to this end concentrated primarily on centrifugal dewatering devices. Such equipment produced good results but was relatively expensive. In 1944, a method was devised utilizing a vibrating screen fitted with a profile wire deck rather than the standard woven wire cloth deck. This machine came to be referred to as a dewaterizer. Results obtained with the dewaterizer approached those of the centrifugal equipment, but at a lower capital cost, Their use reduced either the number of centrifugal units required to follow the dewaterizers or the required energy input to heat dryers, In some cases they eliminated the need for any further dewatering equipment.

Jan 1, 1970

By O. MacIntosh

The Round Mountain gold mine, located 90 km (55 miles) north of Tonopah, Nevada began large-scale production in 1977. During 2008 Round Mountain Gold Corporation (RMGC) relocated the primary crusher facility approximately 300 meters (1,000 feet) to make room for the next phase of open pit mining activities. This facility was installed in 1988 and used a log-crib retaining wall and dump pocket RMGC selected Hilfiker Retaining Walls and Collins Engineers, Inc. to provide design and materials for a new 17 meter (56 feet) high Mechanically Stabilized Embankment (MSE) wall to support the haul trucks at the new location. The construction contractor was EarthTech West Ltd. of Norwood, Colorado. An MSE wall with a cast-in-place concrete face was chosen as a durable, yet less expensive alternative to the reinforced concrete dump pocket that was originally designed for the project. The arrangement of the MSE wall is of an unusual configuration to meet a variety of operational and maintenance requirements. This paper outlines the selection process, design, and construction of the MSE wall.

Jan 1, 2009

By K. Grubaugh

Ghana’s physiographic and geologic features are the basis for its long mining history. The Gold Coast colony has been a significant producer of gold. The gold of the Akan forest (Ghana) was a terminus for caravans that plied Saharan trade routes. Now it also produces significant quantities of manganese, bauxite, and diamonds In addition, the country produces kaolinite, silica for glass, salt, and both aggregate and dimensioned stone. Most secondary minerals are consumed locally but some amounts do find international markets. Ghana revised the mining laws and regulations in 1986. These revised laws dramatically increased gold production and improved the country’s economy. The success of these laws spawned imitators in other African states such as Cote d’Ivoire, Mali, and Burkina Faso. Representatives of these countries claim Ghana was their model. Environmental regulations exist but an intensive adversarial atmosphere is lacking. Ghana has also offered the mining industry incentives like accelerated depreciation rates and exemption from import duties on related supplies and capital equipment. The country has also pursued an aggressive policy to restore the nation’s business infrastructure.

Jan 1, 2001

By M. Fan

Froth flotation is the most widely-used method of separating fine coal, especially coal with coking properties. However, froth flotation is not efficient for treating ultrafine coal and coarse coal particles. Our previous fundamental test results demonstrated that cavitation-generated nanobubbles can significantly improve coal and phosphate flotation performance over a wide particle size range. In this study, the effect of nanobubble on the flotation performances of different particle size fractions of coal was investigated using a bank of 10-liter flotation cells, a specially designed 50 mm inside diameter column and a 152 mm inside diameter column. It was found that nanobubbles that were either directly formed on or subsequently attached to the surface of coal particles during coal froth flotation process improved flotation efficiency. The use of nanobubble in a bank of mechanical cells flotation and column flotation significantly increased the flotation recovery at a given product grade. Nanobubbles increased the flotation rate constants of different coal particle sizes. The presence of nanobubbles in flotation slurry could extend the lower and the upper particle size limits for effective coal flotation.

Jan 1, 2012

By G. E. Agar

In the April issue of Mining Engineering there is a technical note "New size laboratory ball mill for Bond Work Index determination" written by M. Nematollahi which is very confusing. My recollection is that a description of an experimental procedure should be such that someone skilled in the art should be able to reproduce the results. Applying this test to this particular article would according to me cause a failure to be registered. There are apparently three batch laboratory test procedures referred to in the article. One of these is the traditional Bond test with all its limitations such as dry grinding followed by exclusively dry screening, two attributes which fail to simulate conventional industrial grinding. There is a second procedure (NSBM) which the author is advocating as an improvement of the Bond procedure but from the description I doubt that anyone would be able to repeat the procedure. For instance, is the grinding to be done wet or dry, if wet at what pulp density, and how is the screening to be done, wet or dry or a combination?

Jan 1, 1995

By F. M. Jenkins

Improvements in miners? safety and health, as reflected by injury and illness statistics, have reached a plateau and even been reversed. Research into miners' OSH is a necessary adjunct to regulatory enforcement. Under the National Occupational Research Agenda (NORA) mining experts have come together to draft a national agenda for this research. The Mining Sector Council, one of ten NORA Sector Councils, has produced a draft national research agenda to guide all mining research entities: academia, government, and industry. The agenda has seven major objectives, each of which has a sequence of sub-objectives: Reduce the likelihood of disasters in mines; Improve mine disaster response; Improve the health of miners; Improve atmospheric control (ventilation) in mines; Improve health and safety through behavioral research; Improve mine design, systems operations, and management performance to enhance mine health and safety; Apply ergonomics, human factor engineering, to increase health and safety. Long-term maintenance of the Mining Research Agenda requires input from the public, both here and abroad, monitoring of the impact of research results using OSH data, and partners who will translate the research to practice.

Jan 1, 2012

By Ray E. Williamson

One of the prime objectives of the mine industry is to develop a low cost way to clean up what has been called "The Rape Of Mother Nature". The project falls under the broad umbrella of reclamation, which is now considered an essential part of the mining cycle. As such, it is being given full consideration in the initial planning of all surface operations. In most areas, if a proposed mining system does not lend itself to proper reclamation, it is not an acceptable system. By combining mining and reclamation plans, a producer not only can minimize reclamation costs, but can also restore the land to usefulness and insure continuing profits after a deposit is depleted. As long as fifteen years ago, many of the larger mining companies were already deeply involved in this extra cost work. Even then the involved companies were projecting a great need for a bigger bulldozer, Bigger than anything commercially available. At that time, the D9 tractor weighed about 60,000# bare weight.

Jan 1, 1975

By Charles J. Johnson

The United States is totally dependent on imports for all primary chromite and most ferrochrome supplies. Although the United States imports chromite and ferrochrome from a number of countries, the long-term future of chromite supplies appears to lie in southern Africa (Republic of South Africa and Zimbabwe) where 88 percent of known world reserves exist. Floreover, low mining costs and the availability of low-cost electricity for ferrochrome production gives South Africa a comparative advantage over most other chromite and ferrochrome-producing nations. A well-known problem faced by the United States is that when viewed from a longer-term perspective, the major sources of supply of metallurgical grade chromite and ferrochrome may be subject to disruption. The three countries that have caused the greatest concern have been the Republic of South Africa, the Soviet Union, and Zimbabwe. South Africa presents a particularly difficult problem because it may be subject to internal political unrest and/or U. N, economic sanctions. South Africa has increased its share of world chromium production from about 30 percent in 1968 to 62 percent in 1978.1

Jan 1, 1982

By Christian F. Baiz

A new agenda has risen. Born out of governments' policies and world economies, the years ahead will carry with them reduced growth. For inflation dependent and capital intensive industries, such as metals and mining, as well as most other natural resource industries, a period of long-term contraction in outmoded and costly capacity will evolve. This will be supplanted by new, lower cost capacity in some cases, but only if the total cost of production, including cash operating and debt service costs comes in at or below current market conditions. The industrial outlook can be characterized as bearish. As one major U.S. bank economist put it, mining companies planning their five-year forecast from 1984 out, should take the current market conditions and straight-line them to the end of the decade. With low growth and low inflation, the real price of metals will remain flat or slightly declining. As a result, capital funding will be problematic. The low cost producer, that is one with low cash costs and low principal and interest costs per unit of production, will succeed.

Jan 1, 1984

By Stefan Zanon, Ty Faechner, Clayton V. Deutsch

Secondary data are important in geostatistical simulation of continuous variables. Geophysical data and geological trends are used for modeling porosity and permeability. Multiple mineral grades must often be modeled for mining applications. Sequential Gaussian simulation (SGS) is often used because of its relative simplicity and robustness. The two most common approaches to integrate secondary data in Gaussian simulation are with (1) locally varying mean, or (2) collocated cokriging. A significant problem with both of these techniques is variance inflation, that is, the variance of the resulting simulated values is too high because of an inappropriate decision of stationarity or an artifact of choosing a single secondary data in presence of many. We introduce a self-healing procedure for dynamic correction of this problem. The dynamic correction is different for the locally varying mean approach and for collocated cokriging since there are different reasons why each of these methods causes variance inflation. The reasons for variance inflation are discussed and the self-healing is applied to a number of data sets.

Jan 1, 2002

By A. J. Benham, H. Kessler

In the UK a high proportion of land-won sand and gravel is extracted from sub-alluvial gravels and river terrace gravels located within river valleys. However, extraction from deposits of this type is increasingly proving to be less acceptable. Quarries within river valleys often have a high visual impact and the cumulative impact of these operations in close proximity to each other can be high (figure 1). River valley operations are almost always restored to open water. Whilst these may be attractive for nature conservation and provide leisure activities, they can also have a serious impact on the natural hydrology of the flood plain. Wet restoration of quarries located close to airports or airfields can also lead to concerns regarding increased risk of bird strike on aircraft. The Civil Aviation Authority recently suggested that an exclusion zone of 13 km be applied around all airports and airfields to reduce the potential for bird strikes on aircraft. This action is likely to have a serious impact on the availability of potential sand and gravel extraction sites in river valleys.

Jan 1, 2005

By J. Hunter, E. Jackson

This paper describes work done by Placer Dome Technical Services Limited, a subsidiary of Barrick Gold, and Nautilus Minerals Inc. in support of the conceptual design of a subsea mining system. It describes an overall concept design plus specific studies into mechanical excavation at depth. The concept design includes one or more subsea excavators connected to a suction riser, which transports the cut material to a shipboard dewatering and offloading system. A multi-phase investigation was performed into the mechanical excavation of seafloor massive sulphides at depths of around 1600m. Rock samples were recovered and tested for rock properties and cutting behaviour. A small pick drum cutter was procured and tested on a representative concrete slab in a lab and tested again while submerged in a test tank. Finally the cutter was tested on a massive sulphide ore body at 1600m depth. The cutting performance results, e.g. pick forces and specific energies, should provide valuable input to the design of future full scale subsea mining systems.

Jan 1, 2007

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of topdown managerial practices: reductions in production volume, employee layoffs, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefits are often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost-cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization's various constituencies with this direction, and motivate and inspire the organization. Cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2002

By Sean E. Armstrong, Deepak Malhotra

The current trend in gold ore processing is the development of lower grade or highly refractory deposits. The perplexity of treating low grade oxidized ores has been adequately addressed by heap leach technology. However, refractory gold ores are very difficult to positively characterize the gold association within the mineral matrix. Gold accompanied with refractory sulfitlc or carbonaceous mineralization can often be sub­micron In size and occur interstitially. Mineralogical examination of these ores Is difficult, expensive, and occasionally Inconclusive. Hence, the metallurgist Is given little information for the selection of processing alternatives. The purpose of this paper Is to demonstrate the use of diagnostic leach procedures to assist the metallurgist' s decision-making process to solve some of these problems. By sequentially liberating and/or leaching gold associated with specific minerals, the amount of recoverable gold in each stage can be determined. Through careful interpretation of the results obtained by diagnostic leaching, the metallurgist can devise a flowsheet for treating the ore or solve a problem at an existing plant

Jan 1, 1992

By John T. Crawford

Open pit limit analysis techniques of various types have been utilized for many years to design ultimate pit surfaces. In the last 15 years there have been many advances in the development of sophisticated computer methods to aid this process. The extensive capability of the computer has led to multiple alternative approaches to problem solving. Computerized open pit limit analysis methods can be applied to a broad scope of long-range and intermediate-range mine planning and design questions. A single computer run develops a pit design from a set of data. A set of nonsequential runs is used to evaluate changes in pit slopes, property restraints, and mineral model variables. Ore reserve economic sensitivity and intermediate-range mining plans can be developed using sequential computer runs. Present value methods are incorporated by using iterative sequential techniques. Multiple ore processes, dump leaching credits, and the trade-off between open pit and underground mining can also be handled. Many of the applications described are representative of current practice. The remainder are suggested extensions.

Jan 1, 1979

By Sii Smith-Gruner

Blasthole drilling by todays standards is not a mature operation. In most mining appli¬cations, the blasthole drill rig is the least understood piece of machinery. Draglines, mining shovels, and haulage trucks may have more charisma, but the entire mining process starts with the drilling of blastholes to facilitate removal of the overburden and/or the primary material being mined. There are two (2) principal drilling methods them being rotary and percussion. In certain situations, percussion drilling is the most practical method, but for most applications, rotary drilling using the rotary tricone bit is the common and accepted drilling technique. While the drilling rig is on the surface and quite visible to everyone, it is really the object at the end of the drill pipe, the tricone bit, that is doing the work and drilling the hole. The rig supplies power to the bit and air to clean the hole. In addition, it must be capable of providing certain other functions and should be properly outfitted to adequately support the rotary tricone bit.

Jan 1, 1988

A joint research effort by Newmont Gold and Du Pont, working with Kurtis Mooney, of Tri-Combined Resources has developed a new ore-sample bag made of "Tyvek," a spunbonded olefin. "The goal was to find a bag with the best trade-off between efficient draining of moisture, minimal fines loss and compatibility with the conveyor drying process we were developing for our new assay lab," Charles Bucknam, analytical development coordinator for Newmont Metallurgical Services states. None of the available polypropylene, cotton or canvas bags had the needed combination of properties. "Our original tests in 1987 on the plastic bags we had been using showed an average loss of 5.4% of mud sticking to the bags when they were emptied into drying pans. Part of the sample was still in the bag as a residual." Tests on bags of "Tyvek" showed low residuals when the samples were dried in the bags before they were emptied, but about 3% of the fines were lost through the seams. Mooney recommended a new bag design, with fold-over seams.

Jan 1, 1990