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By L. A. Puchkov, Mesentsev. V. K., I. O. Temkin

The problem of increasing underground mine ventilation efficiency is still of top priority. The complication of geological conditions with the depth of underground mining processes and reinforcement of requirements to technological and ecological safety are extorting the necessity of solving this complex problem with using of new information technologies. There exist different approaches to the ventilation problem. One of them, which the authors adhere to, is based on the concept of monitoring (under special mining and geological conditions-automatic control) of mining atmosphere and operative re-distribution of underground mining air among consumer , in accordance with the criterion of optimality [ 1.3 1. ] The set of tasks which should be decided in the frame of con- crete ventilation system depends on the peculiarities of deposit, technological schemes and so on. Nevertheless, some ventilation tasks such as: defining of ventilation network parameters; finding of dependence between these parametrs; operative redistribution of air streems, could be interpreted as universal ones. Main aspects of practical solving of different ventilation problems and their classification were investigated and considered in detail before [I ,2 ]. Some years ago we have began our investigations to develope quite simple and effective methods for decision of ventilation tasks on the base of neural network technology. It is well known that ventilation net, formed by various mine workings, is the main component of underground mining ventilation system. In general, network air distribution may be described by some functional F(Q,R,H), where Q- is a vector of air consumptions; H- is a vector of depressions; R- is a vector of airdynamic resistences. (Q,R,H) - are the informative entities , characterising every branch of the net. There exist some fundamental tasks which should be decided during the process of control of mining ventilation: calculating of natural air distribution Q = Q,{R, H,}, or Q = Q2(R, Q?}, where H, - is the maximal depression of the ventilation net, Q, - is the air consumption in the ventilation shaft; identifying of airdynamic resistance for some branches on the base either of air-depression removal or operative monitoring: [ ]

Jan 1, 1996

By R. M. Williams

Introduction Ring roller mills are efficient size reduction machines embodying the following machine functions: 1) Size Reduction: from a feed size of 2 in. to various size products as fine as 400 mesh, or granulation from 2 in. to 6 mesh containing a minimum of fines. 2) Drying: fluid bed drying of wet feed materials. 3) Conveying: negative pressure air system results in dust-free conveying. 4) Beneficiation: liberation and removal of foreign materials from the auxiliary bottom discharge simultaneously while grinding. Operation Operation of the roller mill system, Figs. 78 and 79, is completely automatic. A feeder introduces raw material into the grinding chamber in the base of the roller mill at a rate determined by pressure variations within the roller mill as material is ground and air conveyed away. The feeder will be activated by the reduced static pressure and introduce unground material into the system, thereby maintaining a constant differential pressure. Plows located ahead of each grinding roll direct the material upward and between the grinding rolls and the bull ring where it is ground to size. The grinding rolls are free to swing out centrifugally, which forces them to bear upon and grind the raw material. Being free to pivot axially, the rolls automatically assume the proper position for grinding and need no adjustment to compensate for wear. Rotation of the rolls is by rolling contact. Once ground to size, material is swept out of the mill by the controlled air flow from the centrifugal main mill fan. Air suspended, the ground material passing through the adjustable spinner separator. In the separator, an accurate size classification is made which allows product-size material to be conveyed away from the roller mill while oversize material is returned internally for additional grinding. By varying the speed of the separator drive, more or less cyclonic action is achieved at this location, effectively controlling product size. Product sized material is removed from the airstream by the cyclone collector. Typically, a conveyor or product storage bin will be located to accept the product as it exits from the bottom of the cyclone collector.

Jan 1, 1985

By R. Ramesh

Understanding the nature of coal surface heterogeneity is a prerequisite to accurate characterization and efficient control of coal surfaces. New techniques based on the centrifugal immersion of particles from the liquid/ vapor interface and film flotation have led to independent estimation of surface energy distributions in individual coal particles. Changes in the distribution of surface sites due to oxidation and polyacrylamide adsorption on coal are studied here using the above techniques. New information on -possible conformations of adsorbed polymers is also obtained.

Jan 1, 1989

By R. J. McGregor

The Internet has revolutionized worldwide communications. Any real or perceived mining incident or environmental spill, no matter how small or remote, can become a disaster of "biblical proportions" through the judicious use of the Internet by environmental and anti-mining groups. In addition, mining companies' own Web sites and unofficial message boards can provide plenty of additional ammunition to the anti-mining forces. This paper explores how the Internet and readily available information are used by anti-mining groups active on the Web.

Jan 1, 2001

By Jihong Xue, Jialin Wang, Della Valle Nicola

Experience of Hard Rock TBM excavating soil in Wanjiazhai Yellow River Diversion Project tells us that selection of Hard Rock TBM to excavate soil in case that rock dominates overall length of tunnel, could be a compromise among tunneling speed, cost and quality. Risk of this operation could be greatly reduced with a detailed study of the geomechanical characteristics of the soil and, if the characteristics are suitable, money and time can be saved by using Hard Rock Double Shield TBM.

Jan 1, 2003

By Li Changgen, A. Bahr

The adaptability of pneumatic flotation cells for the flotation of sulfide ore and the conditions for sulfide ore flotation in pneumatic cells were investigated. The advantages of pneumatic flotation cells over mechanical flotation cells, as well as flotation columns, for the flotation of sulfide ore were demonstrated. Test results indicated that the Cu grade and recovery for concentrates obtained when using the pneumatic flotation cell were 1 % to 2% and 4%, respectively, higher than those obtained when using the mechanical flotation machine.

Jan 1, 1993

By Dale C. Matthews

The Getchell Gold Hine is located about 40 miles northeast of Winnemucca, Nevada. Gold was discovered at the mine in 1934 and production was started in 1938 and ended in 1967 for its first phase of operation. Gold production during this period was about 800,000 ounces. In 1983, FirstHiss Gold Inc. purchased the property and initiated an exploration program that proved minable reserves of about 1,300,000 ounces of gold remained in the mine. During the exploration period, metallurgical testing was conducted to determine the most economical process that could be utilized for recovery of gold from the very refractory ore. After extensive investigation, pressure oxidation of the ore was selected, Engineering for the new plant commenced in 1987 and construction was completed in 1989 at a cost of about $87,400,000.00, not including financing cost.

Jan 1, 1990

By Joe D. Allison, Tom D. Baugh

The analysis for total cyanides (CN, or the cyanide due to the combination of free, weakly associated and refractory cyanide complexes) is required by most regulatory agencies for determination of effluent compliance. This method requires a distillation of the sample at low pH's and is most often sent to contract laboratories at a high time and monetary cost. This paper describes a new micro­distillation apparatus which allows for a multiple of CN,"' analyses to be carried out simultaneously saving both time and money. It can be used in the field, since only electrical power is required for the method. While not being appropriate for reporting values to the respective regulatory agencies as of yet, it is quite valuable for screening a large number of samples prior to submission of the samples to a contract lab for "official" reporting.

Jan 1, 1990

By Paul A. Lahti

Independence Mining Company, Inc. (IMC) has for the past several years processed refractory gold ores at its Jerritt Canyon operation near Elko, Nevada. The ore is typical of those of the Carlin Trend and is refractory due to physical encapsulation of gold in carbon, pyrite, and arsenopyrite. It is also "preg robbing" due to the contained organic carbon that acts as a gold adsorber. Refractory ores require some form of pretreatment before cyanidation to enable economical recovery of gold. The metallurgical facility at Jerritt Canyon is unique in that it consists of two distinct pretreatment methods for the recovery of gold: a chemical process utilizing chlorine and a pyro-metal­lurgical process employing oxidative roasting. This paper pro­vides a comparison of the two methods highlighting flow sheets, pretreatment operation detail, performance comparisons, and pertinent environmental data.

Jan 1, 1996

By K. Nielsen

This paper is based on two recently (2002) published reports: - "Breaking New Ground". Final report on the Mining, Minerals, and Sustainable Development Project (MMSD). - "2002 Sustainability Reporting Guidelines". Published by the Global Reporting Initiative (GRI). The GRI guidelines can be applied in all kinds of industries and other organizations, whereas the MMSD project report is sector specific. However, both reports center on the three pillars of sustainability. The performance indicators as they are presented in the GRI guidelines have been assessed and compared with the sector specific arguments in the MMSD report. Based on this evaluation, the paper points at some indicators that may be useful in the start-up phase of sustainability reporting, seen from the perspective of the aggregate industry in an industrialized North European country with increasing environmental awareness and pressure on natural resources.

Jan 1, 2003

By Mary Korpi

So now you ask, Where are the transcripts? The well-organized co-chairs, Harry and Mary, did their job. Doug Halbe was active in the audience encouraging people to speak up and keeping everything moving along. So where are they? Were the comments so provocative that they could not be written? Was the profanity so bad (even for miners!) that it couldn't be repeated? It appears that at the first session of the Plant Operators' Symposium a glitch occurred with the recording equipment. Thanks go to everyone who did comment during the dis- cussion period. The People I session had a lot of lively conversation and we are sorry that it will not be printed. However, there is now another reason to hold the plant operators' sessions on a regular basis! Another People session can and will be held in the future.

Jan 1, 1998

By J. N. Philbrook

As with most industries, mining must now include in its plan of operation mechanisms to address a project's environmental impact. New regulations have focused attention on the potential environmental impacts of industry, particularly the handling of wastes. Modifications are currently being proposed to the Bevill Amendment. And development is ongoing of Resource Conservation and Recovery Act (RCRA) Subtitle D regulations specific to mining wastes. The result is a growing concern on the part of lenders, developers, buyers and owners regarding acquisition and ownership of mining properties. One of the most effective tools in managing the regulatory requirements is an environmental audit. An environmental audit can be a literature review to determine regulatory requirements. The audit can also take on the form of a phase-one site assessment. This is a limited investigation to determine whether there are specific

Jan 1, 1991

By M. García-Vásquez

In Peru, the third destination in worldwide exploration based on expenditure, mining conflicts have spread dramatically over the last decade. Mining companies need to create new initiatives to avoid social conflicts and strengthen the social capital needed to keep mining in a country with proven mineralogical riches. This document provides information about a research project that explored the opinions and experiences of a resource many times overlooked by companies: the human resource. Over 30 surveys were conducted among professionals working at mines in the Peruvian mining industry, in different departments and from different organizational levels. Mining employees acknowledged that they play an important role in the development of company-community relationships and gave their impressions about initiatives implemented by international mining companies in Peru. Mining employees also provided their recommendations to succeed in a location where cultural differences have not been properly considered.

Jan 1, 2011

By L. Karka

The gold processing plant location in the Chalkidiki coastal area has been studied as a land use conflict case study in the context of a EU research program. The sustainability assessment of the plant establishment is made on the basis of a group of sustainability principles and criteria adopted in the framework of the SPECTRA project. Since the gold processing project has not been implemented yet its sustainability assessment is made on the documents submitted by TVX Gold during the procedure for the siting consent and the granting of environmental conditions. The assessment, appearing on a table, reveals an important effort to achieve a high degree of protection during the operation and after completion of the activity. The specific nature of the development and the knowledge of the local opposition in favour of tourism development have obviously influenced the priorities set.

Jan 1, 2003

By B. K. Mishra, Partha Chakroborty

Jigs are the most important equipment used in the separation process that exploits the stratification of particulate matter under the influence of hydrodynamic and gravitational forces. Very little is known about the determined mechanisms by which particles of varying density, size, and shape stratify in a moving bed. A model is developed by using the discrete element method to understand the behavior of jig bed. This model is utilized here to study the stratification behavior of the bed and its control. The control action is based on the understanding of the physics of the stratification process within the framework of fuzzy logic. The actions suggested by the fuzzy logic controller (FLC) depend on the current degree of stratification and the existing frequency of the jig cycle. The results show that the FLC achieves efficiency in stratification with minor variations to the jig cycle.

Jan 1, 1995

By W. Pariseau, J. Goris, S. R. Dismuke

Ore at the Magmont mine in southeast Missouri is extracted by the room-and-pillar method on two and sometimes three horizons. In 1991, a plan was formulated to recover high-grade ore in pillars using cable halts to accommodate spans of more than 27 m (90 ft ). A test area was selected and a recovery plan developed. A cooperative rock mechanics study was established by Cominco Metals, the US Bureau of Mines and the University of Utah. When initially opened in 1968, the planned production rate was about 910 kt/a (1 million stpy). Due to declining reserves, the production rate was decreased in November 1992 to 570 kt/a (630.000 stpy). Pillar recovery now accounts for about 40% to 50% of the mined tonnage. This method plays a vital role in allowing Magmont to continue to operate.

Jan 1, 1996

By Denis M. Riley, Neville C. Lockhart, Bruce A. Firth

The potential use of the Kelsey Centrifugal Jig to clean fine coal has been studied. It was found capable of cleaning coal at very fine sizes, at least to 0.038 mm at relative densities as low as 1.6. This effect was however very dependent upon the solids feed rate and the absence of significant amounts of clay slimes. Comparisons with a spiral and a laboratory scale Jameson Flotation Cell were made. The concept of recleaning spiral product was investigated. Use of a spiral to reclean the coarse fraction, and a centrifugal jig or flotation to treat the fine fraction, gave significant improvements in final ash values over spiral recleaning of the full size. Future R&D needs include improving feed rate capacity, and application to problems like pyrite removal that are difficult to solve via flotation.

Jan 1, 1995

By Andrzej M. Wala

A prototype expert system for planning and designing an underground coal mine has been developed in a doctoral study at the University of Kentucky. This prototype expert system for underground coal mine planning and designing consists of a number of knowledge bases concerning different elements of design (e.g., ground control, excavation and bulk materials handling, ventilation, etc.). The objective of this paper is to present the development process of the ventilation design knowledge base for this prototype. This expert system prototype is intended for building an instructional expert system for underground coal mine design. Therefore, the undergraduate course on mine design has been used as the basis, for its development. Because of the availability of knowledge and expertise, this research study has been limited to development of a knowledge model for the Appalachian coal mining region.

Jan 1, 1993

By K. L. Whitehead, R. A. Jankowski, N. I. Jayaraman

Most continuous miner sections utilizing flooded-bed scrubbers also use blowing face ventilation. Blowing ventilation, however, interferes with dust capture and minimizes scrubber effectiveness. To enhance the efficiency of the scrubber system and reduce dust concentrations, the Bureau of Mines tested various combinations of operating parameters. Experiments for system efficiency took place in a full- scale model mine at 3.05 m roof height. In general, higher values for scrubber and face airflows resulted in lower dust concentrations. In addition, optimum dust controls would include a face ventilation to scrubber airflow ratio of one. When the airflow ratio was either less than or greater than one, the dust levels in the return and at the operator locations increased. No single dust control technique was the most effective one at all locations due to mutual interaction among techniques.

Jan 1, 1992

By Lee R. Martin, Michael R. Taber

Bird Balls™, the latest development in the ongoing battle at mine sites across North America, help to eliminate accidental avian mortality caused by birds ingesting cyanide leachate. Bird Balls™ are a 4-inch sphere made of high-density polyeth­ ylene (HDPE). They weigh 40 grams and are black in color to provide optimum life in UV intense environments. A floating blanket of bird balls totally excludes birds from a liquid surface. Federal agencies that enforce the Migratory Bird Treaty Act do not specify how to keep migratory birds out of leachate basins. Some state agencies, however, specify that a physical barrier must be in place to exclude migratory birds if cyanide levels are high enough to cause mortality. Industry standards for protecting waterfowl now include Bird Balls™ as well as net­ting, detoxification, and heap leach systems designed in such a manner that no exposed solution ponds or channels exist. Hazing is no longer an option. A bold statement to make? Perhaps, but W. R. Jeffress (1990) covers the subject well when he stated that, "Hazing techniques as a whole have not been effective in excluding waterfowl or other species of wildlife from toxic heap leach solution ponds or tailings impoundments. Research and devel­opment of the new 'Star Wars' hazing techniques, such as laser netting and radar systems, are interesting concepts and will pos­sibly offer an alternative to total physical exclusion or neutral­ization in the future. All of these methods are going to have to be thoroughly tested." For those who may want further docu­mentation, we have included a special reference section cover­ing hazing. R. J. Hallock (1990) stated that, "The Fish and Wildlife Service is particularly interested in migratory birds. In fact, a large portion of our effort, nationwide, is focused on migratory birds. Bird habitats are managed directly through the National Wildlife Refuge System and indirectly through other agency programs. We also have a responsibility to protect birds under the Migratory Bird Treaty Act. Most birds attracted to mine ponds are covered under this Act. The only migratory birds not protected under the Migratory Bird Treaty Act are English Sparrows, Starlings, and Pigeons. Since this is a treaty with five nations, the concept of acceptable losses does not apply. It is not a negotiable situation. There are a few exceptions noted in the Act, including prescribed hunting of selected waterfowl, scien­tific collection, and game bird farming. There is no exception for the loss of migratory birds exposed to solutions of cyanide."

Jan 1, 1996