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By Marina K. Peshkova, Izabell V. Pomorova

Computer modelling system for definition optimal way of in- vestment under condition of diverse directions of activities mining enterprises has been created. The main purpose of paper is to introduce the new scientific approach of finding effective variants of investment for mining industry under free market condition in Russia, it can be also interesting for domestic and foreign investors.

Jan 1, 1996

By Jamal Rostami, Jürgen Schmitt, Rohola Hasanpour

"Double Shield TBMs can be used in fast track projects for accelerated completion where there is limited information available on ground conditions and there are possibilities of encountering weak ground and shear zones. As such, the shielded TBMs are the primary choice of the machines in long tunnels, but face the possibility of entrapment in squeezing ground, which entails long delays and major risks. This paper examines the possibility of using ground improvement methods to increase ground strength, and thus, increase the capability of the machines to cope with squeezing ground conditions. In this study, 3D finite difference simulation of a shielded TBM in squeezing ground was performed to estimate the operational parameters including required thrust to get a machine out of an entrapment. This analysis was also used to evaluate the possibility of preventing machine jamming by the implementation of pre-excavation ground improvement to increase the strength of the ground. INTRODUCTION In order to face adverse tunneling conditions especially using a shielded TBM in squeezing ground, new shield designs, with extra thrust and torque, step shield geometry with reduced shield diameter from front to the back, and conical shape shields have been used. In addition, many of the new machines have the capability to implement ground improvement at distances up to 50 m ahead of the face in order to reinforce the ground and further increase in their chances to cope with squeezing ground conditions. While these features have been added to the machine, there has not been a thorough evaluation of their impact on improving the chances to avoid machine jamming in weak rocks at high depth, which is conducive to rapid convergence of the ground."

Jan 1, 2016

By P. Schilizzi

The increased impact of mining subsidence in the U.S. coalfields and the recent regulatory constraints legislated by government and state agencies have provoked an intense research effort on this topic by government agencies, coal companies and academic institutions. Subsidence and horizontal strain predictions are a basic requirement if subsidence and its associated effects are to be controlled and contained within acceptable environmental levels. As a result, several such prediction techniques have been proposed or are currently under development to assist coal operators in minimizing the detrimental effects of these surface deformations. VPI&SU has been actively involved in this research effort in the past few years, with particular emphasis on the Appalachian coalfield. During the initial stages of this research a large number of subsidence case studies were collected from the literature, the coal industry and government agencies. In total, data from 32 longwall panels and 60 room and pillar panels were collected. This data bank was used to determine relationships between the basic mining and subsidence parameters, in order to allow the evaluation of the various prediction methods for the Appalachian coal region. Based on this data two subsidence prediction techniques, one based on profile functions and the other on influence functions have been developed. Profile function methods provide a tool for a fast calculation of subsidence on a line across a mine panel. Influence function methods, on the other hand, allow for a more detailed calculation of ground movements, in any mode and at any depth, on a grid or at any specific point. The limitations of the data of the collected case studies, i.e. accuracy of surveys, frequency of monitoring, lack of horizontal movement measurements, etc, led VPI&SU to the initiation of a detailed subsidence and strain monitoring program above a number of active mines, located in three major coal producing counties of Virginia. The aim of this program was to enhance the data base with accurate and complete measurements of surface movements and to allow, therefore, the refinement of the prediction techniques. This paper presents this monitoring program, discusses in detail the results obtained from three specific case studies and provides recommendations for the implementation of the field data in the general prediction methods.

Jan 1, 1986

By Harry M. Conger

Kaiser Steel Corporation's Eagle Mountain Mine is located in the Colorado Desert, 60 miles east of Indio, California. Concentrates from the mine are shipped by rail 164 miles to the company's steel mill at Fontana, and also to Longbeach, California for export. Temperatures are typical of the lower desert ranging from a high of 120 degrees in the summer to a low of 25 degrees in the winter. The average annual rainfall of about two inches comes mainly as cloud bursts during the summer months. From its inception, the Eagle Mountain Mine has had the problem of breaking its mine rock. Practices followed from 1949 until 1962 were very costly, did not produce uniformly good fragmentation, and were incapable of sustaining high production. During this period, every conventional type of explosive then in use was tried and found to be unsatisfactory for one reason or another. The first slurry test work at Eagle Mountain was started in 195E and finally by 1962, after having tried all the slurry mixtures then available including some "home made" formulas, a metallized slurry was perfected at the mine which overcame all of the disadvantages of former blasting methods.

Jan 1, 1965

By Dale D. Teeters

Today, I would like to talk about ways to maximize the efficiency of surface coal operations. I doubt I will present any startling new ideas, but my comments may, hopefully, stimulate some conversation today and later back at your own operations. Strip mining is a very old technique used by ancient societies. Only with the coming of the machine age in the early twentieth century did we attempt to increase the magnitude of our operations. The industry, as we know it today, really only got started in the early 1900s with the advent of steam shovels. In the first portion of this presentation, I will attempt to show that we have, in many cases, not changed the basics of strip mining, only the scale. In doing so, quite often we have complicated the operations to the point of being unmanageable and unprofitable.

Jan 1, 1981

By Duane A. Smith

Horace Tabor. No 19th century Colorado mining man is better known but, unfortunately, probably less understood. He is little appreciated for his significant contributions to the industry and the state. A century ago, Tabor was headline news. The legend today, however, has become so all pervasive and so interwoven with fact that the two are hard to separate. For example, he never told Baby Doe on his death bed to hang on to the Matchless mine. Yet this has emerged as staple Tabor fare. So much attention has been focused on his matrimonial triangle that it overshadows the man. Symbol of mining's reward Tabor traveled west in the 1859 Pike's Peak gold rush. In the next generation, he came to symbolize the rewards mining might lavish on an individual. The Leadville Daily Herald (Sept. 10, 1882) could write, without exaggeration, that "the extent which the mining industry of Colorado is under obligation to Tabor cannot be easily estimated - what he has done for Leadville and Denver is patent to all." It had not come easily, nor had Tabor started out a success. His early placer mining at Payne's Bar, near present-day Idaho Springs, CO, had turned no fortune. So in 1860, he, his wife Augusta, and son went south to Colorado City, then over Ute Pass and up the Arkansas Valley to Oro City. Arriving soon after the initial discovery, Tabor staked a good claim. With a sharp eye, he and Augusta broadened their base by establishing a store. Both mining and business would pay dividends in the following years. By the season's end, though, Oro City was already declining. Always on the lookout for a richer district, Tabor and his family moved the next year across the mountains to promising Buckskin Joe. The familiar pattern followed, with the store and post office being the center of their attention. Mining investment and management now replaced the earlier physical panning and sluice operating. Seven years later, the Tabors abandoned Buckskin Joe and returned to Oro City. It had moved up California Gulch to be near the district's best mine, the Printer Boy. Middle class was not enough Middle class respectability, plus a steady income, was the Tabor's by the 1870s; fine as far as it went. But it proved far from the fortune Horace had always been seeking. Oro City languished in the backwash of Colorado mining and Tabor seemed like many men who had drifted around the Territory following the ebb and flow of mining. His faithful wife Augusta had been a steady factor in the success the family achieved. She helped year after year to operate the store and post office. Not simply the happy-go-lucky individual he has often been portrayed, Tabor was a hard working businessman/mine owner. An R. G. Dun and Company agent evaluated him in 1876 "Net worth $23,200. Is a very shrewd businessman and not liable to lose money, has a good chance to make money as he had no competition." Leadville: Tabor's silverlined-fortune After all those years on the Colorado mining frontier, in 1877, Lake County's wealthiest and most respected merchant made another move. It was short in distance, only 4 km (2.5 miles) down California Gulch, then a little north to a new mining camp. This new camp, soon named Leadville, gave birth to the Tabor fortune and legend. Middle-aged (Horace was 47), the Tabors once more set up their general store and found themselves in the midst of the open¬ing of a new district. This time silver beckoned and not the gold that had brought them West 18 years before.

Jan 1, 1989

By John T. Awald

The Bradshaw Mountains of west-central Arizona cover an area of 1600 square miles and contain numerous old mines and prospects. The area has been geochemically sampled on a reconnaissance basis to relate mineralized areas to regional structure and rock types. Copper analyses of stream sediments have been classified and contoured to show the distribution of low background, high background, and low, intermediate and highly anomalous areas. Contoured results are compared to geology and known mines. Several prospecting areas are indicated.

Jan 1, 1970

By G. Oswald

The fatty acid flotation process has been used to produce phosphate for decades, yet the chemical mechanism involved has never been thoroughly investigated. A basic knowledge of the process is lacking, and as such, industry has had to develop their own guidelines for the design and operation of conditioning and flotation equipment. These guidelines are the result of many trial and error attempts, and are not by any means universally endorsed. There are almost as many opinions about how to operate a plant as there are practitioners of the art. This paper covers the currently recommended rules for design as viewed by one practicing phosphate metallurgist.

Jan 1, 1993

By C. R. Copeland

Water sprays are a common method used to reduce particulate matter (PM) emissions. Various factors such as wettability, surface area coverage, fine particle engulfment rates, interparticle adhesion forces, suppressant penetration, and suppressant longevity have all been suggested as critical factors in achieving effective PM control. However, it has not been established which of these factors are the most important. Experimental work indicated that suppressant penetration is the most critical of these factors. Suppressant effectiveness was also improved using hygroscopic reagents which retained moisture, improving longevity. Maximizing suppressant penetration and improving suppressant longevity led to an average 86% reduction in PM10 concentrations in laboratory dust tower tests.

Jan 1, 2008

By K. E. Hjelmstad, W. H. Pomroy

In the event of fire underground, it is essential that all miners be warned as quickly as possible. With mine air rapidly depleted of oxygen and contaminated with smoke and toxic fire gases, any delay in the warning signal could have disastrous consequences. Unfortunately, present mine fire warning systems, such as stench, audible or visual alarms, telephones, and messengers, are often slow, unreliable, and limited in coverage. Recent research by the US Bureau of Mines has established the feasibility of ultralow frequency electromagnetic signaling for underground mine fire warning. Infield testing completed thus far at five mines, signals of from 630 Hz to 2000 Hz were transmitted through rock up to distances of 1645 m (5400 ft) to a pencil-sized ferrite-core receiving antenna and intrinsically safe receiver circuit. Theoretical analysis indicates a capability to transmit effectively for distances in excess of the maximum depths of most American mines, which is about 900 to 1000 m (2950 to 3280 ft) . The prototype system uses off-the-shelf components and state-of-the-art technology to ensure high reliability and low cost. This technology would enable simultaneous and instantaneous warning of all underground personnel, thereby in- creasing the likelihood of successfully evacuating a mine during a disaster. This report discusses the theoretical basis for through-the-rock ultralow frequency electromagnetic transmission, design of the prototype transmitter and receiver, and the results of in-mine tests of the prototype system.

Jan 1, 1991

By Steve L. Bessinger, Luis B. Giraldo, Joram Shenhar, James D. Pile

This paper discusses the Helical Drag Bit (HDB) and its rock drilling applications with an emphasis on use in mining operations. The HDB is a drilling tool that employs cutting members arranged in a pattern to form a helical groove or thread within a borehole. This pattern of cutters can be used for several purposes including roof bolting in mining, interpretation of the lithology of the strata being drilled and low energy consumption drilling. Laboratory and field experiments have consistently shown increase of roof bolt-anchoring capacities in weak rock of more than 100% using the short encapsulation pull test method when boreholes are conditioned using the HDB. In 2004 a series of tests conducted in mines with weak roofs demonstrated the benefits of HDB technology for roof bolting applications in mining. HDB technology offers opportunities for new and beneficial approaches to interpret the geology of roof strata. During conventional drilling, traditional approaches to determine rock properties require simultaneous measurement of several parameters such as thrust, rotational velocity, torque and penetration rate. The unique geometry of the HDB possesses a characteristic that allows determination of the mechanical properties of the rock being drilled by measuring torque as a single drilling parameter. This capability greatly simplifies the process of determining rock properties and provides reliable results. Additionally, HDB technology has been demonstrated to offer significant advantages for rock drilling. A substantial portion of the rock is removed by the fracturing of the internal thread created in the rock bore by the tool taking advantage of the weakness of the rock in tension. Because the rock chips obtained in this process are relatively large, savings in energy are realized when compared to traditional drilling technologies.

Jan 1, 2005

By J. den Drijver, M. Opahle, R. Inderst

Safety reasons render necessary the advanced calculation of the amount of methane degassing from a longwall in the scope of the ventilation planning of mines. Today empirical methods, which are based on observations of operational procedures, are used for the calculation of the amount of methane. Despite of constant improvement those calculations are not always sufficient. In particular calculations which are based on operational facts but not proved by experience are not reliable. Most of all these calculation procedures lack physical-analytical descriptions of the procedure itself, presenting only the effects on important parameters such as the distance between seams in the roof or floor or gas pressure. Tschersich [Tschersich 961 developed an analytical model for an advanced calculation by analysing the degassing of seams in the roof and floor and the physical parameters of gasflow. This model might correct the lacks of existing procedures and improve the precision and reliability of additional calculations. The model simulates the emission record in seams of the roof and the floor. It takes into account not only a multitude of parameters such as the distance to adjacent seams and gas pressure but also the depth of seams, gas content, rank of carbonification, rock temperature, face advance rate, initial and succeeding mining and the face length. In order to comprehend and to verify those correlations we extended the model of Tschersich and programmed this enlarged model using the computer language C++. Aim of this research is to guarantee a much higher accuracy in calculating methane emission caused by mining. The improved planning is expected to result in more safety and better prevention of high methane con- tent in ventilation as well as in a better use of the capacity of the mining equipment. The application [Drijver, lnderst 961 of the ex- tended model will also be very useful in the course of research projects as it allows computer simulation, i.e. in-situ research can be extensively limited or even replaced.

Jan 1, 1997

By David A. Grisafe

Divided opinions concerning dredging-permit locations and boating uses on the Kansas River in northeastern Kansas led to a study of the recreation potential on the river by a legislatively mandated interagency group (five agencies) that included the Kansas Geological Survey (KGS). In addition, the KGS conducted its own study of the river corridor, encompassing the development, geology, and economic resources of the corridor (Brady and others, 1998). The corridor area is 12 mi wide and 140 mi long (171 river miles). Included in the study was the potential impact of restric¬tions to river dredging. The Kansas River and its floodplain in northeastern Kansas are underlain by Lower Permian and Upper Pennsylvanian limestones and shales. The river and its floodplain are the major sources of sand and gravel for northeastern Kansas, and the limestones along the river bluffs supply crushed stone and building stone. The population of the 10-county area bordering the river has grown by 20% since 1980, and now comprises nearly 40% of the state's population (U.S. Bureau of the Census, 1996). Projections (Floerchinger, 1992) indicate close to 50% of the Kansas population will reside in these counties by 2025, with a continued increase in the demand for aggregates. Factors such as floodplain width, price and availability of land, and overburden ratios tend to favor river dredging on the lower part of the river, and floodplain or pit dredging on the upper portion. The use of alternate sources of sand and gravel such as the Missouri and Arkansas Rivers would increase sand prices due to transportation costs to much of the 10-county area. In 1996, river and pit dredges along the Kansas River supplied more than 3 million tons of sand and gravel valued at about $8 million to northeastern Kansas. As a result of its study, the KGS had concerns with the idea of large recreation zones on the river that excluded river dredging in areas of presently large population and projected population growth. This controversial issue is likely to recur elsewhere.

Jan 1, 1999

By C. E. Capes

INTRODUCTION In the coal industry, ever greater amounts of fine coal must be processed due to the need to crush to finer sizes for impurity liberation in low cost physical cleaning processes. Fine coal processing is a major problem for the industry, both through the cost of disposal of reject fines and through the mining cost of lost coal values. Of the available disposal methods, impoundment has always been the most popular. In many cases, when the coal fines were of sufficient quality, froth flotation and expensive filtration methods were used to recover the coal in these waste streams. The coal fines are not always of a marketable quality, however, and flotation, due to poor yields and difficult dewatering, has always been an expensive and not necessarily profitable process. The oil agglomeration method is increasingly important as a technology for the treatment of fine coal-in-water suspensions. These fines can be preferentially wetted and agglomerated by many different oils mixed with the suspensions. Ash-forming impurities remain in suspension and are rejected when the agglomerates are recovered, for example, by screening. Agglomeration-based methods provide perhaps the only practical means for upgrading extremely fine coal to useful products on a large scale. As with froth flotation, oil agglomeration relies on differences in the surface properties of coal and impurities to effect separation. Whereas flotation be- comes less effective with particles finer than 200 mesh (0.075 mm) or coarser than 50 mesh (0.3 mm), there appears to be no lower limit on particle size for oil agglomeration while particles % in. (3.175 mm) diameter or larger can also be treated, if desirable. In addition to this ability to clean a broader size range of coal particles, oil agglomeration can produce a dense, coarse granular product of acceptable strength and low water content without the need for vacuum or thermal drying. The preferential wetting of solid surfaces by immiscible liquids has been utilized, if not fully understood, for a long time. Indeed Gaudin,229 in tracing the ancestry of froth flotation, refers to a 15th century oil-pulp kneading procedure in which water-wetted particles were freed under water from an oiled mass. An understanding of the physical chemistry involved in such

Jan 1, 1991

By Morgan M. Sears

In recent years, one large mine collapse and numerous smaller bump events have resulted in a renewed interest in coal bump research. With numerical modeling, the Energy Release Rate (ERR) calculation quantifies the ?release? of the gravitational potential energy of the rock mass into the environment as mining progresses. This release of energy can occur passively in the form of heat and sound or dynamically in the form of pillar bumps or rock bursts. From the initial application of a calculated energy release rate in the deep hard-rock mines of South Africa, the ERR was found to have a significant correlation with the risk or potential of damaging coal bumps or rock bursts. In this research, an ERR calculation is incorporated into the modern LaModel program to facilitate the analysis for potential coal bumps. Initially the ERR calculations in LaModel are verified using a case study of cut sequences originally modeled using the MULSIM/NL program. Then, the ERR calculations are applied to a bump-prone mine in Southern Appalachia were a number of different pillar recovery cut sequences were used in order to minimize the risk of bumps.

Jan 1, 2009

By E. Fahrenkrog

An intelligent supervisor developed using expert system tools and applied to a crushing plant is presented in this paper. The structure of this supervisor, based on a model of a human operator, consists of a Knowledge base containing a qualitative model of the process, and a Rules base with the heuristic logic used by an operator when supervising a plant. The simulation results obtained show the potential of this type of systems to supervise the automatic operation of a plant.

Jan 1, 1989

By Ian S. Lowndes, Adrian T. J. Moll

With the current trends towards the concentration of extraction to fewer but higher production units in deeper seams, often of higher coal rank, the role of methane drainage ranges has become critical. As mines exploit seams at greater depth and more remote locations there has been a need to extend the lengths of methane drainage ranges and to increase the capacity of the surface pumps. This trend has highlighted the need to effectively simulate the operation of a methane drainage range in order to produce the optimum design and operation of a safe and economic system. This paper describes the development of such an analytical tool. The application of this computer model is illustrated by the analysis of the operation of the drainage system of an extensive mine. The paper concludes by considering the development of a [Knowlege Based or Decision Support System] which will assist the ventilation engineer in assessing the current performance of an existing drainage range and will suggest possible remedial modifications or design strategies which may improve the system performance. INTRODUCTION In order to maintain the general body methane levels to below predetermined statutory threshold limit values (TLV's) on major longwall production units there are, for a given production rate, two major complementary control devices which may be employed by the ventilation engineer. These are the combined design and application of a competent mine ventilation and methane drainage system. The methane drainage system should be designed so as to maximise the capture of the methane (firedamp) from the seam being mined and the strata gas liberated in the vicinity of the extraction zone from gas bearing seams or other reservoirs of gas situated at above or below the mining horizon. The design fresh air quantity entering the face should ensure that under normal operating conditions the methane entering in the vicinity of the face is rapidly dispersed and dilute to well below statutory TLV's. The drainage system must therefore be designed to maximise the capture of the methane gas liberated to minimise the amount of gas which enters the ventilation airstream. GAS DRAINAGE The inherent dangers of methane emissions in mine workings have been a problem of concern to mining engineers for many years. To alleviate the risk, methane drainage has been employed for some years to capture the gas before it becomes a hazard to the operation of the mine. The method of drainage employed will be dependent on a number of factors which include the longwall mining method and production cycle employed, the characteristics of the coal seam being extracted and those of the adjacent gas bearing strata. The location of the gas bearing potential of the over and underlying coal measures must be determined. The gas bearing

Jan 1, 1993

By Robert C. Dunne

Nearly one third of Australia's total gold product is produced in the Kambaloa - Kalgoorlie - Leonora Goldfields. There are presently some 25 gold mines in the area with the possibility of another six plants being constructed in the next year. Details of the gold extraction techniques used on these mines will be discussed and certain innovative technologies and problem areas will be highlighted.

Jan 1, 1998

By R. C. Klimpel

Size reduction of material in aqueous pulps by the use of tumbling media overflow discharge mills is an important and common unit operation in industry. There also has been extensive attention given in recent decades on developing a more fundamental understanding of the breakage processes involved, especially in ball mills. These studies have mostly emphasized the use of size-mass balance or population balance approaches for quantifying the analysis and design of size reduction circuits, ego Austin, et al (1984).

Jan 1, 1989

By K. A. Sauer

Blasting can create severe interference for a mine's carbon monoxide based fire detection system. At the present time, without being able to differentiate between blast and non-blast carbon monoxide, a fire detection system must either set fairly high alarm levels for its sensors, or allow frequent "false" alarms to sound during blasting. This paper will introduce current work being done which will attempt to define characteristics of the carbon monoxide concentrations time curve for blasting. The work uses drift blasting for its data base as it is one of the more common forms of blasting. Future work with the data may produce a mathematical model which can be used to monitor and identify the carbon monoxide time curve for drift blasting.

Jan 1, 1989