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By D. W. Park

Longwall mining is considered to be the most efficient underground coal-mining technique in terms of coal extraction ratio, production rate and safety standards. Due to the increasing demand for higher coal production, the recent trends have been to use wider panels and to maintain a faster face movement. For these reasons, longwall mining can result in unexpected roof falls, excessive face convergence, shield damage and numerous maintenance problems, which can cause sudden interruption of coal production as well as serious safety hazards. Recent work at the University of Alabama has been dedicated to the development of a longwall strata-control and maintenance system that can integrate real-time shield monitoring, data presentation, analysis, forecasting and warning modules. This integrated system has been called LoSCoMS. The main objective of the system is to provide minute-by-minute stability and maintenance information such as the following: high-load, low-setting pressure, leg leakage, etc.; the analysis of various mining and geological parameters to determine past and present roof characteristics; and the forecasting of loading patterns for the following mining cycles, the next periodic weighting, etc. By using this unique system, mine operations personnel are well aware of past, present and future roof-loading patterns at the longwall face and, thus, proper safety measures can be taken ahead of time.

Jan 1, 1999

By J. D. Morgan

The US economy grew steadily in 1989, reaching an annual rate of $5.3 trillion in the last quarter (US trillion=1012 ). The value of domestically processed, mineral-based materials rose 5% to $315 billion (US billion=109). The value of metals produced from US ores rose 14% to $11.6 billion, while industrial minerals rose 2% to $20.2 billion. Recycled scrap was valued at $10 billion. Increasing economic activity stimulated metal prices. Yearly lows and highs were $2.31 and $3.56/kg ($1.05 and $1.62 per lb) for copper, $1.58 and $2.57/kg (72 and $1.17 per lb) for aluminum, 77 and 97 cents/kg (35 cents and 44 cents per lb) for lead, and $1.58 and $2.09/kg (72 cents and 95 cents per lb) for zinc. Many mining and metal companies reported reasonable profits. Consumer demand strongly affects mining because the US economy is saturated with long-lived products. Consumer, mortgage, and Federal debt continued to rise. 250 million US citizens already possess 172 million licensed motor vehicles and 100 million dwelling units. New car production fell 4% to 6.8 million units, while truck and bus production fell 1 % to four million units. New housing starts fell 9% to 1.4 million units. Imports supplied a significant proportion of total US consumption of several important mineral materials. Imports of crude and refined petroleum costing $50 billion exceeded domestic crude oil production. President Bush expressed "strong concerns about this country becoming further dependent on foreign oil." And the Department of Energy held a series of hearings around the country to develop ideas for a "national energy strategy."

Jan 1, 1990

By J de Cuyper, S. R. Rao, J. Leja, K. S. Moon, W. Freyberger

A prolonged grinding of sulphide ores in steel mills appears harmful to flotation recovery and selectivity whenever xanthates are used as collectors. Particles finer than about 10um show a pronounced decrease in floatability. A supposition was made that the cause of the reduction in floatability of ground sulphides is the presence of metallic iron abraded during grinding and deposited on the ground particles. Electro- chemical measurements were made of mixed potentials developed by different sulphide-mineral electrodes (galena, chalcopyrite, pyrite, marmatite, pyrrhotite) in xanthate solutions, without a direct con- tact or in contact with a metallic iron electrode. These measurements showed that without a galvanic contact between the sulphide and the iron, the values of mixed potentials were in the vicinity of the xanthate/dixanthogen redax potential. When contact with iron was established, the mixed potentials shifted towards the more negative reducing or cathodic values, The shift was greater the higher was the ratio of the surface areas: iron electrode to sulphide electrode. Further, the shift in mixed potentials was greater the more reducing were the conditions on the sulphide electrode. Chemical analysis of reaction products produced on the surfaces of sulphides and in the bulk solution showed that less thiosulphate was formed in all of the sulphide-xanthate systems and that more elemental sulphur was detect-

Jan 1, 1976

By Graham Swan, Richard K. Brummer

The paper begins by describing an underhand cut-and-fill mining concept for a 50m thick, generally tabular though irregularly shaped orebody dipping at 30 degrees and occurring at a depth of between 2300 and 2700m in the Sudbury Basin. From this, the broad design requirements of a fill system are stated. Two and three-dimensional numerical models are then described which were built to evaluate the theoretical benefits of different types of fill reinforcement. Included in this evaluation are the effects of span, fill strength, fill tightness, as well as static and dynamic loading types. Results, supported by large-scale physical models, are presented to show the significance of reinforcement on stable, undermined fill performance. Finally the paper describes work which has been done to evaluate the suitability of so-called silicated cemented backfill. This system is, in principal, attractive for deep mining applications since transportation is in the "safe" hydraulic regime, while fill water run-off, segregation and shrinkage effects are potentially eliminated in the stopes. The results from various surface and underground trial pours are reported which substantiate the proposed use of this type of backfill at depth.

Jan 1, 2001

By A. R. Wagner, E. Berkman

The use of high-resolution seismic surveys in coal exploration and mine development is becoming established as a standard technique in the industry. Their most significant contribution is in the effectiveness of reducing the number of core holes needed to understand the complex geological nature of coal by identifying geologic faults and mapping coal seam continuity and relative coal thickness. With these goals in mind, a high-resolution seismic survey was conducted in 1980 in the Wasatch Plateau coalfield of Utah. As a result of the success of this initial survey, numerous additional surveys have been performed over the past six years.. The interpretations of these subsequent surveys have led to the location of faults, fluvial channel sandstones, and coal thickness trends. This paper presents a review of high-resolution seismic technology as applied to coal exploration followed by three case histories, two of which illustrate the utility of the technique related to coal thickness determination and faulting and one that serves as an example of pitfalls in interpretation.

Jan 1, 1987

By Gerald V. Jergensen, Edward J. Samuel

Slurry system are the principal method for storage and transportation of solids within and between concentration operations In a mineral processing plant. A slurry 1s a mixture of solid particles In water, or a chemical solution, that behaves like a liquid. The design of slurry transportation systems is generally analagous to pumping and piping water, but with a few notable exceptions: • The interaction of particle on particle affects slurry transport. • Particles often interact with the fluid, particularly when chemicals have been added to the system. • Particles have a frustrating tendency to settle from the slurry suspension, especially into locations not considered In the design. • Solids have an affinity for wetted surf aces and tend to wear them away. Slurry transportation systems Include a number of separate components, each requiring special design considerations. A systematic evaluation of each component of a slurry transfer system will help overlooking the small details that could cause operational headaches. Most slurry transport systems include: • A receiving sump or tank that provides for mixing and/or momentary storage of slurry. • A driving force.. by a pump, atmospheric pressure or gravity. • A suitable conduit for transportation.. pipes or launders. • A delivery objective.. another sump or process vessel, or distribution system to several process points. • A control strategy and design to regulate the transfer operation. The design of the slurry transportation system normally evolves through the following steps: • Finalizing the process flowsheet and establishing the weights and volumes to be handled. • Identifying and characterizing the various process fluids and slurries. • Defining critical and minimum transport velocities of fluids. • Selecting a pipe diameter (or dimensions and gradient) and

Jan 1, 1986

Some basic terms used in cost management and accounting include: - Cost. A sacrifice made to acquire goods or services, measured by the price paid. Technically, the sacrifice is called a cost until the benefits from the goods or services have expired, at which time the sacrifice is called an expense. In this text, the terms "cost" and "expense" are used interchangeably. - Revenue. An increase in the value of the firm resulting from the sales of goods and services. - Income. The excess of revenues over costs for a specified period. The term is often used with modifiers to indicate specific quantities on an income statement (e.g., pretax income; net income). - Activity. A measure of production work. Traditionally, physical production volume (tons of ore or units of product) has been used as the measure of activity. Other measures include direct labor hours, equipment operating hours, and quantity of materials or supplies consumed. - Responsibility center. A segment of an organization that is responsible for a specified set of activities. In mining, individual operating divisions can be treated as responsibility centers, known as profit or cost centers. Departments within a division are generally treated as cost centers. - Cost center. A portion of an organization having responsibility for achieving specified levels of cost. - Profit center. A portion of an organization having responsibility for achieving specified levels of profit (revenues and costs).

Jan 1, 1999

By Klaus Böde

Within the national and international strategy of the German based construction company HOCHTIEF, the majority of its business units is equipped with the comprehensive software package ARISTOTELES. This software is a powerful business information system for all accounting and controlling related processes in medium-sized and large construction and other related companies. Due to the complexity of the software, time constraints, and limited financial resources an implementation of this software package requires thorough project management. In this paper the relevant elements of project management are outlined based on practical experiences gained during this international IT - implementation project. Special emphasis is directed to the identification and management of potential risks. In this case particular acknowledgement was given to the multinational nature of the project and modernization of the business. This includes thorough reorganization of the company, significant changes of job requirements, and substantial trainings for its employees. At the same time key success factors like knowledge transfer, adoption of Czech legal requirements, commitment of management, networked thinking, and integrated project planning come into play. The costs for implementation had to be carefully evaluated because the software was implemented in a country with a considerably low cost I price level. All these impacts to the business had to be managed within the scope of transformation of business and political environment from socialist to market driven economy.

Jan 1, 2002

By Vas Choudhry

INTRODUCTION Traditionally mineral processing equipment has been procured based on (equipment) specifications prepared by the engineers. As newer materials of construction are being used for equipment manufacture and plant control systems become more sophisticated, the need for thorough and detailed specifications is greater than ever. For example, it is not uncommon to find plants looking at grinding circuits consisting of semiautogenous mills with variable speed, gearless, drives of large horsepower. Technical specifications for the mill, wrap- around motor and control system must, therefore, be carefully prepared to ensure that the respective equipment supplied by vendors meets overall grinding needs. Various engineering and design companies have expended considerable time and effort in developing the specification format. Equipment manufacturers have also given significant effort to developing data sheets aimed at collecting information regarding not only the duty of the equipment, but also the conditions under which it will be operated. As engineers moved from one company to another, the specification format became cross-fertilized and further developed. As a result, specifications on file with various engineers have improved considerably over a period of time. Equipment specifications from earlier projects are commonly used as a basis for tailoring new ones. To keep equipment specifications short, general technical considerations are often compiled as separate specifications. For example, general considerations applicable to the design, manufacture and supply of the mechanical equipment are consolidated under "Standard Requirements for Mechanical Equipment” and included along with that specified for purchase. As the economic feasibility of the project has been established during earlier studies, purchase-related activities can be initiated following completion of the specifications. Procurement itself is a major activity, however, in this chapter only those activities directly related to the purchase of equipment will be discussed. PREPARING EQUIPMENT SPECIFICTION Specification for process equipment or machinery is written in such a way as to define exactly what is required of the equipment. Generally, mechanical

Jan 1, 1986

By Boleslav Taraba, Antonín Taufer

Thermovision monitoring of surface temperature has been examined for the purpose of detection of spontaneous combustion of early stage. Measurements were carried out in bituminous and subbituminous coal mines. It was found that surface temperature heterogenities can be considered as common phenomenon in mine openings. However, the most of the observed temperature heterogenities were not connected with coal spontaneous combustion of early stage. These, so called [non-spontaneous combustion] temperature heterogenities in surface of mine openings were found to be caused by: l. Different conditions of heat transfer between opening surface and air stream; 2. Low temperature (natural) oxidation of coal; 3. Dissipated heat loses of working machine. Sites of early stage spontaneous combustion of coal were characterized by: 1. More significant, local rise in surface temperature comparing with low temperature coal oxidation; 2. Evolution of carbon monoxide with local concentration near the surface of such site more than about 15 ppm (bituminous coals) or 30 ppm (subbituminous coals). INTRODUCTION Mine fires are a serious hazard to life and result in a considerable loss of coal reserves. Thus, great attention is paid to investigation of new methods enabling already early detection of self-heating of coal. The earlier a fire is observed, the easier would it be to deal with. Detection methods used in coal mines are mainly based on: 1. [Mine air analysis]. Changes in composition of mine air are examined. Products of spontaneous heating of coal, not being present in mine air under normal conditions, are considered as indicators of anomalous behaviour of coal (carbon monoxide, unsaturated hydrocarbons) (Mackenzie-Wood and Strang, 1990). 2. [Temperature measurements]. Sites of higher temperature level comparing surroundings are looking for underground using various direct or indirect methods of temperature measurements. This paper summarizes experience from thermovision monitoring, as one of the latest indirect temperature measurement technique, used for the purpose of early detection of self-heating of coal in mine openings. INFRARED THERMOVISION Infrared thermovision device of AGEMA Infrared systems AB (Sweden) was used for the in situ measurements. The constant value of emissivity factor, 0.95, was pre-set as the most probable level of emissivities of coal and rocks in mine conditions.

Jan 1, 1993

By J. Slivnik, A. Stergarsek

[The site] [Z]irovski vrh uranium ore deposit is located in the extreme north-western part of Yugoslavia, some fourthy kilometers from the capital of Socialist Republic of Slovenia, Ljubljana, not far from the Italian and Austrian border. The sandstone type deposit of uranium ore with medium grade is located in a foothill of Julian Alps. The site shows some typical conditions for this region, which demand special attention in respect to the incorporation of an uranium treatment facility into environment. Among these specific conditions the following site characteristics should be mentioned: - populated area of agricultural and recreational value, - unconvenient climatic conditions with excessive rainfall and long lasting temperature inversions in the winter time, - very pure surface and underground waters which supply the drinking water reservate for large area including the capital of Slovenia, - sharp relief, - unconvenient geological structure. The choise of technology The intention to produce uranium and at the same time respecting the natural characteristics and existing uses of the site made the design of the ore treatment facility relatively difficult one. In general, there were two basic alternatives available perform the task. First alternative was to adopt the usual technological flowsheet with wet tailings disposal and with discharge of used water i.e. liquid effluents into the river. In order to prevent the negative impact of such technology on the sourrounding area sophisticated water purification installation and costly measures in wet tailings disposal e.g. impermeabilisation of large areas by concrete injections, large dam constructions, uncertain capturing of the water sources should be employed. Second alternative was to modify the usual flowsheet by employing the maximal recycling of liquid effluents to the process and to dispose the solid

Jan 1, 1980

By Terry S. Maley

Federally owned mineral deposits generally fall into one of three categories: (1) minerals locatable under the General Mining Law of 1872; (2) minerals leasable under the Mineral Leasing kt of 1920; and (3) minerals salable under the Materials Act of 1947. Unlike valuable deposits of gold, silver, copper, iron, lead, etc., which may be locatable, industrial minerals are acquired through a variety of methods depending on use, composition, and date of acquisition. Table 1 may be used to establish the method of acquisition for most industrial minerals.

Jan 1, 1987

By J. Wagner, P. Eger, G. Melchert

In 1991, LTV Steel Mining decided to close an open-pit taconite mine in northeastern Minnesota using a passive-treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. More than 50 Aft (55 million st) of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages. Before the closure, the annual median concentrations ranged from 1.5 to 50 mg/L. Copper, cobalt and zinc are also present but they are generally less than 5% of the nickel values. Median pH levels range from 5 to 7.5, but most of the stockpile drainages have pH levels greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential that a stockpile had to produce acid drainage, the lower the permeability of the capping material required Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to more than 90% for the plastic liner. Five constructed wetlands have been installed since 1992. They have removed 60% to 90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1 % of those for an active treatment plant. Because mine-drainage problems can continue for more than 100 years, the lower annual operating costs should pay for the construction of the wetland-treatment systems within seven years.

Jan 1, 2000

By P. A. Tuzinski, L. J. Dahl, N. R. Adamson, S. E. Brink, R. L. Blake

The US Department of the Interior, Bureau of Mines is developing a process to selectively extract manganese from oxide ores as part of its in situ mining research program. The Bureau is conducting site characterization studies of two manganiferous iron-formation deposits. These studies include: drill core, regional stratigraphic relationships from the existing geologic database, ore body geometry, geologic structure, hydrologic conditions, accessibility of ore minerals to leach fluid, surface subsidence potential and data collected from laboratory leaching experiments. This information is being used to evaluate the technical, environmental and economic feasibility of in situ mining of manganese for these two deposits. This paper will focus on the stratigraphy, mineralogy, ore textures, fractures, permeability and porosity as they relate to in situ mining.

Jan 1, 1994

By Marc Lemieux

A new moving cone optimizing technique will be introduced. In order to facilitate under- standing of the moving cone optimizer, a re- view of the principles of moving cone design technique is presented. A concept called the negative moving cone design technique is also introduced to help facilitate understanding of the moving cone optimizing algorithm. In the introduction to Subsection 3.3, the relationship of the mineral inventory modeling technique to the ultimate pit design optimization methods was reviewed. Five modeling techniques were described, and four mathematically provable optimizing methods discussed. The broad use of the regular 3D fixed block model was attributed, in part, to its applicability to automatic optimization methods of pit limit design such as the Lerchs-Grossman graph theory algorithm, and in part, to its systematic nature.

Jan 1, 1979

By J. E. Powell

Introduction The disposal of mine tailings, development rock, and other unwanted refuse material underground in mines by using pneumatic conveying techniques has been undertaken in the coal industry for many years. Similar equipment has been utilized for backfilling hard rock mines and is currently being applied in a gold mine in South Africa where development rock is being stowed in the mined-out stopes to help reduce the incidence of rock outbursts. On a limited scale, pneumatic conveying has been applied for backfilling uranium mines and one particular mine in New Mexico, U.S.A., has used this technique for 8 years. Other uranium mines in this area are now considerinq the dry backfill technique to eliminate the problems associated with hydraulic fill. The need to backfill in uranium mines is primarily of importance to improve ventilation, stabilize the pillars and roof, and possibly to extract a larger percentage of the uranium ore. If this can be achieved by utilizing the tailings from the beneficiation plant and using rock from the development headings which in itself may be slightly radioactive, then a greater benefit can be derived. Backfill can be achieved with hydraulic fill methods by running slurry into the stopes and allowing the water to decant and return through the footwall development entries to sumps for pumping to the surface. However there are several disadvantages associated with this method in that water is percolating throough the mine workings; it is necessary to build bulk heads in flat lying deposits; it is difficult to fill right to the back; and the decanted water takes with it quantities of the finer sand particles which results in maintenance problems with the mine pumps. Pneumatic conveying can overcome these problems in that the voids can be completely filled with high degree of compaction, heavy bulk heads are not necessary, the development rock can be added to the pneumatic system for disposal underground so eliminating hoisting cost to the surface, and cement can be added to the wetted material. To

Jan 1, 1980

By Malcolm J. McPherson

Observations of environmental parameters in mines have traditionally been made by means of hand-held instruments, these being employed as a basis to ensure that atmospheric conditions in the mine remain within limits commensurate with safety, to safeguard the health of personnel, and to ensure that statutory requirements are met. Thus, starting from the first flame safety lamps of the early nineteenth century, numerous portable instruments have been devised over the years to indicate levels of dust, temperature, humidity, and concentrations of gases including oxygen, methane, and carbon monoxide. Similarly, portable instruments have been used to measure air velocity and pressure. For routine monitoring purposes, hand-held equipment suffers from many disadvantages. Readings are intermittent, often with long delays between successive observations, making short-term trend analysis impossible. Portable instruments are more liable to damage; they are labor intensive and provide a very limited amount of information either for control or planning purposes. The 1960's and 1970's have seen an accelerated development of mine environmental monitoring equipment. Alarm methanometers to give localized audiovisual signals became more common. These were followed by a variety of instruments which gave local, then local/remote continuous records, particularly of methane concentration and airflow. More sophisticated transducers and transmission systems were developed allowing further parameters to be monitored. This led to a proliferation of paper strip and chart recorders which had to be maintained and inspected regularly for trends and abnormalities.

Jan 1, 1979

By George P. Demopoulos, Vladimiros G. Papangelakis, Dimitrios Filippou, A. J. Monhemius, G. W. Warren, E. Peters

A new method developed for the estimation of the activity of Ht in mixed sulfate solutions is described and examples of application of this method to the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3 from 298 to 473 K are offered. The method makes use of an "extended Debye-Hiickel" type of equation that was originally put forth by Das for pure H2SO4 solutions at ambient temperature. The treatment of mixed sulfate solutions was made possible by combining that equation of Das with a speciation algorithm which calculates the abundance of all species formed. The developed method, which also takes into account ionic strength and temperature effects, was used to generate hydrogen ion activity and speciation data for all possible acid/metal sulfate pairs of the system H2SO4-ZnSO4-FeSO4-Fe2(SO4)3. Finally, under the light of the reported data, specific examples of hydrometallurgical reaction systems are analyzed in terms of thermodynamics or kinetics. In particular, the systems discussed are: hydrometallurgical precipitation of hematite, solvent extraction of Fe(III), acid leaching of zinc ferrite, and oxidation of Fe(II) to Fe(III) by O2(aq).

Jan 1, 1993

By Donald A. Dahlstrom, Wai-Ping Kam

The mineral industry and individual processing plants are large consumers of energy. While energy conservation has received some attention in the present Federal Administration National Energy Strategy proposal it is obvious that the mineral industry should also continue to emphasize energy consumption reduction for important economic savings alone. As indicated by other studies, comminution is the largest single consumer of energy in the mineral processing plant (1.3% of total electrical energy consumption in the U.S.A.).1 Fine grinding is the largest portion of this amazing statistic. While substantial energy savings have been demonstrated by new machine developments and improved control methods, undoubtedly there are additional areas in comminution where substantial progress can be made. Some time ago, the U.S. Department of Energy published a report on "Comminution and Energy Consumption" by a committee composed of experts in the field of comminution from industry and academia. They identified the following potential for energy savings by specific areas? Classification device design 9-13% Comminution device design 3-16% Control 9% Grinding additive 3-6% Materials 3% It is apparent that the classification device had the first or second highest savings potential. Obviously, serious research consideration must be given to this technology area. A series of three papers have previously been written on the subject of two stage classification research work for ball mill operation by the authors. Accordingly, a brief review will be made. Previous Research Results on Two Stage Classification The hydrocyclone was selected as the type of classification equipment for this study as it represents by far the majority of the devices used in ball milling. While four different hydrocyclone circuits have been proposed by others,3 only two were considered in this work as illustrated in Figure 1. Flowsheet A is truly counter-current in nature in that the product from the ball milling circuit is taken from the first stage overflow

Jan 1, 1992

By N. S. Tanious

Three water-spray ventilation systems were tested to determine their effectiveness in diluting methane at a room and pillar coal mine face. These systems were: the shrouded nozzle, the spray fan, and the conventional nozzle system that is normally supplied with continuous miners. The testing was carried out in two stages. The air-moving capacities of the nozzles were first evaluated in a duct. The duct tests showed that: (1) the volume of air moved by the nozzle is controlled by the type of nozzle, the space around it, and its location relative to the duct wall; (2) the spray fan nozzles or the shrouded nozzles are both capable of moving air quantities up to 6400 cfm (3.02 m3/s); and (3) when the shroud was removed from around the shrouded nozzle, its bare nozzle moved between 9 and 65 percent more air. In the second stage of testing, a full-scale evaluation of the three systems was conducted. The three spray systems were mounted on a continuous miner which was positioned in an aboveground simulated mine entry. The simulated face tests gave the following results: (1) the standard nozzle system, which is mounted on the front end of the miner, is inadequate for diluting methane; (2) under the best testing conditions (lowest methane emission rate, highest primary ventilation airflow, and closest brattice set back), the slight improvement given by either the shrouded system or the spray fan is the same; and (3) under the worst testing conditions (highest methane emission rate, least primary ventilation airflow, and farthest brattice set back), the spray fan gave superior performance.

Jan 1, 1987