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By James G. Donovan, Mario G. Karfakis

A large percentage of Southern Appalachian coal reserves are located in seams less than 36" thick. As thicker and currently more mineable deposits are exhausted, methods of underground thin-seam extraction must be developed. Past experience with highwall mining of thin-seam coal has indicated that recovery rates tend to be lower than in conventional operations. It is suspected that this will also apply to underground thin-seam mining, regardless of proposed technology or mining method. Backfilling is one alternative for thin-seam coal mining; although backfill has been used extensively in hard rock mining its use in coal mining has been limited. The ability of backfill to provide additional ground support may enhance coal recovery by allowing for the design of undersized pillars. Backfill is capable of providing additional ground support by restricting lateral deformation of surrounding coal pillars and roof. This additional support can result in significant increases in recovery from thin-seam coal deposits. However, the overall feasibility of backfill is dependent on the in situ behavior of the fill material, the properties of the fill, the effects of the filling method on the total mining operation, and the cost of filling per extra ton of coal recovered.

Jan 1, 2001

By J. C. Yingling, R. J. Sweigard, P. W. Conrad, J. M. Ringe, D. H. Graves

Much of the land reclaimed since enactment of the 1977 Surface Mining Control and Reclamation Act is overcompacted. Research has shown that excessive compaction in replaced growing media is detrimental to the establishment of trees. If trees are to be grown on reclaimed surface mined sites, something must be done to alleviate this excessive compaction. Dry bulk density and penetration resistance are two soil parameters that can be used to indicate the level of compaction in reclaimed growing media. The University of Kentucky developed test cells on reclaimed areas at a surface mine in eastern Kentucky to determine the impact of tillage (ripping) on soil compaction and tree survival rate. The ripping methods being evaluated include shallow tillage using conventional farm equipment and deep tillage using a dozer with a ripping arm. Each test cell was planted with various species of trees, and for the first two years of tree growth, data were collected at these test cells for soil dry bulk density, penetration depth and resistance, and survival rate of trees. These data were statistically correlated to determine how ripping affects the relationship between soil compaction and tree survival rate.

Jan 1, 2003

By R. W. Smith

Though generally rather non-selective in nature long chain collectors nevertheless function in different ways in accordance with their own particular physical characteristics. Altering various parts of their structures such as chain length, type of chain, etc. can therefore substantially alter the adsorptive behavior of the collectors in a set environment. The effect of such structural differences of the collectors on physical parameters such as solubility, critical micelle concentration, acid or base strength, tendency to be expelled from the aqueous phase is discussed, as is also the effect of these parameters on flotation behavior.

Jan 1, 1989

By C. J. Savage

Rio Tinto Minera, S.A. operates in Southern Spain, at one of the most ancient mining sites in the world, using advanced computerised mine planning. This paper describes the development and application of the mine planning systems to the copper and gold/silver operations. It briefly covers the hardware configuration, and the advantages and improvements in mine planning achieved. The system's application started with the long term mine planning of Cerro Colorado (open pit) copper mine and was gradually extended to cater for the medium and short term planning requirements of the other operations of the Company. The base of the system is a mineral inventory established by the combined use of the geology and geostatistical methods, and compatible with the mine planning requirements. The planning system has three major components: one used for open pit design and long term mine planning, another used for blast evaluation and finally one used for short term mine planning. Recently, a fourth component has been added to the system for reconciliation between predicted and actual tonnages and grades. There is common data file transfer throughout the system.

Jan 1, 1986

By William Highton

If the economic situation in the Western World evolves on a path similar to that of the past decade, then we Mining Engineers must accept that one of the major cost factors in the production of deep mined coal is going to be that of labour. Whilst not trying to over-simplify matters it does appear that one of the ways of maintaining acceptable coal costs is by obtaining more coal without increasing manpower. One such way could be an increase in the use of the retreat method of mining. The paper theorises and illustrates case studies to show that as the Mining Industry extends the use of Longwall retreat mining systems in coal seams where the risk of spontaneous combustion exists, then the use of bleeder entries should be questioned. In addition to the spontaneous combustion risk, bleeder entry systems where the ventilation flow is not fully controllable cannot be construed as a safe and reliable method of controlling high rates of methane emission. These two major aspects alone should be sufficient ground for Mining Engineers to re-consider the practice of using bleeder entries. An alternative "The Back Return System" appears to offer most of the advantages for controlling the environment, without the disadvantages of the other system.

Jan 1, 1980

Iron ores may be upgraded by flotation of iron oxides or siliceous gangue using either cationic or anionic collectors. The electrostatic mechanism of adsorption can account for the complex chemistry involved. In industrial practice, only cationic silica flotation is used at present in North America. Some of the seemingly paradoxical phenomena of cationic silica flotation behaviors in meeting the demand for low silica concentrates are reviewed.

Jan 1, 1989

By R. A. Metz, Michael M. Easdon, Michael J. Fiannaca

Disseminated epithermal gold metallization occurs within a breccia unit interpreted to be a submarine debris flow. Gold is associated with oxidized pyrite, fluorite, and jasperoidal silica. A minimum of 8 Mt (9 million at) of open-pittable mining reserves will be cyanide heap leached as run-of-mine ore at a rate of 0.9 Mt (1.0 million stpy). Careful evaluation of the combined results of successive sampling projects has established the pit plan, minable reserves, and process metallurgy of the operation. The sampling procedure utilized for a given test depended upon geological interpretation as well as the procedures, successes, and failures of previous tests. This paper summarizes the sampling and testing procedures of the development effort in light of the project goals and attendant problems in achieving them.

Jan 1, 1992

By Louise H. Michaud

An interactive mine planning system that employs recent advances in 3D computer graphics capabilities and 3D geologic modelling to aid with the tasks involved in producing dragline mine plans was developed. As well as offering large potential saving in the time required to carry out the planning tasks, the system offers immediate visual feedback to the planning engineer. This can greatly aid in the conceptual understanding of complex geology and mine plans. The package incorporates the generation of a three dimensional Gridded Seam Model (GSM) as the basis for the development of the geologic database. This modelling method is capable of accurately representing rugged topography and multiple coal seams, including folding and faulting. The GSM is then integrated with an interactive graphics mine planning system in order to develop one model and one database for the generation of the mine design, the depletion of the coal resources and the movement of spoil material. The gridded structure of the model also provides the foundation on which all mine and spoil pile volumes are calculated.

Jan 1, 1992

By David M. Mchaina, Allan E. Hall, Siegfried Rohr, J. D. Botsford

Incidents associated with secondary dust ignitions in the mining of massive sulphide ore deposits are of major concern in Canadian underground metal mines. During stope or development blasting, a highly concentrated cloud of sulfide dust is created and may be ignited, resulting a secondary explosion which releases a considerable volume of sulphur dioxide and possibly other sulphur gases. The consequent pressure, heat and toxic gases can result in loss of life, significant damage to equipment and loss of production. These losses are expensive and should be prevented. Explosions of this type have occurred at the H-W mine of Westmin Resources mainly in the development headings and cut and fill stapes. This paper presents the results of a study conducted at the H-W mine to compare dust sampling methods for explosivity tests. The associated benefits and pitfalls of each sampling technique are examined. The investigative work conducted to develop and test preventive and control methods against sulphide dust ignitions is also discussed. The techniques which will minimize the risk of sulphide dust ignition in metalliferous mines are outlined. A review of current preventive and control measures practised at the H-W mine is also presented.

Jan 1, 1989

By V. Srajer

Several optimization approaches used by the Canadian mining industry were used to investigate surface coal mining operations in Canada. A computer program was applied to optimize truck/shovel systems and for various analyses. The analyses of eight western Canadian coal mines included investigation of fleet imbalance, under- and over trucking, development of the criteria for automated truck control, comparison study of various haulers and loaders, haulage layout, driving conditions, machine performance, servicing and maintenance policies, etc. Each property investigated supplied background information for the study and cooperated in optimization studies. The truck/shovel system optimization study is demonstrated as a test case to outline procedures and step-by-step instruction for similar applications.

Jan 1, 1989

By R. J. Wesely, Corby G. Anderson, L. Ernest Krys, John B. Ackerman, A. D. Zunkel, Suzzann M. Nordwick

Processing of the refractory precious metal ore from the Sunshine Mine is done in a fully integrated hydrometallurgical facility. This operating philosophy began with the construction of an antimony plant during World War 11, and it continued with the construction of a silver-copper refinery in 1984. The antimony plant relies on an alkaline sulfide ambient pressure leach combined with antimony electrowinning and antimony compound production. This plant is the largest producer of antimony metal in the United States. The one-of-a-kind silver- copper refinery uses a nitrogen species catalyzed sulfuric acid pressure leach system. The plant contains innovative downstream silver recovery processes as well as copper solvent extraction and electrowinning. This paper presents the pertinent process chemistries and flow sheets for the two unique hydrometallurgical processing plants.

Jan 1, 1993

By R. D. Lama

Coal mining is one of the major sources of methane release to the atmosphere by human industrial activities and is believed to contribute to -30% of the total methane emissions from industrial activities. In 1993, world saleable black coal production, attained almost 3.5 billion tonnes from which around 65% was produced underground. Coal in underground mines can contain high quantities of methane and some deep coal seams have methane content as high as 50 cubic meters per tonne of coal. Gas is re- leased during coal mining from the mined seam and in a higher degree from the neighboring unmined seams and gas bearing strata which are fractured as mining advances. This paper de- scribes a study which was undertaken to estimate the extent of methane emissions from coal mining in the world. Measured emission related data were collected from most underground coal producing countries in the world. The data included methane flows in the ventilation system, methane flows in gas drainage system, in-situ gas content, methane utilization and coal production. More comprehensive data were collected from a range of gassy and non-gassy Australian mines. Residual gas content of samples from run of mine were also measured. Using the Australian data, mathematical expressions were established to evaluate methane emissions as a function of coal production and in-situ gas content for other mines. These emission models were then used to evaluate the emissions for the countries or coal basins without measured emission data. Trends in methane emissions from underground mining for the year 2000 and beyond were also estimated.

Jan 1, 1997

By A. E. Hall, D. M. Mchaina

This paper outlines a proposed research project to investigate secondary sulphide ignitions. Sulphide dust explosions have resulted in loss of production and considerable capital and equipment replacement cost in Canadian mines. The practical application of laboratory test results to actual mine situations presents a complex problem and is a field requiring immediate investigation. The factors contributing to the outbreak of sulphide ignitions are not clearly understood. This indicates a need for future research to study the influence of blasting parameters, exhaust temperatures, and dust characteristics on secondary ignitions at source. The aim is to establish realistic quantities for each of the parameters and develop a model that will incorporate field and laboratory quantities. It may be possible to predict outcomes of sulphide ignitions when the parameters are known. It is also planned to study the techno-economic feasibility of the preventive and control methods. One aspect of planned future research requires quantification of some terms by obtaining measurements of pollutant concentrations and size distribution of the airborne dust in an underground environment immediately after a main blast. A blast-proof aerosol sampling package to measure the source term will be designed. This sampling package will consist of a sampling section and a shield which will be capable of withstanding a blast explosion. The accuracy in measuring the variables and combination of variables will be the main focus in this proposed study.

Jan 1, 1987

By K. G. Wallace

In 1982, the US Congress passed the Nuclear Waste Policy Act (NWPA) to provide for the development of an underground repository for spent nuclear fuel. This development will be managed by the US Department of Energy. In 1986, the President selected three areas for site characterization to determine their suitability for the development of an underground repository. Those sites were: (1) a site in volcanic tuff located at Yucca Mountain in Nevada, (2) a site in bedded salt located in Deaf Smith County in Texas, and (3) a site in basalt located in Hanford, WA. At present, conceptual repository designs are being developed for each site. A key element of a repository design is the underground ventilation system required to support construction, nuclear waste emplacement, and potential waste retrieval. This paper describes the preliminary ventilation system designed for the repository in tuff. The concept provides separate ventilation systems for the construction and waste emplacement activities. The paper further describes the means by which acceptable environmental conditions will be reestablished to allow reentry into previously closed rooms for the purpose of inspection, maintenance, or retrieval.

Jan 1, 1988

By G. T. Lineberry, B. R. Yama

Artificial intelligence research has produced several tools for commercial application. Some of the techniques that are widely used today include neural networks, fuzzy logic and expert systems. Artificial neural networks (ANNs) are excellent predictive, pattern recognition and data analysis tools. In the mining industry, ANN techniques are being used commercially for real-time process-control applications. Modeling of spatial data, ore-reserve estimation, tunnel design, long wall-stability prediction and geologic roof classification are additional applications in which neural networks have been applied successfully. In this study, a standard back propagation algorithm was used to train a series of neural networks for a real-world predictive task. After training and optimizing the neural network architecture, the performance of the network is measured on an independent validation set. Results indicate a mean error of less than 1 % between the actual and predicted values. A neural network model was developed for learning the spatial continuity of a mineral field and, consequently, for predicting sulfur values for given coordinates. The neural network not only performed satisfactorily, but in some cases performed even better than the kriging model.

Jan 1, 2000

By C. T. Twort

As technology and economic conditions allow mines to operate at ever greater depths, increasing demands are placed on the environmental engineer to adjust the capacity of the installed mine . - refrigeration systems. At the same time the engineer must satisfy the changing legislation, which demands that developments are carried out in as an energy efficient and environmentally accept- able manner. Following the trends outlined above, this paper is written to give an overview of the current and potential future refrigeration technology available to the mining industry. The effects that may be produced by the adoption in mining applications of the new generation of 'green' refrigerants are examined both at the design stage and when considering the viability of retrofitting existing systems so that they comply with the Montreal Protocol. An introduction to the concept of Total Energy Warming Impact (TEWI) is provided, with an explanation of its use in optimising system design and performance, and its incorporation as part of an environmental audit strategy. The paper concludes with a discussion of innovative refrigeration techniques and the possible future developments in legislation.

Jan 1, 1997

By S. C. Lamey, P. A. Hesbach

This study evaluated the use of regionally produced coal combustion products to neutralize and remove metals from acid mine drainage (AMD). Synthetic AMD mixtures were treated with a number of fly ashes and fluidized bed combustion (FBC) ashes. All of the ashes reduced the volume of the sludge produced and gave a faster settling rate than the sludge produced by treatment with lime. Faster settling allows greater throughput rates. In addition, the FBC ashes, which generally contain alkaline components used for sulfur capture, completely neutralized the acidity and, if desired, raised the pH above 10. The fly ashes, on the other hand, reduced the final volume of sludge but required additional neutralizing agents to attain a pH >5. The pH of the AMD can be taken to above 10 to insure complete removal of manganese, or it can be taken to a more neutral pH of 7 or 8 to allow for the safe introduction of the aqueous phase into ponds or streams. The process combines two industrial waste products to reduce the disposal volume of one of the waste products and to produce an environmentally safe aqueous discharge.

Jan 1, 2002

Bigger is indeed better in today's surface mining operations. That is especially true regarding haul trucks. Building larger, "supersize" trucks, however, means designing more powerful engines and drive systems that are also more efficient and environmentally friendly. And miners are demanding that these trucks have longer service lives with minimum maintenance. So truck makers are teaming with engine manufacturers and mining customers to design these larger trucks that will ultimately lead to reduced mining costs. About 180 of those truck makers, engine designers and miners gathered in Tucson, AZ in September to discuss the state of haul trucks in today's mining environment. Haulage 2000 was sponsored by World Mining Equipment and attracted attendees from around the world. Manufacturers described the latest in haul truck advancements. These included the design of more powerful engines, improvements to mechanical and ac and dc drive systems and suggestions on how to reduce maintenance spending. Technology improvements in tires for larger struck was discussed as was the cost efficiency of new, lighter-weight bed liners. The following is a summary of a handful of the presentations.

Jan 1, 1997

By Gordon D. House, J. B. P. Sawyer

The Bannockburn gold prospect is a new discovery in Ontario's oldest gold camp at Eldorado, eastern Ontario. Mono Gold Mines Inc. of Vancouver, British Columbia, acquired the property in 1980 and in 1984 discovered a previously unreported gold bearing quartz vein system to the northeast of the old Bannockburn Mine. Extensive diamond drilling carried out since 1985 defined a quartz vein system over 475 m (1 ,500 ft) of strike to a depth of over 105 m (350 ft). Limited underground exploration by decline to the 22.9 m (75 ft) level in 1988 confirmed the continuity and tenor of the quartz veins. Gold occurs as native metal with minor sulphides and bismuth tellurides in a quartz carbonate vein system within metasedimentary and metavolcanic rocks of the Grenville Province. Metallurgical test work on a surface bulk sample was favourable. Estimates of drill indicated reserves have been made as well as reserves based on the limited underground exploration.

Jan 1, 1989

By Ning Liu, Xuming Wang, Yongqiang Lu, Jan D. Miller

Bench-scale flotation experiments have been conducted to study the effect of nonionic polyethylene oxide (PEO) polymer surfactants on the flotation of Florida phosphate rock. It has been found that PEOs having a molecular weight from 1,200 to 8,000 are effective. Flotation results demonstrate that the addition of nonionic PEO has a favorable effect on phosphate flotation, especially on the flotation of coarse phosphate feed. At about the same collector level, phosphate recovery can be improved by 10-30% with PEO addition. The surface chemistry of phosphate flotation using the fatty acid/fuel oil/PEO system has also been studied to better understand the phenomena involved. The increase in phosphate recovery with PEO addition has been attributed to improved dispersion of fatty acid, which leads to better froth stability and a more hydrophobic surface state.

Jan 1, 1999