Search Documents

By J McNee

Pike River Coal Limited (PRCL) is developing the Pike River Coal Mine in the Paparoa Ranges of New ZealandÆs South Island. The mine is being developed to extract a coking coal deposit of the Brunner Seam, some 46 km northeast of Greymouth, using a combination of continuous miners, road-headers and hydraulic extraction.   The mining area is located within Department of Conservation (DOC) land and is adjacent to the escarpment of the Paparoa Range and the Paparoa National Park. The mine will use its elevation advantage to hydraulically flume coal from the working faces to the pit bottom area where it will be slurried to approximately 35 per cent density of solids and pumped down a slurry line to the coal prep plant some 10.5 km down the Pike River Valley. The coal will be sold on the export market as a high quality coking coal for international steel making.   PRCL faces significant challenges to achieving the goal of cost effective production. The remoteness, high rainfall (greater then 6 metres per year on average), temperature variation and restrictions on access to this subalpine environment have driven the project to develop some distinctive solutions. These include the establishment of survey control in such a difficult environment with vertical and sub-vertical rock faces, significant vegetation and steep slopes by using helicopter survey, aerial photography and LIDAR (Light Detection And Ranging) aerial survey. PRCL has also commenced designing the placement of the main ventilation fans in an underground chamber in the stone drive.

Jan 1, 2007

By J. H. Stears

Increasing use of Birmingham and other roof trusses prompted a Bureau of Mines study of support forces produced on a mine roof by these members. Equations, obtained from laboratory and field tests, are given for calculating the contact forces between the roof strata and a typical truss. Actual contact forces for a specific truss are difficult to estimate because of variable friction loss at the contact points. A finite-element analysis, using typical contact forces, indicated that trusses have a negligible effect on the stress field in massive, competent roof strata. The effectiveness of trusses in supporting broken rock strata was not analyzed. However, experience has shown that trusses are effective in supporting incompetent roof.

Jan 1, 1988

By H. B. FERNALD

THE interesting and carefully developed formula which Professor Bucky presents for answering the question of whether proposed new equipment will give a net return on investment equal to or greater than that on present equipment starts with an assumption that the management may make this relative return a determining factor in its decision whether or not the new equipment should be provided. I do not question that in some cases the management may take this position, but I would point out the error involved in so doing. The proper test is not a comparison of the return on new as compared with the return on old investment, but is rather a comparison of the return on a particular new investment as compared with the return which would be obtainable from some other new investment which now might be made. Then I would point out that I believe Professor Bucky is in error in using as a factor in his computations the item of unamortized cost of old investment. The financial advantage to be derived from a new investment does not depend on the extent to which we may in the past have written off the cost of old equipment, nor does it even depend upon what was the original cost of that old equipment. Even the salvage or resale value of the old equipment will only enter into the picture to the extent that the present salvage or resale value differs from the ultimate salvage or resale value otherwise to be obtained, after due allowance for the interest factor.

Jan 1, 1930

By D E. Siskind

The Bureau of Mines performed a comparative study of nine sites at eight surface coal mines to determine if the presence of near-surfaced underground abandoned workings resulted in the generation of adverse long-duration, low-frequency blast vibrations. Six of the nine sites had underlying workings, and two had thick layers of low-velocity unconsolidated surface material.

Jan 1, 1990

By Claude K. Howse

The area covered by the present paper consists of about fifty square miles in the immediate vicinity of the settlement of St. Lawrence, which is on the Southern extremity of the Burin peninsula on the south coast of Newfoundland. Physiography Physiographically, the area is part of the Atlantic upland, equivalent to the New England province of the United States. Evidences of two erosion surfaces are to be seen truncating the intrusives and the folded volcanics and sedimentary rocks. The older erosion surface is represented by small monadnocks from 650 to 750 feet in height with the younger surface covering most of the area and characterized by rounded subdued topography with maximum relief of two to three hundred feet and numerous ponds and bogs. These surfaces have been correlated with the High Valley and the Lawrence peneplains of Newfoundland. On the Avalon peninsula, these peneplains have elevations of, respectively, from 1,300 to 1,700 feet and from 500 to 1,000 feet. Glaciation The entire peninsula has been glaciated, with lee-and-stoss slopes showing on the highest hills in the immediate vicinity, many of which have striae and erratics on their summits. The lee-and-stoss slopes, the glacial striae, and the distribution of certain rocks found in the drift and whose source outcrops are known, indicate a southward direction of ice movement.

Jan 1, 1951

By Hugo Medina Medina

El presente trabajo refiere el proceso de mineralización de fluorita en la mina Pasto Bueno, Ancash, el cual por sus características mineralógicas y estructurales es considerado como potencialidad geoeconómica en tungsteno. El estudio de la evolución geo-técnica del yacimiento comprende la estratigrafía, geología económica y los rasgos de la evolución geo-técnica del yacimiento Pasto Bueno a través de un esquema vinculado al desarrollo geosinclinal andino mesozoico y los conceptos de la Neo-técnica global. Una vez realizado estos estudios, se busca una mejor exploración y desarrollo minero del tungsteno-fluorita en el territorio nacional a fin de autoabastecerse de la fluorita en el campo de la siderúrgica.

Nov 20, 1978

By Ben Murphy, Alejandro Yanez, Tatu Miettinen

"Flotation using large volume cells has grown in importance during recent years, particularly given the increasing demand for minerals whilst ore grades are decreasing. Outotec introduced the TankCell® e300 in 2007 to enable concentrator plants to process these higher tonnages. From the beginning, TankCell® e300s with FloatForce® mixing mechanisms have demonstrated good metallurgical performance with decreased operating costs and high availability. This paper deals with specific engineering challenges that need to be considered when installing these units rather than giving examples of performance. Today there are over 100 TankCell® e300s operational worldwide. As more of these units are installed new technical challenges are encountered and solutions developed to maximize their productivity. Lessons have been learnt by operators, engineering companies and the cell manufacturers on how best to design and layout these cells in modern concentrators to ensure smooth transition from design to installation to operation. This paper presents information on important design considerations and learning that has been obtained through the design, installation and commissioning of the TankCell e300 around the world. Areas pertaining to cells layout such as feed and discharge arrangements along with items of metallurgical concern such as sampling, reagent addition and the potential benefits of installing a variable speed drive on the motor will be covered in depth."

Jan 1, 2014

By Carl R. Christiansen

Excellent underground industrial sites and warehouse facilities have been constructed in Europe and at several locations in the United States. Many quarry and mine operators are considering, or should consider, the possibilities of the development of their mineral properties in such a manner as to make underground space that is suitable for a secondary industrial use. Before proceeding with mine or quarry development, the operator should answer the following questions: 1) Is there a need for underground industrial space in your geographical area? 2) Is your deposit suitable for development of space for industrial usage? 3) If the deposit is suitable, what methods of development can be used? 4) What are the comparative economics of the different methods of space development? An honest analysis of the first two questions may eliminate the need for proceeding to the third. Affirmative answers to questions 1 and 2 should be followed by the engineering and economic studies required in response to questions 3 and 4.

Jan 1, 1975

By L. S. McNickle

[Commonly accepted maintenance methods are being outdated by the rapid acceptance and use of more complicated hydraulic circuitry on modern mining equipment. It is no longer adequate to use the maintenance program to merely repair or sustain equipment operation. Ever increasing operating costs place a huge premium on lost production time. It has, therefore, placed the maintenance programs in the position of being required to alleviate equipment malfunctions on production shifts and still attain the maximum unit life from each component part.]

Jan 1, 1961

By William C. Larson

A study was conducted by the Bureau of Mines to provide quarry operators with information regarding (1) the effects of jointing and bedding on rock fragmentation when bench blasting in two small-scale (2.5-ft) limestone benches, and (2) the successful use of inexpensive equipment and field techniques to determine the orientation and spacing of joints and bedding separations within the quarry. Using inexpensive equipment, such as a pocket transit and steel and paper tapes, joint and bedding separations were mapped and their frequencies measured. Results from two small-scale bench blasts in the Stewartville member of the Galena limestone formation showed that when the row of vertical blast-holes was oblique to the vertical joint orientations, the backface expression was outlined by two relatively large triangular protrusions (joint surfaces). In this blast, part of the rock burden was unbroken. When the line of vertical blastholes paralleled a predominant joint set, all of the rock burden was broken and displaced. The thickness of fragments that had been displaced by a blast correlated with the observed bedding thickness in the bench.

Jan 1, 1974

By Gill Montgomery

Although fluorspar is considered an industrial mineral by usage and value, its geological occurrence and the mining and milling methods employed make it more akin to the non-ferrous metal ores. Likewise methods of exploration for it are more like those used in the search for lead and zinc, with which fluorspar is often mixed. In fact, it often takes the mixture of fluorspar, lead, zinc, plus maybe barite to add up to enough recoverable values to make the mineral an ore by definition. This is so true where the fluorspar portion is low grade, perhaps less than 25 percent. Until the development of modern steel milling in World War I times, the invention of aluminum smelting, and development of the fluorine chemical industry and air conditioning, there were few uses for fluorspar aside from ceramic fluxes in the flint glass industry and for uses as glazes for pottery and china. Pure fluorite crystals have long been admired as semi-precious and ornamental minerals of many delicate colors.

Jan 1, 1983

By Robert O. Vernon

The discussion of water and pit mining together is most appropriate. In fact, water can be considered a mineral and a well a narrow pit. Thus, of all the mineral resources mined, water is probably the cheapest, most valuable and least valued. The delivered price, including mining, transportation, storage and marketing rarely exceeds ten cents per ton, and our economy would cease without it. The time has come when the public must recognize that the extraction of a mineral resource from the land is a necessary and inevitable result of the industries? attempt to meet the demands of a growing economy. In so much of Florida, the lands mined can, with forethought and planning, be left as improved real estate, water conservation and management lands. On the other hand, the mining industries must face up to the need for the reclamation of land and compact with themselves, appropriate governmental agencies and with the mining states to restore mined lands to usefulness. Of limestone, sand, and clay 90 to 100 percent of the mined material is used, but with planning and specing, these pits, if they penetrate the water table, become valuable as real property. Phosphate, which returns about 70 percent of the mined materials to the pit, can reclaim the land for many purposes.

Jan 1, 1966

By G. E. Maryniak

To date, human space exploration has been almost completely dependent on the use of resources carried with astronauts and cosmonauts from the surface of the Earth. The only exception to this has been the harvesting of solar energy to power space stations like Skylab, Salyut and Mir for long-duration missions. This dependence on materials which must be transported into orbit at costs in excess of $5000 per pound is the fundamental limiting factor in space exploration and operations. It is likely that launch costs can eventually be greatly reduced by means of such innovations as true single stage to orbit vehicles, aerospace planes, or serial electromagnetic or laser launch systems. However, the Earth will always remain an expensive source of materials for space construction and for basic commodities such as propellant and life support liquids and gasses. Fortunately, abundant sources of materials exist which are already in space, outside of the Earth's deep gravity well.

Jan 1, 1992

This paper investigates the adequacy of current gas monitoring techniques to adequately detect spontaneous combustion in underground coalmines. Despite being in the 21st century spontaneous combustion continues to occur in underground coalmines sometimes being detected only at a very advanced stage. Control of the incident is often then very expensive and time consuming. The adequacy needs to be assessed not only from the point of view of the analysis technique be it tube bundle, gas chromatograph or real time sensor but also the number, location and sampling frequency of the monitoring locations. Recommendations are made to optimise monitoring processes and recognise limitations of current techniques.

Jan 1, 2005

By H Jalalifar, N Aziz

In the ten years since the University of NSW proposed a pillar design methodology for bord and pillar operations, the Australian coal mining industry has changed substantially. What was primarily a bord and pillar design approach is now being applied to chain pillar design in longwall mines where the requirements are substantially different. The dimensions of chain pillars can impact on tailgate conditions (roof, rib and floor), seal performance, and surface subsidence. The status of chain pillar design practice in Australia is reviewed, with a focus on defining pillar strength, chain pillar loading, and assessing the performance of the roof/pillar/system. A new pillar strength equation is proposed for Australian coal that applies for all width/height ratios. An alternative analysis of probability of failure of chain pillars is presented.

Jan 1, 2005

By A. K. Fallaw, G. Wang, L. R. Moore, S. Dobson, Y. Xiong, J. Gu

"As ores degrade, mining techniques and chemistries change to meet market demand and maintain product quality. The balance of recovery and grade is a significant challenge in the Crago Process where an anionic collector is used to float phosphate, followed by acid scrubbing, then an amine float to improve product grade. As the grade is a requirement for DAP and MAP production, recovery is the criteria to suffer. Phosphate losses in the amine float can bring overall recovery down by as much as 18%, creating a growing need to think outside the box to improve recovery. This paper will focus on the theory of amine tail recycling and the best methods to optimize the overall phosphate recovery by recycling the tails from the cleaner flotation step. INTRODUCTION In 2014 the total US phosphate production was down 13% over the prior year, from 31.9 to 27.1 Mt, which accounts for 12.32% of the world’s phosphate rock production. Florida and North Carolina phosphate production accounted for 80% of total US phosphate production, which was down from 85% the previous year. This decline is due in part to the closing of the last phosphate mine in Polk County, FL - which had an operating phosphate mine for over 100 years (Gurr, 2015). Another factor contributing to the reduction in contribution from FL & NC is the increasing challenges in beneficiating the remaining ore deposits. The Central Florida mining district has historically been in the Bone Valley deposit, where raw apatite was abundant with P2O5 values as high as 15%. The Bone Valley ore also had characteristics favorable to beneficiation to 27.5-29.7 %P2O5 while achieving recoveries above 86%. The move southward into the Hawthorne Formation has seen the ore feed grade hit some historic lows, and the matrix characteristics pose more challenges to phosphate producers. The Hawthorne Formation experienced lateritic weathering after the Bone Valley formation which altered the apatite to aluminum phosphate minerals, and alteration of montmorillonite to kaolinite, releasing MgO that caused the dolomitization of the top of the Hawthorne limestone (Cathcart, 1966). Elevated levels of dolomite can yield an increase in slurry viscosities, reduce production rates, and increase energy costs in the wet-acid fertilizer process. The MgO will also act to dilute grade, making it more difficult to achieve a standard 18-46-0 product (McHardy, 1981)."

Jan 1, 2016

By John Owens, Hamid Maleki

Efficient and safe use of mobile roof supports (MRS) depends on the interaction between the MRS and coal strata. Of particular interest to this study are the mechanics of strata deformation as influenced by geologic conditions, pillar extraction methods, and MRS load-bearing capabilities. To provide a better understanding of the mechanics of strata deformation, the authors have collected and reviewed measurements of convergence and stress in one western U.S. mine and have completed pseudo-three-dimensional, boundary-element modeling for two typical pillar-pulling plans. Stress distribution in the mine roof above pairs of MRS’s was calculated to demonstrate how MRS’s contributed to the control of roof block movements. It was shown that overall stress and roof-floor convergence patterns were most influenced by the stiffness of coal-measure rocks and by pillar-pulling sequences and layouts. MRS’s and other support systems play a critical role in controlling the stability of both the immediate roof and the middle roof for a distance of up to 18 m (60ft) above the seam. MRS’s provide unique ground control advantages over other types of secondary support by significantly reducing the time between mining and installation of secondary support. Although MRS’s are similar to posts in stiffness and capacity, they are more effective than posts under static loads because they can yield and still maintain loads at near-peak capacity, whereas posts fail and loose their ability to limit mine roof deformation.

By R. J. Grace

Carbon in the form of coke is used as a reactant in various chemical and metallurgical processes, The high cost of by-product coke along with its periodic lack of availability and high investment necessary for additional by-product recovery facilities indicate the need for a low-cost production unit based on a new procedure for coke manufacture, Traveling-grate coking-stokers were developed by Shawinigan Chemicals Ltd. to produce coke required for carbide manufacture, They were adapted to kilns so that the hot volatile gases could be used for lime burning, Their operation has been described in various patent disclosures (1, 2, 3), and their application to rotary lime burning kilns has been described by Andersen (4). Details of the process and plants have also been published by Kurt Baum (5,6).

Jan 1, 1958

By Roger L. Keller

This paper covers the design and test blast procedures for several drop shafts and edits leading to the completion of a recent Rochester Pure Waters Expansion Project . Due to the projects "in-town" presence, and its close proximity to many sensitive vibration sites, very stringent ground vibration limitations and guidelines for blasting were places on each site.

Jan 1, 1991

By Patrick Wong

The design of piling platforms is addressed in BRE (2004) for both fine grained and coarse grained subgrades. However, for coarse grained subgrades, piling platform designs can often be overly conservative due to either conservative assumptions on soil friction angle, or concerns over density variations of granular fill, particularly for made-ground. This paper provides guidelines on economic design of piling platforms on coarse grained subgrade by providing recommendations on ground characterization, assessment of soil properties and the use of non-linear stiffness soil behavior. An innovative performance-based design approach is also introduced, utilizing proof rolling with associated testing and interpretation using small strain theory to overcome concerns regarding potential ground variability of made-ground. A case study is presented to demonstrate the successful application of this performance-based approach to avoid having to construct a new piling platform over a 2 ha area. Small strain, non-linear stiffness theory was used to enable a practical proof rolling pressure to be adopted without having to reach the design or ultimate operating pressure. The author considers that the performance-based approach adopted on the case study may be similarly applied to a range of other projects to derive economic solutions.

Nov 1, 2022