Search Documents

Arizona E. P. MATHEWSON, Chairman F. W. MACLENNAN, First Vice-chairman CLYDE E. WEED, Second Vice-chairman E. D. GARDNER, Secretary-Treasurer Box 4097, University Station, Tucson, Ariz. I. H. BARKDOLL HENRY F. EASTER MICHAEL CURLEY R. D. LEISK Boston Meets first Monday each month, October to May, inclusive ROBERT S. WILLIAMS, Chairman GLEN F. JENKS, Vice-chairman F. LEROY FOSTER. Secretary-Treasurer Rooms 6-202, Mass. Inst. of Tech., Cambridge, Mass. HOLCOMB J. BROWN ESPER S. LARSEN

Jan 1, 1936

This paper discusses the application of a computerised model based on genetic algorithms (GAs), called GenRel, for reliability assessment of underground mine hoisting systems. The purpose of this paper is to investigate whether GenRel can be applied to predict future failure data of a mine hoisting system based on historical records of failures. The incentive of selecting the GAs for prediction of failures is that GAs are a class of evolutionary algorithms which imitate the biological evolution procedures such as reproduction, selection, crossover and mutation. The reliability of mining equipment changes over time due to an array of factors (eg equipment age, the operating environment, number and quality of repair). These factors affect the equipment's failure patterns and have complex impacts on the equipment's reliability characteristics. The failure patterns are assumed to follow a biological evolution process, and thus GAs can be considered applicable in the modelling process.To conduct the reliability assessment, a study was carried out with historical failure data of hoists in the time period from January to December 2007. Two failure data sets of two mine hoisting systems were collected from two typical underground mines in Ontario, Canada, which are denoted as the NA mine and the SB mine. The failure data sets were prepared in the format of time between failures (TBF). Then, these data sets were entered in GenRel to generate predicted failure data sets for the period of January to March 2008. The paper discusses the statistical similarity of the actual failure data sets for the period of January to March 2008 with the predicted failure data set generated by GenRel in the same time period.

Dec 6, 2010

By Stanton L. Tainter

"As an adjunct to its minerals-investigation program, the Bureau of Mines has developed a number of operating devices and techniques worthy of note. This paper, prepared under the supervision of J. H. Hedges, chief, Tucson Branch Mining Division, and under the general supervision of Lowell B. Moon, chief, Mining Division, reports upon certain methods devised to overcome difficulties encountered in cementing of diamond-drill holes at a Bureau of Mines project at Christmas, Gila County, Ariz.Pressure grouting was employed to recondition a caved hole it was desired to reopen and deepen. The hole, which had boon stopped 7 months previously at a depth of 488 feet, was caved below 449 feet in a contact zone of claylike, altered diorite and crumbly metamorphosed limestone. As other means of obtaining moderate pressure were not available, carbon dioxide gas, drawn from tank of liquid carbon dioxide through a pressure reducing and regulating valve, was used. The hole was reopened successfully with 12 grouting jobs.Another hole, where cawing from several water-bearing fractures between 202 and 232 feet gave trouble, was successfully cemented by the use of a grouting plug. An attempt to cement through the rods had failed, owing probably to agitation caused by water currents. Pressure grouting through the caning set above the cave could not be need, because water was forced up outside the casing when pressure was applied. The problem was solved by using a wooden plug 1-13/16 inches in diameter, which, when soaked in water, expanded to a tight fit in an AX hole. A hole was drilled through the plug, and a rubber flap valve was nailed to the lower end. In the upper end of the plug the hole was enlarged to fit loosely over an EX rod coupling finished smooth. The plug was lowered on the end of the drill rods to a point about 10 feet above the cave, where it was allowed to expand tightly to the hole. Cement grout was then pumped through the rods, and the rods were removed from the hole. After allowing time for the cement to set, the wooden plug was chopped out and drilling van resumed.Over 300 tests were made to determine the type of cement most suitable for use on the Christmas job, and the effect of cement-water ratio, temperature, and various admixtures on workability, setting time, and strength. The results of these tests, described in detail in the body of this report, indicate the desirability of thoroughly testing available cements when it is necessary to drill holes under difficult conditions that may cause failure.When it became desirable to reopen and deepen a caved drill hole, it was considered easiest to recondition the hole by pressure grouting, As other mans for obtaining moderate pressure were not available, a method utilizing carbon dioxide gas was employed. The hole was reconditioned successfully with 12 grouting jobs."

Nov 1, 1949

President-Mrs Andrew E Beer, Richardson Ave, Sea Cliff, L I, N Y First Vice-President-Mrs Lyman H Hart, 6-F Essex House, Garth Woods Apts, Scarsdale, N Y Second Vice-President-Mrs John R C Mann, 90 Edgemont Road, Scarsdale, N Y Third Vice-President-Mrs Edward P Chapman, Jr, 2632 Vista Larga Dr N E, Albuquerque, N M Fourth Vice-President-Mrs R A Cattell, 7717 14th St, N W Washington 12, D C

Jan 1, 1959

By Eti Purwaningsih, Widi Astuti, Erik Prasetyo

Selective-reductive leaching of manganese from low-grade manganese ore using tannic acid as a reductant in acidic media was demonstrated by XRD, SEM-EDX characterization, and batch leaching studies at room temperature. The pH change in the liquid phase before and after leaching revealed that selectivity of manganese over iron was due to the hydrolysis of iron. The acidity in the liquid phase during leaching was dictated by two mechanisms: proton-consuming reaction (manganese oxide reduction by tannic acid) and proton-producing reaction (ferric ion reduction by tannic acid to produce ferrous ion). Based on the leaching studies, the more prevalent reaction between these two was determined by initial leaching conditions: tannic acid concentration, sulfuric acid concentration, liquid-solid ratio, temperatures, and agitation time. Kinetic studies revealed that maximum recovery was attained within 6-h agitation, which indicated a product layer diffusion process.

By Dan Brown

A method is outlined for computing the contribution of a micropile group to global stability of a sliding mass. The forces in the micropile are computed in a way which accounts for the effect of soil mass movement on the mobilization of axial and shear forces and which maintains compatibility between shear and axial force as a function of displacement. The method provides a rigorous model to incorporate the pile forces into the stability calculations, including the effect of pile forces on the resultant shear and normal forces at the sliding surface. This paper demonstrates the proposed solution using a simple example slope.

Jan 1, 2007

By Emad Farouz

The resistance of very dense glacial outwash formations consisting of sand, gravel and cobble formations can be quite high, and techniques for measuring the strength and deformation properties often cause engineers to underestimate the strength of these layers in drilled shaft design. More realistic measurements of this dense formation can be achieved with slotted steel casing pressuremeter tests. To minimize disturbance and achieve accurate measurements, drilling a pilot hole prior to probe insertion is necessary. Characterizing geologic formations that contain significant amounts of gravel and cobbles is challenging because of scale factor. Inserting a standard pressuremeter probe into this formation without damaging the membrane is difficult. This paper presents a case study for the IR-75 project in Dayton, Ohio, USA, where these dense materials were characterized using a slotted casing pressuremeter, optimizing design by providing more realistic properties of these materials.

Jan 1, 2006

By S. Matsuyama, S. Tomita, H. Kawahara, G. Deguchi

A proper management system of coal mine methane gas associated with underground mining activities is essential for the mine safety due to its nature of explosion. Optimum design of the mine ventilation and gas drainage need accurate prediction of gas flow rate emitted by mining activities. Permeability to gas, which is affected by stress conditions of surrounding rock mass, governs the emission rate of the gases. JCOAL has developed a three dimensional FEM simulation program named Mine Gas Flow 3D (MGF-3D). MGF-3D is designed to predict the volume of methane gas emitted from surrounding coal and rock seams based on stress distribution and permeability change which are determined by 3D stress analysis. In MGF-3D, stress change and/or expansion of fractured zone affected by mining is calculated at the first and then gas emission into roadways and longwall panels under the determined stress conditions is calculated using Darcy’s law. MGF-3D also can set up a number of pre-drainage holes and estimate drainage gas volume from each hole. This function makes MGF-3D remarkable program. These simulations for gas emission can contribute to mine gas utilization plan. Comparison between actual measurement of gas emission in the underground mine and simulation results has been performed and availability for the mine safety and problems with MGF-3D are discussed in this report.

Jan 1, 2003

By A. E. Dabbagh

Saudi Arabia’s mineral potential offers development target that compliment the national effort to diversify the income of this oil and gas economic based nation. Ma’aden, a joint stock company with paid-up capital of US$1 billion, has from its inception in 1997, actively developed in-house engineering and management skills to transform the Arabian shield’s mineral potential into such real projects. Gold mine operating facilities of 100,000 oz/yr underground and 50,000 oz/yr open pit are de-scribed, as well as 3 targets, two of which are underdevelopment; Al Hajar (3,000 tpd at 2.5 gpt Au)and Al Amar (5,000 tpd at 20 gpt Au). Emphasis is also on exploitation of phosphate rock and down-stream fertilizer products, based on the Kingdom’s107,000 sq. km. northern basin geological reserve. Al Jalamid, the prime target, represents 216 million tonnes of these P2O5 reserves. Saudis and expatriates, together, lead international engineering companies and contractors operating and developing these facilities.

Jan 1, 2000

By ALICE V. Petar

Among the rarest of the rare metals are four that are linked together by a common historical background as well as by chemical relationship. With the excep- tion of indium, these metals are likewise characterized by the patriotic nature of the names given them by their discoverers. The existence of gallium, germanium, and scandium, was predicted by the Russian cherist, D. I. Mendeleeff some time prior to their discovery; and these elements might well have been overlooked, had not the search been stimulated by the urge to confirm the scientific hypothesis of their existence. Nowhare found in sufficient quantities to attract attention, these little known elemente are nevertheless widely distributed in the earth's crust. So far they are found commercially mostly in the sulphide ores of zinc and must be considered as being largely curiosities of the zinc smelter. Recent progress in electrolytic zinc refining, however, now gives promise that the way may be open for the recovery of these very rare metals in larger quantities-- possibly in quantities sufficient to permit of their finding commercial utilization.

Nov 1, 1930

By Chris Brown

"The Island Copper plant was designed and built by Fluor Utah Ltd, in conjunction with Utah design staff, Originally designed to treat 33,000 tons/day (t/d) of ore, the current average milling capability is 38,000 t/d (Nov'74). The first of six semi-autogenous grinding lines was brought on line in October 1971, startup of the remainder being governed by equipment delivery schedules.The summer of 1973 saw the start-up of an additional three ball mills, and attainment of the present production level. The current process flowsheet is shown in simplified form.CRUSHINGThe crushing circuit is relatively simple, comprising single stage crushing of the ore followed by screening to fine and coarse fractions.The crusher is a 54 x 74in. Allis Chalmers Superior Gyratory with a setting of 9-lOin., driven by a 500-hp motor. Trucks dump on three sides of a rectangular dump pocket. An 84in. x 20ft. link belt apron feeder draws crushed ore from a 250-ton surge bin below the crusher, discharging onto a 72in. wide inclined steel cord conveyor belt. A fixed splitter box at the conveyor discharge separates feed to two parallel Jeffreys 6 x 20ft. vibrating grizzlies for screening into +4in. and -4in. fractions. The fractions are collected on short reversible conveyors which feed the coarse and fine ore stacker conveyors. Trippers distribute ore to outside stockpiles adjacent to, and above, the concentrator grinding 'floor."

Jan 1, 1975

By Hermann Wotruba, Lars Weitkämper

"Dry coal dressing was popular during the 1950’s and 60’s in many parts of the world. The devices mainly used were air jigs and air tables.The increase in ash and moisture content of run-of-mine coals due to the wide advanced mechanisation of mining methods during and after this period led to that pneumatic devices being unable to treat run-of mine coals with the desired efficiency. Since the 1960’s almost all new coal preparation plants have been based on wet processes that are highly efficient in terms of coal recovery and their ability to handle damp and sticky run-of-mine coals. (Frankland, 1995)However, water is becoming increasingly costly and the disposal of fine products, containing most of the water, is an environmental concern. There would be significant cost savings and a lower total energy consumption if coal could be cleaned dry. Efficient dry coal treatment would be an interesting solution in desert, arid or cold areas.In Germany one dry coal dressing plant is in operation. This is the last operating dry coal dressing plant existing in Europe. The actual technical standard of dry coal dressing has been analysed during test-work and sampling in this plant (Saar Region in Germany). The process and the advantages and disadvantages are presented. The plants problems are low efficiency in the fine fraction –6 mm and the coarse fraction +30 mm and a low overall throughput as well as the lack of an automatic process control system. The separation results in the medium size fractions between +6 and -30 mm are excellent"

Jan 1, 2003

By John Organiscak

A majority of continuous mining machines employ a water spray system and a machine mounted flooded-bed scrubber to suppress and capture dust during coal mining. These machine mounted dust control systems must be designed to function within the localized face ventilation system at the mining section to control both dust and methane. Spray systems can impede or improve the scrubber effectiveness in controlling dust or methane at the mining face. Laboratory experiments were conducted to examine the effect of spray type, spray pressure, machine body blocking sprays, and scrubber airflow on dust and gas levels while using a 12.2 m (40 ft) exhaust ventilation curtain setback from the face. These experiments were conducted with the mining machine positioned at the end of a simulated 6.1 m (20 ft) sump and slab cut. Results indicate that the hollow cone nozzles with blocking sprays best complemented the flooded-bed scrubber performance in an exhaust ventilation system. This external spray system notably reduced dust and gas levels on the off-curtain side of the mining machine for both the sump and slab cut as compared to the flat spray nozzles. Higher scrubber airflows reduced dust and gas levels on the curtain side and in the return of the continuous mining machine. The remote operator position, located on the off curtain side and parallel to the inlet end of the exhaust curtain, sustained the most stable and lowest dust levels around the mining machine.

Jan 1, 2010

By E. Chin

Under the seventh 5-year plan (1986-90), the Chinese Government continued to implement reform and to open the country further to the outside world in order to accelerate the growth of its national economy. As a result of expanded foreign economic exchanges and domestic achievements in education, science and technology, and cultural and public health undertakings, the national economy was strengthened. In 1988, there was impressive growth in the Chinese economy. The gross national product (GNP) grew by 11.2070 reaching $373.4 billion; 2 the national income grew by 11.4070 to $310.9 billion. The major problem in the Chinese economy was the imbalance between high demand and insufficient supply. Chronic shortages resulted in price increases and high inflation, which averaged 19% for China as a whole and about 30% in urban areas. Macroeconomic stability took precedence over market-oriented reform initiative. Because of rapidly growing inflation, the Government re-imposed price controls and rationing in major cities in the fall of 1988. China continued to be a major world producer of minerals, metals, and fuels. Output of the principal commodities continued to rise. The largest in-crease in production was salt which rose 24% in output in 1988; followed by sulfuric acid, 14%; cement, 12%; soda ash, 9%; caustic soda, 7%; and steel, 6%. For fossil fuels, the increase in output of natural gas was 14% in 1988; followed by coal, 3%; and crude oil, 2%. The output of electricity by thermal-fired powerplants rose by 9% while that for hydroelectric power-plants rose 7%. Although China's overall energy output has increased annually since 1980, the growth in demand continued to outstrip the supply.

Jan 1, 1990

By Jamie Archibald

The Department of Mining Engineering at Queen?s University conducted a study of backfill practices in underground mines across Canada to assess the current state of backfill usage and to overview potential hazards associated with backfill practice, from preparation to transportation to placement. The primary aim of this study was to cover each component of a typical mine backfill system, and to identify potential incidents leading to the disruption of backfilling operations and any associated corrective actions. This paper, Part II of the study, deals with underground operations consisting of backfill transportation and backfill placement. Part I of the study, which deals with surface operations consisting of backfill material supply and backfill plant preparation, is also presented in these proceedings. A review of safety measures associated with current backfill operations and recommendations for procedures of best practice that should be implemented to reduce fill-related hazards in all mine backfill workplace environments are presented. In general it has been found that system failures normally lead only to minor losses to the operations.

May 1, 2009

By C. L. Liao

The chief experiences for constructing deep tubular columns foundation under deep water are as follows: 1. P.C. tubular columns were sunk inside the caisson. 2. P.O. tubular columns of 3.6 M. diameter were sunk thru thick soil layer to a depth of 47 M. by vibrators. 3. The double wall steel cofferdam was sunk thru soil layer to a depth 31.3 M.. 4. Bore the bedrock with rotary drill succesfully. According to the successful experiences mentioned above, the deep tubular columns foundation may be constructed beyond 100 meters.

Jan 1, 2010

By J. Bongardt

Ecologically acceptable techniques are described for the handling of waste materials from the fabrication industry. New production methods and the recycling of sludges from grinding and other waste materials are suggested.

Jan 1, 1997

This is what I term ... the graveyard end of any Conference. It's almost over. Those of you remaining are either all talked out or past the information overload stage. And some of the sensible? ones have left for more exciting field trips, or gone back to their work-site where they earn their daily crust, or headed off South to another Conference of interest to the Energy sector that is being held currently in Christchurch. But that's OK. I have a thick skin! And neither am I particularly Politically Correct! I am not a miner: I am not involved in the mining industry in a hands on way at all. I am not even an academic. I am not even too sure why I am here ... apart from the fact that I agreed to come! At various times in my life I have been a D istrict Councillor, Chairman of a Regional Council and even an MP. I am a supporter of responsible mining.  All of what I have to say is my own point of view rather than that of either the Coal Producers' Federation or the mining industry. That is not to say that we are often in agreement, but I thought I would clear that point right at the outset. And some of what I will talk about will not strictly be to the topic - it's hardly mind-bending riveting stuff. Well, is it? But obviously because you are still here you have some interest in the topic.

Jan 1, 1997

By H. S. Marshall

Optimum Colliery is an opencast strip mine producing 18Mt of bituminous coal per annum for the export and inland markets as well as for domestic power generation at the Hendrina PowerStation. Coal is exposed by four 60m3 and four 11m3 walkingdraglines and transported from the open cuts to the processing plants by twelve 130 ton coal haulers. Overburden and interburden areas are drilled by nine 250mm-diameter rotary drill rigs. Until 1997 all surveying tasks were conducted by electronictotal stations requiring accurate control points from which line-of-sight XYZ readings could be taken. In 1997 a GPS system was introduced which consisted of a fixed base station and two rovers. The rovers were able to perform most of the survey tasks assigned to total stations. In addition, two overburden drills were equipped with blasthole drill navigation systems, which includes the drill monitoring and material (strata) recognitions system. The rest of the drilling fleet will also be equipped with GPS systems. Blasthole positions are designed in the office based on survey and geological/geophysical information and transmitted via radio link to an industrial PC on the drills. Together with GPS positional data, both the planned and actual drill positions are displayed on an LCD screen. This eliminates the need for surveyed hole positions to be staked before drilling, and for actual hole positions to be surveyed after drilling. As holes are drilled, performance and rock property data transmitted back to the office. Future applications will include GPS monitoring of dragline positions and pad elevations. GPS receivers on the draglines will utilize the existing base station to calculate and transmit XYZ co-ordinates. Another application will be locating of boreholes in the field prior to the pumping of specified explosive charges into the blastholes. Charging instructions for each blasthole will be loaded into the computer on the explosives truck which will be equipped with a GPS system for hole identification.

Jan 1, 1998

By Wenbing Guo

The stability of strip pillar is the key to successful strip pillar mining. In analyzing the stability of the strip pillar, the width of yield zone must be determined. The determination of the width of yield zone has been an important subject for researchers. In this paper, the numerical method was used to study the relationship between the width of yield zone in strip pillar and coal recovery ratio. The results showed that as the recovery ratio increases, the width of yield zone increases exponentially. Accordingly, the formula for determining the width of yield zone was updated and the effect of changing coal recovery ratio on strip pillar deformation is presented.

Jan 1, 2006