Search Documents

This paper first describes the essentials of the slurry shield method and its achievements, then problems encountered during driving tunnels and their countermeasures, and finally shows problems to be solved in the future. The author works at Tekken Construction Co., Ltd. as a director. All the data cited are based on material gained from the slurry shield tunneling works undertaken by the said company. The mark, viz*, indicates that Tekken Construction Co., Ltd. has obtained or is applying for a patent in the U.S., Europe and Japan. 1. CONSTRUCTION RECORDS BY SLURRY SHIELD METHOD AND ITS PROBLEMS (1) Shield machines in the future should have the following characteristics; a. to be able to drive less cohesive soil b. to make no change to the ground water table level c. to make it possible to let people work in normal air pressure d. to cause less settlement at the surface To meet the above conditions various kinds of mechanical shields have been are tried, viz. limited air pressure type, rotary cutter with slit regulator, screw-discharge type, blind shield, etc. As far as the author knows, however, they are not 100% successful. Tunnels need their own accuracy in accordance to the usage. Both ease of driving

Jan 1, 1976

By Maiman R

One method of forecasting prices of metals is based on analysis of historic relationships between prices, inventories and consumption. The first, but generally overlooked step in this analysis should be to remove from the inventory and consumption figures the effects of seasonal variations. The next step is to construct diagrams which show prices plotted against ratios of inventories to consumption. These diagrams indicate that, when inventories are high, prices show little response to changes in inventories. Below a critical level of inventories, however, the psychology of the market changes and small changes in inventories lead to large moves in prices. The critical level of inventories is termed the "pinch-point"; the diagram which shows prices in relation to ratios of inventories and consumption may be called a "pinch-point diagram".

Jan 1, 1990

By R Rodriguez, S Gumo

The Lihir Gold Mine, in Papua New Guinea, is a large open pit operation within an active geothermal system inside a collapsed volcanic crater. This unique setting has a big impact on the mine operation because of the occurrence of geothermal hazards. The system for managing geothermal hazards that has been developed by Lihir Gold Mine is a pioneering effort that can be applied to future mine discoveries in a similar environment. The controls are integral to the mining operations and allow mining to proceed whereas without them mining could not be considered. Truck and shovel productivities in conventional open pit operations are constrained by diggability, equipment availabilities and utilisation. At Lihir, additional constraints are in the form of 100 m exclusion zones around working shovels and 50 m exclusion zones around working drills. Given that the mine has seven large digging units and six drills, this amounts to a lot of area that excludes the presence of people on the ground. So how are the necessary work like grade control, survey, blasthole loading, and in-pit maintenance performed safely to achieve production targets? The answer is in the highly specialised procedures that have been developed that utilise geological, geothermal and geotechnical knowledge to predict problem areas and also deal with the organisation of movement in the pit for people and mining equipment. This paper will detail how scheduled material movement can be maintained despite the challenging conditions faced at Lihir Gold Mine.

Jan 1, 2007

By Baafi EY, Chatterjee PK

The quality of mine planning decisions ultimately depends on reliable estimates of the characteristics of the orebody. The quant- ifiable factors such as grades or thickness can be estimated from field data gathered from outcrops or exploratory drillholes. Since outcrop data is necessarily limited to the periphery of a deposit, extensive drilling generally is required. This paper outlines a method for selecting the number and location of additional exploratory boreholes using an iterative procedure based on a mathematical optimization concept called fixed point theory. The method is illustrated through its application to an exploratory drilling program for a coal mine where optimized locations gave a lower estimate of regional and block variances than a manual Choice.

Jan 1, 1986

By Thornton D, Esterle J, La Rosa D

Control of blast fragmentation has a significant impact on coal mine profitability. Two approaches for the characterisation of coal blastability, particularly in terms of fines, are presented. Both approaches were implemented for the predictio

Jan 1, 1998

By Bailey S, Avraamides J

Laboratory-scale experiments were conducted in a mechanically stirred aeration vessel to determine the rusting abilities of aerated water in the presence of various catalysts compared to the industrially used ammonium chloride. The catalysts used were tartaric acid and citric acid, firstly by themselves, and then in later experiments mixed with ammonium chloride. From these experiments it was found that leaching of iron from reduced ilmenite in the presence of either tartaric acid or its sodium salt was much slower than in the presence of ammonium chloride. Citric acid or its sodium salt also give a slower rate of leaching than the ammonium chloride system, but citric acid and its sodium salt mixed in equal proportions produced a rate of leaching approximately twice as fast as the standard ammonium chloride system. When tartaric acid was mixed with ammonium chloride the leaching rate was found to be equivalent to the leaching rate of the same amount of ammonium chloride alone, thus indicating that tartaric acid made no contribution to the leaching in this svstem_

Jan 1, 1996

A nine-month investigation was conducted into the effect on coke quality and blast furnace operation of the addition of bentonite and southern coal to the northern coal fed to the coke ovens at the Newcastle steelworks.Additions of 0·3 per cent bentonite or 25 per cent southern coal to the northern coal increased the coke strength from 15-20 A.S.T.M. stability to 25-30 A.S.T.M. stability. It is likely that improved mixing and blending facilities would, in both cases, give a coke of over 30 A.S.T.M. stability.For the same coke strength, the use of 0 3 per cent imported Wyoming bentonite was considerably cheaper than the use of 25 per cent southern coal, but the use of Australian bentonite promises the same coke strength for still lower costs. Other additives such as coke breeze, charcoal, iron ore fines, and certain other finely divided materials, gave relatively minor improvements in coke quality.There appeared to be sufficient improvement in blast furnace operation and production to justify full scale addition of bentonite to improve coke quality, although other variables, particularly iron ore physical quality, overshadowed on many occasions the effect of coke quality. Further coke trials with southern or bentonite will be carried out when ore quality has been improved by the introduction of ore sintering at Newcastle.INTRODUCTIONDuring the period of operation of the Newcastle coke ovens and blast furnaces from April 1960 (when No. 3 blast furnace was blown in after rebuilding) to December 1960, a bentonite coke trial was carried out based on earlier research findings (Gregory, 1959a, 1959b; Felton and Gregory, 1960; Gregory, 1960) that as little as 0 3 per cent to 05 per cent bentonite clay added to northern N.S.W. high volatile coking coals gave a significant increase in coke strength. The bentonite coke trial was followed by trials...

Jan 1, 1962

Quite often the reserve assessor becomes enamored with the numbers gen- erated and forgets the basis for his assessment. The quality of the assess- ment can only be as good as the quality of the input data. The use of seismic data from the Gippsland Basin in assess- ing Esso/BHP's oil and gas reserves is an excellent example of this principle. By significantly improving the quality of seismic data, a much more reliable estimate of a field's reserve potential can be made. In addition, it provides the basis for further delineation drill- ing which, as recent experience in Gippsland has shown, often leads to increased reserves.

Jan 1, 1979

By Renwick MT

Two innovative ground reinforcement products have been developed for use in the mining industry. One of these products is a high strength polyethylene (HOPE) bar for use as a rib bolt in underground coal mining and as a corrosion proof tendon in open pit mines. The other product is a cable bolt (Ultrastrand) which demonstrates enhanced load transfer and is available in continuous lengths. Ultrastrand's exceptional in- situ performance and versatility makes it ideal for mechanised installation in both underground and surface mining operations. Details of these products are presented and results from labortaory and field trials are discussed.

Jan 1, 1992

The effect of accurate detonator delay timing on blast results can now be studied with the development of the ICI Electronic Detonator. This detonator has an accuracy and precision orders of magnitude greater than the current range of pyrotechnic delay detonators. A series of field trials have been conducted to quantify the effect of delay accuracy and timing on blast performance. These trials have demon- strated that delay timing can have a marked influence on blast fragmen- tation, muckpile displacement, blast vibration and airblast.

Jan 1, 1989

By Takiuchi T, Kurita M, Owada S

This paper describes the possibility of the application of flotation to the separation of monazite from xenotime and of columbite from ferberite, which have been said to be difficult with generally used physical beneficiation methods. For Malaysian monazite and xenotime samples, a great difference is observed between the flotation recoveries at pH 7.5 using 1.0 x 10-4mol/1 dodecylammonium chloride (DAC). The grade and recovery of columbite in the binary flotation with both minerals result in 85 per cent and 67 per cent in the cleaning froth and 91 per cent and 51 per cent in the re-cleaning froth, without adding any scavenging stages. For monazite samples from various localities, the flotability is dominated by the electrostatic interaction between mineral surface and collector ion using DAC as collector, but the singular decrease of flotation is observed in the sample of which the crystallinity is low and the surface structure is rugged and complex. Otherwise, ferric ion in the flotation system probably dissolved from mineral is found to activate the flotation using sodium dodecylsulfate as collector. For columbite and ferberite, the separation is judged possible at pH 3.0 using 1.0 x 10'3mo1/l sodium oleate (NaOl) from the single flotation results of each mineral. In the binary flotation, however, columbite recovery in the froth is greatly diminished below that expected. This would be because NaOl is prevented from adsorbing on the columbite surface of which the charge is transformed more negative side by the specific adsorption of the tungstate ion dissolved from ferberite.

Jan 1, 1993

By Hocking G

For some underground structures, the use of the plane strain assumption in stress analyses may not be justified. The finite element method and photoelasticity have been used to obtain complete 3-D solutions, but, for various reasons, neither method has found universal use. The boundary integral equation method (B.I.E.M.) can be more efficient and economical than the finite element method for 3-D problems involving large volume to surface area ratios. A B.I.E.M. program developed for calculating stresses and deformations in infinite elastic media has been used to determine the 3-D distributions of stress around T- and Y- junctions of circular tunnels in stress fields in which the ratios of horizontal to vertical stress are 0, 0.33, 1.0 and 2.0. For the T- junction considered,stress concentrations at the intersection are approximately twice the plane strain values. Except where horizontal field stresses are high, the stresses in both tunnels approximate the plane strain values at about two tunnel diameters from the point of intersection of the tunnel centre lines. The stresses in the two branches reach those for the corresponding plane strain, two parallel tunnel case two diameters from the point of intersection of thq inner tunnel walls. Very high stress concentra- tions occur in the pillar of rock between the inner tunnel walls near the point of intersection.

Jan 1, 1976

By Jorgensen FRA, Moyle FJ, Turner TM

Laminar flow furnace techniques and thermal analysis were used to study the combustion of Kambalda nickel concentrate and Collie coal. The study was made to ascertain the suitability of the latter as a replacement for the fuel oil currently burnt in a flash furnace at the Kal- goorlie Nickel Smelter. The coal was found to ignite at temperatures between 500-600¦C which was the same as that required for the most reac- tive component of the concentrate, namely py- rite. The rates of reaction of both the coal and concentrate were dependent on oxygen con- centration. Sulfur dioxide hindered the combus- tion of concentrate and of coal, the effect on the concentrate being the more pronounced. The effects of moisture content and the tendency for spontaneous combustion of the coal were also noted.

Jan 1, 1982

By Sengstock G. W, Spathis A. T

Benchmarks of mine equipment involved in the excavation process of coal mines would suggest that such equipment is not always operating at an optimum level. Dragline operations and truck/shovel operations rely on efficient use of their plant in order to maintain high mine throughput. The first process which affects the material to be excavated is the drilling and blasting process. Drilling and blasting delivers a fragmented material with a given disposition ready for excavation by mine equipment. As mine operators demand more productivity from their major excavating equipment, many sites are considering the use of productivity monitors to measure their outputs. Some of these productivity improvements will be directly related to the drilling and blasting process, so that as the monitoring systems improve, the opportunities to evaluate all drilling and blasting variables will also improve. This paper reviews current and newer methods for monitoring equipment productivity in mines. These include simple time and motion studies obtained by either manual timing of processes or by automated data collection equipment being adopted by the industry. Case studies for truck/shovel operations are discussed and the productivity improvements are compared with typical industry standards. These improvements relate specifically to parts of the load, haul and dump cycle and the potential for significant improvements are identified. Particular opportunities for drilling and blasting improvements are also presented.

Jan 1, 1995

Oxygen is required for the leaching of gold ores in cyanide solutions. The source of this oxygen demand and the effect of dissolved oxygen concentration on the rate of the process are briefly reviewed.A method of measuring the oxygen consumption rate is described and some experimental results reported.Fundamental aeration theory and rating of aerators is summarised to show how this type of experimental work provides the basis for full-scale design of aeration equipment.

Jan 1, 1984

Drag pick roadheaders and continuous miners have been applied in the coal mining industry for several decades, having replaced drill-blast methods as the primary means of excavating coal and coal-measures strata. The generally harder rock types associated with metalliferous mining have precluded the use of such machines in the past, however, developments in machine technology and increasing labour costs and environmental constraints suggest that there are now likely to be applications suited to the method. Metalliferous mining engineers are generally unfamiliar with the machines themselves and with the fundamental criteria controlling rock cuttability. This paper gives an introduction to the machines and the controlling factors.

Jan 1, 1987

A major tool in the search for petroleum is reflection seismic mapping. The period which has seen most of the exploration in Victoria is also one which has seen major advances in this technology, from 1963 try present day. Seismic mapping can be divided into three interlinked areas - acquisition, processing, and interpretation. In acquisition the major changes have been from an explosive energy source in 1963 to gas exploders in 1968 and airguns in 1970. The number of recording channels has increased from 24 to 192, with digital recording introduced in 1966, and floating point recording in 1976.

Jan 1, 1982

By Pradhan GK

Blasting is one of the most important operations involved in surface coal mining. The removal of over-burden waste in surface coal mines of India had experienced many improvements in terms of blasting, explosives selection, blast design, equipment selection, deployment. etc. Two case studies of very large surface coal mines have particular importance in their blasting operations. Both these units have been equipped with large capacity excavating machines, hauling units and also have some difficult mining situations. Blasting is done in benches in close proximity to human dwellings and over coal seams developed by underground methods with problems of high wall stability etc, as well. The various steps taken to improve the blasting operations ensure smooth operation of the equipment to meet the targetted coal production.

Jan 1, 1991

An ongoing research program into surface subsidence over Room and Pillar coal mining is described. A subsidence monitoring network has been established for one Room and Pillar mine in the West Moreton Coal Field of South East Queensland, at which pillar extraction is being conducted. The maximum measured subsidence to 28 January 1986 was 638 mm, with movement continuing. Analysis of the monitoring data with view to application of the subsidence pre- diction theory developed by Kowalczyk (1972) is discussed. The Kowalczyk theory provides predictions of subsidence depression, slope of surface, horizontal displacement, surface curvature and horizontal strain, for both the Partial and Total Settlement cases. The development of subsidence with time is also investigated and a preliminary analysis conducted.

Jan 1, 1986

The Coal Corporation of New Zealand Ltd (CoalCorp) is the largest coal producer in New Zealand, with extensive properties in both the North and South Islands. CoalCorp's North Island operations are kilcmetres to the south of Auckland. opencasts, are located in the catchment wildlife, historical and scenic values. in this catchment is the single most mining operations. centred on Huntly, a town some 80 Five coal mines, four of which are of Lake Waahi, a lake with significant The discharges of mine lodgement water important environmental constraint on Throughout New Zealand the use of water is controlled by a statute called the Water and Soil Conservation Act 1967. All industrial water users are required to hold Water Rights, which are in effect licences to take, use, dam, divert or discharge water. Water Rights are obtained through a legally defined process and any potentially affected party has the per to object to their granting. A special tribunal hears the evidence for and against an application, and issues its decision, which is reviewable in a higher court on Appeal. Rights, if granted, are issued subject to conditions and, in the case of mining discharges, limits would be set on flaw rate, suspended solids concentrations, turbidity, pH and the concentrations of any potential toxicants. This paper presents a case study of an integrated, catchment wide water management plan for Lake Waahi, that was prepared by the author, and others while the author was in the employ of CoalCorp, and its predecessor, State Coal Mines. The author is grateful to CoalCorp for their permission to submit this paper.

Jan 1, 1988