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By W. A. Crosby

The ability of open pit mines to steepen overall final wall angles allows significant cost reductions as a result of reduced waste movement requirements. Final wall angles are principally controlled by three factors: geological conditions; hydrological conditions; and wall control blasting practices. The first of these factors is not controllable by the mine operator, the second can be influenced to some degree, but the last one certainly can be controlled, hence the current interest in final wall blasting practice at many mining companies. This paper discusses common blasting techniques employed to steepen final pit walls and outlines the attractiveness of moving from small hole high cost systems to the use of full size production drills as a means of reducing wall control blast costs. Attempts to make this change have been limited at many mines by the physical size of the drills and their inability to reverse drill. In the past, pres pi it, pre-shear or trim holes have had to be drilled vertically, at considerable distance from the upper bench toe, with the result that inter-berm face stability is reduced and final wall angles have to be made somewhat more shallow than desirable. The paper concludes with a description of how these problems can be overcome by utilizing the new Bucyrus 39R which has the capability of drilling at a ?15 degree angle underneath the machine. It is concluded that the resulting wall control blast designs will offer large mines improved final wall angles with resulting significant overall cost reductions.

Jan 1, 1998

By William L. Meyer

With high expectations and promises, computers were introduced to the mining industry in the late 1950s and 1960s. Applications spread in the 1970s when capabilities began to catch up to early promises, and people within the industry began to see the benefits of using computers in business and engineering. The 1980s have seen a wide acceptance of computers, both large and small, and the use of computers is accelerating throughout the industry. Computers have changed dramatically over the last 25 years. The power of some microcomputers matches the capabilities of main frame computers from less than 10 years ago. The variety of software on these micros exceeds what is available on many larger computers today. Changes over the next 10 years are likely to be greater than those of the last 10 years. Making use of available computer technology while trying to cope with the rapid changes in this industry will take much effort within mining. To take advantage of existing computers, consider and evaluate: project needs and applications; professional, administrative, and support personnel; computer software and technology; and computer and related hardware. Note that this list is in the order of decreasing importance. These categories are also presented in the order for which organization and solutions should be provided to get the most out of computers. To start with a computer and go up the list has cost many mining companies needless expenditures, wear and tear on personnel, and frustration. It is assumed for this article that the need for computer tools is self evident. You can do without a computer by using the appropriate techniques (manual methods) with any required shortcuts plus a lot of personnel time. Indeed, several companies are doing that as a "solution" to what to do with their excess engineering personnel in these lean times. However, the future may be better served if some of these people could be prepared to handle the applications and technology presently available. People and Problems To present the factors related to turning the computer into a productivity aide, it may be enlightening to examine some common people problems that reduce productivity. The most valuable resource any mining company has is its mining professionals. And, particularly with computers, people either make the successes or create the barriers, not the machines. The following list of people problems (syndromes and complexes) has been amply observed during some 23 years of the author's experience with computers and their applications in mining. Home Grown Syndrome - "Nobody else can really understand my problem or provide `exactly' what I need to solve it." While there may be some truth to this syndrome, it would be an unusual project that cannot be handled with existing solutions for at least 75-80% of the needs. Having a base to build on will also speed the development of any remaining needs. It does not seem justified to start all over for a new application, even if "our problem is unique." Not Invented Here Syndrome - This "justification" for the continued existence and budgets of some groups has various forms: "It wasn't done here so it obviously can't do the project the way I think it should be done"; and, "If it wasn't invented here, it obviously

Jan 11, 1983

By G. C. Hambleton

There is sufficient indication of the existence of a basic misconception in the Coal Mining industry (on a world-wide basis) as to what computer control really does, what it costs, how it works and how and what it achieves as to make this presentation a welcome opportunity to present the case in what we hope is a simple, meaningful way. A plant cannot be said to be "automated" unless the control system has the capability to react automatically in accordance with predetermined programs under a great multiplicity of operational situations.

Jan 1, 1981

By Dirk van Zyl

It can systematically assess if the control and management systems designed for protection of sensitive ecosystems are adequate. The results of the assessment can help to identify key elements in the project that pose higher risks due to uncertainties in design. These assessments can then be used to make recommendations to further manage and reduce risks as the project is developed. QUALITATIVE RISK ASSESSMENT The general principles of a risk assessment are well summarized by Kaplan and Garrick (1981): "In analyzing risk we are attempting to envision how the future will turn out if we undertake a certain course of action (or inaction)." Fundamentally, therefore a risk analysis consists of an answer to the following three questions: What can happen? (i.e. what can go wrong?) How likely is it that that will happen? If it does happen what are the consequences?" Risk assessments can be performed using various levels of sophistication depending on the amount and accuracy of data available. A qualitative risk assessment uses descriptors throughout to express the level of risk. The definitions of the descriptors are presented in terms of the magnitude or concentration of contaminants. The results of a qualitative risk assessment can be used to: a)Document the evaluation and decisionmaking process. Although differences of opinion may exist about the definitions of the descriptors, the process is well-documented; b)Express the relative risk associated with specific activities or design elements; and, c)Select those failure modes or release mechanisms that may result in significant risks. These mechanisms can then be further developed in quantitative risk assessments. A qualitative risk assessment can be performed in a systematic approach using four steps (Van Zyl, 1987): A qualitative environmental risk assessment can be used to describe the risks associated with the development of a new mine and to make an evaluation of the adequacy of its design for environmental protection. The relative magnitude of risk associated with selected failure modes and exposure/consequence scenario assessments is the final result of a qualitative risk assessment. These failure modes are based on site specific areas and components, and mining and construction phases. The four steps of a risk assessment (hazard assessment, exposure assessment, consequence assessment, and risk characterization) are used in the development of a qualitative risk assessment. Relative magnitudes (using a five point scale of negligible to high) for each step, can be quantified in a qualitative risk assessment. Development of the descriptors for the relative magnitudes in each step is a very important part of a qualitative risk assessment. The success of a qualitative risk assessment depends on the adequacy of the information base and the subjective judgements made in each step. The quality of the risk assessment is, therefore, dependent on the experience of the assessors. A mining project in a sensitive coastal environment is presented as an example to demonstrate the application of a qualitative risk assessment. INTRODUCTION Environmental impacts from mining operations have been a significant factor in the last century. This was especially the case prior to the development of a better understanding of environmental processes and the potential impacts of acid rock drainage (ARD), and associated heavy metals, or the uncontrolled disposal of tailings and waste rock (Smith, 1987). Much care has been exercised over the last two decades in designing and operating mines to limit the environmental impacts as far as possible. All new mines are specifically designed with mitigative methods to manage such potential environmental impacts. Attention is directed to ARD impacts, safe disposal of mine waste rock and tailings, transportation and storage of chemicals and fuels, and final reclamation. A qualitative risk assessment can be used to address all project systems and activities that may potentially pose a risk to the environment.

Jan 1, 1992

By S. V. Krishnan

In the upgrading of finely-disseminated iron ores, selective desliming is the critical step which must be controlled in order to achieve efficient flotation. A prerequisite for selective desliming is a properly-dispersed pulp; sodium silicate is commonly used as a dispersant. The mechanism by which sodium silicate acts as a dispersant in the presence of calcium ions was examined by streaming potential measurements, settling tests, abstraction density determinations, selective flocculation tests and scanning electron microscope observations. The study established that calcium silicate precipitates on the mineral surfaces dispersed the pulp. Although sodium silicate was a nonselective dispersant, the addition of corn starch aided the flocculation of goethite over quartz at low silicate additions, but became ineffective at higher silicate levels. A model is presented to explain the dispersant mechanism of sodium silicate in the presence of calcium ion for selective flocculation of iron ores.

Jan 1, 1982

By Wilbur J. Morin

Construction of Flaming Gorge Dam in northeastern Utah necessitated the construction of a new state highway, Utah-260, to provide access to the dam and the town of Dutch John. A 550-foot arch structure was designed to span Cart Creek, about one mile southwest of the dam. The rock exposed at the site is highly fractured quartzitic sandstone with interbedded shale of the Precambrian Uinta Mountain Group. Eight exploratory holes were drilled, four in each abutment area, to determine rock types, the extent of fracturing at depth and rock strength. Drill cores in the west abutment revealed blocks of quartzitic sandstone loosened by the weathering and partial removal of underlying shale beds. The rock in the east abutment area was found to be highly fractured to depths of 70 feet and as far east as 50 feet from the footing locations. Selected core sections were tested for unconfined compressive strength but the values were not considered-representative of the in-situ fractured rock. To prevent movement along or, perpendicular to open fractures, four drilled-in columns were provided at the base of each footing. These extended 50, feet beyond the base of the footing, along the bearing and inclination of the thrust reaction.

Jan 1, 1963

By Rudolf E. Pfister

One of the Swiss transalpine highways includes two remarkable tunnels: the 16.3 km long Gotthard Road Tunnel and the 9.3 km long twin tube Seelisberg Tunnel, both presently under construction. Large diameter shafts up to 900 m long are required for ventilation. Excavation techniques for rock formations ranging from loose sedimentary rock to granite and very hard siliceous limestone were carefully evaluated. The methods finally applied include excavation of shafts in hard rock, conventional drilling and blasting, excavation by ripper-tooth excavator ("Big John") in marlstone, shield protected heading in loose material and soft rock, and tunnel and shaft lining, both by poured concrete and by prefabricated elements. A critical review of the success of these methods can now be made after a five year construction period.

Jan 1, 1976

By C. R. Stephan

Explosion-resistant seals in underground coal mines isolate the environment within the sealed area from the active workings of the mine. The current United States Title 30 Code of Federal Regulations (CFR) requires these seals to be constructed of solid concrete blocks. The CFR also allows for alternative methods or materials to be used to create a seal if they can withstand a static horizontal pressure of 138 kpa (20 psi), provided the method of installation and the material used is approved in the ventilation plan. The purpose of this report is to identify those explosion-resistant seals that have been tested and meet or exceed all the requirements of the CFR.

Jan 1, 1997

By David E. Thompson, Wesley E. Stimpson

The Massachusetts Bay Transportation Authority (MBTA) Red Line Extension Northwest is currently in the early stages of construction. The 3.1 mile extension of the Red Line from the existing Harvard Square Station in Cambridge, Massachusetts to Alewife Brook Parkway in Cambridge, Massachusetts will include a large, near surface hard rock, rapid transit station chamber at Porter Square in Cambridge (Figure 1). [ ]

Jan 1, 1979

By U. F. Beichmann

INTRODUCTION The City of Oslo together with the neighbor municipalities, Baerum and Asker, are presently building a jointly owned sewage treatment plant located on the west side of the inner Oslofjord. The project is scheduled for completion late 1981. Because the location of the treatment plant is at a distance of about 20 miles (30 km) from the city center, a discharge of more than 13 yds 3/sec (10 m3/sec.) of sewage and storm water will have to be transported over considerable distances. The topography of the area and the geological conditions early indicated that the only realistic transport method had to be through tunnels. As planning proceeded, full face tunnel boring emerged more and more as a favorable alternative to conventional drill and blast medhods. Today the scheme comprises nearly 25 miles (40 km) of tunnels being excavated by full face tunnel borers. In addition a number of access tunnels and cross cuts are to be excavated by conventional methods.

Jan 1, 1979

By Toshio Fujiwara, Sumikichi Ito, Masao Kitamura

The Tennohji-Benten Giant Trunk Sewer Project has been under construction since 1974 in the eastern part of Osaka, the second largest city in Japan. The entire project is divided into 7 blocks, some of which have already been completed. This 8.8-km sewer tunnel, being driven through a densely populated area, was planned to be constructed by the shield tunneling method. This paper described shield tunneling performances and ground behaviors during the construction of Blocks 2 and 3. An earth pressure shield (dia., 6,750 mm) was employed in Block 3 tunneling. The ground was generally soft and the cover over the tunnel varied from 13 m to only 4.5 m, so that a considerable amount of chemicals was injected to stabilize the ground. A hand-digging type shield (dia., 7,250 mm) was used in Block 2 tunneling under compressed air. For 85 m of the total length of 1.6 km, the soil at the face was extremely soft, and therefore, the ground freezing method was additionally employed.

Jan 1, 1981

By D. S. McAllister, P. M. Rice, M. E. Fowler

The Westside Light Rail Project, a major 19.3-km (12-mile) extension of Portland, Oregon's light rail system, includes 4.6 km (2.8 miles) of twin 5.8-m (19-ft) diameter running tunnels, a binocular type station which, at 80 m (260 ft) below the ground surface, will be the deepest mass transit station in North America, two 9.4-m (31-ft) diameter station access shafts, and a 5.2-m (17¬ft) diameter ventilation shaft. The tunnels are being excavated by TBM and conventional rock, soft ground, and mixed-face methods. Geologic conditions, alignment, underground opening design, excavation method selection, and payment provisions for excavation and initial ground support are discussed.

Jan 1, 1995

By S. Rezaei

Moving ground in the mining industry is almost inevitable; however comprehensive awareness of these movements is necessary to mitigate risk. Monitoring of displacements caused by mining is a key tool for geomechanical risk management. Good monitoring may prevent unexpected failures and protect personnel and equipment. Many displacement monitoring techniques are available, however not all are reliable, accurate, and cost effective. Close range photogrammetry (CRP) is a monitoring method with high accuracy, reliability, and cost effectiveness; and has the ability to measure places that are inaccessible. In CRP, some series of photos are taken in different positions with different angles at different time intervals depending on the displacement rates. These photos are processed using PhotoModeler software and 3D models are made. By comparing 3D models, displacements can be measured. This method has been demonstrated at the Freeport-McMoRan Safford Mine in Arizona. A fault related instability in part of the pit is reactive to mining, and provided an opportunity to compare results between traditional monitoring methods and CRP. In this project, multiple series of photos were taken at different times using a Canon 5D Mark III digital camera, then PhotoModeler software used to make 3D models for each specific measurement event. Movement rates were determined by comparing different 3D models. These results are then compared to results of other monitoring methods to validate the CRP displacement method.

Feb 27, 2013

By Donald P. Schlick

Gentlemen, today I would like to talk to you about metal and nonmetal mine health and safety--past, present and future. Briefly, I will comment on the past because it is important to an understanding of our present activity and our plans for the future. Federal inspection of noncoal mines was not authorized until 1966, when congress passed the federal metal and nonmetal mine health and safety act; public law 89-577, with the passage of this act, the federal inspector, for the first time, had the delegated authority and responsibility to enforce health and safety regulations designed to prevent personal injuries and occupational diseases, the new law also provided for the education and training of our miners; assistance to the operator through the transmission of technical and scientific information and assistance and equally important, the law made provision for state participation in the congressional mandate to prevent injuries and save lives in the mineral industry, Before I tell you about our program and our future plans, I want you to know that I am here to listen as well as to talk! In my view, the only kind of communication that is meaningful is two-way communication. Our nationwide progress in metal and nonmetal mine health and safety during 1972 cannot be measured in reduced fatalities or injuries. The unforeseen tragedy that took pace in Kellogg, Idaho, in may of last year mode that almost a certainty.

Jan 1, 1973

By Indranil Roy

Gua supergene enriched iron ore deposit from Jharkhand, India has been geostatistically modeled. Population modeling shows a negatively skewed 3-parameter log-normal fit for Fe and positively skewed 3-parameter log-normal fit for Al2O3 and SO2. Semi-variographic studies for Fe indicate spherical function fit using point kriging cross-validation technique with Co=4.06(%)2, C5.11 (%)2, Co+C=9.1 7(%)2 and 'a'=348m. Kriging with 50mx50mx 10m block size at 740mRL led to a global mean kriged estimate of 61.98% and kriging variance of 4.04(%)2 for Fe with central 90% geostatistical confidence limits at 61.39% and 62.24% for that level. This led to an ore inventory at 740mRL as 7.29 million tonnes of ore.

Jan 1, 2002

By P. Hambach

Murer Company, Andermatt, Switzerland, can claim to have done pioneer work in the construction of inclined shafts. This happened in 1968/69, when we decided to bore with a Wirth tunnel borer an inclined shaft, 1100 m in length, 3.0 m in diameter, and with a grade of 65%, in the 2400 kilo pascall per sq. cm granite of the Montblanc Massive. The whole excavation was accomplished in ten months which, at least for European conditions, can be claimed as a record. It was, at least to our knowledge, the first inclined shaft to be bored full-face (Fig. 1). Encouraged by the experiences and performances attained at Châtelard, we approached other projects of the same kind. We were awarded, together with Hochtief Ltd., Essen, a contract from Schluchseewerke, Freiburg, Germany, in December 1969, for the construction of a penstock for the Hornbergstufe at Wehr, Germany, with a diameter of 6.3 m. This inclined shaft with a grade of 55% is located in Schwarzwalder granite with a compressive strength of up to 2000 kilo pascall per sq. cm, about 31,000 psi. As no exact geological data were available about the rock to be worked, and a fault zone from 80 to 150 m long had to be faced, as well as a few individual fissures of varying thickness, it was decided to use the multi-stage method. The 3-m diam tunnelling machine which had driven the oblique shaft at Châtelard had now finished work, and an immediate beginning was made with driving the pilot staft. This was very welcome to the contractor, since exact information about the type of rock present and the inflows of water was required immediately and before the final borehole diameter was fixed, for the purpose of dimensioning the supports to be subsequently installed.

Jan 1, 1974

By Alastair R. Biggart

ABOUT BENTONITE TUNNELLING Much has been written and many learned papers given on this subject whose generic term is Slurry Tunnelling. This paper is about the particular form of slurry tunnelling known as the Bentonite Tunnelling System. This method. of tunnelling was invented by J.V. Bartlett of consulting engineers, Mott Hay and Anderson in 1964. The general principles are incorporated in British Patent No. 1083322. It was not until the early 1970's that serious experimental work was started to prove the technical feasibility of the process. In the U.K. in 1971 Edmund Nuttall Limited started on an experimental length of 3.8m diameter tunnel at New Cross in London. In Germany at about the same time Wayss and Freytag were starting on a 3.7m diameter collector sewer tunnel in Hamburg. In Japan early slurry tunnelling work was carried out in the 1960's. In the early 1970's a large number of slurry tunnels of various diameters were carried out in that country. This paper is being presented at a time when this system of tunnelling has become an accepted method throughout the developed world. As a result of the work carried out so far there is now a large amount of data existing regarding the effects on the ground in the immediate area of the tunnel, settlement at the surface and the ability of the system to cope with ground varying from clays to coarse gravels and containing large erratics such as granite boulders. The decade of the 1970's has therefore seen a very rapid pace

Jan 1, 1979

By P. R. Hervey, J. W. Foise

Quartz is the second most widely used electronic material, with approximately 3,000 t (3,300 st) of single crystals used each year. Most of the quartz used in electronics is synthetic and is manufactured using a technique called hydrothermal growth. This paper reviews the basics of hydrothermal growth, the feedstocks used for these crystals and the challenges to improving the growth process. This paper also reviews the processing of these crystals, the markets and applications where they are used, and the global outlook for these markets.

Jan 1, 2002

By Sara Swiokla Korsikas, Toren Olson, Amado Guzman, Yuri O. Zepeda

Ore agglomeration has been used as part of the heap leaching process for the last 40 years. However, industrial experience shows that the lack of a universal agglomeration standard has limited the benefits of this otherwise valuable unit process. The more complex the ore in terms of the nature and relative abundance of fines (particle size smaller than 74 μm), the more important that the agglomeration product satisfies some minimal requirements. This paper presents an agglomeration scale that identifies the quality standards for agglomerates and documents the resulting mechanical, physical and hydraulic (hydrodynamic) behavior associated with each level on the agglomeration scale. The hydrodynamic properties of an agglomeration product are critical for the proper design of a leaching operation and, as shown in this paper, can be used to select the optimal pretreatment method for a given ore sample. Agglomeration as a unit process not only allows better conditioning of the hydrodynamic behavior of the ore but also creates an opportunity for optimized delivery of reagents to kickstart the leaching process, which may ultimately improve the economic performance of leaching. Industrial case data are used to demonstrate the shortfalls associated with low-quality agglomeration and the benefits of improved agglomeration, which range from enhanced porous structure (better percolation and drainage characteristics) to better metallurgical response (faster kinetics and higher metal recovery). Proper agglomeration has been used to render otherwise untreatable ores into valuable leaching resources.

Sep 1, 2024

By Rolf Lange

Introduction The Harzwasserwerke, a public body of the Federal State of Lower Saxony, supplies drinking water to an area bordered by Braunschweig, Bremen, the Northern and the Western edges of the Harz-Mountains. From the very beginning in 1928, the Harzwasserwerke have been systematically constructing reservoirs in the western Harz which have the function of collecting and storing the frequently occuring flood waters as well as providing drinking water. The Grane-Reservoir with a capacity of 45 Million cu.m., the last of the big reservoirs, was built in 1968-1970. A system of connecting tunnels effectively enlarges the natural catchment area of this reservoir and the surplus waters of the Oker and Radau valleys - where floods occur particularly during the spring - are being conducted to the reservoir. By building the 4.800 m long "Radau-Tunnel", the waters of the Radau valley will now also be used more efficiently and its surplus waters will pass to the Grane Reservoir via this new tunnel and the Oker-Grane-Tunnel which was finished in 1970. The Project The Radaustollen has been planned and put out to tender by the Harzwasserwerke as a conventional "Freispiegelstollen". The horseshoe profile has a cross-section of 8 m2. Lining was required only in disturbed rock areas; lining of the whole tunnel was not necessary. The gradient of the tunnel is 4 % 0 rising = 25 m over the total length of 4.800 m.

Jan 1, 1979