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By L. Bergkvist

"History can provide many answers with regard to what today’s mining industry looks like and how we got to where we are today. It has always been self-evident that safety has to be given the highest priority and, throughout history, many mine workers have been injured, become ill and have even sacrificed their lives due to the way in which attempts have been made to extract the ore, often due to ignorance of the dangers being faced. In more recent stages of history we have seen certain dangers being compensated by means of higher wages and bonus systems in order to have the work carried out: one example of this is when the rock heating method was employed and the men who first went underground to put out the fires that were burning, were paid extra. The working conditions, to which these people were exposed, with smoke-filled closed spaces, shortened their life expectancy considerably and today we can ask ourselves whether it is really possible to value these efforts just by higher wages. In all mines worldwide the working environment has been improved and many mining companies have a zero vision where work-related injuries and accidents are concerned. Despite this, incidents of varying severity still occur and a continuous improvement process and ongoing training is necessary in order to constantly minimise risks and improve the working environment. Atlas Copco takes this into account in all its development and we not only review our own production units but also the needs of our customers, with regard to the machinery that is produced in order to cater for customers’ safety and production objectives. Underground mining probably started at the beginning of the 11th century when people with modest tools tried to extract ores that were present in the bedrock. Methodology has developed enormously over the years with a strong focus on increased efficiency and higher production. In different parts of the world the development is driven forwards at different rates depending on which controlling factors are regarded as necessary. Political decisions, profit goals and productivity have partly controlled the development, but the greatest factor where improvement is concerned still remains with increased understanding of the totality. During more than 1000 years since underground mining has been conducted, all individuals at all levels have constantly improved their expertise and the human element has been of great importance with regard to the development that has been made, even though technology often occupies a leading role when we describe the improvements made."

Jan 1, 2011

By Anibal Gajardo

Because of the Chilean Ministry of Mining's interest in the development of industrial minerals, the Chilean Geological and Mining Service (Servicio Nacional de Geología y Minería, SERNAGEOMIN) has carried out a research program during the last two years to identify projects that represent interesting investment opportunities for small- to medium-scale operations in Chile. Most important of these projects are: (1) Quebrada Lluta aluminum sulphate, for drinking- and industrial-water treatment, with a potential domestic and foreign mar- ket of almost 43,000 tonnes per year and investments of about US$1.8 million; (2) Quebrada Lluta-Quebrada Cardones pumice, for abrasives, filters, fillers, and light- weight aggregates, with a potential market of about 30,000 tonnes per year, and in- vestments of US$2.0 million; (3) El Maule dolomite, for soil conditioner and iron smelting, with a total potential domestic market of some 60,000 tonnes per year, and estimated investments of US$2.0 million; (4) Las Escaleras bentonite, for animal feed, pelletising, and oil absorbents, with a potential market of almost 6,000 tonnes per year, and investments of about US$2.4 million; (5) Laraquete-Carampangue andalucite, for alumina refractories, with a future total domestic and foreign demand of about 15,000 tonnes per year, and estimated investments of US$2-2.5 million; (6) Rio Lía garnet, for fillers and sand-blasting abrasives, whose domestic market represents 10,000 tonnes per year, with investments of US$2.3 million; and (7) Munilque pumice, for building bricks and panels, with a potential domestic market of 250,000 tonnes per year, and investments of US$1.4 million. The development of these projects will represent an important increase and a significant diversification in Chilean industrial-minerals production.

Jan 1, 1999

By Anthony Harding, Rodolfo D. Aradas, Juan M. Fernandez, Darío Tsingas

"The adoption of tunneled combined sewerage interceptors and outfalls leads to design linings which are often subject to internal pressures that are larger than the external pressures, resulting in significant tension loads. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining. However, improvements in concrete technology and the need to seek efficiency in terms of time and costs, have driven designers to consider single pass segmental linings. The Riachuelo Sanitation project in Buenos Aires is subject to these constraints both upstream and downstream of a sewage treatment plant. This paper describes how the challenges of up to 2 bar pressure differential have been addressed by careful analysis of soil structure interaction to ensure that the full benefit of external ground pressure is realized, resulting in a more optimal design for the constructor both in terms of cost and time. INTRODUCTION The construction of long sewerage interceptors and outfalls is becoming an increasingly common piece of infrastructure for modern urban cities facing a large water front and estuarine conditions, which are under a significant environmental burden imposed by decades of sustained growth. Such works intercept most of the distributed sewage discharges to then divert them to a central treatment point from which it will be finally diffused via an outfall into a water body capable to accept these discharges under acceptable environmental conditions. Depending on the magnitude of the sewage load to be handled, the configuration of the urban environment and the conditions of the receiving water body, both in terms of oceanography forces and seabed conditions, these schemes will vary in length, conveyance capacity and design and construction requirements. When conditions permit, the current trend is the execution of long outfalls using flexible solutions (such as the use of HDPE pipes) which usually require some form of concrete ballasted weights to resist off shore dynamic forces when directly laid over the sea bed. However, this concept faces limitations when the conveyance requirements indicate the need for large diameters (typically above 3000 m) and also when the outfall needs to avoid deep features off shore such as navigation channels. When this occurs, tunneling, particularly segmentally lined tunnel constructed by TBM emerges as the most feasible approach for large diameter, long deep outfalls. The operating conditions often result in internal pressures that are larger than the external pressures, resulting in significant tension loads in the lining. The need to meet stringent durability conditions for the normal design life of 100 years often drives client specifications to require a double pass solution with a cast in situ secondary concrete lining."

Jan 1, 2016

By Barbara H. Carroll

In order to rapidly evaluate an area for its mineral potential, a reconnaissance exploration program generally includes the following: 1. Outlining an area of interest 2. Identifying known mineral deposits 3. Bibliographic search of the literature 4. Evaluation of geochemical and geophysical surveys 5. Compilation and review of geologic maps The information now available from various government agencies regarding the mineral deposits, geology, and geochemistry may be integrated and used as a tool to rapidly evaluate an area before the field season. The databases most commonly used in the United States are the USBM MAS/HILS system and the USGS MRDS system for their information on mineral deposits; GEOREF and GEOARCHIVE for bibliographic information; and NURE data for the geochemistry and geophysics. In conjunction with the project geologist, this information may be used to plot known deposits and their geochemical signature as well as any other areas of like signature for further examination.

Jan 1, 1985

By Kenneth N. Han

The authors investigate the use of froth flotation to remove carbonaceous material from Carlin gold ore. They also study the effect of type and concentration of various oils as flotation collectors and of sodium silicate as the dispersion agent on the overall recovery of carbonaceous material. And they examine other variables affecting froth flotation efficiency, including particle size, pH of the solution and temperature. Han and Chen also investigate the effect of reduction and oxidation of carbonaceous material on froth flotation efficiency. This investigation showed that aromatic type oil was the most effective collector. And the authors also found that oxidized carbonaceous material was difficult to float unless the oxidized portion was subject to reduction before flotation.

Jan 1, 1990

By Mark Gershon

This paper describes a linear programming (LP) application that schedules mining operations in an optimal manner. The model is developed such that it can be applied to a broad spectrum of mining activities. While linear programming has been applied to mine scheduling in the past, the models have been either site-specific or they have only optimized one aspect of mine operations without regard to others. The Mine Scheduling Optimization (MSO) concept makes use of a mathematical model to: (1) Determine the optimal operation of a mine, from mine to plant to market. (2) Account for mine-plant-market interfaces. (3) Optimize operations over the life of the mine. (4) Accomplish long, intermediate, and short range planning.

Jan 1, 1982

By Da-Rong Chou

An optimum method for selecting exploratory drilling locations has been developed. The process has been modelled as a highly non-linear programming problem subject to constraints. Solution involves an iterative algorithm which converges rapidly and procedures have been developed to distinguish between local and global optima. The algorithm has been implemented as an interactive computer program which allows the user to influence directly the solution process and to evaluate the effect of any manual adjustments to the optimal solution.

Jan 1, 1984

By Jurgen Hahn

The paper reports on both, the design and decision making for the filters in a backfill plant in Europe as well as more then 10 years of operation and maintenance experience of the vacuum disc filters installed. It begins with the first step, the filter sizing based on a sample provided by the customer, followed by the commissioning of the filter units and reports on the development of the filter performance during the following 10 years of operation. Based on the physical properties of the sample and the process targets of the client for the backfill plant, the paper shows the logic steps taken in the laboratory to ensure the target moisture, determine the required filtration area and filter size as well as the selection of the ancillary units and the formulation of the performance guarantee. The paper discusses some issues with filter operation during the commissioning phase and the actions taken. Finally, the paper concludes by highlighting the gradual change over the more than 10 years of operation and how this change affected filter performance and operating costs.

Feb 1, 2024

By J. F. Dresser

Managing environmental compliance at a complex facility has the potential to bring a high degree of personal and professional satisfaction to both the corporation and the individuals responsible for day-to-day operations. The decade of the 1990's, however, has seen the emergence of a nationwide trend of aggressive federal and state civil and criminal enforcement for environmental violations. This trend, spearheaded by the U.S. Department of Justice (DOJ) and the U.S. Environmental Protection Agency's (EPA) Office of Enforcement, has the potential to place the corporation, its corporate officers, and compliance personnel at collective professional risk, as well as a growing tendency to place accountability on individuals. Management of environmental compliance has been anecdotally compared to a shooting gallery at a carnival, with the following exception: At the shooting gallery, successfully hitting nine out of ten targets usually brings a reward and recognition of shooting skill; hitting nine out of ten environmental compliance expectations not only brings agency consternation and negative publicity, but the "gallery" will likely shoot back with stiff fines and possible criminal allegations. Faced with the challenges of the new environmental compliance shooting gallery, corporations and professionals are often left asking themselves, "How do we (or more appropriately, can we) win at this game?" This paper examines recent federal enforcement statistics and offers several suggestions for coping with the responsibility of managing environmental compliance in the 1990's.

Jan 1, 1992

By Frederick J. Murrell

No other region of the world is enjoying the tremendous growth of power use that is currently being experienced in Asia. Fortunately for the coal industry — particularly in Asia — the power plants being planned or under construction are designed to use coal as fuel. This has produced a significant increase in the demand for steam coal that, in turn, has encouraged many in the industry to develop new coal mines. Indonesia is a country that has enjoyed substantial growth in coal production. This developing country has 195 million people who live on the nearly 13,000 islands. It has quickly emerged as the third-largest exporter of steam coal, following only Australia and South Africa. Almost all coal in Indonesia is mined by surface-mining methods.

Jan 1, 1996

By Harrison R. Cooper

The expanding use of digital control in the metallurgical industry is a significant recent development. From 1970 to 1975, approximately forty metallurgical plants throughout the world have adopted automation techniques based on digital controls (see Table 1). Several recent technical reports have described development of digital control systems in concentrator grinding control, 1,2 flotation,3 and smelter operations.4,5

Jan 1, 1975

By Penglu Gan, Jinjie Zou, Chenglang Pan, Xiaowu Tang, Yu Zhao

"The north segment of the Zizhi Tunnel that consists of twin tunnels was excavated at a shallow depth in soft ground using the Shallow Tunneling Method. Based on continuous field measurements, the development histories of surface settlement were analyzed first. The observed development process could be roughly divided into three stages and the influence of river was evidenced. Transverse and longitudinal surface settlements above the twin tunnels were then fitted with empirical models. The obtained trough width parameters in transverse and longitudinal direction (it and il) and the volume loss (VLs) were presented and discussed. Additionally, surface settlement was compared with the crown settlement. The relationship between surface and crown settlement behaved in two different ways inside and outside the river-affected region. The findings in this project give references for predicting surface settlements in similar tunneling condition. INTRODUCTION Nowadays tunnel construction has become a major way of utilizing underground space in many large cities. The ground deformation will be inevitably induced in the tunneling process. Engineers should always be careful about excessive deformation that may damage adjacent structures. For shallow tunnels, controlling ground deformation turns to be more risky. Since soil arching is not completely formed in the shallow tunneling, settlements can easily develop from tunnel crown to ground surface.A conventional tunneling method named Shallow Tunneling Method (STM) has been developed and widely applied to constructed shallow tunnels in China. The major difference between this method and the New Austrian Tunneling Method (NATM) is whether considering self-supporting capacity of surrounding ground or not. In order to reduce the disturbance of surrounding soils, several guidelines are highlighted in this method, including advanced pipe forepoles, strict grouting, short excavation length, strong support, quick closure and frequent measurements (Fang 2012). Nevertheless, the ground deformation is still hard to control and becomes a concerned problem, mainly because ground settlement has some regional features and largely depends on the detailed excavation methods (bench cut method, multiple heading method, etc.) and ground condition (sand, clay, decomposed rock, etc.)."

Jan 1, 2016

By M. Z. Rashad

The intersection of joint sets and excavation planes leads to removable blocks which can be expected to fall or slide. The amount and cost of supports required to stabilize these blocks of excavation are related to the number and dimensions of key blocks, the mechanical properties of joints and the active forces present. In this work, the application of the block theory in the study of the kinematics and stability of removable blocks is investigated considering any number of sliding faces for some Egyptian limestone quarries.

Jan 1, 1993

By Allen V. Reicks

This paper reviews the impact of the idler set on the performance of belt conveyors. Idler rolls as part of the load support system and their interaction with the conveyor system will be discussed. in particular, the rotating performance of the individual idler roll concentrating on the rotating resistance and life of the bearing and seal design are addressed in detail. A basis for the development of performance specifications for use in conveyor design that takes advantage of the idler manufacturers design and manufacturing expertise is discussed.

Jan 1, 2008

By Bilgehan Kekec, Sertac Dündar, Niyazi Bilim

"Knowledge of the abrasion resistance of aggregates is important when using them for asphalt and concrete mixes and highway construction materials. In this study, the usability of natural building stone waste as aggregates for different engineering applications was investigated. To this end, test samples were obtained from a number of natural stone quarries and stone cutting factories. The abrasion tests were carried out on the test samples and results were compared between samples. The abrasion strength values were determined with both the Micro-Deval (MDe) and the Los Angeles (LA) abrasion test methods. A correlation coefficient was also determined between the LA and MDe tests results using an appropriate statistical model.Introduction The rapid consumption of natural resources has led researchers to work on the efficient utilization of such resources. To this end one can convert waste into useful raw materials, or determine alternative uses of the industrial waste materials. This has become increasingly important as storing or dumping waste may result in environmental problems. In addition, the use of industrial waste in a different application of the construction industry prevents rapid consumption of limited natural resources and can mitigate environmental problems related to raw material production, Industrial waste such as blast furnace slag, fly ash, building demolition material, marble waste and dismantled asphalt have been used as highway and concrete materials (Ahmed 1993, Ramaswamy and Aziz 1992, Schroeder 1994, Ceylan and Manca 2013, Holtz and Eighmy 2000, Hebhoub et al 2011). It is very important to analyze whether these aggregates are of the required quality in terms of their application and their economic life. This analysis can be carried out using various tests such as the Micro-Deval and the Los Angeles abrasion tests, sieve analysis, durability chemical resistance, peeling and adhesion, and freezing-thawing tests (Erdem et al 1996). Specifications for aggregates also include terms that define the grain shape, cleanliness and surface textures."

Jan 1, 2017

By Wilbur C. (Original by) Helt

Throughout the history of mankind, the principal use of coal has been to produce heat through combustion. The heat is used in many ways: to warm air space for our comfort; to provide heat or energy to power industrial processes, such as cement and steel production; and to produce electricity. Because it is our nation's most abundant fossil energy fuel, coal in the late 20th century is on the threshold of becoming a significant source for synthetic liquids and gas energy fuels for this country. This is made possible by conversion processes which can change solid coal into various synthetic gases and liquids. These coal-derived fuels are nearly identical to the processed fuels and chemicals provided by natural gas and crude oils, which presently provide almost all the petrochemical feedstocks and energy fuels needed for the residential, light commercial, and transportation markets. A revolution is beginning to take place, not only in the United States, but in many other countries with a return to a coal-based energy economy. Also, new combustion and conversion technologies which are compatible with national health and environmental goals are rapidly emerging. These technologies will allow coal's use to be expanded not only in its traditional markets, but also to supply markets held by natural gas and crude oil. With the worldwide decline in natural gas and crude oil reserves, coal is being-looked upon to meet the energy demand. Because of these new coal conversion technologies, coal will no longer be only a combustion fuel, but a valuable raw material for production of a variety of clean fuels and chemicals.

Jan 1, 1981

By David F. Becker

Two-dimensional, finite-difference elastic modeling aids in planning an optimum seismic-acquisition scheme to define the extent of subsurface cavities resulting from in situ gasification. To understand the seismic effects of a cavity, two models are compared and contrasted. Model A consists of a low-velocity layer (LVL) in a half space; Model B contains a rectangular water-filled cavity in the LVL. Amplitude differences are the dominant effect on the surface records for each model. Cavity resonance and diffraction effects are more definitive in vertical seismic profiles (VSP's) and in a "snapshot" of the wave field. Interpretation and subtraction of corresponding records for both models shows the need for pre- and post-gasification seismic recording. Also VSP data are more informative than surface records.

Jan 1, 1983

The MINER Act of 2006 mandated that all underground coal mines must install and maintain refuge chambers. Refuge chambers serve as a temporary shelter in case of emergency. Several factors affect the performance of a refuge chamber: heat production inside the chamber and introduction of CO when chamber doors are opened are two major factors. This study examines the CO purging process and to determine total air quantity and time necessary to lower the CO con-centration to safe levels for different inlet/outlet configurations using three-dimensional simulation technique. The study uses Reynolds Averaged Navier Stokes and continuity equations along with the spe-cies transport model assuming uniform air mixing. The heat transfer of any kind is neglected and the purging process is assumed to take place isothermally. The standard k-e model is utilized for simulating turbulence in the flow field. This research provides useful guidelines in developing an efficient strategy for purging refuge chamber. Keywords: Airlock chamber, Purging, Carbon monoxide, Turbulence

Feb 27, 2013

By J. B. Fletcher

Miami Copper Company has used conveyor belts underground since 1947, At that time, the draw level for a portion of the orebody was only 25 feet above the haulage level To get the main haulage drifts as far away as practical from under the stoping area, 301, belt conveyors were used for lateral transfer, If the haulage drift was kept in good ground., a satisfactory draw of these stopes could be effected in that repairs to the conveyor drifts could be accomplished while drawing ore from the stopes. Some 7,400,000 tons of ore were mined with the 301d belt conveyor at a belt cost of approximately $0,004 per ton of ore. When the mining plan for a new section of the mine was laid. out in 1953, it was decided to use belts to collect the ore from the higher draw levels, and. move the ore laterally to centrally located concrete ore passes for transfer to the main haulage level (See Cut #1), The final plans used belt conveyors too collect from 3 stopes: on the 570 level, 2 stopes on the 720 level, and one stope on the 900 level. The six stopes to be mined in this manner would produce about 8 million tons of ore, and the sequence of mining was such that not more than four 400 feet conveyors would be in use at one time, Four conveyors using 36 inch, 4 ply belting were designed by the mine engineering office and fabricated at the mine shop, so that no piece was longer than 10 feet, and. the heaviest piece was the 25 horsepower motor, The head drive section, and the tail-pulley-takeup section were of bolted construction so they could be broken down for easing moving, Due to the size of the mine openings, the belt had to be transported into the mine in 400 feet rolls, requiring two splices for an installed belt. A torque arm speed reducer was used with a V -belt drive which made it possible to change the speed of the conveyor by changing the diameter of the V-belt pulley (See Cut #2).

Jan 1, 1958

Introduction The US mineral industry in 1983 participated in the recovery from the recent recession. Compared with 1982, the value of raw nonfuel mineral output rose 8% to $21.2 billion. The $218 billion worth of goods processed from this crude mineral output represented a 9% increase over 1982. Even in real terms, these figures reflect growth. Demand for nonfuel mineral materials, of course, depends on the overall state of the economy, which steadily improved each quarter in 1983. Of particular importance to the mineral industry were surges in key mineral-consuming sectors such as construction and automobile manufacturing. New housing starts rose one-third, to 1.7 million units, while automakers turned out about 35% more cars (6.8 million) and 25% more trucks (2.4 million) than in 1982. These are significant increases, even considering recent trends toward smaller, lighter vehicles, and multiple-unit housing. A comeback for the mineral industry, however, is bound to proceed unevenly, particularly at the beginning. Traditionally, the industry lags behind the rest of the economy during a recovery, and some mineral products respond to overall economic improvement more quickly than others. This pattern has been repeated many times and the industry is used to it. Mineral executives know it is best to be patient and cautious during the first stages of an economic upturn. Many experts say that it may take extraordinary toughness, patience, and caution this time around. Steel Improves Raw steel production - a major indicator of both material use and mineral production - rose 14% to 77 Mt (85 million st), stimulating a 7% rise in domestic iron ore production to 39 Mt (38 million It). Still, the iron ore industry operated at less than half capacity, with most major mines remaining closed for part of the year. Iron ore imports dropped 24% to 10 Mt (11 million st), so demand was partly met by withdrawals from stocks. Despite the increase in steel production for 1983, output remained far below levels of just a few years ago. For example, 1983 production was still 29% less than in 1981. Raw steelmaking capacity actually declined about 10% during the year to 122 Mt (135 million st). The industry continued to cite steel imports, especially those from developing nations, as a major cause of domestic capacity loss. As long as steel production remains weak, steelmaking metals suffer. Domestic producers of bulk ferroalloys of chromium, manganese, and silicon operated at about one-third capacity in 1983, with six of the 19 companies involved being closed all year. The US mined no manganese or chromium, and very little nickel, although the country's only nickel mine did resume production in November. Molybdenum production, at 13.6 t (15 st), was only about one-third as much as in 1982. The major molybdenum mines, Climax and Henderson in Colorado, remained closed all year. To meet demand, molybdenum stocks were halved to 19 t (21 st). Mine shipments of tungsten, another mineral tied to steel production, dropped 30% to 1.1 kt (1,200 st) of contained metal. One of the most positive responses to the general economic recovery came from the aluminum smelting industry. By the end of the year, it was operating at about 79% capacity, compared to 59% in January. Nevertheless, the 3.3 Mt (3.64 million st) of primary aluminum produced represented only a slight increase over 1982. Total bauxite imports were about 27% below 1982 levels. Production of magnesium metal rose 11% to 100 kt (110,000 st). But titanium was more typical of other

Jan 5, 1984