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By S. S. Szoke

The concrete masonry industry, represented by the National Concrete Masonry Association has significantly expanded its markets since the industry's inception. The concrete masonry industry has developed and refined concrete masonry units by producing a variety of quality products on automated machines. In the sixties, architectural concrete masonry units gained popularity. In the seventies, the concrete paver market expanded. In the eighties, segmental retaining wall units became popular. The industry continues to research and develop new products and applications for concrete masonry to satisfy the needs of designers, specifiers, installers and owners. Both existing and innovative technologies in the concrete masonry industry are discussed.

Jan 1, 1993

By P. Grotjohann

In processing heavy mineral sands, the low feed concentration and respective high value of the desired minerals require high capacity production and sharp classification/separation techniques to reduce the specific production costs. The allflux® separator, a new process system introduced to the heavy mineral industry, meets these criteria in an economical way. Its two-stage process, a combination of rising current and fluidized bed technology, allows the treatment of extremely high massflows in a single unit. Using concepts that have proven successful in processing concrete sands for many years, testwork in coal, iron ore, and heavy minerals looks very promising.

Jan 1, 1998

By David L. Durler

In-situ uranium mining is a relatively new and innovative method utilized for the commercial extraction of uranium. As with any mining method, however, significant environmental concerns will be evident and must be addressed in a rational and far-sighted manner. Experience has shown that radiological and non-radiological environmental problems may not manifest themselves until after the in-situ methodology has become established and matured to some degree. It is important, therefore, to recognize potential environmental concerns and incorporate them into an environmental program that spans the premining, mining, and post-mining phases of an in-situ operation.

Jan 1, 1982

By Henning E. Soderberg

Yesterday, air pollution was somebody else's problem -- today, it is everybody's problem. The coal industry with thermal coal drying, is aware of their problem and the necessity of doing an acceptable job; however, there is much to be said as to how good a job is required and what performance limits should be set up. American Air Filter Company has been one of the pioneers in the solution of the thermal coal dryer dust problems, Because of high moisture content, products of combustion and occasional temperature surges, only wet collection has been considered as the practical approach. Our first installation goes back some 12 years with a total to date of 29 Individual wet collectors, each, fabricated of suitable corrosion-resistant material, at 14 operating plants. To eliminate a potential air pollution problem, a performance requirement of not more than approximately one-quarter (1/4) grains per cubic foot in the dust collector discharge was used. In nearly all installations, operating performance surpassed requirements, but discharge stacks were not entirely free of discoloration. However, plant nuisance and air pollution complaints were eliminated. This satisfactory performance was accomplished by medium priced wet dust collectors operating at a 4-6" W.G. pressure drop with cater drain requirements of about 1 gallon of drain water per 1000 cubic feet of air exhausted.

Jan 1, 1962

By W. V. Bluck

Higher coal quality is being recognized in potentially lowering the cost of power as measured at the bus bar. Assessment of potential coal supplies for most any given power plant is now going beyond buying at the lowest delivered fuel cost and is now taking into consideration other factors such as handling, storage, pulverization cost, boiler fouling, post combustion cleanup, and waste disposal costs. New measurements of quality are being considered now by those producing and those consuming the fuel by assessing numerous variables in the total fuel cycle to achieve the lowest possible power costs.

Jan 1, 1983

By Steven W. DeCou, Marcus R. Jensen, Stephen Navin

The Lake Mead Intake No. 2 is a project constructed for the Southern Nevada Water Authority which includes a 12-foot diameter lake tap and intake shaft constructed in over 225 feet of water; 1650 feet of 16x14-foot horseshoe-shaped tunnel leading to a forebay that is 165 feet long, 35 feet tall, and 30 feet wide; twenty-two 4-foot diameter steel lined well shafts extending 325 feet from the ground surface to the forebay; 3500 feet of 12-foot diameter pipeline crossing a bay in Lake Mead that has water depths of up to 80 feet; and 2700 feet of 9-footdiameter steel-pipe-lined tunnel. Major site grading for a future pumping station in the area above the forebay is also included as part of the project. The project is on the schedule’s critical path for completing the first phase of a $2 billion water supply program for the Las Vegas Valley. In this paper, the owner, the designer and the construction manager present a discussion of the risk management strategies that were used to control costs, minimize project delays, and facilitate problem resolution. The discussion includes an assessment of the effectiveness of the risk management strategies in meeting these objectives. This paper will be of interest to owners and engineers planning underground projects, especially those projects that present unique risks during the construction phase.

Jan 1, 1999

By Huayang Luo, Hui Li, Wei Zhou, Gang Chen, Scott Huang

The beach and offshore gold resources demonstrated at Nome, Alaska are some of the richest found in Alaska. They contain potentially significant resources that may be exploited in the future. Several companies have contributed to the exploration and reserve estimation in Nome offshore gold deposits. More than 3,000 holes were drilled and over 10,000 offshore samples were analyzed in the Nome offshore areas of approximately 40 km2. Those 3,000 plus drill hole logs were converted into digital formats comparable with ArcGIS software. Considerable amounts of mineral resources data were processed and visualized using ArcGIS 8.3 and its geostatistic, 3D analysis, and spatial analysis components. In this study, based on the data processing and visualization results of ArcGIS, a user-friendly website for mineral resource management and utilization is developed using ArcIMS 4.0.1. ArcIMS is a GIS solution to build and deliver maps, data, and tools over the Internet. The Nome offshore mineral resources website presents the geostatistic and GIS analysis information. This site allows clients to access the information and perform ArcGIS analysis, such as interactive data query, and map layers display of the gold resource distribution, average grade, gold reserve, and relative mineral resource estimation via remote computers. With linkage to other related mining web sites, this web site allows users to search for related publications and more flexibly manage the information. A few other appropriate customized tools are also being developed to assist interactions between the server and clients for data analysis and management.

Jan 1, 2005

By M. E. Lewellyn

A lower moisture content for a clean coal product means increased Btu content, or increased yields at the same Btu content, and lower operating costs. The conventional surfactant-based dewatering aids effeciently lower the moisture content but often the presence of residual surfactant in the filtrate and recycle water causes problems downstream. ACCOAL-DRI 1000, a surfactant-based dewatering aid, was developed to solve this problem by minimizing the downstream effects while efficiently lowering the moisture content. The theory of the use of surfactants in filtration will be discussed as well as the development and field evaluation of this new product.

Jan 1, 1988

By M. A. S. Martins, H. Medeiros, B. Y. B. Dos Santos

This paper contains the geometallurgical studies, performed for Mineração Rio do Norte bauxites, applied to a selected area belonging to Plateau Saracá III, referring to an exploitation period of one year and three months, approximately. It is worth mentioning that Mineração Rio do Norte has the biggest bauxite operation in Brazil producing 8,500,000 tons of concentrate per year. The studies included wide investigations directed to the final objective of establishing a precise mining and production planning, based on the different behavior of the distinct bauxite ores, when submitted to industrial processes. Geometallurgy can be defined as the study of the regionalization (space distribution) of the metallurgical variables of a mineral deposit. This study involves and integrates all process engineering, geology, geostatistics and mining planning, among others. The development and application of the geometallugical studies to Mineração Rio do Norte were motivated by several reasons and necessities, among them: 1. Improving the forecast of the amount of concentrate (metallurgical mass yield) produced; 2. Improving the equipment operational efficiency, providing a more homogeneous feed; 3. Conducting a more precise material balance that permits a better daily, monthly and yearly production control; 4. Improving the forecasts for the final products generated by each ore type; 5. Obtaining better knowledge of the behavior of several ore types, submitted to the different process unit operations; 6. Promoting adequate ore blending, producing an homogeneous feed during mining operation.

Jan 1, 1998

By David Morrison

On the Corramandel Peninsula of New Zealand, the Waihi Gold Mine has undergone a major redevelopment. The upgrade included the construction of two very large overland belt conveyors, both rated for a capacity of 6000tph. The first of these conveyors (CVR2) traverses a total of 1600m over undulating terrain, including a significant section running through tunnels. A large hill is climbed, just after the mid-section of the conveyor run, before dropping back down prior the discharge point. The second of these conveyors (CVR8) traverses 1100m along an alignment with a horizontal curve, a number of vertical curves and a significant lift before the discharge point. The CVR8 conveyor also included a shuttling head pulley arrangement. The mine they service is inside the town of Waihi. The conveyor alignment runs through the town and out to the metallurgical process site on the outskirts of the municipal area. This paper documents the engineering process that took place in the design of these conveyors. The Martha Hill mine in Waihi, New Zealand is unique. The mine is placed in the township. Consequently there are quite stringent environmental limitations on the mine's operation. In [Figure 1] the proximity of the mine to the town is shown. In the top-centre of the photograph the alignment of the existing smaller overland conveyor can be seen leading from the mine to a tunnel through the hill in the background.

Jan 1, 2000

By G. Gillet

The conventional magnetic separators used in the mineral industry are equipped with traditional magnetic circuits or with permanent magnets (rare earth). However, when processing minerals with low magnetic susceptibilities or minerals of very small particle size, these separators are inefficient. In addition, a conventional magnetic circuit consumes considerable amounts of electricity to generate a relatively low magnetic field (~2 Tesla). The equipment is also heavy and bulky. Only a separator having a superconducting sole-noid can contribute in solving most of the problems, and only such a separator can produce high magnetic fields with low energy consumption. New developments and the experience acquired in using these superconducting magnets have resulted in new uses for magnetic separation, especially in the environmental area. This paper presents and describes a separation system that uses superconducting magnets that are completely automated and able to treat raw materials (concentration or purification) or liquid industrial effluents containing heavy metals in solution. Several industrial sectors, including the surface treatment, petroleum and chemical industries, are generating effluents containing heavy metal ions. The main metal ions found in such effluents include zinc, copper and vanadium. The purification of such effluents by magnetic separation is performed by adding a certain proportion of iron salts. The treated effluent passes through a superconducting separator where the flocs are retained in a matrix of steel wires. The efficiency of supraconducting high-gradient magnetic separation (HGMS) by this method exceeds 95%. Mineral separation and industrial-waste purification results are presented.

Jan 1, 2000

The world's largest hydraulic excavator was recently introduced at Syncrude's North Mine at Fort McMurray, Alberta, in Canada. O&K's 826t (910-st) behemoth RH400, with a 42-m3 (55-cu yd) bucket, is capable of loading 72.5 t (80 st) in one pass. Syncrude's Alberta operation is the nation's largest single source of crude oil. It is also the world's largest producer of oil from oil sands. Syncrude produces 205,000 bbl/day, expects to increase production to 225,000 bbl/day by 1999 and to 320,000 bbl/day by 2005. That translates to 73.5 million bbl of Syncrude Sweet Blend (SSB) produced in 1996, 82 million bbl in 1999 and 114 million bbl in 2005. The North Mine is a new development that will replace the current East Mine, to be depleted of oil sand by the end of 1999. The North Mine will feature hydrotransport, a new and unique method of transporting oil sand from the pit to the process plant. Oil sand from the truck-and-shovel operation will be processed through a double-roll crusher and placed in a cyclofeeder where it mixes with hot water. The material is then screened and transported by pipeline to the extraction plant. Hydrotransport will replace conventional conveyor transport for moving raw product from the pit. Mine development will also use two 290-t (320-st) haul trucks to compliment the fleet of existing 218-t (240-st) trucks.

Jan 1, 1998

By Connor Meinke, Shaihroz Khan, Kevin Erwin, Rajiv Chandramohan, Muhammad Usman Siddiqui

A geometallurgy study aims to link metallurgy and geology to reduce technical risk and enhance the economic performance of a mineral-processing plant. It does so by accounting for variability in a deposit to develop cash-flow models with variable throughput rates. High-quality sample selection for metallurgical test work that is representative of the deposit is an essential component of a geometallurgy study, but the large multidimensional data set makes sample selection a daunting task, as classifying the data set while respecting its heterogeneity is difficult. This paper presents a streamlined approach for sample selection, using statistical analysis techniques in Python. It cuts down time to select samples from around 1,200 s per drillhole to about 60 s for data classification and from 12 h to 8 h for handpicking samples from the classified data set, translating to cost savings. The cumulative sum method and k-means clustering method are used in the methodology to elegantly classify the data and select representative samples. The effectiveness of the methodology is demonstrated by presenting data from a prefeasibility study of a copper-iron mine in which 40 samples were selected for flotation test work.

Dec 1, 2024

By Olli Järvinen

The precious metal refinery process is divided into the five process stages: 1 .copper/nickel leaching in autoclave 2. selenium roasting furnace 3. doré metal smelting furnace 4. silver electrolysis 5. gold recovery system. The process has been developed during the years in Outokumpu Harjavalta Metals, which treats about 600000 kg /year copper anode slime. The slime treatment process route in Outokumpu Pori plant has been developed from year 1941. During this period the process has been improved radically. The major changes has been the atmosphere leaching into the autoclave leaching, the sulfuric acid roasting furnace was changed into sulfuric dioxide / oxygen roasting. The old doré smelting furnace has changed into the TROF converter and the gold electrolysis / aqua regia process has changed into the quick hydrochloric acid leaching process. The current production in Pori plant is 30000 kg of silver, 1000 kg gold, 30000 kg of selenium and some hundred kg of platinum- palladium concentrate.

Jan 1, 1995

By D. R. Gehring

Effective project management is an excellent technique for meeting a goal through set, well-defined objectives. Even though project management is successfully used throughout the world in various construction projects, underground mining has unique characteristics that require approaches that vary from classical project management theory. Typically, a project includes four main stages: definition, planning, implementation and control. Definition and planning are often the most overlooked stages, but are arguably the most important. This paper addresses practical techniques for the definition and planning of projects for underground construction.

Jan 1, 1996

By Fred N. Kissell

INTRODUCTION During the last few years, several new ventilation developments have attracted the interest of mining engi¬neers. Some of these developments are applicable pri¬marily to hard-rock mining, while others are more applicable to coal mining. STOPPINGS Parachute Stopping The parachute stopping is a new type of quick-erect stopping that is intended for temporary use in hard-rock mines (Kissell, Thimons, and Vinson, 1975). As shown in Fig. 1, the stopping is shaped very much like an ordinary parachute, with a canopy of impermeable fabric that is sewn to regularly spaced straps running to a common point. To erect the stopping, the straps are attached to a fixed anchor point such as a roof bolt, and the edge of the canopy is lifted into the moving air¬stream. The airstream pops the parachute canopy into place, and the differential air pressure across the stop¬ping holds it in place, forcing the fabric against the walls, roof, and floor of the mine opening. The principal advantage of the parachute stopping is that it requires only a few minutes to install, making it a great time-saver for emergency use or for day-to¬day changes in ventilation during the production cycle. However, the parachute stopping does require some minimum air velocity to lift it and some minimum differential pressure to hold it in place. For a fabric weighing 0.27 kg/ m2 (8.0 oz per sq yd), the minimum air velocity is about 0.5 m/s (100 fpm), and the mini¬mum differential pressure is about 0.05 kPa [0.2 in. water gage (WG) ]. There is always some air leakage around the stop¬ping, mainly depending upon the extent to which pipes or other obstructions encumber the airway and prevent good sealing. Leakage of a few cubic meters per second (a few thousand cubic feet per minute) can be expected, unless foam is used to improve the seal at the edges of the canopy. Quick-Fix Blowout Stopping The quick-fix blowout stopping is a variation of the parachute stopping (Thimons and Kissell, 1976), and it is used in the proximity of blasting operations. This type of stopping is designed to be blown out easily by the blast forces, and it may be reinstalled quickly and easily. The long high-strength straps of the parachute stopping are replaced by groups of short straps that tear easily. These straps are attached at six equally spaced locations around the perimeter of the canopy. To erect the stopping, one strap of each of the six groups is fastened to the mine wall, roof, and floor by using spads, by setting pins with a powder-actuated gun, or by tying the straps to some firm anchor point. Once the straps have been attached, the differential air pressure across the stopping, which must be at least 0.025 kPa (0.1 in. WG), forces the stopping perimeter against the mine walls, thus creating the air seal. It is the self-sealing feature of this stopping that makes it a significant time-saver. Only a few attachment points are needed; in many cases, four attachment points are sufficient, since the stopping naturally tends to form a seal with the airway surfaces. When nearby produc¬tion blasting exerts excessive forces on the stopping, one or more of the straps tears away from its attachment point, protecting the stronger canopy from damage. Damage-Resistant Brattice The damage-resistant brattice is a stopping that is designed for use in mines such as salt and limestone mines where the differential pressures are low and the roof is relatively flat. As shown in Fig. 2, the damage-resistant brattice consists of a series of brattice panels that are hung vertically and joined by Velcro® connections. When the brattice is subjected to strong blast forces, the Velcro® connection peels apart and allows the panels to open without incurring damage. The Velcro® connections can be resealed by hand within a matter of minutes. Such damage-resistant brattices have withstood the blast effects of 318 kg (700 lb) of ammonium nitrate-fuel oil (ANFO) explosive detonated as close as 91 m (300 ft) from the brattice. Ordinary brattice cloth is used for the panels, with a 51-mm (2-in.) wide strip of Velcro® hooks sewn along one edge of the length, and a 51-mm (2-in.) wide strip of Velcro® pile sewn along the other edge. Both the hooks and the pile are sewn onto the same side of the brattice cloth. The resulting Velcro® seal formed be¬tween adjacent panels is perpendicular to the brattice itself, and the leading edge of the seal can be directed either toward or away from the blast forces; the brattice works equally well in either case. To hang the brattice, panels of brattice cloth about 0.9 m (3 ft) longer than the height of the airway are cut from a 1.8-m (6-ft) wide roll. The additional 0.9 m (3 ft) of brattice cloth allows 0.3 m (1 ft) for attachment to the roof by means of a board, with 0.6 m (2 ft) for forming a good air seal at the floor. Each brattice panel is wrapped once or twice around a 51 X 102 mm (2 X 4 in.) or 25 X 76 mm (1 X 3 in.) mounting board that is 254 to 305 mm (10 to 12 in.) shorter than the width of the panel. For convenience in

Jan 1, 1982

By John W. Tieman

The increasing magnitude of our nation's pollution problems seems to stem from two main factors: urbanization and technical advance. In 1920, less than half the country's 106 million people lived in cities. Forty years later, the urban population accounted for 70 percent of the nation's 179 million. It is predicted that by the end of the century, 95 percent of the U. S. population, estimated at 280 million, will live in urban areas. As these people live increasingly in city concentrations, their residues also concentrate. With technological advances to support the increasing population, the variety and quantity of goods that we use also increases. New materials and processes result in increases in pollutants, some of them new. The harmfulness of these pollutants is sometimes known, but sometimes only suspected. One pollutant of concern at the present time is sulfur dioxide, the product of combustion of sulfur-containing fuels. Research on processes to remove sulfur oxides from flue gas has been in progress for many years. Pioneers in this field were the British who, in the early 1930's, installed a full-scale flue gas scrubbing unit on a 120 MW boiler using alkaline water from a Thames estuary plus chalk. Since that time, various methods have been studied by many investigators. Federal laws covering air pollution started with the 1955 Air Pollution Control Act. With the advent of the Air Quality Act of 1967, and subsequent publishing of criteria and available technology for control of sulfur oxides in January 1969, the clamor for information on commercially available control techniques to remove sulfur from fossil fuels has rapidly increased. Although many state-of-the-art papers have deluged the literature during the past several years, the research going on in the area of sulfur oxides control is of such importance that periodic reviews are justified. It is the purpose of this paper, therefore, to again review the state-of-the-art, but this time from the stand-point of what is immediately commercially available

Jan 1, 1972

By J. Harrison Daniel

More stringent dust standards, because of quartz in coal, have become a major compliance problem for the coal industry. Reducing quartz levels has become the major focus of the Bureau of Mines dust control research program. Results to date have identified hath the sources of quartz and prospective control technology. Control techniques are being developed for both room-and-pillar and longwall mining underground operations. Techniques include changes in face ventilation, mining cycle modifications, and better roof bolting dust control.

Jan 1, 1985

By A. M. Marabini, G. Belardi, V. Alesse, M. Acosta

Sotiel mine is situated in the Iberian Pyrite Belt in southern Spain, some 40 km north of the port of Huelva. Although mining operations at the site date back to Roman times, the present mine came into production in 1983 and 5.6 million tonnes of ore had been extracted by 1993. The orebody is volcano-sedimentary and consists of fine grained copper, lead and zinc minerals in massive pyrite surrounded by slates and volcanics. Prior laboratory research had resulted in the synthesis of a new collector, belonging to the MercaptoBenzoOxazole (MBO) class that acts selectively towards Cu and Zn minerals after activation with CuS04. The MethylMercaptoBenzoOxazole (MMBO) version of this collector had been used for the laboratory flotation of Cu minerals and sphalerite activated by CuS04. This resulted in identification of the optimal physicochemical conditions for laboratory-cell flotation of the two minerals from samples of complex sulphide ores, and subsequently the reagent has been tested in the Sotiel plant (Spain). The plant has three flotation sections. With conventional re-agents, the first section yields a Cu concentrate grading 21% with a total recovery of 29%, and the second one yields a 40% Pb concentrate with total recovery of 34% and a 47% Zn concentrate with total recovery of 78%. Application of the new synthetic reagent in the copper and zinc circuits produces a more selective process with a decrease in re- agent concentration grade and recovery are increased by 2 and 9 points respectively in the case of Cu and by 1 and 3 points where Zn is concerned. Moreover, the penalty elements in the Cu concentrate are halved.

Jan 1, 1995

By R. L. Grayson

The health and safety of employees, efficiency of the operating system and production are paramount goals in underground coal mining. The section foreman assumes responsibility for making his part of the total system function to meet these goals. However, section foremen often have not been prepared to assume the full range of their responsibilities upon becoming a supervisor. This discussion addresses the full range of section foreman responsibilities and concomitant authority. Management principles that must be mastered by him are presented, and performance expectations as well as criteria for their evaluation are examined. The benefits realized from effective foreman training are discussed.

Jan 1, 1985