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By H. C. Verakis

Permanent ventilation controls such as stoppings, overcasts, and undercasts for use in coal mines are required to meet MSHA’s safety standards for fire endurance and flexural strength. Due to technological advances in materials and their design for use as ventilation controls, an engineering program was established to evaluate newer or “nontraditional” ventilation controls. The program is intended to assist manufacturers, enforcement personnel and mine operators in determining if “nontraditional” ventilation controls, for example plastic membrane construction and lightweight block, meet the prescribed safety standards. The program is presented with a description of required tests and examples of products evaluated.

Jan 1, 2003

By David Field, David Powell, Richard Hulsen

The Mission Valley Light Rail will loop through San Diego State University (SDSU)and to minimize the impact of construction most of the works will be underground. The project will require construction of a 330-m long (1080-ft), 11.24-m wide (36.9-ft),single twin track tunnel through Stadium Conglomerate, a poorly cemented dense sandy gravel with cobbles. Key technical issues are discussed including the ground conditions and predicted ground response, the use of sequential excavation methods to control deformations and specific construction concerns such as instrumentation and monitoring. Management of the construction process to minimize risk is particularly important in this environment and the strategy selected to control the works is also considered.

Jan 1, 2001

By M. J. Senk, A. Lusin

Federal regulations require that methane liberated at the face be diluted and removed to maintain methane gas concentrations below 1pct (CFR) in working places and intake air courses. The delivery and distribution of intake air at the face is critical for effective face ventilation. Improved techniques for monitoring the movement of intake air to the face are needed. A test system was developed and a computer program written for using a three-axis ultrasonic anemometer to measure airflow in a simulated mine entry. Results of tests conducted in the entry showed that the anemometer is a valuable tool for measuring mine airflow conditions near the face.

Jan 1, 2003

By R. E. J. Putman

The past ten years have witnessed substantial development of electronic equipment for execution of process control functions. The methodology of giving instructions to the data-handling system and the organization of the system, both the equipment and instruction coding taken together, have developed simultaneously. Examples of the technology specific to the mineral processing industry can be cited. Approaches to system design developed for the Pinto Valley concentrator incorporating slave and master data processing have been described by Arney, and his associates (1974). Madge (1970) has described the hierarchical systems employed at the operations of Cominco Ltd. The Kennecott Garfield smelter is controlled by a system of microprocessors linked to a general purpose data processor (Marchant, et al., 1977). These systems provide innovative approaches to couple advancing technical capability in electronic data processing to the objectives of process management. The current state of the art described in this chapter is certain to require updating in the 1980's with the advances in technology anticipated.

Jan 1, 1979

By Ron M. Canon, John M. Begovich

Chromatography, ion exchange, and other techniques based on the interaction of solutes with solid phases offer versatility, high resolution capabilities, and near-universal potential applicability for the separation of valuable constituents in liquid solutions. The expense associated with obtaining reasonable throughput for these separations has been the only, albeit overwhelming, obstacle preventing widescale use of these methods. Attempts to devise continuous (cheaper) systems have previously resulted in moving, or simulated moving, beds of resin with complicated valving and timing sequences. These disadvantages, plus technical problems associated with the disturbing effects of non-plug flow and reduced resolution of moving versus packed beds, severely limit applicability of these systems. Over the past decade a new device has been developed that overcomes many of these problems. It utilizes a slowly (less than one revolution per hour) rotating annular bed of sorbent material with fixed-feed inlet and product withdrawal points. Numerous units of various diameters and lengths have been fabricated and operated, and a parallel effort has developed a satisfactory theoretical treatment of the device. Several simple control systems have been incorporated to thoroughly demonstrate the simplicity of operation, even for multiple products and multiplecarrier flows. This device has been developed using several metal solutions and has demonstrated its power with some of the most difficult, including the zirconium-hafnium, separations. Design equations are available for sizing units based on simple laboratory data and have been tested for units as large as 18 in. in diameter.

Jan 1, 1985

By H. P. Ehrlinger

The Negociacion Minera Santa Maria De La Paz mining operations are located at La Paz (some eight miles West of Matehuala), State of San Luis Potosi, Mexico. These operations consist of a single copper-silver property, called the Dolores mine and a number of silver-low base metal properties. The ores from these several mines are transported by rail, or truck, to the central milling unit. The milling unit has two separate sections to treat the two types of ore. The ores from the several silver-base metal mines are mixed at the mill as they arrive. Up to the present time the silver-base metal ores have been milled to produce a bulk concentrate which carries valued in gold, silver, copper, lead, zinc, cadmium and considerable arsenic. In such concentration the zinc and cadmium values are lost to the operations in their liquidations as they are shipped as lead concentrates. Since these ores have exceptional quantities of arsenic which is concentrated in the milling process, these bulk concentrates have to be sent to a smelter for pre-smelting operations to remove the arsenic.

Jan 1, 1964

By Edgar T. Gregory

A quiet revolution has taken place in the conveyor belt industry, Man-made materials, improved production facilities, better splicing techniques and emphasis on repair and maintenance have all contributed substantially to lowering material handling costs for the mining industry, It wasn't too many years ago that the rubber industry had only cotton for a belt carcass and tree grown rubber for the protective cover. Then came the development of monofilament rayon. This material had desirable elongation and elastic properties and was the first synthetic fiber to be used in place of cotton. But wet strength and other limitations restricted its use, and the conveyor belt industry turned to nylon. Initially, nylon was considered suitable only for the cross threads or filler threads of a belt carcass. Then technical advancements in heat setting and fabric weave created a major change in belt construction. As a result of these advances the industry was able to take advantage of the full tension strength of nylon cord. Another breakthrough in the use of synthetics was the tremendous increase in adhesion resulting from a chemical bond, rather than the limited physical bond available with cotton. But the advantages of nylon had a more Car-reaching effect, We were able to design a two-ply nylon belt that did the work of a four- or five-ply cotton or rayon belt. A six-ply nylon belt now replaces a twelve-ply cotton elevator belt. Arid nylon resists moisture, acid and mildew, It also has excellent resistance to impact and can be produced with controlled elongation and elastic properties that work to great advantage in reduced-ply belt constructions.

Jan 1, 1971

By Roe-Hoan Yoon

INTRODUCTION In 1960, coal accounted for 49% of the world energy consumption, an amount that was reduced to 29% in 1973 because of the availability of cheap oil. At that time, it seemed that oil would remain available for a long time in unlimited quantities. However, this situation changed drastically in 1973/74 when a series of closely spaced price increases from $3 per to $12 per bbl by mid-1974 hit both industrialized and developing countries. Another sharp price increase in 1979/80 to the $34 to $38 per bbl level also hit the world economy hard and, at the same time, set in motion powerful technology development forces for increased coal utilization. At this point, the price of coal was approximately $1.50 per MM Btu, while that of oil approached $6.00 per MM Btu. This huge price differential offered an incentive for developing new coal technologies including liquefaction, gasification, fluidized bed combustion, coal-water mixture (CWM), etc. The CWM technology was of particular interest to the utility industry, which consumes more than 80% of the coal mined in the US for power generation. In this technology, a powdered coal is mixed with water to produce a stable slurry that can be stored for an extended period of time without settling and is readily pumpable. Various reagents in the amount of approximately 1% by weight of the coal are added to inhibit sedimentation during storage and to reduce the viscosity for atomization in burners. The coal loading is in the range of 50 to 80% solids, depending on the particle size and its distribution. With very fine particles, it is difficult to increase the coal loading above 50%, and a binomial distribution helps increase the coal loading. The presence of water consumes a relatively small amount of the heating value of the coal during combustion; for a coal-water slurry containing 30% water, less than 5% of the calorific value of coal is usually consumed due to evaporation. The major advantage of burning coal as a slurry is that many of the oil-burning furnaces can be converted to coal-burning with a minimum retrofit cost. Considering the substantial price margin between coal and oil, the pay- back period for retrofit costs can be relatively short. Nevertheless, the retrofit cost can be further reduced if low-ash coals are used as feedstocks for CWM; there will be savings in the capital cost of installing bag filters or electrostatic precipitators that are designed to remove the ash from the combustion gases. Furthermore, the use of low-ash coals can minimize derating of boilers because the velocity of the combustion gases can be maximized without creating erosion

Jan 1, 1991

By Tsuneyoshi Funazaki, Takayoshi Nakamura, Keizo Miki, Takashi Imaishi

The underground portion (about 10 km) of Tokyo Wan Aqua-Line consists of eight shield tunnels connected with Kawasaki Man-Made Island in between, at four underground locations. The connection work had to fulfill strict precision and safety requirements in the ground about 60 m below soft seabed, but was completed successfully in May 1997. This report describes the connection work in detail, featuring the method of investigating shield machines’ relative positions, ground freezing method and connection mechanism and procedures. It also mentions the present state of Tokyo Wan Aqua-Line that was put in service on December 18, 1997.

Jan 1, 1999

By P. Berendsen

Structures along the rift were subjected to episodic reactivation. Major north-northeast-trending high-angle normal or reverse faults and northwest-trending trans-current fault systems, may exercise control over ore-forming processes. Gabbro and basalt are the dominant igneous rock types. Carbonatite and kimberlite occur in Nebraska and Kansas. Concentrations of Cu, Ni, Co, Ti, Au, Ag and PG-minerals are known to occur in this setting Arkosic sandstone, siltstone, shale and minor carbonate units occur on top of the rift basalts and in flanking basins where they may reach thicknesses of 10 km. The potential for stratiform or unconformity-related metal liferous deposits must be considered.

Jan 1, 1986

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 G. R. Erdman

The industrial mineral filler plant of the Gouverneur Tale Company is equipped with a good dust collection system installed long before the recent popularization of environmental pollution. Credit for this fact is due to the foresight of Mr. R. S. McClellan, Project Manager and subsequent Vice President and General Manager of Gouverneur Talc, who recently retired as Vice President Engineering of the parent organization, the R. T. Vanderbilt Company. Also instrumental in the early stages of plant operation and the solution of start-up problems was J. A. Gustin who is now an engineering consultant located in Martinsville, Va. Credit is most certainly due to the late R. T. Vanderbilt, the company's founder, who favored and approved the investment in the necessary facilities that were far ahead of all competitors in the industry at that time.

Jan 1, 1972

By R. H. T. Garnett

Reserve estimation is a process that commences with sampling and culminates in the issuance of a reserve statement. The tin, gold and diamonds that occur as marine placers on the continental shelf are low grade with very erratic mineral distributions. Sampling, using a variety of special equipment, determines the extent and grade of the mineralization. The sample size is important, especially for diamonds. Together with the sampling density, it determines the accuracy of the grade estimate. Bulk sampling is a confirmatory process. The choice of mining equipment, either new or developed from onshore activities, dictates the unit costs, the cutoff grades and the selectivity of extraction. Thus, the size of the blocks that comprise the mining plan and the reserves are determined. A variety of estimation methods of different reliability are available, with the most sophisticated being kriging. Dilution and losses during mining must be taken into account in estimation, and a grade-volume curve should be constructed. Diamond deposit estimation also involves an extra variable, the dollar value of the stones. During and after mining, essential feedback on the accuracy of un estimation may be given by the RIE factor and by a mineral balance. Reserve estimates are required for several reasons and may be subject to public disclosure. The use of the correct definitions is, therefore, important.

Jan 1, 1999

By Donald L. King, Frank A. Baczek

Sedimentation-based equipment is used in applications where separation of solids from liquid by gravity settling is desired. If a concentrated solids slurry is desired, the equipment is designed to "thicken"; if a clear liquid is desired the equipment is designed to "clarify." Thickeners normally handle higher solids loading rates than clarifiers, which usually process feed slurries containing low concentrations of suspended solids. Thickeners are therefore designed for heavier-duty requirements, and clarifiers have extra features to ensure more complete suspended solids removal. Major components (Figure 1) that are common to all sedimentation-based equipment are: tank, drive-support structure, drive unit and lifting device, rake structure, feed well, and a means of overflow and underflow withdrawal. Specific features are designed interdependently after the overall separation approach is defined conceptually. This conceptual approach is usually based on past experience or evolves from sedimentation studies conducted on samples of the slurry to be handled. Because many variations and combinations of components are possible, the overall conceptual approach has a number of possible designs that will accomplish the desired results. The final choice is based on practicality, potential for minimizing upsets, and cost.

Jan 1, 1986

By Robert E. Blackett

To help local governments plan for long-term supplies of sand and gravel for buildings and infrastructure, the Utah Geological Survey is assessing natural aggregate resources (mainly sand and gravel) in the St. George, Utah area. Whereas much of the aggregate in the study area is adequate for road-base construction, high-quality aggregate for Port- land cement concrete is limited due to geology, and also due to land administration and environmental issues. Virgin River alluvial gravels southwest of St. George are generally poor sources of aggregate because they contain clasts of soft sediments and soluble minerals derived from Mesozoic rocks. Elsewhere, widespread secondary calcium carbonate (caliche), as rinds and matrix in gravel, lower the quality of material. Young river-terrace deposits in Fort Pearce Wash, and along the Virgin River above St. George are the primary sources of sand and gravel for the area. Alluvial fans on the east side of the Beaver Dam Mountains, and on the west side of the Hurricane Cliffs are also sources of aggregate. Stream-channel deposits associated with "inverted valleys" north of the towns of St. George and Hurricane, Utah, and older pediment gravels on the west flank of the Beaver Dam Mountains may be future sources of high-quality aggregate. Accelerated urban development during the 1980s and early 1990s has caused St. George and other communities in Washington County to encroach upon sand and gravel pits originally located in rural, undeveloped areas. Urban residents often view nearby sand and gravel operations as undesirable neighbors and pressure elected officials to close the pits. Pit closures effectively eliminate the remaining reserve from the sand and gravel resource base of the area. More- over, resources may also be lost as new homes are built upon undeveloped sand and gravel deposits. The St. George area is particularly susceptible to loss of aggregate resources because high-quality natural aggregate for construction is already in short supply. Moreover, most of the land in the study area is administered by the U.S. Bureau of Land Management and subject to various land-use restrictions. Much of this public land cannot be developed for mineral materials, such as sand and gravel, because of federal regulations protecting rare plants and animals, archaeological sites, and important watershed areas. Of particular concern to resource development are areas designated as Areas of Critical Environmental Concern, Wilderness Areas, and Wilderness Study Areas. Protection for Endangered Species is a critical element in all planning efforts. Those species present in the St. George area or in areas near- by include: the desert tortoise, southwestern willow flycatcher, Virgin River chub, and dwarf bearclaw poppy. As the St. George area is depleted and/or deprived of sand and gravel resources through extraction and urbanization respectively, construction costs will rise unless conservation measures are instituted. To avoid the loss of aggregate resources, the UGS is pursuing a program of data gathering and field surveying of surficial deposits to determine tonnage and quality of the remaining sand and gravel resources. The resource information from this program will help land planners, developers, and government officials make informed decisions concerning urban development throughout the region.

Jan 1, 2001

By J. A. Madonna

Independent prospectors and small to large-scale exploration company personnel have requested, and are in need of, guidance in geochemical field sample collection methods which will provide the most reliable results during chemical analysis. In cooperation with analytical laboratories, experienced geochemical exploration scientists and mining companies a systematic collection procedure has been developed. The procedure consists of collecting uncontaminated, water, sediment and rock chip samples of the appropriate quantity and/or dimensions to meet the needs of analysis.

Jan 1, 1999

By D. A. Ellis

This paper review s several new applications of solvent extraction developed in conjunction with a research project carried out under the AEC Raw Materials Division by the Dow Western Division laboratories during the last two years. A process for recovery of uranium from ores by contacting the solid directly with organic solvent without a prior aqueous leach and a process for uranium recovery by contacting thick, unfiltered leach slurry with the solvent were studied in an attempt to simplify ad reduce the cost of ore treatment procedures. Processes to produce pure UF4 products at the concentrate mills thus eliminating the production and subsequent dissolution of the concentrate were investigated. Since many of the leach liquors contained vanadium as well as uranium, solvent extraction processes for by-product vanadium were also studied.

Jan 1, 1958

By Brian H. Jasperse, Nicholson Peter J.

Gravity retaining walls have been constructed using Deep and Shallow Soil Mixing (DSM and SSM) since 1991 in the United States. These walls, for both temporary and permanent uses, were constructed by mixing cement with in-situ soils over a volume containing 100% of the required gravity wall zone. Modern design techniques have reduced costs substantially by forming the required gravity wall section as a composite mass. Using ratios of 15-35% by volume, treatment f the ground forming the required gravity section has reduced the cost from about $40 to about $20 per square foot. Design, construction and actual performance of these gravity walls are presented.

Jan 1, 1999

By D. A. Day, H. L. Marsh, P. J. Stephens, C. A. Wiggins

Lightweight cellular grout backfill behind pipe-in-tunnel has been gaining increased acceptance in the tunneling industry and has proved to be both practical and economical. Two successfully constructed projects, the Upper Scioto West Interceptor Sewer (USWIS), in Columbus, Ohio and the Benbrook Pipeline Tunnel Project in Fort Worth, Texas will be discussed. The projects represent two different but successful applications of lightweight cellular grout backfill. The USWIS placed the grout behind precast reinforced concrete pipe, in water bearing limestone, and in close proximity to residential water wells. The Benbrook Project placed grout behind 6,096 meters (20,000 feet) of steel pipe from just two locations, eliminating major surface disruption typically associated with the placement of pumped concrete.

Jan 1, 1999

By J. O. Marsden

The Candelaria copper-gold mine is located approximately 25 km south and east of Copiapo in Region III, Chile. The original concentrator was designed to treat 28,000 t/d (30,800 stpd) of chalcopyrite-bearing ore through a circuit consisting of a single 11.0 m (36 ft) diameter SAG mill, two ball mills, conventional rougher and scavenger flotation, column cell cleaner flotation, and ceramic disc filtration. The plant was commissioned in August 1994 and quickly reached capacity and expected levels of metallurgical performance. In May 1996, a decision was made to double the capacity of the concentrator by the addition of a second line of equipment. The expanded facilities were commissioned in October 1997, less than 18 months after the decision to proceed, and well within the budget. The original concentrator facilities were replicated or duplicated as much as possible, however, a number of important equipment changes were made to take advantage of industry developments since the original concentrator was designed. These included the use of Eimco 120 m3 (4,200 ft3) cells for rougher and scavenger flotation and the installation of a Svedala VTM -800 Vertimill for regrinding. This paper describes the rationale behind these changes and explores the reasons for the success of the project.

Jan 1, 1999