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By William S. Gilmer

INTRODUCTION As man moved through the ages into the era of metals, he became increas¬ingly dependent on the extraction and beneficiation of various ore types. His progression has required more material, new sources, and inevitably, a need to extract the values from ores of much lower yield. Inherently welded to this need to extract has been the attendant requisite of power and water to carry out these tasks. With the richness of these deposits diminished, and the in¬crease of demand, mining has become so intimately tied with the needs of these auxiliary systems that the modern day milling operation can ill afford to ignore them. In the times of Agricola 16th century methods of milling required little thought for power or water consumption. Reduction was accomplished by hand¬sorting and hammer and grinding done with stamps and millstones. Medieval concentration was carried out by the "Jigging sieve" with agitation supplied by the sleeveless arm of the operator (The Mines Magazine,_ March 1933). Little consideration was likely given to the power source unless it became apparent that he had insufficient means to meet the demands of a dawn to dusk operation. Fuel for power production was also probably of little consequence unless sustained drought or warring neighbors burned the miners fields. Water was available from any adjacent stream with recycle, potable, tailings and mill consumption all going and coming from the same source. By the end of the 18th century and the early 19th century the requirements of larger throughputs and better re¬covery were forcing the miner to the need for greater sources of power and water. Arrastras, capable of accepting several hundred pounds of charge, con¬sisted of a clay bottom, a "liner of rocks harder than the substance to be crushed" and a revolving center post in which the ore was ground and amalga¬mated. Used in conjunction with a slucing system, this formed the primary recovery method of the time. Power was supplied by horse or oxen or, if terrain was amenable, by use of a horizontal or overshot water wheel. A typical system required 4.5 kw (6 hp) and needed to run in the vicinity of 15 rpm (Pre¬ston, 1895).

Jan 1, 1986

By E. I. Jurgens, K. E. Hanney, D. C. Comrie, R. H. Fletcher

Introduction The reclamation of mine/mill tailings areas is undertaken for a variety of objectives including safety, appearance, economical use of lands and forests and long term storage of a future resource. The establishing of criteria for these objectives at any site is a shared task of the government and mining company. Our attention in this paper is directed to uranium mine/ mill tailings as they are handled in the Canadian industry and in the unique Canadian climate. We focus our attention on the state of the art. Uranium is a ubiquitous mineral forming an average of 4 g per tonne of the Earth's crust. Ores are mined at about 500 g per tonne so that the residual content of uranium in tailings is comparable to average background levels. However, as in most mine/mill operations, the ore contains other minerals that become readily mobile after milling operations. Thus the main objective of tailings impoundment is the stability both physically and chemically of the mobile materials. Since the requirements for the operation and construction of tailings areas in Canada have changed considerably over the past decade, there exists a great many mine/mill tailings areas which while considered adequate in their day, would not meet modern criteria. However, most of these installations pose no concern or hazard to the public. The proximity of mine/mill development to inhabited land areas has necessitated more stringent modes of tailings operations and provisions for tailings site reclamation. The more important of these have been: 1) the prevention of dyke failure, with large liquid-solid outflows onto adjoining lands, and 2) the prevention of seepage from the tails of pollutants such as chlorides, sulphides, heavy metals and radionuclides. Uranium mill tailings are discharged as a slurry from the concentrator after the removal of generally only about 1000 g, or less, per tonne of uranium from the as-mined ore. As a consequence, a great volume of low level activity waste is generated. The amount of tailings is expected to grow in quantity in the future even faster than the increase in yellowcake production, as the demand for energy

Jan 1, 1980

By Robin Dill, Wei Song, Andrew Perham, Leo Martin

"AECOM completed a subsurface exploration program for an 18-foot diameter, approximately 4-mile long rock tunnel project in Hartford, CT. The tunnel crosses the regional geologic trend through the middle of a sedimentary basin, passing through four separate rock formations, including two volcanic flows. Faulting is prevalent, with at least 15 faults encountered during the site investigation. Severe artesian flows were also experienced in several of the borings, requiring highly specialized drilling equipment. Sixty-two borings and associated testing were performed to characterize the structural geology, hydrogeology, rock properties and ground conditions. A phased program was carefully planned and implemented with participation of geotechnical and geologic specialists, with thoughtful evaluation along the way to react to the ground conditions encountered, and make appropriate refinements. This paper will discuss the subsurface program details; the integrated efforts used to effectively characterize the ground; and will summarize the final characterization presented in the GBR. PROJECT DESCRIPTION The South Tunnel Conveyance and Storage Tunnel project is part of the Metropolitan District (MDC’s) Long Term Control Plan to address discharges to various water bodies throughout the greater Hartford area. This program includes a main conveyance and storage tunnel; a tunnel boring machine (TBM) launch shaft and retrieval shaft; adit tunnels with associated drop shafts and connection structures; consolidation conduits and manholes; and a tunnel pump station (TPS) at the downstream end of the main conveyance tunnel. AECOM is serving as prime designer for the MDC on this project. The main conveyance tunnel (hereinafter referred to as the “South Tunnel”) will be a deep rock tunnel with an invert depth of approximately 180 feet at its downstream end and approximately 218 feet at the TBM retrieval shaft. The tunnel will have a finished diameter of 18 feet. The tunnel will rise in grade at a slope of 0.1 percent to its upstream end. Total invert depth along the deep tunnel alignment ranges from about 180 ft. to as high as 320 feet. The total length of the tunnel will be 21,754 feet. The South Tunnel will be constructed using a shielded TBM and fully lined with pre-cast concrete segments."

Jan 1, 2016

By R. E. Vivas, J. Garcia

"INTRODUCTION Freeport-McMoRan is a leading international natural resources company that operates large, long-lived, geographically diverse assets with significant proven and probable reserves of copper, gold, molybdenum, cobalt, oil and natural gas. Freeport-McMoRan is the world’s largest publicly traded copper producer and largest producer of molybdenum. The Sierrita mine is an open pit truck and shovel operation from which copper and molybdenum are produced. An important key to Sierrita’s success lies in their ability to realize their plans in the field. In certain circumstances, the mine plans are not achieved, and the operation fails to meet its targets which is an issue revealed in reconciliation reports. This technical session discusses the methodologies and procedures used at Sierrita to monitor the implementation of the mine plans, measure the performance of the operation and reduce the variance between plan and actual. Ensuring the operation stays on target is vital so mine productivity and profitability can attain its maximum potential. PROJECT OVERVIEW The Sierrita mining complex is located in Pima County, approximately 20 miles southwest of Tucson, Arizona as shown in Figure 1. The first mining claims at Sierrita date back to the late 1800s while underground mining activities started in the early 1900s. However, open pit development of Sierrita began more than 50 years ago to become the modern mining complex it is today. In 2009, Freeport-McMoRan purchased the adjacent Twin Buttes copper mine, providing significant synergies in the Sierrita minerals district. This venture included the potential for expanded mining activities, operations growth for mining copper and molybdenum, and reclamation activity. It should be noted that in addition to copper and molybdenum, the Sierrita mine produces rhenium which is a rare and highly value metal. The ore deposit contains oxide and sulfide mineralization. The oxide ore is delivered to the leach process while the sulfide ore is routed to the crusher and mill circuit 4,700 jobs on Arizona’s economy Freeport-McMoRan partners with the communities near Sierrita to provide programs that contribute to their sustainability"

Jan 1, 2015

By David G. Chedgy

Noise control is an important consideration in the design and operation of coal preparation plants. It is essential to understand and control noise sources to provide a safe environment for operating personnel. The average noise exposure levels in a typical coal preparation plant generally range between 95 and 100 db. An operator should not be exposed to noise levels of this magnitude for more than 4 and 2 hr, respectively, according to MSHA (Mine Safety and Health Administration) regulations. The major noise sources in a coal preparation plant include noise from impacting the inside surfaces of steel chutes, vibrating screens, coal crushers, pumps, motors, fans, and blowers. The magnitude of noise varies considerably from one situation to another. NOISE EXPOSURE IN COAL PREPARATION PLANTS Noise regulations established by the Occupational Safety and Health administration (OSHA) are accepted by MSHA relative to caal preparation plants. Fig. 14-43 shows a graph of the time of noise exposure in hours per day to which a worker can be exposed for each A-weighted sound level. According to this graph, a worker is permitted to spend 8 hr in a 90-db noise environment, but that time must be halved when the A-weighted sound level increases 5 db. The noise dosage a worker receives is determined by the ratio of the length of time the worker spends in a particular noise environment divided by the length of time he is permitted to spend in that environment. If the worker is exposed to several different sound levels, his total dosage would be the sum of each of the individual dosages. The equation for determining the dosage is: where C is the actual duration of exposure at a given steady state noise level and T is the noise exposure limit for the level present during the time C According to MSHA regulations, the dosage, D, should not exceed one (1) for any worker for a full day of work. As an example of typical plant noise levels, vibratory screens and crushers emanate noise levels in excess of 90 db at a distance of 3 ft (0.9 m) with no material flow. With material flow, noise level increases 1 to 10 db depending

Jan 1, 1991

By Anibal Gajardo

Clays for building bricks and roofing tiles in Chile are classified as common clays and ball clays, with deposits of sedimentary and residual origin, both Cenozoic in age. Deposits are known from north to south, through 11 of the 13 Chilean Administrative Regions, 18° to 39° South latitude, and from west to east, through three of Chile's main geomorphic features, namely the Coastal Plains, Coastal Range, and Intermediate Depression. Alluvial and lacustrine sedimentary common clay deposits are located in the northern and southern Intermediate Depression. The average chemical composition of clay deposits in I and I1 Regions, is 58 percent Si02, 16 percent A1203, and 4 percent Fe203 by weight; the primary minerals are sericite, quartz, feldspar, and albite. The average chemical composition of clays in Metropolitan, VI, and VIII Regions, is 52 percent Si02, 16 percent A1203, and 6 percent Fe203 by weight; the primary minerals are montmorillonite, quartz, and plagioclase. Residual common clay deposits occur in the Intermediate Depression and in the Coastal Range internal basins, VII, VLII, and IX Regions, and they represent surficial alteration of pumice beds and crystalline rocks. The average chemical composition of clay deposits derived from crystalline rocks is 58 percent SO2, 17 percent A1203, and 9 percent Fe203 by weight; the primary minerals are sericite, quartz, and clinochlore. Clay deposits formed from pumice beds contain 47 percent Si02, 24 percent A1203, and 10 percent Fe203 by weight; the primary minerals are kaolinite, feldspar, and cristobalite. Sedimentary ball clay deposits are located in the Coastal Plains and Coastal Range, VI, VII, VIII, and IX Regions, between 34" and 39" South latitude. The average chemical composition of the ball clay deposits is 51 percent ,902, 28 percent A1203, 5 percent Fe203 by weight; the primary minerals are kaolinite, quartz, and sericite (illite?). These clay deposits supply the Chilean building sector with over one million metric tons (mt) (1.1 million short tons [st]) of material per year. The average growth rate of clay consumption during the period 1993 through 1997 was 10 percent annually. The clays are used by both mechanized plants and handcraft facilities.

Jan 1, 2001

By Leonard W. III Joseph, William H. Buttermore

Noise control is an important consideration in the design and operation of coal preparation plants. It is essential to understand and control noise sources to provide a safe environment for operating personnel. The average noise exposure levels in a typical coal preparation plant generally range between 95 and 100 db. An operator should not be exposed to noise levels of this magnitude for more than 4 and 2 hr, respectively, according to MSHA (Mine Safety and Health Administration) regulations. The major noise sources in a coal preparation plant include noise from impacting the inside surfaces of steel chutes, vibrating screens, coal crushers, pumps, motors, fans, and blowers. The magnitude of noise varies considerably from one situation to another. NOISE EXPOSURE IN COAL PREPARATION PLANTS Noise regulations established by the Occupational Safety and Health and- ministration (OSHA) are accepted by MSHA relative to coal preparation plants. Fig. 14-43 shows a graph of the time of noise exposure in hours per day to which a worker can be exposed for each A-weighted sound level. According to this graph, a worker is permitted to spend 8 hr in a 90-db noise environment, but that time must be halved when the A-weighted sound level increases 5 db. The noise dosage a worker receives is determined by the ratio of the length of time the worker spends in a particular noise environment divided by the length of time he is permitted to spend in that environment. If the worker is exposed to several different sound levels, his total dosage would be the sum of each of the individual dosages. The equation for determining the dosage is: where C is the actual duration of exposure at a given steady state noise level and T is the noise exposure limit for the level present during the time C According to MSHA regulations, the dosage, D, should not exceed one (1) for any worker for a full day of work. As an example of typical plant noise levels, vibratory screens and crushers emanate noise levels in excess of 90 db at a distance of 3 ft (0.9 m) with no material flow. With material flow, noise level increases 1 to 10 db depending

Jan 1, 1991

By R. M. Williams

Introduction Ring roller mills are efficient size reduction machines embodying the following machine functions: 1) Size Reduction: from a feed size of 2 in. to various size products as fine as 400 mesh, or granulation from 2 in. to 6 mesh containing a minimum of fines. 2) Drying: fluid bed drying of wet feed materials. 3) Conveying: negative pressure air system results in dust-free conveying. 4) Beneficiation: liberation and removal of foreign materials from the auxiliary bottom discharge simultaneously while grinding. Operation Operation of the roller mill system, Figs. 78 and 79, is completely automatic. A feeder introduces raw material into the grinding chamber in the base of the roller mill at a rate determined by pressure variations within the roller mill as material is ground and air conveyed away. The feeder will be activated by the reduced static pressure and introduce unground material into the system, thereby maintaining a constant differential pressure. Plows located ahead of each grinding roll direct the material upward and between the grinding rolls and the bull ring where it is ground to size. The grinding rolls are free to swing out centrifugally, which forces them to bear upon and grind the raw material. Being free to pivot axially, the rolls automatically assume the proper position for grinding and need no adjustment to compensate for wear. Rotation of the rolls is by rolling contact. Once ground to size, material is swept out of the mill by the controlled air flow from the centrifugal main mill fan. Air suspended, the ground material passing through the adjustable spinner separator. In the separator, an accurate size classification is made which allows product-size material to be conveyed away from the roller mill while oversize material is returned internally for additional grinding. By varying the speed of the separator drive, more or less cyclonic action is achieved at this location, effectively controlling product size. Product sized material is removed from the airstream by the cyclone collector. Typically, a conveyor or product storage bin will be located to accept the product as it exits from the bottom of the cyclone collector.

Jan 1, 1985

By William Paul Robinson

I would like to first summarize the relevant health information relating to the workers and general populations around uranium mining as a basis for understanding the hazards associated with these operations and their available remedies. This discussion will summarize the literature on Radon and its daughters, among the most toxic uranium decay products. Second, I will discuss waste handling in the uranium industry: past, present and future, discussing exploration, mining, and milling and the volumes of water and solid and gaseous wastes which are associated with these various phases of uranium operations. This paper will also include a discussion of the various past and present materials handling technologies and their responsiveness to the concern for uranium waste isolation. I will then conclude with a summary of recent modifications in the relevant standards as applied to uranium mining and milling. Joseph Wagoner, a research epidemiologist with the U.S. Public Health Service has summarized the literature on uranium mining and its health effects in his written testimony as a commissioned witness in British Columbia Royal Commission of Inquiry into Uranium Mining in January of 1980, entitled Uranium, The U.S. Experience: A Lesson in History.1 Briefly summarizinq his report, as early as 1546, miners of uranium bearing ores in Central Europe were reported to have unusually hiqh frequencies of fatal lung disease2. As early as 1879, the real nature of pulmonary disorders among these miners was first diagnosed to be malignant neoplasia or lung cancers. Of 655 miners dying between 1875 and 1912, 40% or 276 of these Central Europe miners died of lung cancer.4 By 1939, it was reported that lung cancer mortality rate for miners in these Central European mining districts was several times (9.7 per 1000) higher than that for similar populations in Vienna, Austria (0.34 per 1000). Thus, before uranium mining began in the U.S., there was a considerable body of information linking uranium mining to lung cancers. The U.S. experience can be summarized in Table 1 also from Wagoner's B.C. Testimony.1 This table shows that through 1978, 205 respiratory cancer deaths have been observed among white underground uranium miners in the

Jan 1, 1980

By R. V. Ramani

Control is a vital management function by which operations are brought into compliance with predetermined standards to achieve the goals of an enterprise. Events that are characterized by a low degree of expectation, avoidability, and intent necessarily have a low degree of control. Such events are difficult not only to predict but to control as well. Fortunately, very few industrial situations fall into that category of events. It is an axiom of control technology that in order to control, one must first measure; further to measure, one must know the characteristics of the subject (or environment) upon which the measurement must be made. Finally, if measurements are to be made reliably, the influences that affect the measurement must be known and, if possible, understood. The complete control cycle therefore consists of the following: (1) defining the objective, (2) planning to achieve the objective, (3) putting the plan into practice with appropriate instructions, (4) measuring variables or parameters of interest, (5) transmitting and transforming the measurements to analyze the system's status and to predict the future outcome, (6) comparing these with the defined objective, and (7) determining and taking corrective actions to bring the actual results closer to the objective. The management principle underlying the control cycle is the principle of management by exception. The application of the principle and the frequency with which corrective actions are taken vary according to the purposes of the review and control. For example, the control of a machine operation (e.g., truck on a haul road) may require adjustments and therefore data, analysis, and decisions, in intervals of seconds whereas the review for ore-grade control may take several hours. Reviews, on the other hand, for cost control may be done in intervals of weeks or months. In any case, three specific purposes of the control cycle are: (1) to correct the operation so that it follows the accepted plan closely, (2) to evaluate the operation and predict future outcomes in light of changes in the environment or of more experience, and (3) to review the objectives and modify these to be reasonable and realistic.

Jan 1, 1979

By T. J. Morris

"From November 2014 through September 2016, Westmoreland’s Coal Valley Mine utilized a Marion 7450 electric walking dragline to extract 1.2 million tonnes of a vertically-dipping, 52-meter wide, fault-thickened seam, beneath a conventionally-excavated pit bottom. Mine planning and operational hurdles encountered throughout a kilometer of mined strike length included mitigating highwall instability in both hanging and footwall slopes, water management, and end-of-life machine reliability and maintenance. The most substantial challenge has been the depressed global coal market. However, the successful application of this mining method significantly aided the overall cost of production at the site. The valuable experience gained from this project will be extended to future mining areas where this technique can be similarly applied. INTRODUCTION Coal Valley Mine is located approximately 220 kilometers southwest of Edmonton, Alberta, Canada, in the foothills of the Rocky Mountains. Since commercial production began in 1978, more than 84 million clean tonnes of coal has been produced and sold domestically as well as exported overseas for power generation. While the existing processing plant has a nameplate capacity of 4 million tonnes per year, the site has operated at a 2 million tonne rate since 2015 due to depressed export markets. Westmoreland acquired the mine as part of its purchase of Sherritt Coal Operations in April 2014. The mine operates 24 hours a day, 7 days a week, with an IUOE workforce of 261. GEOLOGICAL SETTING The geology of the Yellowhead Tower mining area differs significantly from previous mining areas at Coal Valley. The Mynheer coal seam discussed herein consists of steeply dipping, highly-sheared, thrust-faulted, and heterogeneous coal pods. Deep set, southwest striking thrust faults were the likely mechanism for the podding and have resulted in overturned, rolled and highly sheared seams with zone thicknesses of up to 65 meters.The hanging wall is characterized by soft bentonitic mudstones and siltstones, overlain by massive competent sandstone. The footwall is defined by a hard volcanic tuff, interbedded with thin, sporadic coal seams. The sandstone above and volcanic tuff below constrained the faulting system within this zone, enabling the mass podding that has afforded the opportunity for large-scale mining."

Jan 1, 2017

By Barbery G., A. Maachar, M. Bourassa

Laboratory testing for flotation circuit design is carried out on a routine basis in a large number of lab- oratories throughout the world. Usually a sample of ore, assumed to be characteristic of the material to be processed in a future plant, having a mass of the order of a few kilograms, is ground in a batch ball or rod mill, in the presence of water and some re- agents (for pH control, etc. .. ); after dilution to the adequate solid concentration, the resulting slurry is transferred into a laboratory batch flotation machine, having a volume which can vary from 0.5 to 8 10 -3m3. Various types of machines are in common use, manufactured by the same companies that market industrial size flotation machines. The operation of flotation in the laboratory is carried out by an experienced technician, who uses parameters such as impeller rotation speed, air flowrate addition, froth height, froth removal rate, in conjonction with reagent addition sequence, to "test" the ore. After flotation, the froth products ("concentrates"), and the solids remaining in the cell are filtered, dried, and analyzed for the various elements of interest. For flotation circuit design, a kinetic test is usually carried out, in which the froth products obtained at various times are collected to assess the time response of the ore in the laboratory machine with the combination of reagents used. Although this description is rather sketchy, it enables to outline some of the major difficulties in using laboratory data for flotation circuit design: 1. ore sample representatively 2. feed preparation procedure (laboratory compared to industrial scale) 3. laboratory procedures (type of ma- chine, type of operation, experimental errors. . . ) 4. flotation machine scale-up 5. flotation kinetic scale-up 6. flotation circuit design using laboratory data These various points will be discussed in the present paper, in order to stress the problem areas as well as possible solutions. ORE SAMPLE REPRESENTATIVITY It has been stated many times that one of the major problem in designing a flotation circuit is the representatively of the sample to be taken. Sampling of an ore body during prospection and evaluation is a specialized field, which has been progress in with the introduction of geostatistics. The application

Jan 1, 1986

By Peter Kolitsch, Galyn Rippentrop

INTRODUCTION On April 14, 1994, the joint venture of Kiewit Construction Company and Kenny Construction Company was awarded a 76 million dollar contract for the construction of the New Hampshire Avenue Tunnels in Washington D.C. The Notice to Proceed was given on May16, 1994 and scheduled completion is September 1997. This project is one of five contracts for the Mid-City E Line as part of the Washington Metropolitan Area Transit Authority (WMATA)Greenbelt Route. Once completed, the Mid-City E Line subway tunnels will connect service between the U Street-Cardozo and Fort Totten stations (See Figure 1). The New Hampshire Avenue Tunnels project consists of approximately 6800 feet of twin single track subway tunnels, three vertical shafts, associated utility work and comprehensive restoration work. Section E4b involved two methods of tunneling along the project alignment. The first method consisted of the well known soft ground open face shield driven tunnel and the second method consisted of tunnels driven using the New Austrian Tunneling Method (NATM) . The NATM section of twin tunnels begins at the Buchanan Vent Shaft and proceeds approximately 2630 feet under Rock Creek Cemetery, including the Farragut Emergency Access Shaft and connects approximately 390 feet beyond to the existing Fort Totten running tunnels (See Figure 2). Special considerations had to be given to the portion of the tunnel alignment which passed beneath Rock Creek Cemetery. The analyses and subsequent selection of the tunnel support system were based on anticipated geological conditions and the sensitive tunnel alignment. The New Hampshire Avenue Tunnels project was the second soft ground NATM project in Washington D.C. The first, by no coincidence, was completed at the adjacent Fort Totten Station and Running Tunnels Project by Mergentime/Hochtief, AJV. Currently, on a nearby WMATA jobsite, the J.F. Shea Construction Company has started a third NATM soft ground tunnel. Tunnel support systems were studied with respect to three tunneling methods: •A one-pass system consisting of a bolted precast concrete segmental lining •A two-pass system consisting of an unbolted precast concrete segmen

Jan 1, 1997

By Van E. Housman, Stephan Hoffman

Introduction Based upon the 1980 Bevill Amendment to the Resource Conservation and Recovery Act (RCRA), a 1986 Regulatory Determination decision, and subsequent rulemakings, the Environmental Protection Agency (EPA) exempted all extraction and beneficiation wastes and twenty mineral processing wastes from regulation under RCRA Subtitle C (hazardous waste) regulations. These twenty mineral processing waste streams were studied in a 1990 Mineral Processing Report to Congress. For purposes of regulatory classification, EPA made special distinctions between extraction/beneficiation and mineral processing. Wastes determined by EPA to be from the extraction/beneficiation of ores and minerals retain the exemption, while wastes found to be mineral processing, except for the “special" twenty mineral processing wastes, fall within RCRA Subtitle C jurisdiction. For those wastes that are subject to RCRA Subtitle C, § 3004(m) of RCRA requires EPA to set levels or methods of treatment, of any, which would substantially diminish the toxicity of the waste or substantially reduce the likelihood of migration of hazardous constituents from the waste so that short- term and long-term threats to human health and the environment are minimized. These treatment standards are developed by EPA under the Land Disposal Restrictions (LDR) program. Under § 3004(g) (4) of RCRA, EPA is required to promulgate treatment standards for any waste that is newly identified or listed as hazardous. As part of the settlement agreement in Environmental Defense Fund (EDF) v. Reilly and Chemical Waste Management, Inc. v. EPA (1992), EPA has agreed to propose a rule by June 30, 1995 and promulgate a final rule by June 30, 1996. This rule is commonly referred to as the "Phase IV" LDR rule and will address newly identified mineral processing wastes. Other wastes that will be addressed in this rule include newly listed dyes and pigments and wood preserving wastes. Therefore, in the Phase IV rule EPA will develop treatment standards for all mineral processing wastes that have lost their Bevill exclusion. EPA is currently collecting information on the waste characterization, treatment alternatives, and disposal capacity data currently available on these wastes. EPA is also soliciting data and information on opportunities for

Jan 1, 1995

By James Matlock

The announcement of a minable reserve of 13.6 Mt (16 million tons) averaging 0.9 g/t (0.027 oz per ton) Au and 2.4 g/t (0.71 oz per ton) Ag for the open pit-heap leach reserve at Red Mountain No. 3 in Ouray County, Colorado, by Cornucopia Resources in November 1985 brings another open pit-heap leach precious metal ore body to the production stage. With about 8.2 Mt (9 million tons) of waste and metallurgical studies showing acceptable recovery rates, low reagent consumption, and good final percentage recovery, Red Mountain is a discovery that will add to the precious metal inventory of the US. Frank Baumgaruler of Denver, CO, recognized the precious metal potential in Red Mountain No. 3 and acquired all of the old claims. James Matlock conducted a field reconnaissance over Red Mountain No. 3 independently of the Baumgartner activities and recognized epithermal alteration and mineralization in the Tertiary volcanics. He recommended acquisition of the ground and was able to obtain rights and drill six core holes for Amoco in 1982. Amoco drilled a further nine core holes in 1983, but then dropped the property. Cyrano Resources examined the data and through its consulting geologist, V.F. Hollister, acquired the rights dropped by Amoco. In 1984 Cyrano began further drilling of the ore zone demonstrated by Amoco but they were then acquired by Cornucopia Resources. Cornucopia completed development of the property and commenced the permitting process in 1986. The property was recognized as a disseminated gold deposit by both Baumgartner and Matlock, and both deserve credit for properly evaluating mineralized outcrop in the Tertiary volcanics. However, Cornucopia recognized the profit potential in the heap leach exploitation of the ores and de- serves credit for completion of premine feasibility studies. The discovery is clearly a geological one, but the premine engineering studies were essential to the conversion of the prospect to a commercial mining enterprise. The deposit lies on the circular bounding fault of the Silverton caldera. Two reprints follow that help understand the geologic setting of the ore controls.

Jan 1, 1990

By H Sohn, R. R. Fernández

Microscopic gold inclusions in sulfide minerals cannot typically be extracted by conventional cyanidation. The gold ore must be pretreated to oxidize sulfide minerals associated with gold and to remove other minerals and chemical compounds that interfere in the cyanidation leaching process. The recovery of gold from refractory sulfidic-carbonaceous ores after roasting pretreatment was studied. With the addition of an oxygen-containing gas (e.g., air or oxygen-enriched air), sulfides of iron, zinc. copper and other metals are tramformed into solid oxides or sulfates and gaseous sulfur dioxide at elevated temperatures (e.g., 400° to 800°C). When the sulfides are oxidized, individual particles lose internal volume and become porous, allowing leaching solutions access to the gold. The structural characteristics of the calcine have a strong influence on the eventual recovery of gold by cyanidation. These characteristics are strongly dependent on the roasting conditions and roasting method. The optimum combination of particle size, roasting temperature, reaction time and oxygen concentration in the off-gas was determined for a typical refractory sulfidic-carbonaceous ore from the Carlin Trend in Nevada. The tests were run using a 150-mm laboratory rotating tube furnace and 160- and 200-mm.fluid-bed pilot roasters. Laboratory results indicated that the maximum gold extraction was 92%, with the head and the leach residue containing 5.7 and 0.4 g/t (0.166 and 0.013 oz/st) Au, respectively. The maximum extraction was achieved under the following roasting conditions: a top particle size of 150 yin, a residence time of 2 hrs, a roasting temperature of 475°C and with 40% oxygen (by volume) in the off-gas. Similar results were obtained from circulating fluid bed (CFB) pilot-plant testing. The maximum gold extraction was 90%, with the head and leach residue containing of 5.1 and 0.5 g/t (0. 149 and 0.015 oz/st) Au, respective) v. These results were achieved with the same particle size and oxygen concentration as in the laboratory testing but with the roasting temperature of 500 ° to 525°C and a residence time of 30 min.

Jan 1, 2000

By Robert D. Hansen, Basil S. Fee, Richard R. Klimpel

Despite the importance of froth flotation to the mineral industries as a means of separating various minerals, the commercial flotation reagents used have varied little in the last twenty years. Numerous articles and books are available describing existing flotation chemistry and its application, e.g., Fuerstenau (1962), Fuerstenau (1976), Aplan (1980), Somasundaran (1980), King (1982), Leja (1982), Ackerman, et. al. (1984), Crozier (1984), Hansen and Klimpel (1985). There are many reasons for this lack of significant new reagent development including the general utility and relative cheapness of collectors, such as xanthates, and frothers, such as methyl isobutyl carbinol and the glycol ethers. Another important reason is the inherent complexity of the flotation process itself coupled with highly variable and difficult to standardize feed materials which make reliable reagent comparisons difficult and seriously limit the use of theoretically based studies to "predict" new or optimal reagents. In addition, the higher cost of "specialty flotation reagents demands that their performance attributes be significantly greater than existing general all- purpose commercial reagents – something often difficult to prove in practice. Faced with this situation, a detailed applications research pro- gram [Klimpel (1980 ab, 1982, 1984 ab), Klimpel, et. al. (1982)] was organized from 1979-1985 on mineral flotation with the following goals: 1) the development of appropriate batch laboratory flotation testing techniques sensitive enough and statistically reliable enough to identify small differences in performance between different flotation tests (i.e., between various reagents, even those with relatively minor chemical structural changes); 2) the identification of mathematical models with appropriate numbers and types of parameters that have maximum statistical power to statistically distinguish between various time-recovery profiles; 3) the generation of laboratory and corresponding plant scale data in sufficient quantity and consistency so that the highly interactive nature of the "flotation system9' of chemistry/ equipment/operating conditions could be quantified; and 4) the invention and development of really new and unique reagents for giving improved flotation performance. The goal #1 was achieved [Klimpel (1980b. 1984b), Meyer and Klimpel (1984)l by basically using a simple automated paddle device for consistent

Jan 1, 1986

By Suzanne Smith, Frank C. Fantauzzo

Introduction America's workforce is the heart of the nation's economy. The health of its members is a matter of national priority. Statistics show that the most common cause of job difficulties is excess use of alcohol or other drugs. Up to 75% of these troubled employees can be returned to productive careers at little expense and with great benefit to their industries. Of the 1.5 million private corporations in the US, only about 500 have alcohol treatment programs. Even fewer have drug abuse programs. It is time that the myths and prejudices surrounding alcohol and drug abuse are dispelled and help is offered. Corporations and labor unions are now finding that programs to treat these diseases benefit both the employees and the industry. The employee derives health and job security. The company sees increased productivity and decreased costs in sick pay and absenteeism. Unfortunately, three-fourths of the nation's 90.5 million workers are employed in establishments of fewer than 500 employees. In these settings, it is unlikely that either management or the unions will take the initiative in developing programs. Alcohol alone affects the health and productivity of nearly 8% of any workforce. This translates to more than 5 million employees in small business. These workers present an opportunity and a challenge. Alcohol abuse costs the nation nearly $116 billion annually. Seventy billion dollars is attributed to lost production. Medical expenditures related to alcohol are estimated to be nearly $13 billion. The National Institute on Drug Abuse (NIDA) estimates the cost of substance abuse to industry to be in excess of $4 billion a year. In addition to its economic impact, substance abuse has serious personal and social consequences. The mining industry experiences the same exposure as other industries to alcohol, drug abuse, and other employee problems. However, the existence of these problems poses special hazards because of the unique conditions found in mining. Mining has many safety and health hazards. Employees must have full control of their faculties and give full attention to the tasks at hand. Designing employee assistance programs An Employee Assistance Program is a cost-effective, confidential, early intervention system. It is designed to help employees

Jan 11, 1987

By Takeshi Tanaka, Yasuhiro Komamura, Yuusaku Tominaga, Takayoshi Iwamoto

In order to assist better countermeasures for ventilation control in normal/abnormal condition of mine ventilation network in real time, branch relation table derived from a macroscopic characteristic of ventilation network is introduced in this study. The main results in this study are as follows; 1) One of macro characteristics of a ventilation network, as a relation between airflow rates in two branches chosen arbitrarily, is specified under the change of aerodynamic resistances in a branch. Airflow rate in a branch can be estimated by airflow rate in other branch changing aerodynamic resistance by using empirical formula. The empirical formula by computer simulation of the Horonai coal mine, Japan is considered to be a one-valued function with monotone or extremums. 2) A branch relation table shows the macro characteristics, mentioned above, of all the set of two-branch combinations in a network. Elements in the table give both information of control possibility range of airflow rate and total number of extremums in an empirical formula. 3) It is important that when aerodynamic resistance change in a branch is estimated by measuring airflow rates in two typical branches, the two branches should be chosen from branch combinations with monotonous relation in the branch relation table. 4) A flexible expert system to assist ventilation control in the specified branch in real time has been developed by using a branch relation table for a ventilation transfer diagram of the specified branch, such a coal face and an advancing face. A fuzzy reasoning is utilized in the recognition of the safety factor, methane concentration, in the system. And when conviction degree in recognition for methane concentration at the specified branch is too low, the system searches for other branch combinations in the branch relation table stored in the system, to use other ventilation transfer diagram of the specified branch. When a needed ventilation transfer diagram is not stored in the system, the expert system asks automatically the ventilation simulation from other computers linked to the main computer automatically. The system repeats consultation until conviction value of safety in the specified branch approached

Jan 1, 1993

By Angela K. Braden

Igneous rock exposures occupy only a minor portion of surface area (<18 mi2) in Arkansas, and are divided into two major groups: nepheline syenite (7 mi2) and syenite complexes (8 mi2), with various dikes and sills representing the remaining surface exposures. The syenite complexes have been the sites of major vanadium and minor titanium production during the past 50 years. Nepheline syenite exposures were important in the early production of locally used building stone; however, aggregate and roofing granules have now become the principal market for the production of nepheline syenite in Arkansas. Nepheline syenite intruded into a sequence of Paleozoic sedimentary rocks in Arkansas and is exposed in two areas: in Saline County near the town of Bauxite, and in Pulaski County at Granite Mountain, just southeast of Little Rock. Although the central Arkansas region had been investigated thoroughly for bauxite by the early 1950s, the nepheline syenite resources of the region have yet to be evaluated systematically by the state. Arkansas nepheline syenite was evaluated for its ceramic uses in 1952. Some recent industry interest has revolved around its potential use as a sand-blast abrasive. The largest exposed areas of nepheline syenite, located at Granite Mountain, currently are being mined by the Minnesota Mining & Manufacturing Company (3M) and McGeorge Contracting (Granite Mountain Quarry). 3M has been in operation since 1947 and mainly produces roofing granules. A fine powder produced by 3M during crushing that is marketed under the name Donnafill? recently has seen use as filler in self-compacting confined construction and as an additive (frit) in common brick. Since the early 1960s, Granite Mountain Quarries has produced a variety of aggregates, ranging from riprap to industrial sand, and recently constructed a computerized hot-mix-asphalt production facility. Approximately 4.5 million tons and 1.2 million tons of syenite were produced from Granite Mountain and 3M, respectively, during 1979. No production values are available after this date; however, combined production from both quarries is estimated to be at least 6 million tons annually.

Jan 1, 1999