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By J. W. Leonard

Since the interpolation of exploratory data 1 can be no better than sampling procedures, a series of field experiments were conducted in an effort to determine whether hand-cut channel or core washability determinations best represent continuous miner produced run of mine coal. By obtaining a core drilled to within a few feet of channels taken from an underground face and then overmining both locations; core, channels and run-of-mine coal allocations were obtained from a common sample and all allocations were subjected to identical washability determinations. In order to compare results, basic rules2,3 previously anticipated and later published by the writer were employed. The first rule states that "For any full seam washability determination, the sulfur versus ash function for increasing cumulative specific gravity float coal fractions is linear". The second rule states that "For any full seam washability determination, the recovery versus ash function for increasing cumulative specific gravity float coal fractions is logarithmic".

Jan 1, 1988

By Sandy Worden

Coal mining companies in Australia are managing the high-consequence risks across their operations more effectively by using an interactive online risk management system known as Riskgate Developed by the Minerals Industry Safety and Health Centre (MISHC) at the University of Queensland, Australia, Riskgate contains detailed information about 11 high-consequence risk areas (called topics in the system) for opencut and underground coal mines (Table 1). The existing topics are: fires; strata control for underground mining; ground control for opencut mining; tires; isolation; collisions; explosions and explosives; manual tasks; and trips, slips and falls. Every Riskgate topic is focused on coal industry activities (mining, processing, transport and storage). The scope includes mine sites, lease areas and mine infrastructure (mobile, fixed plant, field equipment, buildings, road and rail transport), and all aspects of the mine life cycle from design through to decommissioning. The topics uniformly recognize that a loss of control can result in injury or fatality, equipment damage, production loss, reputation loss and environmental damage. However, the priority focus for Riskgate is the safety of mine personnel.

Jul 1, 2013

By D. L. Kiser

Conventional and advanced coal preparation technologies were investigated through both a literature search and through direct contact with investigators and developers. In addition to a brief description of each process, performance characteristics including feedstock type, ash and sulfur reduction, thermal energy recovery and cost are provided in a tabular form. Seven of the most commonly utilized conventional coal preparation processes, including those respectively accepting coarse, intermediate and fine coal feed, were reviewed. It was found that certain properly implemented and well maintained conventional processes were capable of better than 75 percent ash removal while recovering 90 percent or more of the inherent thermal energy. Almost 50 advanced coal preparation processes were investigated based on biological, chemical and physical principles. Physical processes investigated included cycloning, homogeneous heavy media, electrostatic, high gradient magnetic, flotation and selective coalescence. Using pulverized coal as a feedstock, some of these processes are respectively reported to be capable of removing better than 95 percent ash. 95 percent pyritic sulfur, and 50 percent organic sulfur while incurring energy losses of less than 5 percent.

Jan 1, 1986

By M. Yekeler

The critical surface tension of wetting values (Ye) of realgar (AsS), talc [Mg3si401o (OH) 2]' stibnite (Sb2S3), and sulfur (S) were determined by flotation in the absence of conventional flotation collectors as 38.7, 38.0, 35.5, and 30.0 dyne/cm, respectively. The surface tensions of flotation media were arranged by methanol. Separation of binary mixtures of these minerals was performed exploiting their Ye differences-which form the basis of the "ganuna flotation process". One step flotation test showed that sulfur floats preferentially from its mixtures with realgar and stibnite at recoveries of 73.6 and 70.7 % and grades of 81.7 and 91.2 %, respectively. The separation of stibnite from realgar gave a recovery of 4.1 % and a grade of 41.2 % for stibnite, indicate that a minimal Ye difference of 3.6±0.2 dyne/cm is essential for such separation when conventional flotation reagents are not used. This paper presents data and describes the approach employed in these separations.

Jan 1, 1994

By A. Lashgari, V. Kecojevic

This paper presents research on the environmental impact of digging and loading equipment used in surface coal mining. Environmental impact was assessed through the measurement of equipment exhaust and dust emissions, and sound level. In this study, exhaust emission refers to carbon dioxide (CO2), carbon monoxide (CO), nitrogen oxides (NOx), sulfur oxides (SOx) and volatile organic compounds (VOCs). Dust generation refers to fine particles (PM2.5), inhalable particles (PM10) and total suspended particulate matter (TSP). Sound level refers to the sound pressure level at different distances from the equipment. Modeling of the environmental impact of digging and loading equipment was conducted using the Microsoft Visual Studio.NET software package. This research was a part of a broader project involving the development of a software system for the selection of productive, cost-efficient and ecofriendly mining systems, sponsored by the Appalachian Research Initiatives for Environmental Sciences (ARIES). This research may assist mining professionals in quantifying the environmental impact of digging and loading equipment, and developing strategies for reducing the overall impact of such equipment in surface mining.

Jan 1, 2013

By J. M. Scharer, Bruce E. Halbert, Pettit. Carol M., Lysane Bolduc

The ratio of neutralization potential (NP) to acid production (AP) ratio is often employed for predicting acidic discharges from waste rock dumps. The available NP was evaluated in laboratory studies of limestone dissolution in simulated acidic mine water. The available neutralization potential strongly depended on the particle size. Using limestone particles of 114" (6.4 mm) or greater, less than 20% of the total neutralization potential was exhausted at the onset of acid conditions. Apparently, the dissolution of limestone became mass transfer limited. Under mass transfer limitations, the rate of pyrite oxidation may exceed the rate of neutralization by buffering minerals. The implications concerning the controls on limestone dissolution were examined using a geochemical predictive model for sulphide mineral oxidation in waste rock. The results have shown that in case of heterogeneous waste rock piles the NP/AP ratio is a reliable indicator for short-tam predictions only. Kinetic data on the depletion rate of the neutralizing minerals and geochemical modelling suggest that waste rock environments with NP/AP ratios as high as 5.0 may turn acidic in the long term.

Jan 1, 2000

By James T. Curry

The steady growth of the Northwest portion of the United States over the past two decades, and the very rapid development of Northern California, Western Nevada, and Oregon in particular, led the Calaveras Cement Company people to Shasta County, California in 1957. The presence of a large deposit of high calcium carbonate limestone had been recognized for many years, but it required the momentum of an expanding economy to make these long known reserves valuable. This, plus the availability of a reliable supply of fuel in the form of natural gas, and the ready means of shipping the product to the consumer both by highway and railroad, seemed to offer the proper combination to launch a successful venture. The Calaveras Cement Company had been manufacturing cement by the wet process since 1925 at their plant at San Andreas, California. Starting with two small kilns, the plant in Calaveras County started an expansion program in 1945 that ultimately resulted in the plant as it exists today, consisting of five kilns with a combined production of 4.5 million barrels annually.

Jan 1, 1967

By Andrew McGrath, Geraldine Lyons, Sarah Barcelona

In the dynamic and challenging modern industry landscape, understanding and unleashing the true role and contribution of technical teams is crucial to business success. The cyclical nature of industries has led to shifts in the technical professional’s place within the organization and the technical skills that are desired most. This paper reframes the pivotal role that technical professionals play within complex operating assets to maximize value and realize full potential. This investigation focuses on the Rio Tinto Kennecott Technical group’s cultural journey, which is underpinned by an investment in its people. The conflict between legacy industry beliefs and the necessity for cultural change emerges. This is illustrated by a deep dive into the evolving case study of Kennecott’s Bingham Canyon Open Pit Mine Technical team. Here, a multi-faceted approach to cultural change is helping to unlock the team’s contribution to the life extension of an aging asset. Guided by a vision and strategic roadmap, this approach is part way through a 5-year implementation period and is yielding encouraging business outcomes.

Feb 1, 2024

By M. G. Premo

The McKinley Mine is located in the northwest New Mexico, in McKinley County, approximately 25 miles from Gallup. The mine is operated by The Pittsburg & Midway Coal Mining Co. (P&M), a wholly owned subsidiary of the Chevron Corporation. P&M is headquartered in Englewood, Colorado. Since the McKinley Mine began operations in 1962 a total of 83,391,000 metric tons of coal have been sold through 1990. The 1991 production was approximately 5.000.000 metric tons. The mine operations are contained on a 109.000 square kilometers lease area of which 44.000 square kilometers are on the Navajo Nation. The present customer base consists of four utilities and one industrial account, all of which are located in Arizona. The utility customers are the Arizona Public Service Co. Cholla Station at Joseph City, The Salt River Project. Coronado Generating Station near Joseph City, and The Tucson Electric Company, Irvington Generating Station in Tucson. The industrial customer is the Stone Container Corporation, Snowflake Paper Mill.

Jan 1, 1992

By Leo Gentile, David Selhorst

The $528 million Toledo Waterways Initiative (TWI) was implemented by the City of Toledo in 2002 and completed in August 2020. Toledo is one of many US cities required to implement a Long-Term Control Plan (LTCP) but one of few to have completed its plan. TWI consists of three storage and conveyance tunnels, four below grade storage basins ranging from 4 to 36 million gallons (MG), miles of sewer separation and interceptor improvements, green infrastructure and other appurtenant structures to dramatically reduce combined sewer overflows to the Maumee River, Ottawa River and Swan Creek. All three rivers flow into Lake Erie. The City’s 180-year history as a Midwest shipping, manufacturing and transportation hub provided design engineers and contractors no shortage of unknown underground challenges to complete the projects. The City will begin its 5-year Post-Construction Compliance Monitoring in 2021 to satisfy the final LTCP requirement. A program overview and experience from tunnel and underground basin construction in urban areas with buried active and legacy infrastructure will be discussed.

Jun 13, 2021

By R. J. Wahrer

In 1996, the Office of Surface Mining (OSM) and the U.S. Fish and Wildlife Service (FWS) completed an Endangered Species Act (ESA) programmatic Section 7 consultation. From the resultant Biological Opinion, it was found that coal mining operations conducted under federally approved state regulatory programs would not likely jeopardize the continuation of federally listed species nor result in the destruction or adverse modification of critical habitats. The requirements of the ESA and their integration into the SMCRA permitting process and the responsibilities of the regulatory agency, the FWS and the coal operator will be discussed. Guidance on the development of protection and enhancement plans will be provided and site-specific examples given.

Jan 1, 2003

By R. G. Church

Belle Ayr Mine was established in 1972 as the first large surface coal mine in the Powder River Basin of Wyoming. During the mid-1980s, it was eventually out-distanced in productivity by newer mines, and management recognized that the mine must recapitalize its major mining equipment and enhance its workforce flexibility in order to be competitive in the deteriorating market situation. Therefore, state-of-the-art haulage and loading equipment was placed into service, and a 12-hour rotating shift and a technician-based workforce was implemented. Belle Ayr Mine is located 29 km (18 miles) southeast of Gillette, Wyoming, in Campbell County (Figure 1). The mine is a part of AMAX Coal West, Inc., and with its sister mine, Eagle Butte, located 8 km (5 miles) north of Gillette, is a major contributor to the overall coal production of AMAX Coal Industries, Inc., headquartered in Houston, Texas. This paper addresses mine planning, recapitalization initiatives, and innovative workforce changes which propelled this large, surface coal mine to the forefront of productivity in the ever tightening low sulphur coal market.

Jan 1, 1994

By Kerby Glass, Glenn A. Gruber

Mr. C. A. Hollingsworth introduced commercial column flotation to the Florida Phosphate Industry in 1976, with a six feet diameter prototype cell at the Tenoroc Mine. More than two-dozen column cells have been installed in phosphate beneficiation plants since then. The increased interest in column cells for phosphate flotation, and their potential use in new plant construction, prompted the Florida Institute of Phosphate Research to fund programs to investigate various aspects of column flotation. This report describes a test program, conducted by JACOBS at CF Industries Hardee Complex II, as part of a comprehensive research program awarded to the University of Florida by the Florida Institute of Phosphate Research. The 1.5 feet diameter test column was operated with plant process water and plant reagentized flotation feed. Several variables considered for column cells design and operation were tested. Feed specific capacity, air superficial velocity, and the length to diameter ratio of the column were the variables that influenced phosphate recovery. Concentrate phosphate grade was influenced by concentrate superficial velocity and feed specific capacity.

Jan 1, 2002

By Ted T. Biddle

The world energy crisis has created a greatly expanded exploration program for energy fuels. The demand for materials required for drilling operations such as barite, which is the primary component of drilling fluids, has increased proportionally. As in the case of many other minerals, existing high grade barite mines are no longer capable of producing the required tonnage. Consequently, exploration and development of lower grade ore bodies has been increased. The need to produce a high quality product at maximum recovery rates, along with the ever changing economics affecting both selling price and production costs has triggered accelerated research programs toward more sophisticated and efficient beneficiation methods. Taking into account the specific gravity differential between barite (4.5) and the normal gangue minerals such as silica and calcite (2.7), gravity concentration methods are the prime consideration with flotation as a scavenging process. Greater emphasis on particle size liberation, size reduction and concentration is also indicated. In order to accomplish these objectives, it has been necessary to revert back to the old adage, "Recover your minerals as soon as they are free."

Jan 1, 1980

By Janusz S. Laskowski

Studies carried out over the last 10 years reveal that precipitating particles which may appear in alkaline solutions of long-chain amines and in acidic solutions of fatty acids exhibit clear isoelectric points around pH 10.6-1 1 for dodecylamine and around pH 2.5-3 for fatty acids. These colloidal species can accumulate at solid/liquid and liquid/gas interfaces and affect flotation. While the precipitate in solutions of fatty acids apparently can chemically interact with the mineral surfaces and is flotation-active if sufficiently long conditioning time is available, the cationic flotation of quartz in alkaline solutions is depressed by the colloidal precipitate. The experimental data available in literature on the adsorption, electrokinetic, contact angle and surface forces measurements in the solutions of the weak electrolyte collectors are analyzed and the role played by the precipitate is discussed. It is shown that these concepts allow for an explanation of the selective flotation of sylvite from halite with long-chain amines in potash ore flotation.

Jan 1, 1999

By Merrill P. Allen

The Vernal phosphate rock concentrator is located in the Uinta Mountains near Vernal, Utah. Ore is sedimentary rock from the Phosphoria Formation. Truck and shovel mining is done at a rate of 11,500 TPD. Run of mine ore is crushed and then milled through a SAG mill and ball mill to minus 16 mesh. Milled ore is deslimed using cyclones and hydrosizers. Sands are conditioned with fatty acid, petroleum sulfonate, diesel fuel and frother prior to primary rougher and cleaner flotation. Primary flotation tailing is milled to 95% minus 48 mesh, deslimed in cyclones, conditioned using reagents previously described, and then processed through rougher and cleaner scavenger flotation. Product of scavenger cleaner concentrate is upgraded by reverse flotation of dolomite. Flotation concentrates are combined and dewatered, pulp being milled to 99.5% minus 65 mesh and then thickened to 65% solids. Product is pumped from storage through a 10 inch, 94 mile pipeline to a conversion plant at Rock Springs, Wyoming. Mill tailing is stored behind an earthen dam, water from the settled tailing being reclaimed for mill use.

Jan 1, 1993

By Bill Dershowitz

Consider a deep gold orebody with grade of 4 g/t (0.11 oz/st). At the time of this writing, with gold prices at historic highs, it could be a good, but not great, prospect. But if it is a vein deposit, and those veins are 200 g/t (5.8 oz/st), it would be significantly more attractive if there was a way to produce directly from those veins, leaving the rest of the rock in place. [Figure 1 The red around each of the four injector wells shows areas of high pressure, where the lixiviant fluid is pumped into the rock mass, with orange and yellow indicating dissipated pressure. The black lines indicate some of the fracture pathways through which the lixiviant, with absorbed metal, flows toward the central recovery well where low pressure is indicated in blue. Lixiviant is pumped out through the recovery well. Image courtesy of Golder Associates.] There is a way to do this, in situ leach (ISL) or solution mining. It has been a viable commercial technology for more than five decades.

Jan 1, 2011

By W. Stark

Many developing countries with little or no previous environmental regulation are now promulgating air quality regulations which require facilities to demonstrate compliance with both process parameter based emission limits and ambient air quality standards. For many companies with operations in developing countries, an air quality compliance program at the facility level is lacking and these companies have very little background information to work with in developing a program for assessing and maintaining compliance. This paper will present a methodology for development of a comprehensive air quality compliance program for operations located in developing countries with new environmental regulations. The experiences of the authors in developing an air quality compliance program for a mining operation located in South America will be used as a basis. A program for meeting new air quality requirements can be developed in seven steps. The seven steps are: (1) regulatory review and project scope; (2) design and implementation of a baseline air quality monitoring program; (3) site visit, (4) development of a complete air emission inventory; (5) dispersion modeling; (6) compliance analysis and compliance plan; and (7) project completion.

Jan 1, 1998

By B. J. Arnold, F. F. Aplan

Prior laboratory work has demonstrated that much of the fine ash forming minerals entering a flotation froth are there as a result of water carryover- from the bulk contents of the flotation cell (Arnold and Aplan, 1986a). Using a bank of four 8.5 m3 (300 cu ft) Wemco flotation cells cleaning a well-liberated Lower Kittanning seam coal, test results show that the sulfur and ash content of the froth is directly related to the water content of the froth (or inversely related to the percent solids in the froth). Reagent changes that result in a watery froth produce a higher ash content in the froth. A direct comparison of laboratory and plant results show that the standard laboratory flotation test produces a product higher in sulfur and ash than that produced in the plant. Caution should be exercised when extrapolating laboratory test results to the plant situation. A method of estimating coal flotation product quality in the plant based on laboratory tests is given.

Jan 1, 1991

By B. Moudgil, Hassen El-Shall

Particle shape and size distributions are among the most important parameters that affect the filtration efficiency of phosphogypsum in wet- process phosphoric acid production. Cost-effective enhancement in filtration rate is desired by phosphoric acid producers for higher plant capacity and lower operating costs. In this regard, numerous research efforts have been carried out in different laboratories as well as in pilot and plant testing. Nevertheless, changes in phosphogypsum crystal shape and size distribution deserve special attention. In this study, the results obtained in the presence of Crysmod and Hiflo-S5 surfactants are discussed. The influence of such additives on crystal morphology and size distribution are studied under different sulfate contents (supersaturation). The obtained data are correlated with process efficiency parameters such as filtration rate, digestion of rock, and recovery of phosphate values. Up to 60% increase in filtration rate is obtained. In addition, an increase in digestion efficiency and P205 recovery is achieved due to addition of surface active agents. The observed beneficial effects are explained in the light of the changes induced in crystal habit, size, and size distribution.

Jan 1, 1999