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By P. D. Rao, D. E. Walsh, W. W. McClintock

A column flotation system was designed to conduct release analyses on a very finely disseminated, stratiform copper ore from the Denali Copper Prospect in Alaska. Chalcopyrite is finely disseminated in a carbonate matrix, and pyrite is disseminated in both the chalcopyrite and the gangue. Grinding to -20 µm is required for adequate liberation. A 25-mm x 2.4-m glass flotation column was designed. The ore and its flotation tailings were repeatedly floated to obtain a rougher concentrate. The rougher concentrate was then repeatedly floated to produce release fractions. These fractions were analyzed for copper, iron, calcium and magnesium, and release curves were plotted. The procedure was replicated at each of two grinds, i.e., 99% and 88% passing 37 µm (400 mesh). The procedure should find application for flotation characterization and process selection. Bond grindability testing was also conducted.

Jan 1, 1996

By P. C. O. Chukabarah

Atkinson's resistance square law is the cornerstone equation for traditional expression of energy losses in mine ventilation engineering. But the nomenclature for the various forms of energy losses are often confused for one another, misapplied or misinterpreted. These forms of energy were re-examined from thermodynamic and fluid-dynamic perspectives. Resultant expressions showed that both incompressible and compressible flow regimes in underground mines can easily be accommodated. Given the well-known three major energy forms, which are equivalent to one another but numerically unequal, corresponding equations to Atkinson's (pressure loss) for headloss and workloss were derived. The thermodynamic weight relational resistance ([w] s2/m5) associated with energy per unit weight (headloss) was dimensionalized for the first time. Also, normalized Atkinson-like equations for headlosses and worklosses were derived to ease direct computations in mine ventilation practice.

Jan 1, 1995

By Wayne A. Sadik

The mine ventilation system of the Henderson Mine provides a case study of designing and maintaining high-quality respirable air in a large underground mine with over 200 units of diesel-powered equipment. This system was designed with concern for minimizing exposure to personnel of siliceous dust, diesel exhaust, smoke, and potential fire hazards while optimizing general environmental air quality throughout the multilevel/multiheading operation. As a relatively new operation, the Henderson Mine incorporates a modern ventilating plant and mine de- sign as well as state-of-the-art technology where appropriate. Two main ventilation shafts approximately 2,300 ft (701 m) in depth (one intake, one exhaust) will handle 1.8 million cfm (850 m3/s) of air circulated throughout 60 miles (97 km) of drifting, providing the ventilation requirements for more than 25,000 diesel horsepower (18,642 kw) underground.

Jan 1, 1980

By D. Tao

More than 80 million metric tons of fly ash is produced annually in the U.S. as coal combustion by-product. Fly ash can be converted to value-added products if unburned carbon is reduced to less than 2.5%. However, most of fly ash is currently landfilled as waste due to lack of efficient purification technologies to separate unburned carbon from fly ash. A rotary triboelectrostatic separator has been developed and patented recently at the University of Kentucky with unique features. Several fly ash samples have been used to understand the effects of major process parameters on the separation performance. The results show that compared to existing triboelectrostatic separators, the rotary triboelectrostatic separator has significant advantages in particle charging efficiency, solids throughput, separation efficiency, applicable particle size range. Key words: Coal, Combustion Waste; Fly Ash; Particle charging; Separation.

Jan 1, 2008

By Kadri Dagdelen, M. Waqar Asad

Cement production involves the processing of raw materials that contain - Si02, A1203, Fe203, CaO, MgO, LOI (loss of ignition), S03, K20, Na2O, Ti02, P2055 and Cl- to produce the synthetic mineral mixture called "clinker". The use of other additives - sandstone, flyash, iron ore, and clay - is also mandatory in order to achieve the optimum blending requirements of cement. However, the use of these additives needs to be minimized due to their significantly higher costs ($/Ton). This paper presents a mixed integer programming (MIP)-based optimum quarry scheduling algorithm, which is used to generate quarry plans, satisfying geometric and production capacity constraints while providing minimum cost/optimum blend of raw materials mix to a cement plant. The benefits of this new methodology are demonstrated on a case study.

Jan 1, 2002

By D. A. Poulter

The stability of a liner system is influenced by many factors which can be compiled into four basic groups. They are: 1. the liner system components and physical characteristics; 2. the geometry and slope of the liner system; 3. the loading conditions on the liner system; and 4. the foundation conditions under the liner system. Failures in the liner system that are due to one or more factors from the first three groups usually result in movement relative to the plans of the liner system. Failures associated with factors in the fourth group result in deformation(s) across the liner system section beyond its design limits. For purposes of these discussions a failure in the liner system refers to displacements or movements resulting in physical damage to the liner system such that it can no longer function.

Jan 1, 1995

By Carl-Henrik Knudsen, Rolf Tore Arnesen, Eigil R. Iversen

Recovery of iron and copper from acid mine drainage was studied in pilot scale at a continuous treatment plant at the mine site of the King's mine in Roeros, Norway. The average load on the plant was 1 m3/h. The process tested in this project is a three-step process consisting of: 1) Fe(OH)3 precipitation at pH 3.5, dewatering of iron sludge and transport to ferric chloride plant; 2) after filtration precipitation of residual metals at pH 9, concentration of metal sludge by flotation; 3) extraction of metals from the sludge with sulphuric acid followed by recovery of copper by electrolysis. The copper could be used for local production of different crafts, but this condition needs a further evaluation. The process economy at a full scale plant is evaluated.

Jan 1, 2000

By D. M. Cregger, J. L. Rosenblad, R. E. Ranken

The construction of a large span, high-walled underground opening in a low strength shale rock is unprecedented. The feasibility of constructing a pumped storage project with several tunnels and a large underground powerhouse in low strength shale rested largely on the feasibility of building stable openings large enough to accommodate the required equipment. Because of the lack of experience with large openings in shale, the decision was made to excavate a test adit and test chamber and conduct a multi-faceted geotechnical evaluation program designed to yield pertinent in-situ data on the ability of the shale to accommodate a large underground opening. Factors considered in the shape, size, orientation, and location of the test chamber were: (1) similarity to the anticipated powerhouse chamber, (2) nature of the most important data to be obtained, (3) feasibility of construction, and (4) economics.

Jan 1, 1983

By R. L. Beatty

The Bond International Gold (BIG) Colosseum Gold Mine was discovered in 1865, but no recorded production occurred until the 1930's, with production approximately 19k9 (615 oz) of gold. The mine was closed in 1942 as a non-essential industry during World War II. The property was acquired by Dallhold Resources in mid 1986. Construction of a 1.1 million Mt carbon-in-pulp, cyanide mill started in November, 1986, and was completed in September, 1987. Minable reserves are estimated to be 9,560,831Mt (10,539,000St), with an average grade of 2.1 g/Mt (0.062 oz/st). This paper describes a general view of process flow and plant equipment, as well as a look at the maintenance and operational problems encountered in the fist six months of operation.

Jan 1, 1989

By Jeff Schwoebel, Arcy, D&apos Horner

The Deep Coal Seam Project is a multi- year, large-scale research and development effort between the Gas Research Institute (GRI) and Resource Enterprises, Inc. (REI). The project is being conducted at the Red Mountain Site, a multi-well test site located in the southeastern portion of the Piceance Basin near Collbran in Mesa County, Colorado. The project objective is to develop the drilling, reservoir evaluation, completion and production technology required to produce gas from a thick, deeply buried coal seam. To understand the parameters controlling gas production, project efforts are focused on the Cameo "D" coal reservoir which lies at a depth of about 1707 m (5,600 ft) at the test site. This paper overviews the drilling, testing, completion, and production techniques used on the 1, 2 and 3 Deep Seam wells and implications for resource development.

Jan 1, 1987

By B. Strickland

The decision to accelerate development of Stillwater Mining's East Boulder Mine was made in March of 1998. It required the completion of conceptual designs by July of 1998. This was accomplished through teamwork and close cooperation of mine personnel, engineering firms and vendors, all working toward the common goal of developing an efficient and workable design. Early in the project, representatives of Stillwater Mining, Kilborn International, Parsons Brinckerhoff Transit and Rail Systems, Continental Conveyor, and H.A. Simons met to develop methods to bring the mine into production at a highly accelerated rate and to solve potential bottlenecks, including the movement of personnel, materials, and muck through a 5.6 km (3-1/2 mile) adit. This interaction, including companies not normally associated with the mining industry, led to innovative approaches and designs produced by Kilborn Engineering and Stillwater Mining.

Jan 1, 1999

By D. L. McClure

Gold mineralization at the Colosseum Mine is submicroscopic and associated with pyrite. Pyrite occurs in breccia clasts, replacing dolomite, in crackle breccia veinlets with traces of quartz, and as disseminations in two small, interconnected intrusive pipe complexes of rhyolitic felsite and breccias of felsite and wall/country rock. Breccia types grade from felsite plus wall rock of Pre-cambrian gneiss to cross-cutting breccias "of felsite, gneiss, and Paleozoic sedimentary rocks that are in contact with the Precambrian gneiss terrane one-quarter mile (40Om) southwest of the Colosseum pipes. Mineable reserves are estimated to be 8 million short tons (7.3 million metric tons) at 0.074 troy ounces of gold per short ton (2.3 g/metric ton) at a cutoff of 0.03 troy ounces of gold per short ton (1.0 g/metric ton).

Jan 1, 1988

By M. Schultz

The cost of remediation often drives the selection of the preferred remedial alternative at hazardous waste sites. The use of probabilistic cost/risk analyses can aid in predicting costs of remedial alternatives. Three types of information are discussed in performing cost/risk analyses: (1) data on the quantity of contamination versus the contaminant concentration; (2) unit costs of remediation for the remedial alternatives; and (3) risk to contaminant concentration relationships. Cost/risk evaluations are performed on a site-by-site basis, to account for combined risks of different contaminants and differences in quantity to be remediated versus contaminant concentration. The cost/risk analysis produces a graph of risk versus cost for each of the remedial alternatives. These costs are then compared to facilitate selection of a preferred alternative. An example of comparison of alternatives is illustrated for a historic coal gasification site.

Jan 1, 1992

By I. K. Gilmore

PCS Phosphate operates an open-pit phosphate mine in the central coastal plane of North Carolina. The company has mining and refining facilities located on the south shore of the Pamlico River. Phosphate ore is recovered at the Aurora facility by open-cast mining techniques. Walking draglines and bucketwheel excavators remove the overburden and mine the phosphate ore. The mined ore is slurried about 8 km (5 miles) to the processing plant. At the plant, the phosphate ore slurry is passed through screens to remove material coarser than 2 mm (10 mesh) and then pumped through hydrocyclones to remove material finer than 75 mm (200 mesh). The resulting phosphate and sand mixture is treated with various reagents and subjected to an anionic flotation process. A cationic flotation process removes the sand from the final phosphate concentrate.

Jan 1, 1995

By D. S. Kostick

Soda ash production in the United States during 1994 increased 4%, reaching 9.3 Mt (10.2 million st). That was the second highest production year. Domestic nameplate soda ash capacity is about 11 Mt (12 million st). Overall, the industry operated at about 85% of capacity. Some companies produced at 100% of capacity while others produced at below their design ratings. Although domestic soda ash consumption was slow during the first half of the year, third- and fourth-quarter sales increased, especially in the flat¬glass and fiberglass sectors. These two sectors increased because of greater demand for glass products in the automotive and construction industries. Soda ash sold for pulp caustic soda increased during 1994. This was due to higher prices for and reduced availability of electrolytic caustic soda. It is often preferred for pulp digestion because of its stronger alkalinity.

Jan 1, 1995

By L. J. Prosser, A. T. Iannacchione

From 1991 through 1995, 44 miners out of a total workforce of less than 2,000 were fatally injured in the stone industry. Of these, 12 occurred at underground mining operations with nine deaths resulting from roof or rib falls. A safer environment can be achieved by evaluating the nature of the hazardous ground and by developing more efficient and effective ground-control strategies. Roof and rib conditions were observed and assessed in 33 underground stone mines in Illinois, Indiana, Kentucky, Maryland, Missouri, Pennsylvania and West Virginia (Fig. 1). Hazard assessment indicated that the ground failures that occurred under moderate to substantial overburden, i.e., >30 m (100 ft), were caused by stress concentrations and geologic structures. Ground failures near the surface are caused by solution (water) processes. Selection of the mining horizon and mine-layout decisions

Jan 1, 1999

By T. E. Garnar

Heavy mineral mining has been a small, but important Florida industry over the past sixty years. Early geologic history of each deposit is similar up to point of deposition in alluvium, deltaic sediments, or along shorelines. Later geological development through reworking and concentration is different for each deposit. The Trail Ridge deposit was formed by reworking Citronelle sediments of the Lake Wales ridge. Post depositional leaching of iron from ilmenite makes Trail Ridge an important source of titanium minerals for TiO2 pigment manufacture. Research leading to the separation and sale of by-product heavy minerals from Florida deposits has been important in maximizing profitability. Advances in mineral dressing technology will lead to future mining of lower grade reserves. Future needs for heavy minerals seem certain to expand, with increased activity in exploration and development of mining operations.

Jan 1, 1972

By J. West-Hansen

The problem of long-term production scheduling in an underground coal mine is approached through the concepts of sequencing theory. Based on a typical layout of mining sections, the principles for the approach are: 1. The definition of mining sections as jobs, and mining methods as machines. 2. The reduction of the overall mining activity to the general problem of nonpreemptive scheduling of precedence related jobs on parallel machines. 3. The simplification of the layout to a general type directed network with the nodes representing jobs and the arcs representing precedence relations. 4. The determination of a feasible and near-optimal job schedule given the objective of maximizing the total net present value of the jobs. A general scheduling heuristic is being developed for implementation on an IBM personal computer (PC) as part of an interactive computer system for long-term production planning.

Jan 1, 1986

By F. Ferella

In this paper several leaching tests were per-formed to optimize the leaching section of a hydrometallurgical process for the recycling of alkaline and zinc-carbon batteries. Zinc and manganese oxides were dissolved by an acidic-reductive leaching using sulphuric acid and oxalic acid as reductant. Leaching tests were developed according to a full factorial design. The operational variables were pulp percentage, sulphuric acid concentration, temperature and oxalic acid concentration. Additional tests were performed to evaluate the precipitation rate of Mn and Zn oxalates. Finally a hydrometallurgical process were proposed for the recycling of alkaline and zinc-carbon batteries, in which Zn and MnO2 are recovered from purified solution by electrowinning: Zn is recovered as metallic compound, while Mn can be recovered as electrolytic manganese dioxide (EMD), but recovery of further manganese compounds is possible with simple process changes.

Jan 1, 2006

By V. K. Gupta

A detailed experimental study of the variations in grinding rate with particle size, particle load, ball diameter, ball load, mill diameter, and mill speed was carried out for a soft cement clinker and a hard cement clinker. The effects of the ball diameter, ball load, and particle load were observed to be material (hardness) independent, and those of the particle size, mill diameter, and mill speed to be material dependent. A sharp change in grinding behavior was observed for both the clinkers at about 150 µm size. Below this critical size: (1) the hardness difference between the two clinkers became insignificant, (2) variation in the grinding rate with particle size became markedly more pronounced, and (3) mill speed had little or no effect on grinding rate. The importance of these results in the context of process optimization and control is discussed.

Jan 1, 1988