Search Documents

By Olice C. Carter, B. J. Scheiner

The Bureau of Mines investigated the removal of two toxic/heavy metals (cadmium (Cd) and lead (Pb)) from brass foundry wastewater. Polymers, copolymers, guars, and gums were used in conjunction with calcium hydroxide (Ca(OH)2) and magnesium oxide (MgO) to remove the metals from solution. Several polymers were successful in removing Cd and Pb from the wastewater. The concentrations of Cd and Pb were lowered from 19 to 0.01 ppm and from 20 to less than 0.01 ppm, respectively. The methods investigated could easily be adapted to many existing wastewater treatment facilities and/or be used independently.

Jan 1, 1991

By C. DeRossett, K. F. Unrug

Sedimentary rock fractures commonly occur in the vicinity of outcrops. Mine highwalls and highway cuts provide excellent views of these near-surface joint systems. This paper explains the origin, characterization, distribution and extent of the these joint systems with reference to the lithologic composition of the rocks. The practical implications of these joint systems on the operation of a mine are described. Included are discussions of the discontinuous deformation that results from surface subsidence, the stability of mine portals and near-outcrop underground operations, and the stability of highwalls when using highwall miners and strip operations. Some design procedures are recommended to minimize the problems encountered within mining areas having intense joint systems.

Jan 1, 1996

By Merwin Bernstein

Peru has been an important source of metals since Aug. 29, 1533. On that day Francisco Pizarro took charge of the 24 t (772,000 oz) of gold and silver that constituted Atahualpa’s ransom. At today’s prices, the value of that booty ranges between $100 and $150 million, depending on the proportion of gold to silver. Since then, Peru’s silver and gold production has been legendary. Current mine production Most of Peru’s metals are mined from the Andes Mountains and its foot-hills. The Andes run the length of the country parallel to the Pacific coastline from Ecuador to Chile, a distance of nearly 3000 km (I 875 miles). They are about 300 km (187 miles) wide and much of the range is more than 3000 m (9900 ft) in elevation. High plateaus (altiplanos) occupy a large part of the range. Both flanks are rutted by large valleys and canyons. Many of these peaks are prodigious. which make road building expensive and adds to the cost of mining.

Jan 1, 1993

By Joe Scheuering, Don Poulter, John Trirnble

Closure of the Grey Eagle Mine tailings impoundment is an example of closing a "wet" tailings impoundment at the cessation of milling operations. This paper presents a summary of tailings cover design and construction, tailings deposition sequences to facilitate closure, construction schedules, costs, and post-closure monitoring. Permit requirements which influenced the design and construction of the tailings are summarized. The performance of the cover and post-closure monitoring issues are also discussed.

Jan 1, 1995

By N. S. Harding, M. C. Mai, A. G. Fonseca

Many coal characteristics affect combustion performance. Mill wear, boiler efficiency and derate, slagging, fouling, and ash collection and removal are only a few of the impacts of coal quality on boiler performance. The ability to assess fuel characteristic impacts on busbar costs is essential, although difficult to obtain. The relationships between coal characteristics and ignitability, operability, slagging, and fouling were investigated. The examination of combustion data/performance from a laboratory study, a boiler simulation system (pilot combustor), and commercial boilers indicated the benefits of burning improved quality coal. The specific effects of cleaning are discussed. A validation of the necessity of commercial-scale and/or pilot-scale testing is presented.

Jan 1, 1988

By Daniel Hodouin, Antoine Berton

Mineral processing plants are monitored and controlled using measurements that are usually processed by on-line material balance calculation techniques. However, gross errors, due to sensor biases or failures, may corrupt all the process variable estimates. On-line gross error detection methods are required to ensure efficient mass balance evaluation. In the proposed approach, material imbalances and raw measurement corrections are tested by statistical techniques designed to detect and isolate sensor problems.

Jan 1, 2000

By R. W. Hughes, R. Koopmans

This paper investigates the effect of varying stress levels on the determination of deformation moduli and examines the sensitivity of the borehole dilatometer in measuring rock mass scale features and its ability to represent rock mass characteristics. Cubical blocks of sandstone, limestone and granite were tested in the laboratory under triaxial stress conditions. Field programs were conducted in both granite and sandstone rock masses surrounding underground openings. The dilatometer's zone of influence was determined by conducting tests within an instrumented concrete cylinder and by performing a finite element analysis. Laboratory and field results suggest that the deformation modulus of a rock mass can be substantially affected by the stress field and that the borehole dilatometer is sensitive enough to profile deformation moduli as dictated by the in situ rock mass characteristics.

Jan 1, 1986

By Lawrence J. Connelly

During the last decade, use of freeze conditioning agents (FCA) to ease unloading and handling of both run-of-mine and washed coal during periods of cold weather has become an accepted practice by the coal industry. This paper reviews some of the mechanical means of easing the handling of coal during periods of cold weather, as well as their use in conjunction with FCA's. Factors required to promote a successful cold weather handling program are also covered. Mechanisms by which FCA's function and the influence of various substrate characteristics on the ultimate response to freeze conditioning agent performance are discussed. A modified approach to freeze conditioning is presented.

Jan 1, 1986

By N. Lydakis ? Simantiris

Preliminary results of a mineralogical, geo-chemical and nutrient analysis of soil samples collected from Omalos polje-plateau are presented. This study is part of a project concerning the relationship of lithology and mineralogy characteristics of soils of different geological origin from the island of Crete with their chemical composition, and more specifically with their ionic nutrients content. The results presented in this work show a relatively good correlation of the mineralogy and the bulk content of the soils examined with the available nutrients in soil solution.

Jan 1, 2005

By Klaus Schönert

Theories are proposed to explain consistently a class of phenomena and are established with experiences, hypotheses, and laws. Not all concepts need to be presented in a mathematical format. A comminution theory must incorporate fracture physics, particle breakage, stressing events in crushers and mills, material transport, comminution kinetics and models, etc. In this paper the state of knowledge of some of these aspects is discussed. An attempt has been made to show the benefit of theory in comminution practice.

Jan 1, 1995

By R. Q. Honaker

Until recently, the application of the Jameson Cell technology in North America has been restricted to minerals processing. Recently, laboratory, pilot-plant and full-scale testing has been conducted to assess the Jameson Cell's ability to effectively treat fine coal. Based on the data, carrying-capacity relationships have been developed. In addition to its operational simplicity, the Jameson Cell has the ability to provide a separation efficiency near the theoretical separation performance on the basis of ash rejection while achieving a relatively high throughput capacity Tie results obtained from the various fine coal cleaning applications in North America is presented in this publication.

Jan 1, 1999

By Alan C. Noble

Ore reserve estimation is a multi- disciplinary process involving not only tonnage and grade estimation (resource estimation), but also consideration of technical and legal aspects such as mining the deposit, beneficiating the ores, and selling the product. This paper provides a background to under- standing resource estimation including geologic modelling, manual estimation methods, conventional computer methods. and geostatistical methods. Mine planning, metallurgical studies, legal/environmental, and marketing considerations are also discussed as they relate to estimating ore reserves.

Jan 1, 1991

By P. Brumit, L. Grady, R. Mitts, V. Holm

The Mesquite mine is a large, open pit, heap leach gold mine owned and operated by Gold Fields Operating Co.-Mesquite. The mine uses a fully integrated mine planning and reserve modeling software system developed at the mine. This system has recently been extended to include short-term mine planning, grade control, and daily production reporting. The grade control portion of the program uses a multiple indicator kriging (MIK) approach using the blast-hole spacing and exploration assays. The program permits ore control geologists and mine planning engineers to have immediate access to all the information.

Jan 1, 1991

By Leo J. Laughlin

In recent years, heavy mining applications have put an increasing demand on conveyor pulleys. This has resulted in the increased usage of turbine pulleys. The designs of these pulleys are often based upon the failures seen in the conventional welded designs, overlooking the interaction of pulley-shaft system components as the profile of the disc is modified. This paper will focus on the development of balanced design philosophy using case studies of turbine pulleys in heavy mining applications, evaluated with FEA.

Jan 1, 2002

By Laurindo De Salles Leal Filho

Microflotation tests with sodium oleate, in alkaline pH, were performed with apatite and some silicates (phlogopite, quartz, and chlorite) that commonly occur in Brazilian phosphate ores. Further flotation tests were carried out with selected ores containing the same silicates as important gangue minerals. The results showed that apatite recovery is highly affected by competition with silicate minerals, probably activated by calcium ions dissolved in flotation pulp. Inorganic chemical species (sodium tripolyphosphate, sodium carbonate/ bicarbonate, and carbon dioxide) that could act as water softeners were used as modifier agents. They proved to be capable of improving flotation recovery and selectivity.

Jan 1, 1999

By William Mark Hart

Newmont Mining's executive management launched an initiative in 1999 that was designed to engage the entire workforce in a continuous effort to systematically drive inefficiency out of the corporation. Built on a foundation of teams and teamwork, Gold Medal Performance (GMP) has had a significant and positive impact on the reduction of costs. At the same time, it has increased productivity, improved cash flow, and helped Newmont to further enhance health and safety programs. Currently, more than a hundred teams are working on improving line-balancing production and external communications at all levels of the corporation. The training and rigorous set of tools avail- able to and used by these teams were designed to help them improve communications, identify inefficiencies and their financial impact, develop and implement solutions, and finally, to measure the results of the process enhancement. GMP harnesses the energy, creativity, and productivity of the entire workforce.

Jan 1, 2001

By Anis Farah, Khosrow Aref

Pull-out tests were conducted on cable bolts grouted with concrete, and cement paste. The influence of several parameters on the performance of these cables were studied under loading rates varying from very slow to relatively fast. These parameters include water-cement ratio, cable surface conditions, curing time and embedded length. In addition to being more economical, the results indicate that cables grouted with concrete have higher ductility and ultimate bond strength as compared to those with cement paste only.

Jan 1, 1986

By Stefan Gerl, Werner Stahl

Steam pressure filtration combines mechanical and thermal processes in one filtration device. Steam condensation at the cold layers of the filter cake, build a condensation front, which even removes the capillary water from the porous filter cake. Depending on the choice of parameters it is possible to achieve a very low residual moisture content. The influence of the parameters on the dewatering results was systematically examined on a bench-scale apparatus. This paper explains the physical fundamentals, the influence of the cake dewatering parameters, and one possible method of applying the process to a disk filter device as well.

Jan 1, 1995

The gases transportation and adsorption in the coal are greatly dependent on the pore-crack parameters, such as the porosity, the pore distribution, as well as the number and size of the pores. What?s more, the pore parameters of the coal are always changing with the temperature. However, the pore characteristics and their changes are extremely difficult to quantify. In this case, Fractal Theory provides a good tool to address this issue. Based on this theory, the pore distribution coupled with the size of the pores can be quantitatively described. In this paper, the equation used to calculate the Fractal Dimension of coal pores was deduced and Mercury Porosimetry was employed to test the pores distributions of coal samples at different temperature. The experimental data excellently verified the Fractal characteristics of coal pores. In addition, the experiments also indicate that the Fractal Dimension of the coal pores linearly increases with the temperature.

Jan 1, 2012

By B. K. Mishra, R. K. Rajamani

This paper focuses on the use of a numerical tool known as the discrete element method (DEM) to study the motion of ball charge in ball mills. DEM is employed to simulate the motion of individual balls. While doing so, the effect of liner design on the grinding performance of the mill is studied. Two important, factors, such as the configuration of the liner and the geometry of the lifting surfaces, are correlated with the overall mill performance. An attempt is made to show the effectiveness of the lifter bars in transmitting power from the mill shell to the interior of the mill, with particular emphasis on large diameter mills.

Jan 1, 1994