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By J. W. Snavely

WITH all the advantages of handling bulk materials by means of belt conveyor also go some problems, one of the most persistent being that of cleaning. When sticky materials are being carried; the build-up of material on the return idler rolls results in difficulty of belt training. Much attention has been given to the problem of cleaning conveyor belts, and a great variety of cleaning devices have been developed. Even the best involve troublesome maintenance, and none can completely remove the fine particles imbedded in the belt cover, which cause rapid wear of the return idler rolls, and at the same time, of the belt cover as well.

Jan 12, 1951

By J. C. Draper, R. J. Houston, R. E. Pepperman

Duquesne Light Co. and CAI Consultants, Inc. conducted a demonstration program to establish permanent vegetative cover directly on acidic, deep coal mine refuse. Several plots were treated with formulas varying in soil amendment application rates and plant speak. Periodic monitoring of refuse chemistry indicated when maintenance applications of seed and soil amendments were required. To establish drainage control, the site had to be regraded. The most successful experimental formula was used as the bank for the formula applied to regraded portions of the site. Specific treatment for acidic spots has been initiated. Results of the program indicate that adequate permanent vegetation has been established.

Jan 1, 1985

By A. Montini

The problems encountered in the design of control systems for milling cir- cuits when the model of the system and the model parameters are uncertain are discussed. Considering these uncertainty factors has led to the development of a technique that gives a quantitative assessment of real system stability, reveals the trade-offs between performance and stability and helps the designer in deciding what level of model complexity to use in the controller design. Furthermore, it allows for on- or off-line optimization of the milling circuit performance as it provides the base for the design of a controller which is stable over the plant operating range.

Jan 1, 1987

Radioisotope X-ray and neutron techniques of analysis can be used for the determination of a wide range of elements in minerals. The most important applications of these techniques to the mineral industry are for on-stream analysis of slurries and solids, and for geological assay. The radioisotope X-ray techniques are the more developed ones and two installations for on-stream analysis are in routine use in mineral processing plants in Australia. Neutron techniques are being developed, and should prove valuable for geological assay of large numbers of mineral samples, for borehole logging, and for specific on-stream analysis when the cost of the equipment is warranted.

Jan 1, 1969

By S. Ghafarnejad Parto, Å. Rasmuson, A. Fredriksson, M. Mohammadi, K. M. Forsberg, J. Martinez De La Cruz

The present study aims at recovering rare earth elements (REE) in conjunction with the production of fertilizers from an apatite concentrate. Apatite is one of the REE rich minerals ending up in the tailings pond when Luossarvaara-Kiirunavaara AB (LKAB) in Sweden processes Malmberget’s iron ore deposit. Leaching with nitric acid, hydrochloric acid, and sulphuric acid respectively have been studied. The nitric acid route was chosen for further investigations and the optimum acid concentration for leaching of the REE were determined. The leached REE are recovered by solvent extraction using di-(2-ethylhexyl) phosphoric acid (D2EHPA) and 2-ethylhexylphosphonic acid-mono-2-ethylhexyl ester (EHEHPA).

Jan 1, 2014

By Peter B. Nalle

Over a period of years the Crestmore plant of the Riverside Cement Co. has been supplied with limestone from the Chino limestone bed. The limestone bed dips about 40º and extends 1500 ft along the strike. Thickness of the bed is such that horizontal distance from footwall to hanging wall varies from 400 to 1200 ft. When the new room and pillar mining system was instituted the haulage units used for development were model C Tournarockers. Four of these diesel units were purchased with the idea of using them solely for development work since it was realized that they would have to be supplemented by additional, and perhaps larger haulers.

Jan 4, 1959

The Skybolt is a new bolt concept, point anchored with resin in large diameter holes of specific sizes 38 mm and 45 mm. The new design achieves the optimum annular spacing required for mixing the resin anchor components which is essential for optimum resin bonding of the bolt to the surrounding rock. This paper explains the load transfer mechanisms between bolt/resin/rock, unique to this bolt concept. It compares the pull-out test results to those of paddle and expansion shell type bolts, and highlights the versatility of Skybolt over existing, currently used, rock support systems and the benefits mine operators can achieve when using the Skybolt.

Jan 1, 1992

By Hogan C. J

The compact BWE system set up in 1984 to mine ironsand dunes and the underlying ironsand-clay has been an effective high volume produc- tion unit for New Zealand Steel Mining Ltd at the Waikato North Head ironsand mine. The system utilising two compact S400E (0 & K) Bucket Wheel Exca- vators and a single shared Beltwagon for transfer to the shiftable bench conveyors replaced a fleet of mobile elevating scrapers when the produc- tion requirement was increased by a factor of six. A key factor in favour of the BWE system was the economic advan- tages of low unit costs for both manpower and electrical energy.

Jan 1, 1989

By Karel Verscheure

Reliable furnace cooling technology is a domain of increasing concern to the pyrometallurgical industry as it can significantly increase process intensities, productivity and campaign times of furnaces. Although there are many advantages in using cooling systems, they also impose a variety of problems mainly related to safety, heat losses and sustainability of the operations. The choice of cooling system is hence a matter of trade-offs and differs for every metallurgical application. This paper gives a review of different cooling designs used in the ferrous, non-ferrous and alloying industries. Additionally, the paper systematically reviews aspects of materials selection, manufacturing, installation, water quality and furnace monitoring when using water cooled refractories.

Jan 1, 2006

By Eugene Guccione

For at least a decade, the energy crisis was accurately predicted by a small number of industry people who were ignored until last year, when they suddenly found themselves accused for their "lack of planning" and "greed." With the worsening shortage of natural gas and oil, the current scramble is for alternate energy sources-which means: a big rush into coal and uranium mining. (Some big plans are also on the drawing boards regarding geothermal steam, oil shale, tar sands, and even solar energy. But developing such new industries from scratch would be difficult enough even in a healthy economic climate-which is not exactly what the country currently enjoys.)

Jan 8, 1974

By W. E. Lamont

Flotation studies of phosphate-bearing waste pond materials, low-grade washer products, and raw ores, all from the Tennessee brown phosphate district, showed that these types of materials could be treated without des liming to recover high-grade phosphate concentrates. The investigation showed that fine grinding before flotation was a requisite for increased recovery of the phosphate values and that the optimum pH conditions were in the range of 10.0 to 10.5 when using anionic collectors. Multiple-cleaning of the rougher phosphate concentrate was required to produce high-grade concentrates. Phosphate recoveries ranged from 60 to 82 percent and were inversely related to the grade of concentrate produced.

Jan 1, 1972

By P. C. Kapur

A principal first-order and a minor summation term contribute to the solution to the discretized batch-grinding equation when formulated in cumulative retained mode. Depending on the inter relations hips between the selection and breakage parameters, the minor term may be advantageously modified in a number of ways. The reduced grinding equations thus obtained are solved by iterations to give relatively simple solutions which are tested against experimental data. The irn-plications and advantages of the reduced grinding equations are briefly discussed. In many instances, the trajectory of the particle-size distribution in a batch mill may be extracted from a set of particle mass balance equations as follows

Jan 1, 1971

By Edward L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

E. T. Turkdogan (British Iron & Steel Research Assoc., London, England)—I would like to suggest a different method for the treatment of the authors' data on the Si-0 equilibrium in liquid iron. Because the activity coefficient of silicon dissolved in iron is influenced by the concentration of silicon as well as that of oxygen, the equilibrium constant K2 of reaction 2 becomes a function of metal composition, and, as shown in Fig. 1, a plot of log KP1 at 1600°C against the weight percent of silicon gives a smooth curve. A similar curve is obtained when log Kzl is plotted against the oxygen content of iron. Before

Jan 1, 1955

By Waters CA, Happ JV

The debismuthising plant, commissioned in 1980, is based on the Kroll-Betterton process for preliminary bismuth removal with subsequent antimony treatment for fine debismuthising. Bullion flowrate is continuous and the plant was designed to achieve low bismuth lead product at rates of up to 20 tonne/h.Development of the first stage of the operation has enabled reliable operations at 25 tonne/h to be achieved. Thesedevelopments also introduced the opportunity to treat higher bismuth bullion at up to 35 tonne/h when operating the first stage only to produce product lead of 0.029 per cent Bi, meeting the ASTM B29-55 Corroding Lead Standard.

Jan 1, 1985

By E. L. McHugh

Digital camera and computer technologies can be used to monitor mine slopes and provide real-time warning of rock falls. NIOSH researchers assembled a surveillance system using low-cost video cameras and computer software from the security industry to test its effectiveness. The system is designed to signal an alarm when motion is detected and to record images of the scene. Masking can restrict motion detection to specific areas within the camera view; sensitivity is adjustable. The time-stamped images provide a record that can help reconstruct and quantify an event. Video motion detection can augment standard monitoring methods to increase safety in surface mines.

Jan 1, 2004

By C. L. Pillar

TWO shafts have been completed since the spring of 1948 when underground development started, and three are now under construction. The new program provides two main ore shafts, Nos. 3A and 3B, spaced 195 ft apart and located on the south- western end of the orebody. It is planned that eventually 35,000 tons of copper ore per day will be hoisted by these identical four-compartment shafts. The third shaft of this new group is 600 ft from the present No. 1 shaft and will provide caged sup- plies for the underground mining operations. This No. 4 shaft has the largest cross-section of any shaft in Arizona.

Jan 7, 1954

By Komosa T, Muir D. M

Adequate levels of dissolved oxygen are essential for efficient gold dissolu- tion. The actual levels in plantpuips can be seriously reduced by the presence of oxygen consuming reactive minerals, and reduced oxygen solubility in saline water. The rate of gold dissolution is then limited by oxygen availability rather than cyanide. Ion selective electrode dissolved oxygen meters can give an effective indication of the relative oxygen saturation, but they are not able to give meaningful values of dissolved oxygen in saline water, without custom calibration curves. When the dissolved oxygen concentration is rate limiting, the addition of oxygen or peroxide can improve gold leaching kinetics as well as reduce cyanide consumption.

Jan 1, 1991

By C. S. Compton, D. R. Dolinar, D. C. Oyler

More than 80% of U.S. roof bolts are fully-grouted, but about 1500 roof falls are reported each year. Anchorage failure of a fully grouted bolt can occur when the roof is active near the top of the hole. This paper reports on an extensive series of short-encapsulation pull tests (in which the bolts are installed with only 1 ft of resin) that were conducted in the National Institute for Occupational Safety and Health(NIOSH) Mine Safety Research Laboratory and operating mines in WV and PA. The tests confirmed that poor anchorage can been countered under some weak rock conditions. Suggestions for improving anchorage are included.

Jan 1, 2003

By Robert F. Holub

The Bureau of Mines has evaluated four working-level radiation-measurement methods and optimized them from the inherent and statistical error standpoint. Optimization with respect to various sampling and measurement times yielded no marked improvement over the existing methods. However, when appropriate approximations are made and evaluated, these two-measurement methods can be reduced to simple formulas, eliminating a need to use nomograms. These modified methods also have improved inherent error characteristics. A new method--a combination of two existing methods--with improved inherent and statistical errors has been suggested. All the pertinent equations are given, together with the computer program, so that any two-measurement method can be readily evaluated.

Jan 1, 1980