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The published liquidus data on the Pb-PbS system have been correlated on the basis of one-coefficient Margules equations. Thermodynamic properties of the components of this system have been obtained, and it has also been found that the calculated miscibility gap of this system exists over a very narrow range of temperature (1041 to 1058°C).

Jan 1, 1972

By A Crosky, S Saydam, H Chen, H L. Ramandi

Cable bolts and rock bolts are used as primary and secondary anchoring systems in many underground mines. Reports on the premature failure of cable bolts and rock bolts due to stress corrosion cracking (SCC) in underground coalmines have been increasing in the past two decades. The previous studies found that the SCC in both rock bolts and cable bolts occur as a consequence of atomic hydrogen diffusion into the material, which is known as hydrogen-induced stress corrosion cracking, HISCC (Craig et al, 2016; Wu et al, 2018b). While research to understand the process of SCC occurrence in underground mines is still required, finding a prevention solution to protect the bolts from HISCC is crucial. In this study, we analyse a variety of commercially available coatings for steel corrosion prevention, including barrier coating (ie epoxy, polyester TGIC) and sacrificial coating (hot-dip galvanising). We test the coating on coupons manufactured from rock bolts and cable bolts used in the coal mining industry.

Nov 29, 2022

By J. N. van de Merwe

CONTRIBUTION BYH. WAGNER AND T.T. OZAN The paper by Dr J.N. van der Merwe makes an important contribution to the design of bord-and-pillar workings in the Vaal basin. It has been recognised for some time that the strength of coal seams in the Vaal basin is markedly lower than that of coal seams in other coal-mining districts in South Africa. However, there was insufficient data to quantify how much weaker the extensively jointed coal the Vaal basin is. A number of recent pillar collapses that occurred at Sigma colliery, the only remaining underground colliery in the Vaal basin, provided Dr Van der Merwe with an opportunity to make this assessment.

Jan 1, 1993

By Mark S. Stagg, Rolfe E. Otterness, Farrokh Djahanguiri

The U.S. Bureau of Mines (USBM) evaluated empirical equations that predict fragmentation from underground stope rounds. Controlled blasting is necessary for creating leaching stopes that maximize the recovery and minimize backbreak of the perimeter wall. This paper presents the fragmentation results from one of the three drop-raise blasts used to develop a reduced-scale cylindrical stope, 1.8 m in diameter and 6 m in height. The stope is located in the Colorado School of Mines Experimental Mine (Edgar Mine) in Idaho Springs, Colorado. This stope is part of a USBM research effort to determine the feasibility of incorporating in situ leaching of rubblized stopes into active underground metal and nonmetal mines.

Jan 1, 1994

By Charles H. Jacoby

A decision was made by the management of International Salt Co. in 1960 to eliminate all waste products which were entering the waters of Lake Seneca. This was to be accomplished by the injection of waste slurries into an abandoned brine cavity. The effluent from the cavity was to be treated and used for the manufacture of salt or disposed by deep well injection into the Cherry Valley limestone. After several years of research and design, a construction permit was granted by the state of New York; the injection, recovery, and disposal wells were constructed and after a public hearing an operational permit was issued. A summary of the operational results of the system is given.

Jan 1, 1974

This paper presents a summary of tools and methods used for geotechnical assessments and monitoring systems at block caving mines. A critical review of these tools is given based on the authorÆs experience in block caving operations. The reviewed tools include cavability prediction, fragmentation evaluation, geotechnical monitoring systems, numerical stress analysis and others. Some of these tools have been developed under certain circumstances in particular mines and experience shows that their applications under different geological and mining conditions have often been difficult. Examples from block cave mines are also utilised in this paper to illustrate the importance of the further development of these tools, whilst possible improvements on these tools are also suggested.

Jan 1, 2000

By Michael Chender

The current outlook for financing new copper production is not very encouraging. At a time when companies are slogging through a protracted period of low prices as well as having to accept lower profits due to more stringent tax and royalty schedules, banks are beginning to require companies to take a greater equity interest in new projects. Mineral resource financing, including copper, seems to have lost much of its appeal to the lending institutions, and loans of any kind to many of the developing countries -from which over half of new copper capacity could be expected to come-are being examined much more critically than they were in the late 1960's and early 1970's.

Jan 12, 1976

By R C. Owen, M A. Ward

The paper describes the application of New Zealand's environmental impact assessment procedures to a proposed gold and silver mine in the North Island of New Zealand. The project is described and a summary is provided of the statutory permits or consents that are required prior to operation of the project. Emphasis is given to the requirement for environmental impact assessment and the preparation of a formal environmental impact report. The company's approach to impact assessment is described, with examples of how this assessment and the identification of management alternatives influenced the engineering design of the project. This paper was prepared as a contribution to a working session of the International Association of Impact Assessment VII Annual Conference, July 1988.

Jan 1, 1988

By Dirk van Zyl, Clint Strachan

A study was conducted to assess the feaeibility of increasing the heap height above one lift at the Alligator Ridge Mine. This study concentrated on the physical aspects of the heap and liner performance. Two principle aspects were addressed during this investigation: (a) the adequacy of heap permeability under present and future loading conditions; and (b) the adequacy of the liner to limit seepage losses. Field and laboratory test a were performed and their details and results are presented. It was concluded that the permeability of the heap would remain adequate for higher heap. The geometry of the heap will be the major constraint. It was also concluded that the liner would perform satisfactorily beneath higher heap.

Jan 1, 1987

By John A. Rumball, Martin R. Houchin

"For gold leaching of oxide ores, the optimum cyanide : oxygen ratio is approximately 106 mg/L NaCN : 10 mg/L O2 (6.9:1 by mole). In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio such that leaching may occur in a relatively low dissolved oxygen (DO) environment.RESULTS AND DISCUSSIONGold leaching in a carbon in pulp (CIP) and carbon in leach (CIL) circuit is driven by the supply of cyanide and oxygen, as described by Elsner’s equation (1):• 4Au + 8CN- + O2 + 2H2O ? 4Au(CN)2 - + 4OH- (1)Equation 1 suggests that the ideal molar cyanide : oxygen ratio should be 8:1, or 122.5 mg/L NaCN to 10 mg/L of DO. It is generally accepted however, that oxygen is not completely reduced to hydroxide at the gold surface, and that equation (2) better represents the gold leaching reaction (Marsden and House, 1992):• 4Au + 8CN- + 2O2 + H2O ? 4Au(CN)2 - + 2OH- + H2O2 (2)Additionally, since gold leaching is limited by either the diffusion of cyanide or oxygen to the gold surface (Habashi, 1993), then the relative diffusion rates of cyanide and oxygen must also be taken into account. Marsden and House (1992) suggest that the ideal molar cyanide : oxygen ratio is 6:1, while a more recent investigation using laboratory and plant observations (Heath and Rumball, 1998) suggested a molar ratio of 6.9:1.In practice, although a cyanide : oxygen mole ratio of 6.9:1 applies to some circuits, there are many instances when this is not the case.In sulphide ores, galvanic coupling of the gold with the electrically conductive sulphides significantly increases this ratio. Galvanically connected sulphides, and possibly carbon, provide a large surface area for oxygen reduction. As the cathode surface area increases, the oxygen concentration required to sustain the same rate of gold oxidation decreases proportionately.Galvanically connected particles may be composite particles, however they may simply be liberated sulphides in the same suspension as the gold. Particle collisions within a slurry are sufficient to provide momentary galvanic connection (Greet, 1995)."

Jan 1, 2003

By Karl Sundberg, Allen Nordstrom

Interesting results were recently obtained in geophysical prospecting at the Questa mine of the Molybdenum Corpn. of America in New Mexico. This paper describes that survey, which was carried out during October and November, 1927, by the Swedish American Prospecting Corpn. It is hoped that the paper will make it possible for the mining man to form an opinion of the applicability of geophysical prospecting under difficult conditions, showing, as it does, the results when prospecting for small small orebodies with comparatively poor conductivity, in a region of rough topography. Some principles underlying electromagnetic prospecting not known to be published previously will also be given in an elementary way, with special attention to the general structure of the electromagnetic field. Geological. Conditions at Questa The property is situated in the Taos range of the Rocky Mountains in northern New Mexico. About this region, L. C. Graton says:' The main range is made up of Pre-Cambrian granites, gneisses and schists but in the vicinity of Red River igneous rocks of later age are present almost to the exclusion of the older series. These younger rocks are divisible into two groups. The older of the two, probably Pre-Tertiary age, is represented by large intrusive masses of monzonite porphyry, usually containing considerable quartz. The more recent group comprises intrusive and probably effusive dark-colored andesites and coarse andesitic breccias, some of which contain fragments of the monzonite; there are also flows of rhyolite and beds of rhyolite breccia. The evidence regarding the relative age of the andesite and the rhyolite is not wholly satisfactory, but there is little doubt that the andesite is the older. The ore deposits, although occurring more commonly in the monzonite porphyry than in the rhyolite, nevertheless are believed to be genetically related to the rhyolite. They certainly cut the rhyolite or andesite in places, and hence fall in the late Tertiary. The molybdenite at the Questa mine occurs in veins in the alaskite granite porphyry belonging to the older part of the Pre-Tertiary eruptives. Overlying the granite porphyry is the granodiorite, capping the granite

Jan 1, 1929

By P. K. Kaiser, R. K. Brummer

Paper presented at the conference Risk assessment in the extractive industries, held in Exeter, 23-24 March 1994. A risk-based decision-making procedure has been developed for selecting rockburst-resistant tunnel support in burst-prone mines. The method is based on a risk-cost-benefit analysis and uses support cost data, costs associated with the risk of support failure or excavation loss, costs associated with accidents, injuries and deaths, and the benefits achieved by installing rockburst-resistant support. It takes into account the risk of damage to the support systems due to rockbursts, potential loss of production and the need to rehabilitate in the event of a damaging rockburst. A practical example is provided to illustrate the principles involved in the decision process

Jun 17, 1905

By W. G. Cornwell, R. J. Hisshion

The development of a process for the treatment of telluride concentrates at Emperor Gold Mining Co. Vatukoula, is discussed. The concentrate is produced by flotation in cyanide solution immediately after milling. Two stages of cleaning are employed and a high-grade concentrate is produced usually containing more than 50% of the precious metal. The process developed in the first instance involved batch roasting followed by batch leaching in strong cyanide solution, recovering gold and silver only. The procedure currently employed is chemical oxidation of the tellurides using hypochlorite as the oxidant in a basic solution of a caustic soda and sodium carbonate. After oxidation the gold and silver are recovered by cyanidation. The residue is then leached with sodium sulfide and elemental tellurium precipitated with sodium sulfite.

Jan 1, 1977

By Marcelino Cortina

It is known that underground bituminous coal mining in the Central Asturian Coal Basin (North of Spain) is a complicated task, due basically to the difficult geological conditions: thin and steep Seams with many faults and other disturbances. Therefore, it is not easy to decide what is the most suitable mining method for each of the seams, and problems in making the correct decision are encountered frequently. Because selections in the past have been inadequate an Expert System, ASTURLABOR;hulla, has been designed and will be developed' to provide accurate advice in the mining method selection process. The paper describes the major features of this Expert System and outlines the ASTURLABOR general project, which includes five other mining Expert Systems to complement ASTURLABOR-hulla.

Jan 1, 1989

By Irwin R. Higgins, Joseph C. Milbourne

The selection of a suitable nitrate removal process depends on a variety of site-specific chemical and environmental issues. The dominant technologies for nitrate removal include biological denitrification and continuous countercurrent ion exchange. The decision to apply either of these technologies, or both together, depends on the nature of the waste water to be treated. Factors that affect the selection of the biological system include the feed composition and feed temperature. Ion exchange nitrate removal systems ere less sensitive to the feed composition but require disposal or destruction of the concentrated pregnant eluate. The paper discusses Tetra's continuous countercurrent ion exchange technology (CCIX™) and fixed film biological reactor, Denite®. The treatment of the ion exchange pregnant eluant is also discussed.

Jan 1, 1995

By T. P. Oxford, G. Y. Onoda, E. D. Whitney

Disposal of phosphatic clay waste slurry has been a problem since the advent of hydraulic processing of phosphate rock in Florida. Alternatives to the present practice of storing slimes behind earthen dikes have been earnestly sought for more than a quarter of a century. Seepage dewatering is a promising technique intended to increase waste clay solids content to a level sufficiently high to permit clay disposal in mine cuts, in lieu of above-grade impoundment. An experimental array of vertical seepage columns containing mine tailings sand was constructed. Significant improvement in waste clay dewatering relative to that occurring in a control test was observed when approximately 1800 m3 of waste clay was disposed of in the presence of the seepage aids.

Jan 1, 1983

By Ann G. Kim

Gas samples containing 02, N2, H2, He, CO2, CO, CH4, and trace amounts of C 2 to C6 hydrocarbons are analyzed by a gas chromatographic method that utilizes both thermal conductivity and flame ionization detectors. A porous polymer support and molecular sieve columns are used with argon as the carrier gas. A column selector valve makes it possible to perform a complete analysis either on one 1-ml sample in 40 minutes or on two samples in 20 minutes, one sample for each detector. Samples are introduced either by on-column injection or through a gas sampling valve. By varying operational parameters, the speed, sensitivity, and accuracy of analysis may be modified to suit a particular situation.

Jan 1, 1974

By Crawford G. R, Wold M. B

The application of the hydraulic fracturing technique to the measurement of in situ rock stress from underground excavation is discussed; including relevant theoretical considerations, equipmenl details, experimental technique and analysis procedures. Examples of the application of the technique at three Australian coal and metalliferous mining operations are given. The results obtained from these applications are compared with corresponding results obtained from overcoring tests conducted in close proximity at each site. Generally good correspondence in a wide variety of rock types is indicated. Experience gained with hydraulic fracturing at several underground mining sites has indicated it to be a quick, cost effective means of gaining an understanding of the in situ stress field in sufficient detail for many mine planning functions.

Jan 1, 1990

By J. O. Lewis

Oil wells usually reach their maximum daily output shortly after they are completed. From that time they decline in-production, the rapidity of decline depending on the output of the wells and on other' factors governing their productivity. The production curve of a well shows the mount of oil produced per unit of time for several consecutive periods; if the conditions affecting the rate of production are not changed by outside influences, the curve will be fairly regular, and, if projected, mill furnish useful knowledge as to the future production of the well. By the aid of this knowledge the value of a property may he judged, and proper depletion and depreciation charges may be made on the books of the

Jan 2, 1918

By Worotnicki G, Tillmann V. H

Past experience with fully bonded cable dowels placed as a means of reinforcement in highly stressed crop pillars at the New Broken Hill Consolidated Limited (NBHC) mine indicated such support was not fully effective. Typically overbreak of the crown occurred leaving long lengths of cables hanging from the back stripped of grout and rock with the potential load carrying capacity of the cables not having been fully utilised. This mode of behaviour had been observed in the cable dowelled crowns of three longhole open stopes (EROS) mined to the No. 12 level at NBHC. A system of support with improved mechanism of load transfer from rock to cable and capable of full utilisation of cable strength was proposed for the crown pillars of future Stopes.

Jan 1, 1983