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By Jun Li, Marc Le Vier, Rong Yu Wan, Jan D. Miller

The hydrometallurgical treatment of gold and silver ores by ammoniacal thiosulfate solutions in the presence of a copper catalyst has been actively studied in recent years. Such a process strategy is very attractive due to the low toxicity of the lixiviant and the efficient recovery of the precious metals from difficult-to-treat ores. Important features of the ammoniacal thiosulfate system for the recovery of precious metals from various sources are reviewed in this paper, including leaching, metal recovery, and system stability.

Jan 1, 1995

By Y. C. Kim

This paper describes the implementational aspects of a blast hole kriging system that has been developedfor the purpose of daily ore/waste control in an open pit mine. The primary goal of blast hole kriging is to improve the ore/waste delineation procedure. A complete computer program package called Blast Hole Kriging (BHK) System was developed for IBMIPC AT or XT computers, using the Fortran language and supplemented by a few assembly language routines for the bit- map manipulation. This paper emphasizes the practical implementation requirements of the system and discusses system design considerations.

Jan 1, 1991

By Donald W. Peters

The 191 million acres of public lands that are managed as National Forest System Lands contain extensive geologic habitat for over 40 industrial minerals. The Forest Service actively encourages exploration for and development of industrial mineral deposits within the National Forests. However, due to competing interests, the Forest Service may not always be able to accommodate industry needs. In order to successfully compete with ever-increasing demands for all resources in the 1990's, industry needs to become more active in public involvement and education and in communicating its contributions and needs to public land managers.

Jan 1, 1991

By H. Y. Sohn, H. K. Lin

The leaching of primary porphyry chalcopyrite ore under simulated solution-mining conditions was studied using a packed-bed reactor. A mathematical model incorporating the intrinsic leaching kinetics of chalcopyrite and pyrite grains, the pore diffusion of dissolved oxygen within the ore fragments, liquid-solid mass transfer, and the effect of fluid flow and axial dispersion was formulated and tested for the overall leaching process. The dependence of oxygen solubility on ionic strength of the solution was also incorporated into the model. Satisfactory agreement between model pre- dictions and experimental data was obtained. The model can also predict the rate of the leaching process under different temperatures, oxygen pressures, solution flow rates, and different size distributions of ores.

Jan 1, 1991

By D. D. Banerjee, S. K. Kawatra, T. C. Eisele

A high calcium fluidized-bed combustor ash was shown to be an effective binder for iron ore pellets at dosages of 1 % to 2% of the magnetite concentrate weight. Magnetite pellets that were between 1.1 and 12.7 mm (7/16 and 1/2 in.) in diameter were produced with dry crushing strengths greater than 22.3 N (5.0 lb-force) per pellet, which is comparable to the results produced using conventional bentonite binder. The effectiveness of fly-ash-based binders was considerably improved when calcium chloride was added as an accelerator. The addition of calcium chloride at a rate of 0.1 % to 0.2 % of the total powder weight increased the strength of the dried pellets by as much as 22 % compared to the strength of pellets made using fly-ash without accelerators.

Jan 1, 1999

By T. Vincze

Effective coal mine face ventilation, for remotely controlled and automated mining systems, is essential for the control of methane. The evolution of new mining equipment and methods has required changes and improvements in face ventilation methods. One emphasis today is on the use of remotely operated and automated mining systems that can be used to make continuous cuts of 6 m (20 ft) and deeper. U.S. Bureau of Mines research is studying ways to more effectively ventilate these extended cuts. Two face ventilation techniques that utilize either blowing brattice or a jet fan for deep cutting are examined in this paper. Bureau of Mines procedures for evaluating face ventilation systems are also discussed.

Jan 1, 1992

By Frederick W. DeVries, J. Brent Hiskey

Cyanide has been recognized for about a century as the most effective reagent for processing gold ores. Cyanide leaching has been adapted to various metallurgical settings and continues to be improved. However, in recent years attention has been directed to alternative lixiviants for treating refractory ores and concentrates, and to the development of less environmentally controversial substitutes for cyanide. This paper reviews some of the reagents considered as alternatives to cyanide and focuses on environmental implications for using these newer reagents.

Jan 1, 1992

By René E. Fuenzalida

The copper market has become highly competitive around the world; therefore, operations efficiency is a must for copper producers. The economic outcome in a day-to-day milling is not evident at the concentrator stage, when traditional procedures are used in operations management, based on the supervision of process variables and metallurgical indices. Therefore, in such a complex business, there is a strong need to devise an approach to furnish concentrator's operators with procedures and tools to state and solve the problems related to operational decision making, leading to maximize the economic return of investment; this is what is aimed to be presented in this paper.

Jan 1, 1998

By Hardy J. Smith

The rock mass parameters which need be evaluated to estimate the rippability of rock are briefly outlined and their significance is discussed. Several methods used for estimating rippability are compared, and the advantages of taking into account a wide spectrum of rock mass parameters are emphasized. A systematic means of numerically weighing six rock mass parameters to produce a Rippability Rating (RR) is recommended, and a method of correlating this rating with the refraction seismograph method and with tractor horsepower is shown. Although the overall method demonstrated is systematic and yields specific numerical results, an integrated approach is recommended to its application, taking into account: the Rippability Rating; seismic velocity and geologic material; and other engineering judgment factors.

Jan 1, 1986

By R. D. Miller, L. Schulte, J. Davenport, D. W. Steeples

Shallow seismic reflection methods were successfully used to delineate the subsurface extent of roof failure associated with the dissolution mining of a 120-m (400 ft) deep and 60-m (200ft) thick salt bed in central Kansas. Surface subsidence at North American Salt's Hutchinson, KS, salt-dissolution well field represents a potential risk to surface structures and transportation facilities. Three intersecting common depth point (CDP) seismic reflection profiles, targeting the subsurface around an actively subsiding sinkhole, possess sufficient resolution to delineate the horizontal and vertical extent of subsurface rock failure associated with the subsidence. The three seismic profiles showed a disturbed subsurface area 90 to 105 m-diam (300 to 350 ft-diam) at a depth of between 60 to 75 m (200 ft and 250 ft). Confirmation drilling verified the interpretation of the seismic data. The seismic reflection method has the potential to resolve disturbed subsurface areas greater than 23 m-diam (75 ft-diam) at this site.

Jan 1, 1994

By W. E. Horst

Historically, research organizations have made significant contributions to the development and commercialization of new chemical products for the mining industry and examples of commercial results are cited With the recent demise of research organizations within the mining industry and dynamic changes in the industry, the supporting role of R&D groups has become limited or non-existent. Cat- reduction requirements and new raw-material sources offer future opportunities for R&D organizations to continue their effective participation in the commerical development of new chemical products. Potential areas of interest for future process applications are reviewed.

Jan 1, 1986

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 Frank F. Aplan

Coal flotation offers the promise of a highly effective, large tonnage, low cost means of cleaning fine coal. Unfortunately, it has, to date, not lived up to its promise. Several problems that need to be addressed before coal flotation can achieve its promise are discussed and possible solutions offered.

Jan 1, 1989

By Ronald S. Conti, Harry Dobroski

Re1iabl e monitoring a1ong an underground mine belt line is of great concern because of combustibles, electrical apparatus, and friction. Belt entries are strategically located where a fire can have rapid and disastrous consequences. This paper reviews conventional distributed temperature sensing systems based on resistive, thermistor, and thermocouple effects. These are shown to provide limited benefits. A new system tested by the U.S. Bureau of Mines based on fiber optics and time domain reflectrometry, promises much better temperature and spatial resolution, faster response, inexpensive cable, longer distance, and comprehensive data analysis. Test results in a small, controlled, in-mine fire are given.

Jan 1, 1992

By Olli Järvinen

The precious metal refinery process is divided into the five process stages: 1 .copper/nickel leaching in autoclave 2. selenium roasting furnace 3. doré metal smelting furnace 4. silver electrolysis 5. gold recovery system. The process has been developed during the years in Outokumpu Harjavalta Metals, which treats about 600000 kg /year copper anode slime. The slime treatment process route in Outokumpu Pori plant has been developed from year 1941. During this period the process has been improved radically. The major changes has been the atmosphere leaching into the autoclave leaching, the sulfuric acid roasting furnace was changed into sulfuric dioxide / oxygen roasting. The old doré smelting furnace has changed into the TROF converter and the gold electrolysis / aqua regia process has changed into the quick hydrochloric acid leaching process. The current production in Pori plant is 30000 kg of silver, 1000 kg gold, 30000 kg of selenium and some hundred kg of platinum- palladium concentrate.

Jan 1, 1995

By Matthew J. Hrebar

Dragline stripping operations account for over one-half of the U.S. bituminous coal production mined by surface coal mining methods. The dragline is a popular stripping tool because of its flexibility in varying overburden depths and relatively low operating costs per cubic yard of overburden. Because of the relatively high capital costs of the machines and their use as a primary stripping tool, the selection process is an important step in the mine planning procedure.

Jan 1, 1979

By Heiskanen K., Koivistoinen P.

A common belief is that autogenous grinding suits itself only to certain oretypes. It is shown that properly designed autogenous grinding can be used even with very difficult ores with energy consumptions which are equal or lower than obtained with rod-ball mill grinding. The basic feature in the design is the large port grate developed by Outokumpu. The scale-up of the mills can be done on the basis of the base mill concept. It enables to compare different mill sizes and types. Simple scale-up equations are presented based on actual mill data and experimental work.

Jan 1, 1992

By Shulin Xu, Moreno Pescara, Nicola Avagnina, Piergiorgio Grasso

The Roreto Tunnel is a shallow, twin-bore, road tunnel on the connection between the A6 and the A21 motorway in NW Italy. The challenges faced the design and construction of this tunnel derive from 1) the presence of groundwater, both phreatic and artesian; 2) excavation in loose and/or little cohesive materials; 3) excavation in cohesive materials containing water-saturated, sand lenses; and 4) surface constraints due to the urban environment. In this paper, these problems are examined and the rationale led to the optimum design choices and construction solutions explained. The experience should be useful to others when tunneling in similar situations.

Jan 1, 2003

A thermomechanistic model was developed for the thermal decomposition of the enargite contained in a copper concentrate at 650° to 750°C in a fluidized bed with an inert atmosphere. At the particle level, the model permits one to predict the thermal profile inside the reacting enargite particles, as well as their thermal cycle. At the macroscopic level, a population-based model coupled to the bubbling-bed fluidized bed model allows one to predict the fractional conversion (dearsenification) of an enargite-bearing copper concentrate.

Jan 1, 2002

By Heinrich Schubert

In many unit operations, there are more or less developed turbulent flow conditions. Then, macroturbulence influences the transport phenomena of the particles and microturbulence controls the stresses acting on fluid and solid particles or agglomerates as well as the collisions between particles. Consequently, these conditions have to betaken into consideration for modeling and optimization. The results of corresponding approaches are demonstrated taking classification and flotation as examples. But, at present, extensive simplifying assumptions have to be made.

Jan 1, 1989