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By B. Lin, C. Tang, Z. Chen

Earthquakes, underground impact pressures and rock bursts all produce acoustic emissions. The rate of these emissions can be used to describe rock instability. In this study, it was found that acoustic-emission rates obtained by simulating a twin sample (rock-rock) model could be used to indicate the acoustic-emission-rate characteristics during rock instability. A computer simulation and two case studies support this conclusion.

Jan 1, 1997

By K. N. Han, M. C. Fuerstenau

Challenges in five major areas of hydrometallurgy are presented and discussed. These are: leaching low-grade oxide and sulfide ores; oxidative leaching of sulfide concentrates; processing refractory ores; bacterial leaching and processing: and secondary metal recovery.

Jan 1, 1989

By P. Magnani

Quarry environmental reclamation can be achieved with favorable economical advantages and high energy efficiency, using stabilized materials obtained by the treatment of organic fraction of municipal solid waste (MSW).

Jan 1, 2005

By Anthony G. Grice

This paper discusses the contribution that backfill is making to the Australian mining industry and provides some information on the largest operations together with some novel applications. Each of the three major backfill types; hydraulic, rock and paste are discussed in turn with a focus on new ideas and advances in understanding, technology and operating practices.

Jan 1, 2001

By R. P. King, S. Middlemiss

A method is developed to convert a measured distribution of fracture energies to the equivalent work index. The method assumes that the energy required to grind the material from the feed size distribution to the product size distribution is equivalent to the sum of the impact energies that are required to reduce the feed material by successive single impacts to the required product size. The method was tested by measuring the fracture energy distributions for quartz and comparing the resulting calculated value of the work index with the work index for this material measured using the conventional Bond laboratory procedure.

Jan 1, 1998

By Dennis V. D’Andrea, Peter G. Chamberlain, James J. Olson, William C. Larson

Blasts designed for in situ copper leaching must produce adequate fragmentation and permeability for successful leaching. Copper recovery depends to a large extent on the particle size distribution created by the blast, the permeability in the blast- fractured zone, and the ability to maintain solution flow with a minimum amount of channeling. This paper presents the results of Bureau of Mines experiments where core drilling was used before and after blasting to establish the degree of fragmentation. Data are presented from tests at the Sierrita mine of Duval Corp., and also from tests at the Emerald Isle mine of El Paso Mining and Milling Co. Copper recovery is predicted from fragment size distribution data using a computer model. Data from several blasts are used to show how predicted copper recovery is related to powder factor.

Jan 1, 1977

By C. E. Jordan, B. J. Scheiner

The Bureau of Mines conducted research on the flotation hydrodynamics of fine particle flotation to improve the flotation efficiency in our domestic minerals industry. The turbulent fluid velocity profile was measured in various flotation cells at different levels of dissipation energy. The importance of dissipation energy and bubble size within the flotation cells for the flotation response of a chalcopyrite ore was evaluated. Both increased turbulent fluid flow and fine size bubbles improved the flotation rate of fine size chalcopyrite particles.

Jan 1, 1989

Diesel engines are used in underground mining 1 throughout the world. Exhaust gases from those engines contain toxic components. To protect quality in underground mines, diesel emission control was introduced decades ago, many years before the first surface applications. Today, emission controls, such as catalytic converters, are standard on underground diesel engines in countries concerned with occupational safety and health. Nett Technologies manufactures a range of diesel emission-control devices for underground mining. Emission problems are not the same at each mining operation. And there is no universal control technology. The selection of exhaust aftertreatment technology depends on raw exhaust emissions, particular emission problems, fuel quality and economics. Some of the technologies that have been used in underground mining to control diesel emissions include catalytic converters, diesel filters, fume diluters and water scrubbers. Table 1 compares the effectiveness of these technologies to control the particular components or aspects of diesel emissions.

Jan 1, 1997

By P. T. Luckie

More efficient classification with a single hydrocyclone through equipment and/or operating design changes does not appear possible. However, improvement in classification efficiency by increasing the sharpness index and decreasing the apparent by-passing while changing the cut size is possible through proper staging of inefficient hydrocyclones. But feasible multistaging requires achieving the necessary material balances around the units. Because of the interactions among the units, these balances require extensive iterations. The final step before commerical installation should be a laboratory demonstration, in order to define the control algorithm required to maintain stability. However, eventually a sufficient knowledge base should be developed that will permit simulation in place of laboratory testing as well as the incorporation of a feed forward strategy.

Jan 1, 1989

By Z. T. Bieniawski

In the past 15 years, rock mass classifications have experienced unprecedented development and have emerged as powerful practical methods for assessing ground conditions and tunnel support. Such methods as the RMR System (Geomechanics Classification) and the Q-System have provided many advantages over the classical Terzaghi rock-load method introduced in 1946. These new classifications have found wide applications all over the world but some doubts have been expressed and shortcomings pointed out. The author, who developed the RMR System, takes a penetrating look into the promises and the pitfalls of modern rock mass classifications. He dispels some misconceptions and shows how rock mass classifications can serve as effective and dependable design aids in tunneling.

Jan 1, 1987

By Eric Forssberg, Benny Andreasson

The paper describes experiments to stabilize mineral processing waste materials for use in construction. Fine mineral processing wastes from various mines have been mixed with binders and compacted. As binders blast furnace slag and other materials have been used. Experiments have been made in laboratory scale and in large scale. The results have been evaluated by means of determinations of compression strength and the modulus of elasticity. The paper also describes some experiments in laboratory and large scale to use stabilized mineral processing wastes for back filling in cut and fill mining.

Jan 1, 1992

By Gerald H. Luttrell, Roe-Hoan Yoon

Flotation columns are becoming increasingly popular due to their ability to improve selectivity and to reduce operating costs. Unfortunately, these advantages are not often realized because of poor operating practices and difficulties associated with design and maintenance. This article provides guidelines for the operation and design of columns. The discussion will focus on designing proper wash water systems for improved selectivity, maximizing throughput by increasing the bubble surface area rate, and minimizing operating and maintenance costs. It is suggested that the design of the air sparging system is the most critical element in column flotation.

Jan 1, 1993

By D. R. Taylor, R. G. Goss

The use of clay-based granules as carriers for pesticides dates back to the early 1940s. It now represents a business conservatively estimated at between 180 and 270 kt/a (200,000 and 300,000 stpy) in the United States alone. Prices for these materials typically range from $110 to $165/t ($100 to $150/st). Aside from economic and specific target pest efficacy advantages, the use of clay granules as pesticide carriers also delivers a number of environmental benefits, which are reviewed. Topics discussed include drift control (vs. liquid sprays), mobility (in the environment), worker safety and transportation (spill) safety.

Jan 1, 2000

By Mandira Madhuchhanda, N. B. Devi, P. C. Rath, R. K. Paramguru, K. Srinivasa Rao

An experimental investigation of the dissolution of three base-metal sulfide minerals, namely, CuFeS2, ZnS and PbS, in hydrochloric acid medium in the presence of manganese dioxide is reported. Polarization measurements and leaching studies were employed in the study. Dissolution occurred in the following three ways: by the cyclic action of the Fe3+/Fe2+ redox couple, by galvanic interaction between Mn02 and the sulfide minerals, and because of chlorine evolution from the system. The later two routes were found more effective at higher HCI levels. PbS appeared to be oxidized easily, whereas CuFeS2 was the most difficult to dissolve. ZnS dissolution fell in between PbS and CuFeS2.

Jan 1, 2002

By Karl H. Gehring

According to the increasing importance of boom type roadheaders in tunnelling essential problems occuring in the application of these machines are dealt with. Based on a chart including the various stages for decicion finding the excavation method of underground cavities, both the technical limits and economic criteria are discussed in order to determine the range of applicability of roadheaders. Giving examples-the numerous developments in the fields of pick and cutting technology, performance data of boom type roadheaders in hard rock, safety technology and increase in the machines' degree of utilization, research and development of VA is illustrated. Two topic operation examples show partial aspects of the various tendencies of development.

Jan 1, 1981

By S. Painter

The effects of forced ventilation and thermal radiation in open drifts are included in three-dimensional thermal hydrology simulations of a potential waste repository at Yucca Mountain, Nevada. A semi-analytical model is used to calculate the amount of waste heat removed by ventilation air during each time step of the multiphase thermal-hydrology simulator. The model accounts for thermal radiation and changes in air temperature and humidity along the emplacement drifts. The fraction of heat removed by ventilation is time and position dependent.

Jan 1, 2004

By Julian Boldy

The discovery of the Delbridge massive sulfide deposit in the Noranda district of Quebec resulted from an appreciation of the significance of a mercury leakage haloas a lithochemical pathfinder to blind ore, coupled to its location relative to a geologically inferred ore-bearing horizon within complex volcanic stratigraphy. Systematic sampling of microfractures present in outcrops delineated a diagnostic anomaly, drawing attention to an area considered prospective for buried ore. The massive sulfide deposit was subsequently found to be blind and topped at the 107-m (350-ft) level. This case history is presented in the context of its time and was the first volcanogenic ore deposit to be discovered utilizing mercury as a pathfinder in the Canadian Precambrian. The case history also illustrates that the practical application of an innovative technique coupled to a new geological interpretation can result in success, even on a property that was centrally located in a mining district and had undergone intensive exploration efforts over a 38-year period.

Jan 1, 1991

By T. van Sandwijk, G. Van Weert, E. Molleman

This paper reports on test work that explored the dissolution/precipitation reaction: ZnS + 2HCl - ZnC12 + H2S, which is part of a process used in the production of pure ZnS. The research focused on the influence of proton activity on the dissolution of zinc concentrates obtained from the Brunswick Mine No. 12 in Canada (Brunswick Mining & Smelting); the Red Dog deposit in Alaska (Cominco Ltd.); and the Tara deposit in Ireland (Outukumpu Zinc). A comparison between the results of the experimental dissolution as a function of pH and the dissolution predicted by thermodynamics suggest that the three concentrates contained sig¬nificant amounts of the more reactive mineral wurtzite, although XRD analysis showed mainly the presence of the mineral sphalerite.

Jan 1, 1999

By James E. McTurk, Sheldon B. Bland, Roger E. Melley

During the first fifteen years of operation at the Syncrude facility in northern Alberta, numerous improvements have been made in the field of ore conveying. The unique nature of the material conveyed coupled with the wide range of environmental conditions encountered results in a number of unparalleled challenges. Most of the improvements have been brought about with the use of detailed field evaluation. This paper outlines some of the programs which have been run to optimise belt and system construction, and conveyor performance and utilization.

Jan 1, 1993

By Y. K. Yen, J. D. Miller, C. L. Lin

A PC image-based, on-line coarse particle size analysis system is being developed for the control of crushing and grinding circuits. Initial results had indicated that the system is accurate when tested with irregularly shaped particles which are stationary and do not overlap with each other. Now the system has been successfully tested in the dynamic mode with a moving belt conveyor. On-line size analysis for actual plant operations is discussed and includes: (1) the video system with respect to lighting and data acquisition requirements for a rapidly moving belt and, (2) image sampling, specifically the number of observations needed for accurate sampling and the total time required to perform the calculations for a representative data set.

Jan 1, 1993