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By J. Muir

This report focuses on minimum ore block sizes that are economically feasible to mine with the vertical crater retreat (VCR) method. In 1985, Homestake Mining Co. began a program to bring several small block VCR stopes on line. This report examines these experimental stopes, including design parameters, ground control, drill patterns, secondary blasting, and mucking. Cost and scheduling comparisons are made with mechanized cut-and-fill and open cut- and-fill methods.

Jan 1, 1987

By T. W. Camm

In this US Bureau of Mines report, mine and mill cost models are presented to make estimates of the cost to develop mineral deposits in the desert region of the southwest United States. Regression analysis was used to generate capital and operating cost equations for each model based on daily production capacity. These models are used for Potential Supply Analysis (PSA) studies by the Bureau, which analyzes the economic benefits of minerals in a region.

Jan 1, 1995

By William F. Ryan, Paul T. Gribbon

With the rise in construction claims in public works contracting over the years, the use of Dispute Review Boards (DRB’s) in underground construction contracts has become quite common. However, in order for the DRB process to be an effective tool, there must be complete trust and confidence in the Board members and their adopted procedures by both the owner and contractor. This can be difficult in an industry where Board members and contractors may be well known to each other, while an owner maybe involved in a large complex underground project only occasionally. Using case histories, this paper will discuss some recent experiences with the DRB process from an owner’s perspective.

Jan 1, 2003

By G. A. Goller, Y. C. Lo

Microscale studies involving an ultrafast load cell have been shown to provide direct and accurate measurements of particle strength, particle fracture energy and particle breakage functions under different loading geometry conditions. The effect of grinding media size, shape, density and surface properties on the energy efficiency can be quantitatively determined for different materials to be ground. The applications of microscale comminution studies have been demonstrated to provide good predictions of grinding mill performance with different grinding media.

Jan 1, 1995

By David L. Gefvert

A general review of the role of cationic flotation reagents in the beneficiation of phosphate, iron, and potash ores. The three major types of cationic collectors-amines, ether amines, and condensates will be compared and contrasted. The effect of particle size, water chemistry, and water temperature on the choice of cationic flotation reagents for each industry will be discussed.

Jan 1, 1986

By Robert S. Post

A highly respected coal mining company in West Virginia updated their stacker belt by switching to a new magnetic coupling. The savings they achieved are the subject of this paper. A steep incline and heavy belt loads are powered by a dual drive arrangement. The magnetic couplings were custom designed for complete fluid coupling retrofit and easy installation in the field. Maintenance personnel updated the drives in just a few hours. Over the following several weeks, adjustments were made to the couplings for optimum performance. Cost savings are found in reduced down time, no coupling maintenance, and equipment protection.

Jan 1, 2000

By Deepak Malhotra

Comminution circuits in general account for fifty percent of capital and operating costs for a processing plant. Significant advances have been made in optimization of these circuits. One would expect a few circuits to be the favored designs for plants. Review of grinding circuits worldwide indicates that a variety of circuit designs are utilized for non-technical reasons. A brief review of circuits and reasons for their selection is given in this paper.

Jan 1, 1998

By F. Bourgeois, J. A. Herbst, R. P. King

The ultrafast load cell (UFLC) has proved to be an exceptionally good device for the study of the fundamental processes associated with the impact fracture of particulate material. A new high- sensitivity UFLC has been commissioned at the Utah Comminution Center for the study of low-impact energy single-particle fracture. The force-time histories of individual fracture events have been measured. The force and energy absorbed at crack initiation have been measured at several particle sizes. The mass specific energy for fracture and the associated breakage function have been determined. The distributions of particle breakage energy and particle strength have been measured as a function of particle size.

Jan 1, 1992

By George Owusu, Ernest Peters, A. J. Monhemius, G. W. Warren, David B. Dreisinger, E. Peters

Lignin sulphonic acid (or its salt) is commercially used as a surfactant in the Zinc Pressure Leach process. The surfactant prevents liquid sulphur from coating unreacted zinc minerals thus allowing the leaching reaction to proceed. Infrared studies have been performed using the Attenuated Total Reflection-Fourier trans- form infrared technique (ATR-FTIR); the application of this technique permitted the "in-situ" study of the adsorption of the surfactant by sphalerite. The spectral records obtained from study indicate that the lignin sulphonate ions are both physically and chemically adsorbed by the sphalerite.

Jan 1, 1993

By R. H. Grau

The National Institute for Occupational Safety and Health's Pittsburgh Research Laboratory is now involved in research to identify silica dust generation in underground metal/nonmetal mines. The ultimate goal of this research is to develop control technologies to reduce worker exposure to respirable silica dust. Commodities and job classifications with the highest silica dust exposure have been identified through analysis of the Mine Safety and Health Administration's compliance dust-sampling database. Dust surveys were conducted in an underground limestone and gold mine to investigate silica dust sources, generation levels and the controls being used. A summary of the mining operations, sampling procedures, resulting data and suggested methods to improve dust control are provided.

Jan 1, 2003

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 C. D. Elifrits, N. B. Aughenbaugh

Laboratory tests of samples of fine- grained, argellaceous rocks, commonly referred to as shales, have shown that various changes in their moisture content can be correlated with loss of strength. This reaction to a change of in situ conditions at abandoned mine sites when combined with the field relationships at locations where the predominant overburden material is fine-grained, argellaceous, and fractured provides a predictive tool for engineers dealing with subsidence problems. Such a tool should enable engineers to recognize areas that are prone to be affected by surface disturbing subsidence features.

Jan 1, 1987

By A. M. Johnson, D. H. Carlson, D. L. Johnson, S. T. Bagley

A biologically assisted ferric iron leaching system was evaluated for in situ recovery of three copper sulfide oresfrorm northern Michigan. Laboratory scale bacterially assisted ferric sulfate leaching tests were run on the three ores. A T. ferrooxidans strain was found that could be adapted to copper in solutions at concentrations as high as 20 g/L. Column leaching of 4.5 to 2 mm (-4 +I0 mesh) material yielded extractions of 80-90% copper from one ore and 70 and 60% from the other ores. The highest copper extractions were from the Mount Bohemia ore deposits located in the Keweenaw Peninsula, which have fracture controlled chalcocite mineralization. The Bohemia ores are apparently well-suited for in situ solution mining.

Jan 1, 1987

By David R. Zuchelli, Elio L. . Checca

Two case studies of methane gas explosions and their effect on the operation of underground coal mines are presented. The studies detail the recovery operations and investigations at each mine site. These include the circumstances prior to the explosions and the effects on the surface and underground ventilation control systems. Various ignition sources such as surface and underground electrical power systems, degasification sites, ventilation shafts, test well casings, and lightning activity were investigated. In each case, a lightning report from the National Lightning Detection Network1 was used in conjunction with the physical evidence and eyewitness accounts to confirm lightning strikes as the ignition source for the explosions.

Jan 1, 1995

By D. Limpitlaw, E. M. Hoadley

The minerals sector plays a significant role in the development of many Southern African economies. In the Southern Africa region, as in other developing regions, economic development is seen as the key contributor to poverty alleviation and social upliftment. The significant economic contribution of the minerals sector may be reduced by negative impacts on the biophysical environment and on the communities where mines operate. A critical variable in determining the net contribution of mining companies to SD is the degree of transparency with which the companies operate. Transparency is increasingly emphasised as an essential aspect of good governance and SD, but it is also difficult to establish, and is a sensitive issue for mining companies as they compete with each other for minerals sales. Transparent reporting could ensure that the interests of all stakeholders are addressed as company data is subject to informal ‘auditing’ by any interested party. This paper assesses published reports of five companies over a number of years to establish whether it is possible to make an assessment of the companies’ contribution to SD.

Jan 1, 2005

By Christopher Haycocks, Randolph Reed, Erik C. Westman

The industrial Source Complex (ISC3) model is the accepted standard used to predict emissions of particulate matter less tan 10µm in diameter (PM10) from industrial operations. This model, however, over-predicts PM10 emissions from surface mining operations, making permits harder to obtain. The over-prediction is likely due to the fact that the model applies emissions from mobile (dynamic) sources to stationary (static) areas. Utilizing a Gaussian dispersion equation, a Dynamic Component Program was created to correct the over-prediction of the model and results in a much more realistic modeling of actual conditions from mobile sources.

Jan 1, 2002

By H. J. M. Rose

Arising out of the world energy crisis and the increasing demand for nuclear fuels, the Elliot Lake operation of Denison Mines Limited is currently expanding its facilities to meet its increased contractual obligations of some 90,500,000 kg of uranium oxide between now and the year 2011. The mining of uranium is subjected to increasingly stringent environmental controls by governmental and associated agencies so as to safeguard the health of the employees. A heavy burden of responsibility is thus placed on the Ventilation Department to ensure, through efficient planning and good control, that satisfactory ventilation conditions prevail throughout the entire operation. Management realized at the outset of the present phase of this expansion, that the establishment of a properly organized and administered Ventilation Department would be essential to ensure that long term production goals are achieved within the numerous constraints imposed by existing legislation. The paper describes the formation of the department by recruiting technically competent, but largely inexperienced, ventilation personnel, their practical training programme, the departmental structure and the operational and control responsibilities of the ventilation staff.

Jan 1, 1980

By Simon D. Handelsman

Technical co-operation activities of the Department of Technical Co-operation for Development of the United Nations Secretariat have included the introduction of electronic data processing techniques in mineral sector projects for several years; computers have been provided to countries in Africa, Asia and Latin America. Advisory services are provided to interested developing countries at their request concerning applications for various uses in mineral sector activities. They include advice on appropriate hardware and software depending upon the requirements of the particular Government. The Department's activities in this area are described. The input from a Group of Experts on this subject convened by the United Nations, and their conclusions and recommendations, are also discussed.

Jan 1, 1986

By Wang Yingmin, Xu Zhuyun

There are 3 steps in the process of forming a mine ventilation system, (1) selecting a reasonable ventilation pattern (included pit shaft arrangement); (2) optimizing of the ventilation network and (3) computing and outputting the flow splitting results of the network with the optimal ventilating equipments selected. In the past, the first step was relied on artificial decision-making. In order to design a common ventilation system, some ventilation experts were needed to participate or do some examinations. Even so, the design made was reasonable only for those experts. If there is a mistake in the first step, then even the followed 2 steps are best done, the losses are very difficult to retrieve. So that, the first step is very important. The development of expert systems provided an efficient means and tool for all engineering fields. This paper presents an expert system of selecting mine ventilation pattern and pit shaft arrangement. After testing many times, it is shown that the system can perform the first step of designing a mine ventilation system, and can help the experts doing their study works more efficiently.

Jan 1, 1991

By M. Rossi

The use of service variables in geostatistics (grade-thickness) is common in industry when developing block grade models and geologic resource estimates. This is particularly true in the case of sedimentary and stratabound-type deposits. The approach has proven merits when assessing ore reserves. However, there are cases where its application for preliminary data analysis produces biased estimates. One such case is encountered in uranium disequilibrium studies. This paper demonstrates the inadequacy of service variables when performing uranium disequilibrium studies. Disequilibrium analysis is a necessary preprocessing step when radiation counts are used as raw data to calculate uranium reserves. Typically, a probe is used to obtain the gamma counts from open drill holes. These counts are then regressed (and corrected) against chemical assays obtained from core samples. During this process the grade-thickness variable produces an optimistic image of the relationship between probe grades and chemical (true) grades, causing overestimation of the final geologic resource. The problem is analyzed through a case study.

Jan 1, 1993