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By William C. Smith

Roof support, an important aspect of ground control, involves maintaining roof competency to ensure a safe and efficient mining environment. Wide variability in rock quality and stress distributions requires a systematic approach to roof support design that satisfies specific goals. The success of past roof sup-port in reducing the incidence of roof falls has been primarily attributed to safer roof bolting practices. However, roof falls continue to be the number one occupational hazard in underground coal mines. This U.S. Bureau of Mines report presents a general overview of roof bolting and other roof support methods used in the United States. Characteristics of bad roof and associated roof failure theories are briefly presented as background to roof support. Methods of detecting and monitoring roof behavior and/or bolt performance provide essential feedback on roof support requirements. A discussion follows on roof bolt design that assimilates roof and support parameters into useful equations or nomographs to help decide what bolt types to use and how they should be installed under different roof conditions.

Jan 1, 1993

By E. A. Rychkun

Mining and environmental objectives have traditionally been in conflict. This conflict reflects a delicate balance between the need to spend money to protect the environment, and the need to save money by extracting minerals efficiently. In an increasing number of cases, profit margins diminish rapidly with new environmental regulations and reactionary measures. Forced cleanups and increasing restrictions are unwelcome expensive processes. A practical solution lies in planning rather than reacting. This requires the ability to precisely quantify and qualify environmentally sensitive problems by providing effective engineering tools to model, visualize and analyze subsurface conditions. Prevention of environmental conflicts, and effective cost control are both rooted in the mining company's ability to construct accurate models, monitor changes, assess contamination risks and to design effective remediation plan. This paper presents a case study where these issues are addresses through the application of a new and innovative technology.

Jan 1, 1993

By A. H. Balch

A physical elastic seismic model, based on the Peoria oil field was constructed and used to produce multi mode cross-borehole seismic data. Because this was a physical model, it was necessary to deal with a complex wave field consisting of compressional waves, shear waves, and converted waves. The recorded raw data were complex, have no resemblance to the inter-well geology, and were difficult or impossible to interpret. These unintelligible data sets were extensively computer processed. Detailed, accurate, images of the inter-well structure, and reflecting horizons were obtained as a result of this processing. This investigation demonstrates that excellent, accurate images of the inter-well geology can be obtained by skilled seismic cross-well data acquisition and extensive careful computer processing.

Jan 1, 1993

By R. V. Ramani

One area of study in the Coal Mine Injury Analysis project was to illustrate and enhance the ability of mine safety management personnel to apply analytical techniques to injury experience data and to justify requests for funds for safety enhancement actions on a cost/benefit and other quantitative basis. Four volumes of this final project report detail (1) the objective and scope of the mine safety management research, (2) the results of literature review, and case studies, and (3) models developed for mine safety management. The four volumes are titled as Volume III: Mine Safety Management, Volume IV: Analytical Techniques for Mine Safety Management; Volume V: Mine Safety Management Case Studies and Volume IX: Training Cost Model. In this volume, the following material is presented: (i) review of related literature, (ii) mathematical models to perform quantitative analyses of accident/ injury experience data using the tools and techniques of risk analysis, time series analysis, and the Markov process, and (iii) descriptions of the HDBSEL and ACIM programs which are used to perform accident/injury experience analyses and cost analyses, respectively.

Jan 1, 1993

By Jeffrey S. Walker

Abandoned underground mine openings are susceptible to collapse because of the mining methods used, the character of the overburden, and the typically large, wide entries with minimal roof support. The final effect of the collapse of the underground workings is surface subsidence. To reduce the probability of subsidence, methods to backfill the mine void with various types of materials have been developed. This U.S. Bureau of Mines report describes the available technologies for subsidence abatement and discusses their operation and application. The basis of these abatement methods is the replacement of the mined material with mine waste. Backfilling of mine voids is the most common method of stabilization used to abate subsidence and protect surface structures. Hydraulic flushing and grouting, using remote methods from single or multiple boreholes, are the most often-used methods for the placement of backfill material. Other subsidence abatement techniques are available and may be more appropriate under different conditions. These other techniques include pneumatic stowing, either by in-mine or remote methods, and various point support methods that do not completely fill the mine void and are used for the protection of small areas of the land surface and surface structures.

Jan 1, 1993

By V. P. Bystrov

Vanyukov process has been developed and investigated in Russia over the last 25 years. It has been established that various kind of material could be treated in Vanyukov process. The results of the pilot plant trials as well as industrial experience are presented in this paper.

Jan 1, 1993

By Chris M. Healey

"Abstract- The Jasper Gold mine in northern Saskatchewan produced a total mill feed of 140 127 tonnes at an average grade of 19.0 g/t Au. Both diamond drilling and chip samples from under­ ground workings returned extremely high values, up to 12 851 g/t (375 oz/I) Au over 0.10 meter from a chip sample. In the presence of such extremely high grades, the accurate estimation of reserves is a major problem.ln the first part of this study, production data from the mine were used to evaluate the results of a variety of reserve estimation techniques in this environment. In two out of three cases studied, indicator kriging with assays cut to 342.9 g/t (10 oz/I) gave extremely good results. In the third case, however , indicator kriging gave unacceptable results. Instead, lognormal kriging of uncut data gave the best results.Secondly, from the same database, a number of drill-hole spacings were simulated, and reserves estimated from the simulations. As may be expected, the results of this analysis show increasingly better results with tighter drill-hole spacing. However, even with a 5 m by 5 m spacing the variation from actual grade was quite large. This is not a systematic under- or over-estimation of grade, rather a random scatter of results .The results of this study show very clearly the problems of deriving good estimates of reserves when extremely high-grade samples are encountered. There is a high degree of randomness to this database, so reserve estimation in this situation will remain a high-risk operation."

Jan 1, 1993

By Michael E. Stout

M.A. Industries, Inc. has developed and is now offering on a commercially available basis, complete systems to recover and recycle lead from spent SLI batteries. The system begins with the breaking and separation of the component parts of the batteries and subsequent treatment of the effluent water produced by this operation. The recyclable materials recovered from this process are metallic lead, lead paste and polypropylene. The lead paste is introduced into a process to convert it from a lead sulfate to a lead carbonate. The process also regenerates the salt solutions into reusable carbonate. The lead carbonate is then leached into an acid bath where it is later recovered by a proprietary electrolytic process. The metallic lead is recovered in a short rotary furnace producing metal for further refining and alloying. The polypropylene is further washed and then introduced to a reclaim extruder along with the proper modifiers and additives. The resulting resin can then be sold on the open market to injection molding processors. This complete system greatly reduces the amount of waste to be disposed of and completely complies with all applicable EPA guidelines.

Jan 1, 1993

By Charles Vaught, Henry J. Kellner, Michael J. Brnich, Henry P. Cole, William J. Wiehagen

In 1985, U.S. Bureau of Mines and University of Kentucky researchers began a series of studies relating to self-contained self-rescuer (SCSR) donning proficiency. During the next 5 years investigators examined a number of factors that have a bearing upon miners' ability to put on and use the apparatus in an emergency: the procedure being taught; availability and utilization of training models; opportunities to practice; hygiene; and on-the-job training. This report presents an overview of that research. It is concluded that companies should adopt a hands-on training protocol that allows them to integrate SCSR donning practice into other workplace routines such as fire drills.

Jan 1, 1993

By B. Kolonja

A SIMAN and CINEMA PC-based simulation model was developed to simulate and animate the truck-shovel operations of surface mines. The model is capable of simulating one mathematical dispatching strategy using linear and dynamic programming and six heuristic dispatching strategies. Data were collected from an actual operating mine through time studies and analysis of historical records. The statistical analyses were performed and appropriate theoretical distributions were fitted for various time events in the truck-shovel work cycle. The model was then applied to study overall impact of these dispatching strategies on constrained and unconstrained mine productivity. The simulation/animation model developed in this study seems to be an efficient planning tool for choosing optimal fleets and finding an 'optimal" dispatching strategy to produce an equilibrium between "the quality and quantity of production.

Jan 1, 1993

By Thomas P. Battle

Titanium is the ninth most common element in the Earth's crust, yet only in this century has titanium come into use as an engineering material, particularly in aircraft structures, as the metal, and in pigments, as the dioxide. In this presentation, the metallurgical aspects of processing titanium-containing raw materials will be reviewed. Particular emphasis will be given to the ores and beneficiation techniques which lead to the production of titanium dioxide pigment, which accounts for over 90% of world titanium production.

Jan 1, 1993

By K. Thomson

The Mule Canyon gold deposit, located 14 miles ESE of Battle Mountain, Nevada, was discovered in 1986 as the result of a GFMC grass-roots exploration program. Drilling to date has identified six discrete orebodies which contain a demonstrated gold reserve of 8.487 million tons at an average grade of 0.136 oz/ton, totaling 1,152,000 ounces. Mineralization is associated with argillic alteration and silicification, localized along NNW trending high-angle faults within Miocene basaltic andesites. Trace element geochemistry at Mule Canyon is typical of upper level hot spring precious metal systems, displaying elevated Ag, As, Sb, Hg, and Se.

Jan 1, 1993

By A. Warczok

The heat transfer coefficient between liquid slags and solid surfaces is important for the design and operation of metallurgical reactors. An experimental technique developed for the purpose of measuring the heat transfer coefficient between liquid slags and solid metals is described. During the initial heating up of a Ni cylinder upon immersion in a liquid slag, a layer of frozen slag initially forms, then melts. The heat transfer coefficient measured during the initial rapid heat-up of the Ni cylinder, is approximately twice as high as the heat transfer coefficient measured during the final heat-up of the Ni cylinder subsequent of the liquidus temperature of the slag. The technique was tested in various melts i) NaNO3, ii) NaCl, iii) Na3AlF6 and iv) 2FeO*SiO2, giving consistent results. It was found that the heat transfer coefficient increases with increasing bath superheat and stirring. The heat transfer coefficient during the heating up following complete remelting of the frozen slag, is related to the slag superheat(AT) and the specific stirring energy(W) per kg of slag(E) as follows.

Jan 1, 1993

By S. Rajendran

Much advance has been made in offshore hydrocarbon exploration and exploitation in India. But the same amount of success could not be achieved in the case of other offshore minerals which are amenable for mining. However, employing present technology, there should not be any difficulty in successful exploitation with minimum environmental hazards. A demonstration is provided by considering the conditions prevailing in the Kerala offshore (southwest coast of India) scenario of monazite, ilmenite, phosphatic mud and calcareous deposits. Mud banks are unique phenomenon of the Kerala coast during monsoon season. Acting as barriers to waves, mud banks protect portions of the beaches from being eroded and trap sediments from either side facilitating growth of adjacent beach. The easy minable possibilities of the phosphatic mud during non-monsoon season with less pollution hazards and dumping back the waste material after processing for phosphate at the breaker zones to reduce the erosional effects on the coast make the exploitation economic and ecofriendly unlike the benefication of the lowgrade phosphate ores on land on a comparatively larger area and subsequent crushing, transport and resulting pollution.

Jan 1, 1993

By R. H. Sergent

The interest in using halogens for extracting precious metals from ores has increased due to changes In ore characteristics, environmental concerns and regulations. The rediscovery of halogen leaching capability has been the topic of these and other writers1-30. Much work has been done on the performance of bromine, chlorine and iodine5-29. Of these, bromine and chlorine look most promising. Iodine is quite expensive and sometimes forms an Insoluble film on a precious metal surface22,23. Little experimental work has been published on the relative performance of bromine versus chlorine. The Pourbaix diagrams for the halide leach system (see Fig. 1-4) Indicates a significant stability advantage for bromine In forming complex ions with gold. This should result In greater extraction of gold under similar leach conditions and Is evaluated In this work. The regeneration of halogen from a spent leech solution is a critical requirement for an environmentally acceptable halogen leach process. Bromide can be oxidized In-situ to bromine ~ adding chlorine or ozone2,31. Bromide like chloride can be oxidized In an electrochemical cell to produce halogen on demand 13,15,17. Bromine clearly offers a number of possible regeneration pathways. This work strives to compare the relative ability of chlorine and bromine to extract gold from partially and fully oxidized ores. A commercially pressure oxidized sample was evaluated under a number of experimental conditions. The autoclave feed ore from the same mill was also evaluated after complete oxidation In a laboratory autoclave.

Jan 1, 1993

By T. Shibaraki

A new larger, more efficient and economical Mitsubishi furnace line at Naoshima was put into operation in May 1991. Naoshima Smelter had produced previously about 230,000 mtpy anode copper with two smelter lines, i.e., a conventional reverberatory furnace line and Mitsubishi furnace line, which had been shutdown at the same time of the start up of the new smelter. At the beginning of the operation, there were several initial problems at the area of off gas trains and feeding system. By overcoming them now the process has been continuing satisfactory operation at the design rate. The paper describes about the design concepts and the actual operation of the new smelter.

Jan 1, 1993

In cold regions rinsing of spent cyanide leach heaps is stopped during winter and is resumed again after snow melts. The effect of this idle time on the overall cyanide removal process was studied in this work. Samples were collected for rinsing tests from one heap at the Ryan Lode Mine of Citigold Alaska, Inc., near Fairbanks. The material was tested for cyanide removal a large column, 1.22 m high by 20 cm square, and in a small column, 1.22 m high by 10 cm in diameter. The rinse water was analyzed at regular intervals to determine the rate of cyanide removal from the solids. It was found that diffusion plays a major role in the removal of cyanide from the ore particles. Calculations showed that the insulating effect of the snow cover on the heap provides an excellent moderates the interior temperature of the heap, and would be expected to help the progress of the diffusion reaction during winter. The result expected result wil1 be higher cyanide values reporting to the rinse water after snow-melt.

Jan 1, 1993

By Joon H. Jang

At a selected pH, hydrothermal oxidation of chalcopyrite was carried out under controlled F+,, at elevated pressures and temperatures (172-200°C) by balancing the rate of oxygen injection against the rate of consumption. Chalcopyrite was converted to covellite (CuS) and digenite (CU1.8S) with rejection of iron and sulfur to the solution. Covellite forms in the first stage, followed by nucleation and growth of digenite in the second stage. The effects of rapid and slow injection of stoichiometric quantities of oxygen are compared. Both the covellite and digenite form a porous layer occupying the same volume as the original chalcopyrite grain. An electrochemical kinetic model is presented to correlate the observed results.

Jan 1, 1993

By Zhang Hengzhong

Based on thermodynamics of surfaces and a proposed two-dimensional state equation for surfaces, the relationship between the surface tension (Y) of a solution and the activity (a1) of its component (i) was derived: (1/Y)r2-.¬E (ai/Yl) The derived equation was verified with reported experimental data of water-alcohol systems and water-acetone system, the calculated results showed astonishing coincidence with experimental. Applications of the equation to the five matte systems Cu2S-FeS, Ni3S2-FeS, FeS-PbS, Cu2S-PbS and FeS-Cu22S-PbS also demonstrated that at given matte compositions the calculated surface tensions agreed with experimental fairy well.

Jan 1, 1993

By P. K. Songfack

The transport of slurry within the ball mill depends on the peripheral velocity and porosity of the ball charge. Residence time distribution and mill hold up are of-ten used as indicators of the mode of transport. In this work, the transport problem is tackled via direct simulation of the three dimensional motion of the ball charge. In doing so, the following quantities are calculated: (i) ball size distribution as a function of the distance from the feed end of the mill (ii) mean peripheral and longitudinal velocity and longitudinal velocity of balls of different sizes, and (iii) the spatial distribution of porosity within the ball charge. Hence, the problem of transport is handled as a motion of part of the slurry with the ball charge and part as hydrodynamic flow through the porous structure.

Jan 1, 1993