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By R. W. Bartlett

Aeration curing, over- a long duration in wet- red stockpiles, shows promise as an affordable pretreatment method for oxidizing gold encapsulating sulfide minerals, and possibly organic matter, in low grade refractory ores. Following aeration pretreatment, the ore is reclaimed, neutralized, and cyanide leached by conventional practices. Large tonnages of subeconomic material, including mine stripping waste, may he converted into ore by this new technology. The results presented show that a successful application of this technology will likely require crushing to about -2 cm (-3/4 in.), followed by aeration in a wet stockpile for long periods, up m three years. Natural convection may he inadequate, hut forced air ventilation, at modest pressures and power consumption, is affordable.

Jan 1, 1991

By Thomas D. Barkand

Investigation of several serious hoisting accidents identified machine brake failure as the most common cause. The recent revelation of this potential hazard has prompted regulatory authorities to require an additional, independent, emergency braking system. As a result of this initiative, a new generation of braking systems have been developed and applied to mine elevators. This paper will discuss the design and testing of an electrical dynamic brake, pneumatic rope brake, and traction sheave brake. The effect of compound braking on hoisting systems equipped with multiple brakes will also be addressed.

Jan 1, 1992

By Tom C. Palanglo, Norbert Maerz

Control of crushing and grinding circuits ideally requires continuous particle size measurements on both in- and outgoing streams. Until recently, size distributions could only be obtained by screening methods, which were neither cost effective, frequent enough, nor timely. Input streams are often composed of large fragments, making screening prohibitive. Optical image processing systems, such as the WipFrag System, have been developed to the point that they are an extremely valuable tool to characterize, control, and fine-tune the comminution process. Although accuracy is less than that of screening, measurements are precise enough to detect relatively small changes in size distributions.

Jan 1, 2000

By James A. Jones

The Doe Run Co. emerged from the depressed lead market of the mid-1980s as North America's leading lead producer. Doe Run was lean and mean but quickly recognized that technology had advanced while the company was held to the belt tightening slump. With the 1990s approaching, Doe Run moved quickly to update its technology and control equipment to ensure its position as an industry leader. Doe Run was formed in 1986 when Fluor Corp. and Homestake Mining Co. combined their lead-zinc-copper assets in Missouri to form a joint venture. Doe Run is now owned by Fluor Corp. A rich history of mining, milling and smelting started in Missouri in 1862 when the St. Joseph Lead Co. was founded. Subsequent acquisitions led to the formation of St. Joe Minerals, which was later purchased by Fluor Corp. Six mines, four concentrators and two smelters are presently being operated, and a secondary lead smelter was recently commissioned. The Viburnum, Buick and Fletcher operations are lead, zinc and copper flotation concentrators, while the Brushy Creek plant is set up to process high copper-low lead ores. This article looks primarily at the process control installation at the Fletcher concentrator.

Jan 1, 1991

By John Durkin, Steven Wirch, Fred N. Kissell, Steven Ruggieri

The Bureau of Mines has developed two expert systems to give advice on coal mine dust control, one for continuous miner sections, and another for longwalls. Prototype versions have been evaluated by coal operators and MSHA. Both systems query the user as to the nature and extent of the dust control problem. Typical questions asked deal with matters such as cutting sequence, current dust standards and characteristics of current dust control techniques. Advice given by the system generally does not focus on a single issue, but may suggest a variety of approaches consistent with the ability of the operator to practically implement what is suggested. Both were written using expert system development software called Insight 2+. The advantages of Insight 2+ for the user are: low cost, IBM-PC compatibility, and the fact that little prior experience with computers is required. For the developer, Insight offers an easy to use production rule language and goal driven structure as well as a wide variety of capabilities.

Jan 1, 1987

By D. M. Muir

Thiosulfate offers a nontoxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32; It is shown that an understanding of the copper speciation and sulfur speciation is required to optimize this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2002

By Khosrow Bakhtar, Robert E. Cameron, Arfon H. Jones

The use of rock simulators in rock mechanics research greatly expands the scope of the problems that can be investigated with physical models. However, the exact reproduction of full scale conditions, or absolute simulitude, is not obtainable on a small scale model. For this to be possible, the scales of length, time, and pressure (or mass) must be changed without altering the theoretical equations that describe the behavior of materials concerned. In using rock simulants for physical modeling of structures designed in rock, the geometry of full scale structure is reduced to a size suitable for the available testing machine. This will require the strength related properties to be scaled down. Simulation should be representative of the in situ conditions. Complete simulation will require that friction parameters and the stress ratios be matched exactly between prototype and model. The procedure involved in application of physical modeling for rock mechanics research is discussed in the following pages. Background, theoretical approach, and anticipated benefits to the research community are also elaborated.

Jan 1, 1986

By R. M. Damodaran

The flotation performance of Florida phosphate rock was evaluated in terms of the mixing behavior of reagents and particulates during anionic conditioning of phosphate slurries. The various conditioning variables that influence mixing, namely, solids loading, agitation speed and conditioning time, were investigated to determine their effect on reagent coating of the particles. The phosphate recovery was used to monitor the conditioning efficiency. The mixing characteristics of the phosphate feed were evaluated in terms of the ratio of the mixing power (P) to the minimum power (Pm) required to keep the slurry in suspension. It was found that mixing conditions govern the conditioning time required to obtain a high recovery. Reagentization was slower at lower P/Pm ratios. At higher P/Pm ratios, the flotation recovery was optimized, and the agitation speed was found to have no significant effect. Optimum mixing conditions were obtained for a74 wt% slurry at an agitation speed of 450 rpm (47 radians/sec). Under these optimum mixing conditions, the collector dosage required for an improved recovery was lower and the conditioning time was shorter.

Jan 1, 1997

By P. Somasundaran, C. C. Harris

The power consumption of stirred-media mills was studied using an approach developed from work on stirred reactors. Evaluated were the relationships of factors such as stirring speed and impeller and tank dimensions on the torque required to rotate disc and pin impellers immersed in dense particulate media. Data collected under carious experimental conditions were analyzed. The results were summarized and presented in the form of characteristic plots, general equations and dimensionless group correlations involving power and modified Reynolds numbers. Special attention was directed towards the rheological properties of the media, which was considered a non-Newtonian liquid, and hence the equation of power-law liquids was employed. A procedure for estimating the parameters of effective viscosity and scale-up guidelines (with respect to power consumption) are proposed.

Jan 1, 1996

By T. Stack, C. Roos, M. Drake, P. Conrad

"This paper presents the evaluation Montana Tech completed for the Western Energy Company Rosebud Mine relating to the benefits of survey data collected using novel technologies over traditional methods for topographic surveys. These technologies include Unmanned Aircraft Systems (UAS), photogrammetry, and laser scanning/LIDAR. Utilizing these technologies, large areas such as reclamation areas and cast blasts can be surveyed in a timely manner for use by the mining operation. The areas that were evaluated were the improvements in the safety of employees and the time required to collect data. In addition, there is also a potential cost savings for the operation, all while not affecting the accuracy of the data that is collected. PROJECT BACKGROUND Accurate topographic survey data is critical to successful surface mining operations. It is used for mine planning and design as well as permit compliance. Currently, employees typically collect survey data using GPS equipment or total stations. These methods can be dangerous, as they require employees to work near large operating mobile equipment, edge of high walls, and on piles of stacked steep-sloped loose material. Aerial and satellite photographs, performed by a contractor, can be used to obtain some of this information, but it is expensive and may not be attainable during overcast conditions. Montana Tech, along with the Rosebud Mine, conducted research on the accuracy, cost, and other benefits of survey data collected using novel technologies. Some of the methods studied include, but are not limited to, Unmanned Aerial Systems (UAS) or Vehicles (UAV), photogrammetry, and laser scanning. These methods were evaluated to determine if these technologies provide mining companies with a safer, cost effective, and accurate method to collect data for surface mining operations. The project scope was to evaluate various surveying techniques to determine which techniques would be applicable for the Rosebud Mine and complete a trade-off study comparing the new techniques with currently used methods. The trade-off study included an analysis of the technological differences between the methods, safety and legal considerations for the new techniques, operational limits, and the costs associated with each technique. Working with the Rosebud Mine team, techniques were selected for field trial and accuracy comparison. This paper presents a literature review of applicable technical papers and a summary of the Federal Aviation Administration regulations for UAS, followed by a study comparing conventional GPS topographic surveys with UAS based systems and laser scanning systems. The comparison of the various methods was broken into the following four categories: operator safety analysis, time comparison, survey accuracy, and cost analysis. After all of these portions of comparison were completed a recommendation was provided based on the evaluation that was performed."

Jan 1, 2017

By Edward F. Fries

Computerized, real -time monitoring had its beginning in the U.S. coal industry in the early 1970's. Over the last 10 years, developments in technology have made systems available that are capable of monitoring and controlling many mine parameters that can increase safety and production. However, situations currently exist where computerized monitoring systems are not being utilized to their fullest capability. They produce reams of printed output that are not sorted in a useful format, and human operators are not able to react fast enough in emergency situations tn tile large amount of information that the systems generate. A solution is the application of an expert system as the interface with real-time monitoring. An expert system would use an extensive knowledge base and human-type reasoning ability to make decisions on optimum strategies. Expert systems have been applied successfully to problems in other industries, and could provide significant benefits to mine information management systems. The use of an expert system with real-time mine monitoring is discussed in this paper.

Jan 1, 1986

By Jiqing Zhang, Jon C. Yingling, Andrzej M. Wala, Richard Ray

The purpose of this paper is to present how Computational Fluid Dynamics (CFD) simulations can be used to study the flow across the main airways of a mine ventilation system. in particular, the flow through the transition zone between the upcast shaft and main fan ductwork was investigated. These studies consider potential design modifications of this transition zone to reduce the energy cost. Although CFD has many advantages, it does not completely eliminate the need for experiments, which are still needed to validate numerical solutions. For this reason, data collected during actual mine tests and CFD simulations are compared in this pa- per. This comparison allows a better understanding of the flow phenomena. Moreover, once the numerical solutions have been validated, CFD can be used with better confidence to predict the effect of changes in ductwork configurations on energy losses. CFD reduces the number and cost of tedious experiments, while enabling a broader scope of design comparisons.

Jan 1, 1997

By Raymond S. Shrode

Limestone and dolomite production is of significant importance to the Baltimore and Ohio Railroad. Except for coal, more tons of limestone and dolomite are moved by the Railroad than any other mineral raw material. In the territory served by the Railroad, these materials are produced from every geologic system from Cambrian through Pennsylvanian. Some of the operations produce premium stone acceptable for high-specification steel and chemical use; at others, the stone finds application as aggregate materials and for cement manufacture. The Railroad is interested in seeing continued production from the operations it now serves, and in serving operations in a way mutually beneficial to the Railroad and to the producer. In working with producers, the importance of geologic knowledge in prospecting and development of deposits has been clearly recognized. In turn, knowledge of the economic and technological facets of production and consumption is needed for the geologists to participate with maximum efficiency.

Jan 1, 1966

By D. W. Ashman

Today the electrolytic zinc industry is facing unprecedented environmental pressure and low metal prices. Zinc plants have to decide how they will dispose of iron residues in an environmentally friendly way without major capital expenditures. Only low-cost producers will survive, so companies must continuously improve to stay competitive. Therefore, the challenge of the process engineer is to find innovative solutions to the industry's problems. This paper reviews the status of electrolytic zinc processing and provides some insight into how the industry will respond to the pressures facing it

Jan 1, 1993

By Frank F. Aplan, Robert S. Thomson

A placer ore jig, typically used to recover fine gold, tin and diamonds from alluvial ores, has been modified to remove fine pyrite from minus 6.4 mm (-114 inch) coal. In parallel tests, it proved to be far superior to two conventional coal jigs, the Baum and the Baum-feldspar, in removing fine pyrite from coal. The Pan-Am placer jig was found to remove essentially all of the +28 mesh pyrite and from 99% to 90%, decreasingly, in the 28 to 200 mesh range. This jig also showed a superior performance to the Baum-Type jigs in removing fine coal from its associated refuse. The superiority of the Pan-Am placer jig is related to the strong emphasis given on the suction stroke and, hence, on consolidation trickling, whereas the Baum jigs principally emphasize the pulsion stroke during jigging.

Jan 1, 1995

By J. R. Mattern

The engineering geology of the Rio Tinto Borax Boron Mine creates challenges in providing practical slope design recommendations to mine planning engineers. Low strength sedimentary units interbedded with very low strength lakebed clays surround the orebody. Faulting has offset and juxtaposed these units into variably adverse orientations, while groundwater is compartmentalized both vertically and horizontally within fault blocks. A collective program of geologic data collection, geomechanical strength testing, geologic modeling, slope depressurization, confirmation of underground stope locations, and documentation of slope behavior provides vital information for design investigations and sensitivities. Analysis results lead to risk assessments and operational procedures that add value to the business by optimizing slope configurations and minimizing risk.

Jan 1, 2004

By Richard E. Ray, George N. Aul, Fred Garcia, William P. Diamond

Increasing longwall panel dimensions, particularly face width in gassy coalbeds, may result in unexpected increases in methane emissions. To investigate this problem, continuous longwall face emission monitoring studies were conducted at two adjacent mines operating in the Pocahontas No. 3 Coalbed, where longwall faces were to be extended from 229 to 305 m (750 to 1,000 ft). It was predicted by regression analysis of methane emissions data from 229 m (750 ft) wide longwall faces that extending faces to 305 m (1,000 ft) would increase methane emission rates by only 7 percent (0.6 m3/min (20 cfm)), to 8.6 m3/min (304 cfm) at the VP-1 Mine. In contrast, it was predicted that extending faces at the VP-3 Mine could increase methane emissions by as much as 13 percent (1.8 m3/min (65 cfm)) to 16.1 m3/min (567 cfm). The geologic and mine design factors in¬fluencing the variation in face emissions between the two mines will be discussed.

Jan 1, 1997

By Kenneth L. Schellie

In preplanning the reclamation of a pit or quarry the geology of the site is the name of the game! The planner must know the parameters of the deposit, the quantity and kind of earth materials to be removed, and the amount and nature of the materials to be left behind or wasted as the result of processing the marketable product. With many states and most local jurisdictions requiring reclamation plans prior to the issuance of mining permits, the need for accurate and complete data concerning the geology of the site becomes increasingly important. The producer need only know that marketable materials are available in sufficient quantity to make the mining operation economically feasible-the planner, in order that the land may be reshaped for a useful purpose, must have reasonably precise information as to the dimensions and configurations of the pit or quarry following extraction and the amount and type of materials available on the site (or in some cases offsite as well). Therefore the geology of the site is of major significance in determining the land forms and use capabilities of the property upon completion of the mining process.

Jan 1, 1974

By Alberto Sarmentero

Venezuela, once a world's top gold producer until 1886 Witwatersrand discovery, did let fall its role then because of a serious lack of infrastructure and population, and lately (since World war II times), because of discouraging mining and taxation laws, laying upon an oil prizes bonanza. Recent research leading to estimates of about 5.000 mt. of gold, mainly related to the greenstone belts of the Guiana Precambrian shield outcropping in Venezuela, are opening the scope for both Government and international investing and mining companies, for gold exploration and development projects in the country. This paper overviews Venezuelan Gold mining industry, as seen from the point of view of a participating mining company.

Jan 1, 1989

By Donald E. Dickie

At Sifto Canada's Goderich salt mine near Goderich, Ontario, the stress control method of mining was introduced to overcome increasing roof failure problems. After successful testing, the conventional room-and-pillar mining method was converted entirely to the stress control method. This conversion has successfully stabilized the ground, increasing the extracton ratio from 38% to 50%. At the same time, it reduced the ground control and rehabilitation cost by more than 80%. The success of the conversion is due to the quantitative technique of mine analysis that was developed to ensure that the conversion was safe and reliable. A finite element model of the ground was constructed to predict and validate the safety of the stress controlled mine opening. A system of in situ stress-property measurement instruments was developed to obtain input data for the computer model as well as to evaluate its output quantitatively with regard to time and location. History of roof problems Severe roof safety problems have been encountered at Goderich Mine since it opened in 1959. These problems continued into the 1980s. Following excavation, the roof strata started to deteriorate by slabbing. Even after roof rehabilitation, deterioration continued to progressively higher roof elevations, requiring repeated rehabilitation. The operational impact of these roof failures was severe, ranging from a considerable safety hazard to major production interruptions.

Jan 1, 1993