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By Andrew Griffiths

The emphasis in the title of this paper should be placed on the world "Total", since the detoxification of cyanide in its free and weakly-complexed form with H202 has already found application in many areas, including the treatment of mining effluents. One of the most common forms of cyanide found in gold-mill effluents is hexacyanoferrate (usually ferrocyanide), which is included in measurements of total cyanide but is too stable to be oxidized by H202 or any other conventional oxidizing agent. This has led to the view that H202 cannot be used to detoxify effluents containing hexacyanoferrates, when a limit has been set on total cyanide. A process is described in this paper which does meet this requirement, and which has already been demonstated in two Canadian gold mills. Before describing the new process, the terms "free", "total" and "weakly-complexed" cyanide will be defined as they are used in this paper.

Jan 1, 1998

By D. Ince

Flotation of dolomite from apatite was investigated, using dodecylamine hydrochloride or sodium oleate as the collector, with and without inorganic modifiers such as sodium chloride. Separation of dolomite from apatite was anticipated from the single mineral experiments under various pH and collector concentration conditions. Flotation selectivity in the mixtures, however, was found to be limited. Attempts to control the flotation response of these minerals by addition of salts such as NaCl and KCI indicated that selectivity is possible. The presence of sodium chloride was determined to depress apatite flotation using sodium oleate, leaving dolomite flotation unaffected (Moudgil and Ince, 1989). In this paper, conditions for optimum separation and the effect of major parameters on the desired selectivity are discussed.

Jan 1, 1992

By John C. Edwards, Robert C. Bates

Results are given of a mathematical study by Bureau of Mines personnel of overpressurization ventilation effects in underground uranium mines. The mathematics and computer codes make it possible to analyze many facets of transient and steady-state radon diffusion with Darcy flow. Rapid changes in radon flux occur after imposing a pressure differential across the model. Flux into the model mine drops to near zero and then increases to the steady-state level, while the sink flux increases rapidly and then drops slightly to the steady-state level. Magnitudes of mine flux decreases and sink flux increases are dependent upon the distance from the mine to sink, permeability, and amount of overpressure. Current work on more complex models is also described.

Jan 1, 1981

By R. P. Upadhyay

The Deserado Mine, located in northwest Colorado, is an underground coal mine designed to produce 1.225 million tons (1.35 million short tons) of clean coal per year for the Bonanza Plant located in northeastern Utah. Coal is transported to the power plant via a 61 kilometer (38 mile) captive railroad. Most of the surface facilities and the stationary underground equipment is controlled and continuously monitored by the computers located at the surface control room. In addition to system control, the computer also continuously monitors vital environmental conditions using sensors located at various critical locations underground. The system's advantages are increased mine productivity and safety.

Jan 1, 1988

The present contribution examines the main components of a sustainable land reclamation program applicable to surface coal mines and the environmental threats that hinder the transition to sustainable land management. It compares the main ?waste streams? that cause adverse impacts to the environment with the so-called ?best available technologies and managing practices? that are proposed by organisations with high expertise in land management. Also, it addresses the environmental and socio-economic indicators that should be monitored in order to assess the results of the land management program and to allow remedial actions and continuous improvement. Based on the Greek lignite mines experience in land reclamation, this paper presents the common weaknesses of the land management programmes and proposes an improved communication scheme that moves things towards sustainability. This scheme is based on a more rational exploitation of the available economic resources and a constructive dialog between the mining companies, the local authorities, the state institutions and other stakeholders.

Jan 1, 2003

By Lynn B. Hales, Randy A. Ynchausti

Object-oriented technologies have been developed to more closely model the way we think about the world and our natural approach to solving problems. Higher levels of abstraction, generalization and classification are benefits of an object-oriented approach. Object-oriented programming, design, and expert systems are part of this technology which is shaping the future of real-time supervisory control. Goals of real-time supervisory control systems include: minimizing variations in process operations, improving efficiency, maximizing production, and implementing procedures for starting and stopping the process. Incorporating object-oriented technology in design, development and implementation of real-time supervisory control systems provides new opportunities for these tasks. This paper discusses some of the opportunities and challenges of implementing real- time supervisory control using an object-oriented expert system for a rougher flotation circuit

Jan 1, 1993

By S. Srinivasan

Traditional pit optimization techniques cannot take account of the requirement to blend ore in order to produce a saleable product, as is the case for iron ore, coal, limestone and other industrial minerals. Various techniques are proposed to overcome the deficiencies, many of which have been tested. The techniques in general involve the combined application of pit optimization and blend optimization techniques.

Jan 1, 1996

By Douglas E. Rawling

The successful genetic manipulation of T. ferrooxidans is partly dependent on an understanding of the molecular biology of the organism. For optimum controlled expression of foreign DNA in T. ferrooxidans it is important that donor DNA is derived from bacteria that are genetically similar to T. ferrooxidans or placed under the control of T. ferrooxidans transcriptional promoters. Several structural genes and their controlling regions from T. ferrooxidans have been isolated and their DNA sequenced. These include the genes that encode the nitrogenase enzyme (nifHDK genes), glutamine synthetase (glnA gene) and the recA gene. These genes and the identical genes from a wide variety of other bacteria have been compared at levels of DNA sequence, protein sequence. Where possible, gene expression as well as transcriptional control and protein function of the cloned genes were tested in the enteric bacterium Escherichia coli. The two genes involved in nitrogen metabolism were either expressed or possessed the necessary elements for expression in other bacteria. In contrast the recA gene was not expressed in E. coli from its own promoter. The two gene products that would be tested (glnA and recA) were fully functional in E. coli. The relevance of these findings to the genetic manipulation of T. ferrooxidans is discussed

Jan 1, 1989

By M. Li, J. D. Miller

Existing process technologies for the production of soda ash from trona involves dissolution in hot brine, sedimentation and filtration for the removal of impurities, and subsequent crystallization for the recovery of soda ash. In this regard, mining and operating costs, particularly energy costs, are higher than desired. A preferred processing strategy might be to remove gangue mineral contaminants from the plant feed prior to dissolution in hot brine. Such a preprocessing strategy at ambient temperature and pressure has been limited by the lack of satisfactory process technology. Now based on recent results from laboratory research at the University of Utah it seems that the run-of-mine trona ore can be treated at ambient temperature and pressure using a special flotation procedure to separate the gangue minerals and make a trona concentrate with a purity of almost 99% trona at a recovery of more than 97%. The concept of such a new processing strategy is discussed with respect to current plant practice.

Jan 1, 2002

By P. M. Godinho

The debut of the sustainable development concept in the political arena, and the publication of Our Common Future in 1987, represents the starting point of present concerns and efforts associated with the sustainability of the ecosphere and its ecological and human subsystems. The sustainable production and consumption of natural resources, in particular mineral resources, represents a central aspect of the problem. In this context, an important goal has been to develop sophisticated management systems, which consider sustainability principles, in organizations within the system of minerals and metals (SMM). The development of indicators is only part of this challenge. The extractive industries (EI) as an important stakeholder of the SMM (should) have similar priorities. If embraced, this challenge offers great opportunities, one of them being the potential for advancing the understanding of how these organizations learn and change. The identification of its main determinants offers, in theory, the possibility for their management and a faster achievement of the sustainability levels to which they (should) aspire.

Jan 1, 2007

By C. H. Bucknam

A suite of ore and waste rock materials was selected for the interlaboratory testing of combustion-infrared ("Leco") methods used to estimate carbonate and sulfide minerals present in test materials. The objective of the study is to develop ASTM standard methods to be used for metallurgical characterization of ore, acid drainage prediction for ore and waste during ore body evaluation, and for ore and waste control during the active mining of ore deposits. The results may be interpreted for classification of the materials according to their carbonate-sulfide or acid-base characteristics based on net carbonate value (NCV). The test materials were processed by x-ray diffraction and x-ray fluorescence (XRD-XRF) at Newmont Metallurgical Services (NMS) to obtain a semiquantitative mineralogical composition. Results of the interlaboratory testing for total carbon-sulfur, pyrolysis loss carbon-sulfur and hydrochloric acid residual carbon¬sulfur are compared with the mineralogical composition to aid in interpretation of the NCV classifications of the samples.

Jan 1, 2002

By Raj K. Singhal

This paper is a report on a task force study dealing with many facets of computerization. The primary mandate of the task force was to examine the software and hardware currently available for application relating to reserve estimation, mine planning, economic evaluation, equipment selection, production scheduling and composite mine simulation and to evaluate how adequately the software fulfills the user needs in surface mining of oil sands and coal. To meet its objectives the task force consulted extensively with the users, developers and suppliers of hardware and software. The paper outlines the approach taken by the task force to fulfill its mandate, summarizes its findings and presents some pointers which might be useful to others considering this type of evaluation.

Jan 1, 1986

By M. Carvalho, R. Bicallho, M. Queiroz, R. Gomide, V. Silva, R. Toubes

Since it is becoming increasingly important, from an environmental viewpoint, to minimize blast vibrations induced in urban dwellings and improve rock fragmentation in order to reduce costs with loading, transportation crushing and grinding, a cooperative research project was established between Companhia Vale do Rio Doce - CVRD and the Blasting Research Group in the Department of Mining Engineering at Escola de Minas - UFOP to investigate which elements interfere on ground vibration, air blast, flyrock and rock fragmentation related to rock blasting activities at Conceição Mine, located in Itabira city, state of Minas Gerais, Brazil. This research also involved development of a new explosives formulation in order to minimize the total blasting cost. This paper presents the general scheme of the research running from May 1995 to May 1997 and a summary of the results obtained in the field tests that were carried out in this mine.

Jan 1, 1998

By S. K. Kawatra, M. T. Rusesky, T. C. Eisele, D. X. Zhang

It has been observed in some mineral processing plants that grinding circuit efficiency varies seasonally, such as in some plants which are located in the northern US and Canada and undergo large seasonal temperature changes, with the grinding circuit efficiency different between summer and winter. This indicates that the temperature of grinding circuit slurry has a noticeable effect on grinding performance. The effect has rarely been studied. To this end, an investigation to examine the effect of changing temperature on efficiency and determination of the mechanism responsible has been carried out. Plant investigations and laboratory experiments have been conducted in order to study hydrocyclones. It was demonstrated that when the pressure drop is held constant, the d50(c) size decreased approximately linearly with increasing temperature, while the shape of the reduced efficiency curve remained nearly constant. This effect was determined to be due to changes in slurry viscosity with temperature.

Jan 1, 1990

By C. Orf. Chukabarah

Erratic behavior in convergency during iterative numerical-method evaluation of mine ventilation fan characteristic curves is one of the common problems encountered in mine ventilation network analysis. Five different sets of mine fan data points, that had resulted in unsatisfactory fan characteristic curves, were re-analyzed in the present study, using an embedded mine network optimization computer program. Current results revealed that all five fan data sets not only can be satisfactorily fitted as Yang (1992) did with MFIRE subprogram, but can further be optimized with unique solutions as implemented in the present study. It was concluded, inter alia, that the improved MFIRE-based mine fan curve-fitting computer subprogram (SPLINE) produces satisfactorily similar fan curves as SPSS-based curve-fitting algorithms, including when the latter method uses either standardized or unstandardized fan curve data sets.

Jan 1, 1993

By R. H. Sailors

During the last 15 years, the North American Mining Industry has experienced increasing usage of cast high chromium white iron grinding media in wet grinding applications. First introduced into the cement industry (klinker grinding) where wear rate reductions of four or five times have been realized compared to steel balls, this same grinding media serve the iron, copper, and phosphate markets by resisting not only impacts and abrasion, but also corrosion which occurs in wet grinding. In these markets, single mills containing 250,000 kg of grinding balls are not un-common and hence the economic potential with respect to lower wear rates can be significant. Add to reduced wear rate the increased production efficiency that is possible and it is readily understood why much of the mining industry uses cast high chromium grinding media. Metallurgically, the alloys used consist of a martensitic matrix containing hard M7C3 eutectic carbides. Carbon (2.0 to 3.5%) and chromium (12 to 277.) are characteristically used to arrive at the desired properties.

Jan 1, 1989

By H. S. Soto

The exact reasons that explain the low recoveries of coarse particles in conventional flotation machines are not clear. Being a concern for only a couple of mineral industries comparatively very few studies have been devoted to the problem of coarse particle flotation. Coarse particles flotation is particularly important in potash and phosphate beneficiation. Potash concentrates with particles larger than 1-2 mm do not require additional compaction or recrystallization and receive a premium price. However, recovery of this size particle in conventional flotation cells is very low, and therefore, the coarse floation tailings have to be reground and refloated to produce, at a higher cost, a less desirable concentrate. In phosphate beneficiation deslimed coarse ore (nominally l4x35 or l6x35 mesh) is normally treated separatedly from the finer (35x150 mesh) ore. Concentration by conventional froth flotation alone yields very low recoveries, and therefore, additional processes such as agglomerate flotation in tables spirals and belt conveyors have to be used ( Moudgil and Barnett 1979). Fatty acids and fuel oil used in phosphate flotation have a moderate level of selectivity but considerable amounts of sand report to the froth product, thus concentrates have to be further upgraded by a double flotation process. Concentrates from the anionic circuit are scrubbed in an acidic media to desorb the collectors and then refloated in a cationic circuit to eliminate the fine silica (Lawver et.al. 1978). In this paper the reasons that explain the low recovery of coarse particles in conventional flotation are discussed. A flotation column modified according to the main conclusions of this discussion is tested with two coarse phosphate samples.

Jan 1, 1989

By Eugene F. Casey, John G. Ruggiero

INTRODUCTION Construction of tunnels in urban areas, especially reclaimed areas, pose many problems. The Red Hook Intercepting Sewer Tunnel, Contract 1A is a portion of the Red Hook Water Pollution Control Project located along the Brooklyn waterfront in New York City. This contract required the construction of a 2620 meter long (8600 L.F.), 3 meter (10-foot) diameter soft ground tunnel, eight Tunnel Manholes, nine Regulator structures, four Diversion and Tidegate structures and 765 meters (2500 L.F.) of branch intercepting sewers of diameters between .30 meters (12 inches) and 1.8 meters (72 inches). The construction contract bid price was $62 million with a duration of three years. The tunnel route crosses over five sets of operational twin cast iron subway tubes with clearances ranging from 4.3 meters (14 feet) to as small as 0.35 meters (14 inches). The route of the tunnel traverses historically interesting areas which have been reclaimed over the last 200 years. This paper is a case history describing the contractor's methods utilized to successfully advance the work through the above problem areas. LOCATION The Red Hook Intercepting Sewer Tunnel is located in the Borough of Brooklyn of New York City. The route is

Jan 1, 1981

By Thomas Fliess, Klaus-Christof Ritter, John R. Sturgul

The optimum flow of materials through a smelter is an extremely important phase of the mining cycle. A typical copper smelter will have up to $US 1,000,000 per day of copper being processed. The motion of the overhead cranes in moving the ladles filled with copper matte and slag from furnace to furnace is prescribed but there can be numerous variables to consider. Some of these variables to the system can be: the speed of the overhead cranes, the number of cranes, the size of the ladles, the size of the furnaces, the number of furnaces and the sequence in loading the furnaces. A simulation model was constructed of a working smelter in the SW of the United States. The model has been used to study the effect of varying parameters of the system. The program runs as follows: an input menu appears on the PC screen and the user can navigate through it and change any of the data; the simulation takes place and the results of the simulation sent to a data file. Animation of the system then is shown on the screen in "cartoon" fashion. The software chosen for the simulation was GPSSI H (') and PROOF Professional (') for the animation. The model presented here is believed to be the first reported simulation and animation model for a complete, working smelter.

Jan 1, 1996

By John A. Shuster

INTRODUCTION Controlled ground freezing for mining and construction applications has been in use for over a century. Despite the great technological evolution which has occurred during this period, ground freezing is still used on projects today with much the same basic technology as that used originally over 100 years ago. Major developments have occurred in the separate fields of frozen soil mechanics, refrigeration, and heat transfer analysis. However, except for a few projects in Europe and Asia, these developments have not been combined to upgrade ground freezing techniques to their potential level. In view of this situation, it is believed desirable to examine the art of ground freezing in light of recent technical developments, together with highlights on some of the apparent advantages, disadvantages and economics of the various alternative approaches. The purpose of this paper is to attempt such an examination, with particular emphasis on the practical application of presently available technology. GENERAL ADVANTAGES AND DISADVANTAGES Ground freezing may be used in any soil or rock formation, regardless of structure, grain size or permeability; however, it is best suited to soft ground rather than rock conditions. Freezing may be used for any size, shape or depth of excavation and the same physical plant can be used from job to job despite wide variation in these factors.

Jan 1, 1997