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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 S. K. Kawatra, C. A. Hardison, J. Gurtler, T. C. Eisele, K. Lewandowski

Acid soak tests were used to measure the effectiveness of binders in highly acidic conditions to determine their suitability for use in copper heap leaching. Soak tests involved placing the agglomerates on a screen, soaking them in a solution that replicates the pH of the raffinate used in a heap leach, and measuring the quantity of fine particles that passed through the screen. A wide range of binders were evaluated which had potential for functioning in acidic solution. Only a few binders were effective, with the best-performing binders being nonionic polymers designed for dust suppression applications. The most effective binder prevented all but 1.86% of the fines from being released and passing through the screen, while binderless agglomerates allowed as much as 29% of the fines to pass through the screen. The soak test developed for this study provides a useful method for rapidly identifying promising binders at a low cost, and for examining effects such as curing conditions on agglomerate quality.

Jan 1, 2005

By J. W. Merks

Spreadsheet software is an effective tool for simulating dynamic stochastic systems such as mineral processing plants. The two-product formula is used to show how to set up a Monte Carlo simulation in a spreadsheet template and how to calculate variances of dependent variables. The key to a reliable and realistic simulation model is to obtain unbiased estimates for all independent variables and variances in the set that defines the stochastic system. Monte Carlo simulation is also a powerful tool for optimizing sampling procedures, for applying sensitivity analysis and for designing and evaluating experiments.

Jan 1, 2000

By C. W. Benjamin

The paper covers the development of an efficient, "state-of-the-art" design approach encapsulating extensive research and development by Gulf on soft loading, low impact, zero spillage transfer chutes. The development, which interacts and interfaces the comprehensive methodologies for transfer chute design, allows Gulf to deliver detailed designs within 8-24 hours rather than the norm which is weeks or months. Outputs include 3D models of completed transfers and support structures along with rendered 3D representations of the design which can be fully manipulated around all axis in 3D.

Jan 1, 2000

By Jacques Deraisme

Geostatistics has been applied in many mining feasibility studies throughout the world during the last decade. Recently geostatistics has begun to be applied to the field of mining processes by attempting to aid in the definition of the best mining policy. For a feasibility study the grade-tonnage relationships give a reasonable order of magnitude estimate of the ore reserves within the deposit. But the reserves that will actually be recovered, will vary depending upon the mining methods and the technical means used. The profit earning capacity of the mining project is determined by a great many factors, such as for instance: accessibility of reserves to extracting machines, the haulage distance between the mine and the mill, the variability of produced ore (tonnage and grades) which could necessitate stockpiles or blending areas?

Jan 1, 1979

By Peter K. Achireko, Samuel Frimpong

Design and optimization of open pit limits are of paramount importance because they provide information for evaluating the economic potential of a mineral deposit and for developing short and long range mine plans. Many algorithms and their modifications have been used to design and optimize open pit limits. These algorithms have provided mine planning engineers with pertinent information in designing, optimizing and extracting ore reserves by open pit technology. However, they do not address the random field properties associated with the ore grades and reserves and commodity prices, and thus, fail to yield the truly optimized pit limits in any time horizon. In this paper, a new algorithm, MCSIMFNN, which overcomes these limitations is proposed and used to optimize open pit limits. The random field properties of the ore grade and reserves have been modelled using the modified conditional simulation based on the best linear unbiased estimation and local average subdivision techniques. Artificial neural networks are used to classify the blocks into classes based on their conditioned values. The error back propagation algorithm, in the neural networks, is used to optimize the pit limits by minimizing the desired and actual outputs error in a multi- layer perceptron under the pit wall slope constraints. The optimized pit value obtained by this algorithm has been compared to that from the Lerchs-Grossman's algorithm in a case study. The results are the same, but in random multivariable states, the MCSI MFNN algorithm is the most suitable for pit optimization. The method is also fast since it mimics the operation of the brain in the solution of the pit optimization problem.

Jan 1, 1996

By Sharad Mathur

The purpose of this paper is to present the benefits of high reactivity meta kaolin (HRM) in high performance cement-based systems. HRM, unlike other pozzolans, is manufactured from selected naturally occurring kaolin ore and carefully processed under stringent conditions to result in a consistent product with highly pozzolanic properties. HRM is an ultrafine pozzolan that enhances the mechanical properties (workability and strength) and chemical stability (durability) of Portland cement concrete and cement-based products. HRM is unique with respect to its white color which makes it an ideal choice for architectural applications where visual and aesthetic concerns are critical.

Jan 1, 2003

By Ingvar Janelid

During recent years, numerous articles have been published regarding theories and practical applications of sublevel caving. The reason is the great interest this method has created through its possibilities of standardizing and mechanizing operations and equipment. Other advantages are that the method can be adapted to orebodies of different shape, size, strength etc., and especially that working conditions can be made safe and relatively comfortable since all work is carried out in drifts. As is well known, the disadvantages or sublevel caving are that ore recovery hardly exceeds 85-90 % if waste rock dilution is to be kept below 20-30 %. Therefore, the main research and development work has been concentrated on parameters which can affect and reduce these disadvantages. This paper deals only with principles and problems which apply to large, massive orebodies. The problems with narrow, vertical or inclined orebodies are so different that they require a special handling. In my opinion, the intense research and development work during recent years, combined with practical experience, has given enough knowledge of the influence of different parameters, so that normal sublevel caving can be efficiently planned.

Jan 1, 1975

By A. K. Martin

Adaptive management can be described as a structured, iterative process of robust decision making in the face of uncertainty, with a goal of reducing uncertainty over time through system monitoring. Adaptive management is a tool which can be applied to not only change a system, but learn about the system (Holling, 1978). Adaptive management has been used in ecosystem management for years and guidance is provided in a variety of handbooks and publications. Adaptive management can be applied to industrial facilities and mines through the use of an adaptive environmental management plan (AEMP) and associated practices. The goal of this paper is to provide an explanation of how the plans and practices support regulatory agency approvals and permitting, span the life-cycle of mines, manage uncertainty, and assist in addressing mining impact and legacy issues. AEMPs and associated practices are useful tools to address the uncertainties in identifying, evaluating, and managing impacts of proposed new and modified mining facilities undergoing environmental review. Once a proposed project is approved, the AEMP continues as a living document, being informed, revised, and adapted by the operations. The AEMP can serve as an ongoing management tool for describing and evaluating environmental impacts, continuing in operations into post reclamation. If initiated during planning and environmental review of a project (and in some locations such as the United States [U.S.], the preparation of an Environmental Impact Statement (EIS)), the AEMP becomes a basis to identify, monitor, and manage potential project environmental impacts. Development of an AEMP for an operating mine is also beneficial since there are generally developing and ongoing environmental issues at those facilities as well. Over time, the AEMP is adapted to changing requirements and conditions including those anticipated and unanticipated. Ever increasing scrutiny of mining projects and the complexities of the EIS process highlight the uncertainties inherent in impact predictions. In making the momentous decision of initial project approval, these uncertainties can discourage the regulatory agencies? actions and create stakeholder anxiety and controversy about a project. A well-designed AEMP can support the decision to approve an EIS and enable a project to move forward. Additionally, an AEMP can inform financial assurance estimates and revisions over the life of a mine providing all parties including the citizens of the surrounding communities with greater confidence that potential environmental impacts and risks will be well managed.

Feb 23, 2014

By Boleslav Taraba, Antonín Taufer

Thermovision monitoring of surface temperature has been examined for the purpose of detection of spontaneous combustion of early stage. Measurements were carried out in bituminous and subbituminous coal mines. It was found that surface temperature heterogenities can be considered as common phenomenon in mine openings. However, the most of the observed temperature heterogenities were not connected with coal spontaneous combustion of early stage. These, so called [non-spontaneous combustion] temperature heterogenities in surface of mine openings were found to be caused by: l. Different conditions of heat transfer between opening surface and air stream; 2. Low temperature (natural) oxidation of coal; 3. Dissipated heat loses of working machine. Sites of early stage spontaneous combustion of coal were characterized by: 1. More significant, local rise in surface temperature comparing with low temperature coal oxidation; 2. Evolution of carbon monoxide with local concentration near the surface of such site more than about 15 ppm (bituminous coals) or 30 ppm (subbituminous coals). INTRODUCTION Mine fires are a serious hazard to life and result in a considerable loss of coal reserves. Thus, great attention is paid to investigation of new methods enabling already early detection of self-heating of coal. The earlier a fire is observed, the easier would it be to deal with. Detection methods used in coal mines are mainly based on: 1. [Mine air analysis]. Changes in composition of mine air are examined. Products of spontaneous heating of coal, not being present in mine air under normal conditions, are considered as indicators of anomalous behaviour of coal (carbon monoxide, unsaturated hydrocarbons) (Mackenzie-Wood and Strang, 1990). 2. [Temperature measurements]. Sites of higher temperature level comparing surroundings are looking for underground using various direct or indirect methods of temperature measurements. This paper summarizes experience from thermovision monitoring, as one of the latest indirect temperature measurement technique, used for the purpose of early detection of self-heating of coal in mine openings. INFRARED THERMOVISION Infrared thermovision device of AGEMA Infrared systems AB (Sweden) was used for the in situ measurements. The constant value of emissivity factor, 0.95, was pre-set as the most probable level of emissivities of coal and rocks in mine conditions.

Jan 1, 1993

By D. E. Ranta, Leigh A. Readdy

Defining classes of ore using geostatistical methods that match historical classifications has presented problems in the past. A simplistic and practical approach to this problem is presented. An example of the approach is presented using a porphyry-type system as a case study. The technique described uses area of drill-hole influence and known conditions from similar deposits, or the production history of the deposit being studied. It provides a practical bridging mechanism for defining the class of ore on a block-by-block basis using the error of estimation value developed during kriging. The approach provides a filtering method that refocuses attention on the adequacy of drill-hole spacing.

Jan 1, 1992

By N. S. Tanious

This work was completed prior to the author's appointment with the Nuclear Regulatory Commission (NRC). Therefore the views and conclusions contained in this paper are those of the author and should not be interpreted as necessarily representing the official policies or recommendations of the NRC. Reference to specific brands, instruments, or trade names is made to facilitate understanding and does not imply endorsement by the author or the NRC.

Jan 1, 1987

By Charles Dr. Li, John Dr. Box

Selective flotation and adsorption behavior of zircon and rutile under hot soap conditions have been examined. Conditioning temperature, pH and washing steps were shown to control the flotation selectivity. The adsorption of the sodium soap of oleic acid at zircon- water and rutile-water interfaces was investigated through micro- electrophoresis and adsorption density measurements. The soap adsorption on the zircon surface increased markedly with increasing temperature due to a strong chemisorption/surface reaction, and was almost independent of pH. In contrast, the soap adsorption on rutile decreased at high pH values. A simple physisorption plus hydrophobic interaction appeared to be the principal mechanism for the soap adsorption on rutile at moderate temperatures (below ~70(C), beyond which it may change to chemisorption through an activation process. Water wash, particularly under acidic conditions (pH 2-3), of the rutile particles treated with soap, will lead to a desorption of the soap from the rutile surface by forming an acid salt precipitate.

Jan 1, 1995

By M. Manrique, E. E. Vidal, I. Accorsi, P. R. Taylor

Various pyrometallurgical methods for treating ilmenite and zircon concentrates are reviewed. Laboratory experiments using a thermal plasma reactor were performed to evaluate the conversions of ilmenite to TiC or TiC-Fe and zircon to ZrC or ZrC-SiC. Results are examined and possible processing routes are identified.

Jan 1, 1999

By V. P. Keran, K. Leung

Two 32 foot x 14% foot, 6.4 MW autogenous mills have been installed in the Mount Isa Mines Copper Concentrator to replace the fine crushing plant, fine ore bin, rod mills and primary ball mills. This paper describes the reasons for the change, the rationale for the new circuit design and configuration, the design and scale-up processes used to size the mills, considerations for the installation of large mills inside an operating concentrator and some early operating data.

Jan 1, 1992

By Charles D. Litton

Introduction The successful performance of a mine-wide fire detection system depends upon its ability to detect the presence of a fire rapidly and reliably. It should be sufficiently rapid so that there remains enough time to either safely evacuate a mine or successfully extinguish and control the fire or both. It should be reliable so that false alarms are minimized without sacrificing sensitivity or time response. Systems should also be durable enough to withstand the mine environment over long periods of time while maintaining a high degree of re1iability. Maintenance and calibration of the system should be simp1 e and not require the expenditure of excessive time and manpower to keep it operational. Sensitivity, reliability, and durability of mine fire sensors and their electronic support systems have been the subject of significant Bureau research within recent years. The bulk of this type of information, along with the reports from which the remainder of this paper is derived, can be found in the Bibliography. It suffices to say that there exist commercially available systems for use in mines. This paper addresses a strategy for the use of such sensors and systems. Many factors influence the design of a mine-wide fire detection system, such as the potential sources and modes of ignition, the types of combustibles involved and the quantities avai1able for fire growth and flame spread. Mine air ventilation influences the growth and spread of a fire and also serves to transport the products-of-combustion to other areas of a mine remote from the fire. Fire sensor alarm thresholds place limits on the sizes of fires that can be detected. The time to respond to a detected fire, either in terms of evacuation or control and extinguishment, place additional time constraints on the design of fire detection systems. These factors interact with each other, often in complex ways, and it is the definition and understanding of these factors and their interactions that hold the key to the design of adequate and re1iable fire detection systems. Our level of understanding of the problem has increased dramatically within recent years and it is the intent of this paper to discuss the progress that has been made and how the information can best be used to improve the level of fire detection in underground mines.

Jan 1, 1986

The Newmont Boddington Orebody (NBO) is a large, diffuse Au/Cu orebody in Western Australias South-West corner with approximately 20Moz Au in current Reserves. The current sulphide Resource is reported after calculation with the non-linear estimation technique Uniform Conditioning to account for the mining selectivity being smaller than the average drillhole spacing. Simulation of Au grade is also run over the entire orebody reviewing risk and uncertainty. There are differences in results from the two methods. These have been investigated and the lessons learned of the influencing parameters and effect of technique alone, are helpful for applications to other orebodies.

Jan 1, 2010

By Qinghua Tian, Zhipeng Xu, Dong Li, Xueyi Guo, Liu Zhu

Tellurium (Te) is an important scattered metal. Known as the vitamin of modern industry, national defense and cutting-edge technology, it is the supporting material for new high-technology materials. Currently, its separation and extraction from Te-bearing materials face problems such as long flowsheets and high reagent consumption, giving rise to an urgent need to develop new methods for its recovery.

By Roger N. Miller

Talc mining in Vermont has in recent years undergone a progressive change in mining methods and in mining equipment. Underground mines have been phased out except in special circum- stances, and continuous mining machines (CMM?s) have replaced conventional drill/blast mining systems. Talc mining in Vermont began in the late 1800?s, and has continued without interruption to date. Beneficiation (flotation) has been applied since the early 1930?s, and has provided special products for toiletries and other markets. At the present time, there are two active companies that have evolved from the cumulative absorption of nearly ten smaller operations.

Jan 1, 1984

By E. Knell

COM Energy, Inc., a subsidiary of Occidental Petroleum Corporation, has constructed a 1.6 million hectoliter-per-year COM plant in Jacksonville, Florida. COM will be distributed to customers in the region as a substitute for fuel oil presently burned in boilers and kilns. As the market for COM grows, COM Energy, Inc. expects to build additional units both in this country and overseas. This paper addresses the overall status and technical aspects of the project, focusing on the facilities for COM production and utilization.

Jan 1, 1982