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By T. McCallum, B. Wellbrook, T. Ratnaweera

"Pressure oxidation (POX) leaching of copper (Cu) concentrates continues to be explored as the next generation of leaching processes to sustain existing Cu Solvent Extraction/Electrowinning (SX/EW) operations as easily leachable ores become scarcer. The leach liquors produced, particularly from total pressure oxidation, contain elevated concentrations of Cu and acid, making solvent extraction processing more challenging. Addressing this challenge will require innovative processing techniques and continuous improvement to be successful in achieving satisfactory physical and metallurgical performance in the SX plant. The ability to efficiently process these feeds via SX plays an important role in the continued success of POX technology. Characteristics of a concentrate leach pregnant leach solution (PLS) are discussed, along with best practices that should be considered for processing by SX. Findings discussed in this paper will shed light on ways to reduce process risk and bring additional improvement to the industry with minimal change to the SX plant. INTRODUCTION Hydrometallurgical processing of copper concentrates continues to gain interest from the industry. Treatment by smelting and electro refining continues to dominate, accounting for ~80% of global copper production, but is faced with its own challenges. The case for increased hydrometallurgical processing has been discussed as high grade ore deposits are diminishing, capital costs for smelting are high, and the environmental aspects present challenges for sustainable practice. The hydromet copper industry is also turning a corner as easily leachable copper oxide deposits are depleting, and excess SX-EW capacity exists in certain regions. The transition to hydrometallurgical processing of copper concentrates will take a bit of effort as leaching of copper sulfides is difficult and byproduct credits must be considered. Various POX leaching processes have been studied and proposed to the industry as viable practices. Of the many processes, commercial use has been practiced with the Mount Gordon Copper Process, total and partial pressure oxidation by Freeport-McMoRan at their Bagdad and Morenci, Arizona complexes, the Sepon Copper Process in Laos, and the bioleach BIOCOP™ process in Chile. The experience related to the current paper centers around Cu concentrate leaching performed by Freeport McMoRan (known as CLP). The patented process was developed as an alternative to smelting and refining in 1998. The technology applies to both molybdenum and copper concentrates. Commercial CLP research and development began with Phelps Dodge in 1999 to 2001. The first commercial plant was commissioned in 2003 at the Bagdad operation. Initial operating conditions of the Bagdad CLP were under high temperature conditions before converting in 2005 to medium temperature conditions. In 2007-2009, the CLP technology was commissioned in Morenci, operating medium temperature and high temperature lite conditions until shutting down due to the economic downturn. The Morenci CLP restarted operation in April 2015 due to acid production benefits for the Morenci leach operations. Renewed solvent extraction test work initiated well before restart and has been an ongoing focus for further SX plant optimization."

Jan 1, 2018

The ventilation of a mine is one of the key elements to a successful mining operation. It is, or should be, one of the primary concerns of the mining engineer at an underground mine. Too frequently, however, insufficient thought is given to future requirements. As a result, the mines suddenly find themselves with ventilation problems that cannot be corrected economically, or in short order, and have to suffer the consequences of being on the verge of having units shut down from time to time until the venlilaltion system can be improved. Insufficient ventilation in capital-intensive mining can cause production losses, the values of which far outweigh the significant costs of providing and operating an adequate ventilation plan. Many theories, and techniques in planning and control of underground ventilation systems have been developed over the years . It is the intent of this paper to point out some of the fundamental concepts, from the practical point of view, in the design and operation of a ventilation system, with special reference to underground mines using a room-and-pillar method.

Jan 1, 1986

By J. K. Ross, K. O. Hoal, S. K. Appleby

Understanding ore variability is a key factor in the geometallurgical analysis of a deposit and is beneficial to process development and mine planning. Ore variability is a function of the mineralogy of a deposit, in terms of both ore and gangue minerals and their textural relationships. This study integrates optical microscopy and quantitative mineral analysis to characterize the mineralogy and texture from 13 samples from different lithologic units at the Bingham Canyon Mine. The analysis identified several parameters, such as modal mineralogy, alteration assemblages, distribution of mineral phases and alteration assemblages and microfracture and void space distribution. These parameters can have an impact on the materials’ behavior during processing. This study demonstrates that quantitative mineralogical analysis can provide detailed information for improved understanding of ore variability.

Jan 1, 2010

By Brian P. Canning

Ion exchange resin processes are receiving renewed attention in the mining industry for recovery;, of metals from solution. This interest has been inspired by the development of continuous countercurrent ion; exchange systems (CCIX) which are of much lower cost than the original, fixed bed contactor processes. With the countercurrent systems and new developments to process or upgrade the eluate product, ion exchange can now compete successfully with solvent extraction for treatment of uranium ores. The low concentration of U308 obtained in the CCIX strong eluate is generally upgraded by solvent extraction methods in sulfuric acid systems. Resin loadings of up to 120 grams per liter of U308, however, have been produced experimentally by recycling of eluate (HIM-IX process) and further developments may be expected in the near future. New developments in resin technology are bringing forth products of greater strength, loading capacity, selectivity and density. Densities up, to 1.35 spgr have been claimed by some suppliers. The process is not a new one and has taken years to advance to the present state of development. The earliest system to gain widespread acceptance was the resin-in-pulp system applied to uranium recovery. Ion exchange, however, later lost acceptance in favor of solvent extraction in the 1960's due to problems in resin degradation, resin contamination and resin-pulp separation, in addition to the development of improved solvent extraction reagents and techniques. The resin-in-pulp system continues to have application on high clay ores and has advanced in design. A number of other continuous ion exchange systems were also tried but never gained continued acceptance. In the current resurgence period the CCIX systems to gain acceptance were the Utah and Chem-Sep (Higgins Loop) systems. These processes are relatively simple in concept although require sophisticated controls. Fixed bed columns have also been designed into multistage systems in countercurrent operation but are not discussed in this paper. These systems remain competitive today for many applications. The most recent advancements however have been in the multistage contactors from,, which three are in current acceptance. These are the Himsley, Porter, and NIM systems. All industrial applications of these systems are relatively new, although pilot plant and in-plant development has been in progress over the last decade. Fur36ther developments should be expected in the near future.

Jan 1, 1979

By John A. Herbst, K. Rajamani

Process improvement is probably the most widespread objective of mineral process plant operators in the late 1980's. An important part of such improvements is dynamic optimization which involves reacting to inevitable plant disturbances in such a way that productivity is maximized at every instant of time. This paper describes the way in which mathematical models can be and have been used in dynamic optimization. Both off-line and on-line model applications are described.

Jan 1, 1989

By Keith G. Wallace, Daniel J. Brunner

The traditional approach to mine ventilation planning involved making estimates of airflows, including leakage routes, and summing the corresponding pressure drops along consecutive paths in order to determine the fan pressures required. This methodology changed completely with the availability of computers. Mainframe digital computers began to be used for mine ventilation network analysis in the mid-1960's. Their use spread rapidly throughout the world in the 1970's. Mainframe machines were employed owing to the need for high speed numerical procedures and substantial storage requirements. However, during the past decade, the growing availability of low cost but powerful microcomputers has allowed the development of net- work analysis programs that can handle ventilation systems of hundreds of branches, and which can produce results within a few minutes. This paper discusses recent advances in software and hardware development specific to mine ventilation planning. Software developments include interactive data and output manipulation, graphical representation of output, internal checks on input parameters to preset ranges and subroutines which calculate the gas distribution throughout the network from known gas sources. Hardware advances have led to significant increases in memory to facilitate the analysis of large ventilation models, math co-processor chips which greatly shorten run times, and plotter hardware for graphical output displays. Recent software developments make it possible to graphically display output on printers faster than on standard plotters.

Jan 1, 1989

By J. Bigu

Ventilation conditions in working environments are usually studied by anemometry or, in complex cases, b using special tracer gases such as SF6 and 85Kr. in conjunction with chromatographic and radioactivity techniques, respectively. In some working environments, such as underground uranium mines, however, use can be made of the natural radioactivity environment (e.g.. 222rn. 220rn, and their progeny) to investigate mine ventilation conditions of practical interest. Theoretical studies and experimental data in several underground uranium mines and mine locations show that certain thoron progeny to radon progeny concentration ratios are very good indicators of ventilation conditions. Furthermore, the growth and decay of radon progeny and thoron progeny provide valuable information on mine air residence and clearance times. Some specific examples have been analyzed, such as bacterially-assisted uranium leaching operations in a partially enclosed stope, and the effect on the underground environment of turning ventilation fans on and off for a period of time. Air residence times and other variables of interest, determined from the mine radioactivity environment, were compared with more traditional techniques, such as anemometry and tracer gas chromatography. These studies were also extended to a wet non-uranium mine which exhibited relatively high concentrations of radon and its progeny.

Jan 1, 1989

By N. G. W. Cook

The conventional cyclic system of deep-level mining by drilling and blasting gives rise to an inadequate degree of stope sorting when mining thin reefs. This results in poor utilization of the capital facilities of a mine in the form of shafts, haulages, airways and associated equipment. Continuous and controlled removal of the thin gold-bearing portion of the reefs would permit better stope sorting and hence greater utilization of capital facilities. Results of experiments to develop hard rock cutting machines for mining are reported and the benefits which could be derived from their use are discussed.

Jan 1, 1969

By J. W. White, J. P. Olson

Computer-based dispatching in open-pit truck haulage operations yields many benefits of current interest to mine management. The key tangible benefit is a substantial productivity increase with a given fleet of equipment or, alternately, a significant reduction in equipment required to meet production quotas. Other tangible benefits in mines with concurrent operating objectives include minimizing rehandle, meeting several blending constraints simultaneously, and ensuring a target plant feed rate. Intangible benefits include production forecasting, performance comparisons of trucks or shovels of different manufacture, and extensive on-line report generation. Recent advances in mini- and micro-computer hardware and software and solid state electronics permit design and implementation of system features not feasible a few years ago. This paper discusses system aspects with emphasis on dispatching algorithms needed to meet concurrent objectives.

Jan 1, 1987

By Olav Moklebust

The R-N Process is an outgrowth of the development by the National Lead Company's Norwegian subsidiary Titania A/S, of a process for producing metallic iron and a high titanium content co-product from ilmenite. Development of the process for the treatment of iron ores was continued as a joint project of the Republic Steel Corporation and the National Lead Company in 1953. More recently in July, 1957, the R-N Corporation was created by these two companies to undertake the commercial promotion of the results of this joint project. This paper has been prepared with the permission and encouragement of these three companies. The R-N process has as its objective the making of metallic iron from iron ores or iron ore concentrates. The general principles of the process have already been disclosed in technical papers and patents. In general the process comprises the following steps: 1. Iron oxide in crushed natural iron ores or iron ore concentrates is reduced to about 95% metallic iron, without fusion in a rotary kiln in the presence of solid carbonaceous fuel,*such as, coke or char, limestone and combustible gases. 2. The kiln discharge, consisting of metallized ore, coke, lime and coke ashes, is cooled. The excess coke is regenerated and recycled to the kiln feed.

Jan 1, 1959

By S. Chander

The mechanism of oxidation of sulfur in pyrite is a function of the rate and driving force for oxidation. New evidence is presented in this article to show that at moderate potentials, a sulfur-rich hydrophobic layer is formed. Under ordinary conditions, the sulfur layer is covered with a layer of iron oxides, hydroxides, sulfate or oxy-sulfide ions. Under these conditions, pyrite is hydrophilic. In the presence of iron-chelating agents or iron sequestering ions, iron layer might not form. Under these conditions, sulfur-layer is exposed and pyritic might become hydrophobic. Stronger oxidizing conditions decompose the sulfur-layer, thereby making the surface hydrophilic.

Jan 1, 1992

By George F. Klernrnick

The Pokorny sulfur deposit is located in the northwest comer of the Delaware basin in the Rustler Springs sulfur district of west Texas. To date, 57 sulfur test wells have been drilled by Addwest Minerals delineating a resource of greater than one million long tons (It) of native sulfur. The deposit, hosted by the Permian Ochoan Castile Formation evaporite sequence, is a sulfur-bearing bioepigenetic limestone replacement of banded bituminous anhydrite. Three distinct mineralized horizons are present that correlate with zones of halite dissolution in the Castile. Sulfur mineralization occurs as hydrocarbon-poor disseminated grains, and as crystalline linings of discontinuous planar voids and large vugs.

Jan 1, 1992

By D. L. Monroe

Technical service is assuming an increasingly important role in the sale of asbestos fibre,, Manufacturers are examining raw materials more closely than ever before in order to, obtain the most efficient usage in their processes. Asbestos is one of the more difficult materials to evaluate and consequently has been are of the last to be subjected to evaluation. The main problem encountered in the evaluation of asbestos fibre is that minor differences in grade and texture are not shown up by chemical analysis, and are identified only by specialized physical analyses or actual production use. However, such minor differences become more critical as manufacturing processes are made more efficient, and many purchasing agents and plant chemists are applying a closer scrutiny to their supply of raw asbestos fibre. Many processes have been formulated around grades and qualities of asbestos fibre, which were standard some time ago, but which may now be subject to modification and improvement.

Jan 1, 1959

By Douglas J. Cork

Biohydrometallurgica1 processes in the areas of coal desulfurization (Hoffman, M.R., et al., 1981) and recovery of metals from metal sulfide ores (Lundgren, D.G. and Malouf E.E., 1983) are well known. In addition other areas of potential interest to the mining industries have been outlined (Spisak, J.F., 1979). For instance, scientists involved in this interdisciplinary field have endeavored to apply microorganisms to the problem of effluent sulfate disposal. This chapter assesses the feasibility of utilizing a particular two stage anaerobic microbial process to convert effluent sulfate to orthorhombic sulfur. Strong emphasis is given to the possibility of substituting this bioprocess for alternative gypsum synthesis and disposal methodologies commonly practiced by companies which emphasize sulfuric acid or ammonium sulfate leaching processes.

Jan 1, 1985

By David V. Fitterman, David L. Campbell

We've used direct current resistivity (DC), electromagnetic (EM), induced polarization (IP), and ground-penetrating radar (GPR) geoelectrical methods to study mine dumps. The results reflect lithology, pore water saturation, and dissolved solids in the pore water. If the pore water has a pH less than 5, conductivity maps can indicate acid generating potential. IP measurements can help distinguish mineralogy in mine dumps, especially concentrations of sulfide minerals. EM and DC can help locate acidic/high TDS groundwater associated with mine dumps. GPR methods failed at the sites we studied in the West. Our own conclusions are augmented by those from the recent literature.

Jan 1, 2000

By F. Montgomery Lyon

Pyritic sulfur in coal occurs as discrete mineral particles, and its liberation and physical rejection is the primary target for coal desulfurization. An acceptable solution to the pyrite removal problem from fine coal is not found in the standard methods of coal cleaning such as jigging, heavy-medium separation, tabling, and hydro-cycloning. Although fine coal is an ideal size for froth flotation, this method, as currently practiced is also unsuitable as the fine pyrite usually floats with the coal. One possible solution to this problem may be the froth flotation of pyrite from coal. This reverse flotation scheme would have the major advantage of removing both free pyrite and locked pyrite-coal combinations. With this possibility in mind, we have, as a first step, compared the flotation and adsorption. characteristics of an ore-pyrite and coal-pyrite with potassium-ethyl-xanthate as a collector 1 Related Research. The action of ethyl-xanthate on coal has been studied 2 by Horsley. He measured the contact angles of coal in distilled water and in the presence of purified ethyl-xanthate. The results indicated that the xanthate was not adsorbed by the coal. Additional contact angle data were obtained to determine the effects of cupric, ferric, and ferrous salts on the system. Then either the ferric or cupric salts were in, solution with the xanthate, there was an increase in the natural contact angles of the coal. This indicated that these heavy metal ions activated the flotation of the coal with xanthate. However, ferrous iron did not act as an activator. Horsley stated that the most attractive explanation was that the xanthate is oxidized to dixanthogen in the presence of the ferric and cupric ions.

Jan 1, 1971

By Guido Venturini, Giorgio Martinotti, Luca Delle Piane, Paolo Perello

This paper presents a critical review of geo-structural mapping methodologies applied to deep tunneling projects in complex mountain chains such as the Alps. Geological forecastings are often a crucial part of tunneling projects, which should allow contractees or contractors to assume their own risks. Despite this, often adequate methodological criteria are not applied in the realization of these studies, with consequent increase of costs and delays. A discussion should hopefully start in the world of tunneling in order to define a correct approach.

Jan 1, 2003

By K. Hanumantha Rao, K. S. E. Forssberg, F. Su

The influence of reagents dosage, pH, temperature, and particle size on the kinetics of apatite flotation response from magnetite has been investigated. The first-order models characterizing rectangular distribution and fast and slow distributions (F-S model) of floatabilities gave an excellent fit to the results of apatite flotation when compared to other models. However, the latter model is found to be better than the former in the goodness of fit and also in the description of flotation performance. The kinetic parameters in the F-S model are estimated by using a nonlinear least squares fitting program. The ratio of fast and slow rate constants is observed to be an important parameter for identifying the optimum levels of the variables and to outline the selectivity between apatite and magnetite. The influence of collector dosage is realized from the model parameters by relating it to the fraction of slow- floating particles. An attempt has been made to describe the apatite flotation behavior with the determined model parameters.

Jan 1, 1999

By David M. Spatz

Ore deposit models are defined largely by physical geologic features that relate conveniently to remote sensing. New Landsat, SPOT, RADARSAT and other multispectral and hyperspectral sensors with improved spatial resolution are currently in development. Near-infrared and thermal airborne hyperspectral scanners hold outstanding promise for both mineral exploration and feasibility stage mapping at potential new mining projects. These scanners are capable of identifying silicification, differentiating silicate alteration types, and mapping compositional variations within igneous and metamorphic complexes. Research in 'mineral and rock spectrometry is helping to advance applications of remote sensing. Hyperspectral scanners are capable of differentiating compositional variations within individual mineral species. Innovative data processing techniques continue to enhance computer software applications and facilitate imagery analysis by the geologist. Today, . remote sensing imagery is commonly integrated with multiple data sets in GIS format to form the core data base for regional exploration programs.

Jan 1, 1995

By E. Watkins, M. B. Daza

Although there have been great advances regarding the understanding of mine fires in underground mines in the last century, fires remain high risk incidents. During fire scenarios, many crucial decisions and actions can be made that greatly influence the outcomes of these scenarios. Underground worker decisions are mainly based on training and experience, which in some cases can be complemented with previous analysis of fire effects. In order to review the guidelines that should be taken into account for this kind of examination, a numerical analysis of effects produced by a shuttle car fire under five different ventilation conditions was carried out. The analysis provides some insightful recommendations for firefighting personnel such as time for direct attack and best attack position for first responders and fire brigade groups. Also, the most critical parameters for each scenario were determined. Finally, all results were systematically organized and a first approximation of a fire classification based on the tenability limits was provided for first responder and fire brigade groups. The methodology used in this study for the fire classification could allow for the most appropriate decisions by firefighting personnel increasing the probability to put fires out without compromising their health and safety. INTRODUCTION While there have been great advances regarding the causes of mine fires in underground mines in the last century “small fires have occurred and always will occur in underground mines” (Conti, Chasko, Wiehagen, & Lazzara, 2005). The response time and decisions made during an underground mine fire are critical elements that have direct influence on the event outcome. Mine fires can grow in size quickly causing catastrophic consequences, thus rapid and suitable response actions can result in the difference between an minor emergency situation and a disaster. Upon the confirmation of a fire, a decision must be made regarding whether to fight the fire or evacuate the mine. Even though all underground coal mines possess emergency response plans and firefighting personnel are highly trained, decisions can be complemented with previous numerical analyses. Such analyses could contribute with the knowledge of potential fire effects and consequently with fire preparedness in the mine. Preparedness in underground mines is an important element to reduce the probability of the negative consequences of a mine fire. The time elapsed between the detection of the fire and response in the early stage is a serious component since small fires can produce larger and more serious consequences. If a mine fire cannot be put out within the short time after discovery, the chance of getting the system back in balanced or the success of safely controlling and extinguishing a mine fire is reduced (Conti et al., 2005, Conti, Chasko, Wiehagen, & Lazzara, 2000, Trevits, Yuan, Teacoach, Valoski, & Urosek, 2009, Brake, 2013). As confirmed by Conti and others, if a mine fire cannot be controlled by direct firefighting methods the probability of extinguishing the fire, without sealing is greatly reduced (Conti et al., 2005). However, response actions such as direct extinguishment must be carried out without compromising the health and safety of the firefighting personnel (Kim, Lönnermark, & Ingason, 2010).

Jan 1, 2019