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By Dmitriy Kim, Natalya Ibragimova, Galina Sedelnikova

Gold and copper are lost in flotation tailings in mineral processing of copper-zinc-pyrite ores. Large resources of precious and base metals have accumulated in tailing ponds of Russian plants. Object of the study is the sample obtained from Ural Mining and Metallurgical Company in Russia. The main constituents in flotation tailings are Au, Ag, Cu and Zn with content 1.4 g/t, 12 g/t, 0.66 and 0.5% respectively. The flotation tailings are a refractory material. Gold, as main metal, is fine encapsulated in sulfides, mainly in pyrite. Gold extraction from tailings is 34.0 and 42.7% at P42 and P90 of 0.074mm particle size respectively. In this work heap bioleaching of tailings was studied for oxidation sulfides (pyrite and chalcopyrite) with using mesofilic and moderately termofilic bacteria in acidic solutions. The tailings had low filtration property (< 0.3 m/day) and pelletization was used before bioleaching. Copper containing converter slags flotation tailings and calcium oxide were used as binding material for increasing filtration property of tailings. Copper was extracted in sulfate solution and was precipitated by cementation after cleaning of bacterial solution from iron. Copper recovery was 56.8% at content 61.4% in precipitate. The biooxidation of pyrite was 80%. Cyanidation, leaching with thiourea and heap leaching by cyanide were tested too. Gold extraction from solid bioresidues was 82, 75.3 and 77% respectively. The results of this investigation were recommended for pilot test.

Jan 1, 2014

By Alistair James, Mo Shahsavari, Leon Botham

Recent catastrophic failures of heap leach facilities have revealed fundamental weaknesses in prevailing design paradigms, modeling toolkits, and oversight practices that continue to treat heaps as static, free-draining earthworks despite compelling evidence to the contrary. The core proposition advanced in this paper is that heap materials are intrinsically dynamic: their structure, permeability, and shear strength evolve under the sustained influence of irrigation, climate, and geochemical reactions, and these timedependent changes can precipitate abrupt transitions from granular stability to flow-like failure. Drawing on investigations of recent failures at Çöpler Mine in Turkey and Eagle Gold Mine in the Yukon, alongside earlier incidents in Peru, Arizona, Nevada, and Chile, the analysis identifies a recurrent sequence driving catastrophic behavior: progressive weathering elevates fines and suppresses permeability; drainage systems designed for initial conditions become overwhelmed; pore pressures rise heterogeneously within the heap; and static liquefaction initiates rapid mass movement with long runout. Current guidance, including ICOLD and ANCOLD frameworks and ASTM testing standards, provides a necessary foundation but is tailored to tailings and conventional soil mechanics. These documents offer insufficient direction for characterizing timedependent material degradation, quantifying rheology of weathered ore, and modeling post-failure mobility. To address this deficit, the paper proposes an integrated framework combining enhanced characterization, multi-physics numerical modeling that couples hydro-geochemical processes with large-deformation mechanics, and comprehensive monitoring with Trigger Action Response Plans. The conclusion argues for a heap-specific standard that embeds these elements from concept to closure, aiming to materially improve safety performance and reduce the likelihood and consequences of future failures.

Feb 22, 2026

By J. E. Gebhardt, D. McBride, T. N. Croft, M. Cross

"Heap leaching is well-established as a relatively low-cost and low-energy method of extracting metals from low grade ores. However, the design methodology, attention to the engineering details during heap construction and the long time scale in metal recovery makes the process susceptible to significant variation in the success of a heap leach operation. Often the laboratory predicted recovery rates are not achieved on site due to poor understanding of the complex physics of flow and coupled solid-liquid-thermal reactions within the multi-dimensional heterogeneous ore body. Given the large scale of commercial operations, small changes in metal recovery can substantially change the operating profitability. While there are a variety of approaches to heap leach modeling, computational fluid dynamics (CFD) modeling coupled with leach kinetic models offers a methodology to describe and understand the complexities of heap leaching. The CFD model uses leach kinetics specific for the mineralogy of the ore, including gangue chemistry, and provides an energy balance to calculate and predict temperature. Coupled with the CFD model’s inherent capability for modeling complex fluid flow, the physics and the chemistry of the heap can be simulated. This provides a tool for engineering design, as well as forecasting heap production under different scenarios. The calibrated model is used to simulate a three-dimensional test heap under fluctuating meteorological data, such as precipitation events, periodic solution application, and notably temperature. These simulations provide support for a methodology to design and engineer heap leaching of low grade copper sulfide ore. INTRODUCTION Worldwide copper ore reserves are faced with decreasing head grades with copper sulfides, particularly chalcopyrite being the predominant mineralogy (Nesse, 2000). Heap leaching offers an economical way to recover copper from low grade ore. The ore is stacked and a leach solution is applied and allowed to trickle though the porous bed of ore to extract target metals. The heap can be built with run of mine material or crushed ore and is constructed in order to achieve percolation of the leach solution to all regions. Bartlett (1998) provides an authoritative overview of the solution mining process where the leach solution interacts with the solid, the lixiviant dissolves the target minerals from the solid into the solution, and the dissolved species are transported out of the heap for subsequent recovery. Petersen (2016) provides a recent review of heap leach technology and emerging and potential future applications, and Ghorbani et al. (2016) summarizes the current state and challenges of the technology. Early applications of heap leaching offered a low cost technique to achieve high recoveries from oxide ores, typically greater than 70% depending upon the kinetics of reaction. As world copper resources transition to mainly copper sulfide mineralogy, such as chalcopyrite based ores, achieving high recovery from these copper sulfide deposits is proving more difficult due to the complexity of the leach kinetics, which leads to low leaching efficiency."

Jan 1, 2018

By A. L. Wilder

Coeur d&apos;Alene Mines Corporation&apos;s newest precious metals property is located in the old Rochester Mining District approximately twenty-five miles northeast of Lovelock, Nevada. Built at an elevation in excess of 6 000 feet, the Coeur-Rochester gold silver heap leach property encountered cold weather operational problems typical of most northern Nevada heap leach properties, soon after the start-up of operations last fall. Due to the size of the heap area under leach at Rochester, it was decided that 1 the usual practice of spraying to an "ice field" and waiting for the spring thaw was impractical. Further, the delivery schedule for a solution heating system of the size required was unacceptable. Accordingly, Rochester personnel embarked on a program to seek out a leach solution distribution system that would enable an operation through the winter and yet be cost effective. The findings of this program were rather dramatic and, as a result, the whole perception of heap leach solution application at Rochester has changed forever.

Jan 1, 1988

By D. Scott Barr

The Zarafshan/Newmont Joint Venture operates the Muruntau heap leach project, located in the Kyzylkum desert of central Uzbekistan. The mine produces more than 12.4 t/a (400,000 oz/year) of gold from low-grade oxide ore stockpiles adjacent to the Muruntau open pit. It is op¬erated by the Navoi Mining and Metallurgical Combine and is one of the largest gold resources known (Fig. 1). Since commissioning in 1995, total heap leach production has exceeded 21 t (675,000 oz). The joint venture uses four-stage crushing and screening to produce a final product for heap leaching, Merrill-Crowe processing and local refining.

Jan 1, 1998

By Arthur Miller

Most of the production of copper in the United States comes from a few large companies. Often overlooked, however, are the more numerous small mining operations, which collectively produce a significant portion of the nation&apos;s copper. The objective of this paper is to describe the operations of a small mining company - Ranchers Exploration and Development Corporation - how it views its place in this industry of giants, how it exploits the advantages offered by its relatively small size, and how it protects itself from the hazards being small introduces. Environment is, of course, a critical factor for such a company because it does not have the resources which help large companies weather periods of financial stress. Ideally, this environment is characterized by a heal thy economy, strong product demand, relatively stable prices , adequate grades and tonnages of ore commensurate with depth and over-burden, ready access to utilities, a dependable labor pool, and suitable technical "know how". When the environment is right, properties which were previously uneconomical to operate attract the attention of companies whose primary interest is a return on investment commensurate with risk over a reasonable period of time. Naturally, the amount of the investment and the duration of operation determines the size of the company which would be interested in such a venture. Such is the case with Ranchers Bluebird Mine at Miami, Arizona - a small property operated by a small company in a favorable economic environment.

Jan 1, 1967

By J. M. Mwase

The platinum group metal (PGM) industry is currently reliant on the crush-mill-float-smelt-refine route to process PGM ores. However, there are many instances where this route would not be feasible. An alternative process route has been developed which involves heap bioleaching to extract base metals followed by heap reclamation and a water wash step, leading into heap cyanide leaching to extract precious metals. This process was evaluated through test work on samples of Platreef ore using laboratory scale columns. After 304 days 75% Ni and 93% Cu were extracted in the bioleach experiment at 65°C, and after 60 days 58% Pt, 99% Pd and 90% Au in the follow-up cyanide leach experiment at 50°C. A preliminary process flow sheet has been developed around this. Analysis via a mineral liberation analyser showed that the remaining Pt was in the form of the mineral sperrylite, which appeared to be slow leaching in cyanide in comparison to the other mineral types. Analysis of cyanide effluent solution showed high levels of thiocyanate, which present an environmental risk for disposal and high consumption of cyanide. Further studies to develop the process for commercial application in the South African PGM industry are outlined.

Jan 1, 2014

By J. Libaude

The Changement mine in French Guyana has, since 1983, processed gold ore by classical gravity methods. A large part of the gold is in the form of very small, free or enclosed grains. Recovery by gravity methods is thus limited (25-30%) and the present plant produces about 40,000 t annually of auriferous waste assaying about 6 git. The company therefore decided to retreat the waste by heap cyanidation. After laboratory tests which showed the feasibility of the method, a pilot test was set up on site. An experimental 3000 t heap, composed of waste of 0-8 mm grain size, was laid out by bucket loader on an impermeable pad covered by PVC and geotextile cloth. The upper layer of the heap was reworked by mechanical shovel to break up the area that had been compacted by the passage of the loader so as to restore adequate permeability.

Jan 1, 1998

By G. Voiloshnikov, P. Koblova, Ye. Musin

Preg-robbing activity of the carbonaceous matter negatively impacts the process of precious metals recovery from gold-bearing ores and concentrates. In this paper, ore heap leaching (HL) using a blinding agent which inhibits ‘preg-robbing’ is a promising method. A carbonaceous ‘preg-robbing’ gold ore with head gold grade of 1.92 g/t from a Russian deposit was studied. Corg was 1.12%. In accordance with the Irgiredmet technique, preg-robbing activity was 65.3%. Surfactant reagent DN was used as the blinding agent. Column tests on the ore HL were conducted using two options. They were: a conventional flow sheet (Column 1) and a flow sheet with the reagent addition (Column 2). Gold recovery in Column 1 was 55.39% while gold recovery in Column 2 was 68.48%. The test results confirmed the efficiency of reagent DN. Keywords: Carbonaceous ore, organic blanking, preg-robbing, recovery

Jan 1, 2020

By M. Vaillé, B. Bossé, N. Durupt, A. Michaut

Imouraren is a sedimentary uranium deposit (> 150,000 tU @ 800 ppm), located approximately 100 km North-Northwest of Agadez (Niger); its depth reaches 110 to 170 meters. For low-grades ores, heap leaching is commonly considered as the appropriate technology for metal recovery. More precisely, the ore is crushed (≤ 300 mm) and agglomerated before being stacked. In this case, sulfuric acid can be added during agglomeration and/or irrigation (for three months to a year) to improve uranium recovery. It is known that mineralogical, chemical and physical properties of the uranium ore impact recovery, yet many challenges remain to increase recovery using this process. For example, ore heterogeneity and spatial variability (e.g., variation in uranium, carbonate and/or clay contents) can affect heap leaching performances (i.e., metal recovery, acid consumption or neutralization, percolation rate). However, laboratory column tests using composite ore sample that do not consider ore heterogeneity are widely used to anticipate recovery. Consequently, a new approach that consists in using Imouraren drill core ore samples was recently investigated. This latter also enabled a better assessment of the main parameters that influence uranium recovery and proposed a new predictive model to optimize mining operations.

Jan 1, 2020

By Robin J. Hickson

The Ortiz Mine is operated by Gold Fields Mining Corporation, a subsidiary of Consolidated Gold Fields Ltd., one of the world&apos;s major gold producers. The Ortiz Mine is Gold Fields only heap leaching facility as well as being their first operating mine in the U.S.A. The hydrometallurgical processes utilized for recovery of gold and silver at Ortiz are discussed along with the several practical changes in operation adopted since start-up. Included are heap leaching by cyanidation, concentration of values on activated carbon, desorption, and the final electrowinning steps prior to shipment. Construction costs and pertinent technical data are shown.

Jan 1, 1981

By Paul H. Johnson

Heap leaching is a simple means of recovering copper from oxide and oxide-sulfide ores. Although this method requires relatively low capital investment, it suffers from low copper recoveries and relatively high acid consumption. The objectives of this study were (1) to determine what factors influence these shortcomings, and (2) to establish a basis of correlation. between laboratory and field testing. The principal methods of leaching copper ores at the present time are heap, dump, in-place, and vat. A number of references are presented in the bibliography on the theoretical and practical aspects of these methods. In the heap-leaching method, crushed or uncrushed oxidized copper ore is placed on a prepared drainage pad. Acid leach solutions are dis¬tributed over the top of the heap, caused to percolate downward through the ore bed by gravity, and are drained from its base. The leach duration is generally a matter of a few months. Dump leaching is used to recover copper from very low-grade oxide-sulfide pit-waste materials. Here again, leach solutions are, percolated downward through a heap. However, in this method, little or no acid is added to the leach liquors, prepared drainage pads are not used and the leaching cycle is generally measured in terms of several years. Leaching agents are usually autogenously generated by the breakdown of sulfide minerals within the dump.

Jan 1, 1970

By Allan Neal, Jess W. Smith

FirstMiss Gold Inc., formerly FRM Minerals, Inc., is heap leaching gold from difficult, low grade ores at the Getchell Gold Mine in Humboldt County, Nevada. A two-thousand ton per day facility is leaching material from waste dumps from old operations and from small, satellite deposits around the main orebody. A three-thousand ton per day pressure oxidation mill is under construction to treat sulphide gold ores in the main deposit. The Getchell gold deposit occurs in a wide fault zone in carbonaceous, calcareous sediments and intrusive rocks. Intense clay alteration is typical within the mineralized zones. Silicification is a less dominant alteration phase within the ore. Gold in the upper oxide portion of the deposit occurs both in a free state which is leachable and complexed in fine disseminated pyrite which is not leachable. Gold in the lower sulphide portion of the deposit is almost entirely complexed in pyrite. Abundant arsenic sulphides and variable amounts of remobilized carbon are associated with the gold mineralization throughout the deposit. The waste dump material being heap leached was derived from the upper portions of the gold deposit. The dumps contain high quantitites of fines, clays and sulphides of iron, arsenic and other trace elements. No stockpiling of low grade materials was attempted during the old mining operations, therefore, the dump material is highly variable and unpredictable. A sample of representative material from one dump contained the following:

Jan 1, 1998

By Robert G. Woolery

Union Carbide_ began looking seriously at heap leaching in 1971. At that time some 1.6 million tons of mineral averaging 0.040% U308 were stockpiled at various sites around the Gas Hills, Wyoming, uranium facility. Several alternatives for economically exploiting these reserves were considered and heap leaching seemed the most attractive. At the time, Western Nuclear Inc. was operating a heap leach project nearby in which the low-grade ore was leached with sulfuric acid, the product liquor treated in an on-site solvent extraction circuit, and the stripped product liquor re-acidified and recycled. They were most generous in allowing us to visit their site, answering our questions, and were helpful in discussing the problems associated with heap leaching. They confirmed our belief that, it was possible to operate a heap leach profitably on material too low grade for. conventional milling. Based largely on what we had learned from Western Nuclear&apos;s experience, a program was set up involving a laboratory study to determine the characteristics of the mineral stockpiles as related to heap leaching and to conduct a pilot heap leach adjoining our Gas Hills mill. Basically, the pilot heap construction and leach procedure were similar to those described in the literature(1,2) with certain modifications to permit detailed monitoring of the operation. In May, &apos;1972, the decision was made to construct a test heap. The UCC plant at Gas Hills, Wyoming was selected as the most appropriate site for the follow¬ing reasons:

Jan 1, 1977

By N. Ogbonna, D. G. Dixon

Although heap bioleaching has been recognized as an economic alternative for treating low grade mineral ores, the underlying physical, chemical and biological processes involved are complex. A detailed investigation into the dynamics of heap bioleaching processes has provided much insight into the underlying complexities, and has led to the development of a sophisticated modelling tool - HeapSim. This tool can be of great help in the design and operation of heap bioleaching processes. In this paper, the mathematical model implemented in HeapSim is examined. The model takes into account mineral kinetics, particle level effects, bacterial growth, oxidation and adsorption, gas absorption, pore diffusion, bulk advection, gas balance and heat conservation. Three case studies where the model has been applied are briefly discussed. Computational Analysis in Hydrometallurgy 35th Annual Hydrometallurgy Meeting held in conjunction with the 44th Annual Conference of Metallurgists of CIM Calgary, Alberta, Canada Edited by

Jan 1, 2005

By A. De, J. S. Zuback, T. Mukherjee, T. DebRoy

For successful commercial applications of additive manufacturing, metallic parts need to be defect free, structurally sound and reliable. However, additively manufactured metallic parts are susceptible to distortion, lack of fusion defects and compositional changes. Methods to measure susceptibilities of various alloys to these defects are needed but not currently available. Here we show that the necessary theories can be developed based on a well-tested numerical heat transfer and fluid flow model and decades of research in the field of welding. The proposed theories are validated with experimental results reported in the literature.

Jan 1, 2016

By J. McKelliget, J. Szekely, Oreper. G. M.

"1. INTRODUCTIONThis paper is concerned with heat and fluid flow phenomena in arc welding operations. Fig. 1 shows a schematic sketch of a typical arc welding arrangement. It is seen that an arc is being struck between an inert electrode and a metal surface and that the resultant current and energy flow will case the formation of a molten weldpool.It is clearly appreciated that the weldpool shape and the nature of circulation in the weldpool may play an important part in determining the ultimate weld quality. It is known, furthermore,· that the weldpool behavior in turn will be affected by the spatial distribution of the current and the heat flux it receives from the arc. Indeed, the inherent coupling between the arc and the weldpool is a key feature of welding operations.Up to the present useful work has been done on the modelling of heat transfer and melt circulation in weldpools (1,2,3,4) and also on the description of arcs, including welding arcs (5,6,7,8). However, the coupling between these two sets of phenomena is relatively unexplored in a qualitative sense. The purpose of the present paper is to examine the interaction between welding arcs and weldpools. The actual material will be presented under the following headings:"

Jan 1, 1986

By Antti Roine

Sulfidic zinc concentrates are usually roasted in a fluidized bed furnace into sulfur-free oxide form. Metallic zinc is produced from this oxidic calcine using hydrometallurgical leaching, solution purification and electrowinning stages. The roasting step is necessary because zinc oxides are easier to dissolve using traditional leaching methods than zinc sulfides. The Kokkola Zinc smelter uses various types of zinc concentrates and secondary materials as feed mixture. This makes it difficult to find optimum process parameters for the roaster when the composition and particle size distribution of the feed mixture varies even on a daily basis. Certain conditions may even cause difficult accretion problems or increase the amount of calcine in the process off-gas line excessively. A thermochemical heat and material balance model was developed for process advisor, in order to estimate the effects of different process parameters (temperature, process air coefficient, concentrate feed, oxygen enrichment, water feed, etc.) on the heat balance, roasting temperature and calcine composition. This model was constructed using the heat balance module of HSC Chemistry 4.0 software. The prevailing chemical compounds in the concentrate and calcine were verified using mineralogical analyses and equilibrium calculations. The roasting process seems to operate near chemical equilibrium conditions, if the behavior of the main components is considered. This paper describes briefly the basic principles of the calculation model and outlines the results with several diagrams and discussion. The calculated results were in reasonable agreement with the recent process air oxygen enrichment and water feed test campaigns carried out at Kokkola in 1999.

Jan 1, 2000

By Ignacy A. Lipiec

The advantage of microorganisms used in bioleach systems to conventional chemical reaction systems is that these apply the available energy more precisely where it is needed, either directly onto the mineral of interest or by efficiently catalyzing the production of a reactant. The literature cover the range from empirical models used in describing macro heat balance in heaps to detailed studies relating the micro heat effects of bacteria adhesion energy to the surface of minerals. In this paper, the heat effects are reviewed in a general way describing bioleaching in two macro systems, heap leaching and slurry bioreactors. The micro scale heat effects is the reactions and conditions at the microorganism scale, including the mechanism of leaching and bacterial behavior.

Jan 1, 1998

By A. J. Dickson, A. M. Starfield

This paper reviews the progress made to date in the development of computer models of heat and moisture transfer from rock surfaces to the ventilating air in deep-level mines. The application of these programs to ventilation planning and design is discussed.

Jan 1, 2014