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By Todd Schrauf, James Scott, Mark Smith

"Cyanide heap leaching of gold ores in areas with extremely low winter temperatures requires special considerations to prevent freezing of the leach solution. Factors that impact the solution temperature include ore temperature at the time of stacking and during operation, burial of drip irrigation lines, use of geomembrane covers and heating of the leach solution. Thermodynamic modeling was performed to simulate expected ore and solution temperatures under different operating strategies for Kaminak Gold’s Coffee gold project in the Yukon Territory. Mean monthly temperatures at the site ranged from a low of -22.5 °C (-8.5 °F) to a high of 13.6 °C (56.4 °F), while in situ ore temperatures ranged from -0.5° to about -1.5 °C (31 ° to 29 °F). The modeling results were used to optimize the operational parameters and indicated that a combination of drip line burial and heating of the leach solution during the winter months was required to maintain solution temperatures above freezing during the initial years of stacking, although as the size of the heap increased, heating was no longer necessary.Modeling objectivesThe successful operation of a cyanide heap leach under extremely cold winter temperatures requires the implementation of operational strategies to prevent freezing of the leach solution and the ore within the heap. Thermodynamic modeling of the heap provides the means to quantify the effectiveness of these different operational parameters on maintaining the required operating temperatures to avoid freezing within the heap. The operational parameters that were evaluated with the model included:"

Apr 1, 2016

By G. L. Smit

The Buffelsfontein Gold Mining Company is situated in the Klerks-dorp district of the Province of the Transvaal in the Republic of South Africa, approximately 100 miles west of Johannesburg. Gold production commenced in January 1957 and Uranium treatment of residue slimes as a by-product started in July 1957. The mining property is 5435 mining claims in extent, the equivalent of 7,988 acres or 12.5 square miles. The mine was initially exploited by the Pioneer Twin Shaft System, consisting of a 26 feet diameter down-cast shaft and a 22 feet diameter up-cast shaft, sunk in the north-west area of the mine to cater for the hoisting and ventilation requirements for a milling rate of 150,000 tons per month.

Jan 1, 1964

By Phillip E. Butler

Since early 1973, the Pennsylvania Department of Transportation (PennDOT) has been actively engaged in the utilization of coal mine refuse in the design and construction of highway embankments. The Soils and Geological Engineering Division of the Bureau of Materials, Testing and Research has the task of managing the program which includes field investigations, laboratory testing, engineering evaluation, planning, coordination, implementation, construction control, and review of construction performance. The objectives of the utilization program, in removing colliery refuse banks and utilizing the material in construction, are the environmental and aesthetic rehabilitation of those areas in the Anthracite and Bituminous coal fields which have been plagued for such a long time by air and water pollution, and unsightly landscapes; and the economic rehabilitation of those areas occupied by refuse banks by providing usable land which can now be developed as residential, business, or industrial sites.

Jan 1, 1975

By David I. Smith, Kenneth Arnold, Bryan Aweh, Vincent Falkowsk, Brian Lakin, Andy Fer

Nassau County, New York, is undertaking several projects to improve the water quality in the Western Bays of Long Island. A major step forward will be the completion of the Bay Park Conveyance Project, which will divert most treated effluent away from the Western Bays to an existing ocean outfall at the Cedar Creek Water Pollution Control Plant. The ongoing works include 3.6 miles of microtunneling, 7 miles of sliplining, 14 shafts, and a 75 MGD pump station. This paper provides an overview of the design and an update on construction progress through December 2022. The project is a collaborative effort between Nassau County, New York State Department of Environmental Conservation, the design-builder, and various consultants.

Jun 13, 2023

By W. D. Bachman

A study has been made of wet, autogenous grinding of disseminated copper ores, including testing of a large number of samples from Kennecott Copper Corporation's Chino mine. The efficiency with which the various samples could be ground was found to vary over an extremely wide range, even among samples taken from different locations within the same ore body. These variations in grindability can be qualitatively correlated with the composition of the rock and the fracturing and alteration that had occurred. Because of the large-scale non-homogeneity of disseminated copper ore bodies, extensive and careful testing of autogenous grinding is needed. An accurate correlation of the grinding data from various samples with the geology of the ore body and with mining plans will indicate if variations in grinding mill throughput can be avoided in practice by mixing or blending of mill feed and if, therefore, autogenous grinding can be applied successfully.

Jan 1, 1970

By Bernd Friedrich, Elif Emil‑Kaya, Merve Papakci

In the production of SmCo permanent magnets with excellent temperature stability, corrosion resistance, and oxidation resistance, samarium (Sm), one of the rare earth elements (REEs), and cobalt (Co) are employed. Cobalt (Co) is a crucial component in tool materials, nickel-based alloys, tablet and smartphone batteries, and electric car batteries. REEs and Co have been listed as critical raw materials by the European Union Commission for many years. Due to the ever-growing demand for Co and REEs in technological applications, the recovery of these elements from secondary sources has garnered significant interest. There are two types of SmCo magnets, one of which contains a high amount of iron, approximately 15.2%. This paper focuses on the recycling of Fe-bearing SmCo. In this study, an oxidative leaching process with nitric acid was developed to eliminate iron through in situ hydrolysis and to dissolve REEs and Co. The influence of experimental conditions on the formation of an amorphous iron compound through the hydrolysis of Fe3+ in a nitric acid environment was thoroughly examined based on a Taguchi orthogonal array. The optimal parameters for oxidative leaching were determined to be an acid concentration of 3 mol/L, a solid-to-liquid ratio of 1/10, and a process temperature of 60 °C.

Feb 15, 2024

By L. M. Sandoval, R. Kaunda, C. N. Vasquez, S. C. Falcon

Artisanal and small-scale mining (ASM) involves a wide range of practices, from highly informal and minimally mechanized mining operations with predominantly manual work to formal practices carried out by small but high-tech industrial mining operations [1]. ASM may be a traditional practice, with skills passed from one generation to another. It can be an important driver of local economic development, while simultaneously contributing to a complex array of positive and negative socioeconomic and environmental impacts. There are more than 100 million artisanal and small-scale miners in 80 countries worldwide, and they supply around 20% of the worldwide gold production [2]. According to the Peruvian Ministry of Energy and Mining (MINEM), in 2020, 32% of fatal accidents in formal (legal) Peruvian mining operations were caused by groundfall events [3].The lack of resources, knowledge of best practices in health and safety, and insufficient equipment used in ASM make the probability of suffering work accidents very high. Furthermore, groundfall is one of the main causes of accidents and injuries in underground mines around the world [4], and it is also a concerning problem in ASM, where the associated fatality rate is similarly high. Unfortunately, a proper record of accidents in ASM is not kept, so an estimate of the actual number of groundfall accidents cannot be accurately developed [5]. Currently miners rely on empirical and observational tools acquired through previous experience to assess groundfall risks. The risks for artisanal miners can tend to be significantly greater than risks for those from the mining industry. This is due to the lack of regulation of ASM, which tends to operate outside the legal framework and the regulations lack of enforcement in force for occupational health and safety regulations.

Mar 2, 2022

By Constance F. Acton

Based on laboratory structure analyses, a pilot plant investigation was undertaken to evaluate a Michigan conglomerate native copper ore. Comminution or sized feed was accomplished using wet, closed circuit autogenous grinding with and without crushing of the recirculating load. Coarse metallics were concentrated in two stages of jigging with fine metallic copper being recovered in a three-stage xanthate flotation circuit. With a feed averaging 2.09 % Cu, copper recovery ranged from 86-93 % Cu with an average grade of 55.5 % Ca. An evaluation of the processing flowsheet is made in terms of pertinent independent, dependent, and external variables and design factors. Rate equations are developed to describe the grinding and flotation circuits separately as well as the entire circuit as a whole. Performance equations for the overall operation and for the unit operation of autogenous grinding alone are developed in terms of suitable capacity, efficiency and energy consumption terms. Thus, the effects of feed rate, recirculating load and flowsheet design can be rationally evaluated. Energy consumption for various conditions in the pilot plant is compared to the laboratory value. Additionally, size and scale up factors are discussed. Recommendations are made for further studies to be undertaken to further quantify the ore characteristics and the nature of the autogenous grinding operation. However, the feasibilty of beneficiation of this type of native copper ore by means of an autogenous grinding/jigging/flotation circuit is clearly established.

Jan 1, 1977

By J. Marts

Underground longwall coal mining sections are operated as sealed gobs if the coal is prone to spontaneous combustion. Sealing along the gate roads during longwall face retreat limits the flow of fresh air (oxygen) into the gob and, thus, deprives the spontaneous combustion reaction of oxygen. In a project sponsored by the National Institute for Occupational Safety and Health (NIOSH), researchers at the Colorado School of Mines have used computational fluid dynamics modeling to simulate the flow of gases in sealed longwall gobs. The models were validated using measurements and observations from the field and demonstrate that targeted injection of nitrogen along the gate roads inby the face can be used to control the size and location of explosive methane clouds within the gob and to minimize or eliminate the explosion hazard resulting from the formation of flammable methane-air mixtures.

Sep 1, 2013

By Ben Blaschuk

The Bagdad solvent extraction plant was commissioned in 1969 and was the second solvent extraction-electrowinning (SX-EW) operation to be built following the Ranchers Bluebird SX-EW plant near Miami, AZ. The current operation still resembles its original form, with four independent sections that run in parallel with each consisting of many long and narrow settlers. Through its 40-year history, the Bagdad SX circuit has experienced a range of pregnant leach solution flows and grades. The unique design of the Bagdad circuit has allowed for numerous configuration changes to accommodate the changing operational conditions, while maintaining an extraction recognized in the industry as excellent.

Jan 1, 2011

By Ralph W. Barbaro

In the mineral industry, the objective of a mining venture is to extract, process, and market a mineral commodity in such a manner that the profit of the venture is maximized. In a mining venture, a company normally has control over mine production scheduling, the selection and location of processing facilities (mineral beneficiation plants, smelting plants, refineries, or blending facilities), processed ore blending, and the selection of markets. The flexibility of the above factors provides many alternatives to satisfy the needs of each market with regard to quantity and quality of ore. The purpose of this paper is to present a mathematical model for determining the alternative that yields the maximum profit. Production planning is generally concerned with the best utilization of fixed resources, more specifically, with the determination of production and inventory levels to meet fluctuating demand requirements. A mine can be any source of ore such as an entire mine, a production unit within a mine, or an independent supplier. The objective of production scheduling is to determine the times at which each mine will be used and to allocate a required level of production. Production planning and scheduling problems are intimately associated with the location of new and existing mines and processing facilities. Although the location of the mines is usually fixed, there can be considerable flexibility in locating new processing facilities, in the selection of the processing plant, and in blending the ore before and after processing.

Jan 1, 1983

The Boliden Aitik concentrator in Sweden processes 2,000 tph of low grade copper ore. The plant consists of five grinding lines feeding four bulk flotation banks with a scavenger concentrate regrind mill, and a column cleaner circuit with a regrind mill. The authors installed a model-based expert, optimizing control system to maximize copper recovery in the bulk flotation circuit while maintaining an appropriate copper grade in the cleaner feed. The optimizing control system uses on-line assays and calculates and implements set points for cell pulp levels, air rates and reagent addition rates. It combines the power of a dynamic population balance model which estimates mineral liberation in each stream, an optimizer which computes appropriate set points and a rule-based module which implements the strategy. The benefits have been evaluated over three months. The model-based expert, optimizing control system generates a measurable increase in copper recovery, around 0.5 per cent and an optimized bulk concentrate grade. The need to maintain the optimizing control system and other practical aspects are discussed.

Jan 1, 1998

By Gökhan Çevikbilen, Ümit Karadoğan, Sevde Korkut, Berrak Teymur

This study proposes a methodology for dewatering of mine waste using a multistage process, combining geotextile tubes and anionic polyacrylamide (PAM), which accelerates the recycling process of water for aggregate mine waste facilities. For this purpose, waste from a rock quarry located in Istanbul was investigated. Flocculation tests revealed that the use of anionic PAM at an optimum dosage reduced sedimentation time and decreased turbidity. The compatibility of geotextiles and mine waste conditioned with different dosages of the effective PAM was evaluated by rapid dewatering tests, considering the water content of the filter cake, amount of infiltrated solid content, and rate of filtration. Geotextile dewatering tests were also performed on PAM-free and conditioned suspensions. The dewatering process was optimized by the use of a geotextile tube in two stages: (i) on the unconditioned suspension and (ii) on recovered PAM-conditioned leachate. Directing PAM-free non-hazardous soil-based material obtained in stage i to alternative beneficial uses is suggested, to minimize the volume of waste. Furthermore, recycling of the effluent obtained at the second stage of the proposed method will ensure more efficient water reuse

Sep 29, 2022

By Thomas C. Shrake

The Lomas Bayas copper property is located93 km (58 miles) east of Antofagasta, Region II, Chile (Fig. 1). The deposit was discovered in 1880. The deposit produced intermittently until 1992. Production at Lomas Bayas took place in high-grade veins and breccias mined underground. During 1991, Empresa Minera Mantos Blancos SA (EMMB) optioned the property from Compania Doña Ada SA. Doña Ada maintained the right to continue mining the ores by open-pit and block-caving methods and hauling the ore to its plant located60 km (37 miles) to the north. EMMB conducted exploration and column test programs. On May 9, 1994, Compania Minera Gibraltar Ltda.(CMGL) signed a purchase option agreement to acquire the Lomas Bayas property. CMGL conducted 8,612 m(9,490 ft) of reverse-circulation drilling, 2,028 m (6,650ft) of diamond drilling, a series of metallurgical tests and geologic mapping. The company then decided to exercise its purchase option.

Jan 1, 1996

By T. J. Close

On September 10, 1991, Secretary of the Department of Interior Manuel Lujan deleted the Silver Peak Range North Wilderness Study Area from the list of U.S. Bureau of Land Management lands in Nevada to be considered for wilderness designation. This decision was based in part on the U.S. Bureau of Mines mineral investigation of the wilderness study area which found that it has indications of precious metals resources. The following is a summary of the results of that mineral investigation. The study area lies between the Silver Peak and Dyer mining districts of west-central Nevada. The Silver Peak mining district, to the east, has a long mining history dating back to 1907 when precious-metals-bearing veins were discovered. The major producer in the Silver Peak district was Sunshine Mining Company's Sixteen-to-One silver mine. During the Bureau's study the Sixteen-to-One mine was operating; it has since been idled due to low silver prices. Precious metals-bearing veins were discovered in the Dyer district, to the west of the study area, in the 1860's. Mineral activity in Dyer district consisted mainly of prospecting. The Silver Peak study area itself has no mining history and contains only a few mining claims, but the Bureau examined 13 mineralized sites, most previously unknown and unclaimed. These sites are along two zones that cross the study area from the Silver Peak to the Dyer mining district. The two zones transect a volcanic center of fractured and altered rocks that contain epithermal veins of quartz, calcite, and jasperoid with gold, silver, and base metals. At the surface these veins are poorly defined and poorly mineralized. The more than forty veins examined in the study area are as thick as 17 feet and as long as 1,000 feet. Samples from surface exposures of these veins contained as much as 0.02 ounce per ton gold, 2.1 ounces per ton silver, 1.0 percent copper, 2.6 percent lead, and 0.4 percent zinc. Analyses of the Bureau data disclosed no vein large enough or of high enough grade to be classified a mineral resource. However, most do have indications of silver-and gold-bearing resources at depth. Subsurface exploration had to be done on the vein at the Sixteen-to-One mine to outline reserves (a vein averaging about 22 feet thick and containing 6-to 7-ounces per ton silver); the same is true of veins in the Silver Peak Range North Wilderness Study Area.

Jan 1, 1993

By Y. Luo

Highwall mining, which is a relatively new mining method, is a preferred and often the only feasible method for extracting coal reserve left by surface mining operations in areas with steep terrain and in closely spaced thin coal seams. Though its safety record is comparable to that of surface mining, failures of mine structures in highwall mines, especially the highwall, have occurred. Methods for the systematic designing of highwall mines to meet the safety and operational challenges are still evolving. This paper presents the results of research into improving the existing design methods and developing new ones for highwall mining operations. The design methodology is aimed at ensuring structural stability of the highwall, roof, web and barrier pillars and preventing subsidence. It takes into consideration the major ground control challenges of soft and layered mine roofs, and interactions from mining closely spaced coal seams. An optimization design process applying a pressure arch concept can be incorporated to improve the recovery rate of coal reserve. A computer program based on the design methodology was developed.

Jan 1, 2015

By LeRoy D. Loy

To facilitate effective land reclamation and comply with existing state regulations, surface coal mine operators have in recent years adopted new mining techniques and equipment utilization for steep-terrain mining. In contrast to direct spoiling with draglines or shovels, these new mining methods require some form of overburden haulage from the excavation face to the point of reclamation. Although current mining methodologies such as Block-Cut, Modified Block-Cut, and Mountaintop Removal with Head-of-Hollow Fills have proven effective in achieving reclamation objectives, some production problems have resulted from pit congestion and excessive equipment delays. Recognizing this problem, the United States Bureau of Mines contracted Skelly and Loy to design innovative mining concepts utilizing conveyor haulage in place of trucks, loaders, dozers and scrapers. Project objectives required definition of current bottlenecks and development of mining systems to: alleviate bottlenecks; increase production potential; facilitate additional resource recovery; enhance reclamation; reduce safety hazards; and improve mining economics. Successful completion of project goals within a four year program involves systematic implementation of the following separate work phases: 1) Develop Concepts for Block-Cut Mining Systems; 2) Determine the Economic and Technical Feasibility of Concepts; 3) Prepare Detailed Design and Specifications of Concepts; and 4) Prepare Specifications for Conducting Field Tests of the Most Promising Concepts. At the time of this publication, Phases 1 and 2 are finalized with Phase 3 efforts well underway.

Jan 1, 1977

By M. Westendorf, T. Banerjee, S. Kaushik, D. Tinney

"Cyclones are one of the most extensively used pieces of equipment within the mineral processing industry because of their simplistic operating and maintenance philosophies. They are commonly used as classifiers within the comminution circuit to control the grinding product particle size for satisfactory performance of downstream operations.Cyclones are a key contributor to the effective operation of the plant and have a significant impact on the mineral processing plant operations. If the cyclones are not performing as they should, the results are often a combination of lost recovery, grade, capacity and reduced throughput. Similarly, an inefficient cyclone operation may also lead to low or high recirculating loads that impact the efficiency of the comminution circuit. This highlights the importance of having proper stability in cyclone operation while implementing any plant-wide optimization strategy.One of the key challenges in cyclone operation is that cyclones are highly sensitive to changes in operating conditions and are affected by process fluctuations such as feed pressure, solids concentration and flow rates. Fluctuations in cyclone feed characteristics lead to unstable cyclone performance which affects mineral liberation. For such an impactful unit operation, cyclones have historically been under-instrumented in an otherwise highly instrumented process plant. Traditionally, mill operators have relied on visual observations of the apex discharge to determine the operating state of the cyclones. Visual cues corresponding to the different cyclone operating conditions have been discussed by Neesse et al. (2004) as shown in Fig. 1."

Jan 1, 2014

By Iain Weir-Jones

The efficient operation of an open pit mine presupposes that the slopes are maintained at an angle which closely approaches that of the ultimate stability of the slope. In order to do this in a safe manner, it is essential that the data relating to the behavior of the slopes be monitored and made available, through an instrumentation system, to the appropriate personnel so that soundly-based engineering decisions may be reached with the minimum of wasted effort. In addition to simply detecting potential failures, the system should also define what type of failure is developing; i.e., rotational, wedge, or dilational failures. Providing this data is the prime function of a stability monitoring system. Therefore, in an operating open pit mine, the instrumentation system must provide information which will have a direct bearing upon both the safety and the economics of the operation, as well as provide data which is pertinent to initial design, or to the re-design of slopes where developing instability is found to be a problem.6 It is possible to excavate pit slopes which will remain stable under extremely adverse conditions; however, such slopes would usually be so flat that they would tend to render the operation of a pit uneconomical which might otherwise be mined at a profit. On this basis, all practical pit slopes must be considered to be, to some ex- tent, unstable; if they are not, the design is too conservative and the mine is not returning its maximum profit. To reduce the problem to its fundamentals, one can simply state that the ideal pit slope design produces a slope which stands with zero maintenance for the entire life of the pit and then collapses into the final excavation as soon as the personnel and equipment have been removed. Such a design is impossible to achieve, but the fact remains that an efficient slope would hover on the edge of failure for the life of I the pit. As one retreats from this position, the profitability of the mine decreases because of an unduly conservative design.

Jan 1, 1975

By AKIHIRO YOSHIMURA, HIDEKAZU KATO, KOTA TAKATORI, YASUNARI MATSUNO

Chalcopyrite (CuFeS2) is the most refractory copper mineral when treated in conventional sulfate media leaching systems. This is the first study to examine the use of a dimethyl sulfoxide (CH3SOCH3, DMSO) solution containing copper chloride (CuCl2) for the leaching of chalcopyrite. Leaching experiments for a copper concentrate composed mainly of chalcopyrite were conducted at ambient pressure at 313–413 K. The leaching fractions of Cu, Fe, S, Au, and As were investigated. It was found that 90% of the Cu was extracted in 2 h, and 94% was extracted in 4 h at 373 K, which is competitive with other conventional processes. A DMSO solution containing CuCl2 could selectively dissolve the valuable metals Cu and Au from chalcopyrite, but leave minerals with little economic value such as pyrite (FeS2) and As in the residue. Chalcopyrite is oxidized by cupric ion in proportion to the stoichiometric ratio of Cu in the concentrate to the initial cupric ion in the DMSO solution, which is enhanced by the presence of oxygen below 373 K.

Mar 12, 2021