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By Shani Engelbrecht, Belinda McFadzean, Avuyile Wali, Natalie Shackleton, Vratislav Malysiak

Frothers play a crucial role in sulphide and PGM ore flotation recovery, and AECI Mining Chemicals studies on PGM ores have shown significant flotation kinetic increases with the optimal frother-collector combinations. Using Senfroth 200 as the industry baseline, remarkable kinetic increases were observed with AECI Mining Chemicals developed frothers in the first concentrate. Even in the worst-case scenarios, 4E PGM recovery increased by 5% at a slightly higher concentrate grade. It is important not to limit frother dosage to a fixed value. Instead, enough frother should be added to maintain a stable bench float, measuring the dosages by frother volume before and after tests. Frothers can be specialized blends and their importance should not be underestimated. The results produced by formulating and innovating frothers to address specific industry challenges have been encouraging. Testing a frother on a plant scale does not have to be as daunting as with collectors, enabling the identification of the best frother-collector combinations at an industrial scale. AECI Mining Chemicals bench scale testwork has motivated plant-scale trials that have successfully transitioned to commercialization. This paper compares the results from metallurgical and froth stability tests and shows that occasionally frothers that have a less stable froth can have improved valuable mineral recoveries, while still exhibiting better drainage for reduced entrainment and mass pull. It was shown that caution should be used when relying only on simplified froth stability tests in the evaluation of new frothers.

Feb 1, 2025

By Ernest Y. Baafi

The technique of linear kriging as a grade estimation method of mining blocks is reasonably established in the mining industry. Because of the nonbias condition imposed in kriging which requires that the kriging weights (?i) add up to one, negative weights are sometimes used in kriging. The use of negative weights is not justifiable from the practical standpoint. Also, negative block grades can be obtained in some extreme situations which makes no practical sense. To guarantee non-negative weights an additional constraint is required in the kriging system of equations. Unfortunately, the nonnegative weight constraint results in a set of non- linear system of equations. In this paper, a derivation of the resulting set of nonlinear equations is presented and a numerical algorithm is developed for the solution of the equations. Because the algorithm developed does not remove negative weights arbitrarily, optimal nonnegative weights are always guaranteed. Results obtained using the developed algorithm were compared with those using the standard linear kriging, in terms of computer time and the estimation results. Both the computer time and the kriging variance were found to be higher with nonnegative constraint, as expected. However, some systematic pattern was observed in the kriged values (i.e., over or under estimation) with or without the nonnegative constraint. The study also demonstrated when one should generally expect negative kriging weights in practice, and what practical impact the negative weights can have on the kriging estimates.

Jan 1, 1984

By Miguel Reyes, Mathew Girman, Chenming Zhou

Modern smart mining increasingly depends on sophisticated electrical and electronic systems for improved safety and productivity. With more electronic systems being introduced underground, the mining industry faces electromagnetic compatibility (EMC) issues caused by electromagnetic energy emitted by one device adversely impacting the normal function of another. This paper provides an overview of EMC and electromagnetic interference (EMI) research for underground mining, including a review of EMI in other industries applicable to mining, published EMI research pertaining to mining applications, representative EMI incidences, related EMI legislation in mining, and mitigation strategies.

Jan 3, 2022

By A. P. Mehta

The role of microorganisms in the leaching of metal sulfides is well established (Torma, 1977; Murr, 1980). However, this established knowledge applies mostly to chemolithotropic microorganisms such as Thiobacillus ferrooxidans which function optimally in leaching catalysis between 25-35° C, and in a pH range of 2-2.5. Although leaching with thermophilic microorganisms capable of extending the range of catalytic viability beyond 35° C is also documented, there are few if any attempts to optimize or extend sulfide concentrate leaching with thermophilic microorganisms. When mixed metal sulfides or other materials having different rest potentials (referenced to the standard hydrogen electrode, SHE, in the electromotive series) make contact in a conducting, aqueous medium, the contacting members will act as an electrochemical cell, with the member having the higher rest potential assuming the role of an electrical cathode. In leaching reactions involving such galvanic couples, the cathode becomes passivated, while the anodic member reacts vigorously due to the electro- chemical reaction which occurs (Hiskey and Wads- worth, 1975). Serry, eta1 (1978) observed that when chalcopyrite and pyrite were in intimate contact in natural ores, the chalcopyrite reacted vigorously by galvanic conversion as a result of the higher rest potential (~ 0.63 V) as compared to the chalcopyrite (~ 0.53 V). In addition, it was postulated that because of the elemental sulfur which can form on the anodic chalcopyrite in this galvanic conversion process, reactions in acid-bacterial medium would be expected to have accelerated copper extraction because of the conversion of any sulfur product layer on the chalcopyrite anode to sulfuric acid according to the following general reactions: [MS?M2+ + S° + 2e- (1) and 2S° + 302 + 2H20 bacteria?-2H2SO 4 (2)] where M in reaction (1) designates the metal (or metals in the specific case of chalcopyrite) to be released to solution by galvanic conversion.

Jan 1, 1982

By N. J. Themelis

Autogenous grinding, broadly defined as the self-comminution of ore in a cylindrical tumbling mill without using auxiliary grinding media, was first applied in the early thirties in the so-called Hadsel mills (Figure 1) mainly used in gold mines on the U.S. West Coast. A number of these mills were built in sizes of 20 to 24 ft. in diameter and five-six feet in length but were later abandoned because of operating and maintenance problems. Further development of autogenous grinding led to the Hardinge wet grinding mill (Figure 2), the Aerofall dry grinding mill and others. A tabulation of all known autogenous and semi-autogenous installations around the world was sent recently to the authors by Hr. G. J. Kushner of the Koppers Mineral Processing Division. In the size range of 24 to 32-ft. in diameter, it lists a total of thirty mills used in the processing of copper ores. An additional 120 units are listed in the same size range for the processing of iron ores and other minerals. The largest mills in existence are 36-ft. dia X 15-ft. long mills in Minnesota, powered by 12,000 hp. motors and used in taconite beneficiation. It is indicative of the phenomenal growth of this technology that none of the above one hundred and fifty mills was in operation prior to 1964.

Jan 1, 1978

By William L. Young

I think I should let you in on one of Canada's best-kept secrets, if you will promise not to tell it all over the place. Believe it or not, good, honest, enterprising capitalism is still alive and flourishing north of our common border, and I am living proof that capitalism is still working for the little guy. My personal story of mining development in Canada isn't all that rare -- you've probably heard something like it from other areas and other days several times -- but my case brings it up-to-date. I would like to Tell you briefly the history of Northumberland Mines Limited, a contemporary case of individual enterprise getting a mining operation underway. And if I can do it you probably can too.

Jan 1, 1981

By R. F. Davis

The evaluation and selection of coals for producing metallurgical coke is indeed a com- plex process simply because coal is a complex and variable substance which is sensitive to how it is treated from the time it is mined until it is transformed into coke. A review of the the more common evaluation tests made on coal and how the test results are applied in commercial practice. Parameters used to select coal blends for wet and preheated charges should also be of interest.

Jan 1, 1980

By Ali Soofastaei

Mining operations are increasingly data-rich yet decisionconstrained. Fragmented systems, variability in geology and operations, and sustainability obligations create multiobjective trade-offs that classic analytics cannot reconcile at operational tempo. This paper proposes an end-to-end framework that fuses digital transformation practices (governed data platform, semantic layer, feature store, and MLOps) with generative AI (retrieval-augmented generation, tool-use, and agentic workflows) and decision intelligence (simulation/digital twins and multi-objective optimization). We formalize sustainability-aware objectives, define a practical stack and governance controls, and demonstrate how an AI “decision copilot” can surface options, quantify trade-offs, and document rationale. Two figures illustrate a production-grade architecture and a Pareto frontier for cost–emissions trade-offs; two tables operationalize decision-domain mapping and a transformation maturity rubric. The approach is product- and company-agnostic.

Feb 22, 2026

By F. Arslan

Gold extraction from refractory ores is still a problem. Gold losses in the cyanidation process are mainly due to the presence of sulfides and carbonaceous materials. Oxidation of carbon and sulfide minerals by sodium hypochlorite is a possible method to render the ore amenable to cyanidation, and earlier work by the USBM indicates that electrochemical generation of hypochlorite is promising. Laboratory work was carried out on the oxidation of pyrite and carbon in an electrochemical cell with a sodium chloride electrolyte. The results of preliminary tests are discussed in relation to the mechanism of electrooxidation of refractory gold ores and the estimation of current efficiency.

Jan 1, 1991

By C. J. Slaughter, S. P. Harteis, L. L. Chasko, D. W. Alexander

The Department of Health and Human Services (HHS), National Institute for Occupational Safety and Health (NIOSH), Office of Mine Safety and Health Research (OMSHR), with the assistance of cooperating underground mining operations and state agencies, has conducted research exploring devices and technologies that could be used to assist miners navigating through smoke and dust resulting from a fire or explosion. Recent events in mines confirm that smoke and dust can enter and contaminate mine escapeways, creating an atmosphere with severely reduced visibility. This reduced visibility results in substantially increased escape times, possible disorientation or confusion, and increased stress levels, and may prevent evacuation altogether. Tools or devices that assist miners in navigating through smoke-filled areas void of lifelines could make the difference in successful escape from the mine. This paper presents the results of OMSHR research to identify and evaluate tools and devices that could provide meaningful information to evacuating miners in areas with limited visibility and without the benefit of a lifeline.

Jan 1, 2011

By S. Wegerer, M. Semel

The search for minerals typically starts with a reconnaissance phase. After finding a promising target area, further prospecting work will be conducted. Finally with growing confidence of having encountered an ore deposit with commercially viable concentrations of relevant minerals, an extensive exploration campaign will verify its potential. Best practice and reliable, efficient tools for mineral resource estimation of massive sulfide deposits in the deep sea have to be established yet. Therefore, a new seabed exploration system is in development. Various challenges are caused by the extreme environmental conditions in the deep sea and by the nature of massive sulfide deposits. Information of past and ongoing expeditions were gathered to form the basis of an in-depth requirement analysis. System functions and corresponding process times were derived. The experience from the existing MeBo seabed drill rigs serve as starting point for the concept study and following development. Initial MeBo system was built for maritime research purposes and now has to be converted into a new design, suitable for efficient and economic resource exploration. The new system configuration is modular structured to adapt easily to different application scenarios and challenges. To achieve an extension of the deployment depths, the overall equipment weight has to be limited through light weight construction and material. The drilling module contains a range of geotechnical coring tools to face the varying soil conditions of heterogeneous massive sulfide formations. The major challenge to overcome is the touch down sequence on uneven, 25° inclined, rough terrain in up to 4.000 m water depth. Furthermore, high precision of the final unit positioning is necessary. Landing sub-system proof of concept is validated in laboratory environment with small scale model. A novel seabed exploration system capable to land and operate safely on highly inclined slopes of mineral deposit is described. Obtaining high quality samples by wire-line coring technique is the objective.

Feb 22, 2026

By P. R. G. Bak

The integration of interactive computer graphics technology with data analysis tools can assist in the evaluation of deposit models: the super- imposition of mine openings on complex geology can be quickly perceived using dynamic visualisation, colour-coding and transparency control while analysis functions assist in quantifying displayed information. To illustrate the functionality of such integration a research prototype system is presented which allows the interactive visualisation and evaluation of deposit models comprising both structural boundaries and the distribution of continuous properties.

Jan 1, 1992

By Raymond K. Will

Computers are becoming increasingly valuable tools in the mining industry as a greater variety of appropriate hardware and software becomes available, combined with greater acceptance by management, Within a given time period an engineering staff can evaluate or design a project to much greater detail and higher accuracy by utilizing computers once suitable programs have been developed. We are all aware that throughout the world the decreasing grade of minerals coupled with increasing waste to ore ratios necessitate larger capacity, longer term mining operations and attendant higher capital costs. Computers can be of assistance in all stages of mineral exploitation, from geologic exploration through mine feasibility studies and design, to marketing and transportation. Because of the high speed with which data can be digested and manipulated by computers, preliminary information from any stage of investigation can be analyzed to assist in further guidance of that stage. By use of preliminary mine feasibility studies, financial forecasts and sensitivity analysis, even information from a far-removed phase such as marine transportation of the product, can help guide the exploration phase to a realistic target.

Jan 1, 1973

By E. A. Schmidt

In 1962, while investigating the tungsten potential in the Thompson Creek area for Union Carbide Corp., Henry T. Eyrich obtained anomalous concentrations of molybdenum (up to 19 ppm Mo) from stream sediment samples collected along Pat Hughes Creek, a tributary to Thompson Creek. Follow-up investigations by Eyrich during the same year disclosed the presence of a hydrothermally altered and molybdenite-bearing granitic exposure in the headwaters of Pat Hughes Creek about 2.4 km (1.5 miles) upstream from the sample point. The altered outcrop measured about 549 by 305 m (1800 by 1000 ft), contained abundant northwest-trending quartz veins locally with molybdenite, and was overlain and surrounded by the Challis volcanic extrusive sequence of mid-Tertiary age. Eyrich's subsequent soil and rock chip geochemical sampling program over the altered outcrop area showed a general increase in the molybdenum content to the northwest toward the postmineral Challis volcanic cover. Over a distance of about 305 m (1000 ft), values in the altered intrusive rock increased from less than 5 ppm Mo to over 600 ppm Mo, with aconcomitant intensity of the hydrothermal alteration pattern. Based on these geochemical results and on preliminar; megascopic hydrothermal alteration studies, Eyrich correctly concluded that the altered outcrop is an erosional window and that molybdenum mineralization of sufficient grade could exist beneath the Challis volcanic cover some distance further to the northwest. His recommendation to test the area of potential molybdenum mineralization with several drill holes was, however, declined by Union Carbide in 1962. The property remained unclaimed until 1967, when Eyrich joined Cyprus Mines Corp. Acting on Eyrich's recommendation, Cyprus immediately staked 26 lode mining claims to cover not only the altered intrusive outcrop, but also the northwest trend of mineralization where it projected beneath Challis volcanic rocks. Eleven of these claims are now patented.

Jan 1, 1991

By C. I. Basilio

The mechanisms involved in the adsorption of modified thiol-type collectors on sulfide minerals have been investigated in the present work. These collectors belong to the broad classes of thionocarbamates, thioureas, thiophosphates and thiophosphinates. They differ significantly from the traditionally used thiol-type collectors, such as xanthates and dithiophosphates, in terms of structural features that involve either the introduction of an additional oxygen donor or the alteration of electron densities on donor atoms. Electrochemical studies suggest that the adsorption of these classes of collectors is probably the result of a coupled reaction of the EC-type, involving an initial electron transfer step (E), followed immediately by a chemical reaction (C). Thus, the overall adsorption process is controlled by both the E, and pK of the system. The role of structural features in changing the interaction of the donor atoms with sulfide minerals is also discussed.

Jan 1, 1991

By William F. Lawrence

Research performed by the West Virginia University Coal Research Bureau under the sponsorship of the U. S. Bureau of Mines has demonstrated that coal-ash can be converted into mineral wool insulation of a quality equal to commercial grade mineral wool. An unexpected benefit has been gained due to the discovery that the usual and costly fluxing agents employed when using conventional raw materials are not required when producing mineral wool from coal-ash. Because coal-ash sources are commonly located close to mineral wool marketing areas and because mineral wool is seldom shipped far as a result of its low weight and high volume, the use of coal-ash may offer the mineral wool producing industry profitable opportunities. Moreover, coal-ash produced from experimental limestone based air pollution control processes also yields high quality mineral wool which may aid in retarding corrosion of metals contacted by the wool. In addition, internal fluxing effects and possible sulfur oxide utilization could provide economic advantages to the use of these "modified" ashes.

Jan 1, 1969

By NEHA PANDEY, V.K. REDDY KALLAM, SUNIL KUMAR TRIPATHY, ARIJIT BISWAS

This work discusses the sulfur dioxide (SO2) leaching of low-grade ferruginous manganese ores to selectively recover manganese (Mn) as manganese sulfate (MnSO4), followed by electrowinning of the purified MnSO4 to produce electrolytic manganese dioxide (EMD). The effects of the leaching process parameters on Mn recovery were studied, and the leaching duration and SO2 flow rate were found to have significant effects. Under the optimum conditions derived for grade 1 ore (with total Mn content of approximately 17.16 percent), the specific SO2 requirement (SSR) — that is, the SO2 flow rate per gram of Mn in the leach slurry — was calculated to be 0.014 L/min. At the SO2 flow rate calculated using SSR for grade 2 ore (with total Mn content of approximately 26.29 percent), a Mn recovery rate of 94 percent was realized. Electrowinning of the purified MnSO4 generated after leaching resulted in EMD with 88.01 percent purity and a γ structure.

Sep 1, 2022

By James J. Olson

Most of the projects summarized in this paper are funded under the Bureau's Advancing Metal-Nonmetal Mining Technology program and are part of the in situ mining subprogram coordinated at the Twin Cities Mining Research Center. The borehole mining equipment development, are funded under the Bureau's Advancing Coal Mining Technology program, is essential to accelerated progress in the in situ mining subprogram, and some background information on this concept is included. The initial in situ research projects started in 1971-72 evaluated some of the critical blast design parameters for in situ copper leaching. The present program totals about $1 million per year and includes in-house research projects, cooperative (cost-sharing) projects with the mining industry, and research and development contracts. Two different extraction schemes are under investigation: inplace leaching and borehole (or slurry) mining. The principal commodity targets for the Bureau's improved in situ mining technologies include copper, uranium, coal, and potash. The principal purpose of this paper is to inform the mining industry of the in situ mining research recently completed or being conducted by the Bureau of Mines. In addition the Bureau encourages companies to comment on the program accomplishments as well as offer suggestions on top priority research needs for improving the in situ mining methods described in this paper.

Jan 1, 1977

By Osvaldo A. Bascur

Standards and Technology for bringing information at the desktop has greatly evolved in recent years. The benefits to be realized depend on how these new tools are embraced at the performer level. A key operating challenge is to ensure collective effort is geared towards the most efficient achievement of identified operating and corporate objectives. Presentation, application and data repository modular software are emerging in successful client server applications. The industrial desktop emerges as the new tool for continuous improvement and innovation in industrial operations. Here, process information, reliability maintenance, process simulation, production schedules, performance monitoring are integrated using Microsoft enabling tools at the desktop. A workflow model is presented to assist in implementing a strategic information system in metallurgical plants.

Jan 1, 1996

By Douglas F. Stevenson

Your committee doesn't assign any easy topics to us speakers. How do you define "successful" in what is essentially a losing game? I am reminded of the fellow who returned from a one-week vacation in Las Vegas, and proudly stated, "I only lost $150." To him, that was "success." I am afraid that workers' compensation is a losing game for employers, too, and success has to be defined in terms of how much or how little is lost. We have no chance of producing a profit for our employer. We will narrow down to some suggestions about conducting a workers' compensation program at the plant level, but first I want to discuss the general legal, social and legislative climate in which your plant program operates. Workers' compensation is a statutory program with its general parameters established by the legislature. These parameters are then amplified by the boards and commissions established to administer workers' compensation. What influences the legislature and the boards and commissions as they establish the framework in which we must function?

Jan 1, 1986