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By Rongdong Deng

A tower-like magnetic system comprising eight permanent magnets was installed at the center of a flotation column to separate chalcopyrite and pyrrhotite minerals. A cyclonic flotation was installed within the underpart of the column to separate the pyrrhotite from the gangues. A three-product magnetic flotation column was fabricated to create a magnetic field and a cyclonic zone. The products were Cu concentrates, pyrrhotite concentrates and tailings. The theoretical magnetic field strengths and the magnetic forces were calculated. The results of the flotation experiments showed that the Cu grade increased from 14.20% without the magnetic field to 26.40% in the presence of the magnetic field and that the S grade in the pyrrhotite concentrates increased in the presence of cyclonic flotation. The separation efficiency of this magnetic flotation column was evident. Therefore, this three-product magnetic flotation column may have a potential application, due to its high separation efficiency.

By Justyna Swolkień, Nikodem Szlązak, Dariusz Obracaj

Polish coal mines are characterized by severe geological conditions and the co-occurrence of natural hazards. These hazards are associated with methane and dust emissions during mining processes which can provide methane, dust or methane-dust explosions. Besides, there are such natural hazards as gas and rock outbursts, rock bursts, spontaneous combustion of coal and environmental heat load. The mutual influences of various geological conditions, as well as the natural hazards, intensify the increase of the methane explosion hazard. The occurrence of methane explosions in the Polish mining industry between 2013 and 2108 are analyzed. Fatal accidents are compared with similar events in the global mining industry. The methods of preventing the explosion hazard as well as methane emission control in the Polish coal mining sector are presented. Methane hazard prevention should be adapted to levels and other natural hazards, especially those related to ventilation of underground mine. The methods of preventing methane emissions into mine excavations are often contrary to the means of preventing other ventilation-related hazards in the underground mine, e.g. the prevention of spontaneous combustion of coal in the goaf of longwall panel. Therefore, the design of longwall panels should be preceded by a detailed analysis of the results of both methane emission prediction and forecast of other ventilation-related hazards.

By Ihsan Berk Tulu, Ted Klemetti, Deniz Tuncay, Cicek Sena, Zhao Haochen

"Analysis of Longwall Pillar Stability (ALPS) and Analysis of Retreat Mine Pillar Stability (ARMPS) treat the pillar as a passive structure that is designed to carry overburden dead-weight. This dead-weight is calculated by simple rules based on the geometry of the mining, such as “tributary area theory,” “pressure arch theory,” and “abutment angle theory.” Although the pressure arch loading approach indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology of the overburden in load calculations. The relationship between successful pillar layouts and overburden geology can be incorporated into the load calculation by using the Ground Response Curve (GRC) approach.This paper introduces the GRC modeling methodology to investigate the effect of overburden geology and excavation geometry on load transfer mechanisms using seven field measurement case studies from four U.S. mines. It was also shown that the modeling methodology used to derive GRC in this study approximates mining-induced stresses and deformations within 5% of the values measured in the field.INTRODUCTIONFrith and Reed (2017) stated that current state-of-the-art pillar design methods ignore the overburden mechanics and use estimated dead-weight of overburden to compute pillar sizes. In the United States and around the world, overburden loading is typically estimated by simple geometric rules, generally with the tributary area theory (TAT). The specific overburden mechanics, structural competence of the overburden strata, geology, in situ stresses, and overburden/pillar interactions are typically ignored. However, these important mechanical responses affect the stability of the mine pillars and openings; therefore, they also affect the safety of the mine workers.Research conducted by the National Institute for Occupational Safety and Health (NIOSH) after the Crandall Canyon mine disaster (Esterhuizen, Mark, and Murphy, 2010) showed that small panel width-to-depth ratios and stiff-strong overburden result in a reduction of the observed pillar loads, much smaller than the TAT estimate. In fact, as a response to the Crandall Canyon disaster, Mark (2010) implemented a pressure arch loading approach into the latest ARMPS program to recognize the inherently greater stability of narrow panels at depth. The pressure arch approach is a first logical step to introducing non-tributary area loading into the practical ARMPS program. Although the pressure arch loading indirectly accounts for the generally stiffer overburden response of narrow and deep panels, it does not include the effect of specific geology and mechanical response of overburden in the load calculations."

Jan 1, 2019

By R. L. Virta

Four companies ? H.C. Spinks Clay Co., Inc., Imerys, Old Hickory Clay Co., and Unimin Corp. ? mined ball clay in four states in 2013. On the basis of preliminary data, production was 1 Mt (1.1 million st) with an estimated value of $47 million. Production increased by 3 percent in tonnage from 973 kt (1.1 million st) with a value of $45.1 million in 2012. Tennessee was the leading producer accounting for 64 percent of domestic production, followed by Texas, Mississippi and Kentucky. About 67 percent of total ball clay production was airfloat, 22 percent was crude or shredded and 11 percent was water-slurried.

By K. M. Mohamed, R. K. Zipf

The shear strength properties of generic cement foam material and cement foam/concrete interfaces were examined at three testing scales. In laboratory direct shear tests on specimens with average shearing area of 0.006 m2 (10 in.2), the cement foam material had average peak and residual shear strengths of 0.88 MPa (128 psi) and 0.39 MPa (56 psi), respectively. Depending on the concrete strength, the cement foam/concrete interfaces had peak and residual shear strengths ranging from 0.71 to 0.81 MPa (103 to 117 psi) and from 0.27 to 0.29 MPa (39 to 42 psi), respectively. In laboratory direct double shear tests on specimens with average shearing area of 0.084 m2 (130 in.2), the cement foam/concrete interfaces had average peak and residual shear strengths of 0.17 to 0.30 MPa (25 to 44 psi) and of 0.11 to 0.23 MPa (16 to 33 psi), respectively. In large shear tests of simulated cement foam seals with the Mine Roof Simulator (MRS) test frame, cement foam/concrete interfaces with shearing area of 1.486 m2 (2,304 in.2) had average shear strengths of about 0.08 and 0.16 MPa (11 and 23 psi) along the roof and floor interfaces, respectively. The average shear strength through the cement foam material was 0.38 MPa (55.3 psi). Finite element analysis of the large seal tests and the back analysis of the shear strength of full-scale cement foam seals conducted at the NIOSH Lake Lynn Laboratory confirmed shear strength of about 0.14 MPa (20 psi) along the seal/rock interfaces. The study concluded that the structural analysis of cement foam seals should be based on their residual shear strength determined from small laboratoryscale tests of the cement foam/concrete or rock interface and not be based on their peak strength.

Jan 1, 2014

By Andres Salazar, Carlos Delgado Robles, Richard K. Preece

Minera Escondida, located in the Antofagasta Region of northern Chile, is the world’s largest producer of copper as concentrate and SX-EW cathode. Projects to increase mill and flotation capacity began soon after start-up in 1990 to off-set decreasing copper grade. Subsequent projects had the objective to increase copper production through heap leach and SX-EW production and a second concentrator. The mine footprint concurrently expanded peripherally from the central high-grade enriched core of Escondida and then into the separate Escondida Norte deposit. Early in the mine life, metallurgical forecasting that was based on metallurgical composites of presumed ore types and historical plant production was adequate for operational planning, plant design, and project valuation. This approach became unreliable, however, as the increase in mine footprint was accompanied by an increased variability in key ore body characteristics such as hardness, copper-iron sulfide mineralogy, and sulfide liberation textures that were not reflected in the geological criteria used for ore type designation. The project study teams turned to small-scale physical and chemical tests to better characterize the spatial distribution of these key ore characteristics. Programs associated with capital growth projects were carried out through the mid-2000s to sample and construct a three-dimensional spatial model of hardness, copper sulfide mineralogy, and rougher flotation recovery from tests on 15-m drill core composites. Mathematical models were developed from the respective ore characteristic data to calculate throughput, flotation recovery, and concentrate copper grade. The spatial models were integrated with the concurrent mineral resource block model using standard geostatistical methods and the metallurgical process calculations were applied to the block estimates. The geometallurgical model, originally constructed on a project basis, is now managed by a dedicated team reporting to the manager of Geosciences & Resources Definition in the Escondida organization. The model has evolved with increasing complexity of the mine and processing plants and currently includes seven forecasting areas for three concentrators and four areas for two leach plants. Metallurgical forecasts of mill throughput, final flotation recovery, and concentrate copper grade still have the highest relevance to mine planning and optimization. Sample preparation, test procedures, and quality control methods are summarized for the ore characteristic tests important to these forecasts. Analytical results from recent annual sampling programs are presented for the hardness indices, rougher flotation recovery, and partial extraction copper analyses. Geostatistical analysis of the SAG mill hardness index is summarized as an example for the spatial estimation process. Mathematic models are presented for throughput (based on hardness indices), final flotation recovery (based on rougher recovery and plant calibration studies), and concentrate copper grade (based on sulfide mineralogy and empirical pyrite rejection studies).

Aug 31, 2023

By Juan Camus

To understand why some companies excel in creating value, Jim Collins (2001) and a group of postgraduate business students engaged in a comprehensive, five-year research project. They examined 1,435 U.S. companies for more than 40 years, seeking those that made significant improvements in their financial performance over time. The distinctive pattern sought was: ?Fifteen-year cumulative stock returns at or below the general stock market, punctuated by a transition point, then cumulative returns at least three times the market over the next 15 years. ?The search identified 11 outperforming companies, all in different industries, that were called the ?good to great? companies. To contrast these companies with similar peers within the same industry, the search also selected a group of comparison companies that failed to make the leap from good to great. Collins then set out to examine the transition point. What distinguishing features did the good-to-great companies have that their industry counterparts did not? At the heart of the findings about these outstanding companies is what Collins refers to as the ?hedgehog concept? ? how to find the one big thing that the company must focus on. According to Collins, those who built the good-to-great companies were, to one degree or another, hedgehogs. Those who led the comparison companies tended to be foxes, never gaining the clarifying advantage of a hedgehog concept, being instead scattered, diffused and inconsistent. This insight is complemented by Peter Drucker (2004), an influential management guru, who asserts that the first question an effective executive should ask is: ?what needs to be done?? Asking this question and taking it seriously, he asserts, is crucial for managerial success; and that the answer almost always has more than one urgent task, but the effective leader only concentrates on one task. In this last respect, Drucker emphasizes: ?If they [executives] are among the sizeable minority who work best with a change of pace in the working day, they pick two tasks. I have never encountered an executive who is effective while tackling more than two tasks at a time.?

Jan 1, 2011

By Jr. Pitts

Elevation of surface charge density on colloidal particles in the presence of a high potential electrostatic field is demonstrated as a viable technique for preventing the accumulation of solids in solvent extraction circuits. The effect of the technique is manifest by relative turbidity measurements between pregnant leach solution and raffinate, by changes in the character of the sludge accumulations, by alteration of the zeta potential of particulates, and by a general reduction in the mass of solids.

Jan 1, 1992

By D. Chakravarty, G. Samanta, B. Samanta

The present study highlights the planning and design aspects of a well-known openpit copper deposit in India. The mine has been operational since 1982 and presently reaches a depth of 168 m below the surface. The present planning effort has been given due consideration in view of the recent upsurge of copper prices in the global market. The prime focus of the study has been directed towards examining the possible extent of final pit beyond the current pit outline and generating an extraction sequence of future mining operations. To this end, an orebody model of the deposit has been developed and the optimized pit has been derived using L-G 3D algorithm. A sensitivity analysis has also been performed to scrutinize the possible effects of the changing economic scenarios on the ultimate pit configuration. It has been observed that with the current production rate, mine life can be extended another 40 years. With a five-year production plan, these materials can be extracted in eight push-back schemes. The extraction sequence of these push-backs has been outlined in this paper.

Jan 1, 2011

By Feng Liu

"With seven new applications for plans of work for exploration in the international Seabed Area approved by the Council during its twentieth session of the International Seabed Authority, 26 total approvals have been made by the Council up to date. Among them, three contracts were made with COMRA. On 8 August 2014, China Minmetals Corporation submitted another application to the Authority for approval of a plan of work for exploration for polymetallic nodules in the Area, which is also sponsored by the Government of the People’s Republic of China.China is one of the main contributors to the international seabed regime. The Presentation will describe China’s activities in the Area, such as exploration, technology development, environmental protection and policy making.JIAOLONG is a submersible with capacity of 7000 meters. JIAOLONG’s sea trials were carefully made in 4 years, from 2009 through 2012 and it successfully dove to a depth of 7062m in June 2012 at Mariana trench. A so called "Test Application Phase" started thereafter, and is planned to last for 3-4 years. Two cruises and 4 legs have already been made since then. A wide-range of findings were obtained during dives in South China Sea, and in COMRA’s Exploration Contract Areas for polymetallic nodules and cobalt-rich ferromanganese crusts. This presentation will reveal the colorful findings."

Sep 1, 2014

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 Minerals and Materials Analysis Section

During 1996, US mines produced 319 t (10.26 million or) of gold metal valued at $4 billion. At yearend, mine reserves were estimated to be 4.7 kt (151 million oz) of gold metal. Almost all of the production was from western states. Nevada accounted for about 68% of national production. Information for this article was obtained through annual reports of mining companies, US Geological Survey (USGS) databases and other public sources. Table 1 shows production and reserves by mine. It divides the mines into two categories. These are producing mines whose primary product is gold, and producing mines for which gold is a byproduct or coproduct. The mines listed in Table 1 accounted for more than 98% of US gold production during 1996. Except the Daisy Mine, the table does not include mines that produced less than 31 kg/a (1,000 oz/year). The Daisy Mine started production in December of 1996. Nor does it contain mines whose byproduct concentrate is

Jan 1, 1997

By Yuting Xue

Classification of rock and coal is one preliminary problem for fully automated or intelligent mining. It assists in automated rib stability analysis and enables the shearer to adjust the drums without human intervention. This paper studies the classification of rock from coal on rib images using machine learning techniques. A database of rock and coal images was created by filtering photographs taken by NIOSH researchers during site visits. Machine learning was conducted on patches, smaller images randomly extracted from each rock or coal image. After training, the classifier was validated with the testing dataset and achieved an accuracy score of 0.9.

Jan 13, 2022

In early June, Rio Tinto?s chief executive officer Tom Albanese said that he expected demand for iron ore, aluminum and copper to double in the next 15 years. Driven by global industrialization and urbanization, Albanese said during his company?s annual general meeting that to meet the demand in 2030, the additional supply required will be equivalent to replicating the iron ore output of Australia?s Pilbara region every five years, adding another aluminum production complex the size of Canada?s Saguenay every nine months and developing another copper mine the size of Escondida, in Chile, each year.

Jan 1, 2010

By M. Adnan Göksel

Pyrite cinder is generated by roasting pyrite for sulfur dioxide production. It contains up to 62% iron, but also may contain other hazardous or toxic materials such as Zn, Pb, As, T1, Cd, Cu, Sn and S. Furthermore, the physical characteristics are not properly suited for conventional sintering. As a result pyrite cinder is considered to be unsuitable for iron and steelmaking or for outside storage because of its potential for causing environmental problems. In recent years industrialized nations have put increasing pressure on the manufacturers to either use such waste products or properly dispose of them. In this study, solutions to both the iron recovery and disposal problem were attempted by pelletizing the pyrite fines with internal carbon. The pellets, after hydrothermal hardening, were reduced and melted in a furnace for hot metal production. Hot metal of usuable quality was produced and the hazardous materials were either collected with the fumes or in the slag.

Jan 1, 1984

By R. W. Kobler

The pelletizing process for low grade iron ores has undergone continual changes since its inception over twenty years ago. These changes have necessitated filtration equipment changes in order to produce a product suitable for balling. With modern techniques it is now possible to produce pellets of 68% Fe from ores containing as low as 26% Fe. Low grade ores require fine grinding to liberate impurities This shift to finer grinds over the years has necessitated major changes in the filtration steps. Techniques are now available for producing suitable product from ores with Blaines as high as 3600 cm2/gram. This has been made possible by the development of high performance filters. Recent developments have reduced maintenance costs and produced higher production reliability. The paper discusses iron concentrate filtration from its beginning to present day design. It will be shown that the dewatering step prior to balling has gone through four generations of filters. Particular emphasis is placed upon hydraulic studies which have allowed today's optimum designs.

Jan 1, 1978

By R. P. Killmeyer, W. W. Wen, B. K. Parekh

A continuous pilot-scale test of the GranuFlow Process was conducted using a screen-bowl centrifuge for the dewatering and reconstitution of column -flotation concentrate at a coal preparation plant in Virginia. In this test, a slipstream of the fine clean-coal slurry from the column flotation con¬centrate was treated with a bitumen emulsion before dewatering. The treated products from the screen-bowl centrifuge appeared to be dry and in a free flowing granularform, while the untreated products were wet, sticky and difficult to handle. Test results indicated that the average moisture contents of the dewatered coal products were 35.7%, 35.5%, 32.6%, 29.9% and 26.5% (by weight) with Orimulsion additions of 0.0%, 0.7%, 3.2%, 4.8% and 6.4% (by weight), respectively. The handleability and dust reduction of the dewatered coal products were also vastly improved.

Jan 1, 2000

By Eugie Kabwe

Rock bolts are components of tunnel support structures and their efficacy in reinforcement requires the appropriate estimation of the bolt pre-tension. However, cases of ineffective rock bolt application due to loosening are common which leads to the potential failure of the support structures, thus negatively affecting the tunnel stability. The effective employment of pre-tensioned bolt within support structures requires an appropriate installation tension as a result of sufficient bolt head/nut pre-load. Henceforth, this paper presents a load indicator washer (LIW) capable of withstanding assigned static loading as well as provides an appropriate pre-tension. The different LIW breadths are numerically analysed in the finite element code (ABAQUS) to estimate deformation when a designated 60-kN pre-load is applied. The numerical simulation employs a bi-linear isotropic hardening constitutive law governed by the von Mises yield criterion. The simulation also considers the nominal temperature of the nutLIW-rock bolt connection. Therefore, a long-term relaxation effect on bolt pre-tension as a result of stress relaxation is neglected. The compressive force required to achieve the LIW-predetermined deformation is the bolt pre-tension. It is drawn from the simulation results that the 1.5-, 2.0-, 3.0-, 3.5-, and 4.0-mm-thick LIWs are completely flattened when subjected to 28-, 42.5-, 65-, 76-, and 88-kN pre-load respectively.

By W. W. Harvey

The work to be described was part of an exploratory research program directed toward identifying potentially useful but little known reactions in extractive metallurgy. In particular, the major copper sulfide minerals, as a group, have long been considered insoluble in nonoxidizing acids (e.g. Forward and Barren, 1J60; Parsons and Ingraham, 1970; Peters et al. 1972). This generalization was considered to include nonoxidizing conditions in warm aqueous MC1 solutions (Ingraham et al. 1972) and, indeed, was consistent with our own chemical and mineralogical experience. On the other hand, under hydrothermal conditions, copper and sulfide species are carried in solution and deposited as sulfides in mineralized veins. The question that poses itself is: what are the mildest conditions of temperature and fluid composition under which commercially important copper sulfide minerals can be solubilized in the absence of an oxidizing agent? A reference to H2S formation during oxygen-sulfuric acid pressure leaching (Warren, 1958) of chalcopyrite, when the oxygen partial pressure was allowed to fall, provided a clue. In the present study, experimentation with chalcopyrite concentrate in dilute hydrochloric acid, under re flux conditions (in Pyrex flasks) and with an inert purge gas, revealed substantial amounts of H2S production and iron solubilization, cite negligible copper solubilization, after 2 ½ -4 days. Under comparable conditions the extent of reaction with dilute sulfuric, acetic and phosphoric acids was markedly less.

Jan 1, 1976

By JESSICA W. A. AZURE, Samuel Frimpong, AZUPURI G. A. KABA, FORSYTH A. KADINGDI, PROSPER E. A. AYAWAH

This study developed machine learning (ML) models for predicting rock formation reactive forces experienced by a hydraulic shovel bucket during excavation. To do this, rock formation in the form of muckpile was modeled as granular ball elements in three-dimensional particle flow code (PFC) using linear bonding logic. A typical field-size hydraulic shovel bucket modelled in AutoCAD was used to excavate the rock formation and the three-dimensional shovel bucket resistive forces required to cut through the rock formation were measured and recorded. The experiments involved different muckpile height, bulk densities, repose angles, and average fragment size. Six ML algorithms, artificial neural network (ANN), K-nearest neighbor (KNN), linear, random forest (RF), regression tree (RT), and support vector machine (SVM), were evaluated on their ability to predict the shovel bucket resistive forces. The input variables used for the prediction of the resistive forces were the muckpile bulk density, angle of repose, height, and fragment size. The results showed that the ML techniques are useful and reliable methods of predicting rock formation resistive forces based on the rock formation properties. This research is a preliminary step towards developing reliable models for accurate prediction of excavation forces/torques which could potentially enhance hydraulic shovel process automation.

Sep 27, 2021