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By A. M. Martinez, L. Melis, R. C. Peláez, L. G. Garcia

Orovalle Minerals S. L. operates a copper/gold mine in the Asturias region of northern Spain, with the operation dating back to December 1997. The feed to the El Valle mill, consisting of oxide/sulphide (skarn) mineralization, is highly variable, even on a shift by shift basis and presents challenges to the mill operating staff on a daily basis. The mineralogical characteristics of the ore are quite complex with copper present as native copper and sulphides as well as copper minerals with deleterious elements. Gold is present as native gold and electrum. The mill circuit includes SAG/ball mill grinding, gravity recovery of native copper and gold, flotation of copper concentrate, carbon-in-leach gold recovery and SO2/air cyanide destruction. The paper will provide a description of the different unit operations and present operating data of the mill operation.

Jan 1, 2019

By Staff

Minerals contribute to U.S. gross domestic product (GDP) at several levels - from mining and processing to the manufacturing of finished products. In 2010, the estimated real GDP of the United States increased by 2.8 percent compared with 2009 and the estimated nominal GDP was about $14.6 trillion (Table 1).Trends in various sectors of the domestic economy are often rejected in mineral production and consumption rates. For instance, continued declines in the construction industry during 2010 were rejected in further reductions in the production and consumption of cement, construction sand and gravel, crushed stone and gypsum, which are used almost exclusively in construction. Performances in other sectors were mixed and less easily characterized. Recovery from the economic decline of 2008-2009 became apparent in 2010, as prices for many mineral commodities continued to rise with increasing demand for those materials or the products in which they are found.

Jan 1, 2011

By Lina Ospino Ballesta, Oscar J. Restrepo Baena, Juan Diaz Martínez

Artisanal and small-scale underground gold mining in Colombia plays a significant role in the country’s economy, but it faces persistent occupational hazards that threaten worker safety. Despite mining economic contributions, outdated technologies, limited risk management practices, and insufficient regulatory enforcement have led to recurring workplace accidents, many of which have been fatal. This study presents a systematic review of mining-related accidents over the last decade. Through geo-referenced analysis, high-risk municipalities were identified, and the frequency of accidents was correlated with the mining legal status and operational practices of these municipalities. The findings underscore the urgent need for evidencebased interventions that are tailored to the country’s unique mining context. Ultimately, this research contributes to the global discourse on mining safety by highlighting practical pathways to reduce occupational risks and promote safer, healthier workplaces in resource-constrained environments.

Feb 22, 2026

By Dr. O. M Solandt

CANADA is not an old country we are just now planning to celebrate our lOOth Anniversary. Nonetheless, we have already developed some well-established traditions. One of the minor traditions is the standard speech on the need for more research and development in Canadian industry. I am sure that you have all listened to it many times -I certainly have given it more than once. Much as I am tempted to honour this tradition by repetition, I shall only give you a thumbnail sketch of the ancient address for the benefit of any unfortunate visitors who have not heard it before, and also to provide a base for some further ideas that I want to leave with you. Briefly, the traditional story is that, for a variety of historical and environmental reasons that I shall not attempt to describe in detail, research and development in Canada has grown up in a pattern that is ill adapted to foster the expansion of our manufacturing industries. The story continues by saying that research in the universities is of excellent quality but that we are very short of money to meet the expanding needs

Jan 1, 1965

By Richard A. Thomas, III JAMES H. ROWLAND, Liming Yuan

This paper presents the results of large-scale fire experiments on evaluating the performances of carbon monoxide (CO) and smoke sensors at low ventilation velocities. Experiments using three different combustibles — conveyor belt, coal and diesel fuel — were conducted in the experimental mine at the U.S. National Institute for Occupational Safety and Health (NIOSH) Bruceton Research Facility. A total of eight sensor stations were located downstream of the fire with each station containing sensors for CO, smoke, carbon dioxide (CO2 ), oxygen (O2 ), humidity, barometric pressure and temperature, as well as two airflow sensors. The airflow velocity ranged from 0.22 to 0.26 m/s (44 to 51 fpm) in the tests. The response times were recorded for the CO and smoke sensors at each sensor station when smoke and gaseous products of combustion from each burning combustible reached the station. The response times of the CO sensors were used to determine the appropriate sensor spacing in the belt entry with a low air velocity. The performance of the smoke sensor was found to be affected by the high humidity in the experiments. The results on proper selection of sensors and the determination of sensor spacing at a low ventilation velocity can be helpful for ensuring sufficient early fire warning for underground workers, thereby improving the health and safety of miners.

By Maria I. De Rosa

The U.S. Bureau of Mines conducted a study to determine if correlations exist between the chlorine or nitrogen contents of materials and the hydrogen chloride (HCI) or hydrogen cyanide (HCN) concentrations evolved during the thermal decomposition of these materials. Hydrogen chloride, hydrogen cyanide, and carbon monoxide (CO) were found to be the primary toxic gases evolved during the combustion process. The experiments were carried out in a 20-L furnace with 1-g samples. The furnace temperature, rising from ambient, was set at 1,000 °C with an airflow of 10 L/min. The variables measured were the gas loads (milligrams per gram) of HCI, HCN, CO, and CO2 (carbon dioxide); CO and CO2 concentrations as a function of time were also measured. Other variables included the average concentrations of submicrometer smoke particles and particles' average diameter, mass of particulates, sample and furnace temperatures, and sample weight loss. The data indicate that there are significant correlations between the percentage of chlorine or nitrogen contained in the original samples and the HC1 or HCN concentrations evolved during the combustion of the materials. These correlations may be used to predict and evaluate a material's toxic hazard during combustion.

Jan 1, 2010

By John A. Breslin

Size distributions and concentrations of particulates emitted from diesel engine exhausts were measured with cascade impactors. Samples were taken from the exhaust of two types of engines using three types of fuel and operating under five different engine speed and load conditions. The measured mass median diameters of the diesel particulates were typically about 0.3 um. There was no significant difference in mass median diameter between engines or fuels and only a slight dependence on operating mode. Concentration measurements ranged from 14.2 to 250.9 mg/cu m, and calculated mass outputs, from 52 to 3,443 mg/min. Significant differences in mass output were found between engines, fuels, and especially between different operating modes. The quantity of clean dilution air that would be required to reduce the particulate mass concentration below the 2.0 mg/cu m respirable dust standard for coal mines was greater than the dilution air required to meet the standards for noxious gases for both engines tested.

Jan 1, 1976

By Hong Zhong, Shuai Wang, Zhanfang Cao, Ting Dai

"Manganese is widely used in industries such as the steel industry and is now an essential element in modern industry. Technologies for the efficient and clean utilization of manganese resources must be developed and employed to ensure the sustainable growth of the manganese industry. Our research focuses on the use of beneficiation technologies to improve the grade of ores or the replacement of low-grade manganese carbonate ores with high-grade manganese oxide ores, and thus, to reduce reagent and energy consumption and the yield of electrolytic manganese residues from metallurgical processes; the study of leachate purification technologies; the study of electrochemical behaviors during electrolysis and energy-saving electrolysis methods; the development of chromium-free passivators as alternatives to the highly toxic potassium dichromate passivator; the non-hazardous treatment and resource utilization of electrolytic manganese residues and other manganese by-products; and the development of new manganese products. INTRODUCTION Manganese is widely used in the steel industry, nonferrous metallurgy, the chemical industry, electronics, batteries, agriculture, etc. Globally, more than 90% of manganese is consumed by the steel industry, and thus, it is said that ""No steel industry without manganese""(Banerjee et al. 2017, Zhang et al. 2017). Current manganese resources mainly include manganese ores, marine manganese nodules and waste catalysts. The total global output of manganese ore from land deposits is 18 million tons (metal volume), and the reserves, most of which is in the form of manganese oxide ores, are estimated to be 620 million tons (metal volume). More than 400 manganese ore deposits with a total reserve of 1.22 billion tons have been discovered in China. These deposits are predominantly manganese carbonate ores. Marine manganese nodules exist on the surface of the deep seabed at depths of 2000-6000 m. These nodules, which are also called polymetallic nodules, manganese balls, manganese aggregates and manganese tumors, are mainly composed of iron and manganese oxides. The total reserves of these resources add up to more than 3 trillion tons. Furthermore, the manganese in manganese-containing catalysts can be recycled after they become inactive."

Jan 1, 2018

"Sink-float analysis is often used to obtain yield-ash and density partition curves in the coal industry. These provide a valuable tool for evaluating the performance of a separation process. However, for dense minerals, obtaining complete grade-recovery and density partition curves is more difficult due to the lack of heavy liquids available with the required densities. This paper examines a potential solution to this problem which is to perform batch fractionation of mineral samples in a laboratory-scale REFLUX™ Classifier using high viscosity fluidising liquids. The REFLUX™ Classifier is a gravity separation unit consisting of a system of parallel inclined channels positioned above a vertical fluidised bed. Operated in semi-batch mode, a charge of particles is fluidised from below and particles up to a certain density are elutriated from the top of the system. The fluidisation rate is then increased incrementally to fractionate the sample at progressively increasing densities. Previous work by Hunter et al. (2014) and Iveson et al. (2015) has shown that this method provides excellent agreement with yield-ash and partition curves for coal, especially when glycerol solutions are used as the fluidising liquid. This approach has now been extended to obtain the grade-recovery and density partition curves of high density mineral samples. This method has the potential to provide the minerals industry with an effective tool to evaluate the performance of unit operations separating at cut points higher than the available heavy liquids.INTRODUCTIONMeasuring efficiency and effectiveness is of key importance in the continuous improvement of mineral processing plants. For density based separation, one way the performance of a process can be evaluated is the measurement of density-based partition curves. Currently, this is done in the coal industry using the sink-float method, where heavy liquids are used to fractionate particles into discrete density intervals. However, with high density minerals such as iron ore, liquids of sufficient density are rare, and in most cases also pose serious health and safety concerns to laboratory operators. Most commercial laboratories do not perform sink-float separations above a density of about 4400 kg/m3, the maximum density of Clerici solution without operating at excessive temperatures (Koroznikova, Klutke, McKnight & Hall, 2007; Rosenblum, 1974)."

Jan 1, 2016

By D. C. Seidel

The role of surface charge in soluble salt flotation, which was developed in Part 1, is extended to relate the theory to the specific phenomena of KCI- NaCl separations. Temperature-collector solubility relationships, metal ion activation, and particle size effects are discussed.

Jan 1, 1967

By P. S. Sundar

A laboratory method for the simulation of in-situ leaching of uranium was developed under contract to the Interior Department's Bureau of Mines. Simulation tests using sulfuric acid, ammonium bicarbonate and sodium carbonate as reagents and hydrogen peroxide as oxidant were carried out with representative ores from Texas and Wyoming. The tests not only yielded recovery rates of uranium and permeability changes, but also qualitative inferences on the chemical and physical phenomena which occur underground. Leaching with basic solutions was found to be kinetic constrained and with acid solutions, equilibrium constrained. The rapid permeability changes observed when leach solutions were introduced, were probably caused by gas blockages in the packing. Precipitation of calcite or gypsum and the reaction of clay to leach solutions had slow and gradual effect on the packing permeabilities.

Jan 1, 1978

By J. C. Marchand, M. A. Berube

"L'objectif principal recherché lors du broyage d 'un minerai est de libérer adéquatement ses valeurs utiles en vue de leur concentration ultérieure. La pratique courante consiste à tenter d'obtenir un produit de broyage d'une granulométrie constante. Malheureusement, les propriétés texturales des minéraux utiles varient naturellement dans un gisement et une telle stratégie n'entraine pas toujours pour ces minéraux un degré de libération constant. Pour un rendement optimal du procédé de concentration, cette variable très importante doit donc être périodiquement vérifiée.Jusqu'à maintenant, la plupart des études de libération des minerais se font en examinant des sections polies de particules du minerai broyé. Le GRAAIM a récemment assemblé un système modulaire d'analyse d'images qui servira en grande partie à des mesures automatiques du degré de libération des minéraux. Le système s'avère relativement peu coûteux comparativement à la plupart des analyseurs de texture conventionnels si l'on considère que plusieurs de ses composantes, par exemple le miniordinateur, sont utilisées à une foule d'autres applications, et il permet de plus une grande souplesse d'utilisation puisque l'on a qu'à construire des algorithmes de mesure et de calcul en fonction de l'objectif recherché. Des programmes particuliers permettant des études automatiques de libération sur des sections polies de particules ont ainsi été élaborés. Ils permettent également des mesures de teneurs et de distributions granulométriques apparentes des particules. Des résultats obtenus dans le cas de minerais de fer sont brièvement présentés afin d'illustrer la technique."

Jan 1, 1983

By S. Zhao, S. P. He, M. Y. Zhu, Y. Tao

"The effect of two refining slags (A: 1.0–1.8 CaO/Al2O3 ratio, 11–20 wt% SiO2; and B: 1.0–1.2 CaO/SiO2 ratio, 25–35 wt% Al2O3) on the inclusion morphology of a carbon structural steel (Q235B) was studied by controlling the balance between the steel and the refining slag at 1600ºC in a Si–Mo resistance laboratory furnace. The results showed that most of the inclusions in the molten steel balanced with slag A were formed by a lowmelting CaO–MgO–Al2O3–SiO2 system with a total oxygen content (T[O]) being fixed at 6–13 ppm. The inclusions in liquid steel balanced with the slag B were mostly formed by the CaO–MnO–Al2O3–SiO2 system, with T[O] controlled to 19–26 ppm. The overall size of the inclusions under balance conditions was higher in the steel reacted with the slag B than that reacted with slag A, with the latter showing more inclusions smaller than 3 um. In order to generate a large number of spherical CaO–MgO–Al2O3–SiO2 inclusions smaller than 3 ??m while decreasing the T[O] in the resulting steel, the composition of slag A should be used. This composition allowed improving the cleanliness of the slab, and is also advantageous for the castability of the molten steel. IntroductionThe sample used in this study was a typical carbon steel manufactured by CQ Steel. The galvanized, tinned, and plastic composite steel plates made of the original plates are used extensively for decorative panels, general dust pipes, drums, instrument cases, switchboxes, and train cars, among other uses. The target control composition is shown in Table I. The S and P contents are usually fixed during production below 0.020 and 0.025 wt%, respectively, with the aim of reducing longitudinal cracks on the slab surface."

Jan 1, 2017

By A. B. Coates

During the last three years the use of ethylene glycol dinitrate4 (E.G.D.) as at low-freeze (L.F.) agent in place of nitropolyglycerin has become common in the manufacture of explosives of the dynamite type. The usual proportion of D. G. D. in the explosive "oil" is 25 per cent; the remainder, 75 per cant, is regular nitroglycerin. These proportions were probably selected as a continuation of the practice of 25 per cent nitropolyglycerin and 75 per cent regular nitroglycerin.

Jan 1, 1929

By Bernard S. Covino

The Bureau of Mines is conducting a study of methods to improve the efficiency of the process used to pickle stainless steels. A review of the literature on pickling of stainless steels showed that the chemistry of several process operations involved in the pickling of stainless steels is not fully understood, and that further research could improve the pickling efficiency. The benefits of this research would be a reduction in the annual loss of several thousands of tons of critical minerals such as nickel and chromium, and a reduction in the amount of solids and spent acid solution that are currently discarded. The conclusion from this review is that further research is needed in four operations that either directly or indirectly influence the pickling process: hot working, annealing, conditioning, and the actual operation of pickling, Laboratory studies of the pickling operation are presently in progress.

Jan 1, 1984

By John D. Morgan

The United States is the world's most productive nation and its citizens enjoy one of the highest material standards of living of any people in the world. Materials and energy are the lifeblood of any industrialized economy. Annually the United States uses over 4 billion tons of mineral materials and fuels, or 40,000 pounds per person as detailed in Figure 1. Domestic processed materials of mineral origin and energy are valued at more than $150 billion annually, and they are derived largely from domestic sources, supplemented by imports, as detailed in Figure 2. In recent years the superior productivity of the United States has also enabled it to give food and manufactured articles to many other less fortunate nations and peoples of the earth. What then is our concern with materials at this time? Seeing the burgeoning increases in our mineral demand: from 2 billion tons in 1950, to over 4 billion tons today, and projected to 11 billion tons by 2000 - we are getting questions concerning our ability to continue to increase production sufficiently for the future.

Jan 1, 1974

By R. W. Schenker

INTRODUCTION Environmental and occupational safety and health requirements often have a major impact on the design of comminution circuits, leading to increased capital and operating costs and reduced income. A project's capital cost can be increased by environmental permitting delays and the addition of dust collection equipment. Income can be reduced by lost production during unscheduled plant shutdowns for dust collection equipment maintenance. Dust collection equipment must be carefully selected and sized to minimize impact on the project. The equipment performance must comply with environmental regulations and allow working areas to comply with occupational safety and health regulations. Unnecessary overdesign could jeopardize the project's desirability from an economic standpoint. The equipment must be sufficiently reliable to avoid interference with production schedules. This chapter provides practical information on the selection and sizing of comminution circuit dust collection equipment that is consistent with the requirements stated above. It presents information on the reasons and general principles of dust collection; various types of dust collection equipment; and design criteria for ventilation hoods, duct systems, fabric filter dust collectors, and fans. An example discussing the selection and sizing of dust collection equipment for a simple comminution circuit is also presented. REASONS FOR DUST COLLECTION Dust collection equipment should be installed in comminution circuits for a variety of reasons, some of which are discussed below. These include compliance with government regulations, minimization of housekeeping requirements, product recovery, and improvement in public and employee relations. Compliance with Government Regulations Dust emissions from comminution circuits must comply with both air pollution control and occupational safety and health regulations. The regulations that may influence the selection of comminution circuits are discussed in more detail in Chapter 2. Air pollution control regulations limit the emission of dust, as well as visible emissions to the atmosphere and the concentration of dust in the ambient air. These regulations minimize the degradation of air quality and impact to other environmental considerations such as the health of the general public,

Jan 1, 1982

By Simón Díaz‑Quezada, Ernesto Arancibia, HUMBERTO ESTAY, Tomás Vargas

In situ leaching (ISL) is an attractive technique that enables copper recovery from copper oxide ores that are either low-grade or located at depths too great to be economically exploited through conventional methods. At present, in situ leaching (ISL) has been applied to intact copper oxide ores, in particular, those which (i) present a good natural permeability and (ii) do not require preconditioning. Many copper oxide ores present low natural permeability. These are located above the water table and need preconditioning for the ISL application. The present work shows an economic assessment of the application of ISL to this type of copper ores. The preconditioning technique considered here involves the application of partial mining by sublevel stoping by removing a small fraction of the ore. This technique results in forming an ore bed with good permeability and good solution collection at the stope base. The economic assessment of this approach suggests that it can be implemented with positive net present values to copper oxide ores located at depths in the 100–300 m range, with copper grades above 0.4%. The maximum acid consumption values are below 52.5 kg/t, with blasting procedures designed to produce an ore bed with an average particle size below 6″. The breakdown of operational costs indicates that the mining cost is still very high, accounting for up to 60% of the total operating costs. Therefore, optimizing mining procedures is still necessary for improving the economic outlook of this approach and thus expanding the application field of ISL.

Feb 4, 2023

By B. K. Saikia

A preliminary attempt has been made to study the particle size distribution (PSD) of minerals in one of the industrially important pulverized Indian coal sample using computer-controlled scanning electron microscopy (CCSEM). The results show that clay minerals, quartz, pyrite, and pyrrhotite form the bulk of the mineral matter. Minor minerals, such as calcite, dolomite, ankerite, barite, oxidized pyrrhotite, and gypsum are also observed in the coal sample. The PSD of the included minerals is generally observed to be finer than that of the excluded ones in the coal. Thus, the coal rich in included minerals has more small mineral particles, which may affect its reactivity. The proportion of included to excluded is found to be higher in major cases. Si is found to be mostly occurred as quartz and clay minerals, while Al mostly occurs as silicate minerals. Fe is primarily present as iron sulfides, iron oxide, and Fe-Al-silicate. S is partitioned into iron sulfides and gypsum. Most Ca occurs as carbonates and gypsum, with a minor fraction associated with clay minerals. Mg is found to be mainly present as dolomite and clay minerals, with a very minor fraction present as ankerite. The majority of alkali elements are associated with aluminosilicates. P is mostly associated with kaolinite and/or present as more complex compounds containing Al, Si, and other elements as apatite are found to be absent in the coal studied. Ti is mainly present as rutile and kaolinite. The geo-chemical association of the trace elements has also been discussed. Keywords: minerals, Assam coals, Indian coals, CCSEM study

Sep 1, 2012

By W. E. Wallace, V. Robinson, M. F. Keane, V. Vallyathan

"An in vitro study of the biologic responses of surface-modified and native silica and kaolin was made to provide comparative information on the supression of cytotoxicity by pulmonary surfactant. The release of alveolar macrophage cytoplasmic enzyme, lactate dehydrogenase (IDH), and lysosomal enzymes B-N-acetylglocosaminidase (B-NAG) and B-ghucuronidase (B-GLUC) and sheep blood-cell hemolysis were moni¬tored as indicators of cell membrane damage and cytutoxicity. Surface modification of silica and kaolin with dipalmitoyl lecithin (UPI) resulted in complete abrogation of cytotoxicity of both minerals. These findings indicate that surface modification of minerals with different adsorption properties by pulmonary surfactant generally lessens their prompt adverse effects.INTRODUCTIONAcute and chronic silicosis are well-characterized clinical and pathologic entities resulting from the inhalation of crystalline silica (Morgan and Seaton, 1984). Kaolin, a layered aluminosilicate clay frequently mined and used in manufacturing, contains tetrahedral silica alternately layered with alumina octahedra. Kaolin is relatively .inert biologically, and distinctly greater pulmonary burdens are seen in patients with kaolinosis than are seen in patients with silicosis. Crystalline siliea (quartz) induces a significantly greater degree of fibrosis in exposed animals in vivo than does kaolin (Hamilton and Hardy, 1974; Parkes, 1982; Hunter, 1976; Sheers, 1964; Warraki and t-lerant, 1963; Lynch and Mciver, 1954; Lapenas et al., 1984).This difference in pulmonary disease associated with the two types of dust is not reflected by in vitro cytotoxicity as Jetermined by pulmonary macrophage bioassays or erythrocyte hemolysis. Cytotoxicity studies using crystalline silica and kaolin of similar size fractions show comparable bioassay response on a mass basis. These cellular bioassays, therefore, do not correlate with the relative in vivo pathogenicity of silicates."

Jun 1, 1988