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By K. Peri

The leaching behavior of gold in ammonical solutions with iodine as an oxidant has been investigated using cyclic voltammogram and Tafel polarization. The majority of experiments was carried out at 75°C and the results were compared with the equilibrium consideration on the iodine-ammonia system. The distribution of nine iodide containing species at various pH values in the absence and presence of ammonia was considered at three different temperatures. It was found that by introduction of ammonia into the system, the concentration of iodide (r), iodine (12) and triiodide (13') is increased substantially which in turn helps the rate of dissolution of gold. The apparent activation energy was found to be about 46 kJ/mole, indicating a chemical controlled mechanism.

Jan 1, 1999

By F. E. Senftle

Preliminary geophysical surveys for nickel deposits are usually carried out by airborne magnetometer and surface electrical methods. Once an anomaly is discovered by these techniques, one must resort to chemistry to identify nickel and determine its concentration. Consequently, a method to determine nickel quickly and quantitatively at the exploration site could help guide detailed sampling and provide analytical data that might otherwise be delayed at distant laboratories. In addition, borehole probes capable of indicating nickel in the rock adjacent to the hole, should prove attractive to the exploration geologist. With these needs in mind, preliminary investigations have been made to demonstrate an in situ analytical technique which appears feasible for nickel exploration. The method depends on the very high energy gamma rays emitted when nickel absorbs a thermal or low energy neutron. These neutron capture gamma rays should be distinguished from the lower energy gamma rays emitted during decay of radioactive nuclides as in conventional activation analysis.

Jan 1, 1971

By O. D. Staman

The risk assessment project examines the likelihood of inorganic contaminants from copper dump-leaching operations to contaminate domestic water supplies. The project examines contaminant transport by modeling contaminant movement from the base of a leach pile through the unsaturated zone and into the saturated zone. The modeling effort is unique in that it models infiltration, contaminant transport in the unsaturated and saturated zone combined with geochemical modeling of the unsaturated zone. The project incorporates probability theory to reflect the uncertainty of hydrogeologic parameters.

Jan 1, 1994

By R. M. Parlman

Interest is increasing in obtaining incremental improvements in mineral recoveries in flotation processes because of changing world economic conditions. Research on collector reagents, long indispensable components in flotation systems may provide the cheapest and simplest route to higher metal recoveries. Sulfhydryl group - containing compounds (-SH) and their salts, e.g., dithiophosphates, xanthates and a few other derivatives are commonly used to promote the flotation of sulfide minerals. Alkyl mercaptans, another class of sulfhydryl compounds, have long been known to have collecting properties but have been relegated to dormancy for one reason or another. This paper reports results from new investigations of alkyl mercaptans, trithiocarbonates, and a petroleum oil with a variety of western domestic and Canadian ores for copper and molybdenum sulfides recovery. Specific opportunities are pointed out to the industry for mineral recovery enhancement through the use of the proper reagent combination.

Jan 1, 1980

By A. Halim, A. Martikainen, S. GYAMFI

This paper outlines a unique case of the development of strategies to reduce ventilation and heating costs in Konsuln iron ore mine in northern Sweden. The mine, located just south of Luossavaara-Kiirunavaara Aktiebolag’s Kiruna iron ore mine, was developed as a test mine from 2018-2020 for the Sustainable Underground Mining (SUM) project. Besides functioning as a test mine, Konsuln also contributes to ore production. The existing mine ventilation system was designed for the current production rate of 0.8 million tons per annum (Mtpa). There is a plan to increase this rate to between 1.8 and 2.0 Mtpa.

Sep 30, 2021

By Nikhil Dhawan, Amit Barnwal

The present study reports a processing route to recover metals from integrated circuits of discarded random access memory (RAM) units containing ~ 66% printed circuit boards and ~ 33% integrated circuits. The integrated circuits are manually separated, grounded, classified, and subjected to water fluidization for the effective separation of metals. The significant separation was achieved via water fluidization, and the underflow fraction was magnetically separated. The magnetic fraction was thermally exposed in a muffle furnace, and the process optimization was carried out using a Box-Behnken statistical design. The detailed characterization at subsequent steps significantly aids the understanding of metal-plastic separation and enrichment. A concentrate containing 97% metals (Fe-59%, Ni-9.5%, Cu-7.7%, Sn-13.4%, Pb-5.6%, Ag-1.6%) with 96 wt% recovery can be recovered from discarded IC units. The process pursued is simple, adaptable, and environment-friendly, and the product can be used in conventional smelters.

Jun 23, 2020

By A. Thatcher, C. Day, C. Meyer

The purpose of this paper is to provide general information about the bioaccessibility of metals and specific information about the use of bioaccessibility in risk assessments (human health risk assessments [HHRA] or ecological risk assessments [ERA]) and a list of sites where regulatory agencies have approved the use of bioaccessibility data in risk assessment. The memorandum also cites current U.S. Environmental Protection Agency (USEPA) guidance as well as state specific guidance where applicable. BRIEF HISTORY OF METAL BIOACCESSIBILITY TESTING AND METHODS The bioaccessible fraction of a constituent is that fraction that dissolves or desorbs from its matrix (e.g., soil) in the gastrointestinal tract and is available for absorption (USEPA 2007a; ITRC 2011; ITRC 2017). This is different from the bioavailable fraction, which is the percentage of the amount of an element that an organism is exposed to that is absorbed by that organism during a given time under defined conditions (USEPA 2007a). The bioaccessibility factor is the percentage of a metal that is potentially available for absorption and, therefore, is a conservative estimate of the bioavailable fraction since all that is available for absorption may not ultimately be absorbed into the organism’s system. Currently, there are two main techniques for estimating bioavailability of metals within a medium: in vivo animal studies (time-consuming and often cost-prohibitive), and in vitro tests that simulate human, or animal digestion in a laboratory setting. In vitro and in vivo test methods and protocols have been extensively evaluated by numerous researchers (Ruby et al. 1996; Rodriguez and Basta 1999; Sips et al. 1998; Sips et al. 2001; Molly et al 1993; Oomen et al 2002; Kelley et al. 2002; Oomen et al. 2003; Furman et al. 2006; Drexler and Brattin 2007; Basta et al. 2007; Wragg et al. 2009; Wragg et al. 2011; Chaney et al. 2011; Bradham et al. 2015; Bradham et al. 2018). The most recent scientific literature demonstrates that protocols used to estimate the bioavailability of metals to mammals also predict bioavailability of metals to birds as well (Beyer et al., 2016).

Jan 1, 2019

By Y. C. Guan

The leaching kinetics of chalcopyrite in ammonium iodide solutions with iodine has been studied using rotating disc. The variables studied J include the concentrations of lixiviants, rotation speed, pH of the solution, reaction temperature, and reaction product layer. The leaching rate was found to be independent with the disc rotating speed. The apparent activation energy was measured to be about 50 kJ/mole from 15°C to 35°C, and 30.3 kJ/mole from 35°C to 60°C. Experimental findings were described by a kinetic model, and the overall rate was found to be: (formula)

Jan 1, 1997

By A. Anani

The goal of hot mix asphalt (HMA) design is optimal material blending to meet Superpave specifications. HMA cost minimization has being modeled as linear programing (LP) (Awuah-Offei et al 2011) and mixed integer LP problems (Brown et al, 2012) and solved with commercial software such as LINDO and CPLEX. Often these software, which are designed to solve general optimization problems, have licenses that cost thousands of dollars. The objective of this study is to develop a novel solution algorithm to the HMA optimization problem presented by Brown et al. (2012), which will negate the need for expensive commercial packages and is specific to this problem. This novel algorithm is based on the branch and bound algorithm for solving mixed integer problems. The algorithm is incorporated into a software package with an easy-to-use graphical user interface. The developed algorithm is validated using a real-life HMA problem. Using this solution algorithm will save companies thousands of dollars, otherwise used to purchase software licenses.

Feb 23, 2014

By H. Marshall Farrier

In the past few years the world petroleum industry has increasingly felt the weight of changes in the principal economic factors affecting pro¬fits. As a result of, these changes, it has been necessary for many oil companies to acquire certain new facilities in order to strengthen their competitive positions and thereby protect their tremendous investments in crude oil reserves, pipe line facilities, refining operations, and marketing outlets. Principally these needs have been met by new capital outlays. A supplementary, method of acquiring needed facilities, however, has been to obtain existing facilities through complete or partial acquisition of other companies.' properties. It is this method of meeting competitive pressures with which this paper is concerned. This paper presents a statistical breakdown of the mergers and acquisitions which occurred in the oil industry between January 1, 1954, and October 1, 1959, showing the frequency' with which certain types of properties were acquired in each of the years studied. In addition, it discusses the principal economic conditions which stimulated many of these property trans¬fers, comments on the effects of these mergers on the consuming public, and indicates the types of, mergers and the rate at which they may be expected during the next three or four years. The basic data upon which the statistical analysis presented in this paper is based were taken from several published sources. Obviously they are somewhat incomplete because not all mergers and acquisitions were reported However;, a careful search was conducted through, The Wall Street, Journal, The Oil and Gas Journal, Potroleum Week, and The Oil Daily with the result that the data should be reasonably complete and comparable for each of the years studied, It is believed, therefore, that the statistical analysis which' follows provides a reasonably accurate indication of the general trend in mergers and acquisitions during the period studied.

Jan 1, 1960

By U. B. Kodukula

The iron ore beneficiation plant at Serra-Azul Mines of ArcelorMittal, Brazil operates at a rated capacity of 3.2 million tons per year. The ore is concentrated using magnetic separation, jigging, hydrocyclones and spiral concentrators. The tailings from the process plant are generated from classifier overflow of 135 tons per hour dry solids and thickener underflow of 48 tons per hour dry solids. A systematic experimental program was carried out using Multi-gravity separator (MGS), and wet high-intensity magnetic separator (WHIMS) for recovering the iron values from both of the tailing streams while minimizing the total quantity of tailings to be discarded. The classifier overflow contained 32.3 percent iron, 49.9 percent silica and 2.18 percent alumina and was 45 percent finer than 45 microns in size. The thickener underflow sample contained 47.3 percent iron, 27.6 percent silica and 2.49 percent alumina and was 16 percent finer than 45 microns in size. Separation results on the classifier overflow sample with the MGS indicated that a concentrate containing 62.1 percent of iron, 10.8 percent silica and 0.36 percent alumina can be achieved with a weight recovery of 24.5 percent. The results with WHIMS at 6500 Gauss indicated that concentrate containing 62.6 percent iron, 8.3 percent silica, and 0.65 percent alumina can be achieved at a weight recovery of 34.7 percent. 4.7 percent. WHIMS studies at 6500 Gauss on thickener underflow sample indicated that a concentrate containing 61.4 percent iron, 8.8 percent silica, and 1.74 percent alumina can be achieved at a weight recovery of 57.2 percent. Based on these results, and further in-house test works, a WHIMS installation was adopted for the recovery of iron values from the tailings in the operating plant at ArcelorMittal Serra Azul Mines, Brazil.

Feb 23, 2014

By Xiaoyan Luo, Congcong Dai, Gaipin Cai, Xin Liu, Lu Zong

To overcome the difficulty of accurately judging the load state of a wet ball mill during the grinding process, a method of mill load identification based on the singular value entropy of the modified ensemble empirical mode decomposition (MEEMD) and a probabilistic neural network (PNN) classifier is proposed. First, the MEEMD algorithm is used to decompose the vibration signals recorded under different load states to obtain the intrinsic mode components, and a correlation coefficient threshold is used to select the sensitive mode components that characterize the state of the original signal. Second, singular value decomposition is used to obtain the singular value entropy. Finally, the load state of the wet ball mill is judged based on the magnitude of the singular value entropy. A characteristic mill load vector is constructed from the singular value entropies of the cylinder vibration signals recorded under different load conditions and is used as the input to a PNN, which then outputs the predicted ball mill load state; in this way, a load state identification model is established. Grinding experiments are presented to verify the effectiveness of the proposed method, showing that the method can accurately identify the load state of a wet ball mill. ()

By R. J. Bridwell

Acid mine drainage (AMD) occurs in high sulfur coal and heavy metal mining environments. We show remediation methods using 3D numerical ground water flow models and chemical kinetics of pyrite oxidation for acid leaching of pyrite during air and ground water flow. A recently developed numerical model couples air and water flow with kinetics of iron-reactive bacteria, oxygen transport, specific chemical reaction rates, and pyrite oxidation to calculate migration control of pollution. A model is presented which considers diminution of acid mine drainage in pyrite rich ore bodies by raising the potentiometric surface through a vadose zone to reduce acid mine drainage. A ground water model is presented of an initially saturated mountain, containing an adit, with a sloping ground water table. Ground water recharge consists of snowfall and normal precipitation. Simulations indicate that the historically open adit creates a desaturated mountain above the adit. Significant air saturation ranging from 10-90% oxygen can occur to depths of the adit (-270 m). Remediation consists of plugging the adit, which fill s adit and mountain with water from recharge. Plugging the adit required <10 years for resaturation and rise of the water table in the mountain.

Jan 1, 1994

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By Saurabh Kundu, Shakuntala Tudu, Indrajit Paul, Chandra Sekhar, Manikanta Nallamilli, Shaik Mahaboob Basha, Neha Gupta, Srinivas Dwarapudi, Dhiraj Madhukar Kadhe

Iron ore pelletizing using compressive and shear action on wet mixture feed has been studied. The physical properties, namely, moisture content, drop strength, green compressive strength (GCS), dry compressive strength (DCS), porosity, and cold crushing strength (CCS), have been studied. Pelletizing tests were carried out on four different types of ore, namely, hematite ore, magnetite ore, goethite ore, and sinter return fines. The inference of shear forces on silica distribution index in dry pellet has been studied using optical and scanning electron microscopy. Significant improvement in physical strength was observed due to compressive and shear forces on the pellet mixture feed. However, decrease in moisture content and ball porosity has been observed. Silica distribution index improved by 1.72 times for hematite ore, 1.47 times for magnetite ore, and 1.68 times for goethite ore. It has been found that bubble cavity has been reduced which is good indicator in terms of physical properties.

Jan 29, 2022

By Langtry E. Lynd

The titanium dioxide pigment industry in the United States has always relied to varying degrees on imported titanium concentrates. Dependence on foreign ilmenite was especially high (generally over 85% of consumption) until 1942, when large-scale U.S. production of ilmenite began, and has since ranged from 12% to 47%. Rutile import reliance was generally in the 45% to 80% range until the early 1960&apos;s, when increased use in the chloride pigment process raised dependence on imported rutile to over 90% in most years since 1963. Import reliance of zircon, obtained almost entirely as a byproduct of titanium mineral production, has generally ranged from about 30% to 65% of consumption. This paper will examine the history of U.S. sources of these heavy mineral commodities, and will discuss the potential U.S. future supply in view of changing industrial uses and processes and the anticipated development of new heavy-mineral-sand processing operations, such as those at Richards Bay in the Republic of South Africa and in Sierra Leone.

Jan 1, 1978

By Matthew S. Sanchez, Richard J. Lee, Matthew D. Zock, Drew R. Van Orden

"Current Environmental Protection Agency (EPA) risk models and asbestos fiber counting techniques for monitoring airborne exposures treat all fibers as being equivalent and ignore the effect of dimension on toxicity. While this may have been appropriate when modern analytical methods were not available, the measurement world is now fully capable of making the appropriate distinctions. The importance of width as a determinant of carcinogenicity has been recognized for nearly 30 years within the published literature. Stanton,1 in a landmark study of a suite of fibrous materials, found that durable mineral fibers with widths less than 0.25 mm and lengths longer than 8 mm were causally associated with the induction of tumors. Pott,2 in a later study, postulated a fiber toxicity model that agreed reasonably well with the Stanton findings, but extended the concept to include varying toxicity as a function of length and width. Wylie et al.3 reanalyzed samples used by Davis et al.4 and found that tumor generation was strongly and inversely correlated with fiber width. Crump5 testified increasing fiber length was correlated with disease occurrence. Lippman6 reviewed a number of studies and suggested that mesothelioma was closely associated with long, thin fibers. Berman et al.7 published a risk model, which found that disease was correlated almost exclusively with fibers longer than 40 mm and width less than 0.25 mm. Recently, Loomis et al.8 reanalyzed textile mill samples and found that aspect ratios greater than 40:1 were highly correlated with disease. Incorporation of width into risk models has been limited by the availability of data from operating asbestos plants and, in particular, the observation of an asbestos plant for which there is no observable mesothelioma. There have been only limited studies published on the dimensions of asbestos fibers, with a few serving as the primary references in other literature.9_13 A rare opportunity to collect detailed concentration and dimensional data of airborne crocidolite from an operating asbestos-cement plant using modern analytical procedures arose, providing a chance to supplement the existing literature on airborne fiber dimensions. The asbestos-cement plant is located in the eastern end of Cochabamba, Bolivia along Highway 4. Cochabamba is a relatively large city located in the Andes Mountains, approximately 250 km southeast of the capital La Paz. The city sits in a valley that runs east-west with mountains to the north and south. The crocidolite used in the products made at this facility is mined in central Bolivia, approximately 75 km northwest of Santa Cruz. The crocidolite is a fibrous magnesioriebeckite 14 (blue asbestos). Crocidolite fibers from Bolivia were the subject of prior reports suggesting the fibers are generally longer and thicker than crocidolite from Australia or South Africa.9 At the cement plant, the run-of-mine crocidolite was first pulverized using a hammer mill and then sieved on vibratory sieves to produce fibers of limited size ranges for use in the cement. The sieved crocidolite is mixed with other components, including recycled cement product, to produce a slurry that is vacuum filtered into sheet form. The sheets are then manually molded into a corrugated shape, air dried, and sawed (using circular saws) to accepted dimensions. The sawed sheets are cured in soaking pits for 28 days before being shipped to the consumer. Prior to shipping, the sheets are finished by a light hand sanding followed (at customer request) by applying one or more coats of paint. A detailed description of the cement plant and the industrial hygiene results can be found in Van Orden et al.15"

Jan 1, 2012

By S. M. Bulatovic

The western industrial world has to rely more and more on complex polymetallic sulphide ores as sources for base metals. These ores are composed of fine grained sulphide minerals such as chalcopyrite, galena, sphalerite, pyrite, pyrrhotite and marcasite. The liberation sizes of the individual minerals can range between 30 um and 5 um. Therefore, applying conventional techniques to recover these finely disseminated minerals usually results in unsatisfactory metallurgical performances with high losses of the valuable mineral to the slime , fraction of the tailing. New concepts for treating these polymetallic complex ores are discussed in this paper. Beneficiation techniques utilizing new reagents and a new approach to pulp preparation are described. Some of these techniques were applied to ores from existing concentrators as well as to new ores. The results of these studies are discussed in the following sections.

Jan 1, 1990

By A. Martikainen, H. Dougherty

"At the Kemi Mine, a recent expansion into the Surmaoja orebody required an increase in ventilation capacity. A new ventilation shaft was built with two main fans. The installation is near the entrance gate and only 1.7 kilometres from the nearest permanent dwelling. The main fans were first taken into use as exhaust fans in October 2014. Shortly after the fan installation, comments concerning fan noise were received from the neighbours. The first noise measurements were taken at the main fan installation site by Outokumpu personnel in March 2015. Due to higher than expected recorded values, during late June, 2015, a two-week environmental noise study was planned by the engineers and executed by a consultant specialized in noise measurement. The measurement results were analysed and compared to the requirements of the environmental permit and Outokumpu’s factory standards. While the measured values at the nearest dwelling were within the environmental permit limits, high noise values were recorded at the fan station. A second two-week study will be performed after construction of the main-fan heating station has been completed. Actions taken will depend on the outcome. INTRODUCTION The Kemi Mine is a part of the Outokumpu chain of integrated ferrochrome and stainless steel manufacturing in the Kemi-Tornio region in Finland. The mine itself is a large underground operation with a production capacity of 2.7 million tons of ore per annum. It is also the European Union’s only chrome mine, and at present (2015) the mine extracts 2.4 million tons of chrome ore per year. Safety, cost-effectiveness, and environmental friendliness are hallmarks of the Kemi Mine. Environmental impact produced by the operation of the mine is limited due to the insolubility of the oxide chromium ore, the gravity-based and chemical-free enriching process as well as the closed circulation system of the process water which serves both the whole mine and the enrichment process (Outokumpu, 2015). Importance of the environmental impact of the Kemi Mine is amplified by its closeness to the cities of Kemi and Keminmaa with the nearest habitants living less than 2 km away from the mine site. To show the cooperation with residents the Kemi mine organizes special “neighbour days” for the habitants of the areas closest to the mine. Also, information letters are sent to the neighbours, when changes that may affect the neighbours are being planned and executed."

Jan 1, 2016

By C. D. Elifrits

The required reclamation of land disturbed by surface coal mining often results in the creation of some over steepened slopes which are prone to rapid erosion and sediment production. This natural activity on such slopes is not desirable nor allowed under current regulations. Experience has indicated that novel approaches must be devised to address the problem. Research conducted on field sites in Missouri has indicated that construction, during the reclamation and grading processes, of a man-made drainage system will control the erosion. The drainage system must replicate or exceed the natural system in terms of drainage density and channel frequency. Basic design considerations will be summarized in this paper and field results shown.

Jan 1, 1986