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By Kaixi Jiang, Chaozhen Zheng, Shuchen Qin, Hao Ma, Yufang Wang

The study investigates the behaviors of zinc and iron in neutralized residue during pressure and hot acid leaching. It examines the effects of temperature, acidity, leaching time, and oxygen partial pressure on zinc extraction. The results indicate that the acid to zinc mole ratio is crucial for the extraction process, with a zinc extraction rate reaching 98.0% under optimal conditions.

Feb 14, 2022

By M. Sadegh Safarzadeh, Erich U. Petersen, Jan D. Miller

"An acid bake-leach process has been identified and applied to an enargite concentrate containing ~67% enargite, ~27% pyrite (FeS2), ~3% chalcopyrite (CuFeS2), ~6% sphalerite (ZnS) and <1% galena (PbS). Sulfuric acid baking of this concentrate resulted in the transformation of the concentrate to S8, As2O3, HFe(SO4)2•4H2O, PbSO4 and Cu0.47Fe0.53SO4•H2O, all of which (except elemental sulfur and PbSO4) dissolved during the water leaching step. More than 87% Cu and 64% As were leached when the concentrate was baked at 200°C over 7 hours with a sulfuric acid-toconcentrate weight ratio of 1.6. Less than 1% As was lost to the gas phase. Upon water leaching, copper and arsenic were released to the solution at a concentration ratio of about 3:1. While enargite is very reactive during the sulfuric acid baking reaction, other minerals present in the concentrate such as pyrite, galena and sphalerite may compete to consume sulfuric acid and be converted into their corresponding sulfates at different concentrations. The purpose of this paper is to present our examination of the effects of sulfuric acid dosage on the extractions of Cu, Fe, and As from an enargite concentrate. In this regard, the concentrate, baked concentrate, and the leach residues are characterized and a conceptual process flowsheet is described for the acid bake-leach process for the treatment of enargite concentrates.IntroductionThe occurrence of enargite (Cu3AsS4) in copper ores and concentrates and the associated high arsenic values in such resources have resulted in a considerable decrease in the demand for such concentrates because they cannot be economically processed using conventional technologies such as smelting and atmospheric leaching (Mihajlovic et al., 2011). The exploitation of such problematic deposits through competitive treatment strategies will be required in the near future in order to satisfy increasing pressure from the copper market. It is expected that the average arsenic grade of copper concentrates will increase from 0.17% in 2008 to 0.22% by 2020 (Mayhew et al., 2011).The acid bake-leach process was identified and selected for further investigation at the University of Utah as a possible process alternative for the treatment of enargite concentrates. In this case, adequate amounts of concentrated sulfuric acid are mixed with the concentrate and heated to the temperature range 150-300°C. Subsequently, the baked material is leached with water/weak acid and the acid bake-leach process has some advantages over conventional sulfuric acid leaching (Prater et al., 1970). During water leaching, metal sulfates are released in solution, after which they can be extracted through well-known hydrometallurgical techniques. While the majority of the work has been done on oxide minerals, there is a limited record of sulfuric acid baking of sulfides."

Jan 1, 2015

By J. Frostiak

The Campbell gold operation of Placer Dome Inc. produces an arsenopyrite-sulphide concentrate which must be treated either by roasting, biooxidation or by pressure oxidation to obtain high gold recoveries. Pressure oxidation is a proven process and has the inherent advantage of meeting the stringent environmental regulations in the province of Ontario. A comparison of biooxidation and pressure oxidation was completed early in 1990 and the latter was selected by Placer Dome as the preferred process for replacement of the roasters. The commercial plant design was based on technology supplied by Sherritt Gordon and in July of 1991, the existing roaster operation was shut down and a new pressure oxidation plant was commissioned. The following summary describes the start up of the new facility and presents typical operating data.

Jan 1, 1992

By Atta Ur Rehman, Kwame Awuah-Offei

This work evaluated the effect of bucket orientation and operating parameters on resistive forces and penetration for rubber tire loaders. The work used a 1:16 scale LHD model to test a rubber tire loader (RTL) bucket operating at different levels of tractive effort, speed, digging height, and rake angles in a full factorial design experiment. The work repeated the test on two different muck piles with different particle sizes and used generalized regression modeling to test the association of rake angle, tractive effort, speed, and digging height on penetration and resistive forces for RTL buckets. The results show that speed and tractive effort are more important in explaining RTL penetration and resistive forces than height above the floor and rake angle. Speed, tractive effort, and height above the floor are positively correlated to bucket penetration, whereas the rake angle is negatively correlated to penetration. Similarly, speed, tractive effort, rake angle, and height above the floor are all positively correlated to resistive forces incurred during initial penetration. The observation that the combined effect of speed and tractive effort is negatively correlated to penetration and resistive forces is a novel contribution that enhances our understanding of RTL loading. The results also show that the effect of speed, tractive effort, and height above the floor all change with changes in particle sizes. This work adds to the literature on the effect of rake angle, height above the floor, tractive effort, and speed on penetration and resistive forces for rubber tire loaders.

Aug 24, 2020

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 Ashraf A. M. A. Wali

Many of the economic resources of Egypt have been recognized and exploited for thousands of years (e.g. gold and copper). Most of these minerals, particularly those from hard-rock sited deposits, are found in complex form along with other components while those present in sedimentary sequences are largely in simple compounds or as native elements. Recognition of their characteristic settings (structure, basin development, environment of formation etc.) is the main clue in predicting and locating their presence. The main economic minerals exploited in Egypt today come from sedimentary sequences and include sodium and potassium chlorides, gypsum, sulfur, and sedimentary iron ores. Large amounts of low grade sedimentary phosphates are known but are not of economic value at today&apos;s prices. Recent intensive investigation in the north-eastern Sinai (EI Arish) and along the southern coasts of the Gulf of Suez has revealed new and extensive sulfur and chloride deposits, and considerable oil and gas are now being exploited from closely related sediments. Tin is the only mineral that is produced from hard-rock sources, and gold and copper deposits are present but not of high enough grade to be economically viable. However, a significant part of Egypt has not yet been studied in enough detail to close the door on future discoveries. Another point of considerable geological interest is the presence of diverse, modern evaporitic settings, from which we may draw the analogs for many of the older gypsum, anhydrite, chloride and sulfur de-posits. In fact these analogs are so well displayed that both the Sinai and Gulf of Suez-Red Sea evaporites (Middle and Upper Miocene) can be readily compared with these modern deposits.

Jan 1, 1990

By J. E. Brownhill

This paper does not deal with the typical start-up issues of equipment, production capacity or work force. This is a description of the challenges faced and the changes made by the project team to bring to fruition the reconstruction of Port Inland. Many honored traditions and norms had to be overturned to find the winning combination that provided the productivity, flexibility and cost necessary to survive in today&apos;s competitive minerals environment. This paper covers the innovation in terms of machinery, operations, and management philosophy that permitted the renovation and reopening of Port Inland as a commercial limestone producer in the spring of 1992. Port Inland, constructed by Inland Steel in 1930, operated as a captive source of metallurgical grade limestone for the steel industry until its closure in 1989. Located in the Upper Peninsula of Michigan on the north edge of Lake Michigan, the operations consist of a deep water port facility with crushing, screening and stockpile storage for 500,000 tons of finished product at the port. Ninety-nine percent of the stone is shipped via lake boat to ports within the Great Lakes. The operation is unique in that both metallurgical Dolomite and Limestone are produced on site. In 1930, Port Inland was at the fore front of technological advancement. It was the first major mining operation to use roller bearings and other equipment innovations. Over the 60 years of operation, Inland Steel placed emphasis on steel making technology and iron ore mining at the detriment of the limestone operation. By the early 80&apos;s, Port Inland was no longer a leading competitor. Inland Steel, unable or unwilling to spend the capital to modernize, closed the facility in the fall of 1989.

Jan 1, 1994

By C. J. Webb

Abandoned uranium mines in the southern Black Hills of South Dakota were sampled for uranium, radium, and rare earth elements during 1992 and 1993. Analyses of water samples from several shallow ponds in the mine pits showed pH values between 3 and 4 with uranium concentrations between 1600 and 2600 ppb. Rare earth elements and their respective isotopes were analyzed with an inductively coupled plasma mass spectrometer and were referenced to a shale normalization pattern. All samples showed an enrichment in the middle rare earth elements. Rare earth levels often were greater than 0.2 ppm. At one site, the concentrations of lanthanides were 150,000 times above background levels. While the southern Black Hills have long been known for rich uranium ore deposits, these analyses show that significant levels of rare earth elements also are present, indicating that the potential exist for future development.

Jan 1, 1995

By F. Wolf, R. Ellmies

"Fluorspar is one of the most important industrial minerals. It has a wide range of applications, for example it is used in the steel and aluminum industry, and is also the raw material to produce hydrofluoric acid, Teflon or Gore-Tex. There are only a few major fluorspar mines worldwide, with China being the most important fluorspar producer (U.S. Geological Survey National Minerals Information Center, 2017). At Okorusu, Namibia, fluorspar has been mined with conventional open pit mining methods from 1955 until 2014 from a large scale metasomatic fluorspar deposit with seven identified orebodies. There are about 7 million tons of measured resources left with an average grade of 27.5 % CaF2. This paper is based at an MSc thesis at Technical University Freiberg and describes the design of an underground mine for the A and D orebodies with an annual production rate of 100,000 t acid-grade fluorspar product. By comparing different mining methods and adapting variants of access to the underground orebodies the paper will emphasize on the selection of a suitable mining technology, with a special focus on the economic considerations to decide about the most profitable operation. INTRODUCTION Mining holds an important part in the economy of Namibia. In 2016 11.1 % of the GDP was made through mining activities with 22 active mines (The Chamber of Mines of Namibia, 2016). Only one of them consists an underground mining operation. The global annual production of fluorspar is approximately 6 to 7 million t (U.S. Geological Survey National Minerals Information Center, 2017). Okorusu produced on average about 50.000 t annually in recent years (U.S. Geological Survey National Minerals In-formation Center, 2015). Okorusu Mine is Namibia’s only fluorspar mine. Fluorspar was mined in an open pit mine with four individual pits (A-D) since 1980. In 2014 the mine closed due to the increased stripping ratio and beneficiation problems. The mine assets were bought by Gecko Namibia. Currently Gecko uses parts of the processing plant for beneficiation of graphite from a neighboring mine. Figure 1 shows a panoramic view with the four pits and the mine village. The intent is to develop a concept for the further underground development of the mine. There are still about 7 million t of measured resources left in the deposit, with an average grade of 27.5 % CaF2. This study focusses on the underground mine design. The above-ground plant and facilities are considered as remaining unchanged."

Jan 1, 2018

By James Giulianelli

Personnel at the Jet Propulsion Laboratory (JPL) are studying the technology and applications of salt-gradient solar ponds (see below) for both electrical and thermal energy generation. The brine extraction and processing site operated by the Kerr-McGee Corporation at Searles Lake, California, offers ideal conditions for economic construction of solar ponds. Furthermore, since rising conventional energy costs adversely affect the economic recovery of brine by the present process, this site was selected for a study on the feasibility of integrating the solution mining of trona (Na2CO3?NaHCO3?2H20) in the lower salt with solar ponds for heating. The major emphasis of this study was to determine whether inexpensive thermal energy available at the brine extraction site would be useful in extracting increased mineral value from the resource. The present operation, which involves the simple extraction of the complex brine and its processing at the adjacent plant, is sometimes referred to as solution mining. Since the concept discussed in this paper involves injecting a heated sodium sulfate brine to dissolve carbonate underground, the proposed scheme is referred to as "enhanced" solution mining. The subject is discussed in greater detail in a recent JPL report. (1)

Jan 1, 1981

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 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 G. R. Hart

The expected 1990 Clean Air legislation is providing electric utilities with a series of challenges and decisions as the utilities prepare strategies to comply with the resulting regulations. This paper addresses the strategy development of a coal-based utility --the legislation, the process used, the fuel issues, the options available, and the decisions to be made.

Jan 1, 1991

By Brad Simser

Several case histories from Glencore’s Sudbury Operations show how passive seismic monitoring data is used for geotechnical decision making. The data comes from three different seismic arrays monitoring two open stoping deposits, and a narrow vein cut and fill/blasthole operation. Mining depths range between 1000 to 1680m below surface. The deposits are hosted in hard igneous rocks typical of the Sudbury basin, with characteristically high horizontal stress (approximately 1.8 times the depth of overburden). Rockbursting is the main geotechnical risk, due to the strong brittle nature of the rock and local high mining extraction. Fault related seismicity includes both fault slip events, and the stress channelling effect as the mining front approaches a major fault structure. Planar data trends generally line up with known faults and often indicate early stage fault activation. The structures are risk ranked based on their seismic response. This has been particularly useful at the Nickel Rim South Mine (NRS) where the structural fabric (jointing and small-scale faulting) is generally parallel to the more through going faults. The persistence of structures is difficult to measure, and the NRS faults generally have low offsets and thin gouge. The visual difference between the more persistent structures that occasionally generate large seismic events (up Mw 2.9 to date) and localised joints/slips is often minor. The seismic monitoring data clearly shows the more active structures. This information is highlighted on mine plans to help guide enhanced ground support and seismic re-entry protocol barricade locations. Pillar loading/yielding is a key element to the blasthole operations where a primary/secondary mining sequence is used. The secondary pillars are mined in a yielded state with just-in-time development. An example of the seismic signature of a secondary stope is shown with emphasis on the need for high location accuracy given the stope widths of 12.5 to 15m. The ratio of the shear wave energy to primary wave energy (Es/Ep) has long been used as a method to estimate source mechanisms; the higher the ratio, the more likely the event is fault slip versus rock fracturing. Data sets are filtered on Es/Ep ratios to highlight both fault slip populations and stress fracturing mechanisms. Examples of seismic data quality checks, high stress development, and re-entry protocols are also shown in the case histories.

Apr 26, 2022

By J. Z. Keating

There are close to two million tons of Industrial Minerals processed and sold in North America wherein the processor/marketer has no affiliation with the source mine. The largest quantity, about 800,000 tons, is barium sulfate, which is sourced in lump ore form mainly from China and India. The Alumina Trihydrate Industry sources several hundred thousand tons from various alumina refineries. Substantial quantities of bauxite, zircon, magnesite, and fluorspar arrive in North American ports each month. There are also rapidly growing quantities of offshore talcs and calcium carbonate ores being processed in U.S. plants. These feedstocks are usually quite pure, have unique properties, and enjoy bulk rail or waterborne freight economies that allow successful competition with locally sourced raw materials. With increasing restrictions on mining activities, and the increasing need for sophisticated functional minerals, the importation of minerals will continue to grow.

Jan 1, 1994

By Ramon B. Santos

The Atlas Concentrator, reputedly the largest in the Far East today, is located on the island of Cebu in the Republic of the Philippines. It started operation on a 4000 TPD capacity in 1955. An expansion program, coupled with significant improvements both in the Crushing Plant and the Mil, made the Atlas Concentrator what it is today, treating about 14,000 tons of ore per day at a comparatively low cost of about $0.50 per ton treated. The Atlas Copper Mine is at present mainly an open pit operation, with ore supplied from two pits (Lutopan and Biga) north of the Concen¬trator. Development of an Underground Mine, situated on the main ore body at Lutopan, which will be a block caving operation, has been underway since 1963, and this underground mining operation is expected to b e in full production by the latter part of 1966.

Jan 1, 1966

By Ted H. Eyde

Both private industry and the Interior Department have become alarmed about the enormous amount of Federal land that has been withdrawn from appropriation either under the Mineral Leasing Laws or the Mining Law of 1872. According to a recent article by Gary Benethum and L. Courtland Lee, governmental actions have withdrawn nearly 400 million acres from the operation of the Mining Law of 1872 and over 500 million acres from the Leasing Laws. An addition al 100 million acres for the Mining Law of 1872 and 70 million acres for the Leasing Laws are either encumbered or being managed in such a way as to constitute a defacto withdrawal from mineral development. This means simply that mineral exploration end development under the Mining Law of 1872 is either prevented or discouraged in an area the size of the states of California, Arizona, Washington, Oregon, Nevada, Utah, Idaho, and one half of Colorado combined. Under the Mineral Leasing Laws, exploration and development is either prevented or discouraged in an area equal in size to all the states east the Mississippi River, except Maine.

Jan 1, 1976

By K. A. Natarajan, M. R. Sabari Prakasan

"Biodegradation of sodium isopropyl xanthate using two types of bacterial strains, Paenibacillus polymyxa and Pseudomonas putida, is demonstrated. At concentrations higher than 50 mg/L, the presence of xanthate in the growth medium resulted in bacterial toxicity, retarding growth kinetics. Adaptation through serial subculturing in the presence of higher xanthate concentrations resulted in the development of xanthate-tolerant bacterial strains. Stress proteins secreted by bacterial cells grown in the presence of xanthate were isolated. Bacterial cells could utilize xanthate as a growth substrate, degrading xanthate species in the process. Acidic metabolic products generated by bacterial metabolism promoted efficient xanthate decomposition. Probable mechanisms for the biodegradation of isopropyl xanthate are illustrated.IntroductionDifferent types of alkyl xanthates (ethyl, isopropyl, amyl, etc.) have been used as flotation collectors in the concentration of sulfidic ores for several decades. Large quantities of waste water and xanthate-containing effluents are generated by ore flotation processes, posing considerable environmental challenges. Billions of cubic meters of such process waste waters are produced annually across the world, most of which are discharged to the environment, often without any treatment. Leakages and accidental release of xanthate reagents from manufacturing plants and during transportation and storage can also contaminate the environment. Residual concentrations of xanthate reagents are encountered in waste effluent, which are found to be toxic to aquatic life and unfit for human consumption (Harris, 1984; Okibe and Johnson, 2002). Further, direct recycling of such waste waters for plant operations can compromise water quality standards required for process operations. The presence of residual xanthate in recycled waters from flotation plants deleteriously influences flotation processes. Xanthate can be easily decomposed at low pH values; however, CS2, which is more toxic, will be produced by the acidification of neutral and mildly alkaline xanthate-containing solutions. Physico-chemical methods such as flocculation, chemical oxidation and decomposition and physical adsorption used to remove residual collector reagents from mill process waters are often expensive and not environment-friendly (Oliveira and Rubio, 2009; Cheng et al., 2012; Molina et al., 2013,)."

Jan 1, 2015

By Martha Gross, Amanda Wachenfeld, Brian Keaney, Jean-Michel Charpentier, Frank Perrone

The Hampton Roads Bridge-Tunnel (HRBT) Expansion widens the existing four-lane bridgetunnel corridor to eight lanes through construction of two parallel tunnels, interstate widening, and bridge expansions. As part of the design-build contract, a supplemental geotechnical investigation was completed to support the design. The investigation for the subaqueous tunnel segment consisted of over 48,400 linear feet of drilling and 7,100 laboratory tests. This paper discusses the challenges of planning and executing a large-scale geotechnical investigation for underground works in a marine environment and the use of big data for effectively managing, interpreting, and transmitting data to the design-builder consistently throughout the investigation.

Jun 23, 2024

By Rudolph K. Hoagberg

Silica sands, primarily in coarse size ranges, are used to prop open fissures or voids created in the bedrock by hydraulic fracturing. This procedure increases the flow of gas or oil or other fluids through the bedrock. The sands used must meet various specifications relating to their physical and chemical characteristics; these characteristics are in turn related to the geologic provenance of the sand deposit. The Jordan Sandstone, a Cambrian formation which is exposed in Minnesota and Wisconsin, meets the specifications of a proppant sand by virtue of its depositional history and its sedimentary properties.

Jan 1, 1980