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By QUANWEN PU, Yonggang Wei, Bo Li

The spent catalyst is one of solid waste resources, which contains precious metals with considerable recovery value. However, due to the different compositions of catalyst, the recovery process is difficult. Most of the catalysts are supported by alumina which has good alkali-soluble properties, while platinum is insoluble in alkali. Platinum is enriched by pressurized alkaline solution which is a kind of hydrometallurgical process. The novelty of this study is the separation of alumina and platinum from the spent catalyst and the enrichment of platinum in the solid phase. In this study, a leaching process using NaOH as leaching agent under high temperature and pressure was employed. The effects of alkali concentration, leaching temperature, leaching time, and liquid–solid ratio on leaching efficiency were investigated. The optimum process conditions were determined as follows: alkali concentration of 240 g/L, temperature of 200℃, pressure of 1.20 MPa, time of 1 h, liquid–solid ratio of 5:1. It was concluded that the leaching rate of alumina can reach 99.69%. The content of platinum increased from 0.1749 to 21.12%, the loss of platinum was 3.39%, and the enrichment ratio of platinum increased by 120.82 times. The leaching kinetics of alumina was studied based on the shrinkage core model. The activation energy of alumina leaching is 19.53 kJ/mol, and the leaching process is controlled by chemical reaction. Pressurized alkali solution can not only efficiently leachate alumina from the spent catalyst and enrich platinum, but also reduce the reaction time and increase reaction rate.

Feb 11, 2022

By A. K. Snelgrove

At a time when water resource planning is proceeding on a continental scale, such as the proposed $100 billion North American Water and Power Alliance, which would redistribute water among three nations, including seven provinces of Canada, 35 of the United States, and three States of Mexico, the selection of a single river basin for study may seem to require an apologia. None is offered because of ( 1) the magnitude of the Indus , itself a part of the great Indo-Gangetic Plain drainage system, with Himalayan sources, upon which the thickly populated northern sub-continent of Indo-Pakistan depends for agriculture and hydroelectic power; (2) the extraordinary problems created by dismemberment of the world?s largest irrigation system through legal beheading of the Eastern Waters under the Indus Waters Treaty of 1960; and (3) the herculean effort to contain the twin encroachments of waterlogging and salinization in a basin which faces a shortage of fresh water. The British irrigation system of barrages and canals on the Indus was a venture admirable in conception. Unfortunately, it is now a legacy burdened with unwanted consequences, due to interference with the hydrological regimen, particularly the rise of water table occasioned by leakage.

Jan 1, 1967

By Marcelo de Oliveira, Antoine Allanore, Dennis P. Chen, Davide Ciceri

Potassium fertilizers (potash) are mined in a handful of countries in the Northern Hemisphere. Potash is either expensive or unavailable to the farmers of the Southern Hemisphere. Alkaline alteration of K-feldspar rock (ultrapotassic syenite) in autoclave in the presence of Ca2+ generates a mixture of K-bearing calcium-aluminum-silicate-hydrate (C-A-S-H) minerals that potentially can be used as an alternative local fertilizer. This work investigates the effect of processing temperature (200 °C, 220 °C, and 230 °C) and time (from 0.5 to 3.0 h) on pH, mineralogy, and elemental availability of the C-A-S-H mineral mixture. Increasing temperature results in an increased conversion of K-feldspar and increased content of both the mineral tobermorite (Ca5Si6O16(OH)2·4H2O) and amorphous phase in the resulting C-A-S-H mixture; increasing time results in an increased conversion of α-dicalcium silicate hydrate into tobermorite. The amount of K leached from the mixture is relatively constant across all processing conditions. Hydrothermal alteration in autoclave of K-feldspar-bearing rocks such as ultrapotassic syenite permits the synthesis of a potential potassium fertilizer which alkalinity and mineralogy can be tailored according to soil requirements.

May 22, 2020

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 H. Sevim

In this paper, the research effort in simulating the operation of underground coarse-coal hydrotransport systems (UCCHS) is summarized. The equipment of the system to be simulated is already optimally selected by using an analytical optimization model. The purpose of the simulation model is to test the performance of the system and to obtain the distribution of the operating parameters such as water and power consumption, amount of slurry delivered to the preparation plant, etc. Knowledge of the distribution of these parameters is essential for the efficiency of the design and the operation of the system.

Jan 1, 1985

By T. R. Kostecki, A. J. S. Spearing, A. Hyett, M. Gadde

Ground control research for underground coal mining has progressed significantly over the past several decades. With this progression, and the ability to analyze and model underground conditions, underground working conditions have significantly improved. In order to progress further, the behavior of roof support must be known and be adequately modeled, such that models can be used for support design under different geological and mining conditions. This paper discusses the results from a research project funded by the U.S. National Institute for Occupational Safety and Health (NIOSH) and undertaken by Southern Illinois University Carbondale and Peabody Energy. The research involved installation of active and passive instrumented bolts in mines, recording relevant in situ data and then attempting to model the behavior of the bolts as mining progressed. Such calibrated models could aid in design of roof supports under different geological and mining layouts and thus, hopefully, further improve rock related safety.

Jan 1, 2012

By M. Westerstrand

The processes involved in the concentration of magnetite ore with process water as the aqueous medium can have a strong influence on the surface properties of the magnetite particles. In this study, different leaching methods, as well as zeta potential measurements, were used to examine the major easily accessible ions on the particle surfaces and their effect on the surface charge. The results show that the enrichment of elements on the surface of the particles appears early in the refinement process. Ca was enriched up to 15 times and Si up to 50 times compared to what pore water alone would have given. The leaching experiments also showed that the addition of water glass increased the surface enrichment of Si and that the collector might hinder desorption of Ca. An alkali leaching method was evaluated, which showed that Si was much more enriched than S and Cl. Zeta potential measurements on synthetic magnetite particles showed that process water resulted in zeta potentials different from the potentials measured for these particles in aqueous calcium and silicate solutions. Therefore, it is important to consider the complexity of the process water when making predictions about the properties of the particle surfaces in the final magnetite concentrate, which most studies do not. Zeta potential measurements were also used to rule out a strong influence from organic matter in the process water on the magnetite zeta potential.

By K. Yatsunami

NKK has developed a new cold bonded pellet process. The features of this process are; 1) it is a continuous process with 10 hours curing. 2) Products can be used as materials for various metallurgical furnaces. 3) Various kinds of slag are used as binders if necessary. 4) The quality of products is excellent. The pilot plant completed in 1981 is now being successfully operated. We are also constructing a commercial plant at our Niigata works. We produced cold pellets containing carbon as material for ferroalloys (Si-Mn), by pilot plant and used them in furnaces. Consequently, considerable economic advantages were obtained.

Jan 1, 1984

By R. Mensah-Biney

The aqueous biphase separation process (ABS) has been used to separate ultrafine industrial minerals. The partition behavior of TiO2, Al2O3, Fe2O3 and kaolin was not pH dependent. The partition behavior of SiO2 was, however, pH dependent. The partition coefficient of kaolin in PEG 3400/ Na2CO3 biphase system was = 150 and that of the silica in the same system was = 0.02, resulting in a separation factor of = 8500 between kaolin and silica. The aqueous biphase separation system was used to separate free silica from kaolin in a raw clay sample from Mexico. The partition behavior of mica, feldspar and clay from North Carolina was also evaluated.

Jan 1, 1999

By W. Joseph Schlitt

The use of plate and frame filter presses for dewatering cement copper at Kennecott&apos; s Bingham Canyon precipitation plant is described. The dewatering process begins by periodically flushing a dilute copper slurry from cone precipitators to a rake thickener. The thickener underflows intermittently to an agitated surge tank which feeds the filter presses with a relatively constant slurry containing 10 to 20% solids. The presses operate with a three-stage cycle; loading, air blowing and discharging. Exothermic reactions occur during the air blow which cause actual drying as well as promoting dewatering via simple filtration. At the completion of the air blow, the presses are discharged onto a conveyor belt which transfers material to the load-out building for shipment to the smelter. An extended investigation was undertaken to relate moisture content in the filter cake to maximum press temperature, acidification of press feed, percent solids in the feed, and percent insol in the copper. Of these, press tempera¬ture and feed pH (3. 5 to 1. 0) have the greatest impact on drying. Because the discharged filter cake is hot and continues to undergo exothermic oxidation, significant drying occurs during subsequent handling so that a product containing 8 to 14% moisture is delivered to the smelter.

Jan 1, 1977

By Miguel Reyes, Chenming Zhou, MATTHEW GIRMAN

Electromagnetic energy emitted from electronic devices has been known to interfere with other electronic systems, hindering their ability to function properly. Mines have many electronic devices critical to the health and safety of mine workers that could be negatively affected by electromagnetic interference (EMI). To ensure that devices are electromagnetically compatible, tests must first be conducted to measure emissions and check for immunity. There are many standards available across multiple industries that prescribe emission limits and test methods for electronic devices. Due to the unique environment of an underground mine, it may not be enough to simply adopt a standard from another industry to mining. A literature review has been conducted, and an overview of EMI standards in other industries will be provided in this paper. Also, an example of how a standard can be applied to mining equipment is presented. Finally, recommendations on standards which could potentially be applied to mining will also be included. This work will inform the mining industry of EMI standards in other industries so that mine workers and technology manufacturers have guidance of the steps that can be taken to investigate and reduce the impact of electromagnetic interference and potentially work toward electromagnetic compatibility. The findings and research involved in this effort can also be used to explore the need to develop mining-specific EMI recommendations and standards.

Nov 25, 2021

By T. P. Meloy

Traditionally the mineral and mining engineers have characterized particles by sieving and-settling. Within the last decade, with the advent of the scanning microscope, entirely new experimental and theoretical approachesl-10/have been taken to minutely define the particle surface. This approach depends upon a hypothesis which takes advantage of the recent developments in automatic micro-scopes which can acquire large amounts of information in a short time and the new computational techniques which rapidly reduce the information to meaningful, practical data. Historically sieving and settling are the oldest sizing techniques known. Sieving by square screens, shown on Figure l-A is a common, current practice for sizing particles both in the laboratory and in production. A woven cloth is used which usually has square openings. The size particle that will pass through the opening dependent on a complex relationship of its morphology. As can be seen in Figure l-A, neither the width nor the height of the particle is determined by sieving. From square screens one and only one parameter characterizing the particle size is obtained, that parameter is the radius of the sphere that will just pass through the given sieve opening. A variation of square mesh screen is the slot screens, shown in Figure 1-B. Here another measure more closely associated with the height of the particle is obtained. Once again, one and only one parameter is associated with the particles&apos; shape.

Jan 1, 1977

By John E. Appleby

Grupo Acera, HYLSA originated in 1942 when Hojalata y Lamina began operations to supply steel strip for the Cuauhtémoc Brewery, the parent company. Production began in April, 1943 with growth accelerated because of World War II. By 1948 the company was producing its own steel from electric furnaces charged with scrap iron. Further expansion was hampered by the fluctuations in availability, price and quality of scrap iron. As a result, a search was made for a suitable process to enable HYLSA to satisfy its need for a reliable source of feed for its steel-making facilities. Their relatively low iron requirements at the time did not justify the very high capital investments required using the conventional blast furnace method. Processes which by-passed the blast furnaces were very much in their infancy and were not commercially tested. HYLSA then undertook an investigation of the direct reduction processes, knowing full well that much larger companies in other countries had investigated several processes but their work had not established a trend toward direct reduction or any particular process. However, after much effort and persistence HYLSA arrived at a process which suited their conditions. By using Mexican iron ore and natural gas they developed the now well-known H. y L. Process to produce sponge iron. Concurrent with the start of investigations which led to the H. y L. Process, HYLSA began an exploration program for a suitable source of iron ore. Thus in 1951, Cia. Minera Las Encinas, S.A. was formed, culminating in the development of the ore bodies near Pihuamo in the State of Jalisco. Mining commenced and ore was

Jan 1, 1971

By Tianzu Yang, Weifeng Liu, Lin Chen, BOYI XIE, DUCHAO ZHANG, HUI XIAO

The oxygen-rich bath smelting process of copper dross was simulated using Factsage software. It was found that the two-step simulation results agreed better with the industrial data, especially in the speiss. Bi, Pb, Sb, As, and Cu contents in the speiss by two-step simulation differed from the industrial data by 0.6 wt.%, 0.8 wt.%, 2.6 wt.%, 7.2 wt.%, and 8.6 wt.%, respectively. Twostep simulation results indicated that the speiss partitioning of Sb, As, and Cu increased from 60.1%, 32.3%, and 27.5%to 81.6%, 67.8%, and 47.2%, respectively, with the smelting temperature increasing from 1050 °C to 1250 °C. While the metal partitioning of Sb and Cu increased from 0% and 2.7% to 15.2% and 13.3%, respectively, with the separation temperature increasing from 400 °C to 700 °C.

Oct 19, 2020

By G. Folmo

Allis Mineral Systems&apos; GRATE-CAR agglomeration/induration/reduction process is currently being operated to process ilmenite at Tinfos Titan & Iron KS in Tyssedal, Norway. In this process, balled ilmenite concentrate is fed to a traveling grate where pellets are dried and preheated, using fully oxidized kiln exhaust gas. Hot preheated, semi-indurated pellets are fed directly to a ported kiln where reduction of the ilmenite&apos;s iron oxide fraction occurs in the presence of lump coal. The reduced pellet sand coal char are discharged from the kiln to an indirect rotary drum cooler. Cooled pellets and char are screened and magnetically separated prior to their further processing in a downstream smelting operation. The pellets are melted and the titanium dioxide and iron are separated. Operation commenced in late 1986.

Jan 1, 1992

By C. A. Rowland

Wet grinding rod mills have been used for 50 years to grind ores and to make specification sand. The application of wet grinding rod mills is well understood. Until recently, there have been very few installations of dry grinding rod mills. The basic principles learned from wet grinding rod mills that were used in the application of dry grinding rod mills are 1. It is possible to extrapolate the performance of 5&apos; and 6&apos; diameter wet grinding rod mills into larger diameter rod mills with the larger mills performing as predicted. Wet grinding rod mills as large as 14&apos; diameter (inside shell) by 20&apos; long using 19.5&apos; long rods are in use operating satisfactorily. 2. Wet grinding rod mills generally grind more efficiently when the fines are left in the mill feed than when the fines are removed from the feed. 3. Wet grinding rod mills produce little tramp oversize and generally can be operated in open circuit except when very close control on the top size in the product is required. When operated in closed circuit, the circulating load is normally less than 100%. 4. The power required for the desired grind can be accurately determined from the work indices obtained from rod mill grindability tests on the material to be ground. Where required it is necessary to, apply inefficiency factors for oversize feed and for larger or smaller than normal- ratios of reduction. Recent applications for rod mills have developed where it is required that dry grinding be used. These recent applications cover the grinding of 1. Lead sinter, lead slag and limestone. 2. Iron ore. 3. Silica for making glass sand. 4. Cement clinker. 5. Coke.

Jan 1, 1968

By G. Bylapudi, A. Bhagwat, K. Mondal, A. J. S. (Sam) Spearing

Minimizing the effects of corrosion improves the long-term performance of the rock anchors and ground control systems in underground mines, which is fundamental for safe operation over the design period. The primary objective of this study is to explain the problems due to stress corrosion cracking (SCC), strain-induced corrosion cracking (SICC) and other forms of corrosion, and why the mining industry’s ground control professionals should take this into serious consideration. It is important to clearly determine the kind of SCC mechanisms that causes roof bolt failures in order to suggest the necessary action plan to mitigate or eliminate the possibility of the cause. Pertinent literature and studies around the globe on this complicated subject are reviewed. The secondary objective is to encourage the use of corrosion-resistant ground control products in the underground mining industry in areas of high corrosion potential. Characteristics of SCC on high strength steel are also reviewed. The literature and preliminary studies to date indicate that research work is necessary in United States.

Jan 1, 2015

By R. Heiser, J. Vendetti, B. P. Connor, E. J. Haas

"DISCLAIMER The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health. Reference to specific brand names does not imply endorsement by the National Institute for Occupational Safety and Health. ABSTRACT Health and safety indicators help mine sites predict the likelihood of an event, advance initiatives to control risks, and track progress. Although useful to encourage organizations to work together, executing such risk assessments comes with challenges. This paper focuses on one trona mine’s experience in the development and implementation of a field level risk assessment program to help its entire organization understand and manage risk to an acceptable level. Through a transformational process of ongoing support and communication, Solvay Green River fostered a culture of trust and safety grounded in risk assessment, safety interactions, and hazard correction. The application of consistent risk assessment (RA) tools was critical to create a participatory workforce that not only talks about safety, but actively identifies energies that contribute to hazards and potential incidents. In this paper, reflecting on the mine’s process of RA implementation provides examples of likely barriers that sites may encounter when trying to document and manage risks. As discussed, consistent efforts to establish a participatory risk management program are worth the initial struggle to ultimately reduce incidents. INTRODUCTION Work-related health and safety (H&S) incidents often account for lost days on the job, contributing to organizational/financial and personal/social burdens [1-2]. Accompanying research demonstrates that risk and ambiguity around risk contribute to almost every decision that individuals make throughout the day [3-4]. In response, understanding individual attitudes toward risk has been unquestionably linked to predicting H&S behavior [5]. Although an obvious need exists to identify more comprehensive methods to assess and mitigate potential hazards, some argue that risk management is not given adequate attention in occupational H&S [6]. Additionally, research suggests that a current lack of knowledge, skills, and motivation are primary barriers to mitigating workplace risks [3-6]. Therefore, enhancing knowledge and awareness around risk-based decisions, including individuals’ abilities to understand, measure, and assign levels of risk to determine an appropriate response, is increasingly important in hazardous environments to predict and prevent incidents. This paper focuses on tailored approaches to field level risk assessment (FLRA), measurement, and common barriers to participating in such activities. The authors use a trona mine in Green River, Wyoming, as a case study to illustrate how the organization overcame widespread and site-specific challenges to implement a proactive risk management program. By discussing the mine’s tailored FLRA program, this case study contributes to the literature by first, providing examples of critical components that need to be in place to ensure successful risk management and second, context for continuous quality improvement that can foster a higher level of trust and empowerment on site."

Jan 1, 2017

By X. F. Wang, K. B. Fu

"We investigated experimentally and theoretically the adhesion behavior of Acidithiobacillus ferrooxidans (At.f6) to different copper sulfides. The adsorption experiment showed cell densities of 10.74 × 106, 8.06 × 106, 3 × 106, 4.24 × 106 and 2.35 × 106 cells/cm2, respectively, on the surfaces of djurleite, bornite, covellite and chalcopyrite. The order was: djurleite > bornite > covellite > chalcopyrite. The results indicate that A. ferrooxidans has high affinity to adhering to the surfaces of djurleite and bornite in the acidic region. But the thermodynamic approach predicts that there will be no attachment of At.f6 to the surfaces of bornite, covellite and chalcopyrite. This discrepancy is due to the inadequate description of electrostatic interactions. The DLVO approach shows attachment of At.f6 to the surfaces of djurleite, bornite and covellite, and repulsion between At.f6 and chalcopyrite. The DLVO approach can explain the differences of the adhesion of At.f6 to different copper sulfides.IntroductionThe bioleaching of low-grade copper sulfides is a developing technology, and has been applied successfully to the extraction of copper from secondary sulfide minerals (Watling, 2006; Pradhan et al., 2008; Akcil and Deveci, 2010). The bioleaching of chalcopyrite is still a major challenge (Bosecker, 1997; Brierley and Brierley, 2001; Ehrlich, 2004). A study conducted at Billiton Process Research showed the following preferential order of sulfide minerals leached by mesophilic cultures: chalcocite > bornite > cubanite > covellite > pyrite > enargite > carrolite >> chalcopyrite (Dew et al., 1999). The bacteria can solubilize the valuable metals from the orebodies by the oxidation of minerals. Bacterial adhesion plays a critical role in the bioleaching processes (Chen et al., 2008; Harneit et al., 2006). Generally, bacterial adhesion can be explained by surface thermodynamics and the extended DLVO theory, in which the adhesion energy between the bacteria and mineral is calculated as a function of the separation distance (Sharma, 1999; Bos et al., 1999; Sharma and Hanumantha Rao, 2002). These methods take into account Lifshitz-van der Waals interactions, electrostatic interactions and acid-base interactions (Busscher et al., 2010). These interactions are very well understood and formulated in mathematical equations. The most important inputs in these calculations are surface energy, surface charge, electron donation and electron acceptance on the bacterial cell surface and mineral."

Jan 1, 2015

By D. N. Trerice

The Electric Power Research Institute (EPRI) is sponsoring the construction and operation of a coal cleaning test facility at Homer City, Pennsylvania. The facility represents a major investment by the electric utility industry to advance the state of the art of conventional coal cleaning technology. The facility is unique in design and can process large quantities of coal in conventional flowsheet configurations, simulate full size plant conditions, and perform open and closed loop performance testing on conventional and advanced coal cleaning equipment. Computer operation will also be demonstrated. The facility objectives, initial complement, and operating plane are discussed as they relate to other coal cleaning projects at EPRI.

Jan 1, 1981