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By E. Asselin

Passivation of Fe-Ni-Co alloys during the Caron leach process is thought to result in low cobalt recoveries in ammoniacal ammonium carbonate solutions. A brief review of the available thermochemical data for the (Fe, Ni, Co)-NH3-H2O systems has been undertaken. The stability of the Co(II) and Co(III), Ni(II) and Fe(II) am-mines was examined through the use of speciation and Pourbaix diagrams at 298 and 333 K and at 6 M total ammonia. Increasing the temperature reduces the stability fields of the ammines and generally constrains the thermodynamic window for the leach. The Fe(II) ammines are only thermodynamically stable under reducing conditions. Polarization experiments show that these ammines are unlikely to form if oxygen is present. Fe-Ni-Co alloy passivation may be alleviated by careful management of potential.

Jan 1, 2011

By E. Asselin

Passivation of Fe-Ni-Co alloys during the Caron leach process is thought to result in low cobalt recoveries in ammoniacal ammonium carbonate solutions. A brief review of the available thermochemical data for the (Fe, Ni, Co)-NH3-H2O systems has been undertaken. The stability of the Co(II) and Co(III), Ni(II) and Fe(II) ammines was examined through the use of speciation and Pourbaix diagrams at 298 and 333 K and at 6 M total ammonia. Increasing the temperature reduces the stability fields of the ammines and generally constrains the thermodynamic window for the leach. The Fe(II) ammines are only thermodynamically stable under reducing conditions. Polarization experiments show that these ammines are unlikely to form if oxygen is present. Fe-Ni-Co alloy passivation may be alleviated by careful management of potential.

Nov 1, 2011

By R. C. Emmett

The industrial practice of concentration of solids and production of clear solution by gravity sedimentation is an old technology. Through the years, many devices have been designed and built to aid this process. One of the more significant developments was a revolving rake mechanism to convey settled material to a central discharge point of a circular tank, patented in 1907(1). In recent years, clarification systems employing parallel inclined plates have appeared on the market; the original device utilizing this principle was patented in 1886(2). Numerous other methods have been invented, tested, discarded and sometimes re-invented, all with the specific intention of improving the capacity of a particular settling area. Sedimentation theory, as expressed in Stokes' Law, shows that the rate of settling of a particle is directly proportional to the difference in density between the particle and the surrounding liquid and, more significantly, proportional to the square of the particle diameter. Anything that can increase the latter will greatly assist sedimentation and, as a result, flocculation always has been an integral part of sedimentation. Most materials suspended in aqueous media are naturally flocculent to some degree and, hence, are readily concentrated by sedimentation, although sometimes very slowly.

Jan 1, 1978

The last decade has seen the use of powerful computerized Mine-Wide Monitoring (MWM) systems for detecting hazardous conditions in underground coal mines. Recently, the U.S. Bureau of Mines and Jim Walter Resources, Inc. (JWR) expanded the scope of MWM system to include ground control. Single-point extensometers were installed in each of 30 intersections along a tailgate entry. These instruments monitored the rate of roof sag, a sensitive indicator of roof instability. Data were collected by the mine's own computerized MWM system. The paper describes the successful integration of ground control instruments into MWM, the data reduction procedures, and the identification of several hazardous areas.

Jan 1, 1994

By I. A. Tinto

Labrador City is located in the southwestern portion of Newfoundland-Labrador, approximately 965 kilometers north-east of Montreal. The mine and beneficiation complex of the Iron Ore Company of Canada, known as the Carol Project, is situated 535 metres above sea level in a climatic region characterized by cold winters and short, cool summers. History The iron Ore Company of Canada commenced work in the area in 1949, however, it was not until 1958 that the decision was made to proceed with mining operations. The ore body consists of Specular Hematite (Fe203) and Magnetite (Fe304) with small quantities of Limonite and Geothite. The average grade of the ore bodies is 39% iron.

Jan 1, 1985

By M. K. Rizkalla

This paper discusses the time-dependent behaviour of rock when it involves the presence of several layers of rock strata in the vicinity of mine openings, mining in sequences and the placement of backfill. The paper describes numerical techniques which proved useful when such situations are encountered in practice. The model is elastoviscoplastic. At given time stations, short term loading or changes can be made to the creep behavior of the rock. The modelling technique is first described and is followed by simulations of stresses and displacements in a potash mine with the primary objective to demonstrate the effect of such aspects as mining and fill sequences in 3-D. This involves cutting finite elements representing the strip of the mining face and simultaneously filling those elements representing the newly placed fill. The stiffness of the fill varies with the degree of compaction at each point. In this way, the effect of the time of fill placement, the gap between the top of the fill and the back as well as the degree of compaction are simulated. The second example is a 2-D problem simulating the long term effect of backfill, as a material compacting with time, on the settlement of the layers above it as well as the closure of the room.

Jan 1, 1996

By Liliana Rybarska-Rusinek, Aleksandr M. Linkov, Ewa Rejwer-Kosińska

Joined modeling of stressed state and induced seismicity is a means to join geomechanics with seismic observations. When applied to quantifying rockburst hazard, it provides, on one hand, estimations in terms of mechanics, such as stress concentration, and, on the other hand, in statistical terms of the risk analysis developed in mining seismology. The modeling became possible due to progress in computers and numerical methods. However, despite tremendous increase of computational abilities, the joined modeling is still quite time expensive. To make it available for wide use and real time simulations, there is need to reduce the time cost of its key stages: calculation of stresses, caused by mining, and simulation of seismic events, induced by these stresses. The present work aims to decrease the time cost. The stages are time costly because of the same reason, which is a very large number N (up to millions) of elements, representing rock structure, openings and flaws. This leads to immense computational complexity (roughly of order N2) of conventional accounting for pairwise interactions between the elements. The complexity may be notably reduced, when employing the fact that interactions decrease with growing distance between elements. Specifically, the fast multipole methods (FMM) avoid the complexity N2, by employing translations of far-fields from whole collections of sources. This reduces the complexity to the order 22, where p is the number of terms involved in a single translation, is the number of translations, and is the dimension of the quantity translated. Still, for conventional FMM, the complexity remains too high to routinely perform joined modeling of stresses and seismicity.

Apr 26, 2022

By O. J. Malacarne

The use of a series of thickeners for-washing of the slime fraction of a leached ore is not uncommon in the uranium industry; however, few ore processing mills have used a thickener circuit for washing leached total ore. The, common, practice is to wash the sand fraction in classifiers and, the slime fraction only in thickeners. At the Uravan mill of Union Carbide Nuclear, Company, a total ore' acid leach is employed to extract uranium values from sandstone ores. These leached ores are then washed at a nominal rate of from 1,000 to 1,300 tons per day in a series of washing thickeners. A typical screen. analysis of the ore being washed in these thickeners, is 25 percent -200 mesh, 3 percent +35 mesh and about, one' percent +l4 mesh., The amount of slimes (-200 mesh) will vary from 20 to 30 percent s the mill receives ore from 150 different mines The washing liquor is acidic, from a pH of about 2 in the first thickener to 0.6 pH in the last thickener and of course ally acid duty equipment must be used. The Uravan mill of Union Carbide Nuclear Company is located in Montrose County, Colorado and is physically located on a canyon wall along the San Miguel river. The thickeners referred to in this, paper are located on top of the mesa above the canyon. For purposes of identification, these thickeners are numbered 1 through 8 from south to north.

Jan 1, 1962

By Michael N. Greeley

The movement to reclaim abandoned mine sites has gained momentum as federal, state, and private organizations have increased their commitment and resources to tackle mutual, and often controversial, problems of health and safety. Numerous interorganizational agreements have been implemented to promote cooperation in the characterization of mine site hazards, development of mutually acceptable plans of remediation, and sharing of actual cleanup requirements. Working through these partnerships, the federal land management agencies have begun to focus on abandoned mine reclamation in selected, priority watersheds and other drainage basins. Although there are major difficulties to overcome, significant progress continues to be made.

Jan 1, 1999

By Peter Zhang, Daniel Su, Berk Tulu, Bo Hyun Kim, Zoheir Khademian

Over 2,000 shale gas wells have been drilled in the Pittsburgh Seam longwall reserves. As longwall panels are laid out, some of these shale gas wells must be located in longwall chain pillars. With longwall mining on both sides and the constraint of chain pillar size, gas well in chain pillars are subjected to longwall-induced ground movements and stresses, which could induce deformations in gas well casings Casing deformations are associated with several factors such as overburden geology, surface topography, setback distance, and casing construction. Overburden geology is one important factor that largely determines the locations and levels of deformations in gas well casings Previous NIOSH gas well research has found that casing deformations above the coal seam horizon are smaller under deep cover than unde shallow cover and that casing deformations could occur at the coal seam horizon under deep cover. Recent mine-by cases have provided more insights into the locations and amount of longwall-induced casing deformations as well as the potential occurrence of a large casing deformation at the coal seam horizon. This paper presents three recent mine-by cases with shale gas wells in the chain pillars between two adjacent longwall panels under different overburden depths. Casing deformations were measured by multi-finger caliper surveys and predicted with numerical modeling. With the established numerical model, the effect of overburden depth was further analyzed to investigate the potential occurrence of a large casing deformation at the coal seam horizon under deep cover. These mine-by cases not only provide a general demonstration of how overburden depths can affect longwall-induced stresses and deformations but also give a good indication about the level of casing deformations that could occur under different overburden depths. The study concludes that (1) casing deformations reduce with increase of overburden depths at the gas well; (2) a cementing alternative with production casing uncemented is an effective means to eliminate production casing deformations; and (3) large plastic casing deformation could occur in the production casing at the coat seam horizon under deep cover. The experience and knowledge gained from these mine-by cases would help longwall operators and gaza companies to take appropriate measures to minimize the influence of longwall mining in shale gas wells in chain pillars.

Jun 25, 2024

By M. S. Safarzadeh, V. Agarwal

"The solvent extraction of cerium(III) and samarium(III) from mixed solutions of all rare earth elements (REEs) except promethium using PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), an acidic extractant, was investigated. The effects of aqueous equilibrium pH, various acids (sulfuric acid (H2 SO4 ), hydrochloric acid (HCl) and nitric acid (HNO3 )), initial metal ion concentration and extractant concentration on the solvent extraction of Ce(III) and Sm(III) were systematically studied. From the experimental results, HNO3 and HCl were found to be the preferred aqueous media for the solvent extraction of both Sm(III) and Ce(III). The most promising experimental conditions of pH, PC88A concentration and metal ion concentration were identified for the extraction of Ce(III) and Sm(III). Separation results showed that H2 SO4 at pH 2 provided the best separation between Sm(III) and Ce(III). IntroductionIn recent years, demand for rare earth elements (REEs) has increased significantly because of their many commercial applications. REEs have especially important high-tech applications owing to their unique physical and chemical properties, and they are used in a wide range of areas such as catalysts, ceramics, magnets, lasers, glass, neutron absorption and alloys. As REEs have very similar physicochemical properties, their separation and purification from each other is challenging and gaining significant interest. Samarium (Sm) and cerium (Ce) are found in different REE minerals, including bastnäsite ((Ce,La,Nd(CO3)F), xenotime (YPO4) and monazite ((Ce,La,Nd,Th)PO4) at major production sites in the United States and China, as listed in Table 1 (Bleiwas and Gambogi, 2013). The most common acidic organophosphorous extractants used for REEs extraction and separation are DEHPA (di-(2-ethylhexyl)phosphoric acid), PC88A (2-ethyl hexyl phosphonic acid mono-2-ethyl hexyl ester), Cyanex 272 (bis-2,4,4-trimethylpentyl phosphinic acid) and Cyanex 301 (bis(2,4,4-trimethylpentyl)dithiophosphinic acid) (Sarangi, Reddy and Das, 1999; Surampally et al., 2012; Tian, Jia and Liao, 2013). Out of these extractants, PC88A is known for providing higher separation factors (Acharya, Mishra and Misra, 2015). El-Hefny et al. (2010) investigated the kinetics of the solvent extraction of Sm from chloride media using sodium salt of Cyanex 272 and reported the extracted species to be Sm(OH)A2•2HA. Lee et al. (2005) investigated the solvent extraction of Sm(III) with PC88A and saponified PC88A from chloride solutions and found the stoichiometry of the extraction reactions to be 1.5 with PC88A and 3 with saponified PC88A."

Jan 1, 2017

By Y. A. Attia

A study was performed on selective flocculation and dispersion for ultrafine coal cleaning. A totally hydrophobic polymer, FR-7A, was employed as the selective flocculent for coal, sodium metaphosphate (SMP) as the general dispersant for shale and a synthetic polymeric product, polyacrylic acid-xanthate (PAAX), as the selective dispersant for pyrite. In the adsorption tests, nephelometry and spectrophotometry were employed for determining the concentration of FR-7A and PAAX in the solutions respectively. The adsorption tests indicated that: a) FR-7A has a higher affinity toward coal and pyrite than that for shale; and b) PAAX has a much higher affinity toward pyrite than toward coal and shale. In the selective flocculation tests, the ash-forming minerals can be efficiently rejected using sedimentation as the separation method. However, due to their relatively high specific gravity, pyrite particles co-settle with the coal flocs. To reject fine pyrite, a froth flotation was used for floc separation. The one-step flocculation-flotation process could reject more than 70% of each of the pyritic sulfur and ash minerals, while recovering more than 85% of the coal.

Jan 1, 1990

By Thomas H. Ferrigno

Modern Plastics (July, 1983) reported that about 2.2 million tons of mineral fillers were expected to be consumed by the plastics industry that year, of which 7096 was limestone derived. The combination of fillers and polymers is called a composite and, in the more general sense includes continuous and discontinuous components in a matrix. The only significant technical advance in the fillers industry has been the greater general availability of surfied (Ferrigno 1959), an acronym for surface modified, fillers. The many reasons for this occurrence will be given in detail later, but the primary reason lie with differences between inorganic filler surfaces and the polymers which bind them together to form the composite. Minerals and glasses (fiberglass, fly-ash and beads) have surface tensions in excess of 200 dynes/cm, whereas organic materials have surface tensions less than 75 dynes cm. Water has a surface tension of 72 dynes/cm and is always present as an absorbed layer on high surface tension materials to reduce the surface tension. Although almost any organic liquid or polymer has a surface tension low enough to displace the water layer, the highly polar nature of filler surfaces requires highly polar agents to produce a permanent effect, and frequently the water is so tightly bonded or so much more active that the displacement is temporary. Furthermore; the water layer causes tiny particles to adhere to each other (agglomerate) to make sepaartion or dispersion of the individual particles very difficult. The solution to these problems is then to form a chemically bonded layer on the filler surface similar to that of the polymer so that immediate wetting, dispersion and uniform distribution of the filler particles is obtained.

Jan 1, 1985

By Earl Cook

A high-energy economy based on fossil fuels is in fundamental conflict with an ideal of clean air, clean water, undisturbed scenery, and maintenance of fragile ecosystems. There is an inevitable trade-off between the material standard of living of a modern society and the conservation of its environment. During the past four years, some of the costs of environmental protection have been internalized in the energy-flow system of the United States. The cost of bituminous coal and fuel oil usable under new air-quality standards has doubled or more. The cost of mining coal underground has risen because of a 20-30 percent reduction in productivity resulting from new environmental health and safety legislation; the economic impact of proposed surface-mine regulation may be equally severe. The cost of producing electric power has been rising at a 12 percent annual rate because of environmental costs, and would be climbing still more steeply were it not for the continued forced subsidy of natural-gas consumers by natural-gas producers. The efficiency of the automobile, already a monument to the triumph of self- indulgence over economy, is being further decreased by addition of anti-pollution devices. Part of the recent sharp rise in agricultural costs stems from the fact that five energy units of fossil fuel go into U.S. agriculture for every energy unit of raw food that leaves the farm; further large injections of fossil-fuel energy occur in the transport, processing, and refrigeration of farm products.

Jan 1, 1974

By R. K. Singhal

This new tool can be used for the proper assessment of the potential economic wealth of any risky capital project. It does provide an unambiguous recommendation of the type "go or no go" to the decision-maker simply by comparing two different ratios profit/investment. One ratio determines the minimum value required to at least break-even while the other measures a probable value based on the asymptotic theory of statistical extremes (weakest link concept). Its application is briefly illustrated by means of an underground gold mine project, an oil sands mine project and a poly-metallic open pit project.

Jan 1, 1993

By J. R. Heberger

"The Safety Pays in Mining web application, developed by the National Institute for Occupational Safety and Health (NIOSH) Mining Program, helps mines determine the potential costs associated with mining injuries. This web app groups injuries by type, either by the cause of the injury or by the nature of the injury. When the user selects one of over 30 common types of mining injuries, the app provides information on the distribution of costs of workers’ compensation claims for that type of injury. Based on other user inputs, Safety Pays in Mining will estimate the total costs of the selected injuries, including an estimate of additional indirect costs, the estimated impact of total injury costs on mining company profits, and provide some examples of other items (services, equipment) on which companies could spend the savings that result from the prevention of injuries. This paper reviews the Safety Pays in Mining web application by discussing the development of the app, how it is used to show the true costs of mining injuries, and how mines can benefit from using this app. INTRODUCTION Injuries on the job cause pain and suffering. They can also profoundly affect profits and daily operations. In addition to paying direct costs or increased premiums for workers’ compensation insurance, a company might need to pay overtime for other workers to fill an injured worker’s job role, cover training costs for a replacement worker, or divert administrative resources in the wake of an injury. Safety Pays in Mining is a web app that estimates the distribution of these injury costs and assesses the impact that occupational injuries have on a company’s profits. The costs of specific types of occupational injuries in mining are not readily available as mining and insurance companies don’t usually share this information. As a consequence, companies only have cost information based on previous experience with their own employees. Therefore, if a mine never experienced a finger amputation for one of its miners, it would not be aware of the possible costs associated with this type of injury. In addition, injury costs are unique in that the cost distribution is so wide — with half of the injuries in our dataset having mean costs higher than 90th percentile costs — just using the average cost of a specific injury type does not provide adequate information. Some injuries involve immensely high costs, and even though the risk of these high-cost injuries occurring is low, mines need to be aware of their potential impact on their company’s financial health."

Jan 1, 2018

By G. Hoffmeyer, I. Ream

"Several copper projects exclusively utilizing in-situ recovery methods are currently under development in Arizona. Favorable conditions for In-Situ Copper Recovery (ISCR) include a saturated orebody, fracture hosted mineralization, hydraulic conductivity sufficient to effectively inject and recover solutions using wells, and a relatively flat background hydraulic gradient. Safe operation of an ISCR project requires that the operator have the ability to induce and maintain localized hydraulic gradients, thereby controlling the movement of injected and recovered solutions. Benefits of ISCR include reduced initial capital, and a greatly reduced environmental footprint. THE ISCR METHOD EXPLAINED The method chosen to extract a mineral from a deposit is driven by characteristics such as its size, grade and depth of burial. Large lower grade deposits that require significant excavation to access using surface methods are potential candidates for in-situ recovery. ISCR may also be ideal for smaller deposits due to the lower initial capital. However, regardless of the size of the deposit, certain hydrogeologic conditions must be present for ISCR to be successful. In-situ recovery methods do not require excavations of rock from the surface or underground, resulting in a dramatic reduction in surface disturbance when compared to conventional mining. With the ISCR method, what is visible above ground is the processing plant, well heads, piping, process solution impoundments and evaporation ponds. There are no waste rock piles, tailings impoundments, leach pads, or impacts associated with blasting and hauling. Other benefits include reduced initial capital, reduced dust and noise, and lower water use. Early testing of the in-situ copper recovery method by Occidental on the Van Dyke deposit east of Phoenix and by Kennecott at Safford Arizona in the 1970s produced encouraging results, but the permitting regime for a large-scale operation was not yet in place. Additional testing and commercial application of in-situ copper recovery techniques have expanded since the 1980s, most commonly in conjunction with open pit or underground mining operations. For example, several operations in Arizona (San Manuel, Miami East and Tohono) have used in-situ techniques to extract additional copper following conventional mining from parts of the deposits adjacent to open pits or underground workings. Where the rock has been broken up by conventional methods, the method is called “in-place” leaching. The US government has also been involved in assessing in-situ techniques. For example, joint research was conducted by the US Bureau of Mines and industry on the Santa Cruz deposit in Arizona; and both federal and state agencies have been involved to establish the comprehensive permitting regime that exists today. Currently there are several projects in Arizona being evaluated as stand-alone ISCR operations."

Jan 1, 2016

By Yu-ren Jiang

Novel compounds of hydroxycarbamoyl carboxylic acids, including 2-hydroxycarbamoyl -3-methlcyclohexane carboxylic acid (HCMC), 2-hydroxycarbamoylmethyl decylen-4-yl carboxylic acid (HCDC) and 2-hydroxycar-bamoylmethyl tridecylen-4-yl carboxylic acid (HCTC) were synthesized. The flotation behaviors of diaspore, kaolinite and illite using these compounds as collectors were investigated. The flotation results revealed that the floatability of the minerals was, in descending order, diaspore and kaolinite, followed by illite, and the ability to collect the minerals was, in ascending order, HCMC and HCDC, followed by HCTC. At a dosage of 2×10-4 mol/L, both HCDC and HCTC show a strong ability to collect diaspore and a weak ability to float kaolinite and illite. The flotation recovery of diaspore is over 90% and that of kaolinite and illite less than 30%. Moreover, Fourier transform infrared spectroscopy (FTIR) spectrum and zeta potential, as well as the adsorption amount, indicated that the adsorption interaction between HCTC and diaspore was primarily a kind of chemisorption in the form of chelate rings, while the interaction between the collector and aluminosilicate mineral was dominated by physisorption. It was concluded that the novel hydroxycarbamoyl carboxylic acid compounds are highly selective collectors for the flotation of diaspore vs. aluminosilicate minerals.

Jan 1, 2011

Placing a detonating explosive inside a volume of rock is an efficient method of rock fragmentation. The explosion generates internal tensile stresses in the rock, and because rock is a brittle material, this brings about crack propagation and fragmentation far more efficiently than does application of explosive on the surface. To get the explosive inside, we drill a pattern of boreholes and charge the explosive into the holes. This is really the one and only purpose of making blastholes in mining: to give access for the explosive to the interior of the rock. No matter how big and expensive a drilling jumbo we stand up in front of a rock face, and no matter how many boreholes we let it drill, the rock does not fall apart by itself without blasting. It is the action of the explosive in the boreholes that does it. When we consider that we need a pound or two of explosive for every cubic yard of rock to be fragmented, and a pint of borehole volume for each pound of explosive, we see that the process of blasthole charging is an important element in the whole process of rock blasting.

Jan 1, 1975

By S. J. Schatzel, K. M. Ajayi, Z. Khademian

The integrity of unconventional shale gas well casings positioned in the abutment pillar of a longwall mine could be jeopardized by longwall-induced deformations. Under such scenarios, the surrounding fracture networks could provide pathways for gas flow into the mine creating safety concerns. To provide recommendations for developing guidelines that ensure a safe co-existence of longwall mining and unconventional shale gas production, this study evaluates the impact of parameters that could affect potential shale gas flow into the mine in the event of a casing breach using a discrete fracture network (DFN) model. These parameters are evaluated using a conceptualized DFN realization that is representative of the fractured zone in the overburden, and the range of parameter variations are within values validated with field measurements. The results show that a decrease in fracture aperture (potentially due to longwall-induced stress in the likely vicinity of the breach location) reduces the potential gas flow to the mine by a significantly higher proportion. A 50% decrease in the aperture of the fracture that directly transports the gas from the casing breach location reduces the gas flow to the mine by over 70%. Similarly, changes in the fracture water saturation level significantly affect the gas flow. In all cases, the potential gas flow to the mine is higher if the casing breach occurs at an increased gas well pressure. These findings provide critical information regarding the impact of each of the parameters associated with gas flow in the event of a shale gas casing breach near a longwall mine and could help towards the development of guidelines to ensure a safe coexistence of both industries.

Mar 2, 2022