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By K. A. Natarajan, S. Usha Padukone

"An industrial waste liquor having high sulfate concentrations was subjected to biological treatment using the sulfate-reducing bacteria (SRB) Desulfovibrio desulfuricans. Toxicity levels of different sulfate, cobalt and nickel concentrations toward growth of the SRB with respect to biological sulfate reduction kinetics was initially established. Optimum sulfate concentration to promote SRB growth amounted to 0.8 - 1 g/L. The strain of D. desulfuricans used in this study initially tolerated up to 4 -5 g/L of sulfate or 50 mg/L of cobalt and nickel, while its tolerance could be further enhanced through adaptation by serial subculturing in the presence of increasing concentrations of sulfate, cobalt and nickel. From the waste liquor, more than 70% of sulfate and 95% of cobalt and nickel could be precipitated as sulfides, using a preadapted strain of D. desulfuricans. Probable mechanisms involving biological sulfide precipitation and metal adsorption onto precipitates and bacterial cells are discussed.IntroductionIndustrial effluents from hydrometallurgical and mineral processing operations often contain high sulfate and metal concentrations posing significant disposal problems, which require urgent solution to avoid serious environmental contamination. In such waste liquors, sulfate and heavy metals such as cobalt, nickel, zinc and iron originate from the chemical or biological oxidation of exposed sulfide minerals. Reduction of sulfate and precipitation of toxic metal ions from industrial wastes is essential from the viewpoint of environmentally acceptable waste disposal and recovery of associated strategic metals.Many of these heavy metals are essential for metabolic activity of bacterial cells at low levels. But they exert toxic effects at concentrations encountered in polluted water. Removal of toxic metals through biological reduction of sulfates from industrial waste waters have been practiced for several decades. Metal remediation through common physicochemical techniques such as oxidation-reduction, chemical precipitation, filtration, electrochemical treatment, evaporation, ion exchange and reverse osmosis processes is expensive and not suitable in the case of voluminous effluents containing complexing organic matter and low metal concentrations. Further, strong and contaminating reagents are used for desorption, resulting in toxic sludge and secondary environmental pollution. Biotechnological approaches can be more efficient and cost effective for detoxification of such effluents. Biotreatment/ bioremoval offers several advantages over conventional chemical and physical treatment technologies, especially for diluted and mixed contaminants. Biological detoxification, which involves the use of microbes to detoxify and degrade environmental contaminants, has received increasing attention in recent years (Iwamoto and Nasu, 2001). In addition, valuable metals can be recovered from metal sulfide sludge (Boonstra et al., 1999)."

Jan 1, 2015

By Lech Bolinski, Joe Shirley

Over two dozen Resin-in-Pulp (RIP) plants have been in operation in the fonner Soviet Union since the beginning of 1970. Currently approximately 50% of the gold produced in Russia, Uzbekistan and Kazakhstan, which equates roughly to 10% of the total world output, is recovered using the RIP technology. An alternative to activated carbon, ion-exchange resin has several advantages for the recovery of gold. Resins are less prone to clay or organic foul­ing and do not require thennal regeneration. They also have poten­tially higher loading capacities, faster adsorption kinetics, and are more resistant to abrasion. The original Russian RIP process was based on engineering expertise developed for uranium ore pro­cessing and has a few major drawbacks. The biggest problem is an 18-30 day resin stripping process, which results in a huge gold lock-up. The problem was recently overcome by the development of a new stripping technology which cuts the time to 12-24 hours. Currently, there is rather limited practical knowledge of the Russian RIP process in the West, but often Western mining com­panies developing gold mines in the fonner Soviet Union are hard pressed by their local joint venture partners to take a serious look into RIP. It is probably only a matter of time before one of these companies will cross Soviet technology with Western engineering and develop a modem RIP process as an attractive option to the current CIP and CIL technologies.

Jan 1, 1996

By J. J. Lewis

In the mid-1970's a major new prospect was proved in a previously unworked region of North East Leicester- shire, United Kingdom. Preliminary estimates from borehole information showed over 500 million tonnes of recoverable reserves. A special Planning Team was set up, to co-ordinate the work for the two local Areas, South Nottinghamshire and South Midlands (management of production of the UK National Coal Board is organised in twelve such Areas). The team was led by one of the authors as Deputy Director, Mining, North East Leicestershire Prospect (NELP). The remit imposed by the National Coal Board was to analyse the possible options of number, location and eventual rates of output of shaft or drift access; to select a recommended alternative in the light of geological, mining, topographical and environmental considerations; and prepare submissions in accordance with standard Board practice on major projects - such submissions including detailed engineering design, financial appraisal, and full risk assessment. To assist the Planning Team, surface and underground consult- ant engineers were appointed to prepare feasibility studies of specific civil and engineering problems.

Jan 1, 1979

By Craig Smith

California is the nation's leading producer of diatomite products. The Lompoc Mining District in Santa Barbara County is the world's largest source of commercial marine diatomite. Grefco Inc. exploration has defined a large embayment of commercial grade freshwater diatomite in Shasta County. Exploitation of this massive deposit could substantially increase California's diatomite production.

Jan 1, 1980

By J. A. Pontius

The Cresson Deposit is located in central Colorado within the historic Cripple Creek Mining District. The deposit has moved from its initial discovery in 1990 to full production in less than five years (current reserve nearly two million ounces). This accomplishment required a great deal of cooperative teamwork between the exploration, development, permitting and corporate groups. Nowhere was this cooperation more evident than in the construction of the geologic block model. The detailed modeling of gold and its metallurgical characteristics formed the foundation upon which critical financial and design decisions were based.

Jan 1, 1995

By E. McCullough

"Fostering positive community relations is a principal tenet of sustainable development, but conflict can test even the strongest of relationships. While conflict surrounding resource development projects has the potential to be destructive, it may actually pose opportunities for partnership and collaboration when managed effectively. It is therefore not only important for mineral resource professionals to recognize the financial and social costs associated with legal disputes among project stakeholders, but also for them to prioritize resolving social conflict using alternative channels that allow for win-win outcomes. A variety of dispute prevention and resolution techniques do exist, but successful practice is not yet the norm. Here we review the sources and consequences of social conflict in the context of mining projects, and discuss typical and alternative approaches to conflict management in light of their respective benefits and drawbacks. We also suggest implementation of conflict resolution lessons into resource-related university curricula as a critical step in the continued shift of the mining industry towards sustainable development. INTRODUCTION Social conflict is a recurring phenomenon in the human experience and serves as a critical mechanism for change [1-5]. It occurs when two or more parties perceive that their needs and interests are in direct competition with each other and believe they cannot be reasonably accommodated. Conflict over mineral resource activities, particularly the distribution of benefit and risk, has become an omnipresent issue throughout the world [6-7]. Contrary to common perception, however, conflict can be a positive, transformative encounter in some instances [2, 8-11]. For this to be possible, society and its acting agents must reconsider how to address conflict. What if conflict were only a challenge to try something different? It is well-understood that the mineral industries must manage an increasingly significant volume of social conflict [12-13], which can be a costly externality impacting all of whom are involved. We commonly consider conflict in a two-party sense, but this deeply over-simplifies the true number of stakeholders. Besides mining companies and community members, government policymakers and regulators, public interest groups, and judicial systems, to name a few, bear the social expenses of poorly-managed conflict [4, 6, 12, 14-22]. It is desirable for interested parties to participate actively in a constructive way to pursue their needs rather than contributing to adversarial relationships, operational problems, and legal costs [1, 4, 12]. Some mining companies are of course already working to develop more productive relationships with their stakeholders, but there is undoubtedly still a gap between ideal and common practices. This gap can inhibit collaboration and threaten the potential for mutually-beneficial resolutions to complex social issues [12]."

Jan 1, 2016

By Brett P. Spigarelli

"To meet the growing need for CO2 capture and storage technology, Michigan Technological University is studying CO2 capture using alkali-based solvents. The objective of the present study was to find a way to increase the absorption rate of CO2 into an alkali solution without reducing the absorption capacity of the solution. One approach to increasing absorption rate is to use a surfactant to chemically alter the gas bubble size. The surfactant chosen for the study was a neutral-charge polypropylene glycol methyl ether (PPGME) with a molecular weight of 200. Experiments were conducted to study the absorption rate of CO2 at varying surfactant concentrations. Results showed that as the concentration of PPGME increased in solution, the absorption rate also increased. The CO2 absorption rate increased from 3.45 x 10-3 mol/min CO2 at 0g/L PPGME to 3.92 x 10-3 mol/min CO2 at 0.48 g/L PPGME. This amounted to a 14% increase in the CO2 absorption rate with no decrease in the absorption capacity of the solution. IntroductionChemical absorption using an amine solvent is currently the most mature carbon capture and storage technology available. Amines are advantageous in that they have a fast CO2 absorption rate, which leads to a high CO2 removal efficiency. However, amine absorption has some considerable drawbacks, such as high energy requirements, high equipment corrosion rates, amine degradation in the presence of oxygen, high waste generation and a large increase in plant footprint if new equipment is constructed (Herzog and Golomb, 2004; D’Alessandro et al., 2010). Due to these drawbacks, Michigan Technological University (MTU) is studying CO2 absorption using alkali-based solvents, which address the above disadvantages of amine solvents."

Jan 1, 2015

Application of flotation for the removal of hydrophobic compounds from soils was studied. Bench scale flotation tests were conducted on artificially contaminated soil, using both conventional mechanically agitated machine and flotation column. Flotation parameters tested include surfactant collector type, conditioning time, flotation time, surfactant dosage, pulp pH, solid/liquid ratio in conditioning and pulp temperature. It is found that with conventional flotation 74% removal of the contaminant was achieved from soil particles in the range of 75-830 µm; with column flotation up to 80% of oil could be removed from the 250-830 µm soil fraction, and 65% from the 75-830 µm fraction. Flotation was found to have considerable potential for cleaning up contaminated soils.

Jan 1, 1998

By German Zambrana

The solution of the problem of beneficiation of cassiterite from its primary ore deposits is of fundamental importance to Bolivia. The process today involves a gravimetric treatment of the ore followed by sulphide flotation. During the last year, a cassiterite flotation stage has been added in several plants to treat the slime tailings. Although cassiterite flotation is already economical for the slime tailings and the mechanism of the process are understood, it is felt that further research could improve the results. In the past, considerable amount of research and test ark has been performed to select appropriate collectors to improve recovery, to increa¬se the grade of tin in the concentrate, to minimize the effect of metallic ions like Ca+2, Fe+2 and Fe+3 which prevent flotation, and to increase the pH of the pulp which now it can not be higher than 3.0. It has been reported that the halogen salts (1) like NaCl exhibit special surface affinity for cassiterite but none for quartz. These effect seems to be favourable for the selective flotation of cassiterite from silica minerals. In view of these preliminary results it was decided to follow the research accordingly: OBJECTIVES The objectives of the present investigation are: 1. 0 evaluate the influence of NaCl salts in quartz and cassiterite flotation.

Jan 1, 1971

By Tsunenori Shibata, Kazunori Jimbo, Kaoru Toya, Masafumi Matsumoto, Jinya Mitsui, Toshinori Tsuji

"The Toyama Line is under construction as a natural gas pipeline with a length of 102 km from Itoigawa City to Toyama City. A 2 km-long tunnel section of the pipeline that we are reporting here is being excavated in a mountain area away from an urban area. The geology under which the tunnel is constructed is collapsible fractured breccia slate and Holocene sandy soil. Other tunnels of the Hokuriku Expressway and Hokuriku Shinkansen are in service above the tunnel route. From the starting shaft on Toyama side, conventional tunneling was adopted to facilitate excavating the base rock layer and maintain enough distance from the Hokuriku Expressway tunnel. From the starting shaft on the Itoigawa side, TBM tunneling was adopted to cope with the unconsolidated soft ground for a 200 m-long section from the shaft. We will discuss the issues and countermeasures concerning the selection of a tunnel route and excavation methods, performance of both conventional and TBM tunneling, and underground connecting of these tunnels excavated by conventional (NATM) and TBM methods under a high groundwater pressure up to 1.2 MPa. INTRODUCTION AND BACKGROUND The International Petroleum Exploration Teiseki Co., Ltd. (INPEX) is constructing a high-pressure main pipeline network in the Toyama Prefecture area to promote the use and reliable supply of natural gas as shown in Figure 1. As part of the Toyama line project that has a total length of 102 km, A-1 construction, the nearest section to the tunneling starting point in Itoigawa City, where various tunnel excavation methods have been adopted to install the high-pressure pipeline 20 inches in diameter, a 2 km tunnel in the A-1 construction section discussed here is to be excavated by conventional and TBM methods in a mountain area. Based on environmental studies such as traffic jams due to frequent traffic of heavy vehicles disposing of soil, and the effects of dust, noise and vibration during construction, we selected the route to install the gas pipeline in a mountain area as shown in Figure 2, where the impact on the surrounding environment could be minimized."

Jan 1, 2016

By B. K. Mishra

The motion of the charge inside a grinding mill is of considerable practical importance. The dynamics of grinding mills have been the subject of study by a number of workers because it can accurately predict: i) the power drawn by the mill, ii) the distribution of forces inside the mill, and hence the wear rate of balls as well as the liners, and iii) mass transport of milled product through the porous ball charge. Some of the earlier analyses of the motion of a charge of particulate material in a tumbling mill were reported by White (1904), Davis (1919), and Dyer (1945) and have been reviewed by Rose and Sullivan (1958). In these works, frictional force at the wall of the mill and between the colliding balls, and the interaction of different ball trajectories, was not considered. Moreover, it was assumed that the profile of the tumbling charge is independent of the degree of filling, which is generally not true. However, all this work led to the identification of so-called "equilibrium surface" which is the plane that separates the rotating charge into two regions. The inner region is static; here there is no motion relative to the mill shell. The other region is a shear region where either the balls flow down the surface of the charge (cascading motion), or are projected out of the surface and follow approximately parabolic paths (cataracting motion).

Jan 1, 1990

By J. J. Harrington

Manufacture and mixing of flotation reagents at the mill site provides an economic and convenient method of maintaining a continuous and fresh supply of reagents for concentrator operations. Kennecott Copper Corporation has designed and built a Reagent Mixing Facility which incorporates new ideas in construction and fail-safe operation at its Nevada Mines Division concentrator. Highly sophisticated automation and instrumentation techniques are combined with safety procedures and equipment that meet and exceed all Federal and State safety requirements. Installation of the facility has minimized hazardous working conditions for the operator, isolated reagent preparation from production personnel and equipment, and reduced the time required for reagent preparation from three shifts to one shift per day.

Jan 1, 1976

By Jonathan G. Price

Silver-copper-lead deposlts in Precambrian, Permian, and Cretaceous red-bed sequences near Van Horn, Texas, have the following features In common: (1) mineralization controlled by steeply dipping fractures in sandstones, (2) lack of ore In overlying and interbedded limestones, (3) absence of igneous intrusions, (4) sulfide ores without typical hydrothermal gangue minerals, and (5) associated arsenic, molybdenum, zinc, and cadmium but not gold. Ore was probably deposited along fractures by reaction between low-temperature, oxidizing, metal-rich ground waters and sulfide-bearing waters or rocks. Detailed mapping and studies of fracture patterns indicate that mineralization occurred during Basin and Range extensional deformation, thereby postdating major Trans-Pecos igneous activity.

Jan 1, 1983

By F. Dehghani, M. Kebe, H. Askari-Sabzkoohi, T. Ghosh

The depletion of bauxite reserves around the world has necessitated the search for viable alternative sources of aluminum. The major non-bauxite source of aluminum is alunite [KAl3 (SO4)2(OH)6]. Lixiviation is the common industrial process to recover aluminum from alunite. Due to the presence of quartz (40%) as the main gangue mineral, this process causes the formation of Sodium aluminosilicate and Potassium aluminosilicate complexes that leads to loss of alunite, and chemical reagents. Thus, pre-concentration of alunite is required to remove the gangue minerals. Because of the low degrees of freedom (DOF) of alunite, froth flotation, as a preconcentration method, is a viable alternative to increase selectivity in downstream processes. In this work, the possibility of Alunite preconcentration with micro flotation and mechanical flotation cells was studied. The influence of type and dosage of collector, pH, solid percent, particles sizes were considered on the flotation. Flotation tests were designed based on Taguchi method, followed by performing based on surface charge differential between alunite and quartz on direct and revers flotation. In the reverse flotation, Ca+ 2 and Ba+ 2 were used to activate the quartz surface. Under optimum conditions of reverse flotation, alunite grade and recovery were 40% and 62.1% respectively. In the direct flotation, the surface of alunite was activated by F- . The grade and recovery were 50 and 89%, respectively.

Mar 2, 2022

By J. Douglas

The past year has been a strange one for the fertilizer industry of the world and the United States. Listening to news stories, you would think the sky is falling on the world's agriculture and probably conclude that we should have had an exceptionally poor fertilizer season. In some respects, we did. Prices were low, profits were low, and in some cases nonexistent, but volume was good. We heard much in the press about the farmers' credit crunch. The truth of the matter is that only 6.6 percent of the U.S. farmers have debt-equity ratios of 70 percent or more, and a large percentage of our farmers have absolutely no debt but operate entirely on their own cash assets.

Jan 1, 1985

By G. Richard Dreese

Most coal mining states have passed or amended laws restricting strip ruining in the past two years. In light of this and in anticipation of further restrictions by the states and the federal government on strip mining this paper attempts to show the Impact of these new laws on the structure of the coal mining industry in Ohio and specifically on one small stripping firm in Ohio. The implications of the study are applicable to other states under similar circumstances and to other industries which are being caught up in the ecological-economic struggle.

Jan 1, 1973

By V. C. Koppe, J. F. C. L. Costa, D. M. Marques, A. Amaral

Errors associated with estimating the grade of an attribute of interest in a deposit can compromise planning, sequencing, and mineral beneficiation decisions. Several factors are associated with estimation errors. Among them, we can highlight the factors associated with sample spacing, the size of production volumes, and the variability of the attribute considered in the estimation. The access to estimation error can be obtained by some geostatistical methods, for example, by stochastic simulation. However, this is a process that in some situations is computer intensive and takes time. Previous works have proposed a simplified method to access the Maximum Estimation Error (MEE) associated with different types of grade variables, depending on the sample spacing, at small production volumes and considering specific coefficients of variation ranges. This paper presents an approach to assess the MEE associated with long-term volumes. Considering the methodology proposed, it is possible to approximate if a specific drilling pattern used in a deposit provides an acceptable pre-determined estimation error for Resource Classification. Results and considerations on the impact of the geometry of larger production volumes on the MEE calculation are also presented.

Jun 25, 2023

By S. Shankar

The phenomenon of re-entrainment is seen in many environments, such as sand dune formation, soil erosion, fugitive dust emission, spread of radio-nuclides from accidents involving nuclear weapons, etc. A thorough review of existing literature reveals that work on re-entrainment of dust in mine atmospheres is scant. The present study was undertaken as a part of on-going research in the Respirable Dust Center on the prediction of ambient dust concentrations in mine atmospheres (Ramani, 1983) to identify the contribution of dust re-entrainment to the spatial and temporal concentration in mine airways and included wind tunnel and in-mine studies. A set of seven experiments was performed in the Lake Lynn Laboratory Mine of the U.S. Bureau of Mines under controlled conditions. Two types of source coal dust, anthracite and bituminous, were subjected to airflow with a range of air velocities and walking by two different walkers. Six sets of instruments were used along the test section for sampling the airborne particles. The average air velocity just above the coal dust bed varied between 2.1 to 3.2 m/s. Due to re-entrainment as a result of the airflow conditions, the average respirable dust concentration in the center of the mine airway increased to 0.09 mg/m3 (standard deviation = 0.03 mg/m3) from an initial value of 0.02 mg/m3. The concentration of all (i.e., total) airborne dust increased to 0.17 mg/m' (standard deviation = 0.10 mg/m') from an initial value of 0.02 mg/m'. The action of personnel walking, however, caused higher amounts of re-entrainment. Average concentration of respirable and total dust at the center of the mine airway increased to values of 0.28 mg/m' (standard deviation = 0.12 mg/m3) and 1.53 mg/m3 (standard deviation = 1.0 mg/m3), from initial values of 0.03 mg/m3 and 0.05 mg/m3, respectively. It was observed that the dust concentrations were much higher near the floor, immediately at the end of the coal dust bed. Depending on the level of activity and the amount of dust deposited in mine airways, re-entrainment may become an important source of airborne dust away from the point of actual mining.

Jan 1, 1994

By P. A. Roberts

A proposal for a modified in situ leaching method for extracting gold from oxidized gold ores using a non-cyanide lixiviant is described. A non-cyanide lixiviant is suggested because of the obvious concerns posed by injecting cyanide-bearing solutions into the subsurface. Oxidized gold ores were chosen as a focus because earlier research on the use of sodium thiosulfate as a lixiviant under anaerobic conditions indicated that the presence of pyrite led to rapid thiosulfate breakdown. A reconnaissance research program involving ore characterization and hydrometallurgical test work on samples from four Australian ore deposits and preliminary reactive transport modeling studies was carried out. This work showed that lixiviant-oxidant combinations of sodium thiosulfate and ferric EDTA and iodide and iodine are both capable of extracting high percentages of accessible gold from the selected samples in bottle roll tests under anaerobic conditions. The ore characterization and reactive transport studies suggested that both physical and chemical methods of permeability enhancement may be required to lift bulk permeability and the availability of gold for dissolution to sufficiently high levels to obtain adequate gold recoveries. Assuming that such methods prove to be both necessary and economically viable, the mining method would no longer be regarded as simple in situ leaching. Therefore, the term ?in-place leaching? has been adopted for the proposed gold extraction system.

Jan 1, 2010

By M. Takayasu, J. Y. Hwang, F. J. Friedlaender, G. Kullerud

Al unite has been used as raw material for producing alumina and potassium sulfate fertilizer in Russia for many years. In the United States, this mineral has not been commercially processed though reserves of 5 to 10 billion tons of alunite ore have been estimated. Major constituents of these ores are quartz and alunite. The minerals are finely intergrown and liberation occurs below 10 µm. Adequate separation techniques for such ultrafine particles have not been developed. A new method for the beneficiation of al unite ore is proposed in this study. This method utilizes a small amount of fine magnetite upon which the liberated quartz is selectively flocculated. The co-flocculated magnetite and quartz are then separated from the alunite in a high gradient magnetic separator. Clean products, e.g., an al unite concentrate of 90% grade with 80% recovery, has been obtained from Utah ore. Techniques for selective co-flocculation of magnetite and quartz, separation of the carried quartz, and recovery of magnetite after separation are discussed.

Jan 1, 1987