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By N. W. Johnson

Two analysis tools which have been applied to problems in industrial Flotation processses are the application of kinetics and detailed mineralogical or liberation data, both on a size-by-size basis. The paper describes practical examples of the application of kinetics to examination of the entrainment recovery mechanism, the retardation of valuable minerals at the commencement of flotation sections and the resolution of problems related to valuable species with reduced rate constants at the end of sections. Examples of the usefulness of size-by-size liberation data for monthly composite samples of products from a concentrator are also described.

Jan 1, 1985

By M. K. Gangal, E. D. Dainty, G. Kunchur

This paper presents a validation of C02 as a single surrogate measurement for other diesel-emitted pollutants in multi-diesel-machine operations typical of small underground mines. This means that the simple measurement of C02 alone can be used to estimate the concentrations of other components of diesel exhaust in the mine environment. The linear relationship of C02 concentration with other diesel-emitted pollutants was indicated by the results of simultaneous real-time monitoring of C02 with CO, NO, NO2, SO2, Respirable Combustible Dust (RCD), and Air Quality Index (AQI) in several small underground mines. The SO2 was not directly measured but calculated from the measured C02 concentration and diesel fuel analysis for carbon, hydrogen and sulphur. The measurements were made in the return air drift under various mining conditions involving a number of diesel LHDs and haulage trucks. The statistical analysis and mathematical representation of the several components of diesel pollutants with C02 are presented. Regression analysis shows that at the 1 percent level of significance there is a strong linear relationship of these diesel pollutants with C02. This relationship is discussed in detail, concluding that C02 measurement alone is a good indicator of overall mine air quality and can be used as a control parameter.

Jan 1, 1991

By Ian Mitchell, Peter Faganl, Paul Haddad, Rob Dunne

During the gold cyanidation process, cyanide can be lost from the leachate by various chemical routes. The products of these cyanide losses include base metal cyanide complexes, thio­cyanate and cyanate. These losses are particularly important when treating pyritic or cupriferous ores since the two most sig­nificant cyanic ides, in order of importance, are sulfides and cop­per bearing minerals (I). Cyanidation of pyritic minerals results in the formation of thiocyanate. The problems caused by cyanide soluble copper minerals are well known to the gold processing industry and have been reviewed by several authors (e.g. 2, 3). An important consider­ation, especially with a number of more recent leaching tech­nologies, is the effect of the CN :Cu mole ratio, R, on the gold leaching kinetics. In order to efficiently leach cupriferous ores, it is important that R is maintained at a level that allows suffi­ciently rapid leaching without excessive use of cyanide. The optimum value for R in a fixed leaching system would appear to lie between 3 and 4. This is based on the early observations that the leaching rate is very slow when R is below 3, with a rapid increase in the leaching rate above 3 (2, 3,4). The leaching rate increases gradually when R is greater than 4 (4). The major Cu(I)-cyanide complex in this range of R values is the [Cu(CN)J]2· species. It has been postulated that leaching occurs due to either uncomplexed cyanide or the fourth ligand in [Cu(CN)4]3·, since the stepwise formation constant for this complex is very small (2, 3). An additional consideration when leaching cupriferous ores is the oxidation of cyanide by Cu(II) minerals, resulting in the formation of cyanate. It has also been reported that both sulfide minerals (5) and activated carbon (6, 7) catalyse the oxidation of cyanide to cyanate. From the above discussion, it is important for the leaching con­ditions to be carefully controlled when treating pyritic and cuprifer­ous ores in order to achieve efficient and economically viable leach­ing. For example, large concentrations of thiocyanate in the leachate would reveal large cyanide losses and thus indicate the need for a pretreatment step to oxidize the sulfides. Alternatively, a low R value would indicate slow leaching kinetics and consequent low gold recoveries, indicating the need for increased cyanide dosage.

Jan 1, 1996

By Timothy D. Gardner, Christopher Mark

Coal mines in the Illinois Basin have not engaged in pillar recovery for many decades. In large part, this is due to the exceptionally weak nature of much of the roof in the region. But, as room-and-pillar mining is conducted at greater depths, and larger pillars become necessary, recovering them becomes more attractive. Recently a western Kentucky coal mine became the first in recent times to successfully employ full pillar recovery. This paper describes the many challenges that were overcome during the process. From the beginning, the focus was on protecting the miners from roof instability, using cable bolts, mesh, mobile roof supports (MRS), and engineered final stumps. Two short test panels were extracted first, and the results were used to adjust the support pattern and mining sequence. Further adjustments were made based on subsequent experience. To date, seven panels have been recovered without a ground fall injury.

Jul 1, 2023

By B. R. Satio, P. G. West-Sells, D. B. Dreisinger, B. J. Y. Leong, G. A. Kordosky

Electrolytic techniques have historically been used to remove arsenic, antimony and bismuth from copper refining electrolytes. However, both solvent extraction and ion exchange techniques have been heavily researched and in a number of cases commercially introduced. In this study a large number of solvent extraction reagents and ion exchange resins were screened to determine the selectivity of the reagents for impurity removal. Solvating extractants were found to efficiently remove arsenic from electrolyte. The extent of arsenic extraction increased in the following order: TBP < DBBP < DPPP < Cyanex 925 < Cyanex 923. Antimony and bismuth extraction from electrolyte were demonstrated with the reagent 2EHAP04. The ion exchange resins UR-3300 and Duolite C-467 were found to strongly extract antimony and bismuth from electrolyte. C-467 appeared to be superior to UR-3300.

Jan 1, 1993

By M. M. Foss

Geophysical methods are gaining acceptance in the evaluation of coal mine ground control condition. The use of in-seam seismic investigations has contributed significantly to the body of information concerning ground control feature identification and analysis. Seismic methods have been used successfully in locating voids, faults, fracture zones, roof and floor rock interfaces, and more recently in characterizing in-seam stress distribution. Seismic tomography is an effective tool in data interpretation for several of these applications, but as is the case with other engineering application of geophysical techniques, there are limits as to how much substantive information can be interpreted from a given data set. This paper discusses some of the applications of in-seam seismic geophysical tomography, and the limits to which the transformation from raw data to information should be taken.

Jan 1, 1995

By T. Rudolph, M. Pawlik, J. Benndorf, X. Yin, J. F. Brune, P. Goerke-Mallet

The long and often undefined period in the post-mining phase challenges geo-monitoring with its various responsibilities, like the detection of environmental changes, ground movements and water management. Modern methods of geo- and environmental monitoring observe numerous aspects using active and passive sensors with multispectral, hyperspectral and microwave sensors, with diverse spatial dimensions and spatiotemporal resolutions from satellites, Unmanned Aerial Vehicles (UAVs), in-situ sensors. Data integration, together with on-site knowledge and experience, provides the basis for comprehensive modeling, which improves the understanding of the environmental changes and their related causes, which is an essential step for public acceptance. In this paper, we aim to give a brief overview of various geo- and environmental monitoring methods.

Mar 2, 2022

By Z. Yanni, W. Xuan, Z. Jingyu, D. Jun

"In order to conserve the coal resources, many coal mines which have been mined begin to re-mine. Re-mining face is of complicated circumstances and coal spontaneous combustion is unknown, so experiments are designed to study the characteristics of multiple oxidized coal samples. The investigation into the oxidation of coal is conducive to the safe mining of the coal seam groups and thick coal seams. The non-caking coal is collected as coal samples. The raw coal sample with initial oxidation and the sample after second oxidation and third oxidation are obtained after a certain treatment of the coal. The temperature-programmed system, and proximate and ultimate analysis are adopted to compare the releases of gaseous products of spontaneous combustion characteristic parameters of the multiple oxidized coal sample. With the increase of oxidation times, experimental results indicate that the oxygen consumption rate, the release rate of carbon monoxide and the intensity of heat release are significantly decrease. The characteristic temperature dropped and the size of the pores in coal is smaller as well. INTRODUCTION China accounts for 13% of global coal resources [1-2]. In recent years, more and more coal mines begin to re-mine in order to conserve resources. This production mode is to mine coal pillar left by last exploitation or unavailable for mining. In the process of slicing mining for coal seam groups or thick coal seams, the second or multiple oxidation due to the mining-induced effect, may take place in the goaf of the lower seam. So the spontaneous combustion is prone to occur in this area. The study on oxidation of coal is conducive to the safe mining of the coal seam groups and thick coal seams. Scholars [3-7] have discussed the workability of re-mining for coal mines, verify the feasibility of the existing mining technology for re-mining area, and set up the prevention measures of coal spontaneous combustion. But all these measures are only based on on-site observation data, instead of experiment on spontaneous combustion characteristic parameters of re-mining coal samples which have a great importance for early prediction and forecast. The authors aim at investigating the multiple-oxidated coal spontaneous combustion law, and perfecting the coal spontaneous combustion mechanism to provide a basis for the prediction and forecast."

Jan 1, 2015

By Karoly C. Kocsis, Kyle A. Scalise, Marcelo Bandeira Teixeira

Understanding the effects of various ventilation and climatic parameters on the work conditions and comfort in underground mines is critical for efficient ventilation system design and cost savings and to ensure the health and safety of mine workers. To understand the effects that the thermal damping effect (TDE) and the thermal flywheel effect (TFE) have on the ventilation system design and potential cooling system, this paper compares and analyzes the wet and dry-bulb temperatures at the bottom of an intake shaft using two modeling software packages, Ventsim™ and Climsim™. The comparison shows the consequences and importance of taking into account the TDE/TFE when predicting the climatic conditions in future underground mines, especially when deciding on whether a cooling system should be employed in order to provide adequate climatic conditions in the production stopes, dead-end development headings, and throughout the mine. Ventsim™is able to account for the TFE, while Climsim™does not. Both software packages have their uses and are used within the mining industry, but it is useful to understand their limitations and where the future of underground climatic modeling will lead.

Oct 9, 2020

By Clarice L. Amaral, Ricardo Melamed

Clay-coating has been used as an environmental technology tool for the immobilization of toxic elements. The mechanisms of arsenate retention in clays suggest that not only the system pH is of fundamental importance in the process but also the character of metals and ligands that compose the electrolyte system. The goal of this study was to investigate the interactions between system pH and electrolyte ions on the retention of arsenate in an Oxisol soil. The sorption of arsenate decreases with the increase in system pH, reflecting the competitive sorption of arsenate with OH groups. Solutions containing Ca tend to favour the immobilization of arsenate in a relatively broad pH range.

Jan 1, 1998

By J. Marbeau

In this paper, a geostatistical study of the North Butte roll type uranium deposit is presented. The geostatistical procedure applied takes into account the varying direction of the roll front for reserves calculations. For variogram calculation, the roll front is unfolded thereby allowing estimation of the variogram in directions parallel to and perpendicular to the roll front. Variograms calculated in unfolded space show strong directional anisotropies consistent with the anticipated configuration of the deposit.

Jan 1, 1991

By M. I. Dobrynina

At the beginning of the 80-s the first diamond pipe in the East-European platform was discovered in the North of the Russian Federation on the White Sea Winter coast. During several years while studying this unique area data on kimberlites and country rocks petrophysical characteristics have been collected. Considerable experience in geophysical methods when searching and exploring diamonds was accumulated, and various methods of geophysical data interpretation were used. It has been established from the analysis of geophysical data that diamond-bearing kimberlites are located in the most ancient and the most stable block of the East-European craton.

Jan 1, 1995

Reaction kinetics for gold dissolution in acid thiourea solutions were investigated using formamidine disulfide as an oxidant. For the conditions studied it appears that a surface reaction limits the rate of gold dissolution. The rate was found to be first order with respect to thiourea concentration and half order with respect to the concentration of formamidine disulfide; the apparent activation energy for the reaction was 10.40 kcal/mol (43.40 kJ/mol); and the reaction rate was independent of pH for the pH range 1.0 to 3.0.

Jan 1, 1999

By Hasan Nizamoğlu, M. Deniz Turan, MÜCEVHER TURAN, RAMAZAN ORHAN

Tailings (flotation waste) that is formed during copper production may be considered in the class of valuable wastes due to the amount of copper it contains. Owing to the decreasing grade values in copper ores, utilization of wastes such as tailings that carry certain amounts of copper as secondary sources has become a necessity in both the economic and environmental sense. This study investigated the usage conditions of five different ammonia salts as leaching reactants for the purpose of selective extraction of copper from tailings. For this purpose, the effects of parameters such as leaching temperature and leaching time were examined at different concentrations of ammonium hydroxide, ammonium carbonate, ammonium nitrate, ammonium chloride, and ammonium persulfate. The copper extraction efficiency in the case of using the aforementioned salts by themselves were listed as (NH4)2CO3 (73%) > (NH4)2S2O8 (69%) > NH4OH (64%) > NH4Cl (42%) > NH4NO3 (40%). The highest copper extraction efficiency was obtained in the leaching process that was conducted with the solutions obtained by mixing ammonia salts in the best conditions. Accordingly, as a result of 6 h of leaching at 30 °C in the presence of 22.5% NH4OH and 100 g/L (NH4)2S2O8, 91.47%of the copper was transferred into the

Jun 3, 2020

By R. Mensah-Biney

The loading characteristics of gold-tetrabromide species onto activated carbon have been evaluated using a completely mixed batch reactor system. The overall loading of gold onto carbon was rapid for the first hour but continued slowly without cessation as a result of reduction of gold. Conventional equilibrium considerations were therefore not applicable. Although loading continued slowly after several days, abnormally high loading capacity values of 10-12 meq/g carbon (650-800 kgAu/tonne) could be attained within 72 hours. The loading of gold-bromo species by activated carbon was by the mass transfer of [AuBr4l-onto the carbon surface where reduction to metallic gold took place. Elution of gold from the loaded carbon was feasible provided the carbon had not been loaded to too high capacity values. If loading is carried to high levels, complete elution becomes impractical and the gold may be recovered by ashing the carbon. For the high loading capacities observed, this option would appear to be cost effective. The effect of several variables on the loading capacity of the activated carbon is discussed.

Jan 1, 1992

By Al. Valero, A. Domínguez

This paper appraises the energy requirements for mineral production through an exergy approach taking into account the long-term decline in ore grades. In this context, the exergy required for restoring resources from the dispersed state of the so called Crepuscular Earth into the physical and chemical conditions in which it was delivered by the ecosystems in light of the available technology, is known as exergy cost. The exergy cost is the point of reference in order to evaluate in a single variable, characteristics such as composition, concentration (ore grade) and the state of technology. The ratio between the exergy cost and the minimum thermodynamic cost required to accomplish the same process is called unit exergy cost and provides a measure of the irreversibility of the analyzed processes. Otherwise, the ore grade is one of the main issues which affects directly the costs associated with mining the ore. Hence, the unit exergy costs to produce minerals from progressively lower ores grades by the current technology is analyzed. The unit exergy cost curves are presented for some important minerals such as aluminium, chromium, cobalt, copper, gold, lead, manganese, nickel and zinc, in order to know the trend when the ore grade decreases.

Jan 1, 2011

The 6th International Mine Ventilation Congress (IMVC) was held May 17-22,1997, in Pittsburgh, PA. This marked the second time that the IMVC was held in the United States. The first congress, organized in 1975 by the Mine Ventilation Society of South Africa, was held in Johannesburg. Since then, the meetings have been held every four or five years, with the 1979 meeting being held in Reno, NV. This was followed by Harrogot, England, in 1984; Brisbane, Australia, in 1988; and Johannesburg, South Africa, again in 1992. The IMVC provides an international forum in the field of mine ventilation for the purpose of sharing technology and experience. The meetings are attended by ventilation engineers, academics, consultants, government employees and vendors interested in mine ventilation. As was evident from this meeting, significant progress has been made in the field of mine ventilation. However, disasters continue to occur around the world and long-term health problems continue to affect workers. So there is a need for further improvements in ventilation technology. The highlight of the conference was the technical sessions in which more than 80 papers were presented by authors from more than 20 countries. In addition to the technical sessions, the conference featured field trips to a number of mine properties throughout the United States. Five short courses were offered on topics ranging from respirable-dust control to mine fires and explosions. The conference also featured a trade show. It exhibited the latest advances in ventilation equipment, computer application software, consulting and engineering services, and health and safety equipment.

Jan 1, 1997

By B. Y. Wong

In April 1989, Southern Company Services signed a 3.5 year contract with DOE-PETC for generic engineering development of an advanced physical fine coal cleaning technology known as selective agglomeration. This technology offers the potential for significantly higher pyritic sulfur removal (90% +) than conventional coal cleaning (30 to 50%) while maintaining high Btu recovery (90% +). Engineering development will include bench-scale process development; component development; adaption or modification of existing unit operations; proof-of-concept (POC) module design, fabrication, testing and evaluation; and small commercial facility conceptual design. The information obtained during POC operation will be sufficient to result in a technical and economic design base that can support construction and operation of a small commercial plant. The major goal of the research is to develop selective agglomeration technology to achieve 90% pyritic sulfur removal while operating at Btu recoveries above 90% based on run-of-mine quality coal. This objective will be accomplished in two phases: Phase 1 -bench-scale and component development, and Phase 2 -POC module operation and conceptual design of a small commercial plant. Currently, work is proceeding under Phase 1 (Tasks 1-7) of the project. A review of the status of Tasks 1-7 is presented in this paper.

Jan 1, 1991

By S. N. McIntosh

Column bioleaching was evaluated by the U.S. Bureau of Mines as a means of recovering manganese from a low-grade ore from the Three Kids deposit in Southern Nevada. Manganese was solubilized from the ore using indigenous heterotrophic microorganisms. Diluted molasses medium was provided as nutrient for the microorganisms. The medium was recirculated through the ore bed until the sugars were spent. Two methods were evaluated to recover manganese from the sugar depleted bioleaching solution: (1) adsorption with a weak cation exchange resin followed by stripping and precipitation techniques, and (2) direct precipitation of the manganese using ammonium carbonate. Both methods removed up to 95 pct of the solubilized manganese from the medium as a carbonate salt. After manganese removal, the medium was replenished with fresh molasses and recycled back through the column. More manganese was effectively leached. This process of manganese solubilization and recovery followed by replenishment and recycling of the medium was repeated until 98 pct manganese was extracted from the ore.

Jan 1, 1993

By Jaime Adasme, Héctor González, Benjamín Celada

"INTRODUCTION Santiago de Chile is a 7 million inhabitant city which has a 103 Km long subway network operated since 1975 by Metro S.A. This network is used on a daily basis by 2.3 million people. In 2012 Metro S.A. started the biggest enlargement of the network in its history, through the design and construction of the new Line 3 (21.7 Km) and Line 6 (16.5 Km). The detailed engineering contract for civil underground works of Line 6 (L6) was awarded to the Consortium integrated by ZAÑARTU Ingenieros Consultores and GEOCONTROL S.A., in which Geocontrol was in charge of the design of 11 stations and 14.5 Km of tunnel. L6 crosses L3 in Ñuble and Ñuñoa Station, L2 at Franklin Station and ends, intersecting L1, at Los Leones Station as shown in Figure 1. LOS LEONES STATION DESIGN Location and Characteristics Los Leones Station is placed at the North end of the L6, next to the same named station of the L1 and it has four construction units, as is shown in Figure 2: I. Access Shaft (49 m x 47 m). II. Access Gallery (34 m long). III. Station Tunnel (120 m long). IV. Connection Gallery with L1 (104 m long). A singular feature of Los Leones is that the western section of the station tunnel, built from the access gallery, is located below an underground parking lot which is located in Providencia Avenue, as shown in Figure 3. It is important to highlight that the distance between the vault of Los Leones Station Tunnel and the foundations of the underground parking lot is only 6 m."

Jan 1, 2016