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By K. Ueda

Lead concentrates from Kuroko (black ore) mines, which contain Cu 4 ? 7%, Pb 55%, Zn 3 - 7%, As 0.5 - 0.9% are treated by hydrometallurgical process in order to smelt the product by electric furnace smelting together with other lead resouces from Kuroko. The hydrometallurgical pretreatment involves sulfuric acid leaching at first stage, ferric leaching at second stage. This paper describes the short history of lead recovery from Kuroko and the performance of laboratory test, pilot plant and commercial operation.

Jan 1, 1982

The deformation, failure, and filling characteristics of a caving roof in the initial and normal mining stages of a pitching oblique longwall mining area are analyzed using large-scale threedimensional physical-similitude experiments and numerical calculations to study the characteristics of roof fracture and migration in a steeply dipping seam. The results show that the roof fracture development has evident sequential and spatial characteristics. Among them, immediate roof breaking in different parts of the mining area shows difference in time and space. The failure sequence of the immediate roof in different areas changes with the mining; unique regional stability evolution characteristics are observed in the suspended immediate roof simultaneously, resulting in its significant regional stability on the goaf filling.

Jan 7, 2020

By L. L. Oriard

There are certain site-specific geological and physical features of a rock mass which control its behavior under the dynamic stresses induced by the action of explosives. It is essential that blasting technology be adapted specifically to those features. There does not exist a single, simple "right" way for each type of blasting operation, but rather each operation must be custom-designed for each site. When this is done, it is often possible to produce unusual but highly desirable end resglts, such as undisturbed narrow rock walls, monoliths and square benches. Although the techniques illustrated here were developed specifically for "sculpture blasting", the geomechanics principles would apply to other types of blasting control, both large-scale and small-scale. Because the techniques are designed more for the purpose of modifying the site responses which would ordinarily be expected than they are to developing new "blasting formulae?, the name "Modified Site Response Blasting" will be used.

Jan 1, 1984

Factors which cause thiourea consumption in gold-leaching systems include adsorption by gangue mineral particles, complexation with base metal ions, thermal degradation, and oxidation by air/ferric iron. Of these factors oxidation by ferric iron is the most significant factor. Of course, ferric sulfate is desired as an oxidant for the gold leaching reaction, but an excess of ferric sulfate leads to high thiourea consumption. In this regard, the rate of gold leaching by thiourea must be balanced against the rate of thiourea decomposition. It is important to note that the thiourea decomposition reaction in ferric sulfate solution is relatively slow in pure solutions and has been found to be first order with respect to both thiourea concentration and total ferric iron concentration. However, when mineral particles from gold-bearing ores or concentrates are present, the decomposition rate can become quite significant. As might be expected, the catalytic activity of mineral surfaces varies with particle composition and size. Experimental results are discussed with respect to the consumption of thiourea.

Jan 1, 1997

By C. I. Richman

The E h potential during of a iron reducing bacteria such as Aquaspirillum Magnetotacticum (A.M.) can be predicted by a growth model. It also reflects the adsorption of Fe+2 Cu+2 and Mn +2 ions, that can be incorporated into magnetic material called magnetosomes. The Ferric ion concentration during controlled growth of Thiobacillus Ferrooxidans (T.F.) is a function of the bacteria population curve, while A. M. ferrous ion concentration is a function of the integral of the population curve. Charting of the redox potential of T.F. during batch oxidation of refractory ores such as pyrite and pyrrhotite can be helpful to establishing onset and rate the bulk bio-oxidation rate. The onset of biooxidation is marked by an increase in Fe +3 ions that can be correlated with increased growth due to adsorbed electrons.

Jan 1, 1998

By Alan Rhodes

This study is initiated to investigate the efficiency of separation of mineral slimes using electroflotation as compared to that of column and conventional flotation techniques. Important parameters such as collector concentration, pH, current density, aeration rate, etc., have been studied. The results indicate that electroflotation can be used more efficiently in processing rutile slimes (10 µ) under certain operating conditions.

Jan 1, 1982

By Adrian Brown

The primary method of slope stabilization is ground water-control. Recent research has established the properties which slope materials must exhibit in order for stabilization measures to be feasible, but there is little guidance in the literature about suitable field tests to develop the parameters needed for this evaluation. This paper presents a proven method for large scale testing which allows an evaluation of the feasibility of ground water pressure control in a reasonable cost and time frame. Methods of performance and analysis of the test are presented, and the method is illustrated by reference to case examples.

Jan 1, 1984

By Yi Luo

This paper presents some of the results of a research on long-term subsidence over and near the chain pillar systems -the area available to long-term subsidence in longwall operations. Although the long-term subsidence in most longwall operation is insignificant, it does exist in some cases. For the cases where long-term subsidence is significant, it has been found that the development process can be expressed by an exponential decaying function. The stability factor of the chain pillar system and the potential for long-term subsidence are the two important factors that control the magnitude and development characteristics of the long-term subsidence process.

Jan 1, 1999

By Elena Chiriotti, Federico Valdemarin, Jan Cenek

"SUMMARY The “28 May Station” is the only transfer station between the existing Green and Red metro lines in Baku. As part of the huge development strategy of the metro network, the complete separation of the existing underground lines has been planned at this location, in order to simplify the operation of the future metro system. The extreme challenge of the project is represented by the need of achieve the separation of such lines over a breakdown of the operation of just five weeks. The lack of direct access from the surface, a complex geology with artesian water layers, a congested underground space and sensible buildings represent additional constraints. The chosen design solution consists in creating a complex steel pipe jacking frame around the operating tunnels and then excavating under such frame two large caverns where the separation of the existing lines and the construction of the new metro tunnels will be achieved. Soil treatments have been conceived to mitigate the geotechnical risks and to reduce possible impacts on the existing structures. The paper illustrate the challenges of this extraordinary project, one of the most complex underground structures under study, the design solutions and the risk management approach used to manage the complexity and to design the mitigations measures. INTRODUCTION The metro network in the capital of Azerbaijan is rapidly growing together with its metropolitan area. The beginnings of the existing metro system started in Baku in 1967 in Soviet times. To date, only two lines (Green and Red) are in operation with a total length of 34 km, including 23 stations. The future network will be much wider: besides the construction of three completely new lines and the extension of two existing lines, the whole metro project includes the development and modernization of the existing metro sections. A consortium formed by Systra (leader), Mott MacDonald (Praha) and Saman (Korea) awarded the contract for the preliminary and detailed design of infrastructures for the extension of Baku Metro Network. This extension consists in 83 km of new lines and extension of existing lines. As part of this modernization project, the connection of the Green Line at the 28 May / Cefer Cabbarli Stations, focus of this paper, represent also it’s ""Achilles' heel"" given that the already very congested system have only one transfer station."

Jan 1, 2016

By S. Tuylu, D. Adiguzel, A. Bascetin, O. Ozdemir, U. Cinar

"In recent years, use of mineral processing tailings as a paste backfill has been significantly increased due to the environmental problems occurred during the disposal of the tailings in mine area. The paste material used to fill the stopes excavated is generally consisted of tailings (solid ratio: 70–85%) and cement (3-7%w/w). Meanwhile, the strength of the paste material is completely related to ratios of these materials. Cemented Paste Backfill (CPB) system is used as support depending on the roof pressure and also as an underground disposal method. Therefore, temporary strength value of the paste material gains a great importance. For example, the paste backfill material must compensate the minimum 4 MPa strength value in order to procure the permanent fortification, and the mixture cost must be minimal as well. For this reason, in this study, the Pb-Zn tailings were used to prepare for the paste backfill material using cement in order to perform the uniaxial compressive strength (UCS) tests. Additionally, a statistical experimental design and linear programming techniques was used to find the optimum mixture in terms of strength and cost. The pulp solid ratios (PSR) of the tailings and cement (by the solid) were varied as 75-85% and 3-8%, respectively. The results of this study; the optimum mixture is ~79.5%PSR and 6.8% cement ratio (by the solid) for 4 MPa UCS (28 day) and 16-17 cm slump value determined by this method with statistically reviewed experimental data. INTRODUCTION Fine-grained tailing waste materials resulting from mining activities are an important environmental problem. In terms of environmental protection, the use of tailings with paste backfill is a very attractive approach and a desirable solution to tailings management. Paste backfill, which is used to fill underground openings, is made by primarly mine tailings mixed with hydraulic binders and water. Its main benefits are not only disposal of mine tailings in underground, but also providing a certain strength to ensure a safe working environment. Therefore, it is necessary to use hydraulic binders due to durability of the system (Benzaazoua et al., 2004). Paste backfill, formed from the mix of dewatered plant tailings (75-85 wt. % solids), water and binder (3-8 wt. %) (Brackebusch, 1994; Landriault et al., 2005).Water is used to determine the chemical reactions between tailing and binder materials for strength as well as increasing pumpability. Portland cement and ash can be used as binder materials (Douglas and Malhotra, 1987). The factors which affect strength and stability of paste backfill separate into two groups called interior and exterior factors. Interior and exterior factors determine the strength, stability and deformation features of backfill in short and long terms and also affect the transportation of backfill to underground (Benzaazoua et al., 2004; Erçikdi et al., 2006; Yilmaz et al., 2010; Nasir and Fall, 2010). Material properties of tailings as well as site operations to fill the underground openings are the most important steps for the design purposes. Grain size distribution, chemical, and physical properties of tailings, and mechanical properties of paste fill material are used to understand the suitability of tailings as paste fill material (Ozturk et al., 2014). In addition, Fig. 1. is also proposed to apply a typical design for the operational stages of paste fill applications on the site."

Jan 1, 2016

The paper describes a practical methodology based on numerical modelling for the prediction of progressive failure of underground mine stopes with cable bolt support. A case study of the 40-761 stope at Kidd Creek Mine, Timmins, Ontario is presented. The stope was mined by blasthole open stoping in 1986 as a lead stope within a mining block between 36-1 and 38-2 levels. Initially designed to peak at 38-2 level, the stope back caved upwards approximately 40m towards 36-1 level. Cable bolts were installed above the stope from 36-1 level after caving had begun. The stope eventually stopped to cave when the falling rock mass encountered a sufficiently high cable density. The paper provides details of the geomechanical data and modelling results of the case study. Numerical modelling is carried out using a finite element package known as e-z tools which has, among other things, a special cable/rockbolt simulation capability.

Jan 1, 1994

By T. Gonzales

Magma Metals Company operates an Outokumpu Flash Furnace, four Peirce-Smith Converters and two Anode Casting Wheels supported by six Anode Vessels. Process gasses from the Flash Furnace and Converters are treated in a two train/double contact sulfuric acid plant. Sulfur capture for the smelter is +98%. The new flash furnace was commissioned on July 7, 1988 and has processed over three million tons of sulfide concentrate without a major rebuild. Magma has gained unique experience in the operation of the flash furnace at high oxygen enrichments with low off-gas dust loadings. New procedures have been developed to maintain secondary material generation at equilibrium and for maintaining metallurgical control of operating parameters. This paper describes all the procedures, operation control parameters and operating philosophy that has allowed Magma to achieve superior performance.

Jan 1, 1992

By Ralph C. Flow

In Cleveland County, North Carolina, one and one-half miles south of Kings Mountain, Foote Mineral Company operates an open pit for the production of spodumene, feldspar, mica, and commercial stone. Spodumene concentrate is sent to Footers Sunbright, Virginia plant and to other customers. Exton, Pennsylvania and New Johnsonville, Tennessee plants produce lithium compounds sold to the oil industry for multipurpose lithium-base greases, to the metal industry as welding flux, to the air conditioning market, and to the glass industry. Ceramic grade spodumene, feldspar, and mica concentrates go to other processing companies from the Kings Mountain plant. Waste amphibolite is delivered to a neighboring quarry operation.

Jan 1, 1962

By Stephen Meyer, Véronique Falmagne, Antti Pyy

Kittilä Mine is a gold mine located in Northern Finland, owned and operated by Agnico Eagle Finland. The mining operation started in 2008 with open pits which were completed in 2012 and production moved to being entirely underground. The mine consists of four separate orebodies, currently producing 2.0 Mt per annum, and requiring over 19 km of development on a yearly basis. The principal mining method is long hole stoping with delayed backfill. Microseismic monitoring was initially tested in the Suuri orebody, in the mining block between the 625 and 500 Levels. A small monitoring system was installed in 2018, after observations of stress-induced damage to the rock mass and in anticipation of future mining at greater depth. The initial goals were to evaluate if useful data could be recorded and test the signal quality of different sensor types. Prior to 2018, ground control related challenges in the Suuri and Roura mining blocks had been mostly related to sill pillar mining and block movements between weak graphitic schist planes. Seismic monitoring in the Suuri deposit proved successful for following the rock mass response to mining and helped support the rationale for early monitoring in the new, deeper mining block in Rimpi at 900 m depth. Preliminary geotechnical characterization and testing of the rock mass showed areas of silicification in the footwall rocks with potentially continuous structural features. Seismic monitoring of the Rimpi area has confirmed the brittle behavior of the rock mass, with strong seismic responses induced by stress changes following blasting being recorded. In addition to this expected behavior, a large magnitude event associated with significant damage in the footwall drive development 90 m above the stoping was experienced. Initial investigation of the rockburst showed two separate damage locations with over 300 tons of displaced rock. The seismic monitoring system recorded this rockburst as a single seismic event with magnitude significantly larger than previously recorded. Additional analyses indicated a possible thrust fault event, triggering two separate strainbursts. Following this event, the ground support system was upgraded in parts of the footwall drives to improve dynamic capacity. Systematic calculation of the source mechanisms for the small footwall events down to Mw-2.5 has revealed potential planar structures in the footwall. Early implementation of microseismic

Apr 26, 2022

By B. Qiu, Y. Luo

Longwall and/or room-and-pillar mining operations in multiple coal seams may not only induce subsurface and surface subsidence but also cause interactions between these mined coal seams. The interaction might destabilize underground mine structures and subsequently induce additional strata movements. Mathematical models to use the predicted subsurface deformations to assess the interactions and the consequences have been developed. The models are incorporated into a computer program, CISPM-MS, for predicting the final surface movements and deformations, as well as the mining interactions associated with multiseam coal mining operations. It predicts final surface movements and deformations caused by the individual mining operations and by the interactive effects. The program can also be used to assess mine structural stability in multiseam mining operations. The paper presents the developed interaction models and their application in surface subsidence prediction caused by multiseam mining operations. A case study involving mining in two coal seams, using longwall and room-and-pillar mining methods, respectively, will be used to validate the program.

Jan 1, 2013

By Anil K. Ray

Roof falls are one of the greatest hazards in underground coal mines worldwide. Due to stringent safety measures and extensive support system development, roof falls have been reduced significantly but they still persist in many underground coal mines. Some of the roof falls initiate with cutter roof or guttering. In the past, many factors have been identified as being responsible for the development of cutters and roof fall. These responsible factors can be broadly classified as stress related or non-stress related. In this paper the finer details of mining technique have been taken into consideration for better understanding of cutter roof and roof fall problems. Three dimensional finite difference modeling has been used to explain the mechanism of cutter development. Strain softening material behavior has been used to realistically simulate the cutter formation, and common cutting sequences as implemented in the field have been simulated. This was done with an objective to determine whether the cutting sequence has really any significant control over cutter formation or not. In addition to cutting sequences, the effect of cut length is also studied. The effect of step cutting and turning of crosscut into and away from major and minor horizontal stresses is also examined to see its influence on cutter development.

Jan 1, 2009

By William H. Bird

Over the past 14 years, the efforts of 2 companies and several individuals have outlined a major solfataric gold ore body in the Summitville district in the southeast San Juan Mountains of Colorado. The hard work of these years could not have flowered without a dedication to modern exploration methods, an intense interest in new theories of ore genesis, and a relentless discontent with the accepted geology of the Summitville area. To set the stage for this discovery period, it must be noted that it began 100 years after gold was first found at Summitville. It was the height of the "porphyry copper" era and gold was still not a part of the explorationists' portfolio. It was also a time of great intellectual stimulation. Theories were rapidly developing to relate different types of ore deposition and to place ore genesis within the fabric of plate tectonics. Summitville itself had just been linked to the newly discovered Platoro caldera complex and the Platoro lineament. This in turn related Summitville to the other San Juan volcanic field caldera ore deposits.

Jan 1, 1990

By Tim Cleary, Steve Skelhorn

The 9th Line / 16th Ave tunnels are part of a $700 million expansion of the York Durham Sewage System, north of Toronto. The 15 km of tunnels presented many challenges, including glacial and postglacial deposits, at depths up to 55 m. Due to high hydrostatic heads, the Owner specified EPB tunnelling, however, an alternate was proposed utilising rib and lagging tunnels, combined with a de-watering scheme. State of the art technology was utilised with a new Lovat TBM, incorporating PLC control, soft start water-cooled motors and a head designed to tackle the mixed ground expected. The 9th Line tunnels were completed in 2002. Subsequently the second section of tunnel along 16th Avenue has been awarded to the Joint Venture. This paper presents a case history of the soft ground tunnelling, including design elements, tunnel systems and TBM operations.

Jan 1, 2003

By W. Petruk

An investigation was conducted to determine the minimum number of samples that must be studied by image analysis of polished sections in order to characterize a mill product and to determine the apparent mineral liberation. It was found that a representive polished section cannot be prepared from an unscreened sample that has a wide size range of particles. Similarly individual screened' fractions are not representative of the sample because minerals are partitioned during screening. Consequently the quantities of soft brittle minerals are increased in fine grained fractions and quantities of hard minerals are increased in coarse grained fractions. It is assumed that results obtained by combining data for a series of narrow size range screened fractions (1 Tyler size range) are representative of the sample, and relatively accurate apparent mineral liberation data can be obtained for a mill product by analysing each fraction and combining the data. Somewhat less accurate data would be obtained by analysing a series of screened, fractions that have a wider size range of particles (5 Tyler size ranges). Mineral liberation analyses show that the most reliable apparent mineral liberation in each screened fraction is a value taken from a smooth curve drawn through the lowest points on a graph of % free vs size. A correlation between the apparent mineral liberation in screened fractions and calculated mineral liberations using Kings liberation model is good for sphalerite but not for chalcopyrite and galena.

Jan 1, 1985

By Mark Van Dyke, Mark Mazzella, Gamal Rashed, Nicole Evanek, Brent Slaker

In the past decade, there have been several incidents of massive ground collapses in underground stone mines in the eastern United States. Fortunately, these events have not resulted in any fatalities. However, three mine workers were injured and many others were at risk due to the hazard from the fall of ground and/or the airblast associated with these massive collapses. The National Institute for Occupational Safety and Health (NIOSH) initiated a project to better understand the causes of these massive ground collapses to help prevent their future occurrence. The main objective of this study is to investigate the main factor(s)that initiated one of these massive ground collapses. The authors relied on several tools including three-dimensional (3-D) LiDAR scans for the surface subsidence feature and the underground mine workings around the collapsed area, borescope data at multiple locations around the collapse, S-Pillar analysis for average and unfavorable conditions, and numerical models. The emphasis has been placed on the impact of the following limestone pillar stability parameters: pillar width-to-height (W/H) ratio, benching, the existence of karst features, weak roof, and geological discontinuities. 3-D LiDAR scans were utilized to show the shape and the extent of karst cavities observed within stable pillars around the perimeter of the collapsed area. Together, this coupling of field measurements and observations and modeled systems suggests the potential causes of the collapse.

Jul 1, 2023