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By Ramesh Kumar Chauhan, Umakant Sharma, Manwendra Pratap Singh, Ashok Kumar Chadha

The power sector in India has an installed capacity of 267.637 GW as on March 2015. Out of this total installed capacity, the hydropower sector contributes 41,267.43 MW as renewable energy source. The development of various proposed hydropower schemes in India are primarily concentrated in mountainous regions of Himalaya and often involves underground tunnelling. Underground tunnelling of considerable magnitude is generally associated with adverse geological conditions and associated geological surprises. The main objective in case of Tunnels constructed especially for hydro projects, which carry enormous quantum of water is that, it should not leak. Moreover, the tunnels which are part of water conductor system should resist the inflow of water from the surrounding ground in order to avoid draining of natural water sources and lowering of existing groundwater levels. Lowering of water table may result in subsidence and damage to existing surface structures, loss of capacity of drinking water schemes and in some cases even catastrophic sliding of landmass. Grouting and pre-grouting in tunnels serve three different purposes i.e., Stabilization, Strengthening and sealing of the rock mass around tunnels to avoid leakage of water from tunnels. In present paper, results of grouting methodology adopted during final construction stage of RHEP (412 MW) along with the introspection of Water Pressure Tests conducted for determination of the efficacy of grouting were elaborately presented. The process, of contact and consolidation grouting which is respectively followed by water pressure tests along entire reach of HRT (15.177 Km long) were also addressed in detail. Pertaining to the results of water percolation tests (before and after consolidation grouting), it was also attempted to categorize the behaviour of different rock mass classes/ conditions in reference to different quantum of grout intake and corresponding Lugeon values. Importance of planned and dedicated successful grouting procedure adopted in hydropower project at RHEP is also emphasized.

Jan 1, 2016

By R. Zhang, S. Azam, S. Liu, J. H. Golbeck, V. Kurashov, S. Bhattacharyya

Free radicals (FRs) present in coal dust directly influence the interaction behavior between lung cells and dust particles. FRs are atoms or groups containing unpaired electrons, with strong chemical reactivity and a short lifespan. FRs which are quite persistent in natural environments, termed environmentally persistent free radicals (EPFRs), have recently received much attention as new environmentally hazardous substances. EPFRs present on coal dust serves as an active intermediary to catalyze reactive oxygen species (ROS) production by oxygen molecules endangering mine workers’ health. Many EPFR species may be bonded to the particle surface or trapped within the particle during coalification and can be modified with progressive size reduction through cutting at the mining face or crushing/pulverization in the plant. This study measured EPFRs for lignite, sub-bituminous, and anthracite coal dust at various sizes. We especially focused on EPFRs for submicron coal dust prepared by cryogenic methods. The outcome of this study will directly improve the free radical-dependent toxicity quantification and ultimately contribute to the size-dependent coal dust toxicity quantification.

Mar 2, 2022

By Donald G. Foot, Jeffrey D. Mckay

Flotation columns have been readily accepted for use in most sulfide flotation plants: however, recently columns are being used in many other areas. Recent improvements in design methodologies have overcome many operating problems and led to improvements in metallurgy. In addition. Physical improvements in column design have simplified their operation while leading to better control. The Turbo-Air External Bubble Generator has provided a method for bubble size control and variation in air holdup and carrying capacity. These have enabled commercial operations to improve grades and recoveries by optimizing performance.

Jan 1, 1989

By S. K. Kawatra

Although temperature is known to have a substantial effect on many processes, this parameter has been widely dismissed as insignificant for mineral comminution. For this reason, temperature effects on grinding have largely escaped notice. However, it has been observed that processing plants which are subjected to large seasonal temperature variations show a change in performance which appears to be due to changing feed temperatures. The general effect is an increase of the specific energy consumption as the temperature decreases. In autogenous mills, an increased rate of production of critical-size material has also been observed. This is due, at least in part, to changing rheological conditions in the mill, with the slurry viscosity increasing markedly at low temperatures. Mechanical changes in the rock with temperature, such as increased brittle fracture, is also responsible for a portion of the observed seasonal effect, and may account for this phenomenon being observed only in certain plants.

Jan 1, 1989

By M. Ghoreychi, M. Fauueau, P. Lebitou, P. Berest

A brief study of the history of gas caverns in salt formations enables us to consider creep mechanism in a cavity as a phenomenon of dissymmetrical deformation. Among different parameters affecting such a phenomenon, gravity forces, especially in large caverns, seem to be responsible for important bottom heaves as compared to roof releases. This fact is demonstrated here by means of certain theoretical considerations concerning elasto-viscoplastic constitutive laws relevant to rocksalt rheological behavior.

Jan 1, 1986

By Sheldon P. Wimpfen

Sand and gravel has been, and will continue to be, our principal construction material. Most of us are familiar with the patterns of past growth. Today we will examine the present status of this vital industry. We shall also attempt to look into the future to see where it is going and to evaluate the constraints that are being imposed. Natural aggregates are among the lowest in value of all bulk industrial minerals. From the processing point of view, sand and gravel production is relatively simple since the products are sized materials obtained from a deposit of satisfactory physical soundness. They can be used either loose or bound to provide bulk, strength, or protection. One of the main uses of coarse aggregate is in concrete as a filling material. As a general rule, the coarse aggregate constitutes about three-quarters of the volume of concrete. The other main use for aggregate is as a roadstone or roadbase to provide protective and stabilizing bulk beneath the road surface. Also it is used in a mixture with petroleum products as the wearing course on top. The sand and gravel industry is geographically widespread. In general, the output of operations is directly proportional to the amount of construction in any area. A wide variety of other aggregates compete with sand and gravel, including crushed stone, blast-furnace slag, clinker, and artificial and natural lightweight materials.

Jan 1, 1972

By B. M. Moudgill, T. V. Vasudevan

Marine sedimentary deposits account for 80% and igneous deposits 17% of the total world output of phosphate rock. The phosphate mineral is well crystallized and exhibits a greater floatability in the igneous deposits than the sedimentary ores. Both silicates and carbonates contribute the major gangue associated with the sedimentary ores. Although removal of silica from sedimentary phosphates by froth flotation has been in practice for several decades, with the depletion of high-grade reserves, new attempts are being made to improve the efficiency of current silica removal technology and to develop new processes for beneficiation of phosphate ores associated with the carbonate gangue. In this paper, recent developments in processing of sedimentary phosphate ores containing carbonate and silica gangue are discussed.

Jan 1, 1987

By Dale R. Ralston, Roy E. Williams, Gerry V. Winter, George L. Bloomsburg

Jan 1, 1986

By A. J. Hudson, M. R. Yenchek

Faulty insulators on mine trolley/track haulageways may allow leakage of currents into the mine roof, which may ultimately result in the combustion of the roof material. The National Institute for Occupa¬tional Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), devised a passive means to detect overheating insulators on di¬rect current systems. The detector consists of a spring- loaded car¬tridge that ejects a reflective streamer of white Teflon tape when subjected to elevated temperatures. The cartridge assembly can easily be installed over the outer metallic shell of an existing trolley line insu¬lator. If an insulator overheats due to ground leakage currents, the vis¬ible streamer alerts mine personnel traveling on the haulageway.

Jan 1, 2000

The implementation of NAFTA in January 1994 was expected to have small but beneficial effects on the Mexican economy, mostly through increased investments. Mexico's mining industry was especially likely to benefit, as mineral investment funds would be diverted to the now safer Mexico and away from similarly endowed but more risky Latin American mineral economies. The results during the past two years have shown that it is government and macroeconomic factors that influence investment flows, rather than the fine tuning of trade flows through so called 'free-trade" agreements.

Jan 1, 1997

By Hugh W. Rimmer

The design of comminution circuits and the evaluation of alternatives should be based on state-of-the-art equipment and appropriate design criteria - considerations that are often neglected by today's designers. This paper critically reviews common circuit designs, evaluates various alternatives for difficult-to-treat ores, and discusses the factors that should be considered when developing new plant designs or auditing existing plant performance. Data obtained from laboratory, pilot and plant-scale test work on a wide range of ores and circuits are used to justify the author's conclusions.

Jan 1, 1995

By Veliko Kertikov

Complicated processes of heat exchange and evaporation, leading to changes in the temperature and humidity of the ventilating air flow, take place during the driving of headings. In the case when virgin rock temperature is high, the increase in air temperature and humidity is significant. This causes a deterioration of climatic conditions in the headings. Procedures for predicting the changes in air temperature and humidity are discussed, together with appropriate calculations and computer programmes. Predicted results for example scenarios are used as a background for the selection of approaches and means to improve the climatic conditions in a dead-end heading using auxiliary ventilation.

Jan 1, 1997

By H. Lind

The consumption rate of Estonian oil shale increases due to the growing rate of exported oil-shale oil. Estonian oil shale active resources in working mines are predicted until the year of 2025 when the consumption rate stays at the level of 12 tons per year. If the consumption rate stays at that level, new mines should be opened after 20 years, if the rate increases new mines should be opened even earlier. The predicted active resources in Estonian oil shale deposits are calculated for 60 years, based on the parameters of the power station technicoeconomics. As a result, there is a need to open new mines. One of the potential areas for surface mine is the Tammiku-Kose prospect area (Rheinbaun Engineering, 1996).

Jan 1, 2006

By G. V. Krishna Roa, G. Vijaya Kumar

One of the main objectives while planning ventilation systems for mines with multiple fans is minimization of the total airpower consumption of the mine. Solution of this problem by conventional ventilation network analysis programs is tedious and time consuming, and may not yield optimum results in all the cases. The paper presents an algorithm for solving multiple fan networks by finding optimum combination of fan operating points for required airflow distribution in the ventilation system.

Jan 1, 1995

By Phillip J. Maddex

During the last 10 years there have been many new developments in transport and handling equipment. Important technical and economic developments that can be used to reduce costs are; new terminal and materials handling concepts large river tows - 40,000 tons and 9000 hp towboats slurry loading and unloading of ocean vessels long distance pipelining of solids development of the shuttle train (unit train) large ocean barges ? 25,000+ tons ? pushed & towed 150,000 ton self-unloading super tankers - 300,000+ tons container shipping Some of these developments have been discussed at SME meetings in papers describing the transportation of minerals from new mines. But, only a few papers described improved transportation from older operations. Since transportation is a major part of the delivered cost for minerals, the economic benefits to be gained by putting new transportation developments to work are very substantial. Frequently good transportation planning and management makes the difference between a marginal ore body and a very profitable one.

Jan 1, 1972

By R. W. Hagemeyer

By way of background. it is important to keep in mind that the information presented in this paper relates specifically to synthetically produced precipitated calcium carbonate (PCC) fillers. Natural calcium carbonate fillers manufactured by grinding limestone, marble and chalk, though having similar chemical and physical analyses to PCCs, normally contribute somewhat different performance properties in paint, paper and polymer systems. Many factors have been cited and numerous theories have been proposed for the observed differences. Particle size parameters, surface chemistry and particle morphology are the items most frequently mentioned. A discussion of this subject is beyond the scope of this paper.

Jan 1, 1989

By Gordon C. Gutrath

Queenstake Resources Ltd. has been exploring and mining alluvial gold deposits in the Yukon Territory and British Columbia since 1980. The five mines in production produced, in 1987, a total of 13,222 ounces. This paper will briefly review Queenstake's exploration program, property descriptions and mining methods, environmental concerns and a comparison of costs. (Sueenstake has been successful in developing a cash flow base from these operations that provide the capital for the acquisition and exploration of new, and hopefully, larger scale gold producers. NOTE: The historic alluvial mining unit of ounces per cubic yard and English units of measurement have been used throughout this paper. Dollars are Canadian unless otherwise noted.

Jan 1, 1988

By G. W. Heunisch

The properties of Neutra-Fix® and Neutra-Ment®, two new lime substitutes for treating acid mine drainage (AMD), have been compared with lime and Allcament®, two products presently in use for AMD treatment. The two new products are basically dolomitic byproducts and produce sludges that are more compact than those from lime. Sludge settling rates are faster than lime with iron concentrations after 24 hours that comply with Environmental Protection Agency (EPA) regulations. Material utilization and optimum pH are reported.

Jan 1, 1988

By T. R. C. Aston

Extensive undersea coal reserves, identified in the offshore portion of the Sydney coalfield, Nova Scotia, have resulted in the implementation of a multi-year research program to develop site specific guidelines for the undersea longwall mining operations. At present, uncertainty exists regarding the applicability of the current undersea mining guidelines. Preliminary studies have revealed four potential schemes for monitoring seafloor longwall subsidence profiles: seasurface, subsea, geophysics, and direct monitoring. However, further work has indicated that the use of marine geophysical techniques may be the most effective method of identifying and evaluating seafloor subsidence profiles by comparing pre- and post-mining seafloor topographies.

Jan 1, 1990

By V. Srajer

Several optimization approaches used by the Canadian mining industry were used to investigate surface coal mining operations in Canada. A computer program was applied to optimize truck/shovel systems and for various analyses. The analyses of eight western Canadian coal mines included investigation of fleet imbalance, under- and over trucking, development of the criteria for automated truck control, comparison study of various haulers and loaders, haulage layout, driving conditions, machine performance, servicing and maintenance policies, etc. Each property investigated supplied background information for the study and cooperated in optimization studies. The truck/shovel system optimization study is demonstrated as a test case to outline procedures and step-by-step instruction for similar applications.

Jan 1, 1989