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By Kurt Bryan, O&apos

The crushing and milling of mineral bearing ores can now be accomplished more efficiently through the application of WaterFlush technology. WaterFlush crushing has reduced capital and operating costs for the processing of a lead/zinc ore in South America. Similar benefits can be expected in the processing of other ores. WF cone crushers offer improved performance over conventional cone crushers. Performance improvements include the ability to crush wet and sticky ores, increased reduction ratios and greater production of flakier and finer products.

Jan 1, 1989

By Alexander Filimonov, Yury Bloshteyn

The development of a high-efficiency control system for mine ventilation is a complicated scientific and engineering problem. As a result of high-costs and difficult conditions involved in experiments for the development and investigation of mine ventilation systems, simulation is a critical task in cost reduction and productivity. The paper presents the description of a universal simulation model for controlled aerodynamic processes in an Underground ventilation Network (UVN). The high-efficiency programming tool to design and investigate mine ventilation control systems (MVCS) is also suggested.

Jan 1, 1991

By H. Zhu, A. G. Journel

Qualitative and interpretive information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging, and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system provides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data. A case study using a large reference database is presented; the indicator conditioned estimates have a smaller conditional bias and a smaller error variance than the ordinary kriging estimates. The results also showed that the indicator conditioned estimator is more efficient for selection in mining.

Jan 1, 1990

By Leslie C. Thompson

The heap leach process used for recovering gold from oxide and sulfide ores is operated as a closed circuit system in which the cyanide process solutions are continuously recy­cled. In a well-designed operation there is little or no dis­charge of cyanide to the environment. Spent leached ore residues are water washed to remove most of the trace cyan­ides and precious metals remaining after completion of cyan­ide leaching. After the washing step, small amounts of cyanide, metal-cyanide complexes and nitrates remain in the residue. Most of the cyanide and nitrate residue constituents exist in the pore water of the spent ore rather than in the solid mineral fraction. More than 90% of the complexed cyanides in a freshly washed ore residue are present as free cyanide or weakly complexed metal-cyanides. Natural volatilization and decom­position rapidly remove most of these easily dissociable cyanides from the spent ore. Only the stable, strongly com­plexed metal-cyanides, such as gold, cobalt or the ferrocyan­ides and other constituents such as nitrates have a long term persistence in the spent ore residue (Towill et al). Despite washing and natural removal mechanisms, spent ore has the potential to act as a point source of com­plexed cyanides and nitrates for soil and groundwater con­tamination if inadequately contained (Huiatt et al). The groundwater contamination is caused by the leaching of the soluble cyanide compounds and nitrates from the pore water of the residue.

Jan 1, 1990

By K Martin, C. J. Nelsen, J. L. Schutz, S. R. Maynard

Investigations in the Ortiz Mountains have revealed the relationship of igneous activity and gold mineralization to the Tijeras-Canoncito Fault System (TCFS). The northeast-trending TCFS passes through the southeastern part of the Ortiz Mountains where its principal structure is the asymmetric Ortiz Graben. Several fault blocks, containing up to 305 m (1000 ft ) of Eocene Galisteo Formation, comprise the graben that has up to 1220 and 610 m (4000 and 2000 ft) of stratigraphic separation on its southeast and northwest sides, respectively. Intrusions in the Ortiz Mountains can be subdivided into two petrochemical types: an older calcalkaline suite and a younger alkaline suite. The calc-alkaline rocks are characterized by extensive sill, dike, and laccolithic bodies of latite-andesite intrusives and at least one younger (?) granodiorite stock at Candelaria Mountain. The alkaline rocks consist of a large nepheline-bearing augite-monzonite stock, a latite-porphyry hypabyssal plug, the Ortiz diatreme (vent breccia), and trachytic-latite dikes radial to the diatreme. K-Ar age determinations suggest the older suite to be 34 +/-2.2 million years while the younger alkaline rocks range from about 30 to 26 million years. Gold mineralization in the Ortiz Mountains occurs in five distinct environments: brecciapipes, skarns, veins, porphyry-like stockworks, and placers. Lode mineralization is associated with the alkaline suite of intrusive rocks postdating the Ortiz diatreme and predating most of the trachytic-latite radial dikes.

Jan 1, 1991

By James T. Tanner

Mica is a generic term that applies to a group of complex aluminosilicate minerals that have a sheet or plate-like structure and with different chemical compositions and physical properties. All micas form flat six-sided monoclinic crystals with remarkable cleavage parallel to the direction of the large surfaces, which permits them to be split into optically flat films; as thin as 1µm in thickness in some cases (Rajgarhia, 1987). Some micas are more easily split than others. For example, muscovite mica found in pegmatites is more easily split into thin films than is phlogopite. Mica found in mica schist is not as easily delaminated as mica found in weathered pegmatites. According to Dawson (1 949), the commercially important mica minerals are: Muscovite-potassium mica (colorless to pale green and ruby) Biotite-magnesium-iron mica (dark brown to black) Phlogopite-magnesium mica (pale yellow to dark brown) Vermiculite-hydrated biotite or magnesium-iron-mica (bronze yellow flakes) Lepidolite-potassium-lithium mica (pale lilac to deep purple) Some micas of less importance are: Zinnwaldite-lithium-iron mica (gray to smoky brown) Roscoelite-vanadium-potassium-magnesium mica (various shades of green and brown) Mica, principally muscovite, is widely used for industrial applications because of its exceptional physical, chemical, electrical, thermal, and mechanical properties (Table 1). Phlogopite and vermiculite follow muscovite in importance. Biotite finds very little commercial application at the present time. Commercially, mica is used in a number of forms. These forms and their description follow: Sheet mica refers to books of mica either mined from hard rock (pegmatites) or from loosely consolidated clayey material formed from the weathering of pegmatites and alaskites. These books can be readily split into thin film or splittings with specific thicknesses ranging from 0.0031 to 0.10 mm (Davis, 1985). Quality sheet mica is graded into 10 quality classifications (Tables 2 and 3). Books of mica that are flawed with excess inclusions, cracks, or folds (A mica) are called scrap mica and are either ground into commercial products by a dry or wet process. Built-up mica was developed in 1894 as a result of the cost and scarcity of sheet mica, and because many satisfactory electrical parts could be made from it (Preston, 1971). This type mica is formed by layering pieces of mica splittings upon one another and binding them together with inorganic or organic binders. These sheets are then pressed together under high temperature. Mica for this process is produced from pieces of sheet mica too small to be punched into electrical parts (Davis, 1985). Reconstituted mica is mica paper produced by forming a mat of very thin delaminated flakes of scrap mica. This mat is usually impregnated with an organic binder, but is also available unimpregnated. It is dried at 110°C. The mica for this process is either produced from the trimmings of a sheet mica operation or from blocks of A type mica (Davis, 1985, Chapman, 1983). Ground mica constitutes by far the largest use of mica, both quantitatively and application wise. It is produced by grinding and sizing scrap mica (also mica concentrate) obtained from five sources, 1) trimming from sheet mica, 2) A type mica blocks, 3) as a byproduct of spodumene and feldspar mining, 4) weathered pegmatites and alaskites, and 5) metamorphic schists. Synthetic mica is produced by crystal growth in a slowly cooled melt of accurately proportioned chemical oxides. Extended cooling times at a specific viscosity result in larger crystals. Many different micas have been formed by this process; however, fluorophlogopite is the most common.

Jan 1, 1994

By R. Debkowski

Mining methods used to protect the workings in underground salt mines against the destructive activity of natural factors are presented in this paper. Major hazards and methods of elimination of their impact on the stability of workings, were determined. Old and modern technical means and technologies used for protection and preservation of the selected most interesting sites were characterized. The results of surveys and studies allowed proposing the change of mine structure i.e. dividing it into monumental and not-monumental part, which should improve execution of necessary protective works.

Jan 1, 2006

By A. Papandreou

Industrial wastes nowadays constitute one of the most serious threats for the future of our planet. Researchers around the world have very often proposed many kind of solutions in the management problem of industrial effluents. However in most cases suggested solutions are either too expensive to be applied in industrial scale, or they just transfer the problem (e.g. precipitation creates dangerous sludge) and so they create an even greater problem and threat. In the present study the exploitation of valuable hydraulic and adsorption properties of fly ash is studied. Fly ash can easily and cheaply be shaped into stable pellets. After ageing for a sort period of time, these structures can be used as adsorbents for the removal of heavy metals from industrial effluents. Experiments in aqueous solutions have shown excellent adsorption behavior concerning the removal of cadmium, copper, lead, chromium (III) and zinc. The advantage of this technology, except low cost, is that after saturation the pellets can be easily removed from the liquid phase and stabilized in concrete structures without any problem of desorption or leaching. Moreover in these structures a significant amount of cement in the concrete can be replaced by raw fly ash. (Ashcrete as it is called). The utilization of an industrial byproduct as fly ash in the form of pellets as adsorption means and their stabilization with concrete (or ashcrete) combines the useful properties of a solid waste in the treatment of liquid effluents and constitutes a green low cost technology.

Jan 1, 2006

By B. Govindarajan, T. C. Rao, M. Vanangamudi

The results obtained from hatch, flotation experiments on two coals were used to develop relationships between the recoveries of water and solids into the concentrate. When the recovery of non-ash material (RN) for any size fraction is plotted against a parameter X, defined as [x _ Amount of (W) recovered x Collector dosage (C)in the concentrate (cc)(kg/t)] a single "non-ash recovery curve" is obtained. Non-ash recovery curves thus obtained from different size fractions are used to get a unique "modified non-ash recovery curve" for a given coal, using the reduced efficiency curve concept. Similar observations have been noted in the case of recovery of ash material (RA) also. The amount of water recovered into the concentrate is plotted against a parameter "Water Recovery Factor (WRF)," defined as [WRF = T.F.(1+C)] where T is time (in sec) and F is frother dosage (in kg/t). Plotted in this form a characteristic water recovery curve, for a given coal is obtained that may be defined by the following equation: [W4=W_(1 pWRF-e] The above relationships have been verified against the experimental results obtained from three more coals and are found to give satisfactory predicted values.

Jan 1, 1992

By J. M. Mutmansky, Aiping Wang

This paper outlines the patterns of methane emission in both longwall and room-and-pillar operations and discusses the effects that these patterns have on the decision as to whether the methane is most economically handled by ventilation alone or by means of a methane-drainage system in addition to ventilation. The costs of handling the methane in the ventilation system and the costs of implementing the methane-drainage system are discussed, as well as the costs related to the production of coal. The important issues of production slowdowns and gasouts are also discussed, as well as the proper response of mine management to such a situation. Suggestions concerning the keeping of production records related to methane problems are made, and the justification for more intensive economic analysis of coalbed methane extraction and utilization is discussed

Jan 1, 2000

By Thomas J. Regan

The first stage of the Massachusetts Bay Transportation Authority's Red Line Extension Northwest, is a two-track rapid transit extension from Harvard Square in Cambridge, through three stations, to the Alewife Station/Garage complex in North Cambridge. The extension, about 5.0 km. (3.1 miles) in length, is entirely in tunnel, with the Alewife Station/Garage complex and adjacent line sections of tunnel constructed by cut-and-cover methods. The Station/Garage complex, just west of Alewife Brook Parkway, is in an area underlain by deep deposits of very soft highly sensitive clays. It is proposed to construct the station and adjacent tunnel sections by the slurry trench method, using the slurry wall as the permanent structural wall of the station and tunnel. The unusual nature of the underlying clay and its very high sensitivity raised questions concerning the feasibility of the proposed construction. Since research failed to reveal any construction precedent for the specific conditions encountered, a test section was undertaken to determine construction problems, resolve uncertainties, and to establish acceptable parameters for the construction of the slurry walls. PROJECT ORGANIZATION Sverdrup & Parcel as tunnel and transit systems consultant for the Red Line Extension-Davis Square to Alewife had overall responsibility for determining program objectives, project management and test implementation.

Jan 1, 1979

By Arnaud Colson

1 Good morning ladies and gentlemen. Let me first thank you for welcoming me to this international congress. I?ll have the pleasure to explain to you how the Lafarge group works on its quarry rehabilitation. I will deal with the way quarry rehabilitation has affected all branches of the group trough a global approach. 2 Quarries often are a subject of controversy dividing those are for and those who are against. My purpose is rather to examine where factors of progress lay and how in a quarry such as Lafarge we can include quarry rehabilitation, which is so fundamental dimension of our process. 3 - 4 As these two photos of French quarry show taking into account the environment in the quarry industry has been a recent preoccupation. In less than a century rehabilitation has a dramatically evolved in a positive way. Consequently our group integrate an ecological dimension in its activity. It?s an ethical question as well as a personal view of our role as a responsible industrial group. 5 My presentation is built around 4 points: I?ll begin by explaining why it?s our responsibility to rehabilitate quarries. I?ll go on to fill you in on the method of the project. After that I?ll outline the expected results. Finally I?ll talk about the rest of the project and the way we can ensure this know how.

Jan 1, 2002

By G. E. Bandelis

In this paper, solid bed erosion processes and the mechanisms involved when a two-phase liquid-solid mixture flows over a bed of solids in a horizontal annulus are analyzed. There are few such studies available with some authors arguing that the flow rate for erosion is always less than the flow rate for the suspension of solid particles thus necessitating further study and analysis of such phenomena. Tests were run to determine the mechanism of erosion and the erosion velocities of the solid bed formed in a concentric annulus for three flu-ids, water, a low concentration water solution of Carboxyl-methyl-cellulose (CMC), which behaved as a Newtonian fluid and a higher concentration CMC water solution which behaved as a power law fluid. Glass spheres of 2 mm nominal diameter were used as solids. The flow rate at which erosion occurred together with the mechanism of bed erosion were determined visually, while the whole process was video recorded. Our tests indicated different erosion mechanisms and different erosion velocities for the three tested liquids, with the liquid viscosity playing a major role. The first mechanism, observed for water flow, gives erosion from the front of the bed while the second mechanism, observed for the flow of the two viscous fluids, gives erosion from the top of the bed. The role of each of the parameters to erosion is investigated, whether it is turbulent flow with the turbulent fluctuations being more capable to remove the solids from the formed bed or whether it is liquid viscosity, which results in the hydrodynamic shearing force. The results demonstrate that liquid viscosity plays a role in the erosion mechanism and yields different erosion velocities of the solid bed hence, it should be taken into account when modeling flow pattern transitions for solid-liquid flows. Prior studies have not identified this and it could be the reason of the disagreement between theoretical models and experimental and field data.

Jan 1, 2006

By William J. Francart

In 2003, MSHA initiated a survey of the 11 Coal Mine Safety and Health Districts to develop a database for the implementation of Atmospheric Monitoring Systems (AMS) in underground coal mines. Mine operators continue to realize the benefits of improved fire detection capabilities, as the number of mines using the systems, as well as the percentage of mines, continues to increase. Fire detection data and new technology implemented in underground coal mines is discussed as well as regulatory compliance, diesel exhaust considerations and hydrogen interference in carbon monoxide detection.

Jan 1, 2005

By R. D. Lama

Coal mining is one of the major sources of methane release to the atmosphere by human industrial activities and is believed to contribute to -30% of the total methane emissions from industrial activities. In 1993, world saleable black coal production, attained almost 3.5 billion tonnes from which around 65% was produced underground. Coal in underground mines can contain high quantities of methane and some deep coal seams have methane content as high as 50 cubic meters per tonne of coal. Gas is re- leased during coal mining from the mined seam and in a higher degree from the neighboring unmined seams and gas bearing strata which are fractured as mining advances. This paper de- scribes a study which was undertaken to estimate the extent of methane emissions from coal mining in the world. Measured emission related data were collected from most underground coal producing countries in the world. The data included methane flows in the ventilation system, methane flows in gas drainage system, in-situ gas content, methane utilization and coal production. More comprehensive data were collected from a range of gassy and non-gassy Australian mines. Residual gas content of samples from run of mine were also measured. Using the Australian data, mathematical expressions were established to evaluate methane emissions as a function of coal production and in-situ gas content for other mines. These emission models were then used to evaluate the emissions for the countries or coal basins without measured emission data. Trends in methane emissions from underground mining for the year 2000 and beyond were also estimated.

Jan 1, 1997

By George Munro

Heavy water inflows of up to 1350 1/sec in the 19.6 km Moawhango-Tongariro Tunnel section of the Tongariro Power Development Scheme in New Zealand gave rise to severe operating problems, particularly in the equipment stripping stage when pumping installations had to be removed. Due to the necessity to commence stripping from the upstream side the contractors. Codelfa-Cogefar (NZ) Limited, took the decision to install a steel bulkhead some 5000m in from the lower. Tongariro, portal. The article lists the considerations taken in the placement of the bulkhead, and gives details of its design, installation and final removal. A brief description of the geology of the tunnel. together with water flow sources, rates and pressures is also included.

Jan 1, 1981

By Yu Qixiang, Wu Yanyun, Guo Junfeng

The experience of mining coal and gas outburstprone coal seams shows that the degree of outburst danger in various coal seams and even at different parts of the same seam are quite different, and that to deal with them respectively in different ways will not noly be significant to safety but bring us remarkable economical profit, Based on the statistical data,including elght static and dynamic factors, gathered from coal and gas outburst spots at Nantong colliery in Chong Qing district of China, this paper has partitioned the degree of outburst danger of the No. 5 seam there by means of Fuzzy Clustering method. Because in the evaluation multiple indices have been considered, the result of partitioning is identical to practice and more efficient in applications.

Jan 1, 1991

By James C. Puckett

The mining industry finds itself in the middle, between the need to increase production of our energy resources and the necessity of minimizing the environmental impact. Using the recent past as a guide, the mine planning engineer's function will continue to increase as further coal quality constraints are made upon the production staff. The engineer will need to make use of all available tools in order to provide timely answers to the complex "what if" questions that arise. This need to consider many alternatives is bringing about a rapidly increasing acceptance and utilization of the computer. In the areas of data handling, mineralization modeling, and production simulation, the computer is an effective tool for the mine planning engineer. Described herein is a coal data storage and analysis system developed to provide timely answers to the "what if" questions for an operating strip coal mine in Montana. The characteristics of a computerized coal data base and coal quality planning system are outlined in this chapter. The system has been developed for use at a particular coal mine; however, it has applicability to coal mines in general. Fig. 1 is a flow chart showing the functional relationships of the system. There are three main file types: the drill-hole data base, the boundary file, and the zone file. The purposes for which each file is organized are illustrated on the flow chart.

Jan 1, 1979

By J. W. Merks

Spreadsheet software is used to convert test results for drill core samples into borehole statistics such as volumes and masses of in-situ ore, metal contents and variances of metal contents. The properties of variances and the sampling variogram play a pivotal role, The additive of property of variances gives a sound scientific basis to the calculation of confidence limits for metal contents and grades as a measure of the risks associated with estimating reserves and resources.

Jan 1, 2000

By J. A. Herbst

Grinding circuits employed in mineral processing operations are designed to produce feed materials for beneficiation steps such as flotation and magnetic separation, which are sufficiently fine to achieve good liberation of valuable minerals from gangue without over- grinding. In many respects, grinding is the most important unit operation in a mineral processing plant. If adequate liberation is not achieved during grinding, subsequent separation steps will yield low metallurgical recoveries and/or product grades. Grinding energy requirements and operating costs typically exceed 50% of the total expenditures of the entire plant. Because grinding is an inherently energy intensive process and grinding circuit capital and operating costs are high, it is essential that such circuits be run as efficiently as possible. In- creased efficiency in grinding usually translates to a decrease in the energy required to produce a metric ton (short ton) of product size material. It is generally accepted in the mineral industry that efficient grinding circuit performance can not be achieved without the use of some form of automatic control. This is true because all circuits are subject to random disturbances which, if left unchecked, will upset circuit performance and rob a plant of productivity. Such disturbances arise from a variety of sources including natural variations in ore characteristics (particularly hardness changes), uncontrolled water additions, feed-rate upsets, changes in crusher performance, and mechanical upsets such as blockages in pumps and classifiers. Many of these disturbances occur with a frequency which is too high for an operator to detect and react to efficiently. Disturbances which occur on a time scale of several minutes up to several hours can be effectively dealt with using automatic control.

Jan 1, 1979