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By Y. T. M. Ocsa, V. O. Tenorio

This research is the result of a geotechnical study carried out in a natural slope in an Open Pit mine in Southern Peru, highlighting earthquakes as an important cause of instability within the case study presented. This leads to analyze the stability of a slope, according to the safety factor and thus consider a future construction in its environment according to the identified requirements. There are known disasters at national and international level that involve human lives because of the lack of analysis of slope stability conditions, which based on the results will allow to control and to take adequate corrective measures. These mass movements are classified whether they are soils or rocks, considering the mechanism and type of rupture, as well as the presence of water, the speed and magnitude of the movement. The movement problems are due to factors of inherent nature and constitute a reason to perform a calculation study to analyze and estimate the safety factor of each of the evaluated cases

Mar 2, 2022

By R. V. Ramani, R. Bhaskar

The results of an experimental and theoretical research study into the spatial and temporal behavior of dust in mine airways is summarized. Experiments were performed in mine airways under both controlled and normal operating conditions. The controlled experiments included the documentation of the concentration and deposition patterns for two types of dust under three different velocities. Real-time dust concentration data were obtained using real-time aero- sol monitors (RAM-I) to determine the dispersion coefficient in a mine airway. On the theoretical font, a convection diffusion model of the dust flow phenomenon in mine airways was developed considering dominant mechanisms affecting dust transport and deposition in mine airways. Mechanisms modeled include turbulent and gravitational deposition, coagulation, and dispersion. In this paper, comparative analyses of results (8 the controlled experiments with the predictions of the mathematical model are presented. In addition to the overall validity, the adequacy of the individual components of the model, such as deposition in the total and respirable range, and dispersion are examined in light of the experimental observations. The experimental data from controlled experiments compared more favorably with model predicted results for similar conditions as opposed to the comparative analysis results for in-mine experiments. Specifically, the model predictions for an 800-m stretch of a mine airway reveal some significant differences from the behavior noticed in the mine. The deposition was lower than that predicted by the model. Consequently, concentrations were higher than those predicted by the model. The implications of these and other findings for further investigations are discussed in the paper.

Jan 1, 1987

By Werner T. Meyer

Technical modification of traditional zinc- and lead-based products is moving the metals into diversification is particularly apparent in two areas. The evolution of diverse types of heavy-duty vehicles that employ lead acid batteries. and The development of Galfan™ -- a zinc / 5% aluminum/mischmetal coating alloy designed to provided zinc-coated anti-corrosion protection in applications that are not well suited to traditional galvanizing. Because any product breakthrough must be accompanied by advancement and customer oriented thinking at every step in the chain of production and distribution, a concerted effort is required for market evolution to live up to its potential. As such, all those involved in the metals industries should not only track the progress made by technical and marketing innovations, they must participate as much as possible in their development and promotion.

Jan 1, 1986

By S. C. Bandis, N. Barton

During drilling of deep boreholes, local mechanical failures of the wellbore walls may occur due to the inability of the incompetent overburden and reservoir rocks to withstand drilling-induced changes of the stress environment. At present, borehole failure mechanisms in three-dimensional stress fields are poorly understood. Our experimental investigations based on 3-D physical models demonstrate the stabilizing effect of the intermediate principal stress. The latter may play a dominant role in maintaining the integrity of the stress relieving failure zone around the borehole. However, this will depend on the stress anisotropy, the angle of hole deviation and on the angle of internal friction. Our tests also indicate that the failure zone can accomodate high extensional strains. Finally, relations between the physical models and closed-form elasto-plastic solutions are discussed.

Jan 1, 1986

By Heiskanen K., Koivistoinen P.

A common belief is that autogenous grinding suits itself only to certain oretypes. It is shown that properly designed autogenous grinding can be used even with very difficult ores with energy consumptions which are equal or lower than obtained with rod-ball mill grinding. The basic feature in the design is the large port grate developed by Outokumpu. The scale-up of the mills can be done on the basis of the base mill concept. It enables to compare different mill sizes and types. Simple scale-up equations are presented based on actual mill data and experimental work.

Jan 1, 1992

By Y. A. Attia, D. K. Sengupta, H. A. Hamza

Increased recycling of waste paper has been emphasized in recent years in both the United States and Canada for environmental and economic reasons. Removal of ink particles from waste paper pulp is therefore necessary. One of the most promising methods for ink removal is froth flotation. This study investigated the feasibility of a simplified flotation scheme and found that about 90% to 92% ink removal can be achieved. Also, a 95% to 97% ink removal is achievable if a hydrophobic polymer is used ahead of the flotation stage. Clean paper pulp recovery was over 90%. The effects of pulping pH, flotation pH and concentrations of flotation and polymeric reagents are discussed in the paper.

Jan 1, 1995

By Robert Cooke

This paper shows how technology developed to analyse stabilised slurries can be applied to paste flows. The rheological characterisation of paste mixtures using the generalised yield pseudoplastic rheological model is described. It is noted that the slump test does not provide a complete rheological characterisation of a paste. Methods for calculating pipeline pressure gradients for laminar and turbulent flow are presented. The minimum pressure gradient is an important consideration to ensure that solids do not settle on the pipe invert. Important points to be considered for a pipe loop test programme are noted. The usefulness of the pseudo shear diagram for scaling pipe loop test measurements is demonstrated. Issues to be considered for the design of paste reticulation systems are discussed.

Jan 1, 2001

By George M. Potter

During the late 1960s the mining industry became interested in USBM's efforts to develop the gold-silver heap leaching process. In the last 10 years, successful commercial heap leaching applications increased. The process provides a relatively low-capital means of processing treatable ores with reasonable operating costs. Present gold and silver prices compared to capital and operating costs favor the continued growth of the heap leaching method. The heap leaching process is defined as the percolation leaching of relatively coarse gold-silver ore piled on an impervious surface. To date, dilute alkaline cyanide solution is the lixiviant of choice. Other leaching reagents such as thiourea and hypo have been suggested, although they are not currently used in heap leaching practice. Ores may he run-of-mine in size or crushed as fine as about 10 mm. Gold and silver-bearing so¬lutions draining from the heaps may be processed in activated carbon columns to recover the metals, followed by stripping and metal recovery, or treated by the Merrill-Crowe zinc dust precipitation method. All solutions are generally recycled to the leaching step, and the heap leaching system is relatively easy to control from an environmental viewpoint. One advantage of the heap leaching process is its flexibility. Plants may be very simple, comprising leaching of uncrushed ore on a locally-obtained clay-lined pad and shipment of gold and silver recovered in the form of loaded carbon or zinc precipitates; such a plant would have a relatively low capital investment. More elaborate plants for larger ore bodies may be planned to include crushing, cyclic pad use, and done gold-silver recovery. General planning is similar in each case. This article outlines some key factors in designing heap leaching operations and discusses how these factors are applied to develop a working operation. Since individual design requirements and local costs vary so much, only a few general comments on costs are included.

Jan 3, 1981

By A. R. Garcia, A. S. Myerson, W. R. Ernst, J. D. Carruthers, M. D. Franke, L. H. Hilzik

A method for removing nickel and vanadium contaminants from spent HDS catalysts involves pretreating the catalyst with H2S followed by extracting the metals with an acidic solution of ferric ion. The ferric ion solution alone removes significant amounts of active ingredients, cobalt and molybdenum; however, by pretreating with H2S, the extraction becomes more selective for removal of Ni and V.

Jan 1, 1988

By Gregg E. Korbin, Robin B. Dill, Corey T. Dare, Tor L. Brekke, Larry R. Myer

A study was conducted to develop a fundamental understanding of the relationship between the size of an advancing tunnel face, the rate of excavation, and stand-up time in squeezing ground. Stand-up time is defined as the time elapsed after excavation that an unsupported tunnel face will remain stable. Squeezing ground is argillaceous rock or soil that exhibits pronounced time dependence of deformation and strength properties in-situ. A case history study documented the nature, causes, and solutions of several cases of stand-up time problems observed in the field. Then, in the laboratory, a series of physical model tests were performed in which model tunnel size, face advance rate, material properties, and pressure (representing overburden pressure) were varied. Stand-up time was found to increase as advance rate was increased or tunnel size decreased. In addition, an influence of advance rate on the definition of stability ratios was established.

Jan 1, 1981

By William H. Sutherland

INTRODUCTION Coal workers' pneumoconiosis and sili- cosis are only two of several diseases which are rlassed as pneumoconiosis. These are respiratory diseases caused by dusts which are inhaled and accumulated in the lungs. The individual particles of dust cannot be seen by the human eye. They are so small that they escape the natural cleansing mechanism of the nose and air passages and make their way down to the terminal air sacs of the lung where they injure the cells and cause the formation of scar tissue. Consequently, if there is exposure to high concentrations of dust over a period of time - usually, a number of years - the amount of scar tissue increases and begins to impair breathing. As a result, the miner develops shortness of breath, coughing and wheezing ad-if exposure continues - this progresses to permanent disability and frequently to death. Death is often due to pulmonary heart disease, the effect of stress on the heart 2s it tries to compensate for the weakened lungs. Specifically, silicosis is an occupational lung disease caused by the accumulation of free silica (quartz) in the lungs. Silicosis is considered the most important form of pneumoconiosis, not only because of its seriousness as a respiratory crippler, but also because of the large number of workers who risk contracting it in a variety of occupations. Quartz is one of the most common substances of the earth's crust, estimated at about 60 percent. Silicosis has been found in coal, metal and granite miners, as well as in other workers, such as sandblasters and pottery makers. Silicosis is also known to predispose the lung to tuberculosis and to increase the chances that a worker will contract chronic bronchitis and emphysema. The seriousness of silicosis was tragically brought to public attention about 50 years ago. During 1932-34, workers were involved in digging a tunnel through rock at Gauley Bridge, West Virginia. While their exposure time was relatively short, they developed silicosis because of the high concentrations of quartz. By 1936, 476 workers had died of silicosis and about 1500 were believed to have the disease (Washington Post, 1982). It is difficult to tell how many coal miners have silicosis. Because x-rays and breathing function tests do not show the difference the type of pneumoconiosis is generally diagnosed by the miner's work history. For example, if a worker

Jan 1, 1986

By Ian S. Lowndes, Adrian T. J. Moll

With the current trends towards the concentration of extraction to fewer but higher production units in deeper seams, often of higher coal rank, the role of methane drainage ranges has become critical. As mines exploit seams at greater depth and more remote locations there has been a need to extend the lengths of methane drainage ranges and to increase the capacity of the surface pumps. This trend has highlighted the need to effectively simulate the operation of a methane drainage range in order to produce the optimum design and operation of a safe and economic system. This paper describes the development of such an analytical tool. The application of this computer model is illustrated by the analysis of the operation of the drainage system of an extensive mine. The paper concludes by considering the development of a [Knowlege Based or Decision Support System] which will assist the ventilation engineer in assessing the current performance of an existing drainage range and will suggest possible remedial modifications or design strategies which may improve the system performance. INTRODUCTION In order to maintain the general body methane levels to below predetermined statutory threshold limit values (TLV's) on major longwall production units there are, for a given production rate, two major complementary control devices which may be employed by the ventilation engineer. These are the combined design and application of a competent mine ventilation and methane drainage system. The methane drainage system should be designed so as to maximise the capture of the methane (firedamp) from the seam being mined and the strata gas liberated in the vicinity of the extraction zone from gas bearing seams or other reservoirs of gas situated at above or below the mining horizon. The design fresh air quantity entering the face should ensure that under normal operating conditions the methane entering in the vicinity of the face is rapidly dispersed and dilute to well below statutory TLV's. The drainage system must therefore be designed to maximise the capture of the methane gas liberated to minimise the amount of gas which enters the ventilation airstream. GAS DRAINAGE The inherent dangers of methane emissions in mine workings have been a problem of concern to mining engineers for many years. To alleviate the risk, methane drainage has been employed for some years to capture the gas before it becomes a hazard to the operation of the mine. The method of drainage employed will be dependent on a number of factors which include the longwall mining method and production cycle employed, the characteristics of the coal seam being extracted and those of the adjacent gas bearing strata. The location of the gas bearing potential of the over and underlying coal measures must be determined. The gas bearing

Jan 1, 1993

By Michael Michaylov

INTRODUCTUCTICN The coal seams at Bobov dol basin are highly prone to spontaneous combustion in Bulgaria. The risks of endogenous fires (SPONCOM) exist mainly in gob area. During the last 15 years three different technologies for preventing and fighting SPONCOM have been applied in underground mines of this basin: pulp from hard material and water, foam and inerting with nitrogen. On the basis of experimental application of these technologies as well as theoretical and experimental research a new technology - Foam Pulp Technology (FPT) was worked out. It is very effective in difficult to reach places in a gob. BACKGROUND AND THE NEED OF FPT Application of the three methods mentioned above showed advantages as well as some disadvantages, allowing determination of their effective application scope depending on geological and working conditions. Their advantages can be summarized as follows: - Foaming: high viscosity at low density, which allows forming a thick layer; good surfactant wetting properties; excellent effective cooling during evaporation in high temperature zones. - Pulping with mixture of solid particles (e.g., fly ash) and water from surface installation: easy to apply in a mine; low operational and energy costs due to gravity transport from the surface to the gob: good ecological results because the waste material is returned back underground. - Inerting with nitrogen: volumetric action which doesn't restrict the thickness of treated coal pile; easy to apply in a mine; controllable nitrogen delivery depending on fire hazard conditions. Main disadvantages of the same three methods are: - Foaming: rapid disintegration due to intrusion into heterogeneous and porous media and high costs due to the need of frequent large volume foam flows (short foam's life); - Pulping: inapplicable for coal piles with high thickness which is of great importance in the cases of seams with ununiform hypsometry (rapid and frequent changes in a seam configuration) and/or great volumes of coal or ore piles particularly heated to a high temperature; strong dependence on gob floor declination; water draining of the working face area which impedes the movement of supports and chain conveyor's. - Inerting: relatively high costs hardly depending on the rate of face advance (fig.1) in comparison with the other methods; it is difficult to ensure sufficient oxygen at the exit end of the face. This problem is crucial in faces with a high level of methane emissions; accelerating of the oxidation and spontaneous heating of the pile after turning off the nitrogen supply. Inerting should be applied again at higher capacity of nitrogen supply (fig.2) and what is more important, it shouldn't be

Jan 1, 1995

By Moudgil. B. M.

The amount of hydrophobic materials constituting the mineral froth strongly influences the froth viscosity. Higher truth viscosity, on the other hand, can retard the drainage of physically carried over, hydrophobic particles. In phosphate flotation tests, a direct correlation was observed between froth viscosity and recovery, and an inverse correlation existed between froth viscosity and grade. Phosphate flotation tests in the presence of a silica depressant indicated that higher froth viscosity is an effect rather than a cause for the presence of silica particles in the froth.

Jan 1, 1994

By J. Simmons, P. Ziemkiewicz

Acid-Base Accounting (ABA) is an analytical procedure that provides values to help assess the acid-producing and acid-neutralizing potential of overburden rocks prior to coal mining and other large-scale excavations. This procedure was developed by West Virginia University scientists during the 1960s. After the passage of laws requiring an assessment of surface mining on water quality, ABA became a preferred method to predict post-mining water quality,and permitting decisions for surface mines are largely based on thevalues determined by ABA. In order to predict the post-mining water quality, the amount of acid-producing rock is compared to the amount of acid-neutralizing rock, and a prediction of the water quality at the site (whether acid or alkaline) is obtained. We gathered geologic and geographic data for 56 mined sites in West Virginia, which allowed us to estimate total overburden amounts, and values for maximum potential acidity (MPA), neutralization potential (NP), net neutralization potential (NNP), and NP/MPA ratios for each site based on ABA. These values were correlated to post-mining water quality from springs or seeps on the mined property. Overburden mass was determined by three methods, with the method used by Pennsylvania researchers showing the most accurate results to actual overburden mass. A poor relationship existed between MPA and post-mining water quality, NP was intermediate, and NNP and the NP/MPA ratio showed the best prediction accuracy. In this study, NNP and the NP/MPA ratio gave identical water quality prediction results. Therefore using NP/MPA ratios, values were separated into categories: <1 should produce acid drainage, between 1 and 2 can produce either acid or alkaline water conditions, and >2 should produce alkaline water. On our 56 surface mined sites, NP/MPA ratios varied from 0.1 to 31, and six sites (11%) did not fit the expected pattern using this category approach. Two of eight sites with ratios <1 did not produce acid drainage as predicted (the drainage was neutral), and four of 40 sites with a ratio >2 produced acid drainage when they should not have. These latter four sites were either mined very slowly, had non-representative ABA data, received water from an adjacent underground mine, or had a surface mining practice that degraded the water. In general, an NP/MPA ratio of <1 produced acid or neutral drainage sites, between 1 and 2 produced mostly alkaline drainage sites, while NP/MPA ratios of >2 produced alkaline drainage with a few exceptions. ABA is a good tool to assess overburden quality before surface mining and to predict post-mining drainage quality after mining. The interpretation from ABA values was correct in 50 out of 52 cases (96%), excluding the four anomalous sites, which had acid water for reasons other than overburden quality.

Jan 1, 2003

By Leonid Pevzner, Valerie Dmitriev, Yuri Babitchev

Performance of belt conveyors, service life of belts and mechanical elements can be radically improved if the automatic adjustment of the belt speed movement is made in such a way, that the unit load over the conveyor length be constant and close to the rated one under random input freight traffic. Such an adjustment is possible when the system of a controllable thyristor electric drive on the basis of induction squirrel cage motor is used. Computer-aided adjustment of the belt conveyor movement is effected via bicontour digital control of the main drive in order to redistribute loads when the loading of conveyor and contour of the control of tension drive are changed. The system envisages control and condition monitoring of the conveyor electromechanical system, as well as metering of electrical power and the amount of conveyor freight. The results of the simulation of speed control of the conveyor belt are given in the report. Mathematical model of the conveyor electromechanical system describes the movement of the belt with cargo and the tension drive. The input cargo traffic is assumed as stationary ergidic random process with the assigned characteristics. The solution of the problem of the synthesis of a closed-loop control system, the structure and parameters of adjustment, the conditions of asymptotic stability of the control back-up system and the condition of minimization of mean square error of shadowing are also given in the report. Microprocessor controller is used to realize the function of the adjustment unit. Under this control system standard mode of conveyor operation, different modes of start-up, operating mode with decreased speed when transporting people, service and emergency braking of a conveyor and some other modes are realized. The digital model of a conveyor as an instrument for decision making in case of emergency is used in those modes. MASTER TEXT Long-standing practice of belt conveyor operation in mines of Russia has proved their inefficient use with 40-70% capacity and 20-25% availability factor. It is associated with unreasonable power intensity and reduction of service life of mechanical components, and as a result, with the growth of total transportation costs. Low efficiency of conveyor application can be explained by the extremely irregular distribution of conveyor freight traffic. Usually, the width of a conveyor belt is identified in accordance with the possible maximum traffic value, engine power capacity for long-term operation under rated loads. However, actually a conveyor often runs without any load and its average load in most cases is lower than the rated one. The problem can be eliminated by way of the adjustment of the operational mode of a conveyor according to an actual input freight traffic via belt speed control providing for the conveyor regular linear load which is nearly equivalent to the rated one. Experimental research into freight traffic under working conditions of the operating underground and open-cast mines proves the fact that the actual freight traffic can be adequately presented through the model of stationary random function of time, for ex- ample, as a J (t) continuous random Gaussian process that is modulated with a G(t) elementary pulse flow:

Jan 1, 1996

By C. Anderson, K. Nikkhah

This paper outlines the role of simulation software in design and operation of a typical metallurgical plant with mineral processing and hydrometallurgical units, to produce concentrate and pure metal. It addresses the role of simulation and mass balance software in the conceptual, feasibility and detailed design stages. It discusses the use of JKSimMet for sizing of mineral processing units, and METSIM and IDEAS for development of energy and mass balances. In detailed design of a plant, the complex interaction and variation in performance of various units makes it difficult to predict overall system performance and availability. Simulation is used to: assess operating strategies that affect surge capacities at various stages compare different ore types and mining strategies that affect concentrate product quality. optimize transportation logistics for raw materials, concentrate and metal products

Jan 1, 2001

By Thomas A. Colbert

Permanent reclamation of tailing and acid forming mine wastes in the western United States has been largely a losing proposition. There have been few if any successes without actual burial of wastes with soil, overburden, waste rock or other material more amenable to reclamation. Rather than major breakthroughs, development of new techniques has been slow and steady. Revegetation of acid forming wastes with little or no soil cover is now probably feasible. Three key elements include the use of adapted plant species which are now becoming commercially available, lime and selective bactericide for controlling acid, and organic amendments such as manure or sewage sludge. Benefits of this type of reclamation often include reduced mobility of toxic metals and improvements in water quality. With a stringent regulatory regime for mine wastes impending under Strawman II, the importance of good, economical reclamation techniques will become critical to successful and profitable western mining operations.

Jan 1, 1991

By Norbert Patzelt, Johann Knecht, Wolfgang Baum

High pressure roll grinding (HPGR) is a mature but still expanding comminution technology. In the metals mining industry, HPGR is slowly gaining acceptance as a cost-efficient, high-throughput alternative for plant optimization. The increasing need to treat ores with progressively lower grades, complex mineralogies, refractory metal occurrence and variable rock types requires an energy-efficient comminution technology that reduces metallurgical problems inherent in conventional crushing and grinding, while stabilizing leach and flotation circuits and increasing metals extraction. This paper will summarize our latest HPGR pilot test results for gold and copper projects in the United States and South America and their confirmation through the first HPGR operation in copper mining. This paper will also stress the use of the high pressure grinding roll as a metallurgical tool. The application of HPGR for the treatment of heap leach SX-EW ores, semi-refractory gold ores, waste rock material and concentrator feeds will be illustrated.

Jan 1, 1998

By Deepak Malhotra, Robert Dorfler

Modern engineering mill design has been refined over the years to the point where detailed ore and process specification criteria can be developed In the engineering design phase of the project. The plant Is then built to the detailed criteria and performance acceptance tested by the owner to see if the as-built mill meets the criteria, This performance testing is critical to the owner; the test must be systematic with sample collection coordinated throughout the plant. Despite the availability of systematic approaches to plant development, the new plants often fall short of design criteria. This paper discusses the key Issues a Project Manager/Process Engineer should Implement to ensure that plants meet design criteria.

Jan 1, 1991