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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 Eddy J. Jacques

When the automatic control of a ventilation process is considered, and supervising expert systems need to be designed, an important problem to address is: what will be the optimal set points of the regulators that should meet a certain number of independently formulated requirements, distributed over a ventilation network? The set of these requirements, expressed in terms of air flow quantities or differential pressures in certain airways, need not be consistent. Their number is not limited by the number of available regulators, nor by their nature, i.e. passive or active. Moreover, they may be subject to upper or lower limit values. The method described here addresses this problem and tries to provide a tool that should allow to calculate the set points of all the regulators as a global and optimal solution with respect to this set of distributed requirements. The pure mathematical developments in this paper are kept as short as possible in order to allow more room for the description of a relevant example.

Jan 1, 1991

By T. W. Healy, W. J. Trahar

INTRODUCTION The flotation of minerals from their ores in flotation cells involves understanding many chemical and physical processes ranging from electronic events in the bulk mineral and in the mineral surface regime. molecular events at interfaces, the statics and dynamics of thinning and rupture of microscopic to molecular intefacial films, the fluid mechanics of bubble- particle events, the dynamics of air-water-solid colloid states in a flotation machine, etc. etc. D.W. Fuerstenau, whom we honour in this symposium has made unique contributions to many of these diverse physico-chemical and technological sub-processes. The present paper is concerned with a number of observations of the behaviour of minerals in flotation cells and the surface science of some mineral sulfide-water systems. We do not intend to be comprehensive in our analysis, but rather to highlight the challenges that face the scientific masochist who chooses to understand "froth flotationn. In what follows, emphasis is placed quite deliberately on technologically relevant, dynamic or realistic flotation processes i.e. the recovery in a froth of a given sulfide mineral particle of a given size and history from synthetic or actual ores in a flotation cell. The paper also attempts to use the understanding that is emerging from the area of photoelectrochemistry of colloidal

Jan 1, 1989

By S. Kelebek, G. W. Smith

Four samples of galena, each prepared differently, dry ground chalcopvrite and real gar have shown various quantities of liberated sulfur corresponding up to nine equivalent monolavers on their surfaces as determined by the solvent extraction/UV analysis of sulfur using ethanol. The pretreatment of a dry ground galena sample with acidified ammonium chloride or neutral, saturated sodium chloride solutions rendered the mineral readily floatable. The collectorless floatabilities of galena pretreated with the former solution and of drv ground chalcopvrite have been evaluated in reference to the natural floatability of sulfur using the critical surface tension of floatability approach with aqueous methanol solutions. It is shown that the amount of sulfur- on these samples can be correlated with their flotation rate, which was found to he first order within the critical surface tension range. The larger the concentration of surface sulfur, the faster the sulfide mineral floats, thus, the greater its flotation rate constant.

Jan 1, 1990

By F. L. Wilke

The prototype of an expert system, designed to assist layout planning of face operations, is presented. By specific combination of knowledge-based and conventional EDP techniques it has been possible to extend the known Kepner-Tregoe method up to the determination of mature layout solutions in difficult planning cases. It has been proven that the presented strategy - which can be applied to any kind of problem with similar structure - is apt to provide efficient EDP support for handling complex mining problems. Such support goes far beyond the purely numeric evaluation of envisaged alternatives.

Jan 1, 1989

By M. Galetakis

The difficulties that rise during the evaluation of multiple-layer lignite deposits come from the deposit structure (alternating lignite layers with intercalated material of varying thickness), as well as from the limitations of the applied selective mining. Thin layers of lignite and interbedded waste layers are grouped under specified assumptions regarding thickness and ash content, to form the exploitable blocks. However, in practice the decision for excavating a block is made under subjective constraints of different importance or by using uncertain data. Advances in Fuzzy Inference Systems (FIS) have provided a new approach to the evaluation of multiple-layer lignite deposits. FIS have the ability to handle imprecise or incomplete or linguistically ambiguous information and to incorporate them into decision-making processes. In the developed FIS (Mamdani type) new linguistic variables, concerning with working conditions, operators? experience and production were involved. The FIS was used for the estimation of quality characteristics and reserves of the exploitable lignite produced from Southern Field mine, Ptolemais (Greece).

Jan 1, 2005

By J. H. Meza Viveros

This paper describes some actual parameters and technologies used at Mexicana de Cobre Smelter, and the principal design parameters and new technologies which wiil be used with the smelter expansion project, in order to increase the production capacity of anode copper from 180 000 mtpy to 300 000 mtpy. Likewise its describe some parallel projects under construction also in the smelter plant.

Jan 1, 1997

By Edward J. McNamara

Sulphur as an element has been used for centuries. The technique of storing, handling and transporting it in its various forms has changed through the years. Freeport Sulphur Company, a division of Freeport Minerals Company, has produced sulphur since 1912. The first storing and transporting of this product as a liquid began in 1947. Significant environmental problems occurred in the handling of solid sulphur in the late fifties and early sixties. Since the sulphur WAS produced in the liquid form and the major customers used it in the liquid form, it became obvious that a liquid transportation system was the solution. The liquid sulphur delivery eliminated the dusty and hazardous handling problems and the contamination of the sulphur by dirt, acid, moisture and other materials. The remelting by the customer to use the sulphur is thusly eliminated with a savings in energy. In addition, this change in the mode of handling permitted a broad development of new sulphur mines in the marshy coastal area of Louisiana and offshore in the Gulf of Mexico.

Jan 1, 1978

By V. O. Tenorio, A. M. Sanzana

"INTRODUCTION This report summarizes a research about mines which are transitioning from surface to underground mines. It is a guide to make strategic decision in these increasing amount of mines. Capital and operating costs are linked with major strategic decisions in the exploitation of an ore body. This is the reason to analyze costs related to this transitioning world trend. There are multiple reasons for transitioning from Open-Pit (OP) to Underground (UG) mining. The primary economic incentive for going UG is that the cost per unit of ore from OP mining eventually exceeds that from UG extraction. This is due to the excessive amount of waste that must be extracted when the depth of the pit increases. In addition, the reduced footprint of UG operations contributes to diminish the environmental impact on the surface. Furthermore, it becomes more difficult to find new, easily accessible ore deposits. Then, a cost model helps to guide strategic decisions in the transition from OP-to-UG mines. Objectives • Propose a methodology to guide strategic decisions in the transition from OP to UG mining. • Create an integrated cost model based on existing OP and UG individual cases. • Identify and characterize a group of mines transitioning from OP to UG. • Analyze operating and capital costs of a particular transitioning from OP to UG mine. MAIN CONCEPTS Open Pit Mining (OP) The main decisions in OP mines are: Cut-off grade, Stripping Ratio (SR), equipment size, stockpiling, pushback sequencing and processing capacity. The stripping ratio is measured as the tonnage of waste required to be removed to reach and extract one tonne of ore. The material extracted from an OP exploitation can be classified as waste and ore. This classification depends on the cut-off grade. The cut-off grade indicates the minimum amount of material with economic value in a block. The waste from the mine is going to the waste dump and the ore is going to stockpiles where will be store and then going to the processing plant (leaching or concentrator). The waste of this process is going to the tailing pond big pools. And the product is sell in the market. Another important issue is the mining capacity which is going to define the investment in mining equipment. Underground Mining (UG) The first decision to be made in order to open an underground mine is selecting the mining method. Caving methods are the more productive and have lower operating costs. There are three caving methods: Block Caving (BC), Panel Caving (BC) and Sublevel Caving (BC). The access development could be an horizontal adit or a straight or downspiral decline. A shaft could be used for inclined or vertical access. Other key issues are: equipment capacity, cut-off grade and production sequencing."

Jan 1, 2016

By A. D. Davis

This project took a watershed approach in the evaluation of water-quality impacts from past mining activities and current restoration projects in the Bear Butte Creek basin, a small and well defined drainage in a heavily mineralized area of the northern Black Hills. The basin contains numerous inactive and abandoned mines as well as a currently active heap-leach surface gold mine. Bear Butte Creek normally loses all of its discharge to sinkholes in the Madison Limestone aquifer and thus can affect the water quality of this regionally important water resource. Water-quality data were analyzed, stream surveys were conducted, and two abandoned mine restoration projects were monitored to evaluate the effectiveness of the watershed approach and to identify practical remediation techniques that could be applied to other watersheds. A geographic information system (GIS) was developed to organize information on stream quality, abandoned mine locations, and other geologic and hydrologic data. The watershed approach toward assessing and reclaiming abandoned mines appears to be effective when compared to a point-source approach that might improve water quality at specific sites but not result in significant overall improvement to the watershed because of adjacent sources.

Jan 1, 1997

By John Bailey

Stressmap is a program whereby the earth's stress field is charted in detail and utilized for design of mines and mine exploitation. This program is implemented by mapping the attitude (location, direction, dip, and extent) of induced rock ruptures during the process of hydrafracturing drill holes contiguous to mine interest. The program includes utilization of ancillary naturally occurring stress relief signals, They are precipitated because the earth is indeed dynamic and the strata of the crust are continually adjusting to load and/or strain differentials resulting in rock deformation and fracturing. These fracturing adjustments occur as small to tiny earthquakes comparable to Richter magnitudes of one, zero, minus one, and smaller events termed microearthquakes. Obviously, the earth's stress field changes due to continued differential loading and crustal movements; therefore it becomes conspicuously evident that resolving today's stress field as opposed to paleostresses is most important for efficient, economical, and safe mining operations.

Jan 1, 1974

By William N. Poundstone

Consolidation Coal Company, through the mining research division of Continental Oil Company, is now undertaking the installation of a full-scale hydraulic transportation system to carry coarse coal from the mine face to the preparation plant. The facility will include all elements of a fully integrated haulage system including face haulage for both longwall and continuous miner sections, multiple slurry feeds, hydraulic hoisting and 2.4 miles of overland slurry transport. This undertaking is a result of more than six years of extensive research and testing, some of which has been previously releasted to the literature. To provide a reference framework for system description, a brief history of recent coal mining technological developments will be discussed. Following World War II, mechanization resulted in mining machines that were bigger, faster, more powerful, and more reliable. These changes were essentially refinements in an established mining system. They made mining more efficient than before, but they did not change the system itself. By about the mid-1960's, it was apparent that further improvements in the extraction machinery would have a declining payoff, simply because .the worst bottlenecks were in other components of the mining system. A modern continuous miner cannot be run continuously because other operations underground cannot keep pace. In fact, most continuous miners today run at less than 20% of capacity. Consequently, in 1969 Consol and its parent company, Continental Oil, undertook a long-range R&D program to try to change the basic haulage system for the better. Most coal at present is removed from the mine by a hand-off system in which the coal is transferred from the continuous miner to a shuttle car, often with the aid of a separate loader; then from the shuttle car to a system of conveyor belts; and finally from the conveyors to rail cars. The system involves a large amount of moving equipment underground, many transfer points, and the everpresent chance of operational delays and safety hazards. By removing the haulage bottleneck, we believe we can speed up underground operations substantially; and perhaps more important, we could make it feasible to develop a whole new generation of mining equipment that is inherently safer. What we wanted was a truly flexible, continuous haulage system with inherent safety advantages. Ideally the system had to meet three major requirements: First, the coal had to enter the transport system at the face, and remain in that same system all the way to the preparation plant. Second, the system had to be flexible and extensible so that it could- follow the mining machine as it advances and retracts. And, third, the system must be inherently safer than current haulage technology.

Jan 1, 1977

By Rick Bearce, Minsu Cha, Mike Mooney, Yuanli Wu, Lisa Mori

"Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. Chamber pressures can reach 3-5 bar yet the vast majority of testing is performed under atmospheric conditions. This paper illustrates how pressure influences foam stability and conditioned soil behavior, and how atmospheric test results must be viewed in the context of expected chamber pressures. Torsional shear strength, compressibility and abrasivity of foam conditioned sand were found to be ideal when the void ratio was above the ASTM-determined maximum void ratio, achieved by sufficiently expanding the soil grain structure with foam, herein when the foam injection ratio at pressure exceeded 45%. Otherwise, the engineering properties of foam conditioned sand were not ideal, i.e., appreciable torque and abrasivity, low compressibility. INTRODUCTION Proper soil conditioning is critical for effective earth pressure balance (EPB) TBM tunneling. The formation soil at the cutterhead must be transformed into a highly compressible, low shear strength and low permeability medium within the excavation chamber to allow effective EPB performance. This behavior must be maintained for a certain residency time while the soil is in the chamber and screw conveyor. The vast majority of published studies on conditioned soil behavior have been performed under atmospheric conditions (Quebaud et al., 1998; Bezuijen et al., 1999; Psomas and Houlsby, 2002; Vinai et al. 2008; Thewes et al., 2012; Peila, 2014); however, the desired soil behavior must occur under chamber pressures that can reach 5-7 bar. The influence of pressure on conditioned soil is significant and is dramatically different than behavior under atmospheric pressure (Williamson et al., 1999; Mori et al., 2015). This paper illustrates how pressure influences conditioned soil behavior and how atmospheric test results must be viewed in the context of expected chamber pressures. The influence of pressure on foam bubble size (including with time) is shown through digital image analysis. The influence of pressure on foam half-life is also investigated. The compressibility, shear strength, and abrasivity of conditioned soil under pressure is presented and explained in terms of density, soil and air compressibility and porosity."

Jan 1, 2016

By Barry N. Doyle, Tarcisio M. Carvalho, Alan K. Haines, Marcos P. de Melo, Edward J. da Silva

A metallurgical complex to recover gold from highly refractory arsenical ore was recently commissioned by Sao Bento Mineraco. The plant, with a nominal capacity of 20 000 tonnes per month, is situated in the Minas Gerais province of Brazil. The process consists of run-of-mine milling, flotation, pressure oxidation of the concentrate, carbon-in-leach, elution and electrowinning, and effluent disposal. The paper provides an account of the investigations that resulted in the decision to install the pressure oxidation circuit, process and engineering design and plant start up. A comparison is made between the results achieved during the first two years of production and the design parameters.

Jan 1, 1989

By J. J. Lewis

In the mid-1970's a major new prospect was proved in a previously unworked region of North East Leicester- shire, United Kingdom. Preliminary estimates from borehole information showed over 500 million tonnes of recoverable reserves. A special Planning Team was set up, to co-ordinate the work for the two local Areas, South Nottinghamshire and South Midlands (management of production of the UK National Coal Board is organised in twelve such Areas). The team was led by one of the authors as Deputy Director, Mining, North East Leicestershire Prospect (NELP). The remit imposed by the National Coal Board was to analyse the possible options of number, location and eventual rates of output of shaft or drift access; to select a recommended alternative in the light of geological, mining, topographical and environmental considerations; and prepare submissions in accordance with standard Board practice on major projects - such submissions including detailed engineering design, financial appraisal, and full risk assessment. To assist the Planning Team, surface and underground consult- ant engineers were appointed to prepare feasibility studies of specific civil and engineering problems.

Jan 1, 1979

By Edward T. Koch

With the dramatic increase in world demand for basic raw materials, open pit mining is proceeding at an unprecedented rate. A viable demand is the ever tempting Siren's song for increased production or new facilities. When the Siren's lure is viewed against the panorama of today's world economic milieu the concomitant Scylla and Charybdis are seen in the form of high capital cost and high operating cost. If the economic realities of present day open pit mining are to show a proper return on investment, a clear and penetrating eye must be cast upon the area of mine planning. This paper deals with the problem of overburden removal. In almost every open pit mining operation overburden removal is a significant part of the capital cost and operating cost of the total operation. This paper deals with a new and unique method to affect economical overburden removal. Well known to all are the parameters surrounding draglines, shovels, and bucket wheel excavators. All of these machines require a reasonably stable soil to support them and the shovel and bucket wheel excavator require a reasonably stable bank in which to operate. Their reliability, portability and rate of production per dollar of invested capital are good.

Jan 1, 1975

By P. K. Muduli

The number and the type of trucks and shovels are two important factors in determining the optimal design parameters of an open-pit mining system. Characteristics of trucks' arrival and service-time distributions determine the performance measures of a truck-shovel system when it is modeled as a closed queuing network. In all of the previous analytical queuing studies of truck-shovel systems, trucks are assumed to be identical with respect to their arrival and service-time distributions. This assumption, although desirable for reducing computational difficulties, causes either underestimation or overestimation of the performance measures depending on the number and type of equipment used in the model. The relative error in performance measures could be significant when the number of different types of trucks and shovels is large. In this paper an analytical method is proposed to model the truck-shovel system as a multiple-chain closed queuing network. This approach would provide the capability of estimating system performance measures for planning purposes when the truck fleet is not necessarily composed of identical trucks. An example of truck-shovel systems is discussed to show how the incorporation of different types of trucks does affect performance measures.

Jan 1, 1996

By Leonard H. Hoyle

The American Society of Association Executives is a professional society composed of nearly 10,000 individuals who serve as salaried executives on the staffs of more than 6,500 associations. Represented is the full range of international, national, regional, state and local associations...including trade associations, professional societies, philanthropic organizations and others. The dramatic growth of ASAE during the past 15 years is a manifestation of the growth of the association movement during the past two decades. This is not to imply that associations are a new phenomenon, because they have existed for thousands of years. Ancient civilizations show evidence of groups formed for mutual protection and advancement. In the transition from ancient to medieval time, trade associations and guilds came to serve an important function for the craftsmen and merchants they represented, encouraging the growth of new industries, improved processes and education.

Jan 1, 1981

By P. M. Krishna

A five-year effort by the ASTM subcommittee E10.14 on Uranium Resource Evaluation has culminated in the approval of E901-82, Classification System for Uranium Resources. The standard classification was prepared with participation of representatives from the Dept. of Energy, the Dept. of Interior's Geological Survey and Bureau of Mines, utilities, and consultants. The classification of a resource is based on level of knowledge and the economic producibility of the resource at a given time. Alpha-numeric identifiers are used rather than words to avoid confusion with existing terms, definitions, and classifications. An effort is underway to develop estimation criteria to guide users in classifying a resource according to the above format.

Jan 1, 1983

By Sureshan K. Moothedath

This paper provides a mechanistic representation for floc formation, growth and degradation and presents results from an experimental study of batch flocculation in which step changes were made in the impeller speed, flocculant addition, and slurry concentration. A discussion of the experimental results is included in terms of the mechanisms of floc formation and size-change.

Jan 1, 1993