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By Guiseppe Bonifazi

This work applies the definition of "separation function" already introduced in the paper presented at the XVIII IMPC. This 'function" (defined for a certain size distribution after comminution of an ore) refers to the recovery distribution of a mineralogical species in a product made up of all the particles having at least a given content of that species. Many tests would be required to determine the liberation function for each mineralogical species, particularly for complex ores. Several stages of comminution would need to be examined and the mineralogical composition of the particles of each grain size class would need to be analyzed for each process step. A quick and dirty method is shown for obtaining the "separation function". It is based on the processing of data from topological maps of polished and/or thin representative sections of ore. By superimposing grids of different sizes over these maps and with appropriate combinations of mesh sizes, it is possible to simulate the grain size distributions linked to different stages of comminution and then evaluate the mineralogical composition of each grain. The procedure is carried out full automatically and can simulate a complete treatment circuit, imposing cut-off grades for the products at each separation phase. It is also possible to predict the results of treatment processes that involve grinding phases. The procedure has been successfully applied to complex ores containing several useful components.

Jan 1, 1995

By H. Cho, P. T. Luckie

A study was undertaken to investigate the liberation behavior of coal macerals through size reduction and density separation. It was seen that the liberation of coal macerals could be achieved by size reduction, allowing selective separation of coal organic components. However, the degree of liberation was dependent upon the comminution history. Even for the same fineness, the extent of liberation might not be the same depending on how the material was generated. The liberation of coal macerals was analyzed by examining the liberation index. It was seen that, although comminution produced fine particles enriched in inertinite (primarily fusinite and semifusinite), these particles were less liberated than coarser particles. However, the liberation of macerals increased when all the feed was ground to a finer size.

Jan 1, 1999

By Mark D. Cocker

Georgia?s Coastal Plain contains important sediment-hosted deposits of kaolin, bauxite, heavy minerals, sand and gravel, silica sand, carbonate rocks, and fuller's earth. Genesis, location, size, and quality of these deposits are related to terrestrial, marginal-marine, and shallow-marine depositional environments that evolved during development of the southeastern North American continental margin. From the Cretaceous to Eocene, kaolin and aluminous sediments, which contained mica and feldspar, were deposited in marshes, ponds, and bays located in deltas or behind barrier islands or spits. In the Cretaceous sediments, subsequent, intensive, in situ chemical weathering converted mica and feldspar to kaolin. Kaolin eroded from deeply weathered granitic rocks in the Georgia Piedmont was deposited in Paleocene to Eocene sediments. Subaerial exposure during the Paleocene and Eocene desilicated kaolin sediments to form bauxite. Sand and gravel, silica sand, and heavy-mineral deposits are found in Cretaceous to Eocene fluvial and shoreline sediments, some of which are associated with the kaolin and bauxite deposits. Source areas, intensive chemical weathering in the source areas, transportation by the major river systems, and deposition of these clastic sediments in similar or nearby depositional environments are common elements in the genesis of these resources. Eocene fuller's-earth deposits are opaline claystones in near-shore to shelf-marine sediments, which overlie the kaolin-bearing strata. These claystones consist of montmorillonite and opal/ cristobalite derived from alteration of diatom frustules. Favorable ocean currents provided nutrients for extensive planktonic growth. Oligocene and Miocene carbonate rocks were deposited principally in shallow-marine embayments. Miocene fuller's- earth deposits in south-central Georgia and adjacent parts of Florida contain palygorskite that formed through alteration of montmorillonite/bentonite clays. Deposition and subsequent alteration occurred in shallow, brackish-water lagoons under relatively high temperature and subtropical conditions. Middle and late Miocene phosphorites were deposited on a shallow carbonate-shelf platform and were concentrated proximal to anticlinal highs. Numerous marine transgressions and regressions since the beginning of the Pleistocene resulted in shoreline detrital deposits containing aggregate sand, silica sand, and heavy minerals on the Coastal Plain and on the Continental Shelf. Major river systems transported sand and heavy minerals from source areas in the Piedmont and Upper Coastal Plain. Deltaic deposits of heavy minerals were redistributed and concentrated by longshore currents, shoreline processes, and aeolian processes. River-terrace sediments, correlative with the Pleistocene shoreline deposits, contain sand-and-gravel and silica-sand deposits. Aeolian dune sands are associated with both Pleistocene fluvial and shoreline detrital deposits.

Jan 1, 1999

By R. Q. Honaker, D. P. Patil, A. Sirkeci

Because of increasing production of fine coal during mining over the past century and because of inefficient fine-coal recovery technologies, a vast reserve of high-quality coal now exists in refuse ponds. A novel finecoal circuit, consisting of a hindered-bed classifier, an enhanced gravity concentrator and a flotation column, was evaluated for the recovery of fine coal from refuse ponds. The treatment of a pond derived from Pittsburgh No. 8 seam coal resulted in the production of a premium fuel containing less than 5% ash and a calorific value of about 30,170 kJ/kg with 60% mass yield. Results from the treatment of two refuse pond materials are presented in this paper.

Jan 1, 2002

By P. R. A. Andrews, G. Heinrlch, V. I. Lakshmanan

The paper describes a simplified method to chemically modify the surface of industrial mineral fillers. Four industrial mineral samples were taken from feedstock of commercial fine grinding operations. These samples were ground in bench scale ball mills and in the presence of various organic solvents. The ground products were measured for particle size distribution, surface area, surface chemistry by oil absorption and degree of organicJminera1 bonding. Where appropriate, the ground products were compared to commercially available surface modified, industrial mineral fillers.

Jan 1, 1990

By Jean-Luc Cornet

Advances in conveyor technology over the past decade have enabled the design and erection of very long overland belt conveyors. Such conveyors usually require head and tail drives to lower the belt tension and belt strength required. This paper provides an overview of the problems encountered in controlling the head and tail drives on such conveyors and some of the solutions developed by CDI for several such projects.

Jan 1, 2002

By D. III Earley, R. L. Blake

The Bureau of Mines is investigating the potential for in situ mining (ISM) of gold and silver mineralization. This preliminary study examined samples from several types of deposits. It used light optical microscopy and the electron microprobe to characterize the ore and gangue minerals and textural features of these samples. This included the spacial relations between the target minerals and likely natural fluid channel ways. Low-grade disseminated deposit types from the western US were found to contain fracture- hosted or matrix-hosted gold and silver minerals, some of which are encapsulated by quartz or pyrite. Successful ISM application to gold and silver deposits needs this data in order to understand potential problems of the lixiviant reaching the ore minerals.

Jan 1, 1991

By Y. Astafyev

Autotransport is one of the most conventional kinds of transport in iron ore open-pits. It. is successfully used both independently and in combination with other kinds of transport. In the Krtvoy Rog Basin open-pits annual truck transportation accounts for more than 235 million tons of ore and waste rock. In the process of operation trucks make up various transport streams depending on - the development of autoroads in the open-pits; - the capacity and the number of loading equipment ; - the load carrying capacity and the speed characteristics of trucks

Jan 1, 1979

By Eric Forssberg, Mats Hallin

INTRODUCTION Evaluation and optimization of mineral processes has been going on since the the first plant started hundreds of years ago. A huge mass of knowledge has been collected since then. The main problem with this type of empirical knowledge of complex processes is that it is very difficult to formulate and document. The methods used for collecting the knowledge is not consistent but-varies with "he person" that does it. In the late 60's and early 70's efforts were made to use computer based techniques to evaluate process performance and to formulate process models for mineral processes. Models were developed, such as the flotation model by R. P. King (1973) which is still used to simulate flotation circuit behaviour. During the 70's. a number of mass balancing packages were developed together with process simulation packages. The industrial sector also made great efforts to develop and utilize computer based systems for process control and evaluation. The expert system that BOLIDEN created in 1974 at the Kristineberg plant was a remarkable achievement considering the hardware (CDC 3600) and the software tools (FORTRAN) available at that time. The main obstacle to successfully implement optimizing computer control of mineral processes was and still is the limited knowledge about the dynamics of complex processes. There are, however. many activities going on in this area today and it seems that the technology is very near a break through. Process evaluation is the most important tool to improve and maintain the optimal performance of a process. Today dedicated computer based techniques are used for fast and reliable screening of the processes. The stages in process evaluation consist of three basic steps: - Data acquisition, manually or by data logging. - Data refining, mass balancing and parameter calculation. - Data evaluation. The refined data can then be used for model construction/calibration and subsequently for process simulation. This paper describes two studies where the techniques mentioned above are used to evaluate and simulate

Jan 1, 1991

By R. L. Grayson, Y. J. Wang

An integrated approach to the management of underground coal mine production and cost is presented. A conceptual model for objectively analyzing an underground mine to obtain lower cost and higher productivity from operations is outlined. The model is designed to provide mine managers with a quantitative, decision-assisting methodology that can be used in formulating timely responses to fluctuations in operations. It consists of a productivity fore- cast component, routine use of current resource consumption factors, a linear programming scheduling component, a manpower loading analysis, and an inventory control component. The model is applied to an underground coal mine.

Jan 1, 1990

By Robert Dimock

The successful management of large dispersed mineral operations is dependent upon accurate and timely decision making. The plant locations providing the data to support the decision making process are generally separated by distances which elongate the time required to accumulate the data at a central focus. The need exists to examine operational data in context with total mining operations, and in relation to target projections and historical trends. The use of microcomputers for local information tasks is an established capability. Grouping microcomputers into local-area networks is rapidly becoming established. Interconnecting multiple local-area networks to provide a free flowing stream of information between all operational locations of a mining enterprise is possible with use of some emerging technologies. The benefit of the potential interconnections and rapid transfer of information can readily be seen from a production reporting perspective. Numerous other advantages exist' by providing routing to enable a workgroup to be established between separated work functions.

Jan 1, 1989

A series of laboratory based push and pull tests were carried out to investigate how surface profile influence the load transfer mechanism of bolt/resin interface. Tests were carried out in both 75 mm and 150 mm long steel sleeves. Three types of bolts were examined, they were bolts most commonly used for strata reinforcements in underground coal mines in Australia. The bolts had near equal core diameter but of different profile configurations. The change in the length of the encapsulation sleeve was examined in light of the small number of profiles encapsulated effectively in short 75 mm long sleeves. The results showed that peak loads and displacements were directly related to the height and the spacing of the bolt surface profiles. Profile spacing appears to have greater influence on load transfer capacity than the profile height.

Jan 1, 2006

By Robert R. McDougal, Anne E. McCafferty, Bruce D. Smith

Magnetic, electromagnetic, and radiometric airborne survey data have been used in regional and local (drainage basin) scales. In a regional geoenvironmental assessment of the state of Montana, magnetic and radiometric data compiled from airborne surveys were used along with other digital geologic and geochemical data to prioritize mining districts for potential acid water generation. Probability ratio mapping was done in order to integrate the interpretation of many different digital data sets. On a more local scale, the Animas (CO) and Boulder Basin (MT) watersheds have been studied using helicopter geophysical surveys. The airborne geophysical surveys show many more structural features than the geologic maps. Combined interpretation of the geophysical data sets using the probability ratio method has resulted in identification of areas of alteration. Airborne radiometric data in the Boulder Basin area suggests that rocks with high potassium and thorium also have a high acid water buffering capacity.

Jan 1, 2000

By A. E. Isaacson, D. B. Dreisinger, G. A. Kordosky

The U.S. Bureau of Mines is researching the application of solvent extraction technology to highly acidic (pH < 1) copper leach liquors. As increasingly complex copper ores are mined for leaching, use of highly acidic leach solutions maybe necessary to effectively recover the contained metal values. A mixture of two commercially available extractants, based on aldoximes and substituted 8-hydroxyquinoline, which has a high transfer efficiency has been identified. A synthetic leach liquor, containing 5 g/L Cu at pH 0.9 was processed utilizing the mixed extractant and a laboratory SX circuit. The loaded organic was stripped with a synthetic barren electrolyte compatible with electrowinning technology.

Jan 1, 1993

By P. Somasundaran, Brij M. Moudgil

All the major interfacial technologies encountered in mineral processing involve adsorption of surfactants and/or polymers. With the need for processing low grade complex ores it is imperative that conventional techniques such as flotation and flocculation be extended to meet the challenge of treatment of fines. Addition of surfactants or polymers is indeed not limited to the solid-solid separations but extends to particle size reduction in the form of grinding aids and dewatering operations as well. Although progress has been made in recent years to understand the science involved in various interfacial processes, more challenges and opportunities exist today than ever before in processing of the low grade finely disseminated ores. A brief review of the recent advances and the challenges in mineral processing, especially, those related to the interfacial technologies is presented.

Jan 1, 1989

By J. Y. Kim, R. W. Stanley, L. Rosato

Silver contained in zinc calcines undergoes several phase changes as it proceeds through the leaching circuit of a roast-leach-electrowin zinc plant. In this study, the flotation response of silver, from leach residues prepared under a variety of carefully controlled operating conditions in the pilot plant has been examined. Flotation of neutral leach residue is shown to be technically viable and to merit consideration for those plants without a high-acid leach circuit, but having significant silver values in the feed. Residue leach conditions must be kept slightly acidic to promote the formation of Ag2S, (AgCu) 2S and Ag2S rims on residual unroasted sphalerite, while simultaneously avoiding the hydrolysis of soluble iron, which depresses silver recovery and grade. Factors to be considered during integration of a flotation process into an electrolytic zinc plant are discussed.

Jan 1, 1992

By Ke Yang

In Chinese coal mines, extraction of deep, highly gassy soft coal seams sandwiched between soft floor and soft roof in complicated geology is commonly encountered. How to safely and efficiently excavate such seams is a very significant and important problem. It has been a focused research area in recent years. By combining the characteristics of fully mechanized longwall mining methods such as large cutting height and mining along the dip, an integrated method and technologies for the Zhangji Coal Mine were developed. This technology includes the design of a complicated geological exploration system, optimization of mining method and working face parameters, control of rock pressure and high levels of gas, reliability model of the production system, and selection and compatibility of equipment. Engineering practice shows that the integrated technology was successful in mining these complicated seams. This study not only enriches the mining method, but also improves the coal mining practice, especially ensuring both safety and productivity under complicated geological conditions.

Jan 1, 2009

By Brian Flintoff

Basic process control is an integral part of most mineral processing plants. It is widely acknowledged to have helped many operations reduce costs and increase productivity and performance. The research community is very active in the development and evaluation of both model based and Al techniques for advanced control applications. Vendors and specialist consulting or engineering firms are in business to help deliver these solutions to the plant floor. It would seem that there is a good balance between business needs and technology, and that the industry should be moving steadily forward in an aggressive pursuit of plant-wide automation. However on closer examination one sees some systemic problems which are sewing to inhibit progress. One of the mist obvious manifestations is the gap which exists between the available technology and current This paper explores the control of mineral processing systems, with a particular emphasis on some of these problem areas.

Jan 1, 1995

By Roger J. Hornberger, Paul F. Ziemkiewicz, Dirk J. A. vanZyl, Gene E. Krueger, Harry H. Posey, Kim A. Lapakko, Charles H. Buckmam

The Acid Drainage Technology Initiative (ADTI) was initiated in 1995 by federal agencies, the National Mining Association and the Interstate Mining Compact Commission to identify, evaluate and develop cost- effective and practical acid drainage technologies. In 1999 ADTI was expanded through the addition of the metal mining sector group, which began organization efforts in 1998. ADTI addresses drainage quality issues involving metal mining and related metallurgical operations and acid drainage from coal mines, for abandoned, active, and future mines. ADTI is a technology development program. It is not a regulatory or policy development program. The guiding principle of ADTI is to build a consensus among industry, federal and state regulatory agencies. ADTI is focusing these efforts on technology development and technology transfer in the areas of mine drainage sampling/monitoring, prediction, avoidance/remediation and modeling.

Jan 1, 2000

By R. J. Pugh

The surface chemical sites on several fillers (quartz, feldspar, calcite and granite) were studied by the adsorption of well defined acid and basic probe molecules (benzoic acid, benzyl alcohol, ethyl benzoate, pyridine and benzyl amine) from cyclohexane. The results provided a wide variation of adsorption data, emphasizing the extensive range of site heterogeneity on the filler surfaces. In addition, it was shown that the acidic probes were strongly adsorbed on all of the minerals, thus indicating that the basic surface sites dominate the acidic ones. Also, through FTIR studies with vapor-phase probes adsorbed on orthoclase, it was possible to identify the nature of specific sites and the type of bonding occurring between the filler surface and the probe molecule. These types of surface analytical techniques could give useful information for predicting the adsorption functional groups on dispersants, dyes, thickeners, etc. and could lead to enhanced interfacial bonding between the filler and the matrix.

Jan 1, 1993