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The overall mineral assemblage of the Broken Hill orebody is similar to that of a skarn. However unlike the classical skarns it does not represent contact metamorphism of pre-existing limestone beds. It is a stratiform accumulation of exhalative-sedimentary silica, sulphides, (Ca, Fe, Mn) silicates and carbonates, fluoride and phosphate that has later undergone regional metamorphism. The resulting development of coarse-grained quartz, sphalerite, galena, rhodonite, bustamite, mixed carbonates, fluorite, apatite and many minor phases has produced a sulphide-rich skarn- like mass that like many others of its kind, might best be referred to as a stratiform skarn. Recent investigations of occurrences of this type are showing that the incidence of concentrations of particular metamorphic minerals in and adjacent to such orebodies are closely related to bedding and to former sedimentary facies patterns. From this it appears that the mineral assemblages may be used to deduce not only the nature of the materials laid down in the beds, but also the physico-chemical conditions under which sedimentation took place. Several stratiform deposits, including Broken Hill, are used as examples to show that variations in these conditions may have a profound influence on the subsequent response of the rock to regional metamorphism and hence on the mineral assemblages that finally develop.

Jan 1, 1983

By G. R. O?Neil

The justification for a "ligand- selective' approach to fine mineral beneficiation via flocculation is established initially. Special emphasis is placed upon the need to identify non-selective, interfering and complicating adsorption effects. Specific strategies directed towards the design and synthesis of complementary selective flocculants are detailed using a number of different polymers and chelating agents as examples. In this regard, the affinity of polymer-bound ligands for metallic cations, ligand concentration, possible modes of attachment, the application of spaced-out ligands and other considerations in the preparation of selective flocculants are highlighted.

Jan 1, 1983

By A. K. Sinha

The annual production and productivity of underground coal mines in recent years declined from 334 Mt (368 million st) and 14.5 t (16 st) per man per shift in 1969 to approximately 254 Mt (280 million st) and less than 8 t (9 st) per man per shift in 1977. Productivity is still hovering at about 7.25 t (8 st) per man per shift. According to US Bureau of Mines, the estimated US coal reserve is about 396 Gt (437 billion st), 68.65% of which is obtainable by underground mining methods. Approximately 153 Gt (169 billion st), or about 85.2% of the high Btu premium coking coal of the eastern US, would need to be extracted by underground mining methods. It is thus apparent that under- ground mining will continue to play a major role in total US coal production, which is expected to rapidly increase to about 1.1 Gt (1.2 billion st) by 1985, with about 606 Mt (668 million st) being contributed by underground mines. Production Potential of Continuous Mining The production potential of a continuous mining section depends primarily on the producing ability of the miner, transporting ability of the face haulage, and the matching of the two systems. The producing ability of the continuous miner depends on its actual cutting ability and the time available for cutting coal. The performance of 10 continuous miners operating in coal seams of various thicknesses were monitored in Pennsylvania and West Virginia, using continuous electrical power analyzers and time studies. The recordings on current and power strip charts yielded an accurate analysis of the cutting, trimming, and idle times of the machines on a full shift basis. Continuous miners of various models and sizes from 112-298 kW (150-400 hp) were monitored. Based on actual cutting time, the average cutting ability of the machines, as shown in [Fig. 1], ranged from

Jan 1, 1983

By John L. Watson

The processes of magnetic separation and cyclone classification are common in the mineral processing industry, and frequently the two are found in consecutive stages in the beneficiation of a magnetic mineral ore. The application of a magnetic field across the cyclone, to combine the two stages in treating a magnetic mineral pulp, has been investigated with a view to possible practical applications in the mineral industry The results of this research reveal that magnetic particles can be manipulated within the cyclone body by the application of a magnetic field, and that magnetic grades may be significantly upgraded with recoveries in excess of 90%.

Jan 1, 1983

By Morrison R. D

This paper describes major events in the design, construction, camtissioning and operation of the Elura concentrator. It covers the period fran September, 1974 when laboratory testwork on drill core cotmenced to March, 1983 when the concentrator catmenced operation on run of mine ore following successful completion of initial ccnmissioning tests. The concentrator was designed to treat 1.1 million tonnes of lead-zinc-silver ore per year with a plant availability of 89 per cent. This treatment rate has been achieved for test periods.

Jan 1, 1983

By Ronald A. Crowson

Detailed stratigraphic studies of the overburden at North Carolina Phosphate Corporation new South Creek Mine have delineated several aquifers and acquicludes within the 30-meter-thick overburden section of late Pleistocene sands and clayey sands. A major aquifer occurs in the 10-meter-thick sequence of shelly sands of the early Pleistocene Croatan Formation. The water-charged Croatan sands thicken into a paleodrainage surface on top of the Pliocene Yorktown Formation, a major aquiclude. A three-phase dewatering program is projected: 1) improve surface drainage around mine perimeter to reduce both flowage into the pit and rainfall recharge; 2) use a wellpoint system to dewater the upper 8 meters; and 3) use recharge wells along the axis of the paleo- drainage to dewater the overburden below 8 meters.

Jan 1, 1983

By Dan A. Permenter

This paper assesses some of the critical factors that must be considered and addressed in the implementation of small computer systems for technical applications within a coal company. Aspects of hardware selection that are somewhat specific to the coal industry are discussed, and a table of potential areas of application is presented. The dilemma of internal software development is presented and a software development program based on a users group approach is outlined and discussed in detail.

Jan 1, 1983

By William H. Callahan

"For his exceptionally successful career as a geological mentor, for his ore-finding skills, and particularly the discovery of the Central Tennessee Zinc District and for his lecture, 'Prospecting in the USA-Promise and Problems.' " Recipient of the 1982 D.C. Jackling Award

Jan 1, 1983

The "Line of Lade", a generic term by which the great Broken Hill orebodies are collectively known, lies in the County of Yancowinna, New South Wales (NSW) at the south eastern extrenity of the Barrier Ranges. As the township of Broken Hill grew to a city (incidentally it was officially named Willyama but by exerting an enterprising community independence which is still evident today it outplayed officialdom and retained its descriptive name), two major areas of population developed, Broken Hill and South Broken Hill. These two main civic divisions are respectively north west and south east of their dividing line, the surface expression of the orebody. See Fig. 1. The border between the States of NSW and South Australia (SA) is drawn along longitude 1410 East whilst the city of Broken hill's official longitude is 1410 28' 14" East which means it is only 50 km from this political boundary. A latitude of 310 57' 03" South contributes to the harsh climate of high summer temperatures which is not mollified by any significant increase in altitude for Broken Hill is only 300 m above sea level.

Jan 1, 1983

By Dwight L. Sawyer

To provide technology that can help decrease the dependence of the U.S. aluminum industry on imported bauxite, the main ore of aluminum, the Bureau of Mines is investigating the extraction of aluminum from abundant domestic reserves of kaolinitic clay. Miniplant studies of the continuous leaching of calcined kaolin with boiling 25-pct HC1 acid resulted in a 93- to 99-pct extraction of the acid-soluble alumina in the calcined kaolin feed. Data are presented for an acid leaching study carried out in three or four continuously stirred tank reactors (CSTR) in series, feed rates of 100 to 250 lb/hr of calcined kaolin, and total nominal residence times of 0.7 to 2.3 hr. A material balance for a 176-lb/hr calcined kaolin feed rate in a circuit consisting of three reactors, four classifiers, and five thickeners is given. Data provide detailed compositional and physical information for calcined kaolin, process liquors, and acid-leached residue solids.

Jan 1, 1983

By Fred Mosley

The present operation is located on Whitewood Creek about two miles downstream from Deadwood, South Dakota. Early day placer gold operations took place on this creek from Crook City to an area several miles upstream from Deadwood. Early discoveries were in the Deadwood area. In this particular zone, much of the early work was accomplished at stream level and at various elevations above. In the original operations, it was not possible to reach bedrock in many places due to the ground water level plus the existence of numerous large boulders in the same area. The bedrock in this area is approximately twenty feet deep, consisting of Cambrian and Ordovician sediments. Shortly after the early operations began, many small lode mines and several larger mines released mill tailings directly into Whitewood Creek. This practice continued for a full century, thereby limiting the amount of clean water available for sluicing. These tailings in the stream carried large amounts of heavy minerals along with the natural heavier minerals introduced from erosion and were immediately caught in the riffle boxes, resulting in the suspension of many small sluicing operations. No large scale sluicing or mining was ever done at bedrock level in this area, resulting in an almost virgin placer gold deposit. The old tailings cover much of the area, contributing an additional deposit carrying appreciable gold values. In recent years, a company known locally as New Era Mining Company attempted with some success to exploit the area at bedrock level. The equipment used included a Marian dragline with. a three- yard bucket, a washing trommel mounted on a 40 ft by 20 ft floating pontoon barge, together with two banks of Humphrey Spirals and a secondary spiral for collecting concentrate from the two primary

Jan 1, 1983

By Sushil Bhandari

Presented here is the simplified process of fragmentation of homogeneous rocks by blasting based on experimental studies. Small scale single hole blasting experiments on jointed limestone are described. Results show that directions of joints overshadow the degree of fragmentation and also influence the remaining rock. The possible influence of joints on the process of fragmentation of non-homogeneous rock by blasting is also discussed.

Jan 1, 1983

By Randal J. Barnes

A system, such as a mine production system or a mine ventilation system which includes the movement of commodities or some material between decision points may, in many instances, be effectively modelled as a network. Mining has often been characterized as primarily a materials handling function. To a great extent this is true, even though it is an over simplification of all the activities involved in a mining operation. Accepting the materials handling characterization of a mining operation permits the extension of the characterization to a flow process. That is, the ore flows from the mining face through the mining phase (excavation & loading, hauling, dumping) through the milling phase (crushing, grinding, recovery) through the smelter phase and finally to marketing. With this concept it is possible to depict a mining operation as a simple network. For example consider an operation consisting of two mines (A and B) with mills at each mine (MA and MB) with the possibility open to treat ore from mine b at mill NB, but it is not feasible to treat mine B ore at MA. The product of both mills is sold.

Jan 1, 1983

Develop a metal substitute which is more plentiful and less expensive than the metals currently being used in high performance, permanent magnets, while maintaining the quality of the magnet. The New Alloy The rare-earth metal used in most high performance magnets is samarium, an expensive metal of limited availability. Cobalt is also used in high performance magnets, but supplies of this metal also are limited because it is not domestically mined and must be imported. The Bureau of Mines embarked on research to find a less costly domestic: metal source for use in industrial magnets. The alloy found most promising consists of mischmetal, a relatively abundant, naturally occurring mixture of rare-earths, which can be used as a replacement for samarium. Additives of copper, magnesium and iron used in combination with mischmetal aid in replacing some of the cobalt needed for the magnets.

Jan 1, 1983

Extensive infrastructure construction works were required for the development of the underground and open-cut coal mine at Ulan to a production capacity of 5 million tonnes of steaming coal per annum. The Ulan Mine development project was constructed in a two year period at a cost of $240 million. The infrastructure component included the construction of the mine site building works, civil works and 150km of railway, valued at $105 million. These works were successfully completed under a construction management agreement within two years. The separate elements of the project are described in detail in the paper.

Jan 1, 1983

By F. W. Metzger

INTRODUCTION Coal quality control in mining and mine planning has always been important and has become even more essential in recent years due to environmental considerations. The primary consumers of the sub-bituminous coals found in the Powder River Basin are electric utilities that require low sulfur coals to meet government air quality regulations. Electric generating plants are designed to burn coal of a specific quality, and the supplier of that coal must be able to guarantee shipments within specified quality tolerances. Over the past several years, Exxon Coal USA and, more recently, The Carter Mining Company, a division of Exxon Coal USA, have established an evaluation and development program to accurately define the geology and quality of their coal properties. This requires an adequate drill hole density so that detailed correlations of the coal seam and the lithologic units, or benches, within the coal seam can be made. These units are recognizable in the core and also on geophysical logs. Like any systematic approach, geologic modeling has been refined and improved through new technologies. Today, coal seam properties are mapped using computer applications. Rapid access and manipulation of these data allow for optimization of mining efforts. This presentation will demonstrate how a detailed mapping program can be important in both pre-mine development and in-pit quality control.

Jan 1, 1983

By David A. Paul

Over the past several years a great deal of information on blasting vibrations and their effects on structures has been generated. Much of this knowledge has been gained through the use of ground vibration measuring equipment. While this type of information is valuable and gives us great insight into damage that can be incurred by structures from this source, very little, if any, information of this quality is available for the vast majority of cases in which an engineer is called upon to investigate alleged damage from ground vibrations. For the investigative engineer, then, the problem becomes one of accumulating whatever data is available and drawing a conclusion as to whether or not the subject structure was in fact damaged by the blasting vibrations. Such an analysis certainly requires a working knowledge of the literature on the subject and as much experience as he can bring to bear. Even thus armed, however, the data is often ambiguous, confusing, and/or contradictory. A practical approach is presented herein to aid the engineering investigator in arriving at the best possible conclusion available with the information at hand.

Jan 1, 1983

By James M. Barker

Sulfur is a nonmetallic element of great physical and economic importance to the world. It is widely but sparingly distributed throughout the hydrosphere, lithosphere, and biosphere. Sulfur is the tenth most abundant element in the universe and eighth most abundant in the sun. In the earth's crust, which is mainly igneous, it ranks 14th, but is eighth or ninth in sediments (Kaplan, 1972; Stanton, 1972). It apparently is very abundant in the core of the earth, because it is a strong chalcophile, and it is fifth in abundance in stony and iron meteorites (Field, 1972) where it occurs as trolite (FeS). In ancient times sulfur was called brimstone, literally "burning stone." Today the term brimstone is used interchangeably with the term elemental sulfur. Shelton (1979) summarized most of the common definitions of terms, grades, and specifications for the sulfur industry as follows (with minor additions): Sources of Sulfur: Combined sulfur-Sulfur that occurs in nature combined with other elements. Cupriferous pyrites-Pyrite containing relatively minor amounts of copper sulfide minerals. Hydrogen sulfide-A toxic gas (H2S) occurring in natural gas and petroleum. Involuntary sulfur-Sulfur produced primarily as a result of legislative or process mandates. Native sulfur-Sulfur that occurs in nature in the elemental (uncombined) form. Nonferrous metal sulfides-Copper, lead, zinc, nickel, and molybdenum sulfides that are processed for their metal content. Organic sulfurs-Complex organic sulfur compounds occurring in petroleum, coal, oil shale, and tar sands. Pyrites-Iron sulfide minerals that include pyrite, marcasite, and pyrrhotite. Sulfate sulfurs-Sulfur in anhydrite and gypsum. Voluntary sulfur-Sulfur produced in response to market forces. Basic Sulfur Products Produced and Marketed: Acid sludge-Contaminated sulfuric acid usually returned to acid plants for reconstitution. Brimstone-Synonymous with crude sulfur. Bright sulfur-Crude sulfur free of discoloring impurities and bright yellow in color. Broken sulfur-Solid crude sulfur crushed to -8 in. Byproduct sulfuric acid--Sulfuric acid produced as a byproduct of a metallurgical or industrial process, generally relating to combined sulfur sources. Crude sulfur-Commercial nomenclature for elemental sulfur. Dark sulfur-Crude sulfur discolored by minor quantities of hydrocarbons ranging up to 0.3 % carbon content. Elemental sulfur-Processed sulfur in the elemental form produced from native sulfur or combined sulfur sources, generally with a minimum sulfur content of 99.5%. Formed sulfur-Elemental sulfur cast or pressed into particular shapes to enhance handling and to suppress dust generation and moisture retention. Frasch sulfur-Elemental sulfur produced from native sulfur sources by the Frasch mining process. Hydrogen sulfide-Associated with natural gas or petroleum and produced at refineries and coke oven plants; used to make sulfuric acid or recovered sulfur. Liquid sulfur-Synonymous with molten sulfur. Liquid sulfur dioxide-Purified sulfur dioxide compressed to the liquid phase. Molten sulfur-Crude sulfur in the molten phase.

Jan 1, 1983

By J. O?Hanlon

The 4500 m3 blast furnace at the Redcar Works of ESC operates or, a burden of sinter and pellets, both materials being produced within the works. The early history of the furnace was given to the AIME Ironmaking Conference in 1981(1) when the burden was 65% superfluxed minter and 33% acid pellets. While ironmaking performance was adequate, it was felt that there were advantages to be gained by the use of fluxed pellets. For example, Kobe Steel had reported (2) that the rise of 30-50% dolomite fluxed pellets had enabled them to achieve better furnace permeability, higher gas utilisation, and enhanced ore/coke ratios. It appeared probable to BSC that the use of magnesia-bearing fluxed pellets would give a burden which had compatibility of softening and melting properties, i.e., fluxed sinter and dolomite pellets would result in a thinner cohesive zone because of closer matching of softening and melting temperatures, with consequential benefits on furnace stability and efficiency.

Jan 1, 1983

By James H. Neisz, Gregory P. White

This paper discusses the development of surface coal mine planning programs for a microcomputer. A set of seven programs which were originally written for a large mainframe computer are described. The problems encountered in converting these programs to a micro with 52K of available core storage are discussed. A program for economic evaluation which is currently running on the micro is described and plans to convert other programs to the micro are detailed. In addition, we explain the microcornputer system we have assembled and give the rationale for each component. Problems we have encountered with this system are described for the benefit of others who may follow our path.

Jan 1, 1983