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By Kirk P. Kinart

The mid to late 1980s saw a modern day global gold rush that largely focused on the mature mining countries of the United States, Canada and Australia. This gold rush led to a large number of new discoveries in these countries and phenomenal growth rates in annual gold production. For a variety of reasons, however, gold exploration and development activity appears to have peaked in these countries. The drive for mineral investment is, instead, growing in lesser explored countries (LEC). LECs, particularly those of Latin America, are currently enjoying greatly increased attention from North American mining companies. They are becoming major consumers of mineral investment capital and are important markets for exploration and mining skills. Through sole ownership, joint ventures and subsidiary companies, Battle Mountain Gold now operates or controls gold mines in the United States, Chile, Bolivia and Australia. And it has been or is an active participant in gold exploration or development projects in seven other countries, six of which classify as LECs. In selecting new country entries and opportunities for mineral investment, there are several factors to be considered and parties to be satisfied - shareholders, corporate management, financial institutions and host country governments. This article, though, focuses on some of the more practical concerns of the exploration unit as a whole and the exploration geologist in particular. The exploration unit's "new country" concerns primarily relate to exploration potential, ownership security, quality and availability of data and the ability to operate efficiently. The following material reviews each of these concerns and how they impact the new country entry decision, exploration strategy, chances of success and human experience.

Jan 1, 1993

By E. Açma

Sivas-Divrigi flotation plant has a capacity of 90,000 tpy. Beneficiation of the tailings of iron ore magnetic separator seems to be attractive, because of its Cu, Co, and Ni contents. In the experimental work, sulfidic flotation concentrate is produced from these tailings. A roasting-leaching-H2S precipitation procedure is used to treat this concentrate, containing 0.55% Cu, 0.51% Co, 0.74% Ni, and 0.027% Zn. Sulfatizing roasting is carried out in a rotary furnace at 690°C. Roasted product is leached with 10 gpl HzSOl at 70°C and 30% pulp density. For the precipitation of desired metal, H2S is bubbled through the concentrated solution of repeated leaching, under controlled temperature and pH. Final metal recoveries of 91% Cu, 91% Co, and 50% Ni, and 92% Zn are attained. Roasting gases with their 13% SO2 content are suitable for H2SO4 production and the leach residues can be integrated with the iron ore processing plant as they contain 57.4% Fe and very low non-ferrous metals.

Jan 1, 1993

By Ronald J. Vance

One of the key elements of change in the mining industry has been the ever-increasing integration and coordination of previously highly segregated business disciplines, the extent to which the marketing and finance functions have evolved and merged within the mining industry. If one listens to the language of mine product marketers today, one hears terms like contango, backwardation, forwards, options, min/max, synthetics, swaptions, caps, collars, FRA's, spot deferreds, double bottom, head and shoulders. The list is endless and a glossary may be out-of-date even before the ink is dry. No longer can a marketer of mine products get through the day and, more importantly, keep his or her job merely by reciting statistics on supply, demand, prices and the jargon of quotational periods, delivery and payment terms. Walk into the office of any marketing department today, and computer terminals spewing on-line market prices and instantaneous news retrieval command the attention of all who enter. Traditionally, mining companies, particularly those in North America, took a passive view toward marketing their products and an even more passive view toward management of price risk. The typical, albeit simplified, gold producer of the 1970s and early 1980s spent all of its energy exploring, delineating, developing and producing a product that was placed by the mine gate. Like magic, anonymous buyers took it away and left piles of dollars in its place. No fuss, no muss and nothing to get in the way of more exploring, delineating, producing etc. The typical copper producer, meanwhile, was slightly more creative. Copper producers still spent most of their energy exploring, producing etc., but they at least acknowledged the identity of their customers. Many even went so far as to fabricate finished mine products into shapes and sizes that their ultimate customer needed. Wire, cable, sheet and extrusions were all in forms ready to be purchased by power companies, motor manufacturers and telephone companies. But, while production and costs steadily increased, research and development into new expanding markets was funded by little more than lip service. Competitors and competitive products steadily eroded market share and realized prices. The now-famous Business Week magazine cover that proclaimed "The Death of Mining" was an imminent reality.

Jan 1, 1993

The metallogenic map of New Zealand shows the distribution of metallic mineral deposits, according to type and size, in relation to their geological setting. The major purpose of the map and accompanying 200-page monograph is to summarise the distribution, modes of occurrence and origins of the metallic mineral deposits of New Zealand. The map demonstrates the prospectivity of New Zealand for metallic minerals, particularly gold, silver, iron, and titanium. Information on each deposit is summarised in index tables based on major geotectonic units or deposit/commodity type. The mineral deposits are arranged and discussed in relation to tectonostratigraphic and tectonomagmatic units or terranes, under broad geotectonic divisions of the Paleozoic to Mesozoic Western Province, the late Paleozoic to Mesozoic Eastern Province, the mid Cretaceous to early Tertiary rifting phase, and the late Cenozoic Kaikoura Orogen. Regions or areas of marked concentration of mineralisation are recognised as metallogenic subprovinces or districts, namely: eastern Northland (Hg), the Hauraki Goldfield (epithermal Au-Ag-Pb-Zn-Cu), the west coast of the North Island (shoreline placer Fe), east Nelson (podiform Cr), west Nelson (porphyry Mo), the West Coast of the South Island (shoreline placer Ti), west Nelson-Westland (placer Au), Reefton (mesothermal Au-quartz veins), and Otago (placer Au and mesothermal Au-W quartz veins).

Jan 1, 1993

By S. J. Jung

The prime criteria in the design of underground openings with complicated geological structures is ground control. Stability of underground openings for deep mines is critical because incorrect orientation or geometry of shaft, stope, and accessways often results in the failure of openings due to high stress conditions. Current design procedures for complicated orientation and geometry of mines are rapidly becoming inadequate as mines are being developed. In this study, finite element method has been used with optimization criteria to design more stable and safe underground openings.

Jan 1, 1993

By G. S. Bartlett

The theme of this Colloquium, survival strategies, not only conveys a sense of urgency but also takes cognizance of the fact that, as in the political arena, tough decisions have to be made and acted upon in the years to come. It is therefore appropriate that the SAIMM, as spokesman for the metallurgical industry, should be dealing with these issues at this time, and I wish to commend the organizers of this Colloquium for focusing on a mater as important as the future of this great industry. In view of this, I regard it as an honour and privilege to officiate on this occasion, where the best of South Africa's brain power in the metallurgical field will be harnessed with a view to moulding strategies for survival.

Jan 1, 1993

By J. E. Hoffman, T. J. Keefe, Michael E. Stout, O&apos

M.A. Industries, Inc. has developed and is now offering on a commercially available basis, complete systems to recover and recycle lead from spent SLI batteries. The system begins with the breaking and separation of the component parts of the batteries and subsequent treatment of the effluent water produced by this operation. The recyclable materials recovered from this process are metallic lead, lead paste and polypropylene. The lead paste is introduced into a process to convert it from a lead sulfate to a lead carbonate. The process also regenerates the salt solutions into reusable carbonate. The lead carbonate is then leached into an acid bath where it is later recovered by a proprietary electrolytic process. The metallic lead is recovered in a short rotary furnace producing metal for further refining and alloying. The polypropylene is further washed and then introduced to a reclaim extruder along with the proper modifiers and additives. The resulting resin can then be sold on the open market to injection molding processors. This complete system greatly reduces the amount of waste to be disposed of and completely complies with all applicable EPA guidelines.

Jan 1, 1993

By K. S. Olson

My reaction when first asked to present this paper was; "What could I possibly say that would hold the audience?s attention for 15 minutes? What could I offer that anyone familiar with the Nevada Barite Industry wouldn't already know?" Well, quite frankly I can't. The industry has certainly been anything but exciting for the past 10 years and, in fact, quite depressing. The challenge, for those few of us left in it, has been to keep it alive. At times it has felt like a doctor must feel with a terminally ill patient. All I can do is recap the past ten years, review the present state of the industry, and offer a few personal opinions and observations as to where I think we are headed.

Jan 1, 1993

By David A. Newman

Strength and physical property testing of coal is conducted regularly by the Arch Mineral Corporation as part of reserve exploration. Pillar design and mine layout are the primary applications for the coal strength data. Distinct differences in pillar behavior were observed during longwall mining at a mine in Southeastern Kentucky. Horizontal and vertical variation in both triaxial and uniaxial compressive strength was observed within the four (4) benches of the Harlan seam. Similarly, geographical variations in coal strength were noted across the Harlan seam reserve. During the past three decades substantial research efforts have been focused upon coal pillar behavior and the refinement of pillar design methodologies. Ironically, little attention was directed to integrating the variability of coal strength into pillar design. The authors examine, through the presentation of case history data, i) typical industrial practice with respect to establishing a database of coal strength for use in pillar design and stability analysis, ii) approaches in which the observed variation in strength in the Harlan seam is integrated into pillar design and stability analyses, and to iii) propose standards for coal cube testing

Jan 1, 1993

By L. G. Sobral, J. E. Hoffman, T. J. Keefe, A. J. Monhemius, O&apos

The kinetics of electrodeposition of gold from dilute solutions of alkaline KAu(CN)2 at different gold and free cyanide concentrations on a gold rotating disk electrode were investigated by use of a steady-state linear potential scan technique. The design and performance of a laboratory electrowinning cell with a reticulated nickel cathode, operating in the flow-through mode, for the removal of low levels of gold ions from aqueous cyanide media is described. During the batch recirculation of oxygen-free gold cyanide solutions, the gold concentration was reduced from 10 ppm to <0.5 ppm with current efficiencies of up to 80%. The influence of solution flow rate through the cathode and of the pore size of the reticulated nickel foam is discussed. The removal of gold ions from solutions of low ionic strength was also investigated.

Jan 1, 1993

By N. J. Poll

The Zacarias gold-silver-barite deposit appears to be a Precambrian analogue of present-day exhalative deposits on the sea floor. Geochemical, stratigraphic and structural studies of the latter can be useful in elucidating the ore environment at Zacarias, thereby assisting exploration. The Zacarias mine is about 300 km north of Brasilia, within the Goiás Massif, Brazil. It is the southernmost of three auriferous quartzite occurrences along 1 km of a northeasterly striking amphibolite. Zacarias and its neighboring smaller deposit to the north, the Central Pit, contained a premining ore reserve of 650,000 tons at 4.4 g/t gold, 48 g/t silver, and about 20% barite. Gold mineralization is hosted by concordant quartzite strata also containing layered barite, pyrite, barium-mica, sphalerite, galena, chalcopyrite, magnetite, sulfosalts, free gold, and electrum. The host amphibolite is intercalated with barren mica-quartz-chlorite-pyrite schists that are more voluminous in the footwall and are associated with the ore horizons. Above the amphibolite in the hangingwall lies a thin graphitic shale, then a feldspathic arenite. The strata and regional foliation strike northeast and dip 42° northwest. Crenulation and small-scale folds plunge 30 to 40° to the west.

Jan 1, 1993

By D. G. Krige

Recent publications have demonstrated the important role that can be played by a priori information of the grade levels, variability, and spatial patterns in adjacent or nearby areas in improving the quality of grade estimates for virgin or sparsely drilled areas. A research project was therefore conducted involving the collection and analysis of extensive sampling and borehole data from 7 reefs on some 30 Witwatersrand mines. This paper shows that the &apos;equivalent&apos; log variance for the two-parameter lognormal model provides a good basis for the study and comparison of the levels and behaviour of relative variances. The trends of these against the corresponding log areas were found to form distinctive patterns, which are useful for these purposes. The patterns for the Basal, Vaal, Carbon Leader, and Main Reef Series form a reasonably close group, whereas those for the V.C.R.(particularly where the facies are mixed), B Reef, and Kimberley-Elsburg Reefs (particularly for narrow channel widths) do not always conform. The patterns shown by underground chip samples are also compared with those obtained from borehole cores. It is shown how this information can be used to improve the borehole valuation of new mines and of virgin areas in existing mines.

Jan 1, 1993

By T. T. Chen

Raw anode slimes consisting primarily of PbSO4, AgCuSe, Cu3Se2, Cu2-x Se, Cu2O, CuSO4.5H2O, Sn arsenate and Sb-Bi-As oxide are batch-leached with electrolyte-O2 to dissolve Cu. During this process, Cu2O and CuSO4.5H2O are solubilized and the Cu in the selenides is leached with the formation of Ag2Se and Se. A small amount of Cu remains in the Ag2Se, Sn arsenate and Sb-Bi-As oxide. The decopperized slimes are repulped in Na2CO3 solution to convert most of the PbSO4 to NaPb2(CO3)2(OH). The Sn arsenate and Sb-Bi-As oxide partly react, but the Ag2Se is not significantly affected by the Na2CO3 solution. The NaPb2(CO3)2(OH) intermediate phase is dissolved in acetic acid to leave a final product consisting of Ag2Se, Se, Sn arsenate and Sb-Bi-As oxide, together with small amounts of PbSO4, NaPb2(CO3)2(OH) and various gangue constituents.

Jan 1, 1993

By M. A. Trevits

Methane gas is an ever-present problem facing the underground coal mining industry. Mine operators are mandated by law to maintain safe concentrations of methane gas within the mine environment. Ventilation is used by all mine operators to reduce gas concentrations. When gas emissions are such that ventilation alone cannot control the gas, methane drainage methods must be applied. In the 1970&apos;s, there was a concern that unprecedented gas emissions would be experienced as mine operators began new developments in the deep and gassy Blue Creek and Pocahontas No. 3 Coalbeds. Such concern was well founded as significant gas volumes are being emitted as these mining operations mature. In 1971, the O.S. Bureau of Mines began to tabulate and track the change in mine emissions. These data were extracted from the underground coal mine quarterly air quality-quantity inspections performed by the Mine Safety and Health Administration. At that time, approximately 6,560 Mm Id (231.7 MMcfd) of gas were emitted from 430 underground coal mines. It was determined however, that the mines emitting less than 2,832 m Id (100 Mcfd) contributed only 2.1 percent of the total daily gas flow. In 1988, underground coal mines emitted 8350 Mm Id (294.9 MMcfd) from 487 mines. This report evaluates the changing nature of U.S. mine gas emissions over the last 18 years.

Jan 1, 1993

By Jacqueline A. McClaskey

The U.S. Bureau of Mines Information and Analysis Directorate collects worldwide data on virtually every commercially important non fuel mineral commodity. These data form the base for tracking and assessing the health of the minerals sector of the U.S. economy. The Bureau&apos;s data collection activity was instituted by the 47th Congress in an appropriations act of August 7, 1882 (22 Stat. 329), which placed the collection of mineral statistics on an annual basis. The most recent authority for the U.S. Bureau of Mines survey activity is the National Materials and Minerals Policy, Research and Development Act of 1980 (Public Law 96-479, 96th Congress). This act strengthens protection for proprietary data provided to the U.S. Department of the Interior by persons or firms engaged in any phase of mineral or mineral-material production or consumption.

Jan 1, 1993

By M. J. Virnig, Marc Le Vier, Rong Yu Wan, Jan D. Miller

Although most gold production from primary resources is achieved by cyanidation, many research activities have focused on alternative processes using noncyanide lixiviants. Such research has been prompted by environmental concerns and problems associated with the processing of refractory gold ores. Numerous research projects have been conducted to search for a noncyanide hydrometallurgical process for gold extraction. In this paper, a technical review of gold recovery from noncyanide solutions is presented, and new results are reported. Gold recovery techniques that are considered include activated carbon adsorption, cementation, solvent extraction, ion exchange, and reduction-precipitation.

Jan 1, 1993

The continuous casting of zinc alloys has been of fundamental importance for many years in the production of a number of products, including sheet for architectural applications, battery cans for dry cells and wire for metallising. The intrinsic benefits of continuous casting, including efficiency and high tonnage capability, uniformity of metallurgical structure and properties, and absence of voids and other defects, have contributed to the success of these products. Less well known, but of growing importance, is the more recent application of continuous casting technology to the production of zinc alloy bar stock products, including bearing stock, machining bar stock, forging stock and cathodic protection anodes. A wide range of zinc alloys are now continuously cast in a variety of cross sectional shapes and sizes to suit the diverse characteristics of these products. Of particular significance are the introduction of hollow zinc-aluminum bearing stock, and the availability of zinc alloy machining bar stock for hydraulic applications and for producing prototypes of zinc alloy pressure die castings. In addition to the traditional benefits, continuous casting provides special properties which are important in the application of these bar stock products. The list of successful applications of continuously cast zinc alloy bar stock is growing rapidly, and the market potential for resultant new zinc applications appears to be significant.

Jan 1, 1993

By Michael H. Leon, John A. Organiscak

Controlling worker dust exposure on longwall mining systems is difficult because the working face area serves as an immediate return during the mining cycle and the amount of airborne dust generated is directly related to production. Since improvements in longwall mining technology have significantly boosted production levels, additional technology is needed to control the airborne respirable dust generated at present and future production levels. One concept to reduce longwall worker&apos;s dust exposure is to maintain two splits of air at the face -- a clean intake split in the workers walkway, and a return (dusty) split over the face conveyor. The U. S. Bureau of Mines has recently investigated a concept to overcome the visibility handicap of face partitions by utilizing a permeable polyester mesh. The mesh material was anticipated to provide adequate air-splitting capabilities as long as the pressure differential between the face and worker walkway was minimal. Initial testing of this concept at the Bureau&apos;s Lake Lynn Laboratory showed that notable reductions could be achieved with a 1/8 in (3.18 mm) and 1/16 in (1.59 mm) mesh opening size. Dust reductions at 100 ft (30.5 m) and 200 ft (61.0 m) downstream of source were 58 and 36 pct, respectively, for the 1/8 in mesh and 79 and 55 pct, respectively for the 1/16 in mesh. Longwall application of the 1/8 in mesh showed similar results to the Lake Lynn Laboratory tests. A flame retardant mesh was used underground with portable lighting mounted on the shearing machine for face side lighting.

Jan 1, 1993

By C. A. Garcia

The solvent extraction of gold cyanide from alkaline cyanide solutions with monosubstituted guanidines, bis disubstituted guanidines and a tetrasubstituted guanidine was investigated. The guanidine functional group is protonated in alkaline solution and the guanidinium cation is stabilized so that the aurocyanide anion can be extracted even at -pH 12 if an appropriate carrier is used. Typical aprotic carriers including both aliphatic and aromatic solvents limit gold extraction by guanidines to pH 10; whereas the presence of an alcohol extends gold extraction to pH 12. UV spectroscopy suggests that the alcohol facilitates protonation of the guanidines, stabilizes the guanidinium cation, and facilitates gold extraction at high pH.

Jan 1, 1993

Among countries afflicted with insLantaneous outbursts of coal and gas, Australia is noteworthy because of lesser disturbances of the seams and of the occurrence of CO2 in the seam gas from place to place. Research sLarted with the 1954 occurrences at Collinsville and Metropolitan Collieries leading to early publications reviewing the problem, describing occurrences and assessing variations in proneness factors in the two affected coal basins.The basic requirements for proneness include coals of high gas sorptive capacity, high ground stress, use of a mining method which provides higher stress concentrations and limits emission of seam gas, including high rates of advance. With CO2 in the seam gas proneness is greater.The mechanism is complex and not fully understood, but involves the coal, the roof, the floor, the gas, the mine opening, the ventilation, the kind of work and the rate of work. Geological disturbances such as faults and dykes increase proneness and tend to localise occurrences. On-occurrence of outbursts in some mines is difficult to explain.Outbursts are seen as a continuing threat to modem deep Australian mining of high rank coal.The simplest contributory factor to reduce is gassiness - despite the low permeability of outbursting coals - and present practices are showing promise. The greatest challenges for the future are partial degasification to below a known threshold figure and confirmation that this reduction is achieved and identification of anomalous geological structures ahead, the most likely locations for instantaneous outbursts to occur. The advances made to date give promise of a future with reducing experiences of uncontrolled instantaneous outbursts. For the Bulli seam particularly, working to achieve prediction and prevention is most urgent.

Jan 1, 1993