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By John Durkin

The Bureau of Mines has conducted field studies in coal mines through- out the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident. Data from these tests have been used to generate models of expected signal and noise distributions as found above mines throughout the coalfields. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results show that at a 10-pct false alarm rate, the expected probability of detecting a miner's signal from a depth of 1,000 ft is 54 pct; at 500 ft it is 95 pct. These depths exceed the actual depths of 90 pct and 50 pct, respectively, of U.S. coal mines. Sensitivity studies have shown that at a depth of 1,000 ft, for every 3 db of improvement in signal-to-noise ratio, the probability of detection increases 6 to 8 pct.

Jan 1, 1982

By Prescott Greene

AVAILABLE MACHINES Machines discussed in this section include only rubber tire mounted kerf cutting machines of a self¬propelled electrically powered design. Such machines handle bars up to 4.6 m (15 ft) in length, cutting kerfs of from 115 to 191 mm (4.5 to 7.5 in.). The basic design concept of all machines currently in production is very similar. The chassis features dual driving wheels on the cutter-bar end, fixed directly to the main frame. The steering wheels on the outby end of the frame are articulated in some manner to keep all four wheels on the floor over uneven bottom. Machine power for tramming, and all other functions except powering the cutting chain, is furnished from a pump motor that drives the specific pump or pumps required by a given machine. The cutter chain is driven through a mechanical drive train from a separate electric motor having no duty other than driving the chain. The general arrangement of a cutting machine is shown in Fig. 1; two types of machines, with their specifications are shown in Figs. 2 through 5. A hydraulically powered cable normally is included to eliminate the need for manual cable handling and make this a one-man machine. A bug duster, though optional, is needed for most applications. The bug duster is an hydraulically driven scroll conveyor located directly behind the cutter chain drive sprocket. Its function is to move the cuttings away from the sprocket to prevent them from packing up in this area and consuming a lot of machine power to further pulverize them. Available machines vary from models 610 mm (24 in.) high that can cut horizontally only from 203 mm (8 in.) below ground line to 229 mm (9 in.) above, to machines 1143 mm (45 in.) high that can cut in any plane from 178 mm (7 in.) below the ground line to 3.7 m (12 ft) above it. Most currently manufactured machines fall in the 17 200 to 20 400 kg (38,000 to 45,000 lb) weight range, but can be dis¬assembled for underground installation where weight and size are a problem. Maximum teardown results in all pieces having a weight of 5400 kg (12,000 lb) or less and a size allowing passage through a 1.2 x 2.1-m (4x7-ft) opening. Further reduction in either size or weight of the parts becomes a serious problem. Machines currently being manufactured are avail¬able for use with power supplies of 250 v dc; 500 v dc; 440, 550, or 950 v ac (60 Hz). Also available are machines for use on 415, 500, and 950 v 50 Hz. De¬signs to allow operation on other voltages of either 50 or 60 Hz can be made available without any serious problems. As of September 1977, a typical medium-seam ma¬chine without the extra options needed for unusual conditions, but fully equipped to operate, was selling for about $185,000. CAPABILITIES Materials That Can Be Cut The problem of deciding before a machine is put on the job whether it can work effectively is an old one that has never been completely solved and probably

Jan 1, 1982

By John H. White

As production of ground limestone increased our Company found it had an enviromental problem with limestone dust from our hammer mills. With the quarry and processing plant situated within 1 klm of a small township of 5000 people dust collection became essential. Regulations under the Clean Air Act 1972 also had to be complied with. Prior to this any demand for lime flour had been met by the use of a small drier and ball mill. Both expensive to operate. Dust emitting from the mills would amount to over 4000 tonnes per year. The cost savings were obvious. We had a better product which was essentially a by-product. Faced with a surplus of a very useful, but difficult product to handle we considered the possibility of disposing of it on the agricultural market.

Jan 1, 1982

By J. P. Schmid

Results of a comprehensive investigation of the impact of underground mine waste disposal on the health and safety of miners are presented. Information was gathered through an extensive search of American and foreign literature and personal communication with professionals in private industry and government. All conceivable health and safety hazards directly or indirectly related to underground mine waste disposal are analyzed, catagorized, and ranked on an industry-wide basis. Positive health and safety effects are analyzed and ranked in a similar way. Both potential and known hazards and positive impacts are included. Recommendations on abatement techniques for the various hazards are presented. Case histories of a fill-related accident in a metal mine and a health hazard associated wtih coal waste backfilling are included and causes and possible abatement procedures are discussed. The rule of management in the promotion of health and safety in backfilling operation is discussed.

Jan 1, 1982

By Stanley M. Miller

The probabilistic nature of appropriate geologic variables can be included in analyzing the stability of potential slope failure modes. Random variables in the two-dimensional plane shear analysis of a specified structural discontinuity include the shear strength and waviness angle of the discontinuity and, in some cases, the rock mass density. Estimated probability density functions that describe these random variables are combined by Fourier analysis to produce an estimate of the safety factor probability density function, which appears to approximate a gamma distribution. The probability that sliding will occur along the specified structure is equal to the area under this density function where the safety factor is less than one.

Jan 1, 1982

By Allen D. Graham

The coal industry in South Africa is briefly outlined. Test- work carried out on bulk samples of coal in the laboratory and used in the design of the Van Dyks Drift washery are described. Factors affecting the selection of equipment and the designed capacity of the plant are discussed. A description of the crushing plant, washery and load out section is given together with performance data obtained in the final acceptance tests. New features incorporated in the Van Dyks Drift plant and in more recent plants of the Group are outlined.

Jan 1, 1982

By Edward F. Divers

Face ventilation is generally the most critical area in the coal mine ventilation system. Various studies have repeatedly shown that good ventilation is by far the most effective and least costly method of controlling dust and gas problems created during face operations. The Bureau of Mines has recently developed and assisted in the development of several new concepts in face ventilation systems, and in methods to accurately evaluate these systems underground. A new type of scrubber and ventilation system design built into the auger support frame of a continu- ous miner was developed. The objective was to improve face ventilation and reduce respirable dust concentrations. With this arrangement, one scrubber is mounted into each side of the boom. Laboratory and underground tests of various scrubber discharge arrangements showed good to excellent dust and methane control. Combined face ventilation systems, using both blowing and exhaust curtain, potentially offer dust and gas control and deeper cutting. Bureau tests at a mine using a combined face ventilation system and remote- control-operated continuous miners showed excellent dust and methane control. The advancement of line curtain systems beyond permanent supports without exposing workmen to roof fall hazards can be accomplished only with specially designed extendable devices. Numerous concepts for line curtain extension have been developed and tested. For the past several years, the Bureau has been testing various types of extensible face ventilation systems. These extensible systems can generally be classified as floor-, roof-, machine-, and rib-mounted systems. In the past 6 years, approximately 40 systems have been evaluated for feasibility. From these, several have been selected as practical or innovative and are presented herein. A technique developed by the Bureau to accurately and safely evaluate the effectiveness of face ventilation is also presented.

Jan 1, 1982

By Woodcock JT

This paper deals with some innovations and current proposals for the treatment of gold ores and considers the possibilities of incorporating new developments in new or revised ore treatment flowsheets. The main topics considered are I. typical practice in relation to the size of gold particles, 2. concentration of coarse gold, 3. leaching reagents, 4. in situ leaching, 5. heap leaching, 6. carbon-in-pulp adsorption, and 7. treatment of complex ores (gold in pyrite, gold tellurides, and carbon-containing ores).

Jan 1, 1982

By Dirk A. Benham, William A. Warfield

INTRODUCTION Whenever a mine operator is faced with a decision between various mining methods or even equipment selection, he must be assured that his decision will have a positive effect on his economic operating goals. For instance, if a mine operator has a choice of using an LHD mining system or a slusher mining system, then his decision to use either must not only fit within the operational limitations of the mining plan (such as production requirements, physical features of the ore body, mine plant facilities, manpower requirements, etc.), but also assure that the ore is being extracted at the least possible cost. To aid in his decision making process, the operator will commonly compare acquisition costs, operating costs, maintenance costs, and the operational advantages and disadvantages of each system in addition to considering his personal observations and feelings. A decision to select a mining system using only those criteria aforementioned will not necessarily lead the operator down the path to maximizing profits. In addition, the operator should also compare the economic effects of each system upon the overall mining operation. A relatively simple method for determining the economic effects is to calculate and compare the break-even grades for each system under consideration. By implementing such an analysis, the operator can now select a mining system which can operate within the limits of the mining plan as well as extract the ores at the least possible cost, thus yielding maximum profits. This paper will present the geologic and physical conditions of a mine being operated by the Hypothetical Mining Company in the Grants Mineral District. An LHD and Blusher mining system are under consideration and are compared by examining operating costs, equipment availability, and the conventional operational advantages and disadvantages of each. Finally, the economic effects of each system upon the overall mine's operation are compared by utilizing break-even grade analysis. DESCRIPTION AND MINING METHODS The Hypothetical Mining Company has located an ore body in the Grants Mineral District. After extensive surface exploration drilling and cost considerations are evaluated, it is decided to open a mine. The following tasks must now be performed: 1. outline ore body and it's basic characteristics, 2. look at mining methods currently in use in the area, and 3. determine mining techniques and methods for exploitation of the ore body. For the sake of argument, the newly discovered ore body is located towards the western edge of the Grants Mineral Belt. The host rock for uranium mineralization is the Westwater Member of the Morrison Formation. The Westwater Canyon sands are overlain by the Brushy Basin Member of the Morrison Formation and underlain by the Recapture Member, all of Jurassic Age. Westwater Canyon sandstone is a fine to very course grained subarkosic sand with interbedded green and red mudstone. The Brushy Basin Member consists predominantly of greenish-gray mudstones and contains thin lenses of sandstone and a few thin beds of limestone. The Recapture Member consists of alternating thin beds of reddish brown, grayish red, and light gray sandstone and siltstone. The Recapture interfingers with the Cowsprings Sandstone in the area of the mine. The mineralization is based on the groundwater flow within the Morrison Formation. Primary ore distribution is based on three basic parameters: ore migration in a geochemical cell, lenticular mudstone interbedding, and enrichment along fault zones. In areas where two fault systems intersect, ore thicknesses of up to 30 m (100 ft.) are encountered. In those areas where the ore is well defined and thicknesses facilitate full face mining, the mining methods are determined more by ground or operating conditions, equipment availability, and access to working areas than they are in the fringe areas of the ore body where grade control is more important and split-shooting and break-even grade determines the mining technique. If a modified room-and-pillar mining method using systematic development is selected, better control of the ventilation, equipment utilization, and mining plan can be obtained. Figure I shows a typical mining area where the ore is thick,

Jan 1, 1982

By P. C. Upadhyay, J. G. Singh

Reissner's thick plate bending theory has been recast for rocks which exhibit the property of double elasticity: different Young's modulus and Poisson's ratio in compression and tension. The governing differential equation and other relevent expressions have been presented in a form compatible to the applied mechanics results so that they can readily be used. Effect of the ratio of Young's modulii in compression and tension, (Ec/Et), on the maximum plate deflection and the maximum bending moments has been evaluated over a wide range. It has been found that the inclusion of bi-modulus property through a parameter (ß = Ec/Et), changes the sheer deformation of the plate to such an extent that the bi-modular effect of rock cannot be overlooked in the thick plate analysis, especially when ß is expected to be greater than 2.

Jan 1, 1982

By Rodolfo V. de la Cruz

The in situ deformability of rock masses is determined by relating the applied load to the radial displacements of points on the borehole wall that are outside of the loaded surfaces. The external displacement method includes the steps in which: a) radial displacement sensors are installed to measure the change in length of a diameter of a borehole; b) unidirectional self- equilibrating pair of forces perpendicular to the direction of radial displacement measurements are applied on opposite sectors of the borehole wall, and; c) using elastic theory, the in-situ deformability of the rock mass can be related with the applied loads and measured radial displacements. The displacements outside the loaded surfaces are comparatively smaller in magnitude than displacements inside the loaded surfaces. These displacements, however, are sufficiently large and can be measured precisely by commercially available linear displacement sensors. Loads are applied by a conventional borehole jack. Existing methods for measuring the in situ deformability of rock masses yields unreliable results due to complex boundary stresses, small and varying contact areas, and the existence of fractures. It was shown that in the external displacement method, the effect of boundary pressure distribution and contact area are negligible. Also, since the displacements measured in the external displacement method were due to materials that are deeper inside the rock mass, borehole fractures have less influence on the calculated deformation modulus.

Jan 1, 1982

"Projections of demand for Alberta coal indicate a quadrupling of current production rates to some 70 million tonnes/year by the end of the century. About half of this output-comprised of subbituminous coal-will be required within the province, primarily for generation of electric energy. The remainder-roughly 70 per cent high-volatile bituminous (hvb) steam coal and 30 per cent medium- or low-volatile bituminous (mvb/lvb) metallurgical coal-will be exported, principally to Pacific Rim and Western European countries. Direct employment in mining and coal processing is projected to increase from the present ca. 3000 to at least 12,000 persons.This paper presents separate forecasts for subbituminous, hvb and mvb/lvb coal production in the period 1982-2000; notes a number of possible developments that could substantially modify these forecasts; and briefly discusses attendant infrastructure requirements. Attention is drawn to potential shortages of qualified manpower and to threatening inadequacies of transportation facilities.IntroductionDespite the dislocations triggered by the 1973 'oil crisis', energy budgets of Western industrial countries are mostly still in the very early stages of the anticipated transition to greater reliance on coal. Shift s to coal are still more often only talked about than being implemented; and the public policies which are essential for timely development of facilities for producing, transporting and using coal are in many instances not yet even broadly formulated, let alone enunciated.In these circumstances, long-range projections of coal demand and supply-even if restricted to internal requirements- are subject to greater uncertainties than usually afflict such forecasts.On the demand side of the equation, these uncertainties arise ultimately from linkages between a need for coal and the availability and pricing of OPEC oil. The current surplus of oil on world markets, which has recently forced substantial reductions of posted prices, is undoubtedly a transient phenomenon that is unlikely to have any long-term impact."

Jan 1, 1982

By Frederik W. de Klerk

INTRODUCTION During the past 40 years, there has been in the United States of America and other industrialised Western countries a distinct displacement in the procurement of minerals from domestic sources towards an increased dependence on imported minerals. This was caused in part by one or each of the following: a lack of local supply of particular minerals, domestic source depletion or exhaustion and the relative ease and inexpensiveness of obtaining minerals from comparatively unexploited sources in underdeveloped and some developing countries, notably in the Middle East, South America, Southern Africa, and Australasia. Governments of the industrialised nations, concerned about the reliance of their economies on imported raw minerals examined both the degree of reliability and the extent of mineral resources in the countries and regions supplying the essential minerals. This brought a painful awareness of the vulnerability of industrialised countries as a result of the possible interruption of their mineral imports. In this regard, the United States of America may be quoted as a case in point: a report by a House of Representatives Subcommittee on Mines and Mining (Santini Subcommittee)1 revealed that the United States in 1980 was dependent on foreign sources for more than 50 per cent for 24 of the 32 minerals essential for national survival. The Subcommittee also acknowledged that although the United States may develop its own alternative energy sources, there are in many cases no substitutes for the strategic + minerals imported from foreign sources, from countries which are often unstable at best, hostile at worst. This resulted in various policy responses as well as contingency measures, amongst other, renewed emphasis on the utilisation of domestic mineral resources, an intensified search for substitutes of critical minerals and increased stockpiling programmes. Increased attention was devoted to analyses of the political and economic conditions prevailing in the regions from which strategic and other minerals are exported to the industrialised countries, and the formulation of policy measures vis-a-vis those regions. One region which attracted a considerable degree of attention has been Southern Africa, and in particular South Africa.2 The Santini Subcommittee affirmed that while the bulk of the minerals imported by the United States is supplied by a number of source countries, a host of critical[t] minerals vital to the well-being of that country (and this includes all the Western industrialised countries) originates from Southern Africa, a region, deservedly referred to as the "Persian Gulf of Minerals". Apart from the Republic of South Africa the mineral-rich countries concerned are Angola (diamonds, iron ore, oil), Botswana (diamonds, coal), South West Africa/Namibia (diamonds, uranium), Zambia (copper, cobalt), Zaire (industrial diamonds, copper, cobalt) and Zimbabwe (gold, nickel, chromium, asbestos). The Subcommittee however noted that, with the exception of cobalt, the greatest portion of the reserves of the critical minerals listed, lies within the borders of South Africa. SOUTH AFRICA A RELIABLE PURVEYOR OF MINERALS In view of the continual instability and political risk, along with the nationalisation of mineral industries in third world countries, importing industrialised nations have in recent years become more and more concerned about security of long-term supply, and have in consequence begun to diversify their mineral enquiries to areas where the following conditions prevail: • Long-standing record of consistency of supply; • An economic system of private enterprise; • Political stability; • A well integrated infrastructure, with a maintenance of transportation and development costs at realistic levels, and • Attractive investment opportunities, with security of the return of profits.

Jan 1, 1982

By Lynn C. Jacobsen

Among the unforeseen consequences of the 1973 Arab oil embargo has been a considerable array of new or increased taxes on the so-called energy minerals. These taxes will be the subject of this report. Both Federal and State taxes have been enacted, but I will be concerned mostly with state severance taxes and particularly those on uranium. Severance taxes are considered to include all taxes having the distinctive feature of being applied on a natural resource at the stage of extraction. The tax may be based on units of production or on value, and if on values it may be on gross value or on gross value less either arbitrary or cost-related deductions. The tax has a number of aliases - resource excise tax, conservation tax, privilege tax, mining excise tax, ad valorem production tax, and more - and this makes comparison of tax burdens among states difficult. The windfall profit tax on oil is an example of a severance tax at the Federal level. Severance taxes are an established feature of state tax systems, but they continue to be a controversial issue, and proposals to raise or modify existing severance taxes are regularly submitted to the legislatures of the Western energy producing states. No concensus exists as to what is a reason- able and proper level of severance taxation or to the form it should take. The taxes which have been adopted by the various states reflect the interaction of a variety of interests and the specific circum- stances in each state. What follows is a summary of theoretical, practical, and emotional viewpoints and arguments that surface in any statehouse in which a severance tax bill has been introduced. The New Mexico experience will be heavily relied upon. THE ECONOMISTS Marginal effects. A severance tax which is based on a gross percentage of revenue or on units of production is a constant addition to variable costs, and to the mine operator has the same effect as any other increase in operating costs. The direction of these effects is straightforward: the tax will cause the property to have a lowered present value, to be mined at a lower rate than without the tax, raise the minimum grade that will be mined, lead to lower total recovery, make marginal properties sub-marginal and discriminate in favor of richer, more profitable operations (Lockner, 1965; Steele, 1967). In the short run, production facilities are fixed and imposition of a severance tax will have little effect on production levels. In the longer term, capital is mobile and investment and exploration expenditures will shift from minerals and jurisdictions with high taxes to those with low taxes. Over a considerable range of taxation the effect will be to change the relative position of the taxing state, but an overly optimistic evaluation of the capacity of mineral producers to absorb a tax can bring an industry to a halt. It is generally acknowledged that imposition of high severance taxes on taconite in Minnesota stopped development completely, and that only the adoption of a constitutional amendment limiting the amount of taxes that could be imposed in the future brought the firms back and encouraged them to make the huge investments required (Weaton, 1969). A tax which is a percentage of the net operating income (gross revenue less cash operating costs) does not influence the cut-off grade for recovery nor change the time preference for extraction, and hence, is free of the negative features of the tax applied to gross revenues or units of production. In theory it is a more efficient tax but relative administrative complexity and inherent difficulty in predicting revenue have discouraged its use. The Wyoming severance tax on uranium, which uses grade of ore as well as price in establishing taxable value, is the most cost related, and hence, the most neutral and efficient of the various state severance taxes on uranium. Economic rent. Despite the discrimination and the anti-conservation aspect inherent in most severance taxes, economists generally endorse their use because they are seen as a vehicle to appropriate rents - that is, returns greater than the long-run competitive supply price. Conspicuous examples of supposed economic rents are the returns to oil producers because of the OPEC cartel, the returns of the uranium producers under AEC buying contracts in the 19501s, and the high prices obtained by the uranium producers for contracts entered into in the 1976-1979 period. Mining of coal in the Western states is believed by some to generate huge economic rents because of the OPEC caused increase in price of a competitive fuel (McLure, 1978, p. 261), and possibly because of clean air regulations favoring the burning of low-sulfur coal. In theory, such surplus returns could be taxed completely away without affecting supply. In practice, the situation is more complex (Steele, 1967, pp. 234-236); economic rent of mineral production is an elusive quantity involving as it does replacement costs, and technical and market risk, and it, like beauty or pornography, probably exists mostly in the eye of the beholder. Rent may also be perceived to be present in the upper portion of a cyclic market which also has a downside. Where rent exists, it is almost certain to be short-lived - cartels self- destruct, government subsidies end, competitive adjustments occur - but the taxes imposed to capture it tend to be immortal. There is little doubt that the perception of un- usual and undeserved (obscene) profits in the mid- and late 1970's was a major factor in the adoption of energy mineral taxes strikingly higher than had been previously considered. At the New Mexico legislature of 1977 supporters of a moderate tax were repeatedly confronted with some variant of the statement, "You can't expect me to believe that a

Jan 1, 1982

By R. D. H. Bedd

GEOLOGICAL NOTES The area under discussion is situated approximately 150 m north of Loraine No. 3 shaft at ± 1500 m below surface. The block being mined extends from about halfway between 50 and 52 levels to just below 48 level (see Fig. 1). The EB reefs form the lower portion of the EB zone of the Elsburg series and in the 81 line area the various conglomerate bands show the best development. Up to 18 separate reef bands are developed and the distance from the bottom conglomerate band to the top is ± 26 m. The thickness of the quartzite which forms the middling between the various reef bands varies from 0.1 to 2 m. The strike is roughly north-¬south. The reef bands are payable individually. However, owing to the steepness of the reefs and their close prox¬imity, conventional mining would prove very difficult. The nonpayable reef bands all carry varying amounts of gold and the whole area is a massive payable reef body approximately 26 m wide and 60 m high at 300 to 400 m on strike. The major structure of the area consists of a north¬-south trending syncline. The western flank of the syncline has a steep easterly dip, in places approaching the vertical. This flank cuts out against the overlying rocks of the EA zone. The latter forms a noncon¬formity with the underlying EB zone. The eastern flank of the syncline dips to the west at an average dip of 0.17 rad (10°). The 0.1 rad (6°) north-plunging syncline was sub¬jected to severe faulting. The most important are the Nos. 4 and 10 faults, both of which have a roughly north-south strike. The No. 4 fault dips to the west at an angle of 1.04 rad (60°) with a downthrow of approximately 150 m to the west. The dip of the No. 10 fault is 0.69 to 0.81 rad (40° to 50°) west, with the western block having moved 150 m updip relative to the eastern block. The EB reefs are being mined by the sublevel stoping method down from the sub-outcrop position to the cutoff against the No. 4 fault. On the downthrow side of the No. 10 fault, that is just above the 54 level, two reef bands are payable and will be mined conven¬tionally. ROCK MECHANICS From the section in Fig. 1, it can be seen that the area under consideration is surrounded by stoped-out areas. This will naturally change the stress distribution extensively. The only way to calculate the stress field for such a geometry is to use the finite element method. It was established that this method worked for the present geometry and so the method was applied to predict the stress behavior of the final geometry. From the results, it appeared that the effect of the old stopes was to destress the area. There are, however, some areas-such as the 50 and 48 north footwall haulages-which will require continuous attention. In these two footwall haulages, deterioration can take place due to tensile stress which

Jan 1, 1982

By W. T. Walter

High-G centrifuges from five preparation plants were sampled to determine and quantify the various operating factors affecting performance. The operating factors that were considered include feed rate and percent solids, size of feed material, screen-basket type, hardness of coal and age of the flights. The performance parameters that were measured include product surface moisture, recovery and degradation of the coal. Regression equations with good significance levels were developed.

Jan 1, 1982

By Richmond AJ, Allan J

The use of long-hole in-seam drilling techniques for seam gas drainage ahead of mining was introduced to the Australian coal industry by ACIRL in mid-1981. ACIRL's research program has involved the development and demonstration of drilling and borehole survey technology in addition to evaluating the gas drainage potential of long-hole in- seam boreholes. This paper presents the results of the long-hole drilling carried out to date in the Illawarra District of the New South Wales coal fields. Drilling experience in relation to both vertical and horizontal directional control of the drill string, drill performance and borehole survey techniques are discussed. In addition, results of gas drainage effected by the long boreholes are presented. Future potential and requirements for further development of this technology are Reviewed.

Jan 1, 1982

By John R. Duble

Through 1980, demand for cement in the Pacific Basin countries still seemed to exceed output. Availability of cement in the industrialized and developing countries of East Asia, Southeast Asia, and Australasia for the 1975 - 1980 period are discussed in this report. Quantitative data includes production, imports, exports, and apparent consumption. An account of new cement plants and plant extensions is provided. Countries and areas covered include: East Asia---Japan, South Korea, North Korea, Taiwan, China, Hong Kong, Philippines; South east Asia---Thailand, Vietnam, Singapore, Malaysia, Indonesia; Oceania (Australasia)---Australia, New Zealand, New Caledonia, Fiji.

Jan 1, 1982

By A. A. Ruitenberg, L. R. Fyffe

"This paper compares several distinct types of mineral deposits associated with different families of granitoid rocks in the New Brunswick Appalachians. Porphyry copper deposit s are associated with late-stage differentiates of Lower to Middle Devonian I-type igneous complexes. Contact metasomatic deposits were formed where these plutons intrude carbonate rocks and they gave rise to vein deposits in fracture zones near wrench faults. The I-type granitoids were emplaced mainly in areas of thin continental crust and locally along prominent faults in areas of thick continental crust.In contrast, tin-tungsten-molybdenum-bearing greisen deposits and skarns, and antimony-bearing quartz veins are associated with predominantly S-stype granitoid complexes ranging in age from Middle Devonian to early Carboniferous. The mineral deposits occur within or along the contacts of very fractionated (specialized) late phases of these intrusive complexes, which are characterized by high K2O/Na2O, Rb/Sr and Rb/Ba, and low Fe, Mg, Zr and Ti contents. These specialized granitoids are in a large wrench fault zone that cuts across thick continental crust in southwestern and central New Brunswick.IntroductionA great variety of igneous intrusions and subvolcanic stocks were emplaced in the New Brunswick Appalachians during the latter stages of and immediately after the Acadian Orogeny (late Lower to Middle Devonian) and during the subsequent Hercynian Orogeny (Carboniferous). The presence or absence and characteristics of mineral deposits associated with these intrusions reflect the level of intrusion, the composition of the associated igneous rocks and the composition of the invaded sequences.Nickel-copper sulphide deposits occur in mafic intrusions in the St. Stephen area of the southwestern Magaguadavic - St. Croix Zone and in the Goodwin Lake area of the northeastern Mirarnichi Zone. Contact metasomatic and vein-type copper-rich base metal sulphide deposits and porphyry copper deposits with or without molybdenum are related mainly to high-level granitoid stocks of intermediate composition in the Matapedia-Tobique and northwest Miramichi zones. Tintungsten - molybdenum deposits with or without base metal sulphide minerals and antimony-uranium deposits are mainly associated with Upper Devonian and Lower Carboniferous biotite-muscovite granites and related 'subvolcanic intrusions that occur in an arc-shaped belt extending from the southwestern Magagaudavic - St. Croix Zone into the central Mirarnichi Zone."

Jan 1, 1982

By E. W. Cokayne

GENERAL DESCRIPTION OF THE METHOD The original application of sublevel caving was in ground so weak that it would collapse even in small headings when the support was removed. Heavily tim¬bered drifts were driven across the ore body; the timber was removed at the end of the drift, and the ore caved and slushed out. When dilution became excessive the next set was removed and so on. This method gave high dilution and poor recovery and was slow, but it was the only way to mine this type of ore body at that time. In more recent times the method has been adapted to stronger ground which needs to be drilled and blasted, so it is not a caving method as far as the ore is con¬cerned. However, the method does rely on the walls to cave and so the name sublevel caving has been retained. The method as presently generally applied is shown in Figs. 1, 2, and 3. Sublevels are established at approximately 7.6 to 12.2-m (25 to 40-ft) vertical intervals. They are usually accessed from a ramp system. A haulage drift is driven down the strike of the ore body, but in the waste. Production drifts are turned off the haulage drift and driven across the ore body on about 10.7-m (35-ft) horizontal centers. This divides the ore body into a geometrical pattern. Slot raises are driven at the end of the drifts near the ore-waste contact and the slot is expanded to the shape of the fan drilling. Up holes are drilled to break towards the slot at burdens of 1.2 to 1.8 m (4 to 6 ft). They are drilled past the next sublevel to the production drift im¬mediately above. When a sufficient number of fans has been drilled, production can start by blasting one or two fans at a time towards the slot. Load-haul-dump (LHD) units are used to muck the ore, which rills out into the drift. At first, when only a small area is mined, the walls may not cave, and the operation will be similar to open stoping. Later, sloughing from the walls will fill any voids created, and the ore after blasting will be con¬tained by the caved waste and gravitate downwards as mucking proceeds. This process is repeated in each of the production drifts as the face is retreated towards the haulage drift. When the top level has been retreated back a safe dis

Jan 1, 1982