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The New Zealand microcontinent is relatively well endowed with gold deposits; its past gold production per unit area of 3.2 kg/km2 ranks high on a world scale. Total recorded production (1857 - 1986) is about 854 000 kg and most of this gold was mined between 1861 and 1920. There has been a strong revival in gold exploration and mining since 1979, with exploration expenditure of around $15 million per annum and a declared gold production in 1986 of 1265 kg (886 kg in 1985). In addition to numerous alluvial gold recovery plants working small to medium sized deposits (mainly in Westland and Otago), there are five medium to large projects that have started production (Martha Hill), or have reached advanced stages of construction (Grey River dredge), permitting (Golden Cross and Macraes) or exploration (Globe-Progress). This summary paper is taken from reviews by Brathwaite et al (1986) and Brathwaite (1988).

Jan 1, 1988

In understanding the consequence of existing law, and the likely implications of its reform, it is necessary to comprehend the logic of the situation that the law provides individual decision makers and how that situation would be adjusted by reform. In particular, the way in which natural resources, including minerals, are used and managed is influenced by the definition and structure of property rights that the law provides. Property rights are enforceable claims to use or to benefit from resources. An example is a mining licence that allows its holder to extract minerals in a specified area. Property rights establish the structure of incentives, opportunities and constraints within which resource use decisions are made, ie the logic of the situation, and hence influence the use and management of resources. The extent and type of mining in New Zealand, for example, reflects the rights that miners have to extract minerals, and their rights to benefit from mining as against their duties to compensate landowners and pay royalties. This paper describes the characteristics of minerals that are relevant to the definition of property rights, analyses the implications of alternative property right arrangements and describes the existing situation.

Jan 1, 1988

By P. T. Slatter

The role of viscometers for rheological characterization in the hydraulic transport of solids is discussed, and rheological models and phenomena pertinent to the hydraulic transport of backfill material are reviewed. The two main branches of viscometry (rotational and tube) for the measurement of mining slimes rheology are compared. The effects of solids concentration, particle size and chemical additives and the practical application of rheology in backfill system design are presented.

Jan 1, 1988

By Munro P. D

Eh-pH measurements were taken on an industrial zinc reverse flotation process at Brunswick Mining and Smelting Corporation Limited. Laboratory zinc reverse flotation testwork on samples of the feed to the industrial process produced Eh-pH data which were similar to the data from the industrial process.Later, the Eh-pH data from the industrial process were compared with data from a pilot plant scale zinc reverse flotation process at Mount Isa Mines Limited. After comparison with the data from Brunswick Mining and Smelting Corporation, deficiencies in the pilot plant Eh-pH data could be recognised and corrective actions were taken for the pilot plant. A robust pilot plant zinc reverse flotation process was obtained with consistent performance at the expected level.The implications of these findings for a range of processes are also discussed.

Jan 1, 1988

By Kevin Connor

During 1986, the Government continued with efforts to ease the country's almost total reliance on coffee exports for trade revenues by allocating 45% of the Government's budget to commerce and industrial projects. The collapse in coffee prices in 1985 continued to exacerbate the country's growing trade deficit, weakened currency, and dwindling reserves of foreign exchange in 1986. Amoco Burundi Petroleum Corp., a subsidiary of Amoco International Oil Co., continued with plans to drill at least two exploration wells in Lake Tanganyika in 1987. Both offshore and onshore drilling exploration was planned by Amoco Burundi. Any oil or gas finds were expected to have substantial impact on the Burundian economy, as a major portion of the country's trade deficit was directly attributable to petroleum and gas imports.

Jan 1, 1988

By C. Bazin, D. Hodouin

"A flexible model involving perfect mixers, stagnant zones, plug flow, material bypassing and recycling zones has been developed for interpreting mixing phenomena in mineral processes. The mixing properties are described by the residence time distributions which can be subsequently interpreted by the flexible model. User-friendly computer programs (for 1MB-PC or compatible) have been developed for simulation and modelling of RTDs using the proposed model. Seven mineral processing case studies are discussed in terms of experimental procedure, model calibration results and application of the estimated mixing model to process modelling, diagnosis, and performance evaluation. IntroductionIn any mineral processing plant there are continuous-flow machines that transform or separate the ore components. Grinding mills, flotation cells, conditioning and leaching tanks are examples of such machines. The performances of these vessels or reactors are controlled by the rate at which the reaction proceeds and the time spent in the environment where the reaction occurs. This paper deals with the latter aspect of mineral processes operation.Since most of the reactions occurring in mineral processing units are time dependent, knowledge of the residence time of the material in process vessels is important for modelling and diagnosis purposes. Due to the random mixing phenomena involved in the process equipment, there is a distribution of the residence time of the ore particles and the fluid in the vessel. The probability density function E(t) that a micro-element of the material flowing through a processing unit stays a time t in the vessel, is the residence time distribution (RTD) of the corresponding component."

Jan 1, 1988

As part of the Bureau of Mines program to reduce U.S. reliance on foreign suppliers of strategic and critical metals, research was conducted to improve technology for the recovery of critical metals from hardface alloy grinding waste, a form of superalloy scrap. This report describes a hydrometallurgical process that demonstrated on a laboratory scale that 79 pct of the chromium, 97 pct of the cobalt, 99 pct of the manganese, 99 pct of the nickel, and 90 pct of the tungsten could be recovered in chemical form from hardface alloy grinding waste. The process involved deoiling the grinding waste, followed by chloride-based dissolution of the deoiled material. A high-grade calcium tungstate (CaW04) product was recovered from the resultant leach residue by caustic leaching and precipitation. Iron, cobalt, man-ganese, and nickel chlorides were sequentially recovered from the leach liquor by solvent extraction. Amine extractants were used to extract the iron, cobalt, and manganese; decanal oxime was used to extract the nickel. Market-grade cobalt chloride (CoCI2), manganese chloride (MnC12), and nickel chloride (NiCl2) products could be produced directly from the resultant strip liquors. The final raffrnate was a relatively pure chromic chloride (CrCI3) solution that compared favorably with commercial solutions.

Jan 1, 1988

By Patricia R. Devine

This appendix documents the mathematical approach to deriving the components of change presented in this report. The formulation closely follows that contained in Chapter IV of the documentation for the BEA 1977 Input-Output Tables.' The basic elements for the calculations include the "use" matrix (U), the "make" matrix (M), and any of the ten columns of final demand (generically represented by the symbol y). The use matrix contains information about changes in the technological processes of production, while the make matrix describes the nature of secondary product production in each industry. We adhere to BEA conventions in maintaining careful distinctions between commodity output (c) and industry output (x). The industry-by-industry 1-0 tables supplied by NYU for use in this analysis are square matrices, with the number of commodities and the number of industries both equal to 85. The BLS table for 1982 (commodity by industry) was aggregated and adjusted to be consistent with the earlier tables. The three basic steps for estimating components of change proceed as follows for each column of final demand. 1) Calculate the actual change in output of each commodity for each of the four time periods: 1963-72, 1972-77, 1977-82, and 1963-82.

Jan 1, 1988

By G. G. Goble

Significant progress has been made in the past decade in determining the load bearing capacity of pile foundations. Developments in the means of prediction of pile capacity as limited by soil strength have been substantial, particularly in the use of dynamic methods. The use of currently available equipment, analytical procedures, and practices in the field, will often produce material economies on a job by allowing increased loads with proven factors of safety. This approach justifies the minimum number of piles required for a safe foundation in a wide range of job sizes and soil conditions. To avoid exposing the reader to excessive detail in the body of this paper, technical topics have been covered more thoroughly in several appendices. I. Wave Equation Analysis of Piles Appendix A II. Dynamic Monitoring and the Pile Driving Analyzer Appendix B III. Case Method Capacity Calculation Appendix C IV. Case Pile Wave Analysis Program Appendix D 1 Preliminary Analysis In designing driven pile foundations, there must be a close relationship between design, construction control procedures, driving practices, and the size of the job. Small commercial buildings or residences involving loads that are only a fraction of the pile capacities do not justify the expense of detailed design processes or elaborate construction controls. Nevertheless, some preliminary analysis of the job requirements and a limited subsurface investigation must be made to understand existing conditions and the possible foundation solutions. In other words, it is necessary to determine that driven piling is the best overall choice of foundation.

Jan 1, 1988

By Gennaro G. Marino

Documented case histories of surface ground movements from mine subsidence were utilized to help determine when the initial collapse of the overburden occurred above longwall panels. By studying this relationship between initial movement at the surface and the amount of face advance, the least-complex conditions exist for empirically assessing the span capacity of the overburden. The objective of this work was to obtain a better understanding of the overburden response to longwall mining. This knowledge will give a better insight on the long-term effects that different overburden types have on the stability and the subsidence potential of room and pillar mines, as well as, the influence of the overburden on subsidence over longwall panels. Theory on the overburden span capacity was developed and correlated to field observations. Data were used on the overburden lithology, depth, width, and face advance of the panel, and the subsidence conditions that were noted on the surface. The subsidence measured on the surface was used to determine when complete failure in the overburden rock had occurred. According to spans predicted by theory and the subsidence measured in the field, the competent lower units failed at a face advance less than when significant subsidence was observed on the surface. In each case studied, there were competent lower beds; however, the full overburden weight was not sustained to the point of subsidence. The best correlation with the surface movement was found with the most shallow, competent bed. Elastic plate solutions with various support conditions were found to best monitor the surface subsidence of these upper roof units.

Jan 1, 1988

By William H. Schiffbauer

The Bureau of Mines is conducting research that is aimed at making the mining industry more efficient in term of both productivity and the health and safety of the worker. As part of this research the Bureau of Mines has integrated a testbed composed of computer and related peripheral hardware to form an intelligent base for performing autonomous mining machine experiments. Although this particular application was con- figured for use on a Joy 16 CM mining machine, its generic structure facilitates its attachment to a variety of mining machine types. The multitasking multiuser computer can be set up for other applications by changing a bubble memory cartridge. The Joy 16 CM implementation includes 96 digital input-output (1-0) ports, 32 analog inputs, 8 analog outputs, 2 serial data channels, and 1 printer port. Operation of the machine can be performed either through a local terminal or remotely through a modem hookup. This report describes a testbed for autonomous mining machine experiments (TAMME)--its hardware, software, and complete system integration--so that it can be used as a foundation for other applications.

Jan 1, 1988

By Shail J. Butani

In 1986 the Bureau of Mines conducted a probability sample survey, Mining Industry Population Survey, to measure such employee characteristics as occupation; principal equipment operated; work location at the mine; present job, present company, and total mining experience; job-related training during the last 2 years; age; sex; race; and education. The population estimates are necessary to properly analyze the Mine Safety and Health Administration (MSHA) injury (includes illness and fatality data) statistics; that is, to compare and contrast injury rates for various subpopulations in order to identify those groups that are exhibiting higher than average injury rates. This report uses the survey's results to characterize the U.S. nonmetallic mining workforce from March through September 1986. Similar reports have been prepared for the metallic, stone, and sand and gravel mining industries, as well as for the entire metal and nonmetal mining (includes metallic, stone, sand and gravel, and nonmetallic industries) sector and the cool mining sector.

Jan 1, 1988

This chapter summarizes data on crude nonfuel mineral production for the United States, its island possessions, and the Commonwealth of Puerto Rico. Also included are tables that show the principal nonfuel mineral commodities exported from and imported into the United States and that compare world and U.S. mineral production. The detailed data from which these tables were derived are contained in the individual commodity chapters of Volume I and in the State chapters of Volume II of this edition of the Minerals Yearbook. Although crude mineral production may be measured at any of several stages of extraction and processing, the stage of measurement used in this chapter is what is normally termed "mine output." It usually refers to minerals or ores in the form in which they are first extracted from the ground, but customarily includes the output from auxiliary processing at or near the mines.

Jan 1, 1988

The Government signalled its intention in the Economic Statement on 17 December 1987 to improve the fairness of the taxation system and to facilitate the process of economic adjustment by: removing tax concessions that benefit some taxpayers at the expense of other taxpayers,ensuring that those who can afford it shoulder their fair share of the tax burden,securing a revenue base which will provide sufficient resources to maintain effective social services,reducing artificial protection and concessions that discriminate against some sectors, and encouraging confidence through an economic environment with a medium-term orientation. The Government has clearly stated to all sectors that tax preferences will be phased out and businesses need to look inwardly to their investment policies if they are to survive in an open economy. This paper will address the effect of these Government objectives on the taxation structure for all forms of mineral exploration in New Zealand. The present tax structure will firstly be analysed, in particular setting out the tax advantages available to the industry. The effect of changes to the tax system within the recent past which relate to mineral exploration will then be examined. Finally the paper will address the question of possible future changes, particularly in the light of Government's intention to move towards a tax system which does not provide an advantage for any one sector of the economy.

Jan 1, 1988

By Julius G. Chang

Against the receding background of the October stock market crash and the December overhang of inventories, the economy began with a shaky start in 1988. As 1988 began, the Administration's estimate of real growth for 1988 had just been reduced from 3.5% to 2.4% and economists and other ob-servers were concerned that the expansion that was 5 years old might be near the end and that a recession might be around the corner. The ensuing moderately strong economic activity, however, belied all the negative signals that were evident earlier, and the real GNP continued to grow at an estimated 2.3% annual rate during the first quarter of 1988, extending the ongoing recovery into the sixth year (table 1.). The relatively accommodative policy of the Federal Reserve Board (the discount rate was cut by 0.25% in January), a strong performance by the export sector, and the revival of consumer spending were major forces underlying the economic strength. But as the quarter drew to a close, signs of tight capacity utilizations were apparent in many of the export and capital goods sectors, including textile, chemical, plastic, metal, and machinery. Employment was at a record high level while the unemployment rate was close to a historical low. Prices were rising at a faster pace than those of 1987, and the dollar resumed its slide after a brief recovery in January and February. These factors gave rise to the fears of higher inflation. Long-term interest rates increased, casting a pall over the prospect of a robust growth for the rest of the year.

Jan 1, 1988

By K. Duckworth

"Comparative tests of the conventional Turam survey configuration and an alternative configuration called the Tx-parallel configuration were conducted at the McClean uranium deposit in northern Saskatchewan. Both configurations detected the known conductors at the site but the alternative configuration demonstrated its particular effectiveness in the reconnaissance role. This effectiveness results from the fact that the length of Tx-parallel traversesis controlled only by the length ofthe transmitter and not by its power. In addition, the field strength along a Tx-parallel traverse is uniform unless the traverse approaches the end of the transmitter. This freedom from a strong gradient of the primary field along a Tx-parallel traverse eliminates the gradient-induced anomaly shifts which are common in conventional Turam operations. The locations of each of the McClean conductors, that were obtained from the Tx-parallel profiles, werein better agreement with the locations known from drilling than were the locations obtained from the conventional profiles. However, the conventional profiles gave better estimates of the conductance of the targets.The results obtained over the McClean conductors indicate that current gathering has a strong influence on Tx-parallel results with consequent unpredictable influence on depth and conductance estimates. However, the depth estimates obtained from the Tx-parallel data appear to be in good agreement with the known depth of the McClean south conductor. The Txparallel results provide shallow estimates of the depth of the McClean north conductor which suggest that the fracture zone above the graphitic conductor is a significant conductor as was also suggested by earlier VLF surveys.Comparison with the wide range of published geophysical test surveys for the McClean site showed that apart from the work required to lay the transmitter, the Tx-parallel mode of operation of a Turam exploration system is operationally very similar to a moving source Slingram type of survey. At the McClean test site, it provided the same depth of exploration as a conventionally deployed fixed loop transmitter."

Jan 1, 1988

By P. Choquet, F. Miller

"The development and testing of a simple low-cost gauge for measurement of tension in a cable bolt grouted in a borehole are presented. Its principle is based on a resistance wire which is wound on a 70 cm length into the spiral grooves of the wire strand cable bolt. Readings are then taken by a robust automatic data logger with a several day autonomy or by a portable readout. In order to have a complete profile of tension along the cable bolt, a number of tension gauges can be installed along its length.This paper provides a description of the development and laboratory calibration of the tension gauge and addresses the two modes of loading for a cable bolt in a rock mass, namely pure tension and shearing at a joint location.In the second part of the paper, four field tests in underground and open pit mines are reported. The first test was used to substantially modify both the gauge and the readout unit principles while the other tests which are still on-going show a very satisfactory behaviour of the modified version of the tension gauge. IntroductionCable-bolting is often used as ground support in Canadian mines for a variety of applications. In underground mines, cable bolts can be installed vertically at the back of cut and fill stopes or in an inclined fashion in the walls of large open stopes. Alternatively, cable bolts at Mines Gaspe (Noranda Inc.) are used in a fan-shaped pattern from a drill drift to stabilize the inclined roof in 25 m wide open stapes. This new application oriented our research efforts toward the design of a novel instrumentation to monitor the efficiency of most commonly used 5/8-inch cable bolts."

Jan 1, 1988

To provide a flexible, low-maintenance, low-cost continuous mine air monitoring system as an alternative to conventional fixed-point, electronic monitoring systems. Background Continuous monitoring of mine air is highly desirable (and often required) not only to improve miner safety, but also to increase mine productivity. Continuous air monitoring systems can provide earl" warning of developing fires, excessive methane accumulation, reduced oxygen levels, and other developing problems in remote, inaccessible or sealed areas, and in active workings. Fixed-point, electronic systems require one Sensor for every gas to be measured at every defined monitoring location. As the number of monitoring locations increases, so does the cost, along with increases in the time required for routine maintenance and calibration of the sensor System cost also increases when monitoring locations are identified for mine areas requiring permissible electrical equipment.

Jan 1, 1988

By J. -P. Saindon, L. D. Nel, A. E. Hall, S. G. Hardcastle

"This paper reports on an investigation into gas and dust concentrations in Ruttan Mine's exhaust air. The values obtained indicate that there is excellent potential to recirculate approximately 25% of the hot exhaust air into the intake air to reduce winter heating costs. Contaminant concentrations vary significantly during the course of the working shift and decrease in the mine exhaust system as the air returns to surface. A proposed on-line control system is outlined which would permit recirculation to be implemented with a pay-back period of less than two years. IntroductionIncreased energy costs and depressed mineral prices have resulted in mines, which use winter ventilation air heating, reviewing their systems to try to reduce costs. Heating costs can be significant, for example, Potash Corporation of Saskatchewan spends an average of $580,000 per mine per year and Ruttan mine spends approximately $IM per year on propane for its direct-fired heating system.Several method s of reducing heating costs have been considered and the following have potential application.Heat Exchange Between Exhaust andIntakeThis is usually accomplished by run-round glycol systems. The system is limited by ice formation on the coils in wet exhaust air and by the low exhaust air temperature, usually l0ºC. It also requires close proximity of the intake and exhaust airways to ma~e the cost of the connecting pipeline and pump systems economic . A feasibility study by Inco's Thompson operation reported that a proposed system of this type had a 19-year payback period and was, therefore, uneconomic. Potash Corporation of Saskatchewan is currently investigating plastic heat exchangers for a trial system because of corrosion on metal exchangers. It has the advantage of a 17°C exhaust temperature and relatively dry exhaust air.Waste Heat ReclamationThe waste heat from compressors and hoists can be used for heating in some mines. The feasibility of such a system depends on the individual layout and the proximity of the heat source to the inlet airway. Other mines have considered using the exhaust air in greenhouses to provide a cash crop."

Jan 1, 1988

Jan 1, 1988