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By Snowden C. T

B Lens Main is a scheelite orebody with an average dip of approximately 15¦ and thickness ranging from 1.5 to 6.0 m. The orebody is overlain by a banded section of ore and waste which tends to slab off if left unsupported. It was originally planned to mine a large portion of this orebody by room and pillar methods, with existing diesel trackless equipment. This, however, proved unsuitable for a number of reasons and the smaller scale method of slot stoping with hand machines and scrapers was employed. The following major problems were encountered. 1. The method was new to the mine and the work force, and had to be commenced quickly using existing or easily obtainable equipment. This is gradually being overcome by training, modification of procedures and introduction of more suitable equipment. 2. The slabbing from the hanging wall had to be controlled, either by support or by mining this low grade section and accepting the resultant dilution. This has been approached in a number of ways, depending on conditions and the method will have to be further modified as different conditions are encountered in new areas.

Jan 1, 1977

By J. A. Herbst, J. L. Sepulveda, J. D. Miller

Effective bismuth removal from flue dust residues has been accomplished for flue dusts from both zinc and copper smelters. Selective dissolution of bismuth, with respect to silver and lead, can be achieved by the proper manipulation of temperature, sulfuric acid addition and sodium chloride addition. Optimum levels of these variables were determined using a response surface technique to maximize the objective function: Y = %Bi/(1 + %Ag). In the case of the flue dust residue from a zinc smelter, which contains bismuth as an impurity (0.05%), 86% bismuth removal can be realized with less than 1% combined silver and lead dissolution. Similarly, in the case of flue dust from a copper smelter, which contains bismuth as a primary constituent (3.3%), 93% bismuth removal was obtained with little dissolution of silver and lead values.

Jan 1, 1977

By Dagbert M, Belisle J. M

Several packages for the estimation of porphyry type deposits exist and produce acceptable results. Recently, however, the need for really trying to obtain maximum information from drill holes has prompted the generation of geostatistical solutions to the problem of reserve calculation. It will be shown that an understanding of a few key points is necessary in order for these solutions (variogram analysis and kriging) to he really ptimal. The most important new fact to be ecognized in open pit ore reserve estimation is that block models do not give an accurate rediction of ore tonnage when a cut-off is pplied but often yield an overestimation of p to 25%. When checked against extensive roduction records, geostatistical methods provide a practical solution to this problem. t now seems that the model used here gives he best possible results. Inasmuch as all arge deposits present very similar geostatis- ical characteristics only a few days of work re necessary to produce a complete inventory f these. The techniques used will be demon- trated using examples from five deposits and pecial emphasis will be given to the accurate rediction of tonnages of ore and waste using he new "transfer function" technique of G.

Jan 1, 1977

By Kennedy B. J

The 1100 Orebody is the main copper production area of Isa Mine with an output of 390 000 tonnes per four week period and a work force of approximately 260 men per shift. Currently a total of 56 nippers work a three shift, five day week roster to-service crews spread over a strike length of 1000 m and a vertical height of 220 in. A variety of rail and diesel equipment provides shaftto cribroom and cribroomto sublevel work place transport of men and materials. Overall eficiency and safety has been improved with a selected group performing supply, storage, clean-up and "bus runs" throughout the orebody - activities which are further co-ordinated by an FM radio system linking units with a control clerk.

Jan 1, 1977

By M. F. Werneke

Flotation of the carbonate, oxide and silicate minerals of copper (malachite, azurite, chrysocolla) has been the subject of much research in recent years, but few effective solutions to this problem have been found. With decreasing reserves of sulfide minerals, the economic recovery of these "oxides" appears to be an important source of copper for the future. Xanthates have been known for many years to be malachite collectors (1), but only at very high dosages, or at lower dosages following activation of the mineral by sulfide ion. Dewitt and Batchelder (2, 3) found that chelating agents such as certain oximes were collectors for malachite and azurite, but also required high reagent dosages. Fuerstenau (4) has suggested, for example, that potassium octylhydroxamate may be an effective collector for malachite, On the other hand, Balberyszski (5) has found that oxide minerals may be completely sulfidized at high temperatures with gaseous sulfur or H2S, and then floated with conventional collectors. None of the above approaches appear to offer an economically effective method for the direct flotation of these oxide minerals.

Jan 1, 1977

Types of structure found in 'Jest Australian beach sands are described. Their recognition by geostatistical methods follows nth a discussion of the effectiveness of sampling patterns. Examples of structures are given, and an account of their effect on valuation procedures.

Jan 1, 1977

By Charles J. Haas

The effectiveness of rock bolts in resisting shear displacement along preexisting fracture surfaces or slip planes was determined in the laboratory with full-scale bolts and large-scale shear test equipment. The system variables were the type of bolt, orientation of bolt relative to shear surface, and normal pressure on the interface. Results showed that, in general, both conventional bolts and resin- grouted reinforcing bars significantly increase the shear resistance along a fracture or bedding plane when the average normal compressive stress on the plane is in the order of 25 psi and when the bolt is oriented such that it tends to lengthen as the shear progresses. An increase in shear resistance is also noted at the higher normal pressure of 250 psi; however, the increase is small compared to the corresponding shear resistance without a bolt. Conventional bolts oriented such that they lose tension as shear displacement occurs added no shear resistance since the tension drops to zero at very small shear displacements.

Jan 1, 1977

Provide means for rapidly re-establishing ventilation control in metal mines after blasting, for emergency applications, and for routine temporary use. Approach Two quickly-installed, parachute-like stoppings have been developed and tested by the Bureau's Pittsburgh Mining and Safety Research Center. How the Parachute Stopping Works The parachute stopping can be fastened to an existing anchor point, opened, and effectively block the air flow, in less than two minutes. Because the parachute stopping tends to be self-scaling, its performance is generally better than that of conventional fabric stopping. However, the periphery of the parachute stopping must be longer than the periphery of the mine opening, Figure 1 shows the parachute stopping deployed in a mine entry. To reduce leakage during routine use, the cloth at the periphery of the parachute stopping can be adjusted and then anchored at several points as necessary. This extra adjustment can also be done after the initial installation during mine rescue or mine recovery.

Jan 1, 1977

By Zoltan F. Oszter

The frictional resistance to motion of a belt conveyor has always been a subject of intensive studies and research by engineers throughout the years. Numerous informations have been developed by analysing series of field tests on belt conveyors of different characteristics and carrying different materials at various capacities. Within certain limits of weight per unit length and tension, the theoretical considerations and the analysis of the field tests, both in the US and abroad, resulted in the development of similar formulas. In general these formulas are safe to use up to the following limits:

Jan 1, 1977

By P. J. Bourassa

Incorporated in 1957 under the laws of the Province of Quebec, Quebec Cartier Mining Co. undertook the development of its low-grade iron ore reserves located at Lac Jeannine in the southwest extremity of the Quebec-Labrador trough. This challenge comprised the construction of a 200-mile access road, two towns, a 191-mile-long railroad from Port Cartier to Lac Jeannine, a hydro-electric generating plant on the Hart Jaune River, and mining, crushing, concentrating and ancillary facilities to support a yearly production of 8.0 million tons of iron ore concentrates at 66% Fe. In order to meet increasing market demands for iron ore concentrates concurrently with the depletion of its Lac Jeannine reserves , Quebec Cartier announced, late in 1969, the first step toward bringing into production a new iron ore deposit, known as Mount Wright, located 70 air miles northeast of Lac Jeannine and 25 miles southwest of Labrador City, Newfoundland. In September 1970, the company announced its decision to develop and bring into production its Mount Wright reserves at an annual rate of 1 8.4 million dry long tons. The scope of this project included the construction of an access road linking the mine, the new town and Labrador City, Newfoundland, the extension of the railroad by some 86 miles, the construction of an ore concentrating plant with all the ancillary facilities, the development: of the mine, the construction of a pourer transmission line and a new town adjacent to Lake Daviault. The Mount Wright story is divided into five individual papers covering: (a) the history and development of the project; (b) the mine; (c) plant control by a process computer; (d) crushing, grinding and concentrating; and (e) the townsite of Fermont.

Jan 1, 1977

By V. E. Dawson

Brake testing of large mining trucks was initiated in British. Columbia in 1969 following an accident involving the failure of the service brakes of a l00-ton electric-drive truck. Some selected results of the 1976 brake test program are presented and discussed ?in this paper . The tests were conducted on end- dump trucks having load capacities ranging from 85 to 235 tons. All tests were made with the vehicles fully loaded operating on downhill grades varying from 8 to 10 %. Stopping distances were measured from initial speeds varying between 10 and 39 mph. The results are adequate, in most cases, to determine the "ultimate" capabilities of the service brakes of varying models and sizes of haulage trucks operating in British Columbia mines.

Jan 1, 1977

The paper outlines the development and objectives of the slim core (50 mm dia.) testing procedures employed at the Company's Central Research Laboratories with particular reference to washability studies required for coalfield evaluation. It shows that when the routine test procedures, that have been developed for cores recovered form the Sydney Coal Basin, were applied to Bowen Basin Coals some of the washing data obtained appeared to be suspect. Though yield indications appeared to be of the right order, product ash, required separating gravity and percentage of near gravity material were found to be at variance with bulk washability data. The results of a correlation study made on an underground seam from the Bowen Basin comparing slim core, hulk sample, and pilot plant washing data are given. The results of a series of studies including washability studies made on slim cores, strip samples, large diameter cores and bulk samples, pilot washing trials and computer simulations of washery circuits treating Lilyvale seam coal from the Bowen Basin are shown.

Jan 1, 1977

By Harold J. Bennett

A comprehensive knowledge of the availability of mineral resources to evaluate and assure a dependable supply is a prerequisite in establishing and maintaining a viable national economy. Since no nation is self-sufficient in all its mineral needs, its prosperity depends to a great degree upon its developing and maintaining an effective national minerals policy. This must be preceded by a systematic inventory of mineral resources that may be available to that nation. The U.S. Bureau of Mines is implementing a mineral deposit inventory program of domestic and foreign mineral occurrences, with initial emphasis on the domestic. In order to provide an in-depth appraisal of minerals availability, the approach includes not only realistic estimates of quantity and quality, but other essential factors such as costs, technology, environmental constraints, and development-time requirements. Analysis of this information provides usable relationships of quantity, price, time, and associated degrees of confidence of the occurrence of identifiable mineral resources. Keeping pace with a changing minerals industry and handling the large volume of information required in this undertaking demands that computer methods be employed.

Jan 1, 1977

By Charles J. Lipton

Third World countries have lately taken a variety of actions to improve their revenues from the development of their mineral resources. Increasingly, their governments seek to negotiate production agreements on the basis of feasibility studies and discounted cash flow projections. Developing countries are now more selective in giving incentives to encourage investment in the mining sector. They recognize the value of their contributions to mining projects by way of guarantees and the provision of infrastructure. Third World governments now seek to participate in the basic decision making which determines profitability, such as loan-equity ratios, plant capacity, and processing and sales arrangements. They are alert to the benefits of large-scale development and appreciate their risks. They seek to increase their benefits from foreign exchange earnings and the multiplier effect of mining projects. New forms of arrangements are being used to insure that the mining sector is developed in harmony with the national objectives of the Third World.

Jan 1, 1977

Throughout October, U.S. producers priced unalloyed 99.5 percent aluminum ingot at 53¢ per pound. Dealers, in last month's domestic market, were quoting unalloyed ingot at a range of 45.5¢-46.3¢ per pound. Costa Rica recently issued a proposal to Japanese aluminum smelters to participate in an integrated aluminum-refining project which would include bauxite development. The project reportedly would include a 600,000-kilowatt hydroelectric power station, a 600,000-metric-ton-per-year alumina plant, and a 300,000-ton-per-year primary aluminum smelter. Two U.S. firms--Aluminum Co. of Amerjca (Alcoa) and Martin Marietta Co.--and several European aluminum smelters are also said to be interested in taking part in this project. Alcoa conducted a feasibility study for the Costa Rican Government in 1970 and estimated the bauxite reserves to contain 150 million metric tons.

Jan 1, 1977

By M. L. Connolly

Zinc production by Cominco Ltd. began in Trail in 1916 at a rate of 55 metric tonnes per day (t/d) and was increased ,in several increments until now electrowinning capacity approaches 750 t/d. The last increment, 40-t/d high-productivity electrowinning plant, was commissioned in 1974. In this paper, the design and operating experience with both the existing electrowinning plant and the new high-productivity plant are described.

Jan 1, 1977

By Skinner A. J, Thoman B. C

The general structure of microprocessors and their method of use is described, and de- tails given of their application in two parti- cular examples of instrumentation for mineral concentrators. One is in a pulp density gauge, and using this example, the way in which a microprocessor-based unit can be made to be self-calibrating is described. The other is in an on-stream analysis detector for uranium in solvent, where a microprocessor is used to re- place a mini-computer.

Jan 1, 1977

By Robert A. Melton

Since many of the easily mined, continuous, thick coal seams in the Appalachian Region have been exhausted, new exploration and mining is being directed toward less continuous seams that are under more cover and are more difficult to mine. The direct results of this are that more money and time and more expertise and data are needed to plan and open new coal mines today. It is also becoming apparent that the old methods of assimilating and preparing information needed for mine planning are inadequate to meet the needs of today's modern mining engineer, especially in the areas of data gathering, storage, retrieval, preparation, and interpretation. The system described here allows assimilation of old and new core data in a relatively quick, accurate, and efficient manner. The system is a set of computer assisted procedures consisting of the following four basic steps: 1) raw data collection, computer input, storage, and graphic preparation, 2) geologic profile correlation and establishment of seam continuity, 3) computerized data posting of important seam parameters, 4) geologic and planimetric analysis for mine planning.

Jan 1, 1977

By Wayne D. Gould

Cities Service Co.'s Pinto Valley concentrator was designed to eliminate excess capital costs without loss of efficiency. The result is a workable plant with some important innovations. These innovations, the equipment used, and plant processes are outlined. Particular attention is paid to the work efficiency and wear of the six ball mills, the largest wet ball mills made. For experiment purposes, four designs of liners were installed. The effectiveness of each design is discussed.

Jan 1, 1977

By J. E. Forbes

Oxygen enrichment of the converter air at Rustenburg Platinum Mines by J. E. FORBES (Associate Member)* An account is given of the adoption of oxygen enrichment to accelerate converting operations and so permit the handling of larger quantities of feed materials. In addition to achieving its object, the use of oxygen-enriched air (6 per cent oxygen by volume) results in an increase in the concentration of sulphur dioxide in the converter off-gas. The slags have the same composition as those produced without oxygen enrichment, and the operation of the converters is easily controlled.

Jan 1, 1977