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By E. A. Rychkun

It is essential for a. mining company to determine an optimal mining strategy which will maximize the return on investment. In the case of Placer Development Ltd., the Lerch-Grossman three-dimensional optimization technique has been implemented on a digital computer to assist in the determination of such a strategy. It is the purpose of this chapter to explain and illustrate the methodology of the Placer Development Ltd. computer system with emphasis on the feasibility phase of a mine's development. In the Placer Development Ltd. strategy determination process, it is essential that certain objectives be considered: 1) There must be some means of constructing a realistic computer model of an ore body which gives a significant weight to geological constraints. 2) Data must be accurate and quantifiable. 3) Computer solutions must be unique, i.e., approximation or iteration methods of determining optimal solutions are undesirable. A method must be used which, when given fixed parameters and data, yields a mathematically sound unique solution. The following material is a presentation of how these objectives have been implemented. The flow of this outline will be from the general to the specific, with an example application.

Jan 1, 1979

By Charles D. Litton

An overview of state-of-the-art technology in fire detectors is presented by the Bureau of Mines regarding their use in the mining industry. Detectors are categorized according to the characteristics of a fire to which they respond. Operating principles of the various detectors, their application, and the advantages and disadvantages of each are discussed.

Jan 1, 1979

"10.1. IntroductionAs discussed by Westland (1981), the six platinum-group elements (PGE) belong to the Group VIII transition metals, to which iron, nickel and cobalt also belong. The chemical similarity between these nine metals accounts for the fact that they tend to be concentrated together as a result of geological processes. These processes started to effect the distribution of these metals at the very beginning of the earth's history.The first line in Table 1 gives the concentration of nickel and certain other Group VIII transition metals in carbonaceous chondrites, those meteorites with a composition that is believed to reflect best the composition of our planetary system apart from hydrogen and helium. The second line is the estimated concentration of the same elements in the earth as a whole. It is seen that these two estimates are quite similar, the earth being perhaps 2 to 3 times richer in these particular metals than the planetary system as a whole. The reason for this is not fully understood, but it may be due to the earth being formed by the accumulation and capture of a greater proportion of iron (and therefore siderophile-rich) than stoney (and therefore siderophile-poor) planetesimals than the planetary system itself.The third line in Table 1 is the average composition of the crust of the earth. With the exception of iron, all of the Group VIII transition elements are rare in the crust, present at concentrations of It tOO to Itt ,000 of that of the bulk earth. This is because the outstanding chemical characteristic of this group of elements is their siderophile nature; that is, their tendency to alloy with metallic iron. Because of this, once the earth became molten very early in its life history, these elements dissolved in the molten iron present at this stage and were removed from the outer accessible parts as this dense liquid sank to the centre of the earth to form the core. Although iron was the main instrument of concentration of the Group VIII metals, its much greater over-all abundance and its ability to combine with oxygen more easily than the others in the group means that significant amounts still remain in the oxidized portions of the earth.The fact that most of the Group VIII metals are available to use in workable concentrations at all is that they are 5 to 30 times more concentrated in the earth's mantle than the crust, as shown in line 4 of Table I. There has been a constant, if slow, interchange of matter between the mantle and the overlying crust throughout most of the earth's history and, under certain circumstances, this interchange has given rise to economic concentrations of metals."

Jan 1, 1979

By E. J. Mayhew

Bentonite and newly discovered deposits of sepiolite, saponite, and hectorite are now being processed and marketed from the Amargosa Valley of Nevada. All of these deposits are large. The bentonite has been known for decades and is the whitest known. The only other sepiolite deposit is in Spain. The only other commercial hectorite deposit is at Hector, California. No other saponite deposit is known. All the components except bentonite are hydrous magnesium silicates. The bentonite is mixed layer Na-Ca. All the materials have characteristics unique to their locale and type, such as high yield point for drilling muds and liquid suspending agents. The sepiolite has geothermal stability. Figure 1.

Jan 1, 1979

By Peter Bush

The deposition of metastable carbonate minerals in ar. aid, sheltered, coastal environment, leads to the formation of a flat, coastel, sabkha plain. The ground waters of the sabkha plain are modified by evaporation, precipitation of salts and reaction between ions in solution and the host carbonates. The resulting brine is similar to those found in fluid inclusions associated with Mississippi Valley type deposits. The aragonite and high magnesium calcite found in the sediments can concentrate lead and zinc from sea water. On diagenesis the lead and zinc are released into the sabkha brines.

Jan 1, 1979

By John Durkin

A computer model has been generated to evaluate speech intelligibility of individuals wearing conventional and electronic hearing protectors. For speakers talking at normal levels in noise levels of 65 db(Lp) or less, it was found that conventional hearing protectors significantly reduced speech intelligibility. Under the same conditions, electronic protectors provided scores equal to those for the unprotected individuals while providing protection from high noise levels. Therefore, electronic hearing protection is valuable in areas where high noise level is intermittent.

Jan 1, 1979

By G. R. Parslow

U, Fe, Mn, Ni, Cu, Zn and Co data for the sediment in both Key and Seahorse lakes, which overlie portions of known economic uranium deposits in the region, are presented. With the exception of U, Fe and Mn, the elemental distributions can be considered anomalous, in a statistical sense, in both lakes. The U values are of particular interest in that Key Lake is not anomalous, whereas Seahorse Lake is markedly anomalous. Tentative correlations made with background data from other surveys in an attempt to differentiate between anomalous and background values indicate that deviations from linearity in a distribution, and not absolute mean or maximum values, are indicative of anomalous samples within the distribution.

Jan 1, 1979

By James M. Barker

The occurrence of borates and zeolites at Mesa del Alamo is well documented by McAnulty and Hoffer (1) and Lefond and Barker (2). Further investigation indicates the presence of priceite and meyerhofferite in addition to the howlite (1) and colemanite (2). Analcime occurs in addition to the clinoptilolite and phillipsite (2). The Mesa del Alamo area is about 200 !a south of Tucson, Arizona, and 13 km southeast of Magdalena, Sonora, Mexico, just south of the unpaved road to Cucurpe (Figure 1). The geology and mineralogy of northcentral Sonora is known only on a regional basis except for small areas mapped in detail during copper exploration. The study area is within the Basin and Range province of North America from which borates and zeolites are now produced in California. The borates and zeolites at Mesa del Alamo occur in geological environments similar to those of the Mojave and Death Valley regions of California (3, 4). Thus, a detailed exploration pro- gram in the Magdalena area could result in the discovery of economic borate and/or zeolite deposits.

Jan 1, 1979

By G. Favini

A Bayesian decision model of minimun risk, based on the probability and costs of mine discoveries and non-economic projects, is presented for massive sulphide exploration in the Canadian Shield. The sample used for the model is composed of data relating to forty mines, sixty non-economic sulphide occurrences, and sixty occurrences of graphitic and pyritic material. These economic and barren samples consist of drill-tested occurrences which were, in varying degree, characterized by conductivity anomalies. Given the large size, the reliability and the homogeneity of the data base available for massive sulphide exploration, it is shown that certain statistical models can and should be utilized as a tool for decision-making by explorationists. Given this data base, information theory tells us that only those signals that are independent of one another will transmit information with minimum error. An ensemble of six significant multilevel signals, markedly independent of one another and consisting of numeric and geometric form descriptions derived from Bouguer anomaly, aeromagnetic and physiographic maps, were identified and evaluated by case studies. The use of these signals as input in a simple statistical procedure, or in a carefully planned and experienced visual appreciation scheme, can be of significant aid in decisions concerning the choice of favourable areas or sectors to explore in detail. The method of discriminant analysis is theoretically and practically suited for the statistical modelling involved. By way of a simulation on our statistical model, the efficiency of the model and of the underlying criteria is determined for historic cases and, by inference, for its validity in future exploration. An approximate optimized solution is derived from the model which suggests that over 90% of the known ore could be found by screening, according to a model such as that herein described, and drilling only 30% of the targets (mostly barren) normally identified and tested in current and past exploration.

Jan 1, 1979

By Robert W. Freedman

In the Bureau of Mines study, a filter with a 20-by 20-inch-square cross section was inserted into the exhaust ducting of a 4-stroke-cycle, 90-hp diesel engine, and the efficiency of removal of total particulate was measured gravimetrically as a function of time. Removal efficiencies were close to 90 pct during the main portion of several extended runs employing several combinations of filter beds. Variations in engine load had little effect on collection efficiency. Particle size as measured by a Bureau-developed online instrument centered on 0.07 m based on number count. Removal efficiency increased rather sharply for both larger and smaller particles.

Jan 1, 1979

By Frederick W. DeVries

Since we first agreed to present this talk we have learned that some of you may have been covering ground we intend to discuss: Bob Schechter, Daryl Tweeton, Don Seidel, Herb Burgman; however, the ideas were original when we began, "novel" as in the title of the talk, and whether our results are news or merely corroborative, we feel they point a direction that could be valuable to all. We worked with many of you in the past on using hydrogen peroxide in in-situ uranium leaching. Our talk today is not directly related to peroxide; it is, I hope, illustrative of Du Pont&apos;s interest in providing service to this industry in any way we can. The scouting work we are presenting was stimulated by field inputs: First, ammonium carbonate leaches cause restoration problems, primarily because ammonium ions exchange on clays with calcium. Second, sodium carbonate solutions, especially in South Texas deposits, can cause intolerable swelling of clays. From discussions with Dr. van Olphen, who wrote the book on clay chemistry, we inferred by comparison of the radii of the hydrated ions of the elements in these clay systems, that since potassium had about the same radius as ammonium, and sodium was much larger, potassium occupied a unique position to solve both problems. We have shown: FIGURE 1 Potassium bicarbonate systems leach uranium without loss of permeability found with sodium Potassium salts are very effective in restoring ammonia-leached sites Before reviewing the details of our work, which was performed by Hazen Research, Inc., I should like to stress its scouting nature. We are trying to assist the in-situ industry by pointing out new, potentially important directions. But, as with our previous work on sodium silicate to restore permeability, we feel the development phases can generally best be carried out in cooperative programs with companies directly involved with operations. DISCUSSION Test Parameters Now for the details: Our leaching tests were designed to note pressure-drop changes across the ore sample as the uranium was leached. Figure 2 shows the apparatus. The [ ] packed length was 20.5 inches (52 cm) with fifteen hundred grams of ore in the two-inch (5 cm)-diameter bed. Pressure drop was measured by manometer and feed rates were maintained constant with a tubing pump. The samples, from a South Texas leach site, were sealed in "Zip Loc" bags, frozen with "dry ice", crushed (still frozen) through six mesh, and blended before placement into the columns. The ores analyzed as shown here: FIGURE 3 Ore Analyses [Sample A Sample B U308 015% 0122% Mo 0004% 0086% Se0012% <0001% Fe3,078%076% Fee- 098% 044%]

Jan 1, 1979

By A. F. Banks

INTRODUCTION Selective flocculation-flotation as a method of desliming potash flotation feed has been practiced in the Cominco Ltd. potash plant since November. 1974 when it was installed to replace a less efficient mechanical desliming process. The plant was designed for a consistent feed containing 4.5% insolubles. In practice the quantity and quality of the insoluble material is quite variable. This variability led to serious problems in the deslime circuit and consequently had an adverse effect on sylvite flotation performance. A costly mechanical solution to the problem was being seriously considered when it was drawn to our attention that a selective flocculation-flotation process had been developed. The process was tried first in the laboratory on the Cominco Ltd. ore, then on a pilot basis on 25% of the mill feed and finally full scale. The time from being informed of the process to full scale operation was 18 months. It has since been incorporated into a tailings regrind circuit. The original mine design called for the mining of an 11 foot height up to the top of the three clay seams. These had to be taken as they were a zone of structural weakness. It also assumed that the beds would be uniform with only a few disturbances. Very soon after the initial start up it was found that permanent openings had to take in the layers right up to the upper clay seams and because of the mining process that this material would have to be milled when encountered. The number of disturbed areas in the mine is greater than the design anticipated. In operation the insoluble content of the mill feed varies from 4.5% to 8% plus with the peaks being very short- term to relatively long, from hours to day. In terms of quality, the insolubles in the mining horizon are relatively soft and easily liberated, whereas those above are hard and liberate slowly.

Jan 1, 1979

By Lex L. Udy

External-detonation-generated plasmas, highly ionized zones of reacting material ejected from the surface of detonating explosive charges, are shown to be the cause of channel desensitization, i.e., the self-quenching of a detonating explosive column loaded in a borehole with an air annulus between the explosive and the borehole wall. The effects of this phenomenon on several explosive compositions and types are demonstrated and discussed. The explosives tested include aluminum-sensitized and explosive-sensitized slurries, ANFO, liquid explosives and dynamites. Various techniques are described that can be used to reduce or eliminate the plasma effect.

Jan 1, 1979

By R. V. Ramani, R. M. Mishra, Y. J. Wang

The validity of the concept of mine resistance in ventilation systems is examined. Mine resistance is the proportionality constant relating the head generated by a fan and the quantity flowing through it when the fan is connected to a mine circuit. It is the total effect of all branches in the mine ventilation circuit. Its importance lies in the fact that for new mine projections, and in the extensions of existing mines, ventilation calculations are usually based upon adjustments of the mine resistance. In ventilation circuits with regulation, and/or with multi-fans, simple adjustments of the mine resistance curve do not lead to correct solution. A ventilation system consists of several interconnected subsystems where one subsystem behavior affects that of the others, and the total system. Through a series of simple but realistic examples, the authors demonstrate the importance of the systems concept in mine ventilation, and its practical application to coal mine ventilation planning. Starting from an initial system with no leakage and one fan, more complex ventilation networks with several leakages, sections and fans, are analyzed to show that ventilation system design on the basis of total systems approach is the correct procedure.

Jan 1, 1979

By D. D. Downing

This paper is a review of material selection considerations concerning protective coatings in the mining industry. The discussion will cover both capital-dollar projects and maintenance requirements. Emphasis will be on industrial finishes for structural steel and process equipment subjected to aggressive atmospheres. The presentation will cover the total needs of a job, emphasizing not only the owner&apos;s requirement for a cost-effective system during plant operations, but also taking into consideration the short-term requirements of general contractors, steel fabricators, erection firms and paint contractors.

Jan 1, 1979

By A. J. Brown

This paper presents an economic evaluation of resin ion exchange and solvent extraction for the purification and concentration of uraniferous solutions derived from sulphuric acid leaching operations. Capital and operating costs are related to the uranium tenors of pregnant solutions. The conclusions drawn herein apply only to cases where resin and liquid ion exchange are technically feasible process alternatives. It is shown that solvent extraction is economically favoured for pregnant solutions at tenors greater than 0.90 gpl U3O8. Pregnant solutions with tenors below 0.35 gpl U3O8 are best treated by resin ion exchange. Between these concentrations, the economics are marginal and the favoured process is indistinguishable within the limits of accuracy of this study.

Jan 1, 1979

By Håkan Stille, Kjeld Boye-Møller, Lars Lundström

BACKGROUND Forsmark Power Station is a nuclear power plant under construction at the Baltic abt 120 km north of Stockholm. Investigations on the Site were started in 1969. Areas were reserved for a maximum of 6 units of which the buildings for two of them, Unit 1 and 2, were nearly finished in 1976, when the investigation for Unit [3], here presented, was carried out, cf Fig. 1. [ ]

Jan 1, 1979

By Vytas Svalbonas

Sophisticated computer analysis methods such as finite elements, finite differences, and numerical integration have become tools in the mineral processing industry for design of large mill shells. While use of such methods allows the analyst-designer to take new freedoms with his designed structure, there are also pitfalls and dangers which must be recognized for the proper use of such sophisticated tools. One of the worst of these is treating any computer answers as "gospel truth". The present paper discusses the knowledge required by the analyst-designer for proper use of computer analysis, as well as explaining to the layman how to identify questionable areas in such structural analyses.

Jan 1, 1979

By K. D. Hester

This paper will review the metallurgical aspects of the completed expansion program at Quirke, and the current rehabilitation and refurbishing program at Panel. During the Quirke program, completed at the end of 1977, the plant capacity was increased from a nominal 4,500 to 7,000 short tons per milling day. The expansion of crushing, grinding, neutral thickening and filtering, leaching, partial neutralization, sand-slime separation, sand washing, C.C.D., clarification, ion exchange, mine water treatment, and tailings neutralization and pumping will be considered. The application of Enviro-Clear thickeners in the mine water treatment circuit and in the C.C.D. will be briefly reviewed. An automatic grinding and classification circuit for limestone will also be covered. The refurbishing program underway at Panel will be discussed. The Quirke and Panel plants will be contrasted and compared. In particular, reference will be made to environmental considerations. The innovative system for producing yellow cake at Panel, LAMIX, will be considered as well as the proposed treatment system for Panel tailings.

Jan 1, 1979

Mitsui Aluminium Co. of Japan announced that it would finance 25 percent of the construction costs for the 217,000 ton-per-year primary aluminum smelter being built by Alumax, Inc. at Holly, SC. Mitsui would receive 25 percent of the plant&apos;s production in return. Construction on the smelter began early in 1978, and is scheduled to be completed in 1981. The Aluminum Company of America (Alcoa) announced plans to restart a third potline at its Point Comfort, TX primary aluminum smelter in July. The company previously announced plans to restart two potlines at the facility in May. Reynolds Metals Co. began preparations to restart primary aluminum production in May in one of two 57,000 ton-per-year potlines at its Corpus Christi, TX smelter. The plant has been closed since 1975.

Jan 1, 1979