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By Thys B. Johnson

A three-dimensional dynamic programing method is presented for determining the optimal ultimate open pit limit. The method given is based on the block concept and is an extention of the two-dimensional Lerchs-Grossmann approach. The three-dimensional technique presented herein is fast and simple and may be used for an initial open pit evaluation when only limited data are available or as a more refined model when the entire deposit is well delineated. The method is illustrated by simple numerical examples and is also presented in algorithmic form. A computer program was written in Fortran IV which implements the three-dimensional algorithm and some computational aspects are discussed.

Jan 1, 1971

[Adams, Dell H Consolidation Coal Co., 3300 One Oliver Plaza, Pittsburgh, Pa. Adams, Douglas K General Electric Co., P.O. Box 2331, Denver 1, Colo. Adams, Kenneth L Peabody Coal Co., 33 Carnation Dr., Belleville, Ill. Ahlborg, William Joy Mfg. Co., 580 Denver Club, Bldg., Denver, Colorado Albrechtsen, Ray H Mt. States Resources Corp., 2330 S. Main, Salt Lake City, Utah Allen, Dr. Harry C U. S. Bureau of Mines, Washington, D. C. 20242 Amerman, Richard W Utah Cons. & Mining Co., Box 155, Fruitland, New Mexico Anderson, G. A Walker Bank & Trust Co., 848 N 3rd E, Price, Utah Anderson, John S. Utah Cons. & Mining Co., 550 California St., San Francisco, Calif. Anderson, Robert Mine Safety Appliances Co., 1881 West N. Temple, Salt Lake City, Utah]

Jan 1, 1971

By Norbert R. Morgenstern

INTRODUCTION An understanding of the role of water in controlling the stability of rock masses is central for a rational approach to the subject. The presence of water can hinder mining opera- tions in two ways: 1. excessive discharge 2. excessive pressure It should be noted that if the rock mass is very tight, excessive pressures can exist without large discharges. Alternatively, if abundant water is available and the rock mass is open, then substantial discharges can occur under quite small pressures. The problems associated with excessive discharge are usually well understood by the mining engineer. Vehicle mobility is inhibited, some areas are flooded and hence become inaccessible; at best, a costly nuisance exists. The methods of solving these problems are also well-known to mining engineers. They generally involve tapping the source of the excessive discharge and channeling it away in such a manner that any hindrance to the mining operation is minimized. The effects of water pressure on the stability of rock masses are less obvious and the following will be devoted solely to this aspect of the problem. The manner in which water pressures enter into the consideration of stability is made clear by an understanding of the concept of effective stress. THE CONCEPT OF EFFECTIVE STRESS The simplest mechanical model for the problem of rock slope stability consists of a rough, rigid block sliding down an inclined plane under the influence of gravity. This is illustrated in [Fig. 1]. The down-slope component of the weight of the block tends to produce movement which is resisted by the shearing force generated by friction along the base of the block. The shear stress per unit area inducing movement is

Jan 1, 1971

By J. Grumer

Nine dust and gaseous inhibitors of propagating coal dust-air flames (lean, stoichiometric, and rich) were evaluated in a newly developed 15-cm-id, 3.6-meter-long instrumented flame duct, under conditions such that wall quenching was virtually absent and the dust concentration was temporally and spacially uniform to within about t5 percent. Listed roughly in order of increasing efficiency, the inhibitors evaluated were rock dust (calcium carbonate), powdered oyster shells (calcium carbonate), Halon 1301 (trifluorobromomethane), Halon 1211 (difluorochlorobromomethane), sodium chloride, Super-K (potassium chloride), regular-grade fire extinguishant powder (sodium bicarbonate), Purple-K (potassium bicarbonate), and Monnex (potassium bicarbonate combined with urea). Experiments were extended to clouds containing 1 and 2 volume-percent of methane. The inhibition of lean, stoichiometric, and rich methane-air flames without coal dust was also examined in a few instances; results agreed with those obtained for coal dust-air flames.

Jan 1, 1971

Previous methods for measuring the flow of solids in Jnrdraulic conveying have not considered the important effects of slip velocity and particle concentration. In this paper an extension of the method proposed byShirato et al. (J. Chem. Engng. 'Japan, 1: 164-167) for determining mass flow in a vertical conduit is outlined.The present method consists of measuring' the volumetric flow of the slurry (by a magnetic flow meter for instance) and the density of the slurry in two pipe sections of different diameters. Effects of variation of slip withparticle concentration, not previously considered, are allowed.Problems involved in estimating the density of a slurry from differential pressure measurement are discussed.The major problem is the uncertainties in estimating frictional losses due to the wall in two-phase flows. The greater reliability of a more "direct" technique, such as by 'Y-ray absorption, for measuring solid concentration is emphasized.

Jan 1, 1971

By Jacques B. Wertz

However excellent the geologic map of an area is, it can only show what is exposed on the ground. It cannot and should not generalize the information nor complete the picture by inference: this is left to the examiner. Consequently, it becomes justified for him to use all expressions of geologic structure in order to gain an additional dimension in geologic interpretation, and particularly so in mineral exploration. In previous studies related to Arizona, the known faults were the starting points and a host of interpolated, supporting geologic factors described in earlier publications ascertained the presence of a series of structural trends and lineaments found to be rather continuous and persistent, even though unsubstantiated by geologic maps. In present studies pertaining to the humid environment, with the same aim of seeking major structural trends and lineaments, the starting points are morphologic expressions such as straight lakes and straight segments of rivers, among others, because there generally is not enough geology available. An example is given herewith for an area that straddles the International Border, north of Spokane. In both semi-arid and humid environments, one observes that mineral deposits quite often occur close to the intersection of a major fracture or lineament with some secondary trend.

Jan 1, 1971

By J. M. Stuve

Calorimetric determinations of the low-temperature heat capacities, standard enthalpy of formation, and high-temperature enthalpies were made of (Na20)4 ?Fe20,(c). The resulting values of entropy (S°), enthalpy of formation (?Hf°), and free energy of formation (?Gf°) at 298.15° K are 104.676 cal/deg mole, -656.2 ±.kcal/mole, and -603.4 A kcal/mole, respectively. Tabulations of Cp°, S°, - (G°-H°298)/T, H°-H°298, ?Hf°, ?Gf°, and log Kf are given to 1,200° K.

Jan 1, 1971

By Joe B. Rosenbaum

New applications and concepts of solvent extraction as a unit operation in extractive metallurgy have been developed in the last decade. Wider use is being made of established solvent extraction techniques in processing spent nuclear fuel elements and in winning columbium-tantalum, hafnium-zirconium, thorium, tungsten, uranium, and vanadium. Commercial application has been extended to recovery of beryllium, boron, bromine, copper, molybdenum, phosphorus, rare-earth metals, and rhenium. Systems in use and proposed typically extract metals or salts as anion, cation, or neutral species from aqueous media by reaction with a recycleable organic reagent.

Jan 1, 1971

A process was developed, on a laboratory scale, for the removal of iron oxides from Weipa pisolitic bauxite. The technique involves the chemical reduction ofthe iron oxides by carbon, followed by selective removal of the iron species by acid leaching or chlorination.To remove more than 90 per cent of the iron it is necessary to reduce the iron oxides substantially to iron metal by heating the bauxite, pre-calcined at 650-800°C, with reactive carbon at 1040-1100°C. Reduction proceeds via the intermediate formation of hercynite (FeO.Al2O3) and difficulties have been encountered in reducing hercynite formed under less favourable reduction conditions.Following reduction, efficient selective removal of iron species is readily effected by acid leaching using dilute hydrochloric acid at 100°C, or chlorination at 500-750°C using Cl2, Cl2/N2, or Cl2/N2/CO mixtures.After removal of unreacted carbon, the final products contain 0·5-1.0 per cent Fe203 and 87-92 per cent Al203.

Jan 1, 1971

By M. M. Tilman

The Bureau of Mines conducted research into the dispersion strengthening of lead by the coprecipitation method. Commercially available reagents in water solutions were reacted to form homogeneous precipitates of lead and aluminum compounds. The resulting precipitates were roasted to oxides and reduced in hydrogen to form mixtures of lead powder and alumina. The powders were isostatically pressed into billets which were extruded into rods. The rods were rolled into strip to provide material for testing. Alloys containing 0.5, 1, 2, and 3 nominal volume-percent A1203 were tested in short-time tensile tests and in tensile creep tests. An alloy of Pb-3 volume-percent A1203 exhibited an average tensile strength of 8,570 psi after rolling to 75-percent reduction at 125° C but had no measurable elongation. Alloys of lower A1203 content provided a better compromise between tensile strength and ductility. For example, an alloy of Pb-0.5 volume-percent A1203 had an average tensile strength of 6,590 psi with 9-percent elongation after rolling to 75-percent reduction at 125° C. Creep rates of dispersion-strengthened Pb-A1203 alloys were below 1 percent in 10,000 hours at stresses of 2,000 to 4,000 psi.

Jan 1, 1971

Christmas Island "C"-grade phosphate consists essentially of the minerals crandallite and millisite. Although containing over 25% P205, this material is not suitable for the manufacture of water-soluble phosphate fertilizers by conventional processes, because of its high iron and aluminium content Cover 25% total R203). In order to produce a water-soluble fertilizer from such material it is necessary to separate the iron and aluminium from the phosphate, which must report in a product acceptable as a fertilizer. Several processes were studied in detail. The first used ion exchange for dissolution and separation and yielded diammonium phosphate; processing costs were high compared with conven- tional processes based on apatite. The latter processes have basically simple flowsheets and cost of processing is low when compared with the costs of the raw materials. The need to separate iron and aluminium from the phosphate introduces additional complexity into the treatment of the C-grade material. The higher processing costs might be justified, however, if alumina could be produced as a byproduct. Two proposed processes have been developed in which: 1. hydrochloric acid is used for dissolution, and solvent extrac- tion for the separation of ferric chloride from phosphoric acid. Aluminium chloride is precipitated and hydrolysed to recover alumina and hydrochloric acid. 2. sulphuric acid is used for dissolution and aluminium is crystallized as ammonium alum. The phosphate is produced as an ammonium phosphate-sulphate fertilizer. High purity alumina can be obtained by treatment of the recrystallized alum. The technology of these processes is described, and their broad economics discussed briefly.\

Jan 1, 1971

By F. W. Tregarthen

"This paper gives a brief description of the methods used to form and implement the present planned maintenance program. The system is designed to assist plant personnel in their task of controlling a large work-force and maintaining the many and varied types of equipment used in a mining and concentrator operation. The types of reports and methods used in scheduling and work-loading are described. General built-in flexibility is derived from computer assistance to the Central Planning Group."

Jan 1, 1971

By Bruce A. Kennedy, Richard M. Stewart

Slope stability has now become a practical tool in the design and operation of open pits. The selection of slope angles is a critical decision that can have far-reaching effects on the accumulated cash flow and the overall profitability of a mining project. Slope failures can now be dealt with in a number of ways. Two methods - the total removal and the partial unloading of a failing zone-have been practiced for many years. However, with the refinement of monitoring techniques, open pits can now learn to live with a slide and even turn a potential loss into a gain. There are various techniques, such as presplit blasting, drainage systems, and artificial stabilization, which can be applied immediately in an existing open pit to improve the stability of the pit slopes. The technology of slope stability will play an important part in the future mining of low grade, previously marginal orebodies, which will have to be exploited if the mineral needs of the world are to be met.

Jan 1, 1971

Air pollution control regulation$ already implemented or being considered for implementation require substantial investment of capital to remove the sulfur oxides from copper, lead, and zinc smelter gases. There will be an attendant increase in production costs and possibly an associated increase in the price of these metals to the consumer. The total investment and any resultant metal price increase will depend upon the control regulations that ultimately will be adopted by the individual States. Controversy has arisen between the metals industry and governmental control agencies regarding the status of stack gas desulfurization technology and the ability of industry to control sulfur oxide emissions to the degree proposed by some of the more stringent regulations currently under consideration. This paper evaluates the problems involved in achieving various degrees of control over smelter sulfur oxide emissions and the technology available to accomplish the task of assuring clean air. The estimated cost of compliance is reviewed for the copper, zinc, and lead industries, but principal at tent ion is given to the copper situation.

Jan 1, 1971

Approximately forty years ago, the military services began a realistic investigation of the problems involved with the replacement of high pressure gaseous systems with liquid oxygen systems. The program was temporarily discontinued because of numerous State-of-the-Art problems. Ten years later, interest in the liquid oxygen breathing concept was revived. Initial testing of this concept was completed in 1946. The ensuing years have seen the general acceptance of many cryogenic breathing systems for airborne applications. The inherent features of weight savings (approximately 70%) and space savings (approximately 80%) make it very desirable for high performance military aircraft. A typical aircraft system consists of a storage container with appropriate integrated control valving (the liquid oxygen converter), a heat exchanger, breathing regulator, and oxygen mask. Normally the liquid converter is located in the aircraft wheel well for easy access by ground crew personnel and the breathing regulator is mounted in the cockpit where the pilot can connect his oxygen mask. An aircraft system such as this will provide the pilot with eight hours of breathing oxygen after a 24 hour standby period. Early in 1960, the National Aeronautics and Space Administration sought a means of providing a cooling system for their personnel involved in fueling the rockets used in the space program. While fueling rockets N.A,S.A, personnel wore a completely enclosed butyl rubber suit and were susceptible to heat prostration. Using the concept of an aircraft system, Aro redesigned the container, heat

Jan 1, 1971

By J. D. Wilkins

"Ore outcrops were first discovered in the area in 1911. Following various periods of exploration by private interests and Cominco Limited, the Coast Copper Company, Limited property was brought into production in August 1962. Subsequently, Cominco explored the adjacent Quatsino Gold Mines property and is currently developing, and producing from, what is now known as the Benson Lake Mine.The Benson Lake Mine was developed using a conveyor-equipped decline and trackless LHD equipment. The operation produces 800 tons per day of copper-iron ore, copper being the main product. Copper and iron concentrates are trucked 25 miles to storage and shiploading facilities near Port McNeill to await shipment to Japan."

Jan 1, 1971

By Evert Hoek

SYNOPSIS It can be shown that the properties of intact rock are relatively unimportant in rock slope stability and that failures are controlled by structural discontinuities such as bedding planes, joints and faults in the rock mass. The frequency, orientation and inclination of these discontinuities as well as their strength characteristics are important factors to be considered in any rock slope analysis and their influence will be demonstrated by means of a number of practical examples. Methods for determining the mechanical properties of discontinuities will be reviewed and the interpretation of the strength test results for use in stability computations will be discussed.

Jan 1, 1971

By J. W. Adams

This report surveys the efforts of six contractors to the U.S. Bureau of Mines with regard to their electromagnetic noise measurement programs. What has been done, what is planned, and evaluations and recommendations are given for each contractor. The main observation is that to date there is not sufficient knowledge of electromagnetic interference in mine environments to design a reliable communication system. This knowledge should be available by the end of June 1972 if certain planned programs are completed successfully. A major effort of this report is to establish parameters to be measured, units to be used, and workable formats for data presentation. This is given in Appendix A. Some details concerning equipment, procedures, locations, and sample data are included in Appendix B.

Jan 1, 1971

By Walter E. Lewis, Robert L. Marovelli

Underground support has a long history as evidenced by Agricola's general description in Dc Re Metallica:1 "The timbering of these openings is done as follows: stulls are set at intervals into hitches in the hanging and footwall, and upon them smooth poles are laid continuously; and that they may be able to bear the weight, the stulls are generally a foot and a half thick. After the ore has been taken out and the mining of the vein is being done elsewhere, the rock then broken, especially if it cannot be taken away without great difficulty, is thrown into these openings among the timbers, and the carriers of the ore are saved toil, and the owners save half the expense. This, then, generally speaking, is the method by which everything related to the timbering of shafts, tunnels, and drifts is carried out."

Jan 1, 1971

By D. G. Kuehn

Positive ion sampling studies have been conducted on do discharges containing 0.33 percent sulfur dioxide in helium. Measurements were made for normalized gas pressures from 0.45 to 6.8 torr and discharge currents from 5 to 40 ma. Ion species observed included SO+, S+, SO2+, SO3+; O+, and 0+, 02+. Studies were conducted on the functional dependence of the various ion species with respect to axial distance, pressure, current, and gas flow rate. Interpretation of these results is consistent with the assumption of SO2 dissociation. Deposition of sulfur compounds was observed in the plasma container during these studies. The present results are compared with previous studies which have been conducted in SO2.

Jan 1, 1971