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By S Lal, S Rost, Q Williams, K Collerson

"An EXTENDED ABSTRACT is available for download. A full-length paper was not prepared for this presentation. Shoshonite suite (absarokite-shoshonite-banakite) and adakite-hosted epithermal Au deposits are a feature of circum-Pacific magmatism. Fijian examples include Tavua (Emperor) and Tuvatu on Viti Levu. New discoveries of shoshonite suite and adakite-hosted epithermal Au mineralisation have been made in the southern Yasawa Islands and in central-northern and central-western Viti Levu. The Fijian shoshonites define four NE–SW trending suites. The oldest is the northern 7.9–5.0 Ma Yasawa suite, followed by the 4.7–3.5 Ma Sabeto–Tavua–Rakiraki suite in northern Viti Levu, the 4.7–4.2 Ma Yanuca–Vatulele suite approximately 20 km south of Viti Levu and the 3.4 Ma Astrolabe suite approximately 75 km further south. Shoshonite suite lithologies with 3.8–3.0 Ma ages also occur in the Lomaiviti islands between Vatu-Cake and Moala, to the east of Viti Levu, defining a trend oblique to the NE–SW shoshonite belts. Seatura, a 3.3–2.8 Ma ocean island basalt (OIB) volcano, sits at the northern end of the Lomaiviti trend shoshonites. Trace element/isotopic chemistries indicate that shoshonite arc magma genesis involved the melting of a hydrated supra-subduction zone mantle wedge and also a lower mantle-derived plume (OIB) component. The upwelling plume provided heat for melting and possibly Au enrichment. Accessing the melt generation zone associated with the plume required a slab conduit or window. Such slab windows form by tearing during subduction or occur at slab edges. Adakites form by plume-induced slab melting. The four NE–SW Fijian shoshonite suites are interpreted to occur in back-arc extensional zones above a slab window (tear) that migrated southward during rollback of the New Hebrides–Vanuatu subduction zone. The plume (Seatura OIB) that is interpreted to have caused mantle wedge melting and formation of the Lomaviti trend shoshonites was focused along the interface between the north-dipping Vanuatu–New Hebrides subduction zone and the west-dipping Tonga subduction zone, which we have seismically imaged at approximately 400 km depth. Our model ‘cracks the metallogenetic code’ for shoshonites and adakites and has regional and global implications for Au exploration.CITATION:Collerson, K, Lal, S, Williams, Q and Rost, S, 2015. Cracking the metallogenetic code for Fijian epithermal gold mineralisation , in Proceedings PACRIM 2015 Congress, pp 219–226 (The Australasian Institute of Mining and Metallurgy: Melbourne)."

Mar 18, 2015

By Taylor R. G

This paper reports a biogeochemical study of the Siberia lode of the Herberton tin field. Soil near the orebody contained high levels of Fe, Cu, Pb, Sn, As, Mld Mn. Polycarpaea spirostylis and Indigofera dominii were associated with these high levels but several other species apparently could not tolerate them. The potential of these species as indicator plants is discussed.

Jan 1, 1975

By Marc C. Bétournay

A mine production locomotive, the world?s first applied industrial fuelcell vehicle, has been designed and tested in the context of a number of proof-of-concept projects supported by the Fuelcell Propulsion Institute, an international consortium of stakeholders dedicated to facilitate the commercialization of fuelcell vehicles. The locomotive?s simple electric-powered motor and controller system was ideal to study a number of requirements related to fuelcell power application: hydrogen power plant operation, underground hydrogen use, risk and regulatory requirements, production performance versus the conventional battery-powered locomotive version under measured duty cycles and production requirements, power plant design improvements for other fuelcell vehicles, and cost-benefit aspects. This article will focus on the design and testing aspects of this project which has led to successful performance demonstrations of the vehicle under surface and underground conditions at two mines. It will also present information on the creation of a safe, reliable and efficient power plant which fulfilled its design objectives, including longer productivity time for a given vehicle fill-up.

May 1, 2003

By Jess Harding

Oyu Tolgoi investment agreement now in full, legal effect Successful completion of a series of conditions to 2009 Investment Agreement was announced March 31, 2010. Full-scale construction now set to begin. First copper-gold commercial production from Oyu Tolgoi expected in 2013. 34% of holding company Oyu Tolgoi LL Cacquired by Erdenes MGL, a Mongolian state-owned resources company. Remaining 66% will continue to be owned by Ivanhoe Mines. ?After 9 years of discoveries at Oyu Tolgoi, a big piece of the future of copper and gold in Asia is poised to become a reality.?

May 1, 2010

By Joseph Gildner, Donald J. Phelps, Jürgen Laubbichler, Christopher Tattersall, David McAllister

The Beacon Hill Station and Tunnels portion of the Sound Transit Central Link Project consists of one mile of twin rapid transit tunnels, an underground station, portals and ancillary works constructed in an urban environment. Presently under construction, the station will set a number of North American firsts including deepest soft ground excavation carried out using the Sequential Excavation Method (SEM).Located in highly variable glacial soil deposits ranging from soft, water bearing sands to stiff, slickensided clays, the station complex and running tunnels proved to be technically challenging during design. Meeting these challenges necessitated an extensive geotechnical investigation, a trial shaft, and state-of-the-art numerical analyses to develop ground conditioning, pre-support, excavation support and structural design. A comprehensive risk identification and mitigation program, and innovative procurement strategy were incorporated into the design and contract bid documents.

Jan 1, 2005

The development and introduction of a preventive maintenance scheme in the coke ovens department, coal preparation section, of The Broken Hill Proprietary Co. Ltd., Newcastle steelworks, is described together with its operation and the results achieved during the first 12 months.'fhe scheme consists essentially of an engineering analysis of the plant to establish maintenance schedules, and to record the details on reference cards.Items are reviewed progressively and a weekly work schedule is prepared, from which work orders are passed on to the maintenance foremen. These foremen in turn originate action orders and issue inspection sheets as required. Results are then reported back to the maintenance planner and used to revise norms, practices, and cycles.INTRODUCTIONWhat is maintenance? Some people consider maintenance to be the work involved in putting things together again after they have fallen apart. The author regards it as the mechanical care and repair of plant machinery and equipment to keep it operating in sound mechanical condition, without undue interference with production processes.Maintenance may be organized or haphazard, and, too often, what has been fondly imagined to be nicely controlled and organized maintenance proves, under pressure, to be more correctly described as haphazard. Haphazard maintenance deals with breakdowns as they occur, and frequently finds itself confronted with more breakdowns than can be handled. Even organized maintenance, if not based on sound planning, can, at times, be found in a chaotic state, because of unexpected and unanticipated breakdown.Properly planned and scheduled maintenance permits an orderly and controlled approach to the problem of maintain...

Jan 1, 1961

By Gabriel Esterhuizen, Tom Goodwin, Scott Schilling, Anthony T. Iannacchione

The Roof Fall Risk Index (RFRI) is a new method introduced by the National Institute for Occupational Safety and Health (NIOSH) to assist the underground stone mine operator in 1) assessing defects the mine strata and 2) rating the relative roof fall risk these defects pose. The RFRI utilizes observational techniques to identify defects in the roof strata caused by local geologic, stress, and mining conditions. Assessment values for ten defined defect categories provides the foundation for estimating a range of risk conditions between 0 and 100 that define the potential for a roof fall. This paper examines how the defect information is collected using two field verification sites and proposes methods to analyze the RFRI data. These examples provide information on how well the method replicates observed conditions and how it might be applied in practice.

During August, 1926, with the consent of Mr. Schell, mine manager, the writer conducted a mill test on this company's concentrators. Mr. Schell not only gave him his permission, but rendered all possible assistance. Although it was impossible to take all the samples one could have wished to obtain, yet the salient points of the mill flow-sheet were sampled for a continuous period of eight hours, and from these samples and separate data supplied by the manager, valuable information was collected.THE MINEThis is a true vein-type of mine; the lode formations, striking almost due north-south, cut the large porphyritic intrusion at right angles. There are three distinct veins on this property - parallel, persistent, and dipping at an angle varying between 40° - 50° to the horizontal.The country rock is very sound, and timber, save for the small amount required for ore chutes, is entirely absent from all mine workings.The lode varies from a width of 1 in. to 8 in., but the stopes are carried forward with a minimurn width of about 30 in.The mine is particularly dry for a West Coast property, and conditions underground are very favourable. Air drills are used...

Jan 1, 1928

By A M. Purba and A Sjadat, A D. Wilson

Ongoing mining of the East Ertsberg Skarn System orebody below the Gunung Bijih Timur and Intermediate Ore Zone caves has been relatively successful and a ramp up to 80 000 t/d was achieved in the Deep Ore Zone Mine. However, the distribution of production, the overall drawpoint availability as well as the rate of change of the cave back profile has not followed the anticipated path. Several key factors influencing cave growth and progress, grade variation, fragmentation, wet muck and surface subsidence have been recognised over the life-of-mine that now have to be taken into account for planning the later stages of mining.The paper will discuss the influence of geological controls of lithology and structure – how this as well as other contributing aspects have impacted ore flow, contributing to some of the widespread panel damage, and been a key factor in compacted draw columns and caused an accelerated appearance of water ingress. This in turn has rapidly changed the distribution of wet drawpoints requiring remote mucking and special controls that also affect the call from the remaining dry drawpoints. Comment is also made on the potential final cave profile if it continues along the current trend and some discussion is offered about possible mitigation measures if this were to come about.CITATION:Wilson, A D, Purba, A M and Sjadat, A, 2016. Progressing cave performance into the later stages of the Deep Ore Zone mine, in Proceedings Seventh International Conference and Exhibition on Mass Mining (MassMin 2016), pp 285–292 (The Australasian Institute of Mining and Metallurgy: Melbourne).

May 9, 2016

By R. Le Houillier, M. Nagamori, A. J. Plumpton

"Asbestos tailings are a typical serpentine, hydrated magnesium silicate, consisting primarily of antigorite and a few per cent of unrecovered fibrous chrysotile. Serpentine has unique thermal properties in that dehydroxylating calcination at 600 to 700°C can yield an amorphous structure in which most of the magnesia is liberated from the original bond with silica and thereby rendered chemically active. The amount of activated magnesia can be quantified by selective leaching with a weak acid such as acetic acid. Many wet processes have been proposed to extract magnesium values from calcined or natural serpentine by means of various acids and their ammonium salts. However, the only commercial utilization of serpentine today is found in dry processes such as the production of fused magnesium phosphate fertilizer .The present paper reviews the physical chemistry of the dehydroxylation of serpentine and also various wet and dry processes in order to provide a general view regarding the chemical transformation of asbestos tailings.IntroductionAsbestos fibers occur as chrysotile, a serpentine polymorph. More than nine tenths of mined asbestos ores consist of massive non-fibrous serpentine, primarily the polymorph antigorite, which is discarded as tailings after fiber extraction. For many decades, Quebec has been a world leader in the production of asbestos fibers. As a result, colossal tonnages of serpentine have accumulated in the Eastern Townships'!'. Serpentine minerals are found in large deposit s throughout the world, and significant research efforts have been made, particularly in Japan and the USSR, mostly in attempts to extract magnesia or silica values therefrom.The chemical composition of serpentine (chrysotile and antigorite) may be ideally expressed as Mg3Si2Os(OH). which corresponds to 43.7% MgO and 43.3% SiO2. Natural serpentines often contain a few per cent of Ni-bearing magnetite and other impurities, and therefore the contents of MgO and Si02are both about 40% or lower.Serpentine (hydrated magnesium silicate) is virtually insoluble in weak acids. However, when dehydroxylated under controlled conditions, ' it decomposes to an amorphous state in which magnesia and silica are isolated and chemically active. The magnesia so activated is readily soluble in weak acids. This unique characteristic of calcined serpentine, first discovered in 1942,, has since attracted the attention of innumerable researchers, whence many processes have been proposed."

Jan 1, 1980

By J. C. Vreugdenburg, B. A. Dippenaar, J. Muller, T. L. de Vries

Iron ore fines are agglomerated to produce sinter, which is an important feed material for blast furnaces worldwide. A model of the iron ore sintering process has been developed with the objective of being representative of the sinter pot test, the standard laboratory process in which the behaviour of specific sinter feed mixtures is evaluated. The model aims to predict sinter quality, including chemical quality and physical strength, as well as key sinter process performance parameters such as production rate and fuel consumption rate. The model uses the finite difference method (FDM) to solve heat and mass distributions within the sinter pot over the height and time dimensions. This model can further be used for establishing empirical relationships between modelled parameters and measured sinter properties. Inputs into the model include the feed material physical properties, chemical compositions, and boundary conditions. Submodels describe relationships between applied pressure differential and gas flow rate through the bed of granulated fine ore particles, combustion of carbonaceous material, calcination of fluxes, evaporation and condensation of water, and melting and solidification. The model was applied to typical sinter test conditions to illustrate the results predicted, and to test sensitivities to parameters such as feed void fraction, feed coke percentage, and the fraction of combustion heat transferred to the gas phase. A model validation and improvement study should follow, ensuring sinter test results are free from experimental errors by conducting repeated tests.

Jan 1, 2015

The applicability of borehole assaying techniques, both conventional and advanced, to orebody evaluation in the mining industry is reviewed and assessed, and the research, development, and demonstration programs necessary to apply the various logging techniques to mining are outlined. At present, the principal method of orebody evaluation in the mining industry is coring. However, coring is costly and time-consuming, and potentially great savings can be realized if all or part of d coring program is replaced by a borehole logging suite specialized to the needs of the particular mining industry. Using a set of 12 minerals, most of which are essential to the U. S. economy, an algorithm is presented for calculating the priority of developing suitable borehole assaying technology to replace all or part of the coring in each mineral industry, The priority is expressed in terms of dollars currently spent for that portion of present orebody evaluation techniques which may eventually be replaceable by in-situ assay techniques. The orebody assay requirements (grades, accuracies, etc.) of the 12 selected mineral industries, as determined from mining industry interviews and published literature, are compiled and represent performance criteria for borehole assaying instruments for the particular industry. Current logging techniques, applied chiefly in the petroleum industry, and advanced assay techniques which are or may be packageable for borehole use are evaluated to determine their performance characteristics. The performance characteristics of the various conventional and advanced techniques are then compared with the performance criteria in each of the 12 mineral industries in order to determine the potential benefit derivable from each technique. Finally, the benefit available from each technique, averaged over the 12 mineral industries, is compared with the cost of development of the technique, to determine the overall priority for investment in research to develop the technique for use in mining. The technology assessment and cost-benefit analysis shows neutron activation analysis in its various forms to have the highest priority for research and development as a borehole logging technique. Other techniques found to be promising include x-ray fluorescence, x-ray diffraction, photoluminescence (optical fluorescence), and infrared spectroscopy. Of the 12 industries considered in the study, those where the need for advanced borehole logging technology is greatest are uranium, copper, gold, and iron.

Jan 1, 1976

By V. N. Cox, C. H. Grant

Both the underwater method and the rock cratering method contribute useful information in evaluating and comparing new explosive compositions. Results indicate that metallized explosive systems which contain no high explosives can be formulated to offer more energy and to do potentially more work than other slurry explosive systems. Commercial field trials are presently being conducted with a metallized explosive that does not contain any high explosive. Although there have been only a few commercial blasts to date, the results are encouraging. The Dow Chemical Co. has been engaged in explosives research since 1953. The incentive for this research was based on the desire to find additional markets and uses for magnesium metal of which DOW is a heavy producer. The thermodynamic calculations for explosives incorporating light metals indicate energies approximately twice that of nonmetallized explosives currently being used. Early in 1960, additional patent rights were acquired from independent inventors and a development station at Virginia, Minn., was set up to conduct a commercial testing and market evaluation program with this new product. The actual manufacturing of the explosive was to take place in the boreholes. Due to the complexities involved in controlling the manufacture of the explosive in the borehole, performance was sometimes in doubt. Furthermore, experience indicated that the metallized explosive systems could not be evaluated by the standard laboratory methods then being used, and it was necessary for us to look for more suitable research methods. Tests were conducted on several known methods for explosive evaluation. The most promising were the Navy underwater method for energy evaluation and a modified Livingston crater method intended to compare explosive performance in rock. After shooting over 2000 charges of 8 to 60 lb under water and in taconites and granites with many types of explosives, a metallized explosive was developed which is now being manufactured at a pilot plant in Virginia, Minn. and is being evaluated commercially. UNDERWATER METHOD An underwater method of evaluating explosives has a number of advantages. A permanent site can be established and operated indefinitely. A large number of charges may be fired in a short length of time. The medium in which the explosive is shot is exactly the same for successive shots. Data are recorded electronically minimizing human judgment. A disadvantage of the underwater method is the lack of confinement provided by the water medium. Many explosive compositions require a greater degree of confinement to develop good energy release. Although the relative significance of the two components of energy release that are usually measured, the shock energy and the bubble energy, and their relationship to breaking rock are not clearly understood, the underwater method is a valuable research tool for screening explosive compositions and gaining an insight into the manner in which explosives release their energy. Fig. 1 shows schematically the underwater apparatus. The piezoelectric gages are calibrated tourmaline crystals which convert the shock wave to an electrical impulse which is transmitted to an oscilloscope and recorded on Polaroid film. The shock traces are picked up by scopes 1 and 2. Scope 1 is timed to pick up the full trace whereas scope 2 is timed to cover the first increment of the shock trace expanded, and therefore allows full inspection of the propagation and peak pressures. Scope 3 records the bubble trace. When the explosion occurs, a bubble of gaseous detonation products is formed. The outward momentum of the water keeps expanding the bubble even after

Jan 1, 1963

Copper waste dump leaching is growing in importance because of the.large tonnages (up to 250,000 ton/day) of low grade waste rock available from open cut mining of copper deposits and proof that controlled leaching of copper from such dumps can be profitable.Overburden or waste rock, ranging in size from large boulders to fines, is dumped as cheaply as possible on sloping sites. Copper is leached from the dumps by applying up to 12,000 gal/min of leach solution (a combination of spent solution from cementation and make-up water) to the top of the dumps by various techniques.Efliuent from the dumps is sent to a cementation plant for copper recovery.Factors which may be controlled, either directly or indirectly, to give a controlled copper content in the dump efliuent (usually 1-2 g/l.) are the cycle of operations (i.e. the alternate wetting and drying periods), thevolume of solution applied to the dump, pH, Fe2+ and Fe3+ content or redox potential, oxygen content, bacteria and their necessary nutrients, and temperature.Dissolution of oxide copper minerals appears to be mainly a function of acid concentration. Copper sulphide minerals need oxidation for dissolution to occur and this is accomplished by a combination of oxygen,ferric ion, and bacteria. Oxidation of pyrite, oxidation of Fe2+ to Fe3 +, and hydrolysis of Fe3+ are of some importance in leaching practice. The presence of gangue carbonate minerals is detrimental.Physical factors connected with penetration of solution into large rocks are important and the treatment of an individual dump usually extends over a period of many years. Recovery of copper from solution is usually achieved by cementation with iron (usually in the form of crumpled cans) but the use of sponge iron is becoming more important. Iron consumption varies from 1 to 4 lbiron per pound of copper. Preconcentration of the copper in the efliuent solution by solvent extraction followed by electrolysis may become a useful method.Application of dump leaching techniques to metals other than copper depends on finding an economic method of recovering the metal from solution...

Jan 1, 1967

By G. van Aswegen

The geometry and morphology of a set of low-angle fractures around a stope in a deep Witwatersrand gold mine are explained in terms of extension fractures forming under variable conditions of stress. Primary extension fractures (E1) form some distance ahead of an advancing stope along the s1, s2 plane. With stope advance, a couple of these fractures end up in a stress regime conducive to transpressional shear and a secondary set of extension fractures(E2) is formed at a high angle to the primary fractures. i.e. at a low angle to the stope. As the E2 fractures are undermined, they migrate into a stress regime of transtensional shear and a third set of extension fractures (E3) may develop between E2 fractures. These have sigmoidal shapes, being parallel to the E2 fractures at the E2 discontinuity where s3 is negative, and curved through the un-fractured rock between E2 fractures where s3 is positive at the instant of fracturing. The fractures all display fractographic features characteristic of dynamic extension failure with striae indicative of the direction of rupture propagation and the local, instantaneous orientation of s1.

Jan 1, 2012

By F. W. Bowdish

A theoretical and experimental laboratory study has shown that the rate of breaking of oversized particles in a ball mill is proportional to 1) the concentration of such particles, and 2) the area of the balls, provided that the balls are larger than a certain size relative to the particles. If all undersized material were removed as formed, the rate of breaking would be almost independent of the quantity in the mill. Rate equations are given which are similar to those for zero, first, and second order reactions. Deviations of small balls from the equation for a second order phenomena are quantified by a factor called "nipping efficiency." Some data are correlated by a dimension-less equation, which is used to estimate nipping efficiencies from data not in the correlation. The investigation described here was undertaken after a literature survey revealed that little was known concerning the mechanism of breaking of particles within a ball mill and the effect of this mechanism upon grinding rates. One paper, by Roberts1 , offered a theory concerning the mechanism of breaking, and a rate equation for the breaking of particles larger than some size to particles smaller than that size. That paper provided the starting point for a theoretical and experimental investigation of grinding under carefully controlled conditions. THEORETICAL CONSIDERATIONS In his paper on the probability theory of ball mill grinding, Roberts theorized that "... a given expenditure of power leads either to a certain number of point to point blows per bp-hr or to a certain distance of line contact per hp-hr ..." He assumed that the balls touch each other during each blow or during moving contact. Then he said that a volume of pulp, dependent upon the size being considered, would be covered per minute within which all oversized particles would be crushed to particles smaller than that size. Naturally, the higher the concentration of oversized particles in the pulp, the higher the rate of which they would be broken. From this reasoning Roberts obtained the differential equation -dC/dt = k hp/ton C (1) where k is a constant for any size of particle, density of particle, and moisture content of pulp. C is the percentage of oversize in the material to be ground, t is the time, and hp/ton is the power input per ton of material in the mill. He then integrated the equation to log Co/Ct = k/2.3 hp/ton t , where Co and Ct are the percentage of oversize at time zero and t respectively. By always using the same quantity of material in a mill and assuming that it required constant power to run the mill, he was able to combine the horsepower per ton factor with the other constants to give an equation for a first order rate.

Jan 1, 1961

By Frank E. Woolley, Robert D. Pehlke

Jan 1, 1965

By Motohisa Kanda

The time and amplitude statistics necessary to adequately describe electromagnetic (FM) noise in mines are illustrated through computer software techniques. They are 1) Allan Variance Analyses (AVA), 2) Interpulse Spacing Distributions (ISD), 3) Pulse Duration Distributions (PDD), 4) Average Crossing Rates (ACR), and S) Amplitude Probability Distributions (APD). These statistics are illustrated using data taken from a rather large store of raw analog data recorded in operational mines. The curves generated for the illustrations characterize the noise environment in the mines from which the corresponding data were taken, and should aid in the design of reliable communication systems for such mines.

Jan 1, 1974

By Robert Stefanko

In the context of the following report, an hazardous location can be described as any industrial area in which flammable or explosive gases, vapors, and dusts can be encountered. When electrical apparatus is used in such hazardous atmospheres, the chance of a dust or gas ignition is ever present. Consequently, in an effort to reduce the ignition hazard, several protection systems have been devised. Such systems are termed electrical hazard reduction techniques. The most widely accepted and used of these, the explosion-proof enclosure, is the principal subject of this report. However, other techniques are briefly mentioned. Hazard reduction techniques used in coal mine atmospheres (which can contain methane, coal dust, and air mixtures) are classified as Group I. The explosion-proof enclosure commonly used in mines is defined by the USBM Schedule 2G as a device that can contain internal explosions of methane-air mixtures without undergoing damage or excessive distortion and without an ignition of a surrounding methane-air mixture or discharge of flame. (100) Internationally, the definition remains the same except the words "discharge of flame" are not present. (4,5,31,42,52,76,102) The latter description often refers to flame-proof enclosure construction, but the terms "flameproof: and "explosion-proof" commonly have the same connotation. These enclosures which may not be vapor tight, are distinguished by heavy-wall cast or welded construction and bolted or threaded close fitting flanges.

Jan 1, 1974

By R. W. Stahl

An emergency is defined as an unforeseen combination of circumstances that calls for immediate action. When applied to a coal mine, an emergency may call for prompt removal of the men to the surface through travelways other than the haulageway or intake airways, which are generally contaminated with irrespirable air as a result of an explosion or fire. Therefore, maintenance of adequate and travelable escapeways from all working areas of a mine is vitally important insurance against disaster. Several mine disasters could have been avoided if well-defined escape routes had been provided and made known to all mine employees. Such occurrences, unnecessary as they generally are, unfairly indict the industry when only a small segment thereof is involved. As a result of a rather recent disaster, which might not have happened if good escape routes had been provided, the Bureau of Mines decided to delve into the escape procedure to determine (1) what is being done in the industry and (2) what might be done at reasonable cost.

Jan 1, 1962