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By Mario L. Villa

During 1939 oil production experienced a new and important increase in Argentina in the productive areas of Comodoro Rivadavia (Territory of Chubut), Plaza Huincul (Territory of Neuquén), and those of the. Province of Mendoza. Production in the Standard Oil Company's field in the Province of Salta declined, but that of the Government oil fields in that province inereased 62.5 per cent.

Jan 1, 1940

By Howard M. Wells

The investment worth of a mineral deposit can only be realistically evaluated in relation to specified engineering design criteria which fully detail the proposed method of exploitation. The operational design of a mine falls essentially within the technical discipline of the mining engineer, under the constraint that the technical design should be aimed at optimizing the financial attractiveness of the project. In the case of a marginally viable proposition it becomes vitally necessary to identify the best set of design parameters which together will add up to an optimum investment proposal. This paper examines some fundamental logic of optimization for a "wasting asset" type of investment such as a mine, with special reference to the rate of annual production and the strategy of selective mining.

Jan 1, 1979

By Charles Will Wright

The present struggle for economic and industrial supremacy by the Communist world is against the United States, its main target, and the other Free World nations. The basis of industrial power is minerals, so the Communist nations are building up mineral production within their borders, often regardless of costs, and are acquiring quantities of mineral products from Free World countries for future use. They are contracting for additional supplies and advancing funds for the development of these quantities. A number of the less developed mineral producing countries of the Free World are being infiltrated by Communists and Communistic influence. This situation is well known, but as yet little has been done to oppose these activities or to awaken the public to their seriousness. The Communist countries are still far behind the Free World Nations in production of many essential minerals. But, shortages are being made up from Free World nations in exchange for petroleum, manganese ore, chromite and other products. Restrictions on shipments of strategic materials to Communist countries have not been maintained.

Jan 1, 1964

By P. G. Hallof

Only recently has the term Induced Polarization found its way into geophysical literature. Schlumberger first mentioned the possible use of the induced polarization effect in one of his early papers. Later, induced polarization was the subject of several university theses, such as Seigel's at the University of Toronto and Bliel's at the Michigan School of Technology. In addition, a group at the New Mexico School of Mining and Technobgy has done work on induced polarization. There is very little to be found in print on the subject of induced polarization. Several papers have been presented at meetings, the 1958 AIME and SEG* conventions, for instance, on laboratory measurements of the effect and theoretical considerations useful in the interpretation of field results. This paper is the first attempt to present actual field results which show the usefulness of induced polarization as a prospecting technique. There are several phenomena that can cause polarization when electrical current is passed through the ground. In a paper presented at the 1958 SEG* meetings Professor T. R. Madden of M. I. T. demonstrated that only two of these gave rise to appreciable effects. The first is a result of the membrane and diffusion effects in a sandstone that contains appre- ciable amounts of clay minerals. The unbonded charges associated with the clay mineral forma material that passes positive and negative ions with different mobilities. When current is passed through such a system for some period of time, polarization results. The second phenomenon, which gives rise to very much larger polarization effects, is the one used in the new prospecting technique. These effects are a result of the blocking action or polarization of metallic or electronic conductors in a medium of ionic solution conduction. This electrochemical polarization, called "the over-voltage effect" by electro-chemists, occurs whenever electrical current is passed through a volume of rock which contains metallic minerals such as base metal sulphides. This polarization at metallic interfaces in ionic solutions depends upon the chemical energies necessary to allow the ions to continue the flow of current by giving up or receiving an electron from the metallic surfaces. The energy stored in this reaction isanalogous to that stored when a condenser is charged. If a d. c. current flowing through such a system is interrupted, the polarization can be detected as a small, decaying current that flows after the applied current is discontinued. The decaying potential measured is a result of the current flow caused by charges returning to their equilibrium positions from the positions they assumed under the applied potential field. Because of the polarization, there is an excess of change at each metallic interface. There is an alternate method of measurement of the induced polarization effect. The electrical

Jan 1, 1961

By AIME AIME

On Nov. 11, 1909, M. Alexandre Pourcel, of Paris, France, upon the proposal of a large number of distinguished members, and the unanimous recommendation of the Council, was elected by the Board of Directors an Honorary Member of the Institute. M. Pourcel has devoted forty-three years to the metallurgy of iron and steel ; and the work which he did between thirty and forty years ago constitutes an important part of the founda¬tion of the practice of to-day. Among his striking contribu¬tions are : (1) his perfection, in 1869, of the manufacture of high-grade ferro-manganese in a carbon-lined open-hearth furnace, instead of the costly crucibles previously used; (2) his discovery, in 1874, of the method of making solid steel cast¬ings; (3) his manufacture, in 1875, of ferro-manganese and silico-spiegel in the blast-furnace; and (4) his anticipation, in 1875, of modern American blast-furnace practice, by the pro¬duction, in a very small furnace, of Bessemer pig containing 2.5 per cent. of silicon, from a burden yielding only 46 per cent. of iron, and with a consumption, per ton of pig, of only 1,8401b. of coke, containing 15 per cent. of ash. These brilliant pioneer achievements, together with his contributions to cur¬rent technical literature, won for him the Bessemer gold medal of the Iron and Steel Institute ; the great" medal of honor," which is the highest award of the French Society of Mineral Industry, and other gold medals, as well as the distinction of honorary membership of the Comité des Forges de France, which was conferred upon him in 1891. In recent years, M. Pourcel has been instrumental, as consulting engineer of the Société de Commentry-Fourchambault, at Decazeville, France, in an extraordinary development of the manufacture of special steels. The Invar plant, of this company, is said to make a greater variety of such steels (includ-

Dec 1, 1909

By J. F. Breedis

The stabilization of austenite in Fe-Ni alloys against martensitic transformation after reversion has been attributed' to the lattice imperfections remaining from previous transformation. More recently, however, such stabilization has been associatedzy3 with compositional changes which occur in martensite during slow heating. Dislocation arrangements in deformed austenitic stainless steels strongly influence transformation to martensite on quenching.4 Therefore, it is of interest to observe the transformation behavior of stainless steel after reversion, especially since previous studies have been confined to Fe-Ni alloys. The transformation-product morphology also differs in the two iron-alloy systems;6 plate martensite forms in the latter while stainless steel transforms to lath-type martensite. Samples of Fe-16 wt pct Cr-12 wt pct Ni (maximum C + N = 0.005 wt pct, 0 = 0.02 wt pct), prepared by vacuum melting and casting from high-purity components, were annealed at 900°C for 24 hr, after cold rolling to produce a 40-p grain diameter. The M, temperature of this alloy is -80°C and samples are fully austenitic after annealing. The amount of martensite present after quenching, annealing, and requenching was determined magnetically, to within 0.01 wt pct, using a vibrating specimen magnetometer. Nearly 14 pct of martensite forms during the initial quench in 1 min at -196°C. Two-min and 2-hr anneals were done in air and in evacuated quartz capsules, respectively. All specimens were electro-polished before making the magnetic measurements.

Jan 1, 1967

By THOMAS LEONBRD WATSON

I. INTRODUCTION. THE results embodied in this paper are based on a careful field- and laboratory-study of the lead- and zinc-deposits of the Virginia-Tennessee district, begun in the latter part of the summer of 1904 and completed in the spring of 1905, preparatory to the publishing of a State report .on them. A separate description of the individual deposits in Virginia is purposely omitted, since I have already described them in considerable detail in a State report. The Tennessee deposits are described here in some detail for the reason that no detailed record of them has yet been published. Practically, this paper summarizes the results obtained from a study of the geology of the ore-deposits of the district as, a whole. (I had the pleasure of visiting the deposits of Virginia and Tennessee with Dr. H. Foster Bain of the U. S. Geological Survey, in April, 1905. Figs. 21 and 22 are from photographs taken by Dr., Bail.) II. HISTORICAL. . The first authentic records of lead-mining .in Virginia date hack more than 150 years; and the old lead-mines at Austinville, on New river in Wythe county, V a., were the first to be worked. Colonel Chiswell, a native of Wales, and one of the earlier adventurers in southwestern Virginia, was one of the first operators of the Austinville mines. Chiswell's operations at Austinville commenced in the year 1750, and closed shortly after the beginning of the Revolutionary War, in the' year 1776, covering a period of about 25 years. From that time to the present, mining has been carried on almost continuously in the Virginia area. For many years after the Virginia mines were operated, mining was confined exclusively to the lead-ores. The zinc-ores

Mar 1, 1906

By W. L. Zeigler

THE year 1930 in the Ceur d? Alene district was one of curtailment in production. Many of the small properties were closed entirely and only three large. producers, the Bunker Hill & Sullivan, Hecla, and the Morning mines were left producing at capacity. No innovations in milling were evident, but progress was made in reducing costs as is always necessary in times of low metal prices. One new concentrator was constructed, a 500-ton daily capacity selective flotation plant for, the Jack Waite Mining Co. This mill uses coarse crushing, followed by hand sorting, for both a high-grade ship- ping ore and waste. The remainder of the ore leaving the sorting belt is crushed in a new type Traylor reduction crusher to %-in. size and stored in large capacity mill ore-bins. The grinding is done with ball mills, in closed circuit with a Dorr classifier to 75 per cent - 200 mesh. Minerals Separation 24-in. flotation machines are used both for a lead and a zinc concentrate, with double cleaning in each case. The concentrates are dewatered in Dorr thickeners and filtered on Oliver late-type filters.

Jan 1, 1931

By T. O. Allen, J. H. Atterbury

Laboratory and field tests during the past five years indicated considerable variation in the penetrating power of commercially available gun perforators. Many of the guns which achieved inadequate penetration in these tests have since been improved. However, recent productivity tests indicated the possibility of inadequate penetration or, at least, ineffective penetration in some wells. Laboratory experiments under simulated well conditions have demonstrated considerable plugging of the perforations, apparently as a result of factors associated with the shooting process and/or the drilling mud in the well at the time of perforating. The restrictions to flow per unit of hole depth caused by this plugging appears to be greater for jet perforators than for bullet guns of comparable diameter; however, because of the greater depth of penetration obtained with the jet guns, the total flow rates appear to he approximately equal. Limited testing with an experimental shaped charge suggests that less shot hole restriction and greater flow rates may result from larger-diameter perforations or other factors related to charge design. INTRODUCTION Gun perforating has been accepted for a number of years as a routine well completion method which is often preferred since it permits more selective operation of producing zones. Nevertheless, questions have continued to arise as to the effectiveness of the communication paths established between the productive formation and the interior of the casing. The basis for these questions has generally been failure to obtain anticipated fluid production rates through gun perforated completions in specific wells. These low productivities, together with the frequent recovery of bullets from well bores, were considered strong evidence of inadequate penetration. Laboratory investigations of the penetration performance of many of the bullet guns available as late as 1948 gave support to these indications. Subsequent electrical analog studiesl,2,3 indicated that the depth of penetration required to provide productivities equivalent to open hole was beyond the capacity of most bullet perforators evaluated in the early laboratory penetration tests. These results, together with the advent of the shaped charge in the field of oil well perforating, stimulated the interest of both oil operators and service companies in gun development. Improvements in gun design resulted in jet and bullet guns which appeared to be capable of providing sufficient penetration for most perforating jobs. However, some wells failed to yield satisfactory fluid production even after being perforated with the more powerful guns, again raising the question as to the effectiveness of the perforating operation. This fact, together with preliminary shooting into targets prepared with formation cores, indicated that factors associated with the perforating process and/or the fluids in the well bore at the time of shooting may reduce effective formation penetration and thereby decrease well productivity. These laboratory and field data prompted another phase in the investigation of the effectiveness of gun perforating: a program to determine the extent and seriousness of perforation plugging under simulated well conditions.

Jan 1, 1955

By P. Somasundaran, D. W. Fuerstenau

This article presents the results of an analysis of grinding of 1:1 mixtures of 4x8-mesh quartz and limestone in laboratory ball and rod mills. From these experiments, the amount of energy consumed in grinding each component of the mixture was determined. In the ball mill, limestone consumes slightly more energy than quartz in the initial stages of grinding, but as the grinding proceeds quartz begins to consume a slightly greater fraction of the energy. The postulate that the fraction of energy consumed by any material in a ball mill is proportional to its volume fraction has been shown to be approximately true. On the other hand, in a rod mill energy consumption by quartz and limestone is equal only in the initial stages of grinding, with energy consumption by quartz greatly exceeding that by limestone as rod milling proceeds. Preferential energy consumption in tumbling mills has been discussed in a number of papers. For example, from an analysis of the kinetics of comminu- tion in ball mills, Arbiter and Bhrany' obtained rate equations based on the postulate that only coarse particles are ground, indicating that fine particles are protected from the action of the balls by coarser particles. In rod mills this protective action is much more pronounced than in ball mills. Recent studies on the rod milling of limestone-quartz mixtures have shown that this protective action causes the mineral with the lowest grindability (quartz in this instance) to consume the greater fraction of energy. 2 However, in the ball milling of mixtures it has been postulated that the consumption of energy by one of the constituents is determined by its volume fraction within the mill. 3 Possibly this hypothesis may be a simplification of the ball milling of mixtures since the protective action suggested by Arbiter and Bhrany may result in some preferential energy consumption by one of the constituents of a mixture. The objective of this study has been to determine preferential energy consumption in laboratory ball and rod mills by analyzing size distributions of each material in the products obtained from grinding 1:l mixtures of quartz and limestone. MATERIALS AND METHOD The procedure for carrying out the tests on wet grinding quartz-limestone mixtures has already been described.'r3 In the present investigation, 1:l mix-

Jan 1, 1963

By D. L., Hayes

THE concentration of zinc ore in Wisconsin is a comparatively simple process, although it presents problems that must be overcome in an efficient manner in such a way that installation and operating costs are low. As the ore deposits are small, the first cost of the concentrating plant must be low; while the low margin of profit makes it necessary to have the minimum operating costs. The original mills were copied from those of the Joplin district, as most of them were built and operated by Joplin millmen. These served the purpose well; they made a clean concentrate, which was the chief requirement at that time, as most 'of the mines were' considerably 'richer than the average at the present time, and wages and supplies were also considerably lower. ' The apparatus used at present has changed very little in principle. . The grizzly opening has gradually been increased to 12 in. and sometimes no grizzly 'is used. The crusher, gradually grew in size, the largest crusher has -an opening of about 24 by 13 in. and a 7/8-in. throw on the. eccentric shaft.

Jan 1, 1921

By Jack Haptonstall

INTRODUCTION The mines of western central Mexico historically contributed a profusion of gold and silver for the treasury of Spain and later provided sources for financing the Mexican War for Independence and the Mexican Revolution. The western coastal and barranca (cliff) tribes were hunters and extremely hostile, and the Spaniards were not able to penetrate many of the rich districts of their rugged homeland until the mid-1700's. This was more than 200 years after Cortez began the Inquisition by defeating the Aztecs and their allies in a decisive battle in the great city of Tenochtitlan (present day Mexico City). The Spaniards had a voracious appetite for silver and gold, and it was inevitable that they would finally subdue the natives and commence mining activities. Described in this paper are some of the precious metal mining activities in the southern half of the State of Sinaloa and the western half of the State of Durango (Figure l), and specifically those mining activities in the area controlled by the company with which the author was associated for 14 years, Minas de San Luis, S. A. de C. V., the parent company of which is now Industrias Luis Min, S. A. GENERAL DESCRIPTION Geography, Logistics and Climate The most spectacular of the physiographic provinces, the western Sierra Madre Occidental is the cliff or "barranca" province, the

Jan 1, 1983

By J. H. Schulman, M. H. Buckenham

R. W. Christy (Manager of Sales, Sanitary Engineering Equipment, Link-Belt Co.) and C.D. Rubert (Barrett, Haentjens & Co.) — Messrs. King and Schepman have presented an excellent paper which outlines the general practice in the design of thickener mechanisms. Lifting devices, controls, special applications and underflow pumping arrangements have been reviewed in detail. Pumping arrangements were illustrated which eliminate the need for an expensive tunnel beneath the thickener floor. Most of those illustrated have the common feature of a relatively long underflow suction line extending from the hopper floor to the pump located on the bridge at the periphery of the tank. The authors limit these arrangements to comparatively dilute or thin slurrys. It is implied that dense and coarse concentrates, which are difficult to pump, cannot be handled unless a tunnel is constructed. Fig. 1 shows an underflow pump arrangement which negates the need for a tunnel but which permits the operator to convey a heavy dense slurry. The pump is mounted directly on the fixed hoist platform and the impeller is located at the base of the steel center column. Priming water is not needed. The column

Jan 1, 1963

By Thomas Darlington

THE obligation of an employer to the State requires certain things of him as matters of good citizenship: for instance, that his workmen shall have a living wage, that child labor shall not be employed, that injuries from accidents shall not- make workmen a charge upon the State, and that the laborer's children shall have opportunity for education and to become good and useful citizens. Affairs of this kind are not taken up as philanthropy, for the officials of a corporation or a large manufacturing concern may not feel at liberty to spend the funds of their company as prompted simply by motives of kindliness; but they may spend company money on such matters because it is good business. For years, the poisonous effects of lead, phosphorus and dust have been emphasized in books on industrial hygiene and their elimination has been urged; but the more important and everyday physiology of the workman himself has been neglected. Part of my object in writing this paper is to show how our knowledge of physiology may be applied to working conditions in everyday life. In the interest of industrial laborers, accident compensation laws have been enacted in 33 States. This has been carried forward rapidly, because it has been shown that it pays both employer and employee. A further step is the recognition of sickness and disablement independent of accidents, not only because of their immediate cost to the worker and to the employer, but because continued efficiency in work and business depends largely upon health. Some measure of the importance of health in industry can be gained by the knowledge that records kept by some companies which now make this the subject of careful inquiry show that the time lost by employees, through illness; is several times as much as that lost as the result of industrial accidents. It is true that accidents frequently result in permanent disability or death, but it is equally true that illness is also a cause of permanent disablement or death. Thus the chief difference is that the loss to the employee through accidents occurring in the course of his employment is now generally recognized as a cost

Jan 2, 1918

By R. S. Shoemaker, R. M. Darrah

Expanded markets for copper in the past few years and a consequent search for new ore bodies have revitalized the widely known but seldom applied method of producing copper called heap leaching. Heap leaching is defined here as the process applied to oxide ores which have been mined solely for the purpose of leaching. In this case, all costs of mining the ore become a part (and a substantial one, as will be shown) of the cost of the copper produced, whereas in dump leaching the mining cost has already been accounted for as a stripping cost for the sulfide ore. Of course, with newly opened ore bodies, stripping costs may be divided through accounting procedures, between the copper produced by the mill and that obtained by leaching, but in general this type of operation must be economic on the basis of the sulfide ore alone. Heap Leaching Requires Low Capitalization Heap leaching, as a beneficiation method, is unique in that it is the only process used for the recovery of a metal in which the time involved from mining the ore to metal production is measured in months instead of hours or at the most, days. Then too, after the ore body has been depleted and mining has ceased, metal production will continue for some substantial period of time. Heap leaching is also unique because unlike any other method of beneficiation, metal recovery cannot be accurately forecast ahead of time and recovery will never approach that of a conventionally milled sulfide ore or even that of a vat leached oxide ore. Counter-balancing this drawback, however, is the relatively low capital expenditure necessary to put a heap leaching operation into production and the consequence that smaller ore bodies which would not support the higher capital cost involved in a vat leaching plant can be made into producers. Stated more simply, in heap leaching the operator accepts low recovery in exchange for low capital costs and low break even point. Whether the operator chooses vat leaching with its higher recovery and higher capital costs, is a mater of economics which depends in part on the nature of the ore to decide. For instance, an ore that will vat leach in 7 to 10 days using 7 pounds of sulfuric acid per pound of copper produced might use double or triple that amount of acid during the months that are required for heap leaching.

Jan 12, 1968

By Dennis V. D’Andrea, Sidney M. Runke

This paper describes the Bureau of Mines-El Paso Mining and Milling Company cooperative research program at the Emerald Isle mine3 near Kingman, Ariz. This research program was directed toward developing in situ leaching methods for 200,000 tons of ore exposed in the pit bottom and also 1,500,000 tons of ore under 200 feet of overburden adjacent to the pit. A test area in the pit bottom containing 15,000 tons of ore was blasted and leached. The results of this leach test were encouraging, and the entire pit bottom was leached in-place for about 7 months. Two test blasts under 200 feet of overburden and extending to 290 feet were detonated in an area near the open pit. The results of these blasts were evaluated by core drilling and permeability measurements. An in situ leaching system was designed, but not implemented, to recover copper from the 1,500,000-ton area near the pit. The company decided to terminate operations at the Emerald Isle mine in November 1975.

Jan 1, 1976

By Moshe Sheinkin, Burke O. Trafton

This paper describes the use of a computer in analyzing the expected return on a mining venture. The computer program is designed to incorporate all aspects of a mining project, including the mine, mill, smelter, and refinery. Data input may consist of the operating variables in each phase such as the mining rate, grades, reserves at the mine, and the technical operating characteristics of the mine, mill, smelter, and refinery. Detailed tax computations are shown for a domestic operating company, for a foreign company and for a foreign subsidiary. In addition, the use of the various options that are available such as expense write-offs or deferments to create tax credits during preproduction years are considered, and its effect on the DCF. The program is also constructed to accommodate changes in metal prices, and escalation of capital requirements and operating costs. Output consists of profit and loss statements for entire projects using different methods of depreciation, cash flows, discounted cash flows, net present value and returns on investment. Returns on investment are computed for equity investment, total investment, and total investment less tax credits. Allowances are made for bank and guaranteed loans. Additional financial statements can be made for the following: a) A mine-mill segment with a concentrate selling schedule b) A mine-mill-smelter complex with a smelter product selling schedule c) Profitability of the smelter separately d) Profitability of the refinery separately

Jan 1, 1969

By J. T. Crawford

Although nearly 10 pct of the total tonnage of coal produced annually within the United States is handled by bulk freighters on the Great Lakes, very little of the detail connected with it has been published other than occasional newspaper stories and publication of tonnage statistics. Of the total tonnage floated on the Lakes each year some 10,000,000 is stored and distributed from the port of Duluth-Superior, at the western end of Lake Superior commonly known as the Head of the Lakes. This port has the largest single area concentration of coal docks in the world. Since this area contains the largest ore docks, the largest movable material handling bridge, the largest and highest grain elevator and the largest coal bri-quetting plant in the world, it is entirely fitting and proper that here also should be located the largest coal dock and what we believe to be the world's largest clam shell. Of the sixteen coal docks operated by ten companies, five are owned and operated by the North Western-Hanna Fuel Co. which has two docks on the Superior, Wis., waterfront and three docks in Duluth, Minn. It is with these five docks that we are primarily concerned, General History In the summer of 1871 a small sailing vessel entered the harbor of Duluth-Superior with the first commercial coal cargo. All the coal brought up that first year did not amount to more than 3000 tons. During the year 1877 the first dock equipped for handling coal was built in Duluth. Coal receipts increased to 52,785 tons in 1879 the first year for which an official record was kept. Since then the volume of water-borne coal to the Head of the Lakes steadily increased to a maximum of 12,688,321 tons in the year 1923. This tonnage was nearly equalled in the year 1927 and the next highest tonnage recent year was in 1946 when 10,105,703 tons were unloaded. The average annual bring-up over a ten year period 1938 to 1947 was 8,605,231 tons. Approximately 30 pct of the coal unloaded at the Head of the Lakes is handled over the docks of the North Western-Hanna Fuel Co. Competition of other fuels coupled with expansion of coal fields in the mid-west have held coal receipts for Duluth-Superior at a relatively constant figure during the last eight years although the total tonnage of coal floated on the Great Lakes has more than doubled in the past 25 years. From the shovel and wheelbarrow method of unloading early cargoes to the horsepowered windlass derrick with a wooden tub was but a short step. The first movable coal handling, steam operated,

Jan 1, 1949

By D. Hnrrington

THE Dust Symposium was attended by approximately 100 persons, nearly all of whom remained from the starting hour (2 p. m.) until the use of the auditorium was demanded for another meeting at 5:30 p. in. In calling the meeting to order, D. Harrington made a few remarks as to the importance of the health dust problem in mining as well as in general industry and expressed gratification that the subject is now out in the open and that mining people are desirous of ascertaining the facts. B. F. Tillson acted as chairman of the meeting. The milling executive who desires to know what to do to prevent his workers from being unduly exposed to the dust hazard can get much out of the paper by D. E. Cummings, who has been doing much work in mines trying to keep -the dust in the air within safe limits. His recommendations indicate that the main protection of the worker in mines is by adequate ventilation, supplemented by the extensive use of water in drilling, as well as in water curtaining to condition air both in regard to dust content and to temperatures. Blasting was shown to be one of the chief causes for dust and it was recommended that whenever feasible all blasting should be delayed to the end of the working shift.

Jan 1, 1935

By Richard A. Mullins, James J. Merle

Systematic sampling and analysis in coal-washing plants results in product control and economical operation. A well-organized laboratory system reduces operating costs and increases sales if the operating and sales companies make full use of information it supplies. The operating cost of a control laboratory is less than 1 pct per ton of coal produced.

Jan 5, 1950