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By W. M. Aubrey

Cobbing, as used in this; paper, refers to coarse dry magnetics separation. It is applicable when, by its practice, plant cost can be reduced or the value of its products increased by the removal of a barren or lean reject or a high grade final product. This paper attempts to describe cobbing as it is now being practiced, and also the problems that are of concern to the operator and design engineer. In preparation, 16 plants were contacted, all of which were very cooperative with their time and data.

Jan 1, 1958

By T. A. Read, H. M. Otte

THEORETICAL analysis by Wechsler, Lieberman and Read of the crystallography of martensite formation has shown that the requirement for the existence of a macroscopically undistorted plane between austenite and martensite permits a calculation of the indices of the habit plane of the marten-

Jan 1, 1958

By Brown H. R, Wright E. A

The authors identify the workable coal seams, their distribution in relation to quality and economic occurrence and relate their analytical characteristics to industrial use. The development of established collieries is also discussed with regard to increased production demand.The authors also indicate the potential of the coal resources of the Southern District and postulate their ultimate development.INTRODUCTIONThe Southern Coalfield yields 30 per cent of the total production of bituminous coal in New South Wales. The economic potential of the coalfield was examined last by Harper (1915). Since that time additional knowledge has been gained by prospectors, mining companies and public authorities. Expansion in the steel industry and the building of power stations on the coalfields together with improvements in fuel technology, mining methops and road transport have resulted in production of coal from seams mice thoughtto have no economic value.DESCRIPTION OF THE COALFIELDFor the purpose of this paper the term Southern Coalfield includes also the South-Western Coalfield which together comprise the following Coal Districts:IllawarraDouglas ParkWollondilly-NattaiMoss Vale-Berrima (Hanlon, 1953).Geographically the coalfield is contained by the Illawarra Range in the east, the Shoalhaven River to the south, the Wollondilly River to the west, and in the north by a line...

Jan 1, 1958

By J. C. Ingram

IT SEEMS particularly appropriate that, in celebrating its Diamond Anniversary, the Canadian Institute of Mining and Metalturgy chose our Province of British Columbia as its locale in this, our own Centennial year. I am sure your organization is justifiably proud of its achievements and growth over the period of its sixty years, and we, for our part, are justifiably proud of our growth over our first one hundred years. With your kind indulgence I pro-pose to talk to you today about our industrial growth, or, to put it an-other way, to highlight, historically, our progress in industrial development over the past one hundred years, and to take the liberty of speculating on what we may reasonably look forward to over the next few years. I am sure, Mr. Chairman, that some may have questioned the appropriateness of a talk on the industrial development of British Columbia to the Canadian Institute of Mining and Metallurgy. However, strangely enough, we in British Columbia owe our origin, constitution-ally and industrially, to the mining industry.

Jan 1, 1958

By W. Hunka

PACIFIC PETROLEUMS, Ltd. first discovered commercial quantities of gas in the Peace River area in 1952. Development of gas wells in this area is quite ex-pensive due to low penetration rates. To improve the economics, the potential of the wells in many cases had to be increased. At that time, well stimulation was still in its infancy in Canada and in this area, in particular, no treatment of any consequence had been attempted. Therefore, trial-and-error was the only means available to determine the stimulating technique that would give optimum results. Various fluid treatments were available and these were used wherever the application was warrant-ed. This paper covers acid fracture and explosive treatments as carried out on various gas-bearing horizons.

Jan 1, 1958

By Wm. C. Phelps, R. E. Grace

b R.c c)nduciivity of slags and glasses is of particular interest when viewed as an activated ionic flow process. The ionic conductivity, for example, has been found to obey the Easch-

Jan 1, 1958

By E. H. Bronson

PROPERTY of Malartic Gold Fields Ltd. is situa-ated in the great clay belt in the northern part of the Province of Quebec. This belt represents the floor of the glacial lake Barlow-Ojibway. The clay blanket has a gently rolling, almost flat surface, with here and there projecting knobs and ridges that outline the large irregularities of the surface on which the clay was deposited. At irregular intervals glacial eskers dominate the landscape. The ore-bearing country rock is covered by strata of clay, sand, and silt to a depth varying to 40 ft. There are serious structural problems when it is necessary to place loads of unequal intensities on this surface to support buildings and machinery for a modern mining plant. Earlier mining companies and their engineers paid little attention to the science of soil mechanics, partly because they believed it unnecessary and partly because they knew little of the subject. The results are evident in some of the tottering structures in older camps. Careful analysis of soil problems is well worth-while, since cost of foundations may vary from 20 to 50 pct of the final cost of a structure. Low operating and maintenance costs can be achieved only in this way. If it is definitely established that a plant will be in operation for only a few months, this limited time factor will probably influence the design of the foundation, and rightly so. If sensitive and complickted equipment is to be mounted on these foundations and the plant is to operate for several years, there should be a thorough study of foundations and a very careful design. A familiar problem is presented by the difficulty of operating a permanent plant originally designed for a few months' work. The engineer must beware of these hazards and disassociate himself from them if he cannot prevail on the promoter to spend the proper amount for a thorough foundation study. Laws of certain provinces and states hold the engineer equally responsible with the contractor for any 'damage that may be caused to building through inadequate study-ignordnce of the facts is no excuse in the eyes of the law. Types of Soil: The engineer should be familiar with such terms as silt, clay, peat, and varved clay, as well as perpafrost, especially if he is to work in the far northern reaches of the country. He should also be familiar with soil attributes such as porosity, texture, consistency, permeability, compressibility, consolidation, and shearing resistance. The design of any foundation requires an accurate knowledge of the physical properties and location of the soils involved. Older textbooks on the subject outline various empirical methods to determine the carrying power of soil. Tables are given in reference books. The modern ehgineer should be wary of these modes of thinking. He should analyze his problem carefully, calculate to what depth of soil the loads may be transmitted, and then check the bearing value of all soils to that or greater depths. If the strata are water-carrying, he must determine the possibility of this water being accidentally re-

Jan 1, 1958

By Woodcock J. T

When an aqueous suspension of pyrite and a manganese ore reacts with oxygen, manganese is dissolved by the ferrous sulphate and sulphuric acid produced in situ by oxidation of pyrite. In the absence of added acid, the optimum conditions are: a molecularratio of Mn02/FeS2 of about 1·0, a temperature of about 1400 C., and an oxygen pressure between 25 and 90 lb./sq. in. Under these conditions, complete extraction of manganese is obtained in six hours leaching. An addition of sulphuric acid enables an Mn02/FeS2 ratio of 2·0 to be used successfully.Manganous sulphate decreases in solubility with increase in temperature above 1000 C., but even when the solubility limit is reached during leaching, reaction to form MnS04 still proceeds, and on cooling the MnS04 redissolves.INTRODUCTIONMany manganese deposits contain secondary manganese oxide minerals which are difficult to concentrate. Considerable attention has therefore been given to their hydrometallurgical treatment. In most manganese oxide minerals, the manganese is quadrivalent and must be reduced to the divalent state for dissolution. Reduction and dissolution can be accomplished in a number of ways, one method being to use aqueous ferrous sulphate solutions.A possible source of ferrous sulphate is pyrite as it is known that ferrous ion is an intermediate product in the aqueous oxidation of pyrite. It was therefore thought possible, that by heating an aqueous suspension of manganese oxide and pyrite with oxygen, the ferrous sulphate and sulphuric acid formed from pyrite would provide the necessary leaching reagents for manganese in situ. There are certain advantages in producing ferrous ion in situ...

Jan 1, 1958

By Bain J. H

Since zinc was first deposited at Risdon in February, 1917, provision of the most economical cathode assembly has been a subject of extensive research, the major problems being corrosion and efficient use of power.From the corrosion viewpoint, a perfect cathode is one in which the life of the headbar and the deposition sheet are the same. However, corrosion usually concentrates in a narrow zone across the face- of the sheet, resulting in breakages which, before the advent of argon arc welding, meant a loss of a 'complete assembly.Attempts to extend sheet life included use of thicker sheets, multitudinous protective coatings applied with varying degrees of success, re-rolling, and for a time, aluminium consumption was reduced when broken sheets found re-use as protecting strips. This latter economy became impracticable when electrode spacing was reduced for greater efficiency in power utilization.As an integral part of the electrode, the headbar was modified accordingly. Copper headbars, although more corrosion resistant, were replaced by aluminium due to a possibility of dissolved, copper promoting deterioration.Thicker electrodes and regulated spacing reduced internal shorting, whilst provision of knife-edge type supports on both contact and insulator ends of headbars aided in electrode centralising and continuous electrical conduction.After much experimeIitation, an assembly has been evolved which, with the aid of argon arc welding and tbe use of minimum additional aluminium, permits comparable headbar and sheet lives, combined with good electrical conduction throughout the life of the cathode.INTRODUCTION Over 300 tons of zinc are produced daily at Risdon from a purified zinc sulphate solution by electrolysis, the zinc being deposited upon all-aluminium (except for copper contact) cathodes. It is stripped in 72-hour cycles from the cathodes, melted and cast into the customary rectangular slabs.

Jan 1, 1958

By D. A. Ellis

This paper review s several new applications of solvent extraction developed in conjunction with a research project carried out under the AEC Raw Materials Division by the Dow Western Division laboratories during the last two years. A process for recovery of uranium from ores by contacting the solid directly with organic solvent without a prior aqueous leach and a process for uranium recovery by contacting thick, unfiltered leach slurry with the solvent were studied in an attempt to simplify ad reduce the cost of ore treatment procedures. Processes to produce pure UF4 products at the concentrate mills thus eliminating the production and subsequent dissolution of the concentrate were investigated. Since many of the leach liquors contained vanadium as well as uranium, solvent extraction processes for by-product vanadium were also studied.

Jan 1, 1958

By Richard F. Hinds, F. O. Reudelhuber

Application of the conventional depletion drive calculation methods to volatile oil reservoirs results in erroneous estimates of ultimate recovery. In view of the increasing number and importance of volatile oil reservoirs, a special technique has been developed which will result in more realistic predictions using laboratory data obtained from reservoir fluid studies of a specific type. The experimental data are designed to permit continuous material accounting and, therefrom, provide the hy-clrocarbon composition of both the flowing oil and gas phases. The resultant well-stream composition data are then used directly in surface recovery calculations utilizing equilibrium ratios. A step by step procedure, specifically designed for routine use by the practicing reservoir engineer, is presented in an appendix. An actual study performed on a deep Mid-Continent reservoir is used ay an il-lustrathe example. INTRODUCTION It has been a practice for many years to utilize the conventional ma- terial balance methods in conjunction with relative permeability concepts for the prediction of recovery from solution gas drive reservoirs.' Those who have performed such calculations recognize that compromises of several types are necessary in order to reduce the calculations to a reasonable degree of complexity. The most serious assumption involved results from the necessity of treating the produced oil and gas as separate fluids, independent of each other in their behavior. It is further assumed that the gas which is evolved in the reservoir as a result of pressure decline will not yield liquid upon the reduction of pressure and temperature resulting from production through surface equipment. Although these shortcomings have been recognized,' it has been difficult to attempt refinement of calculation procedures since the laboratory data available normally were not of the proper type or extent to permit such calculations. Three general procedures have been available for depletion drive calculations when laboratory fluid data are of the conventional type. Differential Procedure The most simple, and most widely used, method requires use of the formation volume factor and gas sol- ubility data obtained from a differential liberation performed at reservoir temperature. This procedure ignores the differences existing between the fluid behavior in the reservoir and its behavior as it is produced through surface separation equipment. The errors introduced are not serious when dealing with very low volatility fluids and this method may be utilized if the laboratory data indicate only slight differences between the differential data and the flash data obtained from separator tests. Modified Differential Procedure This method was developed when it became apparent that medium volatility fluids evidenced a wide difference between the flash and differential data. The differential data are adjusted by changing from a residual oil basis to a stock tank oil basis. All that is required is multiplication of the differential data by the ratio of residual oil to stock tank oil relative volumes existing for the original reservoir fluid at the determined saturation pressure. This procedure generally results in increased calculated ul-timate recovery; however, such results should be viewed critically. Upon examination it may become apparent that the results are influenced by errors in reservoir liquid

Jan 1, 1958

By Charles Prasky

ABOUT five years ago the Bureau of Mines began a study, at Minneapolis, of the various methods for beneficiating the low-grade manganese deposits of the Cuyuna range. Several samples of green carbonate slate from the Cuyuna range, containing about 7 pct Mn and about 28 pct Fe, were obtained for this study. The component minerals in the carbonate slate formation were so intimately associated that mineral dressing methods were not suitable for concentrating manganese to a ferrograde product. Although upgrading of manganese and iron minerals has been effected by flotation methods, it appears that manganese cannot be separated from iron except by chemical means. Because the flotation studies at Minneapolis were carried out simultaneously with the hydrometallurgical studies, only crude slate was available for process testing. An important economic consideration in selecting any one of the several chemical methods proposed for recovering ferrograde manganese is the availability of the chemical reagent. Fortunately, large tonnages of sulfur are available on the Cuyuna range in low-grade pyrite and pyrrhotite deposits that are readily concentrated by flotation to a suitable feed for a sulfide roasting furnace as indicated by a Bureau of Mines investigation in 195 0-1951.1 The roasted residue from the sulfide concentrates is a potential source of marketable iron oxide. Therefore, if these sulfide deposits were employed in recovering manganese, utilization of two heretofore unused mineral deposits would be accomplished. Laboratory investigations of several proposed leaching processes were made as a preliminary step in the investigation of hydrometallurgical methods for the treatment of Cuyuna carbonate slate using sulfur as a chemical reagent. From results obtained in the laboratory tests, these leaching processes did not appear entirely suitable for treating Cuyuna carbonate slate. The method developed at the North Central Experiment Station and selected for a more intensive pilot-plant investigation has been termed the differential high-temperature sulfatizing process. Essentially, this sulfatizing process consists of the following steps, described in the order in which the small-scale pilot-plant investigations were made. The first and perhaps most significant step in the process consists of a sulfate roast. Carbonate slate is roasted in an atmosphere of sulfur dioxide gas and air. The overall chemical reaction for converting manganese carbonate to a sulfate at a high temperature in a sulfur dioxide atmosphere follows MnCO8 + SO2 + 1/2 0, = MnSO4 + CO2 (H077°O = —64,180 cal per g mol) .' The need for concentrated sulfuric acid is avoided. Fine grinding is not essential. Removal of carbon dioxide from the slate during roasting produces a more porous structure and permits easier permeation by the sulfatizing gas mixture. The temperature limits for this conversion of manganese have been established as 600" and 850°C. Iron sulfate is unstable and is not formed at these temperatures; phosphorus is not converted to a water-soluble form; and polythionates are not formed. The second step in the process consists simply of a water leach of the sulfatized product. Manganese sulfate in the sulfatized product is dissolved in water. Iron, phosphorus, and calcium remain in the leach residue as water-insoluble products. The third and final step consists of the recovery of ferrograde manganese oxide from manganese sulfate leach solution. Water is evaporated from the leach solution, and impure monohydrate crystals of manganese sulfate are recovered. The moist crystals are formed into pellets or extrusions and thermally decomposed to produce a ferrograde manganese

Jan 1, 1958

By A. C. Johnson

This report describes exploration, development, and exploitation methods, and summarizes costs at the Stormy Day mine, which was discovered in 1941. Several shipments of tungsten ore were made in 1944 to the Metals Reserve Company, Salt Lake City, Utah. The purchase of tungsten by the Federal Government, which began in 1951, stimulated interest in tungsten, and a successful program of exploration with participation of the Defense Minerals Exploration Administration (DMEA) indicated enough ore to warrant development of the property. Development work comprised drifting, crosscutting, and raising. Shrinkage stoping was used for mining the ore. Operations were suspended in October 1956, when the Federal Government terminated its purchase program. Total production of the mine was approximately 20,000 tons of tungsten ore. INTRODUCTION This information circular is one of a series, prepared in cooperation with various mining companies and published by the Bureau of Mines, relating to methods and costs of equipping and developing mining properties in the United States.

Jan 1, 1958

By S. A. Braley

DRAINAGE water from coal mines is probably the most serious water pollution problem today, varying in importance according to location of the mines and geological structure. Drainage may be either acid or alkaline in character. Acid discharge, the most severely detrimental to a stream, is caused by natural oxidation of the sulfuritic material (FeS2) in the strata associated with the coal seam. Since the acid is the result of a natural reaction the acid water differs because it does not cease with abandonment of the mining operations. There is no known economical method of neutralizing acid mine water or any practical method to prevent oxidation of exposed pyrite. Since production of acid from a mine does not stop when mining stops, the total quantity produced depends entirely upon the excavated areas. The increasing volume of acid water in manv mines has greatly increased operating costs. Pumping is expensive and acid mine waters are destructive of all equipment, especially metals in pumps and piping, and necessitate the use of corrosion-resistant materials. Discharge of the acid mine drainage into streams neutralizes their normal alkalinity, causes them to become acid, and produces an environment unfavorable for aquatic life and unsuited for industrial or domestic use without costly treatment. Mine drainages vary in percentage composition over wide limits, although the usual dissolved substances are ferrous and ferric iron, aluminum, calcium and magnesium sulfates, and lesser amounts of sodium, potassium and manganese sulfates and chlorides. Some alkaline discharges may contain heavy concentrations of iron as iron bicarbonate. These waters may produce iron hydroxide deposits in the receiving stream but do not cause it to become acid. In the extensive literature on acid mine water there appears to be a great deal of confusion about the importance of various components and the methods for their determination. In many instances faulty conclusions have been drawn from use of unsuitable methods of analysis. It is desirable that the factors and terms used in evaluation of analyses of mine waters should be so clearly defined that any interested person could properly appraise any analytical report. Some analysts report complete chemical analyses of mine waters and neglect to record drainage volumes. Others report only a minimum of analytical data after taking no precautions to preserve the original composition of the water during the time elapsing between collection and analysis. Some use methods of analysis intended for so-called pure waters of the potable and boiler water classes. These methods are not applicable to highly buffered waters such as mine water. Probably the most common criteria for evaluation are pH, free acidity, or acidity or alkalinity to methyl orange or methyl red, total acidity or acidity to hot phenol-phthalein, and the sulfate content. If these determinations are made on carelessly collected samples after a few days to weeks standing in warm rooms, they do not in any way represent the character of the water flowing from the mines. It is hoped that a brief discussion of the fundamental value of some of these factors may lead to a bettqr understanding of the need for more careful evaluation of mine water discharges. The term pH is one used by chemists to express relative acidity or alkalinity in terms of concentration of effective hydrogen ion in a solution. It is defined as the negative logarithm of the hydrogen ion concentration or activity in equivalents per liter. pH = logarithm A neutral solution, which is one containing the same number of hydrogen and hydroxyl ions, has a pH of 7. As the hydrogen ions increase and the solution becomes more acid, the pH decreases toward zero; and as the hydroxyl ions increase and the solution becomes more alkaline, the pH approaches 14. When dissolved in water to a dilute solution acids like sulfuric and hydrochloric, commonly known as strong acids, ionize completely, and the pH or hydrogen ion concentration varies with molar concentration of the dissolved acid. However, in high concentrations of such acids, the pH or hydrogen ion concentration is less than the acid concentration because the acid does not completely ionize. In only very dilute solutions does the pH represent the total amount of acid that can be neutralized by an alkali. All ionization reactions are equilibrium reactions. If other chemicals are added to the solution of an acid and the added chemical produces an ion that is the same as one of the ions of the acid, the degree of ionization of the acid is altered and the pH changes to some value that represents the active hydrogen ion of the new solution. Thus if iron sulfate is added to a solution of sulfuric acid the pH increases, since the common sulfate ion suppresses the degree of ionization of the sulfuric acid and decreases the effective hydrogen ion. However, the total acidity of the solution is increased. There are two salts composed of iron and sulfate— ferrous and ferric sulfate. In these salts there is no hydrogen ion that can ionize to give an acid solution, but when they are dissolved in water, the pH is less than 7 and the solution becomes acid. This is caused by a reaction known as hydrolysis and is represented by the equations FeSO4 + 2H2O ? Fe(OH)2 + 2H + SO,: or Fe,(SO,)3 + 6H2O ? 2Fe(OH)3 + 6H+ + 3504 A solution with a total acidity of 5000 ppm according to the first equation will have a pH of 4.40 but one with an acidity of 75 ppm, according to the sec-

Jan 1, 1958

By P. J. M. van Heteren

The flotation system is usually distinguished from other physical chemical systems by the importance of interactions at the solid-liquid and solid-gas interfaces. In recent years, numerous quantitative studies have been made of the distribution of common collectors between the solid and aqueous solution phase. Although in flotation the main emphasis is placed on the adsorption process, chemical reactions will also take place in the bulk solution phase, These side reactions are often undesirable and will contribute towards the complex behavior of many a flotation system In sulfide flotation, the precipitation of insoluble base metal xanthates is a well-known phenomenon although the conditions under which the precipitation reaction will proceed and the magnitude of the solubility products are not known with accuracy. A knowledge of the solubility of these xanthate salts will not only be of value in flotation research, but the mill operator might be interested in knowing whether precipitation of metal xanthate can be controlled or completely prevented in the flotation circuit thereby reducing reagent consumption, For these various reasons the solubility of lead, copper, zinc, and silver ethyl xanthate was determined. The experimental techniques and results will be discussed in this paper.

Jan 1, 1958

By M. R. Geer

American and European practices in cleaning fine coal are strikingly different. The tables, launders, classifiers, and pneumatic devices used in America are seldom employed in Continental Europe, where much of the fine coal is cleaned in feldspar jigs, often supplemented by froth flotation of the extreme fines. This difference in choice of cleaning equipment may be fortuitous, but in large measure can be attributed to a difference in economic factors. Coal being more costly in Europe, there is greater emphasis on efficient cleaning of all sizes, including the extreme fines, and it is common to produce a high-ash middling for "on-site" consumption to avoid any waste of fuel value. The feldspar jig has been found advantageous under these conditions. In the United States fuel coal must be prepared as cheaply as possible, and metallurgical coal must be prepared as efficiently as possible; thus in both branches of preparation practice, any cleaning device that promises greater economy or higher efficiency warrants consideration. The feldspar jig, as employed in Europe, has a much higher unit capacity than the wet table used so extensively here and therefore offers economy in the capital costs of a washery through saving in space. As pointed out by Vissac,4/ the jig operates under automatic control, and therefore can cope with fluctuations in quality of feed. Maintenance costs for a single, large-capacity unit, such as the feldspar jig, would be expected to be lower than those for a battery of low-capacity cleaners. These considerations led the Bureau of Mines to undertake an investigation of the feldspar jig to determine its possible usefulness in this country.

Jan 1, 1958

By J. R. Nettle

The electrodeposition characteristics of seven binary alloys of titanium have been investigated. The object of the electrorefining experiments with an alloy was to determine the efficiency of titanium separation from individual alloying elements under established conditions. Reported results are only indicative. It is conceivable that numerous duplications of tests might give average maximums that would vary from those noted in this report; however, in the few tests that were repeated, the magnitude of transfer of the alloying elements was of the same order. The results detailed herein are for a given set of conditions. Many combinations of operating variables are possible, and the results achieved under different conditions probably would differ from those reported.

Jan 1, 1958

By J. H. Wernick

IN temperature-gradient zone-melting1 a molten zone is moved through a solid or across a solid surface by the establishment of a temperature gradient. This technique has both practical and fundamental aspects. One practical application is to make p-n junctions for semiconductive devices, particularly for devices in which the junctions are desired within the semiconductor. From a fundamental point of view, the technique is being investigated as a method for determining diffusivities in liquid alloys, and preliminary diffusivity results have been reported by the writer." In this paper, the effects of crystal orientation, temperature, and molten zone thickness in temperature-gradient zone-melting, and the bearing of these effects on diffusivity measurements and n-p-n junction formation are discussed. Experimental Procedure An effect of crystal orientation was noted in early experiments. To facilitate its study, movements of wire zones across a surface, rather than through the body of a single crystal, were observed for various surface planes and travel directions. The experirr-entai setup is illustrated in Fig. 1. The graphite end-section for the high temperature heater has an apron about 1/16 in. above the upper surface of the crystal. This apron insures that the surface temperature of the block is equal to or greater than the temperature within the block at every point, Thus, the zone does not penetrate the block and convection in the liquid is minimized. The experi-through a block is shown in Fig. 2,

Jan 1, 1958

By J. Ludden

By Sims Some two years ago we began investigating low coke button bituminous coal for use at our Bound Brook, New Jersey plant as a replacement for anthracite. Since August, 1957 the plant has been operating continously on this coal with the exception of a new 200,000#/hr, cyclone boiler. This study was motivated not from our desire to conduct combustion research, but for the sole purpose of reducing our steam costs, The indications were that the economics were greatly in favor of the use of the bituminous coal. The attempts to reduce the costs have developed some knowledge that has enabled this program to succeed reasonably well as will be discussed later by Mr. Ludden. The production of steam size anthracite is dependent upon either the reclamation of old culm banks or the breakage in the production of the domestic sizes. The anthracite industry has not as yet been able to cut, its mining costs to the point where the production of steam sizes has become a profitable business. This has resulted in two basic problems: (1) A constantly rising price in an attempt to have those sizes carry their share of the cost and, (2) Periodic shortages of supply when the demand is good but the market price prohibits the mining of anthracite to produce those sizes only, These conditions have made the long range forecast appear as though the price would go even higher and/or the supply at times be critically short.

Jan 1, 1958

By Kenneth E. Merklin

The heavy media process is now being used extensively throughout the world for the gravity concentration of a great number of different minerals. The process is a commercial adaptation of the heavy liquid procedure which has been used in laboratories for many years to separate mineral of different specific gravities. In the heavy media process, a suspension of finely divided particles in water is used to increase the apparent specific weight of the fluid to the desired separating point. The original heavy media process used sand, galena, pyrite and occasionally other materials as the solid constituent of the separating suspensions. As the process developed, the need for a more universal media meeting the following requirements was recognized: 1. High specific gravity. 2. Resistance to abrasion. 3. Resistance to corrosion, 4. Readily reduced to a suitable size consist for suspension in water. 5. Available in quantity at economical price levels. 6. Easy to recover by a simple method.

Jan 1, 1958