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By Richard O. Y. Breese

Geologically and commercially, the term diatomite is applied to the nearly pure sedimentarv accumulation of diatom frustules- the microscopic skeletons of unicellular aquatic algae belonging to the class of golden brown algae, bacillariophyceae. The sediments are fine-grained, siliceous, and consist primarily of amorphous opaline silica with only minor amounts of organic residue, secondary minerals, and co-deposited non-diatomaceous or crystalline clastic debris. In the geological sense, the name diatomite implies sedimentary accumulations that have reached appreciable thickness and when thick enough, such accumulations consequently may have possible commercial potential. Although the term diatomite is popularly and inappropriately applied to any sediment in which there is an abundance of diatom frustules, alternative terminology is more correctly employed to describe the less pure diatomaceous sediments, for example: clay-bearing diatomite or diatom-bearing clay. Synonyms in current usage include diatomaceous earth and kieselghur. More antiquated and obsolete terminology includes tripoli-powder, tripolite, and infusorial earth. Worldwide, diatomites occur within Tertiary to Recent lacus- trine and marine sedimentary facies. Although diatomite is wide- spread throughout the world, deposits that contain high purity, commercially versatile ore are uncommon. Physical properties of the diatom and of processed diatomite that provide unique commercial value in a broad spectrum of market end-uses include ornate fine structure, low bulk density, and high porosity and surface area. Properties of equal importance are mild abrasiveness, high absorptive capacity, insulating ability, relative inertness, and high brightness. End-use markets are diverse and range from insulating brick and absorbents through quality sensitive filter aids and premium quality functional fillers. Notwithstanding both the economic attractiveness of the specialty markets and the commercial versatility of the high purity deposits, deposits of lesser purity are mined in nearly all parts of the world for less demanding uses. Mining costs are minimized through open pit quarrying, but in Europe, Asia, Africa, and South America underground mining methods are also employed. Blasting is not required because diatomite is soft and easily broken loose with mechanized equipment. Following gentle crushing, the ore is dried, milled, and processed into one of three broad categories of products: naturally milled, straight calcined, and flux calcined grades. Each of these principal categories is further subdivided into additional grades through particle size adjustment of the powders. Agglomeration of particles, alteration of fine structure, and color change are achieved through calcination. Flux calcination further accentuates these changes. Production throughout the world is dominated by the United States, followed by Romania, the former Soviet republics, and France. Other major producers include Spain, Mexico, Iceland, Korea, Japan, and Germany. Denmark is a major producer of Moler earth products, which consist of a diatomite-clay mixture. HISTORICAL BACKGROUND The first industrial use of diatomite can be traced back some 2000 years to the Greeks and to the use of diatomaceous earth as a component in lightweight building brick and in ceramic pottery. It was not until the mid-1800s, however, that the unique properties of diatomite were first recognized and the market end-uses explored and developed. One of the most important of the early uses followed the development of dynamite by Alfred Nobel in the mid-1860s, whereupon diatomite was used as a component of the explosive to improve stability and safety. Other early uses included low temperature insulating and refractory bricks and as a component in insulating and fireproofing construction panels. During the 1920s, processing technology underwent a very rapid evolution with the development of calcination, flux calcination, and air classification technologies. Through these technologies, innumerable different size and grade classifications could be made for market applications and for rapidly diversified end- uses. Today, the application of processed diatomite for filter aid is the largest of the quality sensitive end-uses. Specific filtration uses include the clarification of beer, wine and liquor, vegetable oil, syrup and sugar, pharmaceuticals, and swimming pool water, to name a few. As a functional filler and extender, processed diatomite is ideally suited for application in paint, rubber, and plastic formulations. Other filler applications include use as an anti-blocking agent in plastic film, anti-caking agent for fertilizer, thermal insulating material, catalyst carrier, polish, abrasive, pesticide and fertilizer carrier, and chromatographic supports. Throughout much of the world diatomite is still used as a component of insulating brick and as an absorbent.

Jan 1, 1994

By Wisecarver D. W.

Today the longwall is getting increasing attention in the United States as an excellent way to mine coal. This is not to say it is the best way in every mine because conditions, capital costs, and markets may well dictate another method. However, operators with working longwalls are often showing preference by phasing out room-and-pillar sections and replacing them with longwall. In the United States there are about 90 longwalls in operating coal mines and the number is increasing. In Europe, 95% of underground coal mining is by longwall compared with only 5% in the United States. In the Western States about 25% of the underground coal mines use longwall mining. There is logic behind the increase in longwalling. Compared to room-and-pillar mining, straight single-pass longwall has important advantages that show up in underground coal mining in any part of the country.

Jan 1, 1978

By Stephen V. Thompson

Within recent years portable seismic refraction units have found their place in the industry for shallow investigations, Completely portable, relatively inexpensive and of proven accuracy, the portable refraction seismograph is an electronic tool in an electronic age. The age of electronic instrumentation has seen the development of seismic reflection and refraction equipment for deep exploration, especially in the petroleum industry. Large, expensive units, normally truck-mounted and utilizing explosives, are being used successfully for this type of sub- surface investigation. The portable seismograph utilizes the same theory for shallow work as that applied to deep refraction seismology.

Jan 1, 1964

By D. Malhotra, K. Purdy, G. Ramadorai

INTRODUCTION Today, flotation is clearly the dominant mineral concentration method. Since it is a relatively selective process, it is used for almost all sulfide minerals. A recent U. S. Bureau of Mines study indicated that approximately 225 million metric tons of sulfide ore was processed in 67 plants in the United States in 1980 (USBM Staff, 1981). There were over 100 plants processing copper ores in the world (Bassarear, 1985). Sulfide ores containing lead, zinc, copper, molybdenum, precious metals, cobalt, nickel, and iron are generally separated and concentrated by flotation. This chapter briefly reviews the plant practice related to the recovery of the above-mentioned sulfide minerals with emphasis on chemical reagents used for the production of marketable-grade products. PROCESSING OF SULFIDE ORES It is beyond the scope of this chapter to review the milling data for operating plants which have been extensively covered in literature (Tveter and McQuiston, 1962; Rausch and Mariacher, 1970; Weiss, 1985; Crozier, 1979). However, the following generalizations can be made regarding the processing of sulfide ores: 1. The primary grind is targeted to produce as coarse a product as necessary to provide an economic degree of liberation. 2. The concentration process, generally flotation, is designed to produce a concentrate consisting predominantly of valuable minerals and a middling fraction which may require further grinding to produce an optimum release of minerals. 3. The chemical reagent suite (collectors, frothers, etc.) for the separation of sulfide minerals from gangue minerals is generally complex. Total reagents used in the flotation process can be as high as six to eight, as is the case for lead and molybdenite separation from complex sulfide ores. 4. Chemical reagents are generally expensive because of the high selectivity for sulfide minerals. The process flowsheet is dependent on several factors, including ore grade and mineralogical composition. Generic process flowsheets for processing different sulfide ores have been developed for discussion in this chapter. However, there appears to be a consistent relationship between the reagent combination choice and the mineralogical composition of the ore (Tveter and McQuiston, 1962). These are covered in detail in the following sections. LEAD AND ZINC Galena (PbS) and sphalerite (ZnS), which commonly occur together, are the only minerals of lead and zinc, respectively, in most primary deposits. Feed ore grades are typically 1 to 5 percent Pb and 1 to 10 percent Zn. Very often economic quantities of copper and precious metals, silver and gold, also occur with these base metals.

Jan 1, 1986

By William F. White

It is a pleasure to have the opportunity of being here today to discuss the application of horizontal filters in the metallurgical industries. The use of horizontal type filters has been limited in metallurgical plants. However, in the recent past there have been new designs of this type equipment which greatly broaden their field of application. Through their use in many applications, important economies can be achieved over more conventional methods. The first of the modern continuous horizontal filters was initially developed by Oliver United Filters as their scroll type horizontal filter. This was an outgrowth of the old Oliver Sand Table that was limited to very coarse, free filtering pulps containing no appreciable amount of fine particles. The sand table was rather limited in application. The later continuous scroll type horizontal filter provided for a reverse air blow after discharge which reslurried the heel remaining and permitted the filtration of pulps containing finer particles. In the manufacture of phosphoric acid by the ?wet? process, the filtration of gypsum from the strong acid presented an extremely difficult filtration problem due to blinding of the filter media caused by crystallization of the soluble salts contained in the acid. A filter which allowed for continuous cloth washing was required, and this led to the development of the continuous pan type, and travelling belt type horizontal filters which provided for this need. Among the filters developed were the Prayon by Engineering and Industrial Corporation of Luxembomg for use in their phosphoric acid plants. They are one of the largest manufacturers of phosphoric acid in Europe. The Dorr-Oliver Traveling Pan Filter was also developed by Mario Giorgini, Manager of Dorr-Oliver?s Italian subsidiary, for use with the Dorr Company?s phosphoric acid process. Basically, there are four existing types of horizontal filters in commercial use at this time: The scroll discharge non-pan type, the continuous belt type (Lurgi), rotary pan type, and the traveling belt type. The construction and principle of operation of these various filters will be discussed.

Jan 1, 1958

By Stanley J. Gasior

Most bituminous coal mined near Eastern industrial areas requiring high Btu pipeline gas is caking and therefore unsuitable for fixed-bed pressure gasification by present techniques. If the caking property of such coal can be destroyed the resulting fuel can be gasified in a fixed bed at pressure with steam and oxygen as a preliminary step in making a high-Btu gas. To find a practical way to convert strongly caking coals of granular or small lump size to noncaking fuel was the object of this study. In previous work strongly caking coals of 1/8- to 1-1/2-inch size was converted to a noncaking coal char by treatment in a static bed in about 3 hours [1/]and coal of 18-100 Tyler mesh in a fluidized bed in about 5 minutes.[2/] An inert gas such as `steam, nitrogen, carbon dioxide, or a mixture of all three with a small amount of oxygen was used in both studies. In our work a strongly caking bituminous coal from the Pittsburgh seam of 4-8 Tyler mesh size was converted to a-noncaking form in free-fall in about 2 seconds by dropping it through a countercurrent flow of steam containing 4 to 7 percent oxygen at 1,150°-1,200° F and 300 psig. This method should also be applicable to smaller-sized material.

Jan 1, 1965

By J. P. A. Hortley

In conventional electrolytic copper production, looped copper starter sheets, on which the copper is deposited, are supported by hard-drawn copper bars. These bars have cross-sectional areas of between 1 and 1.4 in2. The suspension bars serve two purposes: firstly to support the cathode, which can weigh up to 150 kg, and secondly to introduce the electric current. IYI examined these two requirements in detail to see whether a better design could be achieved. Considering firstly the current carrying requirement, it wee noted that under normal refinery conditions, each cathode carries between 400 and soak. If one applies the generally accepted rule that 1 in of copper can carry 1000A4 a suspension bar need theoretically contain only 1/2 in2 of copper. This contention is supported by the fact that the 500A current passed through the cathode also appears to pass quite satisfactorily through the two support loops, which have a cross-sectional area of approximately 0.35 in 2. Turning now to the strength requirements, the cross-section of hard-drawn copper bar required to support a 150 kg cathode is relatively small, and easily met by the present designs. It is not, however, the static load applied by the 150 kg cathode immersed in the electrolyte which causes the damage to the hard-drawn copper, or even the increased static load of a 100 kg man standing on one foot in the centre of the bar; the damage is actually caused by the dynamic loads applied to the bare when they are dropped, thrown into containers, lowered too rapidly into the cell, or otherwise mistreated. The important requirement is therefore that the bar does not permanently bend. Its proof stress of limit of proportionality, rather than the amount that it deflects under static loading, should be the strength criterion. With the hard-drawn copper normally used for the manufacture of suspension bars, it has been observed that the copper becomes annealed during use, particularly at the end of the bar where the current is introduced. Thus, after a relatively short time, the cathodes are in effect being supported by annealed copper bars.

Jan 1, 1978

By R. Q. Honaker

Recent studies conducted at Virginia Tech have shown that ultrafine coal particles can be selectively coagulated and separated from mineral matter without the use of traditional agglomerants or flocculating agents. This technique utilizes hydrophobic interaction forces to induce coagulation of coal particles, while particles of mineral matter are dispersed using pH control. After selective coagulation, the coal coagula can be recovered by a sedimentation technique. In the present work, factors such as pH, particle size, and solids concentration have been examined. A wide range of coal samples have been successfully upgraded using this technique.

Jan 1, 1991

By Jan Visman, James W. Parkinson

GENERAL INTRODUCTION Sample collection, preparation and analysis are all steps in a single process designed to provide information about a much larger amount of material than the sample itself. For example, information about the ash content of a unit train load of coal may be derived from a single, relatively small sample of perhaps a few hundred pounds (liters) extracted from the entire shipment. These three steps can be thought of as links in a chain, allowing the simple analogy that the strength of the chain, or, in other words, the value of the information is only as strong as the weakest link. Sample collection, discussed in Part 1 of this chapter, is critical because analytical procedures can do no more than reveal the characteristics of the sample presented to the laboratory. If that sample does not properly represent the population to be characterized, neither will the analysis of that sample. Sample preparation is also a critical part of the chain. Any change in the nature of a sample between the time it is collected and the time it is analyzed will appear to reflect the nature of the population. For example, sample preparation procedures that allow air to partially dry the coal sample before reaching the laboratory will cause the sample analysis to indicate a lower moisture content than the sample originally had. Other changes can be more subtle. Second only to moisture loss, oxidation reactions generally cause the greatest problems. Oxidation of a coal sample can alter surface properties, changing flotation response. In extreme cases, combustion parameters, such as caking or agglomerating properties or mineral composition, such as pyrite content, can change. Water samples can also be altered by oxidation. For example, ferrous iron can oxidize to ferric iron, possibly changing water quality parameters such as pH. Sample analysis, the subject of Part 2 of this chapter, is the final link in the chain. Obviously, no laboratory procedure can correct for problems created by improper sample collection and preparation. At the same time, poor analytical techniques will create incorrect information about the total amount of coal from which the sample was extracted (the population) in the same manner as improper sample collection and preparation. The key to gaining correct information about the population is to view these three steps as parts of a single process. Following proper techniques through only one or two steps of the process will not produce accurate information.

Jan 1, 1991

By R. Kingman

At Tahawus, New York, National Lead Company operates the MacIntyre Development, This operation produces 10,600 long tons of ore per day for crushing, 8,000 tons for grinding and processing, of which 2,000 tons per day reports as tailing for disposal in an impounded tailing storage area. With the change in location of mining operations at the mine of National Lead Company, a change in the area for tailing disposal by gravity became necessary, This called for the diversion of tailing from near the proposed mining area to areas more favorable for long term storage by gravity. In order to avail the operation of maximum storage for the future, a uniform minimum grade launder was proposed with a minimum velocity and maximum outfall at the discharge. Disposal of the gravity and flotation tailing was formerly accomplished in open ditch from the concentrator at a grade of 1.5 percent. It was desirable to design the new launder at grades less than this for the greater storage elevation.

Jan 1, 1966

By S. P. Singh

In order to understand the intricate nature of blast damage mechanism and to counter the associated problems, small scale blasting experiments were performed on hydrostone, concrete and granite. This was followed by a 2.4 m x 2.7 m (8'x 9') drifting operation in a quartzite quarry. Interior as well as exterior damage was assessed by different techniques. On the basis of the experimental results, the effect of explosive characteristics on the damage was examined.

Jan 1, 1992

By John P. Norton

Microcystaline silica has been mined in Illinois from the Clear Creek formation since the turn of the century, especially in the area around Tamms in Alexander County, in the southernmost part of the state. Production of this silica, consumed mainly by the abrasives and coatings industries but also sought after for many filler/extender uses, has grown with the economy with several new applications overshadowing traditional markets in recent years. Such an important commodity was given the early attention of the Illinois State Geological Survey and a very complete report was issued in 1953 (Report of Investigations No. 166), authored by J. E. Lamar. The mining and processing of the silica ore has changed very little since the first reported production in 1906, although emphasis has been placed on the production of the finer sized grades to meet newer market requirements. Industrial Mineral Notes 40, published by the Illinois State Geological Survey in June 1970, describes a method by which a less than 1-micron fraction could be commercially produced from the readily available finest commercial grade presently being marketed (99% minus 10 microns). The finer grades exhibit to a lesser degree the reinforcement, high flatting efficiency, thickening and dry brightness properties associated with the synthetically produced silicas. It is expected that the extremely fine grades of microcrystaline silica will become accepted in the markets that now use a combination of precipitated silica and less expensive extender/filler minerals such as kaolin or calcium carbonate.

Jan 1, 1976

By Daniel G. Ganey

Kerr-McGee Coal Corporation has used diesel face haulage and support equipment at its dual-seam Galatia Mine in Southern Illinois since production activities commenced in 1983. The mine began production from its lower seam, the Harrisburg No. 5 coal seam, in October 1983 and from the upper Herrin No.6 coal seam in April 1985. Before production began, the company developed a program designed to make use of the flexibility offered by diesel equipment. While productivity was an important goal, the top priority of the program was to provide a safe and healthy work environment for the miners. Management believed that high productivity would naturally follow. History has proven this belief to be true.

Jan 1, 1990

By James M. Barker, Richard O. Y. Breese

The recognition of perlite as a distinct volcanic glass, and of the arcuate fractures that often characterize these natural glasses, dates back at least to the late 19th century and perhaps into the 18th century (Howell, 1974). Some authors suggest that recognition of perlite dates considerably further into antiquity, perhaps to the 3rd century BC (Caley and Richards, 1956). Most recent definitions identify perlite by the presence of vit¬reous, pearly luster and by the presence of characteristic concentric or arcuate perlitic fractures. As discussed more fully below, arcuate fractures in perlite need not be megascopic. The textures of perlite which commonly occur in deposits range from dense to highly vesiculated to pumice-like. Thus, the classical definition of perlite is descriptively restrictive compared to the natural range of textures and neglects to address the issues of genetic origin and geologic occurrence. In spite of the petrological usage of the term perlite, the in¬troduction of expanded perlite aggregate into industrial markets caused the term to be applied as well to the lightweight, cellular aggregate that is produced through the rapid thermal expansion of milled perlite ore. Perlite is distinguished petrologically from other natural glasses by a silicic or rhyolitic composition by the presence of 2 to 5 wt% total chemical water held within the glass structure and often by the presence of pearly luster and onionskin-like perlitic fractures. Worldwide, occurrences are associated with Tertiary through early to middle Quaternary volcanics and with the glassy portions of silicic domes and flows, with vitric tephra, with the glassy chill margins of dikes and sills, and with the glassy portions of welded ash flow tuffs. Less commonly, perlite is reported in association with the glassy portions of volcanic plugs and lacco¬liths. The perlite carapaces that partially or fully comprise extru¬sive domes and flows are often thick and areally extensive, and thus provide commercially attractive targets for low cost open pit mining. Perlite tuffs and tephras are also important commercial sources. Mining costs are minimized by open pit quarrying and by either bulldozer ripping or blasting. Crushing and sizing facilities are generally close to the pits. Due to the low weight and large volume of expanded perlite, unexpanded perlite that has been crushed and sized is usually shipped nationwide directly to local markets where it is expanded and processed for distribution to end users. The vast majority of international trade is in unexpanded perlite. In the United States, the evolution of the expanded perlite industry can be traced to the late 1930s and early 1940s when expanded perlite aggregate was introduced into gypsum plaster and concrete markets as a substitute for vermiculite (Schundler, Jr., oral communication, 1991) and was promoted for use in a much broader spectrum of products (Howell, 1974). By the early 1950s, end user markets were well established and small expanders were numerous east of the Mississippi River. Today, mining and expan¬sion is undertaken throughout the world. Worldwide production of perlite is dominated by the former Soviet republics, the United States, and Greece. Total worldwide production of processed perlite during 1990 is estimated at roughly 1 778 000 tons (Davis, 1991). The physical properties of expanded perlite that give this prod¬uct unique commercial value include: low bulk density, chemical inertness, high insulating ability, nonflammability and fire resis¬tance, and its ability to retain water. These and other physical properties give expanded perlite value in such uses as: lightweight acoustical and thermal insulating aggregate; component in plaster, insulating cements and lightweight concrete; loose fill insulation; as aggregate in horticultural applications; and in milled form as filter aid. In the United States and Europe, the largest end use is within building construction products.

Jan 1, 1994

By S. P. Girrens

A coupled finite element geomechanical- hydrology code is currently under development for application to the problem of predicting groundwater disturbances associated with mine subsidence. The structural-fluid coupling is addressed by calculating the subsided mine geometry, with emphasis placed on determining the strata disturbance and locating damaged regions, for input into a hydrology code, which determines localized volume flow rates and aquifer fluctuations. Benefits from coupling will be best realized when field measurements, an additional aspect of the study concurrent with analytical investigations, indicating the relationship between increasing rock strain and increasing permeability are incorporated into hydraulic material descriptions. Hydrologic and struc- tural calculations are presented to demonstrate computational capabilities applicable to mine subsidence

Jan 1, 1982

By Yu. A. Polozov, V. A. Lagunov, O. Yu. Lushinkova, Yu. I. Svirskiy, Eh. Ya. Kipko, Roy A. Williams

Hydrodynamic investigations in exploratory boreholes and grouting holes are conducted for the purpose of obtain¬ing information about the hydraulic properties of the hydrostratigraphic section to be intersected by the proposed underground workings. The information obtained from the investigations provides the basis for calculating the hydrau¬lic coefficients of fractured permeable rock, the dimensions of the anticipated grout isolation curtain(s) around the un¬derground workings, the number and location of grouting holes, the injection pressure modes, and also the volume(s) of grout that will be required (Anon., 1976, 1978). The following data on each aquifer are obtained from the investigations conducted in monitoring and grouting bore¬holes and the analysis of the results: 1) the top of each hydrostratigraphic unit, 2) the thickness of each unit, 3) the ground water fluid potential distribution in each unit, 4) the coefficient of permeability, 5) the piezoconductivity, 6) the fracture porosity, 7) the geometry of the fractures in the rock, 8) the elasticity-compressibility coefficient of the fractured rock, 9) the chemical composition of the ground water, 10) the direction of flow of the ground water, and 11) the expected inflow rate of water into the shaft, drift or tunnel. STG uses its DAU-3M type flowmeter to conduct in¬vestigations of directions of flow in vertical, inclined and horizontal drillholes. The DAU-6 instrument is used to de¬termine the direction of flow of ground water in each frac¬ture or fractured aquifer. Various singular and double DAU type packers are used for pumping and for injection studies (tests) and for flowmeter investigations. Normally the instruments enumerated above permit in¬vestigations to be conducted in each separate aquifer with¬out reinforcing the holes with casings. On the basis of these investigative data, both the hydraulic properties of unfractured rock and the hydraulic properties of the fractured rock are estimated. Dual porosity rocks require special attention because they tend to segregate the grout. 3.1 FLOWMETER INVESTIGATIONS IN BOREHOLES The STG flowmetric methodology is based on the mea¬surement of the ground water flow rate through the borehole by hydrostratigraphic interval after the disturbance of the hydrostatic equilibrium in the "hole-aquifer system" (after pumping or injecting). The relationship of the head changes to the discharge into or from a particular hydrostratigraphic unit obtained during the tests serve as the basis for calcu¬lating the hydraulic properties. Flowmetric investigations facilitate the determination of the number of aquifers, their depths, their thickness, the hydraulic properties of the fractured rock and the magnitude and direction of the flow of ground water. 3.1.1 FLOWMETER HARDWARE STG conducts flowmetric investigations in boreholes using its DAU-3M-108, DAU-3M-73, DAU-3M-57 and DAU-3M-44 instruments.' They have respective external diameters of 108, 73, 57 and 44 mm. The type of flowmeter selected for use depends on the borehole geometry and the technological scheme for carrying out the investigations. Boreholes with a drilling diameter of 76-93 mm are inves¬tigated with the DAU-3M-73 flowmeter; boreholes drilled by bits with a diameter of 112 mm and more are investi¬gated using the DAU-3M-108 flowmeter. The DAU-3M¬108 and DAU-3M-57 instruments are used for flowmetric investigations with a packer. 3.1.1.1 The Downhole Sensor The sensor design of the DAU-3M-73 hole flowmeter is shown in Fig. 2. The design of the DAU-3M-108 instru¬ment is similar to the design of the DAU-3M-73 instrument. The frame of the flowmeter sensor shown in Fig. 2 consists of a casing, an upper and lower centering mount and two rings to which the guiding rods are attached. The upper rods are built into the connector bushing; the lower rods are built into the coupling sleeve. The borehole cable is attached using a half-coupling, a packing ring and a constriction nut. Thus, the frame of the flowmeter sensor is made so that the free passage of water to the impeller is facilitated along with the necessary rigidity. The primary moving component of the flowmeter is the double-bladed impeller, which rotates on cobalt-tungsten pivots and agate thrust bearings. Special extended air cham¬bers protect the supports of the impeller from the action of the borehole fluid which may contain fibrous and abrasive particles. The air located in the chambers shields the sup¬ports from direct contact with the borehole fluid when the sensor operates in a borehole. The hollow casing of the impeller serves the function of a lower cap. The upper cap is attached to the casing using a threaded connector; it is affixed also with a lock-nut. An adjusting screw with a

Jan 1, 1993

By Henry N. McCarl, Gary Waters, William A. Vogely

INTRODUCTION In the past three decades, world trade has grown from less than $100 billion per year in the years following World War 11 to slightly more than $300 billion in 1970 and over $2,000 billion in the early 1980s. Adjusted for inflation, the real growth of world trade in 1972 dollars increased from less than $175 billion per year in the early 1950s to slightly more than $342 billion in 1970 and almost $700 billion per year by the early 1980s. Thus trade as a whole has increased a little more than twofold in real terms in the past decade." Mineral commodities constituted approximately 20% of the value of total world trade in 1970, and significantly more than that proportion in terms of physical volume. By 1980, de- spite rapidly rising petroleum prices, mineral commodities accounted for roughly 18% of the total value of world trade. Crude oil alone ac- counted for about 16%, making it the single most important commodity in international trade. The worldwide recession of 198 1- 1983 brought a dramatic decline in both volume and price of crude oil, shrinking the impact of mineral commodities to roughly 10% of the value of total exports, worldwide, in 1982- 1983. The decline of mineral commodities as a pro- portion of the value of world trade in the decade 1970- 1980 is due largely to the increasing importance of manufactured goods and consumer products such as automobiles and electronic items. During this period, mineral commodity trade expanded roughly sixfold in terms of current dollars to an estimated $350 to 360 billion in 1980. This was equivalent to doubling the real value of mineral commodities in international trade in the 1970- 1980 period in constant dollars. The U.S. Bureau of Mines has expanded the traditional definition of mineral commodities to include semifinished products such as iron and steel (in addition to iron ore), refined metals such as copper, lead, zinc, aluminum, and tin, concentrates, scrap, and petroleum products. Since large quantities of essentially mineral derivatives travel in this form, it is reasonable to use these expanded definitions in stating the role of minerals in world trade. Thus minerals in world trade comprise 30 to 33% of total export trade in all commodities during the period 1976- 1980 (see Table 1.3.1). In addition, the U.S. Bureau of Mines estimates the value of all mineral commodities consumed in the world (at the national level) and compares this value to total worldwide commodity consumption. By this system, mineral commodities range from 30 to 40% of all commodities consumed each year in all countries during the period 1976- 1980 (see Table 1.3.2). The growth in export trade in mineral commodities by commodity group is shown for the period 1976-1980 in Table 1.3.3. These data parallel the swings in worldwide economic activity during the same time period. By any of the above measures, minerals, especially the fossil fuels, constitute a significant proportion of both total economic activity and

Jan 1, 1985

By John T. Awald

The Bradshaw Mountains of west-central Arizona cover an area of 1600 square miles and contain numerous old mines and prospects. The area has been geochemically sampled on a reconnaissance basis to relate mineralized areas to regional structure and rock types. Copper analyses of stream sediments have been classified and contoured to show the distribution of low background, high background, and low, intermediate and highly anomalous areas. Contoured results are compared to geology and known mines. Several prospecting areas are indicated.

Jan 1, 1970

By J. R. Palmes

Three coal samples, selected out of eight with well characterized surface properties, were used in flocculation tests and synthetic mixture of coal and silica was used in the selective flocculation experiments. Coal wettability and flocculant type were found to have a strong effect on the flocculation results.

Jan 1, 1993

By Harry W. Barr

Judging by the inquiries that come to Battelle, a number of companies have run into problems in determining the size and character of markets for mineral fillers in general and specialty fillers in particular. Usually these problems arise during a project to develop a new mineral filler when management suddenly realizes that a considerable sum of money will have to be spent before any profits are realized from sales of the new filler. What management needs in this case is the odds for or against the success of the development. And these odds frequently are controlled by the markets for the new filler. Basically, the problems involved in gaging markets can be simplified to how much of this new filler can be used and by whom? But there are some potential booby traps in these simple questions that should be exposed. This paper will discuss a few of these problems such as: 1. Describing the filler so that the prospective customer recognizes its possible applicability. 2. Finding; a prospective customer who can verify the filler's applicability. 3. Expanding successful test results to total industry markets. 4. Appraising competitive products, and 6. Discovering all the possible uses for the new filler.

Jan 1, 1961