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By Charles E. Robertson

As it becomes more and more apparent that our nation must place a great deal of reliance on coal as an energy source in the coming decades, prospecting for new reserves Un Missouri and other states in the Western Interior Region is increasing. As more and more of the known reserve becomes committed to existing or planned projects operators will be forced to look beyond the fringes of existing coal fields for additional reserves. Perplexing geologic problems invariably confront all prospectors and are particularly bothersome to those new to a particular area. It is the purpose of this paper to alert prospective operators to geologic problems likely to be encountered and to offer guidance in the recognition and solution of these problems. Particular emphasis is placed upon geologic structure and washouts. Other geologic problems have been discussed in a previous paper.

Jan 1, 1977

By J. C. Agarwal

A significant portion of the, coal mined by U. S. Steel is beneficiated to upgrade the quality of the resultant coke to meet blast-furnace requirements. Primarily because of degradation from modern mechanized mining methods, a considerable quantity of the coal to be beneficiated is in the 1/4-inch by 100-mesh size range. In the cleaning plants, this coal is usually cleaned on concentrating tables and then mechanically dewatered in solid-bowl centrifuges to 9 to 14 percent water. At some plants, to further decrease the amount of water shipped with coal, and to improve the coking characteristics of the coal at its destination, mechanical dewatering is followed by thermal drying. At U. S. Steel's-Alpheus preparation plant at Gary, West Virginia, approximately 50 percent of the total coal produced is in this fine size range, and two fluidized-bed dryers are used for the thermal drying step. The two fluidized-bed dryers are 14 feet in diameter and were designed by the Dorr-Oliver Company. Although the original design called for a rate of drying equivalent to 37 tons, of moisture per hour, presently they are removing twice that amount. This paper describes, the major problems encountered' in operating these dryers at the present, high capacities and how they were overcome.

Jan 1, 1963

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

The STG integrated method of grouting can be divided into the several phases as outlined in preceding chapters. For convenience in describing technical procedures, they can be grouped as: 1. Investigations in non-geotechnical, exploration bore¬holes. 2. Drilling the holes necessary for geotechnical investiga¬tions and for grouting. 3. Conducting appropriate hydrogeologic tests in those holes and consequent calculations. 4. The preparation of a clay mortar. 5. The preparation of a clay-cement grout with additives. 6. The injection of the grout. 7. Checking the quality of the grout curtain. Items 2, 4, 5 and 6 are discussed below. These activities contain the procedural aspects of grouting. 7.1 DRILLING GROUT HOLES Grout holes belong to a very select class of drillholes. The necessary drilling equipment must enable the operator to drill the holes in inclined, twisting directions. In addi¬tion, the equipment must permit drilling under structurally and hydrogeologically complex conditions. The equipment must permit the operator to conduct specific testing activi¬ties in the drillholes. These activities include hydrodynamic analyses, flowmetric analysis, and the installation and re¬moval of deflectors, packers, grouting plugs, casings, lin¬ers, pumping facilities and other work. As explained in Chapters 5 and 6, the grouting of sat¬urated rock is conducted both through holes drilled from the surface and through holes drilled from the face of a shaft, drift, or tunnel. The drilling of grout holes from the surface can be carried out by an aggregate of equipment that can be the same equipment used for drilling exploration boreholes. Depending on the projected depth of the holes, the STG ZIF- 1200MR and ZIF-650 drilling rigs (or modifications of them) are used. The SKB-4, SKB-5 and SKB-7 high-output drilling rigs (workover rigs) have been used in recent years. The STG BMP-24 drilling rigs are used for carrying out the descent-lifting operations for drilling holes from the sur¬face. In a number of cases, the UKB-500C, URB-3AM and URB-2A power-fed drilling equipment is used for drilling holes from the surface. It should be noted that the drilling of grout holes usually requires an electric drive assembly. Drilling with diesel drive assemblies would be used only to preclude the possi¬bility of losing electric power during drilling operations. Turbine drilling would be used only for appropriate techni¬cal-economic reasons. The selection of the grout hole design is determined by the hydrogeological and structural geological conditions at the site as interpreted in Chapters 2 and 3. The design of grout holes must be as simple as possible in order to min¬imize costs. Hole design guidelines can be adopted as a basis for this purpose, unless site-specific conditions require otherwise. The mouth of the drillhole must be outfitted with a guide-pipe having a length of at least 2 m and an outside diameter from 219 to 234 mm. The upper part of the hole must be attached by a jig consisting of borehole casing that has a diameter ranging from 108 to 146 mm. The length of the jig h is determined by the equation [ ] where k = 1.1 to 1.2 is the load factor; P,, is the injection pressure of the grout into the mouth of the drillhole; D is the external diameter of the jig pipe; m = 0.6 to 0.7 is the work condition factor; T[ ].1 MPa is the bonding value of the rock cemented to the jig. The grout hole is drilled from the jig shoe to the de¬signed depth using a rock-crushing bit with a diameter of 93 mm or more. However in complex hydrogeological condi¬tions when the shaft intersects unstable rock, other hole designs can be used. The diameter of grout holes must permit an aggregate of investigations to be conducted in them using down-hole borehole geophysical and flowmetric logging instruments. It is necessary to cement the casing strings reliably in the grout holes, thereby permitting the injection of the grout under high pressure through the pres¬sure tight mouth of the borehole. Technological details for drilling grout holes such as the rotational rate of the drill bit, the axial load on the rock¬crushing bit, and the drilling fluid flow rate are optimized for the specific rock-hydrogeological conditions largely by experience. The hole diameter and type of rock crushing bit are important variables in these details of drilling. It is advisable to drill holes using water as the drilling fluid. However in those cases where the hole walls are unstable or under very high ground water pressure, the use of a well¬ engineered drilling mud should not be precluded. Unfortu¬nately, drilling mud can influence test results. When steeply dipping fractures with inclination angles of more than 60 to 70° are encountered, it is necessary to drill guided, inclined grout holes. This procedure permits the maximum number of fractures in each hole to be stu-

Jan 1, 1993

By K. W. Harris, K. A. Perry

Reserve depletion in Central Appalachia is continuously creating unique ground conditions for underground coal mines with many of these difficult environments directly attributable to multiple seam mining and/or deeper overburdens. While many empirical studies have been performed in an effort to improve understanding of these problems along with potentially improving safety and extraction, many of the difficulties encountered lie outside of the normal realm of expected behavior. This is often the case when mining in bump prone ground, where additional concerns are introduced and design buffers are warranted. The boundary element software LaModel was used to study three bump events in a deep-cover, multiple-seam reserve located in Harlan county in the Kentucky region of Central Appalachia. This region is notoriously bump prone due to significant areas of deep cover, the presence of strong to massive lithology (such as sandstone), and an extensive history of underground mining that increases the probability of multiple seam interactions. Multiple seam interactions are best understood with respect to site-specific parameters, including both the geological and geometrical components of interburden, overburden and mine workings. Initially, empirical-based approaches (ARMPS/AMSS) were used when attempting to back-analyze the bump events. However, it was recognized that a more detailed investigation was necessary to understand the fundamental causes/conditions associated with the bump events. Consequently, the LaModel study resulted in a mine-specific calibration method for the reserve. With this method in place, enhanced bump prediction throughout the reserve is expected, such that the stability, recovery and safety of future mining may be improved.

Jan 1, 2014

By D?Arcy R. George

A survey of the copper mining industry in Western United States revealed that uranium is almost universally present in the solutions resulting from leaching the waste ore dumps to recover copper. The U308 content ranges from about 2 to 15 ppm and a potential production of up to 1,000 tons of U3O8 per year is indicated. A six-week pilot plant test at the Bingham Canyon mine of Kennecott Copper Corporation showed that the uranium is readily recoverable by ion exchange techniques. The design of the new types of countercurrent ion exchange columns and operation of the pilot plant are described.

Jan 1, 1967

By Fritz Kleiner, Walter Meintrup

On Nov. 4, 1981 A/S Sydvaranger's 1-kt/h (1,100-stph) wet-process, iron ore ball mill completed its first four months of uninterrupted, full-load operation in Kirkenes, Norway. This 6.5-m-diam (21-ft-diam) mill is driven by a gearless ring or wraparound 8.1-MW (10,860-hp) motor at 13.1 rpm-a first of a kind in this segment of industry. This article examines reasons for selecting this type of drive over more conventional schemes, lists specific advantages of such large mills, and describes the installation in Norway. History For almost a decade, good operating experiences have been gained with 28 gearless ring motor drives in the cement industry, driving 2.5 to 4-m-diam (8.2 to 13-ft-diam) tube mills with drive powers ranging from about 3-4 MW (4,000 - 8,000 hp). Why then did the mineral ore processing industry hesitate until 1980 to adopt this successful concept for similar applications on ball, semiautogenous, and autogenous mills? There are a number of good reasons in the eyes of conservative mill builders and operators, the most commonly cited ones are: • No operating experience in this segment of specialized industry. • More severe environmental conditions in the wet ore grinding process. • An indifferent attitude of mill builders and electric motor manufacturers towards new drive technologies. • Limited confidence in solid-state power supply systems, such as frequency converters of the required size. There have been and still are numerous problems associated with low-speed geared mill drives of any kind, especially with individual motor/gear sizes approaching or exceeding about 4 MW (5,360 hp). Every mill builder knows about them, but operators learn to accept them as inevitable. The Decision to Change Three things combined to break this technological stalemate: the courage and progressive spirit of one major iron ore processor in Scandinavia, the cooperation of three experienced manufacturers, and an unusual application problem that could not be solved by any conventional approach. The last factor was surely the decisive one, but the first one does not come as a surprise either. The Swedes near Kiruna and the Norwegians around Kirkenes are experienced ore miners and processors, and much credit goes to them for technological breakthroughs in the industry. At A/S Sydvaranger in Kirkenes, above the Polar circle at about the latitude of Alaska's northern tip, the existing grinding facilities, with a total of 14 100 to 240-t/h (110 to 264-stph) ball mills, can not be expanded. Nevertheless, to increase mill throughput, only installing a larger mill in place of an existing smaller one was a practical alternative. For this replacement, the owners set requirements that seemed impossible to meet: • The old 100-t/h (110-stph) ball mill should be replaced with a new ball mill with 10 times the rated throughput, without significantly impairing the operation of the remaining mills, and without significantly changing the mill building. • The new mill should have a variable-speed drive to ultimately optimize the grinding process by means of a closed-loop process¬computer-controlled grinding cycle, and to minimize the specific energy consumption. • Availability, efficiency, and life expectancy of all new components must be higher than those being replaced. • Inrush-current and harmonic loads on the rather weak electric supply line must be minimized to ensure safe plant operation. All old ball mills at A/S Sydvaranger are the geared type, using single synchronous and wound-rotor, slow-speed motors with ring-and-pinion gears. Operators are familiar with the limitations and problems associated with such drives, and they are aware that the following items become major concerns when drive powers are drastically increased: • Gears are subject to wear and tear, require frequent maintenance, and eventual replacement of major parts. • Gears are sensitive to misalignment, overload, and thermal distortion, limiting their useful life. • On dual or quadruple drives, load-sharing and torque oscillations between motors can be a major reason for concern. • At these speeds, ring-and-pinion gears reach their torque transmission capabilities altogether at around 4 MW (5,360 hp) per motor/pinion. To obtain the desired variable-speed performance of the new drive, the only practical and economical conventional solution would have been a frequency-controlled, low- or medium-speed dual motor drive with about 8 MW (10,720 hp) of power. This, however, was not feasible because of limited floor space. Therefore, bids were solicited for the alternative drive method, the gearless ring motor. General Considerations Why are such large mills considered? After all, one could avoid all the problems by simply staying with smaller mill unit sizes. Under competitive pressures of free markets, however, grinding efficiencies and specific energy consumption become key factors in selecting new equipment. Specific energy consumption of ball mills decreases with increas-

Jan 9, 1982

By Stephen C. Moore

The Grossschloppen vein-uranium deposit, Bavaria, West Germany, was examined utilizing underground workings during 1980-82 by Esso Erz GMbH, an affiliate of Exxon Minerals Company (EMC). Geologic evaluation entailed dense drilling of a portion of the deposit from workings constructed specifically for the program. Discovered in 1977, the deposit was initially explored by surface diamond drillholes which allowed definition of a 30-60 m wide vein system discontinuously mineralized along a 1000 m strike length and to at least a 450 m depth. The underground program was conceived as a cost effective procedure to answer questions on vein correlation, grade continuity and variability. A 1200 m decline allowed access for detailed sampling of approximately 10% of the known area of mineralization. Fanned drillholes, logged by gaga probe, were spaced to provide intersections of veins at 10 to 20 m intervals. Six cross cuts also penetrate the pitchblende and uranophane mineralization which occurs in 0.1 to 2.5 as thick quartz veins. Detailed cross-sections and level plans were constructed for resource estimates of the intensively studied portion of the vein system. The program resulted in the discovery of local, high grade areas and an average grade in the evaluated area nearly double that expected from surface drilling.

Jan 1, 1983

By G. Johnston, P. K. Chatterjee, S. Holguin

M. Gershon The article is an excellent one, providing a basis for the conduct of the major tasks in underground mine planning and scheduling. I object to only one word. Since that word is featured in the title, it is a strong objection. The word used erroneously is optimization. There is no optimization performed in the article. By definition, an optimization is an approach that yields the best of all possible solutions. We can limit this definition to its narrowest sense, the optimization techniques of operations research such as linear programming, or broaden it to include less sophisticated search procedures that find the best mine plan or schedule. No such claim is made in the article. No optimization of any kind is performed. The major tool used is a simulation, which, in truth, is probably more appropriate for this problem than any optimization. But simulation does not optimize. It only allows for quick evaluation of many options, leading to the selection of the best plan "of those tried," not "of all possible plans." This article, of course, is not the first mining paper to make this error. It seems that the word optimization is used more to impress people than to refer to any act of optimizing. It is used in a way that implies "try to optimize"or "come close to optimize," but not to really do it. It is usually appropriate to quietly ignore this error. But when Dr. Chatterjee, who has done so much good work in true optimization projects and whose work I have come to admire, makes such an error, it is time to publicly dispute it. Having discussed this very point with him in the past, I am sure that he will agree. If he can support this position in his response, perhaps people will start to listen and we can reduce the number of false claims of optimization. This should be easy for him in this case since the approach he used, simulation, is the more appropriate one anyway.

Jan 8, 1988

By Robert L. Akright

The Sumich (Victorine) gold mine is located in the Toiyabe Mountain Range on the east side of Victorine Canyon, a north-trending branch off Kingston Canyon in the northwest quarter of Section 27 and southwest quarter of Section 22, T16N, R43E, in the southern end of Lander County, Nevada (Fig. 1). HISTORY Discovered in 1862, the Victorine reached a peak of development between 1872 and 1887. The "Victorine" and "Morning Star" lode mining claims, located on the outcrop of a prominent auriferous quartz vein, were patented in 1869 and 1891, respectively. 1, respectively. Gold ore was mined underground in adits driven, on the level, directly into the side of the mountain. Ore brought to the surface was trammed about 457 m (1500 ft) south on a track constructed along the contour to ore bins. From this transfer point, the ore was moved by aerial tram to the bottom of the canyon then hauled by horse-drawn wagon to the mill located about 3.2 km (2 miles) east down Kingston Canyon. Exact details of the milling process used on the Victorine are lacking, but old reports mention water-driven stamp mills, amalgamation, chlorination, and cyanidation. Gold and silver mill products are reported to have been sent to England for final refining. High-grade gold values of 103 g/t (3 oz per ton) remaining in mine walls and on outcrops, attest to the lack of success in treating the Victorine ore in the early mills. The Victorine mine may have been worked sporadically after 1887 with little success. In 1934, control of the property was acquired by William P. Moloney, an attorney from Marion, OH, who also control- 1 led an interest in the successful Goldacres mine in Lander County, NV. This property was studied, sampled, and metallurgical tests were done in 1934, but no development resulted from this work.

Jan 1, 1990

By Robert F. Conley

In the mining, manufacturing and application of inorganic pigments, dispersion contributes significantly. This is especially true with mineral pigments because of the variety, in slurry operations required for their processing. Such operations include any of the following: (1) mine-transport (2) wet grinding (3) flotation/beneficiation (4) wet magnetic separation (5) selective floculation (6) size classification (7) chemical processing (8) spray drying Dosage levels and general economics of dispersant use are broadly variant, being dependant upon the agents employed, from the simplist, i.e., sodium silicate or sodium carbonate, to the more complex, as polyacrylates and organo-phosphates. In certain unit processes the dispersant must exhibit unusual chemical stability and persistence, e.g., in protracted pigment slurry shipments. In others, the agent should be fugitive to prevent secondary reactions from occurring, e.g., with high temperature calcination where alkali salts can act as aggregation fluxing agents.

Jan 1, 1985

By Ralph Musick, Brian Briggs

The U1h Shaft Project is a design/build subcontract to construct one 6.1 meter(m) (20 feet [ft.]) finished diameter shaft to a depth of 321.6 meters (m) (1055 ft.) at the Nevada Test Site (NTS). Atkinson Construction was subcontracted by Bechtel Nevada(BN) to construct the U1h Shaft for the Department of Energy (DOE). The project consists of furnishing and installing the sinking plant, construction of the 321.6 m(1055 ft.) of concrete lined shaft, development of a shaft station at a depth of 297.5 m(976 ft.), and construction of a loading pocket at the station. The outfitting of the shaft and installation of a new hoist may be incorporated into the project at a later date. This paper will describe the design phase, the excavation and lining operation, shaft station construction and the contractual challenges encountered on this project.

Jan 1, 2001

By Greg T. Saretzky, Wilson G. Ward

A comprehensive hydrologic study was completed far the waste rock dump at Equity Silver Mine, BC. Characterization of the hydrologic system included geologic structure. topography, surface hydrology and groundwater systems. The results of the study conclude that the cover system is restricting net infiltration to approximately 5%. However, significant discharge continues to occur from the perimeter of the dump. A three dimensional seepage analysis was carried out to illustrate the influence of groundwater discharge associated with the regional topography and geologic structures. The results of the modelling program show that groundwater discharge occurs from the waste rock dumps when high recharge rates are specified for the surrounding topography- This groundwater discharge strongly influenced by the high hydraulic conductivity assumed far the fractured bedrock. The modelling results are considered preliminary and field drilling and piezometer installation is being conducted to determine the groundwater regime in the vicinity of the waste rock dump.

Jan 1, 2000

By V. Prabhu, D. Mantha, R. Reddy

Secondary copper blast furnace slag was treated with carbon to derive the conditions for maximum recovery of copper with a minimum simultaneous reduction of iron oxide. Experiments were carried out to study the effect of temperature, carbon and CaO additions to the slag on the efficient recovery of copper. A two-stage reduction process was also employed to study the efficiency of copper recovery and the results were compared with those of single-stage reduction. The maximum recovery of copper in alloy phase was obtained with 5 % initial carbon in the slag, 2% CaO addition to the slag and at a reducing temperature of 1573 K. Higher grade of the alloy phase with respect to copper was obtained by employing a two-stage reduction process. The results obtained in this study are comparable to those of the earlier research on the recovery of copper from reverberatory furnace discard slags.

Jan 1, 2004

By Gill G. Geesey, Michael R. Hankins, Paul L. Wichlacz, Anita Gianotto, John G. Jolley, Randy B. Wright

Thin films of copper [2.0 nm on germanium internal reflection elements (IREs) and 3.4 nm on germanium discs] were exposed to 10% gum arabic (aqueous solution) , 2% alginic acid (aqueous solution), 1% bacterial culture supernatant (BCS, simulated seawater solution) and 0.5% Pseudomonas atlantica exopolymer (simulated seawater solution). The IRES were monitored in situ, in real time using fourier transform infrared/cylindrical internal reflection/attenuated total reflection spectroscopy as a function of time at ambient conditions. The discs were characterized (pre- and post-exposure) by X-ray photoelectron and Auger electron spectroscopies. Ancillary graphite furnace atomic absorption spectroscopy was used to monitor the removal process of the copper thin film from the germanium substrates. Results indicate that Cu was oxidized by gum arabic, alginic acid and BCS. Furthermore, Cu was removed from the Cu/Ge interface by all four polymers. The Cu was found associated with the polymer solutions.

Jan 1, 1989

By Conrad G. C. Douglas, Parris A. Lyew-Ayee, Vincent G. Hill

ABSTRACT Distinct patterns are identified in the associations, distributions, and levels of concentration of the silica minerals, boehmite, aluminous goethite, and phosphate minerals in the bauxite deposits of Jamaica. These result from syngenetic and diagenetic reactions associated with post-bauxitization tectonic and associated activities. Three basic types of bauxite are identified, viz., Jamaica-1 (< 3.0% boehmite), Jamaica-2 (> 3.0% boehmite and 30-80% of the iron as aluminous goethites), and Jamaica-3 (> 3.0% boehmite and > 90% of the iron as aluminous goethites). The Jamaica-1 type has a mean value of < 2% boehmite as A1203, while this level in the Jamaica-2 type is usually about 3.5%, and > 4% in the Jamaica-3 type. Similar discrete associations were found for the species and concentrations of aluminous goethite and phosphate minerals. The process and geological implications of these are discussed.

Jan 1, 1984

By G. G. O. O. Uwadiale, M. A. U. Nwoke

The flotation of Azara barite tailings was investigated using crude rubber nut oil (RNOc), refined rubber nut oil (RNOR) and oleic acid as fatty acid collectors. Chemical characterization of the rubber nut oils indicated high acidity, high saponification values and high iodine indexes, which are indicative of a high fatty acid compositions. The Azara barite tailings analyzed 64.6% BaSO4 by atomic absorption spectrophotometry. Gravity and magnetic separation techniques yielded a BaSO4 concentrate with a grade of 74.8% and a recovery of 92.5%. Barium sulfate grades of 90.0%, 92.8% and 94.8% with recoveries of 80.3%, 85.4% and 86.7% were achieved with collector dosages of 750g/t crude rubber nut oils, refined rubber nut oils and oleic acid, respectively. Hence, rubber nut oils are effective fatty acid collectors for the flotation of barite tailings.

Jan 1, 1998

By S. Veeramasuneni, Qingxia Liu, Susan Dichter

Gypsum (CaSO4-2H2O) is an abundant and naturally occurring mineral. Under elevated temperatures (250 to 300°F) gypsum loses its crystalline water and is converted to hemihydrate (CaSO4 -0.5H2O). The hemihydrate form is also called plaster that is widely used in wall- board, joint compound, and many other industrial applications. At temperatures higher than 450°F (up to 1,200°F), gypsum loses all crystalline water and is converted to anhydrite form (CaSO4). The loss of crystalline water at elevated temperatures is an endothermic reaction. This property makes gypsum an attractive filler and fire retardant in certain thermosetting plastics. The applications of gypsum in plastics, food, pharmaceutical, and paper coatings will be reviewed in this paper. The future of synthetic gypsum, a by product of various industrial processes, will also be discussed.

Jan 1, 2003

By P. L. Webster, S. D. Thompson

Sevim and Wang (1988a) have presented a model for designing haulage systems in underground coal mines. The authors contend that their model uses a heuristic algorithm to optimize various haulage system parameters. In reality, it would be nearly impossible to optimize a haulage system, because mining plans are uncertain and often change with respect to time. Therefore, haulage system design poses both a stochastic and a dynamic design problem, and its optimization appears to be well beyond the scope of heuristic algorithms. In regard to the authors&apos; design model and its practical significance, a number of additional issues warrant further discussion and clarification. These issues include: l) their model&apos;s alleged advantage over simulation models, 2) the correctness of their belt network design, 3) the correctness of their bunker design, 4) the necessity of their proposed bunker clearance policies, 5) the correctness of their shaft-bottom bin design, and 6) the

Jan 1, 1991

By Liuming Wu, Willis Forsling

The complexation of Alizarin Red S (ARS) at the surface of hydrous fluorapatite particles has been investigated at 25.0 C by means of potentiometric titrations, adsorption experiments in 0.1 M NaCI ionic medium, and Diffuse Reflectance Infrared Fourier Transform spectroscopy (DRIFT) studies. A chemical model describing the reaction at the aqueous mineral surface has been established under equilibrium conditions according to the reaction [== -CaOH2 + HA2 - « _ =PO CaA2 - z + H30&apos;; to (int.) = -5.61 ± 0.02 3 a =PO- logBs-1110(int.) ( ) within the range 8.40 <_ -log[H ] <_ 9.80.] Experimental data were evaluated using the computer program FITEQL on the basis of a constant capacitance model for the electric double layer. The surface complex structure, has been proposed to involve the quinoid and alpha phenolic oxygens of ARS coordinated to the calcium sites on the fluorapatite surface.

Jan 1, 1993

By Yves Picot

Construction of new installations was recently completed in the Port of Tubarao, Brazil, With this expansion the port, operated by Companhia Vale do Rio Doce (CVRD), has become the largest iron ore port in the world, with an annual throughput capacity of 60 million long tons. GROWTH OR IRON ORE EXPORTS Since its formation CVRD has steadily increased the shipment of iron ore to overseas markets. Starting with less than 100,000 tons in 1942, the yearly export volume grew to 1,500,000 tons in 1951, 5,000,000 tons in 1961 and 25,000,000 tons in 1971. The number of different grades of ore also increased during this period. Production of high grade pellets, starting in 1970, further increased the number of ore products to be shipped. In the same period the size of ore carriers increased twenty-fold to over 250,000 DWT.

Jan 1, 1974