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By Robert C. Merritt

This report describes laboratory as well as pilot heap leaching investigations of low-grade sandstone ores from Wyoming, New Mexico, and Colorado. Sodium carbonate-bicarbonate solutions containing sodium hypochlorite extracted up to 86, 54, and 16 percent U308 from Wyoming, New Mexico, and Colorado ores, respectively. Ammonium carbonate-bicarbonate solutions containing sodium hypochlorite were less effective at leaching these ores. Acid leach in replicate pilot plant testing resulted in U308 extractions of 96, 88, and 81 percent from the Wyoming, New Mexico, and Colorado ores. The development of cost-effective processes for extracting uranium from low-grade ore is essential to the assurance of a continuing domestic supply of uranium.

Jan 1, 1977

Jan 1, 1948

Jan 1, 1948

By L. Harris

The Yanacocha project is the first foreign investment in Peruvian mining since Cuajone during 1976. Three years after the project began, it has become the largest producer of gold from heap-leach operations in the world and the top producer in Latin America. The success of Minera Yanacocha SA (MYSA) opens a new chapter in Peruvian mining with the exploitation of its widely spread gold deposits. And it has attracted the interest of foreign investors in Peru’s mineral resources. Construction began on Aug. 1, 1992. The first gold bar was poured on Aug. 7, 1993 from ore from the Carachugo Mine. During 1993, Minera Yanacocha produced 2.5 t (81,000 oz) of gold and 9.4 t (304,000 oz) during1994 (40% above budget). Production was expected to exceed 15.5 t (500,000oz) during 1995 with the start-up the Maqui Maqui Mine.

Jan 1, 1996

By Edward L. Burwell

The Bureau of Mines conducted laboratory experiments to determine the change during retorting in the apparent permeability and the degree of compaction of beds of broken oil shale. Grades of oil shale studied ranged from 20.6 to 46.7 gallons of oil per ton (gpt), and the simulated overburden pressures applied to the shale were from 300 to 900 psi. Linear regression analysis of the data produced equations describing the response of the oil shale. Oil shales of approximately 20 gpt experience only minor apparent permeability reductions under test conditions, but richer shales (30 to 50 gpt) lose essentially all permeability. The permeability reductions were accompanied by corresponding decreases in bed height that ranged up to 37 percent of the original bed height.

Jan 1, 1974

By A. V. S. Meyer

The Colloquium held at Iscor, Pretoria, on 28th June, 1988, had as its objective the need for Quality Management Systems in the industry. Case studies of how problems were identified and solved by the use of such systems were submitted.

Jan 1, 1988

Why A Friction Hoist? B EFORE discussing the equipment, it would be instructive to review the factors that influenced the management of Opemiska Cop-per Mines to purchase a friction hoist rather than a conventional double drum hoist. The mine required that 250 tons per hour be hoisted from a depth of 2,100 feet. They also specified that the top speed should not exceed 1800 feet per minute. Eight ton capacity skips in balance and a maxi-mum hoisting speed of 1725 feet per minute would meet the required <Output on a duty cycle as follows: Loading time Creep away from loading pocket Accelerate (at 2.5 ft/sec2) 10 seconds 5 seconds 11.5 seconds Full speed run Decelerate (at 2.5 ft/sec2) Creep into dump Cycle time Trips per hour Tons per hour 72 seconds 11.5 seconds 5 seconds 115 seconds 31 31x8 = 248

Jan 1, 1962

By Yotamu Hara, Animesh Jha

"High Curie temperature and large magnetic anisotropy make cobalt an important magnetic material for power engineering applications of magnets operating above ambient. It is also an essential constituent of modem lithium - cobalt oxide batteries, without which modem electronic gadgets will be functionless. Both these applications of cobalt save energy and reduce C02 emission. Ironically, however the production of cobalt from copper and nickel smelting in the world remains one of the least energy efficient process. The paper analyzes the energy balance, material and process chemistry of overall cobalt recovery and the waste generated, which entail the process limitations. We discuss a novel approach for the reduction of sulphide minerals with CaS04, permitting better separation of metals from slag and generating higher concentrations of S02. Such an approach may seem to be an alternative energy efficient option for processing and further purification of cobalt in metallic form. The results are discussed in the context of process thermodynamics and reaction kinetics for Coalloy production.IntroductionCopper sulphides bearing minerals are predominantly associated with iron and cobalt sulphides minerals. Carrollite (CuC02S4) is a mineral that has both copper and cobalt sulphides [1,2], which may also contain FeS, by substituting either Cu2+ or Co2+ ions in mineral lattice. On smelting copper - cobalt - iron sulphide concentrates, some parts of the cobalt often partition to matte at preferentially low oxygen potential by forming eventually an alloy phase with copper, however a significant fraction is often lost into an oxide slag rich in iron and silica. The slag heaps accumulated in the Copperbelt region in Zambia from last 60 years of mineral processing and metal extraction is reported to be 0.3 to 2.6 wt% of cobalt element, which is high [3]. Cobalt is also available in smaller concentrations in the copper smelting and converter slag, as reported in the investigations on the recycling of such slag materials using leaching with ammonium salt [4], iron chloride [5], and sulphuric acid [6], and solvent extraction [7].The recovery of cobalt from slag, irrespective of the techniques researched so far, does not seem energy efficient because the molten slag at 1300°C is quenched by losing thermal and chemical energy. The quenched slag is again reheated to above room temperature for leaching and above liquidus for carbothermic reduction of residual cobalt oxide. For example, in Mintek DC arc smelting [3], 80% of cobalt and 95% nickel are recovered by expending 600 kW per tonne. Assuming that the mineral carrollite is the starting phase, the univariant calculations for the Co-Ca-Si-S-0, Fe-Ca-Si-S-0, and Co-C-Si-S-0 systems are shown in Figure la, lb, and le, respectively at 1573 K."

Jan 1, 2012

By Leonard Obert

This Bur of Mines investigation considers the deformational behavior (creep) of pillars made from three quasi-plastic rocks--salt, trona, and potash ore. The first phase of this study considers the design of a model pillar suitable for creep tests; in the second phase, six model pillars prepared from salt from two sources, from trona, and from potash ore. The pillars in each group were subjected to a different but constant axial stress, and the axial strain was measured for 1,000 hours.

Jan 1, 1965

By E. Chin

Under the seventh 5-year plan (1986-90), the Chinese Government continued to implement reform and to open the country further to the outside world in order to accelerate the growth of its national economy. As a result of expanded foreign economic exchanges and domestic achievements in education, science and technology, and cultural and public health undertakings, the national economy was strengthened. In 1988, there was impressive growth in the Chinese economy. The gross national product (GNP) grew by 11.2070 reaching $373.4 billion; 2 the national income grew by 11.4070 to $310.9 billion. The major problem in the Chinese economy was the imbalance between high demand and insufficient supply. Chronic shortages resulted in price increases and high inflation, which averaged 19% for China as a whole and about 30% in urban areas. Macroeconomic stability took precedence over market-oriented reform initiative. Because of rapidly growing inflation, the Government re-imposed price controls and rationing in major cities in the fall of 1988. China continued to be a major world producer of minerals, metals, and fuels. Output of the principal commodities continued to rise. The largest in-crease in production was salt which rose 24% in output in 1988; followed by sulfuric acid, 14%; cement, 12%; soda ash, 9%; caustic soda, 7%; and steel, 6%. For fossil fuels, the increase in output of natural gas was 14% in 1988; followed by coal, 3%; and crude oil, 2%. The output of electricity by thermal-fired powerplants rose by 9% while that for hydroelectric power-plants rose 7%. Although China&apos;s overall energy output has increased annually since 1980, the growth in demand continued to outstrip the supply.

Jan 1, 1990

By Manuel Pérez-Tello, María M. Salazar-Campoy, Óscar Rodríguez-Hoyos

A common problem during the operation of the Kaldo furnace is the formation of accretions and blockage of the injection lance due to splashing. This typically occurs during the processing of anodic slimes for the production of doré. In this work, a 1:7 scale model of the Kaldo furnace currently in operation at Metalúrgica de Cobre, Mexico, was built in transparent acrylic plastic. Water and colored oil were used to represent the doré and slag, respectively. The model was used to determine the maximum penetration distance of the injection lance under a variety of experimental conditions at room temperature. Input variables included two types of oil, rotation speed, inclination angle, and the fraction of the vessel volume occupied by the liquids (φ). A mathematical correlation for the dimensionless maximum penetration distance of the injection lance d ∗ as a function of φ, the Froude number of the liquids in the vessel (Fr), the Reynolds number of the gas jet (Re), and the oil-to-water kinematic viscosity ratio (η)was developed. Reasonable agreement between the calculated and experimental values was obtained. Digital images showed that splashing was caused by the turbulent gas jet impinging upon the free surface of the liquids, whereas the cascade effect was negligible. The results of this work have been useful to improve the operation of an industrial Kaldo reactor.

By John Freeman

THE die pressing of brass may be described as a method of producing irregularly shaped parts of brass and other copper alloys by hot deformation in a die under pressure. Die pressing of brass was first developed as an improvement on sand castings in order to obtain irregularly shaped articles of brass with superior surfaces, a closer tolerance in dimensions, a denser structure, freedom from porosity and elimination of the relatively large amount of scrap invariably attached to sand castings. The freedom from sandy surfaces with consequent greater tool life in machining operations was also recognized as well as elimination of losses due to the uncovering of blowholes in machining operations. Die pressing also gave alloys of superior strength. Die pressings today are made from extruded rod or shapes, according to design of the part to be made. The greater number of pressings are made from round rod, because of its relatively lower cost and ease of handling. The rod is first sheared or sawed into desired lengths, the diameter of rod used and length of "slug" or "rivet" depending upon ultimate weight and shape of the die-pressed part to be made and design of die. The dimensions of the slug are figured so as to give the, minimum amount of scrap to be sheared from the pressing as it comes from the-die. Extruded shapes having I, T or X sections are often used when the finished part is to have a similar shape or heavy sections are joined by relatively light sections of considerable length. A rod bent in the shape of a U is also used on occasion, for similar reasons. Proper shearing of the slugs is of considerable importance. The sheared ends of the slugs should be as flat and straight as possible. Improperly sheared ends having an angle to the axis of the bar or a rough, uneven surface are liable to give folds or laps in the finished pressing and proportionately high rejections. The property of shearing varies considerably with different alloys and should be considered in the selection of a material for a given part. Where satisfactory shearing is not possible, the slugs may be cut from the bar by power saws. Extruded

Jan 1, 1931

By C. C. Popoff

The growth of the aluminum-smelting industry in the Pacific Northwest, resulting from national defense requirements, emphasized a need for local sources of alumina to supplement the alumina production shipped from the East. Because supplies of foreign bauxite were being interrupted and our domestic bauxite reserves were inadequate, it was necessary to expedite the investigation of other possible sources of alumina during World War II. A program of investigation of high-alumina clay deposits in the Northwest was carried out jointly by the Federal Geological Survey and the Federal Bureau of Mines. As part of this program the Cowlitz clay deposits near Castle Rock, Wash., were explored by the Bureau of Mines in 1942-43. These deposits are near railroads, tide-water, and Bonneville Power Administration lines and within 22 to 100 miles of 4 aluminum-reduction plants.

Jan 1, 1955

By Roger M. Sherman

[Investigation of mine land characteristics, evaluation of irrigation systems, and evaluations by the mining industry, determined that irrigation is a feasible method for aiding revegetation of coal mined lands in western arid and semi-arid regions. The various regions studied displayed a commonality of characteristics which enables, independent of the site or region, the recommendation of solid set irrigation. Irrigation should be supplemental by complimenting natural precipitation and be should implemented on a temporary basis.]

Jan 1, 1980

By S. H. Ash

THE INVESTIGATION of barrier pillars in the Western Middle field is part of the comprehensive study of the mine-water problem in the anthra¬cite region of Pennsylvania by the Federal Bureau of Mines (1, 2, 5, 6, 7, 8,9,10,11,1,2,15,16).8 The Western Middle field is in Schuylkill, Columbia, and Northumberland Counties in eastern Pennsylvania. It has an area of 120 square miles, is 42 miles long from Delano on the east to Trevorton on the west, and is 2 to 5 miles wide. In the Western Middle field are 58 underground water pools containing 38 billion gallons of water (5). Some of the pools overflow to the surface, and the water from others seeps into adjacent mines through permeable barrier pillars separating them from abandoned mines. Several active mines are interconnected to workings in abandoned mines, which are partly filled with water. These mines are separated by barrier pillars that are considered effective only below the altitude of the connections. In some abandoned mines, pumping stations maintain the water at altitudes where the hydrostatic pressure against the barrier pillars is not excessive and does not endanger adjacent active mines. If water in these abandoned mines is allowed to rise to where it can overflow into the active mines, it must be pumped from the active mines at lower altitudes; this materially increases the cost of pumping. It is estimated that from 1944 to 1948 approximately 30 percent of the water pumped to the surface was from abandoned mines.

Jan 1, 1953

Jan 1, 1998

By Robert S. Sanford

The demand for aluminum for military use during World War II called for an expansion of aluminum production in the United States A large part of the bauxite (the normal ore of aluminum) consumed in this county comes from Netherlands Guiana, South America. During the war, enemy activities were at times a serious threat to the flow of bauxite to the United States. The need for aluminum. stimulated the investigation of domestic deposits of bauxite and emphasized the wisdom of studying other aluminous materials, such as high-alumina and diaspore clays, to determine their possible use as aluminum ores. The occurrence in Pennsylvania of high-alumina flint clays and nodular diaspore clays has been known for many years. Several companies are mining these high-alumina, low-iron (less than 3 percent Fe2O3) clays and using them for the manufacture of refractory brick. Most of the production has come from Clearfield County, but clay deposits arc known also in Cambria, Centre, Clarion, Clinton, Indiana, Jefferson, Somerset, and Westmoreland, Counties.

Jan 1, 1949

By Ludwig Schmidt

"IntroductionThe evaporation losses of gasoline in the refinery, can be reduced by proper methods of refinery construction and operation. When gasoline evaporates slowly, as when stored in tanks that are not vapor tight, the most volatile part evaporates first, so that the remaining liquid in not only less in volume, but is also lower in quality. In some,evaporation changes the characteristics of the product so much that it must be reblended to meet trade specifications.Refiners are, therefore, greatly interested in the various appliances and methods used to reduce these losses. In the past this interest has been directed largely to storage tanks, probably because evaporation from tanks is more readily observed than losses during other refinery operations. As tests by the Bureau of Mines on evaporation of gasoline from small storage tanks had indicated that the losses during the various stages of refining might be equal to or greater than those of standing storage, a survey was during the spring and early summer months of 1924 in a large number of refineries in the Mid-Continent field. In order to enable the refiner to select the results of those tests that conform most nearly to the conditions that he has to meet, tests were conducted at various stages of refining, as follows: (1) Randown tanks, (2) (agitators), (3) filling tank cars, (4) storage of refined products, and (3) miscellaneous handling. The results are presented in this paper."

Nov 1, 1925

By Glenn C. Reed

This report is one of a series describing investigations within the Missouri River Basin in Montana made by mining engineers of the Bureau of Mines Minerals Division, Region II. The primary purpose of these investigations is to provide information to agencies of the Department of the Interior and and others concerned with the planning of Federal power developments in the basin. The report contains such factual data as have been authorized for public distribution. The field investigations in Broadwater County were made during the late fall of 1948 and the summer of 1949. Virtually all known metallic mineral deposits and some nonmetallic mineral deposits within the county were investigated. However, some long inactive mines and prospects on which little or no information is of record may have been omitted inadvertently. Many of the mines and prospects have been inactive for extended periods. Most of the underground workings now are inaccessible. Because of such conditions, impressions gained by the inspection of surface features have been supplemented necessarily, where possible, by information obtained from Federal and State publications.

Jan 1, 1951

By Robert R. Perron

The U.S. Bureau of Mines is engaged in many diverse programs for improving mine safety. Of particular interest to the Bureau are new and improved means for minimizing the hazard of fire which can be initiated by prolonged low energy electrical faults on trolley line systems. When a high energy fault occurs on a trolley line, wherein the current exceeds the magnitude normally drawn by legitimate loads, such as locomotives, then the circuit breakers at close-by power rectifier sets trip. Tripping of the breakers not only protects the equipment at the rectifier sets, but also disconnects the energy source from the fault and thereby minimizes the fire risk. However, the fault current is frequently of a level substantially below that required to trip the overload breakers. When the fault is a substantial percentage of the set level of the breakers, the energy dissipated by the fault is frequently sufficient to clear the system by rapidly burning itself clear. Such a fault is often short-lived and does not present as serious a fire risk hazard as a prolonged, much lower energy fault, wherein the energy level is too low to clear the system. The breakdown of a trolley line insulator, in which there was a 20 or 30 ampere leak, would represent such a fault or illegitimate load and a substantial fire risk.

Jan 1, 1974