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By R. J. Andreini

Solvent extraction is widely used in hydrometallurgical processing of uranium for purification and upgrading leach solutions prior to recovery of metal values. Conventional solvent extraction processing utilizes mixer-settler units to achieve mixing of the aqueous and organic phases. Use of mixer-settlers permits continuous treatment of feed, but the processing rate is restricted by the time required for phase separation after mixing. Because of the high-shear type mixing used in a mixer settler a portion of the organic phase becomes mechanically entrained in the aqueous resulting in loss of extractant. For this reason application of mixer-settler units is often limited by the settling area required for phase separation, especially for systems where high volume throughputs are desirable or necessary. Several alternatives to mixer-settler operations involving the use of column extractors have been proposed. Packed columns (1-2), in which organic and aqueous phases are fed countercurrently, utilize packing materials similar to those used in gas absorption or distillation columns. Extraction columns utilizing rotating(3-5) or reciprocating elements(6-7) to achieve mixing have also been developed. Van Dijek(8) originated pulsed columns, in which mechanical or air pulsing of the phases enhances the mixing in the vessel. Each of the above column processes involve varying degrees of mechanical complexity which may lead to operational difficulties.

Jan 1, 1975

By Paul Basinski

The Northern Reese River Valley is in west-central Lander County approximately 31 miles north of Austin, Nevada in the north-central Basin and Range Province (Figure 1). Authigenic zeolites, which were previously undescribed in the literature, are voluminous in this small sedimentary basin. Uranium mineralization is also abundant in this study area. Until now, what we believe to be cause and effect have not been put together. X-ray diffraction, differential thermal analysis, and scanning electron microscopy reveal clinoptilolite, erionite, analcime, and minor chabazite to be present (Figures 2, 3). Assays show uranium to be present in thicknesses up to 0.7 meters at amounts up to 0.10% eU308. The sediments in the Northern Reese River Valley belong to the Mio-Pliocene Humboldt Formation equivalents. This formation consists largely of tuffacious lacustrine and fluviatile sedimentary rocks. Mudstone is the dominant lithology and intercalated thin zeolite strata (usually less than 0.6 meter thick) are present. Zeolites in the Northern Reese River Valley were diagenetically derived from rhyolitic glass deposited in a shallow, saline-alkaline lake under arid to semi-arid conditions. Clinoptilolite from the study area was K-Ar dated at approximately 4.7 + 0.5 million years which corresponds to Middle Pliocene age (Krueger and Basinski, in press). This age is further substantiated by Middle Pliocene mammalian fauna collected in the vicinity by Deffeyes (1).

Jan 1, 1979

By B. G. McNish

Neutron Activator Laboratory Analyzer used for Rapid Analysis for Ore Blending, Stripping, and Mine Control BAUXITE is a rock and not a mineral. Since it is a rock, its mineral content varies depending upon the parent material, the topographic location of the deposit and the severity of the weathering and oxidation processes which produced it. At Bauxite, Arkansas the major mineralogical constituent of the bauxite is gibbsite with ~IL- purities of silica, iron oxide, and titania minerals. Minor amounts of other minerals are found. Chemical composition varies from 45% to 60% alumina, 5% to 25% silica, 1% to 15% ferric oxide, and 1% to 3% titania. The Arkansas bauxite region is located entirely within the north- central area of the West Gulf Coastal Plain near the northwestern boundary with the Interior Highlands. The region trends northeast-southwest and is about 42 kilometers long. It is divided into two districts; one in Saline County and the other in Pulaski County. The Saline District is the most important since it has produced most of the bauxite. This district is located at Bauxite, Arkansas and the deposits are found around the flanks of the Saline Dome. It is roughly square-shaped and is about 190 square kilometers in area. The source rock for the deposits is a Late Cretaceous, grey, nepheline syenite.

Jan 1, 1979

By E. A. Laurila

During last years many different types of X-ray fluorescence analysers have appeared in the market most of these instruments being designed for laboratory use. The instruments applied ins continuous processes are usually modifications of these laboratory types. The application of these instruments to the analysis of heavier elements seems to be quite satisfactory. By lighter elements difficulties are caused by the strong absorption of the characteristic fluorescence radiation, which sometimes makes the use of vacuum or helium chambers necessary. In the following an instrument of another type will be described. It has been developed exclusively for the analysis of titanium in ilmenite concentrate, where the content of Ti02 varies between 43 - 46%. Preliminary measurements have shown that in this interval absolute change of 1% in the Ti02 concentration causes a relative change of about 2% in the intensity. Because: the accuracy of 0.5 % Ti02 is sufficient, 1% relative accuracy should be, attained in intensity measurement. The problem is not very easy to solve due to the fact that Ti K radiation is rather soft and the requirement's for accuracy are rather high. Being applied to the analysis during a continuous process may statistically fluctuating variables in connection of sampling and disturbances of many kind set special requirements for the instrument design.

Jan 1, 1960

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. H. Bassarear, J. D. Vincent

General. Copper, the first metal used by man, today is the third in consumption after iron and aluminum. Compared to these it is relatively rare, with less than 0.01% of the earth's crust copper, 8% aluminum, and 5% iron. Nevertheless. our modern civilization is heavily dependent upon copper because of its high conductivity and resistance to corrosion, ease of working, durability, wide range of properties by virtue of its readiness to form alloys with other metals, and its attractive colors and texture that make it so desirable for many crafts and arts. These attributes explain why copper is chosen for a long list of uses, including electrical wiring, switchgear, and bus bars; piping, roofing, and siding; and manufactures of brass, bronze, and other alloys. The fact that copper ore is mined in nearly all parts of the world is significant. Its importance is shown in Table I, which gives figures on world production from 1968 to 1977. In the Free World, North and South America and Africa are preeminent. The table also shows the generally upward trend of production in this period; accurate figures for 1978 and 1979 from the same source are not yet available (1980), but it is certain that major environmental, economical, and political factors continued to disturb the industry in those years and into 1980.

Jan 1, 1985

By A. Subbotin

During developing the Ingulska mine at the Mi-churinske uranium deposit in the central part of Ukraine the radioactive rock dumps have been piled. A height of dumps reaches to 15-25m. They occupy a large territory and can be a source of covering with radioactive dust the area around the Ingulska mine. Uranium content exceeds 0,01% in all dump rocks samples while in the dust fraction samples it ranges from 0,01 to 0,06%. Uranium content in road dust at the dump?s foot reaches 0,137%. A new (for Ukraine) method of f-radiography of tree and bush leaves sampled at the territory about 100km2 has been used. It is based on fission of 235U nucleuses due to heat neutron influence in a nuclear reactor and on following study of the Lausan films with tracks drawn by the fractures of these nucleuses. Uranium content of the dif-fusion-disseminated dust type is (0.9-22.2)?10-6% while in the individual particles it can be considered much more because of burned holes in Lavsan above them. The dust content with uranium in Kirovograd reaches to 20-50 part/cm2 while near the dumps it ranges from 100 part/cm2 to 300 part/cm2 in the radius of 1,5-2km from the Ingulska mine.

Jan 1, 2005

By G. J. Hartman

The Fort Cady in situ borate mining project involves recovery of boron from a mineral deposit located over 1400 feet below the surface. The resource recovery method is being developed using in situ mining technology employing weak acid solution injected directly into the ore body. As the acid contacts the calcium based ore (primarily natural colemanite), the contained borate values are digested as boric acid. This boric acid solution is then pumped to the surface by use of submersible pumps. At the surface the borate values are recovered as a finely divided solid white powder after a series of chemical reactions and precipitations resulting in the production of calcium borate. The refined product is then sold under the trade name CADYCAL 100.TM All environmental permits for up to a production rate of 90,000 tons per year have been obtained. These permits required an Environmental Impact study (EIS) for federal lands and an Environmental Impact Report (EIR) for the private portion of the property. Regulatory permitting required over 5 years to obtain all the various authorizations for this project. The ore body has an average thickness of 118 feet extending over 273 acres. At a production rate of 90,000 tons per year with only a 70 percent resource recovery allowance, in place reserves are sufficient to sustain production for over one hundred years.

Jan 1, 1997

By C. E. McFarland, N. W. Kirshenbaum

Cortez Gold Mines is located about 75 miles southwest of Elko, NV. Activity in the mining district dates from 1862. The current operation developed from a 1963 joint venture of Webb Resources, The Bunker Hill Company, Vernon F. Taylor, Jr., and American Exploration & Mining Co. Three years later, the USGS discovered gold on the property following a regional geochemical survey. Drilling in 1966 and 1967 identified 3.4 million st of oxide ore grading 0.28 oz Au/st, and a 1700 st/day countercurrent decantation mill was commissioned in 1969. Heap leaching started in 1971 on low grade ore and continues to the present. The mill was shut down in 1976 following exhaustion of known oxide reserves. Mobile equipment was sold and the proceeds committed to local exploration. In 1980, a new plan of operations was developed starting with existing low grade and newly discovered mill ore. The mill resumed operations in 1981 and has been operating to date. A series of metallurgical innovations, culminating in the commissioning of a new fluid bed roaster in the summer of 1990, has enabled treatment of a series of increasingly refractory ores. Current partners in the venture are Kennecott Corporation, Vernon F. Taylor, Jr., and Placer Dome U.S. Inc., manager of the operation. Idaho Mining Corp. holds a 7.5% carried interest.

Jan 1, 1992

By Judith A. Marks, Deane K. Smith, Jan M. Mutmansky, Maria Klimkiewicz

The mechanical mining of coal seams where roof, partings, and floor rock are extracted along with the coal often introduces large numbers of quartz particles into the mine atmosphere. This study concentrates on the quartz properties in situ and in the airborne dust to determine how they are released from the source rock and whether they are fractured by the mining machinery. Three mines using drum-type continuous miners from different geographic areas were sampled to provide a data base. The roof and floor rocks were primarily siltstones containing 5% to 25% quartz measured by the X-ray powder diffraction (XRPD) method. Much of the work presented here is based on the morphologies of the mineral grains determined by the scanning electron microscope (SEM). The study concentrated on particles of 0.2 to 10.0 µm and on particles containing > 75% Si. Mechanically-crushed quartz particles were also examined for comparison purposes. Particle shapes from the airborne samples suggested that fractured quartz particles were rare. Particle statistics also show that the average size of quartz particles in the airborne samples were similar to the average size of all particles. The conclusion is that very few quartz particles from the source rocks are fractured during mining due to their small initial size and the protection of the associated clays.

Jan 1, 1991

By Eric R. Braun

Ore reserves in the Republic mining district were nearly exhausted in 1984 when hole D-54 intersected a vein twenty- eight feet in drill width averaging 1.57 opt gold and 11.95 opt silver below post-mineral lake beds. The discovery area, termed "Golden Promise", has announced proven and probable ore reserves of approximately 372,000 tons averaging 1.0 opt gold and 4.5 opt silver, and drilling indicates another 756,000 tons of mineralized material containing 0.37 opt gold and 1.4 opt silver (Hecla fourth quarter 1986 report). This paper describes new geological interpretations made as part of a district research study sponsored by Hecla Mining Co., which led to the D-54 discovery. Important new geological concepts include: 1) re-interpretation of the volcanic stratigraphy of the district and recognition of a suite of pyroclastic rocks that are unique to the Republic graben, 2) identification of disseminated subaerial mineralization at a paleosurface that corresponds to the newly described upper contact of the Sanpoil Volcanics, 3) recognition that epithermal veins have a maximum productive vertical range of 0-500 meters, measured from the paleosurface, and 4) veins exhibit visual and geochemical vertical zoning within the productive zone with highest gold occurring at an optimal depth, which is interpreted as the average depth of hydrothermal boiling.

Jan 1, 1987

By Yuuichi Umeki, Yuusaku Tominaga

In order to keep good air condition in any specific branch such as coal face and/or heading in an underground coal mine, effective factors of all the branches with respect to the specified branch have been investigated, using computer simulation. Main results of the paper are as follows; 1) A branch in a network is classified to one of three classes of effectiveness to increase, to decrease and not to change airflow rate in the specific branch by altering aerodynamic resistance in the branch. 2) Distribution of position of branches, belonging to each class, related to a specific branch is one of the macroscopic characteristic of a network which is the inherent property of every network. 3) A relation of the aerodynamic resistances of any two branches to keep a constant airflow rate in the specified branch is shown as a monotonous curve. 4) Ventilation transition diagram with the rate of airflow in the two branches as coordinates, and for different rates of airflow in the specific branch as the parameter, is found to be straight lines. 5) Existing range of airflow rates In the specified branch is given as a parameter in the enclosed area in the ventilation transition diagram. Moreover, an expert system to assist ventilation control using a transition diagram of airflow rate is introduced in this paper.

Jan 1, 1991

By Harry M. Edenborn, Richard W. Hammack

Experiments were done to determine if a mushroom compost-based sulfate reduction system could be used to treat nickel-contaminated mine waters. Sulfate reduction systems were established in columns containing acid-washed mushroom compost. Simulated mine waters containing 2000 mg/L sulfate and 50 to 1000 mg/L nickel were adjusted to pH 4.5 and pumped through the columns at flow rates between 15 and 25 mL/hr. During the first nine days of operation, virtually all influent nickel was removed in the columns by sorption and ion exchange mechanisms. The nickel removal rate then dropped to 18 to 30 mg Ni/day (7.8 to 12.8 nmol/ g-substrate/day), probably due to low sulfate reduction rates. When sodium lactate was added to the inflow, a sustained and seven-fold increase in the nickel removal rate was observed. Bacterial sulfate reduction rates measured in mushroom compost-based wetlands exposed to coal mine drainage are 2 to 20 times faster than the rates observed in this study. Low sulfate reduction rates in the columns may have been due to the inhibition of microbial activity by high nickel concentrations and the removal of labile organic compounds from the mushroom compost substrate during acid-washing. Results of this study indicate that bacterial sulfate reduction can effectively treat nickel concentrations up to 500 mg/L if labile carbon is nonlimiting.

Jan 1, 1992

By Joel Nonnweiler, Galen Samuelson Nagle

The Sacramento Regional County Sanitation District (SRCSD) has undertaken an interceptor expansion program to meet future wastewater needs associated with projected growth over the next 20 years. The Lower Northwest Interceptor (LNWI) will include over 17 miles (27 kilometers) of pipeline including 14 miles (23 kilometers) of dual force main ranging in size from 54- to 60-inch (137- to 152-centimeter) diameter and 3 miles (5 kilometers) of 120-inch (305-centimeter) diameter gravity pipeline. The estimated capital cost for the program is $331 million, with approximately $236 million in construction cost (as of November 2002). The project includes 4,700 feet (1,433meters) of tunnel including 2 crossings of the Sacramento River and one crossing of the Barge Canal, and 11 other smaller tunnel crossings beneath various creeks, sloughs, highways, and railroads. Preliminary design of the tunnels for the LNWI are discussed in this paper. The overall purpose of the preliminary design was to sufficiently define the project to allow planning level cost and schedule estimates to be performed. There have been changes to the project during final design including pipe sizes and configurations, tunnel and pipeline lengths and anticipated flows. This paper addresses only the preliminary design of the LNWI tunnels. Final design issues and changes made since completion of preliminary design are not addressed in this paper.

Jan 1, 2003

By G. J. Hartman

The Fort Cady in situ borate mining project involves recovery of boron from a mineral deposit located over 1400 feet below the surface. The resource recovery method is being developed using in situ mining technology employing weak acid solution injected directly into the ore body. As the acid contacts the calcium based ore (primarily natural colemanite), the contained borate values are digested as boric acid. This boric acid solution is then pumped to the surface by use of submersible pumps. At the surface the borate values are recovered as a finely divided solid white powder after a series of chemical reactions and precipitations resulting in the production of calcium borate. The refined product is then sold under the trade name CADYCAL 100.TM All environmental permits for up to a production rate of 90,000 tons per year have now been obtained. These permits required an Environmental Impact Study (EIS) for federal lands and an Environmental Impact Report (EIR) for the private portion of the property. Regulatory permitting took over 5 years to obtain all authorizations for this operation. The ore body has an average thickness of 118 feet extending over 273 acres. At a production rate of 90,000 tons per year with only a 70 percent resource recovery allowance, in place reserves are sufficient to sustain production for over one hundred years.

Jan 1, 1997

By L. G. Wilson

In our comparison of California and Turkish colemanites, we should first place the discussion in context. In order to exclude technical considerations, which are not germane to this paper, we must make the manifest and basic observation that if colemanite were not acceptable for the production of glass products it would not be used, and we would not be interested in this comparison at all. Suffice it to say that the colemanites, being calcium borates, provide a necessary flux in glass manu¬facture, together with the requisite degree of physical strength and chemical durability which can be achieved only by the use in glass of a. flux substanti¬ally free from alkali; so the sodium borates are automatically excluded from the production of textile fibers. Thus we have today under consideration only California colemanite, Turkish cole mite, and, because it provides a degree of competition to both, ABA, or anhy¬drous boric acid, which, although it is a refined intermediate and of much higher cost, it is also of a much higher degree of purity, and its characteristics can easily be modified to produce a desired end product, so we must include it in any consideration of high quality borates. [Calcim Borate Pentahydrate] Colemanite is a [calcium pentahydrate,] with the formula Ca2B6011.5H20. It has a theoretical B203 content of 50.8%.

Jan 1, 1973

Energy Developments Ltd. (EDL) has developed power plants at two Australian coal mines that featuring 94 gas-fueled Caterpillar G3516 engine/generator sets. They will convert to electricity 145 kt/a (160,000 stpy) of coal-seam methane gas for sale to a local utility. The $100-million project will cut the sites' methane emissions in half, provide a low-cost energy source and offset mine operating costs. The project began in May 1995. It is located at the Appin and Tower longwall underground mines, 80 km (50 miles) south of Sydney in New South Wales. The installation is one of the first to capture coal-seam gas from mine ventilation air and gas drainage systems. Coal- seam gas contains 40% to 60% methane, which fluctuates constantly. The system is expected to convert 578,000 m3/d (20.4 million cu ft/d) of coal-seam gas to 94 MW. It will also reduce greenhouse gas emissions by 3.5 Mt/a (3.8 million stpy) of CO, equivalent emissions. The Appin and Tower mines each produce 2 Mtla (2.2 million stpy) of clean coking coal. They operate around the clock with about 400 workers per site. The mines are owned by BHP Steel, Collieries Division, which will share the revenues from energy sales. The Appin Power Partnership consists of EDL and Lend Lease Development Corp.

Jan 1, 1997

By R. W. Seedsman

Mandalong Mine was originally planned to operate with panel widths of 250 m and a predicted surface subsidence in excess of 3 m. The consent conditions applied by the NSW government on this mine plan were very tight and, following a change in ownership, were considered by the new operator to present a number of unacceptable business risks An acceptable risk profile for the mine layout restricted surface deformations to less than 500 mm vertical subsidence, less than 7 mm/m tilt, and less than 5 mm/m strain. Empirical subsidence prediction methods indicated that it would be necessary to reduce extraction panel widths of 80 m - an uneconomic option. The application of a number of rock mechanics concepts identified that the local overburden geology could be exploited such that panel widths of up to 175 m could be possible. The 125 m width was selected as a low-risk introduction of this new subsidence prediction method. The extraction of the first 2 longwall panels has demonstrated the validity of the prediction subsidence method and has provided the opportunity to refine the selection of key input parameters. The impact of mining through a zone of thrust faults was successfully predicted. The mine is now planning the introduction of 160 m wide panels, and will review the associated subsidence impacts prior to any further increases in width.

Jan 1, 2006

By David M. Sullivan

Jim Walter Resources, Inc., (JWR) a division of Jim Walter Corporation, has 5 underground coal mines in Central Alabama varying in depths from 400-2500 feet. Gas Chromatography plays a vital role in safety and production at each mine. Chromatographic data is used to monitor working areas for safety and proper ventilation and to control the quality of extracted methane for sales purposes. Instruments have a1 so been employed during mine rescue operations. JWR's first Gas Chromatograph (GC) was installed in April 1984 to monitor gob gas taken from longwall gob areas and sold based upon BTU value. The GC allows maximum extraction rate of the gas within the quality guidelines. By late 1985, another system was purchased and both units were upgraded to perform an analysis of indicator gases which may appear during mine emergencies. Each unit has the ability to detect and measure the following gases at almost any level ; Oxygen (021, Nitrogen (N2), Methane (CH4), Carbon Dioxide (C02), Hydrogen (HZ), Carbon Monoxide (CO) , Ethylene (C2H4), Ethane (C2H61, Acetylene (C2H2) and a composite of hydrocarbon threes and above (C3+). The analytical run is accomplished in less than ten minutes and is completely automated. This report will introduce Gas Chromatography as applied by Jim Walter Resources for the analysis of underground mine air.

Jan 1, 1987

By S. A. K. Forson, Newton A. Amegbey

In order to investigate production decline in Tarkwa Goldfields Ltd., located in a tropical rain forest, amongst other areas, a health survey was conducted with the aim to see 1. The health status of the workers. 2. Which parameters carry the most information about the health situation and which of them can be applied easily during screening programmes. 3. What steps could be taken to improve the situation. In all 249 workers were investigated. A non-invasive method involving taking of body weight and arterial blood pressure was used. All subjects were required to answer a questionaire. Emphasis was placed on the history of malaria and diarrhoea within the last six months. Both management and workers co-operated fully. Another set of 110 workers from a neighbouring tyre factory were also investigated for control. Among the underground workers, the percentage body weight loss during a shift increased with decreasing body weight. Dehydration levels could be as much as 4 to 5% of body weight. This could be attributed to the fact that workers took insufficient or no water during the shift. The health status of the mine workers was generally poor and in our opinion malnutrition combined with malaria severely threatens the health and well-being of the workers. Hypertension is also a problem. An improvement in production is intimately linked with the well-being of the workers.

Jan 1, 1989