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By K. N. Han

The leaching behavior of palladium in ammoniacal solutions was investigated by using the rotating-disk technique in an autoclave. The study included the effects of rotation speed, temperature, oxygen pressure, composition of ammoniacal solutions and catalysts on the overall leaching rate. The dissolution of palladium in ammoniacal solutions was discussed in terms of the thermodynamics and a kinetic model. Even though the Eh-pH diagram suggests that palladium metal can dissolve in ammoniacal solutions at room temperature, it was found that the dissolution was very slow at temperatures below 100 °C but was significantly improved at higher temperatures. It was also found that the rotating speed of the palladium disk had no effect on the leaching rate. The apparent activation energy was found to he 69.7 kJ/mole. Based on the results obtained, it was concluded that the dissolution of palladium is controlled by chemical reaction.

Jan 1, 1999

By Håkan Stille, Jalaeddin Y. Rafi, Fredrik Johansson

"INTRODUCTIONIn tunneling projects, pre-grouting is performed with the purpose of establishing an impervious zone around the tunnel periphery. This is obtained by reducing the penetrability of the most conductive fractures in the rock mass. The main attention, besides economy of the project, is given to limiting the ingress of water into the tunnel to a certain amount during construction s well as operation period. Failure in pre-grouting process may, according to Bruce (2007), significantly affect the project in terms of safety, performance, cost and time. In this respect, determination of design parameters (pumping pressure, properties of the mix and stop criteria) affects these projects significantly. In current practices, depends on the geological conditions and requirements of the project these parameters differ widely. Weaver (1991) recommends selection of design parameters, specifically grout injection pressures, based on site specific factors and the conditions at each specific hole into which grout is to be injected (grout hole logging and water pressure test data). Houlsby (1990) correlated the allowable grouting pressure to the quality of the rock mass and the rock cover above the grouted fracture. In his methodology, grouting should be continued until the maximum pressure was attained. Later, Lombardi and Deere (1993) introduced the Grout Intensity Number (GIN), which limits the combination of injection pressure and injected grout volume in order to control the energy induced in the fracture i.e. avoid fracture jacking. Even though the GIN method was a step forward in understanding of the mechanism of the fracture deformation, there are ambiguities connected to this methodology, thus determination of the intensity number is challenging (see e.g., Rafi and Stille 2015)a.A main problem when no theoretical solution is practiced is that effects from the chosen injection pressure, such as possible increases of transmissivity and changes in total grouting time, remains hidden in the overall grouting process. The question is if a high or a low pressure should be used to fulfil the requirements of the projects at the lowest possible cost."

Jan 1, 2016

By J. S. Whatley

The properties, origin and industrial uses of kaolin clay are briefly reviewed. The general waterwashed beneficiation process is described. Yost aspects of filtration and solids-liquid separation as practiced in the kaolin industry are mentioned along with devices that are currently in the developmental stage. The paper focuses heavily on the well known art of rotary vacuum filtration, including general construction and operating details. Devices under investigation that might be used to mechanically or electrically dewater clay slurries to higher cake solids levels than can be achieved with rotary vacuum filters are described briefly.

Jan 1, 1986

By Vincent Tricot, Daniel Altier, Roger Storry

"INTRODUCTION The Liantang / Heung Yuen Wai Boundary Control Point (BCP) project, located in the north-east New Territories of Hong Kong, will form the seventh land crossing between the Hong Kong Special Administrative Region (HK) and Shenzhen in China (Figure 1). The BCP project comprises an 11km long dual two-lane trunk road linking the border crossing facility to the existing road infrastructure in HK and when completed it will facilitate future regional development and alleviate frequent traffic congestion at the existing Boarder control points.In December 2013 Dragages Hong Kong (a member of the Bouygues Construction Group) was awarded the 5.4km long Contract 2 section of the project, including the 4.8km long Lung Shan Tunnels, by the Civil Engineering and Development Department of the Government of the HK SAR. To overcome the difficult ground conditions anticipated along the Contract 2 section of the project the tunnels will be constructed using mechanical and drill and blast (D&B) excavation techniques together with a 14.1m diameter multi-mode Earth Pressure Balance Tunnel Boring Machine (TBM). Land constraints imposed on the project alignment require that the final 500m section at the northern end of the Lung Shan tunnels, under Princess Hill (Figure 2), takes an almost 90 degree turn towards the north. The resulting 354m radius curve restricts the sight-line of road users to below the minimum 110m at 80km/hr hence, the internal span of the tunnels needs to be increased from 12.6m, in the standard straight section, to 15.4m in this curved section to accommodate a widened shoulder which will provide the required sight-line distance."

Jan 1, 2016

By W. G. Prast

Best known for its extensive bauxite and alumina exports, Jamaica also has a small but active industrial minerals sector. The island has for many years been a net exporter of small tonnages of gypsum, metallurgical-grade limestone and marble products. As bauxite and alumina earnings have declined the government of Jamaica has made extra efforts to promote growth of overseas sales of these nonmetallics. The nearby U.S. market is a natural first choice for new exports. Overview In 1984, Jamaica quarried an estimated 3.2 million cu m of marble and fill and an additional 3.5 million cu m of sand and gravel, for use in domestic construction. These amounts are in line with the production in earlier years of the 1980s but are not a factor in the export pattern and need not be considered further. Similarly, annual production of 15 million ton of silica sand for the manufacture of glass bottles is principally consumed by the domestic market.

Jan 1, 1986

By B. J. Arnold, F. F. Aplan

A model incorporating rate and residence time to describe the froth flotation process was used to provide data for the evaluation of various kinetic flotation models and to provide scale-up information from laboratory to industrial scale coal froth flotation. Rate constants were determined in laboratory and plant froth flotation tests and the residence time distribution was measured for a bank of four 21 ft 3 (0.6 m3 ) WEMCO cells treating Upper Freeport seam coal and a bank of four 300 ft 3 (8.5 m3 ) cells treating Lower Kittanning seam coal. It was found that a lag time for continuous flotation should be incorporated into scale up models and that a kinetic froth factor ratio of between about 2.0 and 2.8 should also be used to scale up data from laboratory to plant scale.

Jan 1, 1989

By D. Symonds, A. J. Richins, M. G. Nelson

Mining activities at Kennecott and Park City are similar in that both districts began operation in the last half of the 18th century, and both operated on a large scale for many years. However, they are different for two important reasons. First, the mines in the Park City district were always underground. The city of Park City was above many of those mine workings. It remained in place after mining activity stopped, and as the town became an up-scale ski resort, property values increased and the tailings dumps became desirable building sites. In contrast, Kennecott eventually became an open pit mine, and the growing pit effectively consumed many of the small towns that had grown up around the underground workings. Even towns on the periphery of the open pit were razed to allow for the disposal of mine overburden. Second, almost all mining activity stopped in Park City in the early 1970s, just as the first rigorous environmental legislation in the United States was enacted. (The Ontario mine operated sporadically until 1982.) Many mine structures, waste dumps, tailings ponds and piles, and tunnels were simply abandoned as the mining companies ceased business or were bought out. Kennecott, on the other hand, has been in continuous operation for more than 120 years, so a closure plan hasn’t been finalized. Nonetheless, environmental and social problems have arisen, and the company has had to address them.

Mar 2, 2022

By Joseph W. Siefke

The Kramer borate deposit is located in the western Mojave Desert at Boron, California, about 100 miles northeast of Los Angeles (Figure 1). The deposit derives its name from the district in which it lies. Borax (Na2 B407.10H2O) is being mined from the Boron open pit to serve a major portion of the United States and world borate markets. This paper deals primarily with those geologic factors which affect slope stability in the overburden at the Boron open pit. Discussion includes slope failure history, slope monitoring techniques and the results of a dipmeter survey of overburden structure. Open pit mining was begun at Boron in 1957. The initial pit was successfully excavated at the recommended 1.5:1 (horizontal to vertical) slope in the overburden. During pit expansion in 1962, excavation of the overburden exposed beds dipping into the pit at +15 degrees and numerous high angle fractures associated with two intersecting fracture systems, the West Jenifer and Portal fault zones. Ensuing south and east wall failures indicated the need for more structural information in the arkose to establish better wall design criteria. Barnard and Kistler (1963) recognized that the many facies changes, faults and other variables in the Boron overburden make it extremely difficult to reduce prediction of slides to a simple arithmetical formula. Despite the difficulties and uncertain¬ties, special programs such as surface resistivity, refraction seismic and core drilling were conducted in an attempt to predict slope stability conditions and to gather geologic information. These early efforts while helpful, did not provide the necessary details of bedding orientations and fault locations which are of paramount importance in our slope stability program. A dipmeter survey in 1974 successfully measured these variables and data from that survey are instrumental in the design of slopes currently being excavated.

Jan 1, 1976

By S. -Y. Hwang

An ongoing problem for industry in Korea is effective removal of heavy metals from and safe disposal of spent power plant fly ash. This research endeavor attempts to develop selective separation of Ni from leach liquor using a selective chemical precipitation method. The research was conducted by changing two variables, the pH and the concentration of ions in solution. The effect of other ions present in the system on the separation efficiency of Ni species was also investigated by adjusting OH and NH3 concentrations. In the pH range of 7-9, the chemical precipitation method produced a high yield of Ni by precipitation from the fly ash leach liquor.

Jan 1, 2010

By Xin Wang, He Shao, Wenpu Li, Yiyi Zheng, Xi Chen, Yurong Gao

This study utilized experimental and numerical simulation methods to investigate and analyze the atomization characteristics of three internal air–water mixed atomizers under different operating conditions. By comparing the research results, the effective dust control working parameters for the application of the selected atomizer in the engineering field were determined. Firstly, the atomization characteristics of the three atomizers were studied using a customized experimental system. The results indicated that nozzle 2 had a wide atomization range, a small atomization distance, and small droplet size; nozzle 3 had a narrow atomization range, large droplet size, and fast atomization speed; and nozzle 1 not only had a large atomization range but also could produce droplets of dry mist size with fast atomization speed, meeting the dust reduction requirements of the Majiliang Coal Preparation Plant. Secondly, Fluent software was used to simulate the atomization process and particle size distribution of the three internal mixed atomizers, determining the working conditions of the atomizers, the required number of atomizers, and the application angle of the atomizers in the internal mixed dust removal system. Finally, the atomized dust control system was applied on-site, achieving a total dust removal efficiency of 90.72% and a respirable dust removal efficiency of 89.75%.

Mar 9, 2024

By Donald G. Oss

The need for instrumentation and automatic control of the various parameters in the heavy media process of iron ore beneficiation has been apparent for some time. Continued demands for higher grade, competitive products from the Mesabi Range have made it necessary to increase the efficiency of the process in every possible way. A brief review of a typical heavy media flow scheme, as illustrated in. Figure l, might be in order for those not intimately associated with this process of iron ore beneficiation.

Jan 1, 1962

By James R. Dunn

The mineral industry" has made and will continue to make important contributions to the growth of our economy. However, the industry is presently under continuous and increasingly severe attacks by organizations and individuals interested in the preservation of our environment. Yet neither the public interest value of preservation nor the public interest value of our mineral industry is known. In the absence of such values, judgments about best land use where minerals are involved are nearly always made on emotional grounds. An example of the sort of problem that has been created is in the New York Metropolitan Area. Because of institutionally-created shortages stemming largely from zoning decisions and building over deposits, the effective cost of fine aggregate delivered at dockside at Manhattan rose from $2. 65/cubic yard in July, 1969, to $4.10/cubic yard in May, 1970, this in spite of approximately ;l0,000 years of reserves on Long Island. The cost of fine aggregate for New York City alone has "Increased over $S million annually within one year, with the cost increase for the Tri-State Metropolitan Area (coastal Connecticut, New Jersey, and New York)" exceeding $10 million annually. The ab0ve situation has created a cost increase which is clearly the result of non-conservation of a mineral resource. That is, in readily measurable values, it Is costing the public about $10 million per year because good conservation practices were ignored-a public-interest loss. Admittedly, this is not the whole story because the public is simultaneously obtaining other values from the land surface that would otherwise have had to be dedicated, temporarily to be sure, to mineral recovery-a public-interest gain. However, the point is that we do not know where the balance lies-the net public interest value; it may lie one way for deposits zoned out of existence by a growing suburb, another for areas designed as permanent greenbelts, and still another for areas under new highways

Jan 1, 1971

By K. A. Foo

Minproc Resources Inc. is developing a tailings retreatment project in Bolivia at the Colquiri zinc-tin-silver mine, in the Bolivian Andes. Mining at Colquiri has been continuous since 1940 and COMIBOL, the Bolivian state mining company, has owned and operated the underground mine since 1964. There are 10 million tonnes of tailings at Colquiri containing 0.51% Sn, 4.21% Zn and 50 g/t Ag. Minproc plans to mine and concentrate the tailings at 1.15 million tonnes per year to produce feed for pyrometallurgical upgrading. The tailings are moderately complex, with cassiterite grain size ranging from 200 to 5 pm. The marmatite (ZnFeS) in the tailings is relatively easily recovered, with zinc recovery of 80% to a 40%-45% Zn concentrate. The major problem with the zinc metallurgy is that the marmatite is complexed with iron, which results in iron contents of 14%-17% Fe in concentrate. This makes the product very difficult to sell because of the low Zn:Fe ratio. Most zinc smelters require a Zn:Fe ratio of 6:1 or 7:1, whereas this concentrate has a 3:1 ratio. Concentrate sale terms are therefore unfavorable, and the high cost of transportation from Bolivia to the smelters is an additional burden.

Jan 1, 1992

By Harold F. Yde

Hydraulic tailings fill in the Butte deep level mines was based upon studies made in 1958 by the Anaconda Company Mining Research Department, which published Bulletin No. 35, entitled "Hydraulic Stope Filling". Since then, many things have changed. At the time of the Research Departments study, dry mine tailings were hauled by rail cars from the Anaconda tailings ponds, twenty-five miles distant, to the underground mines' tailings fill plants at the Leonard Anselmo, and Mt. Con Mines. Now, with the installation of the new Weed Concentrator in Butte, tailings is delivered by pipeline to a cyclone at the Kelley Shaft, and stope filling has become more highly automated and streamlined. Presently, mill tailings at approximately thirty percent solids by weight, is pumped from the concentrator, eight thousand feet horizontally and upward, to the Kelley Fill Plant, where they are dewatered and deslimed by three Krebs Model D20B Cyclones, which discharge the material into the cased and grouted mine delivery bore holes at desired densities up to seventy percent solids. The vertical boreholes and four-inch rubber lined Victaulic pipe carry the material downward to horizontal distribution lines, which in turn tap into the stops-filling, three inch, unlined steel Victaulic pipelines. The slurry may travel several thousand feet before it finally discharges into the stope, where it lends support to the mined-out area.

Jan 1, 1969

By Leif A. Nordell, Philip E. Freeland

A paper discussing specification, methods, situations and results encountered in underground phase construction of the Rocky Mountain Pumped Storage Project near Rome, Georgia. The scope of work included excavation, rockbolt/shotcrete/wire mesh primary support and cast-in-place concrete lining of the (1) 216 m, top flared shaft, connecting 1.57 radian elbow, and 590 m tunnel to a 10.67 m finished diameter; (2) complex double bifurcation section; (3) excavation, support, installation and backfill concrete for three parallel, 135 m steel penstocks of 5.79 m finished diameter; (4) construction of a 43 m diameter reinforced concrete intake/discharge structure atop the shaft.

Jan 1, 1985

By W. S. Sanner

Experiments were conducted to determine the quantity and purity of ultraclean anthracite that could be prepared in the laboratory, using conventional separating techniques. A low-, a medium-, and a high-volatile anthracite were studied. Specific gravity separation followed by grinding, screening, and refloating at lighter specific gravities yielded small quantities of material purified to 1.0 percent ash, as follows: From low-volatile anthracite, 0.7 percent; from medium-volatile coal, 1.0 percent; and from high-volatile coal, 2.3 percent. The reduction in ash had no appreciable effect on the volatile matter or sulfur content of the coal. The limited quantities of material containing 1.0 percent or less ash obtainable indicate that if ultraclean coal is desired, a practical approach should include the processing units as an integral part of a conventional dense-media washing plant.

Jan 1, 1968

By Lars Lövgren, Jörgen Jönsson

Heavy metals may be retained within deposits of sulfide minerals under oxidation and in the nearest recipients of drainage water by sorption to secondary iron precipitates. The extent of sorption is strongly influenced by solution pH and presence of complexing ligands, such as sulfate and natural organic acids. Desorption of metals and organidinorganic anions to recent secondary Fe precipitates, collected at the Kristineberg mine, Sweden, has been investigated under different geochemical conditions. Elemental composition and structural characterization (X-ray powder diffraction) indicate presence of schwertmannite. While metals such as Ni and Pb were fractionally desorbed from the precipitates under acidic conditions, oxyanions, e.g. arsenatdarsenite and sulfate were desorbed preferably under alkaline conditions. In a separate study the adsorption of NOM onto synthetic goethite was investigated. NOM adsorption showed a strong pH dependence, 95% was adsorbed at pH 3 and 40 % was adsorbed at pH 9. Addition of 2 mM of sulfate desorbed about 10 % of the adsorbed NOM.

Jan 1, 2000

By R. Pinksen

The IOC Mining and Operations Departments expressed an interest in reducing the amount of oversize material (>1.0 m x 1.0 m x 1.0 m; 39 inches x 39 inches x 39 inches) being produced and its subsequent downstream effects including in-pit sorting and reduction, damage to mobile equipment, and significant delays in the loading pockets and the primary crushers. To achieve this goal an oversize reduction project was undertaken by the mine and to date has significantly improved upon baseline measures. One key approach used to reduce the amount of oversize was the implementation of thicker emulsion. The introduction of a thicker emulsion provided more resistance to the forces created by dynamic water and reduces the infiltration of the emulsion into the cracks and fissures of the rockmass. Reduced amounts of oversize and more consistent fragmentation throughout the muckpiles has been a result. Additionally, a significant reduction in nitrates leached into the mine water discharge has been realized. To determine the effectiveness of the oversize reduction project, IOC used a of first-of-kind technology to assess fragmentation presented to the shovel at the digging face. A Digital Vision System (DVS) was installed on one of the shovels to capture images that were stamped with GPS locations. A large population of digital images were analysed to produce a robust fragmentation distribution baseline that was used as one of the mine key performance indicators (KPI). Changes to blasting practice were subsequently measured against the baseline KPI to assess effectiveness.

Jan 1, 2011

By T. L. Dobecki

Numerous seismic techniques have proven to be important and cost effective aids to both coal exploration and nine planning. Projects conducted by Sandia in recent years have sham seismic refraction is a valuable tool for determining overburden properties while high resolution, 2-0 and 3-D seismic reflection surveys are the primary means of napping coal seam distribution, structure, and continuity. Further, seismic methods utilizing existing boreholes (e.g. downhole, crosshole and guided wave) provide detailed measures of overburden/interburden modulus variation, seam continuity, and calibration for other seismic surveys. Examples include mapping faults of 2-10 m threw in seams 3-15 m thick at depths of 80-300m.

Jan 1, 1982

By Sakir Selcuk, Brian Hamilton, Paul Zick

The 1.8 mi (2.9 km) Minneapolis-St. Paul International Airport Light Rail Transit Tunnels and Station project is comprised of the underground segments of the 11.8 mi(18.8 km) Hiawatha Light Rail Transit route in Minneapolis, Minnesota. The 21 ft 2 in(6.5 m) diameter twin tunnels were mined 65 ft beneath one of the busiest airports in the United States using an earth pressure balanced tunnel-boring machine. This paper will provide a project overview, review the major equipment selected, tunnel segment casting, and describe excavation and lining operations for the tunnels and station.

Jan 1, 2003