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By A. H. Reitsema, Hans E. van Dam

In CIP, CIL, and Heap Leach gold recovery operations, a sub-optimal activated carbon performance invariably causes a significant loss of revenues. In this paper it is shown, how dedicated analyses of carbon samples can be used as a guide in plant performance optimiza­tion. Firstly, a brief outline is given of the most important methods of analyses, including the specialized methods not normally used by mining operations, but provided by carbon manufacturers. Then, a number of practical cases are discussed in which carbon sample analyses provided insight which allowed significant improvements.

Jan 1, 1995

By Slobodan Vujic

Production of building materials such as are stones, sand, gravel etc., is characterized by a relatively low economic value and requires reasonable transport costs. That is why we are often faced, in our practical work, with the fact that within the framework of a relatively small area several open pits of building materials are, developed side by side while neither ecological, urban and spatial nor location factors have been taken into consideration. Numerous locations together with heterogeneous factors. point undoubtedly to the problem of planning the open pits locations for building mateials as a very serious and complex one. Even when certain localities are in question, it is rather a difficult task to present a real state and encompass all the, important location factors by mathematical model ling. This paper presents one of such models for solving the problem of selecting a location for building materials open pit.

Jan 1, 1992

By Cahit Helvaci, Robert B. Kistler

Borates are defined as ' 'salts or esters of boric acid; a compound containing the radical B203" (Bates and Jackson, 1987). Borates are defined by industry as any compound that contains or supplies boric oxide. A large number of minerals contain boric oxide, but the three that are the most important from a worldwide commercial standpoint are: borax, ulexite, and colemanite. These are produced in a limited number of countries (Fig. 1), dominated by the United States and Turkey, which together furnish about 90% of the world's borate supplies (Lyday, 1991). Production in the United States originates in the Mojave Desert of California; borax and kernite are mined by US Borax from its large deposit at Boron. Borate containing brines are pumped from Searles Lake by North American Chemical Co., and a limited amount of colemanite is mined by Newport Mineral Ventures from Death Valley. Turkish production is controlled by Etibank, the national mining enterprise, which supplies most of the commercially traded ulexite and colemanite from mines in the Bigadic and Emet Districts, plus borax from the huge deposit at Kirka. Borate minerals have been employed in a wide range of uses for many centuries, dating from at least the 8th century when they were used primarily as a flux for assaying and refining gold and silver. Their valuable properties and relative rarity soon stimulated international trade in borates; Marco Polo claimed to have trans- ported Chinese borate minerals from Tibet to Europe, and his home port of Venice was the center for borate imports and use throughout the Middle Ages (Travis and Cocks, 1984). Borates were traded at relatively high prices for highly specialized applications into the late years of the 19th century. At that time they were being used for medicines, food preservatives, ceramic glazes, and in expanded applications as metal fluxes. It was in that era that borax was discovered in Clear Lake, CA, and more significantly, the playa deposits of western Nevada were found and exploited by F.M. "Borax" Smith and others. Research and development by Smith's company began the evolution of borates from a high priced commodity with a few specialized uses to the relatively low priced chemical raw material used in large tonnages on a worldwide scale today. Borates are often defined and sold by their boric oxide or B,03 content, and most statistical data are listed in tons of B203. Of the products sold by the industry, borax pentahydrate or 5 mol and boric acid are the most commonly traded commodities. Boric acid plants are operated by all of the major borate producers. Glass fiber insulation is the major end use in the United States followed by textile glass fiber and borosilicate glass, detergents, and ceramics. Detergent usage continues to be a major end use in Europe.

Jan 1, 1994

By M. Stoica

Bioremediation is a complex process which involves mass transfer, chemical and biochemical phenomena. In particular, the adsorption kinetics of a substance by biomass may by model by taking into account: - Enzymatic kinetics type; - Combined kinetics - enzymatic kinetics at the same time with the Monod type biomass growth; - Chemical kinetics for substance adsorption according to Freundlich and Langmuir ad-sorption isotherms; - New empirical kinetics models based on experimental data. In this paper modelling of kinetics of bivalent lead ions on live vegetal biomass (aquatic plant Pistia stratiotes) as well as of hydrocarbons on dead vegetal biomass (pyrolysed nuts) is studied (Stoica, 2004). Modelling was carried out using experimental data and relative equations with an error of 5%.

Jan 1, 2006

By Irving D. Cohen

In order to overcome our reliance upon foreign energy sources for both crude supply and finished products, we must realize the goals proposed by Project Independence. In general this involves expanding production of existing and new oil, gas, and coal resources, utilizing and improving nuclear technology and the developing of new energy sources such as solar, geothermal, oil shale, tidal, wind and stimulation techniques. There is a continuing debate, both in the scientific community and the consuming public as to the potentiality of nuclear power generation being cost effective and environmentally and safety conscious. The development of new sources of energy does not occur overnight; it is rather a continuing effort in time and money to achieve the goal of providing energy to an ever increasing demand. The public has been accustomed to the availability of energy whenever and wherever it was needed. The era of "energy gluttony" has begun to fade into the realm of "energy awareness". Unfortunately, it required the action of another country to bring the picture that has been discussed many times in the past by energy suppliers into correct focus. Nevertheless, the public responded by conservation efforts to reduce energy wastefulness. Still, the demand for foreign importation of energy supplies is on the rise. What is our recourse? The largest known unexploited energy resource available in the United States is our coal resources. Moreover, the Department of the Interior has noted that 63 counties in Montana, Wyoming, and the Dakotas hold 60% of the nation's least expensive strip minable coal. This western coal is the most abundant and least costly Fossil Fuel in the United States. It is acknowledged that western coal is an important input in meeting the energy needs of our nation.

Jan 1, 1976

By Charles N. Speltz

The cost of transportation of industrial minerals frequently is higher than the cost of the product. When a mine, industrial-mineral plant, or customer is served by a single railroad, because of the lack of competition, that railroad may in- crease rates and/or reduce service so that the economics of that mine, plant, or customer are affected adversely. Transloading of industrial minerals from rail-to-truck or truck-to-rail to improve economics and sales of product is not a new concept. However, transloading to create competition and reduce freight costs or to improve service is a relatively new concept brought on by the recent mergers of many of the main-line railroads, both in the eastern and western United States. For example, in 1998, with completion of the Burlington Northern/Santa Fe (BNSF) and the Union Pacific/Southern Pacific mergers (UPSP), the western United States has only two main-line railroads. The industrial-mineral producer, to reduce the cost of transportation or increase the level of service, must evaluate potential transloading opportunities in light of higher prices and reduced service brought on by reduced railroad competition. This paper discusses industrial-mineral transloading and examines the case history of the Tucker Hill perlite project in southern Oregon. The Tucker Hill project is a classic study of industrial-minerals transloading where the project would have failed without the transloading.

Jan 1, 1999

By B. Suresh, Kalyan K. Das, Pradip

A series of salicylaldoxime derivatives with alkyl group substitution in the main chain and the side chain were synthesized and evaluated for the flotation of malachite, cerussite and smithsonite. The effect of chain length and the position of the substituent group on the selectivity of separation amongst oxidized copper, lead and zinc minerals are discussed in this paper.

Jan 1, 1995

By Thomas J. Regan

The first stage of the Massachusetts Bay Transportation Authority's Red Line Extension Northwest, is a two-track rapid transit extension from Harvard Square in Cambridge, through three stations, to the Alewife Station/Garage complex in North Cambridge. The extension, about 5.0 km. (3.1 miles) in length, is entirely in tunnel, with the Alewife Station/Garage complex and adjacent line sections of tunnel constructed by cut-and-cover methods. The Station/Garage complex, just west of Alewife Brook Parkway, is in an area underlain by deep deposits of very soft highly sensitive clays. It is proposed to construct the station and adjacent tunnel sections by the slurry trench method, using the slurry wall as the permanent structural wall of the station and tunnel. The unusual nature of the underlying clay and its very high sensitivity raised questions concerning the feasibility of the proposed construction. Since research failed to reveal any construction precedent for the specific conditions encountered, a test section was undertaken to determine construction problems, resolve uncertainties, and to establish acceptable parameters for the construction of the slurry walls. PROJECT ORGANIZATION Sverdrup & Parcel as tunnel and transit systems consultant for the Red Line Extension-Davis Square to Alewife had overall responsibility for determining program objectives, project management and test implementation.

Jan 1, 1979

By F. Grajales Munoz

The Cienega project, now under construction by Penoles group, is located in the mountains of the State of Durango, Mexico. The gold and silver deposits are found in the 4-km long system of veins, which will be extracted by underground methods. The planned 1000 tpd process plant will contain a countercurrent cyanide circuit for oxide ore and a flotation circuit for sulfide ore. Considerable resources have been devoted to development of infrastructure in the isolated location, as well as for the mitigation of environmental impacts. Startup is scheduled for the third quarter of 1994.

Jan 1, 1994

By A. J. Monhemius, S. Raghavan, G. W. Warren, E. Peters, D. W. Furerstenau

A lyometallurgical process for extracting copper from an ore containing chrysocolla by leaching it with a kerosene solution containing LM 63 in the presence of small amounts of aqueous ammonia is described. The experimental results indicate that 70 to 75 percent of the copper can be extracted from the ore using an ammonia content that is about one-fourth the stoichiomeaic quantity required to leach copper in an aqueous leaching system. The rate of copper extraction was found to be a function of particle size, ammonia concentration and temperature. The large quantity of physically adsorbed water together with ammonia in the pores of chrysocolla provides a mechanism for the transport of copper to the external surface of the particles where it is complexed by the LM molecules and transferred into the organic phase. When size reduction accompanies leaching, the extraction process was found to proceed when only "trace" quantities of ammonia are present in the system. The kinetics of the extraction process appear to be controlled by a mixed (reaction and diffusion) mechanism.

Jan 1, 1993

By Severn P. Brown

Cement plants in the central Hudson River valley utilize limestones of the Helder-bergian Series of the Lower Devonian. Chiefly calcilutites, calcarenites, and cherty calcisiltites, these rocks represent progressively deeper environments, from lagoonal to neritic, with scattered reef deposits. Stratigraphic continuity is marked, and a layer-by- layer analysis shows strikingly constant chemical compositions. The structural picture varies from flat-lying and relatively unfaulted beds on the northwest, through gently folded and faulted beds on the north, to complex overturned beds with closely spaced imbricate faults on the south. Operating techniques are simpler in the north, where grade control is effected chiefly by the initial layout of the faces. In the south, grade control requires flexibility and frequent adjustment of faces or scheduling. A system of quarrying along strike has been developed, grade being computed from a cumulative foot-per cent graph of the critical oxides in each mappable layer. Balancing shovel production among the many faces is simplified by comparing production requirement ratios with ratios of the various types of rock in each face. Drilling and blasting limits are geologically controlled if warranted, or large blasts embracing several rock types are shot and the resulting pile of broken rock is staked along shovel limits.

Jan 1, 1966

By H. Zhu, A. G. Journel

Qualitative and interpretive information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging, and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system provides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data. A case study using a large reference database is presented; the indicator conditioned estimates have a smaller conditional bias and a smaller error variance than the ordinary kriging estimates. The results also showed that the indicator conditioned estimator is more efficient for selection in mining.

Jan 1, 1990

By Arthur W. Darby

Heathrow Airport is owned and operated by BAA who are engaged in a major programme of expansion. In order to link the expansion of the airport in the west with the existing central terminal area, a twin bore, 8.8m outside diameter, road tunnel,1280m long, is being constructed. The tunnel drives pass over, with limited clearances, an operating railway tunnel, and pass under, with about one diameter cover, the airport taxiways and aircraft stands. Selection of the machine was heavily influenced by the need to minimise settlement.

Jan 1, 2003

By Gary Krix

The Amdel Thickener Interface Gauge (TIG) provides continuous on-line measurement of the level of the liquid/solid interface in thickeners and Counter Current Decantation (CCD) washers. Unlike other interface level measurement systems, the TIG also determines the span of the transition zone. The transition zone is the region between the clear liquid overflow zone and the compressed solids zone. The Thickener Interface Gauge determines the level of the interface by measuring the natural radioactivity of the solids in the thickener tank using an array of up to twelve detectors mounted vertically in a stainless steel probe. All solids contain low levels of natural radioactivity while the liquid phase generally does not. The concentration of natural radioactivity at each level in the thickener therefore depends on the concentration of solids. The radiation emitted by the solids is converted to electrical pulses by the detectors in the probe and the pulse-rate provides an accurate measurement of the density. A typical count-rate profile is presented in Figure 1. The vertical axis indicates the depth in the tank referenced to the surface of the liquid. The horizontal axis indicates the count-rate measured by the TIG probe, this count-rate is proportional to the density and can be used to determine the settling rate. The count-rate at the top of the graph is relatively low, this region corresponds to the clear overflow zone which contains virtually no solids. Moving down the vertical axis the count-rate increases dramatically at the level of the transition zone where the solids content increases with the depth in the tank. In this region the settling conditions of the solid particles change from free settling to compression. Moving further down the vertical axis the count-rate reaches a plateau where the count-rate remains relatively constant although there are often small fluctuations, this region corresponds to the solids compression zone. The liquid/solid interface as measured by the TIG corresponds to the depth at which the count-rate crosses the target count-rate which is generally selected to be midway between the liquid count-rate and the compressed solids count-rate. The length of the TIG probe is selected to cover the typical operating range of the liquid/solid interface in the thickener or washer. If, for example, the minimum bed level is 3.0 metres below the surface of the liquid then the probe length is selected to extend 30 metres below the surface. The TIG probe can include up to twelve detectors and the se are spaced over the measurement range. For small measurement ranges of around one metre 4 to 6 detectors would normally be used while for larger measurement ranges of three metres or more twelve detectors would be supplied.

Jan 1, 1993

By Igor V. Nazarov

INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.INTRODUCTION Tens of deposits in' coal basins of Western and Eastern Siberia are being open-mined with the technology of overburden rehandling into the mined out space of pits by excavators - draglines. This technology is preferred due to the high productive Russian equipment, comparatively low cost, and relatively small Influence exerted on the environment. The basic tendency of the last decades is the aspiration for enlarging the sphere of the' technology application for development of gentle and steeply dipping seams with the use of blast destruction of overburden and with combined winning of loose alluviums and rock partings. Complex technological schemes with multiple rehandling are widely used. In addition to it, stripping workings, intermediate storage of mineral resources, placing of transport dumps, and engineering construction can be realized with the use of draglines. More than ten of dragline faces are simultaneously exploited in some pits, and the rehandling coefficient ranks from 0.1 to 8. Here, conditions of winning and placing (position of a face and existing dump) are varying in space and time; this leads to the necessity of reconsidering the order for conduction of works (schemes) within the current designing. By now, in order to this, it is required to realize complex engineering calculations by graph-analytical methods and definite experience. The need is available for automatization of this process by creation of the corresponding software. The software is to: • Orient on the active pits and use information on the existing geology, equipment, and situation in mine. • Calculate the existing schemes more operative and on a higher qualitative level to model their development in a pit space with parameter optimization. • Predict situations demanding to change the existing technology for mining operations and recommend optimal technological schemes. METHODOLOGICAL FOUNDATIONS FOR MODELING The problem is not new, it has more than fifty year-old history of creating mathematical models algorithms, and programs in Russia, Ukraine, USA, Canada. Australia and other countries with the developed mining branch. Conventionally, all population of programs can be divided into three groups depending on goal and interval of prediction: • Long-term programs used in designing and intended for substantiation of the nine capacity, selection of mining system, establishment of limits for applying the technology of overburden rehandling. • Mid-term programs used in current planning for calculation of technological schemes and certificates of face in active mines.

Jan 1, 2002

By A. J. Stewart, M. Guay, J. W. Critchfield, A. P. Hoddeson

The MetroWest Water Supply Tunnel project includes three main work shafts, excavated primarily in rock. Shaft L is 9.8 m (32 ft) diameter and 124.1 m (407 ft)deep. Shaft E is 7.0 by 12.8 m (23 by 42 ft) and 91.4 m (300 ft) deep. Shaft 5A is 7.9m (26 ft) diameter and 72.5 m (238 ft) deep. Construction methods are compared and contrasted. Lessons learned involve a differing site condition in soil overburden, contractor-proposed modifications, and remedial slurry wall work. Other aspects discussed include noise and vibration control, groundwater inflow, water treatment, muck handling and contract administration issues.

Jan 1, 1999

By James S. Goff, Stephen J. Navin, Wesley W. Moulton

The White River Shale Oil Corporation (WRSOC) is developing a prototype oil shale facility on Federal Lease Tracts Ua and Ub located in northeastern Utah. This paper covers the successful driving of 1,525 m (5,000 ft) of dogleg downgrade decline with a 70-ton Paurat Roadheader mining machine and a conveyor muck-handling system. Ground support is with rock bolt and shotcrete; welded wire mesh is optional. The Upper Decline of 3.89 m by 8.69 m (12.75 ft by 28.5 ft) was mined through the Uinta Formation sandstones and shales in 210 days. The sandstones have a compressive strength in the 48 MPa (7,000 psi) range with a few bands of shale up to 137.8 MPa (20,000 psi). Green River Formation dolomitic marlstone with some sandstone lenses was mined in the Lower Decline 3.89 m by 5.64 m (12.75 ft by 18.5 ft) in 175 days. The Green River marlstones are tough massive formations ranging up to 206.8 MPa (30,000 psi). Roadheaders for use on steep slopes must be modified to accommodate the particular problems associated with mining downdip. The paper concentrates on the application of Roadheaders to steep slopes and the problems of mining tough materials such as marlstone. The paper also shows the advantage of using the method of excavation on long drives.

Jan 1, 1985

By I. S. Parrish, D. W. Kappes, G. G. Austin

Micron-sized gold disseminated in lower Cambrian siltstone has been found at the Sterling mine near Beatty, NV. A shoestring-shaped body has been developed by central and fringe drifts and is being mined via a modified retreat room and pillar system. The siliceous ore crushed to 5.08 cm (2 in ) is stacked to 4.6 m (15 ft) over a layered sand, gravel, and impervious PVC base. Gold is leached using a 0.1% cyanide solution and deposited on activated coconut shell carbon. Stripping of the carbon by hot solutions of 1% NaOH and 20% Ethanol yields overall recovery of about 75% of the fire assay head.

Jan 1, 1983

By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

By Darryl J. Butcher

The Akjoujt Project is operated by MORAK SA, a company incorporated in the Islamic Republic of Mauritania. MORAK is jointly owned by General Gold International SA (A wholly owned subsidiary of General Gold Resources NL.), SAMIN, and the International Finance Corporation. The project was devel­oped to treat approximately 2.1 million tonnes of TORCO (Treatment of Refractory Copper Ores) tailings containing an average 3.2gAu/t, and 0.75%Cu/t. The process involves the use of ammoniacal cyanidation for gold extraction, and conventional carbon adsorption, and eventual desorption, of gold values. This is believed to be only the second commercial application of this leach chemistry in the world. The other being a small vat leach operation on the Paris Mine Dumps. (This operation was described by Mr M Ruane in a paper to a previous Randol Forum.) Initial work on the process, and the Akjoujt process design assumed that the reaction involved was anaerobic. This paper describes the operating experience, plant trial, and eventual installation which has lead MORAK to the conclusion that the process is not anaerobic, but requires oxygen, or an oxidant to proceed.

Jan 1, 1995