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By B. R. Reddy, P. V. R. Bhaskara Sarma

A process for the separation and recovery of cobalt and nickel was optimized for a sulfate leach solution of Indian Ocean sea nodules containing 80 g/m3 cobalt and 730 g/m3 nickel using the sodium salt of Cyanex 272 as the extractant. Extraction of both cobalt and nickel increased with an increase in equilibrium pH and extractant concentration. The extracted species with respect to cobalt appears to be CoA2.3HA. More than 99.6% extraction of cobalt was achieved using 0.04M solvent in a three-stage counter current simulation at the A:O phase ratio of 3:2. The co-extraction of nickel was about 0.6% only. Two-stage countercurrent stripping of cobalt from the loaded organic at an A:O ratio of 1: 7 resulted in a pregnant electrolyte enriched by 0.8 kg/m3, thus enabling a ten times overall enrichment of cobalt. From the cobalt free raffinate, nickel extraction was carried out using 0.25M solvent in two countercurrent stages, and the extraction showed a 99.8% recovery. Stripping of nickel from the loaded solvent was carried out at an equal phase ratio with the advance electrolyte of pH 1.75 in two countercurrent stages. The nickel stripping efficiency was found to be 98.8%. The present studies indicated that complete recovery of cobalt and nickel was possible using nine counter-current stages.

Jan 1, 2002

By K. Kavouridis

Coal is broadly recognized as sure, competitive, diversified, not vulnerable and predictable in price energy resource. In power generation coal is playing a dominant role in the EU-27 with 25% of installed capacity and almost one third of the power generation. The role played by the domestic resources and especially by coal are increasingly becoming the focus of the EU energy strategy. There is a strong pressure for the decarbonization of the energy mix. The Emission Trading system (ETs) can have an impact on the shift to lower carbon-intensity fuels. The impact of ETs on coal can be important, because it is very short sighted and only defines the period up to 2008-2012. The ETs CO2 regime must ensure that investment in coal-fired plants in the long term are supported. EU Research Institutes and Coal Industry identified an important CO2 reduction potential by improving the efficiency of the conversion of solid fuels into electricity. Highly efficient clean coal technologies can contribute to reasonable costs and challenge the issue of climate change. It must be pointed out that the EU Energy policy should now concentrate on the necessity to effectively support demonstration projects and to create the legal framework for the integrated approach of efficiency enhancement and CCS. It is not a right approach to implement CCS before the technology is demonstrated and before it is clear that it will be commercially viable.

Jan 1, 2007

By R. A. Jankowski, J. J. McClelland

Laboratory tests were conducted by the U.S. Bureau of Mines to determine the respirable dust reduction effectiveness of and interaction between face airflow and water sprays for a continuous miner. Exhausting face ventilation was varied from 3,000 to 9,000 cfm (1.42 to 4.25 m3/sec). Spray-water-flow was varied from 15 to 35 gpm (0.057 to 0.132 m3/min), while nozzle operating pressure was varied from 80 to 200 psi (5.62 to 14.06 kg/cm2). Results from gravimetric dust samples indicated that airflow had the greatest individual impact on reducing dust levels, with return and operator concentrations reduced by as much as 57% and 99%, respectively. Interactions between dust control parameters were found to be significant. Often, these interactions defined a level of application for a control parameter where further increases in that parameter failed to produce additional reductions in dust concentrations. In several cases, increases in a control parameter resulted in higher dust levels at the operator's location. These higher dust levels were attributed to additional rollback and/or airflow turbulence. Regression modeling indicated that increases in airflow to 8,400 cfm (3.96 m3/sec), water flow to 25 gpm (0.095 m3/min), and water pressure to 140 psi (9.84 kg/cm2) typically were beneficial at the operator and return sampling locations.

Jan 1, 1991

By George Aul, Richard Ray

Short-hole horizontal degasification systems have been utilized in Island Creek's Virginia Division mines since 1986. These systems remove methane from the coal seam in advance of longwall mining. Without an in-seam methane drainage program, methane liberation rates from the longwall faces may exceed 0.47 cu m/s (1,000 cfrn), requiring 47 cu m/s (100,000 cfm) of air for adequate dilution capability. Optimization of the degas systems has enabled methane liberation levels and the associated ventilation requirements on the longwall faces to be reduced by 50 to 80 percent. Since the inception of the first degas system at the Virginia Pocahontas No. 6 Mine, Island Creek has developed an overall methane drainage program designed to maximize gas production and minimize ventilation requirements for methane dilution. Gas production from the degas systems is affected by four main design criteria: (1) hole location, (2) hole length and spacing, (3) collection system capacity, and (4) time available for drainage. Drilling equipment and materials for the gas collection system are selected to meet the necessary criteria while minimizing manpower requirements. Benefits gained from reducing methane liberation rates from the longwall faces are fourfold: (1) improved safety due to lower methane concentrations in the face area, (2) fewer production delays caused by excessive methane concentrations, (3) lower fan operating costs resulting from reduced air requirements, and (4) enhanced worker comfort resulting from lower air velocities and less dust generation.

Jan 1, 1991

By Lynne Chastain

The Eastern Shoshone and Northern Arapaho tribes of the Wind River Indian Reservation, Wyoming are interested in developing their industrial mineral resources. The U.S. Bureau of Indian Affairs (BIA), Division of Energy and Mineral Resources (DEMR) is assisting the tribes in evaluating the potential of their industrial mineral prospects for development. Gypsum occurs on both sides of the Owl Creek Mountains in the basal portion of the Jurassic Gypsum Springs Formation. The gypsum resources that are being evaluated crop out along the northern flank of the Owl Creek Mountains in the Sweetwater basin, a small topographic sub-basin of the Big Horn Basin. From October 1998, to April 1999, DEMR personnel mapped, sampled, and drilled the southcentral butte within the Sweetwater basin. Samples were analyzed for free and combined water, and major mineral oxides to determine gypsum purity. Gypsum purity averaged 93.6 percent for surface samples and 95.1 percent for drill core samples. The basal portion of the Gypsum Springs Formation is comprised of several beds of gypsum up to 9 feet (2.7 m) thick separated by 0.5 to 2.0 foot (0.15 to 0.61 m) thick lenses of siltstone and limestone. Overall gypsum in the formation ranges from 35 to 90 feet (11 to 27 m) in thickness. A resource of approximately 7 million short tons (st) (6.4 million metric tons [mt]) has been identified.

Jan 1, 2001

By W. J. Schlitt, K. McNaughton

A heap-leach field test was conducted during the 1993-1994 winter season at Carmacks, Yukon Territory, Canada. The purpose of the test was to demonstrate the viability of heap leaching Carmacks oxide copper ore in an arctic setting on a year-round basis. The test itself utilized a 5-m-diam crib loaded with 250 t of composite ore from the Carmacks copper deposit. The ore was stacked to a total height of 7 m in the crib, including 1 m of ore as an over- layer above the emitter system. This matched the plan for the commercial heap at the time when the test was started. The design also replicated an interior segment of the commercial heap. Leaching was done at a flow rate of 0.2 L/min/m2 using leachate at 21 °C. This temperature was maintained with no external heat input other than normal process heat transferred from electrowinning to the leachate via solvent extraction. Winter conditions were quite typical of those expected at the mine site. The temperature reached -54°C, while averaging -13°C over a three-month period. In spite of some flow system problems, leaching continued unabated, and freezing was limited to the insulating ore over-layer and isolated points near the outer crib walls. Thus, the test demonstrated that year-round heap leaching of Carmacks copper ore is practical in an arctic setting.

Jan 1, 2000

By John T. Gormley, Pressley L. Campbell, Harry L. Crouse

INTRODUCTION This paper summarizes an investigation conducted to determine the relationship, if any, between reported occurrences of abnormal levels of carbon dioxide (C02) gas and the construction of a 2.44meter diameter main sewer tunnel under South Eighty-Fourth Street, West Allis, Milwaukee, Wisconsin. Specific objectives of the study were to determine: (1) the sources of C02, (2) the significance of each C02 source, (3) how C02 could move to areas where it was reported to occur in abnormal concentrations, and (4) what actions could be implemented to eliminate elevated C02 levels associated with the tunneling operation. To accomplish study objectives, expertise from several scientific and engineering disciplines was required including chemistry, geochemistry, microbiology, hydraulics, and hydrology. Pertinent documents were reviewed and field data pertaining to each aspect of the study were collected as required and examined to evaluate existing conditions. Background On or about February 1, 1971, gas with a composition different from normal atmospheric air was reported to enter basements and wells of residences in the vicinity of South Eighty-Fourth Street, West Allis, Wisconsin. Examination of the gas composition revealed that it possessed an elevated concentration of C02 and a depleted concentration of oxygen (02). Public health officials who investigated the appearance of the objectionable gas concluded within reasonable certainty that the elevated C02 concentrations were associated with the tunnel construction under Eighty-Fourth Street.

Jan 1, 1979

By Steven W. DeCou, Marcus R. Jensen, Stephen Navin

The Lake Mead Intake No. 2 is a project constructed for the Southern Nevada Water Authority which includes a 12-foot diameter lake tap and intake shaft constructed in over 225 feet of water; 1650 feet of 16x14-foot horseshoe-shaped tunnel leading to a forebay that is 165 feet long, 35 feet tall, and 30 feet wide; twenty-two 4-foot diameter steel lined well shafts extending 325 feet from the ground surface to the forebay; 3500 feet of 12-foot diameter pipeline crossing a bay in Lake Mead that has water depths of up to 80 feet; and 2700 feet of 9-footdiameter steel-pipe-lined tunnel. Major site grading for a future pumping station in the area above the forebay is also included as part of the project. The project is on the schedule’s critical path for completing the first phase of a $2 billion water supply program for the Las Vegas Valley. In this paper, the owner, the designer and the construction manager present a discussion of the risk management strategies that were used to control costs, minimize project delays, and facilitate problem resolution. The discussion includes an assessment of the effectiveness of the risk management strategies in meeting these objectives. This paper will be of interest to owners and engineers planning underground projects, especially those projects that present unique risks during the construction phase.

Jan 1, 1999

By E. M. Frizzell

This paper addresses the use of the microcomputer programs BACKONE and BACKWEDG for an estimation of rock mass strength characteristics by back analysis of plane and wedge failures. The artificial support requirements are also determined by the programs PLANE2, BOLTPAT, and BOLTWEDG in terms of rock anchor installation angles, tensions, and installation patterns. These programs have been combined into a package called BACKPACK, which can be applied in open pit mines where some failures have already occurred.

Jan 1, 1988

By Anthony D. Songer, James E. Diekmann, Jarrett E. Carlson

Computer Aided Design (CAD) systems are currently recognized as a necessary tool for the management of projects. Currently, CAD is used for TBM and conveyor setups, concrete lift design and overall constructability reviews. Typically, such CAD models exist only in 2 dimensions. The advent of more powerful computers, enhanced CAD programs and after market animation packages provides tremendous potential to the Tunneling industry. In particular, effective application of these technologies enhances cost, time and quality in field operations.

Jan 1, 1997

By Cao Changlin, Gong Qian, Hu Jiexue

The thiosulfate, effects copper of concentrations of and ammonia ou the extractlon of gold from sulfide gold concentrate have been studied. The experimental results showed that it is possible to reduce thiosulfate concentration. Above 95% of gold extraction was obtained in O. 2M thiosulfate leaching solution in two hours under the suitable conditions. Therefore, the process of washing residue was simplified, the consumption of thiosulfate and the loss of thiosulfate carried were reduced. by washing residued.

Jan 1, 1992

By M. J. Virnig, J. M. W. Mackenzie, M. W. Johns

The properties of Henkel's Aurix® resin which uses a guanidine functionality to recover gold by ion exchange have been described in publications of the International Mineral Processing Congress and Randol International (1)(2). The purpose of this paper is to provide an update on the results of further testwork using Aurix®. Specifically, this paper presents the first results of resin in pulp testing, all the results previously reported were for testwork carried out using synthetic gold leach solutions.

Jan 1, 1995

By Dmitriy A. Malovichko

The general theory for the description of seismic sources is briefly discussed. The effect of excavations on seismic radiation is considered. Expressions for seismic source mechanisms in terms of the geometrical and mechanical parameters of source processes are provided for the following cases: fault slip and shear failure in a confined environment, dynamic stress fracturing around a tunnel, rock fall, landslide and sudden subsidence. A classification of seismic events in mines based on source mechanisms is introduced. The classification separates blast-, slip- and crush-type events. Various approaches of analysis of source mechanisms involving forward modelling and inversion are discussed. The following examples demonstrating the utility of source mechanisms in mining are presented: forensic analysis of damaging seismic events, assessment of the increase in the depth of failure for dynamic stress fracturing around tunnels and its duration, examination of the rockmass deformation regime, assessment of deformation around tunnels using crush-type events, identification and parameterisation of weak geological structures, stress inversion from slip-type events. Finally, the requirements for seismic data to ensure high quality source mechanism solutions are briefly reviewed and future challenges in the interpretation and utilisation of seismic source mechanisms in mines are speculated on.

Apr 26, 2022

By Dietrich F. C. Hudewentz, Alfred H. F. Lücker

For centuries tunnellers have made use of the experience of miners. In West German coalmining tunnellers have returned the impulses in recent years by giving the miners valuable stimuli with the result that a technology has evolved which benefits drill and blast heading, opens the door to TBM heading and has developed special measures for difficult strata conditions in deep coal mines. WHAT DO THESE ROCK HEADINGS LOOK LIKE? The main roadways dealt with in this paper have crosssections of 20 to 40 m2, big enough to allow the massive airflows needed to aircondition the mines. Because of the difficult strata conditions they have to be supported: in shotfired headings mainly with multi-element arches, in TBM headings with rings of 6 to 6.5 m diameter. In West German coalmining the majority of rock headings are blasted. The proportion of rock headings driven by TBM was 11 % in 1980 and 16 % in 1981, a rising trend expected to continue. Drill and blast headings Drill and blast headings are normally equipped with two or three-boom electro-hydraulic jumbos, electro-hydraulic crawler-mounted loaders with 1.2 m3 shovel capacity, a movable working platform and both chain and belt conveyors for dirt clearance to the minecar loading point. Fans and air-condition plant complete the equipment. Spacing between arches is usually 0.8 m. Investment for this type of mechanisation works out at around 1.3 m DM.

Jan 1, 1983

By Z. Eisenstein, H. Heinz

INTRODUCTION Contemporary underground transit systems often require cross sections which are not adaptable to shield tunnelling. Due to the frequently large dimensions of these cross sections, which are normally situated at shallow depths and in soft ground, full face advance is not feasible because of ground control and construction requirements. Ground deformation and face stability are controlled by "staged excavation", which consists of sequentially driving smaller, specially arranged, individual headings hence avoiding full-face excavation. Shotcrete is normally used for initial support and these tunnels are frequently described as applications of the New Austrian Tunnelling Method (NATM). Figure 1 illustrates the relative size of large cross section tunnels with respect to conventional shield tunnels. Within the scope of this paper, 'large' cross sections are defined as those whose continuous (i.e., without intermediate pillar support) cross sectional excavated area exceeds 60m2. This definition includes most double track highway, railway and subway tunnels, subway stations and some single track railway tunnels. Excavation schemes which have been more frequently used for continuous cross sections (i.e., with no intermediate pillars) are presented in Figure 2. This classification is an extension of that presented previously by Eisenstein et al. (1986). The symbols used for classifying the excavation schemes are formed by the letter T (for "type"), followed by a number, which represents the number of excavation stages fully embraced by a shotcrete ring, termed "cells" by Lessmann (1986). The numbers inside the cross sections in

Jan 1, 1989

By Richard M. Levine

Now that the former Soviet Union has divided into 15 countries, it is necessary to analyze separately the industrial mineral position of each of these countries. Industrial mineral data The former USSR was one of the world's largest producers of industrial minerals and had some of the world's largest reserves. Production and reserve figures, however, must be qualified. Even when these figures were reported by the Soviets, it was not clear that the production figures were for products that would be equally marketable in a competitive market economy. The reserve figures are based on the Soviet system of reserve classification, which is not directly equatable with the US Geological Survey and US Bureau of Mines classifications of economic reserves in market economy countries. The Soviets reserve classification system, in terms of which reserve figures will be given, is based on the reliability of the quantity of the material in place. The Soviet system assigns each occurrence to one of seven categories A, B, C1 and C2 are considered reserves; P1, P2, and P3 are considered resources. Mining in the former Soviet Union was authorized on the basis of the reserves in place in categories A, B and C, which had to be in prescribed ratios. However, the categories A, B and C do not necessarily correspond to Western concepts of material economically exploitable under present market prices with existing technologies.

Jan 1, 1992

By S. Hicks

This technical note describes an alternative procedure that can be used in linear programming calcula¬tions where the compliance limit of lbs S02/million Btu for the blending coal is subject to change. Dr. Mateer in his technical note titled "Coal blending for sulfur compliance" (ME, September 1994, p. 1103) defined an "excess sulfur" parameter that provides a valid constraint equation for a linear program optimization. The coals used by Dr. Mateer in his examples are shown in Table 1. To create the parameters for the constraint equa¬tions to blend to an SO2 content of 1.2 lbs S02/million Btu; the excess sulfur for Coal A was defined as Sulfur excess%o = 0.5 - 0.6-13,000/10,000 = -0.28 This equation was used to create the constraint equation -0.28A + 0.44B + 1.36C<- 0.0 Another way to create the parameters for the constraint equation is given below. In these equations: ? W is the total weight; ? A, B and C are the fractional proportions of each potential blend stocks; ? Sa, Sb and Sc represent the percent sulfur content of the blend stocks; ? Ha, Hb and He represent the calorific content of the blend stocks in Btu/lb; and ? H and S represent calorific and sulfur contents of the composite blend. The weight of blend to produce one million Btu is [ ]

Jan 1, 1997

By Heinrich H. Becker, Vladimir L. Konyukh, Sergey P. Koltsov, Valery A. Davidenkol

Ramifide conveyor transport of the biggest russian coal mine "Raspadskaya" is simulated by Petri nets. There are 6 longwalls with accidental output. 12 belts, and 5 transfer bunkers at this mine. It is necessary to coordinate transport links for recon- structed conveyor system. Many tasks were solved by dynamic simulation, such as estimation of transport lateness, influence of transfer bunkers on an unevenness of total coal flow, maximum filling of each bunker, maximum time of main conveyor refusal, co-ordination of unloading for dependent bunkers, choice of main conveyor. The problem of mine-wide conveyor transport animation for dispatcher is formulated in reference to mine "Komsomolets". OBJECT OF SIMULATION The biggest russian coal mine "Raspadskaya" is situated on a south part of Kusnetski coal basin (West Siberia). One mines about 20.000 tons of coal out of flat seams by 2.2-4.5 m thickness in a day. There are 6 fully- mechanized longwalls by output 720- 3600 tons in a shift in mine. Coal haulage to surface is carried out by 12 belts having 1.6 - 4.3 km length. For a smoothing over un- evenness of coal flows 5 transfer bunkers to 300 tons were intro- duced. The designed conveyor system is divided into two parts (Figure 1). In the upper part some coal from Face 1 comes through belt road C, into transfer bunker 8,. From the opposite side that bun-

Jan 1, 1996

By Wolfram Schnabel

Recently Lurgi has succesfully commissioned Peru&apos;s first direct reduction rotary kiln at SIDERPERU?s Chimbote works. The order included comprehensive engineering services and supply of special equipment to modify three existing cement kilns according to the SL/RN process. The kilns were cut to 62m length and installed with a slope of 2.5%. A new heating system, including shell burners, was supplied and inlet and outlet ends of the kilns completely renewed. Figure 1 shows the kilns after modification.

Jan 1, 1981

By W. J. Wuest, M. J. DeMarco

The US Bureau of Mines (USBM) recently developed a rock-mass classification system for evaluating the structural competency of bedded roof strata. The system is called the coal-mine roof rating (CMRR), When compiled with the companion Lotus 1-2-3 spreadsheet, CMRR data are a useful tool with applications to longwall gate-road pillar design, safety-hazard mapping and artificial roof-support analysis. This paper gives a review of some applications under actual conditions found in current US mining operations.

Jan 1, 1997