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By E. C. Dowling, S. A. Elmquist, L. A. Kipfstuhl

The Cliffs and Associates Limited (CAL) 500,000 tpy HBI plant located in Trinidad was commissioned after modifications in early 2001. This plant employs the novel Lurgi Circored® process to reduce iron ore fines using a combination of circulating fluidized bed and conventional fluidized bed reactors in a hydrogen based. This paper will review the advantages offered by working in the Caribbean nation of Trinidad and Tobago, the Circored® processes, and plant start-up experience.

Jan 1, 2002

By D. A. Curry

This paper describes a study of the influence of non-normal loading on the indentation behaviour of single bit-teeth. Indentation experiments have been performed on a soft, isotropic limestone using both sharp and blunt 60 degree wedge-shaped indentors constrained to penetrate the rock at 0, 15, and 30 degrees to the rock surface normal. For both sharp and blunt indentors, the normal force required to produce a given normal penetration decreased as the offset of the penetration direction from the rock surface normal increased. The crater volume produced by a given normal penetration with the sharp indentor was largely independent of the penetration direction. In contrast, the crater volume produced by the blunt indentor was increased markedly by non-normal penetration at small penetration depths, because the threshold penetration for chip formation decreased with non-normal loading. The crater volume produced by a given normal force was significantly increased by non-normal penetration, and this increase was particularly pronounced with the blunt indentor. The energy required to form unit crater volume was correspondingly reduced by non-normal indentor penetration. A simple method for predicting the reduction in the rock's resistance to chip formation is outlined, which is supported by the experimental data. The implications of these findings for rotary drilling are considered.

Jan 1, 1986

By W lethlean, Laurie Smith

When coarse gold is present in an ore, there are advantages in physically recovering this gold in the grinding section of the ore processing plant. This reduces the risk of the coarse gold being locked up in the grinding section equipment, reduces the quantity of activated carbon to be eluted and reduces the risk of gold passing out of the cyanide leaching circuit only partially dissolved. The free gold may be recovered by various mechanical means utilising the significant difference between the specific gravity of the gold and waste minerals. Frequently, sulphide minerals and ball mill attrition steel in the form of fines and chips are present in the ground ore and behave in a similar manner to the gold in the concentrating process. These materials must be removed to produce a concentrate suitable for direct smelting and several stages of cleaning, sometimes utilising different physical principles, may be required. The removal of these materials invariably results in a loss of gold from the final concentrate. The rejected materials containing significant quantities of gold are returned to the grinding section, consequently the opportunity for a high and early recovery has been lost. The quantity of gold returned to the grinding section will vary according to the number and type of cleaning stages and the physical characteristics of the materials and the gold but surveys of the gravity concentration processes suggest that it may be as high as 50%. To maximise the recovery of gold from the primary gravity concentrate, some operations batch cyanide leach this concentrate with or without additional reagents. The method of agitation and solution recovery vary. The most common method of agitation is by a high-speed propeller mixer and the least expensive but time-consuming method of solution recovery is by decantation after settling and by repeated decant washing. The pregnant gold solution is either introduced into the main ore leaching circuit or the gold is recovered by direct electrowinning. After commissioning in 1994, Union Reefs Gold Mine (URGM) experienced below expected recovery of gold from the gravity concentrate generated from the Knelson Concentrators. It was shown that the recovery into the Knelson Concentrate was high but that the subsequent mechanical concentrating techniques of tabling and magnetic separation resulted in significant gold being returned to the grinding circuit.

Jan 1, 2000

By Avula Rajashekar Yadav, Sreenivasa Rao Islavath

Barrier pillars and gateroads play a vital role for the safe exploitation of coal from the panel in the longwall workings. The barrier pillars and gateroads are subjected to the front abutment and side abutment loads during the retreat of the panel. These structures may fail if the developed load on them is higher than their strength. The stability of the longwall structures such as barrier, gateroads and face is paramount in extracting the coal from the panel safely. For this, a deep longwall mine in India is chosen for the study using a 3D numerical modelling technique. In this paper, three critical conditions such as scenario 1 (no side goaved-out panel), scenario 2 (with side goaved-out panel) and scenario 3 (with two side goaved-out panels) are taken. For each scenario, five retreat distances such as 100, 125, 150, 175 and 200 m are considered for detailed investigation. The development of vertical displacement in gateroads, vertical stresses on barriers, vertical stress concentration factor, abutment zone and yield zone for longwall face are extracted and analyzed. Also, the safety factor of the barrier and longwall face is estimated considering the Hoek–Brown rock mass failure criterion. From the study, it is observed that the maximum vertical displacement of 121 mm in TG3 at scenario 3 for a retreat distance of 200 m and a minimum vertical displacement of 33 mm in TG2 for a retreat distance of 100 m at scenario 2. The development of vertical stress on the barrier is found to be between 8.78 and 13.40 MPa, and the safety factor of the barrier lies in between 1.56 and 1.80. The study also revealed that the yield zone at the longwall face lies within 2 to 3 m.

Dec 29, 2023

By S. Lähteenmäki, P. Koivistoinen, J. Levanaho

Semi Autogenous Grinding (SAG) circuit is the most common grinding circuit to day. In Europe and South Africa fully autogenous (AG) circuits are also popular. SAG circuit has a lower capital cost and simple operation. SAG circuit requires the use of grinding balls, which increases operating costs and decreases availability. An AG circuit may produce a higher Net Present Value to the investment. The AG circuit is more complex to design and operate. However, operating experience from AG circuits illustrates that an AG circuit can be as trouble free as a SAG circuit with the benefit of lower operating cost.

Jan 1, 2001

By Y. H. C. Wang

A detailed study of carrier flotation of kaolin clay using calcite showed the major beneficiation mechanism to be enhanced aggregation between anatase and calcite under intense agitation conditions. In order to develop an understanding of this selective aggregation, surface charge characteristics of kaolinite, anatase and calcite were studied under simulated flotation conditions. Zeta potential of all these minerals tended towards a constant negative value in ole- ate solutions under certain conditions possibly due to adsorption or precipitation of oleate on them. However, whereas the zeta potential of anatase in the oleate solutions was not influenced by the agitation level, that of kaolinite was found to be strongly dependent on the agitation intensity. The effect of oleate on zeta potential of kaolinite was reduced by an increase in agitation intensity. It is suggested that oleate is much more firmly bound to the surface of the anatase and that this preferential attachment is responsible for the enhanced selective aggregation of the anatase with calcite. Agitation level plays a major role in carrier flotation since intense agitation is considered to en- hance both the chemisorption of oleate on anatase and preferential detachment of calcium oleate precipitate from the kaolinite surface, all of this producing a large difference in the surface properties of anatase and kaolinite, and hence in their tendency to aggregate with calcite.

Jan 1, 1981

By Richard Addison

Introduction A staccato beat rings out across the Australian bush. The stamps are at work, slowly pulverizing gold-bearing ore for a patient, grizzled prospector. This is the State Battery near Marvel Loch, a tiny 22.6-t/d (25-stpd) capacity gold plant operated by the Western Australia government. It is one of many such plants located in remote corners of Western Australia and the Northern Territory. They are miniature custom mills operated for the benefit of prospectors and small mine operators. These state batteries are so called because they are operated by state governments and because the principal item of machinery in the plants are stamp batteries. They are fascinating anachronisms - throwbacks to times past, a century ago, to the hard and heady existence of gold rush days. Marvel Loch plant Typical of these operations, and perhaps a trifle more sophisticated than most, is the plant near Marvel Loch, a small center for mining and farming about 400 km (250 miles) due east of Perth. Marvel Loch. The name evokes visions of a pristine lake set in a cool, green, misty glen of the Scottish highlands. Actually, it is probably a hot, dry salt pan somewhere nearby. Just where the "loch" is difficult to discern. There is no sign of it on the map.

Jan 7, 1986

By Noriyuki Fujii

It is no need to say that exploitation of industrial minerals has a close relation to development of the industries related. In the first stage, a small scale manufactures were initiated in areas producing some main raw material minerals. China and cement manufactures, for example, were established depending on the local occurrence of raw materials such as kaolin and limestone without exception. That is, the industrial development is greatly influenced by the local production of the raw materials in the stage. With the development of industrial technology, various kinds of raw material minerals are explored to meet the demands of industries in the second stage. New materials become indispensable, and low-grade raw material minerals, which were left as useless, are developed as useful materials. In the stage, the development of raw material minerals is accelerated by that of industrial technology related. However, industries mainly rely on domestic production of the min raw material minerals.

Jan 1, 1981

By Mario Eduardo Rossi

The Universal Kriging (UK) and the Ordinary Kriging (OK) systems of equations are variations of the well-known system of Normal Equations. They differ only by the number of constraints present in the system. The dual version of these sytems enables one to interpret kriging as the fitting, of an interpolation surface, whose components are a series of variogram functions plus a polynomial trend model. This trend model should account for any systematic decrease or increase of the variable over the study area. It is shown that modeling the trend is useful only when the locations being estimated are beyond the range of influence of neighboring data (extrapolation cases). A case study based on a public-domain coal data set is presented. The variable described (seam thickness) shows an actual trend of increasing data values towards the NW corner of the region considered. UK and OK are used to estimate coal thickness at locations within sample data range (interpolation cases). The UK algorithm that includes a model for the trend does not improve the estimation when compared to the simpler OK algorithm with no trend model. Thus, in interpolation situations, the simpler OK algorithm is recommended.

Jan 1, 1989

By Russell K. McFarland, Eugene L. Foster

INTRODUCTION The U. S. Department of Transportation has underway an important new program which will have a major impact on rapid excavation technology. The Transportation Tunneling Program, as it is called, is a coordinated, multi-modal research and development effort. Its goals, if realized, will significantly improve our ability to build the underground structures needed for transportation. This, in turn, will improve transport efficiency, environmental impact, and the energy consumption associated with the movement of people and goods. Tunneling technology research and development had its beginning at the Department of Transportation in the Office of High Speed Ground Transportation (OHSGT). The OHSGT developed and implemented a program in 1965 to provide the technology for underground construction needed to support future high speed ground transportation. In 1967, when the OHSGT was transferred from the Department of Commerce to the Federal Railroad Administration (FRA), the program accompanied that office. The thrust of the FRA program has been cost reduction through the development of new materials, innovative designs, and better construction methods. During the late 1960's and early 1970's, other developments were underway which would influence the future of tunneling research at the Department of Transportation. An ad hoc

Jan 1, 1974

By R. C. Babcock

Exploration for mineral deposits in the western United States is increasing annually, and the data generated by this effort are increasingly complex, diverse, and abundant. It is obvious that to make full use of this data base, which is both private and public, the technology of the computer must be involved. To lay out the framework for discussion of the particular uses of computers in all steps of exploration, this chapter will discuss the various approaches to the reconnaissance program which might be considered, the types of data to be acquired, the interpretation of these data, and the generation of recommendations based on this interpretation. Where possible, some of those areas where computer technology is now used will be pointed out. The discussion will cover the extent to which the computer is now utilized in those areas or where it should be brought into the program to aid in these activities. However, this chapter will not present an exhaustive evaluation of this technology, but will stress the exploration job and its requirements, so that subsequent discussion of the technology itself can be placed in perspective.

Jan 1, 1979

By G. Kritikakis

Rehabilitation of sites contaminated by oil products and chlorinated organic compounds is a costly task which affects the planning of urban and infrastructure development. An integrated approach based on the non-invasive geophysical technology is utilized for subsurface characterization of contaminated land. In this approach the localized information, provided by chemical analysis of soil samples collected from bore-holes, is used for the calibration of the geophysical data. This information is subsequently extrapolated to the area under investigation by combining it with the geophysical results, providing thus information about pollution accumulation, contaminants? flow and pollution sources. Two case studies are presented from sites contaminated by heavy metals (Venice, Italy) and oil products (Athens, Greece). Resistivity, electromagnetic and seismic methods were used in this approach. Namely, electrical tomography, electromagnetic mapping, ground penetrating radar (GPR), multichannel analysis of surface waves (MASW) and seismic refraction experiments were conducted. In Italy, the sections from the multichannel analysis of surface waves imaged successfully a buried channel where the pollution is concentrated. Preliminary results are also discussed from the geophysical survey in Greece where the thickness of the oil phase located on top of the water layer is 60 cm.

Jan 1, 2006

By Pedro Sanchez-Mejorada

Laguna del Rey is the name of a dry lake bed located in the State of Coahuila, Mexico in a semi-desertic terrain typical of the basin and range physiography. Química del Rey, S.A., a subsidiary of Industrias Peñoles, has been producing sodium sulphate since 20 years ago, from brines pumped from the sub-surface of the present playa. The spent brine is used as raw material for the production of magnesium oxide. An extensive, lenticular deposit is found just below the playa. It consists mostly of glauberite (sodium-calcium sulphate) and blöedite (sodium-magnesium sulphate). The glauberite occurs as thin crystals oriented at random and leave many void spaces among them. These intercrystalline spaces are partly filled with mud, but the whole mass of the evaporite is still very porous. A brine that contains in solution ions of sodium, magnesium, sulphate and chlorine occupies the voids of the sponge-like evaporite body.

Jan 1, 1984

By Karl A. Olsson

The Glenharold Mine is a surface mine operated by Consolidation Coal Company. The mine is located approximately 90 kilometers (55 miles) northwest of Bismarck, and 3 kilometers (2 miles) southeast of Stanton in west central North Dakota. Glenharold has a nominal design capacity of 3.0 million metric tons per year (3.3 million short tons per year). With the exception of local coal sales, this production supplies fuel for Basin Electric's Leland Olds generating station, a mine mouth power plant. The mine has 175 hourly and 50 salary employees. The Glenharold reserve extends over 210 square kilometers (80 square miles). The mining area is on a dissected plateau between the broad flat Missouri River flood plain to the north and the gently rolling uplands to the south. Erosion by intermittently flowing streams has produced many narrow, steep-walled, drainage ways. Mining begins at the 6 meter (20 foot) cover line and continues to the economic recovery line.

Jan 1, 1982

By Peter J. Huck, Swpan Bhattacharya, Madan M. Singh

This paper reviews the state-of -the-art techniques for estimating the duration of post- mining subsidence arising from different mining techniques and evaluates existing post-mining liability systems in the United States and abroad. For each mining technique (room-and-pillar and longwall) the mechanism of subsidence development is examined and the critical factors influencing the duration of subsidence are evaluated. These are followed by a comprehensive summary of field data on the duration of subsidence movements collected in various parts of the world. Using this information, graphical charts are developed to depict the relationship between the time duration and critical controlling factors. Also included are any mathematical relationships that may exist between the different variables. Finally, a survey of current state, federal and foreign legislation on mine operator liability time spans is provided. These laws are evaluated for their applicability in light of the data on duration of residual subsidence. On the basis of this evaluation, guidelines are suggested for the establishment of the mine operator liability structure for the United States.

Jan 1, 1986

By Gail I. Bakker, Mark E. Smith, George Sintay, Allan Young

The Snow Caps mine was an open pit and conventional cyanide heap leach gold project located 10 Km east of Independence, California in the Owens Valley. The project is unique in that it is one of the first projects to go full-cycle, from design through closure, under California's Chapter 15 mine waste regulations adopted in 1984. The property was acquired by Sunshine Mining Company in 1985. During 1986, final design and permitting were completed and the facility was commissioned in 1987. Mining continued to mid - 1990, when the minable ore body was depleted, and heap leaching continued into early 1991. Rinsing of the spent ore was completed in 1991, and final closure will be complete in 1992. The spent ore will be left on the leach pad for its final disposition. The focus of this paper is the permitting and closure aspects of the project as required by California's Chapter 15, Article 7 regulations.

Jan 1, 1992

By P. A. Plunkert, D. E. Morse, L. McCartan, S. F. Sibley

Following the recession of 2001, restrained consumer spending, declines in domestic manufacturing and industrial output, and increased unemployment led to a lack-luster year in the domestic economy. In 2002, the U.S. real gross domestic product (GPD) grew only 2.4%. Significant production declines in the U.S. metals industry were registered by copper, lead and zinc producers. Steel producers, despite a slight improvement in shipments, continued to face strong foreign competition, higher energy costs and lower prices for their products. Homebuilding and other domestic construction sectors— major consumers of nonmetallic mineral products such as cement, brick, glass and stone — remained strong enough to help raise the output of industrial mineral materials slightly above 2001 levels. A strong U.S. dollar relative to other national currencies continued to weaken the competitive stance of U.S. metal and non-metal mineral materials companies alike against foreign producers in markets at home and abroad.

Jan 1, 2003

By T. M. Campoy, J. R. Jones

When extending the life of an existing mine in Appalachia, it is common to acquire the adjacent reserves and extend the existing mine into it. The existing mine is often renovated to accommodate the new conditions. The existing mining system and the track and belt haulage systems may he modified while the new property is integrated into the old one. All of these changes create new constraints for the mine ventilation system (MVS) that require proper planning and control procedures. This paper presents a study that was carried out for the ventilation system of a newly expanded underground coal mine in the Appalachian region. The process of correcting the ventilation system of the existing mine is discussed. That is followed by a discussion of some of the stages of controlling the expanded system. Numerical data for these steps are also presented.

Jan 1, 1994

By J. E. Hoffman, Corby G. Anderson, T. J. Keefe, O&apos, Suzzann M. Nordwick

Antimony removal has become necessary as it is commonly found in precious metal refractory ore bodies. The Sunshine Mine in Kellogg, Idaho has recovered metallic electrowon antimony from its argentiferous tetrahedrite (Cu2S'Sb2S3) deposits for over fifty years. Recently, Sunshine conducted an intense research effort to improve and modernize its antimony facility. This paper presents information which was learned about the antimony electrowinning processes and the development of a single¬-electrolyte antimony electrowinning technology. The relevant effects of process variables were investigated. The research results and the relevant chemistries involved in metallic antimony electrowinning will be discussed.

Jan 1, 1993

By R. Sawyer, M. Sadler, M. Holdworth

Greens Creek is a high grade Ag/Au/Pb/Zn deposit located in southeast Alaska. Maximizing the Net Smelter Return revenue from the fine grained mineralization is a dynamic process given changes in metal prices, smelting terms, ore grades and flotation characteristics. This paper discusses the evolving concentrate production strategy, and how it is affected by such factors as ore and concentrate specifications and by market conditions. Also described is the development of an on-line computer program that provides the mill operators with real time NSR data and a means for optimizing Net Smelter Return.

Jan 1, 2002