Search Documents

By C. A. Garcia

The solvent extraction of gold cyanide from alkaline cyanide solutions with monosubstituted guanidines, bis disubstituted guanidines and a tetrasubstituted guanidine was investigated. The guanidine functional group is protonated in alkaline solution and the guanidinium cation is stabilized so that the aurocyanide anion can be extracted even at -pH 12 if an appropriate carrier is used. Typical aprotic carriers including both aliphatic and aromatic solvents limit gold extraction by guanidines to pH 10; whereas the presence of an alcohol extends gold extraction to pH 12. UV spectroscopy suggests that the alcohol facilitates protonation of the guanidines, stabilizes the guanidinium cation, and facilitates gold extraction at high pH.

Jan 1, 1993

By G. Tapia, R. J. Kelley

Empresa Minera de Mantos Blancos S.A. successfully commissioned two copper SX-EW plants in late 1995. The design of these solvent extraction plants is such that chloride tenors of 30-35 g/l can be tolerated in the leach solution with no contamination of the electrolyte. The design was carried out in conjunction with Bechtel-ARA engineers and was based on the successful application of the available technology in the market; this mainly focused on decreasing the aqueous entrainment in the organic phase. This entrainment can reach 20,000 ppm in conventional plants.

Jan 1, 1998

By Eric Monrad

Discrete event simulation modeling provides a tool to quantify the throughput capacity of stockyards. Interactions between the main equipment types (trains, dumpers, conveyors, stackers, reclaimers, shiploaders) can be captured, including route blockages, breakdowns, and planned maintenance. Simulation has been successfully used at world-class stockyard facilities to determine current capacity and to identify gains resulting from improvement projects. Recent projects have focused on iron-ore, coal, and soya facilities, but the technology is suitable to be used on any bulk material type.

Jan 1, 2008

By Tim O’Neil

Big and getting bigger. Barrick Gold Corp., the third-largest gold producer in the world, began production in September — ahead of schedule — at its Meikle Mine. At a scheduled full production rate of 12.4 t/a (400,000oz/year), it will be the largest producing underground gold mine in the United States. The $180-million Meikle Mine is located on Barrick’s Goldstrike property in Nevada and has 205 t(6.6 million oz) of gold reserves. The compact Meikle deposit has an average ore grade of 23 g/t (0.68 oz/st), making it one of the highest-grade mines in the country.

Jan 1, 1996

By A. McCombs

Previous models describing the aggregation of polymer-coated particles fail to take into account the fact that there are a limited number of sites onto which a polymer segment can adsorb, called "active" sites. Thus, the collision efficiency is a factor not only of the fractional surface coverage, but also of the number of active sites. In this study, a physical model of the flocculation system was devised in which the number of these sites could be varied, in order to study the effect on particle aggregation.

Jan 1, 1988

By Bob Clayton, David Readett

Jameson Cell technology has found applications in the cleaning of entrained material in copper Solvent Extraction - Electrowin plants. The materials involved are largely organic substances that have not been totally removed prior to treatment of the rich electrolyte in the tank house. This paper discusses the recovery of the entrained organics in the rich electrolyte streams at Phelps Dodge Morenci in Arizona. Mount Isa Mines in Queensland. Australia and the Olympic Dam Operations in South Australia. The paper details the design, performance, the feed and product characteristics, capacity and operation. In one operation the entrained material has been observed to include crud that has been formed in the SX train. The mechanism of recovery is also discussed.

Jan 1, 1993

By Jerry W. Danni, John E. Hardaway

Corporations today must comply with an ever growing number of complex and increasingly stringent environmental laws and regulations. An environmental audit program is an effective means in which to uniformly and systematically assess compliance, and to assure management that environmental liabilities are being minimized. This paper describes the design and implementation of Homestake Mining Company's environmental audit program, which has as its primary focus the objective verification of compliance with external requirements and internal good management practices. Major elements of the audit program discussed in the paper include: pre-audit preparation; on-site audit activities; and the post-audit report.

Jan 1, 1992

By Don L. Jensen

With the successful implementation of supervisory control on the Bagdad concentrator grinding circuits, steps have been taken to expand supervisory control to the flotation circuits. This paper discusses the design and installation of the slurry delivery systems, analyzing instruments, level control devices, reagent pumps and supervisory software. Emphasis is placed on the design and installation of a reliable slurry transport system to feed the Courier 30 online analyzing instruments. Total system availability has been measured at plus 95%. Phase 1 acceptance testing of the supervisory software indicates a notable increase in copper recovery with no significant change in final copper grade.

Jan 1, 1999

By Michael L. Nave

An existing coal mine's raw coal 60 inch conveyor system had become productivity bound by a capacity of 3,500 tph. The existing conveyor drives were fixed speed wound rotor induction motor drives installed in 1983. The fast track upgrade installed variable speed medium voltage variable frequency drives to speed up the conveyor to a capacity of 5, 000 tph. The installation took place over a one week system shutdown during Christmas 2000.

Jan 1, 2002

By N. L. Anderson, R. Ramananantoandro, F. Wirnkar

Six-fold, high-resolution, compressional-wave seismic data were acquired across a coal mining property in the Meigs County study area, southeastern Ohio, with a view to differentiating the Clarion Coal Member and a truncating channel sandstone prior to longwall mining without costly drilling. The seismic technique, as is illustrated by our example data, was successfully used to map those areas where the coal is present, as well as those places where it was eroded by incising fluvial streams. Our results demonstrate that the seismic reflection method, using an engineering seismograph, can be a cost-effective way to define discontinuities associated with coal seams.

Jan 1, 1992

By Andrew J. Neale, Mark Franklin, Mike Cooper

Although recent advances have significantly improved our understanding of flotation fundamentals, disturbance variables combine to make it difficult to maintain steady state operating conditions over either the short or long term. One of the major concerns relates to knowing how much reagent to add to the flotation system, how to monitor the addition rate, and how to determine when to adjust the reagent addition rate in the presence of these disturbances. This paper will look at the development and installation of process control systems that address these issues. The economic benefits that accrued from the implementation of these strategies is described.

Jan 1, 1994

By Hassan El-Shall, Abbas A. Zaman, Brij M. Moudgil

The addition of organic and inorganic dispersants to aqueous suspensions of heterogeneous particles (kaolin) was found to significantly affect the solubility of metal ions from kaolin particles and stability of the dispersion. In most of the industrial applications of kaolin, highly concentrated slurries of controlled stability and fluidity are required. The solubility of kaolin particles in terms of aluminum and silicon ions and its effect on the stability of the slurry was investigated. The main objectives of this study were (1) to study the effect of the extracted metals on the properties and performance of the slurry, (2) to understand the reaction mechanism of dissolution of metals from kaolin, and (3) to understand the interaction mechanism of dispersants with kaolin particles. The controlling variables were dispersant dosage, slurry pH, solids loading, and aging.

Jan 1, 2003

By A. J. Monhemius, R. G. Reddy, G. W. Warren, E. Peters

Thermodynamic solubility of chromium in pickling solutions (i.e., HF- HN03-H2O solutions) was determined as a function of HF and HNO3 acid concentrations at 298K. Pure Cr, AISI type 316 and 416 stainless steel were used in this study. The results showed that the solubility of Cr increased with increase in the concentrations of HF and HNO3 acids in solutions. The solubility of Cr increased in the order of pure Cr > 416 SS > 316 SS. The theoretically calculated Cr solubility data were in reasonable agreement with the experimental data.

Jan 1, 1993

By Robert Dunne, John Angove

The physical properties of an ore body require determination for virtually all mining projects, new and existing. The extent and regularity of such determinations being subject to the size and homogeneity of the orebody. Such properties have an impact at the design stage of new plants, with respect to equipment specification, and thus effects capital costs; and also impacts on the operating costs of new and existing plants, with respect to power consumption, production levels and part replacements. All of these can severely alter the bottom line and can be the determining factor in the economic viability of many projects. This paper examines some of the most common properties that are measured, the procedures utilised in determining these properties, and their variability under conditions of reproducibil­ity, and to a lesser extent repeatability. The properties looked at were Impact Crushing Work Index, Abrasion Index, Bond Rod Mill Work Index and Bond Ball Mill Work Index. A number of testing laboratories throughout Australia and the US were utilised in the survey. The results showed up some interesting and important features of the procedures used, all of which have become accepted industry standards, and which had varying effects on the final result. Tests such as the rod and ball mill indices would appear to have reasonably robust procedures which allowed for the determinations of the respective index without the introduction of significant variations, although there were indications that variations could occur. The other tests gave a sufficiently different picture to be able to suggest that an argument could be made for a more intensive investigation to be undertaken, with the possible outcome that a modified test procedure or an alternative test is required.

Jan 1, 1997

By A. C. Nixon, A. D. S. Gillies, Hsin Wei Wu

Ventilation and refrigeration strategies for the 3000/3500 orebodies, Mount Isa Mines, Australia were reviewed. The orebodies lie between 1,200 and 1,800 m below surface and are characterised by steep geothermal gradients, intensively mechanised stoping methods and high ambient air temperatures in summer. Providing acceptable working conditions under these situations is difficult and costly. The ventilation air quantity required in the 3000/3500 orebodies exceeds 550 m3/s when the production rate is greater than 2.5 million tonnes per year. The maximum quantity that can be supplied and exhausted using the existing intake and return ventilation system is estimated at about 630 m3/s. For production rates greater than 3 million tonnes per year, either new intake and return airways will need to be developed or innovative approaches such as controlled partial recirculation used. A description is given of technical and economic investigations conducted at Mount Isa into controlled partial recirculation. During these investigations, a major field trial of a controlled partial recirculation system was undertaken with results indicating that an acceptable working environment can be achieved practically and economically utilising this approach. The cost involved in controlled partial recirculation for supplying the required ventilation quantity when the production of 3000/3500 orebodies exceeds 3 million tonnes per year is examined. A cost comparison between recirculation and other conventional alternatives such as new surface shaft or underground booster fans is included. The results indicate that the option of a new surface shaft will incur a high initial capital cost and moderate annual operating costs. The alternative of underground booster fans will necessitate a moderate capital cost and very high operating costs. Controlled partial recirculation, in this case, offers both the lowest capital and operating costs of the three options evaluated.

Jan 1, 1995

By R. F. Holub, P. J. Dallimore

Basic to solving the problem of the role of radon transport on radon concentrations in mines is to establish whether it occurs primarily as diffusion and forced flow through porous rock or through fissures in the rock. The laboratory experiments performed involved measurements of diffusion and emanation coefficients, porosity and permeability of representative rock samples. Significant differences have been found when comparing the results of the laboratory permeability determinations to those of the mine determinations. Considerations of underlying principles, however, suggest that the diffusion and emanation coefficients are the same in laboratory and mine. It was also found that moisture content plays a dominant role in radon transport through rock. Using these concepts and findings, some conclusions about the radon concentrations in mines have been drawn.

Jan 1, 1981

By George H. Schnakenberg

The application of automation and robotic technologies to coal mining equipment at the face offers improvements in worker safety and efficiency. The evolutionary introduction of autonomous, intelligent machines to perform the most hazardous tasks in underground coal mines may become a reality within the next 10 to 15 years. The US Bureau of Mines Advanced Mining Systems research program is developing the technology necessary to achieve this goal. This program consists of both core and applications re¬search that focus on the fundamental issues of sensor-based, computer-assisted, machine control technology. In the near term, the research is directed specifically to the computer-assisted control of present-day underground equipment. The immediate effect will be relocating equipment operators to a nearby area of safety. It is being performed in a manner that can make incremental improvements in safety and efficiency. The research is being performed closely with private, government and academic researchers in the miring, space, armed forces and factory automation and robotics research areas. It is a mixture of basic research, applied research and the application and adaptation of existing technologies from a multitude of sources.

Jan 1, 1990

By A. E. Stewart

Slope design in an open pit mine includes determining bench height, bench face angle and berm width. Case histories are presented of two highwall slopes (160 and 220 m or 525 and 720 ft high) excavated in dipping strata in an op¬erating coal mine. These examples illustrate the influence that bench face angle can have on the stability of an entire slope. The two highwall slopes, the lower of which experienced significant instability, were excavated in approximately the same lithologic and structural environment. The main differences between the slopes were the angle at which the bench faces were excavated and the excavating methods that were used. Relevent aspects are also described of the engineering geology, slope design and excavation procedures.

Jan 1, 1998

By S. Y. B. Subbarao, K. Ravindranath

Lead and Zinc concentrates are being recovered at Rajpura- Dariba (Distt. Rajsamand, Rajasthan, India) from a complex multi metal sulphide deposit since 1984 by selective flotation employing a large number of reagents. The cost of concentrates' production has been high. Due to the increased availability of concentrates world over and to be competitive, it is necessary to reduce cost of production. An effort has been made by the R.D. Department of Hindustan Zinc Limited to bring down the cost by resorting to production of Bulk Pb + Zn concentrate with enough Ag to make it attractive to the smelters. This paper gives an account of open cycle testing and locked cycle testing in the Dowa Continous Mini Flotation unit. The metallurgical data generated in the mini flotation unit indicate the possibility of obtaining smelter-acceptable bulk concentrates containing Pb+Zn 45%, Ag 400 ppm and graphite carbon about 3%. An in-plant trial in the 3000 TPD concentrator indicated that there would be savings through dispensing with and reduction in some reagents, lower power requirement, etc. Also, a substantial increase in revenue is expected due to higher recoveries by resorting to bulk concentrate production as against individual concentrates.

Jan 1, 1995

By P. J. Ryan

December 1988, Phelps Dodge Corp. brought an underground gold mine into production in the republic of Botswana. The mineralization is associated with steeply dipping shear zones in Archean greenstones of the Tati schist belt. The gold is intimately associated with sulfides and is refractory in nature. The deposit is being exploited by underhand open stoping methods. Vertical and inclined shafts are used to hoist the ore to the surface where it is treated by conventional crushing, milling, and flotation, followed by fluid bed roasting with cip elution and carbon regeneration. Adjacent deposits are being explored with a view to increasing production. Legal and taxation aspects of operating in Botswana are discussed.

Jan 1, 1991