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By P. G. Semple, K. W. Major, R. M. Nendick

As free milling oxide gold ore reserves are depleted, more mining companies are having to evaluate the available alternatives for treating refractory deposits. The selection of a treatment process can be very difficult; and, despite the claims of their respective proponents, there is no one process that will continuously prove superior. Selection of the optimum process for an individual deposit is contingent on the size of the deposit, the grade of the deposit and the refractory nature of the ore. Since extensive metallurgical test programs are usually required to determine the optimum extraction process, an inappropriate initial selection may prove costly and time consuming. This paper discusses the steps involved in evaluating a refractory ore in order to expedite the evaluation of the required process through the feasibility study stage.

Jan 1, 1990

By D. D. Harbuck

Previous studies at the US Bureau of Mines (USBM) have shown that only 70% to 80% of the germanium in domestic zinc process residues can be extracted during H2S04 leaching. To increase germanium extraction, the USBM developed and researched the hypothesis that minor amounts of germanium and zinc silicate, present in zinc calcine, dissolve during the leaching stages of zinc processing, forming soluble germanium and silica gel. This silica gel then selectively adsorbs germanium from solution, rendering the germanium insoluble. Testing showed that as the amount of formed silica gel increased, the amount of insoluble germanium in the zinc residue increased. Several processing alternatives are presented for overcoming this problem.

Jan 1, 1994

The modelling process described in this paper was developed in order to assess the feasibility of various investments options for the exploitation of a lignite deposit located in the Prefecture of Florina, Greece. The model uses as evaluation criterion the net present value. It is based on the characteristics of the reserves and relates the decision making with numerous technical, economic and environmental factors. The examined alternatives include the construction of a new thermal power plant at the mine-mouth, the fuel supply of already existing power plants located at relatively long distances and the fuel exports in neighboring countries. Moreover, the feasibility of post-poning the exploitation of the lignite deposit and preserving its reserves for exploitation in the future is also assessed. The paper also includes a short discussion about the environmental constraints related to the supply of lignite produced from Florina mines to power plants that were designed and constructed for burning fuel mixtures with different quality characteristics.

Jan 1, 2005

By S. Kmet, A. Nguyen-Van, H. J. Schulze

The P/B collision and attachment interactions in fine particle flotation have been quantitatively analyzed. New models for attachment probability and kinetics of ‘true flotation’ have been developed. The results are given for both a single bubble and a bubble swarm. The mechanism of the attachment event is also examined. It is shown that (i) impact collision mechanism and rolling mechanism can be ignored in actual fine particle flotation and sliding mechanism is of importance for attachment of particle onto the bubble surface (ii) the attachment probability of fine particles is independent of bubble size and determined by the kinetic measure induction time of hydrophobicity. The theoretical predictions are also compared with the experimental data.

Jan 1, 1995

By G. D. Hood, B. E. Davis

A fundamental study of the mechanisms involved in the conditioning of coarse Florida phosphate has led to some interesting discoveries. Studies by the US Bureau of Mines have shown that conditioning time and mixing intensity greatly affect the grades and recoveries of the phosphate minerals and quartz in the rougher concentrate. In particular, as the conditioning time or mixing intensity increased, the phosphate recovery remained constant while the amount of quartz floated decreased. This phenomenon is contrary to conventional wisdom and could lead to a more efficient coarse flotation circuit.

Jan 1, 1995

By Schebek, J. Warsen

"Data and information from sustainable development (SD) reports can be seen as a promising and easily accessible source for an Life Cycle Assessment (LCA), i.e. for generic Life Cycle Inventory (LCI) data in particular. The reliability and comparability of LCA results crucially depends on the quality of LCI data, that is defined by specific normative requirements. In parallel the GRI (Global Reporting Initiative) provides a set of guidance documents for enhancing the quality, rigor, and utility of SD reporting with specific reporting principles that address similar issues on a company level comparable to LCI data quality requirements on the process level. In order to assess the general suitability of the fundamental reporting principles for LCI data quality purposes selected reports from mining and minerals (M&M) sector are assessed within a detailed analysis."

Jan 1, 2005

By J. G. Groppo, D. J. Sung, B. K. Parekh

Hyperbaric filtration for the dewatering of fine coal cleaned by froth flotation was evaluated on a laboratory scale. A laboratory pressure filtration procedure designed to obtain a uniform cake structure from dilute slurries containing a significant amount of coarse material is described. Baseline tests were conducted to determine the optimum operating conditions for the eventual application of the process to a continuous pilot-scale hyperbaric filter. Investigated were filter operating parameters such as driving force, time, cake thickness, percent solids, viscosity and pH.

Jan 1, 1996

By O. E. Etheridge Jr., R. A. Lowe, C. I. Basilio, J. M. Randolph, S. W. Sheppard

The low-shear viscosity of kaolin slurries is one of the principal characteristics that determine whether a clay can be utilized for paper and ceramic applications. In this work, the causes of high low-shear viscosity and methods for improving the rheological behavior of the slurries were investigated. The presence of fine-grained smectite impurities within the kaolin was shown to detrimentally affect the low-shear rheology of the slurries produced from these clays. It was also shown that mechanically working (i.e., pugging) a crude kaolin followed by desliming to remove these impurities can reduce the low-shear viscosity.

Jan 1, 2000

By Barbara C. Schickner

No group has been harder hit by the problems confronting the coal mining industry than small, independent surface mine operators in the eastern US. Burdened by costly government regulations, major capital shortages, declining productivity, high unemployment, and idle and closed mines, many in the industry think the breed will not be able to survive much longer. But there are a few sole owners fighting to remain independent-and succeeding. John Wagner is running a coal stripping operation in northwest Pennsylvania on a unique blend of aggressive management and marketing, support from a team of blue-chip professionals, and some unusual tactics. Though Wagner's approach is hardly an across-the-board formula for survival-he is currently reorganizing under Chapter 11 of the Bankruptcy Reform Act-a look at his operation helps illustrate some of the unique problems confronting eastern surface miners.

Jan 2, 1980

By Jan K. Wolski

Detection of the air recirculation branches within a large ventilation network may be difficult, therefore a PC computer routine has been developed to perform this task in an efficient and reliable manner. This paper describes the method illustrated using a network with complex multi-recirculation circuits. The fact that only the air flow directions and not the flow rates are used in calculations is of some interest. The air recirculation during a real mine fire is demonstrated using the PCVENT program, whose version 4.0 includes current information about any recirculation branches during network calculations or during a fire simulation. This paper also discusses some transient problems related to air recirculation, and gives examples.

Jan 1, 1993

By C. Alexander

Stillwater Mining Company is developing a second underground palladium and platinum mine approximately 21km (13 miles) west of their existing Nye operation in south central Montana. A 5650 meter (18,550-foot) tunnel is required to gain access to the ore bearing horizon (J-M Reef). Access and primary mine development can be accelerated through the use of two 4.6 meter (15-foot) diameter tunnelboring machines (TBM). One TBM was purchased new while the other was purchased used. Machine specifications, site support facilities, portal/launch chamber construction, TBM assembly, startup and operation are discussed in this paper.

Jan 1, 1999

By V. Saltas

The present work investigates whether dielectric spectroscopy can be used to detect contamination, which may appear in a natural porous material, due to the spreading of pollution. For this purpose, dielectric and conductivity measurements, in the frequency range of 10mHz to 1MHz, were carried out in sandstone samples, partially filled or saturated with solutions of leachates, at different concentrations. The experimental results suggest that although the role of water is dominant to the measured electrical conductivity, variations of two orders of magnitude are observed due to the different concentrations of leachates, in partially filled sandstone samples. Experimental data are well fitted with a Havriliak?Negami dielectric relaxation function, superimposed with a conductivity term. The parameters of the fitting function have been correlated to the concentration of leachate in the sandstone samples and considerable changes have been observed at low leachate?s concentration.

Jan 1, 2005

By J. Craynon, M. Karmis

Previous papers by the authors have presented a systems-engineering approach based on the premise that systems can only be optimized if all factors are considered and integrated into mine planning. This paper discusses the challenges inherent in optimizing the design of large-scale surface coal mining operations in Appalachia. Regulatory and permitting programs in the United States often focus on single parameters, rather than the full suite of desirable outcomes for sustainability. By utilizing geographic information system (GIS) tools to evaluate available data on environmental and social resources, the regulatory barriers which prevent operations from incorporating ecological and other sustainable development concerns into coal mine sustainability performance were identified. By analysis of the on-the-ground issues related to sustainability, the key parameters to be incorporated into an optimized coal mine design in Appalachia are discussed along with possible changes to the regulatory framework that would enhance incorporation of sustainability into coal mine design.

Jan 1, 2011

By A. A. Sonntag, I. Szanto, D. A. Goodman

This paper presents the most recent developments in mixer-settler technology directed towards treating higher throughputs, increasing efficiencies and providing further improvement in SX technology with a new concept: the submerged launder. Industrial plants built in the last past few years and using these improvements are described.

Jan 1, 1993

By Jean-Michel Rendu

Electronic data processing' is becoming a necessary part of all large mining operations. Accountants, geologists, mining engineers, samplers, and truck drivers are needed to operate a mine. So appear to be systems analysts, computer operators, and software engineers. Trucks, loaders, and drills must be used to extract useful material from the ground. So must be mainframe and microcomputers, plotters, digitizers, and computer terminals. The papers presented in this section describe experience gained in Europe, Australia, and North and South America. The mining and data processing environments and the size of the companies vary significantly, but the conclusions drawn are often strikingly similar. Common answers to often-asked questions can be summarized as follows: - Why invest in data processing? The main reason is that information systems can supply accurate and timely information for better decision-making. Other reasons are mentioned including, to speed-up the processing of large volumes of information, to perform operations which cannot be performed manually, or to reduce costs. But all of these reasons appear ancillary to that of supplying accurate and timely information.

Jan 1, 1989

By M. C. Manderson

While the United States has been the world's largest volume producer and marketer of phosphatic fertilizers for many years, it has recently suffered heavy losses for a variety of reasons. While improved economic performance is expected, it is still at least a year or two away. But when recovery does manifest itself, it will likely yield only mediocre profits, due in part to the fact that about 50 percent of output is export-dependent. Therefore, there appears to be limited likelihood that profits will be adequate to justify the further outlay of large amounts of capital for expansion.

Jan 1, 1986

By G. Belardi, N. Sheau, P. Plescia, F. Veglio

A study was conducted to assess a new wet gravity-separation machine, identified as the Multi-Gravity Separator(MGS). Chromite fines, obained from an Albanian chromite and olivine ore and containing 23% Cr2O3 and 18% SiO2, were used in the study. The first step was to determine the influence of various operating parameters. The study indicated that the most important variables for the MGS are rotational speed, tilt angle and shake amplitude. The best treatment conditions for the ore were then identified by investigating a series of circuits designed to produce a marketable product. In open circuit, a concentrate containing 50% CI-203 was obtained with a recovery of 72%.

Jan 1, 1996

By G. Wang

Industrial minerals processing has gained importance lately, not only due to its wide range of new and regular applications in processing different industrial minerals, but also due to the strict specs under which products are commercialized. Among the processes applied to industrial minerals, flotation is a leading technology. The laboratory study and commercial operation demonstrate that the sulfonated reagents are very effective collectors for industrial minerals. This paper compares synthetic petroleum sulfonate with fatty acid on iron reduction in glass sand processing and describes the effect of conditioning pH on iron reduction using synthetic petroleum sulfonate as collector, the effect of molecular weight of natural and synthetic petroleum sulfonates on their flotation performance and the enhancement made for certain products.

Jan 1, 2011

By Pieter C. van Aswegen, J. A. Brierley, C. L. Brierley

The bacterial-oxidation (BIOX®) process for the pre-treatment of refractory ores for gold recovery is marketed by BlOMlN Technologies S.A. The process was originally developed by GENMIN who is still providing testwork, design and commissioning assistance to BIOMIN. Since 1986 three BIOX® plants have been commissioned by GENMIN. A further two plants will be commissioned during 1993 and 1994. The commissioning and operational experiences from these plants are described in the paper.

Jan 1, 1993

By Gu Guohua, Hu Yuehua, Zhang Qin

The flotation behavior of pyrrhotite was investigated by using ethyl xanthate as a collector. Results showed that pyrrhotite had good floatability from pH 2 to pH 11, and poor floatability when pH was >12. The flotation of pyrrhotite was dependent on pulp potential on various pH values. The potential-pH range for pyrrhotite flotation was established. Cyclic voltammeny and FTIR spectroscopic analysis showed that the major adsorption product of ethyl xanthate on pyrrhotite was dixanthogen. The intensity of FTIR signals of dixanthogen adsorption on pyrrhotite and the anode current of a pyrrhotite electrode and flotation response of pyrrhotite are correlated with pulp potentials.

Jan 1, 2005