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By Felicia F. Peng

Two modes of collector addition techniques are applied in the column flotation for cleaning ultra fine coal. The collector can be: 1) added directly into the coal slurry through the feed system; and 2) gasified collector and transported in the gas phase through the bubbles. Operating parameters of the column flotation were investigated through three phases of work plans for Pittsburgh No.8 seam coal. In present study, the column flotation using two modes of collector addition techniques were tested and compared. Ninety percent or higher combustible recovery can be achieved by using both methods. However, utilizing the gasified collector addition technique in column flotation has more potential than direct liquid addition technique to obtain the higher recovery at same collector dosage.

Jan 1, 1993

By Frank Kitzinger, Jacques Nantel

Under special circumstances, electrical energy can successfully replace chemical ex­plosives for blasting rock. High pressure plasma can be generated in the confines of a drillhole, by a powerful electrical dis­charge. The energy level can be adjusted to replicate the effect of a high explosive. The main difference is the almost total ab­sence of gas generation with electric blast­ing. Once the rock fractures, the small amount of matter used for generating the plasma rapidly cools off and regains its former volume. High speed film studies clearly show, that the initial speed of blasted rock fragments is the greatest, no further gas propelled acceleration takes place .. Figure 1, shows a typical electric blast of an oversize boulder of quarzite in an open pit mine.

Jan 1, 1992

By H. N. McLeod, M. J. Thom

The use of cyanide in gold mining requires the careful handling and storage of cyanide rich tailings. Cyanide in groundwater can frequently be both persistent and mobile, so that tailings basins need to be designed to limit and collect seepage. Assessment of the potential environmental impact requires an understanding of the hydrogeologic regime, both before, during and after mining. Groundwater monitoring wells provide a basis for monitoring tailings pond behaviour and for assessing the impact of mitigative measures to reduce or control seepage. A case example of Cheni Gold Mines Lawyers Project in Canada is presented to illustrate the use of groundwater monitoring to determine the amount of cyanide degradation and attenuation between the tailings pond and the receiving environment.

Jan 1, 1991

By C. G. Bock

Geologic profiles constructed from exploratory drill holes gave basic geologic information for bidding on 4913 ft. of twin rock tunnels under the Potomac River. To provide additional geologic information for construction, tunnel faces and shafts were mapped throughout excavation. This information was plotted in plan and section so that geologic structure could be projected ahead and prediction of conditions could be made. In structurally complex areas, 3-D models were made and used to show the geologic structure. Core from exploratory drill holes was relogged and structure oriented with that found in the tunnels to make the ultimate use of the core and refine the geologic picture. As excavation proceeded, geologic mapping showed that the projection-prediction approach was useful and essentially correct.

Jan 1, 1974

By R. J. Essex

In support of the Conceptual Design of a Nuclear Waste Repository in Salt, a confined core pillar design method developed by others was reviewed. The method, which was developed for applications in coal, represents the confined strength of the pillar material in terms of a linear failure criterion. However, triaxial compression strength tests conducted on salt samples indicate that a non-linear strength criterion is more appropriate for salt. The rationale behind the confined core method is reviewed. A rederivation of the confined core method is then presented that incorporates a non-linear strength criterion. Benefits of the modified method are that the strength of the confined pillar core can be more accurately represented, and that two contributors of pillar strength, rather than one, can be addressed.

Jan 1, 1988

By J. H. Lammers, John Turney

The Eskay Creek Project was interesting in many respects, includ­ing extremely high grade of precious metals, refractory nature of the ore, carbonaceous content of ore resulting in preg robbing, and high content of many heavy metal sulfides in addition to the usual iron sulfides. Although the process plant was never constructed, extensive testwork was conducted and a flowsheet for the treat­ment of the effluent form pressure oxidation was developed as a basic engineering package. The flowsheet included removal of iron and gypsum by neutralization, selective recovery of copper by zinc precipitation, and recovery of zinc by solvent extraction and electrowinning. The zinc recovery produced a significant impact on the project economics. The waste water from the process met the environmental requirements for British Columbia.

Jan 1, 1996

By M. Pantazidou

Motivated by recent EU legislation already entered into force or in preparation, this article aims at offering glimpses of the future landscape in the area of subsurface protection against contamination from point sources. Towards this end, it discusses the most salient parts of legislation for the protection of water resources. It then presents results from the wide consultation rounds organized by the European Commission in order to both receive input and help make all opinions heard on the issue of soil protection. Finally, it introduces key provisions of the recent legislation on environmental liability. From the above pieces of legislation, this paper highlights the elements that concern specifically the protection of the subsurface against spills of hazardous wastes from point sources and the requirements for subsurface restoration.

Jan 1, 2005

By G. S. P. Pereira, E. M. R. Santos

Acid mine drainage (AMD) is a serious environmental problem in mining activities. Prediction is the first step for evaluate the potential of acid generation and there are some possible methods to estimate it. They are described as static tests, which examine the balance between acid producing and acid consuming materials, and kinetic tests, which attempt to predict drainage quality overtime. Static methods are very simple and give a qualitative classification of the ores based on their potential to generate acid drainage. The characterization of ores to determine their acid producing potential is vital for the prevention of long term environmental liabilities. Laboratory tests were conducted under different methodologies to predict the acid producing potential of sulphide overburden, ore materials and tailings from a deposit of copper ore.

Jan 1, 1999

By G. Hilson

The exact application of sustainable development in the mining and minerals industry has precipitated considerable debate in recent years. Since the publication of the Brundtland Commission?s Report, Our Common Future, numerous attempts have been made to define sustainable development in the mining context. The inability of the Brundtland Report to outline an effective sustainability framework, combined with its contention that no single blueprint for sustainable development exists, has prompted many academics and practitioners to provide viewpoints on the application of sustainable development in the mining and minerals industry. This paper provides an overview of the many groups of assessments made of sustainable development in the mining industry. Sustainability assessment and reporting for this industry sector using indicators are also addressed.

Jan 1, 2003

By C. Vasquez, A. Nieto

In past drilling programs for a multi-seam Texas lignite reserve, extensive e-log data was collected; however, little laboratory analyses were performed. As a cost and time saving incentive, sampling of lignite was intensified. In a recent drilling program in east-central Texas, detailed laboratory analyses and e-log information was gathered on a multi-seam lignite reserve of the upper Wilcox Group. This data will undergo statistical and geostatistical techniques in an attempt to discern whether or not predicted Ash and Btu/lb values can be derived from the e-log gamma-density relationships. Final characterization of the dataset will be used in a geostatistical model of that reserve. This model will be the basis for further geological investigations and mine planning.

Jan 1, 2004

By Erich U. Petersen

Harbuck et al. (1990) present results of research on sulfuric acid leaching of a germanium-gallium ore and shed considerable insight on possible extraction methods for gallium and germanium. However, the presentation does not give sufficient details to evaluate the research, so some of the conclusions may not be as applicable as stated. The objective of this communi¬cation is to indicate that relevant and easily obtainable geological and technical information was omitted. Consequently, on this basis, alternative explanations for some of the data are possible. Discussed below are the omission of: • pertinent geological, mineralogical and geochemical literature; • details regarding the determination of germanium concentration in quartz by electron microprobe; and • details on the calculation of the amount of germanium locked in quartz.

Jan 1, 1992

By K. Nielsen, V. Bauer

"The paper presents a brief overview of the long mining history and the more recent political development in the Slovak and Czech Republics as well as in Norway and Sweden. Mining used to be very important sources of economic wealth in the four countries, but in today’s economy does exploitation of non-energy minerals usually account for less than one per cent of the GNP. The paper will discuss and compare the mining legislation, land use planning and mineral policies framework in the four countries and how this may influence sustainable management of mineral resources including planning for mineral supply, landbanks and sterilisation of resources. The paper will then identify some positive and negative elements in each country’s political and administrative framework."

Jan 1, 2005

By P. N. H. Bhakta, X. P. V. Lei

The U.S. Bureau of Mines developed an alkaline oxidative pretreatment to increase the recovery of gold from refractory sulfide ores containing arsenopyrite (FeAsS) and/or pyrite (FeS2). Pretreatment of a low grade ore containing 0.4% FeAsS, 3.5% FeS2, and 2.74g/mt Au with 1.2m NaOH, 40 psig o2, 100° C, and 4 hr in a 2-L autoclave resulted in 94 to 96% sulfide oxidation. cyanidation of the pretreated residue resulted in 88% Au extraction compared to <20% Au extraction for untreated ore. Cyanide consumption was 0.25 kg NaCN per metric ton of ore. A flowsheet for treating sulfidic low-grade gold ore is proposed.

Jan 1, 1990

By P. E. Sarquis, R. Lenzo

The concentration of barite by gravity separation generates substantial quantities of fine particle wastes, and it is estimated that =40% of the contained barite is lost to these waste streams. In this study, froth flotation was examined as a potential method for the recovery of fine-barite particles. The study included the use of kinetic equations to estimate the variables affecting flotation, batch-scale rougher flotation tests to study the flotation variables and an examination of alternatives for the cleaning of the rougher concentrate. Results indicated that a concentrate grade of 96.5% could be achieved with a recovery of 77.5%. Although barite flotation from industrial wastes is more difficult than direct barite flotation, the process has considerable economic potential.

Jan 1, 1996

By Risto Lindsberg

A wide concept of flotation equipment and technologies is presented in this paper. The basis for the presentation in Outokumpu&apos;s world-wide experience in mineral processing and other related areas, and continuing research and development work done in Finland as well as abroad by Outokumpu&apos;s subsidiaries (and customers). It is understood that flotation equipment selection for a certain process stage is becoming more complicated. It is obvious that flotation equipment in grinding circuit needs different design from a multistage cleaning process. In this paper, column flotation is compared with other flotation methods. Thus three areas of flotation are discussed in this paper: 1. Flotation in the grinding circuit, Skim-Air machines 2. Rougher-scavenger flotation, conventional cells vs columns 3. Cleaning flotation, columns

Jan 1, 1988

By A. Mahtab, S. Xu, P. Grasso, B. J. Fu

The large population base, complex geology of the large land mass, and notable commercial activity have accelerated the development of underground construction market in China. The projected lengths of underground openings per year in the various sectors are: hydro-tunnels, 180 km; coal mine entries, 40 km; transport-tunnels, 300+ km. An example of the mega projects (being planned by the Government) is the water supply scheme for connecting Yangtze river to Yellow river involving 131 km of water tunnels with a diameter of 8-10m. Several large projects are highlighted in the paper with reference to the schemes for generating hydro-power, mining of coal and minerals, and constructing transportation networks. The related problems of construction and geomechanics are outlined.

Jan 1, 1995

By Fu Lizhu, Qiu Tingsheng

An application of water-system magnetizing technology for the mineral processing and hydrometallurgy is introduced in this paper. The water-system magnetizing technique flotation and cyanidation leaching test of vein-ore of gold-bearing and conventional technique flotation and cyanidation leaching of gold-bearing vein-ore was carried out. The best condition of water-system magnetizing was determined by orthogonal test. The results have shown that the water-system magnetizing technology may increase the efficiency of flotation and cyanidation leaching for gold. The industry-scale test results also show that it can increase flotation recovery by 1-3% and leaching extraction by 3-5% of a gold-bearing vein- ore. The interaction of magnetizing water-system with minerals was carried out and initially investigated.

Jan 1, 1995

By Stephen J. Navin

The Los Angeles Metro Red Line has installed high density polyethylene (HDPE) as a gas and water barrier around all subsurface structures. The paper reviews the geological setting and resulting need for the barrier. HDPE installation practices are outlined, as are the risks to the barrier, from normal placement methods. Testing and inspection methods used to assure a quality installation are described, and also the field tag method for recording deficiencies and their repair. Specifications and installation changes that will be incorporated into subsequent contracts to improve the quality of the installation are high lighted. The cause of the fire that destroyed part of a tunnel is reviewed as are the revised precautions put in place to prevent a recurrence.

Jan 1, 1991

By W. -C. Huang

In this paper, a methodology for the reliability assessment of geogrid-reinforced unpaved roadways is presented, by taking into account the variability of the subgrade?s undrained shear strength. Analyses are performed using the Point Estimate Method and the Monte Carlo simulations technique. The undrained shear strength is represented by its correlation with the California Bearing Ratio and it is modeled as a random variable following a long-normal distribution. Analyses are performed for different types of reinforcement. The study provides a quantitative assessment of the variation of the system?s probability of failure with this parameter. Overall, the approach suggested in this study may be considered as a complementary approach on the traditional concepts of global or partial safety factors.

Jan 1, 2008

By C. J. Webb, C. J. Paterson, A. Davis

This work focused on identifying, examining and ranking the physical and environmental hazards at inactive and abandoned mine sites in the Black Hills of South Dakota. Earlier inventory projects in the Black Hills concentrated on federal lands, while more recent efforts have examined abandoned mines on state and private lands. The more recent efforts are a result of passage of legislation by the State of South Dakota requiring a comprehensive inventory. The inventory information provides criteria for identifying those sites that require further investigation or characterization of the physical safety or environmental hazards. For most AML sites in the Black Hills, location information is all that is typically needed, because the majority of sites pose little environmental or physical hazard.

Jan 1, 1999