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By D. B. Jenkins, D. R. Taylor

Treatment of bentonite clay with mineral acids yields a modified clay product of high surface area and acidity that exhibits enhanced adsorptive and catalytic properties. A highly specialized segment of the clay industry based on this process has evolved into a worldwide business with a capacity of about 500 kt/a. This paper will present data on the chemistry, mining, manufacturing, and applications for acid-activated clays.

Jan 1, 1988

By V. Avdiyskiy

The most pressing topic raised nowadays by the world community faces environment and social consequences of the business intensification process, primarily that of mining and mineral industry, which is through the number of its activities mostly associated with pernicious impacts. World top managers are confronted with the dilemma of reconciling traditional financial framework aiming at successful business development measured by revenues, shareholder value, profit margin and incorporating Sustainable Development (SD) at all levels of decision making process, avoiding depriving future generations of the means to meet their own needs. The rapid consolidation and globalization of the industry stipulates that companies are an integral part of the world economic environment. Therefore a company?s financial performance is under the pressure of operational and environmental performance. Among them special attention is paid to the social and economic background, the relationship with regulatory institutions, and the developments for environmental protection.

Jan 1, 2003

By John W. Rozelle, David S. Bolin

INTRODUCTION During the normal course of a mining project, a feasibility study will be prepared that addresses all the aspects of the project including geology and mineral inventories, mining and geo- technical, metallurgical processing, infrastructure, environmental considerations and economic analyses. These studies are prepared for various reasons. Occasionally, a feasibility study will be prepared solely for use within a company as justification for development expenditures, however, these documents are frequently submitted outside the company either to raise funds from financial institutions or from public financing on one of the various securities exchanges. Mineral industry consultants are often called upon to participate in the preparation of feasibility studies or to conduct an independent audit and review of an internally prepared study. As the recoverable mineral resources form the foundation upon which the balance of a feasibility study is based, including the economic analysis of the project, the resource aspect of the study is examined very carefully by financial and securities organizations. The balance of this discussion is directed toward the various geological and resource estimation aspects of feasibility studies that experience has shown to be of particular importance. Much of this discussion will be directed toward open pit gold operations, although the principles are applicable to any type of deposit. 2.0 GEOLOGIC RESPONSIBILITIES IN FEASIBILITY STUDIES The principal geological effort in the preparation of a feasibility study is generally dedicated to the following areas: - Preparation of Geologic Reserve/Resource Estimates - Condemnation of Sites for Facilities, Access Roads, Leach Pads, Waste Dumps and Tailings Disposal - Collection of Geotechnical Data - Provision of Mineralogical and Petrological Data Pertinent to Metallurgical Processing - Selection of Appropriate Bulk Sampling Sites for Collection of Metallurgical Samples Each of these items will be addressed in detail in the following sections. 3.0 RESERVE/RESOURCE ESTIMATION An ore reserve estimate consists of the determination of a volume, or tonnage, and a grade for the deposit. There are numerous cases in the mining industry of projects that have experienced severe difficulties when operational ore grade, tonnage or metallurgical amenability have proven to be deficient compared to predicted estimates. An error in estimation of tonnage generally leads to more long term problems affecting mine life and production schedules. However, a significant error in the estimation of grade, particularly if mined grade is lower than anticipated, can have an immediate, and often disastrous, effect upon a project. The geologic preparation leading to an ore reserve estimate generally follows a logical sequence familiar to

Jan 1, 1987

By J. J. Davis, D. G. Osborne

The Australian coal industry is characterised by efficient fines recovery, and the climate does not dictate the use of thermal drying. With the increasing trend to underground mining and hence finer ROM coal, and market pressures for reduced product moistures, dewatering issues are assuming increasing importance in the Australian coal industry. The greatest potential gains in dewatering performance undoubtedly lie in the treatment of finely sized material. This paper examines the dewatering issues which have been recognised by the Australian coal industry, and describes current Australian research in this field.

Jan 1, 1995

By R. RAMSDEN

The deep South African gold mines rely on refrigeration to provide a safe working environment. Chilled water, which is produced in large central refrigeration plants, is distributed throughout mines In insulated pipes. In view of the high cost of the insulation materials and recent regulations which prohibit the use of certain insulation materials, a careful examination of the actual benefits of insulating chilled water pipes was undertaken. The objective of the investigation was to produce general guidelines regarding the use of insulation, but the results of numerous studies have shown that the use of insulation is extremely site specific and thus no general guidelines can be given. To assist ventilation engineers with studies on insulation requirements for their cooling systems a computer program has been developed. This paper describes the personal computer program which contains the same user friendly interface as developed for other COMRO programs. Is fully menu driven and incorporates a comprehensive HELP facility which provides background information and assistance with the selection of input data. The effects on the ventilation air and chilled water temperatures from not insulating chilled water pipes in certain areas are calculated. Air leakage, heat flow from the surrounding rock to the ventilation air and heat flow from the ventilation air to the water flowing in chilled water pipes are taken into account. A simple cooling system is considered in which cold water is distributed over a distance of 1 000 m through pipes to a single air cooler. The influences of changes in the temperature of the chilled water and ventilation air, as well as air leakage on the insulation requirements are determined.

Jan 1, 1991

By L. A. Obasi, C. Obasi

Investigations were carried out to determine the effects of changing metamorphic conditions on the formation of magnetite from the Itakpe iron ore deposit. Various magnetite grain sizes from ferruginous quartzites from different zones were determined and analyzed statistically. The results reflect the reaction of mineral individuals. In particular, the granulometry of magnetite changed with changes in the mineral formation conditions in the deposit and correlate with the mineralo-geochemical zones. This is interpreted as part of a readjustment of the mineral to the prevailing conditions. Because granulometry is a prebeneficiation parameter, this work will be, no doubt, of importance to the exploitation and beneficiation of the quartzites and rich ores.

Jan 1, 2000

Over the last two decades, the mining industry has spent considerable time and effort in installing sophisticated control systems (including expert systems) to regulate and improve the performance of AG/SAG mills. Yet the need for these systems is often overlooked – unmeasured and uncontrolled variation in the feed material. With AG/SAG mill technology replacing rod and ball mills as primary grinding equipment, the need for careful and thoughtful feed preparation has gone. To maximise mill throughput, operations need to better understand the ore characteristics affecting AG/SAG mill performance. Industrial operating data will be used to illustrate these ideas and concepts. It is often quite surprising which ore characteristics that are the most influential on mill throughput.

Jan 1, 2004

By J. C. Yingling, R. Kumar, J. Sottile

The capability for on-line measurement of the quality characteristics of conveyed coal now enables mine operators to take advantage of the inherent heterogeneity of those streams and split them into wash and no-wash stocks. Relative to processing the entire stream, this reduces the amount of coal that must be washed at the mine and, thereby reducing processing costs, recovery losses and refuse-genera¬tion levels. In this paper, new ap¬proaches for optimal control of the segregation process using time-se¬ries models and empirical distribu¬tions are presented and demon¬strated using field data.

Jan 1, 2000

By A. E. Ketler

Optical smoke monitoring fills an important gap in ventilation and fire safety: namely monitoring of smoky, low temperature fires where little CO and heat are generated. Smoke monitoring also avoids the nuisance alarms due to diesel exhaust, battery chargers, blasting and welding. The smoke optical density (OD) fire alarm standard specified by MSHA presents an opportunity for improved safety. Experience of actual mine usage of the SmokeBoss*100 is reviewed, with particular regard to effectivity, maintenance and cost.

Jan 1, 1995

By Richard Keith Corbin

INTRODUCTION With the world media full of predictions that the price of gold will quadruple in three years (Maybury, R.J., 1988), and with financial forecasters and strategists touting opportunities to make 400% in gold (Skousen, M., 1988), explorationists and entrepreneurs are scurrying to find enough gold to feed the global gold fever created. At the same time, gold deposits in the United States and other developed and intermediate countries are becoming less attractive because of environmental restrictions, radical reductions in tax incentives, and depleting reserves, causing people in the mining industry to begin looking at opportunities for foreign investment in gold mining concessions in lesser developed countries (LDCs). Meanwhile, LDCs are responding with chamber-of-commerce aplomb in marketing their opportunities. In the face of all this frenzy and hype, targeting gold mining concessions in LDCs for foreign investment may be done more objectively by employing a systematic approach. For this paper the SHOP rating system (Corbin, R.K., 1987), which considers factors of the LDC's stability, hospitability, ore occurrence, and profitability potential is used. The result is that a tiny banana-growing republic in Central America, first discovered by Columbus and named the "Rich Coast'' because of the many gold adornments worn by its Indians, has been rediscovered and emerges as a classic LDC gold target.

Jan 1, 1988

By Agne Rustan

Most of the mines in Sweden are metal ore mines in hard rock and none of these mines are classed gassy because there is no methane emission. The risk of methane explosions in Swedish mines is therefore very small. Since the 1960?s, in Swedish mines, there has been a change from electric and pneumatic loaders and transport machines to diesel. Today in almost all Swedish underground mines diesels are used. One of the most common complaint from the underground mine- workers is the exhaust gases from the diesel-vehicles. This is a strong motive for attempts to assure a more comfortable environment. Another motive for a better efficiency of ventilation under ground is the increasing cost of energy for fans and for heating the air during winter. For the largest mine in Sweden, the Kiirunavaara Mine, 36% of the energy for ventilation is used for preheating the air during the seven months when the temperature is below zero. The air quantities used for ventilation are large. In table 1 a comparison of the ratio between yearly produced ore and waste rock and installed fresh 'air capacity is shown. [ ]

Jan 1, 1980

By Ralph P. Hackl

The Congress gold property, located near Goldbridge, B.C., is extremely refractory with most of the gold disseminated in fine- grained arsenopyrite. Metallurgical testwork conducted by Giant Bay Biotech Inc. indicated that biooxidation pretreatment was capable of increasing cyanide gold recovery from the ore to greater than 90%. To determine if the bioleach process could be successfully scaled up, a 225 cubic meter commercial size bioleach reactor was built and tested at the mine site in 1989. At that time the tank was the largest bioleach reactor ever operated. This paper discusses our experiences in operating the tank, summarizes some of the data obtained and describes the problems encountered.

Jan 1, 1990

By K. S. E. Forssberg, S. Subramanian, Hanumantha K. Rao

The dispersion characteristics of apatite and magnetite minerals have been assessed based on zeta-potential measurements, using various inorganic and organic reagents, namely sodium silicate, sodium tripolyphosphate, sodium hexametaphosphate and lignin sulphonate. These results highlight that apatite is dispersed to a greater extent vis-à-vis magnetite. Further, the dispersion efficiency of the phosphate reagents is better than that of sodium silicate or lignin sulphonate, for both apatite and magnetite. Batch flotation tests on a high phosphate magnetite ore from Kiruna indicate that higher apatite recovery with minimum phosphorous loss to the magnetite fraction can be achieved using sodium silicate as a dispersant. Although comparable dephosphorization can be attained with lignin sulphonate dispersant, the recovery of magnetite in the non-float fraction is lower, possibly due to the adverse synergistic effect of this organic reagent with the Atrac collector, resulting in the flotation of magnetite. The high intensity conditioning of pulp for up to 30 min resulted in better apatite flotation with <0.015% phosphorous in the magnetite product.

Jan 1, 2002

By Gordon R. Wicker, Peter V. Avotins, Steven S. Ahlschlager

Laterite ore slurries exhibit Bingham plastic behavior and can be characterized by the magnitude of their yield point and Bingham viscosity. These two parameters are affected by ore composition, solids concentration, and temperature and are used to predict the pressure drop in pipelines and heat transfer coefficients in shell-and-tube heat exchangers. In cycloning of laterite slurries, the calculated cut size is corrected by factors obtained from the rheological parameters.

Jan 1, 1979

By Keith A. Heasley

The objective of this paper is to back-analyze the August 6th ,2007 collapse at the Crandall Canyon Mine in order to better understand the geometric and geo- mechanical factors which contributed to that collapse. In this work, the LaModel boundary-element program along with the best available information is used for the back- analysis. To initiate the analysis, a six step base model of the mining in he Main West area was developed. This base model included a step for each of the critical stages in the mining of this area. Next, calibrated values for the critical input parameters: rock mass stiffness, gob stiffness and coal strength, were developed and optimized based on the best available information. Finally, the model was used to simulate the final mining scenario. As a result of this back analysis , a number of conclusions can be made concerning the mine design and the August 6th collapse: 1) Overall, the area was primed for a massive pillar collapse because of the large area of equal size pillars, 2) The abutment stress from the active retreat sections and the adjacent longwall panels were significant contributors to the collapse, 3) From the modeling alone, it is not clear exactly what triggered the August collapse, although the active mining is a reasonable assumption.

Jan 1, 2012

By Wm. Randolph Reed, John A. Organiscak

Haul trucks have the potential to generate large amounts of respirable dust. This respirable dust has been shown to be a health hazard to personnel, especially if it contains a high silica content. Lack of dust sampling data from haul trucks prompted the completion of a study to quantify respirable dust concentrations. These field studies were conducted measuring instantaneous respirable dust at stationary locations from passing haul trucks at a stone quarry and a coal mine site. Fugitive dust levels from haul trucks were analyzed to characterize dust dispersion. This analysis will indicate safe following distances for haul trucks and other heavy equipment to avoid over-exposure of respirable dust from the lead haul truck.

Jan 1, 2005

By A. LaPlante, A. Cauchon

This gravity circuit at Les Mines Camchib Inc. consists of two pinched sluices to bleed a feed to one of two 76 cm (30") Knelson concentrator. The Knelson concentrate is upgraded to smeltable grade with a smaller Knelson (18130 cm) and a riffleless table. Their tails are column cyanided and washed prior to recycle to the grinding circuit. This paper details size- by-size circuit performance. The Knelsons recover around 90% of free gold (as determined by Mozley Laboratory Separator), even below 37 pm. The sluices are ineffective, with upgrading ratios around 2, but approaching unity in the fine sizes. Much of the effectiveness of the circuit lies in the high gold circulating loads in the grinding circuit, which partly atone for the poor sluice performance, and the ability of the Knelsons to recover free gold. Secondary upgrading recovers slightly above 99% of the primary concentrate gold, 90% of it in a 65% Au concentrate and the balance in a heavily loaded (10 to 20 oz/st) pregnant solution, generated by intensive column cyanidation.

Jan 1, 1990

The United States is being invaded... by foreign capital: marks, francs, pounds, yen, lire, riyals, you name it: On almost any given day the Wall Street Journal will contain a new report on a department store, newspaper, bank, hotel, agricultural land, supermarket chain, et a1 being bought into by overseas investment. Xenophobic reaction to this revised national condition has begun to set in. Several farming states have and are introducing legislation to monitor foreign land buying. In Congress a mandatory reporting requirement for foreign purchasing is currently under study. In a relatively short period the country has reverted from world leader- ship in overseas acquisition and involvement to become itself one of the prime investment opportunities in existence. Interestingly enough, one of the industries where this changed status has become most apparent and pronounced is within that small/regional/segmented/low value-to-weight bulk commodity enterprise ranked as the backbone of the nation&apos;s construction activity. U.S. cement making is not only undergoing internationalization in its ownership, but also in its product, equipment, and engineering expertise.

Jan 1, 1979

By B. Dabrowski, J. D. Miller, D. Halbe, J. Hupka

An air-sparged hydrocyclone (ASH) mobile system was evaluated for continuous stripping and recovery of cyanide (the AVR process) from process water at a gold plant site. The ASH unit performed exceptionally well as an absorber. HCN was removed from the gas phase in a single one second pass with an efficiency exceeding 99%. HCN concentration in the discharged gas phase was lower than 10 ppm, which provided for a safe working environment. The stripping efficiency, controlled by the Henry’s Law constant, exceeded 40% in one pass.

Jan 1, 2004

By Paul Kents

The Canadian Javelin Limited Cerro Colorado copper-porphyry deposit in Panama, possibly the largest known copper-porphyry, contains between 1350 and 450 meter elevations, drill proven and probable ore in excess of 3.0 billion tons averaging 0.65% of copper equivalent. The deposit is located in the Central Cordillera Range, straddling the Continental Divide at 1500 meter elevation. Local topography is very steep. Accessibility is difficult, all logistics made by helicopter, and only recently a 52 km. road from the Pan-American highway was completed into the area. The deposit was discovered in 1969, and since then 75 shallow exploratory holes and 98 deep holes, the deepest 1340 meters, totalling 45,000 meters have been drilled. Deep holes were drilled at the corners of a regular rectangular 150 meter grid.

Jan 1, 1975