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By Rob Dorey

The disposal of mine waste continues to be one of the main controlling factors in the economics and feasibility of project development. Particular to gold and precious metal mining, waste disposal is further complicated by the environmental and political implications of the use of cyanide. Regulatory compliance criteria have partially dictated and can be anticipated to further dictate the approach and methods of tailings disposal. To develop practical, economic, and environmentally acceptable tailings disposal systems within these criteria requires the use of common sense approaches and the application of available technology. Waste disposal is typically considered during the pre-feasibility stages of project evaluation. At this time, the main emphasis is on the economics and practicality of extracting the metal values from the ore. Frequently, the result of this is that the nature of the tailings and the ability to dispose of the tailings is prejudged. It is also frequently the case, however, that during the feasibility stage and project permitting, the requirements for tailings disposal become paramount.

Jan 1, 1998

By A. Kyriazopoulos

Quarrying is an important activity as it significantly contributes to the economy of a country. This activity presupposes the destruction of the natural vegetation, the removal of the surface soil and deposition of inactive materials. The lack of fertile soil in these disturbed areas is usually a problem for the plant cover establishment. The purpose of this study was to investigate the potential of the establishment of ten herbaceous plant species to inactive quarries with the use of limited amount of fertile soil. The research was conducted in the area of the quarries of the cement manufacture company ?TITAN?, Thessaloniki, Greece. On a terrace of one of the quarries, a 2 cm layer of fertile soil was placed. In early October 2007, the herbaceous species, Lolium rigidum, Festuca arundinacea, Bromus inermis, Agropyrum desertorum, Phalaris aquatica, Dactylis glomerata, Medicago sativa, Medicago lupulina, Sanguisorba minor and Phacelia tanacetifolia, were seeded separately. The first results indicated that among the tested species Dactylis glomerata, Festuca arundinacea and Phacelia tanacetifolia had the highest establishment capability.

Jan 1, 2008

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 J. R. Palmes

Three coal samples, selected out of eight with well characterized surface properties, were used in flocculation tests and synthetic mixture of coal and silica was used in the selective flocculation experiments. Coal wettability and flocculant type were found to have a strong effect on the flocculation results.

Jan 1, 1993

By Timo Niitti

Within the minerals industry, flotation is the predominant method when processing sulphide ores. There is hardly any competition in this area because of the high efficiency and low costs of flotation. When processing other ore types magnetic or gravity• methods are commonly used and sometimes leaching methods are selected. The wide variation of the properties of gold (high value, low ore grades, softness, high specific gravity etc.) sets challenging requirements to the processing methods and particu­larly for flotation machines, which should be able to effectively recover free fine gold, coarse gold and gold bearing minerals throughout the full size range. In gold processes the amount of concentrate is usually low, but in some cases large amounts of gold bearing sulphides e.g pyrites has to be recovered. In gold processing seldom does only one method provide the optimum results, but the recovery is usually made using several complementary technologies: gravity separation, leaching and flotation are the most common ones. Mineralogy is the determin­ing factor when selecting the method or methods to be used.

Jan 1, 1995

A joint research effort by Newmont Gold and Du Pont, working with Kurtis Mooney, of Tri-Combined Resources has developed a new ore-sample bag made of "Tyvek," a spunbonded olefin. "The goal was to find a bag with the best trade-off between efficient draining of moisture, minimal fines loss and compatibility with the conveyor drying process we were developing for our new assay lab," Charles Bucknam, analytical development coordinator for Newmont Metallurgical Services states. None of the available polypropylene, cotton or canvas bags had the needed combination of properties. "Our original tests in 1987 on the plastic bags we had been using showed an average loss of 5.4% of mud sticking to the bags when they were emptied into drying pans. Part of the sample was still in the bag as a residual." Tests on bags of "Tyvek" showed low residuals when the samples were dried in the bags before they were emptied, but about 3% of the fines were lost through the seams. Mooney recommended a new bag design, with fold-over seams.

Jan 1, 1990

By Hans von Michaelis

It is appropriate that this opening session of HAZPAC '91 and Randol Gold Forum CAIRNS '91 should address the question of what the two industries can learn from each other. The panel is made up of members with experience in both industry. Several are experts on managing both hazardous waste and the mine/mineral processing environment. There is a marked difference in the regulatory needs with respect to treating and disposing of mining and mineral processing wastes, and "hazardous" or industrial waste materials. The topic of this paper is on the things that the two industries have in common: Many of the processes and technologies that are being used or are currently being developed for treatment of hazardous waste are the same or similar to the processes that have been used for decades or k,nger in the mineral processing industry. Hazardous waste treatment and remediation of contaminated solid and/or groundwater is a relatively new industry. Many of the practitioners in this new industry are relatively inexperienced in most of the "new" technologies that are being applied or developed.

Jan 1, 1991

By Stephen R. Brown

Current conditions in the gold market demand that mine and plant operators make budgeted production targets at the lowest possible unit costs. For those companies bringing new gold pro­duction capacity on-line, achieving budgeted production levels as quickly as possible after start-up is vitally important to mini­mize unit costs and to begin a positive cash flow. Whether the objective is to simply improve unit costs or successfully start-up a new, complex plant, success will be strongly influenced by the skill levels of the operators and supervisors. The only way to assure return on plant investment, and to survive during depressed metal prices, is to ensure that plant operators have the knowledge to effectively run the plant. Technology available in computer-based, multimedia training systems, including: inter­active animation, videos, voice-overs, schematics, and text can now be used to train operators at their own pace using plant-spe­cific information. Additionally, it has been shown that learning through multimedia provides a higher degree of long term reten­tion than more traditional learning methods.

Jan 1, 1998

By C. J. Pritchard

I commend the authors on examining an interesting method of shaft lining and attempting to improve safety in a dangerous environment by remotely installing the shaft lining. It is important, though, to not trade off shaft lining safety for long-term mine safety by lining an intake shaft with combustible material. In many operations, the mine utilities are installed next to the lining of the intake shaft, supplying a possible ignition source if damaged or overloaded. Although the polyurethane studied in the paper is of relatively high density, no mention is made of the flame retardency of the samples. When exposed to heat, small amounts of polyure¬thane will melt and bum but are extinguished when the heat source is removed. If large surface areas of combustible polyurethane - a tunnel or mine shaft - are exposed to ignition heat sources that are not removed or extinguished early, an uncontrollable, fuel rich fire may result with high carbon monoxide levels, low oxygen concentrations, and greatly increased burning rates that can have devastating effects on the ventilation system and miners&apos; safety.

Jan 1, 1990

By R. Bouzaiene

In the paper presented by F.W. Brackebusch on the “Basics of paste backfill systems,” paste fill was presented as a backfill process that offers many advantages over other alternatives such as hydraulic fill and rockfill. It was observed, however, that the mechanics of paste-fill transportation in pipelines is not fully understood and that the success of its implementation in practice depends on the precise control of the proportions of fines, aggregates and water in the mixture. The author emphasized the necessity for laboratory and full-scale testing to determine the suitability of a material to be used as paste fill. Although experimental testing is definitely an important operation in the design of a reliable paste fill, advances in the understanding of the fundamental laws that govern paste flow in pipelines are equally relevant. Ideally, the results of such efforts would provide predictive models for the rheology of the paste and the corresponding pumping-energy requirements. In an attempt to achieve this objective, an ongoing research program has been active at McGill University’s Department of Mining and Metallurgical Engineering.

Jan 1, 1995

By Martin H. Col, Thomas W. Steele

The ability to make a good profit in the mining industry is becoming more and more difficult. Typically, grades are lower, sites are more remote, and environmental restrictions are getting tighter than ever before. While the price of the materials P.roduced, such as gold and silver, have stayed flat or declined, the external costs (goods and services) have increased. Increasingly difficult environmental restrictions have increased the lime and costs of develoJ?in9 new deposits, while often placing restrictions on a mme s production rate. Environmental costs for mine closure and site reclamation also make it very difficult to show a long-term profit while mining. Typically, the answer to this cost/price squeeze has been technological innovation. The whole concept of heap leaching low-grade gold ore is one innovation that provided some very goocf profits to the mining companies; but, today, those profits are being eroded by the continuing cost/ price squeeze. This paper will discuss material handling in a heap leach stacking operation and the alternatives of trucks, grasshopper conveY.or systems and mobile conveyor systems.

Jan 1, 1992

By Merwin Bernstein

Peru has been an important source of metals since Aug. 29, 1533. On that day Francisco Pizarro took charge of the 24 t (772,000 oz) of gold and silver that constituted Atahualpa’s ransom. At today’s prices, the value of that booty ranges between $100 and $150 million, depending on the proportion of gold to silver. Since then, Peru’s silver and gold production has been legendary. Current mine production Most of Peru’s metals are mined from the Andes Mountains and its foot-hills. The Andes run the length of the country parallel to the Pacific coastline from Ecuador to Chile, a distance of nearly 3000 km (I 875 miles). They are about 300 km (187 miles) wide and much of the range is more than 3000 m (9900 ft) in elevation. High plateaus (altiplanos) occupy a large part of the range. Both flanks are rutted by large valleys and canyons. Many of these peaks are prodigious. which make road building expensive and adds to the cost of mining.

Jan 1, 1993

By Anthony J. Peach

With the new generation of so called "Super TBM", we would all expect to witness the implied super-performance. In some instances this is occurring, but one must ask why is it not occurring in the majority of applications? For hard rock TBM related projects, we are observing a decrease in the volume of projects in the previously traditional areas such as North America and Western Europe and an increase in Asia (Hong Kong, Indonesia, China, Korea etc). As a consequence less experienced contractors are acquiring the latest ultra high power equipment, without the knowledge necessary to achieve optimum performance. The interdependence of TBM and muck removal systems has been assessed with emphasis on the emergence of the continuously extending conveyor technology, as a means of achieving dramatic productivity increases. The Australian system assessed here at the time of drafting this paper holds the world record tunnel excavation production of 2,166 metres. A little considered aspect of the adoption of conveyors is the associated improvement in safety.

Jan 1, 1995

By W. R. Dengler

In Canada, most of the rock being broken in underground metal mines is being done by using traditional drilling and blasting methods. Despite advances being made in hardrock boring and other, more exotic techniques, Dynatec believes that the traditional methods will prevail for many years. It is also believed that modest research efforts expended on the traditional methods will result in substantial financial benefits to the mining and rock tunneling businesses. Dynatec has pursued productivity improvements through the use of long rounds in shaft sinking and lateral development. The concept of longer rounds was developed by Dynatec on the Craig Shaft Sinking Project (RETC, 1991). This technology was subsequently used to sink the two shafts at Aur Resources with great success. The development of a Long Round Jumbo for tunneling is a natural progression of the long round technology developed for the Craig Shaft. The Dynatec Long Round System has been patented in the United States and South Africa, with additional patent applications pending in Canada and Australia.

Jan 1, 1993

By D. Limpitlaw, E. M. Hoadley

The minerals sector plays a significant role in the development of many Southern African economies. In the Southern Africa region, as in other developing regions, economic development is seen as the key contributor to poverty alleviation and social upliftment. The significant economic contribution of the minerals sector may be reduced by negative impacts on the biophysical environment and on the communities where mines operate. A critical variable in determining the net contribution of mining companies to SD is the degree of transparency with which the companies operate. Transparency is increasingly emphasised as an essential aspect of good governance and SD, but it is also difficult to establish, and is a sensitive issue for mining companies as they compete with each other for minerals sales. Transparent reporting could ensure that the interests of all stakeholders are addressed as company data is subject to informal ‘auditing’ by any interested party. This paper assesses published reports of five companies over a number of years to establish whether it is possible to make an assessment of the companies’ contribution to SD.

Jan 1, 2005

By C. R. Bennett

A copper heap leach model, employing leading edge computational fluid dynamics (CFD) technology, is applied to the Zaldivar heap leach operation in Chile in order to explore and analyze the possible impact of operational changes. The effect of changes to the heap operation on copper recovery has been previously investigated and reported by the Zaldivar operation. This paper examines the extent to which a comprehensive heap leach model supports the analysis and conclusions of the published work. The heap is a complex multi-phase process, consisting of a solid static porous media with complex fluid flow, gas and liquid phases, competing solid-liquid reactions, dissolution of minerals and transport through the heap. The model accounts for the physical and chemical features of the heap, including transport and reactions kinetics for the important copper and iron sulfide minerals, ferrous oxidation, bacterial effects, thermal energy, acid and sulfate balances. The model was calibrated to published data on the ore body and employed to analyze the impact of a number of operational changes, including solution flow rate, acidity, lift height, crush size and head grade.

Jan 1, 2012

By S. K. Kawatra, S. J. Ripke

During iron ore pellet production, bentonite clay is used as a binder. Typical pellet plants spend from $3 million to $5 million annually for the clay. If bentonite dosages could be reduced by using it more efficiently, a significant cost savings would result. If the binding mechanisms can be completely understood, procedures can be developed to use bentonite more efficiently. Classical bentonite bonding theory is based on the behavior of bentonite at low percent solids and high mixing shear rates. Under these conditions, bentonite was understood to expand, disperse into platelets, and dry into a bonding "film" or "gel." However, these are not the conditions that exist during pelletization, which is carried out at high percent solids and relatively low shear rates. In this paper SEM imaging was used to identify and explain the bonding mechanisms of bentonite on the surface of magnetite concentrate. It was determined that bentonite would form a fibrous network under the proper conditions and that the formation of these fibers corresponded with an increase in the bonding of particles by the bentonite.

Jan 1, 2000

By R. Ciccu

Permeable reactive barriers (PRB) are one of the most promising systems for groundwater remediation. PRB are constructed with the purpose to intercept the contaminated flow and to degrade it as a big reactive filter. The most common type of reactive barriers is realized by excavating a trench and by filling it with a substance able to treat the contaminants dissolved in the water. Another type of PRB is obtained by realizing a line of wells in which chemically active compounds are injected. A new method for barrier construction has been studied at DIGITA?s laboratories. It makes use of the waterjet technology to increase soil permeability and to inject active compounds. This technology is especially suitable in the case of deep contaminated aquifers where traditional construction methods are difficult to apply. The paper describes the experimental apparatus especially designed and constructed and the activities carried out to investigate the relationship between waterjet operative parameters and the penetration of the jet in the soil. In conclusion, on the basis of the experimental results, the economical feasibility of the technique is evaluated.

Jan 1, 2008

By Richard D. Christie, K. Jay Pillai

In the past, it was not unusual for coal preparation plants to discard fine run-of-mine coal. This practice has changed due to increasing quantities of fine material, improvements in beneficiation methods, and the need to recover revenue from these fines. It is in this context that the coal industry has increasingly been turning to froth flotation for fine coal beneficiation. Reagent schemes have been developed to promote coal flotation and to treat the resulting refuse material. While reagent technology has improved, however, most plants rely on manual control of reagent dosing and circuit operation. This often results in misuse of reagents, loss of coal recovery, and consequent loss of revenue. Fine coal circuit operations can be dramatically improved through automation. Intelligent process control systems are now in use which are capable of optimizing reagent usage, maximizing coal recovery, and minimizing chemical costs associated with refuse handling. This paper describes a type of control system currently used in preparation plants, and provides data and information on the significant improvements such systems can produce.

Jan 1, 1994

By Dilip K. Sinha

In the paper some interesting cases of applications of Operations Research and Computer Methods as worked out by the author and accepted by the management of some of the newly formed Indian mining organisation for implementation are highlighted. The main emphasis on the application cases was to use simple techniques and methods which yield the result in shorter time period, The case problems mainly deals with the production system optimisation in unit mines, areas/divisions and at the corporate levels. Also the management decisions regarding reorganisation of transport and distribution system of material and mineral are attempted to be optimised. Further, the case of management system development with computer aided decision making worked out for single large Iron Ore Project captive to a steel plant is outlined. Finally, the case of a large mining company having decentralised units and divisions geographically dispersed throughout the country, computerised management decision-information system designed on the basis of inputs and outputs of decision models relevant for different levels of management in the organisation is depicted.

Jan 1, 1986