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By B. Schimm

Mining of material without blasting and / or selectively becomes more and more important for high quality ROM-products. Surface Miners have been developed especially for this purpose. The cutting technology of these machines has been improved, so that harder material as well as wet and sticky materials can be cut with better results now. Especially the cutting drum design and more precise drum manufacturing process now allow production and equal tool wear over a long period. The better knowledge of rock parameters influencing the cuttability and cutting results allow higher production, less cutting tool wear and therefore reduced production costs.

Jan 1, 1999

By L. Diestelow

Evaporation and crystallization processes are used extensively in the mining industry to provide many pro-ducts. In the case of solution mining evaporators are used to concentrate, or to concentrate and crystallize the raw materials being mined. In the case of underground, or strip mining dissolving and crystallization are used in many processes in order to purify the ore to saleable materials. Presently evaporators and crystallizers are being used in the production of sodium chloride, potassium chloride, sodium carbonate, sodium sulfate, lithium chemicals, aluminum, and many others. The evaporator is a device designed to remove water or solvent from a solution. In an evaporator the energy released by steam condensing on one side of the heat transfer surface is transferred to the product solution on the other side of the heat transfer surface. As long as the boiling temperature of the product liquor is below the condensing temperature of the steam, the product solution will absorb heat. This heat absorption causes vaporization of the water (solvent) in the product solution resulting in concentration of the product. The simplest evaporator is the single effect evaporator. If we assume the feed introduced into the single effect evaporator is at its boiling point, ignore radiation losses, and assume the steam into the heat exchanger is dry and saturated, then the heat transferred will correspond to the latent heat of vaporization. Therefore, one kilogram of condensing steam will produce one kilogram of evaporation. Economies in energy usage compared to the single effect evaporator can be made by using multiple effect evaporators, or vapor recompression evaporators.

Jan 1, 1993

By Qingxia Liu, Chen Tingzhong, Chen Jin, Yang Xiaosheng

It is common problem (Huan Xinsheng, etc.,l992)for most iron ore concentrators in China that the concentration of thickened tailings is lower than the need for economical transportation. To solve the problem, two methods of improving the properties of the existing thickeners and using separate thickening technique have been applied in three iron ore concentrators. However, in the case of the Daye iron concentrator a new technique of cyclone-flocculated sedimentation was developed by present authors and verified by experiments. The new technique employs efficient hydrocydone designed by authors in conjunction with a low cost flocculant named KLP.

Jan 1, 1995

By Robert McEwen

Conveyor equipment beyond its prime chronically suffers from a lack of understanding in today's plant environment regularly delivers more material than original designers ever expected. A case in point is a belt conveyor in a major hard rock mine/milling operation asking to bring the unit up to current standards while eliminating spillage and reducing airborne dust. The challenge was to keep the system going by revamping the system while keeping the same footprint and allowing for higher production rate. Thirty years of daily maintenance and dust collection costs have virtually disappeared by the end of this challenging upgrade.

Jan 1, 2008

By Andy W. Stephens, William H. Langer

In Australia and America, encroachment by conflicting land uses, zoning restrictions, and the "not in my backyard" syndrome make it increasingly difficult to access high-quality aggregate resources located near the market areas. Attempts by government agencies in America to protect aggregate resources for future development have met with varying degrees of success. The State of Queensland, Australia, designates aggregate resource areas as Key Resource Areas, which protect the resource and the routes to transport the resource, provide a separation area from incompatible land uses, and indicate the likelihood that the area is free from conflicting social or environmental issues.

Jan 1, 2005

By G. G. O. O. Uwadiale

Starting from a crude ore assaying 45.6% Fe, a fine-grained oolitic iron ore was concentrated by the oil agglomeration technique to 90% Fe recovery and 65% Fe assay. The ore required grinding to minus 5 µm to effect adequate liberation, and the technique yielded optimum results at pH 9. The roles of pH, collector, and bridging liquid concentrations on selectivity and yield of iron minerals in the concentrates are discussed.

Jan 1, 1991

By Fathi Habashi

ION FLOTATION was introduced by F. Sebba in 1959. This technique permits the recovery of metal ions from solution through the introduction of an appropriate cationic or anionic surface-active agent into the solution. The surface-active agent, called a collector, is added in stoichiometric amounts in relation to the metal content of the solution. It reacts with the metal ion to form an insoluble soap, and is levitated to the surface by gentle bubbling of air to form a foam which collapses into an insoluble scum. The optimum conditions for the ion flotation with soaps of C10-16, fatty acids are shown in Table 15-1. Baarson and Ray (1965) found that once the metal was completely precipitated as the hydroxide, as little as one hundredth the stoichiometric amount of the collector was required to cause complete flotation of the [ ]

Jan 1, 1970

By M. G. Ayat, B. C. Scott

Coal degradation is the breakage of coal particles to finer sizes due to the continuous forces of attrition and gravity to which coal is subjected during mining, handling, and preparation. The objective of this paper is to determine the extent of degradation that a coal slurry experiences when transported through pumps and pipelines. The examination of degradation results for a number of different coal slurries have indicated that the extent of breakage is dependent on the physical properties of coal and the time span of circulation. These results have also indicated that certain size fractions of coal are more susceptible to breakage than others.

Jan 1, 1987

By Konstantinos Theodoridis, Michael Galetakis, Olga Kouridou

Recent advances in Artificial Neural Networks (ANN) and Adaptive Neuro-Fuzzy Inference Systems (ANFIS) have provided a new approach to the estimation of related quality characteristics, such as heating value, ash content and moisture of coals used for power generation. The basic strategy for developing ANN and ANFIS models for the prediction of missing quality values, is to train the models using an existing quality data set and an appropriate learning method. Statistical analysis results of the estimated values, showed that ANN and ANFIS are not only more accurate than the widely used regression models, but also tends to reproduce the variability of the initial data, while regression models generate a smooth representation of reality.

Jan 1, 2002

By Anthony J. Ranalli, Florentino B. Maestas, Katherine Walton-Day, Richard W. Healy

Water movement and water chemistry were monitored in the unsaturated zone at two sites in fluvial tailings deposits along the Arkansas River near Leadville, Colorado. One of the sites was remediated by the incorporation of lime and biosolids into the soil. Preliminary results, based on data collected during the 11 months following remediation, indicate that differences between the two sites can largely be attributed to heterogeneity of the deposits. Remediation has increased the alkalinity in the upper soil zone, but as of yet, there is no indication that soils at depths greater than 30 cm have been affected.

Jan 1, 2000

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 Roger B. Jr. Herbert

Surface water samples were collected from water accumulations at the surface of a neutral pH mine tailings deposit in Kristineberg (Sweden) where algal growth and iron hydroxide precipitates were observed. Ferric iron in the aqueous samples was determined by (adsorptive) differential pulse - cathodic stripping voltammetry. The analyses indicated that labile Fe3+ concentrations were in the range <20 to 337 nM, while total Fe3+ levels were much higher at 0.9 to 8.3 uM. The labile Fe3+ levels are more than two orders of magnitude greater than would be expected based on equilibrium with ferrihydrite. These results suggest that iron complexation with strong ligands in the surface water competes with iron hydrolysis, and that these ligands may be of algal and/or bacterial origin.

Jan 1, 2000

By M. Taxiarchou

The continuously increasing rate of the non-renewable raw material consumption together with the production of immense volumes of solid wastes and effluents is one of the main characteristics of our modern society. This leads to an unconditional necessity to reduce the raw material and energy consumption and to recycle the used materials and products. Life Cycle Analysis (LCA) constitutes a promising tool in this direction. LCA is a methodology, whose main purpose is the objective calculation and analysis of the environmental burdens of products, processes and activities as well as the estimation of the possibilities to perform environmental improvements in combination with the rational use of raw materials and energy. The purpose of this paper is to present the life cycle of marble and granite from the quarrying to the processing stage, including the transportation between the quarry and the processing plant, by quantifying the environmental impacts that derive from each stage and the evaluation of their potential effects to the environment and to human health.

Jan 1, 2007

By M. Li, J. D. Miller

Existing process technologies for the production of soda ash from trona involves dissolution in hot brine, sedimentation and filtration for the removal of impurities, and subsequent crystallization for the recovery of soda ash. In this regard, mining and operating costs, particularly energy costs, are higher than desired. A preferred processing strategy might be to remove gangue mineral contaminants from the plant feed prior to dissolution in hot brine. Such a preprocessing strategy at ambient temperature and pressure has been limited by the lack of satisfactory process technology. Now based on recent results from laboratory research at the University of Utah it seems that the run-of-mine trona ore can be treated at ambient temperature and pressure using a special flotation procedure to separate the gangue minerals and make a trona concentrate with a purity of almost 99% trona at a recovery of more than 97%. The concept of such a new processing strategy is discussed with respect to current plant practice.

Jan 1, 2002

By R. A. Paul

The requirements for water inflow control for the Chicago Intercepting Sewer System are stringent. This posed special problems in grouting the bored and conventionally mined tunnels, shafts and chambers of the system. In adapting conventional grouting techniques to the specific problems encountered in the system&apos;s pilot project, numerous field procedures were developed. Careful preand post-grout testing and evaluation identified the most efficient and economical of these procedures. As an example of some of the conclusions reached during the project it was found that the mineralized groundwater in the Chicago area tended to reduce the efficiency of the grout holes, thus limiting their useful life. Pressure washing to remove natural fillings was a critical factor in achieving a permanent grout seal. The value of relatively thin lubricating grout mixes was definitely established. Although not an ideal situation, satisfactory results could be obtained by manifold grouting several grout holes simultaneously if done within specific limits of hole groutability, location and numbers. Caulking proved to be a primary controlling factor in achieving acceptable results. To achieve such a high degree of water inflow control requires close supervision by experienced personnel. "Temporary grouting as a construction expedient" produces seepage conditions which are extremely difficult to treat.

Jan 1, 1974

By Thomas D. Kaufmann

The 1982 recession set the US mining and metals industries reeling. Will the oncoming recession of 1991 hit as hard? Probably not, thanks to a shallower downturn, a weaker dollar and remarkable lower costs. Effects of the last recession That the 1982 recession was traumatic to the American mining and metals industry is an understatement. Quantities of metals consumed dropped. Metals prices fell despite continuing general inflation. The resulting real gross revenues of producers of each of the major metals plunged, in the trough of 1982, to levels one-fourth to two-thirds of those of the peak of 1979 (Table 1). By contrast, most industries in the United States were not hit anywhere nearly as hard. Real GNP, the aggregate of all production, slipped only 1 % from 1979 to 1982. Metals are most sensitive to the business cycle because of their applications. All metals but gold are raw materials to downstream industries. Raw materials are victims of strong fluctuations. This is because buying industries try to hold high inventories in boom periods when goods are in short supply. They reduce inventory levels in buyers markets when suppliers have idle capacity and raw materials are in ample supply.

Jan 1, 1990

By L. Landryova

The Department of Control Systems and Instrumentation, VSB - the Technical University Ostrava, has been involved in a project dealing with utilization of landfill gases, when the methane gas utilization and minimization of its release into the atmosphere was the main concern. The landfill site is generally a place, where technology for energy production can be built. The conditions for this technology implementation vary and depend on various factors. This paper is presenting findings and experience gained regarding a method of methane gas utilization for energy production. This method is concerning building bioreactors at the landfill sites, which are already operated. Every bioreactor can be thought of as a process, which is controlled in order to maximize energy production and minimize the methane gas escape into the atmosphere. The bioreactor landfill can represent a number of environmental and cost savings and, at the same time, is able to comply with all legislative issues.

Jan 1, 2005

By J. K. Neathery, T. X. Li, H. Ban, J. M. Stencel, X. K. Jiang

Upgrading molybdenite ore can be technically difficult and expensive if talc is a major impurity in the ore. The layered structure of molybdenite and talc decreases the surface specificity of floatation and suppression agents, thereby making molybdenite ore beneficiation inefficient if under some wet processing methods. However, oxidic talc surfaces may be distinct from the sulfidic or oxysulfidic molybdenite surfaces, such distinction related to electron work functions and/or densities of electron donors/acceptors sites. If such differences are present, the upgrading of finely sized molybdenite ore by dry triboelectrostatic methods may hold advantages over traditional wet methods. We report on the upgrading of molybdenite ore using a laboratory-scale, drytriboelectrostatic beneficiation system. This system employs pneumatic transport conditions to tribocharge, beneficiate and collect the fine molybdenite ore particles. Using this system, two Mo ores were beneficiated under dry conditions without the addition of water or surface modifiers and additives. Beneficiation performance was dependent on the particle size of the feed ore. The surface and particulate morphology and elemental concentrations in the parent feeds and the beneficiated products were examined by scanning electron microscopy (SEM) and optical microscopy. These data, in conjunction with a complete recovery analysis, define some potential advantages of dry, triboelectrostatic beneficiation processing and provide insight into factors controlling molybdenite ore upgrading.

Jan 1, 1999

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 E. F. Divers

Adequate ventilation of coal mine working faces is the most important technique for controlling respirable dust and methane. Choosing the right technique presents some tough questions. US Bureau of Mines research has shown that to control respirable dust, you must contain the dust near the face, keeping rollback (turbulence) to a minimum. For methane, the most effective approach has been to use a blowing brattice, or tubing, and to create turbulence and disperse the face methane, allowing it to pass over the machine and into the return. It is immediately apparent that the two approaches may counteract one another, thus complicating the decision as to which system may be best for a given situation. At present. Bureau research has developed two successful machine-mounted face ventilation systems to meet these different needs and allow deeper cutting. The fan- powered dust scrubber is designed to control dust primarily associated with blowing face ventilation systems. The spray- fan controls methane on exhaust-ventilated sections.

Jan 1, 1987