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By C. M. F. Vieira

In the county of Campos dos Goytacazes, north of the State of Rio de Janeiro, Brazil, there is a large production of red ceramic, mainly perforated bricks. A percentage of these bricks are damaged during the firing processing and become a red ceramic waste. This work investigates a possible solution to this environmental problem through the mixture of fired brick wastes, up to 20 wt.%, with clay bodies to produce red ceramics. Cylindrical pressed bodies were fired at temperatures varying from 500 to 1100ºC. After firing, samples were then tested for linear shrinkage, water absorption and mechanical strength. The results showed that brick waste addition did not changed the workability of the clay and that up to 5 wt.% of waste no detrimental effect occurred on the fired properties at all temperatures.

Jan 1, 2010

By G. R. Brough

"Today it is more important than ever to get the maximum possible return on capital invested in the processing industry. To this end the plant is often operated continuously and the choice of equipment is, consequently, extremely important.Screening spans a wide range of particle sizes and there are many different types of screening elements. The following types are common:1. Cloths and elements of rubber.2. Wire mesh screens with round wires.3. Wire mesh screens with profiled wires.4. Perforated steel plates.5. Elements of plastic.6. Gratings of steel beams.7. Gratings of iron rods.We would like to deal with two of these types namely rubber and briefly on plastics.We first introduced rubber screens to the Canadian Mining Industry in November, 1963. This stemmed from a conversation with the superintendant of one of Canada's largest screening plants containing 48 vibrating screens, with an average wire cloth life of 10 to 12 days. We contacted the manufacturer of rubber screen cloths who had supplied rubber screens to a mine in Northern Sweden for a 50,000 ton per day plant in 1951."

Jan 1, 1983

By Orhan Gokce Goksu

It has been shown that metallic tungsten powder can be obtained by electrochemical reduction of solid CaWO4 in molten CaCl2-NaCl eutectic mixture at 600oC. In this study, constant and pulse voltage electrolysis experiments were performed to optimize reduction kinetics and obtain information about the mechanism of above process. It was found that pulse voltage applications yield faster reduction rates when average voltage of pulse voltage application was the same as constant voltage application. In addition, analysis of the current vs. time graphs of constant and pulse voltage electrolysis studies showed that reduction occurs at potential differences higher than about 2.2 V between CaWO4 cathode and graphite rod anode.

Jan 1, 2010

By Augustine O. Orumwense, Micheline Boisclair

"The use of stirred mill to complement tumbling mills in grinding fine grained minerals is increasingly becoming an attractive processing option. Parameters such as agitation speed, grinding media type and size, feed pulp density, and grinding time were studied in order to elucidate their impact on stirred milling. Test results showed that the parameters have a profound effect on stirred mill efficiency and operating cost. A comparative test with a tumbling ball mill was also made and the specific energies of both mills in fine grinding were analyzed. A difference of over 40% in energy savings particularly when the product size is smaller than 20 µm was obtained with the stirred mill.INTRODUCTIONIn industrial processes where very fine and ultrafine particles are required such as in chemical, ink, food, paint and lacquer, pulp and paper, plastics, pharmaceutical, metallurgical and ceramic industries, the use of stirred mills for grinding is well established. Mineral processing plants are gradually shifting focus to the use of stirred mills for fine grinding and /or regrinding purposes as the target liberation size gets very small. A number of plants processing finely/sparsely disseminated ores are known to have adopted stirred milling technology for their fine grinding needs (Enderle et al., 1997; Harbort et al., 1999; Gao et al., 2000; Davey, 2003 & 2006; Pease et al., 2006).There are different kinds/designs of stirred mills available on the market but, all can be divided into two sub groups namely fluidized and non-fluidized types. The non-fluidized stirred mills consist of Tower mill, Vertimill, Sala agitated mill (SAM), and ANI-Metprotech (SVM). These mills are characterized by their low-speed and the use of fairly coarse grinding media size, 3 – 20 mm. Hence, they are mostly suitable for relatively coarse grinding application. The fluidized type includes the Isamill, Netzsch mill and Stirred mill detritor (SMD). These mills have a characteristic high agitator speed, use fine grinding media size of 0.5 – 5 mm, and are employed in very fine grinding operations. The superior fine grinding capability of stirred mills is attributable to two main process parameters, which are the use of fine grinding media and a high mill speed."

Jan 1, 2008

By Karl Marquis

La Mine Mouska exploite depuis deux ans certains blocs de réserve à l?aide de la méthode long trou. Même si, à priori, la méthode long trou semble rentable, le contrôle de la dilution ainsi que le respect d?un échéancier serré s?avèrent primordiaux afin que cette méthode d?exploitation puisse être justifiable économiquement. La présentation suivante fera la comparaison économique entre cette méthode et celle de chambre-magasin.

Oct 1, 2001

By Liping Yu Che, Xiaotie Wang, Mingli Cao, Jizu Yongfu Yuan

"It is difficult separating fluorite from Ca, Ba, Si intergrowth minerals than simple from Si, using common reagents such as combination of oleic acid or paraffin soap and water glass, but the finest quality fluorite concentrate whose grade is over 96%F must be required in chemical plant.This paper studies the flotation process of native fluorite from calcite, barite and silicate minerals whose flotation properties is similar to fluorite, using new effective collector H602 and new depressor S602 that is cheaper in cost, and describes the flotation properties. In order to determine optimum flotation separation condition, the effect of pulp pH, pulp temperature, pulp density and the effect of dosage of reagents on flotation were investigated and the flotation result was provided by oleic acid collector and the results of collector H602 were compared with those of collector oleic acid in the test. The test result of ore samples shows that at moderate pulp pH values (10.5-11.5) and other moderate technical conditions, the fluorite mineral can be obtained by new reagents and the rational reagents combination. The conclusion is 98%F of fluorite concentrate can be obtained, using the combination of H602 and S602 and only 5 steps in techniques. The paper discusses the mechanism of the flotation separation of fluorite mineral from intergrowth minerals."

Jan 1, 2003

By Mohamed Ourriban, Yongjun Peng, Qi Liu, Denis Cotnoir

"In the flotation of fine particles, there are two difficulties in general: low recovery of valuable minerals and high recovery of gangue minerals. The low recovery of fine valuable minerals is attributed to low bubble-particle collision and attachment efficiencies, while high recovery of fine gangue minerals is attributed to mechanical entrainment through water films between gas bubbles. Over the last five years COREM has been actively developing fine particle flotation techniques with the objective of improving fine particle flotation separation efficiencies.The fine particle flotation techniques with both generation of micro bubbles and enlargement of sizes of fine particles have been developed to increase bubble-particle collision efficiency. For oxidized fine sulphide minerals, both physical and chemical techniques have been developed to modify the hydrophilic surfaces and therefore increase bubble-particle attachment efficiency. To reduce mechanical entrainment of fine gangue minerals, a new approach, polymeric depression and flocculation, has been developed. By selecting the high molecular weight polymeric depressants to make fine gangue minerals hydrophilic and also enlarge their sizes, entrainment can be minimized. By combining these techniques, we are able to improve both flotation recovery and selectivity in some fine ore flotation systems.INTRODUCTIONWith depleting mineral resources and their declining grades, ores leaving grinding circuit for froth flotation are becoming increasingly finer to achieve mineral liberation. Together with the increasing demand for minerals, ever-increasing tonnages of fines are being produced. Therefore, flotation of fine particles is an immense challenge to be tackled by researchers all over the world today."

Jan 1, 2006

By R. Stefanko

This study concerns itself with the effects of diesel exhaust on mine ventilation systems. The approach here consisted of the development of mathematical models for emissions, dilution, and dispersion of gaseous pollutants from diesels. The general scheme was to use partial differential equations to predict concentration growths. Specifically, the following situations were modeled: 1. A single stationary diesel engine working in a single roadway. 2. A single diesel engine moving with uniform velocity in a single roadway. 3. Multiple diesel engines moving continuously in a cycle in a roadway with appreciable leakage. 4 Multiple diesel engines moving continuously in a cycle in a roadway with little or no leakage. 5. Multiple diesel engines moving randomly in a roadway with uniform air velocity.

Jan 1, 1974

By J. Wickens

Haile Gold Mine is located near Kershaw, South Carolina, approximately 50 miles south of Charlotte, North Carolina. Gold was first discovered at the site in 1827, and the property has been through several operating periods since. The relatively low grade and refractory nature of the deposit has been a challenge for efficient processing since the start of mining on the property. Early processing techniques included gravity separation and barrel chlorination. The last operation employed heap leaching in 1985 through 1992. After being closed and reclaimed for over 20 years, the property is poised to re-open and produce once again. In this chapter of the Mine?s legacy, flotation and ultra-fine grinding will be employed to achieve economic extraction of gold and silver from the pyrite. This paper briefly reviews some of the mine?s history, the metallurgical testing, the flowsheet and discusses design considerations. KEY WORDS: process plant, flash flotation, leaching, SMD, stirred media detritor

Feb 27, 2013

By Scott Orenstein

Construction blasting has allegedly been the cause of property damage in the following situations: (1) When the detonation of the shot hurls rock and debris into the air that causes property damage upon impact; and (2) When property owners notice cracks in their walls and foundations after they experience the momentary vibrations that coincide with the detonation of the shot. The current state of the law for both these situations is firmly established. Blasting is classified as an abnormally dangerous activity, for which the blaster is held strictly liable, whether the damage is the result of flying debris or vibrations and concussions generated by the blast. It is when the alleged blasting damage is supposedly from concussions and vibrations, however, that the courts usually reach the wrong result. The typical scenario involves property owners that thoroughly investigate their property after feeling blast generated vibrations, and find cracks that they believe did not exist beforehand. Most often the truth is that the property owners have never noticed these cracks before because they have never looked that closely before. Any structure has a certain number of cracks due to a variety of causes, such as settlement overtime and temperature and humidity changes.

Jan 1, 2004

By Bruce Mennie

PT Freeport Indonesia (PTFI) operates copper and gold mining operations in a mountainous area of the Mimika regency, near Tembagapura, Papua (formerly, Irian Jaya), Indonesia. The mining and concentrating operations typically produce 240,000 metric tonnes per day of Copper and Gold ore from the combined mining of an 80,000 tonne per day (ore) block cave operation (DOZ Mine) and a 160,000 tonne per day (ore) open pit mining operation (Grasberg Open Pit). The Grasberg Open pit mine will be complete in 2016 at which time PTFI?s operations will convert to Underground. Mining operations will transition from today?s mixed surface and underground operation to full underground mining over the next 6 years. This paper reviews the history of Redpath?s relationship with PTFI, beginning with a raiseboring contract in 1981 and evolving into vertical and horizontal development contracts of up to 37,700 equivalent metres of lateral development and 4,000 metres of vertical development in 2011. An overview of the current operations (PTFI?s Grasberg Open Pit and DOZ Underground Mines) and transition period (challenges for the transition from current to future underground mines) is presented with details of development of common underground infrastructure and future mines; Big Gossan Mine, DMLZ Mine, Grasberg Block Cave Mine, and the Kucing Liar Mine.

Oct 1, 2010

This paper reviews recent positive developments in Europe on the regulation of gold mining. However, it also examines the problem that while gold projects may be bankable and technically and environmental defensible, the odds tend to be stacked against granting of an environmental permit. The historic background to this situation is examined and current developments and initiatives are critically analysed. Standards and benchmarks for the industry have been established across the community and these have a strong influence in European Union accession (and aspiring) states as well. While this is welcome in regard to improving environmental performance, it also represents a significant milestone with mining (and particularly gold mining) now æon the mapÆ as a legitimate enterprise, a situation that was patently not the case prior to 2003. At the project level, very frequently, the difficult biophysical problems are addressed and satisfactorily dealt with according to the new regulations, but still there are problems regards trust and acceptance that underpin a æsocial licenceÆ. What goes wrong and how can companies deal with the social/environmental issues that lead to entrenched views and concerns, irrespective of any amount of demonstration of good practice and corporate social responsibility? What is the role of the non-governmental organisation (NGO) and are they as accountable and responsible as they should be? The findings presented draw upon recent experience with the environmental permitting of projects in Spain, Greece, Romania, Bulgaria and Serbia on behalf of Australian, Canadian and British companies as well as international funding institutions.

Jan 1, 2007

By Michael J. Rinker, P. A. Tibble, M. Wiseman, R. V. Nicholson

Tailings, from an active copper-zinc operation, containing about 10% sulphur were investigated to assess the onset of acid production and potential lime requirements for treatment of drainage. Oxygen consumption rates were measured over two years to verify spatial and seasonal variations in sulphide oxidation rates. Shallow cores were collected to assess the quality of tailings porewater and to characterize solids that had been subjected to oxidation and depletion of neutralization potential (NP) for several years. Oxygen consumption data were used to quantify rates of NP depletion and onset of acid drainage from the near- surface tailings. Based on measured oxygen consumption rates and identification of NP remaining in the tailings, future lime use in the treatment plant was expected to rise significantly without mitigation. Geochemical modeling calculations were calibrated with observed oxygen consumption rates and the model results agreed well with actual lime use in the waste water treatment plant during operations. The modeling also demonstrated the benefits of lower lime demands and treatment costs after closure as a result of construction a soil cover on the acid generating tailings.

Jan 1, 2000

By Chu E. Ho

Key variables that govern the jet cutting process are examined based on fundamental theories of jet hydrodynamics and soil mechanics. Under normal conditions of jet grouting operations, lift speed and rotation speed are found to be of less importance than the depth of jetting, nozzle pressure, nozzle diameter, and the soil bearing resistance, with regards to their influence on jet cutting distance. An analytical equation linking the governing variables is proposed, which allows for the possibility of evaluating column diameters achievable in different ground conditions based on theoretical calculations. When used in conjunction with shallow jet grouting field trials, the equation can provide a means for extrapolating trial results to conditions at actual depths for production jet grouting.

Jan 1, 2006

By John F. Elliott

Because of the importance of the steel industry in the economy, a program of study was undertaken to develop a computer model by which it would be possible to predict the need of the industry for raw materials and energy in the next several decades. This report gives the results obtained it a preliminary 6-month program.

Jan 1, 1973

By Donald O. Capstick

A mineral survey of a 5,700-acre portion of the 11,510-acre Upper Deep Creek Wilderness Study Area (ID-111-44B) in southwestern Idaho was conducted by the U.S. Bureau of Mines in 1985. No mining claims have been located, no minerals have been produced, and no resources have been identified in the study area. Three reconnaissance samples of alluvium from the Deep Creek drainage contained $0.21, $0.22, and $2.72 per cubic yard in placer gold, higher than usual for the Owyhee River canyonland area. The samples of near-surface material contained very fine gold in values too low to support large-volume commercial placer operations, but the quantity and size of the particles of gold in the alluvium is expected to increase near bedrock. Consequently, the area may be a target for recreational as well as small commercial suction dredge operations. The physical characteristics of the individual pieces of gold (bright and angular) indicate that it may have recently come from an unidentified nearby source.

Jan 1, 1986

By Barbara Hendrickson

Outline ? Canadian Regulatory Update ? Turning the Corner: Background & Status ? Implications of U.S. Waxman-Markey bill for Canada ? Federal-provincial considerations ? Current certainties and uncertainties ?Turning the Corner? as Originally Proposed ? April 26, 2007 - the Canadian federal government announced Turning the Corner: An Action Plan to Reduce Greenhouse Gases and Air Pollution (?Turning the Corner?)

May 1, 2009

By Steve Tadolini

Underground roof falls can have devastating effects on the safety of operations personnel, and equipment, and seriously impact production. Immediate steps are usually taken to danger off and secure the area while clean-up efforts are designed and implemented. A critical step, often overlooked due to production demand, is the determination of - why the roof fall occurred so that additional occurrences can be avoided in future developments or what measures can be taken to identify areas that have similar ?symptoms?? Forensic engineering includes the investigation of materials, products, structures or components that fail or do not operate/function as intended. The authors define forensics in ground control engineering as the study of evidence discovered while examining underground roof falls by applying expert observational techniques and established mining engineering principles to determine the probable cause, hypothesize solutions, and design engineering safeguards to prevent reoccurrences. Simply stated, the primary steps in the forensics of underground roof fall techniques are: ? Assess regional and local conditions prior to the event. ? Assess post-event conditions. ? Hypothesize plausible ways in which the pre-event conditions ? became the post-event conditions.Search for evidence that either denies or supports the various ? hypotheses.Apply engineering skill to relate the various facts and evidence into a cohesive scenario of how the event may have occurred. This paper details the proposed technique by utilizing a roof fall case study that required the examination of five primary factors: mine design parameters, excavation geology, method of excavation, method of support, and mining cycle times.

Jan 1, 2009

By M. Rossi

Geologic ore controls are usually interpreted and modeled from cross sections and plans, as they are critical to construct meaningful and accurate ore reserves models. The geologic boundaries are often modeled as two-dimensional surfaces or three-dimensional solids and used as hard boundaries to constrain the grade estimates. In many cases, the geologic model is the most important factor in estimating the mineralized tonnage predicted by the reserves model, since it is generally drawn to separate the volumes of mineralized and waste material within the deposit. Because geologic models are interpreted from widely spaced drill hole data, the accuracy of the contacts of the different zones modeled could be poor. The lack of accuracy in the definition of geo-logic zones can have a significant impact on a resource model. In this paper it is shown that the geologic interpretation can and should be checked for potential biases. In particular, an unbiased overall volume of the original drill hole information with respect to the resulting solids and codes assigned to the block model is sought. In addition, geostatistical conditional simulations can be used to simulate the geologic attributes modeled, thus providing an alternative view of the geology, and a measure of the uncertainty of the geologic boundaries. The simulated geologic model provides an assessment of the impact of alternative geologic interpretations on the over-all uncertainty of the reserves model. In the case study presented here, the uncertainty of the geologic model is quantified for a difficult-to-model, high-grade copper deposit in northern Chile.

Jan 1, 2004

By Thomas Barczak

Roof support systems are designed for roof control to prevent unplanned falls. It sounds logical and has been the conventional thinking in support design since supports were first installed. In order to determine which support system should be used or which would be the most effective, the degree of control provided by the support system must be known. This question embodies the concept of a ground response curve, which is a measure of support control by assessment of the convergence in the mine entry as a function of the support capacity. In this National Institute for Occupational Safety and Health (NIOSH) study to optimize standing roof support design, ground response curves were developed for longwall tailgate conditions from numerical models of Pittsburgh Coal Seam geology. The models were calibrated against tailgate convergence measurements that were made in two Pittsburgh Coal Seam mines as the depth of cover varied during the panel extraction. Ground response curves were developed for four loading conditions: (1) development, (2) side abutment, (3) front abutment near the longwall face, and (4) full extraction inby the face. In general, the tailgate convergence and required support capacity increase through each of these loading stages. It was concluded that prior to failure of the rock mass, the support system regardless of its capacity has relatively little impact on tailgate convergence. Recognizing that the support cannot prevent much of the (pre-failure) convergence that is occurring is an important part of support design. Supports that exhibit high loading stiffness but cannot sustain that loading through a displacement compatible with the ground response curve will not provide adequate roof control because they can fail prematurely. The required capacity depends on the loading plus yielding characteristics of the support and the amount of rock failure that has occurred. The loading plus yielding character establishes where the support loading intersects the ground response curve. Design criterion for support capacity based on the identifying the onset of strain-soften rock response leading to ?damaged roof? is proposed as a foundation for assessing support design requirements. The capacity without accounting for the loading and yielding character of one support should not be used to assess the capacity requirement of an alternative support design, particularly when the loading and yielding characteristics are significantly different. A sensitivity study was made to evaluate the impact of mining height and overburden depth. As expected, the results show that convergence increases with increase in mining height and increase in overburden depth. Some specific support examples are also analyzed. Although this is a first step and the two-dimensional numerical models have limitations, these initial studies provide valuable insight into the control provided by the roof support system and will ultimately lead to optimizing support design based on specific mine site conditions.

Jan 1, 2008