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By R. N. Murarka

"Hydrocyclone modelling and selection procedure is illustrated. Computerized procedure for hydrocyclone cut size determination for grinding and non-grinding applications is described.A standard procedure for evaluating operating hydrocyclones is described in detail. Many case studies are illustrated comparing actual plant performance with the computer simulation output in terms of overflow product size distributions.INTRODUCTION Cyclones are widely used for applications such as: close circuit grinding, backfill, tailings and dewatering. Normally, cyclones are used for very fine separations where screens are not suitable or too expensive. Figure 1 shows the separation size range of various classifying devices. Cyclones are popular because of their low capital and operating cost. Cyclone selection procedure for different applications depends on the amount of information available on the cyclone feed slurry characteristics. Closed circuit grinding applications will be discussed in detail in this paper. The Cut Size:The size of the material in the feed which reports 50% to each product stream (i.e. underflow and overflow), after correcting for the feed solids by-passing with the underflow liquid, is termed the cut size or ""d50c"". This is often used as the criterion and the basis for cyclone design.When the corrected recovery to underflow of each mesh size in the feed is plotted against the geometric mean size in microns on a log scale, the micron size corresponding to 50% recovery is the d50c size."

Jan 1, 1992

By M. E. Kuchta

Research is currently being conducted at the Colorado School of Mines in the use of high-pressure water for scaling down loose rocks in underground mine openings. In addition to improved miner safety, the adhesion strength of shotcrete applied to rock surfaces treated with high-pressure water is also increased significantly resulting in improved overall support capabilities of the shotcrete layer. Test results show an increase in adhesion strength by a factor of four on a concrete test wall cleaned with water at 21 Mpa (3000 psi) as compared to a surface cleaned at 0.7 Mpa (100 psi).

Jan 1, 2002

By Fang Wu

The paper designs an extraction flow for the total recovery of nickel and cobalt and removing magnesium simultaneously from the cadthodic materials of the spent hydrogen-nickel and cadmium-nickel batteries. The separation of Co, Ni and Mg though P507 extraction .The extraction equilibrium pH is 4.5~5.0, ßNi/Co is 140~180, and ß Ni/Mg is 20~25; nickel and magnesium are scrubbed in two steps, in which the equilibrium pH of nickel and magnesium scrubbing is controlled at 5.0±0.1 and 4.4±0.1 respectively. The stepwise scrubbing technique is adopted to remove 94.5% of magnesium and to recover 99.45% of nickel and 95.35% of cobalt. During the integrated extraction and precipitation process the total recovery fraction of nickel and cobalt are 99.99% and 99.95%, and the recovery fraction of magnesium is 94.02%.The recovered NiSO4 and CoSO4 solution are enriched and crystallized.

Jan 1, 2009

By J. B. Gwiazda

S. Budirsky J.B. Gwiazda's article deals with an interesting problem that has not been studied thoroughly up to now. Gwiazda has proposed a technical solution that eliminates horizontal load imposed by the supports on the roof. That load is due to a discrepancy between the trajectories of the canopy and the overlying strata. It is true that the improved lemniscate guidance system proposed by Gwiazda could eliminate the horizontal load but, on the other hand, it would represent a higher cost of the supports, and it would complicate the already complicated mechanism of powered supports. That is why we must be convinced that the proposed improvement is actually needed. From that point of view, the following questions should be elucidated. As shown in Fig. 1, the point 0 travels along the curve a, which produces horizontal load on the roof in the direction of the coal face. As stated by Gwiazda, "such a high load is capable of destroying the roof above the support, causing rock debris to be scattered around the face." The results of our measurements carried out in coal mines of the Czechoslovak part of the Upper Silesian Coal Basin show that the convergence in the modern type of powered supports does not exceed several millimeters (not more than 10) per hour. Similar conclusions were drawn from field measurements performed in the Polish part of the Upper Silesian Coal Basin (see S. Romanowicz and H. Szopka in Proceedings, Scientific and Technical Symposium Simmex'85, Katowice, Poland, pp. 73-83). The small vertical closure of the supports also induces a small horizontal displacement of the canopy. In addition to this, the transmission of forces between the roof and the canopy is influenced by the layer of debris on it, i.e., the canopy slides without imposing a greater horizontal load on the roof. This was deduced from field measurements of Voest-Alpine F 4/4500 powered supports equipped with rams instead of the common front lemniscate links (denoted as 1 in Fig. 5). In these supports, the pressurizing of the space of piston rod (1a in Fig. 5) causes the rams to close, which induces horizontal load on the roof in a direction toward the coal face. After the setting of a support unit, the pressure in the piston rod space was found to drop, frequently to zero, because the small horizontal sliding between the canopy and the debris or inside the debris caused the horizontal reaction from the roof to fall to zero, although the debris were pressurized by vertical setting load. As a consequence, there was no horizontal load imposed by the canopy on the roof. A rise of the horizontal load was recorded only after the passage of the shearer and during lowering of the adjacent units. Thorough information on the results of the aforementioned field measurement is given in the paper, "Analysis of the performance of shield powered supports installed in a thick seam," published in Mechanizacja i automatyzacja gornictwa, 1982, No. 12, pp. 38-46. An English translation of the paper is available from the author. We have deduced from our observations that horizontal load imposed by the canopy on the roof in the direction toward the coal face is useful for roof control because it limits the displacement of the immediate roof toward the gob particularly during the rise working. We came to the conclusion that horizontal load on the roof toward the coal face should be induced on purpose. Could Mr. Gwiazda prove with the results of field measurements his contrary opinion? Has the small horizontal displacement of the canopy toward the face actually had an adverse effect on the roof? As shown in Fig. 2, during the setting of a support unit, the canopy imposes a horizontal load on the roof in the direction of the gob. In this case, I share Gwiazda's opinion that the horizontal load could have an adverse effect on the roof. Nevertheless, two important circumstances were neglected - the horizontal compliance of the supports and the interaction of adjacent units. The question of the compliance was analyzed precisely by I. Krumnacker in Gluckauf-Forschungshefte, 1984, No. 5, pp. 219-223. He found that due to the clearance between the hinge pins and the eyes of the sheild and due to the elasticity of the steel structure,

Jan 1, 1987

Jan 1, 1967

By P. L. De Bruyn

[According to the Young equation, SG = SL + Coso, the equilibrium contact angle depends on the values of the three interfacial tensions involved. A solute promotes wetting, i. e. a decrease of contact angle if it decreases.LG and/or YSL or if it increases SG. Dewetting, the important step in flotation is, promoted if the solute increases y and/or SL or decreases. Most solutes used for wetting or dewetting are, positively adsorbed at all interfaces involved and consequently according to the Gibbs equation lower the interfacial tensions. Wetting is therefore expected to occur if LG and SL are more affected by the solute than SG. Dewetting on the other, hand demands a greater decrease of SG than that of SL (and of LG). See P. L. de Bruyn, J. Th. G. Overbeek and B. Schuhmann, Jr., Mining Engineering (1954) P. 519.]

Jan 1, 1960

By F. S. Crawford

A large number of operators of various industries in the United States do not appear to realize the great returns in dollars and cents which result from intelligently directed safety work . Managers of co 1 mines , metal mines , open-pit mines , quarries , steel mills , cement mills , oil rei meries , iron works , or other industrial operations , should by all means realize the great waste resulting from accidents , in order to appreciate the necessity for a continuous accident -prevention policy . While the prevention of accidents is worth while from the humanitarian standpoint alone , it has an equally important economic side , and before our mining industrial operations will be made as safe as they should be , it is apparent that this dollars and cents viewpoint must be given full recognition in order to bring before many of the men who run the industries the great importance of this phase of industrial management . : There is a tendency upon the part of the opera or who has not given thought to the cost of accidents ( and there are many mining operators of this type) to insure his company against compensation losses and against catastrophes for which he can secure insurance , and think he has done his duty ar an executive . Even though industrial operations were not compelled to pay compensation , and even if the management were not moved by humanitarian motives to try to stop accidents , it would pay many times over to carry on accident prevention work vigorously and continuously. : In some parts of the United States , the state compensation and insurance requirements are such that the operator does not receive a reduction in his insurance rate per men employed upon having made safety installations or upon having achieved a reduction of accidents in his plant . Under such conditions the management frequently does not feel encouraged to emert much effort in bettering the accident rate . However , when the responsible officials of a company realize the much greater harm to an operation which results from doing no accident - prevention work , and the great benefit in reduced costs which usually follows effective safety work , they should be inclined to do almost everything possible to reduce accidents , regardless of considerations as to accident compensations . There are enough indirect costs resulting from accidents to wreck many types of business ; excessive accidents result in disorganization and failure , while immunity from accidents usually means a smoothly running efficient organization .

Sep 1, 1930

By Stefano Trevisani

Abstract The FIEC Sustainability Vision states that “risks should be identified and allocated in a fair manner across the project team from the early stages of the design phase. A partnering approach, where objectives and timescales are agreed in advance together with all relevant partners in the value chain, offers a useful solution to improve on site efficiency and reduce disputes”. An alliance or collaborative form of contract involving all parties is the best way to ensure fair contract conditions and proper risk allocation in construction projects. Collaborative contracts are particularly useful where there is uncertainty or undefined information or in the event of technical difficulties and other risks difficult to allocate among the parties involved in the project. Owners sometimes require even special output in terms of innovative technical solutions or special performance. In addition, this particular form of cooperation has been construed and developed with the intention of avoiding and mitigating another great risk associated with the construction industry (especially in complex projects): disputes and conflicts, which are often a major cause of delays, increased costs, loss of reputation and opportunities. In contrast, Alliances are a way to increase and strengthen business relationships, technical and economic innovation and effectiveness, in a worldwide global context where the waste of resources must be avoided in order to guarantee future recovery and growth. Of course, the total cost of a project is usually a key factor and the main driver for the Owner and the Contractors in deciding the type of relationship between them as well as the subsequent relationship with subcontractors and lower-tiers. This paper and presentation, will explain the main features and the principle benefits that the use of collaborative contracts can bring to all parties involved in the construction project, including the sustainable financial return that might be achieved if costly and time consuming disputes can be avoided.

Jan 1, 2014

By K. Park, J. Sohn

Recovery of industrially useful metals from various secondary sources is an important issue in Korea whose natural resources are limited and needs in the strategic metals are on the rise. In order to meet such needs, researchers at the Korea Institute of Geoscience and Mineral Resources have launched a number of projects to help the nation to recover various metals from secondary sources. In this study, silver is successfully recovered from spent silver-oxide batteries first by distillation to remove mercury. The distilled residue was next subjected to leaching of silver using nitric acid. The study involves finding optimum conditions to leach silver from the distilled residue and subsequently to recover silver from the leach liquor by chemical precipitation. The chemically precipitated products are then subjected to reduction roasting to recover silver metal.

Jan 1, 2002

By R. D. Sharpe

Gypsum wallboard manufacturers in the United States shipped 3.18 billion m2 (34.2 billion sq ft) of wall-board products during 2004 versus 2.93 billion m2 (31.5billion sq ft) in 2003. Following a historic high production of gypsum wallboard products in 1999, production decreased in 2000. But it has steadily increased during2001 through 2004. Wallboard production in the United States increased about 8.6 percent in 2004 from 2003. Following several years of a “building boom” of new wallboard plants and the expansion of the manufacturing capacity of several existing plants, 2004 was a relatively quiet year. However, several new plants and capacity expansions were announced or are in progress during 2004.

Jan 1, 2005

An independent contractor is defined by the Mine Safety and Health Administration (MSHA) as ?any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine.? Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines.

Aug 1, 2009

An independent contractor is defined by the Mine Safety and Health Administration (MSHA) as ?any person, partnership, corporation, subsidiary of a corporation, firm, association or other organization that contracts to perform services or construction at a mine.? Contractors that perform specific types of work are required to report the number of employees who work at coal mines and noncoal mines. Companies In 2007, a total of 2,999 contracting companies reported employment at coal mines to MSHA, or 35.7% of all independent contracting companies.

Aug 1, 2009

By Persifor Frazer

The following notes on the Whopper and adjoining mines in the Gunnison district of Colorado mere made in the spring of this year. The time chosen for the author to visit the region was, unfortunately, the most unfavorable of an exceptionably unfavorable year. About the middle of May all the hill slopes, which at this period of the pear are generally covered with pasture, were thickly covered with snow. The unusually large precipitation of this Tear caused loacal mountain torrents at every few hundred feet, which wore away the oft foothills into gulches, gouged great chasms out of the roads, and transformed miles of usually dry soil into dangerous quagmires. Travel was totally interrupted for weeks, except on horseback or afoot, and even then with great difficulty and some danger. The Whopper mine is situated on the Whopper Mountain, about two miles from the headwaters of Rock Creek, and on the right hank of that stream. The Whopper Creek flows into Rock Creek horn the east, and, by a precipitous descent, offers excellent facilities for its utilization as a source of power. This stream, which pours past the picturesque Whopper Cabin about thirty tons of water a minute, has a fall of 100 feet in 400 yards, and is said to be a stream of some size, even at the seasons of the year when drought prevails. The Whopper claim extends down the hill a distance of about 250 feet to its intersection with the Whopper Creek (on the other side of which is a small tunnel on its extension called the "Teller") and over the steep hill northwest to the limits of the claim about 1250 feet. The part of the mountain in which this mine is situated is remarkable for its splendid forest, the spruce, fir, and quaking asp covering the mountain-sides with a green growth of valuable timber. The distance from Gothic City to this mine is about eight miles along the valleys of East River and Rock Creek, and on the divide which separates them. The elevation of Gothic City is given from the engineer's notes as 9500 feet above sea-level, and the mean of several observations with a Beck watch-barometer made the elevation of Whopper Cabin (which is about fifteen feet above the floor of the Whopper upper tunnel) about 1260 feet above Skiles's Cabin in Gothic City. The record of this instrument must, how-

Jan 1, 1881

By Persifor Frazer

THE following notes on the Whopper and adjoining mines in the Gunnison district of Colorado were made in the spring of this year. The time chosen for the author to visit the region was, unfortunately, the most unfavorable of an exceptionably unfavorable year. About the middle of May all the hill slopes, which at this period of the year are generally covered with pasture, were thickly covered with snow. The unusually large precipitation of this year caused local mountain torrents at every few hundred feet, which wore away the soft foothills into gulches, gouged great chasms out of the roads, and transformed miles of usually dry soil into dangerous quagmires. Travel was totally interrupted for weeks, except on horseback or afoot, and even then with great difficulty and some danger. The Whopper mine is situated on the Whopper Mountain, about two miles from the headwaters of Rock Creek, and on the right bank of that stream. The Whopper Creek flows into Rock Creek from the east, and, by a precipitous descent, offers excellent facilities for its utilization as a source of power. This stream, which pours past the picturesque Whopper Cabin .about thirty tons of water a minute, has a fall of 100 feet in 400 yards, and is said to be a stream of some size, even at the seasons of the year when-drought prevails. The Whopper claim extends down the bill a distance of about 250 feet to its intersection with the Whopper Creek (on the other side of which is a small tunnel on its extension called the "Teller ") and over the steep hill northwest to the limits of the claim about 1250 feet. The part of the mountain in which this mine is situated is remarkable for its splendid forest, the spruce, fir, and quaking asp covering the mountain-sides with a green growth of valuable timber. The distance from Gothic City to this mine is about eight miles along the valleys of East River and Rock Creek, and on the divide which separates them. The elevation of Gothic City is given from the engineer's notes as 9500 feet above sea-level, and the mean of several observations with a Beck watch-barometer made the elevation of Whopper Cabin (which is about fifteen feet above the floor of the Whopper upper tunnel) about 1250 feet above Skiles's Cabin in Gothic City. The record of this instrument must, how-

Jan 1, 1881

By Ted C. Briggs

A removable-jacket distortion apparatus was constructed and used to measure distortion coefficients for two high-pressure vessels. The measured distortion coefficients were used to compute distortion coefficients for volumes VI and (V1+V2) of a 1,000-atmosphere Burnett compressibility apparatus for the temperature range 0° to 75° C. Young?s modulus for Armco 17-4 PH stainless steel, heat treated to condition H1150-M, was computed from experimentally determined distortion coefficients. A 10-to 14-percent correction to the values obtained for Young's modulus may be required because pressure vessel end effects were neglected. The distortion coefficients of the compressibility apparatus are believed to be accurate to about 1 percent.

Jan 1, 1970

By A. Ahmed, A. Fathy, M. Eissa, K. El-Fawakhry, A. El-Mohammady

Silicomanganese is widely used as a complex reducer and an alloying addition in the production of various grades of steel due to its economic and metallurgical advantages. It is also used as a semi-product in the manufacture of medium- and low-carbon ferromanganese and metallic manganese. Manganese-rich slag, resulting from high carbon ferromanganese production, has the advantages of high manganese content, high Mn/Fe ratio, low excess oxygen, low phosphorus content, low fine content and low cost. Such slag seems to be very attractive to use as raw materials for the production of silicomanganese alloys. In the present study, experimental heats were designed and carried out to optimise the factors affecting the production process of silicomanganese using manganese rich slag in the charge. The results of pilot plant experimental heats showed that the optimum metallic yield and recoveries of manganese and silicon are obtained with initial slag basicity,(CaO + MgO) / (Al2O3), equals 1.8 by using dolomite as fluxing material and charging quartzite and fluorspar in percentage of 25% and 4% of the blend, respectively. The results showed also that an amount of 30% of coke in excess of the stoichiometric amount should be added. These result are relative for the specific high Al2O3 ores used.

Jan 1, 2004

By R. Oler

The need for yieldable ground support, particularly in high stress or deep mining conditions, has grown in recent years. This paper highlights some of the current industry limitations and provides selection criteria for a new yielding ground support system, DSI?s Dynatork Bolt. This bolt distinguishes itself by withstanding 16 ? 30 kJ of energy deflecting loads anywhere from 7 ? 20 tons (depending on the energy). A summary of the laboratory test results and case studies will also be presented as a measure of the performance of this dynamic product.

Jan 1, 2012

By A. P. I. Popoola, T. J. Olaniyi, A. A. Adeleke

"A laboratory froth flotation experiment was conducted on a low-grade carbonatite copper ore sample obtained from Phalaborwa in the Limpopo province of South Africa. The sample was a homogenous hydrocyclone overflow which serves as the feed to the flotation cells at Palabora Mining Company (PMC). The sample has an average copper assay of 0.59% with predominant copper-bearing minerals being chalcopyrite, bornite and cubanite. The carbonatite nature of the ore comes from the high content of calcium (28.85%) and magnesium (6.84%) minerals. Collectors used were sodium diethyl dithiocarbamate and potassium ethyl xanthate alongside Senfroth 38 supplied by Senmin. The results showed that at 200 g/t mixture of collectors (50:50), an optimum grade of 8.03% Cu in the rougher flotation concentrate was achieved at 74% recovery, while during the second flotation, 24.65% Cu was obtained at 74.4% recovery using a Senfroth 38 dosage of 6 L/t with 100 g/t mixed (50:50) collectors. The particle size and pH value of the pulp played a significant role in that the mixed collectors performed efficiently at pH above 8.3 and at room temperature while particle sizes greater than 53 µm were well concentrated when compared with those of less than 53 µm. INTRODUCTION The need for copper ore concentration research is on the rise as a result of the depletion of deposits and the advent of low-grade copper ores. Although most copper ore deposits have other valuable minerals that support their economic extraction, the increase in technological innovations as regards copper usage and applications has increased the demand for copper. Several factors influence concentration results in a froth flotation column, of which the reagent used is most influential."

Jan 1, 2015

By M Olsen, L van den Berg

Bowen Basin coalmines suffer from hot and humid ambient conditions during the summer period. The ambient conditions combined with high VRTs, increasing depth of working and significant equipment heat loads results in heat issues underground. Coalmines operate under heat stress management plans as required by legislation with associated trigger action response plans (TARPs). Some mines also employ refrigeration as part of their heat management strategy.A recent case study was conducted on a mine producing about 4.5 Mt/a from their longwall and experiences summer surface ambient temperatures of about 23.5ºCwb. The expected virgin rock temperature is 46ºC at 300 m depth. The mine currently introduces a modest amount of surface cooling at the portal using ‘off-the-shelf’ air conditioning units. This system does not effectively manage face temperature primarily due to positional inefficiency.Underground conditions remain hot in summer and work is typically undertaken in accordance with the Heat TARP. This has a direct impact on the productivity of crews, worker comfort and also negatively impacts the workforce morale. The mine commissioned a study to determine a refrigeration strategy aimed at maintaining underground conditions below TARP levels 90 per cent of the time.The ventilation network model was calibrated against actual temperature data to simulate the heat loads including longwall, conveyor system, strata and auxiliary diesel fleet. This model was then used to determine the cooling requirements for bulk surface cooling, bulk underground cooling, surface district cooling and underground district cooling strategies.These estimates were used to undertake a total owning cost trade-off for the different strategies. The study concluded that a chilled air shaft has the lowest technical risk but the highest total owning cost due to shaft development needs. Introducing chilled water to an underground cooler via boreholes offered the lowest total owning cost and was therefore recommended.CITATION:van den Berg, L and Olsen, M, 2017. Heat load assessment and mine cooling strategies for a longwall coalmine, in Proceedings Australian Mine Vent Conference 2017, pp 231–236 (The Australasian Institute of Mining and Metallurgy: Melbourne).

Aug 28, 2017

By Trevor L. L. Orr

"AbstractThe background to the harmonization of geotechnical standards that has taken place in recent years in Europe has been the move to more economic and political integration following World War II that has led to the formation of the European Union. Prior to 2010 the standards used in the European countries for geotechnical design, investigation and testing and for the carrying out geotechnical work, such as the installation of piles, were the different national standards, which were not harmonized. The harmonization of geotechnical standards in Europe started in 1981 with work on a model Eurocode 7 for geotechnical design that led eventually to publication by CEN, the European Committee for Standardization, of the European Standard version of Eurocode 7 in 2004. In parallel with the work on Eurocode 7, a large number of associated harmonized standards have been, and are being, prepared by CEN and by the International Standards Organization (ISO) for geotechnical investigation and testing and for the execution of geotechnical works. Standards published by CEN must be adopted by the CEN member countries and all conflicting standards withdrawn. Hence all the CEN countries have adopted the same the harmonized text of Eurocode 7, but with National Annexes that allow national choice with regard to Design Approach and partial factor values. The adoption of Eurocode 7 and its associated geotechnical standards has removed the barriers to geotechnical activity in Europe due to the presence of different national standards. It has also enhanced the ability of EU firms to compete in the global market.Background to harmonization of geotechnical standards in EuropeThe initial moves towards the harmonization of geotechnical standards in Europe can be related to the economic and political developments that took place in the period immediately following World War II to revive the economies of Western Europe. Europe at that time was divided by a political and, in many places, a physical barrier, known as the Iron Curtain, into two very different and separate zones: communist in the east and non-communist in the west. In 1952 the European Coal and Steel Community (ECSC) was formed, linking 6 countries: Belgium, West Germany, France, Italy, Luxembourg and the Netherlands, and establishing a common market in coal and steel. The ECSC was the first international organization to be established on the basis of supranational principles whereby negotiated power is delegated to an authority by the governments of the member states. In 1957 the ECSC became the European Economic Community (EEC), also known as the Common Market in the English-speaking world, with the aim to bring about economic integration. With the addition of Denmark, Ireland and the UK in 1973 and Greece in 1981, followed by Portugal and Spain in 1986, this led to the formation of the European Union (EU) in 1993. East and West Germany were reunified in 1990, following the fall of the Iron Curtain in 1989. In 1995, Austria, Finland and Sweden joined the EU, and since then the numbers of countries in the EU has increased to 28, many of which are countries that were formerly behind the Iron Curtain."

Jan 1, 2014