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By J. Loredo

Wastes related to abandoned mine sites can constitute important potential pollution sources, depending on their mineralogical and geochemical characteristics and volume. Mine waste disposal sites contain a diverse variety of wastes including overburden material and waste rocks, the ore which cannot be economically removed and wastes from the smelting processes when they are accomplished at the mine site. These materials are usually heterogeneous in size, mineralogy and metal concentrations. Asturias, in northern Spain, has an extensive mining history and, in consequence, there are abundant unreclaimed and derelict mine sites with abandoned mines and spoil heaps of different age, morphology, content and dimensions. In these spoil heaps, waste materials are subjected to the intense action of a humid environment, so the instability of sulphides and sulpharsenides results in the production of acid and metal-rich leachates, which are incorporated to surface water or infiltrated through the land reaching groundwater bodies. The mineralogical and geochemical characteristics of the stored materials are key data to evaluate if they represent an environmental risk. Mineralogy and geochemistry of wastes and the particular specific environmental conditions of each site affect the rate of weathering and therefore the metal release. The characterisation of mine wastes is a necessary step in order to establish suitable assessment strategies with the aim of reducing the leaching, transport and widespread of ecotoxic elements from mining wastes to the environment (surface water, sediments, soils and air). As a consequence of the weathering of As-rich mineral phases, high arsenic contents are commonly detected in effluents from mine voids and spoil heap leachates.

Jan 1, 2006

By Liguang Wang, Roe-Hoan Yoon

The thin film balance (TFB) technique was used to measure the equilibrium film thicknesses (H3 between two air bubbles in sodium dodecyl sulfate (SDS) and electrolyte (NaCl) solutions. The results were used to determine the magnitudes of the hydrophobic forces (K232) using the extended DLVO theory. The Km values determined from He measurement allowed us to predict disjoining pressure isotherms, which were found to be in excellent agreement with those obtained experimentally using a bike-wheel film holder. The rate of film thinning was measured at low SDS concentrations with varying amounts of electrolyte (NaCl) added. In general film thinning was controlled by the capillary pressure during the initial stages, while it was controlled by the surfaces forces during the later stages. At low NaCl concentrations, it was possible to predict the rate of film thinning using the Reynolds equation, provided that the driving force was corrected for the contributions from the hydrophobic force, which in turn were determined from the KZ32 values obtained from the He values measured experimentally. At high NaCl concentrations, where it was difficult to measure the equilibrium film thicknesses, the contributions from the hydrophobic forces were determined by fitting the film thinning data to the Reynolds equation. The K232 values obtained using both the equilibrium film thickness and the film thinning measurements showed that hydrophobic force deceased with increasing surfactant and salt concentrations. It was found that the hydrophobic force in foam films was very sensitive to the added electrolyte concentration.

Jan 1, 2005

By D. P. Plute

The mechanization of the materials management function must contribute to the overall goal of optimization of profits. A computerized system contributes to the profitability of the company by saving more than it costs to operate. Design and implementation of the sys- tem must respond to the needs of users, the operating environment of the property, and must support the objectives of materials management. Three basic functions interact within the scope of materials management. They are inventory control, purchasing, and warehousing which have the following objectives: 1) Inventory control-to request materials in a timely manner and in quantities that provide the best level of support to users at the lowest cost. 2) Purchasing-to purchase requested materials and services at the required time and at the lowest cost. 3) Warehousing-to efficiently receive, store, and issue materials and to prepare accurate transaction documents for the activities. The development of the mechanized materials management system will require a plan and objective analysis by management and system users of system requirements. A typical plan would include: 1) System Design Objectives-the development of objectives that support mechanization of the materials management function. 2) System Characteristics and Concepts- the development of key system concepts and characteristics, which identify the needs of materials management. 3) System Inventory Item Classification- development and assignment of inventory category codes to inventory items. 4) System Order Decision Rules-the development of decision rules and forecasting techniques to minimize the inventory investment and to provide acceptable support levels. 5) System Report Structure-the development of a report structure to support the goals and objectives of materials management. 6) System Report Design-the development and design of reports for effective utilization of the mechanized system.

Jan 1, 1979

By R. W. Barbaro, J. M. Mutrnansky

This paper presents a nonlinear integer goal programming model that optimizes a mineral production schedule while considering the penalties and bonuses based on quality variations in the final product. It involves five coal quality goals plus a profit objective in its formulation and uses the weighting method of goal programming for a solution. The goals to be sought involve the sulfur, ash, heat content, moisture content, and ash softening temperature of the blended coal product. The model is linear in its handling of most of these goals but uses a piecewise linear integer formulation for the sulfur and heat content bonus and penalty schedule. The model is applicable to any mineral product blended from several different sources and subject to a varying price dependent on blended product quality or qualities. However, it seems to be most pertinent to optimizing production schedules for coal deliveries to power plants. Accordingly, the model is applied to a hypothetical coal production problem where multiple coal mines are operated to supply a final blended product to a power plant. In this example, the price paid for the coal is assumed to be a function of five of the most important coal qualities. The problem is solved as a direct function of the coal supply contract, thus removing the necessity of determining the weighting coefficients on a subjective basis.

Jan 1, 1987

By Yoshio Hiramatsu

In Toyoha mine near Sapporo, the ground temperature is very high, perhaps due to inflow of hot mineral water, the origin of which may be rock masses intruded by the igneous activity in the Tertiary period. The rock masses are found about 2 km east of the mine, their temperature being estimated at from 770 to 870 K at a depth of 3 km. In this mine several veins bearing zinc and lead ores have been mined down to the depth of 300 m from the level of the main entry, of which altitude is 551 m above the sea level. Formerly no attempt was made at development of the deeper part of the mine than the 350 m level from the main entry. Let us indicate hereafter the levels in this mine in such a way that the level 300 m deep from the main entry is denoted as 300 mL. Since 1974, however, the 450 mL of Tajima vein has been developed by deepening No. 5 Shaft to, and by driving drifts in the level. Much hot mineral water has been flowing into the drifts from rock. After twenty-eight months from the beginning of development, the total length of excavation amounted to about 1300 m. The success in development so far may be attributed to cooling rock and air with chilled water and to adopting heat-resisting explosives and detonators. This cooling costed very much and for further development in this level a more effective and economical cooling is desired if possible. To obtain fundamental data for designing an economical cooling, the authors investigated, as a preliminary study, the heat balance in the main drift of 450 mL, by measuring the temperatures of air, rock, hot mineral water, the rates of flow of air and water and so on, in August 1976. They are now carrying out continual measurements of the variations in rock temperature, air temperature and humidity with time. The present paper describes the details of the preliminary study.

Jan 1, 1980

By T. R. Hughes

How do you fit a processing plant underground with minimal change to mine infrastructure and yet maintain economic recovery, operability and maintainability? By combining fine crushing, continuous-gravity recovery and flotation. A modular, transportable processing plant has been designed that is capable of being installed in underground drives/drifts or on the surface. The Python processing plants have been designed to treat 20 or 50 tons per hour of ore to a particle size of approximately 500 µm and recover gold and sulfides into the concentrate. The plant is only three meters wide (including bolt-on platforms) and can be installed on a 1:50 slope, making for very simple installation. Test work carried out by Gekko Systems Pty. Ltd. has indicated that up to 50% of ores tested to date would achieve gold recovery rates of over 90% using this method. The projected benefits of this strategy are numerous and include low overall capital and operating cost, significantly less power consumption compared with traditional milling circuits and low environmental footprint.

Jan 1, 2010

By R. S. Scheetz

The search for a more effective means of coping with methane liberation has resulted in the expanded use of seam degasification. Its advantages are measured not only in reducing the hazards due to methane, but also in producing a marketable commodity: .the gas, itself. However, the success of a methane drainage system is the culmination of many complex factors, the most important being the coal seam permeability. The two most popular drainage techniques used mining today are the vertically simulated borehole method and the in-seam horizontal borehole method. The objective of this paper is to determine the permeability range in which the selection of the degasification technique is based primarily on equipment and economic analysis. A discussion of the equipment involved will be incorporated into examples evaluated by the Penn State coal methane simulation model.

Jan 1, 1989

By C. Timothy Shaw

Traditionally, only the large mining companies have maintained specialist departments in such areas as Rock Mechanics, Ventilation and Safety. To the small companies this has been a luxury that they could ill afford. Any work required by such companies in these areas, more complex than could be handled by the existing staff, was done by consultants. This situation is changing though and there is a need arising for many specialist departments. These changes are partly being brought about by the effects of inflation as the ever increasing costs are causing more and more operators to increase the size of their operations in search of economies of scale. In addition though the plethora of new laws and regulations are creating a need for many more specialists in all areas of mining in order to ensure compliance. The abovementioned factors, added to the existing Pattern of mines endeavoring to improve the working environment for their labor force, both for reasons of practical labor relations and also due to further legislative pressures, have thus created a climate where, in the near future, departments such as Rock Mechanics, Safety, Ventilation, Environmental Engineering and Subsidence Control will be commonplace in mining companies. It will no longer be practical to function without such services. Many mining companies already maintain such departments and this has particularly been true of the big mining groups of South Africa. From the experience gained by many of these large companies with specialist departments, it is clear that the maintenance of a cadre of experienced, competent professionals in such a department has not always been easy. It would seem from the experience gained that one can generalise and state that graduate mining engineers tend not to view specilisation as an optimum direction for their career development. It is of course true that many professionals, especially those with higher than a bachelors degree, do view these areas as valid career options, but even here experience shows that wastage is high. The time therefore seems to be ripe to take a look at this area in some detail to see whether reasons for the problems can be isolated. Working from that some suggestions can be made as to directions in which improvements might be made. If the challenge of the demands of the new regulations are to be met then such improvements must be made.

Jan 1, 1980

By R. Cooper, K. De Wet, A. Janwong

"Horsehead Metal Products is a zinc refinery in Mooresboro, NC, treating crude Waelz oxide (WOX) to produce special high-grade zinc by a hydrometallurgical process comprising leaching, zinc solvent extraction/electrowinning, melting and casting and bleed treatment. Cadmium removal by zinc-dust cementation plays an essential role in the bleed treatment circuit to prevent cadmium buildup in the circuit. Silica, though present at a low level of approximately 0.3 percent in the WOX feed material, had a significant impact on the efficiency of cadmium cementation with zinc dust, most likely due to the passivation of zinc dust particles with silica gel. Solid/liquid separation efficiency by filter press was also affected. To identify the source of the silica issues, silica levels were mapped throughout the circuit, and adjustments, including using pregnant leach solution as the feed to cementation, and pH control in the WOX leaching and neutralization were introduced to mitigate the issues created by silica gel in the circuit. IntroductionLocated in Mooresboro, NC, Horsehead Metal Products Inc. is a hydrometallurgical zinc refinery processing Waelz oxide (WOX) to produce special high-grade (SHG) zinc. The flowsheet, known as the Modified Zincex process, consists of leaching, solvent extraction (SX), electrowinning (EW), melting and casting and bleed treatment (Fig. 1). Cadmium cementation, part of the bleed treatment process, provides an essential bleed of cadmium from the circuit, as metallic cement. The cadmium cementation circuit consists of agitated cementation reactors, a zinc dust addition system, filter presses, agitated purification (releach) reactors and a cadmium concentrate filter press.At the refinery, WOX pulp is leached at a controlled pH to achieve the maximum zinc extraction, according to the main reaction:"

Jan 1, 2016

By S. S. Hsieh

As part of a program to address long-term needs for ensuring adequate supplies of domestic phosphate raw materials, the Tennessee Valley Authority (TVA) has conducted considerable research on dolomitic phosphate rock beneficiation. The discovery that alkyl diphosphonic acids act as phosphate mineral depressants led to the development of several processes involving a carbonate flotation step for the effective beneficiation of these problem ores. Most recently, a partial de-oiling process in which the reagent consumption is greatly reduced has been developed. The reduction is achieved because part of the initial feed is beneficiated without passing through the separate carbonate flotation step. Using this method, a phosphate product containing 30.6-30.9% P2O5 and 0.7-0.8% MgO was obtained from a Florida dolomitic phosphate pebble which contained about 23% P2O5 and 2.0% MgO. The P2O5 recovery was 80.8-86.5%.

Jan 1, 1989

By J. Fuller, L. Marsden

Windborne dust from alkaline salt flats and mining-related tailings ponds is especially prone to threaten applicable ambient air quality standards. Sodium carbonate crystals, typically present, weather to an exceedingly fine, non-cohesive dust, causing air quality problems for miles downwind. Recently developed specialized polymers react with alkaline dust to form sturdy, wind-resistant crusts with good longevity. An on-going demonstration project at a major trona facility has developed techniques for cost-effective application of these polymers over large areas of soft tailings or sediments in a wide variety of situations. Recently treated areas on the order of 80 acres show effective suppression of dust.

Jan 1, 2004

By Samuel M. Cassidy

The exact date of man's first use of coal is lost in antiquity. The discovery that certain black rock would burn was undoubtedly accidental and probably occurred independently and many times in the world over thousands of years. It is quite likely that these independent discoveries were made when primitive man chanced to build camp fires on exposed ledges of a black rock, then was amazed when it caught fire. The Chinese recorded the use of coal 1100 years before the Christian Era and from the Bible we learn that King Solomon was familiar with coal in what is now Syria. In Wales, there .is evidence that the Bronze Age people used coal for funeral pyres, and it is known that the Romans used this fuel. There are other ancient references. So the knowledge that coal would burn, and even some uses of that knowledge, go back thousands of years. However, practical and consistent use of coal seems to date to England in the Middle Ages.

Jan 1, 1981

By Tetsuo Yamazaki

Natural cold seepages are characterized as rapid upward transports of methane from deeper parts of geological structures to the seafloor. Thermogenic and/or biogenic methane generated in deep sediments moves up to seafloor, and major part of methane is consumed in anaerobic oxidation of methane (AOM) and hydrogen sulfide is created in anaerobic sulfate reduction by consortium of microorganisms. Then the hydrogen sulfide is utilized by chemosynthetic communities near the seafloor, such as Acharax, Calyptogena, Bathymodiolus, and the mat-forming bacteria Beggiatoa (Fig. 1). When the supply of methane is large or rapid, remaining methane escapes from seafloor, and it is aerobically oxidized in seawater. A mass balance ecosystem model of chemosynthetic community around natural cold seepages in sediment layer and on seafloor has been created and improved by the authors (Yamazaki et al., 2005; Takeuchi et al., 2007). The model is constructed from 3 main processes as schematically shown in Fig. 2: (1) Methane supply process; (2) Ecosystem process; (3) Water column process. The part of chemosynthetic communities is in the ecosystem process. A numerical model CANDI (Carbon And Nutrient Diagenesis) was developed by Boudreau (1996) to simulate the biogeochemical processes such as organic matter, oxidant, nutrient, bi-product, and pH diagenesis in aquatic surface sediments. Then, the improved version named C. CANDI was developed (Luff and Wallmann, 2003; Luff et al., 2004). The authors created the same type carbon and nutrient diagenesis process model with calcium carbonate formation like C. CANDI (Yamazaki et al., 2005), and have added the sulfur oxidizing and immobilization processes (Takeuchi et al., 2007). The sulfur oxidizing and immobilization processes are connected with the carbon and nutrient diagenesis process model.

Jan 1, 2008

By Daniel H. Stevenson

Safety and health are fundamental values at Barrick Goldstrike. An effective safety and health program protects employees, controls costs and increases productivity. Barrick Goldstrike believes that all occupational injuries and illnesses can be prevented and that safety must be the responsibility of every employee on the property. Safety and health must be thoroughly integrated with the company's efforts to maximize production at the lowest reasonable cost. The goals of safety and production are not mutually exclusive. They must work together to achieve safe production. Barrick Goldstrike began to mine the Betze deposit in 1987. From 1987 to 1992, Barrick employed a traditional safety system using safety specialists on each crew. These specialists were responsible for ensuring that the work areas were safe and that employees were properly protected and trained in safe work procedures. As the work force increased, it became apparent that this system was not the most effective method of ensuring safe production. In 1992, Barrick Goldstrike implemented a loss control program. It was modeled after the International Loss Control Institutes's (ILCI) International Mine Safety Rating System. This program was based on the philosophy that safety is a management responsibility. It can be managed in the same manner that production and cost issues are managed. Under the loss control system, safety needs are identified and evaluated. Programs with performance standards are developed and implemented and the activities and results are regularly monitored. Between 1992 and 1996, Barrick Goldstrike worked at developing and improving its safety management systems. These efforts had a positive return. The incident rates began to decline as these improved systems were implemented. Studies were undertaken in early 1996 to evaluate the effectiveness of the safety and loss control programs in reducing accidents. The studies showed a strong correlation between the implementation of the loss control programs and the resulting reduction in all accidents. Studies in the process division revealed that Barrick had experienced reductions in personal injury accidents from the projected number that could have been expected had no changes been instituted. These reductions ranged from 39% in 1993 to 59% in 1995. These reductions from the projected rates held true for all types of accidents; personal injury, property damage and Mine Safety and Health Administration (MSHA) reportable.

Jan 1, 1997

By Charles A. Edwards, Kenneth D. Merrill

The Construction of the Northeast Extension of the Baltimore Metro involved soft ground, compressed air tunneling. During the tunneling, gasoline and dry cleaning fluid contamination were encountered. Innovative approaches and solutions were developed to address these problems. Special emphasis was on the problem of compressed air pushing gasoline vapors into surrounding communities, resulting in an extremely dangerous situation and a public relations nightmare. Guidelines and standards were established for working in this contaminated environment. Also, through a proactive approach by all parties, all claims and disputes have been resolved.

Jan 1, 1995

By D. R. Nagaraj

The chemistry and structure-activity relationships for four new classes of sulfide mineral and precious metals collectors developed recently are discussed in this paper. These collector classes are alkoxycarbonyl alkyl thionocarbamates and thioureas, dialkyl (or diaryl) monothiophosphates and dialkyl monothiophosphinates. The main emphasis will be to highlight the differences between collectors and their affinities for various minerals on the basis of data on kinetics of adsorption on pure minerals, natural ore flotation and microscopy of flotation concentrates. The mechanism of interaction of these collectors with sulfide minerals is also discussed with the available data on the FTIR and solution chemistry studies.

Jan 1, 1989

By Yun Bai, Ang Chen, Xiangdong Hu, Yanfei Zhu, Gang Li

"It is well known that tunnelling involves a high degree of risk. Conventional risk management only evaluates risks and chooses mitigation measures before the start of a project. However, mitigation measures also introduce risks, which are ignored in the conventional risk control process when choosing different measures. The Multiphase Risk Management Method (MRMM) takes the risk of mitigation measures and dynamic risk control into consideration. This paper introduces this new method and provides a flow chart for better understanding. A case study of the MRMM is given based on Ningbo Metro Line 3, the first quasi rectangle shield tunnel in China. INTRODUCTION Tunnelling itself is generally complex and involves a high degree of uncertainty (Huang, 2006; Thompson and Thompson, 2006). In recent years, several metro tunnel projects in China have been involved in accidents (Wang, 2006; Gong and Zhang, 2012).As a result, Chinese tunnel engineers are paying more and more attention to risk management in tunnel projects (Xiao-lin and Ping et al., 2009; Zhong and Jia et al., 2014), and scholars around the world have put forward many management processes. Existing risk management mainly focuses on a particular stage of a tunneling project. Tunnel engineers or other project parties usually carry out risk assessment and set up schemes or choose mitigation measures before a project begins. The risk from this initial risk assessment may be defined as the initial risk (Bai and Dai et al., 2013). This kind of managing process has been widely used for its simplicity and comprehensibility. However, this static theory cannot properly reveal the dynamic character of the risk during tunnelling. In addition, to reduce the risk from unacceptable level to acceptable level also calls for optimum measures. Therefore, the multiphase risk management method was proposed (Bai and Dai et al., 2013). The purpose of this paper is to introduce and develop the MRMM, and to provide a brief flow chart to illustrate the risk management process based on it. Finally, an example of the first quasi rectangle shield tunnel in China in Ningbo Metro Line 3 is illustrated. It analyzes the initial and secondary risk and sets up a risk control system."

Jan 1, 2016

By Stefano Colombelli, Nicola Bona, Gabriele Eccher, Luca Schiavinato, Paolo Cucino, Domenico Nave

"BIM technologies provide tools and processes to effectively support the entire life of an infrastructure, from strategic planning to maintenance. As a consequence, infrastructure design processes currently make frequent use of BIM tools. This paper describes the BIM oriented design of the underground railway extension in the metropolitan area of Catania. The paper highlights the design process and the chosen BIM tools considering the boundary conditions characterizing the project, i.e. basic information missing in the final design project, need of coordination between different design disciplines and designer companies, and, finally, need for a flexible design approach able to adapt to changes occurring during design development. INTRODUCTION The underground railway extension in the metropolitan area of Catania is composed of two lots of approximately two km each, namely “Stesicoro-Aeroporto” and “Nesima –Misterbianco”. Works to be realized are: •,Main tunnel: mechanized tunneling using a TBM-EPB machine, for the entire length of the lot; •,Underground stations: San Domenico, Vittorio Emanuele and Palestro, conventionally excavated as enlargement of the TBM tunnel after the partial demolition of precast segments; •,Ventilation and emergency shafts: connecting seven tunnel levels to road level on Stesicoro-Areaposto lot, six on Nesima-Misterbianco lot; •,Additional structures such as technical rooms and parking lot; •,Electric Substation at Monte Po' stop; •,Temporary works: TBM launching and arrival pit to be dismantled at the end of the works."

Jan 1, 2016

By Dean H. Herrick

The production of crushed stone in the United States has exceeded 1.0 Gtpy since 1987. Eighty percent of the crushed stone produced is used in the aggregate industry, accounting for over half of the quantity of natural aggregate consumed in the United States. Approximately 718 of the crushed stone produced in 1989 was limestone and dolomite followed by granite, traprock, sandstone and quartzite, miscellaneous stone, marble, shell, calcareous marl, volcanic cinder and scoria, and slate in order of descending volume (Table 1). Of the remaining 20% crushed stone produced in the United States and not used as aggregate, 12% is used in the manufacture of cement which is an important construction material. Only 8% of crushed stone is used in specialty products not associated with the construction industry. Therefore, this chapter will concentrate on crushed stone as used in aggregates, with occasional reference to other uses or to chapters which discuss specific nonconstruction uses of crushed stone. Construction aggregates are hard, essentially inert materials suitable for being formed into a stable mass by the addition of cementing or binding materials that produce a concrete by compaction, or by natural weight to produce a road or foundation fill. Aggregates are usually from 80 to 100% of the material volume of the construction masses in which they are used. Conditions necessary for a rock deposit to be developed for construction crushed stone include: Quality-should pass rigid specifications for strength and durability; Quantity-adequate volume of rock is needed to have a production life of at least 10 years, preferably 20 or more years; Market-must have adequate market to support a new crushed stone operation; Transportation-transportation cost must be competitive for the intended market; Environmental-the impacts of mining, processing and transportation of crushed stone on the environment at or surrounding the mine site must be within acceptable limits; Permitability-mining, processing and transportation of crushed stone must usually be permitted by governing agency. The following discussion will touch upon all facets of crushed stone operations from the mineral deposit and its geology to technology, uses, economic factors and end with governmental regulations of mining crushed stone. The sections are not designed to answer all questions, but rather to be an introduction to the crushed stone industry. Where more information is required, The Aggregate Handbook by Barksdale (1991) is recommended as the best general source.

Jan 1, 1994

By Rainer Alles, Markus Keller

INTRODUCTION For overland conveyors of several kilometres length and as well as wide for conveyors designed for high mass flows, the cost for the conveyor belting share is 40% to 50% of the invested cost 173. The German Standard DIN 22101 is used for calculation and dimensioning of - conveyor belts and belt conveyor components. Developments in rubber technology and conveyor belt design required a revision of the standard released in 1982 121, which was published in August 2001 131. New research results and publications 16-9, 13-15] led to a better understanding of the material behaviour and their influences on conveyor belts. Test and calculation methods have been established to determine the most important parameters which are related to the performance of a conveyor belt line. These parameters are • The running resistance of the idlers • The indentation resistance of the belt • The dynamic splice efficiency • The distribution of belt load in the splices, transition zones and on pulleys. As a result, new rubber compounds with low indentation losses allow the use of reduced friction coefficients and thus lead to reduced power consumption, smaller drives and lower belt tensions. The deeper understanding of the flux of forces within belt splices led to both optimised splice design and optimised rubber compounds which significantly improve the dynamic splice efficiency. Therefore, in accordance with the standard, the benefits of these technologies and the better understanding of material behaviour allow a reduction of belt strength still maintaining sufficient safety factors. Thus engineers are enabled to calculate belt tensions more exactly and users are encouraged to pay more attention to starting and braking techniques. DETERMINATION OF DRIVE FORCE According to the DIN standards the resistance to motion generally has to be determined for each different section of the belt conveyor including upper and lower run separately. The necessary drive power P is calculated as [ ] with v as the conveying speed. The total of all resistances to motion of carry and return run can be determined as [ ] FHo and FHu are the primary resistances consisting of the running resistances of the idlers, the indentation resistance of the belt, the fulling of the conveyed material and the flexure of the belt. While indentation resistance and idler resistance are measurable, they have been deter- mined to be responsible for up to 70% of the primary resistances covered by FH. Further FN is the secondary resistance that covers, for example, the resistance of feeding points and scrapers. Fa are the total slope resistances and Fs is the total of all special resistances, resulting, for example, from belt steering devices. These three resistances should be neglected in the following discussion. For conveyors where a determination of the substantial parts of the resistances to motion is not possible, according to the new DIN standard [31 a determination of the drive power is acceptable by using the fictitious friction factor) [ ] In this formula the index i identifies the individual section of the conveyor, 1 is the length of the section and MR, MG and ML are the related masses of the idlers, the belt and the load in kg/m. The fictitious friction factor f determines the ratio between the overall resistance to motion and the total of moved masses within the

Jan 1, 2004