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The absence of coal face particle management practices heavily penalizes coal transportation from initial loading to final consumption. Penalties include dust problems, significantly reduced mine loading cycle productivity, mine belt spillage, excessively high coal preparation costs and chute and dangerous pulverizer blockages at the final point of utilization. The common environmental and economic enemy is fines. Everyone knows that fines cause safety and environmental dust problems, but few understand that fines also swell broken coal to a point where 5 to 15 percent more time and capacity must be used to deliver the same tonnage. In this paper, methods and rewards for reducing and/or managing fines at the mine face are discussed. Computer-based loading cycle model productivity estimates, viewed from a new perspective, are made on the basis of material volume rather than on the long established and frequently misleading basis of tonnage. After all, it is typically the volume of broken material being transported that defines the capacity of a given transportation system, while the corresponding tonnages are merely a reflection of the specific material densities. Published evidence suggests that the swelling of broken coal can be decreased very significantly using small quantities of certain non-frothing chemicals added to mine face spray water and/or by employing improved mine face breakage practices. In a future paper, the effects on transportation productivity beyond the coal mine will be discussed.

Jan 1, 1994

By J. C. Yingling, J. W. Leonard

Introduction The absence of coal-face particle management heavily penalizes the transportation of coal from initial loading to final consumption. The penalties include dust problems, significantly reduced mine-loading-cycle productivity, mine-belt spillage, excessively high coal-preparation costs, chute blockages and dangerous pulverizer blockages at the final point of utilization. Fine particles commonly cause environmental and economic problems. It is well known that these fines can cause safety and environmental dust problems. But it is not well understood that these fines can also swell broken coal to a point where 5% to 15% more time and capacity must be used to deliver the same tonnage. In this paper, methods and rewards for reducing and/or managing fines at the mine face are discussed. Computer-based loading-cycle model productivity estimates, viewed from a new perspective, are made on the basis of material volume rather than on the long-established, and frequently misleading, basis of tonnage. It is typically the volume of broken material being transported that defines the capacity of a given transportation system, while the corresponding tonnages are merely a reflection of the specific material densities. Published evidence suggests that the swelling of broken coal can be decreased very significantly using small quantities of certain nonfrothing chemicals, which are added to mine-face spray water, and by employing improved mine-face breakage practices. In a future paper, the effects on transportation productivity beyond the coal mine will be discussed. The precursor to the work presented in this paper, involving the bulk density improvement for broken coal and the subsequent production gains for underground coal mines, was earlier presented in Leonard and Newman (1989). In the past, this topic has been studied and practiced only in byproduct coking in the steel industry. However, a potential exists for an increase in coal-industry productivity by improving the bulk density of coal to yield a subsequent reduction in delivered cost. This can occur with breakage, handling and treatment methods resulting in the loading of greater quantities of coal in fixed volumetric capacity haulage units such as mine cars, shuttle cars and scoops. Laboratory-based experiments to achieve an increase in productivity by increasing coal bulk density were discussed in Leonard, Paradkar and Groppo (1992). Chemical techniques using small quantities of commercially available reagents (surfactants) resulted in about a 13% to 15 % increase in bulk density, which was thought to produce a proportional increase in the productivity of a mine, together with a subsequent reduction in cost. The idea is to mix the reagents with the water that is used to spray coal during mining. In this paper, the impact of bulk density improvements on production rates is presented. Increases in production ranging from 60% to 88% of the bulk density increases are projected. This analysis was performed for atypical continuous-miner section. In the following sections, discussion and results of the analysis are presented. Discussion An analysis was performed to ascertain the impact of bulk density improvements on face-production rates for a typical continuous-miner section. Figure 1 illustrates the section layout and cut sequence. This layout and sequence is identical to the case described in King and Suboleski (1991). As can be seen, the section uses five entries and 12.2-m cuts that are taken by a remotely controlled continuous miner. The seam height is 1.5 m and two shuttle cars (5.7 t nominal capacity) are employed for haulage from the miner to the section feeder, which, throughout the cut sequence, is positioned as illustrated in Fig. 1. The simulation model was coded in the SIMAN simulation language. The major impacts of increased bulk density improvements on such a production system are as follows: •Shuttle-car payloads, in terms of the mass of coal transported per haul cycle, are increased proportionally to the increase in bulk density that results from the application of surfactant. •Shuttle-car discharge times should remain largely unchanged, because they are determined by the volume of material that is discharged, rather than the mass, and this volume does not change.

Jan 1, 1996

By Alfredo P. Vargas

Industrial flotation of sulfide ores is 80 years old. It has gone through many advances to date. However most flotation operations are still struggling to improve performance, which as a worldwide average is at the 90% level. What can be done to push the ceiling to 95% or better without performing finer primary grind, nor without duplicating flotation plant capacity? Such "unique task" can be performed by the low volume high capacity new flotation equipment known as the JAMESON CELL, when used as, "post-scavenger" of final plant tails. Improved efficiencies are obtained mainly from two cases: -Particles which never contacted a bubble. -Particles sheared-off by cell turbulence due to reduced number of hydrophobic sites. The application reverses conventional trend of using large volume mechanical cells by trade-in with smaller efficient equipment: resulting in reduced capital expenditures and operating costs. Outstanding "pre-rougher" applications are also presented.

Jan 1, 1993

By L. Michael Kaas

Any increasing number of restrictions are being placed on mining management's ability to pursue profit. Raw materials pricing, the cost of capital equipment, labor cost, and overhead costs, are becoming more difficult to control. Cost reduction is one of the few remaining areas in which management may still exercise its profit making ability. Equipment maintenance is an area where mine and mill management can readily reduce costs and increase profits. Why is this possible? First, maintenance costs comprise a large portion of total operating cost. Thirty to sixty percent of the operating cost dollar is not unusual. Even a relatively small percentage reduction in this cost represents a very sizeable increase to mining profitability.

Jan 1, 1967

By T. G. Bobick

Task analyses were conducted by the Bureau of Mines at four underground low-seam coal mines to evaluate their supply-handling systems and for use in subsequent design of laboratory simulation experiments. Items were tracked (by videotaping) from delivery to the surface storage areas to their final destinations underground. Of particular interest were those tasks that required manual handling of supplies or equipment. Analysis of the videotapes revealed that the miners handled materials while stooped over a total of 37.8 pct of the time, 31.5 pct while on both knees and 9.5 pct while kneeling on one knee. These working postures impose considerable stress on the lumbar spine and may be implicated in the high number of back injuries in this work population. This paper also discusses various mechanical-assist devices developed by the Bureau and successfully evaluated in the underground workplace. These devices can be used to minimize the manual effort and the corresponding risk of injury associated with handling supplies and equipment components in low-seam coal mines.

Jan 1, 1988

By J. A. Herbst, J. E. Bohrer, Y. C. Lo

A systematic approach has been developed to analyze a phosphate grinding circuit with a view toward determining promising alternatives for increasing mill capacity. This analysis was carried out and capacity increases were predicted in the context of detailed population balance models developed for the plant ball mills and classifier systems. Model development and verification was performed using data obtained in a series of batch tests and two plant test campaigns. The effects of feed rate, percent solids, ball size, and mill material filling, etc., on grinding were investigated in the laboratory and plant. Residence time distribution tests were also performed to determine the transport behavior in the mill. The population balance models were found to provide accurate predictions of full-scale grinding circuit performance. Based on the findings of this study, additional capacity in excess of 25% was predicted for these ball milling circuits by a proper combination of ball size change, mill dilution, and adopting screen classification in place of hydro-cyclones. These predictions have been confirmed by plant tests in which the recommended operating changes have been implemented. Understanding the effects of operating variables on breakage kinetics and the interplay between kinetics, transport, and classification has contributed significantly to increasing the mill capacity.

Jan 1, 1988

By Donna L. Boreck

Introduction Coal has been mined in the western United States since the mid-1800s. The resource is abundant in the West. Despite recent economic conditions, it remains an important part of the nation's energy warehouse. Many of the seams that comprise the western resource base are thick, some exceeding 61 m (200 ft). Multiple, closely-spaced seams or thick coals that split into two or more minable seams are also common. Historically, subsurface development recovered from less than 15% to 50% of these deposits (Matson and White, 1975). This resulted in a substantial loss of inplace reserve due to the limited height that could be mined using the available technology. In an effort to increase future recovery from such deposits, the US Bureau of Mines analyzed the potential for incorporating three thick-seam mining methods into western coal mines. These methods are high-face longwall, multislice longwall, and longwall caving. They were developed in Europe and are being used to mine thick coal seams in Europe and Asia. One aspect that will determine their success in the US is the geology of the individual deposit; namely, are the methods adaptable to the geologic conditions characteristic of western coal? This paper analyzes some of the geologic factors that would affect development of thick or closely-spaced seams using these mining methods. Occurrence of thick and closely-spaced seams Since mining conditions and methods differ around the world, a thick seam is often defined as a seam whose total thickness cannot be extracted using the available equipment. In the western US, the maximum extractable mining height is about 4.3 m (14 ft). For this research, a thick seam was defined as a minable seam 4.6 m (15 ft) thick or more. Since one of the seams is usually lost using standard mining methods, closely-spaced or split seams were also addressed. These were defined as two minable seams 1.5 m (5 ft) thick or more separated by 9 m (30 ft) of interburden. Thick or closely-spaced coal seams are common in the West. Their importance has not been documented due, in part, to the methods used to measure resources. In the past, all reserves greater than 1.1 m (42 in.) thick for bituminous seams and greater than 3 m (10 ft) thick for subbituminous seams were grouped together and were differentiated only by rank. Further differentiation by seam thickness or minability was not done. For this reason, reserve figures for thick or split seams are difficult to determine. By analyzing available published resource data, Ferm and Muthig (1982) addressed thick seam resources. They estimated a resource of 90 Gt (99 billion st) of coal (16% of the Western resource base) in seams 4.6 (15 ft) or greater at less than 610 m (2000 ft) overburden. Yet, a later study of Pierce and others (1982) on one thick seam deposit in the Powder River Basin estimated a resource of 103 Gt (113 billion st). Pierce (1986) reported that the overburden reached a maximum of 731 m (2400 ft). The resources in this single deposit exceeded the 90 Gt (99 billion st) total projected for the entire western US by 12.7 Gt (14 billion st). Due to such differences, this author chose to look at reported occurrences of thick or closely-spaced minable seams in place of resource figures, to verify the need to research thick seam mining in the West. An occurrence was defined as an isolated site where a thick seam or two or more closely-spaced seams were reported. The occurrences were derived from published material - mostly mine descriptions, measured sections, coal exploration logs, and oil and gas logs. Due to time constraints, the reserves associated with each occurrence were not determined. All data points were random. The analysis was limited to occurrences in Colorado, Wyoming, and Utah. Although source material available to the author was limited to general coal summa-

Jan 3, 1988

By Eric Forssberg, Ming-wei Gao

Four parameters of the Drais stirred ball mitt, i.e., bead load, bead size, flow rate and top feed size have been studied regarding their influence on the specific surface area. A factorially designed scheme was employed for conducting 27 mitting tests. The results show that the bead toad is the most important parameter in terms of increasing the specific surface area with less energy consumption. The bead size is also important. The optimum ratio of bead size to top feed size is found to be 14 to 80, which is much wider than in bat2 milling. The variations in flow rate and top feed size appear to influence the process insignificantly.

Jan 1, 1992

By Gary Johnson, Bill Mackenzie

The Paddy's Flat plant of Dominion Mining Limited was commissioned in March 1988 with a design throughput rate of 700,000 tpa. The plant now treats ore at an annualised rate of over 2,000,000 tpa. The only major capital improvement to the plant has been the addition of a pebble crushing circuit. Whilst significant changes in the average hardness of the ore being fed to the plant have obviously occurred, a number of processing innovations have been necessary to enable these throughputs to be maintained. The treatment of ore types with a wide variety of physical properties has been a feature of the operation of the Paddy's Flat plant. The leaching characteristics of the ores are relatively straight forward, and it has been possible to considerably enhance the rate of gold extraction from the ore. Reserves of soft surface ore have been increased which has created the opportunity to improve the profitability of the operation by increasing throughput to considerably above the design level, without having to increase the capital investment in the plant.

Jan 1, 1992

Cost accounting information is used primarily for (1) planning, control, and performance evaluation; and (2) managerial decision-making. Incremental analysis is a tool for managerial decision-making. It is designed to estimate future financial performance, namely the benefits and costs associated with alternative courses of action. Decisions may be distinguished as pertaining to short-term or long-term activities. Long-term activities frequently focus on capacity decisions and the attendant capital budgeting processes used to quantify the financial effects of these decisions. Short-term decisions typically address short-range production quantity and pricing issues, outsourcing, selection of the optimal mix of products, inventory management, and the acceptance of special orders. This chapter addresses these short-term decisions.

Jan 1, 1999

By Roger L. Hulette

Mt. Newman Mining Co. is now completing an expansion program, begun even before initial construction was complete, which will result in facilities with the ability to ship over 30 million tons of iron ore per year by early 1973. Confidence in such rapid future growth was evidenced by careful planning for the future expansion of those facilities provided for initial operation of the project which first shipped ore on 1 April 1969. Ore sales contracts totaling more than 300 million tons have been negotiated, thus justifying the optimism which led the joint venturers to provide over $200 million in initial investment and a like amount in capital required to finance the continuing expansion program. Members of the Mt. Newman Joint Venture are: Amax Iron Ore Corporation - 25% (a subsidiary of American Metals Climax) Pilbara Iron Ltd. - 30% (a subsidiary of Colonial Sugar Refining) Dampier Mining Ltd. - 30% (a subsidiary of Broken Hill Proprietary) Seltrust Iron Ore Ltd. - 5% (a subsidiary of Selection Trust Ltd. of London) ? Mitsui C. Itoh Iron Ore Pty. Ltd. - 10% Mt. Newman Mining Co. Pty. Ltd. manages the project on behalf of the five companies which make up the joint venture.

Jan 1, 1972

By E. A. Barrett, L. L. Rethi

Throughout all segments of the United States mining industry, 163 independent contractor employees were fatally injured between 1990 and 1997. Factors that contributed to these injuries were identified after reviewing descriptive information contained in Mine Safety and Health Administration fatality reports for each of the incidents. Thirty-three unique contributing factors were identified and multiple factors were noted for each fatality. Those most frequently discerned were "failure to follow `standard operating procedures"', (35% of the fatalities), "poor positioning of employee" (26% of the fatalities) and "failure to maintain equipment" (23% of the fatalities). Contributing factors were then associated with the accident and job classifications of the victims. Factors having the highest frequencies in the top five accident classifications where most fatalities occurred were as follows: powered haulage - "failure to maintain equipment"; machinery - "poor positioning of employee"; slip/fall of person - "inadequate fall protection" and "failure to wear safety line"; electrical - "equipment contact with power line"; and falling/rolling/sliding rock - "poor positioning of employee. " Among the job classifications in which most fatalities occurred, leading contributing factors were as follows: truck driver - "failure to follow standard operating procedures" and "poor positioning of employee"; laborer/utility man/pumper - "poor positioning of employee"; mechanic/ repairman and welder - "failure to follow standard operating procedures." Recommendations for utilizing contributing factor information as a basis for safety training are proposed. Training programs may be developed that inform independent contractor employees of factors which, in the past, have contributed to fatal injuries in their job classifications. Then, by combining this information with contributing factors identified in "related" accident classifications, a truly focused training intervention that addresses very specific workplace hazards may he developed.

Jan 1, 2002

By M. Javier

"Mining is the main activity that supports civilization. Actual mining presents contradictory concept to the health of the planet. Its business model is linear, fragmented and characterized by inefficiencies in the utilization of water, energy and mineral resources which generate waste and pollution. Before mining begins, it is critical to determine the vulnerability of the ecosystem and after mining, it is critical to determine the depletion of nature. Attending to these vital matters will require quantifying and measuring them. The purpose of this study is to provide and establish the metric to assess the performance and manage a sustainable future for our existence and that of our planet. This index is defined to measure and control Nature Friendly Sustainability (NFS) based on understanding nature. This index will determine the condition of nature constructed on the measurement of physical, chemical and biological equilibrium. Proposing a new mindset for mining design to satisfy nature’s needs would be to offer the same opportunities to future generations. Hence, sustainability is synonymous with equilibrium under a limited ecosystem. Nature is interconnected. Finally, this index of NFS is readable, standardized and relevant to keep nature’s needs in equilibrium. Establishing and NFS index is the next metric for humanity. INTRODUCTION There are a multitude of definitions of what sustainability is. Most of them are defined in terms of the corporate entity from which they emanate. The classical definition of management states that, “if we do not measure it, we cannot manage it.” Management of ecosystems is the definition of sustainability. Indicators of quantity and quality of sustainability are vital in order to create a metric for sustainability. These indicators will measure the depletion and degradation of nature as they occur through human intervention. The first step is to create a metric of sustainability to simplify its definition. The definition of sustainability is based on whether or not you consider nature to be finite or infinite, which is described in Nature Friendly Sustainability (NFS) [1]. The definition of NFS applies to any anthropogenic activity with an understanding of the equivalent activity in nature. That is to say, human activity with nature requires balance and equilibrium in order to be sustainable. The importance of this equilibrium is quantified in a set of metrics in order to establish measurement and acknowledge indicators for our dependence on nature. Sustainability is synonymous with equilibrium in any ecosystem that is limited and fragile. In the graph is the explanation of sustainability definition. See Graph 1"

Jan 1, 2017

By Kumara Rachamalla

North American mining companies are lagging behind their global competitors in participating in the outstanding opportunities in India. The Indian government has liberalized foreign equity participation in the mining sector by up to 50% and, in some cases, even higher. Delegates from Europe, North America and South Africa learned this at an information seminar held in London, England, Attendees were welcomed by L.M. Singhvi, the UK's high commissioner for India. He introduced a government of India delegation headed by B.P. Baishya, minister of steel and mines. Singhvi is an eminent jurist and leading constitutional expert. He reiterated the soundness of India's legal system. He also outlined the recent Investment Protection Treaty between India and the United Kingdom. Baishya emphasized thee geological diversity and strengths of India's domestic market with its population of more than 920 million people the second largest in the world after China and its reservoir of skilled labor. He also outlined the potential of India's untapped natural resources. The private sector is the backbone of the Indian economy. It accounts for 75% of gross domestic product (GDP). The current minimum program of the new United Front government envisions 12% growth in the industrial sector, 7% in GDP and direct foreign investment of US$10 billion a year. "Mining is an area that can attract a sizable part of this investment," Baishya said. "Projected growth of the Indian economy will require increasingly large quantities of basic raw materials, such as coal and base- and precious-metals to meet the needs of domestic and export markets." Administration of India's mining sector is divided into the Ministry or Mines for regulating and developing the country's mineral resources, five public sector Mining Enterprises, the Geological-Survey of India (GSI), the Indian Bureau of Mines (IBM)and 25 states and seven Union Territories. The GSI is the second oldest (founded in 1851) and the third largest organization of its kind in the world, Baishya said. It has geologically mapped more than 90% of India's 3.2 million kmz (1.2 million sq miles) at a scale of 1:50,000. Several promising mineral projects have emerged from regional exploration programs conducted by GSI and the Mines and Geology State Governments. IBM recently completed a national mineral inventory. It covers 13,000 deposits/prospects of 61 nonferrous minerals. GSI also compiled a similar inventory on 61 coal fields. India is attractive to exploration companies for several reasons. These include favorable geology, accessible locations and a large mineral database. India also has many experienced geoscientists with well-equipped and efficient laboratories, Baishya said. Secretary to the Ministry of Mines A.C. Sen emphasized the largely untapped-geological and mining potential of India. He also discussed the new vistas that have opened up opportunities for exploration and mining. India has large quantities of mineral reserves, Sen said. Its vast Precambrian Shield - like those in Canada and Australia - is endowed with gold, platinum group and base metals, as well as coal and industrial minerals. Annual mineral production is valued at more than US$7 billion. Sen pointed out that India is the largest single consumer of gold. And domestic gold prices command at least a 20% premium above international prices. Recent diamond, gold and base-metal discoveries and prospects uncovered by GSI have generated investment interest from abroad, he added Delegates heard that the Indian Constitution gives the central government the job of framing legislation and the regulation and development of minerals. This ensures that mineral laws are uniform throughout the country. However, the right to grant mineral concessions, such as prospecting licenses and mining leases, rests with the minerals' owner. In India's case, that is the state government. The Indian government has formulated several guidelines that regulate the granting of prospecting licenses for large areas. ? The central government will consider the requests of state governments for the granting of prospecting licenses for areas exceeding 25 kmz (9.6 sq miles). But the license must include a provision to conduct aerial prospecting of the area. ? Any prospecting licensing area should not exceed 5,000 kmz (1,930 sq miles). for a single license. And the total area held by one company should not exceed 10,000 km2 (3,861 sq miles) for the whole country. ? The grant of larger areas will be linked to a mini- mum expenditure commitment on physical targets. State governments will monitor these expenditures. ? The granting of large areas for prospecting will be linked to a schedule of relinquishment.

Jan 1, 1997

By Arun Kumar Singh

Wide variation in the nature of the coal seams and the surrounding rock mass of the Indian coalfields and very little information about the associated stress fields were observed to be the major hurdles in the straight forward application of a continuous miner (CM) based mechanised depillaring approach. Due to various techno-economic reasons, a considerably large number of coal seams have been developed and are standing on pillars in India. The development of pillars is done as per Indian coal mines regulation, which results in pillars of relatively large size. In fact, the large size of the pillars provides stiff natural support to control caving of the massive overlying strata. However, the size of these pillars is not conducive for the single pass pillar stripping technique and, therefore, there is a need for pillar splitting before pillar extraction/retreating. Splitting of the pillar may reduce the competency/stiffness of the pillar, which creates a chance of overriding during final extraction below a massive roof stratum. This paper first discusses the existing coal mining scenario in India followed by a brief presentation of geo-technical details of pillar extraction at the three sites where a CM has been introduced for depillaring/pillar retreating in the country to date. Based on past rock mechanics experiences with conventional depillaring faces, stability issues of the pillars, fenders, and stumps in and around the depillaring face are discussed. This may prove to be an important factor in the success of future CM faces. It is recognized that the application of the modern strata movement monitoring techniques may improve operation safety by providing valuable qualitative and quantitative information that can be used to improve the design of modern concepts like roof bolt based breaker line support during pillaring.

Jan 1, 2009

By H. Zhu, A. G. Journel

Qualitative and interpretive information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging, and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system provides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data. A case study using a large reference database is presented; the indicator conditioned estimates have a smaller conditional bias and a smaller error variance than the ordinary kriging estimates. The results also showed that the indicator conditioned estimator is more efficient for selection in mining.

Jan 1, 1990

By H. Zhu

Qualitative and interpretative information as obtained from geological and/or geophysical studies, in addition to precise measurement, is incorporated into the estimation process through an indicator variable. The indicator conditioned estimator is formulated as a cokriging and its expression is data value dependent as opposed to that of the traditional kriging estimators. The solution of the dual cokriging system pro-vides simultaneously an estimate of the unknown and an estimate of the conditional probability that the unknown belongs to a specific population or class. Being an unbiased and minimum-error-variance estimator by construction, the indicator conditioned estimator is better in the least square sense than the ordinary kriging estimator because it uses additional information carried by the indicator data.

Jan 1, 1989

By V. Carabias-Hütter, A. J. Basu

The paper aims at promoting sustainability assessment and reporting into practice using a globally acceptable set of guidelines and a common framework for internal and external reporting at a project/site level. Indicators are used for measuring performance, and this paper addresses development and implementation of performance indicators for sustainability assessment and reporting at local as well as global levels. The selection of a proper set of indicators is a challenging task. The indicators selected should provide the expected information for making right decisions. Relevant and credible sustainability reporting supported by a consistent performance indicator system can be the starting point for benchmarking environmental and social performance for the natural resources sector.

Jan 1, 2004

By D. J. Shields

The Sustainable Minerals Roundtable was established in 1999 to develop a set of national level indicators to measure the contributions of mineral and energy systems to sustainable development in the USA. The U.S. Forest Service and the U.S. Geological Survey are sponsors of the Sustainable Minerals Roundtable, with meetings convened by the University of Nevada, Reno. Eighteen meetings have been held in various regions of the United States to receive input from different communities of interest. Indicators are being prepared under four criteria: legal and institutional, productive capacity, environmental impact, and socio-economic. This paper reviews the process followed by the Sustainable Minerals Roundtable, and presents the priority indicators.

Jan 1, 2003

By H. F. Ghezzi

The indirect method of drying coal fines is applied to filter cakes which ordinarily contain 22 to 30% moisture and are not readily transportable. The "Thermal Dryer", which operates on the mass transfer principle, has found wide use in coal preparation plants. The thermal dryer is penalized in operation by the necessity of adding coarse coal to the wet fines before entering the dryer body in order to produce a permeable bed, and thus enable hot gases to uniformly contact the wet mass. The ratio of coarse coal to fines varies from 2:1 to as much as 4:1, depending on the average particle size, moisture, and ash content of the fines.

Jan 1, 1985