World of Mining - Surface and Underground

United Schleenhain mine is the largest site in the Miffeldeutsches Braunkohlenrevier, or Central German Lignite Field. It is made up of the three mines Schleenhain, Peres and Groitzscher Dreieck. The first Lignite Mining Plan came into force in 1999; following conflict surrounding the resettlement of Heuersdoil village, the plan was declared invalid by the Saxon Higher Administrative Court in 2003. The mine's close proximity to no less than 14 NATURA 2000 sites represented an additional challenge. Through cooperation between regional planners, MIBRAG mbH as the mine operator and specially commissioned technical consultants, evidence needed to be provided of the compatibility of the planned further operations with issues concerning nature, the landscape and wildlife conservation. A dual assessment of environmental aspects was required as part of the Lignite Mining Plan process. During the EIA the existing framework operational plan from 1994 needed to be assessed, and so did the newly drafted Lignite Mining Plan against the backdrop of the SEA Directive.
The mining project, Garzweiler II, containing 1.3 billion tonne of lignite in an area of 4800 ha, which is in the preparation stage since 1984, is expected to be implemented after 2006. The preparations for site development included the relocation of the material-distribution point, widening of A 61 with demolition of A 44 autobahn, preparation and implementation of resettlement scheme and water management. With a share of 44% in primary energy production in the Federal Republic of Germany, lignite is the most important energy resource which is economically mineable without subsidies and available in sufficient quantities. Lignite extraction in the Garzweiler II mining field is expected to make a crucial contribution toward covering long-term demand.
The annual status report at the Lignite Conference was presented under the heading "Stability through diversity". Germany will be phasing out nuclear energy by 2022 and giving a big push to renewables as a substitute. This makes lignite more valuable as a domestic energy. Lignite-fired power plants are always available but must be operated ever more flexible. Reference in this respect is usually made to gas-fired power stations. That is a misjudgement, since the modern plants in the Rhineland, Central Germany and Lusatia and CCGT plants show hardly any differences when it comes to the control range and the speed of load change. The older power units of the 600-MWand 500-MW class in the Rhineland and Lusatia have been retrofitted to ensure greater flexibility. The BoAplus project in the Rhineland will bring further innovations. In the time horizon 2030, lignite's importance must be assessed in a global and European context. Lignite can go on playing an important role in a diversified electricity mix, with CO2emissions being limited by Europe's cap-andtrade system (ETS). For Germany, lignite remains an important energy-policy option and a significant economic factor, even if a much lower CO2 cap is assumed. Further increases in efficiency are possible. In Central Germany and Lusatia, decisions on follow-up fields must be taken in good time. The lignite industry is seeking close review and coordination with European and German policymakers. Of particular importance is the collaboration in those federal states where Lignite is mined. The Lignite Conference traditionally is an occasion to express thanks for wide-ranging support. This year, special thanks went to Prime Minister Platzeck, who gave the ceremonial address.
The weighing performed at the end of the overhaul demonstrated that the required reduction of the boom's weight had been achieved with the retrofit measures. Based on the new self-weight condition, stability against overturning as well as structural stability and fatigue strength were confirmed for all load case combinations and without any operational restrictions. In combination with other mechanical and electrical measures, excavator 259 is now fit for future demanding operating conditions in the Hambach opencast mine.
In order to study the existence law of the shortest path of strength reduction in the limit analysis of shallow tunnels, ABAQUS software is used to establish a numerical model. The double strength reduction method is used to demonstrate the rationality of the shortest path of strength reduction in the limit analysis of shallow tunnels. From the perspective of saving computing resources, the influence of grid density on the shortest path and the safety factor of tunnel strength reduction is studied. The results show that with the increase of reduction ratio, the tunnel strength reduction path first decreases and then increases, which approximately obeys the parabolic distribution law, and the applicability of the strength reduction shortest path method in the finite element analysis of shallow tunnel is verified. Moreover, the reserve strength of co-hesion is higher than the internal friction angle when the tunnel is unstable. In the actual surrounding rock reinforcement design, priority should be given to the strengthening effect of the internal friction angle. Reducing the grid density has little influence on the shortest path and the overall safety factor of the final strength reduction of the tunnel, so further optimization of the grid can be considered in practical application to save computing resources. The research can provide reference for related projects and follow-up research. © 2021 GDMB Gesellschaft fur Bergbau, Metallurgie, Rohstoff- und Umwelttechnik e.V.. All rights reserved.
RWE Power AG is a joint project of the conveyor belt group of ContiTech AG for the development of energy-optimized conveyor belts. Opencast mine equipment with the highest capacity worldwide is employed for continuous material handling in the Rhenish lignite mining area. The belt conveyors are operated with a belt width of 2.8 m and at a velocity of up to 400,000 m 3 and to be able to achieve these handling capacities and withstand the high stresses imposed on them during operation, the tensile strength of the belts had to be increased. RWE Power AG is striving continuously with advanced existence technology with an aim to reduce the belt conveyors' resistance to motion cause by friction, thus reducing the auxiliary energy requirements of the belts. The energy requirements of the new rubber compound are estimate in collaboration with the University of Hanover by conducting various hysteresis measurements on shear specimens of the new compound.
Beginning in 2010 LE-B has implemented a project group for the coordination and execution of all activities for providing geotechnical safe post-mining landscapes (project group "safe BFL"). Due to the increasing size of the backward dump areas in each of the opencast mines and the planned phasing out of the Cottbus-Nord opencast mine at the end of the year 2015 the company faces the challenge to guarantee geotechnical safety for the post-mining conditions especially the future dump-side residual lake slopes and of dumps sites in the backward area. Therefore, high-quality and cost-optimised stabilisation of embankments of future relic lakes and/or the establishment of a stable subsoil for diverse buildings planned at LE-B (buildings and technical plants, roads, rivers, disposal sites, etc.) will gain more and more importance. After the successful establishment of the project organisation, different objectives were followed. For instance, a data store was implemented for the data collection and analysis of all compaction data exactly to the date. Various deep and surface compaction methods were tested to their application in the post- mining landscapes to be secured. Therefore, a modular system is available fa various applications. Moreover, special technologies like the back-step method, the Mass feeding funnel and the Hydro-dynamic surface securing (HOFS) were developed to be able to secure a high-quality compaction of the dump areas in the next decades. The successful application of the prototype of a so-called measuring vibrator is a milestone for the on-line compaction control at LE-B. The coming tasks will include the further development of the measuring vibrator up to series production and the automation of the adjustment of the compaction technology to the subsoil conditions. © 2018 GDMB Gesellschaft fur Bergbau Metallurgie Rohstoff- und Umwelttechnik e.V. All rights reserved.
Rheinische Aktiengesellschaft für Braunkohlenbergbau und Brikettfabrikation was set up in the year 1908, and this event heralded an unprecedented streamlining of the lignite industry as it grew and developed in the Rhenish mining area. It paved the way for a bundling of forces that had become necessary in the sector's recent history if it was going to successfully face the upcoming challenges on the commodity and energy markets and in the mining sector. The amalgamation of the many Rhenish mining companies also enabled the industry to safeguard its interests more forcefully and effectively in its dealings with other market players and policy-makers. In the light of today's discussions about raw-material shortages, sustainable energy supply, climate protection and emissions trading, lignite is again facing huge challenges, just as it once did. Even if these are new and of a different nature, the course taken 100 years ago may provide pointers for the future alignment of the Rhenish lignite-mining industry. In view of the ongoing efforts made to gain acceptance among citizens, policy-makers and business, backed by an internal promotion of knowledge transfer and further education, the systematic use of technical progress to improve the competitive situation, and a far-sighted gearing of the product portfolio to growth markets, Rhenish lignite is creating a sound basis that will enable it to successfully meet tomorrow's challenges in a time-tested manner.
In this article key aspects of the system-and material-related stability of residual-lake slopes subjected to seismic Impact are described. Requirements are explained and recommendations given for the performance of dynamic numerical FEM calculations. Methods for the calibration of the employed material models are outlined and a concept Is proposed of how to prove the employed materials' stability to liquefaction.
The increasing global demand for primary raw materials requires further mechanization of mining processes. The focus of research has been on developing new methods which activate current processes without reinventing the wheel completely. The effect is generated through a high pulse shaped impact or other measures that cause fatigue of the rock mass. Kotwica and researchers have developed a prototype of road header with a pivoted disc bit and a hydraulic impact feature in 2004. The Narrow Reef Miner from Sandvik Mining and Construction is hydraulically interlocked between roof an underlying stratum during cutting. Since the cutter head can be pivoted horizontally the rock material is excavated in a crescent shaped profile. Research conducted by Bucyrus Europe has resulted in the development of a newly designed cutting head equipped with point attack type picks for mining operations.
To match the high demand for natural stone grains in the current boom in mainstream construction, some operators who normally drill and blast on their own are buying additional drill meters through service providers. In the light of this development, the latter are also increasing their capacities. That is just what German drilling and blasting company Klaus Berge did when it invested in a new Sandvik drill rig, Ranger ™ DX900i, thus also becoming the first in the country to operate the completely new type of drill rig. © 2019 GDMB Gesellschaft fur Bergbau, Metallurgie, Rohstoff- und Umwelttechnik e.V.. All rights reserved.
Since the development of the opencast mine in 1978, machinery and equipment has been continuously advanced, with the underlying legal conditions and changes on the electricity market being major determinants. Over the entire 40 years, groundbreaking developments in materials-handling and mining engineering took place and have meanwhile attracted broad interest in the industry throughout the world. For several years now, PC-aided applications have been increasingly factored into the development and speeding it up. In collaboration with a wide spectrum of experts with experience in mining engineering, the equipment used in the Hambach opencast mine is continuously being advanced and is very well prepared for the future. Looking ahead, one can say that, if the optimization of equipment used in the mine is systematically continued with the aid of future-geared technology, the goal of dynamic opencast mine management with enhanced technical and cost-related transparency will be attained.
Hans Merensky is the all-time most successful discoverer of ore and diamond deposits who ever lived. Without his contribution, both South Africa and Namibia would be a good deal poorer today. Born in Transvaal in 1871 as son of German parents, he studied geology and mining engineering in Germany. As from 1904, he worked as consulting engineer in South Africa. In 1924, he discovered in the Bushveld the largest platinum deposit in the world, later called the "Merensky Reef". In 1927, he discovered at the mouth of the Oranje River the richest deposit of diamonds in gemstone quality ever identified. Selling it to the De Beers Group, he made himself a multimillionaire. As from 1930, Merensky lived at his farm Westfalia, where he became a pioneer in fighting land destruction and soil erosion in South Africa. He now prospected occasionally only, but very successfully. In 1936, his prospection in the Oranje Free State resulted in fresh impulses for the declining gold mining in the Witwatersrand. But a short time later, he identified in the Bushveld the largest chromite deposit in the world, while in 1937 the largest vermiculite deposit in the world was detected by him, and in 1949 an apatite deposit sufficient to cover the fertilizer needs of South Africa for a hundred years. Merensky died in 1952. His considerable fortune was left to a foundation engaged in promoting science and preserving South Africa's natural resources. It also serves to maintain the Merensky Archive. It contains all the scientific publications and prospection records from the different periods of activity of Merensky, as well as folio volumes with newspaper clippings, correspondence, and highly interesting essays on the problem of coal liquefaction. They prove that Merensky was a forerunner for the splendid development initiated by SASOL.
The use of GPS/GNSS positional data on lignite mining equipment in operations management systems and for automation necessitates the fulfilment of high requirements in regard to precision, availability and safety of the signals. The development project was able to implement the functionality of the GPS/GNSS-based positioning system and the position support system in the event of GPS/GNSS failure while meeting the above requirements. If satellite reception is available, the substructure centre can, under the influence of the fluctuating measured values, be determined with accuracy "to the size of a football". In addition, support tests showed that the positions are assisted over long distances and that the bucket-wheel excavator can continue to be operated for up to one hour in the event of a GPS failure. In addition, standards that permit easier implementation, including on spreaders, were developed in preparation for a roll-out to other mining equipment of RWE Power in the Rhenish mining area. The use of GPS PLC as core component turned out to be indispensable for the tasks and requirements to be fulfilled for automation. The implemented positioning system also allows other operations management systems to be used in an optimal manner and processes to be improved [8].
Due to characteristics such as no shock-wave and blasting vibration, soundless demolition technique has unique advantages and remarkable effects in fracturing and improving permeability of coal seams with a low permeability. The experiment reveals that fracturing effects of chemical demolition agents are affected by shapes of borehole, environment temperature, pH of water and particle size of calcium-based materials. With increasing environment temperature, cracking time for briquette coals was gradually shortened. At 50 °C, cracking time for briquette coals was only 40 min, indicating that fracturing effects of chemical demolition agents were improved with the increase of environment temperature. The chemical demolition agents had faster reaction rates with alkaline than with acid solutions and therefore showed more significant fracturing effects in certain time. When pH = 8, cracks in the largest width (25 mm) were produced. When the particle size of quick lime was in the range of 6 to 18 mesh, the best effects were obtained. Too large or small particle sizes are not conducive to playing a favorable fracturing effect. In addition, by combining with theoretical analysis and experiment, non-circular holes are found to be beneficial for improving chemical demolition effects.
The share of renewable energies in electricity production will not only in Germany continue to increase in the future, and the acceptance of "carbon-intensive" power generation is currently falling. But it is impossible to predict today whether imports from reliable imports, smart technologies and storage will make it possible to cover the residual load economically in the long term. In this respect, flexible conventional power plants and not least the lignite power plants are indispensable if not enough renewable energies or other solutions to cover the load are available. In the meantime, the technology used for the power generation from lignite has reached a very high level of development. Nevertheless, the share of power generation from lignite will be smaller with increasing share of renewable energies. However, the decline in the utilisation of lignite power plants opens up the opportunity to market the lignite more in a "refined form", as well as to use it increasingly as chemical raw material in addition to electricity production. This so-called raw material use is applied, for example, in energy storage and in the chemical industry when it comes to substitute natural gas or petroleum products. The hydrogen required for raw material use can be provided in the future from surplus electricity from renewable sources with the advantages: reducing the carbon footprint of the products and the possibility of use of manufactured products as "storage". Among other things it is also positive that lignite is a domestic energy carrier, which does not have to travel long delivery routes to the customer and is not subject to "global political calculus". And anyone who thinks that the mining of lignite in large opencast mines destroys cultural areas and landscape, will be taught a better one at the latest when visiting the renaturation areas. Mining, renaturation, energetic and raw material use of lignite are of course not self executing activities. They provide for many jobs directly linked to these tasks, which once again create jobs for services. In this respect, lignite is not only guaranty for the sustainable and secure supply of energy in Germany, but also for employment. This, combined with long-term permits to mine domestic lignite, provides a sense of security that will continue until the middle of the century. Security for energy supply at a time when neither wind nor solar energy is available, just as security for jobs and the politics that can rely on the availability of sufficient energy reserves for the German economy that have co-founded and will continue to support the status of the "Export World Champion". © 2018 World of Mining - Surface and Underground. All rights reserved.
The Western Austrian company, Gebrüder Scheiber Ltd. in Längenfeld Ötztal, in the state of Tyrol, operates the mining, dressing and treatment of industrial rocks for the construction industry. The area of the project is located in the mid-Eastern Alps, where the rocks are polymetamorphic crystalline. High Alpine location of the new open pit is at an altitude of approximately 1210 to 1300 m above sea level. The E-W length is 400m, in the direction N-S 250m above sea level. The licensing procedure for the authorization of the operation of a mining plan is implemented according to Mineral Law, Forest Laws, Tyrolean Nature Preservation Law, Water Regulations. The equipment used for the surface mining is composed of a drill rig Tamrock Commando 300, hydraulic excavator CAT 320B and a dumper CAT725.
Spontaneous combustion of coal is one of the main disasters affecting safe production in mines. A sodium carboxymethyf cellulose/aluminium citrate (CMC/A)Cit) gel for prevention and extinguishing of mine fires was prepared. Based on a tempera- ture-controBed experiment, the authors studied the influences of the gel on indicator gases generated in the spontaneous combustion of coal, crossing point temperature, and activation energy. The results showed that the crossing point temperature of coal samples treated by the gel increased by more than 13.9 °C, and the activation energy rose by 7.17 to 16.34 %. Moreover, the indicator gases, such as CO and C2H4 generated in the oxidation, decreased significantly. After treatment with the gel, the weight toss rale of the coal samples was reduced and less energy was released. By utilising the self-developed test platform (coal capacity of 2 m3), the spontaneous combustion of coal on the roof of a roadway was simulated and the CMC/AICit gel was used for fire extinguishing. After injecting the gel, the temperature in the furnace rapidly decreased and the concentration of 02 remained at less than 3 %, without showing any after-combustion effects. © World of Mining - Surface and Underground. All rights reserved.
The oxidation of pyrite at the Ibbenbüren mine, operated by the RAG Anthrazit Ibbenbüren GmbH corporation, which is a part of the RAG Group, was investigated to better understand and trace the decomposition of iron sulfide. A particular focus was directed at the bacterial influence on the weathering process and iron bacteria were cultivated with the help of the iron deposits from the western field. The results show that the oxidation of iron provides little energy for the iron microbes which are in a poor energetic position as a result of their autotrophic lifestyle. It is not possible to predict that the amount of iron(III) bacteria can actually produce. In order to ultimately be able to separate the iron load in mine water into a partial content of abiotic origin and a partial content of biological origin, it is necessary to first quantify precisely the presence of bacteria in the mine water and to ascertain the kinetic growth of the microorganisms.
In the areas affected by dewatering measures required for lignite opencast mining, houses without structural waterproofing were built in times of low groundwater tables. When the groundwater rises, these houses are at risk of problems with waterlogging. It falls within the responsibilities of the parties involved in construction, in particular property developers and engineers, to assess the subsoil in terms of the groundwater issue and if necessary provide for waterproofing measures prior to building. This requires that the highest groundwater tables to be expected be taken into account. To prevent future damage to new-builds, property developers, engineers and architects need to be provided with appropriate advice. Problems with waterlogging can be solved with structural or water-management measures. The associated costs render implementation difficult or prevent it altogether. This is especially true of extensive water-management solutions where costly re-infiltration measures are required for supply reasons in order to protect public drinking-water production. For times of particularly high groundwater tables, capping scenarios going beyond the previous reflections about the available supply and which no longer require costly re-infiltration measures were developed. They are cost-efficient supporting measures that could be implemented with the financial participation of those affected. Comprehensive communication with those affected and the involvement of citizens' action groups in reflection and decision-making processes permitted the discussion to be placed on a more objective footing. The solutions found so far are not comprehensive. This issue will thus continue to keep us busy. Empirical values gained so far, in particular as regards in-depth communication with the affected citizens, will be helpful.
Approval practice requires geotechnical aspects to be considered in addition to many other factors in the creation of residual lakes. The proof of stability is furnished in the course of various Special Operating Plan procedures, and the due date for the submission of these plans is determined by the provisions of the Master and Main Operating Plans. The Geological Survey of North Rhine-Westphalia (GD NRW) is involved in the approval process as the technical inspection body.
Since 1976 stability tests performed on rim slopes and permanent slopes in North Rhine-Westphalian opencast lignite mines have been governed by the provisions laid down in the Guideline for Stability Examinations (RfS) of the Arnsberg regional government. This Guideline obliges the parties involved in the verification and inspection process to apply the so-called six-eyes principle, ensuring that the slopes meet high safety standards. In the meantime the "Geomechanics in Rhenish lignite mining operations" working group was set up. Under the direction of the Arnsberg regional government and with input from Geological Service of NRW and the mining company this group of experts is responsible for the structured further development and discussion of the Guideline and also processes geomechanical issues in general. In the case of specific problems additional experts of specialist authorities or universities are consulted, making sure that upcoming questions are dealt with on the basis of sound technical information and scientific facts. This strategy was also adopted in the run-up to the latest amendment to the Stability Examinations Guideline in 2013. Prior to its incorporation into the Guideline, the present earthquake approach developed by experts was revised and modified again by specialists and scientists. The result of these efforts is an addendum to the Guideline that is based on scientific facts and which contains specific provisions for the consideration of impact from earthquakes in stability examinations of permanent slopes. For the residual-lake slope systems the provisions on the level of seismic action to be assumed (return period) go beyond the usual requirements of DIN 1054 (Subsoil - Verification of the Safety of Earthworks and Foundations) applicable in civil engineering as well as Eurocode 8 - Earthquakes and are let by the high requirements of DIN 19700 - Dam Plants. Although a residual lake does not meet the criteria of a reservoir on account of the marginal conditions on site (direct connection to the groundwater in its final state, situated lower than the surrounding terrain), the addendum will ensure that future residual lakes satisfy the same high safety standards that are used in NRW for the dimensioning of dam structures (dams) situated higher than the surrounding terrain. The "Geomechanics in the Rhenish Lignite-mining Area" working group will continue to ensure structured and comprehensive processing of all issues of relevance in geomechanics for opencast lignite mines in NRW.
The article reviews the current and future development of demand and trade for the main solid bulk commodities in Asia-Pacific, including India. This area is the most populous, the largest economic and the fastest growing in the world. China, India and Indonesia alone account for almost three-quarters of the 7,3 billion people living there, including a growing and demanding middle-class population. The region's industrialization and urbanization have sparked a huge need for raw materials. Investments in houses and infrastructure had triggered an immense growth in steel demand over the recent years. The steel demand in the region, especially in China and India will determine the future trade for iron ore and coking coal. Coal is the dominant energy source for power generation in the region, while nuclear energy, LNG and increasingly renewable energies are competing for future shares. After more than a decade of unprecedented boom, the minerals market has returned back to "normal". Since the height in mid-201 1, the commodity trade suffered dramatically from falling prices, which applies to the energy sector with crude oil, LNG and thermal coal and to the industry sector with iron ore, metallurgical coal and metals. The Chinese economy has started a fundamental change. It is in transition from an investment- to a consuming-driven structure, which has led to reduced demand for commodities. As a consequence of the sheer scale China used to have in the consumption; the markets have turned into oversupply. During the so called commodities "super cycle" over the past decade, when soaring demand drove prices for minerals to records, miners had spent billions of dollars in investments, with many of them now found as being uneconomic. Australia and Indonesia are the world's largest exporter of coal, predominately supplying the Asian market. While Indonesia mainly produces low-cost and low-quality thermal coal, Australia delivers premium thermal coal. It is also the world's largest exporter of metallurgical coal. As the world's largest exporter of iron ore, Australia is blessed with the proximity to its main customers in Asia. It supplies most of the iron ore demand in the region, but Brazil is going to emerge as a future strong competitor. The uncertainties of the future market volumes and prices have caused huge problems for the suppliers of coal and iron ore. Many companies will not survive and the production will concentrate on the big global players.
Location map of the Radium Hill mine site 
Radiometrics (uranium channel) of the Radium Hill site showing the distinct U enrichment of the town and mine-processing sites and the main road connecting both areas 
Crushed waste rock dump (RHCR10: 427 ppm U; 0.48 µSv/h), with eroded waste materials in the surrounding topsoils and surface sediments 
The Radium Hill uranium deposit, in semi-arid eastern South Australia, was discovered in 1906 and mined for radium between 1906 and 1931 and for uranium between 1954 and 1961 (production of 969,300 t of davidite ore averaging 0.12 % U 3O 8). Rehabilitation was limited to removal of mine facilities, sealing of underground workings and capping of selected waste repositories. In 2002, gamma-ray data, plus tailings, uncrushed and crushed waste rock, stream sediment, topsoil and vegetation samples were collected to assist in the examination of the current environmental status of the mine site. The preliminary data indicate that capping of tail ings storage facilities did not ensure the long-term containment of the low-level radioactive wastes due to the erosion of sides of the impoundments. Moreover, active wind erosion of waste fines from various, physically unstable waste repositories causes increasing radiochemical (up to 0.94 μSv/h) and geochemical (Ce, La, Sc, Th, U, V, Y) impacts on local soils and sediments. However, measured radiation levels of soils and sediments are at or below Australian Radiation Protection Standards (20 mSv/a averaged over five consecutive years). Additional capping and landform design of the crushed waste and tailings repositories are required in order to minimise erosion and impacts on surrounding soils and sediments.
Federal Minister for Economics and Labor of Austrian parliament compiled mineral resources maps in 2001, documenting the deposits of needed minerals, establishing an Austrian Minerals Resources Plan permitting future exploitation. Plan had two phases that are, compilation and adjustment of manifold single information concerning mineral occurrences of metallic ores, industrial minerals, construction materials, crushed stoned, clay, and energy fuels excepting hydrocarbons in Austria. Phase 2 was collaboration with experts from provincial governments with regional experiences, protecting in land use planning and information of existing land use, settlement areas, natura 2000 areas, forest and groundwater planning. Mineral occurrence and identification of areas of suitable minerals resources were evaluated by system-analytical methods.
The characterization of the soft lignite mined in Germany by an extraordinary high binding potential due to its special structure, is discussed. The lignite contains about 4 to 14% of bitumina in form of modified plant resins and waxes which also have good binding and hydrophobing properties. The Lusatian lignite contains 5 to 15 % cellulose-rich fibrous xylite being well suitable for the formation of solid positive compounds. During the pelletizing process, the raw coal is first activated referring to the binding in an intensive mixer with the addition a small amount of water. The strength of the wet raw pellets is still low but sufficient enough for the mechanical stresses during transportation and rotation motion in the drier. The combustion tests for the lignite pellets were carried out with the help of an automatic boiler that was developed for wood pellets in which the pellets are pushed into the combustion chamber by means of a proportioning screw.
Top-cited authors
Christian Blick
  • University of Applied Sciences Kempten
Gregor Borg
  • Martin Luther University Halle-Wittenberg
Bernd Lehmann
  • Technische Universität Clausthal
Felix Scharfe
  • PMS Handelskontor GmbH
Farhad Mohammad Torab
  • Yazd University