mine3161
GaRZweiler Open Pit Mine
Rhineland, Germany
Nicholas Duim
20781646

* Executive Summary
The Garzweiler mine is located within the Rhineland basin west of Cologne, Germany. The largest single lignite or brown coal deposit in Europe is found in Rhineland which covers an area of around 2,500 km2. Since lignite is the youngest variety of all coals, forming in the early to middle Miocene age about 15Ma. Several coal seams are formed and join up in the center of the Rhenish basin to form one main seam which reaches a maximum thickness of about 100m. Mining operations are carried out by RWE Power, one of Germanys biggest power producers and extraction of energy materials with an about 30% share in electricity generation is no. 1 in Germany and no. 3 in Europe with a 9% share. Lignite extraction by RWE Power AG totals 100 million tonnes a year with 90% of this output goes into power generation in the RWE Power’s power plants. The rest is upgraded to make briquettes, pulverized lignite, fluidized bed lignite and coke. Garzweiler I mining operations have been continued westward since 2006 on into Garzweiler II measuring 48km² that contains 1.3 billion tonnes of lignite accounting for 40% of the Rhineland brown coal to be mined out by 2044. The mine is a large scale open pit that uses the strip mine to continuously mine out lignite. Mining activities start with the stripping of overburden and this is followed by mining the uppermost flat-laying lignite seams, then interburden to uncover further lignite seams. The overburden is used to backfill already excavated sections of the mine and is discharged by spreaders and forms the basis for the high quality reclamation that follows next. The iconic mining equipment used in operations is the bucket wheel excavators with the daily output of a modern day scale excavator used such as the Bagger 288 model at Garzweiler can remove 220,000 tonnes of coal or overburden per day. Spreaders are able to distribute up to 240,000 m3 of the overburden earth mass a day that is fed through a conveyor belt network totally 66km moving at up to 7.5m/sec and rail operations are also used to move the mined material and distribute the coal product.
Most of the Garzweiler mine will be reclaimed for agricultural use once extraction of lignite ends. Dewatering and flood control systems are used in Garzweiler operations to ensure safe and dry mining. Dust is controlled through the use of spraying masts located all around the mine and engines of mining machines are encased to reduce noise. Reclamation of the land back to farmland or some recreational land is carried out after areas have been mined out. The Garzweiler open pit mine was named after the village that was relocated between 1984 -1989 to a point four km distant on the northern border of Juchen. Since World War II, nearly 35,000 people have resettled within the scope of lignite mining. The concept of a joint resettlement is used to which as many residents of the old village as possible move to a new location has proven worthy over the decades. * Contents
Executive Summary 2 1 Introduction 4 2 Geological Background 5 3 History and Current Status 7 3.1 RWE Power and Lignite 7 3.2 History 8 3.3 Garzweiler Mine 8 3.4 Future: Garzweiler Mine 8 4 Mining Method 9 5 Mining Equipment 10 5.1 Bucket Wheel Excavators 10 5.2 Conveyor Belts 12 5.3 Spreaders 13 5.4 Rail Operations 14 6 6.0 Reclamation 14 7 Safety 15 7.1 Water Management 15 7.2 Dust and Noise Control 16 8 Resettlement 17 9 Conclusion 18 10 References 18

* * * * * * * * * * * List of Tables Table 31 Garweiler I mining operations 8 Table 32 Data, facts Garzweiler II mine 9 Table 51 Bucket wheel excavators 12 Table 52 Conveyor Belts 13 Table 53 Spreaders 13 * * List of Figures Figure 21Location of open pit mines including Garzweiler located NW of Cologne in the Rhineland 5 Figure 22 Idealized geological cross section running SW-NE through the Rur, Erft and Koln tectonic blocks 6 Figure 23 Borehole Geology at a survey area of Garzweiler mine 6 Figure 31 Location of RWE Power's mines and power plants 7 Figure 32 Garzweiler Mine 9 Figure 51 The Bagger 288 Bucket wheel excavator used in mining operations 10 Figure 52 Massive network of conveyor belts used at the Garzweiler mine to transfer the mined material 12 Figure 53 Dumping Side: This is where the spreaders distribute the overburden and prepare the soil for reclmation 13 Figure 61 A before/After shot of a depleted mined out area of the Garzweiler mine after reclamation 15 Figure 71 Spaying masts in the open pit mine 16 Figure 81 Location of Garzweiler II expanding boundaries that will effect local villages 17 * * * * * * *
Introduction
This report is a case study of the Garzweiler mine operated by RWE Power located within the Rhineland, Germany. The mine is a large scale open pit strip mine that operates to mine out lignite that originated in 1987. The report will discuss the geological background, history and current status of the mine. The mining method activities and equipment used in operations are also stated. Reclamation of mined out areas due to the mine and safety techniques are also explained as well as the resettlement of communities. Geological Background
Figure [ 2 ] [ 1 ]Location of open pit mines including Garzweiler located NW of Cologne in the Rhineland
The Cenozoic Dutch-German rift system transects the Rhenish Shield, that comprises the Phenish Massif in the north and the Black Forest in the south to form the 100km long and 50km wide Lower Rhine Embayment in Germany. This basin is subsided along NW-SE oriented faults (Figure 2-1) forming several tectonic blocks including the Rut, Venlo, Erft, Krefeld and Koln blocks. The entire sedimentary section (Figure 2-2) consists of the tertiary and secondary fill of a maximum thickness of 1500m and rests on a pre existing Mesozoic to Paleozoic basement. The tectonic geological events which accompanied the formation of the Rhineland lignite value several considerations. In the Paleocene the area of the Lower Rhine Basin remained largely sediment free. From the Early to Middle Oligocene the area was confined to tightly sinking at differing speeds and depths. The old North Sea transgressed onto the basin with a huge carpet of floating peat provided from the heights of the Rhenish Massif. This received fresh water from the south through a wide river, the old Rhine, caused the peat to sink into the rift trench. During the climax of the marine transgression in the Late Oligocene, the entire rift marine sediments were extensively deposited and covered by these accumulated organic masses that became the rich lignite Figure [ 2 ] [ 2 ] Idealized geological cross section running SW-NE through the Rur, Erft and Koln tectonic blocks seams since the Early Miocene regression of the North Sea.

The extensive drift lignite horizons and the lateral change from lignite to sand represent a change in the depositional environment that resulted from transgressions of the North Sea onto the freshwater swamps. It is believed that the Rhineland coal seams including Garzweiler, Frimmersdorf and Morken seams were formed in this way. The lithology of a borehole taken from the Garzweiler mine (Figure 2-3) shows the different coal seams and the overburden layer thicknesses. They join up in the center of the basin to form one main seam which reaches a maximum thickness of about 100 m (Figure 2-2).
Figure [ 2 ] [ 3 ] Borehole Geology at a survey area of Garzweiler mine

History and Current Status
RWE Power and Lignite
RWE Power is Germanys biggest power producer and a leading business in the extraction of raw energy materials. There business consists of low cost, environmentally sound, safe and reliable generation of electricity and heat as well as fossil fuel extraction. They rely on a diversified primary energy mix of lignite and hard coal, nuclear power, gas and hydropower to produce electricity in the base, intermediate and peak load ranges. With a healthy financial base plus the competent and committed support of about 15,300 employees within RWE Power that enables them to enterprise the opportunities offered by a liberalised energy market. With an about 30% share in electricity generation RWE Power is no. 1 in Germany and no. 3 in Europe with a 9% share.

Figure [ 3 ] [ 1 ] Location of RWE Power's mines and power plants
The lignite energy source has a share of about a 25% in total German power generation. In North Rhine-Westphalia 40% of the power generated is on a lignite basis using lignite from the opencast mines of the Rhenish lignite mining area west of Cologne. Lignite extraction by RWE Power AG totals 100 million tonnes a year. About 90 per cent of this output goes into power generation in the Company’s power plants located near the mines. The rest is upgraded to make briquettes, pulverized lignite, fluidized bed lignite and coke for use in households and industrial furnaces but also for waste water and flue gas cleaning. History The largest single lignite or brown coal deposit in Europe is found in Rhineland which covers an area of around 2,500 km2 to the northwest of Cologne. Since lignite is the youngest variety of all coals, forming in the early to middle Miocene age about 15Ma. The lignite overlain by more recent sand, gravel, and clay and therefore is located closer to the surface is mined in large scale open pit strip mining. The lignite seams also extend to a depth of around 500 m while the overburden thickness can be up to 300 m. Garzweiler is one of several large scale open pit strip mines owned by RWE Power in the Rhineland lignite region in Germany.

Garzweiler Mine The Garzweiler mine originated in the late 1980s. The table below describes some of the characteristics of the Garzweiler I operation that ended 2006. Roughly 1750 employees including 150 apprentices are used to carry out mining operations. Size of mining field | 66km2 | Overburden to coal ratio | 2.9:1 | Overburden removal | 130-150 million m3/a | Lignite output | 35-40 million t/a | Table [ 3 ] [ 1 ] Garweiler I mining operations

Future: Garzweiler Mine
To secure the energy supply Garzweiler I mining operations have been continued westward since 2006 on into mining field Garzweiler II measuring 48km². It contains 1.3 billion tonnes of lignite at a maximum depth of 210m which is to be extracted by 2044 and accounts for approximately 40% of the Rhenish brown coal. The new Garzweiler II mine will replace capacity from Bergheim and Garzweiler I that are both nearly mined out.

Size of mining field | 48km2 | Overburden to coal ratio | 5.0:1 | Coal content remaining | 1370 million tonnes | Lignite output | 35-40 million t/a | Start of production | 2006 | Resettlement | 7600 residents from 13 villages |
Table [ 3 ] [ 2 ] Data, facts Garzweiler II mine

Figure [ 3 ] [ 2 ] Garzweiler Mine

Mining Method
Lignite or brown coal can only be mined in open pit operations with a strip mining method. This is because the overburden layers above the coal seams consist of gravel and sand meaning loose soil. This does not permit the safe underground operations as we know from underground operations in the Ruhr region resulting in many incidents. Strip mining is the practice of mining a seam of the mineral i.e. lignite or brown coal, first by removing a long strip of overlying soil and rock known as the overburden. This method of mining is only practical when the ore body to be mined is relatively near the surface.

RWE Power mining activities generally start with the central removal or stripping of overburden utilising a fleet of giant bucket wheel excavators. On each of the six benches or levels in the open pit mine, a bucket wheel excavator is working to extract the covering layer. This is followed by mining the uppermost flat-laying lignite seams, then interburden to uncover further lignite seams separately. Once mined out, the lignite is transported via long conveyor belt systems or railways to the nearby refineries and, later on to the coal-fired power plants. The overburden meaning sand, gravel and loess is used to backfill already excavated sections of the mine. It is discharged by spreaders and forms the basis for the high quality reclamation that follows next. In an environmental move, RWE Power AG carries out immediate reclamation of both outside waste dumps and mined out areas of the opencast mines as part of its normal operations.

Because of their depth below groundwater table level up to 500 m and due to their horizontal extension of several kilometers wide and long, Rhineland opencast mines including Garzweiler require extensive dewatering and flood control systems. These systems are both aimed at preventing in mine flooding and guarantee dry mining to increase stability of slopes.

Mining Equipment
Bucket Wheel Excavators
The icon of an opencast mine or strip mine is the bucket wheel excavator. These are the biggest mining units used in mining operations. The largest bucket wheel excavator in the Garzweiler mine weighing in at 13,500 tonnes is 96m high and 240m long with the technical name of Bagger 288. These units are used to continuously mine both the soft overburden and the lignite coal ore.
Figure [ 5 ] [ 1 ] The Bagger 288 Bucket wheel excavator used in mining operations
Extraction is by buckets fitted onto a wheel like teeth in a toothed wheel. The material mined then slides onto a conveyor belt via an inclined plane. The bucket wheel is mounted at the end of a 70m long girder boom which also contains the conveyor belt for hauling away the mined material. The bucket wheel boom forms part of the swiveling upper carriage of the excavator and is able to be lowered or raised. This movement is achieved by a hoist winch on the counterweight boom. Ropes transfer the lift forces via two steel lattice pylons. The ballast at the end of the counterweight boom offsets the weight of the bucket wheel boom. Using this technology the excavator can extract material from 50m high slopes (high cut) and as much as 28m below the terrain rim (deep cut).
The weight of the excavator rests of 12 crawler tracks in three groups, each 3.8m wide, 15.3m long and 3m high. The track is electrically driven with the travel gear engines of the biggest excavators having an output of around 2800HP. This power allows the excavators to move a distance of 10m per minute.
The excavator’s upper carriage and chassis are connected via a slewing ring. A bridge links the excavator proper with the loading units, which are mobile. From here the coal or overburden drops onto the conveyor belt which leads from the excavator to the material distribution point.
The mining capacity of the excavators in open pits has increased dramatically over the years. One of the first bucket chain dredger’s from the 1900s in the Rhenish lignite mining area was able to remove about 2000m3 of soil per day. Today the daily output of a modern day scale excavator used such as the Bagger 288 model at Garzweiler is 110 times larger and can remove 220,000 tonnes of coal or overburden per day. These monster mining units are designed by companies such as Krupp, O&K and MAN Takraf.
The excavator operator controls the big mining unit from a cabin located close to the bucket wheel. A group of four to five men are needed per shift to operate the bucket wheel excavator. The group leader monitors driving and digging work from the ground and radios instructions to the operative in the cabin. The loading unit driver sits in a cabin above the transporting conveyor belt and keeps an eye on the proper transfer of the coal or overburden. Other crew members relieve the equipment operatives on a regular basis before their concentration runs out. Number | Capacity | Operating Crew | Total service weight up to | Bucket wheel diameter | Total length | Total height | 1 | 60,000m3/day | 4 men/shift | 3,500t | 11.7m | 153m | 43m | 4 | 110,000m3/day | 4 men/shift | 8,000t | 17.5m | 200m | 64m | 1 | 200,000m3/day | 4 men/shift | 13,000t | 21.6m | 212m | 74m | 1 | 240,000m3/day | 4 men/shift | 13,500t | 21.6m | 240m | 96m |
Table [ 5 ] [ 1 ] Bucket wheel excavators
Conveyor Belts
A conveyor belt consists of two belt pulleys over which runs an endless belt. At least one pulley has an engine with gear that drives the conveyor belt. The drive stations that are steel structures the size of a family home equipped with engines that accelerate the belt up to 7.5m/s or 27km/h. Friction transmits the circumferential force from the pulley drive to that taut rubber belt. The belts are put together from several sections made of rubber up to 200m long and 2.8m wide. 200 steel ropes are worked into the rubber to boost stabilization and transmit the power.
Figure [ 5 ] [ 2 ] Massive network of conveyor belts used at the Garzweiler mine to transfer the mined material

The conveyor belts on the extraction side lead to the material distribution point. There, they cross the belts that lead to the spreaders, the coal bunker or coal handling systems. At the node, each arriving belt can be connected to each departing belt. The staff at operations monitoring the control centre of the opencast mine can flexibly steer the material flows. At the push of a button, overburden and coal are distributed on the belts that move the material on, directing it toward the spreader, power plant, train-loading system or coal bunker. This ensures an uninterrupted supply of coal for consumers.

The material distribution point remains stationary for decades in the Garzweiler open pit mine. But like the excavators and spreaders the conveyor belts and their drive stations must eventually relocate. In this case the moving of belts involves the use of special crawlers with crane booms. Two or more of these pipe laying crawlers lift the conveyor belt at a lateral rail and drag it to its new position. Total length | Approx. 66km | Conveyor belt width | Between 2.0 and 2.8m | Belt speed | Between 6.2 and 7.5m/s | Converted belt speed | Between 22 and 27 km/h |
Table [ 5 ] [ 2 ] Conveyor Belts
Spreaders
Spreaders are the opposite units of the bucket wheel excavators. After removing the overburden on the open pit’s extraction side by the excavator, it is then distributed by the spreaders in the depleted mine areas.
Figure [ 5 ] [ 3 ] Dumping Side: This is where the spreaders distribute the overburden and prepare the soil for reclmation
Moving along several spreader conveyor belts the sand, clay or gravel overburden reaches the discharge boom. This boom can be up to 80m long, height adjustable and able to swivel allowing the spreader to discharge accurately. Each spreader is operated by another crew of five and this unit is able to distribute up to 240,000 m3 of the overburden earth mass a day.

Number | Capacity | Operating Crew | Total service weight up to | Discharge boom length | Total length | Total height | 1 | (Ash spreader) 30,000m3/day | 2 men/shift | 300t | 30m | 56m | 14m | 4 | 110,000-150,000m3/day | 3 men/shift | 2,500t | 100m | 155m | 47m | 2 | 240,000m3/day | 3 men/shift | 5,400t | 100m | 180m | 57m |
Table [ 5 ] [ 3 ] Spreaders
Rail Operations
The Garzweiler and Hambach open pit mines are linked by rail with several RWE Power power plants. The lignite processing factories Fortuna- Nord, Frechen and Ville obtain their raw materials via this railway as well. The railway unit is one of Germany’s biggest private rail operations. The railway unit used is also one of the world's heaviest duty railways and can support high axle loads of up to 35 tonnes.

The main routes are the North-South railway and the Hambach railway also referred to as the lignite field arteries. The 32km long double track of the North-South railway links Frimmersdorf in the north with the industrial estate in the south with an estimated travel time of about 45mins. A 22km long double track fork reaches the Hambach mine in about half an hour. The connecting routes of the upgrading facilities and power plants are about 106 km long. The railway operations fleet includes 30 electric locomotives, 17 diesel engines and about 700 wagons. The total rail network extends 340km. Each year the railway operations are able to transport 60 million tonnes of raw lignite and three million m3 of overburden.

The trains are loaded semi-automatically in the mines and travel through a loading bridge where a conveyor belt is located. Lignite and overburden is filled into the wagons from above through a funnel. The engine driver can’t see the loading and hence the train is remote controlled by the loading operative. The loading procedure roughly takes about 14 minutes. The factory branch lines transport an one million tonnes of products annually in wagons of the same type used by Deutsche Bahn, German railways. RWE Power puts the wagons together to form trains and hands them over to external railway companies like Deutsche Bahn for further transportation to customers.

6.0 Reclamation
The reclaiming of the depleted Garzweiler open pit mine sections is a top priority. This is a field where RWE Power has had decades of experience and in order to continuously improve its recultivation methods it collaborates with research institutes, universities and independent experts in environmental protection, forestry and agriculture. Most of the Garzweiler mine will be reclaimed for agricultural use once extraction of lignite ends. The eastern and northern sections of low fertility forest plain that has always been used intensively for agricultural purposes will to be returned to the regions local farmers as commercial land. The most valuable asset in reclaiming these surfaces is supplied by nature itself as the extremely fertile loess soil is available in high quality and quantity.

Figure [ 6 ] [ 1 ] A before/After shot of a depleted mined out area of the Garzweiler mine after reclamation
In this open pit mine section no agricultural steppe will emerge. Two extensive valley troughs will add variety to the farmland. Dry meadow biotopes will dominate but other areas will be created that will be left completely too natural evolution. This will ensure that the production and retention of refuge zones for flora and fauna remain.

Leisure value for people seeking recreation will also get something from the recultivation process. A significant portion of the overburden from the Garzweiler II field will be used to backfill Garzweiler I but leaving a trough in the southwestern section. There a lake will emerge years later from the inflow of groundwater and precipitation as well as water from the Rhine. In all of these measures it is not feasible for people to recreate the original landscape just the way it used to be. But experience has shown that if start-up aid is given that is ecologically convenient and has scientific backing, the self-healing powers of nature are great that the landscape used in mining operations can fit back into the cultivated environment within a foreseeable future.

Safety
Water Management Before the lignite can be mined the groundwater level must be lowered in the mine otherwise its slopes would collapse under the pressure of water and reduce stability. This lowering of the groundwater table level is achieved through dewatering measures by means of gravel packed wells that are sunk several years ahead of mining. In 1986 about 600 wells operating in the Garzweiler mine discharged 80x106 m3 to enable a lignite extraction of 30Mt. The average drawdown of the wells in the mining area was about 150m. Much of this well water is used in dust control of the Mine. To prevent a spread of the cone of depression into protected wetlands occurring due to the dewatering process a recharge by infiltration method will be used to assure the survival of the wetlands. Flood control systems and protocols are issued and combined with the dewatering process this ensures the Garzweiler mine dry mining.

Dust and Noise Control
Several measures reduce the dust and noise from open pit mining, minimizing the nuisance and disturbance for people living in the vicinity of the Garzweiler operation. Exposed overburden and lignite surfaces are kept moist by mobile automatic sprinklers or strengthened by sowing grass or grain. Jets on the bucket wheel of the excavator and at the conveyor belt transfer points continuously spray water to prevent the dust accumulating in the extraction and transport of lignite. On the edge rim of the opencast mine roughly 300 spraying masts create a fine screen of water to control the dust (Figure 7.2-1). Further stationary rotary sprinklers perform this task inside the opencast mine.

To combat noise, the drives of excavators, spreaders and conveyor belts are encased for noise protection. The conveyor belts are fitted with low noise idlers to reduce sound. Also, earth walls on the mine rim shield local townships mildly from mining operation noise.

Figure [ 7 ] [ 1 ] Spaying masts in the open pit mine

Resettlement
The Garzweiler open pit mine was named after the village that was relocated between 1984 and 1989 to a point four km distant on the northern border of Jüchen due to the mine operation. Roughly 1,250 citizens lived at the old site and most of them made the move to the new location. The villages of Königshoven, Elfgen, Belmen, Stolzenberg and Priesterath in the Garzweiler mining field were relocated in the same way.

Figure [ 8 ] [ 1 ] Location of Garzweiler II expanding boundaries that will effect local villages
The 2,500 residents of Otzenrath, Spenrath and Holz (municipality of Juchen) were also affected by resettlement during recent years. The majority of the 260 residents of Pesch (municipality of Erkelenz) have moved to the jointly selected new township of Kuckhoven which many of the approximately 1,300 citizens of Immerath and Lutzerath (municipality of Erkelenz) have chosen for as well. In addition, resettlement of the 650 residents of Borschemich to their new site at Erkelenz-Nord is now under way. Since World War II, nearly 35,000 people have resettled within the scope of lignite mining. This makes resettlement undeniably the most serious intervention by this industrial sector in the intensely used and densely populated, cultivated landscape of the Lower Rhenish Basin.

What matters in the resettlement is not only fair compensation for material possessions like homes, land and businesses though this does enable those affected to make a fresh start without any financial disadvantages at their new place of residence. In resettlement we have to take into account immaterial values like tradition, community spirit and a sense of belonging that cannot be measured in money terms.

In any resettlement it is important to identify and foster structures and the process of change in this mesh of relationships, so that the village community can establish itself and thrive at the new location. From this all those involved pursue the concept of a joint resettlement according to which as many residents of the old village as possible move to a new location for example, from Alt-Garzweiler to Neu-Garzweiler that is selected and planned jointly with the community. The concept has proven its worth for decades now.

Conclusion
The Garzweiler mine is located within the Rhineland basin west of Cologne, Germany. Mining operations are carried out by RWE Power, one of Germanys biggest power producers and extraction of energy materials. The mine is a large scale open pit that uses the strip mining method to mine out lignite. Garzweiler I mining operations have been continued westward since 2006 on into Garzweiler II measuring 48km² that contains 1.3 billion tonnes of lignite to be mined out by 2044. The iconic and main equipment used in operations include bucket wheel excavators, spreaders, conveyor belts and rail operations. Dewatering and flood control systems are used in Garzweiler operations to ensure safe and dry mining. Dust is controlled through the use of spraying masts located all around the mine and engines of mining machines are encased to reduce noise. Reclamation of the land back to farmland or some recreational land is carried out after areas have been mined out. Since World War II, nearly 35,000 people have resettled within the scope of lignite mining.

References
Farag, K. S. I. and Tezkan, B., 2004. Mutli-dimensional radiomagnetotelluric and transient electromagnetic interpretation for the shallow coal seams at the Garzweiler mine, west of Cologne. In: Protokoll über die 64. Jahrestagung der Deutschen Geophysikalischen Gesellschaft, Berlin, DGG, EM09.

NA. 2007. Rhineland Lignite Mining, Germany. [ONLINE] Available at: http://www.mining-technology.com/projects/rhineland/. [Accessed 13 April 12].

Kennedy, B.A, 1990. Surface Mining . 2nd ed. Baltimore, USA: Port City Press.

NA. 2010. Lignite - The Energy to Lead. [ONLINE] Available at: http://www.rwe.com/web/cms/mediablob/en/495526/data/235578/2/rwe-power-ag/media-center/lignite/blob.pdf. [Accessed 13 April 12].
Singhal, R K, 1995. Mine planning and equipment selection 1995 . 1st ed. Rotterdam, The Netherlands: Balkema.

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