Planned mining tests and research in Estonian oil shale deposit

4 Current situation. 2

5 Previous situation. 3

6 Testing criteria. 6

7 European measure. 6

Figure 1 Current underground room and pillar mining. 3

Figure 2 Cutting with longwall shearers. 4

Figure 3 Testing Twin Boom Axial Road Header (Continuous miner) in Estonian Oil Shale deposit in 1970ties. 5

Figure 4 Testing Wirtgen surface miner SM2500 for high selective mining in an open cast mine. 5

Figure 5 One billion tonnes of oil shale has been mined in Estonia from the beginning in 1916 until 2006. 6

Development of oil shale underground continuous mining technology

1 The project aim

Strategic aim of the project is development of Coal mining technology by testing continuous mining system in difficult conditions in Estonian Oil Shale deposit improves coal mining possibilities due to enhancing cutting, supporting and face transport form high productive short-wall face. Currently many coal fields in Europe face difficult mining conditions. The main problems in addition to deep bedding are unstable roof, dilution of side rock and content of abrasive and hard parts of side rock inside or between coal seams.

Aim of the research is to introduce oil shale underground continuous mining technology on example of Estonian oil shale deposit in areas with arduous conditions. The results of insitu testing can be used to improve existing situation in EU coal/oil-shale mining fields with complicated geological conditions and in densely populated regions.

Currently Estonia is independent energy producer thanks to existing of Oil Shale deposit and favourable mining and processing conditions. Due to environmental restrictions, social pressure and deeper bedding of oil shale in potential mining fields, testing of high-productive, environmentally friendly, mechanical mining is needed for successful continuation of independent energy supply (oil shale) for EU state country, Estonia. Situation in energy market of EU will be change in the nearest future. Decreasing need for energy import to Estonia will be very helpful for European energy market. New flexible and powerful mining technology will guarantee securing independence of Estonian energy sector.

Development of mining machinery and mining technology by the way of selective mining will improve environmental situation in Europe and Baltic Sea region. Effect can be achieved in decreasing CO₂ pollution, ash pollution and water pollution. To avoid a potential problem of non-utilizable waste in stockpiles of mine areas selective mining provides leaving non-conditional rock mass in mined-out underground areas.

It is intended to develop research program to develop design of cutting tools/drums with a minimum cutting tools consumption and machine down time. New design of cutting drums will lead to improved tool cutting (pick) loading efficiency with less fine rock and dust production. It is important factor in safety of mining operations. The results of this work will be taken into account for the design of continuous miner. Easy maintainability of machine equipment is just as important factor for reducing maintenance time/costs and enhancing reliability.

The project stages include selective mining research for mining machinery development also for:

Increasing oil yield
Decreasing CO₂ pollution ca. 1,2 times
Decreasing ash amount
Decreasing oil shale losses (2 times)
Avoiding vibration caused by blasting
Avoiding ground surface subsidence (in case of longwall mining)
Increasing drifting and extracting productivity compared with current room and pillar mining (1,7 times)
Increasing safety of mining operations (dust explosion for oil shale and methane gas explosions for coal)

The testing documents elaboration will also be part of the work program of the project. On this part the main partner will be Tallinn University of Technology in cooperation with Mining Department and VKG Oil, Estonia. Also it is planned to cooperating with European Continuous Miner and cutting tools producers.

The final aim of the research is to use BAT (Best available Technology) for underground mining in UK areas with arduous conditions of coal and oil-shale deposits.

2 The main problems to be solved

Cutting selectively oil shale (15MPa) and hard limestone (up to 100MPa). The oil shale seam consists up to 50% of limestone layers and peaces.
Roof support at the face
Stability of the main roof, roof bolting, pillar parameters
Backfilling with rock or residues (ash) from oil production
Water stopping and pumping in problematic environment (30m³/t expected)

3 Project team

Number	Role	Partner
1	Coordinator	Estonian Oil Shale Company, Estonia, http://www.ep.ee/?lang=en
2	Partner	Mining Department of Tallinn University of Technology, Estonia, http://mi.ttu.ee/mining
3	Partner	VKG Oil, Estonia, http://www.vkg.ee/?id=1981
4	Partner
5	Partner	European Continuous Miner producer
6	Partner	European Continuous Miner Cutting tool producer
7	Partner	European research group or institute working together with the machinery producer
8	Partner	European process equipment (crusher, sizer, screen, gravity separator) producer
9	Partner	European pump (pumps, dewatering and backfilling systems) producer
10	Partner	European support (supporting, bolting) producer

4 Current situation

Room and pillar mining with drill and blast technology. Supporting with bolts. Mining production is in total 14Mt/y, including 7Mt/y underground. Total raw material amount is 12Mt/y underground. Tests are made for opening two new mines, with total production 15Mt/y.

Overview of oil shale mining and problems can be found here: (overview.pdf ),
Optimisation of Oil Shale mining Continuous Mining technology: (http://staff.ttu.ee/~oleg/flash/flash.html )
Breakage of oil shale by cutting can be read here: http://www.ttu.ee/maeinst/os/adamson.html
Shortwall mining possibilities in Estonia (http://www.kirj.ee/oilshale/8_nikitin_2003_4.pdf )
Photos of tests can be seen here: photos.
Room dimensions in oil shale mines could be up to 15m in opposite to conventional coal mining with 5m dimensions.

Figure 1 Current underground room and pillar mining

The planned research project is based on the Sustainable Development Act (RT² I 1995, 31, 384; 1997, 48, 772; 1999, 29, 398; 2000, 54, 348) and directs the development of the Estonian fuel and energy sector until 2015. The document defines the current situation in the sector, presents issues set out in the EU accession treaty, prognoses developments in the energy consumption, states the strategic development objectives for the energy sector, the development principles and the extent of the necessary investments. The plan describes the problems that require further analysis and the functions of the state relating to supervision and regulation. The strategic environmental assessment of the document is presented in the strategic environmental assessment statement of the long-term public fuel and energy sector development plan, which has been prepared at the same time as the development plan. The development plan and the statement are both disclosed on the website of the Ministry of Economic Affairs and Communications (http://www.mkm.ee/).

The specified plan helped to direct the development of the power engineering the main objective of which is to attain a level in the Estonian energy sector which is required to join the EU. At the same time, the plan does not provide sufficiently specific guidelines, e.g. regarding the objectives of renewable energy, combined heat and power production and energy conservation, and is too non-specific in directing the development of the energy sector.

The visions and needs relating to the future of power engineering have now changed to a significant extent - in connection with accession to the EU, a number of requirements and objectives have arisen, the energy technology has developed and implementation of the Kyoto Protocol provides new possibilities etc. In order to comply with the specified criteria, it is necessary to specify the public power engineering development plan.

5 Previous situation

Continuous miner operations keep playing a major role in the underground industry in over fourteen countries worldwide. Estonia’s oil-shale industry is at the beginning of introducing modern fully mechanized continuous miner systems, which will dramatically increase productivity and safety in the underground mines.

A longitudinal cutting head type was first introduced in the former Soviet Union by modifying the Hungarian F2 roadheaders and in 1970s in Estonia by modifying the Russian coal roadheader 4PP-3. Evaluation of breakability was performed by a method developed by A. A. Skotchinsky Institute of Mining Engineering (St Petersburg, Russia). For this purpose over a hundred samples produced by cutting of oil shale and limestone, as well as taken in mines by mechanical cutting of oil shale were analysed. In researches evaluations were made for using coal-mining equipment for mining oil shale. Comparative evaluations were made by the experimental cutting of oil shale in both directions – along and across the bedding, including also mining scale experiments with cutting heads rotating round horizontal (transverse heads) and vertical axes (longitudinal heads). In both cases the efficiency was estimated by power requirement for cutting. The feasibility was shown of breaking oil shale by direction of cutting across the bedding by using cutting drums on horizontal axis of rotation. The research also evidenced that the existing coal shearers proved low endurance for mining oil shale. Therefore, the problem arose of developing special types of shearers for mining oil shale or modifying the existing coal shearers.

It was further stated that the better pick penetration of the longitudinal machines allows excavation of a harder strata and at higher rates with lower pick consumption for an equivalent sized transverse machine. It was reported that with the longitudinal cutting heads the dust forming per unit of time decreases due to smaller peripheral speed. The change in the magnitude of the resultant boom force reaction during a transition from arcing to lifting is relatively high for the transverse heads, depending on cutting head design. Specific energy for cutting across the bedding with longitudinal heads is 1.3–1.35 times lower which practically corresponds to the change of the factor of stratification.

The results of these tests were used in large body of fundamental research into rock and coal cutting in the UK during the 1970’s and early 1980’s at the UK Mining Research and Development Establishment.

About three decades ago a progressive mining method with continuous miner, which is most suitable for the case of high-strength limestone layers in oil-shale bed, did not exist in oil-shale mines of the former USSR and in Estonia. Therefore, up to now oil shale mining with blasting is used as a basic mining method in Estonia minefields while continuous miner was tested for roadway driving only. With regard to cutting, the installed power of coal shearers and continuous miners has increased enormously since the original work. Actual state of the market has changed and a wide range of powerful mining equipment from well-known manufacturers like DOSCO, EIMCO, EICKHOFF, etc. is available now.

We have 30 years of experience in cutting with longwall shearers which were not capable of cutting hardest limestone layer inside of the seam. Tests with road headers have been carried out in 1970ties.

Figure 2 Cutting with longwall shearers

Figure 3 Testing Twin Boom Axial Road Header (Continuous miner) in Estonian Oil Shale deposit in 1970ties

We have tested Wirtgen surface miner SM2100 and SM2600 for two years and SM2200 and Man Tackraf surface miner, and are currently testing Wirtgen surface miner SM2500 for high selective mining in an open cast mine.

Figure 4 Testing Wirtgen surface miner SM2500 for high selective mining in an open cast mine

Figure 5 One billion tonnes of oil shale has been mined in Estonia from the beginning in 1916 until 2006

6 Testing criteria

Decreasing CO₂ pollution ca. 1,2 times

Decreasing ash amount

Decreasing oil shale losses

Avoiding vibration caused by blasting

Avoiding ground surface subsidence

Increasing oil yield

Increasing drifting and extracting productivity

Increasing safety of mining operations

7 European measure

1. Currently many coal fields in Europe face difficult mining conditions. The main problems in addition to deep bedding are unstable roof, dilution of side rock and content of abrasive and hard parts of side rock inside or between coal seams. Development of Coal mining technology by testing continuous mining systems in difficult conditions in Estonian Oil Shale deposit improves coal mining possibilities due to enhancing cutting, supporting and face transport form high productive shortwall face.

2. Bases for hard rock mechanical breaking have been tested in Estonia in 1970es. The results of these tests were used in continuous miners producing in UK. Currently The Mining machinery development. Hard rock mechanical breaking.

3. Currently Estonia is independent energy producer thanks to existing of Oil Shale deposit and favourable mining and processing conditions. Due to environmental restrictions, social pressure and deeper bedding of oil shale in potential mining fields, testing of high-productive, environmentally friendly, mechanical mining is needed for successful continuation of independent energy supply (oil shale) for EU state country, Estonia.

4. Decreasing need for energy import. Oil shale, shale oil (0,5% S, -15 freezing temp.)

5. Improving environmental situation in Europe and Baltic Sea region.

6. Decreasing CO₂ pollution, ash pollution and water pollution.

7. Improving safety (dust explosion for oil shale and methane gas explosions for coal)

Thank You,

Yours,

Ingo Valgma

Ingo.valgma@ttu.ee

Mining Department of Tallinn University of Technology