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Geomechanical Processes during Underground Mining: School of Underground Mining - Kindle edition by Volodymyr Bondarenko, Iryna Kovalevs'ka.
Table of contents

Kozyrev V. Panin I. Semenova Yu. Fedotova V. Geomechanics First Online: 13 September This is a preview of subscription content, log in to check access. Kozyrev, A. Google Scholar. Khaitun, S. Sobolev, G. Malinetsky, G. RAN , , vol. Oizerman, T. Kozyrev 1 V. Panin 1 I. Semenova 1 Yu. Appearing net nu- and computing experiments remains absolutely merical methods has allowed to put computing ex- high. To carry out calculations it is necessary to get periment into the new level.

The possibility of di- series of physical quantities which have to be set viding the research object into separated sites ele- during calculation process as coefficients of usual ments allows to form its difficult geometry and and differential equations. In addition, the adequacy physical structure combined with various system of of given results can be evaluated by comparing re- outer factors influencing on calculating area with sults of computing experiments and observations, and without an account of time factor.

The realiza- which can be a physical experiment also. Due to tion example of such technique is the calculation of computing experiment many series of construction the bearing girder stability of oil mining platform. Therefore, the a down part, ice corks and aggressive sea salt. The computing experiment allows choosing the range of calculation in time with an account of all mentioned varying technological factors, which within experi- factors had led to the result when bearing girder ca- ments can give the possibility to get optimum result pacity decreased in one third during five year ex- with low costs.

In this case, defined outer influence had Defining SSS of any not primitive system under been the sea salt, which destroyed cross elements of action of difficult loading, with meaning that the a girder; therefore, it had led to constructive distur- quantity of that loading and its distribution can be bances. As you noticed, during solving certain prob- changed in space and time, is trivial task requiring lem different factors from various fields of knowl- clear description about conditions to model the in- edge were considered.

The experiment had been teraction of separated elements of calculating area. If at Taking into account the duration and the develop- elastic calculation the interaction scheme of apply- ment of such models radical solution generally takes ing loading of initial conditions can not be changed, places. In this case, in geomechanics the approach al- then in case of sufficient relative displacements and lowing carrying out SSS calculation of drift support the vector of applying loadings and the quantity of and rock massif is realized separately.

The efficiency the zone of contact interaction with rocks can be of this approach sharply reduces at the growth of dif- changed rarely at the linear law. It stimulates to ap- ficulty of support elements interaction with the mas- ply non-static conditions of the contact between sif, surrounding a mine working. Similar difficulty is elements of rock bolt model and mine massif model also the nonlinearity of support construction behavior, at carrying out a calculating experiment. In such conditions bolt interaction with the surface of a hole.

At the physically reasonable solution of given problem may moment of resin bolt installation between steel, only be at entering fully description of polyvalent sys- resin and rocks of the hole surface the contacts tem of stress distribution between support elements based on chemical-molecular influence are set.

As a and rock layers. The a complex of materials having strength properties simplest elements of such calculating system, in and chemical characteristics. In results, for realizing terms of physical and geometrical meanings, are adequate modeling of rock bolt exploitation condi- rock bolts, frames, connection points of bolts and tions it is necessary, within single calculating frames, wire mesh, backing-up and a model of rock scheme, to use wide complex of initial conditions layer in a view of parallelepiped.

Since on a stage of a mine exploitation of Ukraine In the simplest geometric scheme of modeling the resin rock bolt is the widest-spread, modeling of resin bolt a single contact surface only exists, for which causes interest. In case, when contact loss ex- it is necessary to simplify this object as much as pects, or happens, between rocks and bolt body, possible, until to remove it from calculating area combined scheme is applied, in which the part of due to external loading replacement.

This approach hole model surface has rigid connection with a rock can not provide required accuracy of defining SSS bolt, and the part of its surface forms the contact system in conditions of creating little nonlinearity with a bolt in conditions of mutual slip. Geometric during carrying out computing experiments.

If preliminary bolts ten- rounded rocks. In result, redistribution of efforts as sion is considered, then in the calculating scheme in bolt construction and as at all drift contour oc- this condition, as a rule, will be realized by applying curs. Modeling at different mine-geologic condi- required effort along the normal on the end of a rock tions has revealed the biggest adequacy of the fol- bolt.

However, such approach is not fully adequate lowing calculating schemes: the first is the bolt hav- relatively to efforts and displacements distribution ing a steel rod and closely installed in a hole with on a surface of mine working contour. And, in case the same diameter; the second is a bearing plate of sufficient efforts of the preliminary bolt tension, with big diameter, rigidly contacting with the bolt, it is necessary to move to the second geometric added to the previous scheme; the third is the same scheme of modeling a steel-polymeric rock bolt.

The cross- occurs due to overlaying contact conditions for a section of a rock bolt is divided by such finite ele- rock bolt bearing plate. Two main approaches are ments into four similar sectors, and the axe of bolt applied: the first is a rock bolt installing in a bore- symmetry coincides with common edge of all four hole that internal surface of a bearing plate gets finite elements. In variants of the calculation of bolts and rock mas- As known, in most coal mines of Ukraine for sif interaction problems exist when cutting efforts in- supporting mine workings rock bolts, as single sup- fluencing on the model of a bolt prevailing relative to port, are used rarely.

In general bolts are exploited longitudinal loading. In such cases strength and de- in combination with a classical flexible frame sup- formational characteristics of polymeric resin, using port. Modeling a frame support is separately quite at bolt installation, significantly influence on bearing difficult task, which can be divided into few stages.

In results, for providing the adequacy of Let us start from the consideration of the main the calculation the third scheme of modeling bolt is question: how accurately is it necessary to describe needed. Due to using such schemes it is possible to the geometry of cross frame support profile? Gener- model displacements of bolt contour with quite big ally the geometry of flexible frame support is deformations in any chosen directions. As a rule, the omitted or simplified. In both cases receiving pictures of SSS cal- From above mentioned it becomes understood culating area can be fully corresponded to elastic that the formation of finite element net, for common state of real rock massif only.

As at developing non- case of modeling steel-polymeric bolt, is unconven- linear processes in the behavior of any material the tional. The first problem, common for any support accurate localization of its centers within selecting elements of a mine working, is small size of the fi- geometrical objects is required. The combination of the finite element size, ducing calculating area dimension, from another the total number of finite elements, conditions of fi- side, increase the stability of carrying out calcula- nite element connection on separated object bounda- tions.

However, at calculating with an account of ries of calculating area determines not only the ra- limiting and beyond-limiting material states, as a pidity of carrying out calculation, but and the qual- test showed, such simplification perceptibly influ- ity of receiving displacement field. In general it is ences on the raising stress along a drift in certain considered that the reduction of finite element linear frame cross-section. Therefore, using real geometry sizes always leads to the quality increase of receiv- of frame cross-section, though it increases the diffi- ing result.

It is fully conformed to reality of rela- culty of calculus, and in the same time fully allows tively simple calculations. And the Now let us pass to the consideration of influence whole picture of finite element net has clearly de- of qualitative modeling flexible tie of a frame sup- fined irregular character. During calculating such port on the stress and deformation distribution in a net can lead to the zone formation of fluctuating frame itself and nearest rock massif.

Applying stresses, that distorts its common picture. As ex- flexible tie in the frame construction allowed suffi- periment showed, for most solving problems it is ciently increase its work characteristics.

Deep Mining - Programme

However, optimal to select twenty-ties finite elements. All this tie, as a factor influencing on SSS system, com-. Con- movements relatively to each other in all range of structive feature of given support element at high examining geomechanical problems. When consid- rate modeling Figure 1a extremely increases com- erable movements of mine working contour are puting costs and decreases the stability of results.

At foreseen, then the another flexible tie model is ap- certain conditions the upper frame part can be ro- plied Figure 1c. In this case, the geometric authen- tated relatively to bars, that negatively effects on ticity of external frame contour is disturbed insig- static balance of all calculating area. Thereby, a nificantly. But considered technology of modeling can darenko Figure 1. Modeling the flexible tie of a frame support: a geometric accurate model; b the tie model providing for its movement without taking into account of dynamics with saving origin frame contour; c the tie model providing for big movements without saving dynamics taken into account.

Therefore, modeling the frame support flexibility geometry of which conforms to geometric charac- can take into account of big movements. It is teristics of real objects. In most cases such approach achieved due to flexible tie modeling, which is fixed guarantees reasonable adequacy of given primitive in and made from material possessing low resistance and real object characteristics. For version, when indicators to compressive efforts. On Figure 1, b the separating a lagging and a filling in calculation is movements of upper frame part, which lowered required, it is necessary to describe the geometry of down and simultaneously pressed the flexible tie concrete blocks with external frame curvature ap- model into a side bar, are well shown.

In result of propriately. It allows not to solve the task of the the arch movement, presented on Figure 1, c, reach- contact between bodies, touching along the surface ing up to mm Bondarenko , that causes to of different curvature. For emulating the behavior of increase zones of limiting rock state forming the loose environment the lagging is described by me- mine working arch. As such objects are entered in the nection of deformation and stress. Also Young construction for providing effort transmission and modulus is chosen to tend to 0.

Omitting these objects can suf- plex of separated geometric elements is not needed; ficiently change SSS of a frame and around mine geometrically, it is the complex of parallelepipeds, working rocks. These elements are steel concrete and mechanically, it is averaged characteristics, lagging, rock filling, wire mesh with wide cells, etc. From another averaged by mechanical characteristics object, the side, if to consider rock massif as a complex of rock. Such measures for real in-seam working tain problem becomes applied problem.

In spite of rock layers can have different geome- Foliation of rock massif extremely changes stress try and physical characteristics during modeling to distribution, as around mine working contour, and in increase the adequacy of received results, it has to zones next to boundaries of rock layers. In this case, change contact conditions on boundaries of these influence degree on stress field for different system layers. There are rigid contact, contact with darenko Using any type of contact can cause qualitative and quantita- tive changes of stress distribution, which presented on a Figure 3.

In case of rigid contact Figure 3a , at horizontal occurrence and not wide range of physical rock layer characteristics, the stress distribution is almost similar to the stress distribution in the model with- out foliation. And in the case of Figure 3b the stress distribution is significantly different from the previ- ous one. Such changes in qualitative and quantita- tive measures of stress distribution happened by en- tering mutual sliding of rock layers in the calculat- ing model.

Now, the stress level is higher in coal seam, than in surrounded rocks and its role of in- creasing drift stability extremely rises. Figure 2. Stress distribution in thin-layered massif near in- a b seam workings. Let us consider stress diagram presented on a Figure 2. The main reason, because of which the fo- liation influence is quite high in given calculating model, is the difference between rock layer strength. Rock layers forming foot and sides of a drift have the increased rigidness relative to rock layers, which forms upper and down areas of calculating model. It causes the stress concentration within geometric area of certain layer.

Taking into account of foliation the problem of reasonability of coal seam deep angle for adequacy of received results happens. To confirm all above mentioned the picture of stress distribution on a Figure 2 is analyzed. The Figure 3. Distributing stress intensity in a massif a with- major feature of this stress diagram is the absence of out taking into account of sliding on rock layer boundaries, b with taking into account of sliding on rock layer symmetry relative vertical axis of in-seam working, boundaries. Metal bars allow com- deformation in conditions of zones of plastic flow bining few bolts, being installed in the drift roof be- occurrence in elements of calculating model.

At that, the height in cross-section of bar model has to be increased relative to real meaning. It is necessary to ignore bearing plates of each contacting bolts in the whole support model. The contact between surfaces of bearing bar and rock massif has to be defined as free, without using friction force. It is linked with two moments. Firstly, during the calculation of individual bolt movements, relatively to each other, absolute quantities can have b different directions, that will cause to appear addi- tional stresses in the bar.

At that, if the bar rigidly connects with a massif, it will cause to wrong cor- rection of SSS on mine working contour. Secondly, when wire mesh takes place between the bar and rock massif surface, it will not limit movements of the bearing bar along the surface of rock massif. In the considered support construction the wire mesh plays the key role of integration factor provid- ing for effort distribution between installed bolts and frames in mine working roof. However, this c mesh limits free near-the-contour rock movement into a mine working. And the quantity of resistance on similar movement in cross section of the con- struction is slightly small.

It allows to consider given element of the construction as rigid mem- brane, set in place of its contact with bolts and frame supports. In results, the wire mesh is modeled as an object repeating the drift contour with width not exceeding the diameter of bar mesh, and me- chanical characteristics corresponding to flexible Figure 4. Modeling the connection of a drift and a long- material. In this case, the additional of rheology 90 hours. In real condition such cable freely rounds a cable combined with a bolt, tying the body of cable frame and takes place between bearing and additional with bolt end; second — the form of longitudinal ca- bolt plate.

Thereby, the cable can slide easy along its ble axis was chosen as sinusoid with straight sec- length relatively to side bolts and frame bars. Then, tions on function maximum; third — the preliminary the loading of the cable in some area can go through cable tension was modeled due to penetrating the it on distance. This frame-bolt support feature, being cable into the frame. As the limitation of longitudinal puting modeling view. At relatively small transmission in zones of bolt contact — a cable and a deformations the bolt end moves into the drift more.

In results, the contact be- and the stress distribution suffered as qualitative and tween the cable and the frame is broken. With going as quantitative changes Figure 4b. Finally, since further elastoplastic calculation and the growth of 90 hours the growth of movements in roof and foot plastic deformation the cable presses into the frame of longwall Figure 4c is markedly seen, with load again. However, due to earlier lost contact in the redistribution of rock layers of the model.

Consequently, this problem has to ence also has localized character on time. Depen- be solved due to two calculating steps: the first is dently on mutual mine working size and existence the SSS calculation until the moment of cable ten- duration, such influence on SSS system can have as sion; the second is correcting parameters of contacts insignificantly e. All above mentioned relates to constructive sup- From all above mentioned the SSS calculation in port elements. However, functioning of the support the zone of longwall influence for mine workings extremely depends on SSS rock massif changes.

Fundamental factor taking into ac- bility of the frame support; high movements of mas- count of such changes influence in the model be- sif contour; stress relaxation, in result of rheological comes the time factor. In this case compensation of efforts and lation of stress and deformation in the rock massive geometric parameters of calculating area will allow become effort redistribution being perceived by to get averaged, and consequently, probable picture support elements.

Also, changing drift geometry on of SSS in the zone of real object location. Istanbul: ture of a mine working. Volume I: Results of cal- physical environment behavior. On a Figure 4, mychov, V. Developing scientific basics of in- creasing mine working stability of Western Donbass a the stress intensiveness is shown, which gained for mines. For this The calcula- tovitskiy, A.

Workshop in Mining Geomechanical Risk: Open Pit Stream

Methods of calculat- tion implemented with account of rheology had ing displacements and surrounded rocks reinforcement been showing within real 10 hours that absolute of Western Donbass mine workings. Parameters of shear zone and methods of their conditions control at underground mining of steep-dipping iron ore deposits in Kryvyi Rig basin.

ABSTRACT: Representative analysis of collected data according to surveying measurements of the earth surface deformations within the mine baffles of Kryvyi Rig iron ore basin is carried out. The relationships between the lowering of the stoping level and change of dimension of basin subsidence and surface collapse across the strike are found.

Practical aspects of implementing the methods of diagnosis and monitoring of geoengineering state of rock mass in the lines of shear and collapse zones are considered. These deposits, as a rule, are small in In Kryvyi Rig iron-ore basin throughout decades a size in relation to the main ore bodies, were mined unique situation with preservation of daylight area by special projects. Therefore, such siderable areas damaged by mining operations were potential cavities may also be a potential hazard to founded.

Surface damages with craters, caves and the day surface. These voids are potentially dangerous In the first case, with the unstable soft ores rather in the event of their caving. Calculating characteris- smooth day surface subsidence with the formation tics theoretically guarantee their stability, however, of the projected caving zones were observed. In this case, the horizons, at mining of which the effect of stoping on prediction of caving zones was and still is more the day surface is considerably reduced. In this case, difficult task, because of taking into account physi- it sudden and uneven caves on the surface are practi- cal and mechanical properties of rocks with higher cally impossible.

At the same time, there is a gradual strength characteristics. In this regard, incomplete subsidence of a considerably large area due to the ceiling settling is possible at the room roof caving, increasing size of trough movement of overlying which in turn can lead to mini-rooms formation, rocks with a decrease in underground mining. Settling of such mini-rooms located near the tionship between the lowering of stoping level and day surface for example, the conditions of deposit change the size of trough movement and the day development of the former MA n.

Ilyicha can surface caving, as well as the definition of guide- lead to unplanned day surface caves many years lines and methods for diagnosis and monitoring of later after deposit declining and complete mine geoengeneering state of rock massif in the lines of closure. InSAR is a radar-location method using interfe- The area of undermined territory estimated by the rometric radar. The method allows to gies These areas have a tendency to expand measure potentially the terrain change in the centi- due to continuous iron ore underground mining.

So, the monitoring of the existing voids state and LIDAR is a laser radar infrared — range with re- undermined territories is a priority for future devel- mote sensing optical technology, which allows you opment of the Kryvyi Rig iron ore basin. The control of geomechanical rock massif state in On the basis of remote sensing the day surface a the lines of displacement and caving zones in the spatial analysis of the obtained results and data in areas of active and dead mines is possible by creat- real time processing is performed, which allows to ing a geoinformation system for prevention and obtain a detailed picture of the deformation and to monitoring the day surface settling.

At geoinforma- predict the possible risk zones. To create an electronic database of existing un- mations and the determination of the causes and derground voids on the basis of the preserved min- patterns of these deformations. In our opinion, the first step is to perform a pre- 2. To implement a system for monitoring defor- liminary simulation and launch a pilot project in a mations of the day surface with the construction of small area, such as the eastern edge of Gleevatskiy dynamic digital models of terrain changes in real quarry of PJSC CGOK in the zone of underground time.

To identify the main patterns and the magni- liquidated MA n. The latter serves as a of the unknown voids and their projected volumes. To create an electronic database of existent and gon Group, and partners. Based on the results of monitoring of the day surface deformations and the electronic database of The practice and experience of mining enterprises existent and projected underground voids to create a show that the current costs of implementing meas- geoinformation system for early warning of possible ures to prevent possible emergencies is much lower surface subsidence in a particular area of the Kryvyi than the cost of their liquidation in the future.

Rig basin. It is our deep conviction that the only way to 7. To clarify the boundaries of the potentially guarantee the impossibility of the day surface cav- dangerous zones of the day surface displacement on ing and subsidence within the boundaries of the the basis of geoinformation system for prevention Krivbass mine areas is the introduction on the mines and monitoring of over large areas subsidence.

When the momentary apparent in- mal system for monitoring deformations of the day crease in production costs, these systems develop- surface with the construction of dynamic digital ment will provide savings in the future, ensuring the models of terrain changes. Modern technologies of ore deposits development. Scientific Papers on the work of the Second Interna-. Concept and assumptions for developing underground brown coal gasification plant for supplying synthesized gas to heat and power plant. ABSTRACT: Concept of developing underground brown coal gasification plant for supplying synthesized gas to heat and power plant operating as a cogeneration unit is described in this paper.

Calculations of energy balance connected with the demand for gas fuel are shown. Dimensions and number of underground reactors are given as well. Basic assumptions for energy plant are discussed. Some elements of project economic as- sessment are also presented. In case of lignite it is espe- furnace gas and its production is relatively cheap. The proposed solution is It is extremely important in regions, where local highly advantageous for the investor.

It allows for community protests against open pit mines. On the using the existing power plant to verify the installa- areas where surface infrastructure is developed, tion for underground lignite gasification ULG as a there would be an opportunity to obtain the chemi- source of fuel for energy production. It is also a safe cal energy contained in brown coal with minimal in- way of carrying out the technological tests due to terference in local plans of land development. The success It is a by- tion purpose as well as the possibility of using the product of smelting process Nowak et al Initially the heat and power plant used only the hard After abandoning supplying the plant with blast coal as a fuel Nowak et al During the next furnace gas it is planned to use only the network years, the blast furnace gas from the smelter was gas.

The alternative is, however, the concept of in- used to heat the boilers together with coal. The net- work gas is also delivered to the installation and it is. Future changes assume the sets with the following parameters of electric power: successive abandonment of the hard coal. It is supplied by Total power is It is assumed that in future the hard coal fuel will be They supply three turbine sets, one produces the totally replaced by the natural, network gas.

It is heat and is adjusted to condensation work, while also planned to install new boilers adjusted for co- two are of bleeding — condensation type. The aim ernization for co-combustion uses the natural nitro- of this project will be: gen-saturated gas of Lw previously GZ Production of power and heat energy in high Blast furnace gas is produced in shaft furnaces efficient gas cogeneration.

Providing the energy in emergency situations — utilized through the dust-cleaning and transferring power safety of smelter and mines. Economic effectiveness. Its heat value ranges from 3.

Event Contacts

Its heat value is 2. Addition- and power plant and combusted together with blast ally it needed to be cleaned before delivery to the furnace gas. Exhaust fumes, due the high level of power and heat plant. Since the blast furnace gas parameters are not It is proposed to use in the heat and power plant good enough for its effective combustion, it is con- the synthesized gas having low to medium parame- ditioned by natural, network gas, mainly to adjust ters.

The selection will be possible after detailed and stabilize it. The regulatory and standard re- analyze of capabilities and requirements of boilers, quirements for Lw type gas are as follows: in which the gas will be used. Probably it will be the. It results from applying the supply flow on the the gas quality after its conversion. Those tests are near level and the higher profitability of using the under preparation now.

The issue will be analyzed in de-. Planned locations of underground gasification sites and gas pipeline routes delivering gas to heat and power plant: 1 — first version of location, 2 — alternative version; A, B, C, D — alternative routes of gas pipelines. Due to the CO2 the parameters of syngas, including composition, aid, low humidity of gas almost zero the higher heat value and flow rate, should be the same as en- value may be expected. Then, the demand for gas ergy parameters of currently used process gas.

Pa- will be Total demand for Assuming that 1 kg of lignite gives 2. Planning the annual production value: Additionally the gas loses caused by its migration into the rock mass must be taken into consideration. Then the demand for solid fuel Since the ULG installation will be commissioned is It is sug- cially after the detailed geological survey and labo- ratory tests, these estimates may need the revision. Assum- sized gas delivery, since the data necessary to calcu- ing that the lignite density is 1.

First, the results of lignite tests as well as Supposing the beds discontinuity, different types defining the quality and composition of blow gases of tectonic disturbances, possible change of lignite are necessary. Test of lignite were made — total value of chemical energy, GJ. The area of planned geological surveys is now Minimum efficiency of lignite gasification system under populated. The by several villages with compact settlement. The construction of gasification installation may proceed significant part of buildings is in bad technical con- in stages, each stage ca.

Rock Falls -- Preventing Rock Fall Injuries in Underground

New buildings, The syngas delivered to the heat and power plant mainly single family houses supplement the existing will be used to produce: space development or are constructed on new ap- — in summer: power energy in condensation, pointed investment areas adjacent to the already — during heating season: power energy together built-up area. In some cases the carbonaceous rocks many problems in its utilization.

From the other side it is conven- at all or was substituted by carbonaceous rocks. Basing on geological report for ground lignite gasification. The distance between the individual lignite layers in The area of lignite, designed for future gasification, the bed reaches 30 meters in places. It will be placed within the region pre- — Henryk from 0. Hence it nite gasification depends on the heat and power was necessary, in some cases, to use the data from plant demand with regard of fuel. As it was calculated in chapter 2, about 35 defining the data as in the study Nowak et al, million tons of lignite, having the volume of about , what gives the opportunity to compare both 30 million m3, are necessary for that purpose.

Since there are not any Basing on preliminary defined geological condi- practical experiences in applying this method, dif- tions and a concept of gasification lines develop- ferent interpretations of financial regulation are pos- ment, it was assumed that underground reactors will sible, however it is not very important from the be constructed successively.

They will be used dur- point of financial evaluation at that stage of work. Those numbers are only estimates. The precise The analyze was made according to the same determining of their number will be possible after rules as in the second II part of gasification, i. The life the water vapor, even in case of applying the air in- time of basic equipment and capital assets ranges jection. In order to maintain, constant in time, flow. It reflects the ap- — environmental fees; proximate estimate of their economic life time. At- — royalties; tempts of forecast for longer periods of time will be — consumables; useless.

Environmental Law, with rates ac- — construction of storage tanks; cording to the appendix no. This cost with further development are tion 0. Rates of house tax — expenditures for installation of equipment and of At ings and storage tank for the backfill. The price of gas calculated this way was holes and up building the installations are planned. However the main outlays will be costs of drilling Using the above data the quantity of income was the boreholes see chapter 4.

Other re- While calculating the operation costs in order to ceipts, such as sale or reuse of reclaimed land, sale define the financial internal rate of return, the item of the own heat and electric power, were not taken which are not related with real cash expense, except into account. Since the plant does to want to base only an the hard without VAT; coal, it must find the alternative fuel, which may be — calculation period is 20 years, including one the gas, especially the syngas.

International Journal of Rock Mechanics and Mining Sciences

Assuming the lowest predicted machines — 3. It is a typical Results of financial analyze: procedure in case of changing the feeding gas. Net present value NPV is about vestment i. Residual about It was is of estimative nature. It results from the absence of also comprised while calculating IRR and NPV in- geological data, detailed extraction parameters, dexes. Estimated residual value is about Unquestionably the results vestment outlays.

The way of determining the resid- of economic evaluation indicate that the further de- ual value assumed in the analyze is well-founded velopment works are reasonable taking into consid- because the lignite gasification station will operate eration the venture profitability aspect.

Will Bawden, Ph.D., P.Eng. (ON & BC)

Almost all known years is envisaged. This economic analyze of the ULG projects, where economic data are presented, project indicated the high profitability of proposed has very good estimates and high profitability of the mining venture. Connecting the installation with the The presented proposal of applying the under- heat and power plant should not be a problem. Four ground lignite gasification to produce the synthe- routes for the pipeline were proposed. The ground tized gas and its delivery to the heat and power plant through which the pipeline is planned to pass in- in the smelter is a cost-effective project and the cludes the farmland and waste land without any im- works on the project are continued.

They will be portant surface elevations. Nu- merous modernizations and gradual reduction of Derkacz, J. The reason is re- Kozula R. Category, Czech Republic: Technical-economical ground gasification of lignite in Poland. School of Un- ranking of lignite deposits management from the perspec- derground Mining. Team work under leadership Nowak, J. Multiple evaluation of lig- concept of lignite deposits management considering the nite deposits management in Lower Silesia through construction of pilot underground gasification installation — their underground gasification. XIX Conf.

Actualities Stage II. Piwocki, M. Detailed location analyze and pre- deposit management possibilities. Task 5: Reserves cal- liminary calculation of reserves data concerning the culation according to the current operative economic solid fuels for ULG installation and proving the delivery criteria, PIG, Poland. Geological report for using bio-gasification method. Study of rock displacement with the help of equivalent materials using room-and-pillar mining method.

ABSTRACT: Field study made with the help of equivalent materials to determine minimum dimension of interchamber and barrier pillars and limiting chamber span was carried out. Modeling was made for gypsum quarry. Modeling results were used to design calculation Breaking compressive stress was taken as a me- diagrams to determine loads acting on barrier pillar. Furthermore, modeling enabled to determine limit- Modeling was made in conditions of Olekminsk ing chamber span and minimum width of barrier quarry.

Density of gypsum 2. While studying set Force similarity were determined by the follow- of tests materials which characteristic is given in ing equation Tables 1, 2 were selected. Density of model material was slightly changed at glass. Strength of equivalent material at geometri- stratification within the nature.

Layer characteristic cal scale was twice as little as that one given at scale is given in the Table 3. The process of patternmaking is the following: The following stand dimensions to patternmaking material was arranged by layers with cm width were accepted: length is 2 m, height is 1 m, width is and compressed by roller 10 cycles. The front wall of the pattern was made of. Breaking compressive stress for rocks and model material at geometrical scale Table 3.

Layers characteristics. Experiment showed that 8-m chamber span was Rock name Layer height within working, cm accepted with rather high level of safety margin. Dolomite 10 Such workout of interchamber pillar was carried out to the left of barrier pillar. Destruction of inter- Gypsum 8 chamber pillars has started. Pillar was destruc- Mudstone 3 ted first, then the rest interchamber pillars and at last Silt 2 the barrier pillar Figure 1c. Dolomite 2 There was not arch formation within chamber Gypsum 4 roof.

Entire rock mass above gypsum layer has Dolomite 4 completely collapsed. Ceiling rock displacement. The width of barrier pillars was 20 formation is not an obligatory element of roof col- and 30 m all dimensions here and then are given in lapse. Rock mass displacement up to the surface terms of nature. Model imitated the area of deposit. Model scale is The width of barrier pillar is 20 m in nature. Six General construction of the model is the same as the pillars were initially worked-out on the both sides of previous one.

Barrier pillar is in the center of the barrier pillar. Construction was in the stable state, model, but its width was increased up to 30 m all there was no caving. Gradual interchamber pillar dimensions are given in terms of nature. Chambers caving was imitated then. As a result, load acting on are worked-out both to the right and to the left of it.

First, the width of 2 in- 10 chambers are worked-out within the right panel terchamber pillars was reduced up to 2 m pillars and 7 chambers are worked-out within the left one. There were no disturbances. It is Chamber scale is Then these pillars were completely re- panel and chamber span was increased up to 44 m moved and chamber span was reduced up to 32 m.

Figure 2a. After that pillar destruction between Such span was stable Figure 1b. Rocks within the. Caving spread to the model spread to the neighboring model. So, width of bar- surface at once. Modeling concerning adequacy of pillars and chamber span to the level of strength: a interchamber pillar was worked-out to the right of barrier one; b interchamber pillar was worked-out to the left of barrier one; c model after roof rock collapse. It was not enough to collapse the rest pillars and shifting rock mass to the surface Figure 2c.

In the first two cases stable chamber span was 32 There was not arch formation. Barrier pillar left the and 44 m. To check this result one more time model same. It confirmed an adequacy of its dimensions to No 3 was worked-out Figure 3a. Span of a single the level of strength in case of emergency. Roof collapse took place at m span that confirmed results obtained in the models 1 and 2. It should be noted that under roof collapse within such single chamber, arch was formed but its contour is indistinct Figure 3b. Model 2. Modeling the process of roof collapse in case of interchamber pillar destruction: a model before roof collapse within the left panel; b roof collapse within the left panel; c roof collapse within the right panel after working- out pillars It was supposed to determine the character of en- How to make barrier pillar stable after intercham- closing rock displacement within the panel confined ber pillar destruction?

Obviously, it should take load by barrier pillars with the help of modeling in case from entire rock mass within panel, i. It is required which interchambers pillars took earlier. According to design the diagram determining loads acting on to the study described above calculation diagram to barrier pillar. This diagram shows that load three or four interchamber pillars acting on calculation acting barrier pillar is neighboring pillars increases and they are destructed as well.

Moreover, rocks are cut along the boundary of barrier pillar. Arch is not formed. Figure 3. Model 3. Compressed stresses within barrier pillar will be 4b in his paper Kulikov It is supposed that V. Probably, it can be true in definite conditions. Modeling carried out These stresses should be less than assumed ones. It is pointed out that this conclusion doesn't corre- spond to that one offered by V.

Kulikov Figure. Figure 4. Calculation diagram to determine load on running Roof of the chambers seemed to be stable while meter of barrier pillar was obtained by modeling increasing span up to 44 m. It is unexpected conclu- made with the help of equivalent material. This cal- sion. In future it will be required to carry out the culation diagram of barrier pillar is true to condi- study of tension stresses within the roof of chambers tions where modeling was carried out, that is, rock with the same span using the method of elasticity mass above roof rock is m, panel width is theory to explain validity of such large spans.

Some studies showed that load acting on pillars Kuznetsov, M. It is de- skiy, M Ph. Study of rock manifestation on the termined by rock weight from the roof layer to pres- models. Moscow: Ugletechizdat: Nasonov, I. Modeling mining processes. Moscow: sure curve. However, diagram of determining load Nedra: Accord- Kulikov, V. Textbook on production processes ing to this diagram load acting on pillar is deter- and production technology. Shkremetko St. Petersburg Energy Institute, St.

Petersburg, Russia. The peculiarities of the management of environmental risks to humans and the environment in post- industrial areas have been analyzed. The necessity of using methods of bioindication to control the state of environmental objects and health of the population on post-industrial mining areas has been substantiated. Restructuring of the coal industry of Ukraine in of resources at which the operation of mining enter- is the most ambitious attempt to recover prises makes no economic sense; and reconstruct a huge economic sector of the state — the issue of liability of economic entities for the in a relatively short time.

This was a positive aspect consequences of mine closure has not been cleared up. As a result of reconstruction, the coal mines closure, which would take into account all industry was supposed to become a more compact environmental impacts from the moment of shut- and market-oriented branch.

However, in practice down of production equipment to the development the positive results of restructuring of the coal in- of strategies for sustainable operation of post- dustry faded into insignificance. The drastic nega- industrial areas. Besides, in most cases the ecologi- tive socio-economic and environmental impacts that cal problems arising at different stages of liquida- led to the emergence of regions with persistent tion of unprofitable mines have considerable impact symptoms of depression have come to the fore.

With the advent of new directions of in- has neither improved the ecological situation, nor fluence on the environment, there is a need to or- solved any other problems that emerged during their ganize: exploitation and liquidation. All of this is related to 1 management of the hydrogeological regime of the fact that the mine closures were not preceded by the high density mining areas; the comprehensive scientific assessments and fore- 2 continuous treatment of highly mineralized casts for the state of environment in these regions as mining water discharged into the hydrographic net- well as no consequences of further influence of the work; liquidated mines on the components of the environ- 3 neutralization of hazardous and radioactive ment were studied.

In particular, such unreasoned waste and land rehabilitation; and unreasonable closure of mines may lead to 4 accounting of mining holes and works for their catastrophic consequences both ecological and so- stabilization; cial as the coal industry is a very complicated multi- 5 bringing of waste heaps to an environmentally industrial production and economic complex, which safe condition.

It is necessary to develop the solved, particularly: methods of environmental risk assessment at mine — there is no clear notion of the volume of mining closure and the system of standards that would take. Hoshovski Till now the liquidation of the coal mines has Coal mining is accompanied by significant in- been funded residually and with the violations of flows of water into mine workings, since the pro- environmental laws.

Neglecting of environmental duction of 1 tonn of Ukrainian coal involves about 3 safety regulations during the closure of mines leads m3 of groundwater. It should be noted that for dec- to significant changes and violation of hydrological ades no proper attention was paid to the issues of regime of areas, pollution of surface and groundwa- treatment of mine waters on the mining enterprises.

Also there remain unresolved issues of treatment of The purpose of this study was to analyze the state mine waters collected in gathering ponds of closed of the environment in the post-industrial mining re- mines as well as no standards for their carrying back gions of Ukraine, where the mines are closed. The coal industry is the foundation for sustainable In about Major coal reserves are concentrated in Do- closed mines of Donbas.

Mining industry also method of mine closure leads to exhaustion and pol- dominates in the GDP structure of independent lution of water resources, both surface and under- Ukraine, although for comparison in the U. According to the data of been a decline in the coal industry of Ukraine. According to the experts ity of most mines, difficult mining and geological each million tons of Ukrainian coal requires about conditions and the lack of a new mine construction. Lack of This has led to mass closure of mines. The long- vegetation on the waste heaps causes their erosion term use of mineral resources in the mining regions both by water and air, which further leads to a nega- resulted in significant changes in the environment tive impact on the environment.

The issue of further handling of waste heaps after Closure of coal mines leads to negative environ- closure of mines remains unresolved. Large areas of coal-measure rocks in- the atmospheric air, the concentration of which 10 tercepted by mine workings led to deformation of times exceeds the maximum permissible limits the earth's surface and destruction of residential and MPL.

During 24 hours 10 t of carbon monoxide, industrial objects. Besides, most of liquidated mines 1. Distribution of burning heaps, by coal mining re- from m and from Taking in consideration the — pollution of atmospheric air, surface and under- above, a special attention should be paid to the ground waters. Table 2 from every waste heap. This is due to the oxidation and 3 show the content of micro- and ultramicro- of pyrites contained in the heaps, which further elements in the rock of the the ChCCM waste heap leads to transformation of some metals, particularly Informational Fe , Al , Mn , Zn , into mobile forms.

Table 2. As Tables 2 and 3 show, the content of heavy met- corded in the area of over 2. The depth of als far exceeds MPL, for example, by 45,5 times for subsidence averages 0. Most underflooding of settlements, etc. The area of built-up areas. Thus, Be- one mining-geological system. It is migrated though the pores, cracks and total area of Among the faults in rocks. The permanent increase of flooded areas is getting to the surface for more than 20 years.

During mainly caused by man-made factors. In Cher- this period, the explosions and ignition of methane vonohrad mining region the total area that in some or in residential and industrial premises have been ob- other way has experienced the negative consequences served within this mining region. Besides, the emission of achyn, Mezhyrichia, Silets, and Sosnivka villages. Therefore, an important component of is 3. The land subsidence also leads to the for- ments of houses, water wells and other underground mation of man-made lakes, such as the lake of over structures.

In general the flooding has mostly oc- impact on the state of the environmental objects and curred in the central part of Chervonohrad mining re- human health. The termination of economic activity gion where more industrial objects and linear utilities of mining enterprises does not guarantee the elimi- are located.

That is why the closure of mines should be mine water drainage systems and washing by the carried out in a way allowing for elimination of groundwater of toxic components from the rocks of negative impact on the environmental objects and waste heaps, which are widely used in the region for health of population living in these areas. However, till now there Also in the karst activation in the mining re- are no methodological principles for analysis and gions of Ukraine is in progress, which is due to the evaluation of ecological risks to the environment effect of mine drainage on the coal mining areas and public health during the liquidation of mines Informational Gorova Another important factor requiring attention at Ecological risk is defined as the probability of de- closing of mines is methane emission to the atmos- liberate or accidental, gradual or catastrophic an- pheric air as the methane is a powerful greenhouse thropogenic changes of the existing environmental gas which causes climate changes.

Methane emis- objects, factors and ecological resources. The main amount of nents: risk to the environmental objects and the risk methane is released to the atmosphere during the to humans. Each of the components is quite impor- coal mining process. Currently Ukraine takes fourth tant for assessing the state of the environment, be- place in the world by volume of methane emitted to cause the scale of risk occurrence and the level of its the atmosphere from the coal deposits.

In general. It should also be noted that industrial areas it is reasonable to use the bioindica- the important factor of risk management is provision tion methods that allow conducting of complex as- of information on ecological situation of post- sessment for all factors by taking into consideration industrial areas to the public through mass media. For the environmental objects.

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Figure 1 shows the structural flowchart of man- levels in several coal-mining regions of Ukraine. Bioindica- eration and development of mining regions of tors that have been grown in post-industrial areas Ukraine. Factors of Impact of Mass Closure of environmental protection measures. The Coal of Ukraine, 7: The conducted analysis of the impact of closure Hoshovski, S. Hydrogeological and Geochemical of mining enterprises on the environmental objects Problems at Liquidation of the Coal Mines. The Coal of allows for the following conclusions: Ukraine, 7: The Coal of Ukraine, 2: The Coal of Ukraine, 4: The permanent ecological monitoring centres The methods should be created in post-industrial areas.

Analysis of Ecological Situation in the Mining Regions For timely detection and prevention of negative ef- of Ukraine. Ecological Bulletin, 3: Survey and Zoning by the should be conducted on the territories of liquidated Degree of Influence of Anthropogenic Factors on the mining enterprises. Kyiv: monitoring of post-industrial areas will allow citi- Polimed: Moscow: Approved by the environmental threats and neutralisation of various Resolution of RosEcology,