Method of development of non-rocky formation and bedding plane deposits with medium and steep pitch
SUBSTANCE: method comprises the identification of operational field, mineral objects of extraction, inside them - operational blocks with standard, temporarily sub-standard and substandard and sub-standard mineral resources and separation of rocky ones, outstripping, current and realtime automated obtaining of express information, digging of uncovering "wells" or short trenches. The roboting automated extraction of a mineral from formations during their extraction using a mechanical method of separation of minerals and rocks of thin rocky interlayers, automated lifting of a mineral to the daylight area or its bypass to the receiving device arranged in an adit. At excavation of fields of upland type, a rock mass is left in a goaf after excavation of interlayers, the face area is temporarily kept using the automated and roboting ready-made fastening.
EFFECT: improvement of performance of development of non-rocky sheet deposits with medium and steep pitch.
The invention relates to the mining industry and can be used in the development of earth bedded deposits slope and a steep drop.
Known widely used open, underground and combined development of coal, ore and some non-metallic deposits earth type with mineral mass and its subsequent preparation and primary processing [1-4].
The main disadvantage of these traditional methods of production of mineral products is separating from an array of career (mine) field of nearly all rocks, splitting, moving and transportation, often at a considerable distance.
The most similar to its functional manifestation and technical results are primarily a way of downhole production, including leaching , as well as a new foreign way of mechanized mining of coal .
The main disadvantages of the first of them is the lack of specificity or selectivity, lack of completeness of the extraction of minerals from the subsoil and the extraction of useful components from mineral raw materials and method  is limited selectivity of the extraction of fossil coal (and other earth minerals) on quality of extracted mineral and energy consumption, zamylennost the bottom space.
The technical result - increase of efficiency of development of the earth formation and sheet-like deposits slope and a steep drop.
This result is achieved in that in the method of development of the earth formation and sheet-like deposits slope and a steep drop, including the allocation of operational fields, mineral objects seizure, and in them - operational blocks with the conditional, temporary non-conforming and non-conforming minerals and the release of rock, cutting-edge, current and operational automated acquisition of the Express-information, driving revealing "wells" or short trenches, carry out robotizirovannoi-automated excavation of minerals from the reservoir during testing using a mechanical method of separation of minerals and rocks in thin rock layers, automated lifting of minerals on the surface or his pass to the receiving device placed in the tunnel, when mining deposits upland type, abandonment of the rock mass in the developed space in the recess of the interlayers, temporarily maintaining the bottom hole space with the help of automated and robotic collapsible mount.
A comparable analysis of the prototype set is ENES differences of the proposed method, which in the aggregate: in-depth qualitative and quantitative differentiation of the working layers, in which their separation on the excavation items carried out on the basis of structural and qualitative characteristics, physico-mechanical properties of rocks, conditions and parameters of occurrence; using a combination of robotic and automated methods of Department of minerals and accommodated rocks from arrays of formation and sheet-like mineral body - chipping, half-rock, rezvanian dense and "draws" loose and quasiregular rocks, which can significantly reduce the energy intensity of their destruction; in the control lumpiness of the extracted mineral mass (coal, ore, and so on); reduce dust downhole space. Thus, the inventive method of robotic and automated exploration of the earth formation and sheet-like deposits slope and a steep drop corresponds to the conditions of novelty, has industrial applicability and inventive step of the development.
In Fig.1 shows a typical geological cross-section Apsatskogo coal Deposit.
Universal mobile unit for implementing the method will be equipped with several specialized manipulators, and allowing somatizirovanne with the help of soft computing devices in series, adjacent or sovmesheno exercise: quick access Express information about the local conditions of occurrence of minerals and elements about the main physical-mechanical and technological properties of minerals and waste rock interlayers, its processing and use; efficient allocation of different extraction elements and their selective separation from the rocks composing the formation and sheet-like mineral body, chipping or cutting, or drawing, depending on the strength of earth rocks.
The method comprises the following elements: formation and sheet-like mineral body earth deposits slope and a steep drop, for example Apsatskogo coal Deposit; host and accommodated rock; universal mobile unit, equipped with working bodies - manipulators, respectively, for receiving, processing and transmitting Express information about the properties of minerals, accommodating and accommodated breeds, conditions and parameters of occurrence of mineral solids to separate from the array of minerals and accommodated rocks thin interlayers; robotic and automated transport system for delivery of extracted minerals on the surface or directly to the consumer; software-computer is green to control the operation of all robotic complex.
The method is as follows.
Produce selection performance (pit, mine, mine, and similar) field, within - mineral objects seizure, and in them - operational blocks with the conditional, temporary non-conforming, non-conforming minerals and rock. Receive automated proactive, ongoing and rapid Express the information necessary for the timely allocation of mineral elements and the production of successive separate their excavation. Perform excavation revealing the workings of "wells" while working with disconnected layers or short trenches in the development of contiguous layers of mineral and rock layers in the process of working out every seam in his stretch with the excavation of the manipulator working body of a generic unit. Perform automated lifting of minerals on the surface using a robotic cable car transport system or the lowering of the galleries on the horizon (when mastering some upland fields), and then the conveyor delivery, or bypass it to the receiving device placed in the adit. Make the placement of rock mass in the developed space in the recess of the interlayers. Perform automated and robotizirovannye the temporary maintenance of bottom space using demountable fastening lightweight type, sequentially moved in the wellbore space.
The inventive method the development of mineral deposits provides in combination: comprehensiveness, use of natural resources and the extracted mineral raw materials, performance, security, and culture of work, efficiency and environmentally friendly production mining operations; the reduction of capital and operating costs, start date field development, infrastructure processes and operations.
Sources of information
1. The Handbook. Open pit mining / K. N. Trubetskoy, M., Potapov, K. E. Vinitsky, N. N. Melnikov), Mining Bureau, 1994. 590 S.
2. RF patent №2279544 from 10.07.2006. Method development steeply dipping deposits of minerals.
3. RF patent №2353771 from 27.04.2009. The method of open pit mining of mineral deposits.
4. RF patent №2327038 from 20.06.2008. How to develop powerful compound structure and average power of steep rocky ore deposits.
5. Arena C. J. Physico-chemical Geotechnology: Textbook. the allowance. - M.: Moscow state mining University, 2001. - 656 C.
6. The use of HIGHWALL system for the extraction of coal from the ledge section. Overview // Open pit mining, 2000, No. 2, S. 54-56.
The way of the development of earth formation and sheet-like deposits slope and a steep drop, including the allocation of usage of the frame fields mineral objects seizure, and in them - operational blocks with the conditional, temporary non-conforming and non-conforming minerals and the release of rock, cutting-edge, current and operational automated acquisition of the Express-information, driving revealing "wells" or short trenches, wherein the exercise robotizirovannoi-automated excavation of minerals from the reservoir during testing using a mechanical method of separation of minerals and rocks in thin rock layers, automated lifting of minerals on the surface or bypass to the receiving device placed in the tunnel, when mining deposits upland type, abandonment of the rock mass in developed space in the recess of the interlayers, temporarily maintaining the bottom hole space with the help of automated and robotic collapsible mount.
SUBSTANCE: method includes the automated and real-time obtaining and processing of the express information on the structure of array of consistently worked-out parts of ledges, their differentiated separation on the basis of the obtained complex system information into multi-scale structural elements of rocks with natural and technogenic fracturing. Separation of the obtained complex system information into multi-scale structural elements of rocks includes strength, elasto-rheological, thermophysical, structural and mechanical characteristics. The automated combined destruction down of structural members comprises the blasting under a mobile engine driven shelter and subsequent disintegration using an electrophysical method in view of the obtained characteristics. Direct accommodation in temporary storage stockpiles and delivery of the obtained products to consumers is performed after the automated feeding of mined rock into a receiving device of the mobile sorting unit with the subsequent separation of mined rock into respective fractions by coarseness.
EFFECT: improvement of performance of development of fields of building rocks of rocky and semi-rocky types.
SUBSTANCE: invention relates to the mining industry and can be used in development of large deposits of commercial minerals of hollow and tilting occurrence with use of the technique of continuous action with the open-pit mining. The method comprises permanent and initial trenching, mounting of transportation lines, excavation of commercial minerals by mining with wedged stopes. The mining with wedged stopes is carried out from the maximum width of excavation stope to the stope width BTi, which enables movement of transportation lines to the next wedged stope in accordance with the condition:
EFFECT: increase in productivity of excavation and loading complex in mining of deposits of commercial minerals by fan-mining method.
SUBSTANCE: invention relates to the mining industry and can be used mainly for loading the rock mass in the dump trucks in the implementation of continuous operation of miners. The method comprises implementation of independent processes of positioning hoppers, which occurs simultaneously with the working process of the miner in the automation of the process of orientation of the complex for loading relative to the miner, and the dump truck - relative to the complex. Implementation of independent processes of location of the hoppers is carried out by moving the frames of the hoppers in a vertical plane and the hopper carriages - in the horizontal plane and is controlled by the vertical movement mechanism and horizontal movement mechanism. At that the hoppers by means of articulated linkages with carriages are pivotable in a vertical plane by means of telescopic mechanisms of rotation. The hopper frames when moving interact by sliding bearings with vertical guides. The complex is equipped with vertical guides of the frame of the modules, which interact with the sliding bearings of the frames of the hoppers, the mechanisms of vertical movement connected with sliding bearings, the mechanisms of horizontal movement, mounted on the frames of the hoppers and connected to the hopper carriages for positioning the hoppers in the horizontal plane, and telescopic mechanisms of rotation of the hoppers in a vertical plane relative to the hinge connections, the system of automatic control of mechanisms of the complex functioning. The complex also is equipped with positioning sensors mounted on the frame of the complex and connected to the automatic control system, and to control loading the hoppers with rock mass on the bottoms of the hoppers the control sensors are placed. At that the automatic control system comprises a microprocessor with a control unit, a control panel of hydraulic system and electric generator.
EFFECT: improvement of the process efficiency of the complex operation for loading of the rock mass in the dump trucks.
2 cl, 2 dwg
SUBSTANCE: method in which the quarry along the length is divided by the lines, of which the first is worked out to a target depth with an external spoil disposal and working out of the subsequent ones is carried out using an internal spoil disposal, placing the overburden in the mined-out space of the adjacent line with the common formation of the dump tiers with the development of mining work. And simultaneously with the start of mining operations in the quarry of the first stage within the quarry of the second stage along the deposits the front quarry is built with angles of the slopes of sides close to the angles of reclamation, the cross-overs are located in it for providing cargo communication of the upper working horizons of the quarry of the first stage with the surface, with the reduction of mining operations in the quarry of the first stage on its longitudinal side the loop cross-overs are made adjacent to the bottom of the quarry in the area of the end side, which is formed with a slope towards the temporary side, marking the limit of the quarries of first and second stage, when achievement in the mining operations in the quarry of the first stage of the current depth. The separation of the sides of the front quarry is carried out, turning them into working, and after complete working out the reserves of the quarry of the first stage the working out the reserves of the quarry of the second stage is carried out, while linking its main openings to the main openings of quarry of the first stage in the locations of the loops, the inner dump in the worked-out area of quarry of the first stage is formed as inclined and horizontal tiers, at first directly with the surface from the side not occupied with main openings, the inclined tier is made with bulldozers with width of the platform on top equal to zero, and then using a draglines it is extended by the amount of boom extension, after this the horizontal tiers are dumped in series from the bottom up from the loop cross-overs with the high ensuring their sustainability, to complete formation of the inner dump.
EFFECT: decrease in the distance of inner transportation of overburden from the working area to the inner dump.
SUBSTANCE: method comprises formation of the working area, technology of mining overburden benches and providing cargo communication of the working horizons to the surface, the overburden benches of the working area are taken of the increased height (25-30 m), based on the condition of their mining using excavators with extended working equipment, the benches are combined into groups of three in each. At that for the upper and lower benches in the groups the minimum working areas are provided with dimensions equal to the width of the transport platforms, providing two-way traffic of technology vehicles and its manoeuvring, for the middle benches the width of the platforms is taken equal to the sum of the width of minimum working area and the width of the recess stope with ready-to-dig volumes of overburden, providing the necessary speed of reduction of mining operations in each group of overburden benches of the working area during the formation of the breakdown of the blasted rock mass based on conditions of placing it on the middle and lower benches. And the breakdown of the rock remaining on the middle benches, is divided into two layers, the upper of which are worked out with excavators with top loading into vehicles that are on the platforms of upper benches, the volumes of the lower layers and volumes of the overburden dumped with explosion on the lower benches are worked out with individual excavators with loading to vehicles at the same level with them. After working out the ready for excavation volumes of overburden in all groups of benches and formation of the corresponding volumes on the adjacent underlying benches and displacement of the boundary of the groups occurring at that down by one bench, their working out is repeated in the above procedure, opening the overburden benches of the working area of is carried out using steep sliding cross-overs with the longitudinal slope of 12-15° and width, providing placement of the breakdown of the blasted rock mass during their extension and at the same time the through passage of the technological transport, the extension of steep cross-overs is carried out using track and wheel loaders by dividing the breakdown of the blasted rock mass to the horizontal and inclined layers with the height defined taking into account the trajectory of motion of the loader bucket.
EFFECT: reduction of current stripping ratio in the initial period of working out of the field.
SUBSTANCE: control method comprises control of the intensity of the high temperature thermodynamic laser irradiation to the area of the laser radiation, regulation of change of the wavefront of the laser radiation, control of milling cutting force P, the parameters of the rock material rigidity f through the registration sensor of the rock material rigidity, mounted on the frame of fibre optic laser emitter, the speed control of movement of the surface miner Vki, introduction to program of algorithm of calculation of the wavefront of laser radiation power W, depending on the parameters of rock material rigidity f and the approach increment of fibre optic emitters li based on the equation.
EFFECT: invention enables to improve the efficiency of management of technological preparation for excavation of rock material and provides remote control of destruction of rock material.
2 cl, 10 dwg
SUBSTANCE: invention relates to the mining industry and can be used in open development of mineral deposits. The method comprises opening the deposit and recovery of mineral deposits with ledges with formation of the inclined surfaces of slopes and pit edges, drilling wells, loading of wells with explosives, breaking of the rock mass with blasting of explosives in units, distributed on the pit ledges, loading and transportation of the rock mass to the sites of its storage or further processing. The location sites and size of rock blocks are determined, hovering on the slopes of the ledges. From the earth's surface or upstream sites of ledges the workers and drilling equipment is descended on the lifelines to the upper surface of the hovering rock block. In the hovering rock block the wells are drilled with the distance between the wells not exceeding the maximum distance equal to the twice depth of distribution in the rock mass in the vicinity of the well of area of the rock destruction that occurs when blasting explosives in the well. The wells are drilled parallel to the surface of the slope of the ledge, and the distance between the wells and the surface of the slope of the ledge is taken as equal to the depth of distribution in the rock mass in the vicinity of the well of area of the rock destruction that occurs when blasting explosives in the well.
EFFECT: improving the safety of open mining operations.
SUBSTANCE: method is performed using the automated system which comprises a laser device with the possibility of longitudinal displacement and is provided with a damper platform placed on the surface miner frame and pivotally connected to the frame of the laser device. The laser device is placed on the frame guides with the ability to move longitudinally along the guides on the rolling bearings using the drive connected with the automatic control unit, and is made in the form of a cassette with fibre-optic emitters placed along the moving direction of the surface miner.
EFFECT: improved technological efficiency due to forming in the surface layer of the processed areas of zones with overlapping of laser slots, providing high concentration of stresses, alternating loads and deformation during laser processing of significant surface; performance improvement of process of destruction, disintegration and decrease in the volume of fraction requiring additional subsequent crushing due to combining the process of cutting slits and layers-strip cutting of rock materials by surface miners, and providing environmental safety.
2 cl, 5 dwg
SUBSTANCE: invention relates to mining and can be used in dredging of valley and floodplain detritus. This method comprises construction of stream diversion channel, service pool for dredge and system of water treatment plants. Stream diversion channel is composed by natural bed in drag bank made at working the deposit in lengthwise direction with earth prism filling to inner slope of dredge bank. Extraction of mineral during stream diversion channel is carried out by asymmetric manoeuvring of dredge to ensure maximum cross-section area of dredge bank. Water level in service pool and water treatment plats is kept level with stream diversion channel water horizon.
EFFECT: higher environmental safety, decreased scope of works.
3 cl, 2 dwg
SUBSTANCE: proposed method comprises drilling the vertical wells, charging the latter, placing the charges, short-delay blasting of said wells and selective excavation. Blasting of blocks is performed in bulk. Note here that all three dimensions of blasted block, i.e. width, length and height, are set irrespective of the position of contacts and the number of ore bodies. After block blasting, portion of shotpile is dumped over slope roof with working of the first pass over rock on the side of ore body hanging side. Depending on attitude of ore body in blasted block, selective working of productive bench is performed in two sub-benches with mining in layers.
EFFECT: decreased losses of ore and ore dilution.
FIELD: mining art, in particular, open-pit mining of mineral resources by high benches.
SUBSTANCE: large-diameter single holes are replaced by a pair of divergent holes of a smaller diameter, in which one hole is always vertical, and the other one is inclined towards the bench; the single holes of the larger diameter are replaced with a pair of divergent bundles of parallel converged holes, in which one bundle is vertical, and the other is inclined towards the bench; the single holes of the larger diameter are replaced with a pair of divergent holes of a smaller diameter, in which one hole is vertical, and the other is inclined towards the bench and positioned in the vertical plane parallel with the first one and distant from it by 1-2 hole diameters; the single holes of the larger diameter are replaced by a pair of divergent bundles of parallel converging holes, in which one bundle is vertical, and the other is inclined towards the bench and positioned in the vertical plane parallel with the first one and distant from it by 1-2 hole diameters.
EFFECT: enhanced efficiency of blasting of the benches.
7 cl, 6 dwg
FIELD: mining industry.
SUBSTANCE: method includes dividing quarry on rows, of which first one is extracted to planned depth with external dump-forming, and extraction of following rows is performed with use of internal dump-forming, placing dug rocks to extracted space of adjacent row with common displacement of dump front with development of mining operations. Second and following rows of quarry are divided on basis of height on extraction levels, extraction of uppermost level is performed with placement of dug rocks in upper dump level of extracted space of adjacent row, using surface transporting communication lines, and during extraction of second extractive level dumping of dump level of inner dump is primarily performed by forming pioneer dump at longitudinal processed edge of quarry, on upper area of which transporting lines are placed and dumping of dump level is performed from there, with descent of mining operations in working area of extractive level profile of upper dump area is altered to provided necessary cargo communications of working horizons of extractive level to dump level, after extraction of extractive level remaining pioneer dump is dug to upper mark of following extractive level, and extraction of following extractive levels is performed analogically, using reformed upper area of pioneer dump.
EFFECT: higher efficiency.
FIELD: mining industry.
SUBSTANCE: method includes cutting steps with varying angles. Angles of double step slopes, different on basis of quarry depth, are formed with consideration of decrease of irregularity parameters with deposit depth, with natural block level of upper horizons and influence from mass explosions and wind erosion of rocks with gradual increase of their steepness until forming of vertical slopes of double steps during additional operations in quarry, while angles of slopes and edge portions on upper horizons in highly fractured rocks may be 50-55°, in rocks of average and non-specific fracture levels - 70-60° and in low-fractured rocks may be 80-85°, and edge portions 60-90 m high in deep portion of quarry with vertical double steps and preventive berms 10 m have slant angle 80-85°.
EFFECT: higher efficiency.
6 dwg, 1 tbl, 1 ex
FIELD: mining industry.
SUBSTANCE: method includes extraction of quarry to planned depth with use of quarry ore chutes with accumulating bunkers, cutting ore chutes with deepening of mining in quarry, crushing ore blocks and pieces from face from bunker walls by explosives, loading ore to railway vehicles, cutting and shutting upper portion of ore chutes at each level when mining approaches there is performed by division on beds and semi-shelves with charges in wells, providing for crushing of rock to needed dimensions and safety of mine walls, and further decrease of pieces size and increasing efficiency of ore chute operation by excluding ore suspension is achieved by use of crushing assembly in form of bowl with plate at base, working as anvil under layer of rock, from where ore mass is self-propelled to bunker, and from there by feeder is sent to crusher and further through intermediate conveyer to main conveyer.
EFFECT: higher efficiency.
4 dwg, 1 ex
FIELD: mining industry.
SUBSTANCE: method includes extracting quarry to planned depth by ore and rocks extraction by displacement of shelves along horizons with transferring to crushing plants, crushing rocks and then delivering them by lifting device to the surface, during extraction of quarry to planned depth at first stage during construction of board at the end of quarry in zone of decrease of power of deposit in stable rocks conveyer rope system is constructed, connected to hoisting machine, to bed with recesses, allowing to raise crushed material to large height at steep angle and with deepening of mining and displacement of crushers to lower horizons conveyer system is extended to provide for optimal transport shoulder for gathering vehicles.
EFFECT: higher efficiency, higher productiveness.
2 cl, 6 dwg, 1 ex
FIELD: mining industry.
SUBSTANCE: method includes opening deposit of mineral resource along its length, extraction of opened rocks in shelves, forming on one of the portions of deposit of forward extracted space reaching planned bottom, moving rocks to external dumps and into extracted space, processing and transporting of mineral resource. Deposit extraction is performed in two directions - perpendicularly to length of deposit with deepening and along length to quarry bottom, while volume of extraction of mineral resource along length is increased and volume of extraction of resources perpendicularly to length is proportionally decreased.
EFFECT: higher efficiency.
2 cl, 3 dwg
FIELD: mining industry.
SUBSTANCE: method includes serial extraction of drifts with placement of opened rocks of drifts in extracted space of previous drifts, continuous combined processes of softening, extraction and movement of rock to dump. Drifts are positioned along cut trench, extraction is performed by adjacent horizontal shavings of face area, rock of each drift is moved by throwing directly to extracted space and compacted in range by realization of kinetic energy of rock.
EFFECT: higher efficiency.
FIELD: mining industry, applicable for slanting of high benches at development of magmatic deposits of mineral resources by open pit.
SUBSTANCE: the method includes drilling of contour holes for formation of a screening peephole, buffer and breaking holes to a depth corresponding to the height of one working subbench with a redrill, the middle row of breaking holes is made with an incomplete drill, charging of the openings and their blasting, dispatch of the rock, after blasting first of outline openings, for formation of the screening peephole, and then of breaking holes and mucking of the rock, similar operations are performed on the underlying subbench of the lower high bench, at the development of the lower high bench, the development of the upper and lower benches is conducted by doubling of the working subbenches, at the development of the lower subbench of the upper high bench the outline openings are drilled to the whole height of the doubled bench, the buffer openings are drilled at a distance of 12 to 13 diameters of the charge from the outline openings and to a depth at least corresponding to the height of one working subbench with a redrill equal to 6-8 diameters of the charge, the first and last rows of the breaking holes are drilled with a redrill, equal to 4-5 diameters of the charge, and the incomplete drill of the middle row of the breaking holes makes up 7-8 diameters of the charge, after blasting of the buffer and breaking opening and mucking of the rock a crest is formed, from whose surface on the side of the slope outline and buffer openings are drilled, the first ones - to the height of doubled subbenches, and the second ones - to the height at least of one lower working subbench, then the breaking openings to the same height as in the above - and underlying subbenches and for production of a natural protective bank on the upper section of the lower high bench in the section of the berm the formed ridge is liquidated by drilling, charging and blasting of the openings of small diameter and depth.
EFFECT: enhanced stability of high benches on the outline of the open pit.
2 cl, 3 dwg, 1 ex
FIELD: mining industry.
SUBSTANCE: method includes opening deposit at distance 150 meters from river and forming of natural filtering wall between river and trench, pumping of water from trench into river, extraction of mineral resource, revegetation of dumps, filling of trench with water, accomplishment of formed water body. Mineral resource is extracted from two serially opened trenches - auxiliary, revegetated as water body, and main, positioned at opposite side of river, and soil from opening of which is used for revegetation of auxiliary trench, while in main trench along whole board on the side of river right beyond mining operations inner dump is formed with width not less than 250 meters and with height at same level with earth surface, water from trenches is fed into river, and then into water body through intermediate collectors, while after forming of water body currents of soil waters between trenches and river are made balanced, balance level is estimated on basis of water levels in auxiliary trench and river.
EFFECT: higher efficiency.
1 dwg, 1 ex
FIELD: mining industry.
SUBSTANCE: method includes extraction of quarry to planned depth in stages with construction f boards with parameters, allowed from stability condition, shutting boards, finishing mineral resource massif. Building and shutting of temporary boards during extraction of steep layers of next level after change of order of extraction of opening and ore zones is started after construction and spacing in center of cut of well-like mine with vertical shelves, with parameters, which are provided for by minimal radiuses of rounded edges enough for movement of rock via spiral chutes to surface to outer dumps, with narrowing space towards bottom at level of opened level of deep portion of deposit with lesser total coefficient of opening of stage and finally board is constructed by steep vertical shelves in deep zone.
EFFECT: higher efficiency.
1 ex, 10 dwg