67 results about "Surface mining" patented technology

The invention relates to a green and environment-friendly deep sea mineral conveying system without tail water being discharged to the ocean. The green and environment-friendly deep sea mineral conveying system comprises a tail water circulating system and a mineral conveying system. The tail water circulating system comprises a tail water pump, a tail water pipe and a tail water collecting device; the mineral conveying system comprises an ore pulp pump, a mineral conveying vertical pipe and a relay cabin; one end of the draft tube is connected with the tail water pump, and the other end of the draft tube is connected with the tail water collecting device; the ore pulp pump is connected to the ore conveying vertical pipe in series, the ore conveying vertical pipe is hung on the water surface mining ship in a suspended mode, and the relay cabin is arranged at the tail end of the ore conveying vertical pipe. The relay cabin is connected with the mining vehicle through a hose; the tail water collecting device, the mixing cabin, the ore conveying vertical pipe and the mining ship are sequentially communicated to form a tail water internal circulation path, and no tail water is discharged to the ocean in the ore conveying process. Through fusion design of the tail water discharge pump, the tail water discharge pipe, the tail water collection device and the mineral conveying system, circulation of deep-sea mining tail water in the conveying system is achieved, and the tail water can be prevented from being discharged to the sea.

The invention relates to the technical field of mining machine transmission mechanisms, in particular to an automatic tensioning system and an open-cast mining machine, and the automatic tensioning system comprises a speed reducer output wheel and a milling roller receiving wheel which are connected through a belt, and further comprises a tensioning part connected with the belt and used for adjusting the tensioning force of the belt; the control part is connected with the tensioning part and used for controlling the tensioning part to change the tensioning force of the belt; and the information acquisition module is used for acquiring the tensioning part information, the speed reducer output wheel information, the milling roller receiving wheel information, a first preset range value and a second preset range value. Compared with a traditional tensioning device of a fixed structure, the system can respond to the requirement for belt tensioning force change caused by various factors in the working process in real time, the appropriate tensioning degree of the belt is automatically maintained in the equipment operation process, the power transmission stability and the equipment operation efficiency are improved, and the system is suitable for popularization and application. And the equipment fault and the maintenance cost caused by the problems of belt slipping and the like are reduced.

The present application relates to the technical field of open-pit mining, in particular to a fully internal discharge period stripping and dumping balance method for open-pit coal mine, comprising: calculating internal discharge space utilization coefficient, ideal internal discharge space utilization coefficient and surplus dumping space; establishing a natural stripping and dumping curve, the natural stripping and dumping curve taking internal discharge space as horizontal coordinate and taking cumulative stripping amount as vertical coordinate, the slope of the natural stripping and dumping curve being internal discharge space utilization coefficient, defining the stage with slope less than ideal internal discharge space utilization coefficient as space surplus stage and defining the stage with slope greater than ideal internal discharge space utilization coefficient as space insufficient stage; finding a year limit set in which the sum of surplus dumping space of space insufficient stage and space surplus stage is 0; calculating the cost of each year limit in the year limit set and finding the year limit corresponding to the lowest cost, which is defined as optimal balance period; and formulating stripping and dumping operation plan by using the optimal balance period. The present application can judge the dumping space surplus and insufficient stages in fully internal discharge period, and improve internal discharge space utilization rate.

The invention relates to a landform-vegetation-hydrology-pond four-dimensional integrated comprehensive ecological restoration method suitable for an open-cast mining field, and belongs to the technical field of mine ecological restoration. Comprising the following steps of (1) landform and rock soil restoration, (2) soil vegetation restoration, (3) side slope hydrological regulation and control and (4) pond ecologication.According to the ecological restoration method, a four-dimensional integrated collaborative restoration technology system is adopted, and the ecological function of a mine is optimized through multi-dimension and multi-technology collaborative optimization.

The invention relates to a transportation method based on bridges and culverts, and relates to the technical field of open-cast mining. The transportation method based on the bridge and culvert comprises the steps that the bridge and culvert is arranged on one side of a first preset position, the bridge and culvert comprises a bridge body and at least one culvert penetrating through the bridge body, and the culvert communicates with the first preset position and a second preset position; each culvert comprises a first lane and a second lane which are opposite in driving direction; the first vehicle group transports materials through the bridge and culvert road; and the second vehicle travels from the second preset position to the first preset position through a first lane in the culvert, and travels from the first preset position to the second preset position through a second lane in the culvert. The bridge and culvert road and the culvert are arranged to form the vertical crossing transportation line, coal is transported to the crushing station through the end slope road and the culvert, the vertical crossing transportation line is formed, the conflict problem of horizontal intersection of the first vehicle group and the second vehicle on the end slope road is solved, potential safety hazards caused by vehicle crossing are avoided, and the safety of the crushing station is improved. And the vehicle transportation operation efficiency is improved.

The utility model discloses a multi-step full-continuous coal mining system adopting buried inclined shaft arrangement for an open pit coal mine, and relates to the field of open pit coal mine mining. The coal mining equipment is composed of an open-cast mining machine, a belt transfer trolley, a transfer machine, a belt transfer bridge, a movable blanking hopper, a displacement belt conveyor, a second belt conveyor and a second lifting belt conveyor, and a coal seam bottom plate is laid at the bottom of the coal pit. The open pit coal mine multi-step full-continuous coal mining technology is achieved, the coal lifting route from the pit bottom working face to the earth surface does not interfere with the dumping truck route, tunneling operation is not needed for lifting the belt conveyor roadway, in the inner dumping propelling process, the lifting belt conveyor and the telescopic belt conveyor can work continuously and do not need to be moved, and the construction efficiency is improved. The problems that the inner dumping volume is affected by arrangement and pit reserving of lifting equipment, the lifting equipment moving time is long, and the mining efficiency is affected are solved.

The utility model discloses a system for anchoring dumping soil in open-cast mining, which comprises a plurality of anchoring bodies and a plurality of drainage pipes, and each drainage pipe is obliquely arranged; the multiple anchoring ropes are arranged at intervals and located on the goaf soil discharging slope face of the soil discharging step from left to right, the lower ends of the anchoring ropes are bound with the anchoring body at the lowest end and are bound with the anchoring bodies and the drainage pipes from bottom to top, and the upper ends of the anchoring ropes extend to the flat plate of the soil discharging step; the fixing piles are fixed to the flat plate of the dumping step, and the lower ends of the fixing piles are bound with the fixing ropes, so that the anchoring body and the drainage pipe are fixed through the fixing ropes, and sliding before soil burying is avoided; according to the utility model, the cost is low, an anchoring body does not need to be arranged by drilling holes during the mining of a lower section, the slope angle of a secondary stripping surface is greatly increased, the cost generated by secondary stripping can be greatly reduced, the mining can be completed without stripping even in an area with good working conditions, and a slope surface can be reserved at a position close to the lower section.

A rod feeding apparatus of the type used in underground and surface mining core drilling is disclosed. The apparatus has a receptacle configured to contain outer rods in a rod storage area. A rod discharging mechanism is configured to support the rods within the rod storage area, and actuatable to displace the rods upwardly and discharge one or more rods from the rod storage area. A rod dispenser associated with the receptacle is adapted to receive the one or more rods discharged from the rod storage area by action of the rod discharging mechanism, and to expose them onto a rod collection area of the rod dispenser for access.

The invention discloses a precious metal vein open-cast mining blasting parameter optimization intelligent calculation system, which comprises a data acquisition module, a double-target coupling algorithm module and an intelligent decision execution module, and is characterized in that the data acquisition module, the double-target coupling algorithm module and the intelligent decision execution module are in communication connection in sequence; the data acquisition module is used for acquiring vein geological grade data, carbon emission related data, slag recovery related data and equipment operation data; the dual-target coupling algorithm module is used for constructing a vein grade grade-rock stratum hardness-blasting energy parameter-carbon emission intensity quaternary mapping model on the basis of the collected data, and the vein grade grade-rock stratum hardness-blasting energy parameter-carbon emission intensity quaternary mapping model is constructed. Optimized weights are automatically distributed based on the vein grade, precise energy control blasting parameters are adopted for a high-grade area, and precious metal loss caused by excessive crushing is reduced; and optimizing the parameters of the low-grade area to guarantee the basic dissociation effect.

The utility model discloses an open-cast mining dust-settling machine, which relates to the technical field of dust-settling equipment, and adopts the technical scheme that the open-cast mining dust-settling machine comprises a water tank and a spray cylinder, the spray cylinder is provided with a spray nozzle, the spray nozzle is provided with a protective device, the protective device comprises a mounting shell fixedly connected to the spray nozzle, and a protective cover is detachably mounted in the mounting shell. The protective cover comprises an embedded plate used for being embedded into the mounting shell, the embedded plate is provided with a net eye cover protruding outwards, and the net eye cover is in a hemispherical shape. According to the dust settling machine for open-cast mining, due to the arrangement of the protective cover, it can be guaranteed that the spraying cylinder normally sprays water mist, splashed stones can be prevented from entering the spraying cylinder through the spraying opening, and therefore the situation that the splashed stones directly hit the fan can be avoided, the fan is prevented from being damaged, and the service life of the dust settling machine is effectively guaranteed.

The utility model discloses a mining structure for recovering a hanging wall ore body through external expansion of a surface mine, and belongs to the technical field of surface mine mining processes. The mining structure for recovering the hanging-wall ore body through external expansion of the surface mine can prevent rolling stones from threatening normal and safe production of the lower portion, and does not need to stop production and expand the wall for transition. The mining structure comprises a side slope close to a slope and a deep open-cast mining operation area below the side slope close to the slope, and further comprises a trapezoid rock wall, an open-section ditch and an operation platform, and the open-section ditch and the trapezoid rock wall are arranged on the operation platform with the free side slope. The operation platform with the free side slope is formed in the process of carrying out lateral blasting and slope expanding shovel transportation mining operation on the non-edge side slope of the open-section ditch, and other operation platforms are formed in the process of carrying out lateral blasting and slope expanding shovel transportation mining operation on the non-edge side slope; and operation rolling stones generated in the slope expanding mining operation process are blocked by the trapezoidal rock wall and are limited to fall into the deep open-cast mining operation area.

The invention discloses an open-pit mine continuous mining system and mining technology, and relates to the field of open-pit mining technology, the mining system comprises a cutting and transshipping all-in-one machine, a mine receiving car, a cable car, a crawler belt self-moving type sealing-tape machine and an end slope sealing-tape conveyor; the cutting and transshipping all-in-one machine comprises a mining machine and a transshipping sealing-tape machine between which a rotary supporting device is arranged; two conical spiral rollers are arranged on one side of a mining machine body, and receiving, crushing and transporting devices are arranged on the two sides of the advancing direction. A track is laid on a truss structure of the crawler belt self-moving type sealing-tape machine; the end slope rubber belt conveyor, the crawler belt self-moving type rubber belt conveyor and the ground rubber belt conveying system are in lap joint to form a continuous conveying system. Wherein the mining process comprises the steps of cutting coal by a mining machine, moving along with a mine receiving car and a cable car, conveying materials to the ground through each device, timely adjusting the direction by a transfer adhesive tape machine, and completing mining circulation. The mining continuity and efficiency of the strip mine are improved, the energy consumption and pollution are reduced, and the device moving time is shortened.

The present application relates to the technical field of equipment overhaul management, and discloses a kind of open pit mining equipment's overhaul management method and system, method includes: based on time period acquisition open pit mining equipment's vibration operating parameter;Periodic variation analysis is carried out to the vibration operating parameter of each time period, and the abnormal variation value of open pit mining equipment in each time period is calculated;Curve fitting is carried out to all abnormal variation values, and the abnormal variation value curve is obtained, and the abnormal variation value curve is processed, and the operating abnormal coefficient of open pit mining equipment is calculated;According to the relationship between operating abnormal coefficient and preset operating abnormal coefficient, it is judged whether open pit mining equipment needs to be overhauled and managed, can deeply fuse the overhaul management method of vibration parameter time sequence analysis, dynamic abnormality quantitative evaluation and intelligent decision-making judgment, to realize the abnormal fault accurate identification and accurate overhaul of open pit mining equipment fault, so as to improve equipment reliability, reduce maintenance cost, and guarantee mine safety production.

The present disclosure provides a method for establishing an optimal boundary of an open-pit mine and formulating a mining plan, including: obtaining geological exploration data, and establishing a three-dimensional model and a pit model; performing a single stripping and mining simulation operation on the pit, and calculating the stripping ratio; in response to the stripping ratio being greater than the limit stripping ratio, adjusting the shape of the mining slope until the stripping ratio is less than or equal to the limit stripping ratio, and continuing the next stripping and mining simulation operation; until the termination condition is reached, outputting the optimal boundary of the pit. By establishing a three-dimensional model and a pit model of the target open-pit mine, and performing stripping and mining simulation, and by setting the limit stripping ratio, the optimal boundary of the pit under the limit stripping ratio can be determined quickly and accurately. Compared with the prior art method of determining the optimal boundary through a limited number of schemes, this technology realizes a method for theoretically obtaining the optimal boundary of an open-pit mine, and through the corresponding optimization algorithm, the feasibility of this technology is realized, greatly improving the actual economic benefits of open-pit mining.

The present application relates to the technical field of strip mining machine, and particularly relates to a filter core life prediction method, an electronic device and a medium. The method constructs state information of the engineering machinery hydraulic circuit in a first preset time period into a plurality of sample features (each sample feature represents an operating state in a single preset unit time), and trains an original model to obtain a life prediction model, so that the model can learn the degradation law and time sequence characteristics of the filter core under different working conditions from historical operation samples. In actual application, real-time state information in a second preset time period is collected and input into the life prediction model, and the remaining service life of the filter core after the second preset time period is directly output.

The utility model relates to the technical field of blasting, in particular to a deep hole blasting device for open-cast mining, which reduces the shaking of an electric three-jaw chuck in the descending process, reduces the shaking of an explosive charge, prevents the explosive charge from colliding with the inner side wall of a deep hole when the explosive charge is put in the deep hole, and is high in safety and reliability. Comprising an electric moving trolley and an electric three-jaw chuck. A cavity is formed in the protection cylinder, the upper end and the lower end of the protection cylinder are open, the protection cylinder is installed on the electric moving vehicle through the lifting mechanism, the lifting mechanism is used for lifting the protection cylinder, the guide mechanism is installed on the electric three-jaw chuck and the protection cylinder, and the height adjusting mechanism is used for adjusting the height of the protection cylinder. The guide mechanism is used for guiding the electric three-jaw chuck, and the height adjusting mechanism is used for adjusting the height of the electric three-jaw chuck.

The invention discloses a crab-type deep-sea mining vehicle, which belongs to the technical field of underwater operation equipment, and comprises a vehicle body walking along a straight line, an ore plowing arm mounted at the front end of the vehicle body in the moving direction and capable of performing ore plowing action on a mining area on one side of the vehicle body, and a collecting arm mounted at the rear end of the vehicle body in the moving direction and used for collecting along the working path of the ore plowing arm, mining operation is completed in a mode of profiling crab movement, the plough arm and the collecting arm which are functionally differentiated in form are arranged, the plough arm is used for turning over the sediment mud surface, the collecting arm is used for collecting ore turned out of the sediment mud surface, the device is suitable for surface mining, suction equipment does not need to be used, and the risk of generating sediment plume is avoided from the source; according to the device, the disturbance to a deep sea ecological system is reduced, the requirement of sustainable development is met, meanwhile, the damage to the sediment mud surface is small, large-scale cutting equipment is not depended on, the device is compact in structure and low in gravity center, and subsidence on a soft sediment layer is effectively avoided.

This application provides a replaceable mining rake mechanism and an underwater mining vehicle. The replaceable mining rake mechanism is connected to the mining vehicle body. The mining rake mechanism includes: a mounting frame for connection to the mining vehicle body; a drive unit mounted on the mounting frame, with a docking portion on its main shaft; a mining rake detachably connected to the drive unit via the docking portion and rotated by the drive unit; and a locking assembly mounted on the mounting frame for clamping or releasing the mining rake connected to the drive unit. This solves the problem in the prior art where the mining rake mechanism is difficult to replace after wear and requires the entire mining vehicle to be lifted to a surface mining vessel for replacement, increasing maintenance time.

The present application relates to coal mining technology field, especially to a kind of coal mine working face surface mining subsidence pit monitoring method and system, coal mine working face surface mining subsidence pit monitoring method includes: target hard difficult collapse rock stratum is reformed, to reduce the strength, integrity and integrity of target hard difficult collapse rock stratum;The roof strata of working face initial mining stage are carried out surrounding rock structure detection, determine the damage range, strength and joint fissure distribution of target hard difficult collapse rock stratum of working face initial mining stage roof;The roof strata of working face initial mining stage are carried out pre-splitting, damage the integrity and strength of target hard difficult collapse rock stratum;The position of working face mining predicted subsidence pit is grouted and filled;Monitoring working face initial mining stage mining working face roof strata microseismic event, surface real-time displacement and surface subsidence during working face mining process.Effectively control roadway under the influence of double thick coal seam and hard roof working face mining surface subsidence pit management problem.

The invention provides a coal mine perforation blasting high-temperature hole temperature measuring device and method, and relates to the technical field of open-cast mining perforation blasting and coal mine safety. The device comprises a temperature measuring assembly, a connecting cable, a concentrator, a digital display processing unit, an alarm unit, a data transmission module and a power supply. According to the invention, the temperature in the blast hole can be accurately measured in real time, and the high-temperature risk is pre-warned, so that the safety production of a coal mine is guaranteed.

The invention belongs to the technical field of mining equipment, and particularly relates to a continuous mining and loading machine for open-cast mining and a working method. A material collecting device; the ore stripping device is arranged at the front end of the chassis, the ore stripping device can be switched between a high position and a low position, the ore stripping device is used for conducting ore stripping on an open-pit mine layer at the high position, stripped ore materials fall on the collecting device and the ground, and the ore stripping device is used for sending the ore materials on the ground to the collecting device at the low position; the temporary storage device is arranged at the rear end of the chassis; and the walking device is arranged on the chassis. Through integration of the high-position stripping function and the low-position material stripping function of the ore stripping device, the opening and closing material stripping and collecting function of the material collecting device and the material storing and buffering function of the material storing and buffering device, the technical bottlenecks that traditional equipment is long in operation window period, low in ore loading efficiency and poor in operation continuity are effectively solved, whole-process integrated continuous operation of stripping, material collecting and conveying is achieved, and the working efficiency is improved. And the mining efficiency of a large surface mine can be effectively improved.

The invention provides a method for calculating the safe distance between a dumping site outside a strip mine and a stope, and belongs to the technical field of open-cast mining design. The calculation method comprises the following steps: acquiring a safety distance between a slope base line of a lowermost step of the outer waste dump and a slope top line of an uppermost step of the stope according to respective slope forms of the outer waste dump and the stope, calculating a composite slope stability coefficient according to the safety distance, and comparing the slope stability coefficient with a slope safety reserve coefficient Fst, and the minimum safety distance meeting the safety requirement between the outer dumping site and the stope is obtained. According to the method, the slope stability change trend under different safety distances is researched, on the premise that the slope safety is guaranteed, the surface mine dumping distance is shortened, the economic benefits of the surface mine are improved, and the problem of reserving the safety distance between an outer dumping site and a stope is reasonably solved.

The utility model provides a replaceable front shovel structure and an underwater mining vehicle, the replaceable front shovel structure is used for being connected to a mining vehicle body, and the front shovel structure comprises a mounting part arranged on the mining vehicle body; a butt joint piece is arranged on the front shovel body, and the butt joint piece is detachably connected to the mounting part; the front shovel body is used for shoveling ore and is detachably connected to the mining vehicle body through cooperation of the butt joint piece and the installation part. The problems that in the prior art, after a front shovel part is abraded, underwater replacement is not easy, the whole mining vehicle needs to be lifted to a water surface mining ship to be replaced, and the maintenance time is prolonged are solved.

The invention provides a surface mining resource accurate positioning method, which relates to the field of mining, and comprises the following steps: obtaining the average grade of a sample of each drill hole in each production step of a mining area; the drill holes with the average grade larger than a first threshold value serve as resource enrichment drill holes; based on the grade interval and the distance between the resource enrichment drill holes, all the resource enrichment drill holes in each production step are divided into a plurality of ore body groups; dividing the reserve boundary of the ore body group on each production step according to the distance between the drill hole adjacent to the ore body group on each production step; according to the method, the system, the equipment and the medium for accurately positioning the open-cast mining resources, accurate positioning, closer to the actual field production, of the ore bodies on all the steps is achieved, and accurate positioning of the ore bodies on all the steps is achieved. And a more scientific design basis is provided for open-cast mining.

The invention provides a mechanical continuous mining device and method for an open pit coal mine bucket excavator, and relates to the field of open pit mining. The mining device comprises a bucket wheel body, a moving device is arranged below the bucket wheel body, a first rotating device is rotationally arranged on the moving device, and a first conveying device is arranged on the first rotating device; by arranging a third electric cylinder, the third electric cylinder can repeatedly and intermittently push and retract a third push rod, when a wheel claw rotates to the position below a rubber ball, the third electric cylinder pushes the third push rod to press a clamping plate downwards through the rubber ball, one end of the clamping plate rotates on a fourth rotating shaft, the other end of the clamping plate stretches a spring, and at the moment, a soil layer remaining in the wheel claw can be popped out; when the wheel claws rotate to the lower portion again and are filled with ore soil, under the gravity of the ore soil, the clamping plates press the springs downwards so as to block the through grooves, through the arrangement of the striking devices, residual ore soil in the wheel claws can be removed by striking the clamping plates after discharging of the wheel claws, and the mining efficiency is guaranteed.

This invention discloses a big data-driven optimization method and system for tailings dam recovery schemes, relating to the field of mineral resource recovery and intelligent optimization technology. The system's operation includes: constructing a detailed three-dimensional digital model of the dam area; conducting value zoning evaluation to delineate high-value recovery zones and low-value replacement zones; implementing surface mining and pipeline transportation of high-value zones using a floating sand mining platform; simultaneously filling low-value materials into the goaf to maintain stress balance; and dynamically regulating the hydraulic system based on intelligent monitoring data of the entire dam area to ensure the safety of the dry beach length and phreatic line. The system comprises six modules: multi-source data acquisition, digital modeling, intelligent zoning evaluation, recovery operation execution, synchronous filling and reinforcement, and dynamic monitoring and balance control. This application achieves synergistic optimization of efficient high-value tailings recovery and dam structural safety through spatial replacement and dynamic balance mechanisms.

The application discloses a mining method for open-pit mine, which comprises the following steps: performing overall perforation on the blasting pile of open-pit mining, performing secondary ore circle on the blasting pile after the test result is obtained, optimizing the blasting sequence according to different types of ores or waste rocks and the free surface of blasting, performing regional blasting according to the blasting sequence, achieving the purpose of sub-blasting, creating conditions for sub-shovel and sub-loading, and reducing the loss and dilution rate of mining.

The invention discloses an electric control method and an electric control system for cutting pick replacement of an open-cast mining machine, and belongs to the technical field of coal mining equipment. According to the electric control method, the operation box controls the motor to drive the cutting pick roller to rotate, then the controller controls the cutting pick replacing tool to replace damaged cutting picks, traditional manual operation is replaced, the cutting pick replacing tool greatly reduces the manual operation intensity, the replacing time of a single cutting pick is shortened, the replacing efficiency is effectively improved, and meanwhile the replacement cost is reduced. According to the method, a front safety barrier is constructed through forced safety logic that a toolbox is opened to trigger a sensor, the sensor transmits a first signal to a controller, and the controller responds to and controls a mining machine to stop. When a worker opens the tool storage box and prepares to replace cutting picks, the system automatically stops the mining machine, the risk that a roller rotates accidentally or parts are operated mistakenly due to the fact that a motor and a hydraulic system are started due to misoperation in traditional manual replacement is avoided from the source, and the personal safety of the worker during short-distance operation is guaranteed.

The invention discloses an underwater cluster type green mining system and method, and relates to the technical field of deep sea mining, and the underwater cluster type green mining system is composed of a wave energy power generation device, a storage cabin, an energy storage ball, a collecting and processing device, an underwater mining vehicle and a mining ship. The wave energy power generation device captures wave energy and stores the wave energy in an energy storage ball on the seabed, the energy storage ball supplies power to the collecting and processing device through a cable, the collecting and processing device wirelessly charges the underwater mining vehicle through a wireless charging transmitting end and a wireless charging receiving end, and the underwater mining vehicle collects minerals and sends the minerals to the collecting and processing device. And the ore is conveyed to a storage cabin on the sea surface through an ore lifting vertical pipe and a conveying pump and collected by a mining ship. The wave energy power generation device captures renewable wave energy and replaces diesel oil for power generation, electric power supply of a sea surface mining ship is not needed, an underwater mining vehicle and a collecting and processing device are deployed on the seabed, mining operation is prevented from being affected by sea surface extreme weather, and uninterrupted green mining all the year round is achieved.