The Planning On The Green Mine Construction Of The Nanyu Limestone Deposit In Jingxing County

The Nanyu limestone deposit in Jingxing county was first opencasted in1954and it was thoroughly closed in2012.During the mining period,8quarries weresuccessively opened and mined.According to the laws and regulations as well as theindustry standards about green mine constuction in China and on the basis of suitingcontrolling measures to local conditions and coordinating development,the planningon the green mine construction of the Nanyu Limestone Deposit in Jingxing Countyhas been done in this thesis.The main geological environmental problems caused by mining in the NanyuLimestone Deposit are instable slopes, dangerous cliffs, waste residues, relictmountains and mining pits.The loose materials on instable slopes are about5-10m inthickness and bared extensively with a few scattered weeds at some points.The loosematerials on instable slopes will slide down easily during rainstorm.The dangerouscliffs are mainly distributed on the original exploitation faces forming large scarps orsteep slopes.The rocks on the dangerous cliffs are disintegrated texture or lamelleteddisintegrated texture and are easily changed into collapses and landslides underexternal influences.The waste residues abandoned during mining are distributednearly everywhere and are not only the sourse of serious dust pollution but also thehidden dangers of landslides during rainstorm.The relict mountains and mining pitsdamage the land scenery and make natural ecologic environment bocome worse.On the basis of the geological environment regionalization in the mining area,geological environments are comprehensively evaluated by analytic hierarchyprocess.The subarea8disturbed slightly by mining is the favorable district of ecologicenvironment,the subareas1,2,3,5and6are the medium districts of ecologicenvironment, the subarea4is the poor district of ecologic environment and the subarea7disturbed strongly by mining is the very poor district of ecologicenvironment.The first phase of the green mine construction project is located in the east partof the mining area and is16.09hectares in area.The waste residue slopes which areeasily become landslides and debris flows are cut at the lower parts making their slopefoots become gentler. Then, the waste residue slopes are protected by the masonry ofcement mortar and rubble. Offtakes are constructed on the waste residue slopes. Andwater-guide troughs are also built on the tables over the waste residue slopes by themasonry of cement mortar and rubble. So rain water can flow freely into the offtakesthrough the water-guide troughs. High,steep,loose and easy to slump waste residueslopes are first cut at their lower parts making their slope foots becomegentler.Then,the waste residue slopes are protected by the step masonry of cementmortar and rubble. The loose coverings(rich in plant seeds and humus) on the remnanttables are collected and piled together. Coarse grains and large broken stones are putjust on the top of the remnant tables and then are covered by finer grains throughbackfilling and rolling layer by layer.After the remnant tables are leveled,the surfacesoils collected formerly are evenly distributed on the top of the remnant table.Andthen, torch trees are planted on the surfaces of the remnant tables by earth-removingmethod.The mining faces are very steep reaching angles of60°-70°in general.Grooves are excavated at the bottoms of the mining faces and then the grooves arebackfilled by soil. Next,creepers are planted in the grooves greening the white stubbletables.The top parts over the mining tables are made green by closing hillsides tofacilitate afforestation and by prohibition of grazing and man-made damage.The earthroad in the mining area is changed into gravel road and trees are planted in the bothsides of the road.The first phase of the green mine construction project begins inMarch and ends in December2016.The total cost of the project is2300000yuanRMB.The second phase of the green mine construction project is located in the middleand west parts of the mining area and is264.63hectares in area.The steep wasteresidue slopes are protected by the masonry of cement mortar and rubble or by that ofdry laid stones.Step masonries of cement mortar and rubble are constructed on thehigher and larger waste residue slopes.The wider step tables are made green byearth-removing planting method.The lower parts of the waste residue slopes arecovered by thick loess and are made green by planting toonasinensis roem, poplar,walnut tree, persimmon tree and so on.The tree distance is3×3m and the treesare arranged in triangle.The tree holes are60×60×60cm in size.The rolling miningtables distributed by many relict mountains and pits are levelled by bulldozer and thesmall relict mountains on the mining tables are scappled.Then, torch trees are plantedon the levelled tables by gouging hole and earth-removing planting method. The treedistance is3×3m and the trees are arranged in triangle.The tree holes are60×60×60cmin size. Grooves are excavated at the bottom of the table’s steep slope and then thegrooves are backfilled by soil. Next,creepers are planted in the grooves greening thewhite stubble mining faces.The gullies’ bottoms covered by thick loess are changedinto large-area terraced fields by constructing terrace ridges using abandoned brokenstones.The terrace ridges are arranged along contours and the surfaces of the terracedfields are inclined to the inside to intercept water and retain moisture.The executionsequences are successively clearing surface obstructives, treating top soils,levellingbottom earths,constructing terrace ridges and backfilling top soil. The second phase ofthe green mine construction project begins in March2017and ends in December2018.The total cost of the project is9000000yuan RMB.The green mine construction of Nayu Limestone Deposit can eliminate thehidden geological disasters such as landslides, debris flows and collapses.After theconstruction engineering is finished, cultivation lands can be increased to more than300acres and woodlands can be increased to more than1200acres.The ecologicenvironment and living condition can be advanced very much.The economic benefit,environmental benefit and social benefit can be harmonious and unitary.