Down-the-hole drilling rig mudziyo unoshandiswa kuchera zviwanikwa zvemvura pasi pevhu kana maumbirwo ematombo.Zviwanikwa zvemvura yepasi imvura yakachengetwa mumatombo epasi pevhu.Inowanzo kuwanikwa muvhu pores, fissures, uye pores mumatombo, uye inogona kukohwa nezvinhu zvakaita sematsime, matsime, uye gr...
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