Txhawb cov thee leeg thiab vov phaj:
Kho tau cov khoom siv hluav taws xob tsuas yog siv nyob rau hauv cov mines thee los txhawb cov thee ntawm thee thiab ru tsev phaj kom ntseeg tau tias qhov kev nyab xeeb ntawm thee mining ua haujlwm.
Nws tuaj yeem hloov kho kom haum rau ntau qhov chaw ua haujlwm thiab cov kev ua haujlwm nyuaj rau hauv cov mines thee, thiab paub kev txhawb nqa thiab qhov siab hloov kho cov kab ke hydraulic.
