Feem ntau cov hmoov hmoov muab cov khoom siv muaj cov hmoov nplej hmoov (ua cov hmoov av rau hauv hmoov) thiab ib sab cib. Cov hmoov tshiab tuaj yeem txuas ncaj qha mus rau hauv cov hmoov av, thiab cov hmoov zoo tuaj yeem yog sieved los ntawm ib sab cib kom tshem tawm impurities thiab tom qab ntawd rov ua dua tshiab.
Cov hmoov txau feem ntau yog hais txog ib txheej tiav ntawm cov hmoov txau tshuab, muaj ntau cov hmoov txau lossis cov hmoov av txau. Cov plaub sab saum toj no tuaj yeem tsim cov hmoov kom tiav cov hmoov txau, uas tuaj yeem ua tiav cov txheej txheem sib pab xws li cov kev pab them rau txheej, hmoov rov qab, thiab rov qab ua dua tshiab.
