Tom qab ob peb xyoos ntawm txoj kev loj hlob, mine-siv tawg-pov thawj cov khoom hluav taws xob tau ua ntau yam kev vam meej.Coal mine hluav taws xob automation tshuab, thee mine kev nyab xeeb kev tshuaj xyuas qhov system thiab lwm yam khoom siv automation tau mus txog ib theem.Mechatronics thev naus laus zis thiab hluav taws xob hluav taws xob ceev tswj tshuab tau siv hauv cov mines thee.Underground tsheb thauj mus los machinery, hoisting machinery thiab thee mining machinery tau pib siv dav.Nws yuav tsum tau hais tias tom qab xyoo ntawm txoj kev loj hlob, ib qho kev tsim ua tiav rau cov khoom tawg-pov thawj hluav taws xob tau tsim, uas ua tau raws li cov kev xav tau ntawm kev loj hlob tam sim no ntawm cov mines hauv av rau cov khoom siv hluav taws xob thiab kev xa tawm, kev siv tshuab hauv av, thiab kev tswj thiab kev tiv thaiv.
Nyob rau hauv xyoo tas los no, cov khoom tawg-pov thawj hluav taws xob rau cov mines tau nthuav dav hauv cov qauv thiab cov qauv tshwj xeeb, xws li tawg-pov thawj siab thiab tsis tshua muaj hluav taws xob mos pib rau mines, tawg-pov thawj zaus hloov pauv ceev tswj cov khoom siv rau mines, tawg-pov thawj siab thiab qis. voltage ua ke hloov pauv rau mines thiab lwm yam khoom siv thev naus laus zis tshiab.Nws kuj tau siv dav hauv av hauv cov mines.Vim qhov kev thov tas mus li thiab ruaj khov, kuv lub teb chaws cov khoom siv hluav taws xob mining tau tsim kev lag luam loj dua, thiab cov phooj ywg kev sib tw tau dhau los ua nruj heev.Yuav ua li cas kom tsis txhob muaj kev sib tw nqi, tsis txhob qis qis dua cov khoom lag luam, thiab txhim kho kev lag luam los ntawm kev siv tshuab thev naus laus zis tau dhau los ua cov lus nug rau txhua tus neeg tsim khoom thiab cov neeg ua haujlwm ntawm cov khoom siv hluav taws xob mining.Txoj hauv kev rau txoj kev vam meej ntawm kev lag luam nyob qhov twg?Tsuas yog kev tsim kho thev naus laus zis nkaus xwb yog tib txoj hauv kev los yeej kev lag luam los ntawm kev tsim cov khoom siv thev naus laus zis, muaj txiaj ntsig zoo ntxiv cov khoom siv hluav taws xob mining.Nyob rau tib lub sijhawm, hais txog cov txiaj ntsig ntawm kev sib raug zoo, tsuas yog los ntawm kev tsim kho thev naus laus zis thiab kev txhim kho thee mining mechanization, electrification thiab automation tuaj yeem txhawb kev tsim kom muaj kev nyab xeeb tiag tiag niaj hnub mine.
Kev tsim kho thev naus laus zis yog lub hauv paus tseem ceeb rau kev ntsuas seb lub lag luam puas siab heev, seb nws puas muaj kev sib tw ua lag luam, thiab seb nws puas tuaj yeem ua ntej ntawm cov neeg sib tw.Nrog rau txoj kev loj hlob sai ntawm kuv lub teb chaws cov khoom siv hluav taws xob mining kev lag luam, daim ntawv thov thiab kev tshawb fawb thiab kev loj hlob ntawm cov tub ntxhais cov cuab yeej siv technology uas muaj feem xyuam rau nws yuav muaj tseeb los ua lub hom phiaj ntawm cov neeg lag luam hauv kev lag luam.Nkag siab txog kev tshawb fawb thiab kev loj hlob tiam sis, cov txheej txheem cov cuab yeej siv, kev siv thev naus laus zis thiab cov qauv ntawm cov thev naus laus zis tseem ceeb ntawm cov khoom siv hluav taws xob hauv tsev thiab txawv teb chaws mining yog qhov tseem ceeb rau cov tuam txhab los txhim kho cov khoom specifications thiab txhim kho kev lag luam kev sib tw.Txawm hais tias cov khoom tshiab xws li siab thiab qis voltage soft starters, siab thiab tsis tshua muaj voltage ua ke keyboards, thiab zaus conversion ceev tswj cov cuab yeej yog tas li tsim, txoj kev loj hlob ntawm cov khoom no tseem muaj ntau yam kev txwv.Ntau yam tseem ceeb ntawm cov khoom tawg-pov thawj hluav taws xob tseem cia siab rau kev siv tshuab txawv teb chaws.Tseem muaj qhov sib txawv loj ntawm qib kev tsim khoom ntawm cov khoom tseem ceeb no thiab cov khoom txawv teb chaws zoo sib xws.Kev tsim kho thev naus laus zis feem ntau dhau los ntawm peb theem los ntawm kev tshawb fawb thawj zaug thiab kev loj hlob mus rau kev loj hlob: lub sij hawm taw qhia, lub sij hawm loj hlob thiab lub sij hawm kom loj hlob.Thaum lub sij hawm taw qhia, kev txhim kho thev naus laus zis qeeb heev, thiab nws feem ntau siv sijhawm ntev los ua txhaum;Piv txwv li, txog 50% ntawm peb theem tam sim no ntawm zaus hloov pauv ceev tswj cov cuab yeej, txog 50% ntawm cov tuam txhab mining tawg-pov thawj ncaj qha yuav khoom txawv teb chaws sib dhos ntau lawm;40% Ntawm cov tuam txhab txais kev siv tshuab hauv tsev los nqus thiab siv, thiab tsuas yog li 10% ntawm cov tuam txhab tuaj yeem tsim thiab tsim tawm ntawm nws tus kheej.Nyob rau tib lub sijhawm, kev tshawb fawb ntawm EMC kev ua tau zoo ntawm lub inverter tseem nyob rau theem pib, tab sis theem no ua rau peb muaj kev sib tw.Yuav ua li cas kov yeej cov kev cuam tshuam ntawm inverter tso zis harmonics ntawm lub hwj chim mov thiab saib xyuas cov cuab yeej ntawm lub hwj chim daim phiaj tau dhau los ua lub hom phiaj ntawm ntau lub tuam txhab.Nws tseem yuav dhau los ua theem tom ntej ntawm kev txhim kho cov hom phiaj.Thaum cov thev naus laus zis thev naus laus zis nyob rau theem kev loj hlob, thev naus laus zis txhim kho sai, thiab kev ua haujlwm tau zoo dua qub;Piv txwv li, tam sim no zaus hloov dua siab tshiab traction shearer, siv cov yam ntxwv ntawm zaus hloov dua siab tshiab tsis tu ncua lub hwj chim ceev tswj thiab PLC centralized tswj, yog nce siv nyob rau hauv daim ntawv thov ntawm lub shearer Mature, txhim kho kev ua hauj lwm efficiency thiab kev cia siab ntawm cov shearer, thiab yeej hloov lub hydraulic traction technology;Lwm qhov piv txwv yog hydraulic winch, uas sib txuas hluav taws xob, roj, thiab roj.Kev ua haujlwm yog qhov nyuaj, rov qab, nrov nrov, thiab kev saib xyuas kev ua haujlwm kuj loj., Tom qab tau txais kev siv tshuab hluav taws xob tawg-pov thawj zaus, cov txheej txheem ntau lawm tau hloov pauv tag nrho, thiab nws tau lees paub los ntawm cov neeg siv khoom lag luam thee.Thaum cov thev naus laus zis tshiab nkag mus rau lub sijhawm paub tab, thev naus laus zis kuj ruaj khov, tsis muaj kev hloov pauv loj, thiab kev ua haujlwm thev naus laus zis tau cuam tshuam los ntawm kev txhim kho ib nrab.Piv txwv li, tam sim no qhov siab thiab qis voltage ua ke hloov pauv yog nyob ze rau qib txawv teb chaws uas twb muaj lawm.Daim ntawv thov ntawm cov cuab yeej siv hluav taws xob xws li PLC, DSP, thiab fieldbus muab kev txhawb nqa rau kev ua haujlwm ruaj khov ntawm kev sib txuas ua ke, thiab cov khoom siv hluav taws xob cuam tshuam tau nkag mus rau hauv kev tsim khoom.Chav tsev qauv ntawm kev sib txuas ua ke kuj tau ua kom muaj kev vam meej.Tsuas yog los ntawm kev lees paub peb txoj kev txhim kho ntawm kev tsim kho thev naus laus zis tuaj yeem ua tiav qhov kev txhim kho cov tswv yim ntawm peb cov khoom.
Ntau lub tuam txhab kuj lees paub qhov tsim nyog ntawm kev tsim kho thev naus laus zis, tab sis tau tawm tsam kom nrhiav tau qhov kev ua tiav.Raws li cov khoom lag luam tam sim no, peb lub hom phiaj thev naus laus zis tshiab nyob qhov twg?Qhov tseeb, yav dhau los pib, hloov pauv, thiab lub thawv hluav taws xob tswj tau tsuas yog tiv thaiv los ntawm cov khoom siv sib cais, uas muaj qhov tsis zoo ntawm cov khoom tsis ruaj khov thiab cov khoom loj.Kev siv cov tshuab monolithic ntawm tus tiv thaiv coj kev ua haujlwm yooj yim thiab kev ua haujlwm.Qhov zoo ntawm kev ruaj ntseg;kev sib koom ua haujlwm ntawm tus txiv neej-tshuab interface ua rau kev ua haujlwm kom pom tseeb, thiab kev ua txhaum lub cim xeeb muab lub hauv paus rau cov tuam txhab thee mine los txheeb xyuas cov teeb meem.Kev tsim kho thev naus laus zis kuj tseem tsom mus rau kev txhim kho txuas ntxiv ntawm nws tus kheej cov khoom lag luam.Piv txwv li, ib lub tuam txhab GM series thee shearer rho tawm hloov pauv muaj kev lag luam feem ntau tshaj 90%, thiab nws cov kev ua haujlwm ruaj khov tau lees paub los ntawm tib lub lag luam;ib lub tuam txhab miniaturized flameproof thiab intrinsically muaj kev nyab xeeb dej theem tswj oob khab kuj yeej kev lag luam Thiab kev lees paub ntawm thee enterprise cov neeg siv.Ntau qhov kev vam meej ntawm kev lag luam yog tsim nyog ntawm peb txoj kev kawm thiab kev siv.Cov tuam txhab lag luam yuav tsum hloov lawv qhov muag tsis pom kev ua raws li qhov sib txawv thiab nrhiav kev ua tiav hauv cov khoom, tsuas yog xav txog qhov kev pab cuam, thiab tsis quav ntsej txog kev txhim kho kev ua tau zoo ntawm lawv tus kheej tshwj xeeb.Kev tsim kho thev naus laus zis thiab kev ywj pheej ntawm cov tswv cuab kev txawj ntse kuj yog qhov lav rau kev txhim kho ntawm peb cov tuam txhab mining tawg-pov thawj.
Grasping txoj kev loj hlob qauv ntawm cov khoom kuj tuav lub lag luam.Lub hom phiaj ntawm txoj kev loj hlob ntawm cov khoom siv mining, peb lub ntsiab lus hauv qab no tau muab tso rau hauv cov ntsiab lus ntawm cov khoom siv hluav taws xob tawg-pov thawj mining:
Ua ntej, qhov yooj yim kev tshawb fawb ntawm cov khoom siv hluav taws xob
kuv lub tebchaws tau pib siv lub tshuab nqus tsev vacuum thaum xyoo 1980s.Tam sim no, mine tawg-pov thawj lub tshuab nqus tsev hloov pauv tau siv dav hauv cov mines hauv av.Kev siv lub tshuab nqus tsev vacuum tau ua lub luag haujlwm zoo hauv kev nyab xeeb fais fab hauv cov mines.Piv txwv li, cov khoom tawg-pov thawj lub tshuab nqus tsev electromagnetic pib cov khoom siv rau mines muaj lub zog tawg qhov kawg, uas yog tsim rau nquag pib ntawm cov motors hauv av thiab kev saib xyuas tsawg;mine explosion-proof khoom Lub sij hawm tawg tag nrho ntawm lub tshuab nqus tsev pub hloov yog me me, thiab ua ke nrog kev tiv thaiv sai sai, nws txhim kho kev nyab xeeb ntawm kev tiv thaiv kev poob siab thiab tiv thaiv roj tawg.Qhov kev thov rau lub tshuab nqus tsev contactors thiab lub tshuab nqus tsev vacuum breakers yog qhov loj heev, tab sis qhov zoo ntawm lub tshuab nqus tsev hauv kev lag luam tam sim no tsis sib xws.Ntau cov txheej txheem tsim khoom tseem yog raws li thaum ntxov xyoo 1980s thiab tseem loj heev piv nrog cov txheej txheem txawv teb chaws.qhov sib txawv.Nyob rau hauv daim ntawv thov ntawm lub tshuab nqus tsev raj, kuj muaj kev cuam tshuam ntawm kev khiav hauj lwm overvoltage thiab guarantee ntawm lub nqus tsev vacuum.Kev txo qis ntawm lub tshuab nqus tsev tuaj yeem yooj yim ua rau muaj kev sib tsoo hauv qhov dej, cuam tshuam rau kev tsim khoom thiab kev sib tsoo.Qee lub tuam txhab kuj tau pib mob siab rau lawv tus kheej rau kev tshawb fawb ntawm lub tshuab nqus tsev cov khoom siv hluav taws xob, thiab Kev tshawb fawb txog kev tiv thaiv huab cua tau ua tiav hauv kev tiv thaiv huab cua thiab lub tshuab nqus tsev adhesion tiv thaiv txoj kev.Qhov no yog yav tom ntej
Muab kev lees paub rau kev ua haujlwm nyab xeeb ntawm cov khoom siv hluav taws xob hauv av.Nrog rau kev txhim kho txuas ntxiv ntawm kev siv tshuab hluav taws xob, kev siv cov khoom siv hluav taws xob hluav taws xob los hloov lub tshuab nqus tsev kom paub txog qhov pib thiab nres tswj lub cev muaj zog yuav yog txoj kev txhim kho.Nws tau raug siv los tswj kev tiv thaiv kev tiv thaiv ntawm cov thee hluav taws xob xyaum, xws li kev tsis sib cuag ntawm thyristors.Tswj, nce kev pab cuam lub neej, muaj kev nyab xeeb thiab txhim khu kev qha.Daim ntawv thov ntawm high-power SCR nyob rau hauv lub oob khab kuj tau hloov qhov kev ua tau zoo ntawm cov tsoos starter.Thaum siv cov khoom siv hluav taws xob siv hluav taws xob muab qhov tseem ceeb tshiab rau kev ua haujlwm thiab kev ntseeg siab ntawm cov khoom siv hluav taws xob tawg, nws kuj tseem coj cov teeb meem tshiab rau kev tawg-pov thawj thiab kev nyab xeeb kev cai ntawm cov khoom.
Thib ob, kev tshawb fawb txog kev xaiv ntawm cov khoom siv hluav taws xob tsawg-voltage pub hloov
Kev tiv thaiv cov dej xau yog ib qho ntawm peb qhov kev tiv thaiv tseem ceeb rau cov khoom siv hluav taws xob hauv av hauv cov mines, thiab kev ntseeg siab ntawm nws cov kev tiv thaiv cuam tshuam rau kev tsim cov thee mine kev nyab xeeb.Tam sim no xaiv qhov kev tiv thaiv kev tiv thaiv ntawm cov hluav taws xob tsawg-voltage feeder hloov yog tseem ua raws li kev tiv thaiv hom zero-sequence voltage thiab xoom-sequence tam sim no;Tsis tas li ntawd, ib qho DC sab nraud yog siv los saib xyuas cov rwb thaiv tsev ntawm cov khoom siv hluav taws xob txuas ntxiv.Vim qhov ntev ntawm lub zog hluav taws xob network thiab daim ntawv thov ntawm cov cables shielded, nrog rau kev siv cov khoom siv hluav taws xob hluav taws xob xws li cov zaus hloov pauv, cov khoom siv hluav taws xob hauv av yog qhov nyuaj.Muaj ntau tus cwj pwm coj txawv txawv hauv kev xaiv kev tiv thaiv kev tiv thaiv thiab qhov tsis paub meej ntawm kev faib cov peev txheej.Cov kev xav tau rau kev tiv thaiv dej xau tau muab tso rau pem hauv ntej.Siv cov thev naus laus zis tau txais txiaj ntsig zoo tshaj plaws, yuav ua li cas txheeb xyuas qhov xwm txheej ntawm kev faib tawm hauv lub qhov dej, kom ua tiav cov kev xaiv raug xaiv thiab txiav tawm cov ceg tsis raug cai tsis cuam tshuam rau lwm cov ceg ua haujlwm, thiab kom ntseeg tau tias cov khoom siv hluav taws xob muaj kev ruaj ntseg hauv av kuj yog ib qho tshiab. lub ntsiab lus uas yuav tsum tau kawm sai sai.
Thib peb, kev txhim kho mining AC inverter khoom
Vim muaj kev nce qib thiab kev loj hlob ntawm kev tshawb fawb thiab thev naus laus zis, kev siv cov khoom siv hluav taws xob muaj zog hauv cov mines hauv av tau tsim sai heev.Ntawm lawv, AC qhov sib txawv ntawm cov khoom siv ceev ceev tswj tau qhov zoo ntawm kev ua haujlwm siab, qis qis, thiab kev tswj xyuas kev ua haujlwm zoo, uas tuaj yeem txhim kho cov txheej txheem ntau lawm.Nrog rau cov xim ntawm cov thee ntau lawm kev lag luam, lub mine zaus conversion ceev tswj ntaus ntawv yog tsuas yog siv rau ceev tswj ntawm txog 100kW, xws li thee mining electromechanical traction qhov chaw.Feem ntau, cov theem pem hauv ntej muaj qhov tshwj xeeb transformer los muab lub zog, uas muaj kev cuam tshuam me ntsis ntawm daim phiaj fais fab.Txawm li cas los xij, raws li kev siv tshuab hluav taws xob txuas ntxiv mus rau kev paub tab, txij li kev siv hluav taws xob traction shearers nyob rau xyoo 1980s, thee mine ntau lawm cov cuab yeej xws li lub tshuab ua pa, winches, hoists, cua compressors thiab lwm yam khoom siv tshuab tau pib siv zaus hloov pauv ceev tswj kev siv tshuab. .Tsis tsuas yog hloov cov txheej txheem ntau lawm, tab sis kuj tseem yog embodied nyob rau hauv high efficiency thiab lub zog txuag.Piv txwv li, lub ntsiab kiv cua ntawm ib lub mine raug xaiv raws li qhov siab tshaj plaws huab cua ntim yuav tsum tau ntawm mine qhov kev pab cuam lub neej.Los ntawm kev tsim kho ntawm cov ncej mus rau kev tsim khoom kom txog rau thaum lub mine raug tshem tawm, cov cua ntim yuav tsum tau nyob rau hauv txhua lub sij hawm sib txawv, thiab qhov sib txawv yog loj heev.Kev siv cov cuab yeej hloov kho ntawm huab cua ntim ua rau muaj hluav taws xob pov tseg ntau.Cov kiv cua txuag hluav taws xob los ntawm kev siv lub tshuab hloov pauv zaus.Lwm qhov piv txwv yog tias cov kiv cua hauv zos hauv lub ntsej muag mining tau teeb tsa hauv ntau qhov chaw thiab khiav mus ntev, uas yog cov neeg siv khoom siv hluav taws xob loj.Vim qhov kev nthuav dav txuas ntxiv ntawm cov thee mining, cov huab cua ntim yuav tsum tau siv sijhawm ntev yog tsawg dua li qhov cua.Cov huab cua muaj peev xwm ntawm lub tshuab, nyob rau hauv qhov kev pom ntawm qhov teeb meem tam sim no ntawm hom loj nees-drawn trolley, lub zog-txuag nyhuv ntawm kev siv zaus hloov pauv ceev tswj kev siv tshuab kuj pom tseeb heev.Vim lub high efficiency ntawm lub zaus converter thiab zoo ceev kev tswj kev ua tau zoo, nws muaj peev xwm siv fais braking thiab stepless ceev tswj kom txuag tau lub zog.Nws yog ib qho kev hloov tsis tau los siv cov tshuab hloov pauv ntau zaus hauv cov mines.Tab sis tam sim no, tsis muaj kev txhim kho cov khoom lag luam lossis kev sim thev naus laus zis tuaj yeem ua raws li cov kev xav tau ntawm kev tsim khoom.
Raws li daim ntawv thov kev paub ntawm av zaus hloov pauv ceev tswj cov cuab yeej, nws yog ib qho tsim nyog yuav tsum ua kom zoo siv cov zaus hloov pauv ceev tswj cov cuab yeej, thiab cov khoom siv hluav taws xob, zaus hloov lub cev muaj zog, thiab cov tshuab tsim khoom yuav tsum tau ua ke nrog cov cuab yeej siv ntau lawm. system los kawm, thiab cov kev tiv thaiv tsim nyog yuav tsum raug coj mus rau qhov sib haum xeeb ntawm daim phiaj hluav taws xob.Txhawm rau hloov mus rau kev txhim kho cov thee mine zaus hloov hluav taws xob thev naus laus zis, tshawb fawb txog kev ua haujlwm ntawm cov khoom siv hluav taws xob ntau zaus hloov pauv rau mines, kev tshawb fawb ntawm zaus converter EMC thiab cov txiaj ntsig ntawm kev ntsuas yoj yoj thiab lwm yam teeb meem, thiab muab kev tshaj lij. thev naus laus zis rau kev tshawb fawb txog kev tshawb fawb, tsim thiab tsim khoom ntawm mine zaus converters.Lub platform xeem yog imminent.
Yuav ua li cas txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau txhawm rau nws, nws yuav tsum tau siv cov thee mine "ntsuab" thiab txo cov kev puas tsuaj rau cov thee mine ntau lawm tau dhau los ua ib lub ntsiab lus tseem ceeb rau lub chaw kuaj xyuas nyob rau theem tom ntej.
kuv lub teb chaws yog lub ntiaj teb cov chaw tsim hluav taws xob loj tshaj plaws, thiab cov thee yog kuv lub teb chaws lub zog loj tshaj plaws.Lub hom phiaj ntawm txoj kev loj hlob ntawm peb lub ntsiab lus saum toj no, kev txhim kho thee mining mechanization thiab electrification los ntawm kev siv thev naus laus zis yog qhov tseem ceeb heev rau kev hloov kho tshiab ntawm cov mines.Txhawm rau ua kom tau raws li cov kev xav tau ntawm kev lag luam thev naus laus zis tshiab thiab kev txhim kho, peb lub koom haum sim yuav txuas ntxiv txhim kho nws lub peev xwm thiab muab cov txheej txheem kev sim siab thiab cov qauv kev sim.Hauv kev teb rau cov kev xav tau ntawm kev txhim kho thev naus laus zis, National Safety Production Shanghai Mining Equipment Inspection Center kuj tseem txhim kho nws cov peev xwm tshuaj xyuas thiab qib.Piv txwv li, qhov loj-loj tawg-pov thawj ntsuas tank ntawm 3.4m tau suav nrog hauv txoj haujlwm npaj los hloov kho rau kev tshuaj xyuas cov khoom siv hluav taws xob loj hauv mining.Xav tau: Lub peev xwm tshuaj xyuas ntawm kuv qhov tawg-pov thawj inverters yuav raug nce mus rau theem ntawm 1000kW kom tau raws li qhov kev xav tau ntawm cov muaj peev xwm loj-voltage motors thiab high-voltage inverters.Peb lub tuam tsev kuaj xyuas yuav siv cov cuab yeej siv thev naus laus zis zoo tshaj plaws los pab txhawb kev sib pauv thiab kev koom tes nrog cov tuam txhab, thiab muab kev txhawb nqa rau kev tsim kho tshiab thiab kev tswj hwm kev nyab xeeb ntawm cov khoom tawg-pov thawj hluav taws xob mining.
Post lub sij hawm: Oct-14-2021