Unveiling the Process of Gold Extraction using Sodium Cyanide

I. Pib Qhia

Hauv kev lag luam khawb kub niaj hnub no , Sodium cyanide ua lub luag haujlwm tseem ceeb. Tsis zoo li cov txheej txheem khawb kub qub, cov txheej txheem khawb kub lag luam niaj hnub no tuaj yeem rho tawm kub ntawm cov pob zeb ores uas muaj cov kub tsawg heev, qee zaum me me li 0.005%, qhov twg kub tsis pom rau lub qhov muag liab qab. Sodium cyanide yog tus neeg sawv cev tseem ceeb hauv cov txheej txheem rho tawm nyuaj no, ua rau kev sib cais kub ntawm cov ores tau zoo. Tsab xov xwm no yuav tshawb nrhiav kom meej txog Sodium Cyanide siv li cas hauv kev khawb kub.

II. Lub hauv paus ntawm Sodium Cyanide

A. Chemical Properties

Sodium cyanide, nrog rau cov tshuaj NaCN, yog cov khoom dawb crystalline. Nws zoo li granules lossis hmoov thiab yooj yim deliquescence. Cov tshuaj no muaj ntxhiab tsw ntawm cov txiv almond iab. Hais txog kev yaj, nws yaj tau zoo heev hauv dej, thaum tsuas yog yaj me ntsis hauv ethanol. Chemically, sodium cyanide yog lub hauv paus muaj zog thiab ntsev kua qaub tsis muaj zog. Nws cov kua dej hydrolyzes los tsim hydrocyanic acid, ua rau cov tshuaj muaj zog alkaline. Nco ntsoov, sodium cyanide muaj tshuaj lom heev. Txawm tias me me, txawm tias los ntawm kev kov daim tawv nqaij, kev ua pa, lossis kev noj, tuaj yeem ua rau lom hnyav thiab tej zaum yuav tuag taus. Nws muaj nws cov nyhuv tuag taus los ntawm kev tso tawm cyanide ions (CN-) uas muaj kev sib raug zoo dua rau cov hlau ions dua li oxygen. Qhov no cuam tshuam cov txheej txheem oxidative ib txwm ntawm cov cell, thaum kawg ua rau cell asphyxia thiab cov ntaub so ntswg hypoxia.

B. Kev lag luam tseem ceeb

Tshaj nws lub luag haujlwm hauv kev khawb kub, sodium cyanide tuav qhov tseem ceeb hauv ntau yam kev lag luam. Hauv kev lag luam electroplating, nws ua haujlwm tseem ceeb rau plating tooj liab, nyiaj, cadmium, thiab zinc. Nws pab txo cov anodic polarization, kom ntseeg tau qhov kev sib cais ntawm cov anode, stabilizing cov txheej txheem plating, thiab txhim kho cov cathodic polarization kom tau txais cov txheej txheem zoo thiab cov txheej txheem plating zoo. Hauv metallurgy, nws yog dav siv nyob rau hauv extraction ntawm precious hlau xws li kub thiab nyiaj. Ntxiv mus, nws yog ib qho tseem ceeb raw khoom nyob rau hauv kev lag luam tshuaj rau kev tsim ntau yam inorganic cyanides thiab tsim hydrocyanic acid. Nws kuj tseem ua lub luag haujlwm tseem ceeb hauv kev tsim cov khoom siv organic xws li iav organic, ntau yam khoom siv hluavtaws, nitrile roj hmab, thiab hluavtaws fiber ntau copolymer. Nyob rau hauv kev lag luam dyeing, nws yog siv nyob rau hauv zus tau tej cov cyanuric chloride, ib qho tseem ceeb nruab nrab rau reactive dyes thiab ib tug precursor rau whitening agents. Tsis tas li ntawd, kev lag luam kws tshuaj siv sodium cyanide hauv kev sib txuas ntawm cov tshuaj xws li cyanoacetic acid methyl ester thiab diethyl malonate. Zuag qhia tag nrho, sodium cyanide's versatility thiab reactivity ua rau nws ib tug indispensable tshuaj nyob rau hauv niaj hnub kev lag luam txheej txheem.

III. Cov Txheej Txheem Kub Kub nrog Sodium Cyanide

A. Ore Kev Npaj

Kauj ruam thawj zaug hauv kev siv sodium cyanide rau kev rho tawm kub yog npaj cov hlau. Cov hlau loj loj uas muaj kub raug tsoo ua tej daim me me siv cov tshuab tsoo hnyav. Qhov kev tsoo thawj zaug no txo ​​qhov loj ntawm cov hlau kom yooj yim dua, feem ntau yog li ntawm 150-300 millimeters. Tom qab ntawd, cov hlau raug tsoo tom qab kev tsoo thib ob, feem ntau nrog cov tshuab tsoo cone lossis cov tshuab tsoo cuam tshuam, txo qhov loj ntawm cov khoom me me mus rau li ntawm 20-50 millimeters. Tom qab ntawd, cov hlau raug tsoo ua hmoov zoo los ntawm cov tshuab sib tsoo pob lossis cov tshuab sib tsoo pas nrig, kom ntseeg tau tias feem ntau ntawm cov khoom me me tsawg dua 0.074 millimeters. Qhov kev sib tsoo zoo no yog qhov tseem ceeb vim nws ua rau thaj chaw ntawm cov hlau nce ntxiv, ua rau muaj kev sib cuag zoo dua thiab kev cuam tshuam nrog cov tshuaj cyanide hauv cov txheej txheem leaching tom qab. Tsis tas li ntawd, cov hlau tuaj yeem dhau los ntawm cov txheej txheem tshuaj ntsuam kom cais cov khoom me me sib txawv, ua rau muaj kev tswj hwm zoo dua ntawm kev kho tshuaj thiab ua kom muaj txiaj ntsig zoo tshaj plaws ntawm kev rho tawm.

B. Txheej txheem Leaching

Thaum cov ore npaj tau zoo, nws nkag mus rau theem leaching, uas yog lub plawv ntawm cov txheej txheem rho tawm kub nrog sodium cyanide. Cov hmoov ore yog tov nrog ib tug ua tib zoo formulated cyanide tov, feem ntau nrog ib tug sodium cyanide concentration li ntawm 0.05% mus rau 0.1%. Nyob rau theem no, cov tshuaj tiv thaiv tshuaj tshwm sim qhov twg cov kub hauv cov ore reacts nrog cov cyanide ions (CN-) nyob rau hauv lub xub ntiag ntawm oxygen. Tag nrho cov tshuaj tiv thaiv tuaj yeem sawv cev los ntawm qhov sib npaug: 4Au + 8NaCN + O₂ + 2H₂O → 4Na[Au(CN)₂] + 4NaOH. Ntawm no, cov atoms kub tsim ib qho yooj yim soluble nrog cov cyanide ions, tsim sodium kub cyanide (Na[Au(CN)₂]), uas dissolves nyob rau hauv cov tshuaj. Cov txheej txheem leaching xav tau kev tswj hwm nruj ntawm ntau yam tsis muaj. Cov pH ntawm cov tshuaj yog khaws cia nyob ib ncig ntawm 10-11 los xyuas kom meej qhov ruaj khov ntawm cyanide thiab tiv thaiv kev tsim cov tshuaj lom hydrogen cyanide gas. Kub kuj ua lub luag haujlwm tseem ceeb; Feem ntau, nws khaws cia nyob rau hauv thaj tsam ntawm 20-30 ° C. Qhov kub qis dhau qeeb qeeb ntawm cov tshuaj tiv thaiv tus nqi, thaum tshav kub ntau dhau tuaj yeem ua rau evaporation sai ntawm cov tshuaj thiab cov cuab yeej muaj peev xwm corrosion. Txaus agitation thiab aeration yog tsis tu ncua muab los xyuas kom meej kev sib xyaw ntawm cov ore thiab cov tshuaj cyanide, txhawb kev kub dissolution.

C. Ntug dej nag

Tom qab cov txheej txheem leaching, cov kub tam sim no nyob rau hauv daim ntawv ntawm soluble kub cyanide complexes nyob rau hauv cov tshuaj. Yuav kom rov qab tau cov kub, ib theem nag lossis daus yog nqa tawm. Qhov no feem ntau suav nrog ntxiv zinc hmoov lossis cov pa roj carbon activated rau cov tshuaj. Thaum siv zinc hmoov, muaj kev hloov pauv hloov pauv. Cov zinc, ua ntau reactive tshaj kub, displaces cov kub los ntawm kub cyanide complex. Cov tshuaj tiv thaiv tuaj yeem qhia tau tias: 2Na[Au(CN)₂] + Zn → Na₂[Zn(CN)₄] + 2Au. Cov atoms kub yog tom qab ntawd txo mus rau lawv daim ntawv hlau thiab precipitate tawm ntawm cov tshuaj. Yog tias cov pa roj carbon activated ua haujlwm, nws qhov chaw siab saum npoo thiab adsorption zog tuaj rau hauv kev ua si. Cov kub cyanide complexes adsorb mus rau saum npoo ntawm cov pa roj carbon activated, zoo cais cov kub ntawm cov tshuaj. Lub loaded activated carbon yog tom qab ntawd ua tiav ntxiv kom rov qab tau cov adsorbed kub. Thaum cov nag lossis daus tiav lawm, cov slurry tshwm sim yog lim los yog centrifuged cais cov khoom kub precipitate los ntawm cov kua seem, uas tej zaum yuav muaj residual cyanide thiab lwm yam impurities.

D. Cov txheej txheem kho kom zoo

Cov kub tau los ntawm cov nag lossis daus tseem muaj qee qhov impurities thiab yuav tsum tau ua kom zoo kom ua tiav qhov siab purity xav tau hauv khw. Cov txheej txheem refining feem ntau pib nrog smelting, qhov twg kub precipitate yog rhuab mus rau ib tug kub kub nyob rau hauv lub cub tawg. Qhov no melts cov kub, cia denser impurities mus rau hauv qab thaum lub molten kub yuav skimmed tawm los yog poured rau hauv pwm. Tom qab ntawd, electrolysis tuaj yeem ua haujlwm rau kev ua kom huv ntxiv. Nyob rau hauv ib tug electrolytic cell, lub impure kub yog ua lub anode, thiab ib tug nyias daim ntawv ntawm ntshiab kub ua lub cathode. Thaum cov hluav taws xob tam sim no dhau los ntawm lub xov tooj ntawm tes, cov kub ions los ntawm lub anode tsiv mus rau cathode thiab tso nyiaj ua cov kub ntshiab, tawm hauv qab cov impurities seem ntawm lub anode. Los ntawm cov kauj ruam ua kom zoo dua no, cov kub tuaj yeem ncav cuag qib purity txog li 99.99%, ua tau raws li cov qauv rau ntau yam kev lag luam, kev tsim cov hniav nyiaj hniav kub, thiab kev siv peev.

IV. Daim ntawv thov kev nyab xeeb thiab Environmental Considerationsment

A. Kev Nyab Xeeb Kev Ua Haujlwm

Muab cov tshuaj toxicity ntawm sodium cyanide, kom ntseeg tau tias kev nyab xeeb ntawm cov neeg ua haujlwm yog qhov tseem ceeb tshaj plaws. Cov neeg ua haujlwm koom nrog hauv cov txheej txheem kub mining siv sodium cyanide yuav tsum tau muab kev cob qhia txog kev nyab xeeb. Lawv yuav tsum ua tib zoo saib xyuas cov tshuaj, nkag siab txog nws cov kev phom sij, thiab paub txog cov txheej txheem xwm txheej ceev. Cov cuab yeej tiv thaiv tus kheej (PPE) tsis tuaj yeem sib tham. Cov neeg ua haujlwm yuav tsum hnav cov hnab looj tes uas tsis tuaj yeem tiv thaiv kev sib cuag ntawm daim tawv nqaij, tsom iav los tiv thaiv lawv lub qhov muag, thiab lub tshuab ua pa kom tsis txhob nqus cov pa uas muaj cyanide tso tawm. Ntxiv rau, cov txheej txheem kev nyab xeeb nruj yuav tsum nyob hauv qhov chaw. Piv txwv li, cov chaw ua hauj lwm yuav tsum tau ua kom zoo-ventilated kom txo tau cov concentration ntawm tej huab cua cyanide. Cov neeg ua haujlwm tseem yuav tsum tau txwv tsis pub noj, haus, lossis haus luam yeeb hauv thaj chaw uas muaj sodium cyanide los tiv thaiv kev noj tsis zoo. Kev kuaj mob tsis tu ncua yuav tsum yog qhov yuav tsum tau saib xyuas kev noj qab haus huv ntawm cov neeg ua haujlwm, tshwj xeeb tshaj yog cov neeg siv tshuaj ncaj qha, txhawm rau txheeb xyuas cov tsos mob ntxov ntawm cyanide raug.

B. Kev cuam tshuam ib puag ncig

Kev siv sodium cyanide hauv kev khawb kub kuj ua rau muaj kev txhawj xeeb txog ib puag ncig. Tom qab cov txheej txheem rho tawm kub, cov khoom pov tseg seem, hu ua Cyanide tailings , muaj cov cyanide seem. Yog tias tsis tswj hwm kom zoo, cov tailings no tuaj yeem ua rau muaj kev hem thawj loj rau ib puag ncig. Cyanide tuaj yeem nkag mus rau hauv av thiab dej hauv av, ua rau cov dej tsis huv thiab ua rau cov tsiaj txhu hauv dej puas tsuaj. Hauv cov dej saum npoo av, txawm tias me me ntawm cyanide tuaj yeem cuam tshuam kev sib npaug ntawm ecological, ua rau cov ntses tuag thiab lwm yam kev cuam tshuam tsis zoo rau kev muaj ntau haiv neeg. Txhawm rau txo cov kev pheej hmoo ib puag ncig no, cov tuam txhab khawb av yuav tsum siv cov tswv yim tswj hwm ib puag ncig zoo. Ib txoj hauv kev yog kho cov cyanide tailings kom txo cov ntsiab lus cyanide mus rau qib nyab xeeb. Qhov no tuaj yeem cuam tshuam nrog cov txheej txheem kho tshuaj, xws li oxidation lossis nag lossis daus, los hloov cov tshuaj lom cyanide mus rau hauv cov tshuaj uas tsis muaj kev phom sij. Lwm qhov kev ntsuas tseem ceeb yog kev pov tseg thiab kev tswj hwm cov tailings kho kom zoo. Kev ruaj ntseg ntawm cov chaw pov tseg lossis cov pas dej tailings nrog cov liners tsim nyog tuaj yeem tiv thaiv kev xau ntawm cov tshuaj lom seem mus rau hauv ib puag ncig. Tsis tas li ntawd, kev saib xyuas tas li ntawm ib puag ncig, suav nrog cov dej zoo thiab cov av, yog qhov tseem ceeb los nrhiav pom txhua qhov kev puas tsuaj ib puag ncig thaum ntxov thiab ua qhov kev kho kom raug sai.

V. Xaus

Sodium cyanide yog ib yam tshuaj tseem ceeb hauv kev khawb kub niaj hnub no, ua rau muaj peev xwm rho tau kub los ntawm cov pob zeb uas muaj cov kub tsawg. Nws tau yog lub hauv paus tseem ceeb ntawm kev lag luam khawb kub tau ntau xyoo, pab txhawb kev tsim kub uas siv roj rau ntau yam lag luam, los ntawm kev ua hniav nyiaj hniav kub mus rau kev siv thev naus laus zis siab. Txawm li cas los xij, nws siv xav tau kev saib xyuas siab tshaj plaws rau kev nyab xeeb thiab kev tiv thaiv ib puag ncig. Cov tuam txhab khawb yuav tsum nqis peev rau cov khoom siv kev nyab xeeb zoo tshaj plaws, muab kev cob qhia rau cov neeg ua haujlwm, thiab siv cov txheej txheem kev nyab xeeb nruj kom tiv thaiv lub neej. Tib lub sijhawm, lawv muaj lub luag haujlwm kev coj ncaj ncees thiab kev cai lij choj los tswj hwm qhov cuam tshuam rau ib puag ncig, kho cov tailings cyanide kom raug thiab saib xyuas lub ecosystem kom tiv thaiv kev puas tsuaj mus sij hawm ntev. Thaum thev naus laus zis nce qib, kev tshawb fawb txog kev nyab xeeb dua thiab zoo dua rau ib puag ncig rau sodium cyanide yuav tsum txuas ntxiv mus. Tsuas yog los ntawm kev sib npaug ntawm kev rho tawm kub zoo, kev nyab xeeb ntawm cov neeg ua haujlwm, thiab kev saib xyuas ib puag ncig tuaj yeem ua rau kev lag luam khawb kub vam meej mus ntev yav tom ntej.