Ua wehewehe ʻia ka hoʻohana ʻana o ka sodium cyanide i ke gula

I ke kaʻina ʻana o ke gula mai nā pūhui cyanide, ʻO Sodium cyanide ʻai ʻia ma nā ʻano like ʻole. ʻO ka sodium cyanide ka mea maʻamau i hoʻohana ʻia mea leaching agent i ke gula unuhi, a theoretically, wale 0.5 grams o ʻO ka sodium Cyanide pono e hookahe i 1 gram gula. Eia nō naʻe, i ka hapa nui o nā mea kanu cyanidation gula, ʻoi aku ka kiʻekiʻe o ka hoʻohana maoli ʻana o ka cyanide, ʻoi aku ka nui o nā helu theoretical e 50 a 100 mau manawa.

ʻO nā kumu nui e hāpai ana i ka hoʻohana nui ʻana o ka cyanide i ka kaʻina hana cyanidation gula puke:

1. ʻO ka hoʻohana ʻana i ka Cyanide i ke kaʻina hoʻopau gula

Ua hoʻohana ʻia nā mea kanu cyanide ka sodium cyanide e hoʻoheheʻe i ke gula mai loko mai o ka ʻeleʻele i mea e loaʻa ai ke gula mai ka leachate. ʻO nā hopena kemika e pili ana penei:

• [2Au+4NaCN+O2+2H2O→2Na[Au(CN)2]+2NaOH+H2O2]

• [ 2Au+4NaCN+H2O2→2Na[Au(CN)2]+2NaOH]

Mai nā hopena electrochemical, ʻike ʻia ʻo ka hoʻopau ʻana i ka 1 gram gula e pono ai ka ʻai ʻana o 0.92 grams o ka sodium cyanide.

2. ʻO ka hoʻohana ʻana i ka Cyanide i nā hana me nā metala kumu pili

(1) Loaʻa i kekahi o nā ʻaila gula nā minerale pili e like me pyrite, magnetite, chalcopyrite, nā minerala sulfate, hydroxides, a me nā oxides. I ka wā o ka paʻi ʻana, hana ʻia ka pauka hao, e hana mālie me ka sodium cyanide, e hoʻonui ana ʻai cyanide. ʻO nā hopena penei:

• [ FeS2+NaCN→FeS+NaCNS]

• [ Fe(OH)2+2NaCN→Fe(CN)2+2NaOH]

• [ Fe+6NaCN+2H2O→Na4Fe(CN)6+2NaOH+H2↑]

• [ S+NaCN→NaCNS]

(2) Inā loaʻa nā ʻano mineral keleawe like ʻole i loko o ka ʻai gula, e hana pū lākou me ka sodium cyanide e hana i nā paʻakikī cyanide keleawe, e ʻai ana i ka cyanide i ke kaʻina hana. ʻO nā hopena penei:

• [ 2CuSO4+4NaCN→Cu2(CN)2+2Na2SO4+(CN)2↑]

• [ 2Cu2S+4NaCN+2H2O+O2→Cu2(CN)2+Cu2(CNS)2+4NaOH]

Ma muli o ka hana ikaika o ka sodium cyanide me nā minela keleawe he nui, ma ke ʻano he 2.3 a i ka 3.4 grams o ka cyanide e hoʻoheheʻe i 1 gram o ke keleawe.

(3) Inā loaʻa ka sphalerite a i ʻole smithsonite i loko o ka ʻaila gula maoli, e hana pū lākou me ka sodium cyanide e hana i ka zinc cyanide a me nā carbonates. ʻO nā hopena penei:

• [ ZnS+4NaCN→Na2[Zn(CN)4]+Na2S]

• [ ZnCO3+4NaCN→Na2Zn(CN)4+Na2CO3]

(4) Inā loaʻa ka arsenopyrite, mercury, selenium, tellurium, a me nā mea ʻē aʻe, e hana pū lākou me ka sodium cyanide. Ke loaʻa nā pōhaku kalapona i loko o ke kino oka, ʻoi aku ka nui o ke kalapona organik, ʻoi aku ka ikaika o ka adsorption o ka cyanide, e ʻoi aku ka paʻakikī o ka leaching cyanide o ke gula.

3. Hydrolysis o Cyanides

I ka hoʻonā, cyanides e loaʻa i nā pae like ʻole o ka hydrolysis ma muli o ka pH, me ka nui o ka hydrogen cyanide i hana ʻia e pili ana i ka alkalinity o ka hopena. Hiki ke hōʻike ʻia ka hopena penei:

• [NaCN + H2O → NaOH + HCN↑]

• [CN⁻ + 2H2O → HCOO⁻ + NH3]

Ma hope o ka hydrolysis, hoʻohua ka ʻāpana o ka cyanide i ka hydrogen cyanide, aʻo kekahi ʻāpana e hoʻoheheʻe ʻia me ka oxidatively hydrolyzed, e hana mālie ana i ka waika formic a me ka amonia. Ma 100°C, CN⁻ nalowale 50%, a ma 130°C, lilo ia 85%.

I ke kaʻina hana cyanidation no ka ʻeli gula, ʻo ka hydrogen cyanide he kinoea ʻawaʻawa loa. Inā ʻaʻole mālama pono ʻia, hiki iā ia ke alakaʻi i ka hoʻohana nui ʻana o NaCN, hoʻonui i nā kumukūʻai hana, a me ka hoʻohaumia ʻana i ke kaiapuni, a me ka hoʻopilikia ʻana i ke olakino i nā mea hana. ʻOkoʻa ka nui o ka HCN me ka pH o ka hopena: ma ka pH 10.5. ʻo 6.1% wale nō o ka hydrogen cyanide i hana ʻia; ma ka pH 10. piʻi ia i 17%; ma ka pH 9.5. hiki i ka 39.2%; a ma ka pH 9.0. he 67.1%. No laila, i nā mea kanu gula CIP (Carbon-in-Pulp), hoʻololi maʻamau ka pH ma waena o 11 a me 12 e hoʻomalu i ka hydrolysis o nā cyanides.

4. ʻO ka oxidation o ka cyanide (CN-) e ka oxygen dissolved (O2)

No ka hoʻonui ʻana i ka helu hoʻoheheʻe ʻana o ke gula, pono e komo ʻo CN- a me O2 i ka hopena. Ma ka lumi wela a me ke kaomi, ʻo ka nui o ka solubility o ka oxygen he 8.2 mg/L. Hiki i ka hoʻohui ʻana i kahi mea hoʻoheheʻe ikaika ke hoʻonui i ka neʻe o ka oxygen i loko o ka hopena, e hoʻonui nui i ka hana leaching. Eia naʻe, pono e kaulike ka ratio o ka oxygen me ka cyanide; inā ʻaʻole, hiki ke emi ka nui o ka leaching. Hoʻopili ka oxygen i hoʻoheheʻe ʻia me ka cyanide e hana i ka cyanate, ka mea paʻa i nā hopena alkaline. Eia naʻe, ma kahi pH haʻahaʻa ma mua o 7. hydrolyze ia e hana i ka amonia a me ka bicarbonate. Penei na hoohalike pane.

• [1/2 O2 + CN– → (CNO)–]

• [(CNO)– + 2 H2O → HCO3– + NH3]

No laila, hiki i kēia hopena ke alakaʻi i ka ʻai ʻana i ka cyanide i ka wā o ka leaching a i ʻole ka hana electrolysis.

5. Adsorption o ka Cyanide e ka pālolo

I ka wā o ka cyanidation kaʻina hana, ʻo ka hao sulfide i loko o ka ʻaila e hoʻohua i ka hao hydroxide, aʻo nā silicates i loko o ka ʻaila e hana i ka silica colloidal i loko o kahi ʻano alkaline. Loaʻa i kēia mau mea ʻelua ke hiki ke hoʻopili i ka cyanide, e alakaʻi ana i ka nalowale o ka cyanide me ke koena leaching.

6. Ka hoʻohana ʻana i ka cyanide e nā mea ʻē aʻe

(1) Ke hoʻoulu ʻia ka slurry a hoʻopiha ʻia me ka ea, e loaʻa ka CO2 i loko o ka hopena. E hana pū ka CO2 me ka cyanide.

• [2NaCN+CO2+H2O→Na2CO3+2HCN↑]

(2) ʻO nā minela Sulfide e like me ka pyrite i loko o ka ʻeleʻele mua e hana me ka dissolved oxygen (O2) i loko o ka pulp oka, a ʻo nā sulfites a me nā sulfate e hana pū me ka cyanide.

• [FeS+2O2→FeSO4]

• [FeSO4+6NaCN→Na4Fe(CN)6+Na2SO4]

Hiki ke hoʻohui ʻia kahi wahi liʻiliʻi o CaO a i ʻole Ca(OH)2 ma mua o ka leaching e hoʻopau i ka waika a pale i ka hopena o luna.

i ka hopena

ʻO nā mea ma luna nei nā ʻano 6 o ka hoʻohana ʻana i ka cyanide i ke kaʻina hana cyanidation gula. Ma waho aʻe o ka cyanide i koi ʻia no ka hoʻoheheʻe maʻamau o ke gula, nui nā mea hoʻohana pono ʻole, e like me kā mākou pane ʻana me nā mineral e pili ana, self-hydrolysis, etc. 

Inā he mau nīnau kāu e pili ana i ka ʻike ma luna, a makemake ʻoe e ʻike i ka , hiki iā ʻoe ke nīnau i ka lawelawe mea kūʻai aku ma ka pūnaewele a i ʻole e hoʻouna i kahi leka, e hoʻopili koke mākou iā ʻoe!