Proses Rawatan Air Sisa Pengekstrakan Emas Sianida

At preseNt, yang sianidaPengekstrakan emas method is one of the MAin Proses Matanges untuk Peleburan Emas in China. ia kegunaanlarutan sianida untuk mengeluarkan emas from ores, featuring high kadar pemulihan, strong adaptability to ore Hartanah, and the ability to produce gold on - site. Since the first use of sianida solution to leACH gold from ores in 1887. this method has been widely applied until now. However, Pengekstrakan Emas Sianida generates a large amount of toksik and harmful substances, posing a huge threat to the surrounding persekitaran and humans. Therefore, in order to reduce the harm, it is necessary to study the Kaedah rawatan of Pengekstrakan emas sianida membazirair. A large number of researchers have summarized the treatment methods, chemical prinCIPles, and development trends of Sianida - mengandungi air sisa, but most of them only discuss one or two methods. Therefore, this article conducts a detailed analysis of various treatment methods for cyanideperahan emas wastewater currently applied in industri, compares the advantages, disadvantages, and application scenarios of each method, which has certain guiding significance for similar aplikasi sebenarnya pengeluaran.

I. Sources and Bahaya of Cyanide Pengekstrakan Emas Air sisa

The main principle of cyanide Pengekstrakan emasn is that in an aerobic envbesisedang berbohong, natrium sianida reacts with gold to form kompleks emases, which are then dissolved. After that, gold can be extracted by enrichment through activated CarbonAdsorpsi or displaced by zink powder from gold cyanide. At the same time, other Logam berat seperti perak, Tembaga, dan zink also form complexes and dissolve.

. sianida digunakan dalam tindak balas and the complexes produced are all toxic and harmful substances. Natrium sianida is easy to hydrolyze and is a Class 1 sangat toksik substance, with a lethal dose of 0.10g. When Sianida leak into water bodies, it is extremely detrimental to the organisms in the water, and will cause a huge threat to humans and the surrounding envbesiment. Therefore, the treatment of cyanide gold extraction wastewater is of great importance.

II. Kaedah Rawatan Utama untuk Air Sisa Pengekstrakan Emas Sianida

Kaedah Pengklorinan Beralkali

. kaedah pengklorinan alkali is currently one of the most commonly used methods for treatimahg cyanide - containing wastewater from cyanide gold extraction. It mainly uses Klorin - Asasd pengoksidaans to oxidize the sianida in the wastewater under alkali conditions, convertimahg them into non - toxic substances. The cyanide - breaking process of alkaline chlorination is divided into two stages:

The first stage is to oxidize cyanide to cyanate, which is called the “incomplete pengoksidaan” stage. CN⁻ reacts with OCl⁻ to first form CNCl, and then it hydrolyzes to CNO⁻. It should be noted that CNCl is highly volatile and toxic under asidic conditions. Therefore, during operation, the nilai pH must be strictly controlled to be in an keadaan alkali.

The second stage is to further oxidize cyanate to carbon dioxide and nitrogen, which is called the “complete oxidation” stage. During the cyanide - breaking process, the pH value has a great imPACt on the Tindak Balas Pengoksidaan. The pH value of the first - stage oxidation should be controlled at 10 - 11. and the reaction time is 10 - 15 minutes. The pH value of the second - stage oxidation should be controlled at 6.5 - 7.0. and the reaction time is 10 - 15 minutes.

A certain mine uses the alkaline chlorination method to treat the sUPernatant of cyanide tail slurry (with a cyanide content of 200mg/L) and the seepage water from the Pemendapan tank (with a cyanide content of 5mg/L). The pH value is controlled at 10 - 11. and serbuk pemutihan is added at a ratio of 35 - 40 times the cyanide content for mixing and stirring. After sedimentation in a Ketuat, the total cyanide content can be reduced to 0.1mg/L.

The alkaline chlorination method is the most commonly used method for treating cyanide - containing wastewater, and pelunturan powder is the most commonly used chlorine - based Oksida. This method is suitable for treating cyanide gold extraction wastewater with high or low concentrations. It can also remove thiocyanate and cyanide - containing complexes (except for ferrocyanide complexes). The medicament is widely available, the generated waste residue is easy to filter, and the operation is simple. However, the operation envBesiment is relatively harsh when using Pemutihan powder to treat wastewater. Now some enterprises use bMelompat liquid or chlorine dioxide insTEAd, which improves the operation environment to some extent. But toxic gases are generated during the reaction process, and it has a relatively large menghakisness to equipment. The medicament cost and maintenance cost are relatively high.

Ferrous Salt Pengkompleksan kaedah

The ferrous salt complexation method is a treatment method for cyanide gold extraction wastewater that has emerged in recent years. By controlling the reaction pH value at 7 - 8. ferrous ions react with Sianida percuma and some cyanide complexes in the cyanide gold extraction wastewater to form precipitates.

Experiments have shown that generally, adding only Ferus sulfat to treat cyanide gold extraction wastewater cannot make the wastewater meet the discharge standards. Therefore, a general oxidant needs to be added to the treated wastewater for deep - Penyingkiran Sianida. As long as the conditions are well - controlled, the oxidant can be directly added for treatment without separating the precipitate, and the discharge standard can also be achieved. This has positive significance compared with the traditional method of pemisahan first and then treatment.

A certain gold smelter uses the natrium sulfida - ferus sulfat method to treat cyanide - poor liquid. The influent has a cyanide content of 2500mg/L. After treatment, the effluent has a cyanide content of less than 20mg/L, with a removal rate of 99.2%, showing remarkable results. The subsequent deep - treatment uses the natrium metabisulfite - air method to reduce the total cyanide to less than 0.4mg/L.

The ferrous salt complexation method is a newly emerging treatment method, mainly used to treat high - concentration cyanide - containing wastewater. Its process is simple, the one - time investment is small, it is easy to operate, the medicament (mainly ferrous Sulfat) is widely available, inexpensive, and easy to use. However, because the ferrous sulfate solution is acidic, when it is mixed with cyanide gold extraction wastewater, the local area becomes acidic, and there is a possibility of generating gas hidrogen sianida. Moreover, it cannot remove thiocyanate, and the treated wastewater still needs deep treatment to meet the discharge standards.

Natrium Metabisulfite - Air Method

. natrium metabisulfite - air method is developed from the sulfur dioksida - air method. It mainly uses the synergistic effect of natrium metabisulfite and air on the Sianida in the wastewater within a certain pH range, with the catalytic effect of Ion kuprum, to oxidize CN⁻ to CNO⁻.

If the cyanide content in the cyanide - containing wastewater is high, pre - treatment can be carried out first to reduce the total kepekatan sianida to less than 100mg/L. Then, natrium metabisulfite and Kuprum sulfat are added, sufficient air is introduced, and the pH value is controlled (generally controlled at 7 - 8), so that cyanide is oxidized to cyanate, which is then dihidrolisiskan to form bicarbonate ions and Ammonia.

. Natrium metabisulfite - air method is suitable for treating low - concentration cyanide gold extraction wastewater. The dos of the medicament is small, the labor intensity is low, but the upfront investment is relatively large, and equipment such as blowers needs to be added. The Keperluan Jawatan for process indicators are relatively strict, and controlling the pH value is very crucial. tembaga sulfate also needs to be added as a pemangkin. The reaction time is long. If the treatment is not proper, a large amount of ammonium ions will be generated, and the generated slag is not easy to filter. There is a small amount of ammonia gas generated on - site, and it has no effect on removing thiocyanides.

Kaedah Pengoksidaan Hidrogen Peroksida

. hidrogen peroksidaKaedah pengoksidaan is to oxidize cyanides to CNO⁻ under normal temperature, alkaline (pH = 10 - 11) conditions, with Cu²⁺ as a Pemangkin, and then hydrolyze them into non - toxic substances. Complex cyanides (complexes of Cu, Zn, Pb, Ni, Cd) are also dissociated due to the destruction of cyanides in them. Ferroion sianida dan lain-lain DIAvy Ion logam form ferrocyanide complex salts and are removed. Finally, the total Kepekatan Sianida in the treated wastewater can be reduced to less than 0.5mg/L.

This method is suitable for treating low - concentration cyanide - containing wastewater. The Hidrogen peroksida treatment equipment is simple and easy to achieve automatic control. However, the generated cyanate needs to stay for a certain period of time to decompose into CO₂ and NH₃. The disadvantages are that using copper as a catalyst may cause copper in the discharged water to exceed the standard, the bahan mentah cost is relatively high, thiocyanides cannot be oxidized, and ammonium ions are generated. In fact, the wastewater still has a certain keracunan. Lebih-lebih lagi, sejak Hidrogen peroksida is an oxidant, it has large corrosiveness, and there are certain difficulties and dangers in pengangkutan dan gunakan.

Kaedah Pengasidan

When using the acidification method to treat cyanide - poor liquid, its reaction MEChanism is relatively complex, mainly including three proses: the acidification process of cyanide - containing wastewater, the stripping and absorption process of HCN gas, and the neutralization process of the stripped liquid.

(1) Acidification reaction: The cyanide - poor liquid is acidified and purified with acid. The complex cyanides in the poor liquid will form inlarut precipitates such as CuCN, CuSCN, and Zn₂Fe(CN)₆ and be removed, and at the same time, Hidrogen sianida dihasilkan.

(2) Volatilization and absorption reaction: The poor liquid is pre - heated to about 30℃ before acidification. Since the takat didih of HCN is only 26.5℃, it is extremely volatile. Therefore, a packed tower is used as the mass - transfer equipment for the contact between the gas - liquid two - phase in the acidification method, which is easy to achieve the stripping and absorption of HCN.

(3) Neutralization reaction: Lime or liquid alkali is used to menetralkan the acid - stripped residual liquid. The residual HCN molecules in the solution will be converted into the CN⁻ form. The acidification method can recover Natrium Sianida from the cyanide - containing wastewater and realize resource pemulihan. However, it has high requirements for equipment sealing, a relatively large upfront investment, requires high - level operation skills, and equipment maintenance is difficult. There are also certain keselamatanbahayas. The wastewater generated after recovery still needs deep treatment to meet the discharge standards.

elektrolisis kaedah

Kaedah elektrolisis menggunakan tindak balas redoks elektrokimia untuk memusnahkan sianida dalam air sisa. Semasa elektrolisis ion, sianida kehilangan elektron pada anod dan teroksida kepada sianat, karbonat, nitrogen, atau ammonium. Sianat terus teroksida kepada CO₂ dan H₂O. Reaksi utama adalah:

CN⁻ + 2OH⁻ - 2e → CNO⁻ + H₂O (24)

2CN⁻ + 4OH⁻ - 6e → 2CO₂ + N₂ + 2H₂O (25)

Electrolysis experiments using a self - made ceramic - based membawa dioxide electrode rod and a stainless - steel cathode plate have proven that by using the electrolysis method to treat cyanide - containing wastewater, after 2 hours of electrolysis, the CN⁻ concentration can be reduced from 385mg/L to 58mg/L, and the Cu²⁺ concentration can be reduced from 450mg/L to 48mg/L. In addition, Hunan Zhongnan Gold Smelter uses the electrochemical method to treat cyanide gold extraction wastewater, which can reduce the total cyanide from 4g/L to 0.8g/L. The difference from the above is that both the anode and cathode plates are made of iron plates. During the operation process, not only electric energy is consumed, but also the iron plates are consumed.

Kaedah elektrolisis digunakan terutamanya untuk merawat air sisa yang mengandungi sianida berkepekatan tinggi. Peralatan ini menduduki kawasan yang kecil, prosesnya mudah dan mudah dikawal, tetapi ia menggunakan sejumlah besar tenaga elektrik, dan kos operasi lebih tinggi daripada kaedah pengklorinan alkali. Kadar penyingkiran sianida adalah purata, dan ia tidak mempunyai kesan ke atas penyingkiran kompleks sianida.

At present, among the treatment methods for cyanide gold extraction wastewater, the alkaline chlorination method, acidification method, and sodium metabisulfite - air method are widely used. The electrolysis method and ferrous salt complexation method are newly emerging methods that have been successfully applied in industrial treatment. The Hidrogen peroxide oxidation method is mainly an Rawatan Kecemasan method. There are many other treatment methods for treating cyanide gold extraction wastewater, such as natural penulenan method, biological method, membrane pemisahan method, ion - exchange method, dan lain-lain. Walau bagaimanapun, sebagai aplikasi industri, they all have certain limitations and still need continuous improvement.