New technology for non-polluting vanadium extraction process

An acid extraction process of vanadium pentoxide

(1) Process

Ore crushing→ball milling→acid leaching→solid-liquid separation→pretreatment→extraction and extraction of vanadium→red vanadium pyrolysis→vanadium pentoxide.

The stone coal vanadium ore is crushed and wet-ball milled to a particle size of -60 mesh, accounting for more than 80%, and then continuously stirred with sulfuric acid, which accounts for 15% of the ore mass. The temperature is 85 ° C, the liquid solid product mass ratio (0.85 to 1): 1, vanadium is four. The valence form is transferred to the solution. After solid-liquid separation, stacking slag, after pretreatment solution to P 204+ TBP + sulphonated coal oil as extraction agent, the half-box 7 countercurrent extraction, followed by 1 ~ 1. 5mol / L sulfuric acid was back extracted 5 A vanadium-containing solution having a mass concentration of 80 to 120 g/L is obtained, and red vanadium (ammonium polyvanadate) is obtained by heating and oxidation precipitation, and red vanadium is heated and decomposed at 550 ° C to obtain vanadium pentoxide.

(2) Process principle and application

Vanadium Vanadium stone coal ore portion of the territory of the Shan County substituted six coordinated mica isomorphous to form trivalent aluminum present in the crystal lattice mica mica formula {K (Al, V) ₂ [AlSi ₃ O ₁₀ ](OH) ₂ }, if vanadium is leached from the mica, the mica structure must be destroyed, so this part of the vanadium is difficult to leach. The mica structure is directly destroyed by acid, that is, under a certain temperature and acidity, hydrogen ions are introduced into the mica lattice to replace A1 ³⁺ , and the ionic radius is changed to release vanadium. Vanadium is oxidized to tetravalent and then dissolved with acid. The reaction formula is:

(V ₂ O ₃ )·x+2H ₂ SO ₄ +1/2O ₂ →

V ₂ O ₂ (SO ₄ ) ₂ +4H ₂ O+x,

V ₂ O ₂ (OH) ₄ +2H ₂ SO ₄ →

V ₂ O ₂ (SO ₄ ) ₂ +4H ₂ O,

The result is a blue vanadium sulphate solution which is subjected to subsequent treatment to obtain a vanadium pentoxide product.

The process has been widely used in more than 10 vanadium processing plants in Shanyang County, Shaanxi Province, with a total yield of 65% to 71% and a production cost of 5.5 to 68,000 yuan/t. Waste from Fe ^2+, Fe ^3+, A1 ³⁺ and other metal ions by oxidation, precipitation, filtration, clarification removed, ammonia nitrogen by adjusting the pH, heating, stripping can remove 90% waste can be recycled; No harmful gases are produced during the production process and there is no pollution to the atmosphere.

2. Process for extracting vanadium pentoxide from salt-free roasting

(1) Process

Ore crushing→drying→ball milling→no salt roasting→acid leaching→solid-liquid separation→pretreatment→extraction stripping→precipitation→red vanadium pyrolysis→vanadium pentoxide.

After crushing, drying and ball milling of stone coal vanadium ore, the particle size of -60 mesh accounts for more than 80%. After calcination at 850-950 °C for 2~4 h, continuous stirring at 85 °C with 15% sulfuric acid ore, liquid solid product mass ratio (1~1.5):1, making vanadium in tetravalent and pentavalent forms. Transfer to the solution. After solid-liquid separation, the slag is stacked, and the solution is subjected to oxidation neutralization pretreatment. The vanadium is extracted by a tank extractor at a level of 3, and the extractant is N235+isoamyl alcohol + sulfonated kerosene, and then back-extracted with NaOH solution at a level of 3 to obtain A vanadium-containing solution having a vanadium mass concentration of 80 to 90 g/L. The solution was heated and stirred with ammonium chloride, and filtered to obtain ammonium metavanadate. The ammonium metavanadate is calcined at 550 ° C to obtain a vanadium pentoxide product.

(2) Process principle and application

Calcination is one of the effective ways to destroy the mineral structure of stone coal vanadium ore. In some areas, the stone coal vanadium ore is calcined at 850-950 °C, which can remove most of the carbonaceous material and destroy the mineral lattice. During the calcination process, oxygen in the air directly oxidizes the trivalent vanadium to acid-soluble tetravalent vanadium and pentavalent vanadium, which can be transferred to the solution by acid leaching.

The salt-free roasting and acid leaching tests are carried out on the stone coal vanadium ore in Hunan Yiyang, Yueyang area and Shangnan County of Shaanxi. The total yield of vanadium is 55%~60%, and the production cost can be controlled at 5.8~70,000 yuan/t. . After the process wastewater is treated, it can be recycled. It does not add any additives during roasting, does not produce exhaust gas that seriously pollutes the environment, and has no pollution to the atmosphere. It is a clean production process.

Third, calcification roasting process for extracting vanadium pentoxide

(1) Process

Stone coal vanadium ore crushing → drying → ball milling → calcium salt ball roasting → acid leaching → solid-liquid separation → extraction back extraction (or ion exchange) → precipitation → ammonium metavanadate pyrolysis → vanadium pentoxide.

The stone coal vanadium ore is crushed, dried and ball milled. The particle size is -80 mesh, accounting for more than 90%. The ball is mixed with limestone or lime. The pellet is calcined at 900-950 °C for 3-4 hours, and 1% to 3% sulfuric acid is used. Secondary intermittent leaching, control liquid solid product mass ratio (2 ~ 3): 1. After liquid-solid separation, the slag is stacked, and the mass concentration of vanadium in the solution is 2 to 4 g/L. The extraction-back extraction process (with the salt-free roasting process) or the ion exchange process may be used to enrich the vanadium from the solution. When using the ion exchange process, the resin can be selected from D290 strong alkaline macroporous anion resin. When the solution pH=2.5, the exchange capacity of D290 resin is 212.3 mg/mL wet resin; when the solution pH is 2~3, the exchange speed is 0. 03～0. 04 mL/(min·mL wet resin), the eluent is 40 g/L NaOH+80 g/L NaCl, the flow rate is 0. 03 ～ 0. 04 mL/(min·mL wet resin), desorption The liquid mean vanadium concentration is 30 to 45 g/L. The pH was adjusted to about 9, the ammonium chloride was added, heated and stirred, allowed to stand, filtered, washed, and the solid was calcined at 550 ° C to obtain a vanadium pentoxide product.

(2) Process principle and application

The calcification roasting of stone coal vanadium ore is to add lime or limestone to the ore in a certain proportion, and after mixing, oxidize and roast, to oxidize vanadium in the ore and form calcium vanadate. The chemical reaction formula is:

V ₂ O ₃ +O ₂₌ V ₂ O ₅

V ₂ O ₅ +CaCO ₃ =Ca(VO ₃ )2CO ₂ ↑

In a 1% to 3% sulfuric acid solution, vanadium is transferred to the solution in the form of vanadic acid, calcium is precipitated as a solution of calcium sulfate and separated from the solution, and the vanadium-containing solution is subjected to a subsequent step to extract vanadium.

The calcification roasting process for extracting vanadium pentoxide is non-polluting. It has been tested in the stone coal vanadium mines in Hunan, Hubei, Chongqing, Guizhou, Gansu, Henan, Xinjiang, Shaanxi and other places, and the plant has been put into operation, with a total yield of 55%~ 70%, the production cost is 5.5 to 68,000 yuan / t. The process uses low acid leaching, and the exchange of residual liquid and vanadium precipitation mother liquor can be recycled. The alkaline washing water of the treated resin is adsorbed and recovered by the 717 resin, and then mixed with the acidic washing water of the treated resin, and discharged after being neutralized by the lime. Limestone has a sulfur-fixing effect during the roasting process. Therefore, the gas generated during the production process is mainly CO ₂ , no harmful gas, and no pollution to the atmosphere.