Calcification roasting process for extracting vanadium pentoxide

First, the 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.

Second, the 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.