Method for cleaner production of sodium vanadate and sodium chromate by pressure leaching of vanadium slag

Abstract

The invention relates to a method for cleaner production of sodium vanadate and sodium chromate by pressure leaching of vanadium slag. The method comprises the following steps of: (1) mixing materials, namely mixing the vanadium slag and a solution of NaOH to obtain a reaction material; (2) reacting, namely performing oxidization reaction on the vanadium slag and oxidizing gas in the solution of NaOH under high pressure to obtain solid-liquid mixed slurry of a solution containing NaOH, Na3VO4, Na2CrO4 and water-soluble impurity components, and iron-rich tailings; (3) performing solid-liquid separation; (4) removing impurities; (5) crystallizing sodium vanadate; and (6) crystallizing sodium chromate. The method is easy to operate and is high in safety; and the operating temperature is greatly lower than the temperature of the traditional vanadium extraction process, energy consumption is low, the high-efficiency co-extraction of vanadium and chromium is realized, and the extraction rate of vanadium and chromium is over 95 percent.

Description

technical field [0001] The invention relates to the fields of vanadium slag hydrometallurgy and vanadium chemical industry, in particular to a method for producing sodium vanadate and sodium chromate through pressure leaching of vanadium slag. Background technique [0002] Vanadium slag is a vanadium-enriched material produced by blowing vanadium-containing molten iron in the presence of oxygen-containing gas. In the iron and steel industry, vanadium slag produced from vanadium-titanium magnetite is the main raw material for vanadium extraction. The composition of vanadium slag is related to the production method and the composition of vanadium-titanium magnetite. Generally speaking, vanadium slag is composed of V 2 o 5 , SiO 2 、Al 2 o 3 , MgO, Cr 2 o 3 、TiO 2 , CaO and other components, and the composition of vanadium slag in each factory is also very different, but its phase structure is basically the same, all composed of spinel, olivine, quartz, etc. [0003] Ent...

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Problems solved by technology

The recovery rate of vanadium in the sodium roasting process is low, the recovery rate of vanadium in a single roasting is about 70%, and the recovery rate of vanadium after multiple roasting is only 80%; the roasting temperature is high (750-850 ° C), and multiple roasting is required , high energy consumption; in the roasting process will produce harmful HCl, Cl 2 and other corrosive gases, polluting the environment

[0004] CN101215005A proposes a method for roasting vanadium slag and sodium salt (sodium carbonate, sodium chloride) or potassium salt (potassium carbonate, potassium chloride). This patent is applicable to high silicon and low vanadium vanadium slag, and the roasting temperature is 700-820 ℃, multi-temperature stage roasting, by controlling the temperature system and salt ratio, it can prevent the charge from sintering, make the process go smoothly, and also reduce the roasting holding time, and the V in the tailings 2 o 5 The content can reach 0.5~1%; CN1884597A, CN86108218A etc. all have carried out different improvement to the additive of sodiumization roasting process and temperature system, and basic principle all is by using the additive (Na 2 CO 3 , NaCl, Na 2 SO 4 、Na 2 SO 3 etc.) and different temperature systems to improve and increase the extraction rate of vanadium, roasting time, furnace charge sintering and other indicators, but the above process is basically the same as the traditional sodium roasting principle, operation process, and operating temperature, and it is impossible to avoid excessive roasting temperature. The problem of high traditional craft

[0007] CN102127655A proposes a method for decomposing vanadium slag with NaOH solution under normal pressure. The reaction temperature is 180-260°C. Compared with the roasting process, the temperature of the vanadium extraction process is greatly reduced, the energy consumption is reduced, and the efficiency of vanadium extraction is significantly improved, but the vanadium extraction process cannot be achieved. Chromium co-extraction; CN102127654A proposes a method of using sodium hydroxide molten salt to decompose vanadium-chromium-containing slag, the reaction temperature is 500-600°C, this process can realize vanadium-chromium co-extraction, but the molten salt reaction process temperature is relatively high; CN102127656A proposes A method for liquid-phase oxidative decomposition of vanadium slag is proposed. By using sodium hydroxide and sodium nitrate medium, the process of oxidative decomposition of vanadium slag is strengthened, and the reaction temperature is lower than that of sodium hydroxide molten salt medium. However, sodium nitrate medium is introduced, and subsequent separation The process steps are increased; CN101812588A proposes a method for decomposing vanadium slag with potassium hydroxide solution under normal pressure, reacting at 180-260°C, the temperature is greatly reduced, and co-extraction of vanadium and chromium can be realized. The disadvantage is that the cost of potassium hydroxide medium is relatively high

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