A method for improving the vanadium yield of vanadium slag sodium roasting process for extracting vanadium

Abstract

The invention discloses a method for improving vanadium yield in a vanadium extraction process via sodium salt roasting of vanadium slag. The method comprises the following process steps: (1) ball milling-leaching: mixing vanadium slag with sodium salt, carrying out sodium salt roasting to obtain roasting clinker, adding liquid caustic soda or high-alkalinity vanadium liquid into the roasting clinker, and ball milling and crushing the materials in a ball mill to obtain crushed slag slurry; (2) thickening-leaching: conveying the crushed slag slurry into a thickening pond, adding liquid caustic soda, and thickening and leaching to obtain thick leachate; (3) washing tailings: pumping the thick leachate into a horizontal filter for filtering to obtain leaching residues and eluate, and the eluate can be used as the high alkalinity vanadium liquid. Since the method of increasing the alkali concentration in the vanadium liquid to leach for extracting vanadium is adopted in the invention, the pH value of the eluate is increased, the solubility of silicon in the vanadium liquid is improved, the formation of silica gel is reduced, the vanadium content in the vanadium mud without silicon is lowered, the loss of the vanadium liquid is reduced, and compared with the existing process, the vanadium recovery is improved by 5-10% and is higher than 90%.

Description

technical field [0001] The invention belongs to the technical field of vanadium chemical industry and metallurgy, in particular to a method for improving the yield of vanadium in the vanadium extraction process by sodium roasting of vanadium slag. Background technique [0002] Vanadium slag is a kind of vanadium-enriched material blown from vanadium-containing molten iron in the presence of oxygen-containing gas. Vanadium slag produced from vanadium titanomagnetite in the iron and steel industry is the main raw material for vanadium extraction. Enterprises that use vanadium titanomagnetite as raw materials to produce iron and vanadium products currently use the traditional vanadium slag sodium roasting process to extract vanadium from vanadium slag, such as my country's Pangang and Chenggang, South Africa's Highveld, New Zealand's steel company etc. The basic principle of sodium roasting is based on Na 2 CO 3 As an additive, the low-valent vanadium is converted into the so...

AI Technical Summary

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 85%; 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

[0003] Chinese patent 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 suitable for high-silicon and low-vanadium vanadium slag, and the roasting temperature is 700 ~820°C, multi-temperature stage roasting, by controlling the temperature system and salt ratio, it can prevent the furnace material 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%; Chinese patents CN1884597A, CN86108218A, etc. have made different improvements to the additives and temperature systems of the sodium roasting process, and the basic principle is to use different ratios of additives (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 inevitable to produce toxic and harmful Gas, low recovery rate of vanadium, etc.

[0004] To sum up, in the prior art, the process of vanadium extraction from vanadium slag generally has high roasting temperature, low vanadium conversion rate and recovery rate, and there are problems such as toxic gas and a large amount of acidic ammonia nitrogen wastewater discharge in the process of vanadium recovery.

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