137 results about "Calcium concentration" patented technology

The invention relates to a method used for directly precipitating vanadium from an acid multi-impurity vanadium-containing solution. According to the technical scheme, the method includes the steps that an oxidizing agent is added into the vanadium-containing solution at first, oxidation is performed, and accordingly an oxidized vanadium solution is obtained; the addition amount of the oxidizing agent accounts for 1.0-2.5 times of the theoretical molar weight of an oxidizing agent required when low valent vanadium in the vanadium-containing solution is completely oxidized into pentavalent vanadium; then urea is added into the oxidized vanadium solution to be stirred according to the mass ratio of the urea to vanadium pentoxide in the oxidized vanadium solution being (3-20):1, solid-liquid separation is performed, and accordingly ammonium polyvanadate and vanadium precipitation mother liquor can be obtained; and afterwards, the ammonium polyvanadate is calcined for 0.5-3.0h at the temperature condition of 450-650 DEG C, and accordingly the vanadium pentoxide can be obtained. According to the chemical composition of the vanadium-containing solution, the vanadium concentration is larger than 6g/L, the aluminum concentration is smaller than 20g/L, the ferrum concentration is smaller than 1.0g/L, the sodium concentration is smaller than 30g/L, the potassium concentration is smaller than 2.0g/L, and the calcium concentration is smaller than 1.0g/L. The pH value of the vanadium-containing solution is smaller than 0.5. The method has the advantages that the technological process is short, the vanadium precipitating rate is high and the purity of the vanadium pentoxide product is also high.