Purification method of ferrous sulfate as byproduct of titanium dioxide

Abstract

The invention discloses a purification method of ferrous sulfate as a byproduct of titanium dioxide. The ferrous sulfate as the byproduct of the titanium dioxide contains titanium, magnesium and manganese impurity elements. The preparation method comprises the following steps: (1) dissolving the ferrous sulfate as the byproduct of the titanium dioxide with water to obtain a ferrous sulfate solution; (2) adding iron powder into the ferrous sulfate solution obtained in the step (1), heating to 90 DEG C or above, and adding phosphoric acid till the pH value of the solution is up to 3 to 4.5; (3)adding sulfide and fluoride into the solution obtained in the step (2), and stirring; (4) adding a flocculant into the solution obtained in the step (3), and then removing flocculating sediment to obtain a purified ferrous sulfate solution. The impurity element content of the extracted ferrous sulfate can meet the requirement of producing battery grade iron phosphate.

Description

technical field [0001] The invention relates to a method for purifying titanium dioxide by-product ferrous sulfate. Background technique [0002] Titanium dioxide, also known as titanium dioxide, is an important inorganic pigment, and its production processes mainly include sulfuric acid method and chlorination method. Ferrous sulfate is the main by-product of sulfuric acid production of titanium dioxide. Generally, every ton of titanium dioxide produced will produce 3.5-4 tons of by-products of ferrous sulfate heptahydrate. After purification or refining, the by-products can be used to produce magnetic powder, pigments, Raw materials for lithium batteries. [0003] CN1104999A discloses a refining process of titanium dioxide by-product ferrous sulfate, which first dissolves the titanium dioxide by-product with hot water, then adds concentrated sulfuric acid to control the pH value to about 2.0, and then presses 0.5-1% of the weight of ferrous sulfate to Add iron powder, ke...

AI Technical Summary

Problems solved by technology

This refining process has a good removal effect on titanium impurities in the by-product ferrous sulfate, but has limited removal effects on magnesium, manganese, calcium and other impurities.

Moreover, the process is to stop the reaction when the pH value remains constant for about half an hour. At this time, the iron powder is exhausted, and ferrous ions are easily oxidized by air to form iron ions, and iron ions will precipitate when the pH value is about 2.0. produced, so that the loss of ferrous sulfate is more serious

[0004] CN1766005A discloses a method for preparing high-purity iron oxide yellow and iron oxide red from titanium dioxide by-product ferrous sulfate. First, the solution of titanium dioxide by-product ferrous sulfate is at a pH value greater than 1.5 and the temperature is lower than 60°C. Hydrolyze titanium ions to generate metatitanic acid to remove titanium impurities, then adjust the pH value of ferrous sulfate solution to 3-7, oxidize ferrous ions to form flocculent ferric hydroxide, and use the adsorption capacity of flocculent ferric hydroxide to remove impurity ions Flocculation and precipitation to obtain refined ferrous sulfate. The loss of ferrous sulfate in this refining method is also serious, and it is difficult to effectively remove impurities in the form of ions by flocculant adsorption

However, magnesium and zinc are more active metals than iron, and iron cannot be replaced and reduced by the magnesium and zinc plasma in the solution to the corresponding metal element. removal of