Production method for preparing ferric hydroxide by utilizing ferrite-containing waste water

Abstract

The invention discloses a production method for preparing ferric hydroxide by utilizing ferrite-containing waste water. The production method comprises the following steps: introducing acid waste water into an oxidation pond, and continuously adding a NaClO solution with the concentration of active Cl- being greater than or equal to 5.2% while stirring, so that ferrous ions in the waste water are completely oxidized into ferric ions; introducing the obtained completely-oxidized waste water into a reaction tank, and continuously adding a sodium hydroxide solution while stirring until the pH is equal to 5-6; filtering a solution in the reaction tank to obtain filter residues and a filter liquor; filter-pressing the obtained filter residues in a filter-pressing machine, filtering and washing the filter residues by using a sodium hydroxide solution with the concentration of 0.1 mol/L, and after filtering, filtering the obtained filter residues with water; feeding the obtained filter residues in a dryer for cold air drying to obtain ferric hydroxide fine powder. Ferric hydroxide with higher purity is prepared from the waste water containing the ferrite ions by using a low-cost and environment-friendly sodium hypochlorite oxidizing agent, so that a great deal of disadvantages in a traditional method are avoided.

Description

technical field [0001] The invention relates to a production method for preparing ferric hydroxide by utilizing ferrous salt-containing wastewater. Background technique [0002] Iron hydroxide, which has the chemical formula Fe(OH) 3 , Reddish-brown amorphous powdery solid. Insoluble in water, ethanol and ether, amphoteric but its alkaline is stronger than acidic. The newly prepared ferric hydroxide is easily soluble in inorganic and organic acids, and also soluble in hot concentrated alkali. A very strong oxidizing agent, such as sodium hypochlorite, can oxidize fresh ferric hydroxide to sodium ferrate Na in the +Ⅵ oxidation state in alkaline medium 2 FeO 4 . Ferric hydroxide is easy to decompose when heated, but the reaction is not complete when the temperature is not high, that is, it gradually loses water. In engineering construction, adding iron hydroxide to concrete can significantly improve the waterproof performance and strength of concrete. Ferric hydroxide c...

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Problems solved by technology

Hydroxide precipitation method has low investment, quick effect and easy operation, but the defects in practical application are also very obvious: 1. The precipitant selected by this method has no selectivity to metal ions in the wastewater system; 2. Due to the The pH is extremely low, and the neutralization ability of quicklime is weak, resulting in a large consumption and a large amount of mud production, which is easy to cause secondary pollution; 3. The concentration of zinc and lead ions in the wastewater of steel wire rope factories is high, and they are all amphoteric metals , its hydroxide precipitation range is narrow, and it will dissolve again when the pH is low or high, and it is difficult for the effluent to reach the standard stably. This is exactly what is often found in environmental law enforcement inspections in recent years. Reasons why heavy metal ions still exceed the standard

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