1. Superior solution of hydrochloric acid
The principle of the hydrochloric acid excellent solution method is to strictly control the acid decomposition process conditions, so that the waste of rare earth in hydrochloric acid solution prior to dissolve. Excellent solution method from the oxidation roasting, decomposition and impurity removal, separation and precipitation, precipitation burning 4 parts.
(1) Oxidative roasting: This step is the key of the optimal solution method, which converts rare earth into oxide and iron into Fe2O3 to facilitate the next acid decomposition.
(2) Decomposition and impurity removal: adding a small amount of water into the reactor, adding hydrochloric acid and materials in portions, controlling the rare earth concentration and pH, and prioritizing the rare earths to separate and extract the rare earths; using the P50 to separate the rare earth elements from the chlorinated rare earth solution, Get a single rare earth chloride; Lake burning: the extraction solution into the sedimentation tank, ammonium oxalate precipitating agent was added to give rare earth oxalate or rare earth carbonate precipitation, the rare earth oxide was obtained.
2. Complete solution method
The whole solution method is to use hydrochloric acid as a solvent, the scrap of rare earth elements and iron are all dissolved in an ionic state, and then through iron removal, extraction and separation process to obtain rare earth oxides. The whole solution by the dissolution of the dissolution, removal of iron, extraction and separation, precipitation, burning and other four parts.
(1) leaching and dissolving: the neodymium iron boron scrap sieved directly with concentrated hydrochloric acid dissolved at room temperature, rare earth and iron into ion form, the use of hydrogen peroxide oxidation of Fe2 + to Fe3 +;
(2) Iron removal: the use of N503 extraction of iron;
(3) Extraction and separation: the solution after iron removal uses P507 to extract and separate the rare earth elements to obtain a single rare earth chloride;
(4) Precipitation to obtain a rare earth oxide.
3. sulfate double salt method
Sulfate - double salt method is the use of sulfuric acid as a solvent to dissolve NdFeB waste, and then the solution at a certain temperature and Na2SO4 reaction to generate ammonium sulfate double salt precipitation, the double sulfate precipitation add oxalic acid solution to generate rare earth oxalate Precipitation, obtained by burning rare earth oxide.
Article from NdFeB Industry Network