1：Experimental Design and Method Selection:

The study involved oxidative roasting of spent Nd-Fe-B magnets followed by leaching with either sulfuric or hydrochloric acid. The effect of acid concentration on the leaching of REEs, B, Fe, and Co was investigated. After leaching, REEs were recovered using oxalate and double-sulfate precipitation methods.

2：Sample Selection and Data Sources:

Spent Nd-Fe-B magnets were used as the raw material. The magnets were cleaned, demagnetized, and comminuted before being subjected to oxidative roasting and leaching experiments.

3：List of Experimental Equipment and Materials:

Equipment included a jaw crusher, ring mill, sieving machine, laser diffraction particle size analyzer, ICP-OES for chemical characterization, TGA for roasting experiments, and XRD for phase identification. Materials included sulfuric and hydrochloric acids, sodium sulfate, and oxalic acid for precipitation.

4：Experimental Procedures and Operational Workflow:

The process involved mechanical pre-treatment of the magnets, oxidative roasting at various temperatures, leaching with different acid concentrations, and precipitation of REEs using oxalate or double-sulfate methods. The efficiency and purity of REE recovery were analyzed.

5：Data Analysis Methods:

The leaching and precipitation efficiencies were calculated based on the concentration of REEs, Fe, Co, and B in the leachates and precipitates, measured using ICP-OES. XRD and SEM were used for phase and morphological analysis of the precipitates.