The preparations before a flotation test include the following:

(1) Sample preparation. The particle size for flotation tests is generally required to be less than 1-3 mm, so the collected samples must be crushed. Usually, a jaw crusher is used to crush the sample to a particle size of about 6.5 mm, and then a double-roll mill and vibrating screen are used for closed-circuit crushing to the particle size required for the flotation test. This particle size ensures the representativeness of the sample and is suitable for the feed particle size of the grinding mill used in the flotation test. Then, the sample is mixed evenly and uniformly divided into single samples of 500-1000 g (up to 3000 g for some low-grade rare metal ores) for testing.

During sample preparation, it is important to prevent sample contamination and avoid the mixing of machine oil and other materials. For sulfide ores, oxidation must be prevented, and it is best to conduct the test immediately after the sample is prepared. If the sample needs to be stored, it should be stored at a relatively coarse particle size (6~25mm). Before the test, it should be crushed to the required particle size to reduce the impact of oxidation.

(2) Preparation of flotation reagents. The quantity of reagents prepared before the test should meet the requirements of the entire test. Reagents should be stored in a dry, cool place. For reagents that are easily decomposed and oxidized, such as xanthate and sodium sulfide, they should be stored in a desiccator. Before using the reagent, it must be checked whether it has deteriorated, and the source of the reagent must be understood.

(3) Preparation of grinding mills. The laboratory should have several grinding mills of different sizes (such as cylindrical grinding mills of φ200mm×200mm, φ160mm×180mm, and φ100mm×150mm), which can be used to grind samples of 500~1000g, 200~500g, and 100~250g respectively. A φ240mm×200mm conical grinding mill can grind 2000~3000g samples. It is best to also have a ceramic ball mill in the laboratory; this type of ball mill can be used if the experiment requires avoiding iron contamination. For grinding mills that have not been used for a long time, rust should be removed before the experiment by grinding with quartz sand or the mineral sample being studied. Before use, the mill can be run empty for a while to remove rust before grinding the sample. After grinding, it must be filled with clean water and covered to prevent oxidation.

(4) Preparation of the flotation machine. Laboratory flotation machines are basically small-sized mechanically agitated flotation machines. Single-cell flotation machines are available in five sizes: 0.5L, 0.75L, 1.0L, 1.5L, and 3.0L. Hanging-cell flotation machines use suspended plexiglass tanks, with sizes ranging from 5~35g to a maximum of 2000g.

(5) Water selection for flotation. Generally, laboratories use local tap water for experiments. After determining the main process conditions, they then verify the results using water sources that may be used in future ore processing plants. When fatty acids are used as collectors, hard water sometimes needs to be softened to eliminate the adverse effects of calcium and magnesium ions on flotation.

(6) In addition to the main preparatory work mentioned above, all instruments and tools used in flotation experiments, such as stopwatches, pH meters, graduated cylinders, pipettes, syringes and needles, wash bottles, medicine bottles, and sample containers of various sizes, must be prepared in advance and thoroughly cleaned.