Our chemistry class had a few days where we did a separation lab. We focused on separation, distillation. filtration, chromatography, and magnetism. My group did a project where we had a mixture of salt, sand, and iron fillings. First, we used a magnet to separate the iron fillings from the sand and salt (magnetism). We went through our mixture multiple times to make sure that we had all the iron we could collect & all the sand & salt was separate from the iron in the original container. From here we took our salt and sand mixture & added warm water to separate them. We knew salt was soluble so that was one way we could separate our mixture. Then we used filtration paper to separate the salt water from the sand (filtration). This caught the sand & let the salt water into another pan where it was its own mixture. We let our sand dry & our iron was separate too. If we wanted to separate and time had allowed we would have followed through with a distillation process to extract the salt from the water. Then we would have completely had 3 separated substances. Obviously, we lost some countable mass due to moving & touching our mixtures, but if this was done in a closed lab none of the mass would be lost because the law of conservation of mass.
A few other techniques that were used by different groups included distillation and separation. Distillation is a process of extracting substances from a mixture (physical). Heat boils water or a mixture & some properties of this mixture are carried over to the other flask through a tube. In the tube it condenses the mixture with cooler air and the newly distilled product is in the receiving flask. Separation is simple. Separation is completely physical change & all that happens is two object such as rocks & sand are moved into two separate piles without much hard work.
These are some different types of techniques to separate mixtures that we worked with in my chemistry class. Hopefully I explained myself well.. if you have any questions just ask. :)