Manual Methods in Separating Mixtures

Handpicking

Basic method of separating substances. It involves picking out substances by hand and separating them from others. It is a manual process and used when the components of the mixture to be separated are large and easily distinguished.

Threshing

is the process of separating grains from the stalks. It involves beating the dry stalks to shake off the dried grains. Traditionally, it was done by hand. However, machines are used nowadays to separate large quantities quickly.

Winnowing

This technique is often carried out following threshing. It is the separation of the heavier particles from the lighter particles using wind or moving air. The wind then blows the lighter particles away, and the heavier grains are caught again in the basket.

Jigging

one of the oldest processes used to separate heavy minerals as well as gold and gemstones from lighter soils and pebbles. Different processes rely on differences in density of the materials to be separated. The force of the water separates the light and heavy fragments. The lighter fragments rise to the top and are washed away while the heavier ones sink to the bottom.

Panning

a simpler process in which the rock or soil mixture is placed in a shallow tray and then swirled in water. The lighter material floats away and the heavier particles remain in the tray.

Filtering

a separation technique that relies on the size differences of the particles to be separated. The important thing to remember is that the holes in the filter must be smaller in size than the particles of the solid substance being separated. Generally used when the mixture contains a solid and a liquid.

Sieving

a separation technique similar to filtering but of two solids, one made of big bits and one of smaller bits.

Sedimentation

the process in which insoluble heavy particles in a liquid are allowed to settle to the bottom of the container.

Sediment

the layer formed in sedimentation at the bottom of the container.

Decantation

the process by which a clear liquid obtained after sedimentation is transferred into another container withou disturbing the settled particles (sediments).

Magnetism

used to separate mixtures of two solids with one component having magnetic properties.

Iron, nickel, and cobalt

with magnetic properties

Gold, silver, and aluminum

without magnetic properties