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The term mineral particle is loosely used in mineral processing. Particles in a mineral processing plant are never a single size but consist of many different sizes. The particles are also many different shapes which makes characterization of the quantity, size, very difficult. Unless a particle is spherical or cubic its size determination is never an absolute process.

There are many ways the size of an irregular particle could be characterised, with none being absolutely right. For instance, the particle size can be characterized by determining the size of hole or aperture the particle will just pass through (sieve size), or the time the particle takes to settle in a fluid such as water and express the particle size as the size of a sphere that has the same settling rate (Stokes diameter). Particle size could also be expressed as the diameter of a circle that has the same cross sectional area or projected area as the particle, when placed either on its most stable position or randomly oriented positions. In three dimensions, the equivalent volume or surface area of a sphere has also been used to describe a particle size. Visual examination under the optical microscope or electron microscope or the diffraction of a laser beam has been used to derive statistical dimensions of particles. All of these methods do not necessarily give the same measure of size for the same sample of particles. Hence it is necessary to mention the measurement method when quoting particle size.

The particle dimensions measured by optical methods are limited to sizes greater than 100. With an electron microscope, particle sizes down to 0.001 micrometer can be measured. For gravity sedimentation methods, the particle size should be greater than 1 micron.sand maker:http://www.hx-crusher.com/
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Where individual measurements are not required approximate size ranges can be obtained by sieving. The closer the successive sieve sizes are, the closer is the approximation to the real size of the particles held between successive sieves. This information is usually sufficient for most metallurgists and sieving is the most common method of determining size.

The use of a microscope to measure the size of irregularly shaped mineral particles can be a tedious and difficult process. A video camera linked to a computer can speed up the process of size recognition by the projected outline of a particle. Video systems are used to size large lumps of rock on conveyor belts and even on the back of dump trucks as the load is tipped into crusher feed bins. The obvious technique is to measure the average distance between two extremities of the particle and the arithmetic or geometric mean of a number of measurements taken.  With its high quality products such as hammer crusher, Raymond mill, Hongxing Machinery has ascended in the front rank of the world in the exporting of mining equipment. The extremities of the distance to be measured is standardized and taken as the mean cord length of the projected outline as defined by Martin’s or Feret’s diameter. Martin’s diameter is the length of the line bisecting the image of the particle. The bisecting line is taken parallel to a fixed direction, irrespective of the orientation of the particle.