Aggregate Terms | Gravel Particle Size | Fineness Modulus

Maybe many new friends have doubts about some basic terms of the industry. Let’s introduce some appellations of aggregate industry briefly to help you better understand and communicate.

In the mining industry, the particle size of gravel is usually between 5mm-31.5mm, and 1-2 / 1-3 gravels are generally collectively referred to as paving gravels. The specific sizes of gravel are as follows:

According to the fineness modulus (MX), the specifications of machine-made sand can be divided into 4 types: coarse, medium, fine and extra fine:

• 1. Coarse Sand: the fineness modulus is 3.7-3.1, and the content of particles larger than 0.5mm exceeds 50% of the total weight, and the average particle size is 1mm-0.5mm.
• 2. Medium Sand: sand with fineness modulus of 3.0-2.3, particle size greater than 0.25 mm and average particle size of 0.5-0.25 mm.
• 3. Fine Sand: the fineness modulus is 2.2-1.6, and the particles with particle size greater than 0.075mm exceed 85% of the total weight, and the average particle size is 0.25mm-0.125mm.
• 4. Ultra Fine Sand: the fineness modulus is 1.5-0.7, and the average particle size is less than 0.25mm.

In addition, the following terms may also be frequently heard to measure the quality of sand:

Mud Content: the content of natural sand, pebble and gravel with particle size less than 75 μm.
Powder Content: the content of particles with the particle size less than 75 μm in the artificial sand.
Methylene Blue (MB value): an index used to determine the adsorption performance of stone powder.
Needle/Flake Particles: needle particles refer to the length of machine-made sand particles is 2.4 times larger than the average particle size; flake particles refer to the thickness is less than 0.4 times of average particle size.