Рубрика: The History of Grinding

The Science and the Scientists

THE ROLE OF SCIENCE Scientists and inventors have long worked to develop and improve size-reduction pro­cesses and machines to solve the engineering challenges associated with grinding. Size reduction-used in every mineral-processing operation—has been a continuing field for scientific inquiry and this has contributed to more efficient size-reduction processes in a number of areas: ■ The […]

Manual Crushing

The second stage of size reduction in mining was manual crushing of mined rocks to sizes suitable for direct use or further breakage (see Figure 3.16). Manual crushing was widely used until the end of the 19th century and is still used in many regions of the world. By 1900, the nomenclature for hand crushing […]

Impact Crushers

In these types of crushers, high-velocity impacts are used to break rocks. They work either by hitting rocks with a high-speed hammer (hammer mills) or throwing rocks against each other or against a steel plate (Barmac crusher). Breakage by impact was the FIGURE 5.17 Material flows through the crushing chamber of a cone crusher (SME-AIME […]

Ball Loadings

Balls used in the first compartment are larger than those in the second because much larger particles must be broken. Sizing distributions vary according to clinker character­istics and whether the mill is in open or closed circuit. Some clinkers contain small, hard nodules about 10-15 mm in size that grind slowly and may enter the […]

Horizontal Disk Mills

The improvement in grinding efficiency in a conventional stirred mill, as the media became smaller, led to sand with a particle size of 0.5-0.9 mm being used as the media and the shaft speed increasing from 1,700 to 2,200 rpm. This highlighted the importance of stir­rer design to ensure that there was a uniform energy […]

Initiation of Explosions

Reliable initiation of the explosive decomposition of nitroglycerin was a problem from the start. Black powder safety fuses were tested but gave erratic results, so Nobel returned to a detonator that he had patented in 1867 before dynamite was invented. This was a tin capsule containing mercury fulminate that exploded when struck, and when used […]