Code 1741 applies to employers engaged in grinding silica or minerals, or stones that have a high free silica content, to a fine powder. 

For the purpose of this interpretation, the term “free silica” means pure silica or contains more than 5% pure silica content. 

Bulk minerals or stones are first crushed into chunks using conveyor type crushing equipment enclosed to prevent exposure to dust.  The chunks are then pulverized in enclosed grinding mills and screened to size.  They may also be washed to remove impurities or ground while wet and then dried.

This classification is also used for all types of sandblasting work except outside surfaces of buildings or structures where work is done using scaffolds or hoisting devices.

Sandblasting of small items, such as casting or parts, in an employer’s shop, can be cleaned to remove burrs or rust in sandblasting booths using sand to abrade and clean the surface of these items.  Sandblasting at the customer’s premises is done using portable equipment to clean items such as tanks, machinery, equipment and the inside of building surfaces.  In addition to sand, glass bead or steel shot can be used in the abrasive mixture.