Minerals contain chemical compositions that are useful to many different industries. Typically their properties can be economically extracted using crushing and grinding processes. Minerals are used to make a wide variety of mixes, powders, slurries, and solids.

Coarse crushing falls into three categories.

Jaw Crushing

• Largest raw feed handler: 24″ Pennsylvania Jaw Crusher
• When material is too large to process through the jaw crusher, a pre-crush is done using a ram hammer
• Raw feed is no larger than 8 inches or less
• The Jaw crusher reduces feed to approximately ¾″ X down
• Material then is placed on a conveyor belt and fed to a large rotary kiln dryer.

Drying

• The dryer is either used to drive off unwanted moisture or to heat the materials before crushing.
• From the dryer, material goes into a bucket elevator and is taken vertically over an impactor which is similar to a hammer mill.

Impact Crushing

• From the dryer material goes into a bucket elevator and is taken vertically over an impactor which is similar to a hammer mill.
• The material can further be sized based on how many times and how fast the impact hammers strike the material.
• Pennsylvania Reversible Impactor - a set of three hammers that smash material between the hammers and breaker blocks.
• “Sledge Hammer” action with three different speeds
• Size reduction: Typical range is ½″ to below 30 mesh

Screening

• Material exiting the impactor is then taken vertically up into a screener deck via bucket elevator.
• Typically, two screens are used to capture material between a large screen and a smaller screen. Over sized material is sent to a roll crusher and them back to the impactor. Undersized material is often kept separate from screen size or customers ask for a Mesh meaning the customer wants a size no bigger than a specification but the material can be as small as it is made.

Roll Crushing

• 18" × 30" Roll Crusher
• The roll crusher will reduce oversize material and then send the material back through the Impactor for further crushing.

Today there are many companies include a full range of particle size reduction options, from crushing to pulverizing to ultra fine micronizing and media milling.

Linda Dunkelberger is a freelance writer and editor.Custom Processing Services, in Reading and East Greenville, Pennsylvania, is a contract manufacturer (toll processor) offering ultra-fine micronizing, grinding, pulverizing, blending just to name a few.