Lignite-free sand for mix production is becoming more difficult for producers to find as sand deposits around metro areas become depleted. Many producers face the prospect of hauling sand from pits far from their plants, incurring higher costs.
In response, many producers are purchasing specialized machines that remove lignite from the fine and course aggregate in an effort to control costs and quality. Lignite is a generic name for coals and coal-like material found in varying concentrations in sands mined from river deposits. When sand containing lignite is used in concrete, small, dark-colored popouts are likely.
To pick the proper machine to remove lignite, concrete producers need to determine the type of sand they receive. Lignite concentration can vary due to spring melt water, so producers should monitor sand deposits before making a selection.