Professional Articles

Roll Press Briquetting Helps Chemical/Mineral Processors to Squeeze More value from Materials, improve Handling

In many chemical and mineral processing industries once money has been invested both in mining (or buying) the raw material and in the equipment and energy needed to prepare it for sale discarding fines will not only waste part of that investment, but might even add cost in transportation and possibly dumping charges. So the question becomes, how can fines be turned into a revenue generating asset? One answer arises in the example of quicklime processing.

When limestone (CaCO3) is calcined in rotary kilns to produce quicklime (CaO), it's not unusual for 10% to 20% of the stone to abrade and emerge from the kiln as quicklime fines (-1/4"). While there are various industrial processes that can use fines, handling and shipping is tricky and dangerous. Due to the highly caustic nature of quicklime, airborne dust easily bums eyes and skin.

Some plants convert leftover quicklime fines into calcium hydroxide - Ca(OH)2 also known as hydrated or water-slaked lime for sale into agricultural applications. For farm uses, hydrated lime fines are preferred over quicklime because they are much easier to handle and favored over raw limestone fines for their higher concentration of calcium and greater solubility. These advantages let hydrated lime act more quickly to reduce the acidity of the soil, and to reduce dependence on chemical fertilizers by helping to free the nitrogen and other natural nutrients from the soil for plant intake.

From the producer's viewpoint, quicklime fines are ideal for this use because they go through hydration much faster than the larger chunks of quicklime, while those larger chunks (typically called "pebble lime") are more readily saleable and more easily handled for steel copper aluminum and magnesium production, water/waste treatment chemical, paper, glass making and flue gas desulfunzation in coal-fired boilers.