High calcium quicklime fines (CaO) are delivered to the plant by pneumatic tanker and blown into our 200 ton silo. We presently receive our product from Carmeuse Lime’s  Northern Lime facility in Blind River, Ontario, approximately 150 kilometers west of Sudbury.

The quicklime is conveyed by two screw conveyors in series into the plant and metered by a variable speed drive into the top of mixing bowl arrangement on top of the Vertimill Slaking System. Speed of the conveyor is controlled by the plant’s Programmable Logic Controller (PLC) and adjusted to maintain the desired temperature in the Slaker.  The fine lime is mixed at this point with fresh potable water and the resulting paste is guided into the top of the mill by rotating paddles attached to the top of the Vertimill screw shaft. The huge screw, which is driven by a 100 HP motor located on top of the Vertimill, forces t he lime paste down and into the grinding media at the bottom of the mill. This media is comprised of small steel balls, 1inch in diameter or smaller. The stirred grinding action pulverizes the quicklime fines and grit, while the finer material rises to the top of the mill and overflows through a launder into the Recycle Tank. This tank is a large cone shaped vessel that is separated by a centre partition. The product is forced under this partition and the lighter (finer) material is allowed to rise to an overflow standpipe on the other side.  The heavier material is pulled out of the recycle tank by a centrifugal pump and injected back into the bottom of the Vertimill for further processing. This recycle flow also helps fluidize the grinding media to promote better grinding.

The finer product overflowing the Recycle Tank stand pipe flows by gravity into a tank pump on the ground floor of the plant. The product is pumped back up to the top of the plant and into a cyclone, where the product is further classified and oversized material is removed and sent back to the top of the Vertimill. The cyclone overflow is allowed to flow by gravity into either of the two, 65,000 gallon product storage tanks, depending on the tank level control setpoint.

When both product tanks are full, the plant’s PLC begins a systematic shutdown of the slaking system. The slaker will remain in a Standby mode until enough room becomes available in the storage tanks again to allow sufficient run time for the mill, usually between 3 to 4 hours minimum. During the standby mode, the product density is lightened considerably and the Vertimill screw is started every hour for a few minutes to keep the grinding media fluid.

The final product is delivered to the client by means of specially equipped pneumatic tankers that can carry a net capacity of between 39 to 43 tons. A client destination code is entered into a remote PanelView HMI (Human Machine Interface) at the truck loading station by the driver and the plant PLC adjusts the amount to be dispensed accordingly. Each load is metered using sophisticated plant instrumentation that measures both flowrate and product density. The PLC also uses this information to calculate the amount of quicklime that is in the slurry for billing purposes.