Paste Thickeners are meant to achieve the highest solids concentrations possible through gravity separation. The resulting mud, or paste, is often so dense that no further separation of water and solids can be achieved. Pastes are then moved to impoundment structures or processed further through Filter Presses.
Because of the high percentage of solids in the resulting space, producers are able to greatly reduce, and sometimes eliminate, impoundment size and volume. They are also able to eliminate free standing water or ponds. Not only does this create a safer working environment, but it also helps with permitting and regulatory requirements.
One benefit of using a Paste Thickener is that it is capable of processing high volumes of fines. Fed from the top, they originally rely on the process of free-settling. After the fines reach a certain point in the process they continue to thicken through hindered settling. Pickets, or rakes, rotate slowly in Paste Thickeners to create channels in the mud to release water.
McLanahan has provided Paste Thickeners without pickets or rakes in operations where producers are not overly worried about mud density, but instead want to process high volumes of fines for water management.
Operation of McLanahan Thickeners has been engineered for simplicity. Each system includes point level pressure sensors to accurately track sludge level and density. PLCs run the system and log data such as feed rate, pH, sludge level and solids concentration. Hydraulic drives are able to give excellent indication of torque on pickets, and underflow discharge may be set to activate based on sludge density, downstream demand, sludge level or simple timers.
For decades, workers at Stevens Creek Quarry dreaded the monthly need to drain and clean out the quarry’s settling pond for its excess slurry tailings. Every 30 to 45 days, the entire operation had to shut down for up to eight days while the pond was cleaned, costing up to $80,000 each cleaning. READ MORE