Deep cone thickeners (also known as deep cone paste thickeners) are mechanical thickeners with a high side wall and a steep feeding throat that has a cone angle slightly steeper than the cone angle of sedimentation tanks. Deep cone thickeners are used mostly for thickening non-Settling solids in liquids. This type of thickener is often used for thickening solids in a wide range of industries such as gasoline refining, petrochemicals, minerals, steel and other metals, glass and paper production, wastewater treatment, and for food and pharmaceutical applications.
Deep cone thickeners are suitable for treating suspensions with high suspended solid concentrations up to around 70-80% by weight and up to 4-5 times the concentration of that which a sedimentation tank could handle. They are equipped with polymer feed or flocculation systems that aid in the formation of bridging flocs and creating a route of solids to accumulate and settle out of the suspension. Deep cone thickeners can handle much higher operating pressures than sedimentation tanks, which means that they can produce higher solids concentrations and therefore achieve higher recovery and higher throughput.
The main structure of the deep cone thickener is the cone-shaped hopper. The shallow bottom section has a steep wall and a deep cone-shaped depth, ensuring that it can hold the feed in suspension and drive it along the slope rather than spilling out into the tank. This allows the deep cone thickener to mechanically mix the feed, sludge, and polymer using the steep cone walls, rather than using a pump or power. The slope is usually between 30 degrees and 45 degrees, so that the theory of sedimentation is based on the ratio of material sinking and the lift generated by the hydraulic head pressure, which is proportional to the slope.
Deep cone thickeners are typically larger than conventional sedimentation tanks and can have a height of up to 35 meters, depending on the process requirements. The feed tank size and depth can also vary, although this is typically determined by the feed characteristics and varying feed rates.
Although deep cone thickeners are suitable for a range of applications, they do have a couple of drawbacks. Firstly, the limited space inside the thickener means that smaller particles may be unable to settle, leading to a reduced recovery rate. Secondly, the steep slope of the cone may put a lot of stress on the materials being processed, leading to abrasion and wear of both the machinery and materials.
