The Perfect Solvent Extraction Process Needs The Right Agitator

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When it comes to solvent extraction, how many times have you heard, “Too much mixing can cause surface air entrainment!” Or, “Too little mixing can cause phase separation!” 

We understand selecting the correct combination of power, speed and impeller type could mean the difference between an effective mixer settler and an under-performing system. 

Our in-house design program gives us insight into the performance of dozens of impeller types and geometries, meaning, we can help you select the right mixer agitator for your solvent extraction job.

The Sepro SX pumper produces a combination of head and flow to ensure adequate solution-mixing and effective transfer straight from the pump box.  Let us take care of the fine-tuning; we can make sure your solvent extraction pump mixer and auxiliaries are set up for optimum performance.

The Finer Details

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Agitator Components

Agitator Shafts

Shafts are manufactured to a stringent straightness tolerance of 1mm/metre of shaft length. Often, half of this limit is achieved with our standard agitator shafts. Ears are attached to circular hubs using deep penetrating continuous welds, which are systematically dye penned. Ears are never attached directly to hollow shafts. Hubs and ears are machined using CNC machines to minimise clearances between ear and hub; this ensures weld strength.

Mounting Bases

Mounting bases are critical components in ensuring gearboxes are correctly aligned and mounted to the beams or structure. This reduces the potential for twisting or flexing of the gearbox housing — a common cause of failure of proprietary gearboxes. All large, top entry Sepro Mixing agitators are fitted with integral mounting bases, or pedestals where necessary. All bases have machined pads, at the top and bottom, to ensure accurate and positive alignment

Large Sepro Mixing Impeller Blades

Impeller Blades

Sepro Mixing manufactures impellers for all applications, including high viscosity duty. However, as most applications are either flow or shear dependent, the Sepro Mixing CHF range of high flow impellers, or the Sepro Mixing CHG range of high efficiency gas dispersers, are the workhorses of the Sepro Mixing stable. Other impellers available are flat blade radials, pitch blade turbines, high viscosity anchors and helical impellers. We also build specialized impellers for pumping, foam breaking dispersion and Solvent Extraction.

Impellers can be manufactured in all materials, including exotics. They can  be supplied coated in rubber, urethane, epoxy or other specialized materials. Impeller blades are carefully checked to ensure that tolerances on angle, camber and curve are maintained. Out-of-spec blades are rejected. Blades are machined where hub and ear attach to ensure flatness. Often, the problem of loose blades is caused by blade flexing, resulting from a lack of flatness and poor contact with the hub ears.

Impeller blades in excess of 2″ thick and 21ft in diameter have been manufactured by Sepro Mixing in Canada.

CANAMIX SX Pump Mixers

The CANAMIX pump mixer for the SX settler incorporates a radial flow pumper impeller, with either flat or curved blades. The blade width is selected according to the head/flow requirements of the process. Dependent on the geometry of the pump box, an upper auxiliary impeller can be fitted to the shaft to improve mixing and, in many cases, reduce power requirements.

The system’s design requires an inlet orifice that’s matched to the impeller diameter to ensure optimum performance and maximized efficiency.

The clearance between the bottom of the pumper impeller and the separation plate is critical. The clearance can be as small as 12mm (1/2”). Accordingly, minimum shaft deflection is advisable. For this reason, CANAMIX SX pumper mixers use drives with extended bearing housings to ensure that deflection is not an issue.

CANAMIX Auxiliary Mixers for SX Settlers

Where a secondary mix box is required on a mixer settler system, usually to improve initial mixing prior to the settling chamber, CANAMIX mixers use dual or triple aerofoil combinations dependent on tank geometry. These impellers are always up pumping to eliminate air entrainment.

The CANAMIX CHFU aerofoil impeller, used on the Secondary tanks, is a version of the successful CHF322 aerofoil impeller used in hundreds of mixing applications. Its low power, high flow characteristics make it ideal for use in Secondary mix boxes on SX settler systems.

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